Patent US3879158A successfully refreshed from Google Patents.
US3879158A
Expired / Lapsed
US
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Apparatus for extruding thermoplastic annular shapes
Assignee: Individual
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Filing: 1973-01-09
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Granted: 1975-04-22
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Expires: 1993-01-09
Abstract
Abstract An apparatus and method for producing annular extrudates of thermoplastic material characterized by uniformity of wall thickness and freedom of markings is provided. This is accomplished by compressing a molten thermoplastic by means of a rotating screw through an annular die having a rotating pin and a stationary bushing wherein the pin rotates in the same direction as the rotating screw and desirably is connected to the end of the screw. In a preferred embodiment the thermoplastic contact with the rotating pin is terminated prior to the termination of its contact with the stationary bushing. The compression of the molten thermoplastic is effected solely by screw generated pressure.
Inventors
- 👤 Enrique Schele
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 16:29
CPC Classifications
B; B29; B29C; B29C48/00; B29C48/25; B29C48/30; B29C48/32; B29C48/34; B29C48/03; B29C48/09; B29C48/10; B29C48/33
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
252 words
A screw-die extruder for producing annular extrudate characterized by uniformity of wall thickness, said screw-die extruder comprising a housing in which is provided at least one entry for the introduction entry of thermoplastic material from a feed extruder, a pressure generating screw rotatably mounted within said housing, said screw being connected to a rotary drive means, a die pin fixedly connected to the discharge end of said screw, a stationary die bushing mounted on said housing, encompassing said die pin to define an annular orifice in which said die pin rotates at the same rate as said screw, an axially located passageway extending through the length of said screw die extruder with two coaxial tubes of different diameters having a spaced relationship between them being mounted coaxially within said passageway such that three concentric passageways are formed, the outertube having a plurality of vents through its wall, the central of said passageways connecting to an axial passageway through said die pin and connected at its other end to an air source, the second passageway, defined by the spacing between said two coaxial tubes, being sealed at its forward end at the die pin and connected at its other end to a coolant source, the third of said passageways, defined between said outer coaxial tube and the wall of the axial passageway through the screw, being sealed at said die pin and connected at its other end to a conduit for removal of said coolant passing from the second passageway through said vents.
Claim 2
Dependent Claim
252 words
A screw-die extruder for producing annular extrudate characterized by uniformity of wall thickness, said screw-die extruder comprising a housing in which is provided at least one entry for the introduction entry of thermoplastic material from a feed extruder, a pressure generating screw rotatably mounted within said housing, said screw being connected to a rotary drive means, a die pin fixedly connected to the discharge end of said screw, a stationary die bushing mounted on said housing, encompassing said die pin to define an annular orifice in which said die pin rotates at the same rate as said screw, an axially located passageway extending through the length of said screw die extruder with two coaxial tubes of different diameters having a spaced relationship between them being mounted coaxially within said passageway such that three concentric passageways are formed, the outertube having a plurality of vents through its wall, the central of said passageways connecting to an axial passageway through said die pin and connected at its other end to an air source, the second passageway, defined by the spacing between said two coaxial tubes, being sealed at its forward end at the die pin and connected at its other end to a coolant source, the third of said passageways, defined between said outer coaxial tube and the wall of the axial passageway through the screw, being sealed at said die pin and connected at its other end to a conduit for removal of said coolant passing from the second passageway through said vents.
Claim 3
Dependent Claim
252 words
A screw-die extruder for producing annular extrudate characterized by uniformity of wall thickness, said screw-die extruder comprising a housing in which is provided at least one entry for the introduction entry of thermoplastic material from a feed extruder, a pressure generating screw rotatably mounted within said housing, said screw being connected to a rotary drive means, a die pin fixedly connected to the discharge end of said screw, a stationary die bushing mounted on said housing, encompassing said die pin to define an annular orifice in which said die pin rotates at the same rate as said screw, an axially located passageway extending through the length of said screw die extruder with two coaxial tubes of different diameters having a spaced relationship between them being mounted coaxially within said passageway such that three concentric passageways are formed, the outertube having a plurality of vents through its wall, the central of said passageways connecting to an axial passageway through said die pin and connected at its other end to an air source, the second passageway, defined by the spacing between said two coaxial tubes, being sealed at its forward end at the die pin and connected at its other end to a coolant source, the third of said passageways, defined between said outer coaxial tube and the wall of the axial passageway through the screw, being sealed at said die pin and connected at its other end to a conduit for removal of said coolant passing from the second passageway through said vents.
Claim 4
Dependent Claim
252 words
A screw-die extruder for producing annular extrudate characterized by uniformity of wall thickness, said screw-die extruder comprising a housing in which is provided at least one entry for the introduction entry of thermoplastic material from a feed extruder, a pressure generating screw rotatably mounted within said housing, said screw being connected to a rotary drive means, a die pin fixedly connected to the discharge end of said screw, a stationary die bushing mounted on said housing, encompassing said die pin to define an annular orifice in which said die pin rotates at the same rate as said screw, an axially located passageway extending through the length of said screw die extruder with two coaxial tubes of different diameters having a spaced relationship between them being mounted coaxially within said passageway such that three concentric passageways are formed, the outertube having a plurality of vents through its wall, the central of said passageways connecting to an axial passageway through said die pin and connected at its other end to an air source, the second passageway, defined by the spacing between said two coaxial tubes, being sealed at its forward end at the die pin and connected at its other end to a coolant source, the third of said passageways, defined between said outer coaxial tube and the wall of the axial passageway through the screw, being sealed at said die pin and connected at its other end to a conduit for removal of said coolant passing from the second passageway through said vents.
Claim 5
Dependent Claim
20 words
The screw-die of claim 1 wherein said coolant is water and air, such as in a fog or spray form.
Claim 6
Dependent Claim
74 words
The screw die extruder of claim (1) 1 wherein the rotatably mounted die pin and stationary die bushing are so configurated that the extrudate contact surface of the die pin terminates a (predetermined) sufficient distance prior to the terminal extrudate contact surface of the stationary die bushing to cause the extrudate to remain in contact with said bushing after passing beyond said pin and in that way eliminating the rotational movement of the extrudate.
Claim 7
Dependent Claim
46 words
The screw-die extruder of claim 1 wherein the rotatably mounted die pin and stationary die bushing are so configurated that the extrudate contact surface of the die pin terminates from 0.030 to 0.25 inch prior to the terminal extrudate contact surface of the stationary die bushing.
Claim 8
Dependent Claim
29 words
The screw-die extruder of claim 3 wherein the extrudate contact surface of the pin terminates from 0.060 to 0.125 inch prior to termination contact with the stationary die bushing.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-21 | 1978-10-21 | 1979-04-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-21 | 1982-10-21 | 1983-04-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-21 | 1986-10-21 | 1987-04-22 | $7700.00 | Window Closed / Lapsed |