附录
外文资料
TEMPERATURE CONTROL
P. H. J. Ingham
Marketing Manager ,Eurotherm Ltd,Worthing,Sussex,UK
SUMMARY
Commercial plastic materials are organically based and are therefore heatsensitive .Accurate temperature control of melt processes such as injection moulding is therefore necessary if problems caused by thermal degradation are to be avoided. The injection moulding process is considered form a temperature controlriewpoint and some of the control methods or techniques are described.since it should not be forgotten that good temperature control can lend to materials and energy savings.
1 INTRODUTION
The injection moulding process is concerned with the efficient conversion of plastics raw material into moulded product of
acceptable standards.Some of ths parameters which determine acceptability are weight,dimensions,colour and stenght,all of which can be affected by the conditions under which the material is processed.Having established by the conditions for thwese parameters so as to deermine acceptability,limits can be set for the conditions under which the material is processed.One of the most important parameters contributing to the correct operation of an injection moulding machine is temperature.All plastics materials can be correctly processed only within a certain range of temperatures which varies from materialFor some mateials and mould types the band isvery small and for others it can be quite wide.
Any attempt to define the limits within which the product is acceptable determines the need for some form of control.There are a number of types of control which,if applied correctly,can lead to adequate performance.Significant material and energy savings can be achieved by correctly pplying the right type of control equipment.The reliability of the system and the degree of operator supervision required also depend very largely on the balance struck between initial cost and performance.
It is the purpose of this chapter to examine the injection moulding machine from a temperature control viewpoint and
to outline some of the control methods can be used ,together with advantages and disadvantages.
2 THE PROCESS
2.1 Machine Zoning
From a control viewpoint,an injection moulding machine consists of a number of zones (each equipped with a means of measauring the temperature) and a controller,which compares the measured value of the set-point and controls the heat input to the zone in such a way as to remove any different between the heat input to the zone in such a way as to remove any difference between the tow. Yu dividing the machine into a number of zones the different temperature requirements of different zones and their different heat input needs can most easily be met (Fig.1).
For this purpose a typical small machine may have three or four barrel zones and a nozzle one. The zones nearest to the material feed hopper are where the plastic is melted and thus require fairly large heat inputs. However, in the zones hearest to the nozzle, the heat produced, by the rise in pressure needed to force the plastic into the mould, means that relatively little additional heat input is requied when the
machine is running. Indeed, if the machine cycle very short, with some materials it may be that more heat is generated than required to maintain the temperature, which will then rise uncontrollably mless some form of additional cooling is applied.
2.2 Thermocpuple Location
Considering again the barrel zones:these consist of a metal arrel with wall thickness sufficient to withstand the high pressures produced during the mjection cycle. The most common form of heating is electrical and is ipplied using band heaters strapped around the barrel (Fig.2). A controller of any kind can only control the temperature at the point of measurement. Ideally this will be as deep into the barrel wall as possible, since it is the temperature of the plastic which is required and not that of the barrel. Plastic is a poor thermal conductor and depending on whether the net heat dow is into or out of the plastic, a thermocouple deep into the barrel wall will register a temperature above or below the actual temperature. If the measuring element is shallow or on the barrel surface, the difference between the measured and actual melt temperatures can be very large. For any given conditions of operation there will be a more or less fixed difference
between the melt and measured temperatures and acceptable produce may be produced. If ,however, the conditions, e.g. machine speed or ambient temperature, change, this may give rise to a melt temperature which does not result in the production of acceptable product. It is therefore important to place the thermocouple as close to the melt as possible , i.e. deep the barrel.
2.3 Temperature Overshoot
The resultant system of an electrical band heater strapped around a thick walled barrel with a deep thermocouple is typical of most plastics processing machinery and present a number of control problems. Not only must stable control be achieved during normal running of the machine but acceptable start-up performance must also be achieved. The machine must be brought to its normal operating temperature as quickly as possible and preferably with no overshoot. (Overshoot is said to occur if the temperature is rising or falling at such a rate as it reaches set-point that it does not stop there but continues past by some amount before returning towards set-point again; see Fig.4.)
The basic cause of temperature overshoot in the system is
multiple heattransfer lags, i.e. where the heat generated electrically first raises the temperature of the heater thermal mass and is then conducted from the second thermal mass to a third and so on, until the heat reaches the point of measurement which, as stated already, is as near as possible to the point in the process to be controlled.
In the simplest cast of multiple heat transfer only two thermal masses would be significantly involved, namely those of the heater and the load. If the thermal mass of each is about the same, this tends to represent about the worst case for overshoots (and hence controllability). Poor heat transfer from heater to load worsens the situation, since the heater temperature (during start-up, for example)can then become very much higher than the load temperature; when the power to the heater is cut off the final temperature reached (ignoring heat losses and assuming equal thermal masses for heater and load) will be the mean of their respective temperatures at the instant when the power is cut off. Thus ,the overshoot in load temperature increases as the heat transfer becomes worse.
