GB2024278A

GB2024278A - Fluidized powder filling of cables

Info

Publication number: GB2024278A
Application number: GB7920889A
Authority: GB
Original assignee: Northern Telecom Ltd
Current assignee: Nortel Networks Ltd
Priority date: 1978-06-28
Filing date: 1979-06-15
Publication date: 1980-01-09
Also published as: CA1072729A; FI791920A; FR2430072B1; GB2024278B; SE445864B; BE877345A; JPS556594A; SE7905457L; ES481973A1; IT7923575A0; FI71628C; CH636726A5; BR7903808A; DK248379A; FI71628B; NL7904959A; IT1121397B; DE2925931A1; FR2430072A1; AU4789479A

Abstract

The conductors of a cable are powder filled by passing the cable through a fluidized bed of powder in a substantially closed condition. The filled cable can be wrapped with tape after exit from the fluidized bed. <IMAGE>

Description

SPECIFICATION Fluidized powder filling of cables This invention relates to the fluidized powderfilling of cables, to the apparatus therefore and to a cable filled by such a method.

Powder filled cables are well known, the powder being applied to the cable in an "open" form, that is with the individual conductors spaced apart so that powder can be applied, as by blowing or otherwise expelling the powder.

Various problems exist with the known ways of filling a cable, one of which is the obtaining uniformity of fill. It is important, in multilayer cables for example,thatfilling be uniform as variation from layer to layer causes variation in the electrical characteristics of the various layers. For telecommunications cables this is at least very undesirable, and in many instances unacceptable.

The present invention comprises filling a multiconductor cable by passing the cable through a fluidized bed of the filling powder, the cable being in a substantially closed condition before entering the fluidized bed.

The invention will be readily understood by the following description of a process and the related apparatus, in conjunction with the accompanying diagrammatic drawings, in which:- Figure 1 illustrates, in side view, a form of apparatus; Figure 2 illustrates in diagrammatic cross-section a cable entering and passing through the apparatus; Figure 3 is a perspective view of one form of apparatusforfilling two cables.

As illustrated in Figure 1, the apparatus comprises a main box or housing 10 having a top portion 11, an air box 12 at the bottom, an air inlet 13, a dust extraction outlet at 14 and a powder inlet 15. At an inlet end of the box 10 there is an inlet die 16 and at the other end of the box is an outlet die 17. The air box 12 is separated from the main box 10 by a porous plate 18.

In operation, powder is filled into the box 10, via inlet 15 and pressurized air is supplied to the air box 12 via the air inlet 13. The air passes through the porous plate 18 and fluidizes the powder in the box 10, as indicated at 19. A certain amount of dust is created and this is extracted through the dust outlet 14.

Prior to filling the box with powder the conductors of a cable are fed through the inlet and outlet dies 16 and 17. As illustrated in Figure 1 the conductors of the cable, at 20 are fed through a preforming guide 21 and then formed into cable form as they pass through the inlet die 16. An initial length of formed conductors is fed through the box 10 and out through the outlet die 17. The formed conductors can then be attached to a suitable lead member for connected to a pulling and take-up mechanism.

Once the conductors are through the box it can be closed, powder fed in and the fluidizing air supply switched on. The conductors are then pulled through the box. As the conductors exit from the box, through exit die 17, they are wrapped in a core wrapping tape 25, by a former 26. In the particular example the former 26 comprises a tapered or conical-entry portion 27 and a parallel portion 28.

The former forms, or wraps, the wrapping tape 25 round the conductors 20, preventing loss of filling medium.

The conductors 20 can be separate, individual conductors or, for telecommunications cables, may comprise pairs of conductors twisted together. The conductors are fed into the box 10 via the inlet die 16, in a substantially closed condition. Some slight spacing between conductors can occur, such as may occur due to slight opening of the conductors after exiting from the inlet die 16, but such opening is minimal. The degree of spacing can be varied, as by varying slightly the bore of the inlet die 16 to vary the amount of filling. Surprisingly, although the conductors are in a substantially closed condition, with probably several layers of conductors, uniform and complete filling is obtained, for cables of quite a large number of conductors. For example, satisfactory filling is obtained for a cable unit of 50 pairs of conductors.The path of the conductors through the box 10 is illustrated in Figure 2.

Figure 3 illustrates a typical form of apparatus for filling two cable cores, in the particular example each of twenty-five pairs of conductors. Two boxes 10 are situated side by side with a common powder supply 40. In the example illustrated rotary oscillating face-plates 41 are provided at the inlet dies to reciprocate or oscillate the conductors as they pass through the boxes. The supply of powder is controlled to maintain a substantially constant bed thickness. In an alternate arrangement, not shown, a plurality of cable cores can be passed through a common bed.

The apparatus is relatively inexpensive, simple and very effective. The process results in uniformly filled cable cores, the filling being controlled and variable as desired. The cable has uniform electrical characteristics.

CLAIMS:

1. A method of powder filling a multiconductor cable core comprising passing the cable core through a fluidized bed of filling powder, the cable core being in a substantially closed condition before entering thefluidized bed.

2. A method as claimed in claim 1, including wrapping the core in a tape on exit from the fluidized bed.

3. A method as claimed in claim 1 or 2, including supplying powder to the fluidized bed art a rate to maintain a substantially constant bed thickness.

