基於八元樹法之五軸切削力及切削彎矩估測

Abstract

銑削中的切削力及切削彎矩對於切削穩定性及工件表面之輪廓精度、尺寸公差具有極大影響，在業界通常以試誤法進行切削路徑及切削參數的調整以減少切削力的過度變化，使切削狀態及精度控制趨於穩定，而這往往需仰賴人員的過往經驗及耗時測試，在學界通常藉由昂貴的動力計及智慧刀桿於切削中進行切削力及彎矩的量測，以切削後數據為依據調整路徑，而受限於動力計的大小及儀器費用，實際導入業界應用端有限。為使切削路徑的調整有參考依據並減少實驗架設及測試的時間耗費，本研究開發一估測切削路徑上切削力及切削彎矩變化之技術，在實際切削前即可觀察負載變化，提早對切削路徑進行調整。 本研究以八元樹法進行實體建模，以碰撞檢查及隱函數判斷進行切削模擬，並整合切削力模型及改良後彎矩模型，估測加工路徑上的切削力及切削彎矩變化。本文以UG(Siemens Unigraphics)進行路徑規劃，並輸出CLSF(Cutter Location Source File)檔及零件模型STL(STereoLithography)檔，其中CLSF檔包含切削路徑、刀具尺寸、空間座標轉換等資訊，而STL檔在經過轉換後成為待切削素材，兩種檔案類型最後皆匯入Matlab軟體進行切削模擬及力學估測。 本論文最終以動力計與智慧刀桿於三軸及五軸工具機進行檢驗，於三軸部分的驗證，實驗及估測結果上之輪廓及幅值皆十分相近，而五軸部分則於整合TNCscope各軸位置及刀尖點速度資訊後，有效修正進給速率及模擬切削力，使輪廓更加接近真實切削行為，可供業界做為調整切削路徑之可靠參考依據，並可做為未來設計等彎矩切削之速度控制器的依據。

The cutting force and bending moment in milling operation have a great influence on cutting stability, contour accuracy and dimensional tolerance of cutting surface. In the industry, the cutting path and cutting data adjustment are usually carried out by trial and error method to reduce the excessive change of cutting force. In academic community, the cutting force and bending moment are usually measured by expensive dynamometers and sensory toolholder during cutting, and the path is adjusted based on the cutting data. Since the size of the dynamometer and the cost of the instrument, the actual introduction of the industry application is limited. To provide a reference for the adjustment of machining path, this research develops a technology to estimate cutting force changes and bending moment on the machining path, the load changes can be observed before actual cutting, and the machining path can be adjusted in advance. In this thesis, the octree method is used for solid modeling. Collision detection and implicit function judgment are used for cutting simulation. The cutting force model and the improved bending moment model are integrated to estimate the changes of cutting force and bending moment on machining path. In this thesis, UG (Siemens Unigraphics) is used for path planning, and outputs CLSF (Cutter Location Source File) files and STL (Stereolithography) files. The CLSF file contains machining path, tool size, spatial coordinate conversions and other information. STL files are converted into materials to be cut, and both file types are finally imported into Matlab software for cutting simulation and mechanical estimation. This thesis is finally tested on three-axis and five-axis machine tools with dynamometer and sensory toolholder. In the verification of the three-axis part, the contours and amplitudes of the experimental and estimated results are very similar. In the five-axis part, after integrating the information of each axis position and tool tip speed of the TNCscope, it can effectively correct the feed rate and simulated cutting force, so that the contour is closer to the real cutting behavior, which can be used as a reliable reference for the industry to adjust the machining path, and can be used as the basis for the future design of the speed controller for equal bending moment cutting.