机械毕业设计英文外文翻译305栏板起重装置的结构与设计

附录外文文献原文：The Introduction of cranesA crane is defined as a mechanism for lifting and lowering loads with a hoisting mechanism Shapiro, 1991. Cranes are the most useful and versatile piece of equipment on a vast majority of construction projects. They vary widely in configuration, capacity, mode of operation, intensity of utilization and cost. On a large project, a contractor may have an assortment of cranes for different purposes. Small mobile hydraulic cranes may be used for unloading materials from trucks and for small concrete placement operations, while larger crawler and tower cranes may be used for the erection and removal of forms, the installation of steel reinforcement, the placement of concrete, and the erection of structural steel and precast concrete beams.On many construction sites a crane is needed to lift loads such as concrete skips, reinforcement, and formwork. As the lifting needs of the construction industry have increased and diversified, a large number of general and special purpose cranes have been designed and manufactured. These cranes fall into two categories, those employed in industry and those employed in construction. The most common types of cranes used in construction are mobile, tower, and derrick cranes.1.Mobile cranesA mobile crane is a crane capable of moving under its own power without being restricted to predetermined travel. Mobility is provided by mounting or integrating the crane with trucks or all terrain carriers or rough terrain carriers or by providing crawlers. Truck-mounted cranes have the advantage of being able to move under their own power to the construction site. Additionally, mobile cranes can move about the site, and are often able to do the work of several stationary units.Mobile cranes are used for loading, mounting, carrying large loads and for work performed in the presence of obstacles of various kinds such as power lines and similar technological installations. The essential difficulty is here the swinging of the payload which occurs during working motion and also after the work is completed. This applies particularly to the slewing motion of the crane chassis, for which relatively large angular accelerations and negative accelerations of the chassis are characteristic. Inertia forces together with the centrifugal force and the Carioles force cause the payload to swing as a spherical pendulum. Proper control of the slewing motion of the crane serving to transport a payload to the defined point with simultaneous minimization of the swings when theworking motion is finished plays an important role in the model.Modern mobile cranes include the drive and the control systems. Control systems send the feedback signals from the mechanical structure to the drive systems. In general, they are closed chain mechanisms with flexible members [1].Rotation, load and boom hoisting are fundamental motions the mobile crane. During transfer of the load as well as at the end of the motion process, the motor drive forces, the structure inertia forces, the wind forces and the load inertia forces can result in substantial, undesired oscillations in crane. The structure inertia forces and the load inertia forces can be evaluated with numerical methods, such as the finite element method. However, the drive forces are difficult to describe. During start-up and breaking the output forces of the drive system significantly fluctuate. To reduce the speed variations during start-up and braking the controlled motor must produce torque other than constant [2,3], which in turn affects the performance of the crane.Modern mobile cranes that have been built till today have oft a maximal lifting capacity of 3000 tons and incorporate long booms. Crane structure and drive system must be safe, functionary and as light as possible. For economic and time reasons it is impossible to build prototypes for great cranes. Therefore, it is desirable to determinate the crane dynamic responses with the theoretical calculation.Several published articles on the dynamic responses of mobile crane are available in the open literature. In the mid-seventies Peeken et al. [4] have studied the dynamic forces of a mobile crane during rotation of the boom, using very few degrees of freedom for the dynamic equations and very simply spring-mass system for the crane structure. Later Maczynski et al. [5] studied the load swing of a mobile crane with a four mass-model for the crane structure. Posiadala et al. [6] have researched the lifted load motion with consideration for the change of rotating, booming and load hoisting. However, only the kinematics were studied. Later the influence of the flexibility of the support system on the load motion was investigated by the same author [7]. Recently, Kilicaslan et al. [1] have studied the characteristics of a mobile crane using a flexible multibody dynamics approach. Towarek [16] has concentrated the influence of flexible soil foundation on the dynamic stability of the boom crane. The drive forces, however, in all of those studies were presented by using so called the metho d of ……kinematics forcing‟‟ [6] with assumed velocities or accelerations. In practice this assumption could not comply with the motion during start-up and braking.A detailed and accurate model of a mobile crane can be achieved with the finite element method. Using non-linear finite element theory Gunthner and Kleeberger [9] studied the dynamic responses of lattice mobile cranes. About 2754 beam elements and 80 truss elements were used for modeling of the lattice-boom structure. On this basis a efficient software for mobile crane calculation––NODYA has been developed. However, the influences of the drive systems must be determined by measuring on hoisting of the load[10], or rotating of the crane [11]. This is neither efficient nor convenient for computer simulation of arbitrary crane motions.Studies on the problem of control for the dynamic response of rotary crane are also available. Sato et al. [14], derived a control law so that the transfer a load to a desired position will take place that at the end of the transfer of the swing of the load decays as soon as possible. Gustafsson [15] described a feedback control system for a rotary crane to move a cargo without oscillations and correctly align the cargo at the final position. However, only rigid bodies and elastic joint between the boom and the jib in those studies were considered. The dynamic response of the crane, for this reason, will be global.To improve this situation, a new method for dynamic calculation of mobile cranes will be presented in this paper. In this method, the flexible multibody model of the steel structure will be coupled with the model of the drive systems. In that way the elastic deformation, the rigid body motion of the structure and the dynamic behavior of the drive system can be determined with one integrated model. In this paper this method will be called ……complete dynamic calculation for driven “mechanism”.On the basis of flexible multibody theory and the Lagrangian equations, the system equations for complete dynamic calculation will be established. The drive- and control system will be described as differential equations. The complete system leads to a non-linear system of differential equations. The calculation method has been realized for a hydraulic mobile crane. In addition to the structural elements, the mathematical modeling of hydraulic drive- and control systems is decried. The simulations of crane rotations for arbitrary working conditions will be carried out. As result, a more exact representation of dynamic behavior not only for the crane structure, but also for the drive system will be achieved. Based on the results of these simulations the influences of the accelerations, velocities during start-up and braking of crane motions will be discussed.2.Tower cranesThe tower crane is a crane with a fixed vertical mast that is topped by a rotating boom and equipped with a winch for hoisting and lowering loads (Dickie, 990). Tower cranes are designed for situations which require operation in congested areas. Congestion may arise from the nature of the site or from the nature of the construction project. There is no limitation to the height of a high-rise building that can be constructed with a tower crane. The very high line speeds, up to 304.8 mrmin, available with some models yield good production rates at any height. They provide a considerable horizontal working radius, yet require a small work space on the ground (Chalabi, 1989). Some machines can also operate in winds of up to 72.4 km/h, which is far above mobile crane wind limits.The tower cranes are more economical only for longer term construction operations and higher lifting frequencies. This is because of the fairly extensive planning needed for installation, together with the transportation, erection and dismantling costs.3. Derrick cranesA derrick is a device for raising, lowering, and/or moving loads laterally. The simplest form of the derrick is called a Chicago boom and is usually installed by being mounted to building columns or frames during or after construction (Shapiro and Shapiro, 1991).This derrick arrangement. (i.e., Chicago boom) becomes a guy derrick when it is mounted to a mast and a stiff leg derrick when it is fixed to a frame.The selection of cranes is a central element of the life cycle of the project. Cranes must be selected to satisfy the requirements of the job. An appropriately selected crane contributes to the efficiency, timeliness, and profitability of the project. If the correct crane selection and configuration is not made, cost and safety implications might be created (Hanna, 1994). Decision to select a particular crane depends on many input parameters such as site conditions, cost, safety, and their variability. Many of these parameters are qualitative, and subjective judgments implicit in these terms cannot be directly incorporated into the classical decision making process. One way of selecting crane is achieved using fuzzy logic approach.Cranes are not merely the largest, the most conspicuous, and the most representative equipment of construction sites but also, at various stages of the project, a real “bottleneck” that slows the pace of the construction process. Although the crane can be found standing idle in many instances, yet once it is involved in a particular task ,it becomes an indispensable link in the activity chain, forcing at least two crews(in the loading and the unloading zones) to wait for the service. As analyzed in previous publications [6-8] it is feasible to automate (or, rather, semi-automate) crane navigation in order to achieve higher productivity, better economy, and safe operation. It is necessary to focus on the technical aspects of the conversion of existing crane into large semi-automatic manipulators. By mainly external devices mounted on the crane, it becomes capable of learning, memorizing, and autonomously navigation to reprogrammed targets or through prêt aught paths.The following sections describe various facets of crane automation:First, the necessary components and their technical characteristics are reviewed, along with some selection criteria. These are followed by installation and integration of the new components into an existing crane. Next, the Man –Machine –Interface (MMI) is presented with the different modes of operation it provides. Finally, the highlights of a set of controlled tests are reported followed by conclusions and recommendations.Manual versus automatic operation: The three major degrees of freedom of common tower cranes are illustrated in the picture. In some cases , the crane is mounted on tracks , which provide a fourth degree of freedom , while in other cases the tower is “telescope” or extendable , and /or the “jib” can be raised to a diagonal position. Since these additional degrees of freedom are not used routinely during normal operation but rather are fixed in a certain position for long periods (days or weeks), they are not included in the routineautomatic mode of operation, although their position must be “known” to the control system.外文文献中文翻译：起重机介绍起重机是用来举升机构、抬起或放下货物的器械。

附录 1：外文翻译随车起重装置的结构与设计相对传统的举升机构,该举升机构只采用了液压缸,使液压系统的管路简单,控制方便,液压系统的可靠性高,且安装方便。

上述的分析与计算,为该机构建立了结构与性能等参数间的数学关系。

有关推销与套筒间的摩擦与磨损,套筒导槽角和翻转角度与举升高度的适应性等问题,将有待进一步的分析研究和结构发。

随车起重装置在国外称为随车吊。

本文按国家标准称其为随车起重装置。

一辆安装了随车起重装置的厢式货车在货物运输中, 不仅显示其防雨防尘的专有功能,而且在货物的装卸方面实现了机械化。

1 随车起重装置的发展随车起重装置的发展, 在国外大体上可分为四个时期。

第一代产品产生于本世纪30 年代末, 其特点主要是单缸举升, 而栏板翻转靠手动, 起升质量为500kg 左右, 栏板(又称载物平台) 触地倾角9°～10°。

目前, 这种产品在东南亚、日本仍在使用, 90 年代, 还在美国得到了新的发展。

第二代产品产生于50 年代初的欧洲市场, 在第一代产品的基础上增加了翻转关门油缸。

举升与翻转分别由二个独立油缸实现。

最常见的是四只油缸的型式, 也有双缸的。

起升质量在500 kg 以上, 载物平台触地倾角10°, 翻转动作凭操作者经验控制。

该种产品目前主要用于美洲及东南亚地区。

第三代产品产生于70 年代末的欧洲市场, 是在第二代产品的基础上增加第五只油缸。

这只油缸在液压系统中主要起相对位置的记忆功能, 使载物平台触地、离地的翻转动作不再由操作者控制而由液压系统本身控制, 从而使升降过程相对平稳与安全。

触地倾角一般为8°～10°。

若兼作厢门用, 因平台尺寸增大, 倾角也可能小于8°。

目前该类产品普遍用于欧美地区。

第四代产品产生于90 年代初, 其液压系统及功能原理同第三代产品, 只增加了记忆油缸的尺寸, 使记忆动作的范围进一步增大。

它不同于第三代产品的关键在于其载物平台增加特殊结构, 由一体改为两体活动联接, 使平台触地后不仅能自动翻转, 而且有一个下沉的动作, 使触地倾角达到6°, 甚至在6以下。

