Research On Thermal Characteristics Of Rolling Linear Guides And Its Influence On The Contact Stiffness Of Joint Surfaces

As an important guide and support component in the feed system of NC machine tools,rolling linear guide has a very important influence on the performance of NC machine tools.Studying the thermal characteristics of rolling linear guideway and its influence on the stiffness of the joint surface has theoretical guiding significance for improving the motion accuracy of the feed system of NC machine tools and the design level of NC machine tools.In this paper,HSR rolling linear guideway is taken as the research object.Firstly,the thermal characteristics are analyzed and modeled theoretically.Secondly,the temperature change and thermal deformation distribution of rolling linear guideway are simulated and analyzed.Then,considering the influence of thermal deformation and load on the stiffness of the joint surface of rolling linear guideway,a Hertzian theoretical model is established.Finally,experiments on thermal characteristics and stiffness of rolling linear guideway are carried out to verify the correctness of theoretical modeling and simulation results.The effects of thermal characteristics of rolling linear guideway and stiffness changes of joint surface on machining accuracy are analyzed.The main contents of the thesis are as follows:(1)Referring to domestic and foreign literatures related to the thermal characteristics and stiffness of rolling linear guides,this paper summarizes the research status and latest progress of the thermal characteristics and stiffness of rolling linear guides at home and abroad,and determines the research direction and methods of the paper.(2)A theoretical heat transfer model for section of rolling linear guide is established.The movement of the ball in the rolling linear guide and the frictional heat caused by different forms of motion are analyzed.Based on the basic law of heat conduction,the mathematical analytic model of temperature field of the guide rail is established,and the temperature distribution law of the cross section direction of the guide rail is obtained(3)The thermal characteristics of rolling linear guide rail are simulated and analyzed.A three-dimensional model of rolling linear guideway is established.According to the actual motion of rolling linear guideway,the boundary conditions and parameters of static load analysis and thermal analysis of rolling linear guideway are determined.Under different vertical loads,static simulation,thermal analysis simulation and thermal-structural coupling field simulation analysis are carried out to obtain the deformation field,stress field and temperature field of rolling linear guide.(4)Considering the influence of thermal deformation and working load,a theoretical model of the contact stiffness of the joint surface is established,and the law of the change of the contact stiffness of the joint surface is analyzed.Based on Hertz contact theory,the contact deformation of rolling linear guideway raceway is analyzed,the relationship between the center deformation of raceway curvature is established,and the contact stiffness model of the joint surface of guide way is obtained.Considering the influence of thermal deformation,the influence of thermal deformation on the contact stiffness model is analyzed.(5)The experiment of the thermal characteristics of rolling linear guideway and its influence on contact stiffness is designed and implemented.Using platinum thermal resistance,the temperature rise of rolling linear guide under different loads is measured,and the deformation and thermal deformation of rolling linear guide under different loads are measured by eddy current displacement sensor.Based on the data collected by the data recorder,the trend of the influence of temperature on contact stiffness is obtained through data processing.Finally,the experimental results are compared with theoretical analysis and finite element simulation results to verify the feasibility of theoretical and simulation analysis.