Finite element static analysis model of machine tool considering influence of joint surface characteristics
In the digital design of machine tools,there is a problem of large accuracy errors in typical joint surface modeling.To address this type of problem,a method that uses virtual materials to equivalently estimate the static properties of the joint surface was proposed.The finite element static analysis model of the whole machine tool considering the influence of the characteristics of the joint surface was established,and the corresponding static stiffness test experiment was completed.Firstly,a new analytical model for the normal and tangential stiffness of the joint surface was proposed by comprehensively considering the effects of the elastic-plastic deformation mechanism and friction.Secondly,according to the characteristics of different types of joint surfaces,virtual materials were used to simulate the stiffness characteristics of the joint surface,and the relationship between the stiffness characteristics and the elastic modulus and Poisson's ratio of the virtual materials was established and applied to the static stiffness analysis of the entire precision computer numerical control machine tool.Finally,the static stiffness test experiment of the entire process system was carried out.In the stiffness test experiment,the stiffness of the spindle end obtained through the experiment in the X,Y,and Z directions was respectively 26.60 N/μm,41.87 N/μm,and 40.17 N/μm,and the experimental data were compared with the simulation data.The research results show that the relative error of the model without considering the influence of the joint surface is nearly 17%,while the relative error of the model considering the influence of the joint surface is within 5%,which verifies the effectiveness of the finite element static analysis model of the whole machine tool considering the influence of the characteristics of the joint surface.The method that using virtual materials to equivalently estimate the static properties of the joint surface is a feasible method for the digital design of machine tools.
digital design of machine toolsvirtual materials methodstatic properties of joint surfacestatic stiffness testfinite element static analysis modelelastoplastic models