U.S. patent number 3,707,615 [Application Number 05/198,251] was granted by the patent office on 1972-12-26 for nozzle for a plasma generator.
This patent grant is currently assigned to Metco Incorporated. Invention is credited to Edwardo Romero, Anthony J. Rotolico.
United States Patent |
3,707,615 |
Rotolico , et al. |
December 26, 1972 |
**Please see images for:
( Certificate of Correction ) ** |
NOZZLE FOR A PLASMA GENERATOR
Abstract
An angular nozzle electrode for plasma generating devices is
disclosed. The nozzle includes an inlet end, an intermediate
portion and an outlet portion in angular relationship so as to
maximize the function and operational life of the nozzle
electrode.
Inventors: |
Rotolico; Anthony J. (Long
Island, NY), Romero; Edwardo (Medford, NY) |
Assignee: |
Metco Incorporated (Westbury,
L.I., NY)
|
Family
ID: |
22732603 |
Appl.
No.: |
05/198,251 |
Filed: |
November 12, 1971 |
Current U.S.
Class: |
219/121.47;
219/121.5; 219/76.16; 313/231.01 |
Current CPC
Class: |
B05B
7/226 (20130101); H05H 1/34 (20130101); H05H
1/3463 (20210501); H05H 1/3478 (20210501) |
Current International
Class: |
B05B
7/16 (20060101); B05B 7/22 (20060101); H05H
1/34 (20060101); H05H 1/26 (20060101); B23k
009/04 () |
Field of
Search: |
;219/75,76,121P,122
;313/231 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Truhe; J. V.
Assistant Examiner: Reynolds; B. A.
Claims
What is claimed is:
1. An angular nozzle electrode for a plasma generator, comprising a
nozzle body having a passage extending therethrough, at least a
portion of the wall of which is of electrically conductive
material, said passage having an inlet end, an intermediate portion
and an outlet portion terminating as an exit port, the axis of said
outlet portion extending at an angle to the axis of said inlet end
and at an angle to the axis of said intermediate portion greater
than 0.degree. but less than the angle to the axis of said inlet
end, whereby to define three distinct portions of said passage.
2. Angular nozzle electrode, according to claim 1, in which the
axis of said inlet end, intermediate and outlet portions extend at
angles to each other so that the sin of the angle between the axes
of the outlet portion and intermediate portion is about nine-tenths
of the sin of the angle between the axes of the outlet portion and
inlet end.
3. Angular nozzle electrode, according to claim 2, in which the
axis of said outlet portion extends at angles of about 45.degree.
to 90.degree. to the angle of said inlet end, and the axis of said
intermediate portion extends at an angle of about 4.degree. to
28.degree. to the axis of said inlet portion.
4. Angular nozzle electrode, according to claim 3, in which said
inlet end of said passage conically narrows to said intermediate
portion.
5. Angular nozzle electrode, according to claim 4, in which the
axis of said outlet portion extends at an angle of about 65.degree.
to the axis of said inlet end, and in which the axis of said
intermediate portion extends at an angle of about 10.degree. to
12.degree. to the axis of said inlet end.
6. Angular nozzle electrode, according to claim 5, including means
for feeding flame spray powder in front of said exit port.
7. Angular nozzle electrode, according to claim 6, forming the
nozzle electrode on a plasma flame spray gun, having a rod
electrode extending coaxially with the axis of said inlet end,
means for generating an arc between said rod electrode and said
nozzle electrode, and a source of plasma forming gas.
8. Angular nozzle electrode, according to claim 1, forming the
nozzle electrode on a plasma flame spray gun, having a rod
electrode extending coaxially with the axis of said inlet end,
means for generating an arc between said rod electrode and nozzle
electrode, and a source of plasma forming gas.
9. Angular nozzle electrode, according to claim 1, including
cooling fluid passages extending in the nozzle body surrounding at
least a portion of said first-mentioned passage.
10. Angular nozzle electrode, according to claim 1, including means
for feeding flame spray powder in front of said exit port.
Description
BACKGROUND OF THE INVENTION
This invention relates to nozzles for use with plasma flame
generators and in particular angular nozzles for use in plasma
stream apparata.
