Method and appraratus for forming a helical tube bundle

Apparatus for forming a plurality of tubes into a helical bundle, the apparatus comprising:

• a frame having a longitudinal axis;
• a carriage mounted to the frame, the carriage having supports engaging the frame, the supports constraining the carriage to move linearly along the longitudinal axis of the frame;
• a first bending die assembly mounted to the carriage, the first bending die assembly having a front surface, a rear surface and a plurality of guideways extending through from the front surface to the rear surface of the first bending die assembly, the guideways engaging the sides of the plurality of tubes to constrain the plurality of tubes laterally while allowing sliding engagement between the guideways and the plurality of tubes along an axis from the front surface to the rear surface of the first bending die assembly;
• a second bending die assembly mounted to the carriage, the second bending die assembly having a front surface, a rear surface and a plurality of guideways extending through from the front surface to the rear surface of the second bending die assembly, the guideways engaging the sides of the plurality of tubes to constrain the plurality of tubes laterally while allowing sliding engagement between the guideways and the plurality of tubes along an axis from the front surface to the rear surface of the second bending die assembly;
• drive means for rotating the first bending die assembly about an axis parallel to the longitudinal axis of the frame, the axis parallel to the frame defining the longitudinal axis of the helical bundle;
• drive means for rotating the second bending die assembly about the longitudinal axis of the helical bundle, the rotation of the second bending die assembly being independent of the rotation of the first bending die assembly;
• and
• drive means for moving the carriage linearly along the longitudinal axis of the frame.