Drawn Over Mandrel的缩写，意思是通过心轴拉制。

下面是这种技术的中英文资料：

To produce specialty tubing, this procedure uses a drawbench to pull tubing through a die and over a mandrel, allowing excellent control of the inside diameter and wall thickness./ I. s" f9 K/ j

为了制造出更精密的管子,本工艺通过拔管机使管子经过钢型和心轴的拉制，这样管子的内径和壁厚精密度就能控制的很好。