起重机中英⽂对照外⽂翻译⽂献中英⽂对照外⽂翻译(⽂档含英⽂原⽂和中⽂翻译)Control of Tower Cranes WithDouble-Pendulum Payload DynamicsAbstract：The usefulness of cranes is limited because the payload is supported by an overhead suspension cable that allows oscilation to occur during crane motion. Under certain conditions, the payload dynamics may introduce an additional oscillatory mode that creates a double pendulum. This paper presents an analysis of this effect on tower cranes. This paper also reviews a command generation technique to suppress the oscillatory dynamics with robustness to frequency changes. Experimental results are presented to verify that the proposed method can improve the ability of crane operators to drive a double-pendulum tower crane. The performance improvements occurred during both local and teleoperated control.Key words：Crane , input shaping , tower crane oscillation , vibrationI. INTRODUCTIONThe study of crane dynamics and advanced control methods has received significant attention. Cranes can roughly be divided into three categories based upontheir primary dynamic properties and the coordinate system that most naturally describes the location of the suspension cable connection point. The first category, bridge cranes, operate in Cartesian space, as shown in Fig. 1(a). The trolley moves along a bridge, whose motion is perpendicular to that of the trolley. Bridge cranes that can travel on a mobile base are often called gantry cranes. Bridge cranes are common in factories, warehouses, and shipyards.The second major category of cranes is boom cranes, such as the one sketched in Fig. 1(b). Boom cranes are best described in spherical coordinates, where a boom rotates aboutaxes both perpendicular and parallel to the ground. In Fig. 1(b), ψis the rotation aboutthe vertical, Z-axis, and θis the rotation about the horizontal, Y -axis. The payload is supported from a suspension cable at the end of the boom. Boom cranes are often placed on a mobile base that allows them to change their workspace.The third major category of cranes is tower cranes, like the one sketched in Fig. 1(c). These are most naturally described by cylindrical coordinates. A horizontal jib arm rotates around a vertical tower. The payload is supported by a cable from the trolley, which moves radially along the jib arm. Tower cranes are commonly used in the construction of multistory buildings and have the advantage of having a small footprint-to-workspace ratio. Primary disadvantages of tower and boom cranes, from a control design viewpoint, are the nonlinear dynamics due to the rotational nature of the cranes, in addition to the less intuitive natural coordinate systems.A common characteristic among all cranes is that the pay- load is supported via an overhead suspension cable. While this provides the hoisting functionality of the crane, it also presents several challenges, the primary of which is payload oscillation. Motion of the crane will often lead to large payload oscillations. These payload oscillations have many detrimental effects including degrading payload positioning accuracy, increasing task completion time, and decreasing safety. A large research effort has been directed at reducing oscillations. An overview of these efforts in crane control, concentrating mainly on feedback methods, is provided in [1]. Some researchers have proposed smooth commands to reduce excitation of system flexible modes [2]–[5]. Crane control methods based on command shaping are reviewed in [6]. Many researchers have focused on feedback methods, which necessitate the addition necessitate the addition of sensors to the crane and can prove difficult to use in conjunction with human operators. For example, some quayside cranes have been equipped with sophisticated feedback control systems to dampen payload sway. However, the motions induced by the computer control annoyed some of the human operators. As a result, the human operators disabled the feedback controllers. Given that the vast majority of cranes are driven by human operators and will never be equipped with computer-based feedback, feedback methods are not considered in this paper.Input shaping [7], [8] is one control method that dramatically reduces payload oscillation by intelligently shaping the commands generated by human operators [9], [10]. Using rough estimates of system natural frequencies and damping ratios, a series of impulses, called the input shaper, is designed. The convolution of the input shaper and the original command is then used to drive the system. This process is demonstrated with atwo-impulse input shaper and a step command in Fig. 2. Note that the rise time of the command is increased by the duration of the input shaper. This small increase in the rise time isnormally on the order of 0.5–1 periods of the dominant vibration mode.Fig. 1. Sketches of (a) bridge crane, (b) boom crane, (c) and tower crane.Fig. 2. Input-shaping process.Input shaping has been successfully implemented on many vibratory systems including bridge [11]–[13], tower [14]–[16], and boom [17], [18] cranes, coordinate measurement machines[19]–[21], robotic arms [8], [22], [23], demining robots [24], and micro-milling machines [25].Most input-shaping techniques are based upon linear system theory. However, some research efforts have examined the extension of input shaping to nonlinear systems [26], [14]. Input shapers that are effective despite system nonlinearities have been developed. These include input shapers for nonlinear actuator dynamics, friction, and dynamic nonlinearities [14], [27]–[31]. One method of dealing with nonlinearities is the use of adaptive or learning input shapers [32]–[34].Despite these efforts, the simplest and most common way to address system nonlinearities is to utilize a robust input shaper [35]. An input shaper that is more robust to changes in system parameters will generally be more robust to system nonlinearities that manifest themselves as changes in the linearized frequencies. In addition to designing robust shapers, input shapers can also be designed to suppress multiple modes of vibration [36]–[38].In Section II, the mobile tower crane used during experimental tests for this paper is presented. In Section III, planar and 3-D models of a tower crane are examined to highlight important dynamic effects. Section IV presents a method to design multimode input shapers with specified levels of robustness. InSection V, these methods are implemented on a tower crane with double-pendulum payload dynamics. Finally, in Section VI, the effect of the robust shapers on human operator performance is presented for both local and teleoperated control.II. MOBILE TOWER CRANEThe mobile tower crane, shown in Fig. 3, has teleoperation capabilities that allow it to be operated in real-time from anywhere in the world via the Internet [15]. The tower portion of the crane, shown in Fig. 3(a), is approximately 2 m tall with a 1 m jib arm. It is actuated by Siemens synchronous, AC servomotors. The jib is capable of 340°rotation about the tower. The trolley moves radially along the jib via a lead screw, and a hoisting motor controls the suspension cable length. Motor encoders are used for PD feedback control of trolley motion in the slewing and radial directions. A Siemens digital camera is mounted to the trolley and records the swing deflection of the hook at a sampling rate of 50 Hz [15].The measurement resolution of the camera depends on the suspension cable length. For the cable lengths used in this research, the resolution is approximately 0.08°. This is equivalent to a 1.4 mm hook displacement at a cable length of 1 m. In this work, the camera is not used for feedback control of the payload oscillation. The experimental results presented in this paper utilize encoder data to describe jib and trolley position and camera data to measure the deflection angles of the hook. Base mobility is provided by DC motors with omnidirectional wheels attached to each support leg, as shown in Fig. 3(b). The base is under PD control using two HiBot SH2-based microcontrollers, with feedback from motor-shaft-mounted encoders. The mobile base was kept stationary during all experiments presented in this paper. Therefore, the mobile tower crane operated as a standard tower crane.Table I summarizes the performance characteristics of the tower crane. It should be noted that most of these limits areenforced via software and are not the physical limitations of the system. These limitations are enforced to more closely match theoperational parameters of full-sized tower cranes.Fig. 3. Mobile, portable tower crane, (a) mobile tower crane, (b) mobile crane base.TABLE I MOBILE TOWER CRANE PERFORMANCE LIMITSFig. 4 Sketch of tower crane with a double-pendulum dynamics.III. TOWER CRANE MODELFig.4 shows a sketch of a tower crane with a double-pendulum payload configuration. The jib rotates by an angle around the vertical axis Z parallelto the tower column. The trolley moves radially along the jib; its position along the jib is described by r . The suspension cable length from the trolley to the hook is represented by an inflexible, massless cable of variable length 1l . The payload is connected to the hook via an inflexible, massless cable of length 2l . Both the hook and the payload are represented as point masses having masses h m and p m , respectively.The angles describing the position of the hook are shown in Fig. 5(a). The angle φrepresents a deflection in the radial direction, along the jib. The angle χ represents a tangential deflection, perpendicular to the jib. In Fig. 5(a), φ is in the plane of the page, and χ lies in a plane out of the page. The angles describing the payload position are shown in Fig. 5(b). Notice that these angles are defined relative to a line from the trolley to the hook. If there is no deflection of the hook, then the angleγ describes radial deflections, along the jib, and the angle α represents deflections perpendicular to the jib, in the tangential direction. The equations of motion for this model were derived using a commercial dynamics package, but they are too complex to show in their entirety here, as they are each over a page in length.To give some insight into the double-pendulum model, the position of the hook and payload within the Newtonian frame XYZ are written as —h q and —p q , respectivelyWhere -I , -J and -K are unit vectors in the X , Y , and Z directions. The Lagrangian may then be written asFig. 5. (a) Angles describing hook motion. (b) Angles describing payload motion.Fig. 6. Experimental and simulated responses of radial motion.(a) Hook responses (φ) for m 48.01=l ，(b) Hook responses for m 28.11=lThe motion of the trolley can be represented in terms of the system inputs. The position of the trolley —tr q in the Newtonian frame is described byThis position, or its derivatives, can be used as the input to any number of models of a spherical double-pendulum. More detailed discussion of the dynamics of spherical double pendulums can be found in [39]–[42].The addition of the second mass and resulting double-pendulum dramatically increases the complexity of the equations of motion beyond the more commonly used single-pendulum tower model [1], [16], [43]–[46]. This fact can been seen in the Lagrangian. In (3), the terms in the square brackets represent those that remain for the single-pendulum model; no —p q terms appear. This significantly reduces the complexity of the equations because —p q is a function of the inputs and all four angles shown in Fig. 5.It should be reiterated that such a complex dynamic model is not used to design the input-shaping controllers presented in later sections. The model was developed as a vehicle to evaluate the proposed control method over a variety of operating conditions and demonstrate its effectiveness. The controller is designed using a much simpler, planar model.A. Experimental V erification of the ModelThe full, nonlinear equations of motion were experimentally verified using several test cases. Fig.6 shows two cases involving only radial motion. The trolley was driven at maximum velocity for a distance of 0.30 m, with 2l =0.45m .The payload mass p m for both cases was 0.15 kg and the hook mass h m was approximately 0.105 kg. The two cases shown in Fig. 6 present extremes of suspension cable lengths 1l . In Fig. 6(a), 1l is 0.48 m , close to the minimum length that can be measured by the overhead camera. At this length, the double-pendulum effect is immediately noticeable. One can see that the experimental and simulated responses closely match. In Fig. 6(b), 1l is 1.28 m, the maximum length possible while keeping the payload from hitting the ground. At this length, the second mode of oscillation has much less effect on the response. The model closely matches the experimental response for this case as well. The responses for a linearized, planar model, which will be developed in Section III-B, are also shown in Fig. 6. The responses from this planar model closely match both the experimental results and the responses of the full, nonlinear model for both suspension cable lengths.Fig. 7. Hook responses to 20°jib rotation:(a) φ (radial) response;(b) χ (tangential) response.Fig. 8. Hook responses to 90°jib rotation:φ(radial) response;(b) χ(tangential) response.(a)If the trolley position is held constant and the jib is rotated, then the rotational and centripetal accelerations cause oscillation in both the radial and tangential directions. This can be seen in the simulation responses from the full nonlinear model in Figs. 7 and 8. In Fig. 7, the trolley is held at a fixed position of r = 0.75 m, while the jib is rotated 20°. This relatively small rotation only slightly excites oscillation in the radial direction, as shown in Fig. 7(a). The vibratory dynamics are dominated byoscillations in the tangential direction, χ, as shown in Fig. 7(b). If, however, a large angular displacement of the jib occurs, then significant oscillation will occur in both the radial and tangential directions, as shown in Fig. 8. In this case, the trolley was fixed at r = 0.75 m and the jib was rotated 90°. Figs. 7 and 8 show that the experimental responses closely match those predicted by the model for these rotational motions. Part of the deviation in Fig. 8(b) can be attributed to the unevenness of the floor on which the crane sits. After the 90°jib rotation the hook and payload oscillate about a slightly different equilibrium point, as measured by the overhead camera.Fig.9.Planardouble-pendulummodel.B.Dynamic AnalysisIf the motion of the tower crane is limited to trolley motion, like the responses shown in Fig. 6, then the model may be simplified to that shown in Fig. 9. This model simplifies the analysis of the system dynamics and provides simple estimates of the two natural frequencies of the double pendulum. These estimates will be used to develop input shapers for the double-pendulum tower crane.The crane is moved by applying a force )(t u to the trolley. A cable of length 1l hangs below the trolley and supports a hook, of mass h m , to which the payload is attached using rigging cables. The rigging and payload are modeled as a second cable, of length 2l and point mass p m . Assuming that the cable and rigging lengths do not change during the motion, the linearized equations of motion, assuming zero initial conditions, arewhere φ and γ describe the angles of the two pendulums, R is the ratio of the payload mass to the hook mass, and g is the acceleration due to gravity.The linearized frequencies of the double-pendulum dynamics modeled in (5) are [47]Where Note that the frequencies depend on the two cable lengths and the mass ratio.Fig. 10. Variation of first and second mode frequencies when m l l 8.121=+.。