A particularly bad case of overshoot (and controllability) occurs where heat is transferred through a considerable thickness of heat-conducting material. This is exactly the
situation which is presented by an injection machine barrel with deep set thermocouple. This sort of heat transfer represents in effect an infinite order multiple heat transfer: several minutes can elapse between switch-on of power and a significant change in thermocouple temperature. In fact the response has almost the appearance of a delay (i.e. transport lag ) although there is really a considerable difference between this heart-transfer lag and a true delay. During the time of the heart-transfer lag, heat is being fed into the barrel, so that even if the source of heat were switched off at the instant the deep thermocouple began to respond, the thermocouple temperature would continue to rise as the heat energy already fed in distributed itself evenly throughout the thickness of the barrel wall.
A large part of the total lag can in practice be caused by the heart-transfer lag which occurs with a resistance heater. From the heater element thermal mass, via electrical insulation, to the outer surface of the barrel. For the lag through the barrel wall(or for any similar from the heat transfer) doubling the heart-transfer distance results in four times the lag. Iron, from which most injection machines are made, is a rather poor material for heat transfer: for example similar lag are obtained
in aluminium and iron when the distance in aluminium is five times greater.
3. METHODS OF CONTROLLING TEMPERATURE
3.1 Measuring the Temperature
The first item in the control system to consider is the measuring element, of which there are tow basic electrical types: active and passive.
The active type are thermocouples. There are formed by the junction of tow dissimilar metals and give an output voltage proportional to the difference in temperature between the thermocouple and the point of measurement (Fig.3). The fact that the millivolt output of the thermocouple in relation to temperatures is non-linear and that it depends on a stable reference temperature for comparison purposes are factors ，Which must be taken into account in the controller. Thermocouples are very robust mechanically. (This is an obvious advantage in the environment of the moulding shop.) They also exhibit good repeatability from example to example of the same type. The two most common types used in plastic processing are both base metal thermocouples and these are nickel chrome/nickel aluminium (Type K) and iron/jconstantan (Type J).
The passive types rely on having a resistance which varies with temperature in a known manner and thus, when fed from a constant current upon temperature. Such elements do not require a reference temperature to be generated by the controller. The commonest are the platinum resistance thermometer (which occupies a larer volume than a thermocouple and is more fragile)and the thermistor(which operates on the same principle and has the same disadvantages).
The thermocouple is by far the most common measuring elcment used in practice. The siting of the thermocouple will depend upon the degree of control required, as will the choice of controller.
3.2 ON/OFF Control
The simplest form of controller provides ON/OFF control of load power. The measured temperature is compared with the set-point and if it is too low, power is applied to the load; if it is too high the power is switched off. In practice there will be a small amount of hysteresis in the controller (mainly so that spurious noise signals on the thermocouple and effects due to mains regulation should not result in rapid ON/OFF chattering
of the load power control relay). If the thermocouple and heater are in very close proximity, i.e. there is no appreciable lag, the temperature will cycle with an amplitude somewhat in excess of the controller hysteresis and with the natural period of the system. There will inevitably be some overshoot on start-up because full power will be applied to the load until the set and actual temperatures become equal and any stored energy in the heater will continue to be transferred to the load even after switch-off. It can be seen that if the thermocouple is deep in the barrel (thus measuring the melt temperature more closely) the system lags will be considerably increased and the temperature cycling will be of a longer period and will become much larger. Similar comments apply to the start-up overshoot.
Thus ,in the least demanding circumstances, an ON/OFF controller with a shallow thermocouple may give acceptable results. However, with the large heaters required to give short start-up overshoot will probably be unacceptable for all but the least demanding situations and will be worse if account is taken of correct siting of the thermocouple.
The natural period of the system results from a combination of heater power and location, sensor location, and the thermal mass of the system.
3.3 Proportional Control (P only)
If we take an ON/OFF controller and force the switching of the output within the controller itself (with variable mark: space ratio)at a rate which is higher than the natural period, then we have proportional control. As the measured temperature approaches the set temperature, the relay will switch off(for a short time) the power supplied to the load. This point, at which just less than full power is applied to the load, is the lower edge of the ‘proportional band’. As the actual temperature approaches the set temperature more closely, less and les power is applied to the load until, when the two become equal, the power input is zero. It is general for the proportional band to be downscale of the set-point, i.e. at set-point the power fed to the load is zer..
The proportional band is usually defined as a percentage of the controller set-point scale span. Since the power applied to the load is proportional to the error or difference between actual and measured temperature (a so-called error-actuated system),it follows that if any power is required to maintain the temperature there must be some error in the system. This error is known as offset or droop (Fig.5). Since, on start-up, the load
power will first be switched off at a temperature below the set-point, the resultant overshoot will be reduced. With a sufficiently large proportional band and sufficiently rapid cycling of the output pow er (compared to the system’s natural frequency) the oscillations in temperature will cease eventually. However, this does not necessarily mean that there will be no sart-up overshoot in temperature, but only that the subsequent oscillation will decay to zero amplitude.
