Research On Ultra-precision Water Resistant PVA Abrasive Based On Controllable Microporous Structure

The rapid development of the electronic information industry has promoted upgrading processing technology and processing accuracy of difficult-to-process materials such as titanium alloy,stainless steel and copper alloy.Polyvinyl alcohol(PVA)grinding wheel is a resin grinding wheel with high porosity and self-sharpening,which is suitable for machining titanium alloy,stainless steel,copper alloy and other difficult materials.However,due to its poor water resistance,porosity structure is not easy to control,and other factors,the current domestic production of PVA grinding wheel can not meet the needs of the electronic information industry of difficult grinding materials precision machining,resulting in the situation that imported products occupy the domestic electronic information industry precision grinding processing market.This paper is dedicated to solve insufficient domestic PVA wheel water resistance,porosity structure is difficult to control the problem,at the same time improve the water-resistance of PVA grinding wheel,grinding wheel blowhole deside method,developed to meet the electronics industry hard materials,precision processing and water resistance of PVA grinding wheel.polyurethane(PU)and phenolic resin(PF)were first used to modify the water resistance of PVA and adjust the pore structure.And then explore the thickener white latex,abrasive and dispersant addition amount of PVA wheel performance of PEG-400 and the influence of porosity structure,finally using different hardness,porosity and abrasive adding amount of PVA wheel of titanium alloy,stainless steel,copper alloy and polyether ether ketone polishing experiments on four kinds of material,to explore the grinding mechanism of PVA grinding wheel.The results are as follows:1.Infrared spectroscopy verified that the isocyanate group in PU and the hydroxymethyl group in PF reacted with the hydroxyl group in PVA to improve the water resistance of Polyvinyl alcohol foam(PVF).The morphology of PVF with different PU and PF contents was observed by ultra depth of field microscope.It was found that the comprehensive performance of PVF was the best when PU and PF contents were 2%and20%of the mass of PVA solution,respectively.The viscosity of the slurry was 1250 m Pa·s,the hardness was 85 HC,the porosity was 64.9%,and the bulk density was 0.42 g/cm~3.The water absorption rate is 174.4%,the tensile strength is 24.9 MPa,and the pores are evenly distributed in the PVF structure,and the pore size is mainly between 100μm and 200μm.2.The content of thickening agent white latex,abrasive and dispersant has significant influence on the structure and performance of PVA grinding wheel.The addition of white latex can increase the proportion of binder in the grinding wheel slurry,and the mixing with abrasive can greatly improve the viscosity of the slurry,effectively solve the problem of abrasive particle settlement,and improve the porosity of PVA grinding wheel.When the content of white latex exceeds 15%of the mass of PVA solution,the viscosity of slurry is too high,the fluidity becomes poor,the agglomeration of abrasive particles occurs,and the porosity and hardness of PVA grinding wheel are reduced.The porosity of PVA grinding wheel decreases with the increase of abrasive addition,while the volume density increases with the increase of abrasive addition.When the ratio of abrasive mass to binder mass is 4:1,the porosity distribution of PVA grinding wheel is the most uniform and the hardness is the highest.The addition of dispersant can effectively improve the viscosity and dispersion of PVA grinding wheel slurry,reduce the occurrence of abrasive agglomeration phenomenon,and improve the porosity of grinding wheel.3.The hardness,porosity and abrasive addition amount of grinding wheel have a certain influence on the grinding wheel polishing performance.PVA grinding wheel with high hardness and certain elasticity has excellent polishing performance and low wear.Because the pore size in the structure of grinding wheel is too large,the grinding wheel with low hardness has low strength and abrasive is easy to fall off,which accelerates the grinding wheel loss speed.PVA grinding wheel with high porosity has enough space for chip containing,and the grinding chips can be discharged depending on the rotation speed of the grinding wheel,which can effectively avoid the blockage of the grinding wheel.In addition,good self-sharpness of the grinding wheel can be maintained,so that the grinding wheel can be continuously and stably grinding,so as to achieve better polishing effect.The amount of abrasive added has a great influence on the amount of abrasive wear.The higher the amount of abrasive added,the weaker the bonding force of the binder on the abrasive,the faster the shedding rate of abrasive particles will be accelerated in grinding,and the loss of the grinding wheel will be increased.