本科生毕业设计（论文）翻译资料中文题目：配合新一代液力变矩器的柴油动力线的一些特性英文题目：some properties of a diesel driveline with hydrodynamic torque converters of thelastest generation学生姓名：学号：班级：专业：机械工程及自动化指导教师：吉林大学机械科学与工程学院Some properties of a diesel drive line withhydrodynamic torque converters of the latestgenerationAbstractDynamic properties of a drive line with a controlled Diesel engine, hydrodynamic transmission mechanism, additional gearing and a loading-working machine producing common monoharmonic loading are investigated. Solution of the dynamic problem is based on phenomenological experimental data: drivingtorque-speed characteristic in the part of the prime mover and so-called external static characteristic in the hydrotransmission part. The non-linear task is solved by a modified harmonic balance method that was described in preceding publications by the author.Keywords: Machine drive line; Controlled Diesel drive; Hydrodynamic torque converter; Working machine; Periodic loading; Stationary dynamic stateNomenclature and abbreviationsa, b --- ------Coulomb and viscous non-dimensional friction lossesA i,B i --- ----coefficients in mathematical expression of torque-speed characteristic i, i m ----------kinematic transmission, supplementary gearing transmission ratio -------mean reduced moment of inertia in driving and loading partI, I, k K ---------tangent slopes of λ(i) and K(i) curves respectivelykλK -------------moment transmissionM ------------Diesel-engine momentM D(ω, z) ----controlled torque-speed driving characteristicM Dmax(ω), M Dmin(ω) ---torque-speed characteristic for maximal and minimal fuel supplyM1, (), M2, () ---pump loading moment and turbine driving momentM T1, M T2 ----friction loss moment in driving and loading partM z, M za ----mean value and amplitude of loading moment-------------hydrodynamic converter characteristic radius吉林大学本科毕业论文外文翻译t -------------timeT, T D------------Watt regulator and Diesel-engine time constantu, z ---------gas lever and regulator displacementw -----------common dynamic variableε -----------regulator structural parameterζ -----------regulator damping ratioλ -----------coefficient of rotation momentν -----------loading angular velocity, π-------index denoting mean value and periodical component---------hydraulic medium density----------rotation angleω1, (), ω2 ---pump and turbine angular velocityDM ------Diesel-engineG, G D ---additional and Watt-regulator gearingHdPT ---hydrodynamic power transmissionIJ --------InjectorLM ------loading mechanism (working machine)P, R, T---pump, reactor, turbineArticle OutlineNomenclature1. Introduction2. Mathematical model of the system3. Stationary dynamic solution at monoharmonic loading4. Results evaluation and concluding remarks1. IntroductionDynamic properties of a drive line (actuating unit) consisting of a controlled Diesel engine (DM), hydrodynamic power transmission system (HdPT), additional gearing (G) and a loading mechanism (LM) or working machine are investigated. The working machine loads the prime mover and the transmissions with a prescribed moment. A simple idealised schematic layout of the complete system is given in Fig.1. The considered Diesel engine is a standard production: ZETOR 8002.1 controlled by a mechanical (Watt’s) or electronic regulator R D governing fuel injector IJ. In the place of the hydrodynamic power transmission there are gradually applied hydrodynamic torque converters of the latest generation that have been projected吉林大学机械科学与工程学院and tested in WUSAM (Research and Projecting Institute of Machines and Mechanisms), j.s.c. Zvolen, Slovakia. These converters represent a three component assembly composed of a rotational pump (P), turbine (T) and a reactor (R) that may revolve in one direction as a free wheel. Advantage of these converters is the fact that their external dimensions and the dimensions of their individual components are identical and they may be mutually changed and arbitrarily combined in order to reach demanded properties. They differ only by internal configuration and blade geometry. According to [1] up to now more than 70 various types have been experimentally tested and from them the ones have been chosen that optimally fulfilled required properties. The mechanical system under consideration represents a sophisticated energy transfer chain from a source––prime mover to working mechanism. Because every real drive is of finite power, any periodic loading always evokes vibrations of all the dynamic variables even though we suppose all the connecting shafts and gearings rigid and backlash free. The influence of dynamic loading on the prime mover may be just controlled by a suitable choice of the torque converter.Fig. 1. Schematic layout of the Diesel drive line.In the paper influence of constant and periodic loading on time course of all the dynamic variables of the system (and particularly on the variables of the prime mover) is investigated at application of some selected types of hydrodynamic torque converters of the latest generation. For fulfilling this task it is necessary to create a suitable mathematical model of the whole combined system and then find its stationary solution corresponding to a required loading.2. Mathematical model of the system吉林大学本科毕业论文外文翻译At the beginning it is necessary to emphasize that mathematical modelling of the drive line in question is based, in our approach, on knowledge of the published phenomenological data: stationary torque-speed characteristic of the prime mover and so-called external static characteristic of the applied hydrodynamic torque converter. It is a much simpler process than modelling based on thermodynamic equations of burning fuel mixture in the Diesel engine and on hydrodynamic equations of real streaming working medium in very complicated cavities of the torque converter. The characteristics are usually given by manufacturer of the individual system components. This is different and simpler approach to solution of the problem than one may find e.g. at Ishihara [2], Hrovat and Tobler [3], Kesy and Kesy [4], Laptev [5] and some others. The derived dimensional and non-dimensional mathematical models of the mechanical system are introduced in [6]. Thenon-dimensional, reduced, so-called single-shaft model (in the driving and loading part), was derived in the form of combined system of the following differential and algebraic equations:(1)(2)(3)(4)M2=KM1, (5)λ=λ(i), (6)K=K(i), (7)(8)吉林大学机械科学与工程学院(9) where the meaning of the individual symbols is explained in nomenclature. In the non-dimensional model all the dynamic variables and parameters are expressed by means of properly chosen relative standard quantities so that the model of the system might be the most simple. Transformation of the original equations system to the non-dimensional form Figs. (1), (2), (3), (4), (5), (6), (7), (8) and (9) is described in detail in [6]. As for this cited paper, it is necessary to say that the relative standard value of loading angular frequency has been settled according to the relation, where in denominator is relative standard value of time. For this value,the time constant of the regulator has been just chosen, i.e. , where therelated dimensional dynamic variables are distinguished by upper bars. The introduced mathematical model has nine variables: M, M1, ω1, z, λ, K, i, M2, ω2 and their meaning is explained in nomenclature. The first three equations represent mathematic model of the prime mover where in inertia moment I there is includedinertia moment of the pump and equivalent part of the working medium because driving and pump shafts are connected by a rigid clutch. The right side of Eq. (3) represents the controlled stationary torque-speed characteristic for which it holds: M D(ω1,z)=M Dmax(ω1)-[M Dmax(ω1)-M Dmin(ω1)]z, (10) where M Dmax(ω1), M Dmin(ω1) represent its non-dimensional extreme branches for maximal and minimal fuel supply and z is the non-dimensional regulator deviation.If the experimentally measured dependences M Dmax(ω1), M Dmin(ω1) are expressed by second degree polynomials then the controlled non-dimensional torque-speed characteristic has the form:(11) From the introduced model it is evident that at chosen parameter value u driving speed growth causes regulator displacement to increase and fuel supply to decrease. The idealised controlled torque-speed characteristic for a chosen parameter value u (gas lever displacement) is schematically depicted in Fig. 2. From Eq. (2) it is evident that the structural parameter ε must be chosen in such away that regulator self-oscillations should not occur. Eqs. Figs. (4), (5), (6), (7) and (8), in the sense of considerations in [6], represent the dynamic equations of the torque converter. Eq. (9) represents simplified motion equation of the loading mechanism under assumptiondoes not depend on rotation angle . In thisthat the reduced inertia moment Ireduced inertia moment there is involved inertia moment of the turbine with吉林大学本科毕业论文外文翻译equivalent part of the working medium too. It is obvious that in this inertia moment and in all moments of the loading mechanism there is considered gear ratio i m of the supplementary gearing of the originally non-reduced system. Eqs. Figs. (6) and (7) represent the external static characteristic of the hydrodynamic transmission, i.e. formal dependences of λ and K on the kinematic ratio i and the dependences are given for every converter type in graphical form. The dynamic variables λ and K are defined in non-dimensional form very simply by non-linear relations Figs. (4) and (5). In a general way these non-dimensional variables are defined by means of dimensional values (distinguished by upper bars) as follows:(12) where individual symbol meaning may be found in nomenclature. As we have chosen (according to Fig. 2) for the relative standard value of angular velocity the idle motion angular velocity of the Diesel engine at maximal fuel supply, i.e. at z = 0, then from Figs. (4) and (12) it is evident that the relative standard moment value is(13)It means that if for the applied drive s−1 and all the applied convertertypes have equal characteristic radius m and if we consider mean valuekg m−3 at stationary thermic regime then the relative standard value of themoment is N m for all the considered converter types. The external static characteristics of the applied converters with internal labelling: M350.222,M350.623M, M350.675, M350.72M3M, are (according to the measuring records [7]) successively introduced in Fig. 3(a)–(d). When the torque-speed characteristic is known and the measured dependences Figs. (6) and (7) are at disposal, it is possible to solve the combined system of differential and algebraic equations Figs. (1), (2), (3), (4), (5), (6), (7), (8) and (9). This is a little complicated task because the differential and algebraic equations in the accepted mathematical model arenon-linear. Stationary dynamic state of the system was calculated by a modified harmonic balance method that is fully described in [8].吉林大学机械科学与工程学院Fig. 