EP0003673A1 - Powder pushing device for filling cable - Google Patents

Abstract

A device for filling the interstices of multistranded cable with powder, comprising an outer cylindrical housing (12) and a concentric inner tube (14) with a closed annular chamber between them. A hopper (32) opens into the chamber and the chamber opens into the tube. A feeder (22) in the chamber pushes the powder from the opening (34) of the hopper to the opening (20) into the tube.

Description

• This invention relates to the production of multi-strand electrical cables and more particularly to filling the interstices of such cables with powder.
• Multi-stranded electrical cables are filled with powder for water blockage. A powder filling for this purpose is described in United States Patent No. 4,002,819 issued llth January 1977 to Northern Telecom Limited assignee of Leo. V. Woytiuk. One method of filling the interstices of the cable is by_passing the cable core through an electrostatic powder chamber as described in United States Patent No. 4,100,002 issued llth July 1978 in the name of Leo V. Woytiuk assignor to Northern Telecom Limited. Such a method is relatively difficult to operate to obtain fine adjustments in the amount of powder filling placed within the interstices of the cable, i.e. the percentage of voids filled by the powder.
• It is an object of the present invention to provide an improved method and apparatus for powder filling a multi-stranded cable.
• The invention consists of a device for filling the interstices of multi-stranded cable with powder, comprising: a cylindrical housing; a tube concentric with the housing and spaced inwardly therefrom to form an annular chamber, the tube flaring outwardly at the inlet end thereof, the chamber being closed at each end thereof and opening annularly into the tube adjacent said inlet end; powder feeding means opening into the housing; and means to move powder from the hopper opening to the annular opening and therethrough into the tube.
• Example embodiments of the invention are shown in the accompanying drawings in which:
• Figure 1 is a side view in cross-section of a device for powder filling a cable;
• Figure 2 is a view similar to Figure 1 showing one alternative embodiment of the device;
• Figure 3 is a view similar to Figure 1, with the cable omitted, showing another alternative embodiment of the device; and
• Figure 4 is a cross-sectional view taken along line 4-4 of Figure 3.
• The example embodiment shown in Figure 1 of the drawings consists of acable filling device 10 having acylindrical housing 12 and acoaxial tube 14 spaced inwardly from the housing to provide anannular chamber 16. Tube 14 flares outwardly adjacent itsinlet end 18 to meet the end ofhousing 12 and to close one end ofchamber 16. A circumferential row of parallel, spacedslots 20 is located intube 14adjacent inlet end 18.
• Ahelical screw member 22 is located inchamber 16 with one end terminatingadjacent slots 20. The end ofscrew 22 remote fromslots 20 is fixed to anannular hub 24 of a great 26 which is coaxial withhousing 12 andtube 14.Gear 26 meshes with adrive gear 28.Hub 24closes chamber 16 at theoutlet end 30 oftube 14 and the hub is freely rotatable axially on the tube. Powder feeding means in the form of ahopper 32 is mounted onhousing 12 and opens laterally intochamber 16adjacent hub 24 through anaperture 34 in the housing.
• In the operation of the example embodiment shown in Figure 1 acore 40 is continuously fed axially throughtube 14 frominlet end 18 tooutlet end 30 of the tube. At the same time a number ofconductors 42 are fed intoinlet end 18 oftube 14, for example from a multi-cage strander, and spirally wound oncore 40. Apowder mixture 43 of predetermined blend is passed in a continuous flow, or as needed, intohopper 32 from aninlet conduit 44. The powder fromhopper 32 passes throughaperture 34 inhousing 12 intochamber 16 and is carried forward in the chamber by the axial rotation ofhelical screw 22 which is driven bygear 28 throughgear 26. As the powder mixture reaches the end portion ofchamber 16adjacent inlet end 18 oftube 14 it passes throughslots 20 in the tube and ontocore 40. The lateral movement ofconductors 42 as they are wound aboutcore 40 assists in the movement of the powder against the core.
• The amount of powder applied tocore 40 is governed by the speed of travel of the core, the size ofslots 20, the speed of axial rotation ofhelical screw 22 and the pitch of the screw. The application of the powder tocore 40 is aided bysloping slots 22 with respect to the axial plane oftube 14 and in the direction of the slope ofconductors 42 as seen in Figure 1.
• In the alternative example embodiment of the device shown in Figure 2 of thedrawings slots 20 intube 14 of the previous example embodiment are replaced by anannular opening 50 which allows greater access of powder fromchamber 16 onto core 40 (tube 14 would be suitably supported by bars not shown). Also,hopper 32 of the previous embodiment is modified to provide a fluidized bed of powder. In the embodiment of Figure 2 ahopper 60, opening ontohousing 12 through an aperture 61, has aporous side wall 62 circumscribed by anannular housing 64 forming aplenum chamber 66 with anair inlet 68.Side wall 62 is connected with a vibrator indication schematically bynumeral 70.
• In the operation of the embodiment of Figure 2 powder flows intohopper 60 from a conduit 72, either continuously or intermittently as required to keep the hopper filled. Air is introduced under pressure throughinlet 68 and passes fromplenum chamber 66 throughporous wall 62 intohopper 60. At thesame time hopper 60 is oscillated byvibrator 70 and powder within the hopper forms a fluidizedbed 74. This activated state of the powder mixture facilitates its movement throughchamber 16 and ontocore 40.
• In Figures 3 and 4 the further alternative embodiment consists of atube 80 flaring outwardly at itsinlet end 82 with a circumferential row of parallel, spacedslots 84 located in the wall of the tube adjacent its inlet end. Acircular housing 86circumscribing tube 80adjacent inlet end 82 defines achamber 88 which contains aspiral feeder 90 fixed on anend plate 92 having acollar 94 projecting outside the housing and carrying anannular gear 96 engagable with adrive gear 98. Ahopper 100 opens through anaperture 102 inhousing 86 intochamber 88. As in the previous embodiment,hopper 100 has aporous side wall 104 circumscribed by anannular housing 106 forming aplenum chamber 108 with aninlet 110.Side wall 104 is connected with avibrator 112.
• In the operation of the embodiment shown in Figures 3 and 4 powder is introduced intohopper 100 through aconduit 114 as required to keep the hopper filled.Vibrator 112 oscillateshopper 100 and air under pressure enters throughporous wall 104 to form a fluidizedbed 116 of powder in the hopper. As a core passes intotube 80 throughinlet 82 together with a plurality of strands to wrap the core,spiral feeder 90 is rotated bydrive gear 98. To clarify the structure of Figures 3 and 4 the core and strands have been omitted but they pass throughtube 80 in the same manner as in the previously described embodiments. Powder fromhopper 100 passing throughaperture 102 ofhousing 86 intochamber 88 is picked up byfeeder 90 and moved towardsslots 84 as the spiral feeder rotates, finally being forced throughslots 84 onto the core withintube 80.
• It will be appreciated that the core and strands shown in Figures 1 and 2 of the drawings are only illustrative and other types of multi-stranded cable may be powder filled by the device of the invention.
• It will also be appreciated that types of mechanisms for drivinghelical screw 22 may be employed other than meshinggears 26 and 28, for example a worm gear and screw, a belt and pulley, or a chain and sprocket may be used.

