| 摘要 |
<p>PURPOSE:To continuously and efficiently manufacture a conduit tube buried under the ground with excellent tensile strength, strength to external pressure, flexibility and the like by a method wherein the conduit tube is continuously composed by fixing both inner and outer pipes onto a metal pipe under pressure by pressing with a press roll at the stage that the temperature of the outer pipe still at a temperature, which is equal to or lower than the melting point and equal to or higher than the softening point. CONSTITUTION:A thermoplastic resin tape (b), which is delivered from an outside die 9, is spirally wound in such a manner as to be laid astride a projected-and-recessed strip formed on the peripheral surface at one end side of a metal pipe A with an angle of inclination in order to be formed into an outer pipe B with a spiral projected-and-recessed face by welding the sides of the tape to each other. A thermoplastic resin tape (c), which is delivered from an inside die 10, is spirally wound in such a manner as to be laid astride a projected-and- recessed strip formed on the inner peripheral surface of the metal pipe A with an angle of inclination in order to be formed into an inner pipe C by welding the sides of the tape to each other. Another heated and molten thermoplastic resin tape (c) delivered from the inside die 10 of an extruder is spirally wound onto the inner surface of the metal pipe A with an angle of inclination so as to overlap the thermoplastic resin tape (c) wound before with the thermoplastic resin tape (c) wound after in order to form the inner pipe C.</p> |
