US3352492A

US3352492A - Method of and apparatus for depositing metal powder

Info

Publication number: US3352492A
Application number: US47053A
Authority: US
Inventors: Arthur T Cape
Original assignee: Powder Melting Corp
Current assignee: Powder Melting Corp
Priority date: 1960-08-02
Filing date: 1960-08-02
Publication date: 1967-11-14
Anticipated expiration: 1984-11-14

Description

, Nov. 14', 1967 T A, T, CAPE 3,352,492

METHOD OF AND AP PARATUS FOR DEPOSITING METAL POWDER Filed Aug. 2. 1960 3 Sheets-Sheet 1 INVENTOR.

ARTHUR T. CAPE ATTORNEYS A. T. CAPE 3,352,492

METHOD OF AND APPARATUS FOR DEPOSITING METAL POWDER Nov. 14, 1967 3 Sheets-Sheet 2 Filed Aug. 2, 1960 JNVENTOR.

ARTHUR T. CAPE ATTORNEYS Nov. 14, 1967 A. 1'. CAPE METHOD OF AND APPARATUS FOR DEPOSITING METAL POWDER 3 Sheets-Sheet 5 Filed Aug Fig. /3

m ME D- m m fl w /E H R T A A M v. F B a m u a 3 5 4 w United States Patent 3,352,492 NEETHOD OF AND APPARATUS FOR DEPOSITING METAL POWDER Arthur T. Cape, Los Angeles, Calif., assignor to Powder Melting Corporation, Burbank, Califi, a corporation of California Filed Aug. 2, 1960, Ser. No. 47,053 2 Claims. (Cl. 239-85) This application is a continuation in part of application Ser. No. 635,717, now abandoned, which in turn is a continuation in part of application Ser. No. 406,918, now abandoned.

This invention relates generally to methods of and apparatus for depositing metal powders onto one or more base metal parts, for the purpose of providing facings resistant to corrosion and wear, for forming welded joints, or for other purposes.

Examination of the flame produced by an oxy-acetylene welding torch nozzle or tip reveals that the flame comprises an inner cone of unburned gases and an outer relatively cool cone in which all the carbon is consumed, and the color of which is bluish.

If metal powder is dropped into the bluish cone, at a point about one-third of the distance from the end of the distance from the end of the nozzle or tip to the end of the bluish cone, the powder is carried by the flame a maximum distance to the base metal or other part onto which the powder is to be deposited.

If the metal powder is dropped into the bluish cone at points closer than this to the end of the bluish cone or at points forwardly of this bluish cone, the distance of travel of the powder is progressively reduced, so that if the powder is dropped into the flame at a point somewhat in advance of the bluish cone, the distance of travel of the powder is about one-half that obtained when the powder is dropped into the bluish cone at a point about one-third of the distance from the end of the nozzle or tip to the end of the bluish cone.

This obviously means that a maximum velocity of the powder is obtained under the condition as first described above, and that this velocity is progressively decreased as the distance of dropping from the end of the nozzle or tip is increased.

It was also observed that if the powder is dropped into the flame under the advantageous conditions noted above, that a more uniform or equal distribution of powder is obtained with respect to the flame and with respect to the surface or object which is being coated or surfaced.

Additional experiments indicated that all of these advantages were also obtained in cases where the powder was dropped into the flame produced by a multiplicity of circumferentially-spaced jets, and irrespective of whether the powder was dropped onto the uppermost jet, or into the space between two of the jets, or at a point laterally of but reasonably close to one of the lateral jets, or even into the center of the nozzle, i.e., along the axis about which the circumferentially-spaced jets are disposed.

The present invention accordingly has as its primary object the provision of a method of the character described, wherein a stream of combustible gas is caused to emerge into the atmosphere to provide a flame for heating a surface to an elevated temperature, a supply of metal powder is provided, the powder is caused to flow, solely by gravity, in a stream such that it falls into a the blue cone of the flame in the manner which has been 3,352,492 Patented Nov. 14, 1967 Another object of the invention is to provide a method of the character described, which is characterized by a smooth flow of gases, which without turbulence, carries the powder to and firmly applies it to the base metal or surface to be coated.

