椭圆内腔表面磨粒流均匀化光整加工研究

Research on Uniformity Precise Finishing Process of Abrasive Grain Flow for Ellipse Inner Cavity Surface

针对磨粒流加工中椭圆孔腔表面加工质量因表面曲率半径变化而不一致的问题,提出通过置入相似模芯实现磨粒流均匀化光整加工的新方法。运用非牛顿流体的幂律方程,建立了磨粒流加工的微元体动力模型,分析磨粒流加工中表面剪切应力分布不均的影响因素,而后通过COMSOL软件进行了数值计算与模拟仿真论证;最后,开展实验研究,对椭圆孔腔壁面压力及表面粗糙度等进行相关数据测量。研究结果显示:置入相似模芯后,椭圆流道的长、短轴方向剪切应力的理论值误差由置入模芯前的9.87%降为0.39%,长、短轴方向剪切应力分布趋于一致;椭圆流道的轴向、径向平均压力差仅为0.03 MPa、0.11 MPa,且表面粗糙度(Ra)差值由置入芯轴前的0.212μm下降为0.005μm,加工压力与表面粗糙度的变化趋势均趋于一致。置入相似模芯的方法改善了磨粒流加工中剪切应力分布不均的状况,为椭圆孔的高质量精密加工提供了重要参考依据。

A new method is proposed to realize abrasive flow uniformity precise finishing processing by inserting a similar mandrel,aiming at the inconsistent surface quality problem caused by the changes of non-circular cavity curvature radius in abrasive flow machining process. The infinitesimal body dynamic model for abrasive flow machining is established by using the power-law equations of non-Newtonian fluids to analyse the influencing factors of the uneven distribution of surface shear stress in abrasive flow machining process;and relevant demonstration is carried out by numerical calculation and simulation via COMSOL software as well.A mold core similar to ellipse cavity is utilized to improve the uneven distribution of shear stress on the surface of non-circular cavity.Experimental studies are carried out to test relevant data such as the wall pressure and surface roughness of the elliptical cavity. The experimental results show that, the simulated value error of the shear stress in both major and minor axis directions of the elliptical runner decreased from 9.87% to 0.39%, which indicated the shear stress distribution tended to be consistent;moreover, the processing pressure and surface roughness also tended to be consistent, the average pressure differences of the axial and radial directions of the elliptical flow channel were respectively only 0.03 and 0.11 MPa;the difference value of surface roughness decreased from 0.212 μm(before inserting the mandrel) to 0.005 μm;The uneven distribution of shear stress in abrasive flow processing process is solved and improved by the method of homogenizing flow channel, which will provide an important reference for the high-quality precision processing of non-circular cavities.