GB1603797A

GB1603797A - Fusion welding of battery terminals

Info

Publication number: GB1603797A
Application number: GB24098/78A
Authority: GB
Original assignee: General Battery Corp
Current assignee: General Battery Corp
Priority date: 1977-11-21
Filing date: 1978-05-30
Publication date: 1981-11-25
Also published as: DE2850499A1; JPS5485346A; CA1125862A

Description

(54) IMPROVEMENTS IN OR RELATING TO ThE FUSION WELDING OF BATTERY TERMINALS (71) We, GENERAL BATTERY CORPORATION, a Corporation organized and existing under the laws of the State of Delaware, United States of America, care of Post Office Box 1262, Reading, State of Pennsylvania, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to a novel method of fusion welding the terminals of lead-acid batteries.

It has long been known that battery posts or terminals can be sealed with respect to a battery cover or other wall surface through which the post or terminal is intended to pass by fusing the post to an adjacent sleeve or bushing which is molded into the cover. The resultant fusion welding of the post and bushing seals the battery cell to prevent leakage. In the case of a battery terminal, such as an automotive battery terminal no further parts need be fused to the terminal post and bushing. In the case of a motive power battery, or an automotive battery in which the post and bushing are to be connected to an adjacent cell using an exterior connector, a battery connector may be either simultaneously or subsequently fusion welded to the post and bushing to create an intercell connection between that terminal and the terminal of an adjacent cell.

The invention is concerned with the use of a radio frequency energy beam to weld terminal connections and, if desired, intercell connections of a lead-acid battery, and more particularly relates to the fusion welding of a battery terminal bushing to a battery terminal post disposed therein.

According to the present invention there is provided a method of fusion welding a battery terminal post to a lead-alloy battery cover bushing secured in an aperture in a battery cover, including the steps of encircling a battery post with said bushing, placing a cooling ring around the battery cover bushing, and applying a radio frequency energy beam to the assembled components to fusion weld the bushing to the terminal post.

According to a further aspect of the invention there is provided apparatus for carrying out said method to fusion weld battery cover bushings to battery terminal posts of lead-acid batteries, wherein at least one radio frequency energy beam nozzle and at least one cooling ring are mounted on a carriage reciprocally movable whereby said cooling ring may engage a bushing seated on a battery terminal post prior to application of a fushion welding radio frequency beam to fushion weld the bushing to the terminal post.

In order that the present invention may be more clearly understood and readily carried into effect, reference will now be made to the accompanying drawings, in which Fig. 1 is an exploded view showing the components of a battery terminal post assembled by the method of the present invention; Fig. 2 is a cross-section of the components illustrated in Fig. 1 shown in the assembled condition; Fig. 3 is a diagrammatic view showing a welding head or oriented generally over the top of an industrial battery; Fig. 4 is a diagrammatic view of a cross-section of one embodiment of the invention in which a cooling ring has been fitted around a bushing and post prior to activation of a radio frequency beam head which is oriented generally along the axis of the post; Fig. 5 is a diagrammatic view of another embodiment in which a cooling ring is fitted a terminal post and cover bushing; Fig. 6 illustrates an individual cooling ring similar to, but on a larger scale than, that shown in Fig. 4; Fig. 7 is a side view of the cooling ring illustrated in Fig. 6; Fig. 8 is a top view of a preferred embodiment double cooling ring for use on a battery cell having both positive and negative terminals which are to be simultaneously fusion welded; Fig. 9 is a side view of the double cooling ring shown in Fig. 8; Fig. 10 is a side view of a preferred embodiment of a fusion welding apparatus; Fig. 11 is a front view of the apparatus illustrated in Fig. 10; and Fig. 12 is a top view of the apparatus illustrated in Figs. 10 and 11.

Referring now to the drawings, the exploded view of Fig. 1 shows how a bushing 1 which is either screwed or molded into a cover 2 is pierced by a battery terminal post 3 and a cooling ring 4 placed thereover as described more fully hereinafter in connection with Figs. 10 to 12.

