Study On Polishing Principle And Expriments Of Magnetorheological Jet Polishing

Magnetorheological jet polishing(MJP)is a sub-aperture polishing technology used in optical processing.It is a high-precision and stable polishing method.Its special processing principle makes it combine the advantages of magnetorheological polishing and fluid jet polishing.It has great potential and advantages in the application of polishing and trimming the shape of small-caliber or large steepness,deep cavity optical parts.However,due to the multi-disciplinary knowledge related to magnetism,fluid mechanics,material grinding mechanics,etc.,the research on the polishing mechanism of MJP is not systematic,and the experimental research is insufficient.In this paper,a kind of MJP machine tool is designed,which has better circulation and mixing mode.With the six degrees of freedom robot,it can be more flexibly and effectively for complex curved surface polishing.Though the finite element analysis of the solenoid was performed using Maxwell software,and the beam focusing effect of the magnetic field device on the jet beam was proved.Through the study of the dynamic theory of MJP,and the use of Fluent finite element simulation software to study the vertical incidence,oblique incidence and edge effects,etc.,the distribution characteristics of fluid velocity and workpiece pressure were studied,and the simulation removal function model was established based on the Preston equation.After that,various factors affecting the removal function(magnetic field,flow rate,abrasive type and concentration,workpiece material,incident Angle,etc.)were studied and analyzed in detail.The accuracy and stability of the MJP equipment are verified,and the good linearity of the MJP removal function to time is proved.The removal functions of different shapes are analyzed,including the generation conditions and characteristics of Gauss-like removal functions,and the characteristics of axisymmetric functions at oblique incidence are systematically discussed.The scope of different removal functions is studied and verified with theoretical model or simulation model.In this paper,the roughness distribution model with time and spatial domains in the removal function region in magnetorheological jet polishing precision optical element are proposed and constructed.By controlling the dwell time of fixed point polishing,the surface roughness can be effectively reduced,thus improving the surface quality of the workpiece.The model laid a foundation,therefore,has important guidance and reference value for the application to the whole aperture polishing.Finally,through the trajectory planning and dwell time calculation of the removal function,polishing experiments were performed on the entire diameter of the optical surface,and the expected goal was achieved,which proved that the MJP machine has reliable stability and accuracy.The feasibility of MJP technology for surface modification of complex curved elements was verified,and the theoretical of the polishing of the secondary rotation surface was analyzed.It is of great significance to the engineering application for MJP technology.