Method and apparatus for the manufacture of reinforced smooth flow pipe

Apparatus for manufacturing reinforced, spirally wound pipe having a generally smooth inner wall from an elongated flat sheet of ductile material and one or more narrow strips of ductile material, comprising

• a. rolling means for continuously forming one longitudinal, generally trapezoidal reinforced impression in the elongated flat sheet corresponding to each of the narrow strips, said rolling means having an entry end for acceptance of said flat sheet and an exit end for issuing the reinforced sheet, and consisting essentially of
• i. means to form one longitudinal, generally rectangular channel in the sheet corresponding to each of said narrow strips,
• ii. means to shape each narrow strip into a reinforcement element having a first continuous portion of a lesser width than the width of said rectangular channels and a second continuous portion comprising a pair of splayed legs extending from the outer edges of said first portion,
• iii. means to insert each of said strips into a corresponding one of said rectangular channels, and
• iv. means to close the walls of each of said channels about said strips to form said trapezoidal impressions,
• b. a forming device proximate said exit end for continuously curling said reinforced sheet into adjacent, helical convolutions, and
• c. means to join said adjacent convolutions.