| 摘要 |
PURPOSE:To form a large diameter and thick-walled pipe with high accuracy by bending the part near the center of a forming material in the direction opposite from the bending direction in pipe bending then forming the material into a pipe shape by using cage rolls in the edge forming stage of an electric welded pipe. CONSTITUTION:Both ends of a forming material 35 are edge-formed to have a curved surface 31 approximately equal to that in pipe making by means of an upper roll 28 consisting of a shaft body 30 and a roll 31 and a lower roll 29 consisting of a recess 29a and a projecting part 29b whereby the part near the center is bent in the direction opposite from the direction in pipe forming. The material 35 is then gently bent by means of an upper roll 36 having a peripheral surface 36a and a lower roll 37 formed with a recessed surface 37a and thereafter the two ends of the material 35 are brought gradually close to each other by cage rolls 41- which contact with the outer surface of the material 35, feed rolls 38, 39, and idle rolls 40-, where cage-formed to a pipe shape. Formation of an electric welded pipe having high accuracy is thus made possible and the method deals with pipe making having a large diameter and thick walled high tension steel. |
