机械专业外文翻译----基于事例推理的夹具设计研究与应用(编辑修改稿)

机械专业外文翻译----基于事例推理的夹具设计研究与应用(编辑修改稿)内容摘要：

ency. The methodology of case based reasoning (CBR) adapts the solution of a previously solved case to build a solution for a new problem with the following four steps: retrieve, reuse, revise, and retain [1]. This is a more useful method than the use of an expert system to simulate human thought because proposing a similar case and applying a few modifications seems to be self explanatory and more intuitive to humans .So various case based design support tools have been developed for numerous areas[24], such as in injection molding and design, architectural design, die casting die design, process planning, and also in fixture design. Sun used six digitals to pose the index code that included workpiece shape, machine portion, bushing, the 1st locating device, the 2nd locating device and clamping device[5]. But the system cannot be used for other fixture types except for drill fixtures, and cannot solve the problem of storage of the same index code that needs to be retained, which is very important in CBR[6]. 1 Construction of a Case Index and Case Library Case index The case index should be posed of all features of the workpiece, which 12 are distinguished from different fixtures. Using all of them would make the operation in convenient. Because the forms of the parts are diverse, and the technology requirements of manufacture in the enterprise also develop continuously, lots of features used as the case index will make the search rate slow, and the main feature unimportant, for the reason that the relative weight which is allotted to every feature must diminish. And on the other hand, it is hard to include all the features in the case index. Therefore, considering the practicality and the demand of rapid design, the case index includes both the major feature of the workpiece and the structure of fixture. The case index code is made up of 16 digits: 13 digits for case features and 3 digits for case identification number. The first 13 digits represent 13 features. Each digit is corresponding to an attribute of the feature, which may be one of“ *” , “。 ” , “ 1” , “ 2” ,…, “ A” ,“ B” ,…, “ Z” ,…, etc. In which, “ *” means anyone, “ ?” uncertain, “ 0” nothing. The system rules: fixture type, workpiece shape, locating model cannot be “ *”or“ ?” . When the system is designed, the attribute information of the three items does not have these options, which means the certain attribute must be selected. The last three digits are the case identification number, which means the 13 digits of the case feature are the same, and the number of these three digits is used for distinguishing them. The system also rules: “ 000” is a prototype case, which is used for retrieval, 13 and other cases are “ 001” ,“ 002” ,…, which are used for reference cases to be searched by designers. If occasionally one of them needs to be changed as the prototype case, first it must be required to apply to change the one to “ 000” , and the former is changed to referential case automatically. The construction of the case index code is shown in . Case library The case library consists of lots of predefined cases. Case representation is one of the most important issues in case based reasoning. So pounding with the index code,. Hierarchical form of Case The structure similarity of the fixture is represented as the whole fixture similarity, ponents similarity and ponent similarity. So the whole fixture case library, ponents case library, ponent case library of fixture are formed correspondingly. Usually design information of the whole fixture is posed of workpiece information and workpiece procedure information, which represent the fixture satisfying the specifically designing function demand. The whole fixture case is made up of function ponents, which are described by the function 14 ponents’ names and numbers. The ponents case represents the members. (function ponent and other structure ponents， main driven parameter, the number, and their constrain relations.) The ponent case (the lowest layer of t。