英文翻译
注塑模的温度调节系统
商用塑料是最常用的，但它是热敏感性材料。如果说因热引起的问题是可以避免的，那么象注塑模中熔化过程中精确的温度控制就是有必要的。]
从温度控制的观点和一些控制方法和技术的角度来考虑（这些方法和技术因不应忘记而被叙述），好的温度控制能节约和热能。
一、介绍
注射模过程曾引起一次会议的讨论，这次会议为模制产品的塑料原材料制定了可行性标准。一些可行性参数是重量，尺寸，颜色和强度。所有这些参数都受材料制造环境的影响。为了决定其可行性，为这些参数已经建立了相应的公差。对注射机的正确操作起作用的众多参数中，最重要的一个参数是温度，所有的塑料产品的制造都只有在特定的温度范围内。
这个特定的温度范围因材料而异。一些材料的这个温度范围相当宽，而另一些材料的这个范围却相当窄。
为使产品在允许温度限制范围内，需要某些形式的温度控制。如果应用正确，这里有大量的类型能导致正确控制形式的操作。通过正确的应用控制设备。能节省贵重的塑料和能量。系统的现实性和操作者监管要求的程度，也很大程度上依赖于最新消耗，运输消耗，工作费用三者之间的平衡。
这章的目的是从温度控制的角度来检查注射模具和列举一些常用的温控方法以及其优点。
二、过程
2·1 模具的分类
从控制的角度来说，一个注射模具由许多分区和一个控制部分组成（每一个分区有一种测量温度的方法），控制器比较两者之间的不同测量价值和控制两者之间的不同，而用某种方法输入到这个分区的热移走。通过划分模具的分区，能使这些分区更容易认识，不同的分区，要求有不同的温度和不同的热输入（如图1）为了达到这个目的，一个典型的小模具就可以有3～4个桶型区和喷管区。这些离主流道衬套最近的区域是塑料要求熔化的地方。因此要求有相当大的热量进给。然而，在离主流道衬套最远的浇口处，通过增加注射压力，使塑料和浇口之间产生摩擦热。这意味着，当模具在工作时只需要相当小的热量输入。如果机器的循环周期非常短。某些材料在制造过程中比被要求的热量产生更多的热量，为了保持温度，就需要采用某些形式的冷却方式应用。2·2 热电偶的安装
再考虑这些桶型区：一个型腔应具有足够的壁厚。用以承受足够的压力。最平常的加工方法是电加热和使用一个带状的加热片贴在型腔周围（如图2），在任何类型的一个控制器都只能控制一个点的测量温度的测试，而且尽可能贴近型
腔。因为我们需要的是塑料的温度，而不是型腔的温度，塑料是热的不良导体。依靠纯热进去塑料，如果热电偶安放在型腔的表面或非常浅，那么测量值和实际值之间将会有非常大的差异。
任何给出的操作环境都或多或少的存在实际值和测量值之间的差异。然而如果环境变化，如模具的运动速度和周围的环境温度变化，这都可以影响到工件的熔化温度。因此，热电偶的安装位置要尽可能的靠近型腔的内壁。
2·3温度过调量
一个具有一个热电偶的加热片贴在一个深孔型腔的壁上。它的合模系统是最典型的塑料加工机械，而且存在着大量的控制问题，不仅在正常的模具工作期间必须完成稳定的控制，而且可行的合理的初始操作也必须完成机械可以在不用调节时尽可能完美而迅速地使它达到正常的操作温度（如果温度上升或下降，以某一频率。就是说它经过那点，但不停留在那点，而是在它返回那点时继续通过一定数量的点。在这种情况下，过量调节就出现了。如图4）
在系统中引起过量调节的基本原因是，多个热传导滞后等产生的残余热量。首先，引起受热物体的温度上升，然后，传递给第二个受热物体，同时使第二个物体温度上升，然后从第二个受热物体传递给第三个受热物体。以次类推直到热在传递过程中达到控制温度的点附近。
举一个最简单的多个热传递的例子，如果两个受热体，如果每个受热体都是一样的，那将是过调量中最糟的。一种情况，冲加热到装入的差的热传递使环境变糟，因为加热温度（如在开始时的温度）。将使最终装入温度远高于其本身。当加热电源切断时，最终温度就达到了。（忽略温度损失和假设加热热量和吸收热量相等）。这将意味着最终电源切断时，最终各方面的温度。因此，过调量作为过调量作为热传递在装入温度上升时变地更糟。
在特别糟的过调量（可控制）的情况出现在热传递通过热导体材料的深处，这是实际的环境。这个环境是一个具有深的安装电热偶的注射模具环境。这套热传递系统抽绘一个无限次续的多热传递系统的影响。在打开电源和在热电偶中的一次重要转变之间需要几分钟的时间。实际上，这反映的是一种延时的表现（如传导滞后），虽然热传导滞后和真正的延时之间存在着差异，在热传导滞后和真正的延时之间存在着差异，在热传导滞后的时间中，热进给到型腔，以至于热源被切断的瞬时深的热电偶开始反应，当热能已经进给通过整个型腔壁后来完全地分配本身。
总的滞后的大部分，可以是由于发生在热阻传导体的热传导滞后引起，热阻传导体从热的基本发热体，经过电隔离在型腔外表，因为滞后通过型腔壁（或任何一个类似的热传导）两倍的热传导距离而产生了四倍的滞后。大多数注射模具制造用的钢材对热传导是相当差的材料。举一个简单的例子：当在铝中的距离比在铁中大五倍时。在铁和铝中能得到相同的热滞后。
三、温度控制的方法
3·1温度的测量
在控制系统中，首先要考虑的一条是测量的元素，它有两种基本的电子测量类型：主动的和被动的类型。
主动类的是热电偶，它由两种不同金属片和一个外部电压组成。这个外部电压与热电偶和测量点之间的不同温度相称（如图3）；热电偶的毫伏输出电压与温度不成线性关系，它依赖一个作为比较目的的稳定的参考温度，这一事实都是在控制器里必须考虑的因素，热电偶具有相当强的机动性（这在模具工厂的环境中是相当有利的）。这些因素也表现好的重复性。从例子到相同的类型的例子，两个最常用在塑料加工过程的例子都是金属热电偶的基本组合材料，它们是
镍铬/镍铝合金（类型K）和钢/铜合金（类型J）。
无源类热电偶，存在一种阻力，这种阻力使温度不同于众所周知的那种方式。因此，当在恒流电源的作用下，这种阻力将产生电压，这个电压依赖于所通过的材料的温度。最常用的是铂阻热电偶（这种热电偶比以前讲的普通热电偶具有更大的容量，并且更容易碎。）和热敏电阻（它是用同样的原理进行工作具有同样多的不利条件）。
热电偶是在实践中被大量使用的最常用的测量工具。热电偶的定线将依赖于要求控制的度数和所选的温度控制器。3·2控制器的开关
控制器的最简单的形式提供负载电源开关的控制，测得的温度与安装点比较，假如温度太低，负载电源将参与工作，假如温度太高，负载电源见被切断，在实际中，在控制器中有一些磁滞现象。如果热电偶和加热器非常接近，那么这就不存在滞后，温度将以某种振动进行循环。这个振幅是由控制起的滞后和系统的自然周期引起，因为全功率的电源在要求的温度和实际温度相等之前一直提供负载，所以在开始时有一定的过调量是不可避免的。很明显，如果热电偶在型腔壁的深层（因此测量的熔化温度更接近）。系统的滞后增大，温度的循环周期将变长，振幅将变大，也同样在开始时有一个过调量。
因此，一个具有线的热电偶开/关控制器可以得出所接受到的结果，这是起码的要求。然而具有大的热电偶的开/关控制器要求有一个更短的启动时间。如果计算考虑了这个热电偶的正确安放位置，那么这个启动时间过短将可能是对于所有控制器来说是不接受和更糟的。除这起码的要求。
这套系统的自然时期来源于一个热电偶能量与位置的联合作用，传感器的位置和系统的热量集中区域三个因素。3·3比例的控制（仅仅是P的控制）
如果我们使用一个开/关控制器，并且迫使输出量转换。在控制器内部本身有一个频率，这个频率高于自然时期的，然后我们将要进行一个比例的控制问题。当测量的温度接近安放点的温度时，继电器将在短时间内切断提供负载电源，在比最大电源电压少一些的这个点是比例带的最低边缘，当实际温度接近安放点的温度时，越来越少的电源电压进给量，直到两者完全相同时，电源输入量将变成零。总的一句话来说，对于比例带到安放点呈降低的比例趋势。例如在安放点的电量进给为零。
比例带的定义就是一个控制器安放点的范围段的一个百分率。因为电源负载的误差是成比例的，或是实际温度与测量温度之间存在着差异（一个所谓的误差一个实际系统），这产生的后果将是假如任何电源要求保持温度，这将使在系统中产生某些错误，这个误差就是众所周知的偏差和下降（如图5）。然而在开始上升阶段，在温度还低于安放点时，负载电源将被关掉，短期内的结果将降低，用一个足够大的比例带和足够快的外部输出电压的循环（与系统本身的自然频率相比）温度的波动将最终停止。然而，这并不意味着这里没有上升的过调量，而仅仅只是意味着在此以后的波动将减小到振幅为零。
