CNC加工實驗量測系統之設計與實現

刀具在工具機加工過程中，刀具磨耗會造成刀具切削力降低與溫度上升，導致加工品質下降與加工誤差上升，後續造成加工成品組裝精度不佳等問題，故如何預測磨耗刀具的更換時間成為工具機加工中非常重要的課題。刀具過早汰換會造成刀具浪費，間接增加生產成本；過晚更換亦會增加工件之加工誤差，若在加工過程中產生斷刀現象，除了造成工件損壞外，更會嚴重損毀加工設備，設備維修之停機將影響生產排程。本研究開發一套小型CNC銑床加工機台做為實驗平台，具備自動進料、自動加工、自動量測等功能，可以自動進行大量的工件加工和加工數據的量測與收集，以利後續進行刀具壽命之預估。研究中使用EtherCAT做為機台內許多不同模組之通訊介面，以Visual Studio C#程式語言進行控制程式的開發。透過設定不同的進給速度、切削深度、主軸馬達加工轉速等加工參數進行實驗，系統取得加工時之主軸電流、與轉矩數值和加速計擷取加工中的振動數值。加工完畢後，工件採取隨機取樣或加工路徑中心兩種取樣模式測量加工之深度，計算取得平均切削深度、最大誤差與平均絕對誤差，由上述量測之數值，評估刀具磨耗之程度與推算刀具之壽命。

關鍵字

CNC銑床；刀具磨耗； EtherCAT

並列摘要

During the process of tool machining, tool wear will cause the cutting force of the tool to decrease and the temperature to rise, resulting in a decrease in processing quality and an increase in machining error, which will subsequently cause problems such as poor assembly accuracy of the finished product. Therefore, how to predict the replacement time of worn tools becomes an important subject in machining. Premature tool-replacing will result in waste of tools and indirectly increase the production costs; belated tool-replacing will also increase the machining error of the workpiece. If the tool breaks during the machining process, it will not only cause damage to the workpiece but also seriously damage the processing equipment. Downtime for maintenance will affect production scheduling. This research develops a small CNC milling machine processing machine as an experimental platform, which has the functions of automatic feeding, automatic processing, automatic measurement, etc. This machine can automatically process a large number of workpieces, measure and collect processing data to facilitate follow-up estimation of tool life. In the research, EtherCAT is used as the communication interface among many different modules in the machine, and the control program is developed with the Visual Studio C# programming language. By setting different processing parameters such as feed speed, processing depth, and spindle motor processing speed to conduct experiments, the system obtains the spindle current, torque value and accelerometer to capture the vibration value during processing. After processing each workpiece, either random sampling or processing path center sampling mode is adopted to measure the processing depth, calculate the average processing depth, maximum error and mean absolute error. Finally, the degree of tool wear is evaluated and the life of the tool estimated based on the values collected.