摆线泵内转子磨料流均匀化抛光及试验研究

为了降低内转子的表面粗糙度,提出了一种利用磨料流对内转子表面实现均匀化加工的抛光方法.采用与内转子壁面等宽度的方法设置模芯,通过建立均匀化流道,改善壁面的剪切应力分布,使内转子各曲面间的壁面所受剪切应力趋向一致.依据磨料流的流变特性,建立幂律方程,分析磨料流加工过程的剪切率及剪切应力分布状况,并利用COMSOL Multiphysics软件的CFD模块模拟磨料介质在均匀化流道下的表面加工流速、剪切率和剪切应力的分布.结果表明:在无模芯时利用磨料流加工,内转子各表面的剪切速率差值较大;置入模芯后内转子曲面各部分所受的剪切应力比无模芯时明显得到改善,经20次加工循环后,各表面间的粗糙度最大差值由无模芯时的0.847 μm降至0.277 μm,且有效地提高了加工效率及表面质量.

Abrasive flow uniform surface polishing method and experiment for cycloidal pump inner rotor

In order to reduce the surface roughness of the inner rotor of cycloidal pump, a polishing method was proposed to realize a uniform surface polishing by using abrasive flow machining(AFM)on the surface of inner rotor. A mold core was made and installed outside the inner rotor in such a way that the gap between the core and the rotor keeps being constant to establish a uniform flow field around the rotor and allow the rotor surface experiences nearly the same wall shear stress. A power law model was established to represent the rheological property of the abrasive and water mixture and used to analyze the distribution of shear rate and shear stress in AFM process; further the distributions of velocity, shear rate and shear stress of the abrasive media over the processed surface were simulated by means of COMSOL Multiphysics CFD module. The results showed that if there was no mold core installed the non-uniform shear stress leaded to uneven roughness over the processed rotor surface; however, after the mold core was available, the rotor surface experienced uniform shear stress. In this case, the maximum difference in surface roughness Ra was reduced to 0.277 μm from 0.847 μm after 20 processing cycles. The processing efficiency and surface finish quality have been improved substantially.