US2238470A - Blowpipe - Google Patents

Description

April 15, 1941. w. J. JAcoBssoN :E1-m. 2,238,476

BLOWPIPEl F4195 oct. 20, 1937 Iliff/flug@ INVE'NTORS WILGOT J. JACOBSSON SAMUEL R. OLDHAM ATTORNEY Patented Apr.15,1941

Wilgot J. Jacobsson,

Qldham, Elizabeth, N.. Acetylene Company,

Virginia Scotch Plains, and '"'amuel R. J., asslgnors o Oxweld ia. corporation of West Application october zo, 1937, serial No. 169,930 v (c1. 15s-e214) 3 Claims.

blowpipe attachblowpipe attach- This inventio'n relates to a ment, and more particularly a ment which is adapted to use eitherlow or mediu'm pressure fuel gas. The invention is especially useful asan attachment for existing blowpipes, notably for converting a conventional welding blowpipe into a cutting blowpipe, to which use, however, it isnot limited. Some of the features of the invention may be types of blowpipes.

Fuel ,gas (as acetylene) may be available at different places or at diierent times as low pressure (say less than 1 lb. per square inch) gas or as medium pressurey (say 15 lbs. per square inch) gas. As a matter of economy-and convenience,

therefore, it is desirable for a user to have availutilized in other.

able asingle blowpipe which may be used eiciently with iuel gas at these diierent pressures.

In the past, it has been customary to design blowpipes so that they would not flashback at a given fuel gas pressure. However, increasing or decreasing the.pressure to any considerable extent I alter the flashback resistance of may materially For this reason, it has not been `the blowpipe.

possible to sure and medium pressure fuel gas, unless mixers or other parts of the blowpipe were changed. Also, when both welding and cutting work is to be carried on in a shop, it is customary' to employ separate 'welding and cutting blowpipes for the 5 respective operations and to keep both blowpipes available in the shop. This practicetends further to multiply the required number of blowpipes and the expense of blowpipe equipment.

One object of the invention is, therefore, to provide a blowpipe which may be used as acutting attachment 'and connected to a welding blowpipe, thereby saving the expense of purchasing and maintaining a complete welding blowpipe and also a complete cutting blowpipe for performing the twooperations. Another vobject is to provide a single blowpipe which may be used use the same blowpipe for low presbend at lthe front thereof and two Fig. 2 is across-section taken on the line II--II of Fig. 1;

Fig. 3 is a cross-section taken on the line III-III of Fig. 1;

Fig. 4 is a cross-section IV-lV of Fig. 1;`and A Fig. 5 is a broken -longitudinal mid-section showing the connection between the rear end of the attachment and the 'forward end of a'welding blowpipe handle.

vIn accordance with 4taken on lthe line the invention thereis provided a blowpipe comprising a body member, al

combustible gas mixture conduit, means providing anelongated cavity terminating at its forward end at the rear end of the mixture conduit, and terminating at its rear end in the body member, and means at the forward end of the blowpipe for discharging a combustible gas mixture. An elongated combustion-supporting gas conduit in the. cavity is spaced from the internal cavity wall to provide an elongated annular chamber having an appreciable Volume. A mixer nozzle in the cavity issecured to the forward end of the combustion-supporting gas conduit and is vso constructed and arranged that backfires will pass intothe annular chamber. A generally U-shaped fuel-gas passage having an appreciable volume and being adapted to contain `a large volume of f' fuel gas for receiving and extinguishing backres,

which is disposed between the body member and the forward end of the blowpipe, has a, return y terminals at the rear thereof in the body member. A passage in the body member communicates between one of thev terminals of the .U-shapedfpassage and the annular' chamber. Suitable means are provided for, supplying fuel gas and combustionsupporting gas, respectively, to the other terminal of the U-shaped passage and to thecombusefficiently over a wide-range of fuel gas pressures.

A further object is the provision of such'a ,blow- `pipe which will be substantially freeafrom flash-' entirefrange of operating.`

back action over its pressures.

