外文翻译-机械设计理论

Machine design theoryThe machine design is an application technical science which designs the new product or improves the old product to meet the human need. It involves all domains of the project technology , which mainly studies basic idea of the size, the shape and the detailed structure of products. And it also studies the questions of manufacture, sale and usage.The one who do machine design work is called designer or machine design engineer. The machine design is a creative work. Design engineer not only has the creativity in the work, but also has deep elementary knowledge in mechanical drawing, kinematics, engineering material, materials mechanics and machine manufacture technology.As words above, the goal of the machine design is to produce the product which meets the human need. The invention, discovery and technical knowledge are not necessarily bringing the advantages to humanity, which take benefits when they are applied on the product. So , it should be realized that if the product is needed or not before a special design carrying on .Its a good opportunity for machine designer to use creative ability on the product design, system analysis and a formulation product manufacture technology. Grasps the project elementary knowledge is more important than memorize some data and the formula. The merely service data and the formula is insufficient to the completely decision which makes in a good design. On the other hand, it should be earnest precisely all operations. For example, a decimal point position wrongly can cause the correct design to false.A good designer should dare to propose the new idea ,and willing to undertake the certain risk. when the new method is not suitable, back to original method. Therefore, designers must have patience. Because the time and the endeavor cannot guarantee success. A brand-new design will leave the obsolete and well known method. As conservativeness of many person, it is not an easy matter. A mechanical designer should unceasingly explore the improvement of method for existing product, should earnestly choose originally, the process confirmation principle of design in this process, and combine with new idea which has not unified.A new design will have questions on many flaws and things not been able to expect. After these flaws and the question are solved, it can manifest superiority of new product. Therefore, when a performance superior product is born, it is following a higher risk also. We should emphasize that, if designs itself does not request to use the brand-new method, it is not unnecessary merely for the goal which transform to use the new method. In the preliminary stage of design, its allowed to display the creativity for designers fully, none of restraint will be take. Even if having many impractical ideas, these can be correct in the early design, before the blueprint drawings are drawed . Only then, the mentality on innovation will be not stop up. Usually, several sets of design proposals will be proposed and compared. May be some thoughts will be used in the last proposal from the other proposals which are not accept .Psychologist frequently discuss that the people should adapts the machine which they operate. Designers basic responsibility is diligently causes the machine to adapt the people. This certainly is not an easy work, because, there isnt a best superior operating area and the operating process for all persons. Another important question is project engineer must exchange and consult with other concerned person. In the initial stage, designers have to exchange and consult with the administrative person of the preliminary design which would be approved. This generally is through the oral discussion, the schematic diagram and the writing. In order to carry on the effective exchange, have to solve the following problems: (1) whether this product truly needed by the people? (2) its competitive or not for this product compare with other companies existing similar products ? (3) if this kind of product is economical? (4) if the service is convenient? (5) if the product will be good on sale? Whether it may gain?Only the time can give the correct answer to above question. But, the product design, the manufacture and the sale can only be go on when the above questions have preliminary affirmation answer. Project engineer also should through the detail drawing and the assembly drawing, consult with the branch of manufacture to the finally design proposal.Usually, some problems will happen in the manufacture process. Such as making some modifies on components size or the common to make the components production easily. But, the project change must be authorized by designer to guarantee the products