| 摘要 |
<p>A metal billet used for hot expansion forming is of square shape in section on its front side as viewed in the press direction, and its diagonal length is not more than the inner diameter of a container. Further, the rear side as viewed in the press direction is circular in section and its diameter is substantially equal to the inner diameter of the container. This metal billet is heated to a press work temperature and then charged into a press forming container. And the metal billet is subjected to hot expansion forming while being centrally drilled by a drilling punch operated by a press pressure device, thereby forming a bottomed vessel for casks.</p> |
