US3171599A

US3171599A - Powder flame spray gun nozzle

Info

Publication number: US3171599A
Application number: US262987A
Authority: US
Inventors: Anthony J Rotolico
Original assignee: Metco Inc
Current assignee: Metco Inc
Priority date: 1963-03-05
Filing date: 1963-03-05
Publication date: 1965-03-02
Anticipated expiration: 1982-03-02
Also published as: DE1245813B; GB978530A

Description

March 2, 1965 A. J. ROTOLICO 3,171,599

POWDER FLAME SPRAY GUN NOZZLE Filed March 5, 1963 AIR COMPRESSOR OXYGEN 3 FUEL POWDER INVENTOR ANTHONY J ROTOL/CO 0 EYS United States Patent Office 3,lll,5% Patented Mar. 2, 1965 3,171,599 POWDER FLAME SPRAY GUN NOZZLE Anthony J. Rotolico, Lynhrook, N.Y., assignor to Metco, Ind, Westbury, N.Y., a corporation of New Jersey Filed Mar. 5, 1963, Ser. No. 262,987 2 Claims. (1. 29-85) This invention relates to a new construction of a nozzle for a powder flame spray gun.

Powder fiame spray guns are devices utilized for spraying heat-fusible material, such as metal or ceramics which are fed to the gun in the form of a powder. As these guns are often used for spraying metal, they are sometimes commonly referred to as powder-type metal spray guns. These guns are often provided with burner jets for producing a conventional combustion flame and with means for conveying the powdered material to be sprayed, generally entrained in a carrier gas, through the flame, where the powder is melted or at least heat softened, and thence away from the gun, as for example onto a surface to be coated. United States Patent 2,961,335, of November 22, 1960, describes a powder-type flame spray gun. When operating the flame spray gun, as described in the said patent and other flame spray guns which were provided with a nozzle forming a combustion flame through which the powder was passed a phenomenon would sometimes occur which was known as nozzle loading. This phenomenon involved the sticking and solidification of the powder being sprayed on the nozzle face which after a period of time would interfere with the efficient spraying operation and necessitate interruption thereof and cleaning or even replacement of the nozzle.

This phenomenon would be more troublesome with the spraying of certain materials and when, for example, spraying powders which will exothermically react in the flame, the phenomenon is particularly emphasized and troublesome. Furthermore, when spraying these exothermically reacting powders, the same would become ignited in the flame causing a back-firing and interrupting the spraying operation.

One object of this invention is a new nozzle construction for a powder type flame spray gun which has a substantially reduced tendency toward loading during spraying even when spraying materials, in connection with which this problem was particularly pronounced, and does not have the prior art back-firing tendencies even when spraying exothermically reacting powders.

These and still further objects will become apparent from the following description read in conjunction with the drawing in which:

FIG. 1 is a vertical section of an embodiment of a nozzle in accordance with the invention,

FIG. 2 is a front elevation of the nozzle shown in FIG. 1,

FIG. 3 is a vertical section of a further embodiment of a nozzle in accordance with the invention,

FIG. 4 is a perspective view showing a still further embodiment of a nozzle in accordance with the invention mounted on an extension head, and

FIG. 5 is a vertical section of the nozzle shown in FIG. 4 with the extension head being diagrammatically shown. ni

Referring to the embodiment shown in FIGS. 1 and 2 of the drawing, 1 represents a nozzle body which is constructed of conventional material, as for example, leaded copper. The forward end of the nozzle body has a substantially fiat nozzle face 2. Eight burner jets 3, arranged in the form of a ring, are drilled through the nozzle body and terminate at the face 2. The intermediate portion of the jets has a slightly enlarged bore at 4 and terminates at the rear face of the nozzle body in the annular groove 5. A central powder conduit 6 is drilled through the nozzle body and is concentrically positioned with respect to the ring of burner jets 3. The forward end of the central powder conduit 6 terminates as a cylindrical extension '7 which projects past the Hat portion 2. on the face of the nozzle body.

An annular channel 8 is cut into the face of the nozzle body and is concentrically positioned between the central powder conduit 6 and ring of burner jets 3. The inner wall of the groove 8 is defined by the cylindrical extension 7.

A multiple number of air holes 9 radially extend through the side wall of the nozzle body in communication with the annular channel 8. In the embodiment shown eight such air holes are provided, one positioned between each pair of adjacent burner jets 3. The positioning of these radial air holes may be seen by the dotted lines in FIG. 2.

