| 摘要 |
Method and apparatus are described for preforming the long edges of flat steel plate prior to the plate being formed, pressed and welded into large diameter pipe. In accordance with the method the edges are roll-formed while the plate is of excess width to provide material to serve as a lever arm during rolling, so that the metal can be suitably bent at locations spaced from the outer edges, and after forming the edges of the plate are sheared adjacent these locations to provide the preformed abutting edges suitable for the pipe. |
