MXPA00006391A - Cutting nozzle assembly for a postmixed oxy-fuel gas torch - Google Patents

Abstract

A novel cutting nozzle assembly for a postmixed oxygen-fuel gas torch is disclosed. The nozzle assembly includes a cylindrical shroud which surrounds and extends away from the gas discharge orifices in the gas discharge end of the cutting nozzle. The cylindrical shroud has the advantage of producing a tighter gas stream and of promoting a more thorough mixing of the preheat oxygen and the fuel gas to provide a hotter, more compact flame which produces a more parallel-sided cut through metal workpieces. The cutting tip therefore conserves metal as well as cutting gases. It also cuts faster than prior art postmixed cutting nozzles

Description

CUTTER NOZZLE FOR A GAS TORCH OXYGEN AND FUEL, MIXED SUBSEQUENTLY TECHNICAL FIELD The present invention relates to torches of oxygen gas and fuel and, in particular, to a cutting nozzle for torches of oxygen gas and fuel, mixed later.

BACKGROUND OF THE INVENTION Gas and oxygen gas cutting torches are useful for cutting ferrous alloys. With the appropriate equipment, cuts can be made through very thick ingots. During operation, an oxygen and fuel torch is used to direct a burning stream of oxygen gas and fuel onto the surface of the metal to be cut. The metal is thus heated to its ignition temperature, at this point, a stream of cutting oxygen, directed to the surface, oxidizes the heated metal to effect this cut. The cutting torch may be of the pre-mix or post-mix type. In a pre-blended torch, the preheated oxygen and fuel gas is mixed inside the torch head, before being discharged for ignition. In a rear mixing cut torch, the preheated fuel oxygen gas is discharged from the torch into streams if mixed. The turbulence in the discharged streams mixes the oxygen and the combustible gas before ignition occurs. A major advantage of the subsequently mixed cutter blowtorch is that it does not undergo flashback, a potential hazard associated with the use of pre-mix torches. The recoil of the flame occurs when the mixture of oxygen gas and fuel in a pre-mix torch ignites inside the torch head. Subsequent mixing torches are therefore preferred for heavy industrial applications where a torch is subjected to considerable heat. An additional advantage of the back mix torch is that the back mix nozzles produce a larger heat zone than the pre-mix nozzles. This allows the back mix torch to operate further away from work, decreasing heat stress in the torch and increasing the service life of the nozzle.

