U.S. patent number 3,729,611 [Application Number 05/151,108] was granted by the patent office on 1973-04-24 for plasma generator.
This patent grant is currently assigned to Centrul de Sudura Si Incercari La Oboseala Timisoara. Invention is credited to Alexandru Vas.
United States Patent |
3,729,611 |
Vas |
April 24, 1973 |
PLASMA GENERATOR
Abstract
A plasma generator with a hollow electrode connected to a
venturi pump which draws a portion of the gas out of the arc
chamber in a direction away from the workpiece to stabilize a
molten-metal pool formed by the plasma generator. The withdrawn
portion of the gas is recycled to the region around the plasma arc
between the arc chamber and the workpiece.
Inventors: |
Vas; Alexandru (Timisoara,
RU) |
Assignee: |
Centrul de Sudura Si Incercari La
Oboseala Timisoara (Timisoara, RU)
|
Family
ID: |
26848331 |
Appl.
No.: |
05/151,108 |
Filed: |
June 8, 1971 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
721843 |
Apr 16, 1968 |
3594609 |
Jul 20, 1971 |
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Current U.S.
Class: |
219/121.36;
313/231.01; 219/121.55 |
Current CPC
Class: |
H05H
1/40 (20130101); H05H 1/42 (20130101); B05B
7/226 (20130101); H05H 1/3436 (20210501) |
Current International
Class: |
B05B
7/16 (20060101); B05B 7/22 (20060101); H05H
1/40 (20060101); H05H 1/42 (20060101); H05H
1/26 (20060101); H05H 1/34 (20060101); B23k
015/00 () |
Field of
Search: |
;219/121P,75,121R,74
;313/161 ;315/111 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Truhe; J. V.
Assistant Examiner: Peterson; Gale R.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of my application Ser.
No. 721,843 filed Apr. 16, 1968 and issued July 20, 1971 as U.S.
Pat. No. 3,594,609.
Claims
I claim:
1. A plasma-arc generator comprising:
a housing structure;
a nozzle received in said housing structure and having a mouth
adapted to be trained against a workpiece;
a tubular electrode mounted in said housing structure and extending
axially toward said nozzle while defining an arc chamber therewith
for generating a plasma therein;
means communicating with said arc chamber for introducing a
plasmogen gas thereto for conversion into a plasma and projection
through said nozzle as a plasma jet against said workpiece;
an annular piece spacedly surrounding said nozzle at the mouth
thereof to define an annular compartment opening inwardly toward
said workpiece; and
a venturi pump connected to said electrode and to said annular
chamber for inducing a portion of the plasmogen gas to flow away
from said mouth and said workpiece through said electrode in said
arc chamber and thereafter returning said portion through said
annular chamber, thereby reducing the velocity of said jet.
2. The plasma-arc generator defined in claim 1, further comprising
means for introducing metal powder into said annular chamber for
metallizing said workpiece.
Description
FIELD OF THE INVENTION
The present invention relates to improvements in plasma generators
of the type described in the above-identified application and
particularly to improved plasma generators with magnetic focusing
of the plasma and means for admitting supple-mental gases to the
arc chamber. The invention also relates to improved plasma
generators for cutting and welding metals and for coating materials
with metal, for metallization and for chemical reactions at high
temperatures in the metallurgical industries.
BACKGROUND OF THE INVENTION
Plasma generators of various types have been proposed heretofore,
such generators generally comprising a nozzle through which a gas
is induced to flow and an electrode arrangement for ionizing the
gas and converting the same into a plasma. The system may use a
transferred arc or a completely internal arc and is generally
connected to a source of gas at high pressure.
The mechanical forces at the nozzle, as a consequence of high-gas
velocity, often give rise to instability of a metal pool formed by
the plasma generator during welding or the like. Such high axial
forces may be required where metal cutting is desired but
represents a disadvantage where welding, metal cutting or the like
using a pool of metal is desired. It should also be mentioned that
it is known to provide tubular electrodes in a plasma generator,
mainly for introducing additives to the plasma stream.
OBJECT OF THE INVENTION
It is the principal object of the present invention to provide a
plasma generator which is more versatile and effective than the
plasma generator described in my prior application and which also
is able to overcome the disadvantages of prior-art plasma
generators as described above.
SUMMARY OF THE INVENTION
This object and others which will become apparent hereinafter are
attained in a plasma generator which, except as modified as
described below, will have the configuration and operating
modalities of the plasma generator described in the aforementioned
copending application. I have now found that it is possible to
stabilize the metal pool formed by the plasma generator when the
latter is not used for cutting, e.g., to obtain a stable metal bath
for welding, coating, remelting, alloy . . . , by reducing the
axial velocity of the jet emerging from the arc chamber of the
plasma generator, especially by inducing a low-pressure drop in
this chamber at the electrode tip. More specifically, I provide the
electrode as a tubular member through which a portion of a
plasmogen gas is induced to flow in a direction opposite the plasma
jet and from the axial zone of the arc chamber by an external
ejector (venturi pump) connected to the tubular electrode. The
extracted gas is then reintroduced into the nozzle in an exit zone
thereof between the nozzle member defining the outlet from the arc
chamber and an annular piece which covers this nozzle and defines
an angular space therewith. This space may also be used to
introduce a metal powder when metallization is effected.
DESCRIPTION OF THE DRAWING
The above and other objects, features and advantages of the present
invention will become more readily apparent from the following
description, reference being made to the accompanying drawing at
which the sole FIGURE is an axial cross-sectional view of the
nozzle region of a plasma generator according to the present
invention.
SPECIFIC DESCRIPTION
The plasma generator illustrated in the drawing comprises a tubular
electrode 1 and a nozzle body 2 supported with respect to one
another by a ceramic insulator 3. When the electrode 1 is replaced
by a solid rod, the apparatus can be used for metal cutting with
high jet velocity. When, however, the nozzle is tubular as
illustrated, e.g., for welding with a stable metal pool, it is
connected to the inlet 10 of a venturi ejector (venturi pump)
represented at 4 and located externally of the generator on a
suitable bracket as illustrated.
When the ejector 4 is operative, a portion of the plasmogen gas
Q.sub.p, introduced via the coupling 5 and passing through the
nozzle chamber 2 as represented by the arrows, is withdrawn and is
represented by the gas portion Q.sub.e.
From the venturi pump 4, the gas Q.sub.e is introduced via a
fitting 6 into the space between the nozzle 2 and an annular piece
7, the nozzle and this angular piece 7 defining a downwardly
converging annular chamber so that the gas emerging therefrom
focuses upon the imaginary conical apex which lies at the axis of
the generator and the pool Because of the reduced pressure in the
arc chamber (i.e., the chamber of member 3 in which an arc is
struck between the electrode 1 and member 2), the axial velocity of
the plasma arc or jet is reduced and impinges upon the workpiece P
with reduced force. As a consequence, the hot metal bath remains
stable. Of course, when the system is operating with a transferred
arc, the arc passes from member 2 to the workpiece P.
When the plasma generator is used for alloying, metal powder is
introduced into the plasma arc together with a supplementary gas
Q.sub.s. The powder is thus carried by the gas traversing the space
between piece 7 and nozzle 2. When the generator is used for
chemical reactions or metallization, gas subject to the reaction or
metallization powder can be introduced at the top of electrode 1 or
through fitting 6 or both.
The venturi pump (ejector) 4 comprises a nozzle 8 through which the
supplementary gas portion Q.sub.s is introduced. Around the nozzle,
in accordance with the venturi principle, a low pressure is
produced at 9, thereby drawing gas in through fitting 10. The gas
then flows through outlet 11 into fitting 6.
* * * * *