function not to be damaged. Sometimes, some kinds of design flaws founded before product assembling or in the experiment before packing. These instances exactly showed the design is a dynamic process. There is always a better method to complete the design work. Designers should be supposed unceasingly diligently, to seek these better methods. Recent year, the engineering material choice appeared more important. In addition, the choice process should be a continuously and reappraisal process. The new materials unceasingly appear, and some original materials keep reducing. The environmental pollution, material recycling, workers health and security will attach the new limiting condition to the choice of materials. In order to reduce the weight or save energy, it should be requested to use different material. The competition from domestic and international, the request enhancement for product service maintenance and convenience , customers aspect and so on will feedback pressure and urge the people to carry on the material reappraising. Because of the materials wrong selected , which cause the product responsibility lawsuit, has already had the profound influence. In additional, its clear that the material and the material processing interdependence. Therefore, in order to get the satisfy result under the reasonable cost and quality guarantee, project engineer have to choose, determine and use the materials carefully. The first step of product manufacturing is design . Design usually divide into several explicit stages: (a) preliminary design; (b) functional design; (c) production design. In the preliminary design stage, the designer emphatically consider the function of product. They always conceive and consider several plans, then decide if the thought is feasible; If it is feasible, they should make the further improvement to one or several plans. In this stage, the question of choice of material is: Is there a material which can conform the performance to be supplied for choice; If no, whether has a bigger assurance to develop a kind of new material in limit of the cost and the time.In the functional design and the engineering design stage, it needs to make a practical feasible design. The quite complete blueprint must be drew up in this stage, and choose, determine the materials for each kinds of components. Usually, the prototype or the working model must be manufactured , and carries on the experiment to it, appraises products function, reliability, the outward appearance and the service maintenance and so on. Although this kind of experiment will indicate that some materials will be replaced , before the product sending into the production line. But, this point is absolutely not a excuse to take not earnestly choice of the material. The outward appearance, the cost and the reliability of the product should be carefully considered, unified with the function of product. Its best for a successful company to use the same materials which are used in the normal production and the same manufacture technology when they are manufacturing the prototypes as much as possible. The function completely prototype cannot be made economically according to the anticipated sales volume, or there are some great different in the quality and the reliable for prototypes and the official production installment , this kind of prototype does not have the great value. Project engineer should complete the analysis, the choice and the determination of the material in this stage , but not remains it to the production design stage . Because, the material replacement in the production design stage is decided by other people, who are inferior to project engineer to all functions understanding of the product. In the production design stage ,it should be completely determined with the material, to make them to adapt with the existing equipment, and to use the existing equipment economically to carry on the processing, moreover, the material quantity can quite be easy to guarantee the supply. In the manufacture process, it will appear the situation to change the material on using. The experience indicated that, use some certain cheap materials to take the substitute. However, in the majority situation, changing the materials after the production process will spend higher than changing the materials before the production process . Completing the choice of materials in the design stage, may avoid the most such situations. The most common reason for changing the materials when the product under manufacturing is that the new material is appeared. Certainly, these new materials possibly reduce the cost or improve the product performance. But, the earnest appraisal to the new material must be carried