| 摘要 |
<p>Method and apparatus for preforming the long edges of steel plate (11) prior to manufacture into pipe (47) by the U-O process or the like by utilizing plate of a width exceeding that required for pipe of a given diameter by an amount at each edge having an excess (X) at least equal to the width of the pipe. The plate is roll formed using the excess width thereof as a lever arm to obtain a bend (A1) at the bitter edges (20) of the pipe and thereafter the plate is sheared along a line (S-S") adjacent the bitter edges (20), followed by bevelling and polishing the bitter edges (20), and further roll forming the edge areas (A2 and A3) to complete the preform thereof. </p> |
