US3226028A

US3226028A - Flame-spraying torch

Info

Publication number: US3226028A
Application number: US297844A
Authority: US
Inventors: Donald C Schilling
Original assignee: Eutectic Welding Alloys Corp
Current assignee: Eutectic Corp
Priority date: 1963-07-26
Filing date: 1963-07-26
Publication date: 1965-12-28
Anticipated expiration: 1982-12-28
Also published as: CH419918A; GB1016808A; AT266535B; CH422597A; AT281535B; DE1621866B1

Description

D' 1965 D. c. SCHILLING FLAME-SPRAYING TORCH 2 Sheets-Sheet 1 Filed July 26, 1963 INVENTOR Donald 0.8012]; llig %Ma%% 2 Sheets-Sheet 2 INVENTOR De 1965 D. c. SCHILLING FLAME-SPRAYING TORCH Filed July 26, 1963 United States Patent Ofiiice 3,226,028 Patented Dec. 28, 1965 3,226,028 FLAME-SPRAYING TORCH Donald C. Schilling, Fairview Park, Ohio, 'assignor to Eutectic Welding Alloys Corporation, a corporation of New York Filed July 26, 1963, Ser. No. 297,844 16 Claims. (Cl. 239-1) This invention relates to a torch for flame-spraying coatings upon surfaces, and it more particularly relates to such a torch which utilizes finely divided powder.

Flame-spraying torches are used for applying metal and plastic coatings upon surfaces by spraying them with powder-laden flame. Such torches utilize mixtures of combustible and combustion supporting gas such as acetylene and oxygen, which are susceptible to flash back and explosion. Flash back is particularly dangerous when it occurs in a powder container made of a relatively light material that is likely to fly apart into dangerous fragments.

An object of this invention is to provide a flame-spraying torch in which the danger of flash back is minimized.

Another object is to provide such a torch in which flash back will not occur in the powder supplying passages and container.

A further object is to provide a simple and dependable structure for such a torch.

In accordance with this invention powder is introduced into the passageway for the combustion supporting gas,

such as oxygen, before it mixes with the combustible gas, such as acetylene. The passageways for the gases are constructed and arranged to facilitate maintenance of an eflicient flame, such as a neutral flame of the desirable equal pressure torch type, when the pressure of combustion supporting gas is substantially greater than that of combustible gas. This prevents a combustible gas such as acetylene from flowing back within the torch from the point of mixture, and minimizes any flash back from occurring in the mixing chamber or in the powder supplying components. Explosions in the powder container are accordingly prevented.

Novel features and advantages of the present invention will become apparent to one skilled in the art from a reading of the following description in conjunction with the accompanying drawings wherein similar reference characters refer to similar parts and in which:

FIG. 1 is a side view in elevation of one embodiment of this invention;

FIG. 2 is a cross-sectional view taken through FIG. 1 along the line 22;

FIG. 3 is a full size view in elevation partially broken away in cross section of the embodiment shown in FIG. 1;

FIG. 4 is an enlarged three-dimensional view broken away in cross section of part of the embodiment shown in FIG. 3;

FIG. 5 is an enlarged front view in elevation of another part of the embodiment shown in FIG. 3; and

FIG. 6 is a cross-sectional view taken through FIG. 5 along the line 66.

In FIGS. 1-3 is shown a flame-spraying torch '10 having a tip =12 mounted in front of body 14. Separate longitudinal passageways 16 and 18 (shown in FIG. 3) extend part of the way through body 14 for respectively conducting a pressurized combustible gas such as acetykm and a pressurized combustion supporting gas such as oxygen through body 14. Gas injecting assembly or handle 20 including similar passageways 16 and 18 is connected to the back of body 14 as a convenient means of connecting a pressurized source of such gases thereto. The term pressurized is used herein in the usual engineering sense to refer to pressures above atmospheric pressure. Such pressures are also described as positive gauge pressures in common engineering terminology. A powder supplying passageway 22 having a valve 24 interposed in it is mounted upon body 14. Powder supplying passageway 22, valve 24 (both shown in FIG. 3) and powder container 26 and its mode of connection to body '14 are substantially similar to that described in commonly assigned copending application U84, S.N. 286,343 filed June 7, 1963, and details of their mode of operation and structure are described therein and later herein.

Referring to FIGS. 3-6, powder supplying passageway 22 intersects combustion supporting gas passageway 18 before passageway 18 enters mixing chamber 28 where it joins with acetylene passageway 16. A relatively restricted section 30 is interposed between passageway 18 and mixing chamber 28 to increase the velocity and decrease the pressure therein at the point where powder supplying passageway 22 intersects the passageway carrying the combustion supporting gas, such as oxygen. This facilitates the feeding of powder into the oxygen stream. Restricted low pressure passageway 30 is conveniently incorporate-d within nozzle tip 32 which is slightly spaced by conical powder insertion space 34 from transition tube 36 which carries the oxygen to mixing chamber 28. Intermediate passageways 38 and 40 respectively join restricted low pressure passageway 30 with supply passageway 18 and mixing chamber 28.