2. Idealised diagram of the driving torque-speed characteristic.Fig. 3. External static characteristics of the hydrodynamic power transmissions: M350.222,M350.623M, M350.675, M350.72M3M.3. Stationary dynamic solution at monoharmonicloadingIn this section stationary solution of the system Figs. (1), (2), (3), (4), (5), (6), (7), (8) and (9) will be looked for always with the same prime mover and successively considering all the converters types whose external static characteristics are introduced in Fig. 3(a)–(d). If each of the nine dynamic variables is denoted by a common symbol w≡M, M1, ω1, z, λ, K, i, M2, ω2 then, in accordance with applied method, every dynamic variable may be formally expressed as a sum of its mean and its centred periodic component, i.e.:w=w+w π. (14) Following the mentioned method, on restrictive presumption that it holds:MM z→wπw, (15)吉林大学本科毕业论文外文翻译the system Figs. (1), (2), (3), (4), (5), (6), (7), (8) and (9) splits into twoindependent systems of equations: a system of non-linear algebraic equations for calculationw and a combined system of linearised differential and algebraic equations for calculation w π. If one considers that friction losses in the driving part are implicitly expressed already in the torque-speed characteristic of the drive and in the external static characteristic of the applied hydrodynamic torque converter and friction losses in the loading part are supposed as a combination of Coulomb and viscous friction, i.e.:M T 2=a +bω2, (16)then the non-linear algebraic system has the form:(17)The combined system of the linearised differential and algebraic equations is(18)where for writing abbreviation it is denoted:吉林大学机械科学与工程学院(19) The solution process of both equation systems Figs. (17) and (18) is introduced in [8]. The system of non-linear equations (17) was calculated for three parameter levels u (u = 0.3, 0.4, 0.6) that respond to 30%, 40%, and 60% of the maximal gas lever displacement. To each chosen parameter value u, a certain driving angular velocity interval responds. From Fig. 2 and from Eq. (2) it is evident that for a chosen value u the corresponding mean driving angular velocity value must lie in interval:ω1ω1b, (20)ωwhere for border values of the interval it holds:(21) For the chosen parameter value u = 0.3 and for different mean values M z, the calculated mean values w(for the drive line with given drive and all the consideredconverter types) are introduced in diagrams in Fig. 4(a)–(d). Analogical mean values w of the same variables corresponding with the parameter u = 0.4 are in Fig.5(a)–(d). Finally, the calculated mean values w corresponding with parameteru = 0.6 and identical torque converter types are depicted in Fig. 6(a)–(d). Here it is important to remind that x-coordinates in Fig. 4, Fig. 5 and Fig. 6 represent the mean angular velocity interval (20) gradually for parameters u = 0.3, 0.4, 0.6 and the decimal fractions on this section denote only its decimal division. From the calculated mean values w in Fig. 4, Fig. 5 and Fig. 6 and from the introducedexternal static characteristics in Fig. 3a complete nine of the mean values w can be determined for any mean loading value Mand estimated loss moment value M T2in the loading part. When this complete nine w is known then it is possible, in the sense of the applied method, to construct all the constant coefficients of the combined differential and algebraic system (18) for calculation wπ. This system is already linear and may be solved by known classical methods. First of all, we take interest in stationary dynamic solution. In sense of the procedure one may express the centred periodic component of every dynamic variable in the form:wπ=M za(W c cosνt+W s sinνt), (22) where notations W c, W s represent cosine and sine components of the dynamic factor (transmissibility) of corresponding dynamic variable. Detailed computing procedure is introduced in [8]. For transmissibility of the centred periodic component of every dynamic variable it holds:(23)As an example in Fig. 7, Fig. 8, Fig. 9, Fig. 10 and Fig. 11 there are successively introduced dynamic characteristics of the centred periodic components of dynamic variables: moment (M) and angular velocity of the drive (ω1), loading moment of the pump (M1), moment (M2) and angular velocity of the turbine (ω2) for the system with hydrodynamic converter M350.222 and for chosen parameter value u = 0.4. Results are given in two forms of dynamic characteristics, namely as classic frequency response functions (upper parts) and as Nyquist diagrams (lower parts). Both types of dynamic characteristics are calculated for four values of the loadingmechanism inertia moment: kg m2 and for supplementary gear ratio i m = 1. Equal sections of loading angular velocity Δν with value π corresponding to equal sections on frequency response function x-coordinates are in the Nyquist diagrams separated by bold points as well. In dynamic calculations, theDiesel-engine time constant s, regulator time constant s and the regulator damping ratio ζ = 0.55 were considered. The left parts of the dynamic characteristics in Fig. 7, Fig. 8, Fig. 9, Fig. 10 and Fig. 11 correspond to the dynamic regime with mean values: λ = 0.111, K = 3.12, i = 0.127, which are quantified bybold points on the left thin vertical in the external static characteristic in Fig. 3(a), when the converter works in so-called friction clutch regime. Mean values of dynamic variables, corresponding to this dynamic regime, are: M = 0.0506,= 0.158, ω1 = 0.673, ω2 = 0.0855, M z = 0.152, z = 0.0849. These values areMalso accentuated in Fig. 5(a) by bold points on thin vertical line. In this dynamic regime the converter works with mean transfer energy efficiency η≈ 0.405. Theright parts of the dynamic characteristics introduced in Fig. 7, Fig. 8, Fig. 9, Fig. 10 and Fig. 11 correspond to dynamic regime with mean values: λ = 0.111, K = 1.1,i = 0.74, represented by bold points on the right thin vertical on the external staticcharacteristic in Fig. 3(a) when the converter works in so-called moment converter regime with mean energy transfer efficiency higher than 0.8. The mean values of dynamic variables corresponding to this dynamic state are: M = 0.0506,M= 0.0557, ω1 = 0.673, ω2 = 0.4986, M z = 0.0466, z = 0.0849 and aremarked out in Fig. 5(a) as well on thin vertical line by bold points. Non-dimensional friction losses at dynamic calculation were considered according to (16) as follows:, , where is dimensional relative moment standard value (13).Fig. 4. Mean values of the chosen dynamic variables w of the system with converters: M350.222,M350.623M, M350.675, M350.72M3M for optional parameter u = 0.3.Fig. 5. Mean values of the chosen dynamic variables w of the system with converters: M350.222,M350.623M, M350.675, M350.72M3M for optional parameter u = 0.4.Fig. 6. Mean values of the chosen dynamic variables w of the system with converters: M350.222,M350.623M, M350.675, M350.72M3M for optional parameter u = 0.6.Fig. 7. Dynamic factor (transmissibility) of the centred periodic component of the system driving moment with the converter M350.222 in fretting clutch and moment converter regime for optionalparameter u = 0.4Fig. 8. Dynamic factor (transmissibility) of centred periodic component of the driving angular velocity of the system with the converter M350.222 in fretting clutch and moment converter regimefor optional parameter u = 0.4Fig. 9. Dynamic factor (transmissibility) of centred periodic component of the pump moment of the converter M350.222 in fretting clutch and moment converter regime for parameter u = 0.4.Fig. 10. Dynamic factor (transmissibility) of centred periodic component of the turbine moment of the converter M350.222 in fretting clutch and moment converter regime for parameter u = 0.4.Fig. 11. Dynamic factor (transmissibility) of centred periodic component of the turbine angular velocity of the system converter M350.222 at fretting clutch and moment converter regime forparameter u = 0.4.4. Results evaluation and concluding remarksIn the paper some dynamic properties of a Diesel drive line with some the latest generation torque converter types were inquired and stationary response to common monoharmonic loading was calculated. Mean values of all dynamic variables were calculated for the system with the same controlled drive and successively four chosen torque converter types. In order to save space, complete dynamic calculations are performed only for the system with converter M350.222 and results are introduced in form of frequency response functions and Nyquist diagrams.Already from the calculated mean values in Fig. 4, Fig. 5 and Fig. 6 one may judge technical possibilities and collaboration aptness of the applied drive with the considered converter type. Even from these diagrams it is evident that at application M350.222 this converter can work in arbitrary hydrodynamic regime when optional parameter value u 0.6. Working regime of the system adjusts automatically and depends only on external loading and parameter values u. At maximal loading and lower values u all the considered hydrodynamic converter work in hydrodynamic friction clutch regime when turbine rotation may even extremely decrease to zero value. At mean loading the converter works in the system as hydrodynamic moment converter with average energy transfer efficiency above 0.8. At low system loading and higher values u, the converter behaves as quasi-hydrodynamic fix clutch when relative working medium velocity is low and creates impression of stiffened substance. In this working regime angular velocities of all the converter rotating components are close to each other and mean energy transfer efficiency approaches theoretically to 1. From calculated mean values in Fig. 5 and Fig. 6 it is evident that the torque converters: M350.623M, M350.675, M350.72M3M can at optional parameter u 0.4 cooperate with given drive only in moment converter andhydrodynamic fix clutch regime respectively. The dynamical responses of the drive line with the torque converter M350.222 are depicted in Fig. 7, Fig. 8, Fig. 9, Fig. 10 and Fig. 11. In Fig. 7 and Fig. 8 dynamic factors (transmissibility) of moment and angular velocity of the drive are introduced. It is evident that at chosen value of damping ratio ζ = 0.55 only one significant resonance of these variables occurswhich lies always in loading frequency interval (), regardless of the fact in what regime the applied converter works. Resonance values of moment and angular velocity of the drive are significantly influenced by total inertia moment ofvalue is, the lower resonant values are. Verythe loading mechanism. The higher Isimply one can inquire influence of the supplementary gearing ratio i m because reduced inertia moment I z changes with its second power. It is interesting that change of the loading mechanism inertia moment does not shift resonant peak of dynamic characteristics that remain practically at the same loading angular frequency ν. Remarkable results may be observed in Fig. 9(a) and (b) where the dynamic factors of the pump loading moment corresponding to resonant values of moment and angular velocity of the drive are minimal and express small sensibility to I z magnitude in both inquired converter regimes. In Fig. 10 and Fig. 11, the dynamic factors of driving moment and angular velocity of the turbine are drawn for the case when the applied converter works in friction clutch and moment converter regime. Whole range of dynamic calculations has been made for different values of the time constant and regulator damping ratio ζ. It turned out that the drive linewith all the applied converter types has small sensibility to time constant magnitudeof the Watt regulator. Time constant changes in range (0.01–0.1 s) did not visibly reveal in calculated dynamic factors what is certain difference in comparison with hydrostatic transmission mechanisms (see e.g. [9]). On the other part, dynamic calculations prove that damping ratio ζ influences noticeably resonant values of all dynamic variables. The resonant transmissibility peaks of the driving moment M r and angular velocity ωr in dependence on damping ratio ζ, for the system with converter M350.222 and for four different loading inertia moment values areintroduced in Fig. 12(a) and (b). The thin dash lines always denote stationary resonant dynamic factor values of appertaining variable corresponding to zero-value loading frequency. Equally, as in previous cases, left parts of the Fig. 12(a) represent resonant values of moment and angular driving velocity when the applied converter works in hydrodynamic friction clutch regime. Analogically the right parts of the Fig. 12(b) represent resonant values of the same variable when the converter works in hydrodynamic moment converter regime. From the introduced diagrams it is evident that disturbance transmissibility from the loading mechanism to the drive grows with increasing damping ratio ζ. On the other part, dynamic calculations showed that for low damping ratio values (ζ 0.1) indication of a secondary resonance ofchosen variables appears in loading frequency band but the values of this secondary resonance are essentially lower than corresponding stationary values.Fig. 12. Transmissibility resonant values dependences of moment and driving angular velocity on damping ratio and on reduced inertia moment of the loading for the system with the at hydrodynamicclutch and moment converter regime at u = 0.4.配合新一代液力变矩器的柴油动力线的一些特性摘要：带有控制柴油机的车的动态特性，液力传导机制，还有传动装置和进行普通装卸工作的装载机的调查。

