英文资料
Limits and Tolerances
The breakage of the machine spare parts ,generally always from the surface layer beginning of .The function of the product ,particularly its credibility and durable ,be decided by the quantity of spare parts surface layer to a large extent. Purpose that studies the machine to process the surface quantity be for control the machine process medium various craft factor to process the surface quantity influence of regulation, in order to make use of these regulations to control to process the process, end attain to improve the surface quantity, the exaltation product use the function of purpose .
The machine processes the surface quantity to use the influence of the function to the machine
(A) The surface quantity to bear to whet the sexual influence
1.Rough degree of surface to bear to whet the sexual influence
A just process vice-of two contact surfaces of good friction, the first stage is rough only in the surface of the peak department contact ,the actual contact area is much smaller than theoretical contact area, in contact with each other the peak of the units have very great stress, to produce actual contact with the surface area of plastic deformation, deformation and peak between the Department of shear failure, causing serious wear.
Parts wear may generally be divided into three stages, the initial stage of wear and tear, normal wear and tear all of a sudden intense phase of stage wear.
Parts of the surface roughness of the surface wear big impact. In general the smaller the value of surface roughness, wear better. However, surface roughness value is too small, lubricants difficult to store, contact between the adhesive-prone elements, wear it to increase. Therefore, the surface roughness of a best value, the value and parts of the work related to increased work load, the initial wear increased, the best rough surface is also increased.
2.Cold Working hardening the surface of the wear resistance
Processing the Cold Work hardening the surface of the friction surface layer of metal microhardness increase, it will generally improve the wear resistance. Cold Working but not a higher degree of hardening, wear resistance for the better, because too much will lead to hardening of the Cold Working excessive loose organization of
metal, even a crack and peeling off the surface of the metal, declined to wear resistance.
(B)The surface quality of the impact of fatigue strength
Metal hand alternating loads of fatigue after the damage occurred in parts often Chilled layer below the surface and, therefore parts of the surface quality of fatigue very influential.
1.Surface roughness on the impact of fatigue strength
In alternating load, the surface roughness of the Au-site easily lead to stress concentration, a fatigue crack, the higher the value of surface roughness, surface traces of Yu Shen Wen, Wen at the end of the radius smaller, anti-fatigue damage at the end of the more capacity Worse.
2.Residual stress, fatigue Cold Work hardening of the impact
Residual stress on the impact of large parts fatigue. Surface layer of residual stress fatigue crack will expand and accelerate the fatigue damage the surface layer and the residual stress can prevent fatigue crack growth, delaying the formation of fatigue damage.
(C)The surface quality of the corrosion resistance of the impact
Parts of the corrosion resistance to a large extent depends on the surface roughness. The higher the value of surface roughness, Au Valley accumulate on the more corrosive substances. Corrosion resistance of the more worse.
Surface layer of residual stress will produce stress corrosion cracking, lower parts of the wear-resistance, and the residual stress is to prevent stress corrosion cracking.
(D) The surface quality with quality
Rough surface will affect the value of the size of the co-ordination with the surface quality. The gap with rough value will increase wear and tear, increased space, with the requirements of the destruction of nature. For Fit, the assembly part of the process of convex surface-crowded peak times, the actual reduction of the surplus and reduce the support of the connection between the strength.
Dimensioning
The design of a machine includes many factors other than those of determining the loads and stresses and selecting the proper materials. Before construction or manufacture can begin, it is necessary to have complete assembly and detail drawings to convey all necessary information to the shop men. The designer frequently is called upon to check the drawings before they are sent to the shop. Much experience and
familiarity with manufacturing processes are needed before one can become conversant with all phases of production drawings.
Drawings should be carefully checked to see that the dimensioning is done in a manner that will be most convenient and understandable to the production departments. It is obvious that a drawing should be made in such a way that it has one and only one interpretation. In particular, shop personnel should not be required to make trigonometric or other involved calculations before the production machines can be set up.
Dimensioning is an involved subject and long experience is required for its mastery.
Tolerances must be placed on the dimensions of a drawing to limit the permissible variations in size because it is impossible to manufacture a part exactly to a given dimension. Although small tolerances give higher quality work and a better operating mechanism, the cost of manufacture increases rapidly as the tolerances are reduced, as indicated by the typical curve of Fig 14.1. It is therefore important that the tolerances be specified at the largest values that the operating or functional considerations permit.
Tolerances may be either unilateral or bilateral. In unilateral dimensioning, one tolerance is zero, and all the variations are given by the other tolerance. In bilateral dimensioning, a mean dimension is used which extends to the midpoint of the tolerance zone with equal plus and minus variations extending each way from this dimension.
The development of production processes for large-volume manufacture at low cost has been largely dependent upon interchangeability of component parts. Thus the designer must determine both the proper tolerances for the individual parts, The manner of placing tolerances on drawings depends somewhat on the kind of product or type of manufacturing process. If the tolerance on a dimension is not specifically stated, the drawing should contain a blanket note which gives the value of the tolerance for such dimensions. However, some companies do not use blanket notes on the supposition that if each dimension is considered individually, wider tolerance than those called for in the note could probably be specified. In any event it is very important that a drawing be free from ambiguities and be subject only to a single interpretation.
Dimension and Tolerance
In dimensioning a drawing, the numbers placed in the dimension lines represent dimension that are only approximate and do not represent any degree of accuracy unless so stated by the designer.
