超弹性复合磨料气射流抛光方法

Air Jet Polishing Method of Superelastic Composite Abrasives

目的利用复合磨料对TC4钛合金进行气射流抛光,研究磨料入射角度、抛光气压、抛光时间等工艺参数对其表面粗糙度及表面形貌的影响。方法以橡胶作为超弹性基体,采用冰晶石粉与1μm的金刚石微粒对橡胶颗粒表面进行分批次涂覆,最终得到形状规则、表面磨粒附着均匀且粒径约为2 mm的复合磨料。利用ABAQUS有限元仿真软件对抛光过程进行模拟,并采用单因素实验法对抛光过程及结果进行研究。结果当磨料入射角度为20°、抛光气压为0.5 MPa、抛光时间为2 min时,TC4钛合金表面能降至最低(Sa为38.7 nm)且表面形貌较为均匀平坦(S_(ku)为3.9)。当复合磨料循环抛光6~8次后,其表面金刚石磨粒层会出现破损与脱落,为不影响最终抛光效果,需通过重新涂覆金刚石的方式对其表面进行修补。结论复合磨料在对TC4钛合金抛光的过程中能有效降低其表面粗糙度并降低磨粒对工件表面的损伤。磨料入射角度主要影响复合磨料撞击工件表面时的形变量和切削力,抛光气压则主要影响发生形变时在工件表面的滑移距离。

TC4 titanium alloy is widely used in aerospace parts,medical equipment and automobile industry because of its good mechanical properties,large specific strength and low thermal conductivity.The operational demands within these sectors necessitate superior surface quality and minimal surface roughness,thereby imposing heightened prerequisites on the surface polishing procedures.Compared with the traditional air jet polishing process of hard abrasives,the use of composite abrasive polishing can make the workpiece get a more uniform surface and a lower surface roughness,and reduce the subsurface damage to the material surface while removing the material on the workpiece surface.In order to explore the effect of composite abrasives on the surface roughness and surface morphology of TC4 titanium alloy in the air jet polishing process,the work aims to use rubber as a superelastic matrix,and coat the surface of rubber particles with cryolite powder and 1μm diamond particles in batches,so as to obtain a hyperelastic composite abrasive with a particle size of about 2 mm,a regular shape and a uniform surface abrasive adhesion.ABAQUS finite element simulation software was used to simulate the deformation and motion trajectory of the composite abrasive polishing process to explore the effect of abrasive incident angle and polishing pressure on the surface morphology and surface roughness of the material.The Mooney-Rivlin constitutive model was used to characterize the rubber matrix,and the corresponding incident angle and polishing pressure were simulated after setting of the corresponding incident angle and polishing pressure.Analysis of the results revealed that the incident angle of the abrasive affected the deformation and cutting force of the composite abrasive during polishing,while polishing pressure affected the slip distance of the composite abrasive on the material surface.The effects of incident angle,polishing pressure and polishing time on the surface of the composite abrasive were studied by single factor comparison method.The surface of the material was observed and characterized by super depth of field three-dimensional microscope,white light interferometer(Super View W1,Chotest,China),scanning electron microscope(SEM)(ΣIGMA,ZEISS,Germany).Finally,it is concluded that TC4 titanium alloy can get lower surface roughness and more uniform surface morphology when the abrasive incident angle is 20°,the polishing pressure is 0.5 MPa and the polishing time is 2 min.Furthermore,the material removal rate under different abrasive incident angles and polishing pressure is calculated by measuring the mass change before and after polishing,aiming to characterize removal efficiency and machining accuracy under varying process parameters.The surface quality is further analyzed by surface skewness and kurtosis.However,after 6 to 8 cycles,the diamond abrasive layer will be damaged and peeled off due to the continuous collision between the surface diamond abrasive layer and the titanium alloy surface.In order not to affect the final polishing effect,it is necessary to repair the composite abrasive and coat the surface with diamond abrasive particles to obtain a uniform diamond abrasive layer.