机械设计外文文献翻译、中英文翻译unavailable。

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Belt Conveying Systems Development of driving system Among the methods of material conveying employed，beltconveyors play a very important part in the reliablecarrying of material over long distances at competitivecost．Conveyor systems have become larger and more complex and drive systems have also been going through a process of evolution and will continue to do so．Nowadays，bigger belts require more power and have brought the need forlarger individual drives as well as multiple drives such as 3 drives of 750 kW for one belt(this is the case forthe conveyor drives in Chengzhuang Mine)．The ability to control drive acceleration torque is critical to beltconveyors’ performance．An efficient drive system should be able to provide smooth，soft starts while maintaining belt tensions within the specified safe limits．For load sharing on multiple drives．torque and speed control are also important considerations in the drive system’sdesign. Due to the advances in conveyor drive controltechnology，at present many more reliable．Cost-effective and performance-driven conveyor drive systems covering a wide range of power are available for customers’choices[1].1 Analysis on conveyor drive technologies1．1 Direct drivesFull-voltage starters．With a full-voltage starter design，the conveyor head shaft is direct-coupled to the motor through the gear drive．Direct full-voltage starters are adequate forrelatively low-power, simple-profile conveyors．With directfu11-voltage starters．no control is provided for various conveyor loads and．depending on the ratio between fu11-and no-1oad power requirements，empty starting times can be three or four times faster than full load．The maintenance-free starting system is simple，low-cost and very reliable．However, they cannot control starting torque and maximum stall torque；therefore．they are limited to the low-power, simple-profile conveyor belt drives．Reduced-voltage starters．As conveyor power requirements increase，controlling the applied motor torque during the acceleration period becomes increasingly important．Because motor torque 1s a function of voltage，motor voltage must be controlled．This can be achieved through reduced-voltage starters by employing a silicon controlled rectifier(SCR)．A common starting method with SCR reduced-voltage starters is to apply low voltage initially to take up conveyor belt slack．and then to apply a timed linear ramp up to full voltage and belt speed．However, this starting method will not produce constant conveyor belt acceleration．When acceleration is complete．the SCRs,which control the applied voltage to the electric motor． are locked in full conduction, providingfu11-line voltage to the motor．Motors with higher torque and pull—up torque，can provide better starting torque when combined with the SCR starters, which are available in sizes up to 750 KW．Wound rotor induction motors．Wound rotor induction motors are connected directly to the drive system reducer and are amodified configuration of a standard AC induction motor．By inserting resistance in series with the motor’s rotor windings．the modified motor control system controls motor torque．For conveyor starting，resistance is placed in series with the rotor for low initial torque．As the conveyor accelerates，the resistance is reduced slowly to maintain a constant acceleration torque．On multiple-drive systems．an external slip resistor may be left in series with the rotor windings to aid in load sharing．The motor systems have a relatively simple design．However, the control systems for these can be highly complex，because they are based on computer control of the resistance switching．Today，the majority of control systems are custom designed to meet a conveyor system’s particular specifications．Wound rotor motors are appropriate for systems requiring more than 400 kW ．DC motor．DC motors．available from a fraction of thousands of kW ，are designed to deliver constant torque below base speed and constant kW above base speed to the maximum allowable revolutions per minute(r/min)．with the majority of conveyor drives, a DC shunt wound motor is used．Wherein the motor’s rotating armature is connected externally．The most common technology for controlling DC drives is a SCR device． which allows for continual variable-speed operation．The DC drive system is mechanically simple, but can include complex custom-designed electronics to monitor and control the complete system．This system option is expensive in comparison to other soft-start systems．but it isa reliable, cost-effective drive in applications in which torque,1oad sharing and variable speed are primary considerations．DC motors generally are used with higher-power conveyors，including complex profile conveyors with multiple-drive systems，booster tripper systems needing belt tension control and conveyors requiring a wide variable-speed range．1．2 Hydrokinetic couplingHydrokinetic couplings，commonly referred to as fluid couplings．are composed of three basic elements; the driven impeller, which acts as a centrifugal pump；the driving hydraulic turbine known as the runner and a casing that encloses the two power components．Hydraulic fluid is pumped from the driven impeller to the driving runner, producing torque at the driven shaft．Because circulating hydraulicfluid produces the torque and speed，no mechanical connection is required between the driving and driven shafts．The power produced by this coupling is based on the circulated fluid’s amount and density and the torque in proportion to input speed．Because the pumping action within the fluid coupling depends on centrifugal forces．the output speed is less than the input speed．Referred to as slip．this normally is between l% and 3%．Basic hydrokinetic couplings are available in configurations from fractional to several thousand kW ．Fixed-fill fluid couplings．Fixed-fill fluid couplings are the most commonly used soft-start devices for conveyors with simpler belt profiles and limited convex/concave sections．They are relatively simple,1ow-cost,reliable,maintenance free devices that provide excellent soft starting results to themajority of belt conveyors in use today．Variable-fill drain couplings．Drainable-fluid couplings work on the same principle as fixed-fill couplings．The coupling’s impellers are mounted on the AC motor and the runners on the driven reducer high-speed shaft．Housing mounted to the drive base encloses the working circuit．The coupling’s rotating casing contains bleed-off orifices that continually allow fluid to exit the working circuit into a separate hydraulic reservoir．Oil from the reservoir is pumped through a heat exchanger to a solenoid-operated hydraulic valve that controls the filling of the fluid coupling．To control the starting torque of a single-drive conveyor system，the AC motor current must be monitored to provide feedback to the solenoid control valve．Variable fill drain couplings are used in medium to high-kW conveyor systems and are available in sizes up to thousands of kW ．The drives can be mechanically complex and depending on the control parameters．the system can be electronically intricate．The drive system cost is medium to high, depending upon size specified．Hydrokinetic scoop control drive．The scoop control fluid coupling consists of the three standard fluid coupling components：a driven impeller, a driving runner and a casing that encloses the working circuit．The casing is fitted with fixed orifices that bleed a predetermined amount of fluid into a reservoir．When the scoop tube is fully extended into the reservoir, the coupling is l00 percent filled．The scoop tube, extending outside the fluid coupling，is positioned using anelectric actuator to engage the tube from the fully retracted to the fully engaged position．This control provides reasonably smooth acceleration rates．to but the computer-based control system is very complex．Scoop control couplings are applied on conveyors requiring single or multiple drives from l50 kW to 750 kW.1．3 Variable-frequency control(VFC)Variable frequency control is also one of the direct drive methods．The emphasizing discussion about it here is because that it has so unique characteristic and so good performance compared with other driving methods for belt conveyor． VFC devices Provide variable frequency and voltage to the induction motor, resulting in an excellent starting torque and acceleration rate for belt conveyor drives．VFC drives．available from fractional to several thousand(kW ), are electronic controllers that rectify AC line power to DC and，through an inverter, convert DC back to AC with frequency and voltage contro1．VFC drives adopt vector control or direct torque control(DTC)technology，and can adopt different operating speeds according to different loads．VFC drives can make starting or stalling according to any given S-curves．realizing the automatic track for starting or stalling curves．VFC drives provide excellent speed and torque control for starting conveyor belts．and can also be designed to provide load sharing for multiple drives．easily VFC controllers are frequently installed on lower-powered conveyor drives，but when used at the range of medium-high voltage in the past．the structure of VFC controllers becomes verycomplicated due to the limitation of voltage rating of power semiconductor devices，the combination of medium-high voltage drives and variable speed is often solved with low-voltage inverters using step-up transformer at the output，or with multiple low-voltage inverters connected in series．Three-level voltage-fed PWM converter systems are recently showing increasing popularity for multi-megawatt industrial drive applications because of easy voltage sharing between the series devices and improved harmonic quality at the output compared to two-level converter systems With simple series connection of devices．This kind of VFC system with three 750 kW /2．3kV inverters has been successfully installed in ChengZhuang Mine for one 2．7-km long belt conveyor driving system in following the principle of three-level inverter will be discussed in detail．2 Neutral point clamped(NPC)three-level inverter using IGBTsThree-level voltage-fed inverters have recently become more and more popular for higher power drive applications because of their easy voltage sharing features．1ower dv/dt per switching for each of the devices，and superior harmonic quality at the output．The availability of HV-IGBTs has led to the design of a new range of medium-high voltage inverter using three-level NPC topology．This kind of inverter can realize a whole range with a voltage rating from 2．3 kV to 4．1 6 kV Series connection of HV-IGBT modules is used in the 3．3 kV and 4．1 6 kV devices．The 2．3 kV inverters need only one HV-IGBT per switch[2,3].2．1 Power sectionTo meet the demands for medium voltage applications．a three-level neutral point clamped inverter realizes the power section．In comparison to a two-level inverter．the NPC inverter offers the benefit that three voltage levels can be supplied to the output terminals，so for the same output current quality，only 1/4 of the switching frequency is necessary．Moreover the voltage ratings of the switches in NPC inverter topology will be reduced to 1/2．and the additional transient voltage stress on the motor can also be reduced to 1/2 compared to that of a two-level inverter．The switching states of a three-level inverter are summarized in Table 1．U．V and W denote each of the three phases respectively；P N and O are the dc bus points．The phase U，for example，is in state P(positive bus voltage)when the switches S1u and S2u are closed，whereas it is in state N (negative bus voltage) when the switches S3u and S4u are closed．At neutral point clamping，the phase is in O state when either S2u or S3u conducts depending on positive or negative phase current polarity，respectively．For neutral point voltage balancing，the average current injected at O should be zero．2．2 Line side converterFor standard applications．a l2-pulse diode rectifier feeds the divided DC-link capacitor．This topology introduces low harmonics on the line side．For even higher requirements a 24-pulse diode rectifier can be used as an input converter．For more advanced applications where regeneration capability is necessary, an active front．end converter can replace thediode rectifier, using the same structure as the inverter．2．3 Inverter controlMotor Contro1．Motor control of induction machines is realized by using a rotor flux．oriented vector controller．Fig．2 shows the block diagram of indirect vector controlled drive that incorporates both constant torque and high speed field-weakening regions where the PW M modulator was used．In this figure，the command fluxis generated as function of speed．The feedback speed is added with the feed forward slip command signal. the resulting frequency signal is integrated and thenthe unit vector signals(cosand sin)are generated．The vector rotator generates the voltageand anglecommands for the PW M as shown．PWM Modulator．The demanded voltage vector is generated using an elaborate PWM modulator．The modulator extends the concepts of space-vector modulation to the three-level inverter．The operation can be explained by starting from a regularly sampled sine-triangle comparison from two-level inverter．Instead of using one set of reference waveforms and one triangle defining the switching frequency， the three-level modulator uses two sets of reference waveforms U r1 and U r2 and just one triangle．Thus, each switching transition isused in an optimal way so that several objectives are reached at the same time．Very low harmonics are generated．The switching frequency is low and thus switching losses are minimized．As in a two-level inverter, a zero-sequence component can be added to each set of reference waveform s in order to maximize the fundamental voltage component．As an additional degree of freedom，the position of the reference waveform s within the triangle can be changed．This can be used for current balance in the two halves of the DC-1ink．3 Testing resultsAfter Successful installation of three 750 kW /2．3 kV three-level inverters for one 2．7 km long belt conveyor driving system in Chengzhuang Mine．The performance of the whole VFC system was tested．Fig．3 is taken from the test，which shows the excellent characteristic of the belt conveyor driving system with VFC controller．Fig．3 includes four curves．The curve 1 shows the belt tension．From the curve it can be find that the fluctuation range of the belt tension is very smal1．Curve 2 and curve 3 indicate current and torque separately．Curve 4 shows the velocity of the controlled belt．The belt velocity havethe“s”shape characteristic．A1l the results of the test showa very satisfied characteristic for belt driving system．4 ConclusionsAdvances in conveyor drive control technology in recent years have resulted in many more reliable．Cost-effective and performance-driven conveyor drive system choices for users．Among these choices，the Variable frequency control (VFC) method shows promising use in the future for long distancebelt conveyor drives due to its excellent performances．The NPC three-level inverter using high voltage IGBTs make the Variable frequency control in medium voltage applications become much more simple because the inverter itself can provide the medium voltage needed at the motor terminals，thus eliminating the step-up transformer in most applications in the past．The testing results taken from the VFC control system with NPC three．1evel inverters used in a 2．7 km long belt conveyor drives in Chengzhuang Mine indicates that the performance of NPC three-level inverter using HV-IGBTs together with the control strategy of rotor field-oriented vector control for induction motor drive is excellent for belt conveyor driving system．中文译文：带式输送机及其牵引系统在运送大量的物料时，带式输送机在长距离的运输中起到了非常重要的竞争作用。