To specify a degree of accuracy, it is necessary to add tolerance figures to the dimension. Tolerance is the amount of variation permitted in the part or the total variation allowed in a given dimension. A shaft might have a nominal size of 2.5 in. (63.5mm), but for practical reasons this figure could not be maintained in manufacturing without great cost. Hence, a certain tolerance would be added and , if a variation of ±0.003 in.(±0.08mm) could be permitted, the dimension would be stated 2.500±0.003(63.5±0.008mm).
Dimensions given close tolerances mean that the part must fit properly with some other part. Both must be given tolerances in keeping with the allowance desired, the manufacturing processes available, and the minimum cost of production and assembly that will maximize profit. Generally speaking, the cost of a part goes up as the tolerance is decreased. If a part has several or more surfaces to be machined, the cost can be excessive when little deviation is allowed from the nominal size.
Allowance, which is sometimes confused with tolerance, has an altogether different meaning.
It is the minimum clearance space intended between mating parts and represents
the condition of tightest permissible fit. If a shaft, size 1.4980.0000.003+
-, is to fit a hole of
size 1.5000.0030.000+
-, the minimum size hole is 1.500 and the maximum size shaft is 1.498.
Thus the allowance is 0.002 and the maximum clearance is 0.008 as based on the minimum shaft size and maximum hole dimension.
Tolerances may be either unilateral or bilateral. Unilateral tolerance means that any variation is made in only one direction from the nominal or basic dimension.
Referring to the previous example, the hole is dimensioned 1.5000.0030.000+
-, which
represents a unilateral tolerance. If the dimensions were given as 1.500±0.003, the tolerance would be bilateral; that is , it would vary both over and under the nominal dimension. The unilateral system permits changing the tolerance while still retaining the same allowance or type of fit. With the bilateral system, this is not possible without also changing the nominal size dimension of one or both of the two mating parts. In mass production, where mating parts must be interchangeable, unilateral tolerances are customary. To have an interference or fore fit between mating parts, the tolerances must be such as to create a zero or negative allowance.
Tolerances Limits and Fits
The drawing must be a true and complete statement of the designer’s expr essed in such a way that the part is convenient to manufacture. Every dimension necessary to define the product must be stated once and repeated in different views. Dimensions relating to one particular feature, such as the position and size of hole, where possible, appear on the same view.
There should be no more dimensions than are absolutely necessary, and no feature should be located by more than one dimension in any direction. It may be necessary occasionally to give an auxiliary dimension for reference, possibly for inspection. When this is so, the dimension should be enclosed in a bracket and marked for reference. Such dimensions are not governed by general tolerances.
Dimensions that affect the function of the part should always be specified and not left as the sum or other dimensions. If this is not done, the total permissible variation on that dimension will form the sum or difference of the other dimensions and their tolerance, and this with result in these tolerances having to be made unnecessarily tight. The overall dimension should always appear.
All dimensions must be governed by the general tolerance on the drawing unless otherwise stated. Usually, such a tolerance will be governed by the magnitude of the dimension. Specific tolerances must always be stated on dimensions affecting or interchangeability.
A system of tolerances is necessary to allow for the variations in accuracy that are bound to occur during manufacture, and still provide for interchangeability and correct function of the part.
A tolerance is the difference in a dimension in order to allow for unavoidable imperfections in workmanship. The tolerance range will depend on the accuracy of the manufacturing organization, the machining process and the magnitude of the dimension. The greater the tolerance range is disposed on both sides of the nominal dimension. A unilateral tolerance is one where the tolerance zone is on one side only of the nominal dimension, in which case the nominal dimension may from one of the limits.
Limits are the extreme dimensions of the tolerance zone. For example, nominal dimension
30mm tolerance 30.0230.000++ limits 30.025
30.000
Fits depend on the relationship between the tolerance zones of two mating parts,
and may be broadly classified into a clearance fit with positive allowance, a transition fit where the allowance may be either positive or negative (clearance or interference) , an interference fit where the allowance is always negative.
Type of Limits and Fits
The ISO system of Limits and Fits, widely used in a number of leading metric countries, is considerably more complex than the ANSI system.
In this system, each part has a basic size. Each limit of part, high and sign being obtained by subtracting the basic size form the limit in question. The difference between the two limits of size of a part is called the tolerance, an absolute without sign.
There are three classes of fits: 1) clearance fits, 2) transition fits ( the assembly may have either clearance or interference ), and 3) interference fits .
Either a shaft-basis system or a hole-basis system may be used. For any given basic size, a range of tolerance and deviations may be specified with respect to be line of zero deviation, called the zero line. The tolerance is a function of the basic size and is designated by a number symbol, called the grade-thus the tolerance grade. The position of the tolerance with respect to the zero line also a function of the basic size-is indicated by a letter symbol(or two letter), a capital letter for holes and a lowercase letter for shafts. Thus the specification for a hole and shaft having a basic size of 45mm might be45H8/g7.
Twenty standard grades of tolerance are provided, called IT 01,IT 0 ,IT 1-18, providing numerical values for each nominal diameter, in arbitrary steps up to 500mm (for example 0-3,3-6,6-10…, 400-500mm). The value of the tolerance unit, I, for grades 5-16 is
=+
0.0.001
i D
Where i is in microns and D in millimeters.
