| 摘要 |
PURPOSE:To enable the expansion of the inside pipe to be accomplished while making sealing sure by making equal the inside diameter of the cylinder chamber communicated with the rear parts of the pipe expanding liquid feed holes pierced in the press-fit plugs and the inside diameter of the inside pipe. CONSTITUTION:Press-fit plugs 9, 9' have tapered parts 10, 10' on the outer side of their inside ends and are formed with cylinder chambers 11, 11' of the same diameter as the inside diameter R of an inside pipe 4 in the inside rear part, these cylinder chambers 11, 11' being communicated with the pipe expanding liquid feed hole 12 and discharge hole 12' communicated with the inside pipe 4. With this constituition, the cylinders 11, 11' of the press-fit plugs 9, 9' are communicated by way of the feed hole 12 and discharge hole 12' in the pipe expanding process. Since the inside diameters thereof are the same as the inside diameter of the press-fit plugs 9, 9', the axial direction reaction force for the press-fit plugs 9, 9' is negated, hance the sealing pressure of the tapered parts 10, 10' of the press-fit plugs 9, 9' for the end part of the inside pipe 4 is sufficiently maintained by the lock set pressure of the press-fitting cylinders 7, 7', due to which the leakage of the working water 28 from the sealing part is prevented. |
