GB2163912A

GB2163912A - Cartridge fuse manufacture

Info

Publication number: GB2163912A
Application number: GB08521452A
Authority: GB
Inventors: Kenneth Baty; Alexander Donald Guthrie
Original assignee: Dorman Smith Fuses Ltd
Current assignee: Dorman Smith Fuses Ltd
Priority date: 1984-08-31
Filing date: 1985-08-29
Publication date: 1986-03-05
Also published as: GB8521452D0; GB8422075D0; GB2163912B

Abstract

In an automatic method of manufacturing a cartridge fuse comprising a rigid tube 2, a fusible element 3 electrically connected to terminals comprising an apertured inner cap 6 and an outer cap and optional arc-quenching material 5, a fusible element 3 is cut from an advancing strip 10 of metal and is fed lengthwise of the element into the rigid tube 2 through an aperture in an inner cap 6 fitted at one end of the body until the element 3 is in contact with or adjacent to both the inner caps. The fusible element 3 is electrically connected to both of the inner caps 6, and outer caps 8 are then electrically connected to the inner caps. A disc of arc-quenching material may be inserted between the inner and outer caps. <IMAGE>

Description

SPECIFICATION Cartridge fuse manufacture This invention relates to cartridge fuses of the kind comprising a substantially rigid tube of electrically insulating material fitted at each of its ends with a terminal of metal or metal alloy and containing at least one fusible element extending between and electrically connected to the terminals, the tube usually, but not necessarily, being filled with an arc-quenching material, such as sand.

The invention is particularly concerned with car tridge fuses of the aforesaid kind in which the terminal at each end of the substantially rigid tube comprises an inner cap of metal or metal alloy which fits over the end of the rigid tube and which has an aperture in its end wall and, overlying and electrically connected-to the inner cap, an outer cap of metal or metal alloy whose end wall is axially spaced from the apertured end wall of the inner cap. In some circumstances, the space between the apertured end wall of the inner cap and the end wall of the outer cap of each terminal may house a disc made of or impregnated with an arcinhibiting material.

Cartridge fuses whose terminals comprise inner and outer caps as hereinbefore described will, for convenience, hereinafter be referred to as "cartridge fuses of the kind described".

It is an object of the present invention to provide an improved method of manufacturing a cartridge fuse of the kind described, which method can be effected automatically.

According to the invention, the improved method comprises the steps of: (i) feeding a strip of metal or metal alloy from which fusible elements are to be formed in the direction of its length towards a fusible element forming station; (ii) transversely cutting or otherwise forming a fusible element from the leading end of the advancing strip at said fusible element forming station; (iii) transferring the fusible element so formed in the direction of its length towards a fusible element loading station at which is supported a substantially rigid tube of electrically insulating material having secured to each of its ends an apertured inner cap of metal or metal alloy;; (iv) feeding the advancing fusible element lengthwise into one end of the substantially rigid tube until the leading end of the fusible element is in contact with or is adjacent to the inner cap at the remote end of the tube and the trailing end of the fusible element is in contact with or is adjacent to the inner cap at the nearer end of the tube; (v) and permanently electrically connecting the ends of the fusible element to the inner caps.

After the fusible element has been permanently electrically connected to the inner caps, the substantially rigid tube with the inner caps secured thereto may be discharged from the fusible element loading station and fed to a capping station where outer caps of metal or metal alloy are permanently electrically connected over the inner caps; if desired, a disc made of or impregnated with an arc-inhibiting material may be introduced between the end faces of the inner and outer caps of each terminal.

Where the substantially rigid tube is to be filled with sand or other arc-quenching material, such material can be introduced into the tube after the first of the two outer caps has been permanently electrically connected to the inner cap at one end of the tube.

Preferably, to facilitate effecting permanent electrical connection of the fusible element to the apertured inner caps at the loading station, the width of the strip of fusible element material from which the fusible element is cut and formed is such that end parts of the fusible element will protrude outwardly through the apertures in the inner caps when the fusible element is positioned in the substantially rigid tube and, before effecting permanent electrical connection of the fusible element to each inner cap, the protruding end portion of the fusible element is folded or bent over against the outer end surface of the inner cap.

