數值控制加工中心機程式加工時間估算與鑽孔路徑最佳化研究

The Study on Machining Time Estimation of the Part Program and Drilling Path Optimization for CNC Machining Center

胡其寬(Chi-Kuan Hu)

指導教授 ： 蔡哲雄

國立臺北科技大學/機電學院/製造科技研究所/碩士(2006年)

https://doi.org/10.6841/NTUT.2006.00216

摘要

電腦數值控制工具機(CNC)的加工程式多半應用CAD/CAM系統的後處理(Post-processor)來產生，並且能夠依據使用者所建構之刀具路徑來計算其刀具路徑長，以及依使用者所設定的切削進給率來計算零件加工所需的加工時間。然而，CAD/CAM軟體所計算之零件加工時間並不考慮CNC工具機本身的進給率延遲現象。因此，零件在機台上加工的時間會比CAD/CAM軟體所預估出來的理論值還要長。造成理論值與實際加工時間之間誤差的最大因素來自於刀具移動的加、減速性能，以及在刀具路徑的選擇中是否使用了許多的短線段(G01)來逼近曲線或圓弧的程式段(G02/G03)。本文以雷射動態校正儀(HP-5529A)對數控工具機實際進給率進行量測，並經由量測所得之數據來近似CNC工具機之實際進給率，並經由三軸CNC工具機的加工實例比較，本方法確實能夠準確的預測出工件實際的加工時間。此舉對於規劃生產排程以及估計加工時間成本，能提供更有效的參考依據。
然而由於工具機在進行加工的同時，總加工的時間是由二個部分組合而成，第一個部分為:當加工機在進行加工時，其刀具實際切除材料所需的時間；第二部分則是當刀具在定位移動時，所花費的行走時間，也就是快速定位(G00)的移動時間。有許多的研究都著重在於切削時參數的設定，其目的是能夠讓其路徑達成最佳化，以減少加工所需的時間；但是，卻只有少數的研究著重在於第二部分的研究。旅行銷售員問題(Traveling salesman problem, TSP)是一典型且著名的路徑最佳化方法之一，適用於在工件上鑽許多的孔的路徑規劃，本最佳化方法可求解最短的刀具定位路徑或是最節省時間的刀具定位路徑，以減低生產成本，所以本論文在後半段的部分則是著重在於使用排序演算法，在計算完所有節點之最短路徑後，置入基因演算法將鑽孔路徑最佳化，以做為輸出NC鑽孔程式之依據。

關鍵字

刀具路徑資料 ； 加工時間 ； 旅行銷售員問題 ； 排序演算法 ； 基因演算法

並列摘要

According to the feed rates setting and the tool cutting paths planned by the CAD/CAM system, the post-processor of the CAD/CAM system is able to calculate the part program total machining time on a numerically controlled (NC) machine tool. For a CAD/CAM system, machining time calculating usually has no considered the delay of feed rates of the CNC machine tool itself. Therefore, the actual machining time of a part will be a longer duration than the estimated time by CAD/CAM system. In present study, by using a laser dynamic interferometer (HP-5529A) to measure the actual feed rates of CNC machine tool with some sampling feed rate and move length commands. In this paper, by using the measured data, an algorithm of predicting actual part program machining time is presented. Experiments of pocket milling and free form surface machining are conducted for the verification of the proposed method.
The total machining time of the part program includes the time of real cutting work material and the time of tool positioning movements. Many researchers focus on the cutting conditions analysis in order to minimize part-machining time. But fewer researchers gave attentions on the time of tool positioning movements during machining. Traveling Salesman Problem (TSP) is a typical and famous optimization method for the moving paths problems. In the latter part of this thesis has been using the TSP method to investigate the optimization of the drill positioning paths.

並列關鍵字

Tool location data ； Machining time ； Sorting algorithm ； Traveling salesman problem ； Genetic algorithms

參考文獻

[3]M. M. Flood, "The Traveling Salesman Problem," Operations Research, Vol. 4, pp. 61-75, 1955.

[4]M. Held, R. M. Karp, "A Dynamic Programming Approach to Sequencing Problems," Journal of Society Industrial and Applied Mathematics, Vol. 10, pp. 196-210, 1962.

[5]M. Miroslaw, G. Mohan, and P. Mihir, "Serial and Parallel Simulated Annealing and Tabu Search Algorithms for the Traveling Salesman Problem," Annals of Operations Research, Vol. 21, pp. 59-84, 1989.

[6]R. Karp, "Reducibility among Combinatorial Problems," Complexity of Computer Computations, pp. 85-104, 1972.

[8]Pallot B. and Duchamp R., "Motion Time Calculation for Numerically Controlled Machine-tools," International Journal of Production Research, Vol. 29, pp. 2433-2441, 1991.