EP0676024B1 - Gas torch nozzle - Google Patents

Abstract

The invention relates to a gas torch nozzle, comprising a nozzle body with axial gas supply channels. According to the invention, there is provided an outlet ring (115) mounted on the distal end of the nozzle body (101), said ring having a large number of small axial holes (117) forming outlet orifices, and a traversing element (120) made of porous metal, for example sintered metal, is arranged between the downstream end of the supply channels (103) and the above mentioned outlet ring (115), said element letting the gas pass through said axial holes during normal operation of the torch in order to obtain a flame fractionated into small tongues, but stopping the propagation of the flame upstream when igniting said torch. Preferably, the number and the cross-section of said axial holes (117) are selected to that the outlet ring (115) acts also as a noise limiter.

Description

The invention relates to the field of torches, in particular torches which can be used in cutting techniques (flame cutting for example) of flame machining (in particular any oxy-fuel torch), of stripping, of stripping, or of surface quenching.

Whether it is heating nozzles, or even cracking or flame cutting nozzles, the risks of flashbacks in the use of torches is well known, and manufacturers are always seeking to minimize these risks which are the cause of serious accidents.

It has already been proposed to mount, inside the nozzle body and far behind the outlet orifice, a porous element intended to constitute a safety barrier in the event of a flashback. Such a solution is for example illustrated in the documents CH-A-472 632 and FR-A-1 448 292.

This is how FR-A-1 448 292 describes a gas torch nozzle, comprising a nozzle body provided with axial gas supply channels which open in the vicinity of the distal end of the nozzle body, the gases passing through a porous metal through element arranged inside said nozzle to block the propagation of the flame upstream when said torch is lit.

The gas torch nozzles described in these documents also have a single outlet orifice forming a wide flame releasing the heat at a considerable distance from said orifice.

For there to be a flashback, it is necessary to combine the arrival of a mixture of detonating gas in the body of the torch or in the supply hoses of this torch, and the ignition of this mixture of detonating gas by A flame. Accidents generally occur when the torch is ignited, or following projections of molten metal against the front of the nozzle, blocking the gas outlet holes. Indeed, it happens that the operator opens the gas inlet valves, and presents a flame at the end of the nozzle to light the torch, without having taken the time to purge and without having established the normal gas flow rate.

The above-mentioned solution is not entirely satisfactory, since the safety barrier is relatively far from the outlet orifice of the nozzle, and it is not possible to mount it near this outlet orifice, because the formation of the flame would be too disturbed.

The danger is particularly important in the case of cutting torches, pickling, oxy-welding, oxy-brazing, or even oxygen-cutting. Indeed, if for any reason, which may be simply negligence in the careful closing of the valves during the previous shutdown of the torch, oxygen is introduced into the gas circuit or vice versa, the fact of presenting the flame at the end of the nozzle ignites the mixture, propagates the reaction wherever there is actually a flammable mixture, and it is then the accident.

The object of the invention is to improve the safety of the torch nozzles with regard to the risk of accident due to flashback, while allowing the flame to be structured, giving the nozzle great flexibility of use and high precision. Operating.

The object of the invention is therefore to produce a gas torch nozzle, the structure of which makes it possible to effectively counter the inadvertent ignition of a mixture of detonating gas, in particular during the lighting of the torch, whatever the type. torch, while organizing the structure of the flame to have a more concentrated heat near the outlet of the nozzle.

It is more particularly a gas torch nozzle, comprising a nozzle body provided with channels axial gas supply which open in the vicinity of the distal end of the nozzle body, the gases passing through a porous metal through element arranged inside said nozzle to block the propagation of the flame during ignition of said torch, characterized in that it comprises an outlet ring mounted on the distal end of the nozzle body, said ring having a plurality of small axial holes forming outlet openings for said nozzle, and that the through element of porous metal is interposed between the downstream end of the supply channels and the aforementioned outlet ring, said element allowing the gases to pass through the axial holes during normal operation of the torch to obtain a fractional flame in small darts .