A further object of the invention is to provide novel apparatus for practicing the aforesaid method.

A still further object of the invention is to provide novel apparatus of the character described, in which is incorporated means for eflectively and efliciently controlling the flow of the powder.

Other objects and advantages of my invention will become apparent during the course of the following description.

In the acompanying drawings forming a part of this specification, and in which like'numerals are employed to designate like parts throughout the same,

FIG. 1 is a side elevational view, showing a single jet flame of the character which has been described, and showing the effect of dropping the powder into the blue cone of the flame from a point above the blue cone;

FIG. 2 is a side elevational view, similar to FIG. 1, but showing the elfect of dropping the powder into the flame at a point just forwardly of the tip of the blue cone;

FIG. 3 is a front elevational view of the nozzle of an oxy-acetylene torch, having a series of uniformly and circumferentially-spaced jets or flames of the character which has been described, and showing the metal powder dropped into the space between the two uppermost jets;

FIG. 4 is a side elevational view of the nozzle of FIG. 3, and showing the point at which the powder is dropped, in relation to the length of the blue cones of the flames;

FIG. 5 is a front elevational view of the nozzle of an oxy-acetylene torch, having a series of uniformly and circumferentially-spaced jets or flames of the character which has been described and showing the metal powder dropped into the blue cone of the uppermost jet of the torch from a point above this jet;

FIG. 6 is a side elevational view of the nozzle of FIG. 5, showing the point at which the powder is dropped, in relation to the length of the blue cones of the flames;

FIG. 7 is a front elevational view of the nozzle of an oxyacetylene torch, having a series of uniformly and circumferentially-spaced jets or flames of the character which has been described, and showing the metal powder dropped at a point adjacent one of the lateral jets of the torch and at a point laterally of this jet;

FIG. 8 is a side elevational view of the nozzle of FIG. 7, showing the point at which the powder is dropped, in relation to the length of the blue cones of the flames;

FIG. 9 is a front elevational view of the nozzle of an oxy-acetylene torch, having a series of uniformly and circumferentially-spaced jets of flames of the character which has been described, and showing the metal powder dropped into the center of the nozzle, i.e., along the axis about which the circumferentially spaced jets are disposed; 7

FIG. 10 is a fragmentary cross-sectional view of the nozzle of FIG. 9 taken on the line 1010 of FIG. 9, and showing the point at which the powder is dropped, in relation to the length of the blue cones of the flames;

FIG. 11 is a side elevational view of a preferred form of apparatus for practicing the'method of the invention;

FIG. 12 is a fragmentary front elevational view of the portion of the apparatus of FIG. 11, which is opposite to FIG. 12;

FIG. 13 is a cross-sectional view, on an enlarged scale, taken on the line 1313 of FIG. 11;

FIG. 14 is a cross-sectional view, on an enlarged scale, taken on the line 1414 of FIG. 11;

FIG. 15 is a cross-sectional view, on an enlarged scale, taken on the line 1515 of FIG. 1 1;

FIG. 16 is a cross-sectional view, on an enlarged scale, taken on the line 16-46 of FIG. 11;

FIG. 17 is a cross-sectional view, on an enlarged scale, taken on the line 1717 of FIG. 11, and

FIG. 18 is a cross sectional view, on an enlarged scale, taken on the line 1818 of FIG. 11.

Referring to FIG. 1 of the drawings, reference numeral 1 designates generally a single flame, such as produced by a single jet 2 of an oxy-acetylene torch, and which flame comprises an inner cone 3 of unburned grass, and an outer cone 4 in which all of the carbon is consumed, and the color of which is blue or bluish.

