Study On Thermal Errors Simulation And Experiment Methods Of Spindles Considering Machine Tool Structural Thermal Deformation

Spindle is the core component of NC machine tools and an important source of thermal error.At present,the research on the thermal characteristics of the spindle only considers the heat source of the spindle body.However,the thermal errors at the end of the spindle is caused by the coupled thermal field between the spindle and the structures,and the effect of the thermal deformation of the structure on the end of the spindle cannot be neglected.Therefore,it is very important to consider the influence of thermal deformation of structural parts on the thermal error of spindle,in order to study the thermal characteristics of spindle and improve the machining accuracy of NC machine tools.In this paper,the thermal characteristics of spindle system and structural parts were studied from the aspects of simulation analysis,thermal error modeling and experimental testing.Firstly,this paper introduces the distribution of heat sources of machine tools,and establishes the theoretical models of heat generation of spindle system and feed system,as well as the theoretical model of heat dissipation of machine tools,which provides theoretical basis for the simulation and analysis of thermal characteristics of machine tools.The heat transfer process between the spindle heat source and the machine tool structure was analyzed.The mechanism and coupling relationship of the thermal deformation between the spindle and the machine tool structure were studied.The importance of considering the thermal deformation of machine tool components to the study of thermal error of spindle was expounded.Taking a T-type horizontal machining center as the research object,two finite element modeling methods,single spindle system and thermal error of spindle considering structural components,were used to simulate the thermal-solid coupling.It was proved that the thermal error modeling method of the spindle considering structural components can reflect the thermal characteristics of the spindle system more accurately.Based on the deformation field results of the above simulation analysis,the thermal deformation of structures was transformed into the thermal error of guide-slider by using the thermal error model of structures.Based on the multi-body theory,the mapping model of thermal deformation of structural parts to the thermal error at the end of the spindle was established,and the relationship between the thermal deformation of structural parts and the thermal error at the end of the spindle was obtained.Based on the five-point method,a new method for measuring thermal error of spindle was proposed.An experimental system for separating thermal errors of spindles was built.The spindle thermal error separation experiment was carried out on the Ttype horizontal machining center were separated,and the distributions of temperature field and deformation field at different rotating speeds were also completed.Finally,the experimental results were compared with the results of simulation calculation and theoretical modeling.The results show that the simulation model and thermal error theoretical model are reasonable and accurate,and the feasibility of the spindle thermal error separation experiment considering thermal deformation of the structure is feasible.The research results in this paper provide a new method for simulation modeling and experimental detection of thermal error of spindle in precision horizontal machining center.It provides a more accurate theoretical basis and a more comprehensive evaluation method for the thermal balance design stage of machine tools.It is of great practical significance and engineering value to improve the precision of precision machine tools in China.