US2210402A - Method of removing metal from metallic bodies - Google Patents

Description

Aug. 6, 1940- J. M. GAINES. JR-

METHOD 0F REMOVING METAL FROM METALLIC BODIES Filed Feb. 27, 1937 FIG.2

INVENTOR JOHN M. GAINES JR.

ATTORNEY Patented Aug. 6, 1940 UNITED STATES METHOD OF REMOVING METAL FROM METALLIC BODIES John M. Gaines, Jr., Kenmore, .N. Y., assignor to The Linde Air Products Company, a corporation of Ohio Application February 27, 1937, Serial No. 128,088

10 Claims.

This invention relates to the art of thermochemically removing metal from metallic bodies, and more particularly to a method of cutting metallic bodies in which a stream of oxidizing gas,

such as oxygen, is applied to a heated portion of the metallic body to be cut.

It has been customary in such cutting or metallic bodies, particularly those composed of iron or steel, to heat a portion of the body to a sumciently high temperature, usually designated as the kindling temperature, by means of a high temperature preheating flame, such as that produced by the combustion of a mixture of oxygen and acetylene; and then to direct a relatively 16 high velocity jet of an oxidizing gas, preferably substantially pure oxygen, upon the portion previously heated to the kindling temperature so that the iron or steel upon which the cutting jet is directed will be partially converted to the oxide and swept away by the action of the high velocity jet. Such high velocity jets usually have a velocity of between 600 and 1800 feet .per second. By a. progressive movement of the blowpipe nozzle across the metallic body, a portion of the body, substantially corresponding in width to the cutting jet, may be removed and a cut or kerf produced along a line corresponding to the path of movement of the blowpipe.

However, since the upper edges of the kerf will not be maintained at the kindling temperature during cutting, due to the cooling'action of the high velocity jet, the lack of suflicient rapidity of heat conduction through the steel to the upper edges of the kerf, and, the usual presence of millscale on the upper surface of the steel, it is necessary to supply heat to the metal undergoing cutting, in addition to the heat produced by the combustion of the iron or steel. To supply this additional heat, the preheating flames have been applied to that portion of tlie body being cut or removed by the high velocity jet. The preheat! ing flameshave heretoforeusually been produced by forming a combustible mixture of oxidizing gas and fuel gas, such as oxygen and acetylene, in a suitable mixer, which may be located in either the handle or the nozzle of the blowpipe. When projected against the body from one or more passages in the blowpipe nozzle, primary combustion of the oxy-acetylene mixture is completed a releo atively short distance from the end of the nozzle, and a relatively hard heating flame having a high temperature and a high rate of combustion is produced. These jets usually have a velocity, such as from 200 to 500 feet per second, which is 5 lower than that of the cutting jet.

Such a heating flame is unobjectionable when utilized to preheat a portion of a metallic body to the kindling temperature, but when utilized to provide supplemental heat during the cutting operation the walls of the kerf tend to become 5 rough and corrugated, with pronounced drag lines, and the edges of the kerf tend to become rounded. The roughness of the walls and the rounded edges of the kerf are produced by a melting down of the edges due to the high tem- 10 perature and the relative hardness of the preheating flames. A kerf having a rough wall and a rounded edge is undesirable, particularly in instances in which the cutting blowpipe is used to cut from metallic bodies shapes which are to be used as interfitting parts of machinery or similar apparatus. In some instances, it is necessary to cut a shape of a larger size with the blowpipe, and then machine the cut edges because of the dimensional precision necessary for interfitting parts.

In addition, with such combustible mixture jets it is impossible entirely to eliminate flashbacks, with the attendant danger of spoiling expensive shape-cut parts when the work is partially finished.

The objects of this invention are to provide a method or removing metal from metallic bodies by means of astream of oxidizing gas in which a cut or kerf will be produced which has smoother walls and straighter edges than has been heretofore possible to obtain; to provide such a method in which the possibility of flashbacks and backfires during cutting is obviated; and to provide such a method which will be simple and economical. Other objects and novel features of this invention will become apparent from the following description and the accompanying drawing, in which: 4 Fig. 1 is a vertical view, partially in section, ofa metallic body and a blowpipe nozzle, illustrating the removal of metal from the body by the nozzle, which is particularly adapted to carry out the method of this invention;

Fig. 2 is a horizontal view of the discharge end of the nozzle takenalong the line 2-2 of Fig. 1;

' Fig. 3 is a horizontal view, similar to Fig. 2, of an alternative construction of the nozzle of Fig. 1, and

Fig. 4 is a vertical view of a blowpipe provided with the nozzle of Fig. 1. i

As illustrated in Fig. ,1, a heated portion of a metallic body B may be cut or severed so as to produce a kerf K, having walls III and H,

by means 01 a high velocity jet J of oxidizing gas. The jet J, preferably substantially pure -oxygen, may be directed upon the body B from a central or inner passage C of a blowpipe nozzle N.

