Research On Material Processing Characteristics Of Functionally Gradient Grinding And Polishing Plate

The development of cutting-edge technology has made the demand for precision components more and more intense,the surface processing precision and flatness of the wafers or optical components applied to components directly determine the working performance of the components,but due to the unique physical and mechanical properties of such hard and brittle materials,the traditional processing technology is difficult to achieve uniform removal of component processing surface materials and reduce component performance.In this paper,a new material processing method based on functionally gradient grinding and polishing plate is proposed,which is different from traditional homogenizing plate processing technology,the polishing plate used in this method has the following characteristics: the abrasive particles are soft-bonded in the matrix and in soft contact with the workpiece as a particle reinforced composite;at the same time,the elastic modulus exhibits a gradient distribution along the radial direction of the plate surface,in the case of the K coefficient of Preston's removal function weakly changing or fixed value,in order to achieve uniform removal of each point and flatness of the workpiece surface,the product of the stress P and the relative velocity V at each contact point in the radial direction is set to a constant value.The main work and research results completed in this paper are as follows:(1)Based on the analysis and comparison of the advantages and disadvantages of the commonly used composite mechanical model,the eight-chain network model was used to establish the elastic modulus prediction model of particle-reinforced composites based on size effect,the prediction accuracy of elastic modulus of elastic layer was compared by Mori-Tanaka method model and eight-chain network model through tensile test of elastic layer sample.The comparison shows that due to the influence of particle size on the mechanical properties of the elastic layer,the Mori-Tanaka method has a significant deviation in the prediction of the elastic modulus of the elastic layer,and the eight-chain network model has a good predictability of the elastic modulus within 40% of the particle volume.(2)Establishing the contact model between the elastic layer of the functionally gradient polishing plate and the workpiece,and derived functionally gradient thin layer frictionless contact stress equation by semi-inverse solution method.At the same time,the compensation function H(z)was introduced to compensate the influence of the stress of the non-contacting spindle on the contact stress p(y)of the contact surface,therefore,the preliminary stress equation was obtained.The equivalent stress distribution of the workpiece contact surface under displacement loading was obtained by ANSYS-Workbench simulation.Determined the value range of the parameter N in the function H(z),calculated the contact stress predicted value under the parameter N through Matlab,and kept the fitting error with the simulation result within 10%.Then the analytical expression of the stress prediction equation and the function N(?/h)of the relationship between the parameter N and the amount of depression and plate thickness were obtained.(3)Set up the processing experiment platform,and measured the stress of the workpiece contact surface in each gradient ring under the three sets of ?/h ratio by the film pressure sensor.Thereby obtained from the results: the error of test value of the workpiece contact stress corresponding to the same ?/h ratio but different thickness was within 5%;compared with the predicted value of the stress prediction equation,the error was kept within 10%,which verified the accuracy of the stress prediction model and the correctness of the design concept of the functionally gradient plate.Used a 5-gradient plate made of 1000 mesh silicon carbide abrasive particles mixed with elastic binder to processed K9 glass,and measured the removal amount of K9 glass in each gradient ring,which showed: after processed for 1.5 hours,the uniform removal of K9 glass was better reflected in each gradient ring,the surface pits and scratches were weakened and the surface quality became stable.It was confirmed that the functionally gradient grinding and polishing plate can realize the uniform removal of materials.