When metal powder 5 is dropped into or onto the bluish cone 4, at a point 6 which is about one third of the distance from the end. of the jet 2 of the torch to the end of the bluish cone 4, the powder is carried by the flame a maximum distance to the base metal or other part onto which the powder is to be deposited, and in the form of a spray, as indicated in FIG. 1.

The powder acquires a maximum velocity, which is the velocity of the flame, and the flame heating the sur face which is to be coated, melting the powder during its transit to said surface, and causing the melted powder to become bonded to said surface. None of the powder is apparently carried by or in the peripheral portion of the main mass of the flame, the approximate boundaries of which are indicated by reference numeral 7. This portion of the flame is more or less luminous.

As the powder is thus dropped into the flame, it is uniformly or equally distributed with respect to the flame and with respect to the surface or object which is being coated or surfaced. 'Ihe flame carries the powder to such surface, with a minimum of turbulence, and firmly applies it to the base metal or surface which is being coated or surfaced.

As the distance of the point from the end of the jet 2, at which the powder is dropped into the flame, is in creased the distance of travel and the velocity of the powder are progressively reduced, so that if the powder is dropped into the flame at a point somewhat in advance of the bluish cone 4, in the manner shown in FIG. 2, the distance of travel of the powder is about one-half of that obtained under the conditions shown in FIG. 1.

In FIGS. 3 and 4, reference numeral 8 indicates the nozzle or tip of a conventional o-xy-acetylene torch, having in this case, six circumferentially-spaced openings 9, through which the combustible gas passes and is ignited to form in eifect, a single flame, but which actually consists of six distinct flames, each of the same character as that shown in FIG. 1 and of the drawings, that is to say, each flame comprises an inner cone 3 of unburned gases, and an outer cone 4 which is blue or bluish.

The metal powder 5, in this instance, is permitted to fall into the blue cones between the two uppermost flames, at approximately the same distance from the end of the nozzle or tip 8, as in FIG. 1. The powder spreads out in the manner shown in FIG. 3, is caught by the other flames of nozzle, and is thus carried by the main mass of the flame to the surface to be coated. The major portion of the powder becomes flame-borne before the center 9a of the nozzle is passed, and the remainder is picked up in the lower portion of thhe flame and merged with the powder in the upper portion of the flame. The feathery outer or peripheral portion of the flame, designated by reference numeral 10, apparently does not carry any powder at all.

The net result of thus introducing the powder to the flame of the multi-jet torch is approximately the same as that accomplished in FIG. 1, that is, the powder acquires a maximum velocity, which is the velocity of the flames, the flame or flames heat the surface which is to be coated, melting the powder during its travel, and causing the melted powder to become bonded to said surface. The powder, moreover, is uniformly or equally distributed with respect to the flame or flames, and with respect to the surface or object which is being coated or surfaced. This is accomplished with a minimum of turbulence, and the melted powder is firmly bonded to such surface.

In FIGS. 5 and 6, the conditions are the same as in FIGS. 3 and 4, except that in this instance, the powder is dropped so that it impinges on the blue cone of the uppermost flame or jet of the torch. The powder immediately surrounds the blue cone of this flame and is carried into the main mass of the flame. Some of the powder which passes beyond the influence of this cone is caught by the blue cones of the other flames or jets of the torch, but this represents only a very small portion of the powder which is supplied.

The net result, and advantages of thus introducing the powder are approximately the same as accomplished in FIG. 1.

In FIGS. 7 and 8, the conditions are the same as in FIGS. 3 and 4, except that in this instance, the powder is dropped in the manner shown in FIG. 7, that is, at a point adjacent one of the lateral flames or jets of the torch and at a point laterally of this flame or jet. If the point at which the powder is dropped is reasonably close to this flame or jet, the powder is pulled into the blue cone of this flame or jet and is thus drawn into the main mass of the flame, so that the net results and advantages are substantially the same as obtained in FIG. 1.

If the flow of powder is too great or heavy, or if the point at which the powder is dropped is not reasonably close to this flame or jet, some of the powder will fall to the ground.

