磁场分布对多磨头磁流变抛光材料去除的影响

为研究磁场分布对材料去除的影响,设计轴向充磁异向排布、轴向充磁同向排布、径向充磁异向排布、径向充磁同向排布4种磁铁充磁和排布方式,利用有限元软件Maxwell仿真不同磁场的磁力线分布及抛光轮表面的磁感应强度分布,并采用数字特斯拉计测量实际磁感应强度。对单晶硅基片进行定点抛光试验,检测抛光斑沿抛光轮轴向的去除轮廓及峰值点的表面形貌。仿真和实际磁感应强度检测结果表明,不同磁场分布方式对抛光区的磁场分布有很大影响,磁铁轴向充磁同向排布与径向充磁异向排布时,具有较高的磁场强度和较好的多磨头效果。定点抛光试验表明,采用轴向充磁同向排布与径向充磁异向排布这两种方式时,能实现多点加工,其中轴向充磁同向排布时加工效率较高;但采用径向充磁同向排布时,由于抛光区磁感应强度较低,磁流变微磨头无法对工件进行有效地抛光。峰值点表面形貌检测结果表明,采用不同磁场分布方式时,对工件表面均是以塑性去除方式去除。研究表明,通过优化磁铁充磁和排布方式,可实现多磨头磁流变抛光的加工原理。

Effect of Magnetic Field Distribution on Material Removal in Magnetorheological Finishing with Multiple Polishing Heads

In order to study the effect of magnetic field distribution on material removal,four kinds of magnet magnetization and arrangement methods were designed,including axial magnetization reverse arrangement,axial magnetization co-arrangement,radial magnetization reverse arrangement and radial magnetization co-arrangement.The finite element software Maxwell was used to simulate the magnetic field line distribution of different magnetic fields and the magnetic induction intensity distribution on the surface of the polishing wheel,and the actual magnetic induction intensity was measured by a digital Tesla meter.Spot polishing experiments were performed on the monocrystalline silicon substrate to measure the removal profile of the polishing spot along the axial direction of the polishing wheel and the surface topography of the peak point.The results show that different distribution modes of magnetic field have great influence on the magnetic field distribution in polishing area.By using the axial magnetization co-arrangement or radial magnetization reverse arrangement,the magnetic field intensity is higher and the effect of multi-micro polishing heads is better.The two distributions can realize multi-point processing,and the first one is more efficient.However,when radial magnetization co-arrangement,workpiece cannot be polished availably due to the low magnetic field intensity.The results of peak point surface topography detection show that the workpiece surface is removed by plastic removal under different magnetic field distribution modes.By optimizing the distribution of magnetic field,the machining principle of MRF with multiple polishing heads can be realized.