Static And Dynamic Characteristics Analysis And Structure Optimization Of Vertical Internal Grinder

In the process of internal grinding of small aperture ring workpiece,the grinding wheel diameter is too small to realize high speed grinding,resultin g in low machining efficiency.In order to solve this problem,our research group developed a vertical internal grinder with double spindle and multiple stations.However,it is difficult to evaluate the static and dynamic performance of the machine because of its complex structure,many joint surfaces and difficult parameter identification.In this paper,the double spindle vertical internal grinder as the research object,based on the research of grinding force and joint surface stiffness,the static and dynamic characteristics of the grinder machine,and optimize the configuration and size of the bed and column.It mainly includes the following contents:(1)Grinding force analysis and structure design.The internal grinding process was analyzed from the grinding mechanism and geometric relationship,the grinding force model of unit width was established,and the relationship between grinding force and grinding parameters was explored,providing force parameters for grinding process selection and subsequent simulation analysis.According to the basic requirements of equipment,clear technical requirements,configuration of the machine structure,establish the geometric model of the machine.(2)Modeling and analysis of joint surface stiffness.The stiffness analysis and calculation of the main connecting surfaces in vertical internal grinder were carried out,including screw connection,roller slide and ball screw.The normal stiffness of the connecting piece and the axial stiffness of the screw are calculated respectively.Based on Hertz contact theory,the equivalent stiffness of roller linear slide rail,ball screw and other curved surface contact surfaces was calculated,and an example calculation was carried out according to the actual model of grinding machine.(3)Analysis of static and dynamic characteristics of the whole machine.Based on the grinding force parameters and joint surface stiffness parameters,the finite element model of the whole grinder was established.The static and dynamic characteristics under gravity and coupling of gravity and grinding force were analyzed respectively.The static and dynamic simulation results of the whole machine are analyzed to find out the weak links of the whole machine and determine the subsequent structural optimization objects.(4)Structural optimization.Based on the unit structure method and topology optimization method,the bed and column were optimized for configuration design,and the performance parameters of parts before and after configuration optimization were compared to evaluate the rationality of the new configuration optimization.After configuration optimization,dimension optimization was carried out,response surface models of bed and column were established based on orthogonal test,and the model was evaluated by goodness of fit and correction coefficient.Weight was given to each response function,single objective optimization model was established,genetic algorithm was used to solve,and static and dynamic performance before and after optimization was compared and analyzed.The results show that when the mass of the whole machine increases by 24 kg,the maximum displacement under gravity decreases by about 63.4%,the first natural frequency increases by 10.8%,the maximum harmonic response amplitude decreases by about 62%,and the static and dynamic characteristics of the whole machine are greatly improved to achieve the purpose of optimization.