磁流变抛光加工中磁场发生装置的设计与实验

Design and Experiment of Magnetic Field Generator in Magnetorheological Polishing Process

目的研究磁流变抛光加工中磁场发生装置设计对抛光效果的影响。方法设计三种基于电磁铁的磁场发生装置,分别为圆形阵列、扇形和环形磁场,进行三维静磁场有限元仿真,对比分析不同磁场发生装置的磁场强度、方向云图及5 mm高处磁场强度曲线。为保证加工过程中磁场和磁流变液的稳定性,针对三种磁场结构设计不同的冷却方式。制造环形磁场发生装置,将其集成到自制磁流变抛光平台,使用表面经过阳极氧化的铝合金样件进行抛光实验。结果圆形阵列磁场极头间隙处形成高磁场区,随着高度的升高,磁场强度迅速下降。在离极头5 mm高处,磁场强度从300 mT下降到约145 mT,抛光区域磁场强度较小。扇形磁场5 mm高处,磁场强度呈抛物线分布,最大可达330 mT,磁场方向单一,有效抛光区域占比较小。环形磁场5 mm高处,磁场强度最大可达240 mT,工件运动整个过程都处于高磁场区域,抛光效率高。结论环形磁场发生装置磁场强度和磁场方向都满足抛光要求,有效抛光区域较大,抛光后表面质量明显改善,抛光效果较好。

In order to study the influence of the design of magnetic field generating device on the effect of magnetorheological polishing,three magnetic field generating devices based on electromagnet are designed,which are circular array magnetic field,fan-shaped magnetic field and annular magnetic field.Three-dimensional static magnetic field finite element simulation was carried out respectively,and the magnetic field intensity cloud maps,directional cloud maps and magnetic field intensity curves at 5 mm height of different magnetic field generating devices were compared and analyzed.In order to ensure the stability of magnetic field and magnetorheological fluid during processing,different cooling methods were designed for three magnetic field structures to compare and optimize.The annular magnetic field generator was manufactured and integrated into the self-made magnetorheological polishing platform.Anodized aluminum alloy samples were used for polishing experiments.It was founded that a high magnetic field area was formed at the gap of the pole head of the circular array magnet field.As the height increased,the magnetic field intensity decreased rapidly.At the height of 5 mm from the pole head,the magnetic field intensity decreased from 300 mT to about 145 mT,and the magnetic field intensity in the polished area was small.The magnetic field intensity at the height of 5 mm fan-shaped magnetic field was parabolic distribution,with the maximum up to 330 mT.The magnetic field direction was single,and the effective polishing area was relatively small.At the height of 5 mm annular magnetic field,the maximum magnetic field intensity can reach 240 mT.The workpiece was in the high magnetic field area during the whole movement process,and the polishing efficiency was high.The magnetic field intensity and direction of the annular magnetic field generator meet the polishing requirements,and the effective polishing area is large,the surface quality is significantly improved after polishing,and the polishing effect is better.