Modeling Analysis And Experimental Research On Thermal Characteristics And Thermal Error Of High-speed Direct Drive Feed System

With the continuous improvement of modern processing technology on the speed and accuracy of machine tools,the direct drive technology of linear motors has attracted more and more attention.Compared with the traditional transmission method,the linear motor direct drive feed system has significant advantages such as fast feed speed,large acceleration,and high positioning accuracy,which can meet the high-speed cutting performance requirements of precision machine tools.However,the structural thermal deformation caused by the heating of the linear motor will affect the machining accuracy of the machine tool,which restricts the excellent performance of the direct drive feed system to a certain extent.Therefore,this paper takes the high-speed direct drive feed system as the research object,and conducts related research on thermal characteristics analysis and thermal error modeling.The main research work of the thesis includes:(1)Comparing the advantages and disadvantages of the ball screw drive mode and the linear motor drive mode,an experimental platform for the high-speed direct drive feed system is built.Aiming at the heating problem of the linear motor,the electromagnetic loss heating mechanism and its influencing factors are theoretically carried out.Analyze,qualitatively analyze the loss distribution and heating law of the linear motor through the magnetic-thermal coupling simulation.It is concluded that the heating of the primary coil of the motor is the main internal heat source of the direct drive feed system,and various error elements of the feed axis are determined.(2)Based on the finite element method,a thermo-structure coupling simulation model of the direct-drive feed system is established.According to the simulation results of the temperature field and the thermal deformation field,the temperature and thermal deformation coupling relationship between different components are analyzed,and the thermal deformation of the structure is explored.The effect of deformation on various thermal error elements shows that linear guides and grating rulers are the main thermal error sensitive components.(3)By setting up a set of temperature and thermal error measurement system to conduct experimental research,the direct drive feed axis is explored under different load conditions,from cold start to thermal equilibrium.The resulting positioning error is decomposed,and the simulation results are compared with the experimental results to verify the reliability of the finite element model.It is concluded that the positioning accuracy is most affected by the thermal deformation of the structure,and the straightness is less affected by the thermal deformation.(4)Based on experimental measurement data,fuzzy C-means clustering and correlation analysis methods are used to screen out the thermal key points,and the temperature rise of the thermal key points is used as the modeling variable,and multiple linear regression and polynomial fitting algorithms are used to The positioning error of the direct drive feed axis is decomposed and modeled.The model still has high prediction accuracy under different working conditions and can provide accurate compensation values for thermal error compensation.