US2448098A - Method of thermochemically cutting metal - Google Patents

Description

Aug. 31, 1948. -H. e. HUGHEY METHOD OF THEKMOCHEMICALLY CUTTING METALS 3 Sheets-Sheet l Filed Dec. 7, 1944 IN VEN TOR HTQOZZMEYS.

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Patented Aug. 31, 1948 METHOD OF THERMOCHEMICALLY CUTTING METAL HowardG. Hughey, Fanwood, N. J., assignor to Air Reduction Company, Incorporated, a corporation of New York Application December 7, 1944, Serial No. 567,060

6 Claims. (Cl. I489) This invention relates to a method for thermochemically cutting metal.

In the cutting of metal by means of an oxygen cutting torch, such as an oxyacetylene cutting torch, the thickness of the work-piece that can be cut with a given oxygen jet depends upon the ability of the jet to maintain the cutting operation at the lower portion of the kerf. The thicker the work-piece, the more difficult it is for the oxygen jet to maintain the cutting operation due to the relativel great distance from the preheating flames to the lower portion of the kerf, the tendency of the molten slag and oxide running down from above to blanket the face of the cut, and dilution of the oxygen stream because of its mixing with the products of combustion from the preheating flames. Therefore, there is a limit to the thickness of a Work-piece that can be cut in the usual way by a standard cutting torch.

The principal object of this invention is to provide an improved method of thermo-chemically cutting metal in which these difficulties are overcome or lessened to such an extent that a given oxygen jet may be made to cut heavier sections than heretofore.

According to my method the cutting oxygen and one or more relatively large flame jets are projected alternately into the kerf. The flame jet is large enough to reach substantially to the bottom of the kerf and sufficiently heat the en-. tire face of the cut. The flame jet is then turned off and the cutting oxygen jet projected into the cut. This cycle is repeated until the cutting operation is completed. The result is that, when making a heavy cut, sufficient heat is supplied to the lower portion of the kerf so that the metal adjacent the kerf at the side where the cut is to continue never will be allowed to cool to-a pointv below that at which the thermo-chemical action takes place. Also the large flame jet blows out the molten slag and oxide so that when the cutting oxygen jet is again projected into the kerf it will attack fresh metal, and. moreover, dilution of the oxygen stream in the lower portion of the kerf .by products of combustion from the heat ing flame such as would'normally interfere with continuance'of the thermo-chemical action, is avoided, thus making it possible to cut heavier sections than if the same oxygen jet were pro.

jected continuously into the kerf when employin heating flamesinthe usual way..

The accompanying drawings illustrate several forms of cutting torch; whichmay be used to carry outthe improved method. In the drawings- Figs. 1-5, inclusive, illustrate more or less diagrammatically one form of torch embodying the invention and its mode of operation. In these figures;

Fig. 1 is a longitudinal section through a portion of the torch tip and the valve mechanism hereinafter described for causing alternate projection into the kerf of the cutting oxygen and the flame jet;

Fig. 2 is a vertical transverse section through a work-piece that has been partially cut through by the torch shown in Fig. 1, the section being taken in the plane of the cut, and the purpose of the view being to show the cutting oxygen being projected into the kerf when the valve is in the position shown in Fig. 1;

Fig. 3 is a view corresponding to Fig. 1 showing the valve in the position in which the supply of cutting oxygen is out 01f and the large flame jet is projected into the kerf Fig. 4" is a view corresponding to Fig. 2 showing the large flame jet being projected into the kerf when the valve is in the position shown in Fig. 3;

Fig. 5 is a transverse section through the tip of the torch taken on the line 55 of Fi 3;

Fig. 6 is an enlarged side elevation of the valve removed from the torch;

Fig. 7 is a transverse section through the valve taken on the line 1-1 of Fig. 1;

Figs. 8-12, inclusive, illustrate, also somewhat diagrammatically, another form of torch for use in carrying out the method of the invention. In the figures of this group,

,Fig. ,8 is a longitudinal section through the torch showing the valve in the position in which the cutting oxygen, is being projected into the.

kerf;