Standard shaft and hole deviations similarly are provided by sets of formulas, However, for practical, both tolerances and deviations are provided in three sets of rather complex tables. Additional tables gives the values for basic sizes above 500mm and for “Commonly Used Shafts and Holes” in two categories ---“General Purpose” and “Fine Mecbanisms and Horology”.
中文翻译
极限与误差
机械零件的破坏，一般总是从表层开始的。产品的性能，尤其式它的可靠性和耐久性，在很在程度上取决于零件表层的质量。研究机械加工表面质量的目的就是为了掌握机械加工中各种工艺因素对加工表面质量影响的规律，以便运用这些规律来控制加工过程，最终达到改善表面质量、提高产品使用性能的目的。机械加工表面质量对机器使用性能的影响
（一）表面质量对耐磨性的影响
1.表面粗糙度对耐磨性的影响
一个刚加工好的摩擦副的两个接触表面之间，最初阶段只在表面粗糙度的峰部接触，实际接触面积远小于理论接触面积，在相互接触的峰部有非常大的单位应力，使实际接触表面积处产生塑性变形、弹性变形和峰部之间的剪切破坏，引起严重磨损。
零件磨损一般可分为三个阶段，初期磨损阶段、正常磨损阶段忽然剧烈磨损阶段。
表面粗糙度对零件表面磨损的影响很大。一般说表面粗糙度值越小，其磨损性越好。但表面粗糙度值太小，润滑油不易储存，接触面之间容易发生分子粘接，磨损反而增加。因此，接触面的粗糙度有一个最佳值，其值与零件的工作情况有关，工作载荷加大时，初期磨损量增大，表面粗糙最佳也加大。
2.表面冷作硬化对耐磨性的影响
加工表面的冷作硬化使摩擦副表面层金属的显微硬度提高，故一般可使耐磨性提高。但也不是冷作硬化程度愈高，耐磨性久愈好，这是因为过分的冷作硬化将引起金属组织过度疏松，甚至出现裂纹和表面金属的剥落，使耐磨性下降。（二）表面质量对疲劳强度的影响
金属手交变载荷作用后产生的疲劳破坏往往发生在零件表面和冷硬层下面，因此零件表面质量对疲劳强度影响很大。
1.表面粗糙度对疲劳强度的影响
在交变载荷作用下，表面粗糙度的凹谷部位容易引起应力集中，产生疲劳裂纹，表面粗糙度值愈大，表面的纹痕愈深，纹底半径愈小，抗疲劳破坏底能力就愈差。
2.残余应力、冷作硬化对疲劳强度的影响
残余应力对零件疲劳强度的影响很大。表面层残余拉应力将使疲劳裂纹扩
大，加速疲劳破坏；而表面层残余应力能够阻止疲劳裂纹的扩展，延缓疲劳破坏的产生。
（三）表面质量对耐蚀性的影响
零件的耐蚀性在很大程度上取决于表面粗糙度。表面粗糙度值愈大，则凹谷中聚积腐蚀性物质就愈多。抗蚀性就愈差。
表面层的残余拉应力会产生应力腐蚀开裂，降低零件的耐磨性，而残余应力则能防止应力腐蚀开裂。
尺寸标注
一个机构的设计除了要考虑载荷硬力和选择合适的条件外还包括许多因素。装配或制造之前必须完成装配图和零件图的绘制以便传递所有必要的信息给车间的工人。设计人员非常频繁的被叫检查图纸在这些图纸送到车间之前。要熟悉生产图样的所有情况，需要对制造过程非常熟悉并具有很多经验。
图纸应仔细被检查以便使尺寸标注在生产车间最方便和理解的方式下标注。非常明显图纸应在有一种且只有一种解释的方式下标注。特别是，在生产用机械能被调整好之前，车间工作人员不需要进行三角学或其他复杂的计算。
尺寸标注是一项复杂的工作，要熟悉它需要长期的实践经验。
公差必须标注在图纸尺寸的后面以便限制在尺寸方面的变动偏差，因为不可能知道一个在尺寸方面非常精确的零件。虽然小的公差产生高质量的产品和机器，但是随公差的减小制造成本快速增加，正如图典型曲线所示，因此公差的确定在能保证产品质量或功能下取最大值。
公差可能是单向的或双向的。在单向尺寸标注中一个公差是零，所有的偏差由另一个公差给出。在双向尺寸标注中，使用平均公差即上下偏差绝对值相等的公差带。
工艺制造流程发展大批量制造低成本依靠零部件的互换性。因此设计者必须确定包括单个零件的合适公差和确定装配零件公差是间隙或过盈。生产者把公差标注在图纸上依靠产品类型和制造工艺类型给出注释。如果尺寸公差没有特别注明，图样必须要一个给出这些尺寸的公差值的综合注释。然而一些生产者并不用综合注释假定每个尺寸是单独的被考虑的可能会规定出注释中要求的更宽的公差。在任何情况下非常重要的是图纸不能模棱两可和只能有一种解释。
