Study On Precision Mapping Technology Of NC Machine Tool Based On Meat-Action Decomposition

Accuracy is an important index to measure the quality of CNC machine tools.The accuracy of machine tools directly determines the processing quality of parts.Accuracy mapping refers to pre-determining the machining accuracy of the CNC machine tool,and then decomposing and mapping the accuracy of the machine step by step to the design accuracy of each component of the machine tool.The accuracy mapping is an important content in the accuracy design and analysis of machine tools.But the CNC machine tool is an extremely complicated electromechanical system,which has thousands of components,which brings great difficulty to the precision mapping of the CNC machine tool.So far,the precision design of machine tools has been based on the experience of engineers.There is no quantitative theoretical value to refer to,nor is there a suitable mapping method.The result of this status quo is that too high a design accuracy value of parts and components will cause the cost of the machine tool to be too high,and a too low design accuracy value will make the overall accuracy of the machine tool unable to meet user requirements.Based on this,this article combined with the National Natural Science Foundation of China's key projects,in-depth research based on meta-motion decomposition(FMA)CNC machine tool precision mapping technology,the paper includes the following parts.First,the existing precision design methods for machine tools at home and abroad,such as precision modeling and precision mapping,are introduced.The research status of machine tool precision mapping methods,precision modeling techniques,and structural decomposition methods for electromechanical products are analyzed.The problems of decomposition and other methods,finally elaborated the research content and overall framework of this article.Then,the relevant concepts,definitions and decomposition steps of the meta-motion decomposition theory are introduced,and the whole machine is decomposed to obtain the meta-motion using the function-motion-motion decomposition method(FMA);then on the basis of FMA decomposition,the accuracy of the CNC machine tool is analyzed The principle of chain mapping;the precision mapping relationship is divided into tree-shaped precision mapping relationship and chain-type precision mapping relationship.The characteristics of the two precision mapping relationships are introduced.Based on this,the respective mapping principles of the two precision mapping relationships are analyzed;The NC rotary table is used as an example to explain the FMA decomposition method,and the FMA decomposition tree of the CNC machine tool is given,which provides theoretical support for the subsequent accuracy mapping.Then,for the mapping solution of the tree-shaped mapping relationship,a precision mapping method for CNC machine tools based on grey correlation analysis and competitive evaluation is proposed.First,the gray correlation analysis method is used to quantify the degree of influence between the parent layer and the child layer unit,and the influence weight of the child layer unit on the parent layer unit is obtained;secondly,the correlation relationship between the child layer units is established using a competitive evaluation method Model,and use the Lagrange multiplier method to solve the model to obtain the influence weight between the sub-layer units;then the two weights obtained are synthesized to obtain the integrated weight;then consider the cost,reliability and accuracy between Relationship,an accuracy mapping model is established;finally,the milling function is used as an example to illustrate the mapping process of the mapping method.Finally,for the solution of the chain mapping relationship,a precision mapping method for CNC machine tools based on error analysis is proposed.First,the multi-body system is combined with the FMA decomposition tree to describe the chain mapping structure;then the screw theory is used to model the chain mapping structure error,and the spatial error model under the chain mapping structure is established,and the spiral theory is used to The spatial error is synthesized to obtain the comprehensive value of the spatial error;then the manufacturing cost,the spatial error pitch and its size are used as the design criteria,and an accuracy mapping model is constructed,and the NSGA-? genetic algorithm is used to perform the mapping solution;finally,the pallet exchange rack is rotated The unit as an example illustrates the accuracy mapping process based on error analysis.