以修正製程需求表達法辨認廣義加工特徵之研究

Abstract

傳統的特徵辨認法，需要預定特徵的幾何外形，因而造成交錯特徵的 辨認不易、應用範圍有限，以及加工上的不經濟。而所謂的廣義加工特徵 ，係指一組面集合，其可在同一進刀方向上，用同一把刀具連續切削完成 的區域，因其不需預先定義的幾何外形，故可避免傳統辨認法的問題。本 研究所發展的系統，其主要目的即在找出工件的廣義加工特徵，供作加工 資訊，促進CAD/CAM的整合。 本系統共有三個主要模組，分別處理 ：(1)製程需求的推導、(2)加工面的分割、(3)廣義加工特徵的產生。第 一個模組透過工件的邊界表達法（B-REP）資料，將每個工件面轉換成製 程需求資料，其內容包括加工每的面的可行進刀方向及刀具規格。若有一 加工面無法求得其製程需求時，第二個模組便將該面予以分割，使各個子 分割面皆可求得個別的製程需求。最後，第三個模組將利用各加工面的製 程需求，推導出該工件上所有的廣義加工特徵，作為最後的輸出。 本 研究並以五個實例進行驗證，該等實例皆可產生適當的廣義加工特徵作為 最後的輸出。 This research proposes a method for recognizing generalizedmechining features from a prismatic part. Here, a generalizedmachining feature is defined as a set of connecting faces, whichcan be produced by the continuous machining of a particular toolin a certain workpiece setup. Machining feature recognition hasbeen a widely known research topic, and most previous researchersadopt a template-matching approach. That is, they first define atemplate machining feature and try to match the template on theworkpiece to locate features. In practice, the number of templatesare difficult to enumerate exhaustively, and therefore the previousalgorithms are deficient in robustness. In the proposed method,the mechanism for recognizing machining features does not requiredefining templates and therefore would be relatively more robust.The porposed algorithm has been implemented in C language on aPC486 machine and showed satisfactory results.