US2210403A - Method of removing metal from metallic bodies - Google Patents

Description

ug 6, 1940- v G. M. sKlNNER 2.210,403

METHOD 0F REMOVING METAL FRM METALLIC BODIES Filed Feb. 27, '1937 FAIG. 2

INVENTOR o I GEORGE M. SKINNER ATTO RN EY Patented A ug. 6,1940

PATENT OFFICE IVIETHOD OF REMOVING METAL FROM METALLIC BODIES George M. Skinner, Buffalo, N. Y., assignor to The Linde Air Products Company, a corporation of Ohio 1 Application February 27, 1937, Serial No. 128,117

6 Claims.

'This invention relates to the art of thermochemically removing metal from metallic bodies, and more particularly to a method of. removing metal from metallic bodies in which a stream of oxidizing gas, such as oxygen, 'is directed onto `a heated portion of the metallic body.

It has been customary in such removal of metal from4 metallic bodies, particularly those composed of iron or steel, to heat a portion of 10 thebody to a suiciently hightemperature, usually designated as the kindling temperature, by means of a high temperature preheating ame, such as that produced by the combustion of a mixture of oxygen and acetylene; and then to direct a jet of an oxidizing gas, preferably pure oxygen, upon the portion' previously heated to the kindling temperature so that the iron or steel uponwhich the oxidizing jet is directed will be partially converted to the oxide and-swept away by the action of the jet. Both the combustible mixture jet which produces the heating flame and the metal removing `jet of oxygen are' normally discharged 'from the nozzle of a blowpipe.

By a progressive movement of the blowpipe nozzle across the metallic body, a portion of the body may be removed and a cut produced along a line corresponding to the path of movement of the blowpipe. Such a method when utilized lo sever a portionl of the metallic body from the remainder of the body will produce va. cut or kerf substantially corresponding in width to the oxidizing jet, which in this instance has usually a velocity o1' 600 to 1800 vfeet per second.v In addition, such a method may be employed in thermo-chemically removing metal from the surface of a metallic l body, and in such instances the velocity of the oxidizing cutting jet is usually lower than the velocity of the jet utilized in completely severing a portion of the body, being from 200 to 1000 o feet per secong.

However, si ce the upper edges of the kerf will not be maintained at the kindling temperature during cutting, due to the cooling action of the cutting jet, the lack of suiiicient rapidity of heat conduction through the steel to the upper edges of the kerf, and the usual presence of millscale on the upperA surface of the eel, it is necessary to supply heatto the metal undergoing treatment, in addition to the heat prdduced by the combustion of the iron or steel. 'I'o supply this additional heat, it has been customary to utilize the preheating flame used to heat a portion of the body to the kindling temperature. Such preheating flames have heretofore been produced by forming a combustible mixture of oxidizing gas and fuel gas, such as oxygen and acetylene, in a suitable mixer located in either the body or the nozzle of the blowpipe, and directing this mixture from the nozzle onto the portion of the body tol be treated. Such preheat- 5 ing flames, which usually have a velocity of from v200 to 500 feet per second, have a high rate of combustion and a relatively high temperature; such llames are also relatively hard, since primary combustion of the Oxy-acetylene mixture 10 is completed a relatively short distance from the end ofthe nozzle.

A relatively high temperatureand hard heating name is unobjectionable when utilized to preheat a portion of a metallic body to the kin- 15 dlingv temperature, but when utilized to provide supplemental heat during the removal of metal by the oxidizing jet, the resultant surface produced by the cutting operation tends to become rough and corrugated, and in the case of the complete 20 severance of a portion of themetallic body, the Walls of the kerf tend to become rough and corrugated,'with pronounced drag lines, and the edges of the kerf tend to become rounded. The roughness of the. wallsand the rounded edges 25 of the kerf are produced by a melting down of 'the edges due to the high temperature and the relative hardness of thepreheating llames...

In addition, with such combustible mixture l jets it is impossible entirely to eliminate flash- 30 backs, with the attendant danger of spoiling expensive shape-cut parts when the work is partially finished.