The porous metal through element is therefore close to the outlet of the nozzle, and the flame is structured in a plurality of small darts, which makes it possible to concentrate the heat in the immediate vicinity of the outlet, while allowing to modulate without risk the flame thanks to the presence of the through element. The realization of small heating holes also makes it possible to hinder, even to prohibit, the penetration of the liquid metal projected against the nozzle inside the holes by simple phenomenon of capillarity combined with the use of a higher pressure of gas ejection.

Preferably, the number and the section of the axial holes of the outlet ring are chosen such that the total section of these axial holes corresponds substantially to the total section of the gas supply channels, to simultaneously perform a limiter function. noise.

In accordance with a particular embodiment, the through element is produced in the form of a crown or a flat washer, which is arranged in the immediate vicinity of a distribution chamber common to the gas supply channels. In particular, the through element is mounted in the outlet ring, while being in abutment against an associated shoulder.

The through element may be made of sintered metal, in particular bronze or brass.

It may also be advantageous for the nozzle to further comprise at least one filter element disposed in front of the inlet orifices of the axial gas supply channels, in order to retain the impurities carried by the gases during the operation of the torch and avoid thus the clogging of the through element. Advantageously then, the proximal end of the nozzle body has at least one circular gas distribution groove into which the inlet orifices of the axial channels open, this groove or each of these grooves then receiving a filter element produced in the form of 'a porous ring.

More preferably, when it is a nozzle more particularly intended to equip a cutting or flame cutting torch, the nozzle body has a central nozzle for the passage of oxygen and axial channels arranged around this nozzle for the passage of heating gases, and the through element is produced in the form of a crown mounted on the distal end of said nozzle.

Advantageously then, the outlet ring associated with the through element is threaded onto the distal end of the nozzle body forming the outlet of the nozzle, and this ring is fixed by brazing to said body. In particular, the outlet ring is surrounded by a protective ring which is fixed simultaneously by the aforementioned brazing.

• la figure 1 est la coupe axiale d'une buse de chalumeau à gaz, ici de chalumeau de décriquage, dont la structure est conforme à l'invention ;
• les figures 2 et 3 illustrent, respectivement en coupe et en vue en bout, le corps isolé de la buse de la figure 1 (sans l'élément traversant en métal poreux ni la bague de sortie associée) ;
• les figures 4 et 5 sont des vues respectivement en plan et en coupe (la figure 5 est une coupe selon V - V de la figure 4) de l'élément traversant en métal poreux, ici réalisé sous la forme d'une couronne plate ;
• la figure 6 est une vue en coupe de la bague de sortie qui assure le maintien de l'élément traversant en métal poreux précité, permettant de mieux distinguer l'épaulement d'appui associé et l'un des nombreux petits trous axiaux de cette bague, ces trous étant ici agencés sur une seule rangée circulaire ;
• la figure 7, qui est à rapprocher de la figure 1, illustre une variante de la buse précédente, dans laquelle des éléments filtrants sont en outre prévus à l'entrée des canaux d'amenée des gaz de chauffe, ici sous la forme de deux anneaux poreux, pour retenir les impuretés véhiculées par les gaz lors du fonctionnement du chalumeau et éviter ainsi le colmatage de l'élément traversant.