Mechanical EngineeringIntroduction to Mechanical EngineeringMechanical engineering is the branch of engineering that deals with machines and the production of power. It is particularly concerned with forces and motion.History of Mechanical EngineeringThe invention of the steam engine in the latter part of the 18th century, providing a key source of power for the Industrial Revolution, gave an enormous impetus to the development of machinery of all types. As a result a new major classification of engineering, separate from civil engineering and dealing with tools and machines, developed, receiving formal recognition in 1847 in the founding of the Institution of Mechanical Engineers in Birmingham, England.Mechanical engineering has evolved from the practice by the mechanic of an art based largely on trial and error to the application by the professional engineer of the scientific method in research, design, and production.The demand for increased efficiency, in the widest sense, is continually raising the quality of work expected from a mechanical engineer and requiring of him a higher degree of education and training. Not only must machines run more economically but capital Costs also must be minimized.Fields of Mechanical EngineeringDevelopment of machines for the production of goods the high material standard of living in the developed countries owes much to the machinery made possible by mechanical engineering. The mechanical engineer continually invents machines to produce goods and develops machine tools of increasing accuracy and complexity to build the machines.The principal lines of development of machinery have been an increase in the speed of operation to obtain high rates of production, improvement in accuracy to obtain quality and economy in the product, and minimization of operating costs. These three requirements have led to the evolution of complex control systems.The most successful production machinery is that in which the mechanical design of the machine is closely integrated with the control system, whether the latter is mechanical orelectrical in nature. A modern transfer line (conveyor) for the manufacture of automobile engines is a good example of the mechanization of a complex series of manufacturing processes. Developments are in hand to automate production machinery further, using computers to store and process the vast amount of data required for manufacturing a variety of components with a small number of versatile machine tools. One aim is a completely automated machine shop for batch production, operating on a three shift basis but attended by a staff for only one shift per day.Development of machines for the production of power Production machinery presuppose an ample supply of power. The steam engine provided the first practical means of generating power from heat to augment the old sources of power from muscle, wind, and water One of the first challenges to the new profession of mechanical engineering was to increase thermal efficiencies and power; this was done principally by the development of the steam turbine and associated large steam boilers. The 20th century has witnessed a continued rapid growth in the power output of turbines for driving electric generators, together with a steady increase in thermal efficiency and reduction in capital cost per kilowatt of large power stations. Finally, mechanical engineers acquired the resource of nuclear energy, whose application has demanded an exceptional standard of reliability and safety involving the solution of entirely new problems- The control systems of large power plank and complete nuclear power stations have become highly sophisticated networks of electronic, fluidic. Electric, hydraulic, and mechanical components, ail of these involving me province of the mechanical engineer.The mechanical engineer is also responsible for the much smaller internal combustion engines, both reciprocating (gasoline and diesel) and rotary (gas-turbine and Wankel) engines, with their widespread transport applications- In the transportation field generally, in air and space as well as on land and sea. the mechanical engineer has created the equipment and the power plant, collaborating increasingly with the electrical engineer, especially in the development of suitable control systems.Development of military weapons The skills applied to war by the mechanical engineer are similar to those required in civilian applications, though the purpose is to enhance destructive power rather than to raise creative efficiency. The demands of war have channeled huge resources into technical fields, however, and led to developments that have profound benefits in peace. Jet aircraft and nuclear reactors are notable examples.Biaengineering Bioengineering is a relatively new and distinct field of mechanical engineering that includes the provision of machines to replace or augment the functions of the human body and of equipment for use in medical treatment. Artificial limbs have been developed incorporating such lifelike functions as powered motion and touch feedback. Development is rapid in the direction of artificial spare-part surgery. Sophisticated heart-lung machines and similar equipment permit operations of increasing complexity and permit the vital functions in seriously injured or diseased patients to be maintained.Environmental control Some of the earliest efforts of mechanical engineers were aimed at controlling man's environment by pumping water to drain or irrigate land and by ventilating mines. The ubiquitous refrigerating and air-conditioning plants of the modem age are based on a reversed heat engine, where the supply of power "pumps" heat from the cold region to the warmer exterior.Many of the products of mechanical engineering, together with technological developments in other fields, have side effects on the environment and give rise to noise, the pollution of water and air, and the dereliction of land and scenery. The rate of production, both of goods and power, is rising so rapidly that regeneration by natural forces can no longer keep pace. A rapidly growing field for mechanical engineers and others is environmental control, comprising the development of machines and processes that will produce fewer pollutants and of new equipment and techniques that can reduce or remove the pollution already generated.Functions of Mechanical EngineeringFour functions of the mechanical engineering, common to all the fields mentioned, are cited. The first is the understanding of and dealing with the bases of mechanical science. These include dynamics, concerning the relation between forces and motion, such as in vibration; automatic control; thermodynamics, dealing with the relations among the various forms of heat, energy, and power; fluid flow; heat transfer; lubrication; and properties of materials.Second is the sequence of research, design, and development. This function attempts to bring about the changes necessary to meet present and future needs. Such work requires not only a dear understanding of mechanical science and an ability to analyze a complex system into its basic factors, but also the originality to synthesize and invent.Third is production of products and power, which embraces planning, operation, and maintenance. The goal is to produce the maximum value with the minimum investment and cost while maintaining or enhancing longer term viability and reputation of the enterprise or the institution.Fourth is the coordinating functioning of the mechanical engineering, including management, consulting, and, in some cases, marketing.In all of these functions there is a long continuing trend toward the use of scientific instead of traditional or intuitive methods, an aspect of the ever-growing professionalism of mechanical engineering. Operations research, value engineering, and PABLA (problem analysis by logical approach) are typical titles of such new rationalized approaches. Creativity, however, cannot be rationalized. The ability to take the important and unexpected step that opens up new solutions remains in mechanical engineering, as elsewhere, largely a personal and spontaneous characteristic.The Future of Mechanical EngineeringThe number of mechanical engineers continues to grow as rapidly as ever, while the duration and quality of their training increases. There is a growing: awareness, however, among engineers and in the community at large that the exponential increase in populationand living standards is raising formidable problems in pollution of the environment andthe exhaustion of natural resources; this clearly heightens the need for all of the technical professions to consider the long-term social effects of discoveries and developments. -There will be an increasing demand for mechanical engineering skills to provide for man's needs while reducing to a minimum the consumption of scarce raw materials and maintaining a satisfactory environment.Introduction to DesignThe Meaning of DesignTo design is to formulate a plan for the satisfaction of a human need. The particular need to be satisfied may be quite well defined from the beginning. Here are two examples in which needs are well defined:1. How can we obtain large quantities of power cleanly, safely, and economical/ without using fossil fuels and without damaging the surface of the earth?2. This gear shaft is giving trouble; there have been eight failures in the last six weeks. Do something about it.On the other hand, the statement of a particular need to be satisfied may be so nebulous and ill defined that a considerable amount of thought and effort is necessary in ( order to state it dearly as a problem requiring a solution. Here are two examples.-1. Lots of people are killed in airplane accidents.2. In big cities there are too many automobiles on the streets and highways.This second type of design situation is characterized by the fact that neither the need nor the problem to be solved has been identified. Note, too, that the situation may contain not one problem but many.We can classify design, too. For instance, we speak of:1. Clothing design 7. Bridge design2. Interior design 8. Computer-aided design3. Highway design 9. Heating system design.4. Landscape design 10. Machine design5. Building design 11. Engineering design6. Ship design 12. Process designIn fact, there are an endless number, since we can classify design according to the particular article or product or according to the professional field,In contrast to scientific or mathematical problems, design problems have no unique answers; it is absurd, for example, to request the "correct answer" to a design problem, because there is none. In fact, a "good" answer today may well turn out to be a "poor" answer tomorrow, if there is a growth of knowledge during the period or if there are other structural or societal changes.Almost everyone is Involved with design in one way or another, even in dally living, because problems are posed and situations arise which must be solved. A design problem is not a hypothetical problem at all. Design has an authentic purpose—the creation of an end result by taking definite action, or the creation of something having physical reality. In engineering, the word design conveys different meanings to different persons. Some think of a designer as one who employs the drawing board to draft the details of a gear, clutch, or other machine member. Others think of design as the creation of a complex system, such as a communications network. In some areas of engineering the word design has been replaced by other terms such as systems engineering or applied decision theory. But no matter what words are used to describe the design function, in engineering it is still the process in which scientific principles and the tools of engineering—mathematics, computers, graphics, and English—are used to produce a plan which, when carried out, will satisfy a human need.Mechanical Engineering DesignMechanical design means die design of things and systems of a mechanical nature machines, products, structures, devices, and instruments. For the most part, mechanical design utilizes mathematics, the materials sciences, and the engineering-mechanics sciences.Mechanical engineering design includes all mechanical design, but it is a broader study, because it includes all the disciplines of mechanical engineering, such as the thermal and fluids sciences, too. Aside from the fundamental sciences that are required, the first studies in mechanical engineering design are in mechanical design.The Phases of DesignThe complete process, from start to finish. The process W begins with a recognition of a need and a decision to do something about it. After much iteration, the process ends with the presentation of the plans for satisfying the need.Design ConsiderationsSometimes the strength required of an element in a system is an important factor in the determination of the geometry and the dimensions of the element. In such a situation we say that strength is an important design consideration. When we use the expression design consideration, we are referring to some characteristic which influences the design of the element or, perhaps, the entire system. Usually quite a number of such characteristics must be considered in a given design situation. Many of the important ones are as follows:1. Strength2. Reliability3. Thermal properties4. Corrosion5. Wear6. Friction7. Processing8. Utility9. Cost10. Safety11. Weight12. Life13. Noise14. Styling15. Shape16. Size17. Flexibility18. Control19. Stiffness20. Surface finish21. Lubrication22. Maintenance23. Volume24. LiabilitySome of these have to do directly with the dimensions, the material, the processing, and the joining of the elements of the system. Other considerations affect the configuration of the total system.To keep the correct perspective, however, it should be observed that in many design situations the important design considerations are such that no calculations or experiments are necessary in order to define an element or system. Students, especially, are often confounded when they run into situations in which it is virtually impossible to make a single calculation and yet an important design decision must be made. These are not extraordinary occurrences at all; they happen every day. Suppose that it is desirable from a sales standpoint—for example, in medical laboratory machinery—to create an impression of great strength and durability. Thicker parts assembled with larger-than-usual oversize bolts can be used to create a rugged-looking machine. Sometimes machines and their parts are designed purely from the standpoint of styling and nothing else. These points are made here so that you will not be misled into believing that there is a rational mathematical approach to every design decision.ManufacturingManufacturing is that enterprise concerned with converting raw material into finished products. There are three distinct phases in manufacturing. These phases are as follows: input, processing, and output.The first phase includes all of the elements necessary to create a marketable product. First, there must be a demand or need for the product. The necessary materials must be (available. Also needed are such resources as energy, time, human knowledge, and human skills. Finally, it takes capital to obtain all of the other resources.Input resources are channeled through the various processes in Phase Two. These are the processes used to convert raw materials into finished products. A design is developed. Based on the design, various types of planning are accomplished. Plans are put into action through various production processes. The various resources and processes are managed to ensure efficiency and productivity. For example, capital resources must be carefully managed to ensure they are used prudently. Finally, the product in question is marketed.The final phase is the output or finished product. Once the finished product has been purchased it must be transported to users. Depending on the nature of the product, installation and ongoing field support may be required. In addition, with some products, particularly those of a highly complex nature, training is necessary.Materials and Processes in ManufacturingEngineering materials covered herein are divided into two broad categories: metals and nonmetals. Metals are subdivided into ferrous metals, nonferrous metals, high-performance alloys, and powdered metals. Nonmetals are subdivided into plastics, elastomers, composites, and ceramics. Production processes covered herein are divided into several broad categories including forming, forging,casting/molding, .heat treatment^ .fastening joining metrology/quality control, and material removal. Each of these is subdivided into several other processes.Stages in the Development of ManufacturingOver the years, manufacturing processes have- gone through four distinct,-although overlapping, stages of development. These stages are as follows: Stage 1 ManualStage 2 MechanizedStage 3 AutomatedStage 4 IntegratedWhen people first began converting raw materials into finished products, they used manual processes. Everything was accomplished using human hands and manually operated tools. This was a very rudimentary form of fully integrated manufacturing. A person identified the need, collected materials, designed a product to meet the need, produced the product, and used it. Everything from start to finish was integrated within the mind of the person who did all the work.Then during the industrial revolution mechanized processes were introduced and humans began using machines to accomplish work previously accomplished manually. This led to work specialization which, in turn, eliminated the integrated aspect of manufacturing. In this stage of development, manufacturing workers might see only that part of an overall manufacturing operation represented by that specific piece on which they worked. There was no way to tell how their efforts fit into the larger picture or their workpiece into the finished product.The next stage in the development of manufacturing processes involved the automation of selected processes. This amounted to computer control of machines and processes. During this phase, islands of automation began to spring up on the shop floor. Each island represented a distinct process or group of processes used in the production of a product. Although these islands of automation did tend to enhance the productivity of the individual processes within the islands, overall productivity often was unchanged. This was because the islands were sandwiched in among other processes that were not automated and were not synchronized with them.The net result was that workpieces would move quickly and efficiently through the automated processes only to back up at manual stations and create bottlenecks. To understand this problem, think of yourself driving from stoplight to stoplight in rush hour traffic Occasionally you find an opening and an: able to rush ahead of the other cars that are creeping along, only to find yourself backed up at the next light. The net effect of your brief moment of speeding ahead is canceled out by the bottleneck at the next stoplight. Better progress would be made if you and the other drivers could synchronize your speed to the changing of the stoplights. Then all cars would move steadily and consistently along and everyone would make better progress in the long run.This need for steady, consistent flow on the shop floor led to the development of integrated manufacturing, a process that is still emerging. In fully integrated settings, machines and processes are computer controlled and integration is accomplished through computers. In the analogy used in the previous paragraph, computers would synchronize the rate of movement of all cars with the changing of the stoplights so that everyone moved steadily and consistently along.The Science of MechanicsThat branch of scientific analysis which deals with motions, time, and forces is called mechanics and is made up of two parts, static’s and dynamics. Static’s deals with the analysis of stationary systems, i. e., those in which time is not a factor, and dynamics deals with systems which change with time.Dynamics is also made up. of tyro major disciplines, first recognized as separate entities by Euler in 1775.The investigation of the motion of a rigid body may be conveniently separated into two parts, the one geometrical, the other mechanical. In the first part, the transference of the body from a given position to any other position must be investigated without respect to the cause of the motion, and must be represented by analytical formulae, which will define the position of each point of the body. This investigation will therefore be referable solely to geometry, or rather to stereotomy.It is clear that by the separation of this part of the question from the other, which belongs properly to Mechanics, the determination of the motion from dynamical principles will be made much easier than if the two parts were undertaken conjointly.These two aspects of dynamics were later recognized as the distinct sciences of kinematics and kinetics, and deal with motion and the forces producing it respectively.The initial problem in the design of a mechanical system therefore understands its kinematics. Kinematics is the study of motion, quite apart from the forces whichproduce that motion. More particularly, kinematics is the study of position, displacement rotation, speed, velocity, and acceleration. The study, say of planetary or orbital motion is also a problem in kinematics.It should be carefully noted in the above quotation that Euler based his separation of dynamics into kinematics and kinetics on the assumption that they should deal with rigid bodies. It is this very important assumption that allows the two to be treated separately. For flexible bodies, the shapes of the bodies themselves, and therefore their motions, depend on the forces exerted on them. In this situation, the study of force and motion must take place simultaneously, thus significantly increasing the complexity of the analysis.Fortunately, although all real machine parts are flexible to some degree, machines are usually designed from relatively rigid materials, keeping part deflections to a minimum. Therefore, it is common practice to assume that deflections are negligible and parts are rigid when analyzing a machine's kinematics performance, and then, after the dynamic analysis when loads are known, to design the parts so that this assumption is justified.。