In the copending application of John M. Gaines, Jr., Serial No. 128,083, filed February 27, u 1937, there is disclosed and claimed a method of overcoming this objection by utilizing a diffusion flame to provide supplemental heat during the removal of metal by 'the oxidizing jet. The diffusion flame is produced by directing, onto o the metallic body, a low velocity jet of combustible gas adjacent the cutting jet, and a low velocity jet of oxidizing gas between the cutting jet and the combustible jet. 'I'he low velocity jets of combustible gas and oxidizing gas, which 5 may have a velocity of 35 to 175 feet per second and preferably about feet per second, intermingle outside the nozzle and burn with,a soft gentle`ame, particularly vadjacent the surface of the body, and liberate the greatest amount of 50 heat where the two jets come together at the lip or edge of the kerf. A diffusion flame, when utilized to provide supplemental heat during cutting, produces a kerf having a smooth wall and sharp upper edges. In addition, jets mixing and burning outside the nozzle entirely obviate the danger of backiires or flashbacks during the removal of metal by the cutting jet, thus elirninating the danger of spoilingy expensive shape-cut parts when the work is partially nished.

The objects of this invention are to provide an improved method of regulating the iiow of oxidizing gas to the diffusion ame; and to provide a simple method for producing a combustible mixture for initial preheating, and a diffusion flame for supplemental heating. Other objects and novel features of this invention will beco-me apparent from the following description and the accompanying drawing, in which:

Fig. 1 is a vertical view, partially in section, of a blowpipe particularly adapted to carry out the method of this invention;

lFig. 2 is an enlarged vertical sectional view of the lower end of the nozzle of the blowpipe of Fig. i; and

Fig. 3 is an enlarged horizontal view, looking upwardly, of the end of the nozzle of the blowpipe of Fig. 1.

As illustrated in Figs. 1 and 2, a nozzleI N of a blowpipe may be provided with a central passage C through which a stream of oxidizing gas may .be passed; an outer passage O through which a stream of combustible gas, such as acetylene, or a combustible mixture, such as a mixture of oxygen and acetylene, may be passed; and an intermediate passage I through which a stream of oxidizing gas, such as oxygen, may be passed. The central passage C may be provided with an upper portion I0 and a restricted lower portion or outlet Il by means of which a jet of oxidizing gas having a relatively high velocity may be formed in a well known manner, the oxygen pressure in the upper portion I0 being considerably greater than the pressure in the outlet Il, and the drop in pressure when passing into the restricted portion giving the oxygen stream the desired velocity. Ihe outer passage O may be similarly provided with an upper portion I2 and a. lower restricted portion or outlet I3 which is adapted to direct a jet of combustible gas or a combustible mixture substantially parallel to the central jet and onto a portion of the metallic body adjacent that upon which the central jet impnges.

In accordance with this invention the supply of oxygen to the intermediate passage is derived from the oxygen passing through the central passage, such as by means of a plurality of connecting passages I4 which lead from the restricted portion Il of the central passage into an enlarged portion or chamber I5 of the intermediate passage, from kwhence the diverted oxygen will ow through a lower'restricted por- .ton or outlet I6 of the intermediate passage.

The chamber I5 not only distributes the gas equally around the peripheryof the intermediate passage, but also reduces the velocity of the oxygen owing therethrough, since the'velocity -of the oxygen passing through the lower portion of the central passage is considerably greater than that used in producing a diffusion type flame. The outlet I6 of the intermediate passage will direct a relatively low velocity jet of oxygen between the central cutting jet and the outer combustible gas jet'. It will be apparent that due to this diversion from the central passage, oxygen will ow through the intermediate passage only lwhen .the cutting jet is employed, and the flow of oxygen through the intermediate passage may be regulated in accordance with flow through the central passage.