An example of an oxygen and fuel gas cutting torch, after mixing, and nozzle of the prior art are taught in U.S. Patent No. 4,455,176, which was issued to Fuhrhop on January 19. of 1984. That patent describes a combination of a cut-off torch and nozzle assembly for cutting by oxygen and fuel, mixed together, using two separate annular streams of preheating oxygen gas surrounding the fuel gas stream with the preheated oxygen stream , annular, internal, directed to collide with the fuel gas stream very close to the point of discharge from the nozzle assembly. This nozzle assembly is secured to the head of the cutting torch by a hollow retaining nut, which forms an annular recess with the nozzle assembly for discharging the stream of preheated external oxygen gas. All prior art back mixing nozzles for gas and oxygen gas torches operate in substantially the same manner. A stream of cutting oxygen is discharged from an axial bore in the nozzle. A plurality of fuel gas discharge orifices, arranged in a concentric ring around the preheated fuel gas, d discharge from the axial bore, and a second plurality of gas discharge orifices, arranged in an outer concentric ring discharge the oxygen from preheating, which acts as a cover that surrounds the fuel gas stream. As the gas streams flow into the workpiece, a mixture of fuel gas and oxygen occurs and the mixture ignites to heat this workpiece. Tests have shown that up to 50% of the preheating oxygen stream, discharged from the torch nozzles mixed later, of the previous technique, is lost to the atmosphere, before the mixture with the combustible gas occurs. This contributes to inefficient combustion and reduces the heating process. It also contributes to the cost of cutting, so gases are not used to their full potential. It has also been observed that the back-mix torch nozzles of the prior art are incapable of making a parallel side cut through a coarse workpiece. The cut is narrower along the top of the workpiece (ie, near the torch nozzle) than along the bottom of the workpiece. The thicker the piece of work, the wider it has to be cut on the bottom side. If many thick ingots must be cut, a significant loss of the metal will occur. A further disadvantage of the prior art cutting nozzles for subsequently mixed fuel oxygen gas torches is their direct exposure to recoil splashes of the molten metal from the cut. This metal in the recoil splashes tend to adhere to the discharge end of the nozzle, frequently blocking the discharge orifices. When this occurs, the torch must stop operating to allow the nozzle to be cleaned or replaced. This interrupts the workflow and increases operating expenses. In order to overcome these disadvantages of the prior art, a novel cutting nozzle assembly for an oxygen-fuel gas torch, after mixing, was described in applicant's Canadian patent No. 2,109,772, which is entitled CUTTER NOZZLE ASSEMBLY FOR OXYGEN GAS TORCH AND FUEL, REAR MIXING. This patent was issued on April 20, 1999. The nozzle assembly, described in this Canadian patent, includes a nozzle having passages extending from an intake end, to receive gas from the torch to a gas discharge end, to discharge these gases. The nozzle assembly further includes a cylindrical envelope that surrounds and extends away from the gas discharge end of the nozzle, to protect the discharge end of the nozzle from splash back from the molten metal, and to concentrate, direct and promote the mixture of oxygen / fuel gas streams. This results in a narrower, cleaner cut, with more parallel sides, which preserves the metal in the cut and increases cutting speed and efficiency. Also, the service life of the nozzle is increased because the discharge end of the nozzle is protected against return splashes. The wrapper is an integral part of a hollow retainer nut, which is used to receive the nozzle and couple the nozzle assembly to a torch head. The hollow retaining nut is usually produced from a cylindrical metal bar material, which requires a certain amount of materials removed from the metal to form the cavity of the hollow retaining nut. The material required to be removed and the machining time to do so, increase the manufacturing cost of the nozzle assembly. The two-piece structure of the nozzle assembly also requires that the nozzle and wrap be placed together before the assembly can be coupled to the torch. In a workshop or foundry environment, where the cutting nozzles are used, the construction of two pieces makes it possible for one piece to be separated from the other and to be lost. Likewise, in the construction of two pieces, an annular gap must be left between the nozzle and the hollow retaining nut, in order to allow the two parts to be assembled together manually. This gap spacing can affect the exact alignment of the gas discharge passages of the nozzle with the envelope. As a result, the quality of nozzle performance can be compromised.

