Apparatus and Process for Producing Extruded Plastic Foil Hose

An apparatus for continuously manufacturing extruded plastic foil hose, comprising an extruder with a die having an annular drawing orifice suitable for forming the foil hose, and an internal and/or an external cooling device surrounding said drawing orifice and at least a portion of an expanded foil hose, said internal and/or external cooling device being provided with an inlet for a coolant, preferably cooling air, and being connected to a coolant supply and at least one outlet supplying coolant into an annular gap between the expanded foil hose to be cooled and an annular skirt of said internal and/or external cooling device, wherein said internal and/or external cooling device is a multistage device, preferably arranged directly on the extruder die and coaxially with the drawing orifice and having multilevel tangential outlets for the coolant to stabilize a first conical, non-stabilized section of said expanded foil hose by an internal and/or external spiral coolant stream, said multistage internal cooling device comprising at least two internal annular cooling-orienting units arranged at axial distances from each other, at least partly internally surrounding the non-stabilized section of the foil hose through the internal main annular gap, each of the internal annular cooling-orienting units being connected to the coolant supply in such a way as to supply the coolant with selectively and individually adjustable temperature and/or volume and/or pressure, said multistage external cooling device comprising at least two annular external cooling units arranged at an axial distance from each other, at least partly externally surrounding the conical, non-stabilized section of said expanded foil hose through the external main annular gap, each external cooling-orienting unit being provided with at least one tangential inlet and being connected to a second coolant supply for feeding the coolant with selectively and individually adjustable temperature and/or volume and/or pressure.

A process for producing plastic foil hose, said process comprising the steps of:

• surrounding at least a portion of a non-stabilized, expanded section of the foil hose just exiting from a drawing orifice of an extruder die by using an external multi-stage cooling device and thereby providing an external main ring gap at a radial distance from an external surface of the foil hose and/or by using an internal multi-stage cooling device and thereby providing an internal main ring gap at a radial distance from the internal surface of the foil hose;
• supplying coolant of selectively predetermined temperature and/or pressure and/or volume, mainly cooling air, into the external and/or internal main ring gap(s) through axially multi-level tangential inlets and directing the tangential coolant streams onto the external and/or internal surface(s) of the non-stabilized section of the foil hose in order to cool externally and/or internally the non-stabilized section of the foil hose, thereby stabilizing its structure by means of generating at least one spiral coolant stream from the multi-level tangential coolant streams within said external and/or internal main ring gap(s) by using a centrifugal force affecting the coolant streams along the external and/or internal surface(s) of the expanded foil hose, and by using density and pressure differences between various parts of the coolant flows.