| The digital control machine tool has a large influence on the development of the national manufacturing industry as the basic support equipment of the modern manufacturing industry.Domestic digital controlled machine tools,are still different from digital control machines in the country in terms of accuracy,performance and reliability Because of this,Japan’s high-end digital control machine tool market has been occupied by overseas machine tools for a long period of time,and the improvement in the reliability level of domestic machine tools has been coming to an end.It is one of the causes of the deterioration of the performance and reliability of the machine tool in Japan.In this paper,we design a 5-axis interlocking machining center with high rotational speed,high accuracy,and high reliability under the support of the national important scientific technology special item,and study the structure sensitivity analysis and optimization design for the beam of machine tool.Finally,the reliability evaluation was carried out for the assembly process of the machining center.Finally,a design process suitable for the small processing center was formed.The main research contents of the paper are as follows.（1）the present state of reliability analysis and reliability management of digital control machine tools in Japan and abroad is discussed.This paper summarizes the design technology line of the five axis machining center for the problems existing in the design of the 5-axis digital control machine tool in China at present.（2）the design criteria of machine tools in Japan and overseas are summarized.We calculated the number of revolutions and power of the main shaft from the actual situation of machine tools.Three dimensional model of five axis machining center was constructed by CATIA.（3）The finite element analysis is carried out on the beam and the bed part,and the structural parameters such as the strength,stiffness and modal of the machine bed and the beam are obtained through the analysis.The sensitivity analysis is carried out for the main moving part in the machine tool,the beam,and the degree and order of the influence of each design variable on the strength and reliability of the beam are obtained when the significant level is 0.025.Referring to the results of sensitivity analysis,with the help of ISIGHT software integrating ANSYS and solidworks software,an optimization model is constructed with the maximum deformation,maximum stress and maximum mass of the beam as the constraints,and the quality of the beam as the optimization objective.The optimal Latin hypercube sampling is used to extract the design variables.Based on the sample points,a response surface model is established,and the genetic algorithm is used for optimization calculation,which proves the effectiveness of the optimization method.（4）According to the assembly process after the design and processing of the machine tool,the reliability evaluation is carried out.The assembly process of this machine tool and the assembly process of two sets of conventional milling machines are selected,and an assembly model evaluation model of a digitally controlled machine tool based on TOPSIS is established,and the weight of each index is obtained using the combined right and left method using the expert evaluation method and the entropy right method.An optimum assembly plan is obtained by deriving the preferential sorting of the three types. |
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