Multi-Step Optimization Desig Of Weak Structural Parts Of Machine Tools

At present,the machine tool design generally adopts a more conservative approach,such as relying on experience or analogy of similar products.This has resulted in a mismatch between the load that the machine tool structure can bear and the actual load,and the low utilization of materials.The design change cycle is also relatively long,which is difficult to meet the market demand;secondly,there is a lack of a universal method for further improving the performance of existing machine tool designs,and it is difficult to meet increasing product quality requirements.Therefore,this paper proposes a multi-step optimization design method for weak structural parts of machine tools.This method mainly includes four parts: weak structural parts identification,external contour optimization,internal rib design and key size optimization.The PT50 machine tool and the SH523 B double-spindle horizontal machining center are taken as examples to verify the correctness,efficiency and universality of the method.The specific research content is as follows:Firstly,introducing automotive cylinder head / valve flexible production line,and make preliminary design of PT50 machine tool according to the production process,the finite element model of the PT50 machine tool is established,and the static analysis,harmonic response analysis and modal analysis are performed on the whole machine,combining with modal experiments,the weakest structural part of the whole machine is identified as the column.The optimization goals of statics,dynamics,and economics for column are proposed.Secondly,the original column is filled with material,and the interfaces between the column and other components are fixed.The external contour topology optimization is performed based on the compromised planning method,and the shape of the column is redesigned based on the optimization results.The method is used to optimize the internal ribbed plates,the effects of different types of ribbed plates on the performance of the columns are discussed,the principle of ribbed plate selection is summarized,and the internal ribbed plate layout design of the columns is carried out.Thirdly,based on the principle of response surface optimization,the parametric model of the column is established with the key size of the column as design variables;the value range of each key size is defined,and the experimental group is designed according to the CCD method;the response surfaces of different performance indicators are fitted according to the calculation results of the experimental group;the optimal combination of the column sizes is predicted.After the optimization,the maximum deformation of the column is reduced by about 17%,the mass of the column is reduced by 3.4%,and the natural frequencies of the first six modes are significantly increased.Finally,summarizing the PT50 machine tool optimization experience,proposing a multi-step optimization design method for the weak structural parts of the machine tool,and verifing the design method on the SH523 B dual-spindle horizontal machining center.After optimization,the maximum static deformation of the structural part is reduced by 14.93%,and the natural frequencies of the first three orders increase by 9.19%,5.90%,and 32.28%,respectively,the mass is reduced by 0.37%;the optimized structural part is assembled back to the whole machine,and it is found that the maximum static deformation of the whole machine is reduced by 0.76%,and the first three natural frequencies are increased by5.86%,1.24%,and 30.5%,respectively,and the total mass is reduced by0.10%.