Theoretical And Experimental Study On Fixed Abrasive Deterministic Lapping Processing

The rapid development of high-quality,high-precision optical component manufacturing technology has laid a solid foundation for the development of optical technology.Due to their advantages,large aspherical optical elements are widely used in modern optical devices and aerospace field.Lapping and polishing are an important processing methods for manufacturing optical components.The exploration and attempt to find a more efficient,high-quality,controllable lapping process has never stopped.This paper proposes the fixed abrasive deterministic lapping technology for manufacturing large aspherical optical elements.This paper explores the fixed abrasive deterministic lapping process of fused silica glass from three aspects: mechanism exploration,simulation modeling and experimental analysis.1.A highly efficient,controllable fixed abrasive deterministic lapping process was proposed.Through the line lapping experiments,results indicate that the liquid central supply mode is beneficial to the improvement of process efficiency and surface quality compared with the traditional liquid supply mode.Moreover,this liquid supply method can improve the wear of the lapping pad,thereby improving the stability of the lapping removal efficiency.The influence of process parameters on the surface hardness after processing and the material removal mechanism of the fixed abrasive lapping were analyzed.The linear relationships between material removal rate and tool speed,load and time were verified by line lapping experiments with different parameters.Results reveal that the material removal process of the fixed abrasive lapping process conforms to the convolution iteration principle of CCOS.2.A simulation model of the surface topography of the fixed abrasive lapping pad was established based on the unit cell theory and the assumption of uniform abrasive particle size.At the same time,the effects of parameters,such as the size and concentration of the abrasive particles and the shape of lapping pad,were considered in the model.Based on the simulation data of the fixed abrasive lapping pad topography,the calculation model of the contact gap between the lapping pad and the workpiece,under certain parameters was established based on the removal mechanism of the hard and brittle material and the micro-contact between the lapping pad and the workpiece.Furthermore,the point lapping removal spot model was established.The accuracy rates of the point lapping removal spot model were verified by point lapping experiments.3.The convolution operation relationship between the total lapping removal and the point lapping removal was established considering the shape of the lapping pad,the size and concentration of the abrasive particles,the rotational speed and loaded load of the lapping tool,and the trajectory parameters.The fixed abrasive lapping surface generation model was also proposed.For the grid trajectory,the lapping experiment and surface simulation under different parameters were carried out.The accuracy rates of the surface generation model were verified by comparing the PV and RMS values of the surface residual error and the depth of the lapping removal.The influence of different trajectory parameters and process parameters on the band error suppression ability was analyzed by PSD curve.The factors affecting the efficiency and stability of lapping removal were analyzed.The model was modified to improve the accuracy of the surface prediction and the deterministic of the fixed abrasive lapping process.