on , to guarantee its all performance to achieve the purpose. Remember that: the new materials performance and the reliable is not understood by the people. The majority of products expiration and the product accident caused by negligence case is that the selects of the new material not truly understood their long-term operational performance. The product responsibility lawsuit forces designers and the company use the best procedure when they choose materials. In the material choosing process, five most common questions are: (a) did not understand or cannot use the best and the latest information about the material application aspect; (b) has not been able to foresee and to consider the possible and reasonable usage of product (for example: designer is also supposed further to forecast and the consideration when the product used wrong. In recent years, many products responsibilities lawsuit case, because wrongly uses the plaintiff which the product receives the injury to accuse produces the factory, and wins the decision); (c) the material data are not entire or some data are indefinite, especially its long-term performance data; (d) the quality control plan is not suitable or not confirmed; (e) the personnel who is not competent to choose the material. Through the analysis five questions above , may obtain these questions is does not have the sufficient reason existence the conclusion. It will avoid these questions appearance and indicate the direction after these questions analysis. Although, using the best choice of material will not avoid having the product responsibility lawsuit. Designer and the industry carries on the choice of material according to the suitable procedure, may greatly reduce the lawsuit the quantity. From the above discussion, the choice of material should understand the material nature, the characteristic and the processing method comprehensive and basically.机械设计理论机械设计是设计新产品或改进旧产品以满足人类需要的应用技术科学。它涉及到项目技术的各个领域，主要研究产品的尺寸、形状和详细结构的基本思想。并对生产、销售和使用中存在的问题进行了研究。做机械设计工作的人被称为设计者或机械设计工程师。机械设计是一项创造性的工作。设计工程师不仅具有创造性的工作，而且在机械制图、运动学、工程材料、材料力学和机械制造技术方面有很深的基础知识。如上所述，机械设计的目标是生产符合人类需要的产品。发明、发现和技术知识不一定给人类带来好处，当它们被应用于产品时会带来益处。因此，在进行特殊设计之前，必须了解产品是否需要。这是机械设计师在产品设计、系统分析和配方产品制造技术上运用创新能力的良好时机。掌握项目的基础知识比记忆一些数据和公式更重要。仅仅服务数据和公式不足以做出一个好的设计的完全决策。另一方面，它应该是非常精确的所有操作。例如，小数点位置错误会导致正确的设计错误。一个好的设计师应该敢于提出新的想法，并愿意承担一定的风险。当新方法不适用时，回到原来的方法。因此，设计师必须要有耐心。因为时间和努力不能保证成功。一个全新的设计将留下过时和众所周知的方法。作为许多人的保守性，这不是一件容易的事情。机械设计师应不断探索现有产品的改进方法，在这一过程中应认真选择原来的设计、工艺确认原则，并结合尚未统一的新理念。一个新的设计会对许多瑕疵和无法预料的事物产生疑问。经过这些缺陷和问题的解决，可以体现出新产品的优越性。因此，当一个性能优越的产品诞生时，它也跟着一个更高的风险。我们要强调的是，如果设计本身不要求使用全新的方法，那么对于使用新方法的转换目标就不必要了。在设计的前期阶段，可以充分展示设计师的创造力，不受约束。即使有许多不切实际的想法，这些都可以在早期的设计中正确，在绘制图纸之前。只有这样，创新的心态才会止步。通常，将提出几个设计方案并进行比较。可能会有一些想法被用于其他提案中不接受的最后提案中。心理学家经常讨论人们应该适应他们操作的机器。设计师的基本职责是努力使机器适应人们。这当然不是一件容易的工作，因为没有一个最好的优越的操作区域和所有人的操作过程。另一个重要的问题是项目工程师必须与其他相关人员进行交流和协商。在初步阶段，设计人员必须与初步设计的行政人员进行交流和协商，并予以批准。这一般是通过口头讨论、示意图和写作。为了进行有效的交流，必须解决以下几个问题：（1）该产品是否真正需要的人？（2）与其他公司现有同类产品相比，该产品是否具有竞争力？（3）这种产品是否经济？（4）服务是否方便？（5）产品是否有销路？是否会有所收获？只有时间才能对上述问题给出正确的答案。但是，当上述问题有了初步肯定的答案时，产品设计、制造和销售只能进行下去。项目工程师还应通过详细的图纸和装配图，与制造部门协商最终设计方案。通常，在制造过程中会出现一些问题。如对零件尺寸进行修改，或使零件易于生产。但是，工程变更必须由设计人员授权，以保证产品的功能不受损坏。有时，在产品组装前或包装前的实验中，会出现一些设计缺陷。这些实例表明，设计是一个动态过程。总是有更好的方法来完成设计工作。设计师应该不断努力，寻求更好的方法。近年来，工程材料的选择显得更为重要。另外，选择过程应该是一个持续的重新评估过程。新材料不断出现，一些原始材料不断减少。环境污染、物质回收、工人健康和安全将把新的限制条件附加到材料的选择上。为了减少重量或节省能源，应要求使用不同的材料。来自国内外的竞争，要求提高产品服务的维护和便利性，客户的方面等将会反馈压力并督促人们进行材料的重新评价。由于选用的材料错误，导致产品责任诉讼，已经产生了深远的影响。另外，很明显，材料和材料处理相互依赖。因此，为了在合理的成本和质量保证下得到满意的结果，项目工程师必须仔细选择、确定和使用材料。产品制造的第一步是设计。设计通常分为几个明确的阶段:(a)初步设计;(b)功能设计;(c)生产设计。在初步设计阶段，设计师着重考虑产品的功能。他们总是构想并考虑几个计划，然后决定是否可行;如果可行的话，他们应该对一个或几个计划做进一步的改进。在这一阶段，材料选择的问题是:是否有一种材料可以满足选择的性能;如果没有，是否有更大的保证来开发一种新的材料，以限制成本和时间。在功能设计和工程设计阶段，需要进行切实可行的设计。在这个阶段，必须画出相当完整的蓝图，并选择，确定每种成分的材料。通常，原型或工作模型必须制造，并进行实验，评估产品的功能、可靠性、外观和服务维护等。虽然这种实验表明一些材料将会被取代，在产品进入生产线之前。但是，这一点绝对不是不认真选择的借口。产品的外观、成本和可靠性应仔细考虑，与产品功能统一。对于一个成功的公司来说，最好是使用同样的材料，这些材料在正常生产中使用，在制造原型尽可能多的时候使用同样的制造技术。这个功能完全不能按照预期的销量来实现，或者在质量上有很大的不同，在原型和正式的生产安装上都是可靠的，这种样机没有很大的价值。项目工程师应在此阶段完成材料的分析、选择和确定，但不能将其保留到生产设计阶段。因为在生产设计阶段的材料更换是由其他人决定的，他们不如项目工程师对产品的所有功能理解。在生产设计阶段，应与材料完全确定，使其与现有设备相适应，并在经济上使用现有设备进行加工，而且材料数量相当容易保证供应。在制造过程中，会出现改变使用材料的情况。经验表明，用一些便宜的材料代替。但是，在大多数情况下，在生产过程中改变材料的花费要比在生产过程之前更换材料要高。在设计阶段完成材料的选择，可以避免大多数这样的情况。当产品在制造过程中发生变化时，最常见的原因是新材料出现了。当然，这些新材料可能会降低成本或提高产品性能。但是，对新材料的认真评估必须继续进行，以保证其全部性能达到目的。记住:新材料的性能和可靠性是人们所不了解的。大多数产品的失效和因疏忽造成的产品事故是新材料的选择并不能真正理解其长期运行性能。产品责任诉讼迫使设计师和公司在选择材料时采用最佳程序。在材料选择过程中，最常见的五个问题是: ( a )不了解或不能使用关于材料应用方面的最佳和最新信息；( b )未能预见和考虑产品的可能和合理使用(例如:设计者还应进一步预测和考虑产品何时使用不当。近年来，许多产品责任诉讼案件，因错误使用产品受到伤害的原告指控生产厂，并胜诉)；( c )材料数据不完整或某些数据不确定，特别是其长期业绩数据；(四)质量控制方案不适宜或者未得到确认的；( e )无权选择材料的人员。通过以上五个问题的分析，可以得出这些问题是没有充分理由存在的结论。它将避免这些问题的出现，并在这些问题分析后指明方向。但是，采用最佳的材料选择并不能避免产品责任诉讼。设计师和业界按照合适的程序进行材料的选择，可以大大减少诉讼的数量。从以上论述中，材料的选择应全面、基本地了解材料的性质、特点和加工方法。