US2582946A

US2582946A - Flame method of cutting metal

Info

Publication number: US2582946A
Application number: US34238A
Authority: US
Inventors: Warren E Brill
Original assignee: Individual
Current assignee: Individual
Priority date: 1948-06-21
Filing date: 1948-06-21
Publication date: 1952-01-22
Anticipated expiration: 1969-01-22

Description

Jan. 22, 1952 w. E. BRILL FLAME METHOD OF CUTTING METAL Filed June 21, 1948 INVEN TOR. ZL/arren E. Brill BY 7M WM arr-45y; y

Patented Jan. 22, 1952 UNITED STATES PATENT OFFICE Claims.

This invention relates to the art of subjecting metal to the action of heat supplied by an oxyacetylene (or similar) flame for the purpose of melting, cutting, severing, gouging, beveling, cleansing or inspecting the metal.

The conventional oxy-acetylene process of cutting ferrous metals depends for its operation upon the rapid chemical action between the white-hot metal and a stream of pure oxygen. Thus, while the prior art is replete with cutting torches, all such tools may be said to consist, essentially, of a blowpipe having a nozzle from which there emerges (l) a flame consisting of a mixture of acetylene (propane or other fuel gas) and oxygen, usually in the proportion of oneto-one, capable of heating a spot on the iron or steel to a white-hot temperature and (2) a discrete stream of substantially pure oxygen, under pressure.

A In the hands of a skilled workman modern oxyacetylene torches are susceptible of many uses. Thus, they may be employed in cutting through even the thickest steel, in piercing holes in iron or steel and also in beveling and gouging operations upon ferrous plate or pipe stock. The use of present-day torches, however, is subject to certain limitations. By way of example, such torches can be used only upon ferrous metals since, as is well known, non-ferrous metals do not form oxides that will ignite when subjected to the high-pressure oxygen stream.

Accordingly, it is an object of the present invention'to provide a novel method of cutting both ferrous and non-ferrous metals.

Another limitation upon the use of present day torches is manifest in the cutting of high carbon steel. Here the oxygen stream from the high pressure valve has a rapid cooling action upon the hot metal. As a result of this rapid cooling action numerous small cracks are formed in the metal adjacent to the cut. Therefore, in cutting away the riser or sprue of a casting constituted of high carbon steel the cut must be made a substantial distance from the body of the casting so that the said cracks will be confined to a stub which, subsequently, must be machined off, as on a lathe. The high cost of machining-away a large stub frequently dictates the use of forgedmetal in instances Where cast-metal might be used were it not for the trouble and expense of removing the riser or sprue from the casting.

Accordingly, another object of the invention is to provide an improved flame method of cut" ting high carbon steel, and one which may be practiced without producing cracks or other defects in said metal.

Another very real objection to present day oxyacetylene torches is that they are incapable of that nice degree of control which would permit theiruse in the removal, say, of boiler tubes or rivets, without danger of scoring or otherwise scarring the metal in which such parts are usually seated. The same lack of control imposes a lower limit (say of an inch) upon the thickness of the metal which can be subjected to the cutting or gouging action of a conventional torch.

Accordingly, another object of the present invention is to provide a method which shall lend itself readily to the removal of metal from stock of substantially any thickness dimension, and this too Without deleterious effects upon the surrounding metal in the event of an accidental or temporary loss of control of the torch while it is in use.

Yet another object of the present invention is to provide a novel method of making an on-thespot inspection of welded metal.

In the above connection it will be recalled that, up to now, the only means available for revealing sub-surface defects in welded metal comprise (a) X-rays and (b) so-called supersonic or vibratile methods. The limitations upon the use of such test methods and equipments are so serious that, as a practical matter, the only weldinsurance that is acceptable to large-scale users of welded metal is the high standards which they have established as to the skill and experience of the persons entrusted with making the welds. As will hereinafter more fully appear, the present invention by providing a simple and convenient method for making a non-destructive (or easily reparable) sub-surface exploration of the metal, permits the use of welding in instances where welding has not heretofore been used because of the absence of a satisfactorily convenient means of inspecting the metal after it has been welded.

