Research On The Effect Of Thermal Deformation Of Precision Machine Tool Feeding System On Repeatability

Repeatability of CNC machine tool is an important indicator of performance and is an important factor that affects the consistency of batch processing.Feed system is a moving part.The relative movement between the components will produce thermal deformation.It seriously affects repeatability.Therefore,studying the thermal deformation of the feed system has an important engineering significance to improve the repeatability.In this paper,the feeding system of uniaxial repeatability mechanism research platform is taken as the research object.The influence of the thermal deformation of the feed system on the movement error and repeatability is analyzed.The main research contents are as follows:(1)Uniaxial repeatability mechanism test bed was designed,the bed and worktable are optimized.The finite element model of the feed system and the spring model between the guide rail and the slider,the screw and the nut are established,the equivalent stiffness and damping of the spring model are calculated.(2)Based on the theory of thermodynamics,the main heat source of feed system is theoretically modeled,the heat generation of the main heat source and the heat dissipation of the main part of the feed system are obtained,which provides the theoretical foundation for the finite element simulation analysis and heat source research of feed system.(3)The application of layered simulation method for repeatability.Firstly,the temperature field and the structure field analysis of the screw layer is carried out.The thermal deformation of screw and rail are obtained under different time and temperature.The deformation on the worktable is extracted,and the movement error and repeatability are calculated.(4)The experimental platform of uniaxial repeatability mechanism was taken as the experiment object,the thermal characteristics experiment of repeatability was carried out.By analyzing the experimental data under different states,the influence rules of the thermal deformation of the feed system on the repeatability are obtained.It verifies the correctness of the finite element simulation model.The measures to suppress repeated positioning errors are proposed to improve the repeatability.The paper studies the influence of thermal deformation of feed system on the accuracy of repeatability.Meanwhile,a new finite element modeling method of screw and nut and the method of layered simulation are proposed.It provides a new idea for FEA simulation of feed system.