Plasma flame generators and spray guns utilizing an electric arc
and a flowing gas stream passed in contact with the arc are known
and have been used successfully for commercial and experimental
purposes. These devices generally consist of an electrode
arrangement striking an arc therebetween, a nozzle and means for
passing a stream of gas in contact with the arc and through the
nozzle.
In generators of the transferred arc type which are generally used
as torches for cutting, welding, and the like, the arc generally
extends from an electrode such as a rod electrode or a flat face
electrode, such as a disc, to the workpiece through a nozzle, such
as a cooled nozzle, while a gas stream is passed concurrently
through the nozzle with the arc.
In plasma flame generators of the non-transfer type, the arc is
struck between an electrode pair, one of which is in the form of a
nozzle, and the gas stream is passed in contact with the arc and
through the nozzle.
Plasma flame spray guns, in principle, merely constitute plasma
flame generators in which means are provided for passing a heat
fusable material into contact with the plasma stream where it can
be melted or at least softened and propelled, as for example, onto
a surface to be coated.
In U.S. Pat. No. 2,960,594 to Thorpe, a plasma generator is
described, in which the electric arc is constricted and elongated
and passed at least part way down a nozzle by means of a sheath of
plasma forming gas which, thus acting on the arc, is in itself
converted to the plasma energy state, may be utilized as a heating
medium. This plasma flame generator is well suited as the plasma
flame generating portion of the plasma flame spray gun as described
in U.S. Pat. No. 3,455,510 to Rotolico.
Plasma spraying into smaller holes or bores presents difficulty
with regard to accessibility of the area to be sprayed. For
purposes of coating such areas angular nozzles such as those
disclosed in the aforementioned U.S. patent to Thorpe were
necessary. In these devices the outlet portion of the nozzle
passageway is at a right angle to a central bore portion. While
nozzles of this construction effectively operate, they require
large quantities of cool water due to the large amount of heat
absorbed by the walls of the nozzle during the arcing process. In
addition, arcing within these angular nozzles causes erosion and
pitting in the passageway thereby necessitating frequent
replacement. Consequently, the use of this type of nozzle has not
proven to be practical.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to provide an
angular nozzle for a plasma flame generator which overcomes the
aforementioned disadvantages of the prior art.
It is another object of the present invention to provide an angular
nozzle electrode for a plasma flame generator which has a
relatively long operational life.
It is yet another object of the present invention to provide a
plasma flame generator angular nozzle which is capable of spray
coating into small holes or aperatures.
BRIEF SUMMARY OF THE INVENTION
These and other objects are accomplished in the present invention
wherein there is provided an angular nozzle electrode for a plasma
generator. More specifically, the invention relates to an angular
nozzle electrode having a nozzle body which contains a passage
extending therethrough, the passage containing an inlet end,
central intermediate portion and an outlet portion terminating as
an exit port in the nozzle body. The intermediate portion of the
nozzle passage extends at an angle to the inlet end and the exit
portion extends at an angle to the axis of the intermediate
portion. The angular nozzle electrode of the present invention
enables the determination of optimum angles between the portions of
the nozzle passage which results in a plasma gas directing medium
which is both durable and effective in plasma spraying
processes.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a vertical section of the angular nozzle electrode of the
present invention.
DETAILED DESCRIPTION OF THE DRAWING
AND SPECIFIC EMBODIMENTS
Referring now to FIG. 1, there is demonstrated the angular nozzle
electrode 10 of the invention. More specifically there is shown a
nozzle body 11 through which extends a nozzle passage of three
components, an inlet end designated as 12 which conically narrows
to an intermediate portion designated as 14, and an exit portion 15
terminating at exit port 19. Additionally, the particular
embodiment of FIG. 1 shows tubular blind bores 20 and 21 through
which a coolant such as water can be circulated. Nozzle body 11
contains ribs 16 which facilitate the affixation of the nozzle to a
plasma generator.
