Modeling And Optimization Technology For Meta-action Unit’s Key Quality Characteristics Of The Machine Tool Based On The Motion Transfer Coefficient

CNC machine tools are the basic manufacturing equipment of the national manufacturing industry.With the gradual improvement of domestic CNC machine tools’ functions,the insufficient quality of domestic CNC machine tools has gradually become the main reason restricting its development to the high end,and the parts’ feature error of the machine tool is one of the main reasons affecting the its quality.In order to ensure and improve the quality of domestic CNC machine tools,it is necessary to optimize the key quality characteristics of CNC machine tools from the perspective of parts’ feature error control.Meta-action theory reveals the essence of complex electromechanical products’ function realization from the perspective of motion transmission.The basic structural unit obtained through FMA structural decomposition-Meta-action unit is the smallest structural unit inheriting the main quality characteristics of CNC machine tools,which provides a universal technical basis for the fine analysis and control of CNC machine tools’ multiple key quality characteristics.This paper takes the Meta-action unit as the basic object of modeling and optimization of machine tools’ key quality characteristic.Starting from the main interested parties of CNC machine tools,through the analysis and ranking of the machine tools’ quality characteristic,and combined with the relationship between the machine tools’ quality characteristic and the Meta-action units’ quality characteristic,the key quality characteristics of Meta-action units are defined.Starting from the definition of the Meta-action unit’s key quality characteristics,the concept of the Meta-action unit’s motion transfer coefficient is introduced.Based on the relationship among the parts’ feature error,the motion transfer coefficient and the key quality characteristics of the Meta-action unit,and taking the motion transfer coefficient as the intermediate variable,the mapping model between the parts’ feature error and the key quality characteristics of the Meta-action unit is established.Based on the key quality characteristic model of the Meta-action unit,optimization of the Meta-action unit’s key quality characteristics is realized by controlling the feature error of the parts with the goal of minimizing the unit’s comprehensive manufacturing cost and the key quality characteristics loss.The specific research contents of this paper are as follows:(1)Analysis and extraction of the Meta-action unit’s key quality characteristics.In view of the difficulty in analyzing and controlling the quality characteristics of CNC machine tools due to their complex structure and various quality characteristics,the FMA structural decomposition method of complex electromechanical products is used to decompose the CNC machine tools,and the basic object for the study of CNC machine tools’ key quality characteristics – Meta-action unit is obtained;This paper analyzes the composition of the main interested parties of the CNC machine tools,analyzes the quality characteristics composition of the CNC machine tools by using the use case analysis method for different main interested parties,and ranks the quality characteristics of the CNC machine tool by using the fuzzy evaluation method combining the three parameter interval grey number,fuzzy comprehensive evaluation and projection index function,so that the key quality characteristics of the CNC machine tools are extracted.According to the inheritance relationship between the machine tools’ quality characteristic and the Meta-action units’ quality characteristic,the key quality characteristics of the Meta-action units are determined,and the concept of Meta-action units’ motion transfer coefficient is introduced to analyze the characterization indexes of the Meta-action units’ key quality characteristics.Finally,the key quality characteristics related to the feature error of unit’s parts are selected from the Meta-action units’ key quality characteristics,which lays a foundation for the subsequent modeling and optimization of the Meta-action units’ key quality characteristics.(2)Motion transfer coefficient modeling of the Meta-action unit based on the parts’ feature error.According to the characterization index of the Meta-action units’ key quality characteristics based on the motion transfer coefficient,to establish the Meta-action units’ key quality characteristic model,it is necessary to establish the Meta-action units’ motion transfer coefficient model first.Firstly,the motion transfer coefficient of the Meta-action unit is characterized,and the Meta-action unit’s ideal motion transfer coefficient model is established.Based on the ideal motion transfer coefficient model and combined with the characterization index of the Meta-action units’ key quality characteristics,the relationship among the part’s feature error,motion transfer coefficient and key quality characteristics of the Meta-action unit is analyzed;Then,based on the Small Displacement Torsor(SDT)method,the parts’ typical feature error in the Meta-action unit is analyzed and modeled,and the joint surface error of parts’ features is analyzed and modeled based on the parts’ feature error model;Finally,under the assumption of rigid body,the attitude error and position error between the Meta-action unit’ parts are introduced into the ideal motion transfer coefficient model,and combined with the joint surface error model of parts’ features,the mapping relationship model between parts’ feature error and motion transfer coefficient is established,It provides a basis for the modeling of the Meta-action unit’s key quality characteristics based on the motion transfer coefficient.