In order to avoid mesh constraint when simulating chip separation by finite element method, cutting process of single CBN abrasive grain is simulated by using coupling method of finite element method and smoothed particle hydrodynamics. Chip mechanism of single CBN abrasive grain and its geometric features' effects on cutting deformation of workpiece material are analyzed according to the stress variation of CBN abrasive grain and workpiece material, and motion situation of smoothed particles in cutting layer. CBN abrasive grains' scratching experiment is carried out by using abrasive block of vitrified bonded CBN wheel. It is concluded that workpiece material occurs plastic deformation, flows to the side and front owing to the extrusion of abrasive grain, and finally forms chip in front of abrasive grain. The shear angle increases with the increase of grain rake angle, it results in the decrease of ploughing and increase of cutting. The wear of the edges of abrasive grain is faster due to its lower strergth and larger contact stress. Wear abrasion and micro-breaking result in the dullness of abrasive grain.%为了解决有限元法模拟切屑分离时的网格束缚问题,采用有限元法和光滑粒子流体动力学(SPH)法的耦合方法进行了单颗立方氮化硼(CBN)磨粒切削过程的微观力学仿真.通过CBN磨粒与工件材料的应力变化与分布情况以及切削层SPH粒子的运动情况,从微观角度分析了单颗CBN磨粒的切削成屑机理,并分析了CBN磨粒的几何特征对工件材料切削变形的影响；采用陶瓷CBN砂轮贴片样块进行了磨粒划擦实验,结果表明:磨粒的推挤使工件材料发生塑性变形,沿磨粒的前方及两侧隆起,并最终于磨粒的前方流出而形成磨屑；磨刃前角增大,剪切角随之增大,导致磨粒的耕犁作用减弱而切削作用增强.磨粒刃边强度低、接触应力大,磨损速率较快,易于发生磨耗及微破碎磨损而使磨粒钝化.
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