Another and important object of the invention is to provide a truly low pressure flame method for the cutting etc. of metal, and thus to effect substantial savings not only in operating expenses but also in the cost and weight of the torch and its accessories.

The foregoing and other objects are achieved in accordance with the method of the present invention by mixing oxygen and acetylene (propane, or other fuel gas) in the proportions required to provide a neutral flame, when the mixture is ignited, then subjecting the surface metal to be cut to said flame for a period sufficiently long to provide a drop or small puddle of molten metal upon said surface and then increasing the force or pressure back of the flame (as by controllably increasing the amount and pressure of the oxygen in the mix) in order to blow the molten metal away, from its area of origin, without burning it or scoring the surrounding metal.

As will hereinafter more fully appear in cannection with the description of the accompanying drawings, a conventional "cutting torch (1. e. one having a lever actuated, high-pressure oxygen valve) may be modified to permit the practice of the method of the invention by (a) blocking the opening through which the high pressure oxygen stream normally passes to the central nozzle opening", (2;) using said high pressure valve to control a low pressure stream of oxygen and (c) diverting said low pressure stream either within the torch or its nozzle, to the passageway through which the mixed oxygen and fuel gas flow. Alternatively, the method of the present invention may be practiced with a conventional cutting torch by providing the torch with a welding nozzle (i. e. one having a single oriflce) with its seat cut away in a manner later described.

Certain preferred details of construction and operation together with other objects and advantages will appear and the invention itself will be best understood upon reference to the following specification and to the accompanying drawing wherein: v v

Fig. 1 is a side elevation and Fig. 2 is a longitudinal sectional view of a cutting blowpipe constructed in accordance with the principle of the invention, I

Fig. 3 is a longitudinal section of an alternative form of blowpipe and nozzle within the invention,

Fig. 4 is a plan view showing the tip end of the nozzle of Fig. 3,

Fig. 5 shows a neutral flame and Fig. 6 shows a highly oxidizing flame emerging from the nozzle of Fig. 2 and Fig. 7 is a view in perspective showing the manner in which the blowpipe of the invention operates to cut a piece of metal.

The blowpipe used in the method of the present invention, as it is illustrated in Fig. 1, has

the outward appearance of a conventional cutof a handwheel 9 and lever II, respectively. If

desired separate inlet connections may be provided for the two oxygen pipes 8 and 10.

As is also conventional, the oxygen inlet pipe 8 extends a limited distance through the interior of the inlet pipe 5 for. the fuel gas and terminates in an injector or mixing chamber l2 where the said gases are mixed, preferably inthe proportion of one-to-one, solely under the set control of the handwheels 6 and 9, respectively.

In accordance with the present invention the combustible mixture in the injector or mixing chamber 12 instead of passing directly to the socalled pre-heat orifices of a conventional cutting nozzle passes through a combustiblemixture passageway l3 to a second chamber [4 adjacent to the nozzle end of the blow-pipe where the percentage and pressure of the oxygen in the mixture, and hence of the force or pressure in back of the flame, may be increased by the addition to the mix of oxygen supplied under the control of the lever-actuated valve I l in the second oxygen inlet pipe in. As previously indicated, the degree to which the force or pressure in back of the flame need be increased in the practice of the method of the present invention is very small and, ordinarily, need be no more than a pound or two. Hence the hose and other equipment used in the practice of the invention may be of light weight, yet safely-portable, construction. g

In the embodiment of the torch shown in Figs. 1 and 2 the nozzle 2 contains but a single opening 20!, through which the combustible mixture or mixtures in the chamber i4 pass. Alternatively, as shown in Figs. 3 and 4, when a flame of a greater circumference is required, the nozzle which is here designated 2' may be provided with several circumferentially arranged openings 21), 20 etc. vA nozzle similar to the one shown in Figs. 3 and 4 may be made from a conventional cutting-nozzle simply by plugging its central orifice and cutting-off (or cutting a passageway through) the end of the seat (indicated by the dotted lines M, Fig. 3) through which the cutting oxygen ordinarily passes to the said central orifice. With the nozzle thus altered it may be used with a conventional cutting torch in the practice of the present invention, since the space formerly occupied by the said seat now comprises a mixing chamber similar in function to the second mixing chamber E4 of the blowpipe shown in Fig. 2.