附录Steeplechase lifting device structure and design Lifting Gear steeplechase and design of the structure of the lifting mechanism is relatively traditional, the tail plate lifting mechanism using only a single fuel tank, so that the hydraulic system of the pipe is simple, convenient control and high reliability of the hydraulic system, and and ease of installation. The above analysis and calculation of the institutions such as the structure and properties of the mathematical relationship between parameters. To promote inter-related with the sleeve of the friction and wear, the sleeve guide groove angle and flip angle and a high degree of adaptability, such as lifting will be subject to further research and the analysis of the structure of hair.Lifting Gear steeplechase vehicle movements in foreign countries as the rear door (end plate), its installed in the car named after the tail. In this paper, according to national standards call a lifting gear steeplechase. Steeplechase a lifting device installed on the van in the carriage of goods, not only to demonstrate its proprietary water-resistant dust-proof function, but also in the loading and unloading of goods mechanization achieved.1. steeplechase development Lifting GearLifting Gear steeplechase development, largely in foreign countries can be divided into four periods. The first generation of products in the 30's at the end of this century, characterized mainly lifting cylinder, and the steeplechase manually turned on, from or about the quality of 500kg, steeplechase (also known as loading platforms) touchdown angle 9 ° ~ 10 °. At present, this product in South-East Asia, Japan still in use, 90 years, is still the United States by the new development. Second-generation products in the early 50's the European market, in the first generation of products based on the increase of turnover to close the fuel tank. Lift and flip the fuel tank by two to achieve independence. The most common is a type 4 tank, but also of the double. Lifting the quality of more than 500 kg, platform loading touchdown angle 10 °, flip action control based on the experience of the operator. The products are mainly used in the Americas and Southeast Asia. Third-generation products in the 70's at the end of the European market is the second generation of products based on the increase in the fuel tank of the fifth. Only the fuel tank of the hydraulic system in the relative positions of the main effect of memory function, so that touchdown to loading platform, off the flip action is no longer controlled by the operator by the hydraulic control system itself, so that the process is relatively smooth take-off and landing and security. Touchdown angle is generally 8 °~ 10 °. If itdoubles as a car door, and a result of increased platform size, angle may also be less than 8 °. At present these products to Europe and America in general. Fourth-generation products during the early 90s, and its hydraulic system and function of principles with the third-generation products, only an increase of the fuel tank the size of memory, so memory and increase the scope of action. It is different from the third generation of the product lies in the loading platform to increase its special structure, from one body to two activities connected to the platform after the touchdown, not only can automatically flip, but there is a sinking action to achieve the touchdown angle 6 °, even in 6 below. At present, the products in the Netherlands, Yugoslavia and China has applied for a utility model patent. The domestic market has been stereotyped. From the performance, security, reliability results, the fourth-generation products will be gradually replaced the second and third generation products. The first generation of products, because of its simple structure, light weight, although the technical content, but with the advantages of easy maintenance, etc., in developing countries will still have a certain market. Lifting Gear steeplechase development in China only a few things more than a decade. The former Ministry of Posts and Telecommunications in 1985 imported from Japan with a number of lifting devices steeplechase van. Since then, by the Special Purpose Vehicle Institute of Hanyang, Hubei auto parts plant andCommunication Ministry of Posts and Telecommunications Machinery Factory Mingshui three cooperation made the research and development, which lasted more than two years, due to various reasons can not be put into use. In early 1988, Ministry of Posts and Telecommunications Communications Machinery Factory Mingshui technical staff, continue to develop. Post Office in Beijing to help the strong, thanks to the efforts of the past four years, increasing product quality stabilized. Early use of domestic products as a driving force for car engines. To achieve in 1992 a car battery as the driving force of the hydraulic pump station. After 1992, lifting gear steeplechase van due to the development of domestic and began to develop, the skill level is gradually close to the international. According to the current understanding of the situation, the domestic production steeplechase of the enterprises, including Lifting Gear Mingshui, such as posts and telecommunications equipment factory at least five, the product structure have a single-cylinder, four-cylinder, five-cylinder and the early 90's and the latest U.S. technology-based The five-cylinder technology. Although the product mix in the form, the international four-generation products are produced in China, but its development is still in its infancy. The expansion of the domestic market, but also the need for inter-and opportunities. Speaking time may not last long, from the varieties ofspeaking, a short period of time will still exist a variety of forms, but in the end may be the single-cylinder and five-cylinder products.2. steeplechase of the basic principles of lifting gearLifting Gear steeplechase varieties are numerous, but the basic fundamental tenets of the original but it is the same, that is, parallel four-bar linkage of the practical application of the principle of parallel move, it is two sets of parallel four-bar linkage, sub-put longeron on both sides of car, synchronous movements, while the DCE is the above mentioned loading platform (steeplechase). Design, the following three issues to be resolved: BC under the driving force for rotation; BC under the role of rotational dynamics and the role of the form of points; CD under the C-point after touchdown, there must be a rotationaround the point D moves to E end of touchdown to facilitate loading and unloading of goods.2.1 Power SystemSteeplechase early in the development of lifting devices for the automotive engine through the oil pump driven from power-driven devices. Working hours as a result of the need to idle the engine running, is now seldom used. At present, the basic use of micro-driven hydraulic pump station, a car battery for power source. Micro-pump station has the basic components of DC motors (with the car battery voltage to match), control valves, gear pumps, combination valve(overflow, cutting one-way), and the fuel tank, electric start switch, control switch and so on. According to different vehicle battery voltage, DC motors are 12 V, 24 V are two different power according to the weight since there are 018 kW, 110 kW, 112 kW, 115 kW, 2 kW, 3 kW and so on. Gear pump according to the number of tanks (mainly hydraulic flow) and the hydraulic system pressure to choose, there is displacement 1 ml, 112 ml, 116 ml, 210 ml, 215 ml, 410 ml wide range of specifications, the maximum output pressure gear pump up to 25M Pa. Hydraulic Pump Station has been the international product quality is stable, less quality of domestic products, mainly the quality of the solenoid valve or volume too large, however.2.2 The form and the role of driving force transmission pointBoth rely on power through the pressure of hydraulic oil system from the fuel tank to the BC transmission poles. Fuel tanks and installation of the number of different positions, and to take the DC bar the difference in the rotation, the power transmission lines are also different. a1 cylinder on the front. Hinge for a long shaft B, the two parallel four-bar linkage mounted on the shaft at both ends, a shaft connected to the middle arm, then the fuel tank of the piston rod end of the fuel tank on the other side of the fixed bracket on the transmission of power as follows: oil tumbler cylinder → → BC rod shaft, the working process in Figure 2. b1 on the rear cylinder. The fuel tank24 is located in the middle of linkage, the two four-bar linkage in the middle of the BC bar with fixed beams together, the middle beam connecting rod and the fuel tank, fuel tank connected to the other side with the stent. c1 four-cylinder and five-cylinder type. Five-cylinder structure of the memory of the fifth hydraulic cylinder is a cylinder in the hydraulic circuit, the loading platform to participate in only touchdown after the reversal platform action, without reference platform for take-off and landing, and its basic structure with the same four-cylinder. Four-cylinder under the structure of the fuel tank of BC, which is different from the distinction between single-cylinder.2.3 CD under the rotationCD of the rotation pole, four-cylinder with five-cylinder fuel tank of the type of contraction depend on the realization of single-cylinder rear-mounted on, CD can not be achieved under rotation (but can be reversed to achieve at the highest position, because the structure of more complex, and I shall not introduce) ; for the single-cylinder front-on, based on the structural changes under BC achievable. The actual design, AD is also required under certain technical processing to meet the requirements. In addition, note that, D CE articulated only in the D point, the other type for the D, C two hinged.3 steeplechase lifting device to determine the technical parametersLifting Gear steeplechase main technical parameters: Rated lifting the quality of travel movements, take-off and landing speed, shot size, platform size, operating voltage and power motor, gear pump row weight (rated output flow), control valves, the type and quantity of and the fuel tank of the bore and stroke, rated working pressure. Under normal circumstances, the beginning of the design parameters are known to width and height from the floor, battery voltage and capacity, beam spacing and beam auto height and size of rear overhang. Known p a r a m e t e r s a r e t h e f u n d a m e n t a l b a s i s f o r d e s i g n.栏板起重装置的结构与设计相对传统的举升机构,该尾板举升机构只采用了单油缸,使液压系统的管路简单,控制方便,液压系统的可靠性高,且安装方便。

本科毕业设计（本科毕业论文）外文文献及译文文献、资料题目：High-rise Tower Crane designed文献、资料来源：期刊（著作、网络等）文献、资料发表（出版）日期：2000.3.25院（部）：机电工程学院专业：机电工程及自动化High-rise Tower Crane designed under Turbulent Winds At present, construction of tower cranes is an important transport operations lifting equipment, tower crane accident the people's livelihood, major hazards, and is currently a large number of tower crane drivers although there are job permits, due to the lack of means to monitor and review the actual work of a serious violation . Strengthen the inspection and assessment is very important. Tower crane tipping the cause of the accident can be divided into two aspects: on the one hand, as a result of the management of tower cranes in place, illegal operation, illegal overloading inclined cable-stayed suspended widespread phenomenon; Second, because of the tower crane safety can not be found in time For example,Took place in the tower crane foundation tilt, micro-cracks appear critical weld, bolts loosening the case of failure to make timely inspection, maintenance, resulting in the continued use of tower cranes in the process of further deterioration of the potential defect, eventually leading to the tower crane tipping. The current limit of tower crane and the black box and can not be found to connect slewing tower and high-strength bolts loosening tightened after the phenomenon is not timely, not tower verticality of the axis line of the lateral-line real-time measurement, do not have to fight the anti-rotation vehicles, lifting bodies plummeted Meng Fang, hook hoists inclined cable is a timely reminder and record of the function, the wind can not be contained in the state of suspended operation to prevent tipping on the necessary tips on site there is a general phenomenon of the overloaded overturning of the whole security risks can not be accurately given a reminder and so on, all of which the lease on the tower crane, use, management problems,Through the use of tower crane anti-tipping monitor to be resolved. Tower crane anti-tipping Monitor is a new high-tech security monitoring equipment, and its principle for the use of machine vision technology and image processing technology to achieve the measurement of the tilt tower, tower crane on the work of state or non-working state of a variety of reasons angle of the tower caused by the critical state to achieve the alarm, prompt drivers to stop illegal operation, a computer chip at the same time on the work of the state of tower crane be recorded. Tower crane at least 1 day overload condition occurs, a maximum number of days to reach 23 overloading, the driver to operate the process of playing the anti-car, stop hanging urgency, such as cable-stayed suspended oblique phenomenon often, after verification and education, to avoid the possible occurrence of fatal accidents. Wind conditions in the anti-tipping is particularly important, tower cranes sometimes connected with the pin hole and pin do not meet design requirements, to connect high-strength bolts are not loose in time after the tightening of the phenomenon, through timely maintenance in time after the tightening of the phenomenon, through timely maintenance and remedial measures to ensure that the safe and reliable construction progress. Reduced lateral line tower vertical axis measuring the number of degrees,Observation tower angle driver to go to work and organize the data once a month to ensure that the lateral body axis vertical line to meet the requirements, do not have to every time and professionals must be completed by Theodolite tower vertical axismeasuring the lateral line, simplified the management link. Data logging function to ensure that responsibility for the accident that the scientific nature to improve the management of data records for the tower crane tower crane life prediction and diagnosis of steel structures intact state data provides a basis for scientific management and proactive prevention of possible accidents, the most important thing is, if the joint use of the black box can be easily and realistically meet the current provisions of the country's related industries. Tower crane safety management at the scene of great importance occurred in the construction process should be to repair damaged steel, usually have to do a good job in the steel tower crane maintenance work and found that damage to steel structures, we must rule out potential causes of accidents, to ensure safety in production carried out smoothly. Tower crane in the building construction has become essential to the construction of mechanical equipment, tower crane at the construction site in the management of safety in production is extremely important. A long time, people in the maintenance of tower crane, only to drive attention to the conservation and electrical equipment at the expense of inspection and repair of steel structures, to bring all kinds of construction accidents.Conclusion: The tower crane anti-tipping trial monitor to eliminate potential causes of accidents to provide accurate and timely information, the tower crane to ensure the smooth development of the leasing business, the decision is correct, and should further strengthen and standardize the use of the environment (including new staff training and development of data processing system, etc.).The first construction cranes were probably invented by the Ancient Greeks and were powered by men or beasts of burden, such as donkeys. These cranes were used for the construction of tall buildings. Larger cranes were later developed, employing the use of human treadwheels, permitting the lifting of heavier weights. In the High Middle Ages, harbour cranes were introduced to load and unload ships and assist with their construction – some were built into stone towers for extra strength and stability. The earliest cranes were constructed from wood, but cast iron and steel took over with the coming of the Industrial Revolution.For many centuries, power was supplied by the physical exertion of men or animals, although hoists in watermills and windmills could be driven by the harnessed natural power. The first 'mechanical' power was provided by steam engines, the earliest steam crane being introduced in the 18th or 19th century, with many remaining in use well into the late 20th century. Modern cranes usually use internal combustion engines or electric motors and hydraulic systems to provide a much greater lifting capability than was previously possible, although manual cranes are still utilised where the provision of power would be uneconomic.Cranes exist in an enormous variety of forms – each tailored to a specific use. Sizes range from the smallest jib cranes, used inside workshops, to the tallest tower cranes,used for constructing high buildings, and the largest floating cranes, used to build oil rigs and salvage sunken ships.This article also covers lifting machines that do not strictly fit the above definition of a crane, but are generally known as cranes, such as stacker cranes and loader cranes.The crane for lifting heavy loads was invented by the Ancient Greeks in the late 6th century BC. The archaeological record shows that no later than c.515 BC distinctive cuttings for both lifting tongs and lewis irons begin to appear on stone blocks of Greek temples. Since these holes point at the use of a lifting device, and since they are to be found either above the center of gravity of the block, or in pairs equidistant from a point over the center of gravity, they are regarded by archaeologists as the positive evidence required for the existence of the crane.The introduction of the winch and pulley hoist soon lead to a widespread replacement of ramps as the main means of vertical motion. For the next two hundred years, Greek building sites witnessed a sharp drop in the weights handled, as the new lifting technique made the use of several smaller stones more practical than of fewer larger ones. In contrast to the archaic period with its tendency to ever-increasing block sizes, Greek temples of the classical age like the Parthenon invariably featured stone blocks weighing less than 15-20 tons. Also, the practice of erecting large monolithic columns was practically abandoned in favour of using several column drums.Although the exact circumstances of the shift from the ramp to the crane technology remain unclear, it has been argued that the volatile social and political conditions of Greece were more suitable to the employment of small, professional construction teams than of large bodies of unskilled labour, making the crane more preferable to the Greek polis than the more labour-intensive ramp which had been the norm in the autocratic societies of Egypt or Assyria.The first unequivocal literary evidence for the existence of the compound pulley system appears in the Mechanical Problems (Mech. 18, 853a32-853b13) attributed to Aristotle (384-322 BC), but perhaps composed at a slightly later date. Around the same time, block sizes at Greek temples began to match their archaic predecessors again, indicating that the more sophisticated compound pulley must have found its way to Greek construction sites by then.During the High Middle Ages, the treadwheel crane was reintroduced on a large scale after the technology had fallen into disuse in western Europe with the demise of the Western Roman Empire. The earliest reference to a treadwheel (magna rota) reappears in archival literature in France about 1225, followed by an illuminated depiction in a manuscript of probably also French origin dating to 1240. In navigation, the earliest uses of harbor cranes are documented for Utrecht in 1244, Antwerp in 1263, Brugge in 1288 and Hamburg in 1291, while in England the treadwheel is not recorded before 1331.Generally, vertical transport could be done more safely and inexpensively by cranes than by customary methods. Typical areas of application were harbors, mines, and, in particular, building sites where the treadwheel crane played a pivotal role in the construction of the lofty Gothic cathedrals. Nevertheless, both archival and pictorial sources of the time suggest that newly introduced machines like treadwheels or wheelbarrows did not completely replace more labor-intensive methods like ladders, hods and handbarrows. Rather, old and new machinery continued to coexist on medieval construction sites and harbors.Apart from treadwheels, medieval depictions also show cranes to be powered manually by windlasses with radiating spokes, cranks and by the 15th century also by windlasses shaped like a ship's wheel. To smooth out irregularities of impulse and get over 'dead-spots' in the lifting process flywheels are known to be in use as early as 1123.The exact process by which the treadwheel crane was reintroduced is not recorded, although its return to construction sites has undoubtedly to be viewed in close connection with the simultaneous rise of Gothic architecture. The reappearance of the treadwheel crane may have resulted from a technological development of the windlass from which the treadwheel structurally and mechanically evolved. Alternatively, the medieval treadwheel may represent a deliberate reinvention of its Roman counterpart drawn from Vitruvius' De architectura which was available in many monastic libraries. Its reintroduction may have been inspired, as well, by the observation of the labor-saving qualities of the waterwheel with which early treadwheels shared many structural similarities.In contrast to modern cranes, medieval cranes and hoists - much like their counterparts in Greece and Rome - were primarily capable of a vertical lift, and not used to move loads for a considerable distance horizontally as well. Accordingly, lifting work was organized at the workplace in a different way than today. In building construction, for example, it is assumed that the crane lifted the stone blocks either from the bottom directly into place, or from a place opposite the centre of the wall from where it could deliver the blocks for two teams working at each end of the wall. Additionally, the crane master who usually gave orders at the treadwheel workers from outside the crane was able to manipulate the movement laterally by a small rope attached to the load. Slewing cranes which allowed a rotation of the load and were thus particularly suited for dockside work appeared as early as 1340. While ashlar blocks were directly lifted by sling, lewis or devil's clamp (German Teufelskralle), other objects were placed before in containers like pallets, baskets, wooden boxes or barrels.It is noteworthy that medieval cranes rarely featured ratchets or brakes to forestall the load from running backward.[25] This curious absence is explained by the high friction force exercised by medieval treadwheels which normally prevented the wheel from accelerating beyond control.目前，塔式起重机是建筑工程进行起重运输作业的重要设备，塔机事故关系国计民生、危害重大，而目前众多的塔机司机虽然有上岗证，由于缺少监督和复核手段，实际工作中违规严重。