In operation, the nozzle is attached to the forward end of a powder type flame spray gun in the conventional manner, as for example by the use of a nut which screws on the forward end of the gun and which engages the flange 10 provided on the nozzle body. The nozzle may thus be connected to a gun of the type shown in United States Patent 2,961,335 in identical manner as the nozzle shown on said gun. The fuel and combustion supporting gas passages on the gun are in communication with the groove 5 in the rear face of the nozzle body and a combustible mixture of these gases, as for example acetylene and oxygen, passes from the groove 5 through the portion 4 of the burner jets and out through the burner jets 3 where the same is ignited forming a ring or sheath of flame surrounding the central powder conduit 6. The central powder conduit 6 is in communication with the means provided in the flame spray gun for feeding powder entrained in a carrier gas and the entrained powder passes through the conduit 6 out of the nozzle and within the flame sheath propagated from the ring of burner jets 3. The powder particles are melted or at least softened and propelled away from the gun, as for example onto a surface being coated. The action of the combustible gases passing through the burner jets 3 for combustion, and to a lesser extent, the passage of the entrained powder through the central powder conduit 6 aspirates ambient air into the air holes 9 and through the channel 3 around the cylindrical extension 7 forming an initial protective or buffer sheath of syphoned air between the powder as it leaves the central powder conduit 6 and the flame sheath.

In all respects the flame spray gun is operated in the conventional manner, as for example in the manner de scribed in United States Patent 2,961,335 and the nozzle is simply used in place of the nozzle shown in said patent.

With the use of the nozzle in accordance with the invention, however, the tendency toward loading with melted powder is substantially decreased even when spraying materials which normally have a pronounced tendency toward such nozzle loading, as for example, exothermically re acting powder, and the tendency toward back-firing is substantially reduced.

The embodiment shown in FIG. 3 is identical to that shown in FIGS 1 and 2 in construction and operation except that the cylindrical extension 7 is enclosed at its forward end at 11 and provided with a multiple number of jets 12, as for example eight jets equally spaced on a circle and which are divergent, i.e. directed outwardly from the axis of the conduit 6.

This embodiment is particularly adaptable for spraying ceramic and other high melting point material powders on passing through the central outer conduit 6 are V 3 diffused outwardly by the divergent direction of the jects 12 into the flame sheath.

The nozzle, as shown in FIGS. 421ml 5, is for use with a conventional extension head, as for example for spraying the inside of cylinders. In this embodiment the nozzle body is formed of three parts, i.e. the outer body 13, the intermediate cylindrical insert 14, and the inner cylindrical insert 15, which are all constructed of copper and may be assembled as an integral unit, as for'example with the

soldered joints

16 and 17. The intermediate cylindrical insert 14 has a multiple number of burner jets 19 which are arranged in the form of a ring and terminate at the flat nozzle face 18. The burner jets are in communication with the annular channel 211 formed between the outer body 13 and intermediate insert 14. A passage 21 in the outer body of 13 communicates the groove with a cylindrical socket bore 2 2 for the oxygen and fuel gas conduit 23 provided in the extension head 24. A central powder conduit 25 is provided in the inner insert 15 and nozzle body 13 and is concentrically positioned within the ring of burner jets 19. The central insert 15 form a cylindrical extension 26 of the central powder conduit 25 which extends past the fiat portion 18 of the nozzle face. A passage 27 in the body 13 communicates the powder conduit 25 with a cylindrical socket 28 into which the powder conduit 29 of the extension head fits. An annular channel 30/ is formed by the central insert 15 between it and the intermediate 14. This annular channel 31) is concentrically positioned between the central powder conduit 25 and the ring of burner jets 19. An annular groove 31 is provided in the body 13 and 7 this groove is in communication with the channel 30 by means of one or more passages 32 in the intermediate insert 14 A passage 33 in the body 13 communicates the groove 31 with the rear face of the nozzle body and a compressed air conduit 34 leadsthrough the extension head to an air metering jet 35, and thence to the passage 33. Air is fed through the air conduit 34 by meansof the air compressor diagrammatically shown. The nozzle body is held in place on the extension head by means of the threaded nut 36. V

V In operation, fuel and combustion supporting gases, as for example oxygen, acetylene, or the like, pass through the conduit 23 and the passage 21 into the grooveZQ and thence through the burner jets 19 where the same is ignited at the nozzle face. forming a ring or sheath of the flame. The powder is to be sprayed, entrained in the carrier gas, is passed through the conduit 29, the passage 27 and out through the central powder conduit 25 whence 'the same passes through the flame and is melted or at least heat softened and propelled against the surface to be coated. Compressed air from the air compressor is passed through the conduit 34, passes through the meter ing jet 35, passage 33, into the groove 31. From the groove 31, the air passes through the passage 32 into the annular channel 30 and out of the same as a buffer sheath of air between the entrained powder emerging from the central powder conduit 25 and the flame sheath formed from the ring of burner jets 19.