(3)Modeling of the Meta-action unit’s key quality characteristics based on the motion transfer coefficient.Firstly,combined with the motion transfer coefficient and the characterization index of the Meta-action unit’s key quality characteristics,the characterization model of the Meta-action unit’s key quality characteristics is established,and the necessity of considering the motion transfer coefficient uncertainty in the modeling process of the Meta-action unit’s key quality characteristics is analyzed;Secondly,the causes of the Meta-action unit’s motion transfer coefficient uncertainty in the actual operation process are analyzed,and the main factors affecting the uncertainty of the Meta-action unit’s motion transfer coefficient are analyzed based on the internal energy conservation relationship of the Meta-action unit,and the main factors affecting the motion transfer coefficient uncertainty are obtained;Then,based on the motion transfer coefficient of the Meta-action unit,the uncertainty error of the motion transfer coefficient is introduced,and the motion transfer coefficient model of the Meta-action unit with uncertainty is established,the feasibility of the model is verified by the actual running data of the Meta-action unit.The mapping relationship model between the main influencing factors and the uncertainty error of the motion transfer coefficient is established by using radial basis function(RBF)neural network.Finally,combining the Meta-action unit’s uncertain motion transfer coefficient with the representation model of the Meta-action unit’s key quality characteristics,the Meta-action unit’s key quality characteristic model is established,which provides a model basis for the comprehensive optimization of the Meta-action unit’s key quality characteristics.(4)Comprehensive optimization of the Meta-action unit’s key quality characteristics.Part tolerance optimization method is an effective method to realize the comprehensive optimization of the Meta-action unit’s key quality characteristics by controlling parts’ feature error.Firstly,based on the Monte-Carlo simulation method and Kriging agent model,the actual variation range of the part’s feature error under the influence of multi tolerance is modeled to calculate the value range of the parts’ feature error under the influence of multi tolerance.Secondly,the modeling idea of the Meta-action unit’s key quality characteristics comprehensive optimization model is analyzed.Aiming at the minimum probability of the limit value of the Meta-action unit’s key quality characteristics,the constraint conditions of the key quality characteristics are established on the basis of considering the key quality characteristics’ allowable probability,so as to make the constraint conditions more relaxed;According to the traditional tolerance-cost model,the comprehensive manufacturing cost function of the Meta-action unit is established,and the key quality characteristic loss function of the Meta-action unit is established by combining the Meta-action unit’s key quality characteristic model with the design requirements;Taking the minimization of comprehensive manufacturing cost function and key quality characteristic loss function as the objective function,combined with the key quality characteristic constraints of the Meta-action unit,a comprehensive optimization model of the Meta-action unit’s key quality characteristics is established.Then,the multi-objective optimization method is used to solve the optimization model,and the entropy weight TOPSIS method is used to select the optimal solution.Finally,the comprehensive optimization method of the Meta-action unit’s key quality characteristics is explained through example analysis.The optimization results are compared with enterprise’s design results and traditional tolerance optimization design results,and the effectiveness of the comprehensive optimization method of the Meta-action unit’s key quality characteristics is analyzed.The comprehensive optimization method of the Meta-action unit’s key quality characteristics controls the parts’ feature error of the Meta-action unit through the tolerance optimization design for the parts’ key features of the Meta-action unit,obtains the part tolerance combination that reduces the manufacturing cost and key quality characteristic loss of the Meta-action unit at the same time,and realizes the comprehensive optimization of the Meta-action unit’s key quality characteristics,quality improvement of the CNC machine tool is realized at the level of the Meta-action unit.