尺寸和公差
在图样标注时，除非设计者有意标明，注在尺寸线上的数字表明的尺寸仅是近似的，并不代表任何精确的等级。为了明确尺寸等级，在尺寸后面加上公差等
级是必须的。公差是在某一零件上被允许的变化量或在尺寸上总的变化量。一个轴可能有一个名义尺寸2.5英尺，但由于实际操作原因它不能实现在花费大量制造成本。因此一个确定的公差将被加上，如果±0.003英尺的变化被允许，尺寸将标注为2.500±0.003。
尺寸标准给定小的公差意味着相应零件比其他零件更合适。配合的零件都必须保持渴望的允差值，制造过程有效，生产装配中实现最小成本和最大利率。一般的说，如果公差减小生产成本上升。如果一个零件有几个或多个面要生产，当要求小的偏差生产成本将急剧上升。
允差有时会和公差混淆，它具有完全不同的意义。允差是设计最小的公差空间在配合零件和代表最紧的配合条件下。如果一个轴尺寸为1.4980.000
0.003+-,与它配合的孔的尺寸1.5000.0030.000+-,最小孔为1.500和最大轴的尺寸为1.498。因此最大允差为0.002和最大间隙为0.008，在最小轴和最大孔尺寸的基础上。
公差可能是单边的或双边的。单边公差意味以前任何偏差只在名义尺寸的一个方向。如上面的例子，孔的尺寸标注为1.5000.0030.000+-,表示单边公差。如果尺寸标注为1.500±0.003,公差表示为双边的。单边系统允许公差值发生变化但依然能保持相同的允差或配合类型，对双边的公差系统，它是不可以的，如果配合零件中一个或两个名义标注尺寸发生变化。在大批量生产中配合必须满足互换性，单边公差是常用的。为了在配合零件有过盈或受力配合，公差必须产生一个零或负的允差。 公差极限和配合
图纸必须真实和完整反映设计者的意图在这样方法下零件方便于制造。每一个尺寸必须表达不同视图里尺寸至少且只能为一次。对于有特殊要求的尺寸，如既有尺寸大小位置和要求，把尺寸和位置最好标在同一视图里。
除绝对需要的尺寸之外，不应该再有更多的尺寸，而在任一方向上，只能在一个尺寸上注上特殊要求。在偶尔情况下给出一个辅助的尺寸作为参考，可能为检验时用。在这种情况下，尺寸应该用括号括起来，以便参考。这样的尺寸不标公差。
影响零件功能的尺寸必须总是明确的给出不能留下另外的尺寸。如果不直接标注，在这种尺寸可能产生总的变化将要有以下构成的，有其他尺寸和他们公差的和或差，而且这会导致这些不能不定得过紧。整体尺寸应该能表现出现。
在图纸上所有尺寸都有由一般公差来制定除非特别标明。一般，如一个公差被标注的尺寸数字的旁边。专门公差标注在影响尺寸功能或互换性必须专门标注公差。
公差系统是必须允许这样一种变化在制造过程中必须出现的精度变化，仍然提供互换性和功能真确的零件。
公差在不同尺寸上不同的是为了允许在制造上不可避免的缺陷。公差变化依赖制造机器的精度，加工过程和尺寸大小。公差范围越大，制造过程中成本越低。双边公差的公差带会以名义尺寸上下移动，单边公差的公差带只能在名义尺寸的一边变动，在这种情况下名义尺寸可能是一个极限尺寸。
极限是公差带最外边尺寸。如名义尺寸30mm公差带
30.025
30.000
+
+极限尺寸
30.025
30.000
。
配合依赖于两个配合零件公差带关系，可以分成公差为正的间隙配合，过渡配合它的允差可能是正值或负值，过盈配合它的允差总是负值。
极限和配合的种类
世界标准组织的极限和配合，广泛用在许多先进米制国家，它比英制标准体系更相当复杂。
在世界标准公差系统，每个零件有一个基本尺寸。每个零件有一个极限尺寸，上下偏差从基本尺寸分开，大小和符号是极限尺寸减去基本获得的。差值为零件的两个极限尺寸之差称为公差，它是没有符号的绝对值。
这里有三种配合：1）间隙配合2）过渡配合（此配合可组成过渡或过盈）和3）过盈配合。
任何一个基轴制或基孔制都有使用。任一给定基本尺寸，公差范围和偏差被标准化根据零偏差，这个零偏差称为零线。公差是体现基本尺寸的一个功能被一些数字符号设计，这些数字符号叫等级即公差等级。公差带位置相对零线的位置也是基本尺寸一个功能—用字母符号来表示，用大写字母表示孔和用小写字母表示轴。对有基本尺寸为45mm孔和轴的配合就可以写成45H8/g7。
规定了20种标准公差等级，即IT01，IT0，IT1-118，它们是在500mm 以内硬性划分的每一段（例如0-3，3-6，6-10，……,400-500mm）的基本尺寸都对应有不同的标准公差数值。基本公差单元值为i，公差等级为5-16是i单位为nm和D单位为mm.
