Research On Mechanisms And Device Of Magnetic Reconditioning For Polishing Fluid In Magnetorheological Finishing

Magnetorheological finishing technology has received more and more attention in recent years due to its many advantages.Magnetorheological polishing fluid,as a working medium that directly participates in material removal in magnetorheological finishing,affects polishing efficiency and workpiece quality to a large extent.In the process of magnetorheological finishing,affected by process characteristics and material characteristics,particles in the polishing fluid will inevitably agglomerate and sedimentate,and behave as coagulation of the polishing fluid,which affects the rheological properties of the polishing fluid,and then affects the polishing efficiency and polishing quality.Therefore,this thesis puts forward the idea of magnetic reconditioning of magnetorheological polishing fluid in the finishing process,and studies the feasibility and mechanism of magnetic reconditioning,as well as the influence mechanism and law of different magnetic field characteristics on the reconditioning effect,develops a magnetic reconditioning device,and carries out related experiments.The main content of this thesis is as follows:A particle dynamic model of magnetorheological polishing fluid based on the discrete element method is proposed and established,which provides a method for the study of the microstructure,dispersion state,and particle movement of the polishing fluid under a magnetic field.Based on the research on the rheological characteristics of magnetorheological polishing fluid,experiments on shear characteristics are carried out to verify the model.The evaluation index for the agglomeration and sedimentation of ferromagnetic particles and abrasive particles is established,and the typical coagulation behavior of polishing fluid with different mass fractions of ferromagnetic particles during magnetorheological finishing is studied.The simulation and experimental research of static magnetic field restraining magnetorheological polishing fluid coagulation are carried out,and the formation mechanism of related phenomena is analyzed and explained from the perspective of microstructure.Based on the obtained coagulation state of the polishing fluid,the mechanism of magnetic reconditioning polishing fluid by the dynamic magnetic field is studied,and the feasibility of realizing redispersion of particles is proved.Aiming at the characteristics of the direction,intensity waveform,intensity frequency,intensity amplitude and quantity of intensity period of the dynamic magnetic field,from many aspects such as the range of motion of particles,the speed of chain formation,and the chain structure,the mechanism and law of the influence of the magnetic field characteristics on the reconditioning effect are studied and obtained.On the basis of the above research,the magnetic field arrangement scheme,the magnetic pole arrangement method and the bearing structure of the permanent magnet group of the magnetic reconditioning device have been studied.The magnetic reconditioning device has been developed,and the magnetic reconditioning experiment of the magnetorheological polishing fluid is carried out,which verified the effectiveness of the method of the magnetic reconditioning of the polishing fluid in magnetorheological finishing studied in this thesis.