In FIGS. 9 and 10, reference numeral 11 indicates the nozzle or tip or a conventional oxy-acetylene torch, having, in this case, six circumferentially-spaced openings 12 through which the combustible gas passes and is ignited to form, in effect, a single flame,.but which as in FIGS. 3, 4, 5, 6, 7 and 8 actually consists of six distinct flames, each of the same character as that shown in FIGS. 1 and 2 of the drawings, that is to say, each flame comprises as inner cone 3 of unburned gases, and an outer cone 4 which is blue or bluish.

In this case, however, the metal powder is introduced through a tube 13 which extends axially through the nozzle or tip, through the end plate 14 of the nozzle (which has the openings 12 therein) and to a point 15, which is approximately one third of the distance from the end of the nozzle 11 to the end of the blue cones of the flames.

With the nozzle in a vertical or substantially vertical position, as shown, the powder will fall through the tube 13 and be caught by the blue cones of the flames, and carried to the surface or object to be coated, in substantially the same manner as described in connection with FIG. 1.

If the length of the tube 13 is increased, so that its end extends beyond the ends of the blue cones of the flames, the effectiveness of the method is seriously reduced, and there are immediate signs of clogging of the powder feed, in addition to a marked decrease in the distance the powder is carried by the flame, due to the substantial drop in the velocity of the powder.

It is to be noted that the method of introducing powder into the flame, as described, with reference to FIGS. 1 and 3 through 10 inclusive, is substantially the same as that described in the application of Arthur T. Cape and Anthony M. Cirello, Ser. No. 406,918, filed Jan. 29, 1954 (now abandoned), and the copending application of Arthur T. Cape, Ser. No. 635,717, filed Jan. 23, 1957, of which applications the present application is a continuation-in-part.

In FIG. 10 of the aforesaid Cape-Cirello application, for example, the powder was introduced into the flame in such a manner as to be drawn into the flame, and carried to the surface by means of the flame. It was stated, in that application, that the powder outlet must be sufliciently close to the gas outlet, so that the powder will flow freely and independently of the flame, but will be drawn into the flame. It was further stated in that application that the powder was sprayed and melted immediately, essentially in a single operation, by means of the flame which carries the powder.

Although the specific nature of the flame was not discussed in that application, it is apparent that the invention with which the present application is concerned is essentially the same as that disclosed in the Cape-Cirello application, since the results, as stated in the preceding paragraph, are obtainable only under the conditions outlined in the present application.

In FIGS. 11 to 18 inclusive, I have illustrated a preferred form of spray gun or apparatus which I have found to be extremely well adapted for practicing or carrying out the method of the invention, as exemplified by FIGS. 1, 3, 4, 5, 6, 7, 8, 9 and 10 of the drawings, but more particularly that form of the invention discussed with reference to FIGS. 9 and 10.

Referring to FIGS. 11 to 18 inclusive, the apparatus will be seen to comprise an' oxy-fuel gas blowpipe or torch, which, except for the nozzle and certain other parts, is of conventional construction, including a mixer body or chamber 21, having

nipples

22 and 23 at its rear end for attachment of the chamber 21 to separate sources of oxygen and acetylene under pressure, respectively. Valves 24 and 25 are provided for the purpose of controlling the volume of oxygen and acetylene, respectively, delivered to chamber 21, and thus the proportions of the resultant combustible mixture leaving chamber 21.

The chamber 21 is attached at its forward end to a connector pipe 26, which is threaded to a stem 27, which, in turn, has threadedly connected thereto a discharge tip or nozzle, generally indicated by reference numeral 28.

The discharge tip or nozzle 28 comprises a tubular member 29, having an axial passageway 30, which, as shown in FIG. 16, communicates with a passageway 31 in the stem 27, and with a passageway 32 of enlarged diameter in the outer end of the member 29. The member 29 has soldered in its outer end a head 33, having an axial bore 34 and a plurality of circumferentiallyspaced openings 35 (see FIG. 17), for the passage of the combustible gases into the atmosphere.

