As a countermeasure for dealing with cases in which the inner surface of existing pipes, such as an agricultural water pipe, a sewage pipe, and a water supply pipe undergo cracking or corrosion on the inner surface, or has deteriorated, a method is available in which existing pipes are rehabilitated by lining the inner surface with a plastic material.
In a method of this type, a plastic strip including joint portions at its opposite side edge portions is used, and the plastic strip is helically wound in an existing pipe to form a rehabilitating pipe for lining. For example, Patent Document 1 describes a method in which a drum around which a plastic strip is wound is installed on the ground, a winding machine is disposed in an existing pipe, the plastic strip is continuously supplied from the drum to the winding machine and is helically wound, and the joint portions of windings of the plastic strip that are arranged adjacent to each other by being wound are joined with each other, and thereby the plastic strip is formed into a tubular shape. The rehabilitating pipe thus formed is left as is in the existing pipe, and the plastic strip is newly fed, wound, and joined, and thereby a rehabilitating pipe is formed additionally and successively.
As shown in FIG. 21, a conventional winding machine 300 includes an annular frame 310 on which a plurality of rollers 320 are journaled, and a joining mechanism 330 for joining joint portions at opposite side edge portions of a plastic strip 600. The joining mechanism 330 includes an outer roller 331 and an inner roller 332, between which the plastic strip 600 is sandwiched to join the joint portions, and thereby the plastic strip is formed into a tubular shape. The winding machine 300 orbits along the inner surface of the existing pipe 200 by reaction that causes the plastic strip 600 to be sent out from the joining mechanism 330.
Meanwhile, sediment may exist or cracks or pits and projections have been formed on the inner surface of the existing pipe 200 due to a long-term use, and therefore there is the possibility that the outer roller 331 may get stuck by such pits and projections or the like. If the outer roller 331 gets stuck by the pits and projections on the inner surface on the existing pipe 200, it can no longer be smoothly rotated, which also makes the orbiting of the joining mechanism 330 difficult.