Fig. 9is an end view of the'torch shown in Fig. 8 as seen from the tip end;

Fig. 10 is an enlarged section through the valve mechanism only, showing the valve turned to the position in which the supply of cutting oxygen is cut off and the supplies of oxygen and fuel gas for the large flame jet are turned on;

Fig. 11 is a transverse section through the valve taken on the line I |-I l of Fig. 10;

Fig. 12 is a transverse section through the torch tip taken on the line l2l2 of Fi 8;

Figs. 13 to 15 inclusive, illustrate, more or less diagrammatically, a third form of torch embodying the invention. In these figures,

Fig. 13 is a longitudinal section through a portion of the torch; I Fig. 14 is a transverse section through th torch tip taken on the line I4-I4 of Fig. 13; and,

Fig. 15 is a transverse section taken on the line |I5 of Fig. 13.

Referring first to Figs. 1 to 7, inclusive, the torch therein illustrated has a tip I provided with a passage 2 for the cutting oxygen and a passage 3 for supplying a mixture of oxygen and a fuel gas, such as acetylene, to the flame jets. The cutting oxygen issues from a discharge orifice 4 at the end of the tip and the gas mixture for the flame jets issues from a number of surrounding orifices 5 to which it is distributed by an annular chamber 6 in the tip in communication with the delivery passage 3.

A valve 1 associated with the tip has a port 8 extending through it, which in one position of the valve, permits cutting oxygen to flow through the passage 2 to the discharge orifice 4. It also has a second port 9 passing through it whose axis is at right angles to the axis of the port 8. This port controls the major supply of gas mixture to the discharge orifices 5, but encircling the valve 1 at the place where the port 9 is located, is an annular groove or recess ID which always allows a small portion of the gas mixture to pass to the discharge orifices 5, no matter what position the valve is in. The valve may be turned continuously at a predetermined rate, in any suitable way as by a motor (not shown) through bevel gears l l and I2, or it may be turned by hand. When the Valve is in the position shown in Fig. 1, only a small portion of the gas mixture passes the valve through the recess it, as shown in Fig. '7, for the preheating flames and pilot flames at the discharge orifices 5, but the port 8 permits cutting oxygen to flow freely to the discharge orifice t. Fig. 2 shows a jet of cutting oxygen l3 being projected into 2. Keri being cut in a work-piece W from the discharge orifice 4 when the valve is in the position shown in Fig. 1. When the valve 7 is in the position shown in Fig. 3 the axis of the port 8 is at right angles to the passage 2 and the supply of cutting oxygen to the discharge orifice 4 is cut off, but the axis of the port 9 is now in alignment with the passage 3, thus permitting a large supply of gas mixture to pass through the passage 3 to the discharge orifices 5. Thus, in this position of the valve, no cutting oxygen is projected into the kerf, but a large composite flame jet M is projected into it, as shown in Fig. 4. As the valve rotates, the cutting oxygen discharge orifice is supplied with oxygen twice in each revolution. The flame jet orifii'ces 4 receive some gas mixture for relatively small flames at all times and receive a greatly augmented supply of the gas mixture twice in each revolution of the valve alternately with the supply of cutting oxygen to the discharge orifice 4. The discharge orifices 5 for the flame jets and the passages leading to them may be somewhat larger than usual, so that the augmented supply of gas mixture to the orifices 5 will produce a relatively large flame jet that will reach substantially to the bottom of the kerf and sufliciently heat the entire face of the cut, as indicated in Fig. 4. This large flame jet will also blow out the molten slag and oxide so that when the cutting oxygen jet is again projected into the kerf it will attack fresh metal, as above described. When the supply of gas mixture to the discharge orifice 5 is reduced, when the valve is in the position shown in Fig. 1, the relatively small flame jets at the discharge orifices 5 then serve as pilot flames and also as preheating flames of the usual type to be used at the start of the cutting operation, at which time the supply of cutting oxygen may be cut "off in any suitable way until the metal has been brought to ignition temperature at the place where the cut is to be started,

