Positioning error prediction and compensation of ball screw feed drive system with different mounting conditions

For semi-closed-loop computer numerical control machine tool, the pitch error of screw caused by thermal expansion can deteriorate the positioning accuracy of ball screw feed drive system. This study presents different prediction models for positioning error of ball screw feed drive system based on the mounting condition, where the total error is separated into geometric error and thermal error. The coefficients in the model are identified using the multiple linear regression method. The prediction model is validated and the error compensation is also done for the X axis of a three-axis computer numerical control milling machine. The test results show that the model developed can well predict the thermal error under any given temperature as well as position during the temperature rising process of ball screw, and it can greatly improve the system positioning accuracy through compensation.

对于半闭环计算机数控机床，热膨胀导致的丝杠螺距误差会降低滚珠丝杠进给驱动系统的定位精度。本研究根据安装条件提出了滚珠丝杠进给驱动系统定位误差的不同预测模型，其中总误差被分解为几何误差和热误差。模型中的系数采用多元线性回归方法确定。对预测模型进行了验证，并对一台三轴计算机数控铣床的X轴进行了误差补偿。测试结果表明，所建立的模型能够很好地预测滚珠丝杠升温过程中在任何给定温度和位置下的热误差，并且通过补偿可大大提高系统的定位精度。