Study On Prediction Method Of Precision Index For Five-Axis Flank Milling Machining

Five-axis linkage CNC machine tools are widely used in high-precision manufacturing.Due to various error factors,machining errors are inevitable during machining.In modern manufacturing,the requirements for machining accuracy are getting higher and higher.In order to reduce machining error and improve machining accuracy,it is necessary to predict various precision indexes on the surface of the part before machining,thus providing an important reference for process planning,optimization and error compensation.To this end,this paper designs a set of precision prediction methods for some precision indexes of Five-axis flank milling parts,and develops a precision prediction systems based on these methods.These precision indexes are: 1.Geometric error,including flatness,cylindricity,parallelism,slope and perpendicularity(face to face)error;2.Point contour error.The main research work of the thesis is as follows:(1)The main error items affecting the machining accuracy of the machine tool are studied,and the motion transformation between adjacent bodies is deduced.After analyzing the geometrical relationship between the cutter location,the cutter contact and the predicted point,the cutter location,The calculation of the cutter axis vector,the cutter contact and the predicted point are realized in sequence.Established a comprehensive error prediction model for five-axis flank milling.(2)Comparing the conventional algorithm and the bionic intelligent algorithm of geometric error assessment,it is determined that the geometric error assessment needs to meet the minimum condition,and the optimization algorithm is particle swarm optimization(PSO);respectively,the flatness,cylindricity,parallelism,inclination and verticality(face-to-face)mathematical modeling is carried out,and an adaptive PSO algorithm that dynamically changes the inertia weight is used to optimize the solution.(3)Based on the principle of CMM,the prediction principle of point contour error is introduced.The ideal and actual machining surface reconstruction based on NURBS is carried out.The method of solving the intersection of normal and actual machining surface is deduced,the prediction of point contour error is completed.(4)A Five-axis flank milling machining precision prediction system was developed.The system development was closely combined with actual needs and modular design.A machining verification test of “S” shaped test piece was designed,and the prediction model was used to calculate the corresponding accuracy index,and measured the values of these indicators actually.The results show that the relative error between the predicted value and the measured value is small and the trend is the same,thus verifying the validity and accuracy of the accuracy prediction method and system.Through the above research,the prediction of geometric error and point contour error of five-axis side milling machining is realized,and the scheme is proved to be feasible by an example.