The spraying in all respects is effected in the conventional manner, and the extension may, for example, be positioned in a cylinder to spray the side wall thereof. With the construction, nozzle loading and back-firing tendencies are substantially surpressed.

The provision of the cylindrical extension of the central powder conduit passage and the annular channel surrounding the same through which air passes apparently sets up flow characteristics which prevent the conventionally occurring nozzle loading and back-firing tendencies. The cylindrical extension should extend past the nozzle face at least A of an inch and in connection with conventiontional nozzle sizes, having for example a central powder conduit with a diameter between and is preferably extended from t'o' about past the nozzle face.

In the embodiment in which the air passing through the annular channel surrounding the powder conduit is forced from a compressed air source, as contrasted to being aspirated, the extension may be dispensed with and the powder conduit may terminate flush with the nozzle face. In this embodiment, however, the air should be passed through the device at a flow rate of at least 0.3 s.c.f.m. and preferably from 0.5 s.c.f.m. to 1 s.c.f.m.

While the invention has been described in detail with reference to certain specific embodiments, various changes and modifications which fall within the spirit of the invention and scope of the appended claims will become apparent to the skilled artisan. The invention, therefore, is only intended to be limited by the appended claims or their equivalents wherein I have endeavored to claim all inherent novelty.

I claim:

1. A nozzle for a powder flame spray gun comprising a nozzle body terminating with a nozzle face having a substantially flat portion, a multiple number of burner jets arranged in the form of a ring in said body and terminating at the flat portion of said face, a central powder conduit extending through said body concentrically positioned Within said ring of burner jets and terminating as a cylindrical extension past said fiat portion of said face, an annular channel in said face, concentrically positioned between said central powder con duit and said ring of burner jets surrounding said cylindrical extension and a multiple number of air holes References Cited in the file of this patent UNITED STATES PATENTS 2,209,323 Corley July 30, 1940 2,643,955 Powers et al. June 30, 1953 2,890,419 Kough' July 23, 1957 V FOREIGN PATENTS 1,054,610 France Oct. 7, 1953 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,171,599 March 2, 1965 Anthony J. Rotolico It is hereby certified that error appears in the above numbered patent req'iiring correction and that the said Letters Patent should read as corrected below Column 2, lines 71 and 72, after "powders" insert in that the entrained powders column 3, line 21, for "form" read forms line 47, strike out "is"; column 4, line 12, for "conventiontional" read conventional Signed and sealed this 3rd day of August 1965.

(SEAL) Attest:

ERNEST W. SWIDER I EDWARD J. BRENNER Attesting Officer Commissioner of Patents

Claims

1. A NOZZLE FOR A POWDER FLAME SPRAY GUN COMPRISING A NOZZLE BODY TERMINATING WITH A NOZZLE FACE HAVING A SUBSTANTIALLY FLAT PORTION, A MULTIPLE NUMBER OF BURNER JETS ARRANGED IN THE FORM OF A RING IN SAID BODY AND TERMINATING AT THE FLAT PORTION OF SAID FACE, A CENTRAL POWDER CONDUIT EXTENDING THROUGH SAID BODY CONCENTRICALLY POSITIONED WITHIN SAID RING OF BURNER JETS AND TERMINATING AS A CYLINDRICAL EXTENSION PAST AND SAID FLAT PORTION OF SAID FACE, AN ANNULAR CHANNEL IN SAID FACE, CONCENTRICALLY POSITIONED BETWEEN SAID CENTRAL POWDER CONDUIT AND SAID RING OF BURNER JETS SURROUNDING SAID CYLINDRICAL EXTENSION AND A MULTIPLE NUMBER OF AIR HOLES RADIALLY EXTENDING THROUGH THE SIDE WALL OF SAID NOZZLE BODY IN COMMUNICATION WITH THE AMBIENT ATMOSPHERE AT ONE END AND IN COMMUNICATION WITH SAID ANNULAR CHANNEL AT THE OTHER END.