v portion of the outer passage O Also in accordance with this invention, the diameters or relative dimensions of the connecting passages I4 may be so proportioned that a denite predetermined amount of oxygen will be diverted from the central stream. In this -way, the flow of oxygen through the intermediate passage may be controlled so that the optimum results will be produced when utilizing any given pressure in the upper portion of the'central passage to produce a given velocity and rate of ow of oxygen through the lower portion. It will be apparent that in some instances, such as in a nozzle adapted to remove metal from the surface of a metallic body in which the central cutting jet hasl a lower velocity and the lower restricted portion II is eliminated or relatively larger in diameter, it may be desirable to divert oxygen into the intermediate passage from the portion II) of the central passage; but it will also be apparent that in a nozzle adapted to utilize oxygen pressuresA of any considerable amount, the lower pressure existing in the restricted portion will permit the use of agreater number of connecting passages, which will tend to distribute the diverted oxygen more uniformly around the periphery ofV the chamber I5 of the intermediate passage.

The central passage C may be formed in an inner or principal member I1 of the nozzle N; the intermediate passage I may be formed between the lower portion of the inner member I1 and an intermediate member I8; and the lower may be formed between the intermediate member I8 and an outer member I9. The outer member I9 may be spaced from the intermediate member I8 by suitable means, such as lugs 20, and, if desired, the intermediate member I8 may be similarly spaced from the inner member I1'. The upper end of the outer passage O may consist of a plurality of longitudinal passages member I'I; and the members I8 and I9 may be secured to the inner or principal member I1 by suitable means, such as by press fits over the circumferential portions 22 and 23, respectively. In addition, the outlets I3 and I6 of the outer and intermediate passages O and I, respectively, may be cylindrical, as is more clearly illustrated in Fig. 3, or may be formed as a plurality of small passages, not illustrated copending application Serial No. 128,083.

In order to supply oxygen and fuel gas to the various passages in the nozzle, the nozzle N', as in Fig. 1, may be secured to a head H of a body B of the blowpipe by a coupling nut 25 in such a manner that a central oxygen passage 26 formed in the head H is in alignment with the central passage C of the nozzle; and an outer passage 21 formed in the head II terminates in an annular groove in alignment with a similar groove formed in the nozzle N to form an annular chamber 28, 'from which connecting passages 29 lead to the inlets 2|.

In order to provide a mixture of oxidizing gas and fuel gas in the outer 'passage O for use during initial preheating, and oxygen passage 30 formedl in the head H may lead to an annular groove aligned with a similar groove formed in the nozzle N to form an annular chamber 3| from which4 a plurality of connecting passages 32 lead into the upper end of the inlets 2 I. In this manner a mixer is formed at the upper end of each of the inlets 2l. By passing acetylene through the passage 2l, the annular chamber 28, and the connecting passages 29|, and simultaneously or inlets 2|, drilled in the here, but disclosed in I passing oxygen through the passage 30, the annular chamber 3| and the connecting passages 32, an Oxy-acetylene mixture will be directed through the outer'passage O of thenozzle, and will produce a high temperature heating flame, which when applied thereto, will quickly bring a desired portion of the metallic body to a temperature necessary for cutting or removal of a portion of the metallic body by means of a jet of oxygen directed from the central passage C.

The upper end of the nozzle may be conical in shape and a conical aperture formed in the head H, having the same slope as the upper end of the nozzle, so that when the nozzle is drawn tightly into the head by means of the nut 25, sealing surfaces 33 will be formed which will prevent leakage of gas from or to the central pas-k sage 26 and the annular chambers 28 and 3|.

The body B of the blowpipe may be provided with an inlet connection 40, to which may be connected a line adapted to deliver a suitable supply of loxidizinggas, such-as oxygen, and an inlet connection 4|, to which may be attached a line providing a suitable supply of fuel gas, such as acetylene.. Leading from the inlets 40 and 4|, respectively, are passages 42 and 43, formed in a valve body V; and installed in the body V are shut-olf valves 44 and 45, which are adapted to prevent the flow of gas through the passages 42 and 43, respectively, when the blowpipe is not in use. The valve 45 is also adapted to be used as a regulating valve for the fuel gas.

