表面粗糙度对冷锻摩擦因子的影响

Influence of surface roughness on friction factor in cold forging

借助圆环镦粗实验,以Cr12MoV为模具材料,20钢为工件材料,分别在磷皂化润滑与无润滑条件下,探讨模具与工件的表面粗糙度对冷锻摩擦的影响规律,为冷锻成形中模具和工件表面粗糙度的选择提供参考。实验结果表明,冷锻摩擦因子随模具表面粗糙度的增大而增大。工件表面粗糙度对摩擦的影响在不同润滑条件下具有不同的表现,磷皂化润滑条件下,工件表面粗糙度越大,摩擦因子越小;无润滑条件下,摩擦因子随着工件表面粗糙度的增大先减小后增大。同时发现,随着变形程度的增加,试样的表面粗糙度逐渐趋近于模具的表面粗糙度。

To provide the selection guide for surface roughness design of die and workpiece in cold forging,the influence of initial surface roughness of die and workpiece on friction was investigated by ring compression tests under two different lubrication conditions.During the tests,Cr12 MoV and 20 steel were chosen as the material of die and workpiece,respectively.From the tests results,the friction factor increases with larger surface roughness of the die.However,the influence of initial surface roughness of workpiece on friction factor is different under different lubrication conditions.For zinc phosphate coating plus soaping process,the friction factor decreases with the increasing of surface roughness.Under the dry condition,the friction factor decreases firstly and then increases with the surface roughness.Meanwhile,it is found that the surface roughness of workpiece after compression is gradually close to that of dies.