JPS6477522A - Manufacture of corrugated tube with smooth inner surface - Google Patents

Abstract

PURPOSE:To efficiently manufacture a corrugated tube, the inner surface of which is smooth and on the outer surface of which spiral ridge is provided, by a method wherein a band-like body, which is produced by discharging thermoplastic resin from an outside die, is spirally wound so as to form an outer tube and an inner tube is formed by spirally and urgingly fusion-bonding a thermoplastic resin tape discharged from an inside die onto the inner surface of the recessed part of the outer tube. CONSTITUTION:Hot and molten thermoplastic resin band-like material (a), which is discharged from an outside die B having a deformed discharge orifice, is fed so as to straddle the spiral ridges 5 of a first revolving shaft assembly 1 equipped with the spiral ridges 5 under the predetermined drafting at a tilting angle in order to spirally wind, resulting in forming an outer tube (c) having spiral wave and being guided to a second revolving shaft assembly 2. Next, hot and molten thermoplastic resin tape (b), which is discharged from an inside die C housed near the center part of the second revolving shaft assembly 2 is fed onto the second revolving shaft assembly 2 so as to spirally wind in order to abut an inner tube (d) against the inner surface of the recessed part of the outer tube (c). Further, the recessed outer surface of the outer tube (c) is urgingly fusion-welded to said inner tube (d) with a press roll 8, which comes into opposedly contact with the second revolving shaft assembly 2, and finally cooled down and hardened.