In further accordance with this invention, a two-way valve 46 is installed in the valve body V and utilizes the passage 42 as an inlet. Valve '46 is provided with two outlets-anoutlet 41, to

which is connected a tube 48 leading to a valve body V in which is installed a regulating valve 49, and a second outlet 50. Tubes 5|, 52, and 53, respectively, connect the outlet 50, the passage 43, and the outlet 41 (through the tube 48 and valve 49) with the central, outer, and intermediate passages 26, 21, and 30 of the head H. The valve 45 is adapted to regulate the ow of fuel gas through the tube 52 to the outer passage O of the'nozzle, and the two-way valve 46 is adapted to permit the flow of oxidizing gas through the tube 5| to the central passage, or through the tube 53 to the outer passage O of the nozzle.

A valve chamber 54 for the two-way valve 46 is formed between a cap 55 and the valve body V, seats 56 and 51being formed in the cap and the body V at either end of the chamber 54. When the two-way valve 46 is moved against the seat 56, oxygen will flow through the outlet 50, formed in the valve body V, to the central pas'- sage C of'the nozzle; and when the two-Way valve is moved against the seat 51, oxygen will ow through the outlet 41, formed in the cap 55, to the valve 49 and the outer passage O of the nozzle.

The valve body V is provided with a stem passage 58, through which a stem 59 of the valve 46 extends, the stem being provided with an enlarged threaded portion 60. 'Ihe walls of the stem passage 59 are threaded to cooperate with the enlarged threaded portion 69 of the stem so that by turning the stem the valve 46 may be moved to any desired position between the seats 56 and 51. In addition, a gland 6| may be provided, the gland being threadedly secured to the body V and adaptedto retain packing against purposes, the two-way valve 46 is moved against the seat 51, and the flow .of acetylene and oxygen to the outer passage O through the tubes 52 and 53 regulated by means of the valves 45 and 49, respectively. When' the portion to be heated has reached'the kindlingA temperature, the cutting owgen isturn'ed on\by moving the valve 46 against the seat 56, the oxygen then passing through the tube 5| to the central passage C. During the removal of metal by the oxygen directed from the central passage C, supplemental heat will be provided by the diffusion flame pro duced by the acetylene directed from the outer passage O and the oxygen diverted from the central passage C into the intermediate passage I through the passages |4, as previously explained.

In case .a slightly higher temperature of the supplemental heating flame is desired, such as in cutting at higher speeds or on rough surfaces, or in order to prevent the formation of carbon deposits in the lower ends of outlets I3 and I6, the valve 46 may be adjusted so that it is spaced a small distance from the seat 56 and a small amount of the cutting stream of oxygen is diverted at the valve 46 and flows through the tube termined amount of'oxygen in the fuel gas during cutting, the correct setting of the two-way valve 46 during the cutting operation is. rst determined, and a stop screw 62, having a threaded portion 63 in engagement with a threaded hole in the valve body V and adapted to abut against the end of the two-way valve adjacent the seat 56, is turned into engagement with the end of the two-way valve and locked ln position by a lock nut 64. The stop screw 62 may also be providedwith a packing gland similar to the gland 6| provided for the stem 59 of the valve In utilizing the stop screw 62, it is set in position during the i-lrst of a series of similar cutting operations. For subsequent cutting operations the two-Way valve is merely seated against the seat 51, the preheat mixture adjusted by means of the valves 45 and 49; and when the portion to be cut has reached the desired temperature, the cutting oxygen turned onand the required predetermined amount of oxygen in the fuel gas in the outer passage automatically obtained by moving the two-way valve into abutment with the stop screw 62. During cutting, the required amount of oxygen to form the diffusion flame will be diverted from the cutting Stream through the passages |4, as previously described.

