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机械工程英语原文+翻译

机械工程英语原文+翻译
机械工程英语原文+翻译

Unit 6 Injection Molding

Injection molding (Fig 6.1) is the predominant process for fabrication of thermoplastics into finished forms, and is increasingly being used for thermosetting plastics, fiber-filled composites, and elastomers.

It is the process of choice for tremendous variety of parts ranging in weight from 5g to 85g. It is estimated that 25% of all thermoplastics molded. If newer modification, such as reaction injection molding, and the greatly increased rate of adoption of plastics as substitutes for metals are considered, it is likely that the worldwide industrial importance of injection molding will continue to increase. Currently, probably close to half of all major processing units is injection molding machines. In 1988, a dollar sale of new injection molding machinery in the U.S. was approximately 65% of total major polymer machinery sales volume; this included 4,600 injection molding units. The machines and their products are ubiquitous and are synonymous with plastics for many people.

A reciprocating screw injection molding machine combines the functions of extruder and a compressive molding press. It takes solid granules of thermoplastic resin, melts and pressurizes them in the extruder section, forces the melt at high velocity and pressure through carefully designed flow channels a cooled mold, then ejects the finished part(s), and automatically recycles. This machine is a descendant of the plunger type “stuffing machine” patented by the Hyatt brothers in 1872 to mold celluloid. In 1878, th e Hyatts developed the first multicavity mold, but it was not until 1938 that Quillery (France) patented a machine incorporating a screw to plasticize the elastomer being molded. In 1956, Ankerwerk Nuremberg commercialized the modem reciprocating screw injection molding machine for thermoplastics. Today, over 50 machine manufacturers are listed in Modern Plastics Encyclopedia, offering machines to the U.S. market ranging from 2 to 6,000 tons clamping capacity. (A machine with a 10,000-ton capacity has been built to mold 264-gallon HDPE trash containers.) A host of suppliers of auxiliary equipment, molds, instruments, and controls service this major segment of the polymer industry.

Injection molding is particularly worthy of intensive study because it combines many areas of interest extrusion, mold design, rheology, sophisticated hydraulic and electronic controls, robotic accessories, design of complex products, and, of course, the integration of materials science and process engineering. The objectives of injection molding engineers are simple enough: to obtain minimum cycle time with minimum scrap, to attain specified product performance with assurance, to minimize production costs due to downtime or any other reasons, and to steadily increase in expertise and competitiveness. Profit margins for

custom injection molders are said to be generally skimpy; an established way to improve profits is to be selected for more demanding, higher margin jobs demand the highest level of efficiency and competence.

This text will concentrate on the reciprocating screw machine thermoplastics, which has largely replaced the older reciprocating plunger types except for very small-capacity machines.

Injection Molding Materials

It is not possible to injection-mold all polymers. Some polymers like PTFE (Poly-tetre-fluoro-ethylene), cannot be made to flow freely enough to make them suitable for injection molding. Other polymers, such as a mixture to resin and glass fiber in woven or mat form, are unsuitable by their physical nature for use in the process. In general, polymers which are capable of being brought to a state of fluidity can be injection-molded.

The vast majority of injection molding is applied to thermoplastic polymers. This class of materials consists of polymers which always remain capable of being softened by heat and of hardening on cooling, even after repeated cycling. This is because the long-chain molecules of the material always remain as separate entities and do not from chemical bonds to one another. An analogy car, be made to a block of ice that can be softened (i.e. turned back to liquid), poured into any shape cavity, and then cooled to become a solid again. This property differentiates thermoplastic materials from thermosetting ones. In the latter type of polymer, chemical bonds are formed between the separate molecule chains during processing. In this case the chemical bonding referred to as cross linking is the hardening mechanism.

In general, most of the thermoplastic materials offer high impact strength, corrosion resistance, and easy processing with good flow characteristics for molding complex designs. Thermoplastic are generally divided into two classes: namely crystalline and amorphous. Crystalline polymers have an ordered molecular arrangement, with a sharp melting point. Due to the ordered arrangement at molecules, the crystalline polymers reflect most incidents light and generally appear opaque. They also undergo a high shrinkage or reduction in volume during solidification. Crystalline polymers usually are more resistant to organic solvents and have good fatigue and wear-resistant properties. Crystalline polymers also generally are denser and have better mechanical properties than amorphous polymers. The main exception to this ruler is polycarbonate, which is the amorphous polymer of choice for high-quality transparent molding, and has excellent mechanical properties.

The mechanical properties of thermoplastics, while substantially lower than those of metals, can be enhanced for some applications through the addition of glass fiber reinforcement. This takes the form of short-chopped fibers, a few millimeters in length, which are rsndomly mixed with the thermoplastic resin.

The fibers occupy up to one third of the material volume to considerably improve the material strength and stiffness. The negative effect of this reinforcement is usually a decrease in impact strength and an increase in abrasiveness. The latter also has an effect on processing since the life of the mold cavity reduced from1,000,000 parts for plain resin parts to about 300,000 for glass-filled parts.

Perhaps the main weakness of injection-molded parts is the relatively low service temperatures to which they can be subjected. Thermoplastic components an only rarely be operated continuously above 250℃, with an absolute upper service temperature of about 400℃. The temperature at which a thermoplastic can be operated under load can be defined qualitatively by the heat deflection temperature. This is the temperature at which a simply supported beam specimen of the material, with a centrally applied load, reaches a predefined. The temperature value obviously depends upon the conditions of the test and the allowed deflection and for this reason, the test value are only really useful for comparing different polymers.

