Research On Part Geometric Shape Error Evaluation Method For Precise Assembly

In the precision/ultra-precision micro-mechanical system assembly process,the component geometry shape error is one of the important factors affecting assembly accuracy.Geometric shape error is a mesoscopic geometry,and the relationship between it and assembly accuracy is not enough.In this paper,the traditional shape error evaluation method based on the principle of minimum inclusion is not enough to quantitatively describe the relationship between shape error distribution and assembly precision,and a method for surface shape error evaluation is proposed.The main research contents are as follows:Firstly,two geometric shape error modeling methods are studied.Based on the non-Gaussian simulation and B-spline surface reconstruction of the shape error modeling method,the geometric shape error mathematical model was established.Based on the measured data,the input parameters of the non-Gaussian simulation are determined by analyzing the detection parameters of the actual machined surface.The surface of the machined surface is generated by the non-Gaussian plane simulation method,and the surface shape error is obtained by wavelet filtering.The B-spline surface is used to reconstruct the coordinate error data.Secondly,the assembly precision is calculated based on the difference surface method.Assembly accuracy is characterized as the extent to which the position of the assembled part surface relative to the reference part surface changes after assembly.Based on the surface shape error model,the assembly calculation of the surface of different geometrical features on the surface of an individual part and the ideal surface,as well as the assembly calculation of the two parts surface,gives the method of determining the assembly precision.Thirdly,the part geometry error was evaluated based on the assembly precision index.The geometrical parameters of the parts are calculated to realize the quantitative description of the relationship between the characterization parameters of surface geometric distribution and the assembly precision,and the assembly accuracy parameters are calculated and the assembly precision index is used to evaluate the effect of the geometrical shape error on the assembly precision.And gives the shape error evaluation procedure and examples for rectangular plane,circular plane and cylindrical surface.Finally,the geometric shape error evaluation system for assembly is designed and built based on MATLAB GUI.The quantitative relationship between shape error and assembly precision is studied from the point of view of software system to realize the control of assembly precision.The prototype system is developed and the corresponding verification is carried out for the evaluation and simulation of precision product assembly.