基於三維射線法之多物理量加工模擬系統;Multi Machining Error Simulation System Based on Tri-Dexel Data Structure

[[abstract]]本研究主要目的在開發一套虛擬五軸加工系統，透過APT刀具與Tri-Dexel模型進行加工模擬。透過事前模擬來避免產生不可預期的錯誤，進而解決加工參數設定錯誤所導致的加工成本上升。在模擬切削過程中使用者可隨時檢查切削中的工件是否符合預期，如果不符合使用者可以即時中止模擬，檢討原因後調整參數再次進行模擬。 本系統首先將讀入STL三角網格的三維資料結構轉換為Tri-Dexel資料結構，接著利用本研究推導的APT刀具與讀入的路徑CL點資料結合加工誤差資訊，對Tri-Dexel模型進行干涉判斷與布林運算，可以得到經過切削後的Tri-Dexel模型資料。同時，透過切削過程中所獲得之體積移除率乘上切削力係數可以得到即時的切削力資訊。最後將切削後的Tri-Dexel模型透過Refinement演算法重建回STL三角網格資料，以利使用者監控加工過程是否符合預期。 In this research, we develop a multi-axis CNC machining simulation system. By using Tri-Dexel data structure and with the automatically programmed tool (APT), we can effectively simulate a multi-axis machining behavior in order to avoid undesirable machining errors, hence reducing costs. This system potentially can be integrated with a PC-based controller to simulate the machining on-line. If NC errors are found, the user can stop and suspend the machining. NC tool-path or machining parameters such as federate can be modified or adjusted to reduce the cutting force and regenerate the machining tool-path. Our research transform the STL data of the model into the Tri-Dexel data structure. We then use implicit equations of the APT cutter to calculate the intersections between the Tri-Dexel model and the APT cutter. The NC tool-path provides the multi-axis movement of the cutter. The Tri-Dexel model is intersected and updated after each step of the movement. Through this simulation, our system can calculate the material removal rate (MRR), then multiplied by the cutting force coefficient to obtain the instant cutting force information. In addition, by integrating multiple machining system information, such as servo dynamic error, machine structure deformation error, and spindle thermal error, our system can simulate the predicted NC tool path to include these multiple physical properties into our simulation. The result can be used to estimate and possibly correct the predicted machining error