外文翻譯--對機械設計的認識

Knowledge of machine design The 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 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. 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 . 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. 對 機械設計 的認識 機械設計是一門通過設計新產(chǎn)品或者改進老產(chǎn)品來滿足人類需求的應用技術科學。它涉及工程技術的各個領域，主要研究產(chǎn)品的尺寸、形狀和詳細結(jié)構(gòu)的基本構(gòu)思，還要研究產(chǎn)品在制造、銷售和使用等方面的問題。機械設計的目的是生產(chǎn)能夠滿足人類需求的產(chǎn)品。發(fā)明、發(fā)現(xiàn)和科技知識本身并不一定能給人類帶來好處，只有當它們被應用在產(chǎn)品上才能產(chǎn)生效益。因而，應該認識到在一個特定的產(chǎn)品進行設計之前，必須先確定人們是否需要這種產(chǎn)品 。 應當把機械設計看成是機械設計人員運用創(chuàng)造性的才能進行產(chǎn)品設計、系統(tǒng)分析和制定產(chǎn)品的制 造工藝學的一個良機。掌握工程基礎知識要比熟記一些數(shù)據(jù)和公式更為重要。僅僅使用數(shù)據(jù)和公式是不足以在一個好的設計中做出所需的全部決定的。另一方面，應該認真精確的進行所有運算。例如，即使將一個小數(shù)點的位置放錯，也會使正確的設計變成錯誤的。 在設計的初始階段，應該允許設計人員充分發(fā)揮創(chuàng)造性，不受各種約束。即使產(chǎn)生了許多不切實際的想法，也會在設計的早期，即繪制圖紙之前被改正掉。只有這樣，才不致于堵塞創(chuàng)新的思路。通常，要提出幾套設計方案，然后加以比較。很有可能在最后選定的方案中，采用了某些未被接受的方案中的一些想法。 通常 ，在制造過程中會出現(xiàn)某個問題?？赡軙髮δ硞€零件尺寸或公差作一些更改，使零件的生產(chǎn)變得容易。但是，工程上的更改必須要經(jīng)過設計人員批準，以保證不會損傷產(chǎn)品的功能。有時，在產(chǎn)品的裝配時或者裝箱外運前的試驗中才發(fā)現(xiàn)設計中的某種缺陷。這些事例恰好說明了設計是一個動態(tài)過程?？偸谴嬖谥玫姆椒▉硗瓿稍O計工作，設計人員應該不斷努力，尋找這些更好的方法。 近些年來，工程材料的選擇已經(jīng)顯得重要。此外，選擇過程應該是一個對材料的連續(xù)不斷的重新評價過程。新材料不斷出現(xiàn)，而一些原有的材料的能夠獲得的數(shù)量可能會減少。環(huán)境污 染、材料的回收利用、工人的健康及安全等方面經(jīng)常會對材料選擇附加新的限制條件。為了減輕重量或者節(jié)約能源，可能會要求使用不同的材料。來自國內(nèi)和國際競爭、對產(chǎn)品維修保養(yǎng)方便性要求的提高和顧客的反饋等方面的壓力，都會促使人們對材料進行重新評價。由于材料選用不當造成的產(chǎn)品責任訴訟，已經(jīng)產(chǎn)生了深刻的影響。此外，材料與材料加工之間的相互依賴關系已經(jīng)被人們認識得更清楚。因此，為了能在合理的成本和確保質(zhì)量的前提下獲得滿意的結(jié)果，設計工程師的制造工程師都必須認真仔細地選擇、確定和使用材料。 制造任何產(chǎn)品的第一步工作都是設計。設 計通常可以分為幾個明確的階段：（ a）初步設計；（ b）功能設計；（ c）生產(chǎn)設計。在初步設計階段，設計者著重考慮產(chǎn)品應該具有的功能。通常要設想和考慮幾個方案，然后決定這種思想是否可行；如果可行，則應該對其中一個或幾個方案作進一步的改進。在此階段，關于材料選擇唯一要考慮的問題是：是否有性能符合要求的材料可供選擇；如果沒有的話，是否有較大的把握在成本和時間都允許的限度內(nèi)研制出一種新材料 。 在功能設計和工程設計階段，要做出一個切實可行的設計。在這個階段要繪制出相當完整的圖紙，選擇并確定各種零件的材料。通常要制造出樣機 或者實物模型，并對其進行試驗，評價產(chǎn)品的功能、可靠性、外觀和維修保養(yǎng)性等。雖然這種試驗可能會表明，在產(chǎn)品進入到生產(chǎn)階段之