Principle And Experimental Study Of Liquid Float Polishing

In this paper, we proposed a new processing technology-liquid float polishing technology based on the polishing mechanism of abrasive jet processing technology, float polishing technology and magnetorheological finishing technology. It has made breakthroughs in the processing principle and technology of large-sized planar optical components to achieve high precision, large area, high efficiency, and low cost processing.The working principles of the liquid float polishing method of non-Newtonian fluid and Newtonian fluid as polishing medium and the design principle of the corresponding polishing grinding head were theoretically explored. The CFD flow field simulation was carried out on the corresponding models of the two fluids by fluent software, and the feasibility of the technology was verified by the simulation results of the pressure and shear force on the surface of the workpiece. For the Newtonian fluid. the influence of different polishing head structure on the machining quality is investigated by numerical simulation. According to the comparative analysis of the simulation results, the fluid flows through the groove on the polishing surface of the polishing head and obliquely strikes on the surface of the workpiece. The polishing head structure corresponding to the incident angle of 60is excellent for polishing the workpieces. For the non-Newtonian fluid, the influence of the inlet pressure of the polishing grinding head on the technology was studied by flow field simulation. The simulation results showed that the shear force and pressure on the workpiece surface increase with the increase of the inlet pressure.The experimental platform was set up, the shear thickening fluid polishing liquid was set up, design a set of experiments, and develop a test plan. By testing the surface roughness of the workpiece,the experimental results showed that the roughness of the K9 glass,decreased from25 nm to 2.5nm,after being polished 90 min.which verifies the reliability of the experimental device system and the feasibility of the technology.The orthogonal experiment was designed.The roughness variation and material removal were used as evaluation criteria to study four key influencing factors: abrasive mass fraction,grinding head inlet pressure,grinding head gravity,mass of dispersed phase in shear thickening phase.For the surface roughness of the workpiece,the difference between the primary and secondary order of the influence of each factor on the roughness of the whole workpiece and the corresponding optimal parameter combination are(main ? time): silica mass fraction is 9%,grinding head pressure is 34.3kg,inlet pressure is 0.3MPa,abrasive grain yttrium oxide mass fraction 14%.For the amount of the material removal,16 sets of experimental results were synthesized.After 90 minutes of polishing,the average the material removal amount is 0.2?m.The optimum combination of factors is that the mass fraction of abrasive cerium oxide is 18%,the inlet pressure is 0.4MPa,the mass fraction of dispersed phase silica in the shear thickening phase is 9%,and the gravity of the grinding head is 40 kg.It was verified by repetitive experiments.In the later design experiment,the polishing time was extended,and the K9 glass material was polished.According to the experimental results,the roughness of the workpiece can reach about 1.0 nm under the current experimental conditions.