Extending into the stem 27, in axial alignment with the nozzle 28, is a tube 36, which passes through the wall of the stem 27, as at 37, and through the nozzle member 29 and bore 34, in the head 33, terminating at a point 38, which is at such a point, in relation to the blue cones of the flames issuing from the openings 35, that powder issuing from the tube 36 will be caught by these blue cones, in the manner described with reference to FIGS. 9 and 10 of the drawings. In other words, the length of the tube 36 may be varied to produce optimum results, from the standpoint of distance of carry and velocity of the powder, but in' general, the tube should not be extended beyond the ends of the blue cones of the flames. The portion of, the tube 36 which passes through the bore 34 is press-fitted or soldered to the head 33.

The tube 36 thus provides a passageway for the powdered metal, which is supplied from a container 39, through flexible plastic tubing 40, a metal tube 41, and flexible plastic tubing 42, the latter being connected to the upper end of the tube 36.

The container 39 may be supported at any desired elevation, such that the powder may flow freely by gravity to the tube 36, irrespective of the position of the torch with respect to such container, the tubing 40 being of sufiicient length for this purpose.

Means have also been provided for controlling the flow of powder through the tubing 42.

For this purpose, the stem 27 has clamped thereto at its rear end, by means of a clamp 43 and screws 44, a support member 45 extending upwardly from the torch body, said support

member having arms

46, 47 and 48. The arm 46 has a flat outer face 49 (FIG. 13), against which the tubing 42 is adapted to be pressed for the purpose of collapsing the tubing to close the passageway therethrough. The arm 47 has mounted therein a pin or shaft 56), the ends of which provide a pivotal support for a bell-crank lever, which is retained in position by means of cotter pins 52. This bell-crank lever comprises a single casting consisting of parallel plates having downwardly extending

arms

53 and 54, rearwardly extending

arms

55 and 56, a cylindrical cross-piece 57 which interconnects the lower ends of the

arms

53 and 54 and is formed integrally with the latter, and a cylindrical cross-piece 58 which interconnects the upper ends of the

arms

55 and 56 and is formed integrally with the latter.

The bell-crank lever is normally maintained in the position shown in FIGS. 11 and 13, as by means of extension coil springs 59 which are connected at one end to a pin 60 which is mounted in the support member 45, and at the other end to a pin 61 mounted in the crosspiece 57. In this position of the bell-crank lever, the crosspiece 57 collapses the walls of the tubing 42 upon each other, as shown in FIG. 13, so as to prevent passage of powder through this tubing.

The arm 47 is provided with an extension'in the form of a clamp collar 62, in which the tube 41 is clamped by means of a screw 63 and nut 64. The tube 41 extends through the arm 47 to a point below this arm, at which it is connected to the tubing 42.

Mechanism has also been provided for withdrawing the cross-piece 57 relatively to the face 49 of the arm 46, so as to relieve the pressure on the tubing 42 to permit the latter to expand to permit passage of the powder therethrough. Such mechanism comprises a support 65 which is clamped to the connector pipe 26, as by means of a clamp 66 and screws 67 (see FIG. 15). The support 65 has laterally-spaced

ears

68 and 69, in which a pin or shaft 70 is mounted. Pivotally secured to the pin 70 is a trigger 71, provided with an upstanding lug 72, in which a pin 73 is mounted. A pair of

links

74 and 75 is pivotally secured'to the pin 73, and the forward ends of these links are pivotally secured to a pin or shaft 76 mounted in the cross-piece 58 of the bell-crank lever.

It will be apparent that upon depressing the trigger 71, the cross-piece 57 will be withdrawn from the face 49, through the medium of the

links

74 and 75 and the bellcrank lever, against the tension of the springs 59, and that upon release of the trigger, the tubing will be collapsed automatically by the cross-piece 57.

