Research On Spatial Offset Trajectory Of Bonnet Polishing Based On Mesh Parameterization

Currently,there is an increasing demand for precision machining of curved surfaces in the fields of aerospace,automotive manufacturing,electronics manufacturing,medical equipment,and optical manufacturing.Bonnet polishing,as a type of ultra-precision polishing technology,is commonly used for the precision polishing of curved workpieces due to its high overall flexibility and adhesion to the workpiece.However,in Bonnet polishing,the edge effect of the workpiece often does not converge due to processing technology,trajectory planning,and other reasons.In response to this phenomenon,this paper proposes a polishing bias path generation method that can maintain the polishing edge shape.This method is based on the mesh surface model of the workpiece and uses parametric grid technology as the basis for trajectory planning of the workpiece surface,thereby solving the problem of the edge effect of the workpiece not converging.The main research contents of this paper are as follows:(1)Research on the identification and optimization of Mesh segmentation points.First,the least squares conformal mapping method is used to generate trajectories and improve the formula for mesh model expandability.Secondly,the reason for the production of parametric grid conformal energy is analyzed,and the relationship between conformal energy and Gaussian curvature is studied.Finally,based on the correlation between the two,a method for identifying segmentation points is proposed,and simulation results show that this method can reduce the conformal energy of the parametric grid.(2)Research on the Edge effect processing method of Bonnet polishing.Firstly,the methods to deal with boundary effects in Bonnet polishing are analyzed,and the Lift up Bonnet method is determined to control the Bias path pitch to generate the Bias path.Secondly,a velocity function is established based on the principle of Bonnet polishing,and a pressure function for the polishing zone is established using Hertz contact theory.The Preston equation is used to establish the function for removing material in Bonnet polishing.Finally,the bias pitch generation rules are determined based on the removal function.Simulation analysis shows that this bias rule can provide a guarantee for controlling the pitch of the Lift up Bonnet method.(3)A method for the Bias path is proposed.Firstly,the boundary is segmented and fitted by Bezier curves,and the Bias path is generated using the normal of the Bezier curve.An improved method for the Bias path distance is proposed,which is used to improve the trajectory mapping under residual deformation after Mesh segmentation.Calculations show that this method can make the spacing between the mapped trajectories more uniform.(4)Experimental verification of Bonnet polishing based on the Bias path.Firstly,the improved Bias path is generated using MATLAB.Secondly,four types of trajectories,including the scanning trajectory,the contour trajectory,the Parametric grid before and after improvement,are simulated and compared using Mastercam.The degree of deformation of the four trajectories is compared,and the uniformity of the trajectory mapping is analyzed.Finally,a comparison experiment on Edge effect and a polishing experiment are conducted using a robot Bonnet polishing system.The results show that the Bias path can converge the Edge effect to a certain extent,and the surface roughness can reach an (6 = 0.058)value.