| 摘要 |
PURPOSE:To produce efficiently a long-sized seamless pipe having no thickness deviation by forming a blank material having a round sectional shape into a hollow blank pipe by a three-roll type inclined piercing method, forming a pseudo-bottom to one end thereof, inserting a mandrel into the pipe and rolling the pipe by a push-bench rolling method. CONSTITUTION:A blank material 1 having a circular section is heated in a heating furnace 7 to the temp. at which said material can be pierced and thereafter the blank material is pierced to a relatively thick walled hollow blank material by an inclined rolling method 8 having three rolls each having a drum-shape and a piercing plug. Such blank pipe is diametrally reduced by an outside sinking rolling method 9 according to need and thereafter one end thereof is drawn to a tubular body provided with a pseudo-bottom by a pipe end swaging method 10. A mandrel 6 is then inserted into the pipe from the open side at the other end by a driving rack and the pipe is rolled by a push-bench rolling method 5. The blank pipe is thereafter finished of the pipe surface by reeler rolling 11 and is cut to a standard size by a saw 12. The cut pipe is finished to a specifed diameter and round shape by a sizing method or is reduced to a desired pipe diameter by a drawing method 15 after heating, by which the product of the seamless pipe is obtd. |
