机床热误差自适应学习补偿方法研究

Research on Adaptive Learning Compensation Method of Machine Tool Thermal Error

机床主轴在运行过程中,受热容易产生变形,从而造成机床加工后的产品精度下降。对此,设计了机床热误差自适应学习补偿控制方法,并对补偿前和补偿后的效果进行实验验证。给出了机床热误差自适应控制原理图,提出了一种用于识别和更新热误差的外生输入自回归模型。采用加权最小二乘法进行参数自适应更新,从而对机床运行产生的热误差进行补偿。设定热误差的动作控制限值,通过实验检验补偿前和补偿后机床热误差变化结果。结果显示:补偿前,机床运行一段时间后,在X和Z轴方向上产生的热误差较大,都超过了误差的设置范围;补偿后,机床运行一段时间后,产生的热误差较小,都保持在设置范围内。采用自适应学习补偿控制方法,能够降低机床产生的热误差,从而提高机床对产品的加工精度。

During the operation of machine tool spindle,it is easy to deform when heated,which results in the decline of product precision after machining.To solve this problem,an adaptive learning compensation control method for thermal error of machine tool is designed,and the effects before and after compensation are verified by experiments.The principle diagram of thermal error adaptive control of machine tool is given,and an exogenous input autoregressive model for identifying and updating thermal error is proposed.The weighted least square method is used to update the parameters adaptively,so as to compensate the thermal error caused by the operation of the machine tool.The action control limit of thermal error is set,and the results of thermal error change before and after compensation are verified by experiments.The results show that:before compensation and after a period of operation,the thermal errors in X and Z axes are larger than the error setting range;After compensation,the thermal error produced by the machine tool after running for a period of time is small,which is kept in the setting range.The adaptive learning compensation control method can reduce the thermal error of the machine tool and improve the machining accuracy of the machine tool.