Referring now to Fig. 3, the general axial orientation of a single ratio frequency beam head 5 over a connector 6 of a motive power storage battery to be welded is illustrated. In one additional feature the present invention, a radio frequency beam head having a cooling ring mounted in cooperation therewith is axially introduced into engagement with each connector to be welded to each "button" of a sealed battery cell. Alternatively, it is anticipated that the increased power, the battery terminal post, bushing and connector can all be fusion welded in a single operation. The preferred axial orientation of the radio frequency beam head over the terminal post is shown by arrow 5' in Figure 4 and a cooling ring 4 is illustrated fitted to encircle the sleeve or bushing 1 and the post 3 contained therewithin. In Fig. 5, the preferred axial orientation of the beam head is again shown by arrow 5' and a slightly different lead flange 11 and battery terminal post 13 are illustrated. In this embodiment a cooling ring is adapted to bridge between more than one battery post 13 so that a single cooling ring assembly can service more than one radio frequency beam. While Figs. 4 and 5 illustrate traditional designs for a rubber cover 7, 17 respectively, it is anticipated that "poly" covers and cases 8 or jar 18 will be used and heat sealed by sealing compounds 9, 19.

Figs. 6, 7, 8 and 9 illustrate alternative preferred embodiments of cooling rings for mounting on a carriage of the apparatus shown in Figs. 10 to 12. In both the embodiment of Figures 6 and 7 and the embodiment of Figures 8 and 9 the flow of cooling fluid into, around and out of cooling rings is schematically indicated by arrows.

Similar schematic arrows are included in Figure 1 where the cooling fluid input 10 leads to a conduit 21 which extends in and around the cooling ring 4, 14 and in turn leads to the output 20. Maximum clearance is illustrated between the cooling rings to facilitate location of fusion welding terminals on either side of a fill hole. In order to maximize cooling efficiency, the cooling rings 4, 14 are preferably aluminum.

Referring now to Fig. 10, the preferred embodiment of apparatus of the present invention embodying a fusion welding station is illustrated. A carriage 100 is adapted for reciprocal, vertical movement along a plurality of rails 120, 121, 122, 123 at the four corners thereof so that the carriage 100 may be moved downwards to engage battery cells which are located on a conveyor 105 and positioned by retractable rams 102. Located above the cooling rings 101 on the carriage 100 are a plurality of beam nozzles 109. These beam nozzles may be of a type generally illustrated in U.S. Patent Nos. 3,894,209 and 3,648,015. Disposed above the beam nozzles 109 on the carriage 100 for vertical movement therewith is network module 104 which is adapted to split and control the radio frequency energy produced by an RF generator 106 and supplied to said module 104 by a cable 115. The generator 106 is located immediately behind carriage frame 108. The height of the module is adjustable and a scale 117 is provided for indicating the desired height.

A control station 110 to control gas flow through gas lines 111 to the network module 104 is supplied by tanks 112, 114 and 116. Referring now to Fig. 11 which is a front view of the apparatus shown in Fig. 10, water lines 113 are shown communicating with the carriage 100 for providing a coolant to cooling rings 101. Since dissipation of gas in the vicinity of the fusion weld is important, it has been found that the axial positioning of the beam nozzles is important to aid in the dissipation of the gas in the vicinity of the weld. Accordingly, an exhaust manifold 103 is provided adjacent to and slightly above the cooling rings 101 such that gas which is dissipating in the vicinity of the fusion weld will be carried immediately away from that area and will not interfere with continuing fusion welding operations. Referring now to Fig. 12 which is a top view of the apparatus illustrated in Figs. 10 and 11, the relative orientation of the various components of the apparatus are clearly illustrated. Beam nozzles 109, for example, are shown oriented within a plane traverse to the advancement of the conveyor so that adjacent spaced apart terminals on individual cells may be fused therewith. Figs. 10-12 show how the fusion welding station of the apparatus of the present invention will weld two terminals simultaneously on a cell cover to a required weld depth of approximately 0.375 inches and will accommodate cell widths of between 6.25 inches and 8.63 inches and cell heights of between 13.75 to 31.75 inches, the majority of which cells will be 20.25 inches high. The cells enter the apparatus one at a time and stop beneath the cooling rings by delayed response from a photoelectric cell 107 shown on the carriage assembly 100. The cooling rings 101 adjust to reciprocate above the cover to selectively index against the cell cover bushings.