附：外文翻译 外文原文： Fundamentals of Mechanical Design Mechanical design means the 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. The total design process is of interest to us. How does it begin? Does the engineer simply sit down at his desk with a blank sheet of paper? And, as he jots down some ideas, what happens next? What factors influence or control the decisions which have to be made? Finally, then, how does this design process end? Sometimes, but not always, design begins when an engineer recognizes a need and decides to do something about it. Recognition of the need and phrasing it in so many words often constitute a highly creative act because the need may be only a vague discontent, a feeling of uneasiness, of a sensing that something is not right. The need is usually not evident at all. For example, the need to do something about a food-packaging machine may be indicated by the noise level, by the variations in package weight, and by slight but perceptible variations in the quality of the packaging or wrap. There is a distinct difference between the statement of the need and the identification of the problem. Which follows this statement? The problem is more specific. If the need is for cleaner air, the problem might be that of reducing the dust discharge from power-plant stacks, or reducing the quantity of irritants from automotive exhausts. Definition of the problem must include all the specifications for the thing that is to be designed. The specifications are the input and output quantities, the characteristics of the space the thing must occupy and all the limitations on t hese quantities. We can regard the thing to be designed as something in a black box. In this case we must specify the inputs and outputs of the box together with their characteristics and limitations. The specifications define the cost, the number to be manufactured, the expected life, the range, the operating temperature, and the reliability. There are many implied specifications which result either from the designer's particular environment or from the nature of the problem itself. The manufacturing processes which are available, together with the facilities of a certain plant, constitute restrictions on a designer's freedom, and hence are a part of the implied specifications. A small plant, for instance, may not own cold-working machinery. Knowing this, the designer selects other metal-processing methods which can be performed in the plant. The labor skills available and the competitive situation also constitute implied specifications. After the problem has been defined and a set of written and implied specifications has been obtained, the next step in design is the synthesis of an optimum solution. Now synthesis cannot take place without both analysis and optimization because the system under design must be analyzed to determine whether the performance complies with the specifications. The design is an iterative process in which we proceed through several steps, evaluate the results, and then return to an earlier phase of the procedure. Thus we may synthesize several components of a system, analyze and optimize them, and return to synthesis to see what effect this has on the remaining parts of the system. Both analysis and optimization require that we construct or devise abstract models of the system which will admit some form of mathematical analysis. We call these models
附录 科技译文： Numerical Control Numerical Control(NC) is a method of controlling the movements of machineComponents by directly inserting coded instructions in the form of numerical data(numbers and data ) into the system.The system automatically interprets these data and converts to output signals. These signals ,in turn control various machine components ,such as turning spindles on and off ,changing tools,moving the work piece or the tools along specific paths,and turning cutting fluits on and off. In order to appreciate the importer of numerical control of machines ,let’s briefly review how a process such as machining has been carried out traditionally .After studying the working drawing of a part, the operator sets up the appropriate process parameters(such as cutting speed ,feed,depth of cut,cutting fluid ,and so on),determines the sequence of operations to be performed,clamps the work piece in a workholding device such as chuck or collet ,and proceeds to make the part .Depending on part shape and the dimensional accuracy specified ,this approach usually requires skilled
