Note: Descriptions are shown in the official language in which they were submitted.
B6Z
Background of the Invention
The present invention relates to a novel method ~or
fusing or welding the terminals and/or intercell connections
of lead-acid batteries, and to apparatus therefor.
It has long been known that bat~ery posts or terminals
can be sealed with respect to -the cover or other wall surface
through which that terminal is intended to pass by fusing or
welding that post to an adjacent sleeve or bushing which is
molded into that cover. The resultant weld of the post and
bushing seals the battery cell to prevent leakage. In the
case of a battery terminal, such as an automotive batkery
terminal, no further parts need be welded to the terminal
post and bushing. In the case of a motive power battery, or
an automotive battery wherein the post and bushing are to be
connected to an adjacent cell using an exterior connector, a
battery cell connector may be either simultaneously or subse-
quently welded to the post and bushing to create an intercell
connection between that terminal and the terminal of an
adjacent cellO See, for e~ample, the top two drawings of
Figure 18 on page 66 of Dr. Georye Wood Vinal's treatise
entitled "Storage Batteries: A General Treatise on the
Physics and Chemistry of Secondary Batteries and Their
Engineering Applications", 4th Edition 1955, John Wiley &
Sons, Inc., which treatise is incorporated by reference as
if fully set forth herein.
One standard prior art technique which has been
used to assemble a motive power battery is to hand weld the
battery terminals. More recently, other methods have been
developed for welding battery terminal posts to battery
terminal bushings, or otherwise making connections through
the wall of a battery cell partition. While these other
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methods have experienced some success r there still exists a
need to create a deep homogeneous weld, particularly in
industrial or motive power batteries, where the amount o~
current carried by the connector and/or terminal is great
and the mass o~ metal to be welded toyether is quite
substantial.
Summary of the Invention
, ~
Our invention generally relates to a method for
using a radio ~requency energy beam to weld the terminal
connections and intercell connections of a lead-acid battery
through an aperture in a battery cell wall, and more particu-
larly relates to the welding of a battery terminal bushing to
a battery terminal post disposed therein, while using a heat
sink or cooling ring to encircle the weld area.
With respect to the preferred embodiment welding
apparatus of the present invention, best results are obtained
when the welding apparatus is operated within specific para-
meters, described hereinafter. As a result of using the
preferred embodiment radio frequency beam welding method of
the present invention, superior industrial battery cell
terminal connections are produced which are characterized by
deep homogeneous dross-free welds between the battery terminal
posts and cover bushings.
Brief Descr_ption of the Draw_ngs
Figure 1 is an enlarged/ exploded view of a pre-
ferred embodiment connector assembly in accordance with the
present invention, shown in an exploded relationship with
respect to ~ cooling ring used during the welding operation;
Figure 2 is a cross-sectional view of the components
illustrated in Figure l;
~5~2
Figure 3 is a diagrammatic view of a preferred
embodiment welding head, oriented generally over the -top of
an industrial bat-tery as shown, for welding intercell
connectors;
Figure ~ is a diagrammatic cross-sectional view
of one embodiment of our invention, wherein a cooling ring
has been fitted around the bushing and post prior to activ-
ation of the radio frequency beam head which is oriented
generally along the axis of the post;
Figure 5 illustrates an alternative method of
welding a battery post to a cover bushing using a cooling
ring fitted thereo~er, and a radio frequency beam head
oriented generally axially with the battery post;
Figures 6 and 7 illustrate a cooling ring similar
to that shown in Figure 4;
Figures 8 and 9 are side views of the cooling rings
illustrated in Figures 6 and 7, respectively, showing the
path of the cooling fluid through those rings;
Figure 10 is-a top view of a preferred embodiment
double cooling ring for use in producing a battery cell
connection involving both positive and negative terminals
which are to be simultaneously welded;
Figure 11 is a side view of the double cooling ring
shown in Figure 10, also showing the path of the cooling
fluid;
Figure 12 is a side view of the preferred embodi-
- ment welding station of the present invention showing a
vertically movable head which is fitted with cooling rings,
beam no~zles, and a network module, and also showing the RF
generator and gas control station which services the head;
Figure 13 is a front View o~ the station illustrated
in Figure 12 also showing the water lines, fume ex~aus-t and
electric e~e of the preferred embodiment;
Figure 1~ is a top view of the apparatus illus~rated
in ~igures 12 and 13 also showing the dual radio frequency
beam heads mounted on the vertically movable beam carriage.
