摘要
Abstract
objectives:With the advancement of the times,the requirements for processing quality and efficiency are becoming higher and higher.Regarding the 0.5 mm thick TC4 titanium alloy perforated plate used in the aviation field,ϕ 2 mm drilling holes are uniformly distributed on its surface,with a hole spacing of 10 mm.The maximum initial height of burrs around the holes reaches nearly 160 μm,and it is required that the average height of burrs should be reduced to below 10 μm after processing.The purpose of this study is to enhance the quality and efficiency of magnetic abrasive finishing on eliminating double sided burrs on TC4 plates with group holes.Methods:Magnetic field distribution law of the permanent magnet array poles are studied through simulation analysis.The pole layout that meets the requirements of double sided magnetic particle grinding of the TC4 group hole plate is selected.To enhance the magnetic induction intensity of the poles,the Halbach array arrangement is employed to design the permanent magnetic field,which contains a weak magnetic field on one side and a strong magnetic field on the other.The strong magnetic field side can significantly increase the magnetic induction intensity and offer a favorable air gap magnetic density,thereby enhancing the magnetic induction intensity in the processing area and optimizing the magnetic field distribution.To further enhance the grinding efficiency and quality,this paper devised a permanent magnetic field scheme featuring an involute Halbach array arrangement based on the involute principle,aiming to improve the magnetic induction intensity and magnetic field distribution.The involute arrangement of magnetic poles exhibits a tendency of converging towards the center,which can effectively minimize the edge effect of magnetic grinding particles.Simulation is employed to analyze the quantity of magnetic pole blocks.It is discovered that a smaller quantity of blocks would cause an impact on the magnetic induction intensity of the magnetic poles.Nevertheless,utilizing 8 magnetic pole blocks can not only enhance the magnetic induction intensity but also decrease the assembly difficulty and production cost.In order to optimize the magnetic pole layout scheme,simulation on the magnetic induction intensity in the region of workpiece and magnetic poles on both side is conducted.What's more,the influence of magnetic pole speed difference on the change of magnetic induction intensity is analyzed.Meanwhile,a test is conducted to eliminate the burrs on both sides of the TC4 group hole plate through magnetic abrasive finishing.The magnetic poles are installed and secured using the designed fixture and connected to the main shaft of the servo motor via a coupling.By regulating the rotational speeds of the motors on both sides,a speed difference can be created,and the test objective was attained.The impacts of speed difference between the magnetic poles on both sides and average particle size of the magnetic abrasive on the removal of burrs around the holes are examined.Results:Based on the simulation analysis,it is found that the higher magnetic induction intensity is mainly distributed at the front and rear edges of the fan-shaped magnetic poles in the arrangement of the fan-shaped Halbeck array.In the involute Halbach array arrangement,the regions with higher magnetic induction intensity of the permanent magnetic field diffuse outward along the involute.Compared with the magnetic induction intensity in the sector arrangement,the difference is not significant,but the magnetic field gradient is slightly higher.The magnetic induction intensity of asynchronous rotating magnetic poles is higher than that of synchronous rotating magnetic poles,and the change in the magnetic field gradient is more pronounced,which facilitates the rolling and renewal of magnetic grinding particles.The average height of burrs on the edge of the outlet hole decreased from the initial 158.2 μm to 9.2 μm,which represented a reduction rate of 94.2%.The average height of burrs on the edge of the inlet hole decreased from the initial 78.2 μm to 6.2 μm,with a reduction rate of 92.1%.At the initial stage of magnetic abrasive finishing,the height of burrs around the hole decreased rapidly and subsequently decelerated.This phenomenon primarily occurs for the reason that as the processing time elapses,the volume of the burrs gradually diminishes,and the force exerted by the magnetic abrasive particles on the burrs also reduces.Conclusions:The test results indicate that the magnetic abrasive finishing method demonstrates a superior effect on removing burrs from the edge of the holes in the TC4 drilling group hole plate of titanium alloy.In the magnetic abrasive processing with double sided magnetic pole,when the rotational speed of magnetic pole I is 500 r/min and that of magnetic pole II is 600 r/min,the magnetic induction intensity and magnetic field gradient are more favorable.This is conducive to the rolling and renewal of magnetic abrasive particles,thereby enhancing the quality and efficiency of burr removal around the holes.Under the conditions of magnetic pole speed difference of 100 r/min(with magnetic pole speeds of 500 and 600 r/min respectively),an average particle size of 250 μm for magnetic grinding particles,a filling amount is 30 g,a processing gap of 2 mm,and a grinding liquid volume of 6 mL,the burr height of the TC4 group hole plate is less than 10.0 μm after 30 min of processing,which meets the technical requirement.关键词
磁粒研磨/毛刺/海尔贝克阵列/TC4群孔板/双面研磨Key words
magnetic abrasive grinding/burrs/Helbeck array/TC4 perforated plates/double-sided grinding分类
矿业与冶金