Other characteristics and advantages of the invention will appear more clearly in the light of the description which follows and of the appended drawings, relating to a particular embodiment of the invention, in reference to the figures where:

• FIG. 1 is the axial section of a gas torch nozzle, here of a cutting torch, the structure of which is in accordance with the invention;
• Figures 2 and 3 illustrate, respectively in section and in end view, the insulated body of the nozzle of Figure 1 (without the porous metal element or the associated outlet ring);
• Figures 4 and 5 are views respectively in plan and in section (Figure 5 is a section along V - V of Figure 4) of the through element of porous metal, here produced in the form of a flat crown;
• Figure 6 is a sectional view of the outlet ring which ensures the maintenance of the aforementioned porous metal through element, to better distinguish the associated support shoulder and one of the many small axial holes of this ring , these holes being here arranged in a single circular row;
• Figure 7, which is close to Figure 1, illustrates a variant of the previous nozzle, in which filter elements are further provided at the inlet of the heating gas supply channels, here in the form of two porous rings, to retain impurities carried by the gases during the operation of the torch and thus avoid clogging of the through element.

FIG. 1 makes it possible to distinguish a gas torch nozzle 100 according to the invention, comprising a nozzle body 101 (the structure of which will be better understood by referring to FIGS. 2 and 3), which is here of generally cylindrical shape ( the axis of the nozzle body is marked X), said body being provided with axial gas supply channels 103 which open through outlet orifices associated in the vicinity of the distal end 111 of the nozzle body 101. The nozzle of torch illustrated here is used to equip a slewing torch, which explains the presence of a central nozzle 102 associated with the passage of oxygen, nozzle whose inlet is referenced 102.2 and outlet 102.1, the aforementioned axial channels 103 then being arranged around this nozzle to ensure the passage of the heating gases. However, this is only an example, and it goes without saying that the invention can also be applied to any other type of gas torches, in particular to conventional type heating torches, the nozzle body of which is then free of central nozzle. In particular, in the case of stripping torches, surface quenching or heating, one could have a nozzle body having in section a polygonal shape (in general rectangular or octagonal), with an axis or several parallel axes (usually two axes).

According to an essential aspect of the invention, the nozzle 100 comprises an outlet ring 115 mounted on the distal end of the nozzle body 101, said ring having a plurality of small axial holes 117 forming outlet openings, and a traversing element 120 made of porous metal is interposed between the downstream end of the supply channels 103 and the aforementioned outlet ring 115, said traversing element allowing the gases to pass downstream in these axial holes during normal operation of the torch for the 'Obtaining a fractional flame in small darts, but barring in a manner known per se the propagation of the flame upstream during the lighting of said torch.

Thus, during the lighting of the torch, the through element 120 made of porous metal constitutes a barrier to the propagation of the flame, which barrier is in the immediate vicinity of the outlet of the nozzle, and prevents the ignition reaction of the mixture. detonating gas to propagate wherever the flammable mixture is actually found, in the event that oxygen is introduced into the gas circuit or vice versa, due in particular to negligence on the part of the operator when previous shutdown of valves when the torch stopped. The through element 120 does not in any way prevent the normal operation of the torch (the direction going from upstream to downstream), with its flame structured in a plurality of small darts, and constitutes an extremely effective barrier to the propagation of the flame (the direction going from downstream to upstream).

The through element 120 can be produced in the form of a crown or a flat washer, made of sintered metal, in particular bronze or brass. In this case, as can be seen more clearly in FIGS. 4 and 5, the through element 120 is produced in the form of a circular crown, mounted on the distal end 111 of the central nozzle. When it is a nozzle intended to equip other types of torches, the through element 120 may be produced in the form of a washer, circular or not, in direct support by an associated shoulder against the distal end of the nozzle body.

The through element 120 is interposed between the nozzle body 101 and the outlet ring 115 which is also mounted on the distal end 111 of the nozzle. The through element 120 is here disposed in the direct vicinity of a distribution chamber 112, which is an annular chamber common to the various gas supply channels 103. The arrangement of this distribution chamber 112, and of the distribution channels lead 103 associated, will be better understood by referring to Figures 2 and 3. In this case, each of the feed channels 103, here four in number, ends on the upstream side by an axial branch opening at a orifice 104 in an associated distribution groove 107, for example associated with the arrival of heating oxygen, and also by a branch branch 105 which opens, at an associated orifice 106 in another distribution groove 108, for example associated with the fuel supply. There is also a distinction, on the downstream side of the nozzle, a circular bearing edge 113 that the through element 120 contacts when it is placed on the distal end of the nozzle. Maintaining the through element is ensured by the outlet ring 115 also mounted on the distal end of the nozzle of the nozzle body 101, a ring whose structure will be better understood by referring to the section in FIG. 6.

