| 摘要 |
PURPOSE:To prevent the nose bending deformation that arises in a sizer stage in the stage of producing a metallic pipe by a Mannesmann plug mill system by improving a rolling method of a pierced blank pipe by a plug mill and a reeler. CONSTITUTION:The blank pipe pierced with a piercer is rolled with a plug mill in such a way that the wall thickness in the top part of the blank pipe after the rolling is thinner the nearer the forward end in the stage of producing a pipe with a Mannesmann process by a double piercing system from a steel billet or the like. The inside and outside surfaces of said blank pipe are polished with a reeler 3 so as to have a uniform wall thickness by rolling the blank pipe after the rolling in such a way as to form the tapered top part wherein the outside diameter in the top part of the pipe increases successively from the forward end up to the final end of the top part and by passing the blank pipe having such tapered top part through a sizer 4 to finish the same to the prescribed size. The nose bending in the forward end part of the metallic pipe in the sizer 4 is prevented. |
