Research On Polishing Process And Equipment Of Boron Carbide Lapping Plate

The ring polishing machine is mainly used for high-precision surface lapping and polishing of KDP crystals,optical glass and ultra-precision metal molds.It is an equipment that uses ring polishing technology to process ultra-precision planes.The lapping plate of the ring polishing machine is usually made of cast iron or pouring asphalt on the marble substrate.Due to the soft material,the wear during the ring polishing process is serious,and the material removal of the asphalt lapping plate is small,it is only used for the polishing of the final processing.In this stage,it cannot be used for rough lapping,so it is necessary to explore a new material for lapping plates.In addition,the ring polishing technology largely relies on the experience of the operator,resulting in low processing efficiency.Therefore,the further and systematic research on the ring polishing technology has guiding significance for the ring polishing process and can improve the stability and certainty of the ring polishing.In this dissertation,a new type of boron carbide ring polishing machine is developed by using boron carbide with high hardness,low coefficient of thermal expansion and corrosion resistance to make lapping plate and correction plate.The microstructure and polishing mechanism of boron carbide are analyzed,and the material removal and surface shape of lapping plate are analyzed theoretically.The main research contents are as follows:(1)The material removal model of ring polishing is established based on the Preston equation,and the abrasive particle motion trajectory model is established based on the principle of coordinate transformation,revealing the mechanism of the impact of the velocity and eccentricity on the workpiece material removal and abrasive particle trajectory in ring polishing.The material removal model of swing ring polishing is established,analyzing the influence factors of the swing period,the length of the pendulum rod and the swing amplitude on the material removal of ring polishing.(2)The contact stress between the correction plate and the lapping plate is solved by ANSYS simulation,and the relative lapping distance of the lapping plate is solved by MATLAB.The swing mechanism is added to the ring polishing machine to adjust the position of the correction plate in real time and optimize the process parameters.(3)It is found that the lapping plate made of the special structure of sintered boron carbide has high precision retention.The microscopic contact model between the boron carbide lapping plate-abrasive particles and the workpiece is established,analyzing the material removal characteristics of the boron carbide lapping plate in the ring polishing.The lapping experiment of the boron carbide whetstone is carried out,exploring the microscopic pore change law of the boron carbide.The precision retention experiment of boron carbide is carried out,comparing and analyzing the precision retention of boron carbide in lapping.(4)The boron carbide lapping plate and correction plate used for ring polishing machine are developed.By splicing the hexagonal prism boron carbide whetstones into the nearly circular honeycomb plate and gluing them on the circular marble substrate,the problem that large-area boron carbide is difficult to manufacture is solved.The new type of LP12 D ring polishing machine is jointly developed,which expands the range of materials for ring polishing,and can be used for ultra-precision polishing and polishing of planar components such as ceramics,metals,and optical glass.