Abstract A method for producing a seamless tubing comprises extruding the thermoplastic material from extruder in the form of tubing in semi-molten condition, introducing the first compressed cooling medium into the tubing and radially spouting the fluid medium against the inner surface of the tubing wall for a certain distance thereby expanding the tubing into desired diameter and simultaneously cooling the tubing, and centripetally spouting the second compressed cooling fluid medium against the outer surface of the tubing wall simultaneously with the spout of the first fluid medium so as to sandwich the tubing wall by the both fluid medium for a certain distance. Further, an apparatus for the method comprises an extruder for extruding the thermoplastic material in the form of tubing in semi-molten condition, means for introducing the first compressed cooling fluid medium into the tubing, means for radially spouting the fluid medium against the inner surface of the tubing wall for a certain distance to expand and cool the tubing, means for centripetally spouting the second compressed cooling fluid medium against the outer surface of the tubing wall simultaneously with the spout of the first fluid medium so as to sandwich the tubing wall by the both fluid mediums for a certain distance, and means for continuously winding up the expanded, cooled tubing.
A method of producing a seamless tubing comprising extruding a thermoplastic material from an extruder in the form of a semimolten tubing, introducing a first compressed cooling fluid medium into the tubing and radially directing said first fluid medium outwardly onto the inner surface of the tubing for a predetermined distance thereby expanding the tubing to a desired diameter, the first fluid medium being directed successively from a plurality of longitudinally and radially spaced nozzles provided on an elongated inner cylindrical wall having a substantial length along the travelling direction of the tubing, centripetally directing a second compressed cooling fluid medium radially inwardly onto the outer surface of the tubing when the tubing reaches its desired diameter while continuing the directing of the first compressed cooling fluid medium, the second fluid medium being directed successively from a plurality of longitudinally and radially spaced nozzles provided on an elongated outer cylindrical wall having a substantial length along the travelling direction of the tubing, equalizing the pressure of the first fluid medium exerted onto the inner surface of the tubing with the pressure of the second fluid medium exerted onto the outer surface of the tubing to fix the inner and outer diameters of the tubing, pulling the tubing axially through the space defined by the inner and outer cylindrical walls through a pair of rotating pull rolls by a wind roll provided at the final end of the travelling direction of the tubing, collapsing the tubing into a flattened sheet by said pull rolls and winding the flattened tubing.
Claim 2
Independent Claim
258 words
A method of producing a seamless tubing comprising extruding a thermoplastic material from an extruder in the form of a semimolten tubing, introducing a first compressed cooling fluid medium into the tubing and radially directing said first fluid medium outwardly onto the inner surface of the tubing for a predetermined distance thereby expanding the tubing to a desired diameter, the first fluid medium being directed successively from a plurality of longitudinally and radially spaced nozzles provided on an elongated inner cylindrical wall having a substantial length along the travelling direction of the tubing, centripetally directing a second compressed cooling fluid medium radially inwardly onto the outer surface of the tubing when the tubing reaches its desired diameter while continuing the directing of the first compressed cooling fluid medium, the second fluid medium being directed successively from a plurality of longitudinally and radially spaced nozzles provided on an elongated outer cylindrical wall having a substantial length along the travelling direction of the tubing, equalizing the pressure of the first fluid medium exerted onto the inner surface of the tubing with the pressure of the second fluid medium exerted onto the outer surface of the tubing to fix the inner and outer diameters of the tubing, pulling the tubing axially through the space defined by the inner and outer cylindrical walls through a pair of rotating pull rolls by a wind roll provided at the final end of the travelling direction of the tubing, collapsing the tubing into a flattened sheet by said pull rolls and winding the flattened tubing.