Technical Research On Trajectory Planning Of Optical Surface Polishing And Error Compensation

Optical free-form surface elements have better optical characteristics than traditional optical elements.They are gradually widely used in optical systems,more complex curved structures also increase the difficulty of optical processing.Computer controlled optical surface forming technology(CCOS)uses computer technology and NC servo technology to accurately control material removal and correct surface shape errors,it is an important method in optical processing.The polishing process takes about 60%of the total hours,which directly affects the accuracy and efficiency of optical processing.Therefore,CCOS polishing trajectory planning is the key of polishing technology,and it is significant to the processing of optical free-form surface elementsCCOS is a closed-loop iteratively controlled polishing process.The fixed-point polishing model can not solve the curve motion polishing problem.Based on the Preston equation and the Hertz contact theory,and combined the polar equations of pressure and relative linear velocity,this paper uses the integral method to construct the curve polishing material to remove the profile model.Aiming at symmetrical aspheric surface with rotation,this paper innovatively proposes a material removal model based on the circular polishing of the curvature change.Such as K9 glass and aluminum workpieces,this paper designs the orthogonal test of fixed-point polishing,the polishing experiment and surface shape detection.This paper obtains good experimental results and the fixed-point polishing modelDue to insufficient helix of equal overlap ratio,this paper proposes an innovative method for polishing trajectory planning of the optimal removal amount of the full surface.The overlap length model of curvature change,the polishing area,trajectory residence time and total material removal model determine the processing efficiency The projection method is used to map the spatial polishing trajectories to a plane,it establishes the mathematical relationship between the amount of material removed with the track pitch of the ring polishing and the projection track pitch.The change of contact area,geodesic curvature radius and polishing posture influence the material removal of the curved surface.The relationship between the material removal contour and the overlapping contour.For example,rotationally symmetric aspheric workpiece with material K9,This paper formulates the corresponding polishing program When R?a,it is fixed-point polishing.When R>a,it is ring polished.Overlap length function,polishing residence timeand total material removal verify the actual effect of the trajectory planning algorithmCatia is used to construct the five-axis linkage machine with a single pendulum head and a single turntable structure.The D-H method is used to build model the chain of the machine.This paper derives the homogeneous coordinate transformation of the tool and workpiece coordinate system.Based on the mixed force and position control method,this paper establishs an error compensation model for a five-axis linkage machine tool.The actual error of the polishing point is converted into changes in position and attitude coordinates.For the rotationally symmetric aspheric surface,this paper calculates the position and attitude coordinates of the concentric circle track points and establishs the spatial error compensation and the five-axis motion variation model.This paper uses CATIA to establish a five-axis linkage machine model,it also uses ADAMS to establish a machine tool kinematics simulation model.the simulation tool head uses concentric circular trajectories to polish the workpiece,constant force polishing for error compensation of the polished area.The error compensation model for five-axis linkage machine tool is correct.