US2287103A - Method of and apparatus for flame machining - Google Patents

Description

June 23, 19 4-2 5 p JONES 2,287,103 7 METHOD OF AND APPARATUS FOR FLAME MACHINING Filed April 3, 1940 l VEN EV ET JONES BY 7 ATTORNEY Patented June 23,1942

METHODOF AND APPARATUS FOR FLAME I MACHINING Everett P. Jones, Elizabeth, N. J assignor to The ldiinlde Air Products Company, a corporation of Application'April 3, 1940, Serial No. 327,587 8 Claims. (01. 148-9) This invention relates to a method of and apparatus for flame machining in which metal is thermochemically removed from the surface of a metallic body by applying an oxidizing gas stream obliquely against and progressively along successive portions of such surface which is at an ignition or kindling temperature to form a groove therein and relates more particularly to a method of and apparatus for controlling the flow of molten slag from such a flame machined groove.

In many instances it is desirable to remove metal from only a portion of a metallic surface to produce a cut which slopes inward from an uncut portion of the surface and extends to an extreme edge of the metallic body. This is particularly true when it is desired to produce cuts Y at the edges of plates or other structural shapes which are subsequently united by welding. Such cuts or bevels may take the shape of a J so that,

, when two plates having such cuts are arranged with the beveled edges adjacent to each other, a

U-shaped groove is provided therebetween that is suitable for welding. It has been. customary to form such J-grooves by thermochemically forming a U'-groove between abutting edges of separate plates thereby forming a J-groove in the edge of each plate. In many instances this is impracticable or impossible. f

Ordinarily when attempting to thermochemically' form a J-groove Sin the surface of a ferrous metal body by means of 'an oxidizing gas stream, the molten slag, which usually comprises of the apparatusof Fig. 1;

to provide an improved method of flame machin ing in which metal is thermochemically removed from the surface of a metal body to produce a J-groove therein; to provide such a method of flame machining wherein the direction of flow of the slag is controlled; to provide such a method of flamemachining for thermochemically forming a. J-groove in the surface of a metal body that is free of fins and is of a uniform contour; to provide such a method of flame machining a J-groove in the surface of a metalbody that is suitable for abutting against a similarly-grooved body for welding the bodies together; and to provide apparatus for performing such methods of flame machining.

These and other objects and novel features will I be apparent from the accompanying drawing in which: i

Fig. l is a schematic view of one form of apparatus embodying. the features of the present invention;

Fig. 2 is an enlarged isometric view of a portion having a J-groove formed in a'surface thereof;

both oxidized and fused or molten metal, is forced out of the groove and over the edge or edges of the groove and over the surface ahead of and to the side of the cut or groove. Especially when forming a J-groove in a substantially vertical surface'such as the vertical edge surface of a steel plate, the molten slag flows down over the loweredge of the plate or flows over the uncut portion of the surface to form adhering flns which must be removed, and in addition, flows over the surface ahead of the cut.- Due to the action of gravity and the deflection of the 'gas stream molten slag does not flow uniformly over the surface ahead of the cut and non-uniformly preheats the surface metal thereby causing the oxidizing gas stream to remove a non-uniform layer of metal from successive surface portions and causes the J-groove to be of a non-uniform depth. Formerly, it has been found to be very dimcult if not impossible to thermochemically form a satisfactory J-groove that is uniform and free of fins in only one plate edge.

Accordingly, it is an object of this invention 55 according to the present invention; and Fig. 5 is a view similar to Fig. 4 disclosing a modified J-groove.

To remove surface metal by flame machining, the metal must be heated to the ignition or kindling temperature before the oxidizing gas stream is progressively applied-thereto. The entire steel body may be heated to the ignition temperature as in a furnace or an electric arc or high temperature heating flame may be utilized to heat successive portions 'of the surface metal to be removed to the ignition temperature prior to the application of the oxidizing gas stream.

According to this invention a single nozzle N is employed to provide an oxidizing gas stream and v a plurality of high temperature heating-flames.

The blowpipe nozzle N may have a central passage ill for oxidizing gas, such as oxygen, to provide an oxidizing gas stream of suitable character. A plurality of preheating passages I l surrounding or partially surrounding the central passage ID, are provided and supplied with a combustible gas mixture such as oxygen and acetylene to produce preheating flames to heat the surface metal to the ignition or kindling temperature. Though any nozzle of the character which is suitable for flame machining may be. used, a nozzle which has been found to be especially suitable for carrying out this invention as herein described, is disclosed in my copending United States Patent application, Serial No. 254,205, filed February 2, 1939.

