Research On The Profile Error Of Complex Surface In-situ Measurement

At present,complex surface parts are more and more widely used.The development of complex curve and surface parts is promoted by demand.The machining error of complex curve and surface is usually measured by the profile error,The method that can accurately describe the machining error help to improve the quality of parts processing and enhance the competitiveness of enterprises.The study of the profile error has some practical value.The main contents of this paper are as follow:1.Complex curve and surface mathematical expressions are established.Aiming at the complex curve and surface with unknown mathematical expressions,a mathematical expression of complex curve and surface CAD model is established with the inverse calculation method of NURBS interpolation.This mathematical expression is used to the evaluation of complex curve and surface profile error.2.Complex curve profile error assessment and visualization are completed.The rough matching model of the actual sampling point set and the theoretical sampling point set is established.The model is solved by using the quasi-differential evolution algorithm.And the measurement reference and the design reference being not uniform is solved,so the actual sampling point set remains approximately the same posture as the theoretical curve.A method that quickly determines the sampling point to the area where the minimum distance corresponding to the complex curve is located is used to solve the minimum distance from the sampling point to the complex curve.The evaluation model of complex curve profile error was established.The simplex method was used to optimize the model,so that the maximum value of the minimum distance between the sample points and the theoretical curve is minimized.Simulation results show that the error of the complex curve obtained by this method is accurate.The mathematical model of in-plane complex curve profile error is established.By using Lab Windows/C VI platform,the error profile of complex curve can be displayed.From the error graph,the error area can be clearly seen and the machining error of the part can be easily analyzed.3.Complex surface sampling point planning and profile error assessment are completed.By applying the method of distributing the complex curve to the complex surface,the programming problem of the complex surface in the in-situ measurement is solved.Compared with other methods,this method is proved to be feasible and effective.The rough matching model of the actual sampling point set and the theoretical sampling point set is established.The firefly algorithm is used to optimize the solving model.The measurement reference and the design reference being not uniform is solved by this model,so that the actual sampling point set remains approximately the same pose with the theoretical curved surface.A method to quickly determine the sampling point to the area where the minimum distance corresponding to the complex surface is located is used to solve the minimum distance from the sampling point to the complex surface.A model for assessing the profile error of a complex surface is established.The model is optimized by the step-by-step acceleration method,which minimizes the maximum value of the minimum distance between the sample point set and the theoretical surface.The simulation results show that the accuracy of the complex surface profile obtained by this method is accurate and the solution accuracy is high.