In the form of torch shown in Figs. 8 to 12, inclusive, the torch tip I is of a standard type in which there is a central passage [5 for the cutting oxygen terminating in a discharge orifice i ii at the end of the tip, and a series of surrounding passages l1 for the combustible gas mixture terminating in a series of discharge orifices 18 at the end of the tip. Cutting oxygen enters the torch at the connection l9. Auxiliary oxygen enters it at the connection 20, and fuel gas, such as acetylene, enters it at the connection 2|. A portion of the auxiliary oxygen passes into a mixing chamber 22 to which some of the acetylene is also delivered through a branch passage 23. This mixture of auxiliary oxygen and acetylene then passes through a tube 24 to an annular chamber 25 in the head 26 of the torch. This chamber supplies the gas mixture to all of the passages 11 in the tip, in a manner well understood in the art, to feed the flame jets at the discharge orifices Hi. This supply of gas mixture is uninterrupted, and the flame jets at the discharge orifices l8 serve as preheating flames of the usual type to bring the metal to ignition temperature at the beginning of a cutting operation and also as pilot flames as hereinbefore described. Within the torch there is a mixing chamber 2? to which some of the acetylene entering at El passes through suitable tubes 28 and 29 when the valve 7', hereinafter described, permits it to do so. Some of the auxiliary oxygen entering at 20 passes through a branch passage 30 and is conducted to the mixing chamber 21 through suitable tubes 3! and 32 when the valve 1' does not obstruct its flow. The cutting oxygen entering at l9 flows through tubes 33 and 34 to the central passage l5 in the torch tip when the valve 1' permits it to do so. A tube 35 places the mixing chamber 21 in communication with the tube 34 leading to the central passage i5 of the torch tip.

The valve '5 is similar to the valve 1, hereinbefore described, except that it has three ports, one of which, shown at 36, controls the supply of cutting oxygen to the torch tip; another of which, shown at 31, controls the passage of auxiliary oxygen into the mixing chamber 21, and a third of which, shown at 38, controls the passage of acetylene into the mixing chamber 21. The axis of the two ports 31 and 38 are parallel and at right angles to the port 36. Therefore, when the port 36 allows cutting oxygen to flow to .the tip, the ports 51 and 38 are out of alignment with the passages which "they control and cut off the supply of auxiliary oxygen and acetylene to the mixing chamber 21. The valve '1" may be continuously rotated in any suitable way as above described. A handle 39 is shown on the valve as representative of any suitable means for rotating it.

The mixer .22 maybe of relatively low capacity designed to supply a normal complement :of combustible gas mixture to the preheating flamesat the jet orifices 18. As above stated, this supply of gas mixture is uninterrupted. As the valve 1' rotates, cutting oxygen is supplied to the :central passage I5 of the tip alternately with the combustible mixture of oxygen and fuel gas. That is,when the valveis in the positionshown in Fig. 8, cutting oxygenwill be delivered to the central passage l5 of the tip, and when it is in the position shown in Fig. 10 auxiliaryoxygen andacetylene will be delivered to the mixing chamber 2 1,

where th'eyiwili' begmixed and-then delivered throughthe'tube' 35 to the central passage of. the tip; 'Thus, -the centra1 passage ofthe tip =i-s utilized not only to project the cutting oxygen into the kerf,abut-also topr'oj'ect a' relativelylarge 'and intense heating flame substantiallytothe bottompf the kerf; I Therefore a-llof the passages-in the torch tip are at'times utilized to suppliy a "combustible --gas mixture to 1 the heating flames; 'Ihe large-heating flame w'ill be alternatelyxprojected into the -ker-fwith the cutting oxygen both' being projected from the 1 central discharge orifice l6 of th'e torch-tip;*from which in: 'usuafpractice, :only the cutting oxygen issues. 'The form of torch illustrated in Figs: 13 to 1-5, inclusive, issimilar to that 'ju'stdescribed', exceptthat the mixing chamber -21=is dis'pensedwith and the. auxiliary oxygen and acetylene for thelarge flame jet are mixed within th'e 'torch tip When-the valve I permits them to do so, the aux'-' iliary oxygen passes from a tube 3|, hereinbefore described, to a tube 40',-'a-nd the acetylene passes from the tube 28, hereinbeforedescribed, to a tube 4|. From the-tube 40,'the auxiliary oxygen flows-through a passage 42 in the head=to the central passage 43 in the head, which is in axial aligmnent with the central cutting oxygen passage 44 in thetip'. "From'the tube 4|, the acetylene flows through a passage 45 in the head'into anaannularpharnber 46 in'the tip, from which it is-delivered by branch passages. in the tip to the ;c entral-,tip passage;44 *n' -mixing chamber 4. may be provided in, the ,tipfthrough which the auxiliaryoxygen andthecacetylene must pass and be mixed before being discharged from the central orifice at the end of the tip;