- -ing the mixer-nozzle,

The above and other objects andnovel features of the invention will be apparent from the following description taken with the. accompanying drawing. inwhich: I

. AFigthrough a blowpipe comprising a'. cutting attachment, constructed-inaccordance with the invention;

1 is a broken longitudinal mid-section'v acetylene Ation-supporting gas conduit. The U-shaped fuelgas passage and the annular chamber cooperate to contain together a sufliciently large volume of fuel gas to receive and extinguish backfires passthereby preventing flashbacks'. For convenience, the words -"4oxyge'n and will be used in this specification to denote respectively any appropriate cutting and combustion-supporting gas,'and any appropriate fuel gas. J

A device constructed in accordance with the invention comprises a body B and a head H connected-by conduits generally, designated as C. The head H carries the blowpipe tip T at the forward end of the blowpipe which is connected thereto by an'attachingnut N in the usual manner. The body B has gas passages therethrough connecting with the conduits C, and contains the gas control elements of the blowpipe, as the valves and the mixer. In the embodiment which is illustrated in the drawing, the blowpipe is constructed as a cutting attachment, and connecting means J are provided for joining the blowpipe to a welding blowpipe handle A.

Q The handle A which is illustrated in the draw! ing (see Fig. 5) is a well-known form of welding blowpipe handle from which the mixer and stem have been removed, and to which the connecting means J may be applied to attach the body B thereto. The handle A comprises the 'usual hollow shell I0, which is attached at its forward end to a forward block I I. The frontend of the forward vblock- IIv 'is formed as an externally threads 34 on 'the forward end of the former connects the forward end of the oxygen conduit with the rear center portion of the cavity I3, and a second passage `I1 connects the forward end of the acetylene conduit eccentrically with the rearv end of the cavity I3.

',I'he connecting means J by which the body B is connected to the handle A, comprises a nipple I8, having an external annular shoulder I9 formed thereon near its rear end. An axial passage 20 extends through the nipple I8,.and is carried rearwardly beyond the rest of the nipple by a, projection 2|, and is carried forwardly of the rest of the 'nipple b y a projection 22 (see Fig. 1). A conical seat 23 is provided on the nipple at the end of the projection -2I, and a conical seat 24 is provided at the end of the projection 22, for a' purpose which will later appear. A plurality of longitudinal'passages 25 extend through the nipple I8 eccentric tc, and in a direction sub# stantially 'parallel to that of the axial passage 20; and a conical seating surface 26 is provided toward the rear end of the nipple I8 surrounding the ends of the longitudinal passages 25.

A hollow nut 21,' having an internal shoulder 28 at its rear end, is formed to t over the nipple I8 with its internal shoulder in contact with the external shoulder I9 o'n the fnipple. When the hollow nut 21 is in place on the nipple i8 with its shoulder 23l in 'contact with' the shoulder I9 of the nipple, it extends rearwardly beyond the projection 2i, thereby protecting the seat 23 thereon. A retaining ring 23 is resiliently held in a groove 30 in the nipple immediately ahead of the hollow Anut 21 and maintains the latter in the-position which has -lust been described.

When th'e hollow nut 21 is 'screwed upon theI externally vthreaded nipple end I2 of the forward block I i, the "conical seats 23 and 25 on the nipple I3 seat in gas-tight contact with corresponding surfaces. and 32-respectively, in the cavityl3 4of the forward block II. Thus, the axial passage 2l through the nipple extends in gas-tight continuation of the oxygen passage I3 in the'forward block II and the plurality of 'eccentric passages 2l through the nipple extend in continuation of .an annular chamberv 33 Awhich is formed in the cavity l: when ciosed by the nipple la 'with the extension 2|. extending therethrough.

.illustrated is that which surface 36 surrounds the end of an oxygen duct 31 which extends forwardly of the recess in the body B. f The forward projection 22 on the nipple IB extends through the recess beyond the rest of the nipple, thus forming with the walls of the recess 35 anannular chamber 38 into which the plurality of eccentric passages 25 lead,

The nipple I3 is'-. preferably made of sturdy construction with heavy tubular walls on the extensions 2I and 22, in order to provide broad seats 23 and 24 thereon. Thus, when the nipple is attached, the seats 23 and 24 come against the corresponding seats 3I and 36 with a definite, sure stop which makes gas-tight assembly certain. Attachment between the nipple and the body B is preferably made permanent. Accordingly, in attaching the nipple I8 to the body B, the threads 34 at the forward end of the nipple and the seat 24 may 'rst betinned, and the nipple is then sweated into the body B.