附录一英文科技文献翻译 英文原文： Experimental investigation of laser surface textured parallel thrust bearings Performance enhancements by laser surface texturing (LST) of parallel-thrust bearings is experimentally investigated. Test results are compared with a theoretical model and good correlation is found over the relevant operating conditions. A compari- son of the performance of unidirectional and bi-directional partial-LST bearings with that of a baseline, untextured bearing is presented showing the bene?ts of LST in terms of increased clearance and reduced friction. KEY WORDS: ?uid ?lm bearings, slider bearings, surface texturing 1. Introduction The classical theory of hydrodynamic lubrication yields linear (Couette) velocity distribution with zero pressure gradients between smooth parallel surfaces under steady-state sliding. This results in an unstable hydrodynamic ?lm that would collapse under any external force acting normal to the surfaces. However, experience shows that stable lubricating ?lms can develop between parallel sliding surfaces, generally because of some mechanism that relaxes one or more of the assumptions of the classical theory. A stable ?uid ?lm with su?cient load-carrying capacity in parallel sliding surfaces can be obtained, for example, with macro or micro surface structure of di?erent types. These include waviness [1] and protruding microasperities [2–4]. A good literature review on the subject can be found in Ref. [5]. More recently, laser surface texturing (LST) [6–8], as well as inlet roughening by longitudinal or transverse grooves [9] were suggested to provide load capacity in parallel sliding. The inlet roughness concept of Tonder [9] is based on ??e?ective clearance‘‘ reduction in the sliding direction and in this respect it is identical to the par- tial-LST concept described in ref. [10] for generating hydrostatic e?ect in high-pressure mechanical seals. Very recently Wang et al. [11] demonstrated experimentally a doubling of the load-carrying capacity for the surface- texture design by reactive ion etching of SiC
外文出处： 《Exploiting Software How to Break Code》By Greg Hoglund, Gary McGraw Publisher : Addison Wesley Pub Date : February 17, 2004 ISBN : 0-201-78695-8 译文标题： JDBC接口技术 译文： JDBC是一种可用于执行SQL语句的JavaAPI（ApplicationProgrammingInterface应用程序设计接口）。它由一些Java语言编写的类和界面组成。JDBC为数据库应用开发人员、数据库前台工具开发人员提供了一种标准的应用程序设计接口，使开发人员可以用纯Java语言编写完整的数据库应用程序。 一、ODBC到JDBC的发展历程 说到JDBC，很容易让人联想到另一个十分熟悉的字眼“ODBC”。它们之间有没有联系呢？如果有，那么它们之间又是怎样的关系呢？ ODBC是OpenDatabaseConnectivity的英文简写。它是一种用来在相关或不相关的数据库管理系统（DBMS）中存取数据的，用C语言实现的，标准应用程序数据接口。通过ODBCAPI，应用程序可以存取保存在多种不同数据库管理系统（DBMS）中的数据，而不论每个DBMS使用了何种数据存储格式和编程接口。 1．ODBC的结构模型 ODBC的结构包括四个主要部分：应用程序接口、驱动器管理器、数据库驱动器和数据源。应用程序接口：屏蔽不同的ODBC数据库驱动器之间函数调用的差别，为用户提供统一的SQL编程接口。 驱动器管理器：为应用程序装载数据库驱动器。 数据库驱动器：实现ODBC的函数调用，提供对特定数据源的SQL请求。如果需要，数据库驱动器将修改应用程序的请求，使得请求符合相关的DBMS所支持的文法。 数据源：由用户想要存取的数据以及与它相关的操作系统、DBMS和用于访问DBMS的网络平台组成。 虽然ODBC驱动器管理器的主要目的是加载数据库驱动器，以便ODBC函数调用，但是数据库驱动器本身也执行ODBC函数调用，并与数据库相互配合。因此当应用系统发出调用与数据源进行连接时，数据库驱动器能管理通信协议。当建立起与数据源的连接时，数据库驱动器便能处理应用系统向DBMS发出的请求，对分析或发自数据源的设计进行必要的翻译，并将结果返回给应用系统。 2．JDBC的诞生 自从Java语言于1995年5月正式公布以来，Java风靡全球。出现大量的用java语言编写的程序，其中也包括数据库应用程序。由于没有一个Java语言的API，编程人员不得不在Java程序中加入C语言的ODBC函数调用。这就使很多Java的优秀特性无法充分发挥，比如平台无关性、面向对象特性等。随着越来越多的编程人员对Java语言的日益喜爱，越来越多的公司在Java程序开发上投入的精力日益增加，对java语言接口的访问数据库的API 的要求越来越强烈。也由于ODBC的有其不足之处，比如它并不容易使用，没有面向对象的特性等等，SUN公司决定开发一Java语言为接口的数据库应用程序开发接口。在JDK1．x 版本中，JDBC只是一个可选部件，到了JDK1．1公布时，SQL类包（也就是JDBCAPI）
外文翻译 专业机械设计制造及其自动化学生姓名刘链柱 班级机制111 学号1110101102 指导教师葛友华
外文资料名称： Design and performance evaluation of vacuum cleaners using cyclone technology 外文资料出处：Korean J. Chem. Eng., 23(6), (用外文写) 925-930 (2006) 附件： 1.外文资料翻译译文 2.外文原文
