Research On Key Technologies Of Cluster Magnetorheological Polishing Of Fused Silica Glass Complex Curved Surface

As fused silica glass is more and more widely used in various fields,fused silica glass,as a typical difficult-to-machine material,has high hardness,high brittleness and low toughness.It is prone to crack and collapse during processing,which seriously affects the surface quality of the parts after processing.Therefore,higher requirements are put forward for the processing accuracy,quality and efficiency of fused silica glass.Polishing is the longest and most time-consuming step in the whole process,accounting for about60%of the whole manufacturing process.The quality of polishing plays an important role in the processing quality and surface integrity of fused silica glass.Therefore,it is necessary to study an efficient and high-precision polishing processing method.As a low damage processing method,magnetorheological polishing technology is used to polish fused silica glass.However,the existing material removal model of MMR polishing cannot predict the removal of materials during the processing of parts,which has poor processing quality and low processing efficiency.Therefore,this paper studies the surface polishing of fused silica glass based on the self-designed cluster magnetorheological polishing equipment.By establishing a magnetorheological polishing material removal model,the influence of various process parameters on the processing effect is analyzed,and the optimal process parameters are obtained.The path planning of magnetorheological polishing for complex surfaces is studied.It includes the following:Firstly,in view of the fact that the existing material removal model can not predict the material removal during the machining process of parts,the normal load of a single particle,the fluid pressure on the surface of the workpiece,the pressure formed by the gradient magnetic field on the surface of the workpiece and the magnetic interaction force model between the dispersed particles of carbonyl iron powder（CIP）are calculated.Based on the solid phase particle theory,the force analysis of hydroxyl iron powder and cerium oxide（Ce₂O）abrasive particles is carried out.Combined with the extended version of Preston equation and the mechanical properties of actual polishing,the material removal model is established,and the dwell time is Fourier transformed.The material removal model was optimized by convoluting the transformed dwell time with the material removal function.Secondly,in order to further improve the quality and effect of optical surface polishing and realize the uniform removal of polished surface materials,a magnetorheological polishing path planning method considering the physical overlap of complex surface polishing paths is proposed.In the algorithm,the uniform overlap of polishing paths on the free surface is considered.The contact between the polishing head and the complex surface is analyzed.The contact between the polishing head and the complex surface is analyzed.An efficient and accurate equal error step size algorithm for magnetorheological polishing of complex surfaces is proposed.The relationship between residual height,radius of curvature and polishing distance is studied,and the contact area diagram of the planned polishing path in three-dimensional space is established.The effectiveness of the planned polishing path machining trajectory method is verified by simulation and experiment.Finally,in order to verify the effectiveness of the established material removal model,the self-designed reciprocating magnetorheological polishing experimental device and the self-configured magnetorheological polishing fluid with good performance were used to test the material removal function of fused silica glass workpiece.The effects of process parameters such as machining gap,polishing time,workpiece speed,and X-direction deflection on the surface material removal rate and surface roughness were systematically studied.Under the optimal process parameters,the experimental average material removal rate of the workpiece surface is closer to the corrected average material removal rate,and the workpiece surface roughness can reach 1.298 nm.