Thermal Properties Analysis And Experimental Study Of Large-Scale Moving Platform In Vacuum Environment

With the development of scientific research activities in China,some special scenes require equipment to work in high vacuum environment.For example,the chip packaging requires the packaging machine to complete the predetermined action in vacuum;The optical lens with special curved surface needs to be processed in vacuum;In orbit manufacturing requires mechanical equipment to complete manufacturing tasks in outer space.The research object of this thesis is a large-scale moving platform for nontraditional machining in vacuum.Due to the lack of air convection in the vacuum environment to dissipate heat for the equipment,a large temperature rise will occur when the equipment continues to work,which may cause the decline of motion accuracy or damage the equipment.Therefore,it is of great significance to analyze its thermal properties and control the temperature rise for improving the machining accuracy and protecting the equipment.Based on the basic principle of heat transfer and the finite element simulation software,this thesis analyzes the thermal properties of large-scale moving platform which is running continuously in vacuum environment and studies the cooling technology,aiming to ensure that it can work safely and stably in the allowable temperature range in the vacuum environment and ensure the processing accuracy in the design index.This thesis analyzes the heat sources of each axis of large-scale moving platform,calculates the heating power of each heat source by theoretical formula,and studies the temperature field and thermal deformation of the whole machine in atmosphere and vacuum environment by finite element simulation.The simulation results show that in the atmospheric environment,the temperature rise of the whole moving platform is within the allowable range,and the thermal deformation is small,which meets the design index;In vacuum,the temperature rise of the moving platform is too high,which is beyond the allowable temperature range of the motor,and the thermal deformation of the actuator position is too large,which exceeds the accuracy requirements of the design index.Therefore,it is determined that the cooling system must be installed for the large moving platform in vacuum environment.Then the temperature field and thermal deformation of the main heat source servo motor with reducer and the secondary heat source bearing guide rail ball screw are simulated.The results show that the main factors causing the temperature rise and thermal deformation of large-scale moving platform are the heating of motor and reducer.Even if the cooling system is not installed,the ball screw of secondary heat source bearing guide rail and ball screw will not have a great impact.Therefore,the cooling objects of the cooling system are servo motor and reducer.The water-cooling system of servo motor and reducer is designed.Based on the theory of heat transfer,three parameters of the water-cooling system are preliminarily calculated,that is,the total length of the cooling channel,the inner diameter of the cooling channel and the cooling water flow velocity.The theoretical analysis shows that the total length and inner diameter of the cooling channel have little influence on the cooling effect.The larger the cooling water flow velocity is,the lower the steady-state temperature of the system is.The correctness of the theoretical analysis is verified by the finite element simulation.On this basis,the cooling effect verification experiment of the cooling system is carried out,and the cooling experimental device is designed and processed.The water cooling experiment of servo motor and reducer is carried out in the vacuum chamber.The experimental results show that the cooling system can control the heat source temperature in a reasonable range.Finally,the simulation accuracy of the model is improved by modifying the parameters of the simulation model.