| 摘要 |
PURPOSE:To certainly fuse and integrate an inner cover layer and an outer cover layer, by bringing the space between a front stage die and a rear stage die, and the internal space of the outer cover layer extruded from the rear stage die in a cone shape to a mutually communicated hermetically closed space and controlling the internal pressure in this hermetically closed space. CONSTITUTION:A cylindrical outer cover 8 is arranged between a front stage die 11 and a rear stage die 12 and the circumference of an inner cover long body 100 is surrounded by the outer cover 18 while the air tube 9 connected to an air pressure control mechanism is provided to the cover 18. By this structure, the space between the front stage die 11 and the rear stage die 12 and the internal space of the outer cover layer 2 extruded from the rear stage die 12 in a cone shape are brought to a hermetically closed space mutually communicated by a communication hole 16. When the internal pressure of the hermetically closed space is controlled to negative pressure, the one shaped outer cover layer 2 extruded from the rear stage die 12 is internally sucked and, therefore, said cover layer is closely fused to and integrated with an inner cover layer 1 without involving air around projections (a). |