An alternative method of supplying a small predetermined amount of oxygen to the fuel gas during cutting is'by means of one or more metering passages, such as the passage 10, shown in dotted lines in Fig. 2, leading from the enlarged portion I5 of the intermediate passage I to the outer passageO. 'I'he passage 10, if desired, may lead'from the upper portion I0 of the central passage to the outer passage O. as at 1| in Fig. 1, or from the outlet or the central passage to the outer passage O. In the last instance, the intermediate member I8 may be shortened so that it will be necessary to drill such metering passage or passages only through the inner member I1. By diverting a small predetermined amount of oxygen from the central passage into the outer passage, use of the stop-screw 62 of the two-way valve is unnecessary, and the adjustment of the amount ofv oxygen diverted into the fuel gas stream during cutting is not left to the operator.

It will be apparent that a mixer may be installed in the body of the blowpipe instead of being formed in the upper end of the inlets 2|; that other arrangements of valves may be used; and that other changes may be made which will not departl from the spirit and scope of this invention.

What is claimed is:

1. In a method of thermo-chemically removing metal from metallic bodies, in which a stream of oxidizing gas is directed in a jet onto a por tion ofthe metal to be removed from a metal body, the steps of directing a jet of combustible gas onto said body adjacent said first-named jet; diverting a portion of said oxidizing gas Vstream to form a jet for supporting the combustion of said combustible jet; and directing said combustion supporting jet between said oxidizing gas jet and said combustible gas jet. j 2. A method of removing metal from a metallic body which comprises mixing a stream of fuel gas and a stream of oxiding gas to form a combustible mixture; directing such mixture in a heating jet onto a portion of said body to be cut so as to raise such portion to a predetermined kindling temperature; directing a second stream of oxidizing gas in a cutting jet onto said heated portion; discontinuing said rst-named oxidizing gas stream; diverging a portion of said second oxidizing gas stream; and directing such diverted portion to mix with and support the combustion of said jet of fuel gas.

3. In a method of removing metal from a. metallic body in which a jet of oxidizing gas is directed onto a portion of a metal body heated by a jet of combustible gas and. a second jet of oxidizing gas directed separately onto said body, the step of forming said second jet by diverting a portion of said rst-named oxidizing gas jet, and

reducing the velocity of said diverted portion below that of said rst-named oxidizing gas jet.

4. A method of cutting a metallic body comprising the steps of mixing a stream of fuel gas and a stream of oxidizing gas to form a combustible mixture; directing such mixture in a heating jet onto a portion of.said body to be 'cut so as to raise such portion to a predetermined kindling temperature; directing a second stream of oxidizing gas in a cutting jet onto such heated portion; discontinuing a large proportion of said first-named oxidizing gas stream so as to direct a jet of a combustible gas onto said body adjacent said-cutting jet; and simultaneously diverting a portion of said second oxidizing gas stream to form a separate jet of oxiding gas directed upon such portion being removed.

5. A method of removing metal from a metallic body comprising the steps of mixing a stream of fuel gas and a stream of oxiding gas to form a combustible mixture; directing such mixture in a heating jet onto a portion of said bodyk to be cut so as to raise such portion to a predetermined kindling temperature; directing a second stream of oxidizing gas in a. cutting jet onto said heatedportion; discontinuing said first-named oxidizing gas stream; diverting a portion of said second oxidizing gas stream and directing such diverted portion into said fuel gas stream so as to form a combustible jet having 'a relatively large proportion of fuel gas and a relatively small proportion of oxidizing gas; and simultaneously diverting a second portion of saidvsecond oxidizing gas stream to form a separate jet of oxidizing gas directed upon such portions being removed.

s. 1n a method' of cutting a metallic-body, the

steps of forming a. highvelocity cutting jet from a stream of oxidizing gas; forming a low velocity jet of combustible gas adjacent said cutting jet; simultaneously diverting a portion of said high velocity jet, reducing the velocity thereof, and directing such diverted portion in a low velocity jet between said cutting jet and said com- A bustible jet; and applying said cutting jet and said low velocity jets onto a portion of said body so as to cut th'e same.

GEORGE M. SKINNER.

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