| 摘要 |
PURPOSE:To manufacture a stainless steel pipe having large diameter easily by forming a stainless steel plate into a body having polygonal profile by die bending, welding the end part and, after annealing, correcting roundness and straightness by upper and lower dies having semicircular profile. CONSTITUTION:A stainless steel plate 1 is placed on a gate stand 3 consisting of 3A, 3B and made to nearly hexagonal form by die bending using a punch 6, and then formed to pentagonal from by adjusting pressing force from the directions A, B and pressing force from the directions of C, D caused by rolls 10, 11. After welding butted parts 9 of the upper side 1C by a welding torch 19, unnecessary parts such as burrs at the weld zone is cut off and ground. Further, after checking the quality of welding, the stainless steel plate is tempered by annealing. Then, it is pickled, neutralized, washed with water and dried. Finally, the shape is corrected for roundness and straightness by an upper die 21 and a lower die 20 having semicircular inner face to obtain a large diameter stainless steel pipe. |