According to this invention, supplemental heat for the cutting operation is provided by the combustion of a low velocity jet L of a combustible gas, directed upon the body B adjacent the cutting j.et J. The necessary oxygen for the combustible gas is provided by a low velocity jet L" of oxidizing gas, preferably oxygen, which is directed towards the body B between the cutting jet J and the combustible jet L. The low velocity jets L and L" may be projectedfrom restricted lower or discharge portions 12 and I3 respectively, of an outer passage 0 and an intermediate passage I both formed in the nozzle N.

The low velocity jets L and L", which may have a. velocity of 35 to 175 feet per second and preferably approximately 75 feet per second, are sufiiciently close to mix or diffuse into one another as they pass between the end of the nozzle and the body B, and produce a soft gentle flame, particularly adjacent the surface of the body B. This soft gentle flame, which may be termed a diffusion" flame, is characterized by its low rate of combustion and relatively lower temperature.

The difiusion flame burns with considerable luminosity; a considerable portion of its heating effect may be due to radiation rather than convection; and the greatest amount of heat is liberated where the two jets come together at the lip of the kerf. The upper edge of the walls 10 and H of the kerf will be straight instead of rounded due to the lower rate of combustion, the lower temperature, and the liberation of the greatest amount of heat at the lip of the kerf; and the walls of the kerf will be smooth and have nearly invisible drag lines due to the gentler action of the diffusion flames providing supplemental heat. The oxidizing gas jet U will shield the inner cutting jet and prevent the inclusion of burnt and unburnt portions of fuel gas in the cutting jet which tends to impair its oxidizing power; and the use of jets mixing and burning outside the nozzle will entirely obviate the danger of backfires or flashbacks during the cutting operation, which is'an important feature.

As is illustrated in Figs. 1 and 2, the passage C may be formed in an inner member 14 of the nozzle N and may terminate in a circular orifice I5; the intermediate passage I may be formed between the inner member 14 and an intermediate member 16 of the nozzle N, and may terminate in an annular orifice l1 surrounding the inner circular orifice I5; and the outer passage 0 may be formed between the intermediate member 16 and an outer member 18 of the nozzle N, and may terminate in an annular orifice i9 surrounding the annular intermediate orifice 11. The intermediate member l6 may be spaced from the outer member 18 by suitable means, such as lugs 20, and, if desired, the inner member 14 may be similarly spaced from theintermediate member 1'6.

The upper portion of the intermediate passage I is preferably annular in shape, and the lower portion may also be annular in shape, and termihate in the annular orifice l1, as in Fig. 2. The lower portion may also comprise a plurality of drilled holes which are spaced about the central passage C and which terminate in a plurality of orifices 2| disposed in an annular ring surrounding the orifice 15, as in Fig. 3. Similarly, the upper portion of the outer passage 0 is preferably annular in shape while the lower portion may be annular in shape and terminate in the annular orifice I9, as in Fig. 2. Or, the lower portion I8 may comprise a plurality of drilled holes which terminate in a plurality of orifices 22, disposed in an annular ring surrounding the annular ring of intermediate orifices, as in Fig. 3.

The blowpipe illustrated in Fig. 4 has a body F provided with inlet connections 24 and 25, which may be respectively connected to suitable sources of supply of a stream of oxidizing gas, such as oxygen, and a stream of combustible gas, such as acetylene. A two-way valve 26 controls the flow of oxygen from the inlet 24 to a conduit 21 and a branch conduit 28, or to a conduit 29, the latter leading to a mixer M installed in the body F; and a valve 39 controls the flow of fuel gas from the inlet 25 through a conduit 3| to the mixer M, from which a delivery conduit 32 leads. Valves 33 and 34 are adapted to regulate the flow of oxygen through the conduits 28 and 29, respectively. The nozzle N may be attached to a head H of the blowpipe by suitable means, such as a coupling nut 35, and the head may be provided with suitable passages (not shown) which register interiorly of the head with the central passage C, intermediate passage I, and outer passage O of the nozzle, and are adapted to connect the passages with the conduits 21, 28, and 32, respectively.