Cycle of Operation

The reciprocating screw injection molding machine is considered as consisting of two: a fixed injection side, and a movable clamp side. The injection side-contain the extruder that receives solid resin in pellet or granular form and converts it into a viscous liquid or melt that can be forced through the connecting nozzle, spine, and runners to the gates that lead into the mold cavities. The mold is tightly clamped against injection pressure and is cooled well below the melt temperature of the thermoplastic. When the parts in the cavities have cooled sufficiently the mold halves are opened at the mold parting plane and the parts ejected by a knockout system drop into a receiving bin below. This summarizes the overall cycle, but leaves out much vital detail that is necessary for understanding the process. However, with this introduction, it is possible to understand the advantages and disadvantages of the process.

Effects of Process Variables on Orientation

In injection molding, any variation in processing that keeps the molding resin hot throughout filling allows increased and, therefore, decreased orientation. Some of the steps

that can be taken to reduce orientation are as follows.

Faster injection (up to a point): less cooling during filling, hence a thinner initial frozen layer, lower viscosity due to shear thinning; better flow to corners; and less crystallinity all favor lower subsurface orientation. The primary effect is that the gate will freeze more quickly. At that point, orientation stops and relaxation starts.

Higher melt and mold temperature: lower melt viscosity, easier filling, and greater relaxation favor reduced orientation.

Reduced packing time and pressure: overpacking inhibits relaxation processes.

Reduce gate size: larger gates take longer to freeze off and permit increased orientation.

Excessively high injection speed can cause high surface orientation and increase susceptibility to stress cracking. For example, molding that are to be electroplated, and will be subject to acid solutions during plating, must be made using very slow injection speeds to minimized surface orientation. On the other hand, the transverse motion component of the melt front in most molding can cause transverse subsurface orientation superimposed on the primary orientation, giving a desirable biaxial orientation effect.

Orientation can be seriously increased by obstruction to flow during filling of the cavity. Flow around an obstruction causes a decrease in melt front speed and leads to high local viscosity and reduced relaxation. This is also likely to occur near the end of the filling phase if gating is inadequate.

The molder must recognize the dangers of excessive fill speed, insufficient injection pressure, excessive melt temperature, and inadequate packing. These dangers are weighed against the opposing effects on orientation discussed above. Thicker parts delay cooling and increase relaxation time and tend to result in lower orientation. Thicker parts also tend to warp less. Therefore, a minimum wall thickness can be established by experience for various shapes, materials, and process combinations. Lower molecular weight broader molecular weigh distribution in thermoplastic favor lower orientation and reduced internal stress in moldings.

The skin thickness ratio is affected by process variables in the same way as one would predict for the orientation; that is, it decrease as the melt for mold temperatures and cavity pressure increases. Thensile strength and stiffness increase as skin thickness ratio increases. Microscopic examination thus provides another way of studying the process efficiently.

Advantages

1. High production rates. For example, a CD disk can be produced with a 10-12s cycle

in high melt flow index PC.

2. Relatively low labor content. One operator can frequently take care of two or more machines, particularly if the moldings are unloaded automatically onto conveyors.

3. Parts require little or no finishing. For example, flash can be minimized and molds can be arranged to automatically separate runners and gates from the part itself.

4. Very complex shapes can be formed. Advances in mold tooling are largely responsible.

5. Flexibility of design (finishes, colors, inserts, materials).More than one material can be molded through co-injection. Foam core materials with solid skins are efficiently produced. Thermosetting plastics and fiber-reinforced shapes are injection molded.

6. Minimum scrap loss. Runners, gates, and scrap can usually be reground. Recycled thermoplastics can be injection molded.

7. Close tolerances are obtainable. Modem microprocessor controls, fitted to precision molds, fitted to precision molds, and elaborate hydraulics, facilitate tolerances in the 0.1% range on dimensions and weights (but not without a high level of operational skills in constant attendance).

8. Makes best use of the unique attributes of polymers, such as flow ability, light weight, transparency, and corrosion resistance. This is evident from the number and variety of molded plastic products everyday use.

Disadvantages and Problems

1. High investment in equipment tools requires high production volumes.

2. Lack of expertise and good preventive maintenance can cause high startup and running costs.

3. Quality is sometimes difficult to determine immediately. For example, post-mold warpage may render parts unusable because of dimensional changes that are not completed for weeks or months after molding.

4. Attention is required on many details requiring a wide variety of skills and cross-disciplinary knowledge.

5. Part design sometimes is not well suited to efficient molding.

6. Lead time for mold design, mold manufacture and debugging trials is sometimes very long.

第六章注塑成型

注塑成型主要是将热塑性材料加工成半成品的过程,也越来越多地用于热固性塑料,纤维填充复合材料,弹性体的加工。

它主要加工重量在5g~85g之间形状不规则的产品。据估计大约有25%的热塑性材料成型,如果经过修改,如注射成型,可替代金属的热塑性材料,可能使注塑成型越来越广泛的被应用。现在被广泛采用的是注塑机。在美国,1988年新型注塑机的销售额占注塑机械总额的65%,大约有4600家注塑机生产厂家。机械和注塑产品无处不在,越来越多的人开始离不开注塑产品。

