CA1302310C - Plastic conduit with integral pull wire - Google Patents
Plastic conduit with integral pull wireInfo
- Publication number
- CA1302310C CA1302310C CA000542784A CA542784A CA1302310C CA 1302310 C CA1302310 C CA 1302310C CA 000542784 A CA000542784 A CA 000542784A CA 542784 A CA542784 A CA 542784A CA 1302310 C CA1302310 C CA 1302310C
- Authority
- CA
- Canada
- Prior art keywords
- conduit
- plastic
- aperture
- extruded
- wire
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 229920003023 plastic Polymers 0.000 title claims abstract description 18
- 239000004033 plastic Substances 0.000 title claims abstract description 18
- 239000004020 conductor Substances 0.000 claims abstract description 19
- 238000001125 extrusion Methods 0.000 claims abstract description 15
- 238000000034 method Methods 0.000 claims abstract description 6
- 229920002457 flexible plastic Polymers 0.000 claims description 10
- 241000251468 Actinopterygii Species 0.000 abstract description 15
- 238000009434 installation Methods 0.000 description 3
- 229920000114 Corrugated plastic Polymers 0.000 description 1
- 239000004677 Nylon Substances 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
- H02G9/00—Installations of electric cables or lines in or on the ground or water
- H02G9/06—Installations of electric cables or lines in or on the ground or water in underground tubes or conduits; Tubes or conduits therefor
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
- H02G1/00—Methods or apparatus specially adapted for installing, maintaining, repairing or dismantling electric cables or lines
- H02G1/06—Methods or apparatus specially adapted for installing, maintaining, repairing or dismantling electric cables or lines for laying cables, e.g. laying apparatus on vehicle
- H02G1/08—Methods or apparatus specially adapted for installing, maintaining, repairing or dismantling electric cables or lines for laying cables, e.g. laying apparatus on vehicle through tubing or conduit, e.g. rod or draw wire for pushing or pulling
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
- H02G3/00—Installations of electric cables or lines or protective tubing therefor in or on buildings, equivalent structures or vehicles
- H02G3/02—Details
- H02G3/04—Protective tubing or conduits, e.g. cable ladders or cable troughs
- H02G3/0462—Tubings, i.e. having a closed section
- H02G3/0468—Corrugated
Landscapes
- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Extrusion Moulding Of Plastics Or The Like (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A plastic conduit with an integral pull wire avoids having to use a fish wire to pull electrical conductors through the conduit. An improved process of extruding plastic conduit comprises feeding a separate flexible wire or cord element through an aperture at the center of the plastic extruder die within the extruded conduit in the same direction and speed as the extruded conduit. An extrusion device has a plastic extrusion die with a central mandrel supported on transverse webs within the die exit, an aperture through one of the webs having a bend therein so the aperture exits at the center of the mandrel and in line with the die, feed rolls for the flexible wire or cord and speed control for the feed rolls to ensure the flexible wire or cord is fed at the same speed as the conduit is extruded.
A plastic conduit with an integral pull wire avoids having to use a fish wire to pull electrical conductors through the conduit. An improved process of extruding plastic conduit comprises feeding a separate flexible wire or cord element through an aperture at the center of the plastic extruder die within the extruded conduit in the same direction and speed as the extruded conduit. An extrusion device has a plastic extrusion die with a central mandrel supported on transverse webs within the die exit, an aperture through one of the webs having a bend therein so the aperture exits at the center of the mandrel and in line with the die, feed rolls for the flexible wire or cord and speed control for the feed rolls to ensure the flexible wire or cord is fed at the same speed as the conduit is extruded.
Description
~302310 PLASTIC CONDUIT WITES INTEGRAL PI~LL WIRE
The present invention relates to a plastic conduit with an integral pull wire. More specifically the present invention provides a plastic conduit for electrical conductors which has a pull wire placed inside the conduit during the manufacturing process to allow for easy insertion of conductors into a conduit after installation.
