多磁极旋转磁场的钛合金表面磁性剪切增稠光整加工特性

Finishing Characteristics of Magnetorheological Shear Thickening Finishing for Titanium Alloy Using Multi-pole Rotating Magnetic Field

目的探究多磁极旋转磁场下钛合金(Ti-6Al-4V)表面磁性剪切增稠光整加工特性。方法设计不同磁极排布的多磁极旋转磁场,通过仿真分析和实验测量,分析N-S-N、N-S-N-S和N-S等3种磁极排布下的磁场特性。基于研制的磁性剪切增稠光整介质,构建光整加工实验装置,探究磁极排布、主轴转速、旋转平台转速和加工间隙对工件表面粗糙度的影响规律,并通过扫描电子显微镜对加工前后的工件表面微观形貌进行对比分析。结果在N-S-N磁极排布下,加工区域的磁场强度较大,磁力线闭合回路较多,能够形成刚性较大和数量多的磁力刷。在N-S-N磁极排布、主轴转速600 r/min、旋转平台速度160 r/min、加工间隙0.7 mm的实验条件下,光整加工效果最优,工件表面粗糙度下降趋势明显,表面粗糙度由初始的1.2μm下降至67 nm,表面光洁度提高94%。通过扫描电子显微镜观测,工件表面的划痕显著去除,仅残留磨粒切削造成的微细划痕。结论调控多磁极旋转磁场的磁极排布可以有效控制光整加工效率,配合磁性剪切增稠光整介质和加工工艺参数优化,钛合金表面能够实现纳米级光整,表面质量显著改善。

This work aims to explore the finishing characteristics of magnetorheological shear thickening finishing for titanium alloy(Ti-6 Al-4 V) using multi-pole rotating magnetic field.Multi-pole rotating magnetic fields with different magnetic pole arrangements were designed.The magnetic field characteristics under three magnetic pole arrangements of N-S-N,N-S-N-S and N-S were analyzed based on simulation approaches and experimental measurements.Experimental setup for the surface finishing of titanium alloy(Ti-6 Al-4 V) was established to investigate the influence of the magnetic pole arrangement,spindle speed,rotary table speed and working gap on the surface roughness of the workpiece.Comparative analysis of the surface micro-topography before and after finishing was conducted based on scanning electron microscope.A large magnetic field intensity and a large number of closed loops of magnetic field lines were obtained in the finishing region under the N-S-N magnetic pole arrangement,which led to form more rigid and a large number of magnetic brushes under the employed magnetic field action.It was observed from the experimental results that the N-S-N magnetic pole arrangement exhibited a good finishing efficiency.The developed finishing media was effective for surface finishing of titanium alloy(Ti-6 Al-4 V).The surface roughness of 67 nm was achieved from the initial value of 1.2 μm,which improved by over 94%,under the experimental conditions of the N-S-N magnetic pole arrangement,spindle speed of 600 r/min,rotary table speed of 160 r/min,and working gap of 0.7 mm.Surface observations showed that a smooth surface without obvious scratches was obtained.The surface quality was significantly improved.The cutting marks were left on the finished surface because of the scratch of abrasive particles.Regulating the magnetic pole arrangement of multi-pole rotating magnetic field can effectively control the photofinishing processing efficiency,and with the optimization of magnetic shear-thickening photofinishing media and processing process parameters,the surface of titanium alloy can achieve nano-level photofinishing and significant improvement of surface quality.