Material Removal Simulation Calculation And Topography Feature Analysis For Robot Polishing On Curved Surface

Polishing is the key process for surface finishing.Different polishing trajectory can form different material removal distribution on the part surface and therefore influence its usability and service life.A well planned trajectory can form a uniform material removal and anisotropic texture feature on the polished surface,so the surface precision and product quality can be guaranteed.As for various intricate polishing trajectories,if it's possible to simulate the material removal and analyze the surface topography calculated,it will be useful for polishing trajectory planning and optimization,so as reducing scrap rate and shortening production cycle.Besides,because the tilted polishing disk has been applied widely in large scale curved surface polishing,this paper simulates the material removal on curved surface after polishing by various intricate trajectories using it,and the power spectrum density(PSD)and fractal dimension(FD)are used to create an analysis and evaluation method for polishing topography features,which can be used to optimize trajectory parameters.The details are as follow:(1)Analyze and summarize the rule of contact region and contact pressure of tilted polishing disk based on numerical FEM simulations,and the SVM method is used to predict polishing force.Then,based on the Preston equation,material removal rate model of tilted polishing disk is established,which is given as mathematical functions of contact region,contact pressure and relative velocity in three diverse types.(2)Based on the proposed model,a global material removal simulation algorithm based on STL model is given to generate material removal map in pseudo-color,which can present the material removal distribution on part surface and therefore be helpful in trajectory planning and optimization.The k-NN algorithm is embedded to improve efficiency.Then experiments are conducted with a 6-DOF industrial robot and the material removal maps simulated are compared with those of measured to verify the correctness and precision of this model and algorithm.(3)The power spectrum density(PSD)analysis method is applied on both the simulated and measured topographies,through which the material removal and topography features of different trajectory strategy can be revealed.Meanwhile,it also proves that the PSD analysis results of simulated topographies are coincident with those of measured.Therefore,the simulated topography is used to study how the three main parameters of constant radius trochoidal trajectory(CRTT)may influence the PSD,and the optimized parameters can then be figured out during the analysis of topography feature.(4)The fractal dimensions(FD)calculated by differential box-counting method are compare with the roughness parameters first to learn how they relate.Then the influence of different polishing parameters on FD are studied.At the end,associating with the above PSD analyses,the FDs of different trajectory strategies and parameters of CRTT are studied to explore its usability in topography feature analysis and polishing trajectory optimization.