Error analysis of high-speed precision micro-spindle equipped with micro-tool in mechanical micro-grinding
Error analysis of high-speed precision micro-spindle equipped with micro-tool in mechanical micro-grinding
复制标题
配备微型刀具的高速精密微主轴机械微磨削误差分析
DOI：
10.1007/s00170-018-1938-5
复制
发表时间：
2018
影响因子：
3.4
通讯作者：
Huang Xiangming
中科院分区：
文献类型：
--
作者：
Li Wei;Li Zhipeng;Ren Yinghui;Huang Xiangming
现有的微主轴系统配备了微型工具妥协的微加工精度和效率，由于他们的大误差。本研究将微工具刀尖之径向误差分为静态机械偏移、热致误差及径向运动误差。微型工具的尖端，具有最小的刚度，是径向机械偏移的主要误差源。提出了一种基于刚度的误差模型来预测微刀尖的径向机械偏移量，预测值与实测值吻合较好。前轴承由于其较大的热损失，在几乎所有转速下的温度都低于后轴承。两个球轴承之间的热增长的差异导致的热致误差。采用最小二乘法对热致误差进行了建模，结果表明，热致误差在最初的1小时内随运行时间迅速增大，随后进入相对稳定状态。所提出的热致误差模型也考虑了主轴热增长的指数特性。与实测值吻合较好。径向运动误差随微刀具悬伸长度的增大而增大，随转速的增大而减小。用最小二乘法对模型进行了建模，并通过实测数据进行了验证。微磨削试验进行了进一步验证静态机械偏移，热致误差和径向运动误差的预测模型。经过误差补偿后，微磨削厚度接近要求值，表明误差预测模型和补偿方案是有效的。
The existing micro-spindle systems equipped with micro-tools compromise micro-machining accuracy and efficiency due to their large error. In this study, the radial error of micro-tool tip was classified into static mechanical offset, thermally induced error, and radial motion error. The micro-tool tip, having the smallest stiffness, was the major error source of radial mechanical offset. A stiffness-based error model was proposed to predict the radial mechanical offset of micro-tool tip, and the predictions were well consistent with the measured values. The front bearing, due to its large thermal loss, had lower temperature than the rear bearing at nearly all rotational speeds. The difference of thermal growths between the two ball bearings resulted in the thermally induced error. The thermally induced error increased rapidly with running time within the first hour and then entered into a relative stable state, which was modeled by the least square method. The proposed model of thermally induced error also considered exponential characteristic of spindle thermal growth in nature. It agreed well with the measured values. The radial motion error increased with the over-hang length of micro-tool, but decreased with the rotational speed. It was modeled by the least square method and validated by the measurements. The micro-grinding tests were conducted to further verify the proposed predictive models of static mechanical offset, thermally induced error, and radial motion error. With the error compensation, the micro-grinding thickness was close to the required value, which showed the error predictive models and compensation scheme were effective.