Apparatus for making plastic film

Claim 2

A die for extruding plastic film, said die having, an inlet passage for receiving a plastic melt under pressure, a plurality of spaced channels having inlet ends communicating with said passage and having outlet ends, a combining chamber in said die communicating with said outlet ends, said combining chamber having a pair of approximately horizontally extending walls and an undulating peripheral surface extending substantially vertically between said walls, an annulus which has a discharge orifice for extruding the melt in tubular form film and said annulus having a receiving end communicating with said combining chamber, and a plurality of passages for a heat transfer fluid extending through the die between said channel inlet ends and said combining chamber, said plurality of passages for heat transfer fluid being adapted for supplying heat transfer fluid in a controlled manner adjacent both sides of the plastic melt passing through the die, said plurality of passages for supplying heat transfer fluid having inlet and outlet passages passing between several adjacent pairs of the plastic melt channels.

Claim 3

The die of claim 1, in which a pair of inlet and outlet passages for supplying the heat transfer fluid pass between the same pair of channels.

Claim 4

The die of claim 1, in which the plurality of passages for heat transfer fluid include a plurality of passages adjacent the inner side of the annulus and extend axially through the die generally parallel to each other in the portion of the die surrounded by the annulus.

Claim 5

A die foR making plastic film comprising, an inlet, a passage in said die communicating with said inlet, a stranding chamber in said die adjoining the peripheral edge of said passage, a plurality of spaced substantially axially ex-tending channels in said die communicating with said stranding chamber and each having a discharge end, a combining chamber in said die communicating with the discharge end of each spaced channel, and an annular discharge orifice in said die communicating with said combining chamber, each of said chambers having a pair of opposed approximately horizontally extending walls and an undulating peripheral surface extending substantially vertically between said walls, said undulating surface being defined by a plurality of substantially V-shaped surfaces interconnected at their bases by substantially arcuate surfaces with each arcuate surface being aligned with an associated wall portion of an associated channel, said V-shaped surfaces in said stranding chamber providing smooth converging flow of plastic melt into said channels and said V-shaped surfaces in said combining chamber providing smooth diverging flow of said melt into an annular passage communicating with said annular discharge orifice, said die being adapted to receive a plastic melt in said inlet as a solid column which is spread in said passage, separated into spaced strands in said channels, combined in said combining chamber to effectively minimize uneven flow rates in different parts of said die, and extruded from said orifice as a plastic tube having a substantially uniform thickness throughout.

Claim 6

A die foR making plastic film comprising, an inlet, a passage in said die communicating with said inlet, a stranding chamber in said die adjoining the peripheral edge of said passage, a plurality of spaced substantially axially ex-tending channels in said die communicating with said stranding chamber and each having a discharge end, a combining chamber in said die communicating with the discharge end of each spaced channel, and an annular discharge orifice in said die communicating with said combining chamber, each of said chambers having a pair of opposed approximately horizontally extending walls and an undulating peripheral surface extending substantially vertically between said walls, said undulating surface being defined by a plurality of substantially V-shaped surfaces interconnected at their bases by substantially arcuate surfaces with each arcuate surface being aligned with an associated wall portion of an associated channel, said V-shaped surfaces in said stranding chamber providing smooth converging flow of plastic melt into said channels and said V-shaped surfaces in said combining chamber providing smooth diverging flow of said melt into an annular passage communicating with said annular discharge orifice, said die being adapted to receive a plastic melt in said inlet as a solid column which is spread in said passage, separated into spaced strands in said channels, combined in said combining chamber to effectively minimize uneven flow rates in different parts of said die, and extruded from said orifice as a plastic tube having a substantially uniform thickness throughout.

Claim 7

A die as set forth in claim 4 and further comprising a fillet in each of said chambers extending between one of its horizontal walls and both its V-shaped surfaces and arcuate surfaces.

Claim 8

A die as set forth in claim 4 in which said inlet comprises a right circular cylindrical opening of extended length, each of said spaced channels has a circular cross-sectional configuration along its full length, and said annular discharge orifice is defined by a pair of cooperating spaced surfaces each having a right circular cylindrical configuration.

Claim 9

A die as set forth in claim 6 in which each of said spaced channels has a substantially frustoconical configuration defined by a precisely finished inside surface to thereby assure smooth flow of melt therethrough.

