| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and an apparatus for producing a steel pipe which, in production of a steel pipe by applying three-point bending to a plate material, enable the production efficiency and quality of the steel pipe to be improved.SOLUTION: The method for producing a steel pipe is provided in which three-point bending is applied to an intermittently fed plate material S multiple times using a die 4 which supports the plate material S at two positions along a feed direction and a punch 7 which presses the plate material S between support positions of the die 4 thereby forming an open tube Sin which a gap g is formed between end surfaces thereof, and then, the end surfaces of the open tube Sare butt-joined with each other. In the method for producing a steel pipe, pressing by the punch 7 is once stopped during bending of the plate material S, and bent angles &thetas; of both longitudinal-direction end parts and a longitudinal-direction central part of the plate material S are each measured on an introduction side and a leading-out side of the die 4 one or more times using angle meters 8a to 8f held by an arm 9. |