Flexible electrical conduits generally made of plastic, and in some cases corrugated plastic, are cut to size and fastened into place between junction and outlet boxes that have already been positioned and located.
Once the conduit is in place, then a relatively stiff wire called a fish wire, generally with a hook at the end, is pushed through the conduit between adjacent boxes. The electrical conductors or cables are then attached to the hook at the end of the fish wire that has been pushed through the conduit and the fish wire is then pulled from the other end. The electrical conductors are pulled by the fish wire and eased into the junction or outlet box. The fish wire is then pulled right through the conduit until the conductors emerge at the other box. The conductors are then disconnected from the fish wire and are ready for connection.
The pushing through of the fish wire is time consuming and at times difficult as the fish wire has to be fairly stiff in order to allow pushing it. At times the wire gets stuck at conduit bends. Furthermore, a fish wire is another piece of equipment which always has to be available and if one is not available, then time is wasted either to find a fish wire, or attempt to push conductors through the conduit.
It is an aim of the present invention to provide flexible plastic conduit which has a wire or cord in 1:~02310 place, thus eliminating the need for a fish wire and eliminating this step of inserting a fish wire through a conduit after installation.
The present invention provides a flexible plastic conduit for electrical conductors having a separate flexible wire or cord element extending through the center of the conduit for at least the length of the conduit for attachment to electrical conductors to be pulled through the conduit.
In another embodiment, there is provided in a process of extruding a flexible plastic conduit for electrical conductors from a plastic extruder die, the improvement comprising the steps of feeding a separate flexible wire or cord element through an aperture at the center of the plastic extruder die within the extruded conduit in the same direction as the extruding conduit at a feed speed corresponding to the extrusion speed of the conduit.
There is also provided an extrusion device for flexible plastic conduit comprising an extruder having a plastic extrusion die with a central mandrel supported on transverse webs within the die exit, an aperture extending through one of the webs and having a bend therein so the aperture exits at the approximate center of the central mandrel, extending in line with the extrusion die to feed a separate flexible wire or cord element through the aperture inside the extruded conduit r feed rolls for the flexible wire or cord element, and speed control means for the feed rolls to ensure the element is fed through the aperture at substantially the same speed as the conduit is extruded.
In a drawing which illustrates an embodiment of the invention, a cross sectional side elevation shows schematically an extruder die for extruding a plastic 1 30231~
conduit with feed rolls and an aperture in the central mandrel of the die to feed a separate flexible wire or cord element into the center of the conduit.
Referring now to the drawing, an extruder die 10 has an inlet 12 from the extruder which opens out to a circular exit 14. A central mandrel 16 is supported on at least two transverse webs 18. The central mandrel 16 forces the plastic to form a tube 19 when it leaves the die 10. As shown in the drawing, the tube 19 passes between two endless belts 20 which have semi-circular ridges therein. Air pressure is applied within the tube 19 to form a conduit 22 with corrugations therein.
An aperture 24 is provided in the central mandrel 16 extending through one of the transverse webs 18 and then having a bend therein so the aperture 24 exits at the center of the central mandrel 16 projecting in line with the conduit 22 as it is extruded. A cord or wire element 26 is passed through this aperture 24, the element 26 is provided from a coil 28 or other suitable storage means and passes through feed rolls 30 which feed the element 26 through the aperture 24. The feed roll speed is controlled to be the same speed as that of the conduit 22 being extruded through the extruder die 10.
The element 26 can be made of wire or may be a cord formed of nylon rope or other suitable material. It must be strong enough to pull cables and wires through a conduit. In one embodiment, the element is fed through the aperture 24 for a short time before commencing extrusion of the conduit 22 so that there is an extra length of element and then is also fed for a short time after the extrusion of the conduit ends, thus the element extends from both sides of a conduit pipe. In another embodiment the element extends for the length of the conduit pipe and when an electrician is installing the ~30Z3~0 conduit pipe he merely cuts a short piece off each end of the conduit to ensure that there is a sufficient length of wire or cord to attach to the electrical conductors and pull them through the conduit. Once the electrician has attached one end of the element 26 to the electrical conductors, he may then pull the other end and the conductors move through the conduit. This avoids the necessity of having to use a fish wire and makes the installation of electrical conductors and cables in a conduit a simpler matter that avoids the necessity of initially inserting a fish wire.
