Abstract In an apparatus for manufacturing a tubular resinous film wherein a tubular film of a thermoplastic film is extruded from an extrusion nozzle, cooled, heated, expanded and wrapped into a roll, a circumferential twist is intermittently imparted to the tubular resinous film after it is cooled but before it is heated and expanded, or circumferential twists in the opposite directions are imparted alternately, by means of cooperating inner and outer rollers which are revolved in the circumferential direction of the tubular resinous film. Means to cool the extruded tubular resinous film comprises a first stationary cooling cylinder having a diameter slightly smaller than the inner diameter of the tubular resinous film, a second rotary cooling cylinder having a diameter slightly larger than that of the first cooling cylinder and adapted to contact and cool the inner surface of the extruded tubular resinous film, and means to form a layer of cooling gas between the inner surface of the extruded tubular resinous film and the periphery of the first cooling cylinder.
In an apparatus for manufacturing a tubular resinous film wherein said tubular resinous film is extruded by a stationary annular extrusion nozzle, said nozzle having an inherent tendency to form a tubular resinous film of nonuniform thickness, folded into a flat sheet and wrapped into a roll, the improvement which comprises a pluralIty of inner rollers having axes of rotation substantially perpendicular to the direction of extrusion of said tubular resinous film from said extrusion nozzle and maintained in contact with the inner surface of said tubular resinous film, a plurality of outer rollers cooperating with respective inner rollers and having axes of rotation substantially parallel to those of corresponding inner rollers, both of said inner and outer rollers being disposed adjacent said nozzle, means for revolving said inner and outer rollers at the same angular speed in the circumferential direction of said tubular resinous film so as to twist said tubular resinous film in the circumferential direction and to evenly distribute said portions of nonuniform thickness along the length of said roll, a stationary cooling former secured to said extrusion die, and a rotary cooling former positioned between said inner rollers and said stationary cooling former, said rotary cooling former being rotatably journaled by said stationary cooling former.
Claim 2
Dependent Claim
209 words
In an apparatus for manufacturing a tubular resinous film wherein said tubular resinous film is extruded by a stationary annular extrusion nozzle, said nozzle having an inherent tendency to form a tubular resinous film of nonuniform thickness, folded into a flat sheet and wrapped into a roll, the improvement which comprises a pluralIty of inner rollers having axes of rotation substantially perpendicular to the direction of extrusion of said tubular resinous film from said extrusion nozzle and maintained in contact with the inner surface of said tubular resinous film, a plurality of outer rollers cooperating with respective inner rollers and having axes of rotation substantially parallel to those of corresponding inner rollers, both of said inner and outer rollers being disposed adjacent said nozzle, means for revolving said inner and outer rollers at the same angular speed in the circumferential direction of said tubular resinous film so as to twist said tubular resinous film in the circumferential direction and to evenly distribute said portions of nonuniform thickness along the length of said roll, a stationary cooling former secured to said extrusion die, and a rotary cooling former positioned between said inner rollers and said stationary cooling former, said rotary cooling former being rotatably journaled by said stationary cooling former.
Claim 3
Dependent Claim
58 words
The apparatus according to claim 1 wherein said stationary and rotary formers are in the form of water cooled cylinders, said stationary former has a diameter slightly smaller than that of the rotary former, and a layer of cooling gas is formed between the inner surface of said tubular resinous film and the periphery of said stationary former.