The aforementioned gas and powder mixing components are incorporated in a gas and powder mixing assembly 41 including nozzle 43, mixing tube 45 and intermediate sleeve 47 Sleeve 47 holds nozzle 43 and mixing tube 45 together and also feeds powder into the conical low pressure space 34 between them.

Nozzle 43 includes peripherally spaced passageways 49 (three for example distorted into the plane of FIG. 3 for the convenience of illustration) extending longitudinally through it for conducting acetylene through it between annular distributing grooves 51. A pair of longitudinal passageways 53 in sleeve 47 conduct the acetylene into annular groove 57 between sleeve 47 and central flange 55 of mixing tube 45. Three inwardly and forwardly inclined passageways 59 convey acetylene through central flange 55 from annular groove 57 into mixing chamber 28. Annular grooves 51 and 57 are actually formed by a pair of semi-circular annular grooves in mating surfaces. The contact of these mating surfaces about grooves 51 and 57 provides a dependable seal for the gas being conducted within them.

Sleeve 47 includes a pair of transverse passageways 63, one of which forms a continuation of powder supplying passageway 22 into communication with low pressure powder supply space 34.. The pair of transverse passageways 63 permits each of them to be disposed close to the ends of sleeve 47 thereby providing an appreciable distance between the one in line with powder supply passageway 22 and mixing chamber 28. The provision of an extra passageway 63 insures that one of them will be aligned with powder supplying passageway 22 either direction that sleeve 47 is assembled. Upon assembly, sleeve 47 is secured in place by insertion of the tip of drive screw 65 within slot 67 in sleeve 47.

The combustible gas such as acetylene is carried through passageways 16 and 53 into mixing chamber 28. Mixing chamber 28 is spaced from powder supplying space 34 and passageway 22 by intermediate passageway 40 to help isolate the powder supplying areas from the mixing chamber.

The structure of resilient insert 44 of valve assembly 24 is shown in detail in FIG. 2 to illustrate the vertical hole 46 through insert 44 that is opened and closed by reciprocal action of plunger 48 in response to movement of lever 50 and the reaction of coil spring 52. In FIG. 1 valve 24 is in the open condition with lever 50 depressed to allow hole 46 to remain open and to cause the powder to flow from container 26 through passageway 22 into space 34 and therefrom into the stream of oxygen.

The outer stem 71 of plunger 48 is inserted within a. bushing 73 of a natural lubricating material such as a tetrafluoroethylenepolymer which slides within sleeve '75 at the rear of the upper portion 77 of body 14. Lever 50 is rotatably connected to stem '71 by pin 79, and a lower extension 81 of lever 50 abuts against projection 83' upon body 14 to provide a fulcrum point for applying the force of lever 59 to reciprocate stem 75. Self-lubricating bushing 73, which is made for example of Teflon the trademark of a tetrafluoroethylene product of the Du Pont Company, facilitates the case, controlability and stability of operation of the lever 50, stem 71 and plunger 43.

Passagew ays l8 and 16 and continuations thereof up to mixing chamber 28 are proportioned to provide an efficient flame at the end of torch It), such as a neutral flame of the type provided in an equal pressure type of torch. The drawing is in approximate full size scale, and the proportions shown therein provide an efiicient operative arrangement when the pressure of oxygen is maintained between 16 to 25 pounds per square inch and the acetylene from 3 to 4 pounds per square inch. For smaller tip sizes a 16 to 18 pound per square inch oxygen pressure is operative with 3 pounds per square inch acetylene, and the higher pressures of oxygen up to 25 pounds per square inch are utilized for larger tip sizes. These pressures however are primarily illustrative in accordance with the specific torches described. In this arrangement roughly equal amounts of oxygen and acetylene are fed into the mixing chamber. In other words, the gases are mixed at the ratio of approximately one volume of oxygen to one volume of acetylene, but this ratio is subject to slight alteration when different powders are deposited.

The greater supply pressure of oxygen relative to acetylene, and the insertion of the powder into the oxygen stream at a point spaced ahead of the mixing chamber prevents the acetylene from flowing backwardly from the mixing chamber should a stoppage of gas flow occur at the tip, such as in backfiring. During backfiring, the higher pressure of oxygen blocks the flow of acetylene thereby preventing any explosive gas mixtures from being formed within the body of the torch, which might explode or sustain combustion within it to cause undesirable heating or burning out from flash back.