Claim 10

A die for making plastic film comprising, an inlet, a passage in said die communicating with said inlet, a stranding chamber in said die adjoining the peripheral edge of said passage, a plurality of spaced substantially parallel axially extending channels in said die communicating with said stranding chamber and each having a discharge end, a combining chamber in said die communicating with the discharge end of each spaced channel, said combining chamber having, a pair of opposed approximately horizontally extending walls and an undulating PERIPHERAL SURFACE EXTENDING SUBSTANTIALLY VERTICALLY BETWEEN SAID WALLS, AND AN ANNULAR DISCHARGE ORIFICE IN SAID DIE COMMUNICATING WITH SAID COMBINING CHAMBER, SAID DIE BEING ADAPTED TO RECEIVE A PLASTIC MELT IN SAID INLET AS A SOLID COLUMN WHICH IS SPREAD IN SAID PASSAGE, SEPARATED INTO SPACED STRANDS IN SAID SUBSTANTIALLY PARALLEL CHANNELS, COMBINED IN SAID COMBINING CHAMBER TO EFFECTIVELY MINIMIZE UNEVEN FLOW RATES IN DIFFERENT PARTS OF SAID DIE WITH SAID UNDULATING SURFACE ASSURING SMOOTH DIVERGING FLOW OF PLASTIC MELT INTO AN ANNULAR PASSAGE COMMUNICATING WITH SAID ORIFICE, AND EXTRUDED FROM SAID ORIFICE AS A PLASTIC TUBE HAVING A SUBSTNATIALLY UNIFORM THICKNESS THROUGHOUT.

Claim 11

A die for making plastic film comprising, an inlet, a passage in said die communicating with said inlet, a stranding chamber in said die adjoining the peripheral edge of said passage, a plurality of spaced substantially parallel axially extending channels in said die communicating with said stranding chamber and each having a discharge end, a combining chamber in said die communicating with the discharge end of each spaced channel, said combining chamber having, a pair of opposed approximately horizontally extending walls and an undulating PERIPHERAL SURFACE EXTENDING SUBSTANTIALLY VERTICALLY BETWEEN SAID WALLS, AND AN ANNULAR DISCHARGE ORIFICE IN SAID DIE COMMUNICATING WITH SAID COMBINING CHAMBER, SAID DIE BEING ADAPTED TO RECEIVE A PLASTIC MELT IN SAID INLET AS A SOLID COLUMN WHICH IS SPREAD IN SAID PASSAGE, SEPARATED INTO SPACED STRANDS IN SAID SUBSTANTIALLY PARALLEL CHANNELS, COMBINED IN SAID COMBINING CHAMBER TO EFFECTIVELY MINIMIZE UNEVEN FLOW RATES IN DIFFERENT PARTS OF SAID DIE WITH SAID UNDULATING SURFACE ASSURING SMOOTH DIVERGING FLOW OF PLASTIC MELT INTO AN ANNULAR PASSAGE COMMUNICATING WITH SAID ORIFICE, AND EXTRUDED FROM SAID ORIFICE AS A PLASTIC TUBE HAVING A SUBSTNATIALLY UNIFORM THICKNESS THROUGHOUT.

Claim 12

A die for making plastic film comprising, an inlet, a passage in said die communicating with said inlet, a stranding chamber in said die adjoining the peripheral edge of said passage, a plurality of spaced substantially parallel axially extending channels in said die communicating with said stranding chamber and each having a discharge end, a combining chamber in said die communicating with the discharge end of each sPaced channel, and an annular passage in said die communicating with said combining chamber and terminating in an annular discharge orifice, said die being adapted to recieve a plastic melt in said inlet as a solid column which is spread in said passage, separated into spaced strands in said channels, combined in said combining chamber to effectively minimize uneven flow rates in different parts of said die, and extruded from said orifice as a plastic tube having a substantially uniform thickness throughout, said die comprising, three portions in the form of a lower portion, an upper portion, and a central portion, said inlet being defined as a right circular cylindrical bore in said lower portion, said passage being defined as a conically extending passage between said lower portion and said central portion, said spaced channels being defined in said central portion and having longitudinal axes arranged in a substantially circular pattern which is larger in diameter than the diameter of said annular discharge orifice, said combining chamber being arranged within said circular pattern of said spaced channels and providing a flow path radially inwardly toward the center of said die into said annular passage, and said annular passage and annular discharge orifice being defined in said upper portion.

