應用切削力分析於五軸加工路徑優化

Abstract

五軸銑削加工於生醫、航太、模具、汽車等產業中接扮演著極為重要的角色，然而在五軸銑削加工的路徑安排以及刀軸軸向規劃方面仍須仰賴加工者的經驗，雖然大部分之商用CAD/CAM軟體能夠透過內建的幾何模擬來確認路徑是否正確以及有無殘料，卻鮮少考慮到切削加工中的物理量，像是切削力、刀具磨耗、振動等等，而在加工過程中過大的切削力會導致刀具以及主軸的損壞，且切削力的變化也會造成刀具偏擺的問題，從而降低最終的幾何精度，因此該如何降低加工過程中之切削力變動就會是一個重要的議題。 本研究將開發出一套軟體可以在曲面上自動生成五軸加工路徑，並找到在等預留量的加工條件下刀具與工件之嚙合區域(Cutter-Workpiece Engagement, CWE)且計算加工時之瞬時切削力(Instantaneous Cutting Force)，來進行切削加工之物理模擬，並且考量加工時刀軸軸向的變化，提出透過加工曲面之曲率來調整刀軸軸向，用來減少切削力之變動，最後藉由改變進給率達成均勻切削力。 在本研究的驗證結果中可以在欲加工面上自動生成刀具路徑並且成功擷取出CWE特徵，在刀軸軸向的變化上有減少的表現，且在切削力之變動上有均勻化的結果。

Five-axis milling plays an extremely important role in biomedical, aerospace, mold, automobile and other industries. However, the tool path and tool orientation planning of five-axis milling still depend on the experience of the technicians. Although most commercial CAD/CAM software can confirm whether the toolpath is correct or not with residual material through the built-in geometric simulation, but rarely consider the physical quantities in the cutting process, such as cutting force, tool wear, vibration, etc., and in excessive cutting force during machining can cause damage to the tool and spindle, and changes in cutting force may also cause tool deflection problems, thereby deteriorating the final geometric accuracy. Therefore, reducing the variation of cutting force during machining will be an important issue This research will develop a set of software that can automatically generate a five-axis machining tool path on a curved surface. By extracting the Cutter-Workpiece Engagement to calculate the instantaneous cutting force during machining, the physical simulation of cutting processing will be carrying out. By considering the change of the tool orientation during processing, this study proposes adjusting the tool orientation through the curvature of the machining surface to reduce the variation of cutting force, and changing the feed rate to achieve a uniform cutting force. In the verification results of this study, the tool path can be automatically generated on the selected surface and the Cutter-Workpiece Engagement features can be successfully extracted. The variation in the tool orientation movement is reduced, and so do the changes in the cutting force.