| 摘要 |
<p>PROBLEM TO BE SOLVED: To bend a composite tube in a desirable shape by giving the tube a tubular core having a winding provided with inner and outer plastic layers made by simultaneous extrude to form the tube having a smooth opening and smooth outer surface. SOLUTION: A composite tube is composed of a core 10 of inner-metal or polymer on which windings 11 are spaced in a longitudinal direction of the core 10. The windings 11 has round inner and outer corners 12, 13 to form substantially square section. The core 10 is covered with polymer layer 14 and 15 simultaneously extruded onto other core 10 by a single extruding operation on its inner and outer surfaces. The compound pipe having a smooth opening 16 and a smooth outer surface 17 is formed. The tubular core 10 is hard compared to the polymer layer, while it is permanently deformed when it is bent. The composite tube can be bent within a desired diametral range or to obtain other shape. The inner core 10 keeps a desired shape of the pipe.</p> |