Means have also been provided for controlling the amount or quantity of powder flowing through the tubing 42. Such means is best shown in FIGS. 11 and 14, and comprises an adjusting screw 77 which is threadedly mounted in the arm 48 of the support member 45. This screw may be adjusted to any desired position, such that its tip 78 constitutes an abutment for the crosspiece 58,

when the trigger 71 is depressed, so as to adjust the extent to which the cross-piece 57 is moved relatively to the face 49, to thereby control the quantity of powder flowing through the tubing 42. The screw 77 may be locked in any adjusted position by means of a lock nut 79, which is brought to bear against the arm 48 for this purpose.

In manipulating the torch, the torch is held or gripped by means of the chamber 21, and the trigger is depressed by the thumb of the hand which grips the torch.

In the use of the torch the combustible gas mixture passes through the annular passageway, between the tube 36 and wall of the tubular member 29, into the passageway 32 and into the atmosphere through the opening 35 in the head 33, where the mixture is ignited to produce flames of the character described with reference to FIGS. 9 and 10.

The nozzle 28 is held by the operator at an inclination to the surface upon which the metal powder is to be deposited, the degree of inclination being illustrated somewhat diagrammatically in the drawing, but being variable to meet different conditions, such as the mesh size of the powder, the melting point of the powder etc.

After the surface to be coated has beeen heated by the flame to a temperature approaching its melting point, the flow of powder from the container 39 is started by means of the trigger 71, and the powder flows freely by gravity through the tube 36 to the point 38, where it enters and is caught by the blue cones of the flames formed by combustion of the combustible gas mixture.

The powder, is thus pulled into the flames and acquires the full velocity of the flames, the flames melting the powder and causing it to become bonded to the heated surface already described.

The method,'as described, is characterized by a smooth flow of the gases, which, without turbulence, carry the powder to and firmly apply it to the base metal.

The apparatus has incorporated therein means for effectively and efliciently controlling the flow of the powder.

It may be noted that in the use of the torch which has been described, the gas flow is in streams substantially parallel with the flow of the powder. The phrase substantially parallel, as herein used, is intended to include angles 'between'the axis of the powder flow and the direction of the gas flow of up to about 10 degrees, speaking only of the torch in which the powder flow is through the center of the nozzle, since excellent results are obtained within these limits. With an angle of convergence between the powder flow and gas flow of degrees, the streams will converge at a distance of about 3 /2 inches from the nozzle, and under these conditions I was able to greatly improve the speed and excellence of the application of a welded overlay, i.e., by spraying and melting. For example, when coating a steel cylinder, 2.7" in diameter and in length, I was able to form a completely sound deposit, .055" in thickness, at the rate of one inch per minute, as compared with conventional methods of spraying and melting which required half an hour for a tube of this length.

It will be understood that various changes'may be made in the method and apparatus described without departing from the spirit of the invention or scope of the appended claims.

I claim:

1. Apparatus for applying surfacing material to a work piece including a torch having a tip from which a flame jet system is, projected against the work piece, means for adjusting the rate of flow of gas to the flame jet system, a powder holder at a higher level than the torch tip, a nozzle with adischarge end outside the tip face and adjacent to the flame system and extending in a direction having a substantial vertical component, a passage connecting the powder holder and the nozzle and through which powder flows by gravity from the holder to the nozzle, valve means movable into difierent positions to obstruct totally or partially the flow of powder through the passage, manu- 8. ally-actuated means on thetorchoperably connected to the valve means for operating said valve means, a stop with which a portion of the valve means comes into con tact to limit the movement of the valve means toward open position, said stop being adjustable to change the maximum opening of the valve means, and said stop including manually-operated means outside of the torch for adjusting the maximum opening of the valve means and the resulting powder flow in accordance with adjustment of the rate of flow of gas to keep the powder flow within the carrying capacity of the flame jet system;

