US3484856A - Anode adjusting apparatus - Google Patents

Description

Dec. 16, 1969 M. A. BQGANTES 3,484,856

ANODE ADJUSTING APPARATUS Filed July 21, 1966 4 Sheets-Sheet 1 INVENTOR MARCO A. BOGNTES ATTORNEY Dec 16, 1969 M. A. BoGANTEs 3,484,856

ANODE ADJUSTING APPARATUS 4 Sheets-Shree?l 2 Filed July 21, 1966 INVENTOIR MARCO BOGANTES "Y ZZ:

ATTORNEY Dec. 16. 1969 M. A. aoGANrEs' 3,434,856 l ANonE ADJusTING APPARATUS Filmv July 21, 195e l 4 sheets-sheet s e Z LUI n.1... I.. u n

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Dec- 16. 1969 M. A..BOGANTES ANODE ADJUSTING APPARATUS 4 Sheets-Sheet 4 Filed July 21, 1966 IIlIIlIIlI-a lilllllll INVENTOR MARCO A. BOGANTES v ATTORNEY United States Patent O 3,484,856 ANODE ADJUSTING APPARATUS Marco A. Bogantes, Oakland, Calif., assignor to Kaiser Aluminum & Chemical Corporation, Oakland, Calif., a corporation of Delaware Filed July 21, 1966, Ser. No. 566,928 Int. Cl. C23b 5/ 70 U.S. Cl. 204-297 12 Claims ABSTRACT OF THE DISCLOSURE An auxiliary apparatus for supporting the anodes of an electrolytic cell for the production of aluminum and maintaining current flow therein during the position adjustment of the cell anode bus bar mounted on the anode supporting superstructure of the cell.

This invention relates to electrolytic cells employing electrodes supported by individual bars or rods of conductor material suspended from one or more cell anode bus bars. More particularly, this invention concerns a novel system for supporting the anodes of an electrolytic cell for the production of aluminum and maintaining current flow therein during position adjustments of the cell anode bus bar mounted on the anode-supporting superstructure of the cell.

ln the prebake-d type of electrolytic cell used in the aluminum industry, a plurality of anodes are individually suspended from metal anode rods or conductor bars, for example of copper or aluminum, which in turn are suitably aixed to supporting conductors or cell anode bus bars which are positioned substantially horizontally above the cavity of the electrolytic cell. During operation of the cell, the lower portion of the anodes is consumed or burned olf, and the anodes must be lowered in order t have the lower surface thereof in the proper position in the electroylte. Accordingly, a suitable jacking mechanism must be provided for lowering and raising the supporting cell anode bus bars. In order to avoid the necessity of removing and replacing all of the anodes at once, they are staggered in their vertical position such that only one or two require replacing at a given time. In view of such staggering, it is necessary, when the supporting cell arode bus bars have reached their lowest position, to be able to maintain the anodes in a fixed position relative to the electrolyte while the supporting cell anode bus bars are raised to their highest position. After the supporting cell anode bus bars are raised to their highest position, the anodes may be lowered further by lowering the supporting cell anode bus bars. Accordingly, suitable structural members or auxiliary anode bus bars are provided above and parallel to the supporting cell anode bus bars. The metal anode rods are of sutlicient length that the ends of the rods extend to a position above the structural auxiliary anode bus bars when the electrode is at its. lowest position. Thus, when the supporting cell anode bus bars reach their lowest position, the rods may be afxed to the structural auxiliary anode bus bars to maintain them in position. The rods may then be disengaged from the supporting cell anode bus bars and the supporting cell anode bus bars moved to the uppermost position. The rods may be again aixed to the supporting cell anode bus bars and disengaged from the structural auxiliary anode bus bars. Lowering of the rods and electrodes may then be resumed by lowering the supporting conductors or anode bus bars.

When an anode has been consumed to a point where it needs to be replaced, the replacement is done with the aid of a suitable lifting device such as a crane. To facilitate such lifting, an opening is generally provided in the Patented Dec. 16, 1969 ICC upper end of the metal anode rod for engagement by a hook of the crane. Accordingly, the metal anode rods must be sufficiently long to extend to the structural auxiliary anode bus bars and also extend somewhat beyond to make possible engaging the crane hook in the opening.