Claim 13

A die for making plastic film comprising, an inlet, a passage in said die communicating with said inlet, a stranding chamber in said die adjoining the peripheral edge of said passage, a plurality of spaced substantially parallel axially extending channels in said die communicating with said stranding chamber and each having a discharge end, a combining chamber in said die communicating with the discharge end of each sPaced channel, and an annular passage in said die communicating with said combining chamber and terminating in an annular discharge orifice, said die being adapted to recieve a plastic melt in said inlet as a solid column which is spread in said passage, separated into spaced strands in said channels, combined in said combining chamber to effectively minimize uneven flow rates in different parts of said die, and extruded from said orifice as a plastic tube having a substantially uniform thickness throughout, said die comprising, three portions in the form of a lower portion, an upper portion, and a central portion, said inlet being defined as a right circular cylindrical bore in said lower portion, said passage being defined as a conically extending passage between said lower portion and said central portion, said spaced channels being defined in said central portion and having longitudinal axes arranged in a substantially circular pattern which is larger in diameter than the diameter of said annular discharge orifice, said combining chamber being arranged within said circular pattern of said spaced channels and providing a flow path radially inwardly toward the center of said die into said annular passage, and said annular passage and annular discharge orifice being defined in said upper portion.

Claim 14

A die for making plastic film comprising, an inlet, a passage in said die communicating with said inlet, a stranding chamber in said die adjoining the peripheral edge of said passage, a plurality of spaced substantially parallel axially extending channels in said die communicating with said stranding chamber and each having a discharge end, a combining chamber in said die communicating with the discharge end of each spaced channel, and an annular passage in said die communicating with said combining chamber and terminating in an annular discharge orifice, said die being adapted to receive a plastic melt in said inlet as a solid column which is spread in said passage, separated into spaced strands in said channels, combined in said combining chamber to effectively minimize uneven flow rates in different parts of said die, and extruded from said orifice as a plastic tube having a substantially uniform thickness throughout, said spaced channels having longitudinal axes arranged in a substantially circular pattern which is larger in diameter than the diameter of said annular discharge orifice, said combining chamber being arranged within said circular pattern of said spaced channels and providing a flow path radially inwardly toward the center of said die into said annular passage, said die comprising a bottom portion which is adapted to be supported in a fixed position and a rotatable portion comprising the remainder of said die and being rotatable on said bottom portion.

Claim 15

A die for making plastic film comprising, an inlet, a passage in said die communicating with said inlet, a stranding chamber in said die adjoining the peripheral edge of said passage, a plurality of spaced substantially parallel axially extending channels in said die communicating with said stranding chamber and each having a discharge end, a combining chamber in said die communicating with the discharge end of each spaced channel, and an annular passage in said die communicating with said combining chamber and terminating in an annular discharge orifice, said die being adapted to receive a plastic melt in said inlet as a solid column which is spread in said passage, separated into spaced strands in said channels, combined in said combining chamber to effectively minimize uneven flow rates in different parts of said die, and extruded from said orifice as a plastic tube having a substantially uniform thickness throughout, said spaced channels having longitudinal axes arranged in a substantially circular pattern which is larger in diameter than the diameter of said annular discharge orifice, said combining chamber being arranged within said circular pattern of said spaced channels and providing a flow path radially inwardly toward the center of said die into said annular passage, said die comprising a bottom portion which is adapted to be supported in a fixed position and a rotatable portion comprising the remainder of said die and being rotatable on said bottom portion.

Claim 16

A die for extruding plastic film having, an inlet passage for receiving a plastic melt under pressure, a plurality of spaced plastic melt conveying channels which have their inlets communicating with said passage, an annulus which has a discharge orifice for extruding the melt in tubular form film and said annulus having a receiving end communicating with the outlet ends of said channels, said plastic melt conveying channels being arranged in parallel relation and having longitudinal axes arranged in a substantially circular pattern which is larger in diameter than the diameter of said discharge orifice, a plurality of passages for a heat transfer fluid extending through the die between the channel inlet ends and the annulus, said plurality of passages for heat transfer fluid being adapted for supplying heat transfer fluid in a controlled manner adjacent both sides of the plastic melt passing through the die, said plurality of passages for supplying heat transfer fluid having inlet and outlet passages passing between several adjacent pairs of the plastic melt conveying channels.