注射机是使塑料塑化和均化,并在很高的压力和较快的速度下,通过螺杆和柱塞的推挤将熔料注射入模具的成型机。它利用热塑性树脂的固体颗粒,挤出机的压力使他们融化,通过精心设计的熔体流道使之进入高流速和高压力的冷却模具内,完成成型过程,回收,然后过程循环。本机是1872年凯悦兄弟的后代塑造赛璐珞发明的一种柱塞式“馅机”机械。1878年,海厄茨开发了第一个多腔模具,但直到1938年Quillery(法国)发明了一种机器装有螺杆塑化成型但是没有弹性体的模具。1956年,Ankerwerk纽伦堡商品化调制解调器用于热塑性塑料螺杆往复式注塑机。今天,超过50家机制造商都列在现代塑料百科全书中,在美国生产的注塑机有2 6000吨锁模能力。(一个有10,000吨的能力已建机模具264加仑的高密度聚乙烯垃圾容器。)是关于辅助设备,模具,仪器仪表和控制这种聚合物服务行业的主要供应商。

注塑机值得深入研究,因为它结合了挤压工艺,模具设计,流体力学,精密液压和电子控制,机器人配置,复杂产品设计等许多领域,当然,也是材料学科和工艺技术的集成。注塑成型工程师的目标是很简单:在最小废料最小循环时间为前提的条件下,保证达到规定的产品性能,最大限度地减少生产成本,并逐步增加专业知识和竞争力。定制注塑商的利润通常说是少得可怜;必须用一个既定的方式来提高利润,追求更高利润、更大就业需求、更高效率和能力的最高水平。本文将主要介绍往复螺杆机热塑性塑料的注塑成型,它已在很大程度上取代小容量机器的类型,除了比较古老的大型往复柱塞式注塑机。

注塑成型的材料

注塑模具的材料不可能是聚合物,如聚四氟乙烯,由于这些聚合物不能作出足够的自由流动,使他们能够注塑成型。其他聚合物,如以树脂和玻璃纤维编织的混合物,是由于他们的物理性质不适合。所以一般来说,聚合物是没有流动性可以注塑成型状态的能力。

绝大多数的注塑材料都是热塑性聚合物。这种聚合物材料类,即使经过多次循环,它们仍有被加热软化和冷却硬化的能力。这是因为材料的长链分子始终作为独立的结构存在,然而化学键却未被破坏。例如,这种聚合物可以变成液体,浇成任何形状的空腔,然后冷却成为固体。这就是属性和热固性热塑性材料不同之处,在后一种类型的聚合物,化学键是在加工过程中形成独立的分子链。在这种情况下,化学键被称为交联,这就是是硬化的机制。

一般来说,大多数的热塑性材料具有高冲击强度,耐腐蚀,以及复杂的设计与良好的可塑性,流动特性强很容易处理。热塑性塑料一般分为两大类:即结晶和无定形。结晶聚合物具有排列的紧密的熔点分子序列。由于分子的有序排列,结晶聚合物的普遍表现为质轻和不透明。他们还出现在凝固过程中体积收缩率增加或减少。结晶聚合物通常更耐有机溶剂,具有良好的抗疲劳和耐磨损性能。结晶聚合物的密度也普遍比无定形聚合物高,有较好的力学性能。主要的例外是聚碳酸酯,它是为高品质透明无定形聚合物成型的主要选择,并具有优良的机械性能。

虽然热塑性塑料的机械性能比金属的低,但可以以采取措施增强玻璃纤维的含量,来强化裁量的机械性能。这是以短纤维的形式展现,长数毫米,这是与热塑性树脂随机混合形式。

该纤维占有体积不大,却能使材料的强度和刚度增强三分之一。这种负面影响通常是冲击强度降低,好处是耐磨性提高。后者对加工过程也有影响,因为模具腔的寿命从典型的普通树脂零件大约1,000,000件减少到玻璃纤维填充树脂零件的约300,000件。

也许,注塑件的主要缺点是工作时能承受的温度相对较低。热塑性塑料部件只有很少部分能连续运行250℃以上,400℃是绝大部分材料的温度上限。热塑性材料可根据负荷运行温度,将其定义为热变形温度。这是在温度达到了预定义,此种材料组成简支梁的中央载荷达到预定义,比较不同的聚合物后,材料允许挠度的测试的目的是用于说明温度值取决于测试值。

循环操作

往复式螺杆注塑机被认为是由两个部分人能组成:一个是固定的注射,一个是可移动的夹子。在注射侧挤出机接收包含在颗粒或粒状的固体树脂,并将其转换成一种粘性液体,或使其熔化,可通过连接喷嘴,首先进入到高温高压的模具腔内。模具是紧紧闭合目的使注射压力和冷却温度远低于热塑性熔体的温度。当零件在腔内充分冷却时,剖分模在模具分模面处打开,推出系统将零件推出落入下面的接收容器内。这概括了整个循环,这概述了整个循环,但省略了许多对理解此工艺所必需的很重要细节。所以通本章介绍,了解这种工艺的优缺点仍是必要的。

加工变量对方向性的影响

在注塑成型时,整个填料过程始终保持成型树脂的高温,任何加工变化都会增加松弛作用而使方向性减少。下面是可以用于减少方向性的若干措施。

较快注塑(到点):在填料过程中冷却较少,因此初始固化层较薄,由于剪应变稀少而粘性较低;能较好地流到角落;结晶度较小;所有这些促成表面下的方向性也较低。主要效果是闸道将较快固化。这样使得方向性停止产生而松弛作用开始增加。

