Method and apparatus for joining sheet- or ribbon formed flows in a coextrusion process

摘要

Apparatus is described for coextruding two materials A and B, in which B is extruded on A through a port (3), in which the separating wall between the flows of A and B is formed as a flap closure (4) which can open and close by pivoting movements and is adapted to adjust its position in accordance with the difference between the pressures of A and B acting on it. The die is circular for extruding tubular flows and the flap closure is ring-formed and at least the hinge forming part of it consists of a springy blade having its surfaces generally perpendicular to the axis of the die. The tubular flows preferably exit in a direction substantial parallel to the axis of the die.