The valve 26 may be so adjusted that oxygen will pass only through the conduit 29, and the flow of oxygen and acetylene to the mixer M may be regulated by the valves 34 and 39, respectively, so that a combustible mixture will be formed which after passage through the conduit 32 and the outer passage 0 of the nozzle will provide a flame for quickly heating a portion of the body B to the kindling temperature prior to the cutting operation. As soon as the portion to be cut has reached the kindling temperature, the valve 26 may be shifted so that the oxygen will pass only through the conduits 21 and 28, thus cutting off the supply of oxygen to the mixer M through the conduit 29 and providing only acetylene to the conduit 32 and the outer passage 0. At the same time the pressure of gas in the intermediate passage I and the outer passage 0 may be so regulated by valves 33 and 30, respectively, that low velocity jets will be directed from the orifices 11 and I9, and these jets will mingle and burn outside the nozzle in a diffusion fiame' which will provide supplemental heat during cutting.

' In some instances, such as in cutting at higher speeds or on rough surfaces when a flame having a somewhat higher temperature may be desired, a small amount of oxidizing gas, or oxygen,

may be mixed with the fuel gas, or acetylene,

which is directed from the passage 0 into the body B, so that the combustible gas will contain a relatively large proportion of acetylene and a relatively small proportion of oxygen. This relatively small proportion of oxygen in the acetylene passing through the conduit 32 may be obtained by retreating the two-way valve 26 from its extreme cutting position so that a free flow of .oxygen to the conduits 21 and 28 is still obtained, yet a relatively small amount 'of oxygen will pass through the conduit 29 to the mixer M. A two-way valve, such as the valve 26, and other suitable apparatus and methods for providing the desired preheat mixture and low velocity jets are disclosed and claimed in the copending applications of George M. Skinner, Serial No. 128,117,

filed February 27, 1937, and Serial No. 329,008, flied April 11, 1940, the latter being a divisionof the former.

The cross-sectional area of the lower portions l2 and I3 of the outer and intermediate passages and I, respectively, are so proportioned as to provide the proper flow of gas to form the low velocity jets L and L". This may be achieved in the nozzle illustrated in Fig. 2 by the relative position of the members l4, l6 and I8 and also the relative dimensions of the outer diameter of member [4 and the inner diameter of member l6, and the outer diameter of member l8 and the inner diameter of member I8. In the nozzle illustrated in Fig. 3, this may be achieved by the relative dimensions of the diameters of the passages which terminate in the intermediate and outer rings of oriflces 2| and 22, respectively.

Either or both of the lower portions l2 and I3 of the outer and intermediate passages O and 1, respectively, may be inclined toward the inner passage C at any desired angle, such inclination in many instances having been found desirable.

The principles of this invention may also be employed in thermo-chemically removing metal from the surface of a metallic body, but in such cases the velocity of the central oxidizing jet J is usually lower than the velocity of the jet utilized in completely severing a portion of the body, being from 200 to 1000 feet per second instead of from 600, to 1800 feet per second. In such instances, the inner cutting jet J will have a velocity of 200 to 1000 feet per second, while the intermediate and outer jets forming the diflusion flame will have a still lower velocity and will be formed in the same manner as has already been described.

It is to be understood that other arrangements of the apparatus may be used to carry out the method of this invention; that any desirable spacing and arrangement of low velocity jet oriflces may be used; and that other changes may be made without departing from the spirit and scope of this invention.

What is claimed is:

l. A method of removing metal from a ferrous metal body in the open air which comprises increasing the velocity of a stream of oxidizing gas so as to form a metal removing jet; forming a second jet of oxidizing gas and a separate jet of fuel gas; directing said second jet between said metal removing jet and said fuel gas jet but in sufliciently close proximity to said fuel gas jet to cause the gases of said second jet and said fuel gas jet to intermingle and provide a combustible gas stream adapted to produce a heating flame; directing said heating flame against said body to preheat a surface portion thereof; and directing said metal removing jet in the same general direction as said heating flame and against such preheated surface portion at a point different from the point of impingement of said heating flame while eflecting a relative movement between said body and said jets.

