全闭环进给机构中光栅尺全行程热误差定量分析

摘要

分析了光栅尺热行为特性影响高精度全闭环进给机构全行程热变形误差产生的原因,以自构建的全闭环反馈的驱动进给机构为实验平台,应用ANSYS为仿真工具,建立了基于光栅尺反馈的不同关键点位置上的进给机构有限元温度场分析模型,以与温升实验数据的对比偏差最小为目标,对不同关键点位置处的有限元模型边界条件进行了修正,以此温度场有限元模型为基础,对不同关键点位置的光栅尺热误差进行了计算,再以径向基函数为基本热变形回归分析模型,对进给机构的光栅热误差进行了定量分析.在所建立实验研究平台上,进行了实验测试验证,结果表明:当进给机构最高温升40℃时,在344mm全行程内,光栅尺热误差定量分析偏差为2.5μr.%Analysis of thermal error resulted from the growth of a linear scale is conducted for a feed drive mechanism with high precision.Thermal behavior finite element models at some critical positions along the feeding direction are established with ANSYS software according to the dimensions from an experimental platform,which is a set-up feed drive test rig with full-closed position feedback.The boundary conditions of the FEMs at different positions are acquired with the comparisons of temperature rise between the experimental data from the platform and the simulation results.Through updating the FEMs with these new boundary conditions,the thermal behavior of the linear scale in the mechanism are also recognized at these critical positions.And then a radial basis function is introduced as a regression analysis model to denote the thermal behavior of the scale in the full stroke.The experimental results show that the maximum regression deviation of the thermal behavior of the linear scale in full-stroke falls within 2.5 μm under the condition of the maximum temperature rise to 40 ℃ in 344 mm stroke.