高精度动态切削力自感知智能刀具的研究

Research on High Precision Dynamic Cutting Force Self-perception Intelligent Tool

切削状态监测是高档数控机床实现智能加工的必备功能,而切削力测量是进行切削状态监测最直接、有效的方法。目前商业化的切削力测力仪由于体积大、价格贵、兼容性差等原因,难以满足实际工业生产的应用要求。针对机械加工过程中动态切削力的准确测量这一研究目标,提出了一种具有切削力自感知功能的智能刀具,该智能刀具以刀杆作为弹性敏感元件、以半导体应变计作为信号转换元件;通过理论计算和有限元仿真,确定了封装半导体应变计的最佳应力区域以及传感器测量电路的设计方案。所研制的智能刀具结构紧凑、兼容性好、精度高、动态特性好,试验结果显示主切削力Fc方向的静态精度为1.799%、横向交叉干扰为2.610%,进给力F_f方向的静态精度为1.628%、横向交叉干扰为0.694%,智能刀具的固有频率为1 778.98 Hz,可以满足在机床主轴转速不超过26 685 r/min的高速切削过程中准确测量动态切削力的应用需求。

Cutting condition monitoring is an essential function for high-grade CNC machine tools in intelligent machining, meanwhile the cutting force is a direct and effective method for cutting condition monitoring. At present, commercial cutting force dynamometers doesn’t meet the demands of industrial application effectively as a result of their large volume, high price as well as poor compatibility. In order to accurately measure dynamic cutting force in machining process, an intelligent tool with cutting force self-perception function is presented. The cutter bar is used as an elastic sensitive element and the semiconductor strain gauge is used as signal conversion element. On the basis of theoretical calculation and finite element simulation, the optimal stress area for packaging the semiconductor strain gauges is determined, and the sensor measurement circuit is designed. The newly developed intelligent tool is characterized with more compact structure, better compatibility, higher precision and even better dynamic performance. Experimental results show that the intelligent tool’s static accuracy error in the Fc direction is 1.799%, the lateral cross-interference is 2.610%;and its static accuracy error in the Ff direction is 1.628%, the lateral cross-interference is 0.694%. With a natural frequency of 1 778.98 Hz, the tool can be used for dynamic cutting force measurement in the high-speed cutting process when spindle speed does not exceed 26 685 r/min.