SUMMARY OF THE INVENTION It is an object of the invention to provide a cutting nozzle that overcomes the disadvantages of the prior art. It is another object of the invention to provide a cutting nozzle having a unitary structure. It is a further object of the invention to provide a cutting nozzle that performs well and is manufactured at a relatively low cost. It is still another object of the invention to provide a cutting nozzle that easily and simply engages a torch, without pre-assembly. According to the invention, a cutting nozzle is provided for a blowtorch of oxygen gas and fuel, subsequently mixed, comprising an integral body, which includes a first end for the connection with a torch of oxygen gas and fuel, the first end has holes for cutting oxygen, fuel gas and preheated oxygen, respectively; and a second end for discharging the cutting oxygen, the fuel gas and the preheating oxygen, and this second end is surrounded by a casing, extending away from the second end, to promote a mixing action of the discharged gases from the second end. the nozzle and produce a gas stream that maintains its configuration over longer distances compared to a subsequent mixing nozzle that does not have this envelope. Preferably, the envelope includes a circular cylinder, having an open end and a chamber defined by a side wall of the circular cylinder. The holes at the first end may include an axial hole for the cutting oxygen, a first plurality of holes for the fuel gas and a second plurality of holes for the preheating oxygen, the first and second plurality of holes respectively surround the axial hole for cutting oxygen. All boreholes end in discharge orifices at the second end for the discharge of gases into the chamber and produce the stream of mixed and longer gases. The integral body of the nozzle preferably includes a helical thread, which is adapted to be coupled to a complementary thread in the oxygen gas torch and fuel, mixed subsequently, and parallel flat surfaces, which can be grasped by a wrench for coupling the nozzle to the gas torch of oxygen and fuel, mixed later, or to remove the nozzle from the torch. Therefore, the present invention provides a unitary structure for a cutting nozzle of a gas and oxygen fuel blowtorch subsequently mixed, the cutting nozzle has a casing extending away from the discharge end of the nozzle, to protect This discharge end of the splash d retreat of the molten metal and promote the mixing of the gas stream of oxygen and fuel. The nozzle also includes a helical thread and gripping surfaces, which are an integral part of the exterior of the nozzle body and used to attach the nozzle to the torch. The unitary construction of the nozzle reduces the machining time and the waste of material during the manufacture of this nozzle, in this way, material and manufacturing costs are reduced. Likewise, exact alignment of the discharge passages of the nozzle with the envelope is facilitated by the unit construction, and the quality of the nozzle performance is ensured.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be more fully described, by way of example only, with reference to the following drawings, in which: Figure 1 is a longitudinal cross-sectional view of a preferred embodiment of the torch nozzle of subsequent mixing, according to the invention; Figure 2 is a top plan view of the rear mixing nozzle, shown in Figure 1; Figure 3 is a longitudinal cross-sectional view of a second embodiment of a rear mixing nozzle, according to the invention; Figure 4 is a top plan view of the rear mixing nozzle, shown in Figure 3; and Figure 5 is a partial cross-sectional view of the rear mixing nozzle, shown in Figure 1, coupled with a rear mixing cutting torch.