通过一系列公式轴和孔基本偏差标准化，但是在实际应用下，公差和偏差被提供在三套复杂表格里。轴表给出基本尺寸在500mm以上和“通用的轴和孔”分成两个表---“一般用途”和“精密机械和钟表”。
外文翻译 英文原文 Belt Conveying Systems Development of driving system Among the methods of material conveying employed，belt conveyors play a very important part in the reliable carrying of material over long distances at competitive cost．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 for larger individual drives as well as multiple drives such as 3 drives of 750 kW for one belt(this is the case for the conveyor drives in Chengzhuang Mine)．The ability to control drive acceleration torque is critical to belt conveyors’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’s design. Due to the advances in conveyor drive control technology，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 technologies 1．1 Direct drives Full-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 for relatively low-power, simple-profile conveyors．With direct fu11-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
中英文资料对照外文翻译 机械设计 摘要： 机器由机械和其他元件组成的用来转换和传输能量的装置。比如：发动机、涡轮机、车、起重机、印刷机、洗衣机和摄影机。许多机械方面设计的原则和方法也同样适用于非机械方面。术语中的“构造设计”的含义比“机械设计”更加广泛，构造设计包括机械设计。在进行运动分析和结构设计时要把产品的维护和外形也考虑在机械设计中。在机械工程领域中，以及其它工程领域，都需要机械设备，比如：开关、凸轮、阀门、船舶以及搅拌机等。 关键词：设计流程设计规则机械设计 设计流程 设计开始之前就要想到机器的实用性，现有的机器需要在耐用性、效率、重量、速度，或者成本上得到改善。新的机器必需能够完全或部分代替以前人的功能，比如计算、装配、维修。 在设计的初级阶段，应该充分发挥设计人员的创意，不要受到任何约束。即使有一些不切实际的想法，也可以在设计的早期，即在绘制图纸之前被改正掉。只有这样，才不致于阻断创新的思路。通常,必须提出几套设计方案,然后进行比较。很有可能在这个计划最后指定使用某些不在计划方案内的一些想法的计划。 一般当产品的外型和组件的尺寸特点已经显现出来的时候，就可以进行全面的设计和分析。接着还要客观的分析机器性能、安全、重量、耐用性，并且成本也要考虑在内。每一个至关重要的部分要优化它的比例和尺寸，同时也要保持与其它组成部分的平衡。 选择原材料和工艺的方法。通过力学原理来分析和实现这些重要的特性，如稳定和反应的能量和摩擦力的利用，动力惯性、加速度、能量；包括材料的弹性强度、应力和刚度等物理特性，以及流体的润滑和驱动器的流体力学。设计的过程是一个反复与合作的过程，无论是正式的还是非正式的，对设计者来说每个阶段都很重要。。产品设计需要大量的研究和提升。许多的想法,必须通过努力去研究成为一种理念,然后去使用或放弃。
中等分辨率制备分离的 快速色谱技术 W. Clark Still,* Michael K a h n , and Abhijit Mitra Departm(7nt o/ Chemistry, Columbia Uniuersity,1Veu York, Neu; York 10027 ReceiLied January 26, 1978 我们希望找到一种简单的吸附色谱技术用于有机化合物的常规净化。这种技术是适于传统的有机物大规模制备分离，该技术需使用长柱色谱法。尽管这种技术得到的效果非常好，但是其需要消耗大量的时间，并且由于频带拖尾经常出现低复原率。当分离的样本剂量大于1或者2g时，这些问题显得更加突出。近年来，几种制备系统已经进行了改进，能将分离时间减少到1-3h，并允许各成分的分辨率ΔR f≥（使用薄层色谱分析进行分析）。在这些方法中，在我们的实验室中，媒介压力色谱法1和短柱色谱法2是最成功的。最近，我们发现一种可以将分离速度大幅度提升的技术，可用于反应产物的常规提纯，我们将这种技术称为急骤色谱法。虽然这种技术的分辨率只是中等（ΔR f≥），而且构建这个系统花费非常低，并且能在10-15min内分离重量在的样本。4 急骤色谱法是以空气压力驱动的混合介质压力以及短柱色谱法为基础，专门针对快速分离，介质压力以及短柱色谱已经进行了优化。优化实验是在一组标准条件5下进行的，优化实验使用苯甲醇作为样本，放在一个20mm*5in.的硅胶柱60内，使用Tracor 970紫外检测器监测圆柱的输出。分辨率通过持续时间（r）和峰宽（w,w/2）的比率进行测定的（Figure 1），结果如图2-4所示，图2-4分别放映分辨率随着硅胶颗粒大小、洗脱液流速和样本大小的变化。
Mechanical engineering 1.The porfile of mechanical engineering Engingeering is a branch of mechanical engineerig,it studies mechanical and power generation especially power and movement. 