【单选题】以下关于覆盖件拉延工艺设计原则中,错误的是( )。 A 尽量二次拉延成形 B 拉延件的成形深度应尽可能平缓均匀使各处的变形程度趋于一致 C 成形表面较为平坦的覆盖件时其主要变形方式应为胀形变形,适当地设置拉延槛和设计合适的压料面以调整各个部位的材料变形流动状况达到良好的效果 D 拉延材料流动不好时,可通过加大过渡区域和过渡圆角、预加工艺切口等办法改善材料的流动和补充条件
【简答题】Mary is well and still enjoying her school teaching (at least, I think so); the children are growing up at a terrifying rate; I am still working for Sanderson’s and liking it well enough — though occa...