基于键合图的变压预紧力电主轴热误差建模研究

Thermal error modeling of motorized spindle under variable pressure preload based on the bonding graph method

高速电主轴工作过程中产生大量的热,导致主轴前端产生热变形,严重影响主轴加工精度。本文提出变压预紧力电主轴热误差预测模型,将传热学理论计算与键合图模型相结合,可实时且准确预测同类结构的电主轴热伸长。建立主轴的热-固耦合模型,通过有限元分析得到耦合作用下主轴温度场分布规律;根据温度场分布规律及热能流向,运用热力学理论将主轴整体模型划分节点,并计算出节点的热参数;搭配20-sim平台构建主轴热学键合图模型,将关键节点温度实时监测模块与热伸长模块关联,针对鼻端热伸长量,计算各关键点热变形并完成热误差建模。实验验证表明,所建立的键合图预测模型误差在0.5μm之内,研究成果可为不同工况下的智能电主轴实时热误差补偿提供理论基础。

A large amount of heat is generated during the working process of high-speed motorized spindle,which leads to thermal deformation of the front end of the spindle.The machining accuracy of the spindle is affected seriously.In this study,the thermal error prediction model of the motorized spindle with variable load preload is proposed.The heat transfer theory calculation and the bond diagram model are combined.In this way,the thermal elongation of the motorized spindle with similar structure can be predicted accurately in real time.The thermal-solid coupling model of the spindle is formulated,and the distribution of temperature field of the spindle under coupling action is achieved by the finite element analysis.According to the distribution law of temperature field and the flow direction of heat energy,the integral model of the spindle is divided into nodes by the thermodynamic theory.The thermal parameters of the nodes are calculated.The 20-sim platform is used to establish the thermal bond diagram model of the spindle,and the real-time temperature monitoring module of the key nodes is associated with the thermal elongation module.According to the thermal elongation of the nose end,the thermal deformation of each key point is calculated and the thermal error modeling is completed.Experimental results show that the prediction model error of the formulated bond graph is within 0.5μm.Research results can provide a theoretical basis for real-time thermal error compensation of intelligent motorized spindle under different working conditions.