Abstract: A method and apparatus for manufacturing continuous ribbed pipes of thermoplastic resin material comprises the following successive steps. A length of pipe is injection molded in a mold cavity between a collapsible male mold element and female mold elements, the latter being shaped to provide integral ribbing on the outer surface of the pipe. After sufficient setting, the female mold elements are disengaged and the male mold element is collapsed and disengaged. A plunger then pushes the pipe length axially along the male mold element. The female mold elements and the collapsed male mold element are then re-engaged such that the one end of the formed pipe forms a closure for the mold cavity at the downstream end. Further material is again injected into the cavity which fuses with the one pipe end and which forms a further pipe length. These steps are repeated until the desired length of pipe is formed.

Abstract: A method and apparatus for manufacturing continuous ribbed pipes of thermoplastic resin material comprises the following successive steps. A length of pipe is injection molded in a mold cavity between a collapsible male mold element and female mold elements, the latter being shaped to provide integral ribbing on the outer surface of the pipe. After sufficient setting, the female mold elements are disengaged and the male mold element is collapsed and disengaged. A plunger then pushes the pipe length axially along the male mold element. The female mold elements and the collapsed male mold element are then re-engaged such that the one end of the formed pipe forms a closure for the mold cavity at the downstream end. Further material is again injected into the cavity which fuses with the one pipe end and which forms a further pipe length. These steps are repeated until the desired length of pipe is formed.