Inventors:
Edward J. Patula - Monroeville PA
Assignee:
United States Steel Corporation - Pittsburgh PA
International Classification:
B21B 1710
Abstract:
A pierced billet is fed to a plug rolling mill, wherein the first rolling pass is effected in conventional manner, i. e. the shell is rammed over a forming plug mounted on the front end of the mandrel and then drawn over the plug by the work-rolls. Rather than removing the shell from the mandrel and returning it to the entry side of the mill, the second pass on the shell is effected by reversing the rotation of the work-rolls and pushing the shell back through the reverse rotating work-rolls over the same plug whereby, in effect, the original exit side of the mill now becomes the entry side. This double passing over the same plug is achieved through the use of a newly designed plug, tapered in both directions, wherein the plug is connected to the mandrel so as to transmit the tension force on the plug to the mandrel.