流道结构对加压内冷却开槽砂轮磨削性能的影响

Effect of Flow Channel Structure on Performance of Pressurized Internal-cooling Slotted Grinding Wheels

针对镍基高温合金磨削时磨削区因砂轮气障效应引起的过热问题,提出采用加压式内冷却磨削方法,鉴于砂轮内流道结构影响磨削液的流动特性和砂轮的磨削性能,同时考虑流道加工工艺和砂轮旋转时离心力的影响,设计直线型和弧线型两种内流道结构。利用计算流体动力学方法分析了流道结构对磨削区流场的影响,表明弧线型流道结构下磨削区的流体速度和分布均匀性更高。制备了具有弧线型和直线型内流道的两种加压内冷却开槽砂轮,在相同的磨削参数下进行了镍基高温合金磨削对比试验,分析砂轮线速度和磨削液压力对磨削温度、表面粗糙度和表面形貌的影响规律。结果表明:相比直线型流道,弧线型流道的冷却润滑效果更好,随砂轮线速度和磨削液压力的增大其换热效率提升更显著,得到的磨削温度和工件表面粗糙度值分别降低了16.8%和17.6%,并获得了更规则的加工表面形貌。

Aiming at the overheating problem caused by the gas barrier effect of the grinding wheel in the grinding of nickel-base superalloys, a pressurized internal cooling grinding method is proposed. In view of the influence of the flow channel structure on the flow characteristics of the grinding fluid and the performance of the grinding wheel, and considering the processing technology of the flow channel and the centrifugal force caused by the rotation of the grinding wheel, two types of straight and curved internal channel structures are designed. The computational fluid dynamics method is used to analyze the influence of the channel structure on the flow field in the grinding zone. Results show that the fluid velocity and distribution uniformity of the grinding zone under the curved flow channel structure are higher. Two pressurized internal cooling slotted grinding wheels with curved and straight internal flow channels are prepared. The grinding comparison tests of nickel-base superalloy are carried out under the same grinding parameters, and the effects of grinding wheel speed and fluid pressure on the grinding temperature, surface roughness and morphology are analyzed. Results indicate that compared with the straight flow channel, better cooling and lubrication effects are obtained by the curved flow channel, and the heat exchange efficiency is more remarkable as the grinding speed and the fluid pressure increase. Grinding temperature and surface roughness of the workpiece are reduced by 16.8% and 17.6%, respectively, and a more regular surface morphology is obtained.