Numerical Simulation And Test Study On Residual Stresses In Beam Of CNC Gantry Boring And Milling Machines During Manufacturing

The demand structure of domestic manufacturing industry presents a trend of high-end development,and higher requirements are placed on the reliability and precision life of large-scale CNC machine tools.The release of residual stress is one of the main factors that cause the change of the precision of the heavy-duty parts of the machine tool.Severe problems may even cause deformation,cracking,etc.,and have an adverse effect on the reliability and performance stability of the machine tool products.As the key bearing structure of the spindle system of CNC gantry boring and milling machine,the beam has extremely high requirements for dimensional stability,structural strength and fatigue life.Therefore,the study of the residual stress in the manufacturing process of the beam components,and accurately grasp the residual stress distribution and change trends,is an important prerequisite for the analysis of beam performance,but also an important basis for optimization of the beam production process.To establish a complete simulation process for residual stress simulat in the manufacturing process of key basic components of CNC machine tools,improve the accuracy of simulation results,provide guidance for the current machine tool component design and production process improvement,and have important theoretical significance and practical engineering value.The main contents of the paper are as follows:(1)The mathematic model of the stress field of the beam during casting,machining and thermal aging was established,and the theoretical basis of the numerical simulation of residual stress under multi-process conditions was analyzed.From the point of view of numerical algorithms and simulation platform,the consistency of the residual stress data in the form of expression is analyzed,which ensures that the residual stress data can be effectively transmitted during the process simulation of multiple beams.(2)The simulation process of the casting process of the XK24 CNC gantry boring and milling machine beam was simulated,on the coupling analysis of the flow field,temperature field and stress field in the casting process,the residual stress distribution of the beam casting blank was studied;the hole-drilling method was used to quantitatively analyze the residual stress in the base of the beam casting rails.The least square method is used to fit the simulation and measurement values to obtain the correction coefficient,and the residual stress field in the casting is modified to obtain the initial residual stress field of the casting blank that is more in line with the actual production.(3)Based on the residual stress field of casting,the unit life and death method was used to simulate the roughing process.The residual stress near the mounting surface of rails was redistributed due to material removal,and the distribution trend was basically consistent with the test results;then,the thermal aging process was performed.Compared with the uncorrected stress field,the numerical simulation and residual stress test results show that the residual stress of the track surface residual stress obtained from the thermal aging simulation based on the modified stress field is reduced from 33.6% to 6.81%,and the finite element simulation accuracy is significantly improved.(4)The residual stress level of the beam components was evaluated,and the change rule of the residual stress field in the manufacturing process was comprehensively analyzed,and the risk of the beam deformation caused by the residual stress.