It is further preferred to form the body B of pressure-forged metal instead of a casting, in

'I'he body B has a large oxygen valve chamber' 39 therein into which the oxygen duct 31 extends from the forward end of the axial passage 20 in the nipple .I 8. Any known or convenient highcapacity valve mechanism may be used to control the passage of cutting oxygen through the l valve chamber 39 to a discharge duct 4U formed in the. body B. I'he valve mechanism 4I here is described in our Patent No'. 2,213,043 for Blowpipe, issued August 27, 1940, and is operated by a lever 42 pivoted, as at 43, to the body B, also as described in our aforesaid patent application. Other forms of valve mechanism and other operating means might be employed. A cutting oxygen conduit 44 has one end fitted into the body B at the forward end of the discharge duct 4l, and extends to the l blowpipe head H, into which its forward end is tted A cutting oxygen passage," extends forwardly in the head to the rear center portion of the cavity 4,3 therein in which the tip T is held by the attaching n ut N. y

The mixer which is employed to form a combustible mixture 'of acetylene and combustionsupporting oxygen is Asomewhat similar to that which vis described 2,198,341 of Wilgot J. Jacobsson, one 'of the in- Blowpipe," issued April 23, 1940. This mixer vis formed by disposing a specially formed mixing assembly in an elongated cavity inthe body B, in a manner which will-.now be explained. A bore 41 extends through the body B, oifset from,'and substantially parallel to the axis of the recess u therein. The cavity thus i formed continues forwardly through a tube or large conduit which islas-tightly connected to the body B, as by silver-soldering at 4l. The

and claimed' in Patentv elongated cavity. It comprises a mixing element or mixer nozzle 53, an elongated conduit 54, and a rear block 55', all rigidly connected together in coaxial series alignment and removably disposed in the lelongated cavity. A passage 56 extends substantially axially through the mixingv element 53, and a passage 51 extends substantially axially through the rear block 55, each passage being a continuation of the passage through the elongated conduit 54. An annular shoulder 58, formed on the rear block 55 adjacent lits forward end, contacts an internal shoulder 59 of the bore 41 and thereby limits the axial position of the unitary assembly within the elongated cavity, and also positions the mixing element 53 axially of the elongated cavity. Contact between the annular shoulders 58 and 59 also seals thecontinuous passage through the' mixing assembly from the annular passage or .chamber between the lelongated conduit 54 and the elongated cavity ahead of the rear block 55 and prevents passage of gas from the elongated cavity on one side of the rear block to the other, except through the passage 51. The rear block 55 is internally threaded in order that an instrument may be inserted therein for withdrawing the V'unitary assembly from the elongated cavity. An ordinary long machine screw will serve for this purpose.

The mixing element 53 which is illustrated in the drawings is substantially cylindrical in form and its forward end is a 4plane face 60 transverse to the axis of the element, and preferably stands at substantially right angles to this axis. The length of the mixing assembly is such that when 'the annular shoulder 58 on the rear bl'ock 55 contacts the internal shoulder 59 of the bore 41 the plane face 60 at the forward end of the mixer is closely juxtaposed to, but slightly spaced from, the face 52 at the rear end of the mixture conduit. Thus, a narrow gap 6I is formed between the two faces. The passage 58 through the mixingelement 53 is shown as being constricted-at its forward end,-as as 62, in order to provide a metering orifice land to give increased velocity to the gaspassing through the mixing assembly as the mixing elementcontact the inner wall of the elongated cavity and space the mixing element therefrom to provide a'passage around the mixing element. The 'gap 6I and the passage along the outside of the mixing e1ement53 are of sunlcient size to permit the passage of backres. As the diameter of the rear block 55 is so chosen that the block ts exactly within the bore 41, the mixthe conduit 54 and along the outside of the mix- 'and at right angles thereto.

41 and closes the end of the bore beyond the locking screw 64.

Combustion-supporting oxygen is carried from the passage 31 to the axial passage through the mixingassembly by means of a duct 68 opening into the passage 31, a valve chamber 69 at the far end of the duct 68, a second duct 10 leading from the valve chamber 63 to an annular groove.

