Error Modeling And Sensitivity Analysis Of A Ultra-precision Five-axis Machine Tool Based On Part Precision

With the progress of science and technology,micro-parts are used in various fields more and more widely.Micro-parts can improve the utilization of space,reduce the consumption of raw materials,reduce the weight of equipment and save production costs.Many advantages make it have good application prospects.Due to the limitations of the current manufacturing level,micro-parts of the complex shape are difficult to achieve high-precision processing,which restricts its use in the field of high-tech equipment manufacturing.Therefore,improving the processing accuracy of micro-parts is of great significance,for the promotion of miniaturization of high-tech equipment.At present,it is necessary to process a kind of micro-parts,which features are of micro size,complicated shape and high precision.Using the existing ultra-precision fiveaxis machine tool.Processing the parts can not meet the processing requirements.In this thesis,to solve this problem,the error modeling and sensitivity analysis of a ultraprecision five-axis machine tool are carried out,and main influencing factors of the machining error are determined.Methods of reducing the machining error are put forward,and the purpose of improving machining precision has been achieved.The main work of this thesis is as following:A comprehensive error model of ultra-precision five-axis machine tool is established.According to the machine structure,a topological model of the ultra-precision five-axis machine tool is built.Error sources of the machine are analyzed,the error elements generated by each component and the transformation relations of the error matrices in each coordinate system are determined.Through the method of homogeneous coordinate transformation,the tool coordinate system and the work-piece coordinate system are transformed into the reference coordinate system of the machine tool,and the comprehensive error model of the ultra-precision five-axis machine tool is established according to the derived from tool point position and working position.The key error elements of the ultra-precision five-axis machine tool are determined,and variation of the key error elements with processing position is studied.Using the firstorder sensitivity function method,the sensitivity formula of each error element in the comprehensive error model is obtained,and when machine parameters are substituted,the sensitivity coefficient of each error element in the initial position is obtained,and key error parameters of the machine are obtained after normalization.Based on the processing of micro-parts change of key error parameters in other processing positions is also analyzed.Validity of the key error elements is verified by using the comprehensive error model to make machining trajectory simulation,and the coupling relationship between the key elements is analyzed.The shape accuracy and surface roughness of a micro-part is tested,the reason of the machining error is analyzed,and methods of reducing the machining error of the parts is put forward.Since it is difficult to test,the shape error are reflected by roundness error of the part.Correlation between the detected surface and the simulated surface is analyzed,and correctness of the comprehensive error model is proved.Based on the comprehensive error model,influence of key error parameters on the roundness error is predicted.The surface roughness of the part under two kinds of processing position is tested,and influence of the dynamic characteristics of the machine on surface roughness is studied.According to the error analysis and detected result of the part error,methods of reducing the part processing error are put forward.