磨削加工中的尺寸效应机理研究

Research on the Size Effect Involved in Grinding

从比切削能和比摩擦能的大小变化与磨削参数的关系出发,研究了磨削加工中的尺寸效应问题,结果认为:比切削能的尺寸效应是金属剪切流动应力的尺寸效应和磨粒顶端钝圆影响的综合作用结果;当磨削深度或工件进给速度减小时,平均未变形切屑厚度减小,金属材料的剪应变效应和剪应变率效应增强,而热软化效应减弱,从而金属材料的剪切流动应力增大;当未变形切屑厚度减小时,磨粒顶端钝圆的影响增大;比摩擦能的尺寸效应是由于工件和砂轮的实际接触面积与磨削深度之间存在非线性关系及工件和砂轮间的摩擦因数的速度效应造成的;当工件进给速度减小时,工件与砂轮磨损平面间的摩擦因数增大。

The specific grinding energy is divided into the specific cutting energy and the specific friction energy. The size effect of the specific cutting energy is a combined behavior caused by the size effect of the shear flow stress of metal material and the effect of the top part of the abrasive grain. If the depth of cut or the workpiece feed speed is reduced, the average undeformed chip thickness will decrease, the effect of the shear strain and the effect of the shear strain rate will strengthen and the effect of temperature will weaken, so the shear flow stress will increase; If the undeformed chip thickness is reduced, the effect of the top part of the abrasive grain will increase. The size effect of the specific friction energy is due to the nonlinear relationship between the depth of cut and the actual contact area between the workpiece and the grinding wheel, and the speed effect of the friction coefficient between the workpiece and the wear flats of the grinding wheel. If the workpiece feed speed is reduced, the friction coefficient will increase.