When the rings are properly indexed, twin beams fusion weld the terminals, after which the beams are preferably reduced drastically in energy level to a point where they will not melt the plastic cover of the jar 18 when moved thereacross (as for example between 0 and 100 watts). Then the cooling rings rise and the cell moves forward until two more bushings index into position. For those jars where more than one pair of bushings and terminals are to be fusion welded thereon, the apparatus will index through positions 1 to 3, etc. until each of the terminals have been fusion welded.

The maximum cycle time is 15 seconds per cell for a two bushing cell and 30 seconds per cell for a 4 or 6 bushing cell.

In the preferred embodiment, the beam settings should be varied in order to accommodate strength, time per weld, gas flow rates, appropriate cooling rings to fit corresponding bushings, center-to-center bushings distances, and finally module height adjustment and lock to insure that the cooling rings are approximately one-half inch above the bushings.

Based on the data detailed below and experience gained during testing, it has been found that a 5 kilowatt radio frequency beam generated, as for example, of the type available from Energystics, Inc., of Toleda, Ohio, is capable of consistently fusion welding two industrial battery terminals, simultaneously to a minimum depth of 0.375 inch. In this regard, in the preferred embodiment high quality fusion welding is ensured by carefully controlling the beam nozzle design, beam strength and duration, beam distance and position with respect to the point to be welded, post to cover bushing fit, and cooling ring design.

As shown by arrows 5' in Figures 4 and 5, the beam is preferably oriented vertically downward onto the centre of the cell terminal 3. The nozzle design and gas flow are chosen to focus and give momentum to the beam sufficient to concentrate the beam, to push the previously expelled gas away from the area, and to prevent lead oxide vapor from traveling back up the beam and causing the beam to scatter and collapse. So that the gas and vapor can be expelled properly, a cooling ring is provided which allows for even gas dissipation on all sides. The use of an aluminum cooling ring to successfully prevent any damage to the plastic cover has been found to be satisfactory. The preferred ring comprises edges in the fusion weld area which are bevelled in order to prevent beam attraction so that the beam will not end to arc to the edge of the ring rather than to the lead parts to be welded. In order to additionally prevent beam arcing, the top surface of the ring is preferably coated with a layer of ceramic.

It has been found that a maximum gap of 0.010 inches per side (0.020 inches if all on one side) may be tolerated between the terminal post and cover bushing. If the post to bushing fit is looser than the above mentioned range, the depth of weld decreases significantly. It is theorized that the heat is not conducting as rapidly to the bushing and/or that is the gap is above 0.020 inches per side, the beam may arc down the post, in a skin effect, into the cell. By maintaining the top surfaces of the post and bushing at equal heights, the depth of weld is maximized.

Accordingly, the following normal operating conditions are recommended for both standard, and 5 and 7 plate cell terminals: 1. Gas flow rates Core (helium) - 17.5 standard cubic ft. per minute+1 Sheath (helium) - 1 standard cubic ft. per minute+1, -0.5 Sheath (hydrogen) - 5 standard cubic ft. per minute+1 2. Beam power - true value (total minus reflected) -4 to 4.5 KW (reflected power to be minimized 3. Beam duration - 9 seconds+ 1.

4. Two terminals welded simultaneously by phase sharing of beam.

5. Distance of beam nozzle from top bf post and cover bushing -- 0.5 inches .0625 inch.

6. Regarding beam nozzle to be used, the tip should protrude about 2.5 inches from the sheath. Tip diameter is about .5625 inch; sheath diameter is about 1.25 inches. Both sheath and tip must be fully insulated with boron nitrate or molybdenum.

7. Beam to impinge on the centre of the post, no more than .0625 inch to any side of the post 8. Post height should be equal to bushing height, + .031 inch, - .093 inch.

9. Post to cover bushing fit -- maximum gap of .010 inch per side (.020 inch if all on one side) at the top of the post and bushing.

10. Cooling ring fit over exposed top of bushing does not have to be tight. Cooling ring diameter can be up to .0625 inch greater than bushing outer diameter.