Mechanical DesignAbstract:A machine is a combination of mechanisms and other components which transforms, transmits. Examples are engines, turbines, vehicles, hoists, printing presses, washing machines, and movie cameras. Many of the principles and methods of design that apply to machines also apply to manufactured articles that are not true machines. The term "mechanical design" is used in a broader sense than "machine design" to include their design. the motion and structural aspects and the provisions for retention and enclosure are considerations in mechanical design. Applications occur in the field of mechanical engineering, and in other engineering fields as well, all of which require mechanical devices, such as switches, cams, valves, vessels, and mixers.Keywords: Mechanical Design ；Rules for Design ；Design ProcessThe Design ProcessDesigning starts with a need real.Existing apparatus may need improvements in durability, efficiency, weight, speed, or cost. New apparatus may be needed to perform a function previously done by men, such as computation, assembly, or servicing. With the objective wholly or partly.In the design preliminary stage, should allow to design the personnel fullyto display the creativity, not each kind of restraint. Even if has had many impractical ideas, also can in the design early time, namely in front of the plan blueprint is corrected. Only then, only then does not send to stops up the innovation the mentality. Usually, must propose several sets of design proposals, then perform the comparison. Has the possibility very much in the plan which finally designated, has used certain not in plan some ideas which accepts.When the general shape and a few dimensions of the several components become apparent, analysis can begin in earnest. The analysis will have as its objective satisfactory or superior performance, plus safety and durability with minimum weight, and a competitive cost. Optimum proportions and dimensions will be sought for each critically loaded section, together with a balance between the strengths of the several components. Materials and their treatment will be chosen. These important objectives can be attained only by analysis based upon the principles of mechanics, such as those of static for reaction forces and for the optimum utilization of friction; of dynamics for inertia, acceleration, and energy; of elasticity and strength of materials for stress and deflection; of physical behavior of materials; and of fluid mechanics for lubrication and hydrodynamic drives. The analyses may be made by the same engineer who conceived the arrangement of mechanisms, or, in a large company, they may be made by a separate analysis division or research group. Design is a reiterative and cooperative process, whetherdone formally or informally, and the analyst can contribute to phases other than his own. Product design requires much research and development. Many Concepts of an idea must be studied, tried, and then either used or discarded. Although the content of each engineering problem is unique, the designers follow the similar process to solve the problems.Product liability suits designers and forced in material selection, using the best program. In the process of material, the most common problems for five (a) don't understand or not use about the latest application materials to the best information, (b) failed to foresee and consider the reasonable use material may (such as possible, designers should further forecast and consider due to improper use products. In recent years, many products liability in litigation, the use of products and hurt the plaintiff accused manufacturer, and won the decision), (c) of the materials used all or some of the data, data, especially when the uncertainty long-term performance data is so, (d) quality control method is not suitable and unproven, (e) by some completely incompetent persons choose materials.Through to the above five questions analysis, may obtain these questions is does not have the sufficient reason existence the conclusion. May for avoid these questions to these questions research analyses the appearance indicating the direction. Although uses the best choice of material method not to be able to avoid having the product responsibility lawsuit, designs the personnel and the industry carries on the choice of material according to thesuitable procedure, may greatly reduce the lawsuit the quantity.May see from the above discussion, the choice material people should to the material nature, the characteristic and the processing method have comprehensive and the basic understanding.Finally, a design based upon function, and a prototype may be built. If its tests are satisfactory, the initial design will undergo certain modifications that enable it to be manufactured in quantity at a lower cost. During subsequent years of manufacture and service, the design is likely to undergo changes as new ideas are conceived or as further analyses based upon tests and experience indicate alterations. Sales appeal.Some Rules for DesignIn this section it is suggested that, applied with a creative attitude, analyses can lead to important improvements and to the conception and perfection of alternate, perhaps more functional, economical,and durable products.To stimulate creative thought, the following rules are suggested for the designer and analyst. The first six rules are particularly applicable for the analyst.1. A creative use of need of physical properties and control process.2. Recognize functional loads and their significance.3. Anticipate unintentional loads.4. Devise more favorable loading conditions.5. Provide for favorable stress distribution and stiffness with minimum weight.6. Use basic equations to proportion and optimize dimensions.7. Choose materials for a combination of properties.8. Select carefully, stock and integral components.9. Modify a functional design to fit the manufacturing process and reduce cost.10. Provide for accurate location and noninterference of parts in assembly.Machinery design covers the following contents.1. Provides an introduction to the design process , problem formulation ,safety factors.2. Reviews the material properties and static and dynamic loading analysis ,Including beam , vibration and impact loading.3. Reviews the fundamentals of stress and defection analysis.4. Introduces fatigue-failure theory with the emphasis on stress-life approaches to high-cycle fatigue design, which is commonly used in the design of rotation machinery.5. Discusses thoroughly the phenomena of wear mechanisms, surface contact stresses ,and surface fatigue.6. Investigates shaft design using the fatigue-analysis techniques.7. Discusses fluid-film and rolling-element bearing theory and application8. Gives a thorough introduction to the kinematics, design and stress analysis of spur gears , and a simple introduction to helical ,bevel ,and worm gearing.9. Discusses spring design including compression ,extension and torsion springs.10. Deals with screws and fasteners including power screw and preload fasteners.11. Introduces the design and specification of disk and drum clutches and brakes.Machine DesignThe complete design of a machine is a complex process. The machine design is a creative work. Project engineer not only must have the creativity in the work, but also must in aspect and so on mechanical drawing, kinematics, engineerig material, materials mechanics and machine manufacture technology has the deep elementary knowledge.One of the first steps in the design of any product is to select the material from which each part is to be made. Numerous materials are available to today's designers. The function of the product, its appearance, the cost of thematerial, and the cost of fabrication are important in making a selection. A careful evaluation of the properties of a. material must be made prior to any calculations.Careful calculations are necessary to ensure the validity of a design. In case of any part failures, it is desirable to know what was done in originally designing the defective components. The checking of calculations (and drawing dimensions) is of utmost importance. The misplacement of one decimal point can ruin an otherwise acceptable project. All aspects of design work should be checked and rechecked.The computer is a tool helpful to mechanical designers to lighten tedious calculations, and provide extended analysis of available data. Interactive systems, based on computer capabilities, have made possible the concepts of computer aided design (CAD) and computer-aided manufacturing (CAM). How does the psychologist frequently discuss causes the machine which the people adapts them to operate. Designs personnel''s basic responsibility is diligently causes the machine to adapt the people. This certainly is not an easy work, because certainly does not have to all people to say in fact all is the most superior operating area and the operating process. Another important question, project engineer must be able to carry on the exchange and the consultation with other concerned personnel. In the initial stage, designs the personnel to have to carry on the exchange and the consultation on the preliminary design with the administrative personnel, and is approved.This generally is through the oral discussion, the schematic diagram and the writing material carries on.If front sues, the machine design goal is the production can meet the human need the product. The invention, the discovery and technical knowledge itself certainly not necessarily can bring the advantage to the humanity, only has when they are applied can produce on the product the benefit. Thus, should realize to carries on before the design in a specific product, must first determine whether the people do need this kind of productMust regard as the machine design is the machine design personnel carries on using creative ability the product design, the system analysis and a formulation product manufacture technology good opportunity. Grasps the project elementary knowledge to have to memorize some data and the formula is more important than. The merely service data and the formula is insufficient to the completely decision which makes in a good design needs. On the other hand, should be earnest precisely carries on all operations. For example, even if places wrong a decimal point position, also can cause the correct design to turn wrongly.A good design personnel should dare to propose the new idea, moreover is willing to undertake the certain risk, when the new method is not suitable, use original method. Therefore, designs the personnel to have to have to have the patience, because spends the time and the endeavor certainlycannot guarantee brings successfully. A brand-new design, the request screen abandons obsoletely many, knows very well the method for the people. Because many person of conservativeness, does this certainly is not an easy matter. A mechanical designer should unceasingly explore the improvement existing product the method, should earnestly choose originally, the process confirmation principle of design in this process, with has not unified it after the confirmation new idea.外文论文翻译译文机械设计摘要：机器是由机械装置和其它组件组成的。