Detailed Description of the Preferred Embodiment
Referring now to Figure 1, it will be understood
that, prior to welding with a radio frequency beam head,
asseml~ly of each battery cell jar is required. As described
hereinafter, a novel method is provided for use in accomplish-
ing this assembly. Basically, a bushing 120 which is either
screwed or molded into a cover 121 is pierced by a battery
post 122 as shown in Figures 1 and 2 and a cooling ring 130
placed thereover, as will be described more fully hereinafter
in connection with Figures 12-14.
Referring now to Figure 3, the general axial
orientation of a single radio frequency beam head 123 over a
connector 124 of a motive power storage battery to be welded
is illustrated. According to one embodiment of the present
invention, a radio frequency beam head 123 having a cooling
ring 130 mounted in cooperation therewith is axially intro-
duced into engagement with each connector 124 to be welded
to each "button", indicated generally by the arrow 125, of a
sealed battery cell. Alternatively, it is anticipated that
with increased power, the battery post 122, bushing 120 and
connector 124 can all be welded in a single operation.
Referring now to Figure 4, the preferred axial
orientation o~ the radio frequency beam head 123 over the
post 122 is shown, and a cooling ring 130 is illustrated as
being fitted to encircle the sleeve or bushing 120 and the
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post 122 contained there~ithin. In Fi~ure 5, a sll~htly
different lead flange 126 and battery post 127 are illustrated,
and a cooling ring 128 is shown which is adapted to bridge
more than one battery post 127 so that a single coolinc~ riny
128 can service more than one radio ~requency beam. While
Figures 4 and 5 illustrate traditional rubber cover designs,
it is anticipated that "poly" covers and jars will be used
and heat sealed in accordance with the preferred embodiment
batteries to be produced therewith.
Figures 6, 7, 8, 9, 10 and 11 illustrate various
preferred embodiment cooling rings for mounting on the welding
carriage 110 of the apparatus 118 shown in Figures 12-14;
Maximum clearance is illustrated between the cooling rings to
facilitate welding terminals which are located on either side
o~ the fill hole of a battery cell being assembled. In the
preferred embodiment, cooling fluid is introduced into and
circulated through these cooling rings as shown by the arrows
131 in these figures. In order to maximize cooling efficiency,
these cooling rings are preferably composed of aluminum.
Referring now to Figure 12, the preferred embodi-
ment welding station 132 of the present invention is illus-
trated. A welding carriage, designated generally as 100, i5
adapted for reciprocal, vertical movement along a plurality
of rails 133 at the four corners thereof, so that the
carriage 100 may be moved downwardly -to engage battery cells
which are located on the conveyor 134 and which are maintained
~ in position by retractable rams 102. Located above the cooling
rin~s 101 on the carriage 100 are a plurality of beam nozzles
109. These beam nozzles 109 may be of a type generally
illustrated in U.S. Patent Nos. 3,894,209 issued July 8, 1975
to Sirius Corporation and 3,648,015 issued ~arch 7, 1972 to
Thomas E. Fairbairn.
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As defined in the abstract of U.S. Patent No. 3,648,015,
each beam nozzle generally comprises "an electron beam torch
whose flame is generated by high power ra~io ~requency pro-
vided by a modified high fre~uency transmitter. The mechanical
structure of the torch is comprised of an electrode held
within a metal nozzle, which is attached by means oE a metal
tube to a high voltage low current point of the final OUtptlt
tank coil of a modified output circuit or amplifier. An
amount of inert or other gaseous media is u-tilized to enclose
the electron beam torch flame immediately adjacent to the
torch nozzle orifice, to (l) provide a shield and focus the ~t
flame on the work piece, (2) to cool the torch nozzle and prevent
the electrode from melting and oxidizing and (3) to vary the
temperature of the work piece."
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 RF generator 106, which is disposed
immediately behind carriage frame 108. A control station 110
to control gas flow through the gas lines 111 to the network
module 104 is supplied by tanks 112, 114 and 116.
Referring now to Figure 13 which a front view of the
apparatus 118 shown in Figure 12~ water lines 113 are shown
communicating with the welding carriage 100 for the purpose
of providing a coolant to cooling rings 101. Since dissipation
of gas in the vicinity of th~ weld is important, it has been
found that the axial positioning of the beam nozzles 109 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 weld area
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will be carried immediately away from that area and will not
interfere with continuing welding operations.
Referring now to Figure 14 which is a top view o~ -the
apparatus 118 illustrated in Figllres 12 and 13, the rela~ive
orientation of the various components of the apparatus 118
are clearly illustrated. Beam nozzles 109, for example, are
shown oriented within a plane traverse to the advancement o~
the conveyor 134, so that adjacent, spaced apart terminals
on individual cells may be welded therewith.
