Patent ID: 8448486

Claim:
A curl-forming apparatus that receives a supplied reinforcing material-attached profile strip in which joint portions are formed at both side edge portions and to which a reinforcing material continuously formed in a longitudinal direction is attached, and that forms curls in the reinforcing material-attached profile strip before mutually adjacent joint portions are joined to each other to produce a spiral pipe, comprising: a support frame; a rotating frame that is surrounded by the support frame and that is supported in a freely rotatable manner via a plurality of rollers by the support frame, the plurality of rollers being disposed on the support frame; a motor that rotates the rotating frame; a curl guide that is disposed on the rotating frame and that is composed of an arc-like plate so as to configure a part of a spiral; a first pinch roller that is disposed on an upstream side of the curl guide; a second pinch roller that is disposed on a downstream side, of the curl guide; and a motor that rotationally drives at least one of the first pinch roller and the second pinch roller; wherein, the curl guide has a radius of curvature substantially similar to or not greater than a radius of curvature of spiral pipe; and in the curl-forming apparatus, while the rotating frame is rotated in an opposite direction to a supply direction of the reinforcing material-attached profile strip, the reinforcing material-attached profile strip is pushed into the curl guide or taken from the curl guide, and subjected to plastic deformation to form a spiral.