纯铁切屑形成特征及影响因素研究

Investigation into Formation Characteristics and Influence Factors of Pure Iron Chip

采用正交切削试验,研究了纯铁材料在不同切削速度下切屑形成特征及变形机理,开展了刀具前角、切削用量、冷却润滑方式等切削工艺参数对纯铁切屑变形规律的影响试验.结果表明,纯铁切屑呈现显著的剪切滑移变形特征,切削工艺参数仅对切屑中晶粒的变形程度产生影响;低速切削时切屑在前刀面上具有"滑-停-滑"现象,晶粒破碎严重,而高速时停留现象减小甚至消失,晶粒呈拉伸状变形;随着切削速度和刀具前角的增加,切削力、切屑变形系数显著减小,切削力则随进给量的增加而增加,但切屑变形系数则呈减小趋势;相同切削用量时,水冷方式下切削力和切屑变形系数最小,而干切时最大.试验结果对纯铁材料选择合适的工艺参数以改善其加工性能具有重要的参考意义.

Based on the orthogonal cutting experiments, the formation characteristics and deformation mechanism of the pure iron chip at different cutting speeds were investigated, and the effects of such cutting process parameters as the rake angle, the cutting parameters and the cooling/lubrication conditions on the deformation rules of the pure iron chip were revealed by experiments. The results show that （1） the pure iron chip has a significant shear slip deformation characteristic, and the cutting process parameters only affect the deformation of the grains in the pure i- ron chip; （2） at lower cutting speeds, an obvious ＂sliding-stop-sliding＂ phenomenon occurs as the chip flows on the rake face, and the grains are seriously broken; （3） however, at higher cutting speeds, the stop phenomenon is reduced and even disappears, and the grains in the pure iron chip show a tensile deformation; （4） as the cutting speed and the rake angle increase, the cutting force and the chip deformation coefficient significantly decrease; （5） with the increase of the feed rate, the cutting force increases while the chip deformation coefficient decreases ; and （6） at the same cutting parameters, the cutting force and the chip deformation coefficient are at the minimum under the cutting fluid condition, but they are at the maximum under a dry cutting. The above-mentioned results are useful in selecting suitable cutting process parameters to improve the machinability of pure iron materials.