lesson31工程师在机械制造业中的作用.doc

Lesson31 the roles of engineers in manufacturing第三十一课 工程师在机械制造业中的作用Many engineers have as their function the designing of products that are to be brought into reality through the processing or fabrication of materials .In this capacity they are a key factor in the material selection-manufacturing procedure .A design engineer ,better than any other person ,should know what he or she wants a design to accomplish .He knows what assumptions he has made about service loads and requirements ,what service environment the product must withstand ,and what appearance he wants the final product to have .In order to meet these requirements he must select and specify the material(s) to be used .In most cases ,in order to utilize the material and to enable the product to have the desired form ,he knows that certain manufacturing processes will have to be employed .In many instances ,the selection of a specific material may dictate what processing must be used .At the same time ,when certain processes are to be used ,the design may have to be modified in order for the process to be utilized effectively and economically .Certain dimensional tolerances can dictate the processing .In any case ,in the sequence of converting the design into reality ,such decisions must be made by someone .In most instances they can be made most effectively at the design stage ,by the designer if he has a reasonably adequate knowledge concerning materials and manufacturing processes .Otherwise ,decisions may be made that will detract from the effectiveness of the product ,or the product may be needlessly costly .It is thus apparent that design engineers are a vital factor in the manufacturing process ,and it is indeed a blessing to the company if they can design for producibilitythat is ,for efficient production .许多工程师的职责是进行产品设计,而产品是通过对材料的加工制造而生产出来的。设计工程师在材料选择-制造方法等方面起着关键的作用。一个设计工程师应该比其他的人更清楚地知道他的设计需要达到什么目的。他知道他对使用荷载和使用要求所做的假设,产品的使用环境,产品应该具有的外观形貌。为了满足这些要求,他必须选择和规定,所使用的材料。通常,为了利用材料并使产品具有所期望的形状,设计工程师知道应该采用哪些制造方法。在许多情况下,选择了某种特定材料就可能意味着已经确定了某种必须采用的加工方法d同时,当决定采用某种加工方法后,很可能需要对设计进行修改,以使这种加工方法能够被有效而经济地应用。某些尺寸公差可以决定产品的加工方法。总之,在将设计转变为产品的过程中,必须有人做出这些决定。在大多数情况下,如果设计人员在材料和加工方法方面具有足够的知识,他会在设计阶段做出最为合理的决定。否则,做出的决定可能会降低产品的性能,或者使产品变得过于昂贵。显然,设计工程师是制造过程中的关键人物,如果他们能够进行面向生产(即可以进行高效率生产)的设计,就会给公司带来效益。Manufacturing engineers select and coordinate specific processes and equipment to be used ,or supervise and manage their use .Some design special tooling that is used so that standard machines can be utilized in producing specific products .These engineers must have a broad knowledge of machine and process capabilities and of materials ,so that desired operations can be done effectively and efficiently without overloading or damaging machines and without adversely affecting the materials being processed .These manufacturing engineers also play an important role in manufacturing .制造工程师们选择和调整所采用的加工方法和设备,或者监督和管理这些加工方法和设备的使用。一些工程师进行专用工艺装备的设计,以使通用机床能够被用来生产特定的产品。这些工程师们在机床、工艺能力和材料方面必须具有广泛的知识,以使机器在没有过载和损坏,而且对被加工材料没有不良影响的情况下,更为有效地完成所需要的加工工序。这些制造工程师们在制造业中也起到重要作用。A relatively small group of engineers design the machines and equipment used in manufacturing .They obviously are design engineers and ,relative to their products ,they have the same concerns of the interrelationship of design ,materials ,and manufacturing processes .However ,they have an even greater concern regarding the properties of the materials that their machines are going to process and the interreaction of the materials and the machines .少数工程师们设计在制造业中使用的机床和设备。显然,他们是设计工程师。而且对于他们的产品而言,他们同样关心设计、材料和制造方法之间的相互关系。然而,他们更多地关心他们所设计的机床将要加工的材料的性能和机床与材料之间的相互作用。Still another group of engineersthe materials engineersdevote their major efforts toward developing new and better materials .They ,too ,must be concerned with how these materials can be processed and with the effects the processing will have on the properties of the materials .还有另外一些工程师一一材料工程师,他们致力于研制新型的和更好的材料,他们也应该关心这些材料的加工方法和加工对材料性能的影响。Although their roles may be quite different ,it is apparent that a large proportion of engineers must concern themselves with the interrelationship between materials and manufacturing processes .尽管工程师们所起的作用可能会有很大差别,但是,大部分工程师们都必须考虑材料与制造工艺之间的相互关系。Low-cost manufacturing does not just happen .There is a close and interdependent relationship between the design of a product ,selection of materials ,selection of processes and equipment ,and tooling selection and design .Each of these steps must be carefully considered ,planned ,and coordinated before manufacturing starts .This lead time ,particularly for complicated products ,may take months ,even years ,and the expenditure of large amount of money may be involved .Typically ,the lead time for a completely new model of an automobile is about 2 years ,for a modern aircraft it may be 4 years .低成本制造并不是自动产生的。在产品设计、材料选择、加工方法和设备的选择,工艺装备选择和设汁之间都有着非常密切的相互依赖关系。这些步骤中的每一个都必须在开始制造前仔细地加以考虑、规划和协调。这种从产品设计到实际生产的准备工作,特别是对于复杂产品,可能需要数月甚至数年的时间,并且可能花费很多钱。典型的例子有,对于一种全新的汽车,从设计到投产所需要的时间大约为2年,而一种现代化飞机则可能需要4年。With the advent of computers and machines that can be controlled by either tapes made by computers or by the computers themselves ,we are entering a new era of production planning .The integration of the design function and the manufacturing function through the computer is called CAD/CAM(computer aided design/computer aided manufacturing) .The design is used to determine the manufacturing process planning and the programming information for the manufacturing processes themselves .Detailed drawings can also be made from the central data base used for the design and manufacture ,and programs can be generated to make the parts as needs .In addition ,extensive computer aided testing and inspection(CATI) of the manufactured parts is taking place .There is no doubt that this trend will continue at ever-accelerating rates as computers become cheaper and smarter .随着计算机和由计算机产生的纸带与由计算机本身控制的机器的出现,我们进人了一个生产计划的新时代。采用计算机将产品的设计功能与制造功能集成,被称为“D/CAM(计算机辅助设计/计算机辅助制造)。这种设计被用来制定加工工艺规程和提供加工过程本身的编程信息。可以根据供设计与制造用的中心数据库内的信息绘制零件图,需要时可以生成加工这些零件时所使用的程序。此外,对加工后零件的计算机辅助试验与检测也得到了广泛的应用。随着计算机价格的降低和性能的提高,这种趋势将毫无疑问地得到不断加速的发展。