Various changes may be made to the embodiments described herein without departing from the scope of the present invention which is limited only by the following claims.
The present invention relates to a plastic conduit with an integral pull wire. More specifically the present invention provides a plastic conduit for electrical conductors which has a pull wire placed inside the conduit during the manufacturing process to allow for easy insertion of conductors into a conduit after installation.
Flexible electrical conduits generally made of plastic, and in some cases corrugated plastic, are cut to size and fastened into place between junction and outlet boxes that have already been positioned and located.
Once the conduit is in place, then a relatively stiff wire called a fish wire, generally with a hook at the end, is pushed through the conduit between adjacent boxes. The electrical conductors or cables are then attached to the hook at the end of the fish wire that has been pushed through the conduit and the fish wire is then pulled from the other end. The electrical conductors are pulled by the fish wire and eased into the junction or outlet box. The fish wire is then pulled right through the conduit until the conductors emerge at the other box. The conductors are then disconnected from the fish wire and are ready for connection.
The pushing through of the fish wire is time consuming and at times difficult as the fish wire has to be fairly stiff in order to allow pushing it. At times the wire gets stuck at conduit bends. Furthermore, a fish wire is another piece of equipment which always has to be available and if one is not available, then time is wasted either to find a fish wire, or attempt to push conductors through the conduit.
It is an aim of the present invention to provide flexible plastic conduit which has a wire or cord in 1:~02310 place, thus eliminating the need for a fish wire and eliminating this step of inserting a fish wire through a conduit after installation.
The present invention provides a flexible plastic conduit for electrical conductors having a separate flexible wire or cord element extending through the center of the conduit for at least the length of the conduit for attachment to electrical conductors to be pulled through the conduit.
In another embodiment, there is provided in a process of extruding a flexible plastic conduit for electrical conductors from a plastic extruder die, the improvement comprising the steps of feeding a separate flexible wire or cord element through an aperture at the center of the plastic extruder die within the extruded conduit in the same direction as the extruding conduit at a feed speed corresponding to the extrusion speed of the conduit.
There is also provided an extrusion device for flexible plastic conduit comprising an extruder having a plastic extrusion die with a central mandrel supported on transverse webs within the die exit, an aperture extending through one of the webs and having a bend therein so the aperture exits at the approximate center of the central mandrel, extending in line with the extrusion die to feed a separate flexible wire or cord element through the aperture inside the extruded conduit r feed rolls for the flexible wire or cord element, and speed control means for the feed rolls to ensure the element is fed through the aperture at substantially the same speed as the conduit is extruded.
In a drawing which illustrates an embodiment of the invention, a cross sectional side elevation shows schematically an extruder die for extruding a plastic 1 30231~
conduit with feed rolls and an aperture in the central mandrel of the die to feed a separate flexible wire or cord element into the center of the conduit.
Referring now to the drawing, an extruder die 10 has an inlet 12 from the extruder which opens out to a circular exit 14. A central mandrel 16 is supported on at least two transverse webs 18. The central mandrel 16 forces the plastic to form a tube 19 when it leaves the die 10. As shown in the drawing, the tube 19 passes between two endless belts 20 which have semi-circular ridges therein. Air pressure is applied within the tube 19 to form a conduit 22 with corrugations therein.
