冷却润滑对纯铁车削刀具磨损的影响机理

Effect of Cooling / Lubrication Modes on Tool Wear Mechanisms in Turning Pure Iron Material

合适的冷却润滑方式是改善切削摩擦,降低切削温度和切削力,提高刀具寿命的关键技术.采用干切、水冷、微量润滑(Minimum quantity lubrication,MQL)以及菜籽油润滑等四种方式进行了不同工艺参数下纯铁材料的车削试验,研究了冷却润滑方式对纯铁车削刀具磨损的影响机理.结果表明:纯铁车削时刀具磨损形态以主、副切削刃处的沟槽磨损和后刀面磨损为主,前刀面上黏结有工件材料并形成积屑瘤;MQL条件下的刀具寿命最长,而水冷时最小;扩散磨损、氧化磨损和黏结磨损是纯铁车削刀具的主要磨损机理;四种冷却润滑方式下切削力、前刀面与切屑间平均摩擦系数和表面显微硬度的显著差异是造成刀具寿命明显不同的根本原因.

The suitable cooling/lubrication modes are the key technology to reduce the friction coefficient between the interface of chip - tool, to improve tool lifetime to reduce cutting force and temperature. The experiments of turning pure iron material were conducted with different cutting speeds under four cooling/lubrication modes, i.e. dry cutting, water - based coolant, minimum quantity lubrication （MQL） and brushing rapeseed oil, to investigate the effects of cooling/lubrication modes on tool wear mechanisms. The results show that the main tool wear mode was flank wear and there were two severe notches wear on major cutting edge and minor cutting edge, respectively. The workpieee material was adhered on rake face to form built - up edge. It had the longest tool lifetime under MQL and the least under water - based coolant. Diffusion wear, adhering wear and oxidation wear were the main wear mechanisms for the cutting tools in turning pure iron. The distinct difference of cutting force, the average friction coefficient between the interface of chip and rake face and the microhardness of machined workpiece surface under four cooling/lubrication modes were the primary reasons, which resulted in different tool lifetime in turning pure iron material.