Koextrusionsmaschine und Verfahren zum Verändern des Innenprofils eines rohrförmigen Extrudats.

摘要

Coextrusion apparatus for varying the inner profile of a generally tubular extrudate (82) formed by a first stream of elastomeric material, by an axially movable inner die ring (35) which varies the size of an orifice and consequently the flow of a second stream of elastomeric material which is deposited on the inner surface of the tubular extrudate. A compensating ring (40) is axially slideably mounted within the inner die ring (35) and moves generally in an opposite direction to the movement of the die ring to compensate for pressure changes within the second stream of material caused by varying the size of the orifice, to provide an accurately controlled initiation and termination of the material. Concentrically mounted pressure actuated piston rods control the movement of the inner die ring (35) and compensation ring (40). The orifice for the second stream of elastomeric material is located slightly downstream of the orifice for the tubular extrudate and extends in a generally radial direction. A reinforcing guide (29) directs a plurality of fiber-type reinforcing elements (31) into the tubular extrudate prior to depositing the second stream of elastomeric material on the inner surface thereof. A method for varying the inner profile of the interior surface of a tubular extrudate is also presented.