In the torch of this invention flash back is completely prevented no matter how rapidly the torch is backfired and relit by tapping its tip on a heated block. This torch is so safe from flash back that no explosion can be caused in the powder container even if a flame or spark is impinged upon the contents of the powder container. A flame directed into the powder container to illustrate a most extreme accident will cause its contents including a substantial amount of oxygen driven backwardly into it by intentional backfiring to burn, but only in a controlled manner without any danger of explosion. This is quite remarkable in comparison to the great susceptibility to explosion of the powder container of existing powder feeding flame-spraying torches where the powder is inserted into the mixed gases. Such existing torches are also quite prone to flash back, to which the torch of this invention is highly resistant.

What is claimed is:

1. A flame-spraying torch comprising a body, a tip section .disposed in front of said body, separate longitudinal passageways in said body for separately conducting a pressurized combustible and a pressurized combustion supporting gas partially through said body, a mixing chamber in said body, said passageway for said pressurized combustible gas joining said mixing chamber, a discharge passageway extending from said mixing chamber through the front of said body and said tip section for discharging gases from said mixing chamber, a powder Supplying passageway extending through said body into communication with said passageway for pressurized combustion supporting gas at an intersection therewith, said separate longitudinal passageways having means for facilitating maintenance of an efficient flame when the supplied pressure of combustion supporting gas is greater than the supplied pressure of said combustible gas, and an intermediate passageway connecting said intersection with said mixing chamber and conducting said greater supplied pressure of pressurized combustion supporting gas from said intersection to said mixing chamber whereby said powder supplying passageway is isolated from said mixing chamber to prevent said combustible gas from flowing backwardly into said powder supplying passageway from said mixing chamber and accordingly minimizing flash back.

2. A torch as set forth in claim 1 wherein a low pressure section is interposed in said passageway for pressurized combustion supporting gas at said intersection where it is intersected by said powder supplying passageway to facilitate introduction of said powder into said passageway for pressurized combustion supporting gas. l

3. A torch as set forth in claim 2 wherein said low pressure section is comprised by a relatively narrow section of said pressurized combustion supporting gas passageway followed by a larger diameter section slightly spaced therefrom, and said intersection being disposed at the space between said narrow and said larger diameter sections.

4. A torch as set forth in claim 1 wherein said mixing chamber has a cross-sectional area greater than said intermediate passageway whereby flashback is minimized.

5. A torch as set forth in claim 1 wherein the portion of said pressurized combustion-supporting gas passageway intersected by said powder supplying passageway is of relatively restricted cross section for reducing the pressure therein whereby introduction of powder is facilitated.

6. A torch as set forth in claim 1 wherein said passageway for pressurized combustion supporting gas is centrally disposed within the crosssectional interior of said body, and said passageway for said pressurized combustible gas being disposed outwardly within said cross-sectional interior of said body whereby said pressurized combustible gas is conducted about said intersection to said mixing chamber.

7. A torch as set forth in claim 1 wherein the portion of said passageway for said combustible gas that joint said mixing chamber is inclined forwardly.

8. A torch as set forth as claim 7 wherein said forwardly inclined portion of said passageway for said pressurized combustible gas includes a plurality of forwardly inclined passageways that join said mixing chamher.

9. A torch as set forth in claim 1 wherein said powder supplying passageway is substantially vertically disposed to pass down through said body to said intersection whereby it conducts thereto powder under the influence of gravity.

10. A flame-spraying torch comprising a body, a tip section disposed in front of said body, separate longitudinal passageways in said body for separately conducting a combustible and combustion supporting gas partially through said body, a mixing chamber in said body, said passageways joining each other at said mixing chamber, a discharge passageway extending from said mixing chamber through the front of said body and said tip section for discharging gases from said mixing chamber, a powder supplying passageway extending through said body into communication with said passageway for combustion supporting gas before it joins said mixing chamber, said separate longitudinal passageways being constructed and arranged to facilitate maintenance of an efficient flame When the supplied pressure of combustion supporting gas is greater than the supplied pressure of said combustible gas thereby preventing said combustible gas from flowing backwardly into said powder supplying passageway from said mixing chamber and accordingly minimizing flash back, said passageways and mixing chamber being incorporated within a gas and powder mixing assembly inserted within said body, said assembly comprising a nozzle having a tip and a flange, a mixing tube including a central flange disposed and connected between a transition tube and a discharge tube incorporating said mixing chamber, a sleeve disposed between said nozzle and said mixing tube having a transverse passageway alignable with said powder supplying passageway, the tip of said nozzle and said transition tube being inserted within said sleeve with a space between them which is aligned with said powder supplying passageway, said transverse passageway in said sleeve being aligned with said space to conduct said powder into it, and aligned peripherally spaced passageways extending through said nozzle, said sleeve and said central flange for conducting said combustible gas through said assembly into said mixing chamber in said discharge tube.