The beam power of 4 to 4.5 kilowatts is presently preferred, adequate fusion welds have been obtained using beam power of as little as 3 kilowatts.

WHAT WE CLAIM IS: 1. A method of fusion welding a battery terminal post to a leadelloy battery cover bushing secured in an aperture in a battery cover, including the steps of encircling a battery post with said bushing, placing a cooling ring around the battery cover bushing, and applying a radio frequency energy beam to the assembled components to fusion weld the bushing to the terminal post 2. A method as claimed in Claim 1, wherein the radio frequency energy beam is oriented along the axis of the terminal post and the bushing.

3. A method as claimed in Claim 1 or Claim 2, wherein the step of fusion welding the bushing to the terminal post is accomplished wkh a radio frequency energy level between 3 kilowatts and 4.5 kilowatts.

4. A method as claimed in Claim 3, wherein said energy is directed for a period of time between 8 seconds and 10 seconds.

5. A method as claimed in any of dais 1 to 4, wherein said cooling ring is fluid cooled.

6. A method as claimed in any of claims 1 to 5, wherein a plurality of bushings and terminal posts are simultaneously fusion welded by a plurality of radio frequency beams.

7. A method as claimed in Claim 1, wherein the radio frequency energy beam impinges upon the centre of the terminal post no more than 0.0625 inches to any side of the post.

8. A method as claimed in any of claims 1 to 7 including the additional step of utilizing the radio frequency energy to fusion weld intercell connections.

9. Apparatus for carrying out the method of claim 1 to fusion weld battery cover bushings to battery terminal posts of lead-acid batteries, wherein at least one radio frequency energy beam nozzle and at least one cooling ring are mounted on a carriage reciprocally movable whereby said cooling ring may engage a bushing seated on a battery terminal post prior to application of a fusion welding radio frequency beam to fusion weld the bushing to the terminal post.

10. Apparatus as claimed in Claim 9, wherein one of said directions of carriage movements is in axial alignment with said frequency energy beam nozzle.

11. Apparatus as claimed in Claim 9 or Claim 10, wherein the or each cooling ring is fluid cooled.

12. Apparatus as claimed in any of Claims 9 to 11, wherein an exhaust manifold is provided for exhausting gases from the vicinity of the bushing and terminal post to be fusion welded.

13. A method of fusion welding a battery terminal post to a battery cover bushing substantially as hereinbefore described.

14. Apparatus for fusion welding battery cover bushings to battery terminal posts substantially as hereinbefore described with reference to the accompanying drawings.

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. 2. Beam power - true value (total minus reflected) -4 to 4.5 KW (reflected power to be minimized 3. Beam duration - 9 seconds+ 1. 4. Two terminals welded simultaneously by phase sharing of beam. 5. Distance of beam nozzle from top bf post and cover bushing -- 0.5 inches .0625 inch. 6. Regarding beam nozzle to be used, the tip should protrude about 2.5 inches from the sheath. Tip diameter is about .5625 inch; sheath diameter is about 1.25 inches. Both sheath and tip must be fully insulated with boron nitrate or molybdenum. 7. Beam to impinge on the centre of the post, no more than .0625 inch to any side of the post 8. Post height should be equal to bushing height, + .031 inch, - .093 inch. 9. Post to cover bushing fit -- maximum gap of .010 inch per side (.020 inch if all on one side) at the top of the post and bushing. 10. Cooling ring fit over exposed top of bushing does not have to be tight. Cooling ring diameter can be up to .0625 inch greater than bushing outer diameter. The beam power of 4 to 4.5 kilowatts is presently preferred, adequate fusion welds have been obtained using beam power of as little as 3 kilowatts. WHAT WE CLAIM IS:

1. A method of fusion welding a battery terminal post to a leadelloy battery cover bushing secured in an aperture in a battery cover, including the steps of encircling a battery post with said bushing, placing a cooling ring around the battery cover bushing, and applying a radio frequency energy beam to the assembled components to fusion weld the bushing to the terminal post

2. A method as claimed in Claim 1, wherein the radio frequency energy beam is oriented along the axis of the terminal post and the bushing.