The operation of the torch shown in Figs. 13 to 1,5,;is similar to...the operation of the other forms of the torch hereinbefore described. When the valve 1' is in the position shown in Fig. 13, cutting .oxygen is discharged through the central passage of .the tip,cthe supply of auxiliary oxygen and acetylene to the central'passage being cut on? by -the valve. vWhen the valve is turned-to the position shown in :Fig'. 10 i the supply of "cutting oxygen is cut off and auxiliary oxygen ls delivered by the tubes 3|, 40 and passage 42, to the central" passage in the tip, and acetylene is delivered by the tubes 28, 4| and passage 45 to the annular chamber 46 in the tip, thence to the branch passages 41 in the tip to the central tip passage, where it is mixed with the auxiliary oxygen in the mixer 48. The combustible mixture thus produced feeds the relatively large flame jet at the central discharge orifice which is projected alternatively into the kerf with the cutting oxygen, as previously described. As in the form of the invention illustrated in Figs. 8 to 12, inclusive, a normal complement of combustible gas mixture is continuously supplied from a tube 49 (corresponding to the tube 24 in Fig. 8) to annular chamber 50 in the tip, from which it is distributed to the series of tip passages to feed the relatively smal1 flames corresponding to the usual preheating flames.

When using any of the forms of torch above described, after the cut has been started, the valve is preferably rotated continuously and at the proper speed to obtain the desired rhythmic frequency of alternation of the cutting oxygen jet and large flame jet. The most effective frequency of alternation may depend upon the thickness of the Work-piece and other conditions under which the cutting operation is being conducted, but for a given operation it can be easily against the metal at the place where the cut is determined or'will sben become a parentto' the operatorafter the cut is started, and he willsee to it :thatfthe speed of rotation of-the valve isadjusted accordingly. I I 7 'Ihe word flame as used herein and in the appended claims refers to the total flame including the secondary-envelope, and not merel'y the priclaimyl" i. j i .7",

The method of thermo chemically cutting through metal Work-pieces" of heavy section which comprises initially heating the metal at the place where-the cut is tobegin to a temperature at which the metal will burn when cutting oxygen is projected thereagainst, projecting cutting oxyg'e'n' onto'the pre-heated work-piece at such place to burna portion of the metal-thereof to form-a kerf extending through the work-piece, thereafter alternatelyand with rhythmic frequency projecting a heating flame and a jet of cutting oxygen into the kerf-to continue the-cutting'operati'on. said heating flame reaching substantially 'to' the bottom. of the kerf, the periodicity of such alternation being such that the metal'adjoining'the kerf at that place where the cut is through metal work-pieces of heavy section which comprises initially directing a pre-heating flame against the metal at the place'where the cut is to begin to bring it to a temperature at which the metal willburn whencutting oxygen is projected' thereagainst; projecting cutting oxygen onto the 'pre-heatedwork-piece at such place to heating flame and "a jet of cutting'oxygen into the kerf to continue the cutting operation, said heating flame reaching substantially to the bottom'of the kerf, the periodicity of such alternationbeing such that the metal adjoining the kerf' at the place where the cut is to continue never cools -t'o' a'point below that at which the thermo-chemical reaction will take place.