The outlet ring 115 has a central bore 116 which corresponds to the outside diameter of the distal end 111 of the nozzle body, so as to avoid any untimely passage of gas at the contact surfaces. The outlet ring 115 also has a plurality of small axial holes 117 which are associated with the outlet of the heating gases, for example arranged in a single circular row as illustrated here. By "a plurality", it is necessary to understand a number much greater than that of the gas supply channels, and by "small section" means a section much less than that of said supply channels. These small axial holes 117 carry out a fractionation of the flame, which takes the form of as many small darts concentrating the heat at a short distance, which can be determined with precision, from the outlet of the nozzle.

Preferably, the number and the section of the axial holes are chosen such that the total section corresponds substantially to the total section of the gas supply channels 103, so as to simultaneously perform a noise limiter function.

For example, when using as here four supply channels 103 whose inlet diameter is of the order of 4.5 mm, thirty-eight to sixty axial holes 117 of a diameter of 1.5 to 1.2 mm, for example distributed regularly over a circumference of the retaining ring, the length of these axial holes being in the order of 10 mm. The arrangement of these axial holes will more generally be provided along one or more lines, this or these lines being able to be rectilinear or curved as the case may be: the distribution along a circular line illustrated here therefore constitutes only one example.

Thanks to this large number of axial holes of very small diameter, it is possible to limit the amount of movement of the flame, and consequently considerably minimize the noise of the torch during its operation. The outlet ring 115 also has, on the upstream side, a support shoulder 118, against which the through element 120 abuts: the through element is then mounted in the outlet ring. In this case, a shoulder 119 is also provided which comes into direct contact with the circular bearing edge 113 of the nozzle body 101, so as to avoid any risk of crushing of the porous metal through element during precise mounting. of the ring 115.

The through element 120 is in the present case in the form of a circular crown of sintered metal, the thickness of which can be of the order of 3 mm, with an internal diameter which is here of the order of 20 mm, and an outside diameter of the order of 32 mm. The outlet ring 115, which is for example made of cupro-tellurium, is preferably threaded with the through element 120, after prior positioning of the latter, on the distal end 111 of the nozzle body 101, and the connection of this ring to said nozzle body is ensured by soldering denoted 125 in FIG. 1. A protection ring 114 is also provided here surrounding the outlet ring 115, a protection ring which is preferably also fixed simultaneously by the aforementioned brazing.

The torch nozzle thus equipped can have any geometry on the outside, and its fixing can be carried out in a completely traditional way by a fixing nut 109 mounted rotatably on the body of nozzle.

The choice of arrangement of the small axial holes used to split the flame therefore makes it possible to adapt the nozzle to the desired needs, the number and the geometry of these holes also making it possible to optimize the efficiency of the torch. It is possible to produce a flame which is more effective than the single dart flame of the known nozzles, while considerably lowering the noise level during operation.

Figure 7, which is similar to Figure 1, illustrates a variant of the previous nozzle, in which filter elements are further provided to retain the impurities carried by the gases during the operation of the torch and thus avoid clogging of the through element.

The torch nozzle illustrated in FIG. 7 differs from the previous one only by the presence of two filter elements 121, 122, which are arranged in front of the inlet orifices 104, 106 of the axial gas supply channels 103. In this case, due to the presence of two distribution grooves 107, 108 at the proximal end 110 of the nozzle body 101, two filter elements 121, 122 are each provided in the form of a ring porous. The presence of such filter elements is particularly advantageous insofar as the sintered metal has the disadvantage of retaining the impurities carried by the gases, from which there arises a risk of clogging which can impair the proper functioning of the nozzle. One or the other of these filter elements can naturally be produced differently, for example in the form of an easily removable filter cartridge, which makes it easy to ensure cleaning and / or replacement. The porous rings 121, 122 may also be glued to the nozzle body, or simply wedged in the associated distribution grooves of said nozzle body.

