Parameter Control And Process Optimization Of 3D Cycloid-like Polishing Toolpath

Polishing is a complex but significant process in traditional machining.At present,the wide application of industrial robot in research and manufacturing provides the possibility for automatic polishing.The material removal model and trajectories of automatic polishing are the hotspot in polishing research,which are the basis of controlling uniform material removal and obtaining good surface quality.So far the traditional polishing toolpath has single form.The innovative toolpath and the optimal control of trajectory parameters are needed.On the basis of the study of the polishing material removal model of the flexible pad,this dissertation analyzes the uniformity of material removal of cycloid trajectory and optimizes the parameters combination for free-form surface polishing.Firstly,this dissertation researches on the material removal model of polishing with flexible pad.The contact condition and polishing force are obtained by the contact simulation in Abaqus.The curve fitting and BP artificial neural network are used for the prediction of contact condition and polishing force.Then the verification experiments prove the validity of prediction.According to the pressure distribution in contact area,the polishing material removal depth model of plane and convex surface is established based on the Preston equation.Secondly,in order to solve the problem of uneven material removal in cycloid polishing,the analysis and optimization of the material removal distribution of the cycloid trajectory are proposed.At first the angle-based flattening algorithm is used to generate the cycloid toolpath.By the simulation of material removal depth,the influence of the cycloid step and radius on the uniformity of the material removal is analyzed.Then the relationship between the material removal depth and the feed rate is analyzed and simplified.Based on the relationship,an optimization strategy for the feed rate is proposed.The track points in a cycloid period are divided into several regions and the points in each region have different feed rate,which can achieve uniform material removal.The simulations of material removal depth of single cycloid toolpath are performed on plane and the convex,and the experiment proves the validity of the strategy.Then the parameters combination for free-form surface polishing is optimized.On the basis of the orthogonal test results and combining the material removal model parameters and the cycloid parameters,the influence of these parameters are analyzed by Taguchi method,BP artificial neural network and grey system analysis with surface roughness Sa and surface texture aspect radio Str.Then the optimal combination is obtained and the prediction of surface quality is performed.The simulation and experiment with optimal combination validates the correctness of above methods.Finally,the future research work is prospected: considering the influence of changing the feed rate on other regions while using optimization strategy;analyzing the influence of curvature change on the feed rate optimization strategy and extending the applicability to free-form surface;increasing the number of experiment as the sample of neural network training and analyzing the influence of changing the parameters on surface quality.