较高的融化和成型温度:融化粘性较低,更容易填充,较大松弛作用促成方向性减少。

减少挤压时间和压力:过度挤压会抑制松弛过程。

减小闸道尺寸:闸道越大则固化时间越长并会使方向性增加。

过高的注塑速度会引起较高的表面方向性及增加应力破裂的敏感性。例如,要电镀的注塑件在电镀时会经受酸溶液,必须采用很低的注塑速度制造以使表面方向性最小化。另一方面,大多数注塑件的融化前部横向运动部分能导致在主要方向性上有层理的表面下横向方向性,产生需要的双轴方向性效应。

在填充模腔时流动受到阻碍会极大地增加方向性。围绕障碍物流动使融化前部的速度下降并产生较高的局部粘性而减少松弛作用。如果闸道不适当,这也很可能发生在接近填充结束阶段。

注塑工必须认识过快填充速度、不足注塑压力、过高融化温度和不充分挤压的危害性。这些危害性要与上述方向性的反向效应相权衡。较厚零件会延迟冷却并且增加松弛时间,趋向于导致较低的方向性。较厚零件也有助于减少翘曲。因此,对各种形状、材料和工艺组合能通过经验来确定最小壁厚。在热塑性塑料中较小的分子量以及较宽泛的分子量分布促成方向性减少同时降低注塑件中的内应力。

外壳厚度比受加工变量影响的方式与方向性预测一样;也就是它能随融化或成型温度及模腔压力的增加而减少。拉伸强度和硬度随外壳厚度比增加而增加。因而显微镜检查提供了有效研究该工艺的另一方法。

优点

1.高生产率:例如,一张CD盘在高融体流动指数生产控制中只需10~12s一个循环就能生产出来。

2.相对较少的工作内容:一个操作者经常可以照看两台以上机械,尤其是当成品能自动卸到输送机上时。

3.零件几乎不需要修整:例如,飞边可以最小化并且模具能被设计成自动将浇道和闸道从零件本身分离。

4.非常复杂的形状也能成型:模具的进步很大程度上是可靠的。

5.设计的灵活性(光洁度、颜色、插入物、材料):通过复合注塑可以成型多于一种材料。可以高效地生产带有固体外壳的泡沫型芯材料。热硬化性塑料和纤维加强形状都可以注塑成型。

6.废料损失最小化:浇道、闸道和废料通常可以重新研磨。循环热塑性塑料可以注塑成型。

7.能得到接近的公差:现代微处理器控制、合适的精密模具和精心制作的液压设备使得尺寸和重量的公差保持在0.1% 的范围内(但不是没有在持续照看时的高水平操作技能)。

8.充分利用聚合物诸如流动能力、重量轻、透明和耐腐蚀等独特属性:从日常使用成型塑料产品的数量和种类就能明显看到。

缺点和存在的问题

1.较高的设备和模具投资需要较高生产量才合算。

2.缺少专门技术和良好的预防性维修会导致较高的启动和运行成本。

3.质量有时难以马上确定。例如,成型后的翘曲会导致零件不能用,因为在成型后几星期甚至几个月尺寸变化都不能完成。

4.对许多需要广泛多样性技能和交叉学科知识的细节必须加以注意。

5.零件设计有时不能很好地适应有效率的成型。

6.模具设计、模具制造和调试试验这些先导工作有时要花费很长时间。

《机械工程专业英语教程》课文翻译

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机械工程英语翻译

Unit1 1、What is the difference between an alloy and a pure metal? Pure metals are elements which come from a particular area of the periodic table. Examples of pure metals include copper in electrical wires and aluminum in cooking foil and beverage cans. 合金与纯金属的区别是什么?纯金属是在元素周期表中占据特定位置的元素。例如电线中的铜和制造烹饪箔及饮料罐的铝。 Alloys contain more than one metallic element. Their properties can be changed by changing the elements present in the alloy. Examples of metal alloys include stainless steel which is an alloy of iron, nickel, and chromium; and gold jewelry which usually contains an alloy of gold and nickel. 合金包含不止一种金属元素。合金的性质能通过改变其中存在的元素而改变。金属合金的例子有:不锈钢是一种铁、镍、铬的合金,以及金饰品通常含有金镍合金。 2、 Why are metals and alloys used? Many metals and alloys have high densities and are used in applications which require a high mass-to-volume ratio. 为什么要使用金属和合金?许多金属和合金具有高密度,因此被用在需要较高质量体积比的场合。 Some metal alloys,such as those based on aluminum, have low densities and are used in aerospace applications for fuel economy. Many alloys also have high fracture toughness, which means they can withstand impact and are durable. 某些金属合金,例如铝基合金,其密度低,可用于航空航天以节约燃料。许多合金还具有高断裂韧性,这意味着它们能经得起冲击并且是耐用的。 3、The atomic bonding of metals also affects their properties. In m etals, the outer valence electrons are shared among all atoms, and ar e free to travel everywhere. Since electrons conduct heat and electri city, metals make good cooking pans and electrical wires. 金属的原子连结对它们的特性也有影响。在金属内部,原子的外层阶电子由所有原子共享并能到处自由移动。由于电子能导热和导电,所以用金属可以制造好的烹饪锅和电线。 It is impossible to see through metals, since these valence electrons absorb any photons of light which reach the metal. No photons pass through. 因为这些阶电子吸收到达金属的光子,所以透过金属不可能看得见。没有光子能通过金属. 4、Some of the useful properties of ceramics and glasses include high melting temperature, low density, high strength, stiffness, hardness, wear resistance, and corrosion resistance. 陶瓷和玻璃的特性高熔点、低密度、高强度、高刚度、高硬度、高耐磨性和