2. A method of removing metal from a metallic body, which comprises the steps of directing an inner cutting jet of oxidizing gas onto successive portions of said body; directing an intermediate low velocity jet of oxidizing gas substantially surpredetermined kindling temperature;

3. A method of cutting a metallic body, which comprises the steps of forming a combustible mixture of oxidizing gas and fuel gas; forming a jet of such combustible mixture so as to provide a high temperature heating flame; applying said high temperature heating flame to a portion of said body to'be cut so as to heat said portion to a subsequently directing .a cutting jet of oxidizing gas upon such heated portion; discontinuing the application of said heating flame; simultaneously directing a low velocity jet of a fuel gas upon said body! adjacent said cutting jet; and also simultaneously directing a low velocity jet of oxidizing gas between said cutting jet and said fuel gas jet, said low velocity jets of oxidizing gas and fuel gas being directed sufliciently close to one another so that the gases of these two jets will intermingle and provide a combustible gas stream of relatively low velocity to produce a relatively soft diffusion flame for providing supplemental heat during cutting.

4. A method of cutting a metallic body, which comprises the steps of directing a cutting jet of oxidizing gas upon a heated portion of said body; directing a low velocity jet of gas consisting of a relatively large proportion of fuel gas and a relatively small proportion of oxidizing gas upon said body adjacent said cutting jet; and simultaneously directing a low velocity jet of oxidizing gas betwen said cutting jet and said first-named low velocity jet.

5. A method of cutting a metallic body, comprising the steps of directing a cutting jet of oxidizing gas upon successive portions of said body; directing an annular low velocity jet of oxidizing gas upon said body adjacent said cutting jet; and simultaneously directing an annular low velocity jet of combustible gas upon said body adjacent said first-named low velocity jet, said first-named low velocity jet surrounding said cutting jet and said second-named low velocity jet surrounding said first-named low velocity jet.

6. A method of cutting a metallic body, comprising the steps of directing a cutting jet of oxidizing gas upon successive portions of said body; directing a plurality of low velocity jets of combustible gas upon said body adjacent said cutting jet; and simultaneously directing a plurality of low velocity jets of oxidizing gas between said cutting jet and said combustible gas jets, said low velocity jets being directed generally parallel to said cutting jet and sufficiently close to one another so that the gases of these jets will intermingle and provide a combustible gas stream of relatively low velocity to produce a relatively soft diffusion flame.

'7. A method of removing metal from a metallic body, comprisingthe steps of directing a cutting jet of oxidizing gas upon successive portions of said body; directing a plurality of low velocity jets of oxidizing gas upon said body adjacent said cutting jet, said plurality of jets being disposed in a substantially annular ring rounding said cutting jet; and simultaneously directing a plurality of low velocity jets of combustible gas upon said body adjacent said first-named plurality of jets, said second-named plurality of jets being disposed in a substantially annular ring surrounding said first-named plurality of jets.

8. A method of cutting a metallic body as set.

forth in claim 7, in which the combustible gas of said second-named plurality of jets consists of a relatively large proportion of fuel gas and a relatively small proportion of oxidizing gas.

9. A method of severing a metal body so as to produce a straight kerf which has smooth walls and straight edges, such method comprising applying'a relatively hard preheating flame having a velocity between 200 and 500 feet per second to aporltion of said body so as to heat the same; applying a cutting jet of oxygen to the so heated portion of said body; discontinuing the applica-' tion of said preheating flame; and during the severing of said body supplying heat by a diffusion flame formed by separate jets of oxygen and fuel gas directed onto successive portions of said body adjacent said cutting jet, said separate jets of oxygen and fuel gas having a velocity of less than 200 feet per second and tending to diffuse into one another and produce combustion principally adjacent the surface of said body.

10. A method of cutting a ferrous metal body in the open ain which comprises supplying fuel gas and oxygen to nozzle means; simultaneously and separately discharging from said nozzle means and toward the surface of said body a relatively high velocity oxygen cutting jet, a relatively low velocity fuel gas jet, and an auxiliary relatively low velocity oxygen jet, directed be-' tween said fuel gas jet and said cutting jet and having substantially the same velocity as said fuel gas jet; discharging such fuel gas jet and such auxiliary jet sufficiently close together so that these two jets will intermingle outside said nozzle means and thus provide a combustible gas stream of relatively low velocity to produce a relatively soft diffusion flame for preheating successive areas of said surface; and causing relative movement of said body and said nozzle means while directing said flame against such successive surface areas to preheat the latter and while concurrently discharging such high velocity oxygen jet in the same general direction as said heating flame and against such areas so preheated but at points different from the points of impingement of said heating flame.

JOHN M. GAINES, JR.

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