The blowpipe nozzle N may be supported and moved relatively to the plate I2 by any suitable means. It is preferable that a self-propelled carriage I3 be used for supporting and moving the blowpipe I4 to produce more accurate cuts or grooves. Such a carriage I3 may be supported on the upper surface of the plate I2 and guided by a rail mounted thereon or may be supported by other means such as separate rails, or other suitable supporting means, on a table extending over or adjacent to the plate I2. The blowpipe I4 andthe operatively attached blowpipe nozzle N may be adjustably secured in a bracket I5 supported by a vertically and transversely adjustable overhanging arm I5 mounted on the carriage I3. A suitable carriage apparatus of such character is'described and claimed in the United States Patent No. 2,183,605 to J. H. Bucknam and A. J. Miller, December 19, 1939.

In order to remove surface metal according to the present invention, the nozzle N is positioned at the edge surface I9 of the substantially horizontal plate I2 so that the preheating flames and the oxidizing gas stream discharged from the outlet orifices of passages I0 and II of the nozzle N are directed against the surface metal to be removed, substantially in the direction of the successive portions of metal to be removed.

The combustible gas issuing from the passages II heats the metaldirectly ahead of the nozzle to the ignition temperature and the oxidizing gas issuing fromthe passage I0 impinges on this heated surface-metal and causes the same to ignite and burn. When the oxidizing gas stream impinges on the surface of the metal to be removed, the stream produces the inwardly curved portion. 29 of the J-groove. The oxidiz-. ing gas stream is deflected upwardly and sweeps over the upper portion of the heated surface to the extreme upper edge of the plate,to produce a substantially straight portion 2I of the groove. This burning or oxidation of the metal takes place progressively as each successive portion of metal is exposed to the oxidizing gas stream. When producing a groove in this manner at the edge of .the plate l2, the surface metal is removed in the form of molten slag, as indicated generally at S, in such a manner that the newly exposed surface is in the shape of a J-groove. When the plate I2 is positioned against or, adjacent to a similarly flame machined plate, the two J-grooves-when aligned form a U-groove, particularly suitable for the welding together of the. two plates.

A conduit 22 is connected through a valve 23 to a suitable source of gas under pressure, such as air, and may be attached to the blowpipe ormounted on the blowpipe supporting means in order to be moved along the cut simultaneously with the blowpipe nozzle. The conduit is preferably supported in an adjustably fixed, predetermined relation relative to the nozzle. A branch portion 24 of the tube 22 is provided and positioned to direct a stream of air upwardly and inwardly against the vertical surface I9 of the plate I2 substantially adjacent and'along the forward edge of the out, as shown at 21, to force all of the molten slag up onto the top of the plate thereby preventing the molten slag from flowing down over the uncut surface portion 28 and preventing the molten slag from flowing ahead'of the groove over the uncut portions of surface I9. The extended portion 29 of tube ,22 contains a plurality of drillings 30 to project a plurality of air jets upwardly and obliquely against the vertical surface I9 of the plate as an aid in preventing the molten slag from flowing from the groove and over the surface ahead of the cut, butprimarily to prevent the molten slag which has. been forced upwardly force the slag upwardly onto the upper surface of the plate and the jets from the tube 29 primarily prevent the slag from flowing over the upper edge and down across the vertical sur-' face. The single jet from tube 24 .is ordinarily sufilcient under some conditions for controlling.

the flow of the molten slag, but usually better results will be'obtained by using a plurality of air jets as described.

Although the removed surface metal can be reduced completely to an oxidized form, consid erable economy can be efiected by removing a substantial portion of the surface metal without completely oxidizing it so that the molten slag contains molten metal. If the molten slag flowed down over the uncut surface portion 28, the slag would form fins on the surface 28 and along the edges of such surface. These fins are usually diflicult to remove and must be removed before the welding operation. The molten sla which flows up onto the upper cold surface of the metal body does not adhere to the metal and usually may be brushed off with little effort. The

molten slag is at a high temperature and if allowed to flow out of the groove and over the uncut surface I9 in front of the groove, the surface metal will be non-uniformly preheated and the depth of the J-groove will not be uniform as the desurfacing reaction proceeds-more vigorously where the metal is hotter. By the present invention, the air jets control the flow of molten light. Beneath suchoxide film there is a thin layer of metal containing carbon in an amount greater than'that of the original metal before the flame machining operation. In this manner, a flame machined surface is so conditioned and improved that subsequent welding of two plates having such surface is considerably facilitated and the resulting welded joint has a strength and uniformity superior to welded plates heretofore beveled by mechanical means. While the nozzle N is herein shown as being so positioned as to direct the oxygen stream inwardly and slightly downwardly against the surface, the nozzle N could be so positioned as to be directed inwardly and slightly upwardly depending upon the contour of the groove desired.

As herein shown and described metal is thermochernically removed along a corner or edge portion of the metal body and the air jet or jets are directed against and blow across to the far edge of that surface which is to be disposed adjacent or against a similarly grooved edge for welding. It is not necessary that the uncut surface portion 28 be as shown and described but the lower edge of the cut could coincide with the vent the slag from flowing out of said groove onto, any portion of said last mentioned surface ahead of said groove; and progressively moving both 7 said oxygen stream and said air stream relativebottom edge of the plate so that the uncut surface portion would be of infinitesimal width, as at 32 of Fig. 5. v In addition, it is not necessary that the surface being flame machined be vertical but the surface can be sloping or horizontal and the gas jets employed for controlling the flow of the molten slag could be of a different number or size depending upon the form of the groove and the amount of slag.