This conventional system has several disadvantages. Current flows into the anode rod during the position adjustment of the cell anode bus bar either through current connection to the auxiliary anode bus bar or by a sliding or scraping electrical contact obtained between the anode rod and the cell anode bus bar as the bus bar is jacked upwards. This gives undesirable sparking with consequent surface disintegration of the cell anode bus bar and of the anode rod. The anode rods must be long enough to be clamped to either bus and the superstructure of the cell must be strong enough to support the auxiliary anode bus bar and all its related appendages. This means the superstructure of the cell must be much stronger than it would otherwise have to be. Since the resultant superstructure is taller than it otherwise need be, the building must also be taller than it otherwise need be. It takes as much as torty-five minutes per cell to raise the main bus and reclamp the anodes by this conventional procedure.

Accordingly, the instant invention is concerned with providing a novel system for supporting the anode of an electrolytic cell for the production of aluminum and maintaining current ow therein during position adjustment of the cell anode bus bar mounted on the anode supporting superstructure of the cell.

Advantageously, the novel system of this invention is independent of the superstructure of the cell. Consequently, a lighter superstructure may be utilized in the design and construction of the cell. This makes possible a substantial reduction in the cost of the cell. Whereas the conventional procedure can require as much as fortyve minutes per cell to raise the main bus and reclamp the anodes, the task, using the instant system, can be accomplished in approximately ten minutes.

Also, the novel system of this invention is advantageous in that shorter anode rods can be used which result in additional cost saving since the anode rods are made of relatively costly materials such as aluminum or copper. There is less wear and tear on the anode rods which results in a further savings.

A further advantage of the novel system of this invention is that there is no sparking with consequent deterioration of the electrical connection of the main anode bus and anode rod during position adjustment of the cell anode bus bar. This greatly increases the life of both the cell anode bus bar and the anode rod.

These and other purposes and advantages of this invention will become more apparent from the following description taken in conjunction with the accompanying drawings.

This invention relates to auxiliary apparatus for supporting the anodes of an electrolytic cell for the production `of aluminum and maintaining current flow therein during position adjustment of the cell anode bus bar mounted on the anode supporting superstructure of the cellThe apparatus includes an elongated frame member and means for positioning the frame member in juxtaposition with the superstructure of the cell. An Auxiliary anode bus bar is mounted on the frame and is adapted to be positioned substantially parallel to an anode bus bar of the cell. Means are associated with the frame and'auxiliary anode bus bar for clamping the anode rods supporting the cell anodes to the auxiliary anode but bar in current conducting engagement. Flexible leads are attached to each end of the auxiliary anode bus bar and a clamp is attached to the free end of each` flexible lead. Means are provided for attaching the clamps to the ends of the cell anode bus bar in current conducting engagement so that the current bypasses the cell anode bus bar and ows into the cell via the axiliary anode bus bar and the anode rods clamped in current conducting engagement therewith. The elongated frame member may be suspended from overhead rails for positional movement, or it may be mounted on wheels therefor, or in any other appropriate manner. Although the elongated frame member may extend only along one side of the superstructure of the cell, it may also be constructed so as to resemble an inverted U in cross-section whereby it envelops the superstructure of the cell when positioned in juxtaposition therewith. When the inverted U-shaped cross-sectional construction is used, then of course, an auxiliary anode bus bar and the related appendages may be provided on each leg of the U. This means that the main anode bus bars on both sides of the superstructure of the cell may be adjusted without having to change the position of the auxiliary apparatus of the instant invention.

In addition, although the invention contemplates clamping the anode rods supporting the cell anodes to the auxiliary anode bus bar in current conducting engagement, in some instances, it may be desirable to provide a exible current conducting connector between each clamp and the auxiliary anode bus bar to compensate for warpage of the anode rods. When this is done, then, of course, the clamps may be associated with the frame so as to grip the anode rods supporting the cell anodes in weight supporting current conducting engagement with the ilexible current conducting connectors completing the circuit to the auxiliary anode bus bar.

The accompanying drawings are illustrative of some embodiments of this invention.

FIG. 1 is a top plan view of one embodiment of the apparatus of this invention with parts removed for purposes of clarity.

FIG. 2 is a front view of the embodiment shown in FIG. 1 with parts removed for purposes of clarity and with a portion cut away to more clearly show one of the anode clamps.

FIG. 3 is a side elevation View partly in section taken substantially along line 3 3 of FIG. l with parts removed for purposes of clarity.

FIG. 4 is a side elevation view partly in section of the anode rod clamping means and exible connection shown in FIG. 3 with parts removed for purposes of clarity.

FIG. 5 is a top plan view partly in section of the anode rod clamping means and flexible connection shown in FIG. 4 with parts removed for purposes of clarity.

FIG. 6 is a side elevation view partly in section of the flexible lead and cla-mp for attachment to the ends of the cell anode bus bar in current conducting engagement therewith shown in FIG. 3 with parts removed for purposes of clarity.

FIG. 7 is a side elevation View partly in section with parts removed for purposes of clarity of another form of ilexible lead and clamp for attachment to the ends of the cell anode bus bar in current conducting engagement therewith.

Referring now more particularly to the drawings, in which the same reference numerals have been applied to corresponding parts, and with particular reference to FIGS. 1, 2 and 3, the superstructure of an electrolytic cell for the production of aluminum is indicated generally at 10. Supported by the cell superstructure 10` are cell anode bus bars 12. Current is supplied to the cell anode bus bars 12 via electrical conductor 14. Attached to each cell anode bus bar 12 are anode rod clamps 16. Anode rod clamps 16 engage `the anode rods 18 which support the cell anodes (not shown) in current conducting engagement with the cell anode bus bar. As shown in FIG. 3, suitable jacking means 20 are also mounted on cell superstructure 10 for adjusting the position of the cell anode bus bar 12. An ore hopper 22 is attached to the superstructure of the cell for supplying makeup feed to the cell.

In accordance with the instant invention, the apparatus for supporting the anodes of the electrolytic cell during position adjustment of cell anode bus bar 12 mounted on the anode supporting superstructure 10 of the cell comprises an elongated frame member 24 which in the embodiment shown here resembles an inverted U in cross-section so as to envelop the superstructure 10 of the cell when positioned in juxtaposition therewith. Each leg 26 of the U is provided with an auxiliary anode bus bar 28 mounted thereon and which is adapted to be positioned as shown, substantially parallel to an anode bus bar 12 of the cell. Suitable clamps 30 are associated with and suspended from the frame by braces 32 for gripping the anode rods 18 in weight supporting current conducting engagement. As shown in FIG. 2, the clamp 30 may be of a toggle type but other suitable clamping means may, of course, -be used.

As shown in FIGS. 1 and 3, a exible current conducting connector 34 is connected at its opposite ends to both a clamp 30 and the auxiliary anode bus bar 28. This provides the path of travel of the electrical current from the auxiliary anode bus bar 28 to the anode rod 18 via the clamp 30. Flexible leads 36 are attached to each end of each auxiliary anode bus bar 28. A clamp 38 is attached to the free end of each flexible lead. Each clamp 38 is suspended from frame member 24 in a suitable manner as by brace 40. Suitable means such as piston 42 and cylinder 44 are provided for attaching the clamps 38 to` the end of the cell anode bus bar 12 in current conducting engagement. To facilitate this connection, a pad 46 may be attached to the end of the cell anode bus bar 12 in a suitable manner as by welding. When such a pad 46 is provided then clamp 38 will grip pad 46 in current conducting engagement.

In the embodiment shown in these figures, an equalizer bus 48 is provided between the two auxiliary anode bus bars 28 so as to ensure even current distribution therebetween. The equilizer bus 48 may be so constructed as to provide additional strength to the elongated frame member 24, as shown here. If, as is shown in this embodiment, uid pressure is utilized to operate the various clamps on the apparatus, then suitable fluid supply lines 50 (segments only shown), are provided on the frame member 24. Fluid storage tanks 52 may be mounted on frame member 24 as a reserve source of iluid pressure should the main source of fluid pressure through fluid supply lines 50 fail for some reason. Pad eyes 54 are attached to the top of elongated frame member 24. The pad eyes 54 are adapted to be engaged by suitable hooks so that the elongated frame member 24 and the apparatus of the instant invention may be suspended from overhead rails for positional movement.

The manner in which clamp 30, exible connector 34, and auxiliary anode bus bar 28 and brace 32 are interrelated shall be explained in greater detail with reference to FIGS. 2, 3, 4 and 5. As shown in FIGS. 3 and 4 support plate 56 is suspended from brace 32 by a plurality of parallel legs 58 each of which is connected pivotally at its opposite ends to both the support plate 56 and brace 32 so as to permit reciprocating movement of the support plate 56 with respect to brace 32. Cylindrical bearings 60 are mounted on the lower end of support plate 56 in journal housing 62. Pivotally mounted on cylindrical bearings 60 by sleeves 64 are clamp pivot linkages 66 and 67. Pivotally mounted on the lower end of clamp pivot linkages 66 is a jaw 68 of clamp 30. Attached to the rear of jaw 68 is exible connector 34 in any suitable manner as by welding. The opposite end of flexible connector 34 is attached to auxiliary anode bus bar 28 in any suitable manner as by nuts 77 and bolts 70. It is desirable although not absolutely essential that flexible connector 34 be divided into two sections, one section extending between one jaw 68 of clamp 30 and auxiliary anode bus bar 28 and the other section extending between the other jaw 72 of clamp 30 and auxiliary anode bus bar 28. The pivotal mounting of support plate 56 on brace 32 by means of legs 58 permits the clamp 30 and flexible connector 34 assembly to move horizontally as necessary to compensate for warpage, distortion, etc. of anode rod 18. Clamp pivot linkages 66 and 67 are operated by the movement of piston 69 in cylinder 71 under uid pressure, piston `69 being linked to clamp pivot linkages 66 and 67 by arms 73 and 75.

With reference now to FIGS. 3 and 6, the connection between the auxiliary anode bus bar 28 and the cell anode bus bar 12 shall be described in greater detail. Suspended from brace 40 is support plate 74 by means of a plurality of parallel legs 76, each of which is connected pivotally at its opposite ends to both support plate 74 and brace 40 so as to permit reciprocating movement of support plate 74 with respect to brace 40. The attachment of each leg 76 to support plate 74 is by means of a pin 78 riding in elongated slot 80 to permit vertical movement of support plate 74 with respect to brace 40. Cylindrical bearing 82 extends horizontally from one plate 74 to another plate 74 suspended on the opposite side of flexible lead 36 from a second brace 40. Suspended from bearing 82 by leg 84 is cylinder 44. Leg 84 is connected pivotally at its opposite ends to both bearing 82 and cylinder 44 so as to permit pivotal movement of the cylinder 44 with respect to bearing 82. Attached to support plate 74 is upper jaw 86 of clamp 38. Extending from cylinder 44 is piston 42 passing through sleeve guide 88 attached to support plate 74. Attached to the lower end of piston 42 is lower jaw 90 of clamp 38. As shown, exible lead 36 is divided into two sections, the free end of upper section 92 being attached to upper jaw 86 of clamp 38 by means of rigid lead 96. Similarly, lower section 94 of exible lead 36 is attached to lower jaw 90 of clamp 38 by means of rigid lead 98. As shown in FIG. 6, lower jaw 90 of clamp 38 is pivotally mounted by means of pin bearing 100 to extension plate 102 attached to support plate 74.

An alternate form of connection between the auxiliary anode bus bar 28 and the cell anode bus bar 12 is shown in FIG. 7 wherein like numerals have been used for like parts. Suspended from brace 40 is support plate 74 by means of a plurality of parallel legs 76, each of which is connected pivotally, at its opposite ends to both support plate 74 and brace 40 so as to permit reciprocating movement of support plate 74 with respect to brace 40'. The attachment of each leg 76 to support plate 74 is by means of a pin 78 riding in elongated slot 80 to permit vertical movement of support plate 74 with respect to brace 40. A journal bearing 104 is attached to each support plate 74, as by bolts 106 to support shaft 108 attached to cylinder 44 so as to permit some pivotal movement of cylinder 44. Attached to support plate 74 is jaw 110 provided at its lower end with stop 112 adapted to contact butter 114 on pad 46 and cell anode bus bar 12. Extending from cylinder 44 is piston 42 in bellows cover 116. Attached to the free end of piston 42 by arm 118 through linkage 120 is jaw 122. Arm 118 is pivotally mounted by means of a pin bearing 124 to support plate 74. Jaw 122 is provided with pad limit stop 126. As shown, the free end of flexible lead 36 is attached to jaw 122, as by welding, in current conducting engagement therewith. A second flexible lead 128 connected at its opposite ends as by welding in current conducting engagement with jaws 122 and 110 provides a path for current travel between jaws 122 and 110. Jaw 122 is suspended from support plate 74 by leg 130 connected pivotally at its opposite ends to both support plate 74 and jaw 122 so as to permit reciprocating movement of jaw 122 with respect to support plate 74. Mounted behind a leg 76 on a pin 78 is plate 132. Pinned to plate 132 is shaft 134 loaded by spring 136 pressing against seat 138 on support plate 74. A bearing plate 140 is provided on a leg 76 for plate 132 to ride against as support plate 74 moves vertically with respect to brace 40, for example during position adjustment of cell anode bus bar 12. This arrangement tends to keep support plate 74 and its related appendages in proper upright alignment as support plate 74 moves vertically with respect to brace 40.

The operation of this apparatus embodying the principle of the instant invention shall now be described with reference to FIGS. 1-6 inclusive. When the cell anode bus bar 12 has reached its lowest position, the elongated frame member 24 suspended for example from an overhead crane by means of hooks engaging pad eyes 54 is brought into position and lowered over the superstructure 10 of the cell so as to envelop the superstructure 10 of the cell when positioned in juxtaposition therewith. During the positioning operation, the auxiliary anode bus bars 28 are positioned substantially parallel to the cell anode; bus bars 12. By means of suitable control devices, either automatic or manual, the clamps 30 are actuated so as to grasp the anode rods 18. At the same time, clamps 38 attached to flexible leads 36 are also actuated so as to grasp the ends of the cell anode bus bar 12, for example at pad 46, in current conducting engagement therewith. By so doing the current is bypassed from the cell 4anode bus bar 12 to the auxiliary bus bar 28. The anode rod clamps 16 holding the anode rods 18 to the cell anode bus bar 12 are then released and the cell anode bus bar 12 is raised to its uppermost position for example by jacking means 20. The anode rod clamps 16 on the cell anode bus bar 12 are then actuated again, clamping the anode rods 18 to the cell anode bus bar 12. Clamps 30 and 38 on the auxiliary bus bar 28 are then released so that the anode rods 18 are again supported by the cell anode bus bar in current conducting engagement and current is again flowing to the cell anode via the cell anode bus bar 12. The auxiliary apparatus of the instant invention may then be moved onto the next cell wherein a position adjustment of the cell anode bus bar is due.

It can be seen that the novel auxiliary apparatus of this invention makes possible a substantial reduction in the cost of the electrolytic cell due to -a much lighter and smaller superstructure. Since one apparatus embodying the principles of this invention may service many reduction cells, a substantial savings in the cost of equipment may also be realized. Since the operation of the auxiliary apparatus of this invention may be fully automatic, a substantial time saving may also be realized. Shorter anode rods can be used to support the cell anodes which results in additional cost saving. Since the ilow of current bypasses the cell anode bus bar during the position adjustment operation, sparking of the main anode bus bar against the anode rod as the main cell anode bus bar moves upwardly with consequent surface deterioration of the electrical connection of both the bus and the rod is eliminated.

While there has been shown and described hereinabove one embodiment of this invention, it is to be understood that the invention is not limited thereto and that various changes, alterations, and modications can be made thereto without departing from the spirit and scope thereof as defined in the appended claims. For example, the elongated frame member may be such that only one auxiliary anode bus bar is attached thereto and thus the cell anode bus bar on one side of the cell only can be adjusted utilizing the apparatus. Similarly, although the apparatus iS of inverted U-shaped cross-section, only one auxiliary anode bus bar may be provided thereon. Further, the instant invention is not to be construed as limited to any particular form of clamp or clamp actuating means. Only the presently preferred types of clamps and clamp actuating means have been described hereinabove. Although the apparatus has been described as suspended from overhead for example from a crane travelling on overhead rails for positional movement, the elongated frame member could also be mounted on wheels for positional movement. The wheels, of course, could rotate either on the floor or on an elevated track for movement. The llexible connectors and exible leads do not necessarily have to be divided into two sections for attachment to their respective clamps, but could be of unitary construction attached to their respective clamps in an appropriate manner. Similarly, the anode rods could be clamped in current conducting engagement directly to the auxiliary anode bus bar without the use of a flexible connector.

What is claimed is:

1. Auxiliary apparatus `for supporting the anodes of an electrolytic cell for the production of aluminum and maintaining current flow therein during position adjustment of the cell anode bus bar mounted on the anodesupporting superstructure of the cell which comprises:

(a) an elongated frame member;

(b) means for positioning the frame member in juxtaposition wiih the superstructure of the cell;

(c) an auxiliary anode bus bar mounted on the frame and adapted to be positioned substantially parallel to an anode bus bar of a cell;

(d) means associated with the frame and auxiliary anode bus bar for clamping anode rods supporting the cell anodes to the auxiliary anode bus bar in current conducting engagement;

(e) flexible leads attached to each end of the auxiliary anode bus bar;

(f) a clamp attached to the free end of each flexible lead;

(g) means for attaching the clamps to the ends of the cell anode bus bar in current conducting engagement so that the current bypasses the cell anode bus bar and flows into the cell Via the auxiliary anode bus bar and the anode rods clamped in current conducting engagement therewith.

2. The apparatus of claim 1 wherein the elongated frame member resembles an inverted U in cross-section whereby it envelops the superstructure of the cell when positioned in juxtaposition therewith.

3. The apparatus of claim 1 wherein the means for clamping the anode rods supporting the cell anodes to the auxiliary anode bus bar in current conducting engagement is provided with a flexible, current conducting connector between each clamp and the auxiliary anode bus bar.

4. The apparatus of claim 3 wherein the clamping means comprises two jaws and wherein the flexible current conducting connectors are each divided into two sections, one section extending between one jaw of the clamping means and the auxiliary anode bus bar and the other section extending between the other jaw of the clamping means and the auxiliary anode bus bar.

5. The apparatus of claim 1 wherein the clamp attached to the free end of each flexible lead attached to each end of the auxiliary anode bus bar comprises two jaws and wherein the flexible leads are each divided into two sections, the free end of one section being attached to one jaw of the clamp and the free end of the other section being attached to the other jaw of the clamp.

6. The apparatus of claim 5 wherein a second flexible lead is provided between and in current conducting engagement with the jaws of the clamp so as to provide a path of current travel between the jaws of the clamp.

7. Auxiliary apparatus for supporting the anodes of an electrolytic cell for the production of aluminum and 8 maintaining current ilow therein during position adjustment of the cell anode bus bar mounted on the anodesupporting superstructure of the cell which comprises:

(a) an elongated frame member of inverted U shaped cross-section, each leg of the U being provided with:

(i) an auxiliary anode bus bar mounted on the frame and adapted to be positioned substantially parallel to an anode bus bar of a cell;

(ii) means associated with the frame and auxiliary anode bus bar for clamping anode rods supporting the cell anodes to the auxiliary anode bus bar in current conducting engagement;

(iii) flexible leads attached to each end of the auxiliary anode bus bar;

(iv) a clamp attached to the free end of each ilexible lead;

(v) means for attaching the clamps to the ends of the cell anode bus bar in current conducting engagement so that the current bypasses the cell anode bus bar and flows into the cell via the auxiliary anode bus bar and the anode rods clamped in current conducting engagement therewith; and

(b) means for positioning the frame member in juxtaposition with and enveloping the superstructure of the cell.

8. The apparatus of claim 7 wherein the means for clamping the anode rods supporting the cell anodes to the auxiliary anode bus bar in current conducting engagement is provided with a ilexible, current conducting connector between each clamp and the auxiliary anode bus bar.

9. The apparatus of claim 8 wherein the clamping means comprises two jaws and wherein the flexible current conducting connectors are each divided into two sections, one section extending between one jaw of the clamping means and the auxiliary anode bus bar and the other section extending between the other jaw of the clamping means and the auxiliary anode bus bar.

10. The apparatus of claim 7 wherein an equalizer bus bar connects the two auxiliary anode bus bars so as to ensure even current distribution therebetween.

11. The apparatus of claim 7 wherein the clamp attached to the free end of each flexible lead attached t0 each end of the auxiliary anode bus bar comprises two jaws and wherein the llexible leads are each divided into two sections, the free end of one section being attached to the other jaw of the clamp.

12. The apparatus of claim 11 wherein a second flexible lead is provided between and in current conducting engagement with the jaws of the clamp so as to provide a path of current travel between the jaws of the clamp.

References Cited UNITED STATES PATENTS 2,758,964 8/1956 Liles 204-286 X 2,816,861 12/1957 Castex 204-243 X 2,825,690 3/1958 Ferrand 204-247 X 3,052,619 9/1962 Schmitt 204-243 FOREIGN PATENTS 1,445,602 6/ 1966 France.

ALLEN B. CURTIS, Primary Examiner

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