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

A pipe-forming apparatus for forming a spiral pipe by joining edges of a strip member adjacent with a difference of one lap with each other while spirally winding the strip member along a peripheral surface of an existing pipe, the pipe-forming apparatus comprising:

• an apparatus frame configured to be 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, and the apparatus frame having a propelling longitudinal direction along a winding direction of the preceding spiral pipe portion;
• a driving part provided in the apparatus frame and configured to join the preceding spiral pipe portion with a following strip portion of the strip member following the preceding spiral pipe portion, the driving part being configured to obtain a propelling force by pressing the following strip portion toward the preceding spiral pipe portion, the driving part including a driving roller having a contact part configured to contact the following strip portion, and an axis of the driving roller being oriented in a machine-width direction orthogonal to the propelling longitudinal direction and oriented along the extending direction;
• a support plate disposed on a front side in the extending direction from the contact part, the support plate being rotatably supported by the apparatus frame about a rotary axis directed in the machine-width direction;
• a non-circular guide portion connected to the support plate at a position on the front side in the extending direction from the contact part, the non-circular guide portion being integrally rotatable with the support plate with respect to the apparatus frame around the rotary axis, and the non-circular guide portion being configured to be applied to an outer peripheral surface on a side of the preceding spiral pipe portion facing the existing pipe;
• and
• an acting portion configured to act such that the non-circular guide portion follows the peripheral surface of the existing pipe or the preceding spiral pipe portion,
• wherein the pipe-forming apparatus is configured to perform 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.