As can be seen from the FIG. intermediate portion 14 of the nozzle
is at an angle to the axis of the inlet end and the outlet portion
15 is at an angle to the intermediate portion 14 and at a greater
angle to the axis of the inlet end 12. The angle at which nozzle
component intermediate portion 14 deviates from the axis of the
inlet end 12 is designated as A and the angle at which outlet
portion deviates from the axis of the inlet end 12 is designated as
B. The difference between the two angles in the FIGURE is
designated as .DELTA.. It has been found that for optimum operation
of a plasma flame spray generator with the instant angular nozzle
electrode, particular angles for the intermediate and exit
portions, 14 and 15, of the nozzle can be established. These
particular angles enable a plasma generator to spray down into
small holes without loss of the durability characteristics of the
instant nozzle.
The optimum angular relationship between the intermediate portion
14 and the exit portion 15 of the angular nozzle has been
empirically established by the following formula:
sin (B - A) .congruent. 90% sin B
Using this empirical formula and optimum spraying angles for exit
portion 15, angle B, the corresponding angles for central
intermediate nozzle portion 14, angle A, can be determined.
To produce reasonably dense normal coatings it is necessary to
spray with an angle to the substrate surface of usually not less
than 45.degree.. Spraying the substrate surface at an angle of from
about 90.degree. to 45.degree. does not produce a very great change
in the coating structure. When using the present nozzle electrode
to spray into bores large enough to permit proper spray distance
from the nozzle exit port 19 to the area being coated then it is
preferable to have the angle of the exit portion, angle B, at or
near 90.degree. so that the spray strikes perpendicularly. For
holes which do not permit a proper spray distance, i.e., holes with
diameters less than 5 inches, an exit portion angle B of about
45.degree. is desirable. A practical all around preferred exit
portion angle B would be about 65.degree. .
Using the aforementioned empirical formula
sin (B - A) .congruent. 90% sin B
the angles of the intermediate portion 14, angle A, corresponding
to the optimum angles of B, 45.degree. to 90.degree. , are
calculated as being from 5.degree. to 26.degree.. For a preferred
angle B of 65.degree. the corresponding angle of A is about
10.degree. .
It is to be understood that the above cited angles of A have been
determined empirically by using the approximate formula referred to
above. Therefore, variations of plus or minus 2.degree. are
considered to be within the purview of the present invention.
Therefore, optimum angles of A would range from about 4.degree. to
28.degree.. It has been further established that a preferred angle
A, having an angle B at 65.degree., would be in the range of from
about 10.degree. to 12.degree. .
There is additionally shown in FIG. 1 a powder feed element 30
through which heat fusable material to be flame sprayed is fed. The
powder emanates from the powder exit port 31 and intersects the
plasma flame spray emanating from the plasma flame exit port 19.
Heat fusable material to be flame sprayed, as, for example,
powdered metal or ceramics which are conventionally sprayed in
devices of this type, is passed through powder-feed element 30 by
means of a small volume of a carrier gas, as, for example, inert
gas such as nitrogen, helium, argon or the like.
Again, referring to FIG. 1, nozzle 11 may be made of any
electrically conductive material as, for example, copper, copper
alloy, brass, aluminum, steel, or the like. However, the nozzle
body may be made of insulating materials as, for example, synthetic
resins, such as polyethylene, nylon or the like. In this instance,
all or at least a portion of the nozzle bore should be lined with
an electrically conductive material or provided with an
electrically conductive insert.
It is to be further understood that while cooling elements 20 and
21 were external tubular arrangements in the embodiments described
in FIG. 1, any means of cooling the present plasma carrying nozzle
electrode can be used. One example would be an annular
configuration surrounding the nozzle passageway.
The novel construction of the present angular nozzle is applicable
to all types of plasma generators and spray guns in which an
arc-forming electric current is passed from a rod electrode,
inserted at intake 18 and extending coaxially with the axis of the
inlet end 12 into the nozzle and which is provided with means for
passing a plasma forming gas in contact with the arc through the
nozzle. For example, the present nozzle, excepting its angular
configuration, is operable with a spray generator in the same
manner as the outwardly tapered nozzle of U.S. Pat. No. 3,145,287
to Siebein et al. In addition, the present angular nozzle may be
used in combination with any conventional extension tube.
While the invention has been described in detail with reference to
the embodiments shown, various changes and modifications which fall
within the spirit of the invention and the scope of the appended
claims will become apparent to the skilled artisan. The invention
is, therefore, only intended to be limited by the appended claims
or their equivalents.
* * * * *