An aperture 24 is provided in the central mandrel 16 extending through one of the transverse webs 18 and then having a bend therein so the aperture 24 exits at the center of the central mandrel 16 projecting in line with the conduit 22 as it is extruded. A cord or wire element 26 is passed through this aperture 24, the element 26 is provided from a coil 28 or other suitable storage means and passes through feed rolls 30 which feed the element 26 through the aperture 24. The feed roll speed is controlled to be the same speed as that of the conduit 22 being extruded through the extruder die 10.
The element 26 can be made of wire or may be a cord formed of nylon rope or other suitable material. It must be strong enough to pull cables and wires through a conduit. In one embodiment, the element is fed through the aperture 24 for a short time before commencing extrusion of the conduit 22 so that there is an extra length of element and then is also fed for a short time after the extrusion of the conduit ends, thus the element extends from both sides of a conduit pipe. In another embodiment the element extends for the length of the conduit pipe and when an electrician is installing the ~30Z3~0 conduit pipe he merely cuts a short piece off each end of the conduit to ensure that there is a sufficient length of wire or cord to attach to the electrical conductors and pull them through the conduit. Once the electrician has attached one end of the element 26 to the electrical conductors, he may then pull the other end and the conductors move through the conduit. This avoids the necessity of having to use a fish wire and makes the installation of electrical conductors and cables in a conduit a simpler matter that avoids the necessity of initially inserting a fish wire.
Various changes may be made to the embodiments described herein without departing from the scope of the present invention which is limited only by the following claims.
Claims (8)
1. A flexible plastic conduit for electrical conductors having a separate flexible wire or cord element extending through the center of the conduit for at least the length of the conduit for attachment to electrical conductors to be pulled through the conduit.
2. The flexible plastic conduit according to Claim 1 wherein an additional length of flexible wire or cord element is provided at each end of the conduit.
3. In a process of extruding a flexible plastic conduit for electrical conductors from a plastic extruder die, the improvement comprising the steps of, feeding a separate flexible wire or cord element through an aperture at the center of the plastic extruder die within the extruded conduit in the same direction as the extruded conduit at a feed speed corresponding to the extrusion speed of the conduit.
4. The process according to Claim 3 wherein the flexible plastic conduit has corrugations formed thereon immediately after being extruded.
5. The process according to Claim 3 wherein additional lengths of the separate flexible wire or cord element are fed through the aperture at the center of the plastic extrusion die prior to extruding the conduit and after extruding the conduit.
6. A flexible plastic conduit for electrical conductors having a separate flexible wire or cord element extending through the centre of the conduit for at least the length of the conduit, made by the process according to Claim 3.
7. An extrusion device for flexible plastic conduit comprising, an extruder having a plastic extrusion die with a central mandrel supported on transverse webs within the die exit, an aperture extending through one of the webs having a bend therein so the aperture exits at the approximate center of the central mandrel, extending in line with the extrusion die to feed a separate flexible wire or cord element through the aperture inside the extruded conduit, feed rolls for the flexible wire or cord element, and speed control means for the feed rolls to ensure the element is fed through the aperture at substantially the same speed as the conduit is extruded.
8. The extrusion device according to Claim 7 including corrugation former means positioned after the extrusion die.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000542784A CA1302310C (en) | 1987-07-22 | 1987-07-22 | Plastic conduit with integral pull wire |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000542784A CA1302310C (en) | 1987-07-22 | 1987-07-22 | Plastic conduit with integral pull wire |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1302310C true CA1302310C (en) | 1992-06-02 |
Family
ID=4136125
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000542784A Expired - Lifetime CA1302310C (en) | 1987-07-22 | 1987-07-22 | Plastic conduit with integral pull wire |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1302310C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016169765A1 (en) * | 2015-04-24 | 2016-10-27 | Kromberg & Schubert Gmbh | Apparatus and method for producing a power chain |
-
1987
- 1987-07-22 CA CA000542784A patent/CA1302310C/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016169765A1 (en) * | 2015-04-24 | 2016-10-27 | Kromberg & Schubert Gmbh | Apparatus and method for producing a power chain |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |