Preparation Of Magnetorheological Elastic Polishing Composites And Experimental Study On Magnetically Controlled Finishing

With the development of mechanical and photoelectric products to miniaturization and portability,the demand for micro-size parts with high-precision and complex profile is increasing mightily,which brings a great challenge to the traditional ultra-precision machining technology.At present,there are some problems existing in ultra-precision machining technology,such as low machining efficiency,low level of automation,difficulty in machining complex surface and easy to cause damage to the workpiece surface or sub-surface.In response to the above situation,researchers are turning to intelligent micro/nano material field for new polishing methods and tools.In this paper,the intelligent material-magnetorheological elastomer was taken as the matrix to develop a new type of abrasive tool and the corresponding magnetically controlled flexible polishing method was proposed,aiming to process small size parts with high efficiency and precision.The main research contents of this paper are summarized as follows:(1)The market demand and the unsolved problems of ultra-precision machining technology were analyzed.The mechanism and application status of flexible polishing technologies were reviewed,and the research progress of magnetorheological elastomer as the bond of new abrasive tool was summarized.At the same time,a new type of abrasive tool named magnetorheological elastic polishing composites(MREPCs)was presented,whose binder is magnetorheological elastomer and the abrasive is diamond powder.(2)On the basis of process experiments,the raw materials and their proportions required by MREPCs were determined.According to the preparation process of MREPCs,a set of thermo-magnetic-force coupling molding device was designed and the magnetic field distribution of the device was simulated.Finally,MREPCs were successfully prepared by the method of magnetic field-assisted molding,and the microscopic morphology,composition,elastic modulus as well as hardness of the MREPCs were characterized.(3)The mechanical properties of MREPCs under different magnetic fields were analyzed,mainly including their compressive mechanical properties and scratch resistance.Firstly,a set of compression device with excitation structure was designed,and then RGM4100 electronic universal testing machine combined with the compression device was used to conduct single compression testing and cyclic compression testing of MREPCs under different magnetic fields.The results show that the compression elastic modulus of MREPCs increased in different degrees under magnetic fields.At the same time,the damage of the MREPCs was tested with and without a magnetic field by using self-built micrometer scratch device.And the conclusion was drawn that the external magnetic field could inhibit the generation of "separation wave" and thus reduce the wear of the elastomer surface.(4)A special polishing device for MREPCs was designed,in particular,the magnetic field structure of its polished head was designed in detail.And the magnetic field distribution of the polishing head under different working conditions was analyzed by means of finite element software simulation.In addition,the material removal function model of spherical MREPCs was established based on Preston empirical equation,and the influence of different physical parameters on material removal was discussed.