One way is to use a hollow billet and then use a fixed or floating mandrel.

一种方法是使用空心坯，然后使用固定或浮动芯棒。

youdao

The maximum height of wrinkling wave does not almost alter with the increase of the initial lead of the mandrel when the initial lead reached a fixed value.

当芯棒伸出量达到一定值后，随着芯棒伸出量的增大，起皱波纹高度极大值变化不明显。

youdao

The maximum height of wrinkling wave does not almost alter with the increase of the initial lead of the mandrel when the initial lead reached a fixed value.

当芯棒伸出量达到一定值后，随着芯棒伸出量的增大，起皱波纹高度极大值变化不明显。

youdao