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1.机械设计过程 机械设计的最终目标是生产一种满足客户需求的有用产品,而且这种产品安全,高效,可靠,经济,实用。当回答这个问题时,广泛地思考,我将要设计的产品或系统的客户是谁? 在产品设计之前,了解所有客户的期望和期望是至关重要的。营销专业人员经常被用来管理客户期望的定义,但是设计师可能会把他们作为产品开发团队的一部分。 许多方法被用来确定客户想要什么。一种被称为质量功能部署或QFD的流行方法寻求(1)识别客户期望的所有特征和性能因素,以及(2)评估这些因素的相对重要性。QFD过程的结果是产品的一组详细功能和设计要求。 考虑设计过程如何配合为客户提供令人满意的产品所必须发生的所有功能以及在产品的整个生命周期中为产品提供服务也很重要。事实上,重要的是考虑产品在使用寿命后如何处置。影响产品的所有这些功能的总和有时被称为产品实现过程或PRP。PRP中包含的一些因素如下: ?营销功能来评估客户的要求 ?研究确定可在产品中合理使用的可用技术 ?可以包含在产品中的材料和组件的可用性 ?产品设计和开发 ?性能测试 ?设计文件 ?供应商关系和采购职能 ?考虑全球材料采购和全球营销 参加工作的技能 ?物理工厂和设施可用

?制造系统的能力 生产计划和生产系统的控制 ?生产支持系统和人员 ?质量体系要求 ?销售操作和时间表 ?成本目标和其他竞争性问题 ?客户服务要求 ?产品在生产,操作和处置过程中的环境问题 ?法律要求 ?金融资本的可用性 你可以添加到这个列表吗?您应该能够看到,产品的设计只是综合过程的一部分。在本文中,我们将更加注意设计过程本身,但必须始终考虑设计的可生产性。产品设计和制造过程设计的同时考虑通常被称为并行工程。 2.机械设计所需的技能 产品工程师和机械设计师在日常工作中使用广泛的技能和知识。这些技能和知识包含在以下内容中: ?素描,技术制图和计算机辅助设计 ?材料的性质?材料加工*和制造过程 ?化学的应用,如腐蚀防护,电镀和喷漆 静力学动力学材料的强度,运动学和机制 流体力学,热力学和传热 ?流体动力,电气现象的基本原理和工业控制

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1.我们可以把钢再次加热到临界温度以下的某一温度,然后在慢慢让其冷却。We can heat the steel again to a temperature below the critical temperature, then cool it slowly. 2.无论任何简单的机床,都是由单一元件即通称为机械零件或部件组成的。However simple, any machine is a combination of individual components generally referred to as machine elements or parts. 3.这些金属不都是好的导体。 All these metals are not good conductors. 4. 在做带电实验的时候,再怎么小心都不为过。 You can't be too careful in performing an experiment. 5.利用发电机可以把机械能转变成电能。 The mechanical energy can be changed back into electrical energy by means of a generator or dynamo. 6.假定电源输入的电压保持不变。 Assume that the voltage input of the power supply remains the same. 7.化石燃料是发电过程中最为频繁使用的能源。 Fossil fuels are most frequently used source daring the power generation process. 8单个机械零件的可靠性成为评估整台机器使用寿命的基本因素。 The individual reliability of machine elements becomes the basis for estimating the overall life 9.说我们生活在一个电子时代,这一点都不夸张。 It's no exaggeration to say that we live in an electronic age. 10.发动机的转速不应超过最大允许值。 Engine revolution should not exceed the maximum permissible. 11.如能从大型核电站获得成本极低的电力,电解氢的竞争能力就会增强。(Electrolytic hydrogen)。 If extremely low-cost power were ever to become available from large nuclear power plants, electrolytic hydrogen would become competitive. 12.电子技术提供了一种新的显示时间的方法。 A new way of displaying time has been given by electronics. 13.远距离输电需要高压,安全用电需要低压。 High voltage is necessary for long transmission line while low voltage for safe use. 14.铝的电阻大约是同等尺寸的铜的1.5倍。 The resistance of aluminum is approximately half again as great as that of copper for the same dimensions = size 15.In fact,it is impossible for no force to be exerted on a body,since in this world everything is subject to the for ce of gravity. 事实上,物体不受外力作用是不可能的,因为在这个世界上任何物体都要受到重力的作用。 16.In a thermal power plant,all the chemical energy is not

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陶瓷ceramics 合成纤维synthetic fibre 电化学腐蚀electrochemical corrosion 车架automotive chassis 悬架suspension 转向器redirector 变速器speed changer 板料冲压sheet metal parts 孔加工spot facing machining 车间workshop 工程技术人员engineer 气动夹紧pneuma lock 数学模型mathematical model 画法几何descriptive geometry 机械制图Mechanical drawing 投影projection 视图view 剖视图profile chart 标准件standard component 零件图part drawing 装配图assembly drawing 尺寸标注size marking 技术要求technical requirements 刚度rigidity 内力internal force 位移displacement 截面section 疲劳极限fatigue limit 断裂fracture 塑性变形plastic distortion 脆性材料brittleness material 刚度准则rigidity criterion 垫圈washer 垫片spacer 直齿圆柱齿轮straight toothed spur gear 斜齿圆柱齿轮helical-spur gear 直齿锥齿轮straight bevel gear 运动简图kinematic sketch 齿轮齿条pinion and rack 蜗杆蜗轮worm and worm gear 虚约束passive constraint 曲柄crank 摇杆racker 凸轮cams

