【導(dǎo)讀】具設(shè)計等項目的設(shè)計過程中得到了應(yīng)用,并取得了令人滿意的使用效果.刀具或機(jī)床的位置一致不變。因為夾具的結(jié)構(gòu)依賴于產(chǎn)品的特點和在企業(yè)規(guī)劃。些設(shè)計論文包括工件的結(jié)構(gòu)設(shè)計、涉及加工工藝，和加工環(huán)境。問題,這在CBR中是非常重要的.事例參數(shù)代碼由16位數(shù)組成：13位數(shù)是事例特征3位數(shù)是事例識別。前13位數(shù)代表13個特征。時,三個項目的屬性信息沒有這些選擇,這就意味著必須選擇確定的屬性。先它必須要求改成"000",前面的自動變成參考事例.所以由索引碼復(fù)合。夾具的結(jié)構(gòu)相似被認(rèn)為是整個夾具，成分和內(nèi)容相似。全部夾具事例是由功能成分組成，它是用功能成分的名字和數(shù)字來進(jìn)行描述的。根據(jù)夾具設(shè)計的需求，事例修改的策略使最。兩個事例之間的相似點是基于兩個事例特征之間的相似點。分別是50kg和20kg的工件。表示事例庫中特性和相關(guān)夾具的特性的相似尺寸。似尺寸值比給定的數(shù)值小，這些事例就不能選來作相似事例。

　　

【正文】 epresentation that can describe the main features of a case family. A case family consists of those cases whose index codes have the same first 13 digits and different last three digits in the case library. The last three digits of a prototype case are always “ 000” . A reference case belongs to the same family as the prototype case and is distinguished by the different last three digits. From the concept that has been explained, the following strategies are adopted: 1) If a new case matches any existing case family, it has the same first 13 digits 21 as an existing prototype case, so the case is not saved because it is represented well by the prototype case. Or is just saved as a reference case (the last 3 digits are not “ 000” , and not the same with others) in the case library. 2) If a new case matches any existing case family and is thought to be better at representing this case family than the previous prototype case, then the prototype case is substituted by this new case, and the previous prototype case is saved as a reference case. 3) If a new case does not match any existing case family, a new case family will be generated automatically and the case is stored as the prototype case in the case library. 4 Process of CBR in Fixture Design According to the characteristics of fixture design, the basic information of the fixture design such as the name of fixture, part, product and the designer, etc. must be input first. Then the fixture file is set up automatically, in which all ponents of the fixture are put together. Then the model of the work piece is input or designed. The detailed information about the work piece is input, the case index code is set up, and then the CBR begins to search the analogical cases, relying on the similarity measure, and the most analogical case is selected out. If needed, the case is adapted to satisfy the current design, and restored into the case library. The flowchart of the process is shown in . 22 5 Illustrating for Fixture Design by CBR This is a work piece (). Its material is 45 steel. Its name is seat. Its shape is block, and the product batch size is middle, etc. A fixture is turning fixture that serves to turn the hole, which needs to be designed. The value of feature, attribute, case index code and weight of the work 23 piece is show n in . Through searching, and calculating the similarity, the case index code of the most similar case is 19325513321402020, and the detailed information is show n in Tab. 3. The similarity is calculated as follows: 24 So the value of similarity measure of the fixture which needs to be designed with the most analogical case in case library is , and the structure of the most analogical case is shown in . After having been substituted the ponent, modified the locating model and clamp model, and adjusted the relative dimension, the new fixture is designed, and the figure is show n in . 25 As there is not the analogical fixture in the case library, the new fixture is restored in to the case library. The case index code is 19325513311402020. 6 Conclusion CBR, as a problem solving methodology, is a more efficient method than an expert system to simulate human thought, and has been developed in many domains where knowledge is difficult to acquire. The advantages of the CBR are as follows: it resembles human thought more closely。 the building of a case library which has self learning ability by saving new cases is easier and faster than the building of a rule library。 and it supports a better transfer and explanation of new knowledge that is more different than the rule library. A proposed fixture design framework on the CBR has been implemented by using Visual C ++, UG/Open API in U n graphics with Oracle as database support, which also has been integrated with the 32D parametric mon ponent library, mon ponents library and typical fixture library. The prototype system, developed here, is used for the aviation project, and aids the fixture designers to improve the design efficiency and reuse previous design resources.