Claim 17

A die for extruding plastic film having, an inlet passage for receiving a plastic melt under pressure, a plurality of spaced plastic melt conveying channels which have their inlets communicating with said passage, an annulus which has a discharge orifice for extruding the melt in tubular form film and said annulus having a receiving end communicating with the outlet ends of said channels, said plastic melt conveying channels being arranged in parallel relation and having longitudinal axes arranged in a substantially circular pattern which is larger in diameter than the diameter of said discharge orifice, a plurality of passages for a heat transfer fluid extending through the die between the channel inlet ends and the annulus, said plurality of passages for heat transfer fluid being adapted for supplying heat transfer fluid in a controlled manner adjacent both sides of the plastic melt passing through the die, said plurality of passages for supplying heat transfer fluid having inlet and outlet passages passing between several adjacent pairs of the plastic melt conveying channels.

Claim 18

A die for making plastic film comprising, an inlet, a passage in said die communicating with said inlet, a stranding chAmber in said die adjoining the peripheral edge of said passage, a plurality of spaced substantially axially extending channels in said die communicating with said stranding chamber and each having a discharge end, a combining chamber in said die communicating with the discharge end of each spaced channel, and an annular passage in said die communicating with said combining chamber and terminating in an annular discharge orifice, said die having a lower portion, an upper portion, and a central portion, said inlet being defined as a right circular cylindrical bore in said lower portion, said passage being defined as a conically extending passage between said lower portion and said central portion, said spaced channels being defined in said central portion and having longitudinal axes arranged in a substantially circular pattern which is larger in diameter than the diameter of said annular discharge orifice, said combining chamber being arranged within said circular pattern of said spaced channels and providing a flow path radially inwardly toward the center of said die into said annular passage, and said annular passage and annular discharge orifice being defined in said upper portion.

Claim 19

A die for making plastic film comprising, an inlet, a passage in said die communicating with said inlet, a stranding chAmber in said die adjoining the peripheral edge of said passage, a plurality of spaced substantially axially extending channels in said die communicating with said stranding chamber and each having a discharge end, a combining chamber in said die communicating with the discharge end of each spaced channel, and an annular passage in said die communicating with said combining chamber and terminating in an annular discharge orifice, said die having a lower portion, an upper portion, and a central portion, said inlet being defined as a right circular cylindrical bore in said lower portion, said passage being defined as a conically extending passage between said lower portion and said central portion, said spaced channels being defined in said central portion and having longitudinal axes arranged in a substantially circular pattern which is larger in diameter than the diameter of said annular discharge orifice, said combining chamber being arranged within said circular pattern of said spaced channels and providing a flow path radially inwardly toward the center of said die into said annular passage, and said annular passage and annular discharge orifice being defined in said upper portion.

Claim 20

A die as set forth in claim 12 in which each of said spaced channels has a decreasing cross-sectional area from its inlet to its outlet.

Claim 21

A die as set forth in claim 12 in which each of said spaced channels has a substantially frustoconical configuration.

Claim 22

The die of claim 1 and further comprising passages for supplying pre-heated gas continuously to inflate the tubular form film emerging from the orifice and passages for withdrawing cooled gas in the tubular film, said supplying passages comprising inlet passages extending through the die inwardly between several pairs of adjacent spaced channels and thence out of the portion of the die surrounded by the orifice, and said withdrawing passages comprising outlet passages extending outwardly between several pairs of adjacent spaced melt channels.

Claim 23

The die of claim 15 in which the gas outlet passages pass between pairs of channels other than those between which the gas inlet and heat transfer fluid inlet and outlet passages pass.

Claim 24

A die as set forth in claim 10 in which said rotatable portion comprises a plurality of components fixed together by a plurality of bolts with each bolt extending through aligned enlarged openings in said components to define an annular gas passage of extended length between each bolt and said components, said gas passages being adapted to flow gas from said tubular form film substantially axially through said die. peripheral surface extending substantially vertically between said walls, and an annular discharge orifice in said die communicating with said combining chamber, said die being adapted to receive a plastic melt in said inlet as a solid column which is spread in said passage, separated into spaced strands in said substantially parallel channels, combined in said combining chamber to effectively minimize uneven flow rates in different parts of said die with said undulating surface assuring smooth diverging flow of plastic melt into an annular passage communicating with said orifice, and extruded from said orifice as a plastic tube having a substantially uniform thickness throughout.