机械工程专业英语 翻译

2、应力和应变 在任何工程结构中独立的部件或构件将承受来自于部件的使用状况或工作的外部环境的外力作用。如果组件就处于平衡状态,由此而来的各种外力将会为零,但尽管如此,它们共同作用部件的载荷易于使部件变形同时在材料里面产生相应的内力。 有很多不同负载可以应用于构件的方式。负荷根据相应时间的不同可分为: (a)静态负荷是一种在相对较短的时间内逐步达到平衡的应用载荷。 (b)持续负载是一种在很长一段时间为一个常数的载荷, 例如结构的重量。这种类型的载荷以相同的方式作为一个静态负荷; 然而,对一些材料与温度和压力的条件下,短时间的载荷和长时间的载荷抵抗失效的能力可能是不同的。 (c)冲击载荷是一种快速载荷(一种能量载荷)。振动通常导致一个冲击载荷, 一般平衡是不能建立的直到通过自然的阻尼力的作用使振动停止的时候。 (d)重复载荷是一种被应用和去除千万次的载荷。 (e)疲劳载荷或交变载荷是一种大小和设计随时间不断变化的载荷。 上面已经提到,作用于物体的外力与在材料里面产生的相应内力平衡。因此,如果一个杆受到一个均匀的拉伸和压缩,也就是说, 一个力,均匀分布于一截面,那么产生的内力也均匀分布并且可以说杆是受到一个均匀的正常应力,应力被定义为 应力==负载 P /压力 A, 因此根据载荷的性质应力是可以压缩或拉伸的,并被度量为牛顿每平方米或它的倍数。 如果一个杆受到轴向载荷,即是应力,那么杆的长度会改变。如果杆的初始长度L和改变量△L已知,产生的应力定义如下: 应力==改变长△L /初始长 L 因此应力是一个测量材料变形和无量纲的物理量 ,即它没有单位;它只是两个相同单位的物理量的比值。 一般来说,在实践中,在荷载作用下材料的延伸是非常小的, 测量的应力以*10-6的形式是方便的, 即微应变, 使用的符号也相应成为ue。 从某种意义上说,拉伸应力与应变被认为是正的。压缩应力与应变被认为是负的。因此负应力使长度减小。 当负载移除时,如果材料回复到初始的,无负载时的尺寸时,我们就说它是具有弹性的。一特定形式的适用于大范围的工程材料至少工程材料受载荷的大部分的弹性, 产生正比于负载的变形。由于载荷正比于载荷所产生的压力并且变形正比于应变, 这也说明,当材料是弹性的时候, 应力与应变成正比。因此胡克定律陈述, 应力正比于应变。 这定律服从于大部分铁合金在特定的范围内, 甚至以其合理的准确性可以假定适用于其他工程材料比如混凝土,木材,非铁合金。 当一个材料是弹性的时候,当载荷消除之后,任何负载所产生的变形可以完全恢复,没有永久的变形。

机械工程英语翻译unit 1

Types of Materials 材料的类型 Materials may be grouped in several ways. Scientists often classify materials by their state: solid, liquid, or gas. They also separate them into organic (once living) and inorganic (never living) materials. 材料可以按多种方法分类。科学家常根据状态将材料分为:固体、液体或气体。他们也把材料分为有机材料(曾经有生命的)和无机材料(从未有生命的)。 For industrial purposes, materials are divided into engineering materials or nonengineering materials. Engineering materials are those used in manufacture and become parts of products. 就工业效用而言,材料被分为工程材料和非工程材料。那些用于加工制造并成为产品组成部分的就是工程材料。Nonengineering materials are the chemicals, fuels, lubricants, and other materials used in the manufacturing process, which do not become part of the product. 非工程材料则是化学品、燃料、润滑剂以及其它用于加工制造过程但不成为产品组成部分的材料。 Engineering materials may be further subdivided into: ①Metal ②Ceramics ③Composite ④Polymers, etc. 工程材料还能进一步细分为:①金属材料②陶瓷材料③复合材料④聚合材料,等等。 Metals and Metal Alloys 金属和金属合金 Metals are elements that generally have good electrical and thermal conductivity. Many metals have high

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机械工程专业英语第二版必考翻译(完整版)

