Dynamic Analysis And Experimental Research On The Protective Device Of High-speed Guide Rails Of CNC Machine Tools

As one of the important parts of the vertical machining center,the CNC machine tool guide rail protection device is mainly responsible for the protection of the machine tool guide rail and the servo feed mechanism to prevent the entry of dust and cuttings and the corrosion of the coolant.With the development of CNC machine tools in the direction of high speed,precision and environmental protection,their rapid traverse speed can reach 60-120m/min,and the acceleration can reach 1?2g.The guide rail protection device has higher requirements in terms of followability,responsiveness,vibration and noise,so as to ensure the normal operation of the CNC machine tool.However,the maximum following speed of the guide rail protection device produced by most domestic manufacturers is only 48m/min,which is difficult to meet the high-speed operation requirements of CNC machine tools.Therefore,studying the motion law,force deformation and vibration characteristics of high-speed CNC machine tool guards is of great significance for solving the speed limitation of high-speed guide rail guards and improving the design and manufacturing level of high-speed guide guards in my country.Aiming at the problems of poor movement stability and high vibration and noise of the high-speed guide rail protection device,the specific research contents of this thesis are as follows:(1)The component composition,structural function,manufacturing process and assembly method of the high-speed guide rail protection device were introduced.According to its actual operating conditions,the causes of vibration and noise were analyzed,and the research technical route was formulated.(2)According to the theory of multi-body dynamics,the dynamic model of the high-speed guide rail protection device was established,the dynamic simulation of the protection device was carried out using ADAMS software,and the movement law of each cover piece of the protection device was analyzed.Using Ansys Workbench software analyzed its transient dynamics.In a complete reciprocating stage from start to stop,the overall deformation and stress of the protective device were obtained,and it was analyzed that the main plane of the cover was the largest deformation,and the equivalent stress at the hinge of the co-moving mechanism and the cover sheet bracket was relatively large.(3)The multi-body dynamics model of the synchronous mechanism of the high-speed machine tool guide rail protection device was established.Using ADAMS to conduct dynamic simulation analysis on the synchronous mechanism with gaps,it is concluded that the pin near the joint between the worktable and the cover has the greatest influence on the movement accuracy of the synchronous mechanism relative to other pins.At the same time,it analyzes the changing law of the speed,acceleration,contact and collision force of the kinematic pair with the clearance and its influence on the performance of the high-speed guide rail protection device in different clearances.(4)Taking the fixed end cover piece of the protection device of the DVG850 vertical machining center as the research object,a three-dimensional model was established through UG.In a free state,the fixed end cover piece was analyzed of modal using Ansys Workbench software.According to the vibration shape diagram of the simulation results,the vibration pick-up point of the cover in the experimental modal analysis was determined.Then,the modal test analysis of the single-piece cover sheet was carried out by the single-point input and single-point output(SISO)method to verify the natural frequency and mode shape.Finally,the accurate modal parameters of the research object were obtained.By welding the bracket and the cover,the natural frequency was increased,and the structure of the protective cover was optimized.(5)The high-speed protection experimental device was built.According to the design indicators of the high-speed guide rail protection device of the CNC machine tool and the servo feed transmission system,the cover structure of the protection device,the wiper mechanism,the synchronous mechanism and the screw nut pair of the feed transmission system,and the servo motor were designed and selected.The vibration test plan of the protective device was formulated from three aspects of measuring point layout,vibration measurement,and data collection.The high-speed protective experimental device built was used to collect vibration signals at different rapid traverse speeds and accelerations.The vibration signal was analyzed in the time domain and frequency domain,and the vibration performance of the high-speed machine tool guide rail protection device was preliminarily grasped and compared with the simulation results.It was verified that the shock load during start and stop was the main cause of the vibration of the high-speed protection device.This thesis takes the guide rail protection device of the high-speed vertical machining center DVG850 and the protection device test bed as the research object,and uses three methods of finite element method,virtual prototype simulation technology and vibration test to study its kinematics and dynamics.The vibration characteristics of the protective device in high-speed motion are studied.The hinge gap of the synchronous mechanism and the deformation of the protective cover are the main factors affecting the vibration of the protective device.It provides a theoretical basis for the design optimization and structural improvement of the high-speed machine tool guide rail protective device.