PURPOSE: To prevent faulty biting and to obtain a seamless steel pipe having a uniform thickness by rolling a thickness of pipe end part in a tapered shape on a rolling stage through a piercing mill or an elongator of Mannessmann type, then subjecting to elongation rolling and rolling the thickness of the pipe end part in a tapered shape.
CONSTITUTION: In the stage of rolling the pipe end part in a tapered shape so that the thickness of the pipe end part becomes thinner toward the pipe end the rolling is performed without causing a faulty biting and a faulty shape of the pipe end. Furthermore, the blank pipe is elongation rolled by a succeeding plug mill and at the time of rolling the pipe end part in a tapered shape, a failing to roll caused by the faulty biting, etc., are not caused and the seamless steel pipe having uniform thickness is obtained in the last drawing roll mill.
MURAYAMA MASATOSHI
ITO KATSUYOSHI
| JPS59209414A | 1984-11-28 | |||
| JPS6116528A | 1986-01-24 | |||
| JPS5520764A | 1980-02-14 |
Next Patent: SHAPE CONTROL METHOD FOR ROLLED STOCK IN CONTINUOUS ROUGH ROLLING