Originally "lug" is thought to have come from Old Norse and is reflected in Swedish where lugga refers to pulling a person by the hair.
一般认为lug最早源自古斯堪的那维亚语，瑞典语里的lugga指的就是拉某人的头发。
During the process of pulling and stretching, the quality of pulling and strething parts mainly show: wrinkle, plosion thin, rebound, lug etc.
在薄板拉深过程中，拉深件的质量问题主要表现为起皱、破裂、变薄、回弹、凸耳等。
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