| 摘要 |
PURPOSE:To equalize a variance of wall thickness of a resistance welded steel pipe, and to obtain steel pipes of different wall thickness from one kind of steel band, by performing the rolling in the wall thickness direction to an intermediate part of the steel band, and making the side end part thicker than the intermediate part. CONSTITUTION:In a breakdown stand group of a resistance welded pipe forming machine, a forming roller of first inlet side stand is reformed to rolling rollers 23, 24 having notch parts 23b, 24b in corner parts of the roller side ends and changed to a rolling stand, and rolling in the wall thickness direction is performed to the intermediate part of a slit material 1 before it is formed to a tubular body. An end part 1c of the slit material 1 which has been cut is formed to a crossing shape being thicker than the intermediate part. The slit material 1 which has been formed in such a way is formed to a tubular shape successively by a breakdown roller 2, a side roller 3, and also, a fin pass roller 4, brought to induction heating by a work coil 5, and both edges of an open pipe are pressed and joined by a squeeze roller 6.
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