Study On The Magnetorheological Hydrodynamic Pressure Polishing Process For Flat Surface

With the rapid development of optoelectronic technology,information electronics and semiconductor lighting technology,the demand for ultra-smooth surface processing is increasing.Accuracy is required to reach nanometer or even sub-nanometer surface roughness,micrometer-level surface accuracy,and no surface and subsurface damages.The traditional ultra-precision polishing technology is difficult to meet higher and higher requirements because of its low efficiency,high cost,and easy to produce surface damages.In this paper,based on the comparative analysis of domestic and foreign magnetorheological processing technology and hydrodynamic pressure research,combining the principles of cluster magnetorheological polishing with hydrodynamic pressure,a polishing technology,magnetorheological hydrodynamic pressure polishing for flat surface,is proposed to provide an efficient polishing method with no surface damages,and the processing mechanism has been discussed through basic theoretical aspects and process experiments.Firstly,a magneto-rheological fluid dynamic pressure polishing plate with V-shaped,U-shaped,rectangular,hole-shaped and other different disk structures was designed to calculate the dynamic pressure of different structural polishing plates,theoretically analyzing the structure of the polishing plate.The dynamic pressure distribution of fluid,through Matlab,V-shaped structure,U-shaped structure,rectangular structure and other models of pressure and dynamic pressure formula for numerical simulation analysis,get when h1/h2>2,dynamic pressure V-shaped structure>U-shaped Structure>Rectangular structure;When the W2 part occupies a length of about one quarter to one half of the whole microstructure part,the dynamic pressure generated by the V-shaped structure and U-shaped structure is relatively large;V-shaped groove,U-shaped groove,Rectangle groove and array hole structure polished disc structural parameters.The movement forms and material removal mechanism of abrasive particles and magnetic particles under hydrodynamic pressure effect were discussed.Secondly,a polishing force measurement platform for the processing process was set up.The effect of the main influencing factors such as the workpiece rotation speed and the machining gap on the actual polishing force was tested using different structural polishing discs.It was concluded that the influence of different microstructures on the polishing force on the surface of the polishing disc was positive.Inverse effect,in which the V-shaped structure polishing disc and the U-shaped structure polishing disc generate dynamic pressure,and the rectangular structure disc has a negative effect on the polishing force;when the gap is 0.8-0.9mm,the V-shaped disc has a higher positive pressure than the flat disc.Nearly 10 N,the tangential force is nearly 16N;when the rotational speed is 500-550r/min,the positive pressure of the V-shaped structural disk and the U-shaped structural disk is higher than the flat disk by 15 N and 20 N,respectively,and the tangential forces are respectively 8N higher.And about 5N.Correctly designing the surface microstructure parameters of the polishing plate is the key to realizing the magnetic flow variation pressure plane polishing.It is proved that the surface of the polishing plate has V-shaped grooves,U-shaped grooves and other specific surface structures to form the dynamic fluid pressure,and the magnetic current is verified.Change the feasibility of pressure plane polishing.Finally,a magnetic flow variation pressure plane polishing test bench was set up to evaluate the material removal rate and surface roughness,and dynamic pressure polishing without a structured polishing disk was used,and a flat disk was used as a comparison,and the single crystal silicon substrate was The object of the study was a polishing experiment.The effects of workpiece rotation speed,machining gap,iron powder concentration,and abrasive concentration on the polishing effect were investigated.By comparative analysis of experimental data,it was found that different structural polishing plates had a great influence on the material removal rate.Different microstructure polishing plates were used.The material removal rate from large to small was in the following order: V-shaped plate>U-shaped plate> Plane plate> Hole plate>Rectangular plate;the polishing plate with V-shaped and U-shaped grooves on the surface had significantly higher removal rate than the flat plate material.Which V-shaped disk increased by about 25%.Through optimization of process parameters,a 3 ?msilicon carbide abrasive was used to polish the monocrystalline silicon substrate under conditions of processing gap of 1.0 mm,workpiece rotation speed of 550 r/min,iron powder concentration of 20 wt%,abrasive concentration of 8 wt%,and spindle yaw of20 mm.The polishing experiment was carried out on flat disks,V-shaped structures and U-shaped structural disks,in which the V-shaped structural disks obtained an ultra-smooth surface with a surface roughness of less than Ra8 nm,and the silicon surface had a good mirror effect.