US3860686A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of and apparatus for extruding plastic materials
Assignee: AT&T Inc
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Filing: 1972-11-03
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Granted: 1975-01-14
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Expires: 1992-11-03
Abstract
Abstract Flow conditions in an extrusion head in a cross head type extrusion apparatus for applying a concentric plastic insulating covering uniformly around a longitudinally advancing filamentary core advancing axially through a die concentrically disposed in an extrusion chamber in the head, are improved by providing channeled tooling within the chamber which bends and divides an initial stream of plastic material forced into the chamber into a plurality of equal streams which combine symmetrically around the core. With respect to certain channels, the ratio of the length of the channel to its effective cross-sectional diameter exceeds a predetermined critical number to achieve the development of steady state fluid flow therein. Additionally, whenever a stream of plastic material is divided subsequent to a bend before steady flow can develop therein, the division is made symmetrically with respect to the principal plane of the preceding bend to ensure identical pressure and velocity profiles in each of the divided streams.
Inventors
- 👤 Daryl Lester Myers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 06:56
CPC Classifications
H; H01; H01B; H01B13/00; H01B13/06; H01B13/14; B; B29; B29C; B29C48/00; B29C48/03; B29C48/06; B29C48/15; B29C48/25; B29C48/30; B29C48/32; B29C48/34; B29C48/36; B29C48/50; B29C48/695; B29C48/70; B29C48/05
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
210 words
A method of extruding a plastic covering around a filamentary core advancing sequentially through an extrusion chamber and an extrusion die which comprises the steps of: forcing a stream of molten plastic compound into the chamber transversely of said advancing core; bending said stream in the direction of the moving core at a first predetermined radial distance therefrom, dividing said bent stream into a first plurality of distinct streams in paths circumferentially spaced around the core at said first predetermined radial distance therefrom, each of said streams being of a sufficient length with respect to its cross-sectional size to achieve equal and constant pressures and velocities at the extremities thereof; directing said first plurality of streams radially inward toward said core; dividing each of said radially directed streams of plastic material into a second plurality of distinct streams circumferentially spaced around the core at a second lesser radial distance therefrom with all of the material of each of said second plurality of distinct streams being moved toward said extrusion die, each of said streams being of a sufficient length with respect to its cross-sectional size to achieve equal and constant pressures and velocities at the extremities thereof; and assembling said last divided streams at said die circumferentially around the core.
Claim 2
Independent Claim
210 words
A method of extruding a plastic covering around a filamentary core advancing sequentially through an extrusion chamber and an extrusion die which comprises the steps of: forcing a stream of molten plastic compound into the chamber transversely of said advancing core; bending said stream in the direction of the moving core at a first predetermined radial distance therefrom, dividing said bent stream into a first plurality of distinct streams in paths circumferentially spaced around the core at said first predetermined radial distance therefrom, each of said streams being of a sufficient length with respect to its cross-sectional size to achieve equal and constant pressures and velocities at the extremities thereof; directing said first plurality of streams radially inward toward said core; dividing each of said radially directed streams of plastic material into a second plurality of distinct streams circumferentially spaced around the core at a second lesser radial distance therefrom with all of the material of each of said second plurality of distinct streams being moved toward said extrusion die, each of said streams being of a sufficient length with respect to its cross-sectional size to achieve equal and constant pressures and velocities at the extremities thereof; and assembling said last divided streams at said die circumferentially around the core.
Claim 3
Dependent Claim
50 words
A method of extruding a plastic covering around a filamentary core, as set forth in claim 1, wherein a substantial part of the flow paths of individual ones of said first plurality of streams is directed parallel and opposite to the direction of said initial stream before the division thereof.
Claim 4
Independent Claim
282 words
A method of extruding a covering of plastic material upon a filamentary core advancing sequentially through an extrusion chamber and an extrusion die which comprises the steps of: forcing a stream of plastic material in a fluent state into the chamber in a direction normal to the path of the advancing core; bending said stream of plastic material to flow in the direction of and parallel to the path of the core at a first predetermined radial distance therefrom; dividing said bent stream into two equal streams transverse to the direction of said bent path and circumferentially at said predetermined first radial distance from said core; bending each of said equal streams in a direction parallel to and reversed from the direction of said advancing core at said first predetermined radial distance therefrom for a first predetermined longitudinal distance of a sufficient length with respect to its cross-sectional size to achieve equal and constant pressures and velocities at the extremities thereof; bending each of said equal bent streams radially toward said advancing core; dividing each of said radially directed streams transversely into a pair of equal streams at a second predetermined radial distance from said core; bending said divided radial streams tO flow toward and in the direction of said advancing core for a second predetermined longitudinal distance of a sufficient length with respect to its cross-sectional size to achieve equal and constant pressures and velocities at the extremities thereof with all of the material of each of said streams which are to flow along said second predetermined longitudinal distance being moved toward said extrusion die; and combining said last bent streams at circumferentially spaced points around the core in the die.
Claim 5
Independent Claim
282 words
A method of extruding a covering of plastic material upon a filamentary core advancing sequentially through an extrusion chamber and an extrusion die which comprises the steps of: forcing a stream of plastic material in a fluent state into the chamber in a direction normal to the path of the advancing core; bending said stream of plastic material to flow in the direction of and parallel to the path of the core at a first predetermined radial distance therefrom; dividing said bent stream into two equal streams transverse to the direction of said bent path and circumferentially at said predetermined first radial distance from said core; bending each of said equal streams in a direction parallel to and reversed from the direction of said advancing core at said first predetermined radial distance therefrom for a first predetermined longitudinal distance of a sufficient length with respect to its cross-sectional size to achieve equal and constant pressures and velocities at the extremities thereof; bending each of said equal bent streams radially toward said advancing core; dividing each of said radially directed streams transversely into a pair of equal streams at a second predetermined radial distance from said core; bending said divided radial streams tO flow toward and in the direction of said advancing core for a second predetermined longitudinal distance of a sufficient length with respect to its cross-sectional size to achieve equal and constant pressures and velocities at the extremities thereof with all of the material of each of said streams which are to flow along said second predetermined longitudinal distance being moved toward said extrusion die; and combining said last bent streams at circumferentially spaced points around the core in the die.
Claim 6
Dependent Claim
60 words
A method of extruding a covering of plastic material upon a filamentary core, as set forth in claim 3, wherein the ratio of said first predetermined longitudinal distance to the effective cross-sectional diameter of a reversed stream and the ratio of said second predetermined longitudinal distance to the effective cross-sectional diameter of a divided radial stream is a predetermined number.
Claim 7
Dependent Claim
27 words
A method of extruding a covering of plastic material upon a filamentary core, as set forth in claim 4, wherein said predetermined number is at least five.
Claim 8
Dependent Claim
48 words
A method of extruding a covering of plastic material upon a filamentary core, as set forth in claim 4, wherein the streams resulting from a dividing step subsequent to a bending step are symmetrical with respect to the principal plane of the bend immediately preceding the dividing step.
Claim 9
Dependent Claim
40 words
A method of extruding a covering of plastic material upon a filamentary core, as set forth in claim 3, wherein said combined streams of plastic material are prevented from contacting said core until it has substantially passed through said die.
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) | 1978-01-13 | 1978-07-15 | 1979-01-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-01-13 | 1982-07-15 | 1983-01-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-01-13 | 1986-07-15 | 1987-01-14 | $7700.00 | Window Closed / Lapsed |