装订线长春光华学院 毕业设计（论文）译文纸The Design of Machinery ProcessDesign Invention CreativityThese are all familiar terms but may mean different things to different people. These terms can encompass a wide range of activities from styling the newest look in clothing, to creating impressive architecture, to engineering a machine for the manufacture of facial tissues. Engineering design, which we are concerned with here, embodies all three of these activities as well as many others. The word design is derived from the Latin designare, which means “to designate, or mark out.” Websters gives several definitions, the most applicable being “to outline, plot, or plan, as action or workto conceive, invent-contrive.” Engineering design has been defined as “.the process of applying the various techniques and scientific principles for the purpose of defining a device, a process or a system in sufficient detail to permit its realization.Design may be simple or enormously complex, easy or difficult, mathematical or nonmathematical; it may involve a trivial problem or one of great importance.” Design is a universal constituent of engineering practice. But the complexity of engineering subjects usually requires that the student be served with a collection of structured, set-piece problems designed to elucidate a particular concept or concepts related to the particular topic. These textbook problems typically take the form of “given A, B, C, and D, find E.” Unfortunately, real-life engineering problems are almost never so structured. Read design problems more often take the form of “What we need is a framus to stuff this widget into that hole within the time allocated to the transfer of this other gizmo.” The new engineering graduate will search in vain among his or her textbooks for much guidance to solve such a problem. This unstructured problem statement usually leads to what is commonly called “blank paper syndrome.” Engineers often find themselves staring at a blank sheet of paper pondering how to begin solving such an ill-defined problem. Much of engineering education deals with topics of analysis, which means to decompose, to take apart, to resolve into its constituent parts. This is quite necessary. The engineer must know how to analyze systems of various types, mechanical, electrical, thermal or fluid. Analysis requires a thorough understanding of both the appropriate mathematical techniques and the fundamental physics of the systems function. But, before any system can be analyzed, it must exist, and a blank sheet of paper provides little substance for analysis. Thus the first step in any engineering design exercise is that of synthesis, which means putting together.The design engineer, in practice, regardless of discipline, continuously faces the challenge of structuring the unstructured problem. Inevitably, the problem as posed to the engineer is ill-defined and incomplete. Before any attempt can be made to analyze the situation he or she must first carefully define the problem, using an engineering approach. To ensure that any proposed solution will solve the right problem. Many examples exist of excellent engineering solutions which were ultimately rejected because they solved the wrong problem, i.e., a different one than the client really had.Much research has been devoted to the definition of various “design processes” intended to provide means to structure the unstructured problem and lead to a viable solution. Some of these processes present dozens of steps, others only a few. The one presented in table 1-1 contains 10 steps and has, in the authors experience, proven successful in over 30 years of practice in engineering design. ITERATION Before discussing each of these steps in detail it is necessary to point out that this is not a process in which one proceeds from step one through ten in a linear fashion. Rather it is, by its nature, an iterative process in which progress is made haltingly, two steps forward and one step back. It is inherently circular. To iterate means to repeat, to return to a previous state. If, for example, your apparently great idea, upon analysis, turns out to violate the second law of thermodynamics, you can return to the ideation step and get a better idea! Or, if necessary, you can return to an earlier step in the process, perhaps the background research, and learn more about the problem. With the understanding that the actual execution of the process involves iteration, for simplicity, we will now discuss each step in the order listed in table 1-1.Identification of NeedThis first step is often done for you by someone, boss or client, saying “What we need is.” Typically this statement will be brief and lacking in detail. It will fall far short of providing you with a structured problem statement. For example, the pr