The Structure Optimization Of Five-axis High-speed Gantry Machining Center Based On Kinematics Simulation

XK2525-80-5X five-axis high-speed gantry machining center is taken as the research object.The rigid-flexible coupled kinematics analysis model of the machining center is established to identify the weakness of the whole machine,and the structures of the related parts are optimized.The main contents are as follows:(1)The rigid-flexible coupled virtual prototype model of the machining center with the column,slide carriage,beam and ram as a flexible body is separately established with Adams and Hypermesh.The average deviation,the standard deviation,the maximum deviation in the movement of the tool nose and the final positioning accuracy of the tool nose are taken as the evaluation criteria.Through the kinematic simulation and calculation analysis,the influences of those four parts on the motion of the machining center are compared.It is found that the slide carriage and the beam in the movement have a greater impact on the X-axis and the Z-axis direction,while the ram has a greater impact on the Y-axis direction.(2)Based on the kinematic simulation results of the slide carriage as a flexible body,the dynamic and static stiffness in X-axis and Z-axis of the slide carriage are optimized.According to the actual project needs,the process of the slide carriage is changed from casting to welding.Eventually,the average deviations of the tool nose in the movement in the X-axis and Z-axis directions are reduced by 50.22%and 15.76%,and the standard deviations are reduced by 43.66%and 44.63%respectively.(3)The static and dynamic stiffness of the beam in the X-axis and Z-axis is optimized by sensitivity analysis and orthogonal test,which reduces the average deviations of the tool nose that caused by the beam by 32.97%and 24.63%,and the standard deviation by 43.70%and 34.78%respectively.The structure of the ram is optimized by the section optimization method,and the movement performance of the machine in the Y-axis direction improved.(4)The new model of the machining center with the optimized slide carriage,beam and ram is established.The static and dynamic characteristics and the kinematic performance are compared with those of the original machine.The results show that although the total mass of the machining center increases by 1.92%under the same load and constraints,the maximum static deformations of the tool nose of the optimized one in the X,Y and Z axes are reduced by 10.49%,3.30%and 14.43%respectively.The first three constrained modal frequencies increase by 5.34%,10.45%and 2.41%respectively.The average deviations of the tool nose in the three axis directions during the movement decrease by 32.97%,6.15%and 24.63%respectively,and the standard deviations are reduced by 43.70%,14.59%and 34.78%.The overall performance of the machining center significantly improves.