油缸管内表面不规则缺陷产生原因分析方法

Cause analysis method of inner surface irregular defects of oil cylinder

在钢管冷拔及后续的精整过程中,钢管内表面时常出现离散分布的凹坑、豁口、裂纹等缺陷,使材料报废,并造成一定的经济损失。对发现的各类油缸管内表面缺陷进行研究,采用光学显微镜与扫描电镜对缺陷的产生原因进行了分析与讨论,从原料管的制造工艺方面查找可能产生上述不规则缺陷的工艺。结果表明:凹坑缺陷属于异物压入型缺陷,由与钢管内壁接触的硬物脱落造成;豁口缺陷由原料管的小内折引起;裂纹缺陷与芯棒、顶头表面损伤有关。

In the process of cold drawing and subsequent finishing of steel pipe,the inner surface of steel pipe often appeared discrete distribution of pits,openings,cracks and other defects,which made the material scrapped and caused certain economic losses.The inner surface defects of various types of oil cylinder tubes were studied.The causes of the defects were analyzed and discussed by optical microscope and scanning electron microscope.The process that could cause the above irregular defects were found from the manufacturing process of the raw material tubes.The results show that the pit defect belonged to the foreign body indentation defect,which was caused by the falling off of the hard object in contact with the inner wall of the steel pipe.The notch defect was caused by the small infolding of the raw material pipe,the crack defects were related to the surface damage of the mandrel and the plug.