4. A method as claimed in claim 1,2 or 3, including oscillating the conductors as they pass through the housing.

5. Apparatus for powder filling a multiconductor cable, comprising: a housing having a bottom and inlet and outlet ends; at least one inlet at the inlet end of the housing for entry of a cable core having a multiplicity of conductors, the inlet of a size to retain the core in a substantially closed condition; an outlet at the outlet end of the housing for exit of the cable

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Fluidized powder filling of cables This invention relates to the fluidized powderfilling of cables, to the apparatus therefore and to a cable filled by such a method. Powder filled cables are well known, the powder being applied to the cable in an "open" form, that is with the individual conductors spaced apart so that powder can be applied, as by blowing or otherwise expelling the powder. Various problems exist with the known ways of filling a cable, one of which is the obtaining uniformity of fill. It is important, in multilayer cables for example,thatfilling be uniform as variation from layer to layer causes variation in the electrical characteristics of the various layers. For telecommunications cables this is at least very undesirable, and in many instances unacceptable. The present invention comprises filling a multiconductor cable by passing the cable through a fluidized bed of the filling powder, the cable being in a substantially closed condition before entering the fluidized bed. The invention will be readily understood by the following description of a process and the related apparatus, in conjunction with the accompanying diagrammatic drawings, in which:- Figure 1 illustrates, in side view, a form of apparatus; Figure 2 illustrates in diagrammatic cross-section a cable entering and passing through the apparatus; Figure 3 is a perspective view of one form of apparatusforfilling two cables. As illustrated in Figure 1, the apparatus comprises a main box or housing 10 having a top portion 11, an air box 12 at the bottom, an air inlet 13, a dust extraction outlet at 14 and a powder inlet 15. At an inlet end of the box 10 there is an inlet die 16 and at the other end of the box is an outlet die 17. The air box 12 is separated from the main box 10 by a porous plate 18. In operation, powder is filled into the box 10, via inlet 15 and pressurized air is supplied to the air box 12 via the air inlet 13. The air passes through the porous plate 18 and fluidizes the powder in the box 10, as indicated at 19. A certain amount of dust is created and this is extracted through the dust outlet 14. Prior to filling the box with powder the conductors of a cable are fed through the inlet and outlet dies 16 and 17. As illustrated in Figure 1 the conductors of the cable, at 20 are fed through a preforming guide 21 and then formed into cable form as they pass through the inlet die 16. An initial length of formed conductors is fed through the box 10 and out through the outlet die 17. The formed conductors can then be attached to a suitable lead member for connected to a pulling and take-up mechanism. Once the conductors are through the box it can be closed, powder fed in and the fluidizing air supply switched on. The conductors are then pulled through the box. As the conductors exit from the box, through exit die 17, they are wrapped in a core wrapping tape 25, by a former 26. In the particular example the former 26 comprises a tapered or conical-entry portion 27 and a parallel portion 28. The former forms, or wraps, the wrapping tape 25 round the conductors 20, preventing loss of filling medium. The conductors 20 can be separate, individual conductors or, for telecommunications cables, may comprise pairs of conductors twisted together. The conductors are fed into the box 10 via the inlet die 16, in a substantially closed condition. Some slight spacing between conductors can occur, such as may occur due to slight opening of the conductors after exiting from the inlet die 16, but such opening is minimal. The degree of spacing can be varied, as by varying slightly the bore of the inlet die 16 to vary the amount of filling. Surprisingly, although the conductors are in a substantially closed condition, with probably several layers of conductors, uniform and complete filling is obtained, for cables of quite a large number of conductors. For example, satisfactory filling is obtained for a cable unit of 50 pairs of conductors.The path of the conductors through the box 10 is illustrated in Figure 2. Figure 3 illustrates a typical form of apparatus for filling two cable cores, in the particular example each of twenty-five pairs of conductors. Two boxes 10 are situated side by side with a common powder supply 40. In the example illustrated rotary oscillating face-plates 41 are provided at the inlet dies to reciprocate or oscillate the conductors as they pass through the boxes. The supply of powder is controlled to maintain a substantially constant bed thickness. In an alternate arrangement, not shown, a plurality of cable cores can be passed through a common bed. The apparatus is relatively inexpensive, simple and very effective. The process results in uniformly filled cable cores, the filling being controlled and variable as desired. The cable has uniform electrical characteristics. CLAIMS:

5. Apparatus for powder filling a multiconductor cable, comprising: a housing having a bottom and inlet and outlet ends; at least one inlet at the inlet end of the housing for entry of a cable core having a multiplicity of conductors, the inlet of a size to retain the core in a substantially closed condition; an outlet at the outlet end of the housing for exit of the cable core in a closed condition; and a porous member at the bottom of the housing and means for feeding air through the porous member to fluidize powder in the housing and surround the cable core with the fluidized powder.

6. Apparatus as claimed in claim 5, including an air box attached to the bottom of the housing, the means for feeding air including air supply means to the air box, the porous member extending between the air box and the housing.

7. Apparatus as claimed in claim 5 or 6, including a top portion on the housing and dust extraction means connected to the top portion.

8. Apparatus as claimed in claim 5, 6 or 7, including wrapping means adjacent to the outlet for wrapping a tape around the cable on exit through the outlet.

9. Apparatus as claimed in any one of claims 5 to 8, including a performing member positioned in front of the entry for preforming of the conductors prior to entry.

10. Apparatus as claimed in any one of claims 5 to 9, including an oscillating member at said inlet for oscillating the conductors as they pass through the housing.

11. A method of powder filling a multi-conductor cable core substantially as hereinbefore described.

12. Apparatus for powderfilling a multiconductor cable substantially as hereinbefore described with reference to the accompanying drawings.