11. A torch as set forth in claim wherein said transverse powder supplying passageway is disposed adjacent one end of said sleeve for maintaining it spaced from said mixing chamber, and a pair of said transverse passageways are disposed equidistantly from the ends of said sleeve to facilitate the assembly of said sleeve in both directions with one of said transverse passageways aligned with said powder supplying passageways.

12. A torch as set forth in claim 10 wherein annular grooves are incorporated across mating surfaces of said assembly for facilitating sealing said combustible gas within said passageways through said assembly.

13. A torch as set forth in claim 10 wherein a central longitudinal passageway extends through said assembly for conducting said combustion supporting gas, and the portion of said central longitudinal passageway in the top of said nozzle adjacent said space is of relatively restricted cross section for minimizing the pressure in said space to facilitate the feeding of powder into it.

14. A process for flame spraying a fusible powder surface by means of a gas torch having a mixing chamber in which combustible and combustion supporting gas passageways join each other which comprises the steps of supplying said powder into said passageway for combustion supporting gas before it joins said mixing chamber, and maintaining the supplied pressure of combustion supporting gas greater than that of said combustible gas for preventing said combustible gas from following backwardly into said powder supplying passageway from said mixing chamber whereby flash back is prevented.

15. A process as set forth in claim 14 wherein said pressure of combustible gas is maintained approximately between 3 to 4 pounds per square inch and said pressure of combustion supporting gas is maintained approximately between 16 to 25 pounds per square inch.

16. A process as set forth in claim 14 wherein acetylene is supplied as said combustible gas and oxygen is supplied as said combustion supporting gas.

References Cited by the Examiner UNITED STATES PATENTS 1,617,166 2/1927 Schoop 239 2,671,689 3/1954 Wett 239-85 2,786,779 3/1957 Long et al. 239-85 FOREIGN PATENTS 551,077 9/ 1956 Belgium.

EVERETT W. KIRBY, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,226,028 December 28, 1965 Donald C. Schilling It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 6, line 5, for "top" read tip Signed and sealed this 3rd day of January 1967.

( L) Attest:

ERNEST W. SWDER Attesting Officer Commissioner of Patents EDWARD J. BRENNER

Claims

1. A FLAME-SPRAYING TORCH COMPRISING A BODY, A TIP SECTION DISPOSED IN FRONT OF SAID BODY, SEPARATE LONGITUDINAL PASSAGEWAYS IN SAID BODY FOR SEPARATELY CONDUCTING A PRESSURIZED COMBUSTIBLE AND A PRESSURIZED COMBUSTION SUPPORTING GAS PARTIALLY THROUGH SAID BODY, A MIXING CHAMBER IN SAID BODY, SAID PASSAGEWAY FOR SAID PRESSURIZED COMBUSTIBLE GAS JOINING SAID MIXING CHAMBER, A DISCHARGE PASSAGEWAY EXTENDING FROM SAID MIXING CHAMBER THROUGH THE FRONT OF SAID BODY AND SAID TIP SECTION FOR DISCHARGING GAS FROM SAID MIXING CHAMBER, A POWDER SUPPLYING PASSAGEWAY EXTENDING THROUGH SAID BODY INTO COMMUNICATION WITH SAID PASSAGEWAY FOR PRESSURIZED COMBUSTION SUPPORTING GAS AT AN INTERSECTION THEREWITH, SAID SEPARATE LONGITUDINAL PASSAGEWAYS HAVING MEANS FOR FACILITATING MAINTENANCE OF AN EFFICIENT FLAME WHEN THE SUPPLIED PRESSURE OF COMBUSTION SUPPORTING GAS IS GREATER THAN THE SUPPLIED PRESSURE OF SAID COMBUSTIBLE GAS, AND AN INTERMEDIATE PASSAGEWAY CONNECTING SAID INTERSECTION WITH SAID MIXING CHAMBER AND CONDUCTING SAID GREATER SUPPLIED PRESSURE OF PRESSURIZED COMBUSTION SUPPORTING GAS FROM SAID INTERSECTION TO SAID MIXING CHAMBER WHEREBY SAID POWDER SUPPLYING PASSAGE WAY IS ISOLATED FROM SAID MIXING CHAMBER TO PREVENT SAID COMBUSTIBLE GAS FROM FLOWING BACKWARDLY INTO SAID POWDER SUPPLYING PASSAGEWAY FROM SAID MIXING CHAMBER AND ACCORDINGLY MINIMIZING FLASH BACK.