应用旋风技术真空吸尘器的设计和性能介绍 吉尔泰金，洪城铱昌，宰瑾李， 刘链柱译 摘要：旋风型分离器技术用于真空吸尘器 - 轴向进流旋风和切向进气道流旋风有效地收集粉尘和降低压力降已被实验研究。优化设计等因素作为集尘效率，压降，并切成尺寸被粒度对应于分级收集的50％的效率进行了研究。颗粒切成大小降低入口面积，体直径，减小涡取景器直径的旋风。切向入口的双流量气旋具有良好的性能考虑的350毫米汞柱的低压降和为1.5μm的质量中位直径在1米3的流量的截止尺寸。一使用切向入口的双流量旋风吸尘器示出了势是一种有效的方法，用于收集在家庭中产生的粉尘。 摘要及关键词：吸尘器; 粉尘; 旋风分离器 引言 我们这个时代的很大一部分都花在了房子，工作场所，或其他建筑，因此，室内空间应该是既舒适情绪和卫生。但室内空气中含有超过室外空气因气密性的二次污染物，毒物，食品气味。这是通过使用产生在建筑中的新材料和设备。真空吸尘器为代表的家电去除有害物质从地板到地毯所用的商用真空吸尘器房子由纸过滤，预过滤器和排气过滤器通过洁净的空气排放到大气中。虽然真空吸尘器是方便在使用中，吸入压力下降说唱空转成比例地清洗的时间，以及纸过滤器也应定期更换，由于压力下降，气味和细菌通过纸过滤器内的残留粉尘。 图1示出了大气气溶胶的粒度分布通常是双峰形，在粗颗粒（>2.0微米）模式为主要的外部来源，如风吹尘，海盐喷雾，火山，从工厂直接排放和车辆废气排放，以及那些在细颗粒模式包括燃烧或光化学反应。表1显示模式，典型的大气航空的直径和质量浓度溶胶被许多研究者测量。精细模式在0.18?0.36 在5.7到25微米尺寸范围微米尺寸范围。质量浓度为2?205微克，可直接在大气气溶胶和 3.85至36.3μg/m3柴油气溶胶。
Manufacturing Engineering and Technology—Machining Serope kalpakjian；Steven R.Schmid 机械工业出版社2004年3月第1版 20.9 MACHINABILITY The machinability of a material usually defined in terms of four factors: 1、Surface finish and integrity of the machined part; 2、Tool life obtained; 3、Force and power requirements; 4、Chip control. Thus, good machinability good surface finish and integrity, long tool life, and low force And power requirements. As for chip control, long and thin (stringy) cured chips, if not broken up, can severely interfere with the cutting operation by becoming entangled in the cutting zone. Because of the complex nature of cutting operations, it is difficult to establish relationships that quantitatively define the machinability of a material. In manufacturing plants, tool life and surface roughness are generally considered to be the most important factors in machinability. Although not used much any more, approximate machinability ratings are available in the example below. 20.9.1 Machinability Of Steels Because steels are among the most important engineering materials (as noted in Chapter 5), their machinability has been studied extensively. The machinability of steels has been mainly improved by adding lead and sulfur to obtain so-called free-machining steels. Resulfurized and Rephosphorized steels. Sulfur in steels forms manganese sulfide inclusions (second-phase particles), which act as stress raisers in the primary shear zone. As a result, the chips produced break up easily and are small; this improves machinability. The size, shape, distribution, and concentration of these inclusions significantly influence machinability. Elements such as tellurium and selenium, which are both chemically similar to sulfur, act as inclusion modifiers in
附录 INTEGRATION OF MACHINERY （From ELECTRICAL AND MACHINERY INDUSTRY）ABSTRACT Machinery was the modern science and technology development inevitable result, this article has summarized the integration of machinery technology basic outline and the development background .Summarized the domestic and foreign integration of machinery technology present situation, has analyzed the integration of machinery technology trend of development. Key word：integration of machinery ，technology，present situation ，product t，echnique of manufacture ，trend of development 0. Introduction modern science and technology unceasing development, impelled different discipline intersecting enormously with the seepage, has caused the project domain technological revolution and the transformation .In mechanical engineering domain, because the microelectronic technology and the computer technology rapid development and forms to the mechanical industry seepage the integration of machinery, caused the mechanical industry the technical structure, the product organization, the function and the constitution, the production method and the management system has had the huge change, caused the industrial production to enter into “the integration of machinery” by “the machinery electrification” for the characteristic development phase. 