DETAILED DESCRIPTION OF THE PREFERRED MODALITY Figure 1 shows a longitudinal cross-sectional view of a cutting nozzle, according to a preferred embodiment of the invention. This cutting nozzle is an integral body, generally indicated by the reference number 10, which includes a nozzle portion 12, having an intake end 14, adapted to be received in a nozzle seat of the oxygen torch and mixed fuel later (see Figure 5). The intake end 14 includes an axial bore 16 for the cutting oxygen, a plurality of fuel gas bores 18, arranged in an internal concentric ring, around the axial bore 16, and a plurality of boreholes 20 of the preheating oxygen, arranged in an outer concentric ring, around the axial bore 16. Each of the bores 16, 18 and 20 extends from the intake end i4 and ends in a discharge orifice 22, 24 and 26, respectively, at an end 28 of discharge of the nozzle portion 12. A helical thread 30 integrates with the outside of the portion. 22 nozzle and is adapted to be coupled to a complementary thread on the gas and fuel oxygen torch, subsequently mixed (see Figure 5). A hexagonal rib 32 also integrates with the exterior of the nozzle portion 12 to provide a grip surface for a wrench, which can be used to attach the nozzle to the torch or remove the nozzle from the torch. A casing 34 is an integral part of the body 10, which surrounds and extends in an axial direction away from the discharge end 28 of the nozzle portion 12 to an open end 36. The casing 34 is preferably a circular cylinder or other cylindrical configurations that can also be used. The side wall of the envelope 34 defines a chamber 38, through which the gases discharged from the discharge orifices 22, 24 and 26 are mixed and grooved to produce a mixed gas stream, which is maintained over a distance longer than a pre-mix nozzle that does not have the wrap. According to this embodiment of the invention, the intake end 14 includes a central portion 40, which surrounds the axial bore 16, two annular steps 42, 44 surrounding the respective internal and external rings of the holes 18, 20, and tapered annular surfaces 46, which are adapted to settle on the head of the torch, having a tapered seat and circumferential gas discharge grooves (see Figure 5). Figure 2 shows a top plan view of the cutting nozzle, shown in Figure 1. As is evident, the hexagonal rib 3-2 of the nozzle portion 12 provides a grip surface for a spanner, for the purpose to facilitate the coupling of the cutting nozzle to a torch. The casing 34 surrounds the discharge end 28 of the nozzle portion 12. This discharge end 28 includes discharge orifices 22 for the cutting oxygen, 24 for the fuel gas and 26 for the preheating oxygen. The discharge orifice 22 for the cutting oxygen is preferably flared. This creates a swirling effect within chamber 38 to promote mixing of the fuel gas and oxygen. The casing 34 also protects the discharge end 28 from the recoil splashes of the molten metal from the cut. This improves the service life of the nozzle, because it substantially eliminates nozzle damage, which results from the return splashes of the metal that contact the nozzle and melt therein. Figure 3 is a longitudinal cross-sectional view of a second embodiment of the invention. The cutting nozzle of Figure 3 is very similar in structure to the cutting nozzle shown in Figure 1. The cutting nozzle 10 is also an integral body 10, which includes a nozzle portion 12 and an integral helical thread 30, a hexagonal rib 32 and an envelope 34, which surrounds and extends in an axial direction away from the discharge end 28 of the nozzle portion 12 to a open end 36 to form a discharge chamber 38. Unlike the embodiment shown in Figure 1, the nozzle portion 12 of this embodiment has a flat intake end 14. An axial bore 16 and holes 18, 20, which they respectively form an internal and an external ring, all extend from the flat intake end 14, which ends at the holes 22, 24 and 26 at the discharge end 28. The axial bore 16 has an intake region, which has a diameter slightly larger than the rest of the hole, to connect with a respective gas passage in the head of the torch, not shown. The flared portion of the orifice 22 is larger and the flare angle is smaller than that of the embodiment shown in Figure 1. While the flare is greater and the flare angle is less than those shown in Figure 1, it should be appreciated that the performance is the same and the flares shown in Figures 1 and 3 are interchangeable. The holes 18 and 20 have a respective inlet portion, defined by respective circumferential grooves, which form distribution channels for the preheating oxygen and the fuel gas, when the nozzle is installed in the torch head. This embodiment of the invention is adapted to be coupled to an oxygen gas torch and fuel torch, which has a head with a flat seat. The integral body cutoff is preferably constructed of a brass alloy, although other materials, such as copper, stainless steel and the like, can also be used. The envelope 34 is preferably at least 16.5 mm long. Larger lengths can be used, but shorter lengths are not recommended. The thickness of the side wall of the envelope 34 is preferably around 5.58 mm for a good resistance to heat fatigue. A thinner side wall can be used successfully, however, the side wall of the envelope 34 of the second embodiment is preferably around 3.53 mm. At least the outer surface of the side wall of the casing 34 is preferably plated with chromium or nickel, to inhibit the adhesion of the recoil splashes of the molten metal. Figure 5 shows the connection of the cutting nozzle, illustrated in Figure 1, to a torch of typical fuel gas and oxygen gas, after mixing. This oxygen and fuel gas torch includes a torch head 50, which has a helical thread 52 on the inside to engage the helical thread 30 of the nozzle portion 12 for coupling the cutting nozzle 10 to the head 50 of the torch. This head 50 of the torch is supported by a tubular handle 54. This tubular handle 54 is hollow. Extending through the tubular handle 54 are the supply tubes 56, 58 and 60 for supplying, respectively the cutting oxygen from an oxygen source, the fuel gas from the source of this fuel gas and the preheating oxygen from the source. source of oxygen. The supply tube 58 of the fuel gas and the supply tube 60 of the preheating oxygen are in fluid communication with the circumferential distribution slots 62 and 64, respectively. The circumferential distribution grooves 62 and 64 are defined on the tapered seat surface 66 on which the tapered annular surfaces 46 of the nozzle portion 12 settle. The procedure and operation of the coupling of the combustible oxygen torches, after mixing, are well understood by those skilled in the art and will not be described further here. The modalities described above, try only exemplary. Changes and modifications may be made in the specifically described embodiments, without departing from the scope of the invention, which attempts to be limited only by the scope of the appended claims

