精密加工中心直线轴复合误差建模研究

Research on Compound Error Modeling for Linear Axis of Precision Machining Center

为提高精密机床加工精度,针对直线轴几何误差与热误差两类重要误差项进行分析,并提出一种复合定位误差建模方法。首先对两端固定式丝杠进给系统的热误差机制进行分析,建立正弦函数误差表达式,利用有限元法提取丝杠表面温度并作为输入量代入到热误差模型中。利用切比雪夫多项式建立静态几何误差预测模型。将两模型叠加,得到复合定位误差模型。对精密加工中心直线轴进行检测实验,实验值与预测模型对比后发现预测精度达到85%以上,验证了复合误差模型具有较高的预测精度,为直线轴定位误差补偿提供了参考。

In order to improve the machining accuracy of precision machine tools,two important error items of linear axis geometric error and thermal error were analyzed,a compound positioning error modeling method was proposed.The thermal error mechanism of the two-end fixed screw feed system was analyzed,the sine function error expression was established,bying using the finite element method,the screw surface temperature was extracted and substituted into the thermal error model as an input.The Chebyshev polynomials were used to establish a static geometric error prediction model.The two models were combined to obtain a composite positioning error model.The detection experiment on the linear axis of the precision machining center was carried out.After comparing the experimental value with the prediction model,it is found that the prediction accuracy is more than 85%,which verifies that the composite error model has high prediction accuracy and provides reference for linear axis positioning error compensation.