Research On Assembly Accuracy Of Composite Boring And Milling Center

With the rapid development of the processing industry,the accuracy and intelligence of the machine tools are increasingly demanding.How to achieve high-precision and intelligent processing has become an important issue in China’s current processing and manufacturing industries.This article participates in the 863 project of the National Twelfth Five-Year Plan to study the assembly precision and assembly adjustment of a compound boring and milling center that uses a complex box as a machining object.Establish a comprehensive spatial error model of the machining center,analyze the error of each component,calculate the deformation amount,calculate the assembly adjustment amount,and mainly study the following aspects:(1)Analysis of the structure,accuracy,and inspection accuracy of the compound boring and milling center.Consider the major testing items and objectives of assembly accuracy,and analyze the accuracy of the inspection for machine tool acceptance requirements.Based on the structure and precision of complex box parts,combined with the characteristics of advanced CNC machine tools,the main error sources affecting assembly accuracy are analyzed to determine the design accuracy and distribution.(2)Deformation Analysis of Key Parts of Hybrid Type Boring Milling Center.The finite element simulation software was used to simulate the stress of the machine tool base,and the deformation of the main part was calculated.At the same time,the load was applied to different positions of the beam and the deformation of the beam was obtained.The simulation results lay a mathematical foundation for establishing a comprehensive error model.(3)The division of assembly units in compound boring and milling machining centers.For a large number of complex machine tool assembly parts,it is difficult to analyze the problem one by one,and the assembly unit division based on the assembly relationship is proposed.Through the analysis of the assembly relationship,an assembly relationship matrix is established,and the assembly unit division results are obtained by an intelligent algorithm,which makes it difficult to calculate the accuracy of later assembly.(4)Establish a spatial comprehensive error model for machining centers.Based on the multi-system theory,a topological diagram of the machine structure and a low sequence array are created,and each individual’s wish to determine the Cartesian coordinate system is set.Through homogenous transformation and SDT modeling methods,the error and deformation of each individual in the system are expressed in a matrix form,and a systematic comprehensive error model is established through matrix transformation.(5)Calculate the actual assembly adjustment of the machining center.The dimension parameters,error amount and deformation amount of the machine tool are brought into the system comprehensive error model,and the difference between the ideal pose of the workpiece on the machine tool and the actual pose is the assembly error.Comparing the actual error with the detection accuracy,the assembly adjustment amount can be obtained.