Claims (10)

1. A device for filling the interstices of multi-stranded cable with powder, characterised by:

a cylindrical housing (12);

a tubular passageway (14) within the housing, at least part of which forms together with the housing an annular chamber (16), the passageway flaring outwardly at the inlet end (18) thereof, the chamber opening into the passageway adjacent said inlet end at at least a plurality of points (20) spaced around the passageway;

powder feeding means (32) opening into the housing; and

means (22) to move powder from the powder feeding means to the openings or opening and therethrough into the passageway.

2. A device as claimed in claim 1 characterised in that the powder feeding means comprisies a hopper (32).

3. A device as claimed in claim 1 characterised in that the hopper includes vibrator means (70) on air inflow means (52,64,68) to form a fluidized bed of powder therein.

4. A device as claimed in claim 1 characterised in that the means to move the powder comprises a helical screw member (22) concentrically mounted within the chamber, and means (24,26) to rotate the screw member.

5. A device as claimed in claim 4 characterised in that the means to rotate the screw member comprises a hub (24) having one end of the screw member fixed thereto, the hub projecting from the housing, and a gear (26) fixed to the hub outside the housing.

6. A device as claimed in claim 5 characterised in that the outwardly flaring passageway meets the housing to close one end of the chamber and the hub closes the other end of the chamber.

7. A device as claimed in claim 1 characterised in that the means to move the powder comprises a spiral feeder (90) concentrically mounted in the housing, and means (94,96) to rotate the spiral feeder axially.

8. A device as claimed in claim 7 characterised in that the means to rotate the spiral feeder comprises a hub (94r having the spiral feeder fixed thereto, the hub projecting from the housing, and a gear (96) fixed to the housing outside the hub.

9. A device as claimed in claim 1 characterised in that the chamber opens into the passageway through an annular ring of spaced slots (20).

10. A device as claimed in claim 9 characterised in that the slots are straight and positioned at an angle to a plane containing the axis of the passageway.

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