1. Integration of machinery outline integration of machinery is refers in the organization new owner function, the power function, in the information processing function and the control function introduces the electronic technology, unifies the system the mechanism and the computerization design and the software which constitutes always to call. The integration of machinery development also has become one to have until now own system new discipline, not only develops along with the science and technology, but also entrusts with the new content .But its basic characteristic may summarize is: The integration of machinery is embarks from the system viewpoint, synthesis community technologies and so on utilization mechanical technology, microelectronic technology, automatic control technology,
本科毕业论文(设计) 外文翻译 学院：机电工程学院 专业：机械工程及自动化 姓名：高峰 指导教师：李延胜 2011年05 月10日 教育部办公厅 Failure Analysis，Dimensional Determination And
Analysis，Applications Of Cams INTRODUCTION It is absolutely essential that a design engineer know how and why parts fail so that reliable machines that require minimum maintenance can be designed．Sometimes a failure can be serious，such as when a tire blows out on an automobile traveling at high speed．On the other hand，a failure may be no more than a nuisance．An example is the loosening of the radiator hose in an automobile cooling system．The consequence of this latter failure is usually the loss of some radiator coolant，a condition that is readily detected and corrected．The type of load a part absorbs is just as significant as the magnitude．Generally speaking，dynamic loads with direction reversals cause greater difficulty than static loads，and therefore，fatigue strength must be considered．Another concern is whether the material is ductile or brittle．For example，brittle materials are considered to be unacceptable where fatigue is involved． Many people mistakingly interpret the word failure to mean the actual breakage of a part．However，a design engineer must consider a broader understanding of what appreciable deformation occurs．A ductile material，however will deform a large amount prior to rupture．Excessive deformation，without fracture，may cause a machine to fail because the deformed part interferes with a moving second part．Therefore，a part fails(even if it has not physically broken)whenever it no longer fulfills its required function．Sometimes failure may be due to abnormal friction or vibration between two mating parts．Failure also may be due to a phenomenon called creep，which is the plastic flow of a material under load at elevated temperatures．In addition，the actual shape of a part may be responsible for failure．For example，stress concentrations due to sudden changes in contour must be taken into account．Evaluation of stress considerations is especially important when there are dynamic loads with direction reversals and the material is not very ductile． In general，the design engineer must consider all possible modes of failure，which include the following． ——Stress ——Deformation ——Wear ——Corrosion ——Vibration ——Environmental damage ——Loosening of fastening devices
使用高级分析法的钢框架创新设计 1．导言 在美国，钢结构设计方法包括允许应力设计法(ASD)，塑性设计法(PD)和荷载阻力系数设计法(LRFD)。在允许应力设计中，应力计算基于一阶弹性分析，而几何非线性影响则隐含在细部设计方程中。在塑性设计中，结构分析中使用的是一阶塑性铰分析。塑性设计使整个结构体系的弹性力重新分配。尽管几何非线性和逐步高产效应并不在塑性设计之中，但它们近似细部设计方程。在荷载和阻力系数设计中，含放大系数的一阶弹性分析或单纯的二阶弹性分析被用于几何非线性分析，而梁柱的极限强度隐藏在互动设计方程。所有三个设计方法需要独立进行检查，包括系数K计算。在下面，对荷载抗力系数设计法的特点进行了简要介绍。 结构系统内的内力及稳定性和它的构件是相关的，但目前美国钢结构协会（AISC）的荷载抗力系数规范把这种分开来处理的。在目前的实际应用中，结构体系和它构件的相互影响反映在有效长度这一因素上。这一点在社会科学研究技术备忘录第五录摘录中有描述。 尽管结构最大内力和构件最大内力是相互依存的（但不一定共存），应当承认，严格考虑这种相互依存关系，很多结构是不实际的。与此同时，众所周知当遇到复杂框架设计中试图在柱设计时自动弥补整个结构的不稳定（例如通过调整柱的有效长度）是很困难的。因此，社会科学研究委员会建议在实际设计中，这两方面应单独考虑单独构件的稳定性和结构的基础及结构整体稳定性。图28.1就是这种方法的间接分析和设计方法。
在目前的美国钢结构协会荷载抗力系数规范中，分析结构体系的方法是一阶弹性分析或二阶弹性分析。在使用一阶弹性分析时，考虑到二阶效果，一阶力矩都是由B1,B2系数放大。在规范中，所有细部都是从结构体系中独立出来，他们通过细部内力曲线和规范给出的那些隐含二阶效应，非弹性，残余应力和挠度的相互作用设计的。理论解答和实验性数据的拟合曲线得到了柱曲线和梁曲线，同时Kanchanalai发现的所谓“精确”塑性区解决方案的拟合曲线确定了梁柱相互作用方程。 为了证明单个细部内力对整个结构体系的影响，使用了有效长度系数，如图28.2所示。有效长度方法为框架结构提供了一个良好的设计。然而，有效长度方法的
