数控机床工作台误差综合补偿方法研究

Study on Combined Error Compensation Method for CNC Machine Worktables

针对由几何误差与热误差引起的数控机床工作台与主轴之间相对位置变动的问题,通过试验分析其在不同温度状态下的误差数据,得到机床工作台平面度误差随热变形保持不变的规律,并提出了一种数控机床工作台平面度误差与主轴热误差的综合补偿方法。该方法通过分别建立工作台平面度误差模型和热误差模型,并运用叠加原理建立综合误差补偿模型,对传统固定单位置点建模补偿方法的原理性缺陷进行了改进。结合机床关键部件的实时温度值和刀具位置的实时坐标值,计算出了全工作台各区域各温度阶段的误差补偿值,进而实现了全工作台主轴轴向综合误差的实时补偿。检验及分析结果表明,相比于传统固定单位置点热误差建模补偿方法,该方法所建模型残余标准差减小约7μm,精度提高比例达到50%;单次最大补偿残差减小约11μm,精度提高比例达到60%,大幅度提高了机床的加工精度。

To avoid of the relative position problems changing between the worktable and the main spindle of any CNC machine because of geometric errors and thermal errors. The error data at diffe--ent temperatures were obtained through experiments, the rules of the flatness errors on worktables were obtained remaining unchanged with the thermal deformation, and a kind of comprehensive com-pensation method of the flatness error and thermal error on worktables of CNC machine tool was pro-posed. In this method, the flatness error model and thermal error model were established separately, then the comprehensive error compensation model was established by using the superposition primi- ple. The principle’s defects of the traditional fixed point model compensation method were corrected. Based on the real-time temperature values of the key parts of CNC machine and the real-time coordi-nate values of the tool positions, the error compensation values of each stage of the whole working ta-ble were calculated. And then the real-time compensation of the overall axial errors of the spindle on the whole working table was realized. The accuracy of CNC machine are improved by using the pro-posed thermal error compensation method. Compared with the traditional single point thermal error compensation method, the standard deviation of the integrated model is reduced by about 7 μm after analysis, and the accuracy ratio is up to 50%. The maximum compensation residual is reduced by about 11 pm, the accuracy ratio of lift is up to 60%.