Claims (9)

1. CLAIMS 1. A cutting nozzle, for a torch of oxygen gas and fuel, mixed later, this nozzle comprises: an integral body, which has a first end for the connection with a torch of oxygen gas and fuel, this first end includes drill holes for cutting oxygen, fuel gas and preheating oxygen, respectively; and a second end, for discharging the cutting oxygen, the fuel gas and the preheating oxygen, this second end is surrounded by a casing, extending away from the second end, to promote a mixing action of the discharged gases the nozzle and produce a gas stream, which maintains its configuration over a longer distance than a pre-mix nozzle, which does not have this envelope.
2. 2. A cutting nozzle, as claimed in claim 1, wherein the holes at the first end include an axial bore for the cutting oxygen, a first plurality of boreholes for the fuel gas and a second plurality of boreholes for the preheating oxygen , the first and second plurality of boreholes respectively surround the axial bore for the cutting oxygen, all boreholes end in the discharge orifices at the second end.
3. 3. A nozzle-cutter, as claimed in claim 2, wherein the envelope comprises a circular cylinder, having an open end, and a chamber defined by a side wall of this circular cylinder.
4. 4. A cutting nozzle, as claimed in claim 3, in which the integral body comprises a helical thread, which is adapted to be coupled to a complementary thread in a torch head of the oxygen gas torch and fuel, subsequently mixed.
5. 5. A cutting nozzle, as claimed in claim 4, wherein the integral body includes parallel flat surfaces, which can be grasped by a wrench, to attach the nozzle to the oxygen gas torch and fuel, subsequently mixed, or removed the nozzle from the torch.
6. 6. A cutting nozzle, for an oxygen and fuel torch, subsequently mixed, this nozzle comprises: an integral body, having an intake end and a discharge end, this intake end is adapted to be received in a nozzle seat of the oxygen and fuel torch, mixed later; a plurality of passages, for directing, respectively, the cutting oxygen gas, preheating oxygen gas and fuel from the torch to a discharge end of the nozzle body; a helical thread, for the coupling to a complementary thread in the torch of gas of oxygen and fuel, mixed later, and surfaces of grip for a wrench, used to connect the nozzle to the torch, the helical thread and the gripping surface they are integrally formed with the exterior of the nozzle body; and a cylindrical envelope, which surrounds the discharge end, this envelope is an integral part of the nozzle body and extends in an axial direction, away from the discharge end of the nozzle body at an open end, to form a chamber, having a suitable axial extension to promote a mixing action of the gases discharged from the passages and produce a gas stream, which maintains its configuration over a longer distance than a subsequent mixing nozzle, which has no envelope.
7. 7. A cutting nozzle, as claimed in claim 6, in which the passages include an axial borehole, through which the cutting oxygen gas is discharged and spaced gas discharge bores, arranged in concentric rings, internal and external, around the axial bore, respectively, the bores in the inner ring are in fluid communication with a fuel gas conduit of the torch, when the nozzle is coupled with the torch and the bores in the outer ring are in fluid communication with a conduit of gas from the torch preheating oxygen, when the nozzle engages with the torch, the axial bore and the gas discharge boreholes end in the holes discharging the discharge end of the nozzle body.
8. 8. A cutting nozzle, as claimed in claim 7, in which the intake end is a flat end, which has all the holes in it, this intake end is adapted to be seated in a torch head, which has a seat flat.
9. 9. A cutting nozzle, as claimed in claim 7, wherein the intake end comprises a central portion, having the axial bore, two annular steps, having respective holes in the rings, internal and external, and tapered annular surfaces, adapted to be seated in a torch head, which has a tapered seat with the circumferential grooves.