Preferably, also, the device for effecting permanent electrical connection between each protruding end part of the fusible element and its associated inner end cap is so located with respect to apparatus supporting the substantially rigid tube at the fusible element loading station, that it will be immediately adjacent the inner end cap which is remote from the fusible element forming station and after the device has been employed to effect permanent electrical connection between the protruding end portion of the fusible element and the associated inner end cap remote from the fusible element forming station, the substantially rigid tube is caused to rotate 189' about an axis extending transversely through the longitudinal axis of the tube so that the said device can then effect permanent electrical connection between the protruding end part of the fusible element and the associated inner cap at the other end of the tube.

Permanent electrical connection between the protruding end portions of the fusible element and the associated inner caps preferably is effected by spot welding or by soldering.

Where a cartridge fuse of the kind described has two or more fusible elements housed in the substantially rigid tube and electrically connected at circumferentially spaced positions to the inner caps, preferably after the first of said fusible elements has been fed into the substantially rigid tube and permanently electrically connected to its inner end caps, the substantially rigid tube is caused to effect partial rotation about its longitudinal axis to provide for introduction of a second fusible element into the substantially rigid tube, and so on.

The invention also includes a cartridge fuse manufactured by the improved method hereinbefore described.

The invention further includes apparatus for manufacturing a cartridge fuse of the kind described by the improved method herein before de scribed. The invention is further illustrated by a description, by way of example, of a preferred method of manufacturing a cartridge fuse of the kind described with reference to the accompanying drawings in which: Figure 1 shows a cross-sectional side view of a cartridge fuse of the kind described, and Figure 2 shows in schematic form the preferred method of manufacturing the cartridge fuse shown in Figure 1.

The cartridge fuse 1 shown in Figure 1 comprises a rigid tube 2 of electrically insulating material and a fusible element 3 which extends between and is electrically connected to terminals 4 at the ends of the rigid tube. The rigid tube is filled with sand 5. Each terminal 4 comprises an inner cap 6 of metal fitted over an end of the rigid tube 2 and having an aperture 7 in its end wall, an outer cap 8 of metal fitted over inner cap 6 so that, its end wall is axially spaced from the apertured end wall of the inner cap, and a disc 9 of arc inhibiting material housed in the space between the inner and outer caps.

Referring to Figure 2, the cartridge fuse shown in Figure 1 is manufactured by a method which comprises feeding a strip 10 of metal in the direction of its length to a fusible element forming station 11 where a fusible element 3 is transversely cut from the leading end 12 of the strip. The fusible element 3 is transferred in the direction of its length to a fusible element loading station 13 at which is supported a rigid tube 2 of electrically insulating material having secured to each of its ends an inner metal cap 6 having an aperture 7 in its end wall.

The fusible element 3 is fed lengthwise into one end of the rigid tube 2 so that end parts 15, 16 of the fusible element protrude outwardly through the apertures 7 in the inner caps 6 Once the fusible element 3 is positioned in the tube 2 the end part 15 of the fusible element 3 is bent against the outer surface of the inner cap 6, and spot welded to this surface by spot welding apparatus 18 to effect permanent electrical connection. The tube 2 and fusible element 3 therein are then caused to rotate through 180 about an axis extending transversely through the mid-part of the fuse and permanent electrical connection between the protruding end 16 of the fusible element 3 and the associated inner cap 6 is effected as before.

The tube 2 is discharged from the fusible element loading station 13 and fed to a capping station 19 at which a disc 9 of arc-quenching material is applied over the inner cap 6 at one end of the fuse body, and an outer cap 8 is permanently electrically connected to the inner cap at this end. The tube 2 is then filled with sand 5 through the apertured end wall of the inner cap 6 at the other end and a disc of arc-quenching material is applied over the inner cap and outer cap 8 is permanently electrically connected to the inner cap.

After the tube 2 has been discharged from the fusible element loading station 13 and fed to the capping station 19, another tube 2 with inner caps 6 secured to its ends is fed to the fusible element loading station from a source of supply 17.