1I in the rear block 55, and a radial passage 12 extending from the annular groove 1I through the rear block 55V to the axial passage 51 therein. A valve 13 in the valve chamber 69, operated by a valve wheel 14, controls th'ev passage of combustion-supporting oxygen to the mixing assembly. i A vAcetylene flows throughthe eccentric passages 25 in the nipple I8 into the annular chamber 38,'

whence it passes through a bore 15 in the body B to the rear end of a passage 16 extending forwardly through the body B. One of the conduits 11 of the group generally designated as C has its rear endterminating at and fitted into the body B at the forward end of the passage 16. The conduit 11 is connected at its forward end toI the head H where a cross bore or header 18 connects its forward endl to the end of a second conduit 18 which extends substantially parallel to the conduit 11 and has its rear end terminating at and fitted into the body B. The conduits 11 and'19 and the header 18 thus provide a generally U- Ishaped passage, disposed between the body member B andthe forward end of the blowpipe, having a return bend at the front and having two terminals at the rear in -the body member. A passage 80 in the body B extends substantially parallel to the passage 16 from the rear end of the conduit 18 and is intersected by a cross passage 8| which opens into thebore 41 ahead of the rear block 55. Thus, acetylene from the conduit I5 in the handle A ows forwardly through the passage I1 in thev head block II to the annular chamber 33; (Thence, -the acetylene continues forwardly through the eccentric passages 25 in` the nipple I8 till it reaches the annular chamber 38. From this point, the acetylene passes forwardly through the bore 15, into the passage 16, thence through the conduit 11 to the head H, through the cross passage 18 in the head, back' it issues'therefrom. A plurality of widely spaced y y I passage 56 crosses the narrow gap s. and enters radial projections 63 around the periphery of the mixing throat 82, forming the rst section of the mixture conduit 5I, at a high velocity. The

creates a vacuum in the narrow gap 6I. 'Ihis vacuum causes the acetylene to flow forwardly through the elongated-annular chamber around ing element 53 to the narrow gap 6I where'it moves inwardly at increasing velocity until it.

meets the stream of oxygen on all sides thereof l The two gases thereupon mix as they enter the mixing throat 82. `From the mixing throat, the mixed gases pass into the second section of the mixture conduit 5I, namely, an expansion passage 83 where theY velocity, of the mixed' gases is reduced.

Thence the mixed gases pass through ia passage 84 in the head H`to a portion of the cavity 46 therein, whence they enter the usual combustible mixture passages in the tip T in conventional element in the acetylene. line.

manner and are discharged from the blowpipe. The two gases thus increase their velocity immediately before they come in contact with one another, and meet at right angles to each-other.

The mixing action of the two gases is essentially independent of the acetylene pressure, as,

if the acetylene pressure is high, for instance, the needle valve controlling the flow of acetylene m'ay be manipulated to throttle this flow and thereby maintain a fixed vacuum at the gap 6l regardless of the acetylene pressure. The value of the vacuum may be so chosen that the aspiration action of the oxygen on the acetylene will insure the correct gas mixture for the particular nozzle or tip T being used.

Should a backfire occur, it will first enter the mixture conduit 5|, which is formed of a metal having high heat conductivity and which has exceedingly thick walls. The mixture conduit will therefore extract and dissipate much of the backfire heat quite rapidly. The danger that this part may be damaged or burnt out is accord-4 ingly minimizedi` Next, the backfire must pass through a, metering constriction in either gas line, such as the metering constriction B2 in the oxygen line, or the metering constriction provided by the gap 6I or the space surrounding the mixing The cushioning effect of the large volumes of gas in each supply line back of the mixing element tends to drive the backfire forwardly of the blowpipe again. Should a backfire pass either metering constriction, it would be smothered in the largepassage behind that constriction without continuing to burn and become a flashback. Usually, because of the relatively low pressure of the acetylene as compared with that of the oxygen, the major portion of the backfiring gases passes .along the outside of the mixer nozzle 53, which is spaced from the internal wall of the cavityrand from the rear end of the mixture conduit 5| to provide a passage of sufficient size to permit the passage of backflres. This portion of the backfire then is extinguished in the large volume of acetylene contained in the annularvchamber surrounding the combustion-supporting gasconduit 54 and in the U-shaped passage formed by the conduits 11 and 19 and the header 1I. By the described construction, therefore, a highly flashback-resistant blowpipe has been provided in which the distance between the rearL body member and the forward end of the blowpipe is maintained unusually short, so that the blowpipe may be attached'to an ordinary welding blowpipe handle without producing a long and unwieldy assembly.

