粉末润滑条件下铝合金拉延过程爬行现象研究

Research on creeping phenomenon in drawing process of aluminum alloy under powder lubrication condition

文章以石墨粉末作为固体润滑剂,对汽车用铝合金进行了一系列塑性拉延摩擦试验。试验中通过改变接触压力、粉末层厚度、滑动速度等参数,并结合试验后对边界层表面的微观形态分析,进行了不同工况下爬行现象对塑性成形过程粉末润滑影响机理的研究。结果表明:润滑膜表面的纵向划痕主要由爬行现象造成,不同工况对爬行现象的影响程度和效果不同,对润滑膜的影响主要体现在强度和频率2个方面;爬行现象随着载荷的增加出现的频率增大,且对润滑膜的破坏加剧,在低速状态下更容易发生爬行现象;适当增加粉末层厚度可以有效提高塑性成形摩擦界面的润滑质量,削弱爬行现象的影响。

Graphite powder was used to lubricate the sliding contact interface during the drawing experiments on automobile aluminum alloy. The friction tests were performed with different contact pressures, thickness of powder layer and sliding speeds.Based on a variety of microscopic analysis techniques,the influence of creeping phenomenon on the mechanism of powder lubrication in metal plastic forming was studied. The results indicate that longitudinal scratches on the surface of boundary layer are mainly caused by creeping phenomenon which is varied with different working conditions.The intensity and frequency can be used in characterizing the influence of creeping phenomenon on the lubricant film.The creeping phenomenon is intensified with higher contact pressure and is weakened with increasing speed.In low speed or high load condition,the creeping phenomenon is more evident.Increasing the thickness of powder layer appropriately can reduce the creeping phenomenon and the damage of the lubricant film in plastic forming.