| 摘要 |
PURPOSE:To decrease the longitudinal warp of a pipe within the limits of tolerance by changing the height of a gripper, in expanding a UOE steel pipe by a mechanical expander. CONSTITUTION:In inserting a pipe A to a mechanical expander, the height of a gripper 1 is set higher than that to be set for a straight pipe A, when the pipe A has an upward warp. Further, the height of gripper 1 is set lower to the contrary when the pipe A has a downward warp. And pipe bearing rolls 3 are lowered, at the time of inserting the pipe A to a head 5, so that the pipe A is supported only by the gripper 1 and a supporting roll 4. This lowering command is outputted by detecting the pipe end with the aid of a proximity switch 7 provided to the lower side of the head 5. Next, the pipe A is expanded while advancing a gripper dolly 2, and at the same time, the position of gripper 1 is changed at every pass in accordance with the advanced distance of the dolly 2. That is, when the pipe A has an upward ward, the gripper 1 is lowered in sequence, and when it has a downward warp, the gripper 1 is raised. And when the half length of pipe A is expanded, the remaining half is expanded from the other end.
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