| 摘要 |
<p>A tube with a thick walled portion at one end is cold-formed by necking one end of a tube workpiece, inserting a mandrel which engages within the tapering neck of the necked portion, drawing the necked workpiece through a drawing die by applying pressure on the mandrel, and withdrawing the mandrel from the workpiece. A thick-walled portion may be formed at the opposite end by interrupting the drawing operation, inserting a second mandrel of smaller diameter with a shoulder engaging in the tapering neck of the workpiece, continuing the drawing to draw the remainder of the workpiece down onto the second mandrel, and withdrawing the second mandrel.</p> |