2.The history of mechanical engineering 18th century later periods,the steam engine invention has provided a main power fountainhead for the industrial revolution,enormously impelled each kind of mechznicalbiting.Thus,an important branch of a new Engineering –separated from the civil engineering tools and machines on the branch-developed together with Birmingham and the establishment of the Associantion of Mechanical Engineers in 1847 had been officially recognized.The mechanical engineering already mainly used in by trial and error method mechanic application technological development into professional engineer the scientific method of which in the research,the design and the realm of production used .From the most broad perspective,thedemend continuously to enhance the efficiencey of mechanical engineers improve the quality of work,and asked him to accept the history of the high degree
机械设计理论 机械设计是一门通过设计新产品或者改进老产品来满足人类需求的应用技术科学。它涉及工程技术的各个领域，主要研究产品的尺寸、形状和详细结构的基本构思，还要研究产品在制造、销售和使用等方面的问题。 进行各种机械设计工作的人员通常被称为设计人员或者机械设计工程师。机械设计是一项创造性的工作。设计工程师不仅在工作上要有创造性，还必须在机械制图、运动学、工程材料、材料力学和机械制造工艺学等方面具有深厚的基础知识。如前所诉，机械设计的目的是生产能够满足人类需求的产品。发明、发现和科技知识本身并不一定能给人类带来好处，只有当它们被应用在产品上才能产生效益。因而，应该认识到在一个特定的产品进行设计之前，必须先确定人们是否需要这种产品。 应当把机械设计看成是机械设计人员运用创造性的才能进行产品设计、系统分析和制定产品的制造工艺学的一个良机。掌握工程基础知识要比熟记一些数据和公式更为重要。仅仅使用数据和公式是不足以在一个好的设计中做出所需的全部决定的。另一方面，应该认真精确的进行所有运算。例如，即使将一个小数点的位置放错，也会使正确的设计变成错误的。 一个好的设计人员应该勇于提出新的想法，而且愿意承担一定的风险，当新的方法不适用时，就使用原来的方法。因此，设计人员必须要有耐心，因为所花费的时间和努力并不能保证带来成功。一个全新的设计，要求屏弃许多陈旧的，为人们所熟知的方法。由于许多人墨守成规，这样做并不是一件容易的事。一位机械设计师应该不断地探索改进现有的产品的方法，在此过程中应该认真选择原有的、经过验证的设计原理，将其与未经过验证的新观念结合起来。 新设计本身会有许多缺陷和未能预料的问题发生，只有当这些缺陷和问题被解决之后，才能体现出新产品的优越性。因此，一个性能优越的产品诞生的同时，也伴随着较高的风险。应该强调的是，如果设计本身不要求采用全新的方法，就没有必要仅仅为了变革的目的而采用新方法。 在设计的初始阶段，应该允许设计人员充分发挥创造性，不受各种约束。即使产生了许多不切实际的想法，也会在设计的早期，即绘制图纸之前被改正掉。只有这样，才不致于堵塞创新的思路。通常，要提出几套设计方案，然后加以比较。很有可能在最后选定的方案中，采用了某些未被接受的方案中的一些想法。
普通钻床改造为多轴钻床 目前，我国中、小型企业的产品质量和生产效率都需要有一个新的提高, 但是加工手段却远远不能满足需要, 许多中小型企业都结合自己的实际对设备的技术状态进行改进，通过强化自身, 以求自我发展普通钻床为单轴机床，但安装上多轴箱就会成为多轴的钻床，改造成多轴钻床后，能大大地缩短加工时间，提高生产效率。 多轴加工应用：据统计，一般在车间中普通机床的平均切削时间很少超过全部工作时间的15%。其余时间是看图、装卸工件、调换刀具、操作机床、测量以及清除铁屑等等。使用 数控机床虽然能提高85%，但购置费用大。某些情况下，即使生产率高，但加工相同的零件，其成本不一定比普通机床低。故必须更多地缩短加工时间。不同的加工方法有不同的特点，就钻削加工而言，多轴加工是一种通过少量投资来提高生产率的有效措施。 多轴加工优势：虽然不可调式多轴头在自动线中早有应用，但只局限于大批量生产。即使采用可调式多轴头扩大了使用范围，仍然远不能满足批量小、孔型复杂的要求。尤其随着工业的发展，大型复杂的多轴加工更是引人注目。例如原子能发电站中大型冷凝器水冷壁管板有15000个“ 20孔，若以摇臂钻床加工，单单钻孔与锪沉头孔就要842.5小时，另外还要 划线工时151.1 小时。但若以数控八轴落地钻床加工，钻锪孔只要171.6 小时，划线也简单，只要1.9 小时。因此，利用数控控制的二个坐标轴，使刀具正确地对准加工位置，结合多轴加工不但可以扩大加工范围，而且在提高精度的基础上还能大大地提高工效，迅速地制造出原来不易加工的零件。有人分析大型高速柴油机30 种箱形与杆形零件的2000 多个钻孔操作中，有40%可以在自动更换主轴箱机床中用二轴、三轴或四轴多轴头加工，平均可减少20%的加工时间。1975年法国巴黎机床展览会也反映了多轴加工的使用愈来愈多这一趋势。 多轴加工的设备：多轴加工是在一次进给中同时加工许多孔或同时在许多相同或不同工件上各加工一个
机械类外文翻译 塑料注塑模具浇口优化 摘要:用单注塑模具浇口位置的优化方法，本文论述。该闸门优化设计的目的是最大限度地减少注塑件翘曲变形，翘曲，是因为对大多数注塑成型质量问题的关键，而这是受了很大的部分浇口位置。特征翘曲定义为最大位移的功能表面到表面的特征描述零件翘曲预测长度比。结合的优化与数值模拟技术，以找出最佳浇口位置，其中模拟armealing算法用于搜索最优。最后，通过实例讨论的文件，它可以得出结论，该方法是有效的。 注塑模具、浇口位臵、优化、特征翘曲变形关键词: 简介 塑料注射成型是一种广泛使用的，但非常复杂的生产的塑料产品，尤其是具有高生产的要求，严密性，以及大量的各种复杂形状的有效方法。质量ofinjection 成型零件是塑料材料，零件几何形状，模具结构和工艺条件的函数。注塑模具的一个最重要的部分主要是以下三个组件集:蛀牙，盖茨和亚军，和冷却系统。拉米夫定、Seow(2000)、金和拉米夫定(2002) 通过改变部分的尼斯达到平衡的腔壁厚度。在平衡型腔充填过程提供了一种均匀分布压力和透射电镜,可以极大地减少高温的翘曲变形的部分～但仅仅是腔平衡的一个重要影响因素的一部分。cially Espe,部分有其功能上的要求,其厚度通常不应该变化。 pointview注塑模具设计的重点是一门的大小和位臵,以及流道系统的大小和布局。大门的大小和转轮布局通常被认定为常量。相对而言,浇口位臵与水口大小布局也更加灵活,可以根据不同的零件的质量。 李和吉姆(姚开屏,1996a)称利用优化流道和尺寸来平衡多流道系统为multiple 注射系统。转轮平衡被形容为入口压力的差异为一多型腔模具用相同的蛀牙,也存
