Abstract:

In this paper, first, a large-strain model describing the machining with large negeative rake angle and blunt round radius is established. Then, the effects of the tool rake angle and the blunt round radius on the chip shape, the effective strain and stress, the strain rate, the cutting temperature and the main cutting force during the cutting at a relatively low cutting speed are analyzed with the finite element software. The results indicate that （1） with the decrease in the tool rake angle and with the increase in the blunt round radius, the effective strain and stress, the strain rate, the cutting temperature and the main cutting force all increase, especially with the tool rake angle; （2） the effect of the blunt round radius weakens at a negative tool rake angle; and （3） large strains are imposed on the chip at a low temperature and a high stress and strain rate, which helps to produce nano-crystalline/ ultra-fine grained chip materials with high hardness by the cutting with large negative tool rake angle and low cutting speed.

Key words: large-strain machining, nano-crystalline/ultra-fine grained chip, finite element simulation, micro-structure