大应变切削制备纳米晶/超细晶切屑形成机理的有限元研究

本文建立了大负前角和钝圆半径联合作用的大应变切削模型，采用有限元Deform分析软件模拟较低的切削速度下，刀具前角和钝圆半径对切屑形态、应力、应变、应变速率、切削温度和切削力的影响。实验结果显示，随着刀具前角的减小和钝圆半径的增加，切削变形区中等效应变、应力、应变速率、切削温度和切削力均有一定程度的增加，且刀具前角相比钝圆半径具有更加重要的影响，而负前角切削时，钝圆半径的作用明显减弱。大负前角低速切削条件下，切屑在相对低的温度、较高的应变速率和应力下发生大剪切应变，形成具有纳米晶/超细晶结构和高硬度的切屑材料。

Research of Finite Element Method on Formation Mechanics of Nanocrystalline and Ultra-fine Grained Chip in Large Strain Machining

Large strain machining model combined large negeative rake angle with round cutting edge radius is established. The effect of rake angle and round cutting edge radius on shape of chip, effective strain, stress, strain rate, temeprsture and cutting force in defromation area at some low cutting velocity is analysed with finite element model. The experimental results indicated that the effective strain, stress, strain rate, temperature and cutting force in deformation area is increased with the decreasing rake angle and increasing round cutting edge radius. The rake angle has more important effect on the formation of ultra-fine grain chips than round cutting edge radius. The effect of round cutting edge radius is weakened with large negative rake angle. Chip is imposed large strain at low temeprature, high stress and strain rate which can produce chip materials with ultrafine grained and high hardness by machining with more negative tool rake angle at some lower cutting velocity