We thus managed to produce a gas torch nozzle whose structure makes it possible to effectively counter the inadvertent ignition of a mixture of detonating gas, in particular during the lighting of the torch, and this for very different types of torches: it is therefore a real safety nozzle. In addition, thanks to the presence of the outlet ring which acts simultaneously as a means of fractionating the flame, as a means of holding the through element in porous metal, and as a noise limiting means, it then becomes possible to design the architecture of the nozzle, in particular by looking for the least noisy outlet flows for a heating power or for a required flame shape, without being dependent on the speed of the explosion of the mixture.

Claims (10)

1. A gas torch nozzle (100), said nozzle comprising a nozzle body (101) provided with axial gas feed channels (103) which emerge in the vicinity of the distal end (111) of the nozzle body, the gases passing through a gas-passing element (120) of porous metal arranged inside said nozzle to block the propagation of the flame in the upstream direction when said torch is being lit, the nozzle being characterized in that it includes an outlet ring (115) mounted at the distal end of the nozzle body (101), said ring having a plurality of small axial holes (117) forming outlet orifices for said nozzle, and in that the gas-passing element (120) of porous metal is interposed between the downstream end of the feed channels (103) and the aforementioned outlet ring (115), said element allowing the gases to pass through the axial holes (117) in normal operation of the torch so as to obtain a flame which is split into small jets.
2. A nozzle according to claim 1, characterized in that the number and cross-section of the axial holes (117) in the outlet ring (115) are chosen so that the total cross-section of these axial holes is substantially equal to the total cross-section of the gas feed channels (103), so as to simultaneously provide a noise-limiting function.
3. A nozzle according to claim 1 or claim 2, characterized in that the gas-passing element (120) is constructed in the form of an annulus or a flat disk, arranged in the direct vicinity of a distribution chamber (112) which is common to the gas feed channels (103).
4. A nozzle according to claim 3, characterized in that the gas-passing element (120) is mounted in the outlet ring (115) and bears against an associated shoulder (118).
5. A nozzle according to any of claims 1 to 4, characterized in that the gas-passing element (120) is made of sintered metal, in particular of bronze or brass.
6. A nozzle according to any of claims 1 to 5, characterized in that the nozzle further includes at least one filtering element (121; 122) arranged in front of the inlet orifices (104; 106) of the axial gas feed channels, so as to trap impurities carried by the gases during operation of the torch and thereby prevent the gas-passing element (120) from becoming clogged up.
7. A nozzle according claim 6, characterized in that the proximal end of the nozzle body (101) has at least one circular gas distribution groove (107; 108) into which the inlet orifices (104; 106) of the axial channels emerge, this or these grooves then receiving a filtering element (121; 122) which is in the form of a porous ring.
8. A nozzle according to any of claims 1 to 7, more particularly where the nozzle is intended to be fitted to a flame descaling or oxygen cutting torch, in which the nozzle body (101) has a central pipe (102) for passing oxygen and axial channels (103) formed around that pipe for the passage of the heating gases, the nozzle being characterized in that the gas-passing element (120) is in the form of an annulus mounted on the distal end (111) of said pipe.
9. A nozzle according to claim 8, characterized in that the outlet ring (115) associated with the gas-passing element (120) is threaded onto the distal end (111) of the nozzle body (101) to form the outlet for the pipe, and in that this ring is brazed to said body.
10. A nozzle according to claim 9, characterized in that the outlet ring (115) is surrounded by a protective ring (114) which is simultaneously secured by the aforementioned brazing step.

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