旋转超声加工中磨粒冲击作用的仿真分析

Simulation analysis on the impact effects of the abrasive in rotary ultrasonic machining process

摘要:

在对单个磨粒进行动力学分析的基础上,定义了评价超声冲击作用大小的量纲一的参数K．采用光滑质点流体动力学(SPH)有限元分析方法,研究了旋转超声加工过程中磨粒的超声冲击作用对材料内部裂纹形成及扩展的影响．仿真结果表明:随着K值的增大,斜向裂纹的倾角减小,扩展深度逐渐降低,磨粒的超声冲击作用是裂纹形成及扩展的主要原因；在切削过程中,随着切削深度的增加,切削力逐渐增大;但是当裂纹产生以后垂向冲击力急剧减小,而横向冲击力变化不大；加工中碎屑的崩碎使磨粒对工件材料具有局部微冲击作用,导致两个方向的切削力都在相对较大范围内波动．

Abstract:

Based on the theoretical analysis of kinematics principles of the abrasive, dimensionless parameter K was defined to describe the impact effects. Smooth Particle Hydrodynamics (SPH) Finite Element Method was used to study the mechanisms of crack formation and extension in the interior of the material under the impact of the abrasive. The simulation results showed that, with the increasing of K, the inclination and the depth of the inclined crack decreased. The interaction mechanisms between the abrasive and the workpiece showed that the impact of the abrasive was the main reason for the crack formation and extension. In the cutting process, the cutting force increased rapidly, and then, due to the formation of the cracks, the vertical impact forces reduced dramatically, but the horizontal impact force changed little. As the local micro-impact phenomenon between the material and the abrasive, the cutting forces in both directions fluctuated within a relatively large range.