US4493747A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for insulating conductors with a crystalline plastic material
Assignee: AT&T Inc
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Filing: 1983-09-02
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Granted: 1985-01-15
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Expires: 2003-09-02
Abstract
Abstract An extrusion system is provided for covering a conductor (14) with a crystalline thermoplastic elastomer insulating material. The plastic material is tubed onto the conductor by apparatus which includes a core tube (61) that is mounted in an extruder crosshead (41) such that its free end is positioned within the interior of a die (81, 101) and is spaced from an orifice of the die a predetermined percentage of the land length of the die. A flow passage between the core tube (61) and a wall which defines the die cavity is controlled in accordance with the relative value of the thermal energy which is released by the insulating material at the onset of crystallization. In one arrangement, which has been found to be suitable for a crystalline thermoplastic elastomer having a relatively high value of released thermal energy, the die cavity and the core tube are arranged to provide a gradually converging path toward the die opening. For an insulating material having a relatively low value of released thermal energy, the flow passage is modified to provide a diverging portion (105) and then a rapidly converging portion (110) which communicates with the land of the die.
Inventors
- 👤 William M. Kanotz
- 👤 William C. Vesperman
- 👤 Max K. Wilson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 13:55
CPC Classifications
H; H01; H01B; H01B13/00; H01B13/06; H01B13/14; H01B13/148; B; B29; B29C; B29C48/00; B29C48/03; B29C48/06; B29C48/09; B29C48/15; B29C48/25; B29C48/88; B29C48/911; B29C48/92; H01B13/143; B29C2948/00; B29C2948/92; B29C2948/92009; B29C2948/92085; B29C2948/92104; B29C2948/92219; B29C2948/92504; B29C2948/9258; B29C2948/926; B29C2948/92609; B29C2948/92819; B29C2948/92942; B29C48/05
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
206 words
A method of extruding a crystalline plastic material, said method including the steps of: determining the thermal energy which is released by a sample of the plastic material over a predetermined temperature range at the onset of crystallization as the sample of the plastic material is cooled after having been melted, cooled and remelted; then providing a die having an exit orifice which communicates through a land of the die with a cavity of the die and a core tube having a free end recessed within the land of the die and having a passageway aligned within the die orifice; providing a flow passage for the plastic material between a wall which defines the die cavity and an outer surface of the core tube, said flow passage converging to the die land and being configured in accordance with the relative value of the thermal energy which is released by the plastic material at the onset of crystallization; advancing a conductor along a path through the passageway of the core tube and the die orifice; flowing the plastic material along the flow passage and through the die orifice; and controlling the step of advancing the conductor to control the drawdown of the plastic material on the conductor.
Claim 2
Independent Claim
206 words
A method of extruding a crystalline plastic material, said method including the steps of: determining the thermal energy which is released by a sample of the plastic material over a predetermined temperature range at the onset of crystallization as the sample of the plastic material is cooled after having been melted, cooled and remelted; then providing a die having an exit orifice which communicates through a land of the die with a cavity of the die and a core tube having a free end recessed within the land of the die and having a passageway aligned within the die orifice; providing a flow passage for the plastic material between a wall which defines the die cavity and an outer surface of the core tube, said flow passage converging to the die land and being configured in accordance with the relative value of the thermal energy which is released by the plastic material at the onset of crystallization; advancing a conductor along a path through the passageway of the core tube and the die orifice; flowing the plastic material along the flow passage and through the die orifice; and controlling the step of advancing the conductor to control the drawdown of the plastic material on the conductor.
Claim 3
Dependent Claim
27 words
The method of claim 1, wherein the flow passage diverges, then abruptly converges to the land for a plastic material having a relatively low onset crystallization energy.
Claim 4
Dependent Claim
41 words
The method of claim 1, which also includes the step of cooling the plastic material after the plastic material is moved out of the orifice of the die, said step of cooling being accomplished in a manner to control the crystallization.
Claim 5
Dependent Claim
25 words
The method of claim 1, wherein the flow passage converges gradually to the land for a plastic material having a relatively high onset crystallization energy.
Claim 6
Dependent Claim
24 words
The method of claim 1, wherein the step of determining the energy of the plastic material is accomplished in an environment comprising static air.
Claim 7
Dependent Claim
58 words
The method of claim 5, wherein said method also includes the steps of heating the sample of the plastic material to a predetermined temperature, cooling the plastic material at a predetermined rate and then reheating and recooling the plastic material, the step of determining the thermal energy which is released being accomplished as the plastic material is recooled.
Claim 8
Dependent Claim
20 words
The method of claim 6, wherein said step of cooling is accomplished at a rate of 30±5° C. per minute.
Claim 9
Dependent Claim
19 words
The method of claim 6, wherein the plastic material is heated and reheated to a temperature of 270° C.
Claim 10
Dependent Claim
21 words
The method of claim 6, wherein the plastic material is heated and reheated at a rate of 10±1° C. per minute.
Claim 11
Dependent Claim
77 words
The method of claim 6, wherein said method includes generating a curve which depicts the heat flow of the plastic material as the plastic material is cooled after having been reheated and for determining an area under the curve between a temperature at which the onset of crystallization occurs and a temperature which is 15° C. lower, said area being representative of the energy released during crystallization and indicative of the crystallization characteristics of the plastic material.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-01-15 | 1988-07-16 | 1989-01-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-01-15 | 1992-07-16 | 1993-01-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-01-15 | 1996-07-16 | 1997-01-15 | $7700.00 | Window Closed / Lapsed |