外文翻譯-夾具設(shè)計(jì)機(jī)械-資料下載頁
2025-06-29 11:27本頁面
【正文】 he 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 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 DesignAccording 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 workpiece is input or designed. The detailed information about the workpiece 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 .5 Illustrating for Fixture Design by CBRThis is a workpiece (). 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 workpiece is show n in .Through searching, and calculating the similarity, the case index code of the most similar case is 19325513321402000, and the detailed information is show n in Tab. 3. The similarity is calculated as follows: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 .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 19325513311402000.6 ConclusionCBR, 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.22 / 2
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