1.With low-power machinery or vehicles the operator can usually apply sufficient force through a simple mechanical linkage from the pedle or handle to the stationary part of the brake. In many cases, however, this force must be multiplied by using an elaborate braking system.(P5)用低能机器或传力工具,操作者通过向踏板或把手的一个简单机械连接构件作用足够的力量到车闸固定的部分。大多数情况,然而,用一个详细(复杂)的车闸系统使这个力量成倍增加。 2. The fundamental principle involved is the use of compressed air acting through a piston in a cylinder to set block brakes on the wheels. The action is simultaneous o n the wheels of all the cars in the train. The compressed air is carried through a strong hose from car to car with couplings between cars; its release to all the separate block brake units, at the same time, is controlled by the engineer. (Braking Systems)(P5) 相关的基本原理是使用压缩气体,通过气缸内的活塞将闸块压在车轮起作用。列车的所有车厢上的车轮同时动作。压缩气体通过一个坚固的管道在由联轴器连接的车厢之间传输;工程师控制其在同一时间释放到所有独立的闸块单元。 3.When the brake pedal of an automobile is depressed, a force is applied to a piston in a master cylinder. The piston forces hydraulic fluid through metal tubing into a cylinder in each wheel where the fluid’s pressure moves two pistons that press the brake shoes against the drum. (Braking Systems)(P5) 当踩下汽车刹车的踏板,在主汽缸中的活塞上施加一个力。活塞驱动液压流体通过金属管道进入每个车轮气缸,在那里液压移动两个活塞将闸片压向轮圈。 4.Machinery ontology including mechanical rack, mechanical connections and mechanical transmission, which is the basis of mechanical-electrical integration, plays a role in supporting the other functional units of the system and transmitting motion and power. Compared to purely mechanical products, the performance and functionality of integration technology in electrical and mechanical systems have been improved a lot, which requires mechanical ontology to adapt its new status in mechanical structure, materials, processing technology, as well as the areas of geometry. Accordingly, the new ontology is with high efficient, multi-functional, reliable and energy-saving, small, light-weighted and aesthetically pleasing characteristics. (Mechatronics System) (P7) 机械体包括机架、机械联接和机械传动,它是机电一体化的基础,作用是支撑系统其他功能单元,传递运动和动力。和纯机械产品相比,一体化技术的性能和功能在机电系统中大幅提高,它要求机械本体适应在机械结构、材料、加工技术以及这些领域中的几何学下的新环境。相应的,新的一体化具有高效、多功能、可靠、节能、小轻和美学的令人赏心悦目的特征。 5. Detecting sensor detecting sensor part includes a variety of sensors and signal detection circuit, and its function is to detect the process of mechatronic systems in the work itself and the changes of relevant parameters in external environment and transmit the information to the electronic control unit. Electronic control unit check the information and sends the corresponding control issues to the actuator. (Mechatronics System) (P7) 检测传感器部分包括各类传感器、信号检测电路,它的功能是检测机电系统自身工作的工程,在外部环境下的相关参数的改变,将其信息传给电子控制单元。电子控制单元通过检查信息,送出相应的指令到执行机构。 6. Electronic control unit, also known as ECU, is the core of mechatronic systems, responsible for the external commands and the signals output by sensors. It centralizes stores, computes and analyzes the information. Based on the results of information processing,instruction are issued according to a certain extent and pace to control the destination for the entire system. (Mechatronics System) (P7) 电子控制单元,也被称为控制单元(ECU)控制,是机电系统的核心,负责外部命令和传感器的信号输出。它集中、存储、计算并分析信息。基于信息处理的结果,按照一定的范围和步调发出命令来实现控制整个系统的目标。 7. It is put into a fairly standard machine tool that has had position sensing and motors on the

机械专业术语英文翻译

机械专业英语词汇 陶瓷ceramics 合成纤维synthetic fibre 电化学腐蚀electrochemical corrosion 车架automotive chassis 悬架suspension 转向器redirector 变速器speed changer 板料冲压sheet metal parts 孔加工spot facing machining 车间workshop 工程技术人员engineer 气动夹紧pneuma lock 数学模型mathematical model 画法几何descriptive geometry 机械制图Mechanical drawing 投影projection 视图view 剖视图profile chart 标准件standard component 零件图part drawing 装配图assembly drawing 尺寸标注size marking 技术要求technical requirements 刚度rigidity 内力internal force 位移displacement 截面section 疲劳极限fatigue limit 断裂fracture 塑性变形plastic distortion 脆性材料brittleness material 刚度准则rigidity criterion 垫圈washer 垫片spacer 直齿圆柱齿轮straight toothed spur gear 斜齿圆柱齿轮helical-spur gear 直齿锥齿轮straight bevel gear 运动简图kinematic sketch 齿轮齿条pinion and rack 蜗杆蜗轮worm and worm gear 虚约束passive constraint 曲柄crank 摇杆racker

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机械英语词汇大全2 金属切削 metal cutting 机床 machine tool 金属工艺学 technology of metals 刀具 cutter 摩擦 friction 联结 link 传动 drive/transmission 轴 shaft 弹性 elasticity 频率特性 frequency characteristic 误差 error 响应 response 定位 allocation 拉孔 broaching 装配 assembling 铸造 found 流体动力学 fluid dynamics 流体力学 fluid mechanics 加工 machining 液压 hydraulic pressure 切线 tangent 机电一体化 mechanotronics mechanical-electrical integration 气压 air pressure pneumatic pressure 稳定性 stability 介质 medium 数学模型 mathematical model 画法几何 descriptive geometry 机械制图 Mechanical drawing 投影 projection 视图 view 剖视图 profile chart 标准件 standard component 零件图 part drawing 装配图 assembly drawing 尺寸标注 size marking 技术要求 technical

