外文翻譯-夾具設(shè)計(jì)機(jī)械-文庫(kù)吧資料
2025-07-05 11:27本頁(yè)面
【正文】 .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。3)Sort the order of similarity measure, the biggest value, which is the most analogical case.Similarity between two cases is based on the similarity between the two cases. features. The calculation of similarity measure depends on the type of the feature. The value of similarity can be calculated for numerical values, for example, pareWorkpiece with the weight of 50kg and 20kg. The value can also be calculated between non numerical values, for example, now the first 13 digits index code is all non numerical values. The similarity measure of a fixture is calculated as follows: where S is the similarity measure of current fixture, n is the number of the index feature, is the weight of each feature, is the similarity measure of the attribute of the i2th feature with the attributeof relative feature of the jth case in the case library. At the same time, , the value counts as follows:.Where is the value of the index attribute of the ith feature, and is the value of attribute of the relative ith feature of the jth case in case library.So there are two methods to select the analogical fixture. One is to set the value. If the values of similarity measure of current cases were less than a given value, those cases would not be selected as analogical cases. When the case library is initially set up, and there are only a few cases, the value can be set smaller. If there are lots of analogical cases, the value should get larger. The other is just to set the number of the analogical cases (such as10), which is the largest value of similarity measure from the sorted order.3 Case adaptation and Case Storage Case adaptation The modification of the analogical case in the fixture design includes the following three cases:1) The substitution of ponents and the ponent。 the knowledge guided strategy means to search on the knowledge rule from root to the object, which is firstly searched by the fixture type, then by the shape of the workpiece, thirdly by the locating method. For example, if the case index code includes the milling fixture of fixture type, the search is just for all milling fixtures, then for box of workpiece shape, the third for 1plane+ 2pine of locating method. If there is no match of it, then the search stops on depth, and returns to the upper layer, and retrieves all the relative cases on breadth.Retrieval algorithms:1)According to the case index information of fixture case library, search the relevant case library。fixture design。這個(gè)發(fā)展的標(biāo)準(zhǔn)系統(tǒng)，用于航空項(xiàng)目，幫助夾具設(shè)計(jì)者提高設(shè)計(jì)效率和重新使用先前的設(shè)計(jì)資源?；谑吕评碇刑岢龅囊粋€(gè)夾具設(shè)計(jì)的框架已經(jīng)被實(shí)行了，使用的是支持基礎(chǔ)數(shù)據(jù)的VC++，UG電腦繪圖軟件。6 結(jié)論 基于事例推理，作為一個(gè)問(wèn)題解決的方法，是一個(gè)比模仿人類思想的專業(yè)系統(tǒng)更有效的方法，已經(jīng)在很多難獲取知識(shí)的領(lǐng)域里得到發(fā)展。 表2 最相似事例的事例索引碼特征名稱 特性值 索引碼夾具類型 車床夾具 1 工件形狀 塊狀 9 工件材料 中碳鋼 3 批量 中批 2 工件比例 小 5 工件重量 輕 5 工件剛度 硬度強(qiáng) 1 加工內(nèi)容 孔 3 程序要求 完成加工 3 定位方法 三個(gè)平面 1
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