Int J Interact Des Manuf(2011)5:103–117 DOI10.1007/s12008-011-0119-7 ORIGINAL PAPER Benchmarking of virtual reality performance in mechanics education Maura Mengoni·Michele Germani· Margherita Peruzzini Received:27April2011/Accepted:29April2011/Published online:27May2011 ?Springer-Verlag2011 Abstract The paper explores the potentialities of virtual reality(VR)to improve the learning process of mechanical product design.It is focused on the definition of a proper experimental VR-based set-up whose performance matches mechanical design learning purposes,such as assemblability and tolerances prescription.The method consists of two main activities:VR technologies benchmarking based on sensory feedback and evaluation of how VR tools impact on learning curves.In order to quantify the performance of the technol-ogy,an experimental protocol is de?ned and an testing plan is set.Evaluation parameters are divided into performance and usability metrics to distinguish between the cognitive and technical aspects of the learning process.The experi-mental VR-based set up is tested on students in mechanical engineering through the application of the protocol. Keywords Mechanical product design·Virtual reality·Experimental protocol·Learning curve· Mechanics education 1Introduction Modern society is dominated by continuous scienti?c and technical developments.Specialization has become one of the most important enablers for industrial improvement.As a result,nowadays education is more and more job-oriented and technical education is assuming greater importance.In this context both university and industry are collaborating to create high professional competencies.The?rst disseminates M.Mengoni(B)·M.Germani·M.Peruzzini Department of Mechanical Engineering, Polytechnic University of Marche, Via Brecce Bianche,60131Ancona,Italy e-mail:m.mengoni@univpm.it knowledge and innovative methods while the second pro-vides a practical background for general principles training. The main problem deals with the effort and time required to improve technical learning,while market competitiveness forces companies to demand young and high-quali?ed engi-neers in short time.Therefore,the entire educational process needs to be fast and ef?cient.Novel information technolo-gies(IT)and emerging virtual reality(VR)systems provide a possible answer to the above-mentioned questions.Some of the most important issues,in mechanical design?eld,are the investigation of such technologies potentialities and the evaluation of achievable bene?ts in terms of product design learning effectiveness and quality.While IT has been deeply explored in distance education,i.e.e-learning,VR still rep-resents a novelty. VR refers to an immersive environment that allows pow-erful visualization and direct manipulation of virtual objects. It is widely used for several engineering applications as it provides novel human computer interfaces to interact with digital mock-ups.The close connection between industry and education represents the starting point of this research. Instead of traditional teaching methods,virtual technolo-gies can simultaneously stimulate the senses of vision by providing stereoscopic imaging views and complex spatial effects,of touch,hearing and motion by respectively adopt-ing haptic,sound and motion devices.These can improve the learning process in respect with traditional teaching meth-ods and tools.The observation of students interpreting two-dimensional drawings highlighted several dif?culties:the impact evaluation of geometric and dimensional tolerances chains,the detection of functional and assembly errors,the recognition of right design solutions and the choice of the proper manufacturing operations.These limitations force tutors to seek for innovative technologies able to improve students’perception.