附录1 中文名称：机械加工中心英文名称：machining center 其他名称：自动换刀数控机床 定义：能自动更换工具，对一次装夹的工件进行多工序加工的数控机床。机械加工中心,简称cnc，是由机械设备与数控系统组成的使用于加工复杂形状工件的高效率自动化机床。加工中心又叫电脑锣。加工中心备有刀库，具有自动换刀功能，是对工件一次装夹后进行多工序加工的数控机床。加工中心是高度机电一体化的产品，工件装夹后，数控系统能控制机床按不同工序自动选择、更换刀具、自动对刀、自动改变主轴转速、进给量等，可连续完成钻、镗、铣、铰、攻丝等多种工序，因而大大减少了工件装夹时间、测量和机床调整等辅助工序时间，对加工形状比较复杂，精度要求较高，品种更换频繁的零件具有良好的经济效果。按控制轴数可分为：（1）三轴加工中心 （2）四轴加工中心 （3）五轴加工中心。 项目二机械加工中心设备技术分类加工中心的品种、规格较多，这里仅从结构上对其作一分类。 一、立式加工中心指主轴轴线为垂直状态设置的加工中心。其结构形式多为固定立柱式，工作台为长方形，无分度回转功能，适合加工盘、套、板类零件。一般具有三个直线运动坐标，并可在工作台上安装一个水平轴的数控回转台，用以加工螺旋线零件。立式加工中心装夹工件方便，便于操作，易于观察加工情况，但加工时切屑不易排除，且受立柱高度和换刀装置的限制，不能加工太高的零件。立式加工中心的结构简单，占地面积小，价格相对较低，应用广泛。 二、卧式加工中心指主轴轴线为水平状态设置的加工中心。通常都带有可进行分度回转运动的工作台。卧式加工中心一般都具有三个至五个运动坐标，常见的是三个直线运动坐标加一个回转运动坐标，它能够使工件在一次装夹后完成除安装面和顶面以外的其余四个面的加工，最适合加工箱体类零件。卧式加工中心调试程序及试切时不便观察，加工时不便监视，零件装夹和测量不方便，但加工时排屑容易，对加工有利。与立式加工中心相比，卧式加工中心的结构复杂，占地面积大，价格也较高。
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 resulfurized steels. Phosphorus in steels has two major effects. It strengthens the ferrite, causing
A Distributed Approach for Track Occupancy Detection Abstract This paper investigates the problem of track occupancy detection in distributed settings. Track occupancy detection determines which tracks are occupied in a railway system. For each track, the Neyman–Pearson structure is applied to reach the local decision. Globally, it is a multiple hypotheses testing problem. The Bayesian approach is employed to minimize the probability of the global decision error. Based on the prior probabilities of multiple hypotheses and the approximation of the prior probabilities of multiple hypotheses and the approximationofthereceiving operation characteristic curve of the local detector, a person-by-person optimization method is implemented to obtain the fusion rule and the local strategies off line. The results are illustrated through an example constructed from in situ devices. Key Words:Track occupancy detection,Neyman–Pearson, Generalized likelihood ratio test, Bayesian approach,Distributed detection 1Introduction With respect to the majority of railway systems in China, a quasi-moving block method is employed to specify the safe zone of a train. A key piece of knowledge to be determined is the set of track segments that are occupied, i.e., track occupancy detection. Then the speed restriction curves for the following trains are calculated accordingly. When there are misdetections, collisions may happen; additionally, false alarms may lead to declines of line capacity. Track occupancy detection is achieved by a set of track circuits. The track circuit is a crucial device mainly composed of a transmitter–receiver pair and a track segment. The measurement is the receiving signal at the end of the track. For each segment, a decision is made locally and individually, which leads to frequent ambiguities on which tracks are occupied for the whole line. It means that the false alarm rate of the line increases greatly. Besides, for the next generation of railway systems, a moving block method is adopted. Such a method requires the exact position and velocity of the train. However, those data are not provided in the current detection mechanism.
