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

A pipe-forming apparatus for 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 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;
• and
• a pipe end guide provided in a reverse portion of the apparatus frame in the machine-height direction, the pipe end guide being constrained with respect to the pipe end portion in a machine-width direction orthogonal to the propelling longitudinal direction and the machine-height direction, and the pipe end guide being engaged so as to be slidable with respect to the pipe end portion in the propelling longitudinal direction,
• wherein the pressing force becomes a fitting force for the fitting and a propelling force for forward propulsion, and wherein 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, and
• wherein the pipe end guide includes:
• a movable pressing portion movable in a plane orthogonal to the machine-width direction, the movable pressing portion is disposed on a propulsion rear side of the following strip portion extruded from the driving part and is disposed on a face side opposite to the reverse side beyond the pipe end portion;
• and
• a pressing portion biasing device biasing the movable pressing portion toward a propulsion front side or the reverse side along a direction in which the movable pressing portion is movable.

A pipe forming method for 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 by using a pipe-forming apparatus, the pipe forming method comprising:

• disposing an apparatus frame of the pipe-forming apparatus with a propelling longitudinal direction along a winding direction of a preceding spiral pipe portion on a partial part in a circumferential direction of a pipe end portion on a forefront side in an extending direction along a pipe axis of the preceding spiral pipe portion formed in advance in the strip member;
• pressing a following strip portion of an unformed pipe following the preceding spiral pipe portion of the strip member obliquely with respect to a machine-height direction along an inward-outward direction of the preceding spiral pipe portion toward the partial part or a vicinity thereof in the preceding spiral pipe portion by using a driving part provided in the apparatus frame;
• constraining a pipe end guide provided in a reverse portion of the apparatus frame in the machine-height direction in a machine-width direction orthogonal to the propelling longitudinal direction and the machine-height direction with respect to the pipe end portion and engaging the pipe end guide so as to be slidable in the propelling longitudinal direction;
• and
• forming the pipe in a state where a part other than the partial part of the pipe end portion is released from the pipe-forming apparatus with the pressing force becoming a fitting force for the fitting and a propelling force for forward propulsion.