Experimental Analysis And Prediction Of Finishing Effect Of PVA Viscoelastic Magnetic Abrasive Tool

Surface quality is one of the important parameter which affects the performance and life of mechanical parts.The magnetic abrasive finishing technology has been applied to the finishing of bearings,auto parts and shaft parts for that it can improve the surface quality and mechanical properties of the parts.However,the magnetic abrasive tools used at present are mostly magnetic abrasive powders with dispersed particles.They are more easily to disperse and has a poor reutilization.Meanwhile,the preparation cost of them is high.Viscoelastic magnetic abrasive tool is a semi solid processing medium which is made of viscoelastic polymer,magnetic medium phase and abrasive particle phase.For its good fluidity and adaptability,it can fit well with the complex surface.Therefore,it can be widely used to finishing the surface parts such as inner hole,outer circle surface,plane,complex surface with trench and narrow slot.Therefore,the preparation of new magnetic abrasive tool using different polymer as matrix is of great importance for the popularization and application of magnetic abrasive finishing.The project is funded by the National Natural Science Foundation(51175365)and the Natural Science Foundation of Shanxi Province(2017D12076).In this paper,two kinds of viscoelastic magnetic abrasive tools are prepared by using PVA and 107 silicone rubber as the matrix,and experimental study is conducted to analyze the influence of main technological parameters on the processing effect.Based on response surface method and with PVA matrix viscoelastic magnetic abrasive tools as the the processing medium,sets up a prediction model about decrease rate of the surface roughness Ra value was set up.The validity of the model is verified by four sets of experiments and the optimized process parameters are obtained.The specific research contents are as follows:1.In this paper,the research progress of magnetic abrasive surface finishing technology is reviewed,and a new magnetic abrasive finishing medium using 107 silicone rubber and PVA as the matrix are put forward.2.The performance requirements of viscoelastic magnetic abrasive tools are put forward.The preparation technology of viscoelastic magnetic abrasive tool is described in four aspects: matrix selection,surface modification of materials,mixing of abrasive and ferromagnetic phase,and mixing of matrix and two phases.The processing mechanism of abrasive tool is analyzed,and the factors that influence the processing effect of abrasive tool are put forward.3.The viscoelastic magnetic abrasive tools are prepared by using PVA as the matrix,and the outer and inner circle of 6061 aluminum alloy tubes were processed by single factor experiment.The influence of main process parameters on surface roughness Ra are analyzed.The results show that the effect of finishing is different with the change of the selected factors.When the outer circle of aluminum alloy tube is processed,the best processing effect can be achieved when the rotational speed of the workpiece is 600r/min,the particle size of the abrasive is 320 mesh,the mass ratio of the abrasive phase and the ferromagnetic phase of the abrasive tool is 1:3,the mass ratio of the matrix in the abrasive tool and the two phases is 1:1,respectively.When the inner circle of the aluminum alloy tube is processed,the best processing effect can be achieved when the mass ratio of the matrix and the two phases is 1:2,the rotation speed of workpiece is 250r/min,the mass ratio of the abrasive phase and the ferromagnetic phase of the abrasive tool is 1:3 and the particle size of the abrasive phase is 320 mesh,respectively.A longer placement time of the abrasive tool will improve the finishing efficiency,but the mobility and viscoelasticity will become worse,and the processing ability of complex parts will be lost.4.Response surface methodology was applied to analyze the relationship of the factors,their interaction and the change rate %ΔRa of the roughness value of the workpiece.The prediction model of surface roughness is established,and the credibility of the model is verified by designing experiments again.Finally,the existing process parameters are optimized,and the optimal process parameters are obtained.5.A viscoelastic magnetic abrasive tool based on 107 silicone rubber is prepared,and its processing performance is explored by designed experiments.It is concluded that the new abrasive tool has good stability and can be used repeatedly.When the particle size of abrasive phase is 600 mesh,the mass ratio of the abrasive phase and the ferromagnetic phase is 1:3,the crosslinking agent is 0.14 g and the workpiece speed is 350r/min,the workpiece surface roughness value Ra can be reduced from 0.299μm to 0.113μm,the relative decrease rate of Ra value is about 62.2%,and the processing effect is best.