2. In a torch for supplying powdered metal or the like through a flame to a work piece, a torch body having a gas chamber therein and from which the gas is discharged through a tip, a tube extending upwardly from the torch body and communicating through a wall of the torch body with the flame, a cylindrical tube of resilient flexible material having walls which can be collapsed upon each other, said cylindrical tube communicating with said firstnamed tube and with a source of powder that falls through the cylindrical tube by gravity, a support member extending upwardly from the torch body, an arm pivoted to said support member and having means in contact with the said cylindrical tube, a spring urging said arm into position to pinch the cylindrical tube, means including a lever actuatable from a position adjacent to a handle portion of the torch body for actuating said arm in a direction away from said cylindrical tube, and an adjustable screw-threaded element on said support member and movable into diiferent positions for limiting the movement of said arm to various positions in which the cylindrical tube is open to any desired degree.

References Cited UNITED STATES PATENTS 1,128,059 2/1915 Schoop 117-105 X 1,536,952 5/1925 Udale et a1. 117-5.3 2,113,022 4/1938 Hefti 251-9 2,173,484 9/1939 Lerch et a1 117-105 X 2,366,424 1/ 1945 Perry 251-9 2,389,702 11/1945 Ullmer 117-105 X 2,549,736 4/1951 Wiese 239- 2,643,955 6/1953 Powers et al 239-85 2,671,689 3/1954 Wett 239-85 2,726,118 12/1955 Jones et'al. 239-85 2,786,779 3/1957 Long et al. 239-85 2,787,497 4/ 1957 Kough 239-85 2,820,670 l/1958 Charlop et al. 239-85 2,961,335 11/1960 Shepard 117-46 3,096,199 7/1963 Lamb 117-46 FOREIGN PATENTS 604,686 7/ 1948 Great Britain.

EVERETT W. KIRBY, Primary Examiner.

R. D. NEVIUS, L. J. DEMBO, Examiners.

R. E. ZIMMERMAN, R. S. STROBEL,

Assistant Examiners.

Claims

1. APPARATUS FOR APPLYING SURFACING MATERIAL TO A WORK PIECE INCLUDING A TORCH HAVING A TIP FROM WHICH A FLAME JET SYSTEM IS PROJECTED AGAINST THE WORK PIECE, MEANS FOR AJDUSTING THE RATE OF FLOW OF GAS TO BE FLAME JET SYSTEM, A POWDER HOLDER AT A HIGHER LEVEL THAN THE TORCH TIP, A NOZZLE WITH A DISCHARGE END OUTSIDE THE TIP FACE AND ADJACENT TO THE FLAME SYSTEM AND EXTENDING IN A DIRECTION HAVING A SUBSTANTIAL VERTICAL COMPONENT, A PASSAGE CONNECTING THE POWDER HOLDER AND THE NOZZLE AND THORUGH WHICH POWDER FLOWS BY GRAVITY FROM THE HOLDER TO THE NOZZLE, VALVE MEANS MOVABLE INTO DIFFERENT POSITIONS TO OBSTRUCT TOTALLY OR PARTIALLY THE FLOW OF POWDER THROUGH THE PASSAGE, MANUALLY-ACTUATED MEANS ON THE TORCH OPERABLY CONNECTED TO THE VALVE MEANS FOR OPERATING SAID VALVE MEANS, A STOP WITH WHICH A PORTION OF THE VALVE MEANS COMES INTO CONTACT TO LIMIT THE MOVEMENT OF THE VALVE MEANS TOWARD OPEN POSITION, SAID STOP BEING ADJUSTABLE TO CHANGE THE MAXIMUM OPENING OF THE VALVE MEANS, AND SAID STOP INCLUDING MANUALLY-OPERATED MEANS OUTSIDE OF THE TORCH FOR ADJUSTING THE MAXIMUM OPENING OF THE VALVE MEANS AND THE RESULTING POWDER FLOW IN ACCORDANCE WITH ADJUSTMENT OF THE RATE OF FLOW OF GAS TO KEEP THE POWDER FLOW WITHIN THE CARRYING CAPACITY OF THE FLAME JET SYSTEM.