The large volume of acetylene contained in the space between the elongated conduit 5I and the inner wall of the elongated cavity which sur- .rou'nds it,A and, back of that, in the U-shaped passage havingterminals in the body formed by assures .a steady even 1. A blowpipe comprising, in combination, a body member; a combustible gas mixture con# duit; means providing a cavity terminating at its rear end in said body member, and terminating at its forward end at the rear end of said mixture conduit; means at the forward end of said blowpipe for discharging a combustible gas mixture; a mixer nozzle in said cavity, the external wall of said mixer nozzle being spaced from the internal wall of said cavity and from the rear end of said mixture conduit to provide along the outside of said mixer nozzle a passage of suicient size to permit the passage of backfires; means providing a generally U-shaped fuel-gas passage'having an appreciable volume disposed between said body member and the forward-end of said blowpipe, said fuel-gas passage having a return bend at the front'thereof and having two terminals at the rear thereof in said body member, said fuel-gas passage being adapted to contain a large volume of fuel gas for receiving and extinguishing backfires, therebypreventing flashbacks; means providing a passage communicating 'between one of said terminals and the passage along the' outside oi.' said mixer nozzle; means for supplying fuel ing gas conduit in said cavity spaced from thel l internal wall thereof to provide an elongated'anconduits 11A and 19, so flow of acetylene ra ally inwardof the gap 6I regardless of conside le changes in acetylene pressure.A Since the mixing action of the mixing element herein described, is not dependent` upon pressure, the blowpipe may be employed eili-` ciently over wide ran'gesof fuel gas pressure.

The form of the invention here described and illustrated in the accompanying drawing is disclosed merely to indicate how the invention may be applied. Other forms differing in detail but not in principle from that here shown and described, will, of course, suggest themselves to those skilled in the art.

We claim: f

4.ciable volume;

cured to the forward ed of said combustionnular chamber having an appreciable volume; a mixer nozzle in said cavity secured to the forward 'end-*of said combustion-supporting gas con-v duit, said mixer nozzle being so constructed and arranged that` backfires will pass into said annular chamber; means providing a generally U- shaped fuel-gasl passage having an appreciable volume disposed between said body member and the 4forward end of said blowpipe, said fuel-gas passage having a return bend at the front thereof and havingtwo terminalsat the rear' thereof in said body member; means providing a passage in i said body member communicating between one of said terminals and said annular chamber; 1 means for supplying fuel-gas to the other of saidv terminals and means for supplying combustionsupporting gas to said combustion-supporting gas conduit; said U-shaped fuel-gas passage and said annular chamber cooperating to contain together a sufiiciently large volume of fuel gas to receive and extinguish backres passing said mixer nozzle, thereby preventing flashbacks.

3. A blowpipe comprising, combustible gas mixturejconduit; ahead member at the forward end of said mixture conduit; a body member; cavity. terminating at its forward end at the rear end of said mixture conduit, and terminating at its rear end in said body member; an elongated combustion-supporting gas conduit in said cavity spaced from the internal wall thereof to provide an elongated annular lchamber having an apprea mixer nozzle in said cavity sesupporting gas conduit, said mixer nozzle being so constructed and .arranged that backfires will pass into said annular chamber: means providing in combination, a

means providing an elol'igated.

2,238,470 Y l l 5 a generali-y.- U-shaped Vfuel-gas passasehaving an appreciable volume comprising a header in said .headmemben and 'two conduits, each conduit being in communication at its forward end with said header4 andterminatingat its rear end in said body member; means providing a passage in said body'member communicating between one of said lastfnamed conduits and said annular cham- Hbei-:'.means forsupplying fuel gas to theother` ofsaid last-named conduits; and means for :s'up- 10 l plyingcombustionfsupportins gas to said com` bustion-supporting gas'oonduit: said U-shaped fuel-gas passage and said annular'chamber cooperating to containtogether a .sumciently large y volume of fuel gas to receive and extinguish backres passing said mixer nomic,4 thereby preventing flashbacks.

wnaor J. JAcoBssON.

Y normanna,v

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