| 摘要 |
Apparatus for extruding a pliable, thin-walled tube comprising an extrusion and shaping die assembly comprising an annular die body, a mandrel supported within the annular die body, a mandrel extension mounted on the mandrel adjacent the die outlet, the mandrel extension having a diameter less than the diameter of the mandrel, a sizing disk supported by the mandrel extension, and means to supply molten polymeric material to the die assembly under pressure to force the material through an annular extrusion flow channel around the mandrel and out the die outlet thereby forming a moving tube of the material, the mandrel extension extending outwardly from the die in the direction in which the tube isextruded, the annular die body having at least one fluid passageway to channel fluid introduced under pressure into the annular die body axially through the mandrel and outwardly from the axis of the mandrel extension to form an air pillow adapted to cool and support the tube around and spaced from the mandrel extension, and the sizing disk being adapted to restrict escape of the fluid and to define a chamber in cooperation with the tube of the molten polymeric material for confining the air pillow around the mandrel extension. This apparatus may be employed in a process to prepare a pliable, thin-walled tube. |
