卧式加工中心双驱Z轴装配体几何误差分析

Geometric error analysis of dual-drive z-axis assembly in horizontal machine center

摘要:

为了量化和识别出零部件制造和装配过程中制约机床精度的关键几何误差项,基于雅克比旋量模型对卧式加工中心的双驱Z轴的装配几何误差建模进行研究,合并平行度和直线度的公差带区域,确定尺寸和几何公差约束下的几何要素的变动和约束方程,建立含有约束条件的误差模型,将模型仿真数据与相似条件下的实测机床误差数据进行对比验证,最后采用Sobol方法进行几何误差敏感性分析。结果表明:雅可比旋量模型可以有效地定量分析机床几何误差分析,丝杠导程误差、床身平面度、导轨Y向的直线度和运行平行度是影响双驱Z轴运动精度的关键误差项,部分误差项间的耦合作用明显。研究结果有助于辨识影响机床精度的关键误差项,为卧式加工中心双驱Z轴的几何误差分配和补偿调整提供理论依据,建模方法适用于多种装配过程。

Abstract:

To quantify and identify the crucial geometric errors which constrain machine accuracy in the process of manufacturing and fabricating parts, we introduced Jacobian-torsor model to study the geometric error of dual-drive z-axis assembly in horizontal machine center. Combined the tolerance zone of parallelism and straightness, we determined the variation range and constraint equation of torsors based on dimension and geometric tolerance, and then we established the error model. We compared the simulation results and the measured error data of similar conditions, and used Sobol sensitivity analysis method to identify crucial geometric errors. The results show the availability of the Jacobian-torsor model in geometric error analysis quantificationally. The lead error of ball screw, flatness of base, straightness of guide and parallelism between sliders in Y direction were identified as the crucial errors, and the intercoupling of some errors is obvious.