摘要
为探究铋系、铅系、硫系3种易切削钢切削性能的差异和铋对易切削钢切削性能影响及其作用机制,利用Kistler测力仪、表面粗糙度测量仪等对1215MS硫系易切削钢、1215Bi铋系易切削钢、12L14铅系易切削钢3种盘条开展了切削对比测试.结果表明:在转速w=1 200 r/min、切削深度ap=0.4 mm、进给量f=0.2 mm/r,且切削刀具和切削角度相同的的切削条件下,1215MS、1215Bi、12L14三种易切削钢盘条的切削合力分别为:130、123、116N;材料的表面粗糙度Ra分别为:5.3、4.9、4.6 μm,C型屑的占比分别为:28％、37％、42％,1215Bi易切削钢的切削性接近于12L14易切削钢,显著优于1215MS易切削钢;在铋系易切削钢中,Bi元素以Bi颗粒的形式存在,或者附着在MnS的表面,形成Bi-MnS复合夹杂物,在切削过程中,切削热使得Bi颗粒发生熔融,起到了润滑作用,断屑性增加,改善了切削性能.
Abstract
To investigate the differences in machinability of bismuth,lead and sulfur free-cutting steels,and to understand the effect of bismuth on machinability of free-cutting steels and its mechanism,a comparative cutting test was carried out on three types of wire rods of sulfur free-cutting steel 1215MS,bismuth free-cutting steel 1215Bi,and lead free-cutting steel 12L14 by using Kistler force sensors,surface roughness measurement instruments,and other tools.The results show that under cutting conditions of a rotational speed of w=1 200 r/min,a cutting depth of ap=0.4 mm,a feed rate of f=0.2 mm/r,and the same cutting tools and cutting angles,the cutting forces of the three free-cutting steel wire rods 1215MS,1215Bi,12L14 are 130 N,123 N,116 N,respectively.The surface roughness values Ra are 5.3 μm,4.9 μm,4.6 μm,and the proportion of C-type chips are 28％,37％,42％,respectively.The machinability of free-cutting steel 1215Bi is comparable to that of free-cutting steel 12L14,and was significantly better than that of free-cutting steel 1215MS.For bismuth-added free-cutting steel,Bi exists in the form of Bi particles or is attached to the surface of MnS,forming Bi-MnS composite inclusions.The cutting heat generated during cutting causes Bi particles to melt,playing a role in lubrication,improving chip breaking and the machinability.
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