Research On A New Type Of Finishing Device And Process Test Based On Multi-Poles Coupling

With the development of science and technology,the requirements for the accuracy and surface quality of products in various fields are becoming increasingly strict.Surface finishing is the key process to improve the surface quality.Based on the research of traditional finishing methods,magnetic field-assisted finishing has been proposed as one of the non-traditional finishing methods.In order to further improve the surface quality and meet the high requirements in application of the product,a novel method based on multi-poles coupling was investigated in this thesis.Accordingly,a new finishing device was designed.The pole arrangements of the magnetic field generator were simulated and analyzed to determine the optimal magnetic pole arrangements using finite element simulation.A surface finishing method called magnetic shear thickening finishing was proposed.Meanwhile,the magnetic shear thickening finishing media was developed.Surface finishing experiments were performed on the surface of titanium alloy(Ti-6Al-4V)worpieces.A novel multi-poles coupled finishing device was designed and manufactured.The designed device mainly consisted of magnetic field generating device,baffle,and C-rotary table.The magnetic field effects of single and multiple magnetic poles were theoretically analyzed,and the distribution of magnetic field under the coupling of multiple magnetic poles was revealed.The magnetic field generating device consisted of magnetic poles and a circular disk,which made of NO.45 steel.64 magnetic poles were placed on the bottom of the disk.The magnetic distribution can be adjusted by varying numbers of magnetic poles,and the arrangement of N and S poles.The baffle was fixed with the C-rotary table using four screws for finishing media placement.The workpiece was fixed on the main spindle of the machine center,which was capable of realizing the rotation of the workpiece.The workpiece and the finishing medium were moved relative to each other to remove the material and attain the finishing of the workpiece surface.Based on the finite element method,simulation analysis of the magnetic field line distribution and the magnetic field intensity of the multi-pole-coupled finishing device were conducted.Moreover,the optimal configuration of the magnetic pole was determined.Compared with the other magnetic pole arrangements,the N-S-N arrangement had more closed loops of magnetic field lines and stronger magnetic field strength.A comparison experiment between simulation and measurement results was performed to verify the validity of the simulation method.Magnetic abrasive media were prepared.An experimental platform integrated with a 4-axis machining center was set up to perform finishing experiments on the surface of titanium alloy(Ti-6Al-4V)worpieces.The effects of C-rotary table speed,spindle speed,working gap,carbonyl iron size and Si C abrasive size on surface roughness and machining efficiency were experimentally analyzed.Under the experimental processing conditions of 160 r / min C-rotary table speed,700 r / min spindle speed,0.7 mm working gap,250 μm carbonyl iron powder and 150 μm Si C abrasive,the surface roughness decreased from 1.2 μm to 0.073 μm after 90 min finishing.Metallurgical microscope and SEM observation results showed that there were no obvious and continuous scratches on the finished surface of the workpiece.The surface roughness was significantly improved.Further finishing experiments were performed on the surface of the titanium alloy produced by laser additive manufacturing.The surface roughness decreased from 6.0 μm to 0.793 μm after 150 min finishing.Experiments on magneto-rheological finishing were carried out to verify the effectiveness of the desigend finishing device using an improved baffle plate.A magnetic shear thickening finishing process was proposed.The shear thickening finishing media was developed.The magnetic shear thickening finishing process was studied to prepare magnetic shear thickening finishing media.Based on an established platform integrated with 4-axis CNC,finishing experiments on the surface of titanium alloy(Ti-6Al-4V)were carried out to explore the surface roughness change with varying C-rotary table speed,spindle speed,working gap and magnetic pole arrangement.After 60 min finishing,final roughness of 0.69 μm was obtained from the initial 0.2 μm under the experimental conditions of C-rotary table rotation speed of 300 r/min,spindle rotation speed of 50 r/min,working gap of 0.7 mm,and N-S-N magnetic-poles arrangements.The effectiveness of the proposed magnetic shear thickening finishing process and finishing media were verified.