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April 23, 1964
J. A. BROWNING
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3,131,288
ELECTRIC ARC TORCH
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Fileld Aug. 7. 1961
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INVENTOR. I
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United States Patent 0 " 1C6
3,131,288
Patented Apr. 28, 1964
1
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3,131,288
forces set up by the action of the vortex drive the heavier
liquid against the inner walls of the arc passageway.
This ?lm effectively cools and insulates the material of
ELECTRIC ARC TORCH
James A. Browning, Hanover, N.H., assignor to
Thermal Dynamics Corporation, a corporation of
New Hampshire
Filed Aug. 7, 1961, Ser. No. 129,750
1 Claim. (Cl. 219-121)
My invention relates to electric arc torches and relates
more particularly to a torch in which a plasma forming
gaseous element may be introduced to stabilize and be
heated by a high-pressure electric arc. Such torches are
the nozzle from the heat of the are 17. The arc creates a
plasma stream with the lighter gaseous element which
remains nearer the center of the vortex.
Since the cool
ing medium is on the interior surfaces of the nozzle pas—
sage it is possible to use materials of low thermal conduc
tivity for nozzle pieces, such as ceramics.
The rapidly rotating ?lm of cooling liquid passes down
ward (as seen on FIGURE 1) and emerges from the
torch in a diverging spray cone 18. The shape of this
well exempli?ed by the device shown in US. Patent No.
2,960,594, issued to Merle L. Thorpe.
cone may be controlled by vortex intensity, nozzle length,
and nozzle exit con?guration. I have found that the
amount of divergence is important in many practical ap
In accordance with my invention, I propose to add to
the conventional gaseous elements a liquid such as water.
plications, since water emerging too close to the zone of
The resulting dual mixture is preferably introduced into
operation may interfere with the heating (and in the case
a flow passage through which an electric arc is estab
shown) and cutting action. However, it is sometimes
lished. If this is done in such a way as to create a
desirable to provide a divergence just wide enough to
strong vortex, the heavier liquid particles will form a ?lm 20 avoid the desired heated zone, yet close enough to aid in
cooling the work piece in the areas not to be heated.
on the inside walls of the arc passageway for purposes
For example, in cutting thin metal plates the warpage of
hereinafter explained.
the sheet may be greatly reduced by supplying the cooling
It is, therefore, a principal object of my invention to
provide improved means for operating arc torches using
medium to the area immediately adjacent to the cut.
25
both liquid and gaseous elements.
I have also found it desirable in some instances to sus
It is a further object of my invention to employ the
pend small particles of an opaque substance in the liquid
methods thereof with minimum modi?cations of known
supplied to the torch. Fine particles of silicon carbide,
devices, thereby realizing the advantages at minimum
expense.
For a better understanding of the invention reference
is now made to the following detailed description and the
accompanying drawing, in which FIGURE 1 is a torch
of simpli?ed design, in longitudinal cross section; and
for example, further aid cooling action by markedly re
ducing radiation through the ?lm. In addition, the in
tense glare of the arc extending from the torch is attenu
ated by the resulting cone of opaque particles and liquid.
The liquid provides a practical vehicle for opaque par
ticles and I have found that the liquid ?lm has much
FIGURE 2 is a plan view of a swirl ring element used
greater ability to constrict and thereby control the arc
35 column than the use of a compressible gas alone. While
in the torch of FIGURE 1.
Referring now more particularly to FIGURE 1, a torch
this desirable action is not completely understood, I the
body 11 is shown containing an electrode 12, a swirl ring
orize that ionization levels in the annular region around
13 and a nozzle 14. These last three elements are held
the are are kept low and the arc is kept constricted much
securely by means of a nut 15 threaded on to the end
more
effectively. Thus higher current densities with
40
of the torch body 11. A tube 19 is used to supply a mix~
torches no larger than prior art devices are easily achieved.
ture of plasma forming gas and water (both under suit
While I have described a particular embodiment of my
able pressure) through a slot 21 and thence into annular
invention for illustrative purposes, modi?cations within
chamber 22 surrounding the electrode 12. The mixture
the spirit and scope of the appended claims hereto may
travels through tangential slots in swirl ring 13, best
occur to persons skilled in this art. For example, instead
shown in FIGURE 2, and enters the arc passage in the
of solid particles in suspension, a dye may be added to
nozzle 14 in the form of a strong vortex.
the liquid to increase its opacity. This is most effective
An electric arc is provided by supplying the torch with
in achieving the desired results.
a source of current, not shown, through lead 27, to the
I claim:
electrode 12. The electrical circuit is completed by the
The method of operating an electric arc torch of the
arc itself, shown at 17, the Work 25, and lead 26 con
type described, in which one or more plasma forming
nected to the source. It will be appreciated that the
gaseous elements are supplied under pressure to said
device is shown in the transferred mode of operation;
torch, comprising mixing a liquid with said gaseous ele
that is, the Work acts as the second electrode. If it is
ments, and introducing the resulting mixture under pres
desired that the are be wholly contained in the torch 55 sure tangentially into the arc passageway of said torch
itself, the nozzle 14 may serve as the second electrode in
to form a vortex driving the liquid portion of said mixture
which case the lead 26 would be attached thereto. Both
against the inner walls of said passageway.
of these modes of operation are well known in the prior
art, and this invention is applicable in either case. In
References Cited in the ?le of this patent
FIGURE 1, the device is shown being employed as a cut 60
UNITED STATES PATENTS
ting torch applied to the work piece 25.
Before reaching the swirl ring 13, the liquid portion
of the mixture introduced through tube 19 serves to pro
vide a cooling ?lm over the body of electrode 12. After
entering the passageway of the nozzle 14, the centrifugal 65
1,935,593
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2,768,279
2,906,858
Wist ________________ __ Mar.
Alexay ______________ __ June
Gaines _______________ __ Oct.
Rava ________________ __ Oct.
Morton _____________ __ Sept.
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