Referring to Figures 12-1~, it will be seen that the
preferred embodiment welding station 132 of the present
construction will simultaneously weld together two terminals
on the cell cover 121 to a required weld depth o~ approximately
3/8ths of an inch, and will accomplish 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 will be 20.25
inches high. The cells enter the apparatus 118 one at a time,
and stop beneath the cooling rings 101 in delayed response
to a photo-electric cell 115, shown on the carriage assembly
100. The cooling rings 101 reciprocate above the cover 121
to selectively index against the cell cover bushings 120.
When the cooling rings 101 are properly indexed, twin beams
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 121 of the jar when moved
thereacross (as for example between 0 and 100 watts). Then
the cooling rings 101 rise and the cell is moved forward
untii two more bushings are indexed into position. For those
jars having more than one pair of bushings and terminals to
be welded, the machine will index through as many positions
as are needed, until each of the terminals have been welded.
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The maximum c~cle time is 15 seconds per cell ~or a two
bushing cell, and 30 seconds per cell ~or a ~ or 6 ~ushiny
cell.
In the preferred embodiment, the beam settinys should
be varied in order to accommodate strength, time per weld,
gas flow rates, appropriate cooling rinys to Eit corresponding
bushings, center-to-center bushing distances, and finally
module height adjustment and lock; to insure thak 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
fre~uency beam generated, for example, of the type available
~rom Energystics, Inc., of Toledo, Ohio, is capable of
consistently welding two industrial battery terminals,
simultaneously, to a minimum depth of 3/8 of an inch. In
thls regard, in the preferred embodiment, high quality welding
is insured 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.
In the preferred embodiment, the beam is oriented
vertically downwardly onto the center of-the cell terminal.
The nozzle design and gas flow are chosen to focus and give
momentum to the beam in a manner which is sufficient to con-
centrate the beam, to push the previously expelled gas away
from the area, and to pravent lead oxide vapor from travelling
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 plas~ic cover has been found to be
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satisfactory. ~loreover, the preferred embodiment coolin~
ring comprises edges 117 in the weld area which are bevelled
in order to prevent beam attraction, so that the beam will
not tend 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 119 of the ring is prefera~l~
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 toleratea
between the post 122 and cover bushing 120. 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 if the gap is above 0.020 inches per side~ the beam may
arc down the post, in a skin effect, into the cell. By main
taining the top surfaces of the post 122 and bushing 120 at
equal heights, the depth of weld is maximized.
Accordingly, the following normal operating parameters
are recommended for both standard, and 5 anll 7 plate c~ll
tenllinals:
1. Gas flow rates - Core (helium) - 17.5 scft/hr -~ 1
Sheath (helium) - 1 scft/hr + 1,-0.5
Sheath (hydrogen) - 5 scft/hr J~ 1
2. Beam power - true value (total minus reflected) - 4 to
4.5 KW (reflectQd 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 of post and co~er
bushing - 0.5 inches ~ .0625".
6. Re~arding beam nozzle to be used, the tip should protrude
about 2.5" from the sheath. Tip diameter is about .5625";
sheath diameter is about 1.25". Both sheath and tip must
be fully insulated with boron nitrate or molybdenum.
7. Beam to impin~e on the center of the post, no more than
.0625" to any side of the post.
8. Post height should be equal to bushin~ heigh-t,
-~.031", - .093".
9. Post to cover bushing fit - maximum gap of .010" per
side (.020" i~ all on one side) at the top o~ the post
and bushing.
10. Cooling ring fit over exposed top of bushing does
not have to be tight. Cooling ring diameter can he up
to .0625" greater than bushing outer diameter.
In alternate embodiments of my invention, the beam
welding of automotive terminals and bushings is contemplated.
In one such embodiment, tests were run with half an
industrial post being tack welded to a partition by a beam
angled downward at 45. The energy level and time required
were considerably less than that needed for industrial
terminal welding, and a beam o~ 250 watts for six seconds
was capable of gaining the tack weld described above. In
this embodiment, however, the concentration of the beam must
be controlled to p~ev~nt melting through the bushing and
nto the plastic at the point of maximum direct impingement.
~One approach for preventing such melt through includes
varying the duration of the beam to produce a satisfactory
weld. By the same token, the positioning of parts to be
welded is critical, while the problems with gas dissipation
are not as severe as those encountered with industrial
battery terminals, as described above. ~ocation of the beam
nozzle approximately one inch from the parts to be welded is
believed to be satisfactory for this embodiment.
The beam power of 4 to 4.5 kilowatts is presently pre-
ferred, however, adequate welds have been obtained using a
beam power of as little as 3 kilowattsO
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