As previously indicated, the present invention provides a method of cutting metal which comprises the steps: (a) of subjecting a small area or spot on the exposed surface of the metal to a flame of a temperature and pressure calculated to convert the said spot into a stationary drop or puddle of molten metal and (b) increasing the pressure or force of the flame (as by increasing the amount and pressure of the oxygen in the combustible mixture) to a degree suflicient to blow away, or to merely upset, the said drop of molten metal.

The flame to which the metal is first subjected preferably, but not necessarily, comprises a so-called neutral flame i. e. one wherein the gases emerging from the tip of the nozzle comprise a one-to-one mixture of fuel gas and oxygen. Such a mixture may be achieved by manipulating the handwheels (6 and 9) of the blowpipe until the clearly defined inner cone 0 (see Fig. 5) characteristic of a neutral flame is achieved. The clearly defined inner cone of a neutral flame is from one-sixteenth to one inch long, depending upon the dimensions of the nozzle openings. If the size of the nozzle openings is increased, a larger flame will be produced since more of the combustible mixture can pass therethrough in a given time.

The alteration in the pressure or intensity of the flame required to blow away the molten metal produced by the neutral flame is obtained by pressing down the conveniently located lever H that controls the admission of pure oxygen into the second mixing chamber M. The increase in the force or pressure back of the flame which results from pressing down the hand lever II will ordinarily convert the neutral flame (Fig. 5) into one having the shorter cone 0' (Fig. 6) characteristic of a highly oxidizing" flame. The upper limit of the pressure increase may be fixed at the regulator (not shown) of the oxygen supply. If the regulator is set to pass say 12 lbs. and the hand wheel 9, when set to provide a neutral flame at 10 lbs. pressure, then, when the lever H ispressed down, the additional oxygen supplied to the mix can be no more than two pounds, making 12 lbs. in all. This increase in the pressure of the combustible mixture is not believed necessarily to be accompanied by any substantial change in the temperature of the flame. That is to say, the temperature of the flame remains sufficiently high to melt the metal, and yet is not so high as to burn the metal or convert it into slag. In any event the flame has no cooling action on the surrounding metal such as accompanie the release of the stream of cutting oxygen from a conventional cutting torch. Hence the present invention can be used upon high-carbon steel without producing cracks adjacent to the cut.

The technique involved in the cutting of metal in accordance with the method of the present invention is similar to that employed by welders in carrying a puddle across the surface of a piece of steel. Thus, referring to Fig. 7, when a puddle of molten metal has been created on the surface of the metal M to be cut by the action of the "neutral flame emanating from the nozzle (which may be of any convenient shape), and the pressure back of the flame has been increased (by pressing down the lever 1, Figs. 1 and 2), the nozzle is moved slowly over the surface of the cut. The said increase in pressure is sufflcient to blow the molten metal, gently outwardly, usually on both sides of the cut and to deposit it in the form of a friable deposit which may subsequently be brushed away. Since the temperature of the flame is not decreased by the described increase in the pressure or force of the flame, a fresh supply of molten metal is constantly presented to the nozzle. Should the pud dle be lost, as it may be if the torch is moved too rapidly, the operator returns the nozzle to the point where the cutting action ceased and creates a new puddle, preferably by letting-up on the hand lever II.

The gentle blowing away of the molten metal when the velocity of the flame or jet is increased by pressing down upon the lever H permits the torch of the present invention to be used in instances where the high pressure blast of the unignited oxygen from a conventional cutting torch could not be tolerated. One such use is the removal of tubes from a boiler for purposes of replacement. Here a conventional cutting torch cannot be used because of danger of scoring the boiler plates with the cold oxygen blast. Obviously, the use of the torch of the present invention presents no such hazard even in the hands of a careless workman. Similarly, if an attempt were to be made to use a conventional cutting torch to detect subsurface defects in welded metal, the high pressure oxygen blast might blow away the metal containing the defect which is intended to be exposed. On the other hand the absence of any blasting action in the use of the torch of the present invention permits the removal of even the thinnest layer of metal Without risk o the underlying or rounding metal.

