發(fā)布時(shí)間：2018-03-17 17:31

  本文選題：DFS編碼　切入點(diǎn)：最大同構(gòu)子圖　出處：《南昌航空大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：企業(yè)在加工過程中首先面臨的是裝夾工件的問題,這個(gè)過程直接影響了產(chǎn)品的質(zhì)量,而工件裝夾的質(zhì)量取決于夾具的設(shè)計(jì)。也就是說夾具設(shè)計(jì)的質(zhì)量和效率直接影響了企業(yè)產(chǎn)品的質(zhì)量和生產(chǎn)效率。在生產(chǎn)制造中,企業(yè)不斷的追求更好的質(zhì)量、更高的效率和最低的成本。這樣他們才能夠在全球化的市場(chǎng)競(jìng)爭中得以生存,得以發(fā)展。在整個(gè)加工過程中,夾具設(shè)計(jì)時(shí)間占整個(gè)加工周期的35%-50%左右,從提高夾具設(shè)計(jì)效率方面來縮短加工周期顯得非常重要。然而傳統(tǒng)的夾具設(shè)計(jì)最為典型的是類比法和經(jīng)驗(yàn)法,這些方法不但成本高、效率低,而且夾具的使用范圍及其有限。難以達(dá)到小批量、多品種的市場(chǎng)要求,難以達(dá)到CAD/CAPP/CAM集成的要求。另外,現(xiàn)代加工中常常出現(xiàn)待加工工件尺寸大、定位準(zhǔn)確性和協(xié)調(diào)性差、容易變形等情況,這使得夾具設(shè)計(jì)工作難上加難。所以打破傳統(tǒng)思維方式,探索新的高效率的夾具設(shè)計(jì)方法迫在眉睫。大量的夾具設(shè)計(jì)案例為夾具設(shè)計(jì)提供了可重用的經(jīng)驗(yàn)和知識(shí),為實(shí)現(xiàn)夾具快速設(shè)計(jì)奠定了基礎(chǔ),而準(zhǔn)確的檢索到相同或者相似的夾具設(shè)計(jì)案例則是實(shí)現(xiàn)夾具快速設(shè)計(jì)的核心與關(guān)鍵.為此,本文根據(jù)零件B-rep表示的實(shí)體模型,通過特征之間的幾何拓?fù)潢P(guān)系構(gòu)造零件的標(biāo)號(hào)圖.結(jié)合標(biāo)號(hào)圖的線性順序性和擴(kuò)展延續(xù)性,提出了特征標(biāo)識(shí)的確定原則,構(gòu)建了最小DFS編碼的遍歷流程.針對(duì)新零件的最小DFS編碼與夾具案例的最小DFS編碼,提出同構(gòu)子圖的挖掘方法,在建立零件相似度和圖集相似度的基礎(chǔ)上,進(jìn)一步提出最大同構(gòu)子圖的判斷標(biāo)準(zhǔn).最后通過挖掘零件的裝夾特征及自身幾何關(guān)系的最大同構(gòu)子圖,以裝夾特征的最大同構(gòu)子圖為優(yōu)先準(zhǔn)則,完成新零件與夾具圖集的準(zhǔn)確匹配,實(shí)現(xiàn)夾具的快速設(shè)計(jì)過程.
[Abstract]:In the process of processing, enterprises are first faced with the problem of clamping workpieces, which has a direct impact on the quality of products. The quality of workpiece clamping depends on the fixture design. That is to say, the quality and efficiency of fixture design directly affect the quality and production efficiency of enterprise products. Higher efficiency and minimum cost. So they can survive and develop in the global market competition. In the whole process, fixture design time is about 35-50% of the whole processing cycle. It is very important to shorten the processing cycle in order to improve the efficiency of fixture design. However, the traditional fixture design is the most typical method of analogy and experience, these methods are not only high cost, but also low efficiency. Moreover, it is difficult to meet the requirements of small batch, multi-variety market and CAD/CAPP/CAM integration. In addition, in modern machining, the size of workpiece to be processed is large, the positioning accuracy and coordination are poor. Easy to deform and so on, which makes the fixture design more difficult. So break the traditional way of thinking, It is urgent to explore new and efficient fixture design methods. A large number of fixture design cases provide reusable experience and knowledge for fixture design and lay a foundation for rapid fixture design. However, retrieving the same or similar fixture design cases accurately is the core and key of rapid fixture design. Therefore, according to the solid model of B-rep representation of parts, Based on the geometric and topological relations between features, the label diagram of parts is constructed. Combining with the linear sequence and extended continuity of label graph, the principle of determining feature identification is put forward. The traversal process of minimum DFS coding is constructed. Aiming at the minimum DFS coding of new parts and the minimum DFS coding of fixture cases, a method of mining isomorphism subgraphs is proposed. Finally, the maximum isomorphism subgraph of the clamping feature and the maximum isomorphism subgraph of the geometric relation of the parts are excavated, and the maximum isomorphism subgraph of the clamping feature is taken as the priority criterion. Complete the accurate matching of new parts and fixture atlas, and realize the rapid design process of fixture.
【學(xué)位授予單位】：南昌航空大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG75

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