The shape of the groove is dependent upon the velocity of the oxidizing gas stream and its I rate of movement with respect to the surface of '22, 2t, and 29 may be bent or curved so that the jets from tubes 24 and 29 are directed against the correct portions of the surface to prevent the slag from flowing over the bottom edge of the surface or flowing over the surface ahead of the cut.

It will be readily the art that various modifications and substitutions can be made in the embodiment of the invention herein disclosed without departing from the scope or spirit of the invention.

What is claimed is:

l. A method of flame machining in which meta1 is thermochemically removed along the comer portion formed by two contiguous surfaces of a metallic body to produce a J-groove therein, which comprises heating at least a portion of such metal to the temperature at which it will ignite when an oxidizing gas stream is applied thereon; directing an oxidizing gas stream against themetal to be removed and substantially in the direction of the successive portions of,

'' apparent to those skilled in lyalong said corner portion.

3. A method of flame machining in which metal at an ignition temperature is thermochemically removed from the vertical surface of a metallic body to produce a J-groove therein, which comprises applying against suchmetalan oxidizing gas stream directed substantially toward the successive portions of metal to be removed;

directing a stream of gas upwardly against said surface to direct the flow of molten slag from said groove in an upward direction; and moving both said oxidizing gas stream and said slag directing stream relatively along successive portions of said surface.

4. A method of flame machining in which' metal at an ignition temperature is thermochem ically removed from the vertical surface of a metallic body to produce a J-groove therein adjacent a lower uncut portion of said surface, which comprises applying an oxidizing gas stream against the metal to be removed and substantially in the direction of th successive portions of metal to be removed; applying against said surface a stream of gas inclined at an acute angle transversely of said surface and directed upwardly away from said uncut surface portion to the far edge of said surface to direct the flow of molten slag upwardly from said groove onto the upper surface of said metallic body; and progresmetal at'an ignition temperature is thermochemmetal to be removed; applying against one of said moving metal along a corner portion formed by two contiguous surfaces thereof, which comprises heating at least a portion of the metal to be removed to the ignition temperature; applying a stream of oxygen against the metal to be re-.

moved to thermochemically react with such metal, such stream being applied in the direction of the successive portions of metal to be removed applying against and across a portion of one of said surfaces of said body and substantially ahead of the advancing forward boundary of said groove a stream of air directed to Preically removedfr'om an edge portion of a. metalli body to produce a groove therein adiacent a lower uncut portion of a vertical surface of said body, which comprises applying an oxidizing gas stream against the metal to be removed and directed toward successive portions of metal to be removed; applying against said surface a stream of gas inclined at an acute angle transversely of said surface and directed upwardly away from said uncut surface portion to direct the flow of molten slag upwardly from said groove onto the upper surface of said metallic body; applying at least one additional stream of gas upwardly against said surface to prevent said molten slag from flowing from said uppfir surface down over said vertical surface; and progressively moving all of said gas streams relatively along successive portions of said surface.

6. A flame machinging apparatus for thermochemically removing metal from along a corner formed by contiguous surfaces of a metallic body to form a J-groove therein, comprising nozzle sively moving said nozzle and said other gas ap-' plying means lengthwise along successive portions of said corner.

7. A flame machining apparatus for thermochemically removing surface metal from an upper portion of a vertical side surface of a metallic body to form a J-groove thereingadjacent an uncut lower portion of said vertical surface comprising nozzle means for applying an oxidizing gas stream against the metal to be removed substantially in the direction of the portions from which metal is to be removed; means for applying a gas stream upwardly against and across said vertical surface ahead of said groove to cause the slag from said groove to flow upwardly and onto the upper surface of said body; means for applying at least one additional gas stream against and across said vertical surface primarily for preventing said slag from flowing from said upper surface over said vertical surface; and means for supporting and moving all of said nozzle and said gas applying means along successive portions of said vertical surface.

8. A flame machining apparatus for thermochemically forming a J-groove in the surface of a steel body which comprises nozzle means for ing gas stream against such metal, said jet and directing at least one preheating jet against the metal to be removed and for directing an'oxidizsaid stream being directed substantially lengthwise of said surface in the direction of the successive portions from which metal is to be removed; means for applying a gas stream, such as an air stream, against and across said surface approximately adjacent the forward edge of said groove to prevent the slag from flowing from said groove onto the uncut surface portion of said surface; and self-propelled carriage means for adiustably supporting said nozzle means and said other gas applying means in predetermined relationship relative to each other and to said surface and for progressively moving said nozzle means and said other gas applying means along successive portions of said surface whereby said groove is progressively formed in said body.

EVERETT P. J ONES

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