基于CFD的磁射流抛光去除机理分析

应用计算流体动力学(CFD)方法分析了一种新型精密抛光技术——磁射流抛光的材料去除机理。磁射流抛光中,含有磨料的磁流变液射流被喷嘴出口附近的局部外加纵向磁场磁化,产生准直的硬化射流束来进行相对远距离的精密抛光。介绍了磁射流抛光的原理和实验装置,分析了磁流变液聚束射流的形成,通过一系列定点抛光实验研究了磁射流抛光工艺的材料去除分布特征,利用计算流体动力学的方法分析了垂直冲击和倾斜冲击情况下,磁流变液射流与工件表面相互作用时径向流场功率密度的分布特征。实验结果和仿真计算结果表明:磁流变液射流在工件表面径向扩展流动产生的径向剪切作用导致了材料去除;CFD方法能模拟抛光区去除率的三维分布,因此可以准确地预测抛光区形状。

Analysis of Material Removal Mechanism in Magnetorheological Jet Polishing by CFD

Magnetorheological(MR) jet polishing(MJP),a new type of precision polishing technology in the material removal mechanism,was studied by the method of computational fluid dynamics(CFD).In MJP,the MR jet containing abrasives was magnetized by a local longitudinal magnetic field near the exit of the nozzle so that it could maintain the coherent and stable structure for a long distance.Firstly the mechanism and experiment set-up of MJP were introduced.Secondly the formation of collimated MR jet in a uniform axial magnetic field was analyzed.And then a series of static experiments were conducted to show the characteristics of the distribution of the material removal during the process of MJP.Finally the characteristics of the power density under conditions of both normal and oblique impingements were simulated by CFD method.Simulation and experiment results demonstrate that the material is removed by shearing actions caused by the radial spread flow of the MR jet over the workpiece surface.The method of CFD can accurately predict the 3-D removal rate distribution(polishing spot),thereby facilitating the accurate prediction of spot shapes on surface geometries.