数控机床动压主轴的热误差建模技术研究

为了降低加工过程的热误差,提高数控机床加工精度,基于时序相关分析理论与数值计算方法,建立了一种以温度场分布及加工参数为输入的新型机床主轴热误差建模方法.所建模型由热误差模型、主轴动压轴承热特性模型以及主轴热传递模型三部分组成.该方法首先根据时序相关理论建立热误差与温度测点之间的相关模型,再通过灰色相关理论完成关键温度测点位置与数量的优化,同时,基于数值计算与热传导理论,建立了动压主轴系统热特性模型.以一台大型龙门导轨磨床为实验对象,建立了磨床主轴箱热误差预测模型.实验结果表明,所建立的热误差模型具有良好的热误差辨识性能.

Study of Thermal Error Modeling of Spindle with Hydrodynamic Bearing in NC Machine Tools

In order to reduce thermal errors and improve machine accuracy, a new kind of thermal error modeling method, which takes temperature and machining parameters as input parameters, was established on the basis of time-series regression analysis and numerical computation. The model consists of a thermal error model, a thermal properties model of hydrodynamic bearing and a thermal transfer model of the spindle. Firstly, the correlation model between the temperature data serial of thermal points and thermal error data serial was established on the basis of time series correlation analysis. Then, the number of thermal points was reduced by calculating the grey correlation. In the meantime, the thermal properties model was established based on time-series regression analysis and numerical computation method. A predicting model of thermal error was established for a large CNC gantry grinder. It is indicated by experiment that the thermal error model has good recognition function for thermal error.