3. The method of thermo-chemically cutting through metal Work-pieces of heavy section which comprises initially directing a pre-heating flame against the metal at the place where the cut is to begin to bring it to a temperature at which the metal will burn when cutting oxygen is projected thereagainst, projecting cutting oxygen onto the pre-heated Work-piece at such place to burn a portion of the metal thereof to form a kerf extending through the work-piece, thereafter alternately and with rhythmic frequency projecting an intense heating flame, produced by increasing the size of said pre-heating flame, and a jet of cutting oxygen into the kerf to continue the cutting operation, said heating fiame reaching substantially to the bottom of the kerf, the periodicity of such alternation being such that the metal adjoining the kerf at that place where the cut is to continue never cools to a point below that at which the thermo-chemical reaction will take place.

4. The method. of thermo-chemically cutting through metal work-pieces of heavy section which comprises initially directing a pre-heating flame metal will burn when cutting oxygen is projected thereagainst, projecting cutting oxygen onto the pre-heated work-piece at such place to burn a portion of the metal thereof to form a kerf extending through the workpiece, thereafter alternately and with rhythmic frequency projecting an additional and larger heating flame and a jet of cutting oxygen into the kerf to continue the cutting operation, said heating flame reaching substantially to the bottom of the kerf, the periodicity of such alternation being such that the metal, adjoining the kerf at that place where the cut is to continue never cools to a point below that at which the thermo-chemical reaction will take place.

5. The method of thermo-chemically cutting through metal work-pieces of heavy section which comprises, initially pre-heating the metal at the place where the cut is to begin to a temperature at which the metal will burn when cutting oxygen is projected thereagainst, projecting a jet of cutting oxygen downwardly against the pre-heated work-piece to burn a portion thereof to form a kerf extending downwardly through the workpiece, continuously projecting a heating flame into the downwardly extending kerf throughout the entire cutting operation, supplementing said heating flame by additional blasts of heating gas, said blasts of heating gas reaching substantially to the bottomof the kerf and alternating said additional blasts continuously with jets of cutting oxygen projected into the kerf, such alternation of said additional blasts of heating gas and jets of cutting oxygen being of a predetermined rhythmic frequency, whereby the cut periodically is free from the cutting oxygen and the molten slag and oxide formed therein are removed by both gravitational forces and the periodic blasts of additional heating gas, the periodicity of such alternation being such that the metal adjoining the kerf at that place where the cut is to continue never cools to a point below that at which '4 the thermo-chemical reaction will take place.

6. The method of thermo-chemically cutting through metal work-pieces of heavy section which comprises heating the metal at the place where the cut is to begin to a temperature at which the metal will burn when cutting oxygen is projected thereagainst, projecting a jet of cutting oxygen onto the heated work-piece at such place to burn a portion thereof to form a kerf extending through the work-piece, alternately shutting oil? the oxygen supply and thereby stopping the oxidizing reaction while it is progressing actively and projecting a flame jet of heating gas onto the metal adjoining the kerf at that place where-the cut is to continue while the supply of cutting oxygen is shut off to heat such metal and to remove molten material from the kerf, said flame jet reaching substantially to the bottom of the kerf, repeating such alternation with a predetermined rhythmic frequency and continuously advancing the alternating jets progressively along the line of the cut during such alternation, the periodicity of such alternation being such that the metal adjoining the kerf at that place where the cut is to continue never cools to a point below that at which the thermo-chemical reaction will take place.

HOWARD G. HUGI-IEY.

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

UNITED STATES PATENTS Number Name Date Re. 16,307 McCutcheon Mar. 30, 1926 1,709,886 Smith et al Apr. 23, 1929 1,721,569 McCutcheon July 23, 1929 2,167,399 Wagner July 25, 1939 2,177,276 Bucknam Oct. 24, 1939 FOREIGN PATENTS Number Country Date 88,358 Austria May 10, 1922 OTHER REFERENCES Van Brussel: New process for metal cutting and autogenous welding, from The Engineering Magazine, July 1908, page 552.

Oxy-Acetylene Handbook, 1943, first edition, pages 435-438 inclusive, particularly Figs. 336 and 339; published by Linde Air Products Co., New- York city, New York.

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