Research On The Key Technology Of Magnetorheological Finishing Of CoCrMo Alloy

CoCrMo alloy is widely used in orthopedic implant surgery due to its high corrosion resistance,fatigue resistance,and mechanical strength.In the finishing stage,the surface of traditional polishing methods is prone to sub-surface damage,substandard surface roughness,and surface deformation,which seriously affects the service life.Magnetorheological finishing(MRF)is a non-contact flexible machining method,which can be applied to the surface machining of workpieces with complex geometry.In this paper,the magnetorheological finishing(MRF)method was used to conduct process experiments on the turn-over cobalt-chromium molybdenum alloy,to explore the necessary conditions for efficient removal of materials,to master the method and principle of achieving proper,uniform,and stable polishing of abrasive particles in MRF,and to achieve efficient and precise machining of CoCrMo alloy surface by this method.(1)Polishing tool Design and rheological behavior analysis of Polishing Fluid:Finite element software was used to conduct magnetic field simulation analysis on magnet size,magnet material and different magnet arrangement.According to the rheological data of magnetorheological finishing fluid during the experiment,the viscosity changes of magnetorheological finishing fluid driven by magnetic field and the removal effect of CoCrMo alloy burr were analyzed.The actual polishing force was collected through experiments,and appropriate polishing tools were selected.To provide the equipment basis for the subsequent experimental research;(2)Research on equal-spacing pseudorange-based paths: In order to solve the linear scratch problem of single path,an equal-spacing pseudorange-based path was proposed based on the two-dimensional path planning method.The stationary points of the scanning path and the spiral path were analyzed to select the appropriate amplitude and direction,and the homogenization of the pseudorandom scanning path and pseudorandom spiral path was realized by the finite element simulation software.The polishing effect of the pseudorandom scanning path with equal spacing was verified by the plane polishing experiment.(3)Research on magnetorheological polishing process of CoCrMo alloy:Kistler9109AA1 dynamometer was used to collect the normal force and shear force in the polishing process,and the influence law of different process parameters on the surface polishing force of CoCrMo alloy was explored by finite element simulation analysis.Taking the surface roughness as the optimization objective,the single factor experiment of different process parameters was carried out on the CoCrMo alloy plane to find the optimal combination of process parameters and to verify the polishing effect experimentally.Finally,the wettability of the polished CoCrMo alloy modified surface was tested.