roller frame housing是什么意思

用法例句

The piercing, drawing, bending and cutting-off progressive die for the auto bracket shell was introduced.

介绍了汽车零部件支架壳体冲孔、拉伸、弯曲压筋、切断级进模的排样设计、模具结构 ,还详细介绍了模具的制造要点。