| 摘要 |
PURPOSE:To enable the production of the necessary plate rolled steel pipe with thickened end part by forming the differential thickness face side of a differential thickness steel plate in a tubular shape by a press with setting to a stepped female die and by finishing it in a steel pipe with welding it afterwards. CONSTITUTION:The steel pipe with a fixed inner diameter face expanding outer diameter face at the both end parts of the pipe shaft and having a smooth boundary part 3 between a thick part 1 and thin part 2 is produced by the plate rolling of a differential thickness steel plate P. The thicker part 1' thinner part 2' and boundary part 3' corresponding to the necessary steel pipe are formed by a rolling on the steel plate P, which is formed in a tubular shape by a die 5 and male die 7 with providing the projecting part adjoining the thinner part 2' on the female die 5 performing their press bending formation. The steel plate P formed in a tubular shape is made the necessary steel pipe with welding the butt end edge. The production of the plate rolled steel pipe with thickened end part is thus enabled. |
