Method of manufacturing a non-circular electrical cable having a reduced pulling force

Patent metadata

Field	Value
Publication number	US-11348707-B1
Application number	US-202016918688-A
Country	US
Kind code	B1
Filing date	Jul 1, 2020
Priority date	Feb 12, 2015
Publication date	May 31, 2022
Grant date	May 31, 2022

Abstract

In various embodiments, a non-circular electrical cable having a reduced pulling force attributable to the exterior surface of an outer sheath, and method of producing the same is provided. In various embodiments, an outer sheath of the cable may comprise a first and second sheath layer, the second sheath layer being located external to the first sheath layer, and comprising a nylon material configured to reduce the pulling force necessary for installing the cable. In various embodiments, the first sheath layer may be extruded using a tube extrusion method into a substantially circular shape, and the second sheath layer may be extruded using a pressure extrusion methods onto the exterior surface of the first sheath layer while maintaining the at least substantially circular shape of the sheath. The sheath may then be pulled onto the surface of a plurality of conductors to form the non-circular electrical cable.

First claim

That which is claimed:

1. A process for producing a non-circular electrical cable, the process comprising:
advancing one or more conductors through a non-circular guide channel defined through the extruder head;
extruding a first sheath layer comprising a plastic material around the one or more conductors through a substantially circular first sheath layer guide channel surrounding the non-circular guide channel of the extruder head, wherein the first sheath layer is initially extruded in a substantially circular shape having an inner surface and an exterior surface and at least a portion of the inner surface thereof is spaced from the one or more conductors;
extruding a second sheath layer around an exterior surface of the substantially circular first sheath layer through a second sheath layer guide channel of the extruder head, wherein the second sheath layer has a different polymer composition than the first sheath layer and the second sheath layer is extruded at a substantially uniform flowrate around a perimeter of the first sheath layer;
applying a negative pressure to the interior surface of the first sheath layer, thereby pulling the first sheath layer and second sheath layer onto the one or more conductors to form a non-circular sheath having a non-circular cross-sectional shape; and
cooling the first and second sheath layers.

2. The process of claim 1 , wherein the second sheath layer comprises a nylon material.

3. The process of claim 1 , further comprising providing a lubricant to the second sheath layer, wherein the lubricant decreases the pulling force of the non-circular electrical cable.

4. The process of claim 3 , wherein the lubricant comprises a silicon-based lubricant.

5. The process of claim 2 , further comprising combining the nylon material and a lubricant prior to extruding the second sheath layer, wherein the lubricant is configured for decreasing a required installation pulling force of the non-circular electrical cable.

6. The process of claim 1 , wherein the first sheath layer comprises a poly-vinyl chloride material.

7. The process of claim 6 , wherein the first sheath layer comprises a foamed poly-vinyl chloride material.

8. The process of claim 6 , wherein the first sheath layer comprises a re-grind poly-vinyl chloride material.

9. The process of claim 1 , wherein a mechanical bond is formed between the first sheath layer and the second sheath layer.

10. The process of claim 9 , wherein the mechanical bond comprises a heat bond.

11. The process of claim 1 , wherein the one or more conductors comprises a first conductor, a second conductor and a ground wire, wherein the first conductor has a first insulative coating on an external surface of the first conductor and the second conductor has a second insulative coating on an external surface of the second conductor, and wherein the first conductor, second conductor, and ground wire are arranged in a substantially flat configuration.

12. The process of claim 1 , wherein:
the first sheath layer is extruded at a first temperature;
the second sheath layer is extruded at a second temperature; and
the second temperature is higher than the first temperature.

13. The process of claim 12 , wherein the first temperature is at least 350 degrees Fahrenheit and the second temperature is at least 500 degrees Fahrenheit.

14. The process of claim 1 , wherein:
the first sheath layer is extruded at a first temperature of at least 350 degrees Fahrenheit;
the second sheath layer is extruded at a second temperature of at least 500 degrees Fahrenheit, and wherein the second temperature is higher than the first temperature; and
wherein cooling the first and second sheath layers comprises advancing the conductors, the first sheath layer, and the second sheath layer through a cooling box comprising a cooling fluid.

15. The process of claim 1 , wherein a thickness of the second sheath layer of the non-circular sheath, measured between the exterior surface of the first sheath layer and an exterior surface of the second sheath layer, varies by less than 40% around a perimeter of the non-circular sheath.

16. The process of claim 1 , wherein a thickness of the second sheath layer varies by less than 20% around the perimeter of the non-circular sheath.

17. The process of claim 1 , wherein a thickness of the second sheath layer varies by no more than 1 mil around the perimeter of the non-circular sheath.

18. The process of claim 1 , further comprising providing a dam paper surrounding the one or more conductors through the non-circular guide channel.

19. The process of claim 1 , wherein the non-circular guide channel has a substantially flat-oval cross-sectional shape.

Assignees

• Southwire Co Llc

Inventors

• Ledbetter Scotty
• Kummer Randy Deon

Classifications

• H01B13/24 Primary

  by extrusion {(extrusion of cables with plastic material in general B29C48/15)} · CPC title

• H01B13/0003

  for feeding conductors or cables · CPC title

• B29C48/06

  Rod-shaped · CPC title

• H01B7/1875

  Multi-layer sheaths · CPC title

• H01B7/0216

  Two layers · CPC title