From the foregoing, it will now be apparent that the present invention provides a novel and economical flame method of subjecting metal to the action heat supplied by an oxy-acetylene or similar flame for the purpose of melting, cutting, severing, gouging, beveling or inspecting the same.

What is claimed is:

1. A method of cutting metal which consists in subjecting a surface portion of said metal to a flame produced by the ignition of a substantially uniform mixture of oxygen and a fuel gas for a period of time sufficiently long to create a increasing the pressure of said substantially uniform mixture of gases feeding said flame to a e sufficient to move said puddle of molten rectal away from its area of origin.

2. A method of cutting metal which consists in subjecting a surface portion of said metal to a flame produced by the ignition of a substantially uniform mixture of oxygen and a fuel gas, said flame being of a temperature and pressure suflicient to generate a puddle of molten metal on said surface, then increasing the pressure of said substantially uniform mixture of gases feeding said flame to a degree sufficient to blow said molten metal away from said surface portion, and then moving said flame along the part of the metal to be out while maintaining the temperature of said flame sufiiciently high to render said part of said metal molten.

3. The method of cutting metal which consists in subjecting a local area of the metal to be cut to a neutral flame, consisting of a substantially uniform mixture of oxygen and acetylene, for a period of time sufficiently long to convert the metal of which said local area is comprised into a puddle of molten metal, and then converting said neutral flame into a highly oxidizing flame consisting of a substantially uniform mixture of oxygen and acetylene of a pressure sufflciently high to move said molten metal away from said local area.

4. The method of cutting a metallic body which consists in forming an ignited combustible gas jet of low velocity, directing said low-velocity jet upon the metallic surface of the body for a period sufiiciently long to convert a small area of said surface into molten metal, forming an ignited gas jet consisting of a substantially uniform mixture of oxygen and fuel gas of a velocity greater than that of said first mentioned jet, and directing said second mentioned jet upon said molten metal whereby to blow said molten metal away from said surface area.

5. The invention as set forth in claim 4 and wherein the temperature of said first and said second-mentioned combustible-gas jets are of the same general order, whereby the cooling effect of said second-mentioned jet upon said metal is minimized.

WARREN E. BRILL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 703,940 Menne July 1, 1902 866,866 Jottrand Sept. 24, 1907 1,311,815 Harris July 29, 1919 1,519,582 Harris Dec. 16, 1924 2,210,403 skinner Aug. 6, 1940 2,367,316 Skinner Jan. 16, 1945 2,425,709 Bucknam et a1. Aug. 19, 1947 2,441,179 Anderson May 11, 1943 OTHER REFERENCES The Oxy-Acetylene Handbook, 3rd printing, February 1945, pages 434-436, 440-442; published by Linde Air Products Co., New York.

Welding Research Committee of The Engineering Foundation, vol. 4, No. 2, February 1940, pages 52-s to 55-s (particularly pages 52-s and 55-s).

Claims

1. A METHOD OF CUTTING METAL WHICH CONSISTS IN SUBJECTING A SURFACE PORTION OF SAID METAL TO A FLAME PRODUCED BY THE IGNITION OF A SUBSTANTIALLY UNIFORM MIXTURE OF OXYGEN AND A FUEL GAS FOR A PERIOD OF TIME SUFFICIENTLY LONG TO CREATE A PUDDLE OF MOLTEN METAL ON SAID SURFACE, AND THEN INCREASING THE PRESSURE OF SAID SUBSTANTIALLY UNIFORM MIXTURE OF GASES FEEDING SAID FLAME TO A DEGREE SUFFICIENT TO MOVE SAID PUDDLE OF MOLTEN METAL AWAY FROM ITS AREA OF ORIGIN.