机床夹具 jig 动力学 dynamic 运动学 kinematic 静力学 static 分析力学 analyse mechanics 拉伸 pulling 压缩 hitting 剪切 shear 扭转 twist 弯曲应力 bending stress 强度 intensity 三相交流电 three-phase AC 磁路 magnetic circles 变压器 transformer 异步电动机 asynchronous motor 液压驱动泵 fluid clutch 液压泵 hydraulic pump 阀门 valve 失效 invalidation 强度 intensity 载荷 load 应力 stress 安全系数 safty factor 可靠性 reliability 螺纹 thread 螺旋 helix 键 spline 销 pin 滚动轴承 rolling bearing 滑动轴承 sliding bearing requirements 刚度 rigidity 内力 internal force 位移 displacement 截面 section 疲劳极限 fatigue limit 断裂 fracture 塑性变形 plastic distortion 脆性材料 brittleness material 刚度准则 rigidity criterion 垫圈 washer 垫片 spacer 直齿圆柱齿轮

机械工程专业英语参考译文

机械工程专业英语》参考译文 高等学校机械设计制造及其自动化专业新编系列教材(供教师及学生使用) 黄运尧黄威 司徒忠李翠琼 武汉理工大学出版社 目录编译者的话……………………………… 第1章材料和热加工………………… 第1课机械学的基本概念………… 第2课塑性理论的基本假设……… 第3课有限元优化的应用………… 第4课金属………………………… 第5课金属和非金属材料………… 第6课塑料和其他材料…………… 第7课模具的寿命和失效………… 第8踩冷加工和热加工…………… 第9踩铸造………………………… 第10课制造中的金属成形工艺… 第11课缎选……………………… 第12课锻造的优点和工作原理… 第13课焊接……………………… 第14课热处理…………………… 第二章机构和机器原理……………。 第15课机构介绍…………………。 第16课运动分析…………………. 第l7课运动的综合………………— 第18课凸轮和齿轮………………— 第19课螺纹件,紧固件和联接件— 第20课减(耐)摩擦轴承…………*第2l课斜齿轮、蜗杆蜗轮和锥齿轮 第22课轴、离合器和制动器……— 第三章机床……… 第23课机床基础 第24课车床…… 第25课牛头刨、钻床和铣床…………第36课磨床和特种金属加工工艺……第四章切削技术和液压“………………第27课加工基础………………………第28课基本的机械加工参数…………第29课切削参数的改变对温度的影响第30课刀具的磨损………… 第31课表面稍整加工机理… 第32课极限和公差…………“

第33课尺寸控制和表面桔整” 第34课自动央具设计………“ 第36课变速液压装置……………—…………— 策37课电液伺服系统…………。……………。 第五章机械电子技术……………………………… 第38课专家系统……。………………………… 第3D课建筑机器人……………………………… 第40课微机为基础的机器人模拟……………… 第41课机器人学的定义和机器入系统………… 第42课微型计算机基础(1)…………………… 第43课微型计算机基础(x)…………………… 第44课可编程控制器…………………………… 第45课CAD/CAM计算机辅助设计与制造… 第46课计算机数控和直接数控,CNC和DNC 第47课加工过程的数控—……………………… 第48课柔性制造系统……………—…………… 第仍课交互式编程系统………………………… 第50课在振动分析方面的计算机技术………… 策51课压力传感器……………………………… 第52课反馈元件…………………—…………… 第53课现代按制理论概述……………………… 第54课管理上采取了新的措施—来自福持汽 第六章英文科技文献和专利文献的查阅………… 6.1 常见科技文献及其查阅……………………… 6.2 专利文献概述………………………………… 第七章英文科拉论文写作………………………… 7.1 标题与摘要写法……………………………… 7.2 正文(body)的组织与写法………………… 7.3 致谢、附录及参考文献………………—…… 参考文献……………………………………………… 第1章材料和热加工 机械学的基本概念 功是力乘以该力作用在物体上佼物体移动的距离。功用公斤·米来表示。l公斤‘米等于I 公斤力作用于物体上使物体移动1米的距离。例如,一项工作需要提升一台300公斤重的设备到两米半高的卡车上,那么就需要750公斤·米的功。由于没有一个人能直接举升别o 公斤重,因此必须使用一种装置去调节所需要的可以控制的作用力。常见的装置是一个斜面 一在这个例子中,一个倾斜在地面动卡车之勾的承载斜板.如果斜板有1G米长,摩擦力忽略,那么就需要75公斤的力将机器该上斜板。总功仍然是7jN?斤·米L用75公斤乘以10米),但作用力已经被改变,于是乎共所需的最大外力仅仅是75公斤。

机械英文翻译

机械英文翻译

英文翻译 机械设计 一台完整机器的设计是一个复杂的过程。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。 Machine Design The 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. 任何产品在设计时第一步就是选择产品每个部分的构成材料。许多的材料被今天的设计师所使用。对产品的功能,它的外观、材料的成本、制造的成本作出必要的选择是十分重要的。对材料的特性必须事先作出仔细的评估。 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 the material, 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. 仔细精确的计算是必要的,以确保设计的有效性。在任何失败的情况下,最好知道在最初设计中有有缺陷的部件。计算(图纸尺寸)检查是非常重要的。一个小数点的位置放错,就可以导致一个本可以完成的项目失败。设计工作的各个方面都应该检查和复查。 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. 计算机是一种工具,它能够帮助机械设计师减轻繁琐的计算,并对现有数据提供进一步的分析。互动系统基于计算机的能力,已经使计算机辅助设计(CAD)和计算机辅助制造(CAM)成为了可能。心理学家经常谈论如何使人们适应他们所操作的机器。设计人员的基本职责是努力使机器来适应人们。这并不是一项容易的工作,因为实际上并不存在着一个对所有人来说都是最优的操作范围和

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