Pipe-forming apparatus for spiral pipe and pipe-forming method thereof

A pipe-forming apparatus forming a spiral pipe by fitting edges of a strip member adjacent with a difference of one lap with each other while spirally winding the strip member, the spiral pipe-forming apparatus comprising:

• an apparatus frame disposed on a partial part in a circumferential direction of a pipe end portion of a preceding spiral pipe portion formed in advance of the strip member, the pipe end portion being provided on a forefront side in an extending direction along a pipe axis of the preceding spiral pipe portion, the apparatus frame having a propelling longitudinal direction being along a winding direction of the preceding spiral pipe portion;
• a driving part provided in the apparatus frame and pressing an unformed following strip portion of the strip member following the preceding spiral pipe portion obliquely with respect to a machine-height direction of the apparatus frame toward the partial part or a vicinity thereof in the preceding spiral pipe portion, the machine-height direction being along an inward-outward direction of the preceding spiral pipe portion;
• a reverse side guide portion provided away to a propulsion rear side from the driving part in the apparatus frame and engaged with the pipe end portion from a reverse side in the machine-height direction;
• and
• a face side guide portion shifted to the propulsion rear side beyond the reverse side guide portion in the apparatus frame and engaged with the pipe end portion from a face side opposite to the reverse side in the machine-height direction,
• wherein a position of the driving part with respect to the apparatus frame is set such that the following strip portion is extruded from the driving part toward an inter-guide clearance between the reverse side guide portion and the face side guide portion, and the pipe-forming apparatus performs pipe-forming in a state where a part of the pipe end portion other than the partial part is released from the pipe-forming apparatus.