| 摘要 |
PURPOSE:To manufacture the pressure resistant synthetic resin pipe having good appearance, a high accuracy and excellent pressure resistance by a method wherein a reinforcing material is fed in a spiral form into a spiral groove between the spiral projections of the preformed synthetic resin pipe rotating about its axis, while a thin strip-like steel plate having a predetermined width is being formed into the reinforcing material having a suitable cross sectional configuration by a shaping instrument. CONSTITUTION:Both sides of the lower peripheral part of a synthetic resin pipe 1 provided with a hollow spiral projection 2 around the outer peripheral surface of a cylindrical pipe wall 1a integrally therewith are receivably held by rotary feeding rolls 4 and a reinforcing material 5 bent into a U-shaped cross-sectional configuration is continuously fed for engagement with a spiral groove 3 between the spiral projections 2 of the synthetic resin pipe 1 adapted to move forward while rotating on the rolls 4. Upon feeding the reinforcing material 5 into the spiral groove 3 of the synthetic resin pipe 1, through almost one complete revolution of the pipe, the reinforcing material 5 is gradually inserted into the spiral groove 3 by a shaping roller 8, while being moved in a standing position with both its side faces 5b urged against both side wall surfaces of the spiral groove 3 and entirely held against the facing sides of the spiral groove 3. This reinforcing material 5 is enclosed with a synthetic resin strip-like material 9 composed of the same material as the synthetic resin pipe 1 to form a resin layer 11. |
