| With the development of optical systems,the demand for optical components has gradually increased.Optical components have important applications in aerospace,space optics,biomedical,and military industries.Simple plane and spherical optical elements have gradually been unable to meet the use requirements of increasingly complex optical systems,and more complex aspheric or free-form surface optical elements are required to meet the use requirements.The manufacture and processing of complex surfaces are one of the key factors that limit the development of the optical system.The processing of complex optical components usually relies on expensive CNC precision machine tools for grinding and polishing,but this way has the problems of high processing cost and limited processing diameter,which makes it difficult for CNC machine tools to achieve large-scale batch processing of optical components.Industrial robots have gradually been applied to optical processing because of their advantages of a flexible degree of freedom,unrestricted processing caliber,and low cost.Therefore,this paper combines the industrial robot with the new bonnet polishing technology and builds a robot polishing system.We try to solve the problems of the robot polishing system in optical processing and lay a technical foundation for developing the robot bonnet polishing technology.The main work of this paper is as follows:(1)Firstly,this paper analyzes the processing principle of robotic bonnet polishing and material removal mechanism,analyzes the motion process of bonnet polishing according to the Preston assumption and Hertz contact theory,simultaneously solves the dwell time,establishes the removal function model,and analyzes the removal function modeling through MATLAB to get the theoretical model of the removal function,and the actual removal function graph was obtained by fixed-point polishing experiment.(2)Secondly,this paper analyzes the positive kinematics of the robot and proposes a tool and workpiece coordinate system calibration method applicable to robotic bonnet polishing for problems such as poor calibration accuracy of tool and workpiece coordinate systems of industrial robots.Different from the traditional calibration method,the tool coordinate system is calibrated with its attitude and position separately,and the high precision calibration of the tool coordinate system is achieved by the six-point method,and the workpiece coordinate system is calibrated with the workpiece turntable as the calibration reference,and the attitude matrix and position matrix of the workpiece coordinate system are calibrated separately,and the calibration is completed by six-position points.Using MATLAB as a tool,the D-H parameter table of the industrial robot is established and the calibration results are verified by simulation calculation.(3)Then,this paper analyzes the robot polishing system,and studies the influence of the robot end position fluctuation,polishing process software,and polishing process parameters on the face shape results.And the impact of robot end position fluctuation on processing is analyzed in detail,and the mesh format error compensation method is proposed to establish the error compensation model and compensate for the error in the processing program,and the compensation experiment verifies that the compensation method can reduce the impact of robot end position and maintain the stability of the removal function.(4)Finally,we built a robotic research and throwing system to perform compensatory processing experiments.Through one cycle of compensation processing,the surface shape of the workpiece improved by 25.3% relative to the RMS before compensation,which proved the effectiveness of the compensation method.Then the polishing experiment of K9 glass with a diameter of 120 mm was carried out.Through three stages of rough polishing,finishing polishing,and six cycles of shaping polishing experiment,the PV value of the workpiece surface shape was reduced from 2.72 λ to 1.016 λ,and the RMS value was reduced from 0.709λ to 0.077 λ.The surface shape convergence effect was obvious.The experimental results show that after the parameter calibration and error compensation of the robot grinding and polishing system are carried out,the surface shape accuracy of the workpiece is improved. |
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