中国地质大学长城学院 本科毕业论文外文资料翻译 系别：工程技术系 专业：机械设计制造及其自动化 姓名：郝晓蒂 学号： 05211429 2015年 4 月 3 日
History Of The Snowblower So who did invent the snowblower or snowthrower? We need to begin by qualifying that question since there are a number of answers depending on your interest. Some notable firsts would be: ●The first machine to clear snow by throwing or blowing it ●The first fully mobile snow clearing machine? ●The first domestic walk-behind snow blower The latter is the one people generally think of and have the most interest in. It is also the one that has the most elusive answer. Chapter 1 So where did it all begin? Looking back in time we need to consider where would there be a need to remove snow while having a source of power available? The need and the enabling power were found on the railways of the U.S. snowbelt and in Canada. The earliest documented art belongs to a Toronto dentist known as J/W Elliot. His 1869 patent #390 design was never built. The story next takes us to Orangeville Ontario, Canada where we find Orange Jull, a gristmill operator and inventor. In 1884 he applied for a patent and was subsequently granted patent #18506. Jull did not have the means to build and commercialize his invention so he contracted the local Leslie brothers to build the machines. The Jull/Leslie machines were self powered but not self propelled. A locomotive was used to move the machine. The Jull design consisted of 2 large inline fans rotating in opposite directions. The lead fan chewed into and pulverized the snow while blowing it back into the discharge fan, which propelled it into the sky. Due to clogging problems it was simplified to a single fan. Further changes to effectively control the discharge were made including a movable deflector and pitching impeller blades. Production was moved to the Cook locomotive works in several locations. Additional machines were built under license. Finally 5 machines were "home built" by end users with the last one finished in 1971. In all 146 were built. Later work consisted of fortifying the design to deal with the hazards of the unknown. Tracks were often blocked with fallen trees and other debris that were concealed in the snow. Legend has it that in one case a herd of cattle were trapped and buried under the snow on the rail bed. As the rotary snowplow progressed forward beefsteaks were flying. They remained in production into the 1950s and a few are still in service today. Many survive as museum pieces with an occasional demonstration. Following his collaboration with the Leslie Brothers Orange Jull went on to create a next generation machine. This design utilized a screw auger to collect the snow. It was not as effective,
Machine design theory The machine design is through designs the new product or improves the old product to meet the human need the application technical science. It involves the project technology each domain, mainly studies the product the size, the shape and the detailed structure basic idea, but also must study the product the personnel which in aspect the and so on manufacture, sale and use question. Carries on each kind of machine design work to be usually called designs the personnel or machine design engineer. 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. 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 product Must 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
近几年，我厂和英国、西班牙的几个公司有业务往来，外商传真发来的图纸都是英文标注，平时阅看有一定的困难。下面把我们积累的几点看英文图纸的经验与同行们交流。 1标题栏 英文工程图纸的右下边是标题栏（相当于我们的标题栏和部分技术要求），其中有图纸名称（TILE）、设计者（DRAWN）、审查者（CHECKED）、材料（MATERIAL）、日期（DATE）、比例（SCALE）、热处理（HEAT TREATMENT）和其它一些要求，如： 1)TOLERANCES UNLESS OTHERWISE SPECIFIAL 未注公差。 2)DIMS IN mm UNLESS STATED 如不做特殊要求以毫米为单位。 3)ANGULAR TOLERANCE±1°角度公差±1°。 4)DIMS TOLERANCE±0.1未注尺寸公差±0.1。 5)SURFACE FINISH 3.2 UNLESS STATED未注粗糙度3.2。 2常见尺寸的标注及要求 2.1孔（HOLE）如： （1）毛坯孔：3"DIAO+1CORE 芯子3"0+1; （2）加工孔：1"DIA1"; （3）锪孔：锪孔(注C＇BORE=COUNTER BORE锪底面孔); （4）铰孔：1"/4 DIA REAM铰孔1"/4; （5）螺纹孔的标注一般要表示出螺纹的直径，每英寸牙数（螺矩）、螺纹种类、精度等级、钻深、攻深，方向等。如： 例1.6 HOLES EQUI-SPACED ON 5"DIA (6孔均布在5圆周上（EQUI-SPACED=EQUALLY SPACED均布） DRILL 1"DIATHRO＇ 钻1"通孔（THRO＇=THROUGH通） C/SINK22×6DEEP 沉孔22×6 例2.TAP7"/8-14UNF-3BTHRO＇ 攻统一标准细牙螺纹，每英寸14牙，精度等级3B级 （注UNF=UNIFIED FINE THREAD美国标准细牙螺纹） 1"DRILL 1"/4-20 UNC-3 THD7"/8 DEEP 4HOLES NOT BREAK THRO钻 1"孔，攻1"/4美国粗牙螺纹，每英寸20牙，攻深7"/8,4孔不准钻通（UNC=UCIFIED COARSE THREAD 美国标准粗牙螺纹）
Title: Modelling of transport costs and logistics for on-farm milk segregation in New Zealand dairying Material Source: Computers and Electronics in Agriculture Author: A. E. Dooley, Parker, H. T. Blair Abstract On-farm milk segregation to keep milk with high value properties separate from bulk milk will affect transport logistics. Separate milk collection, either as independent runs for different milk types,or storage of distinct milk types in the truck and trailer units, may increase the length and number of runs required. Two contrasting regions,with different farm sizes and roading networks were modelled,at two stages of lactation over 20 years. Thirty farms in each region were modelled with 0, 25, 50 and 100% of farms per region changing milk types over a transition period of up to 18 years. Genetic algorithm software was used to search for the order of the farm milk collection pick-ups which gave an optimal, least cost solution for milk collection for each prescribed set of inputs. Milk collection costs within scenario were variable over time depending on the amounts of the different milk types, increasing whenever another run was required, then decreasing over time as the milk load increased. Milk collection cost is small relative to milk income, with the status quo (SQ) cost for milk collection being less than NZ$9.61/kl for the North Island and NZ$13.53/kl for the South Island farm sets. The increased transport costs associated with collecting two milk types ranged from 4.5 to 22.0% more for the different scenarios. The extra cost to an average size North Island farm changing systems (25% farms changing), compared to an equivalent status quo farm, would be between NZ$307 and NZ$1244 per year. Fewer farms changing to differentiated milk production increased the costs per kilolitre of differentiated milk. Keywords: Milk transport; Scheduling; Milk segregation; Collection costs 1.Introduction