逆向工程中曲線與曲面的綴合運算

Abstract

在電腦整合製造過程中,逆向工程以三次元座標量測儀,或雷射量測鑄件外 形及輪廓,然後利用電腦做曲面的綴合,並以此作加工路徑並產生 NC 程式 以控制工具機做加工。 因模具加工的複雜度增加及品質精度的要求日益 提升,曲線及曲面的綴合運算在整個逆向工程顯的更重要。 曲線及曲面的 綴合運算基本上是尋求一連線的曲線及曲面, 或者合成曲線曲面,通過三 維中給定的一組點。逆向工程中這問題顯得較複雜,因為點的數量很大,且 大都是不規則排列。本論文針對曲線在逆向工程的運用,提出可行的做法, 並且實作。而對曲面綴面綴合問題,除了探討對文獻上的做法外,我們也實 作其中一做法,另外我們也提出並實作一新的綴合方法。我們也根據逆向 工程的需求檢討這些方法的適用性。 In the field of computer integrated manufacturing, the reverse engineering is a process that reproduces a manufactured part based on the sampling points obtained from a coordinate- measurement machine or a laser scanning machine. In the process the shape of the part is approximated by fitting surface and from which a NC tool path is generated. The curve and surface fitting becomes complicated when applied to the reverse engineering since the sampling points are numerous and are usually scattered, and moreover, the fitting surface should be well suited for the NC path generation. In this paper, we propose a feasible method for the curve fitting in the reverse engineering. For the surface fitting, several existing methods are surveyed, one if which was implemented. A new approach is also proposed and implemented. These methods are examined according to the needs of the reverse engineering.