All the operations of the method described with reference to Figure 2 are effected automatically in the required sequence.

Claims

1. A method of manufacturing a cartridge fuse of the kind described which comprises the steps of (i) feeding a strip of metal or metal alloy from which fusible elements are to be formed in the direction of its length towards a fusible element forming station; (ii) transversely cutting or otherwise forming a fusible element from the leading end of the advancing strip at said fusible element forming station; (iii) transferring the fusible element so formed in the direction of its length towards a fusible element loading station at which is supported a substantially rigid tube of electrically insulating material having secured to each of its ends an apertured inner cap of metal or metal alloy;; (iv) feeding the advancing fusible element lengthwise into one end of the substantially rigid tube until the leading end of the fusible element is in contact with or is adjacent to the inner cap at the remote end of the tube and the trailing end of the fusible element is in contact with or is adjacent to the inner cap at the nearer end of the tube; (v) and permanently electrically connecting the ends of the fusible element to the inner caps.

2. A method of manufacturing a cartridge fuse as claimed in Claim 1, wherein, to facilitate effecting permanent electrical connection of the fusible element to the apertured inner caps at the loading station, the width of the strip of fusible element material from which the fusible element is cut and formed is such that end parts of the fusible ele-ment protrudes outwaidly through the apertures in the inner caps when the fusible element is positioned in the substantially rigid tube and, before effecting permanent electrical connection of the fusible element to each inner cap, the protruding end portion of the fusible element is folded or bent over against the outer end surface of the inner cap.

3. A method of manufacturing a cartridge fuse as claimed in Claim 2, wherein the device for effecting permanent electrical connection between each protruding end part of the fusible element and its associated inner end cap is so located with respect to apparatus supporting the substantially rigid tube at the fusible element loading station, that it will be immediately adjacent the inner end cap which is remote from the fusible element forming station and after the device has been employed to effect permanent electrical connection between the protruding end portion of the fusible element and the associated inner end cap remote from the fusible element forming station, the substantially rigid tube is caused to rotate 180 about an axis extending transversely through the longitudinal axis of the tube so that the said device can then effect permanent electrical connection between the protruding end part of the fusible element and the associated inner cap at the other end of the tube.

4. A method of manufacturing a cartridge as claimed in any one of the preceding Claims, wherein permanent electrical connection between the protruding end portions of the fusible element and the associated inner caps is effected by spot welding or by soldering.

5. A method of manufacturing a cartridge fuse as claimed in any one of the preceding Claims in which the cartridge fuse has two or more fusible elements housed in the substantially rigid tube and electrically connected at circumferentially spaced positions to the inner caps, wherein, after the first of said fusible elements has been fed into the substantially rigid tube and permanently electrically connected to its inner end caps, the substantially rigid tube is caused to effect partial rotation about its longitudinal axis to provide for introduction of a second fusible element into the substantially rigid tube, and so on.

6. A method of manufacturing a cartridge fuse as claimed in any one of the preceding Claims, wherein, after the fusible element has been permanently electrically connected to the inner caps, the substantially rigid tube with the inner caps secured thereto is discharged from the fusible element loading station and fed to a capping station where outer caps of metal or metal alloy are permanently electrically connected over the inner caps.

7. A method of manufacturing a cartridge fuse as claimed in any one of the preceding Claims, wherein a disc made of or impregnated with an arc-inhibiting material is introduced between the end faces of the inner and outer caps of each terminal.

8. A method of manufacturing a cartridge fuse as claimed in any one of the preceding Claims in which the substantially rigid tube is to be filled with sand or other arc-quenching material, wherein such material is introduced into the tube after the first of the two outer caps has been permanently electrically connected to the inner cap at one end of the tube.

9. A method of manufacturing a cartridge fuse substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.

10. A cartridge fuse manufactured by the method of manufacture claimed in any one of the preceding Claims.

11. Apparatus for manufacturing a cartridge fuse of the kind described by the method of manufacture substantially as herein before described and as shown in Figure 2 of the accompanying drawings.