| 摘要 |
PURPOSE: To execute positioning which is a reference for working tools, such as welding devices, with a simple mechanism by controlling a centering position on the basis of the axial center of a stationary pipe in such a manner that the upper and lower traveling wheels of a wheel frame slide and expand cooperatively in parallel. CONSTITUTION: Piston rods 16, 16 are expanded by applying an air pressure on fluid pressure cylinders 15, 15. At this time, operating rods 20, 20 journaled at their ends with sliding bodies move vertically and pull fulcrum pins 19, 19 at the terminals of the operating rods 20, 20 and, therefore, a turning ring 18 turns clockwise on the outer periphery of a rotating pipe via bearings 17. Then, even if the fluid pressure cylinders 15, 15 are not individually tuned on operation, the moving distances thereof are the turning angle of the turning ring 18 and, therefore, the moving distances are the same and the traveling wheels 14, 14 of the wheel frames 13, 13 move at the specified distance from the center of the rotating pipe and come into pressurized contact with the inside wall surface of the pipe P in contact with the circumscribing circle of the traveling wheels 14, 14. The centering of the rotating pipe is executed and the reference position of the welding device is fixed. |
