US3078913A - Cutting torch - Google Patents

Description

C. C. ANTHES CUTTING TORCH 2 Sheets-Sheet 1 Feb. 26, 1963 Filed oct. 19, 1960 INVENTOR CLIFFORD C.ANTHES Yf f bavwfk z .u mms@ 1 m Mff?? Feb. 26, 1963 c. c. ANTI-IES 3,078,913

CUTTING TORCH Filed om. 19, 1960 2 sheets-sheet 2 JNVENToR. CLIFFORD C. ANTHES law/JJM@ ATTRNEK United States Patent G 3,078,913 CUTTING TORCH Clifford C. Antlles, Union, NJ., assignor to Union Carbide Corporation, a corporation of New York Filed Oct. 19, 1960, Ser. No. 63,585 1 Claim. (Cl. 15S-27.4)

This invention relates to cutting torches, and more particularly to oxyfuel blowpipes employed for severing ferrous metals and the like.

The use of fuel gases other than acetylene for hand and machine metal-cutting operations has been increasing steadily over the past few years. Indications are that this increase will continue due in large part, to the considerable cost advantage enjoyed by such gases as methane or n-atural gas. Such fuel gases, supplied from low pressure (1/2 p.s.i. or less) gas lines in particular, have become increasingly popular as a source of fuel lfor gas cutting operations.

This shift to low pressure fuel gases for gas cutting has necessitated the development of cutting torch apparatus particularly tailored for use with these fuels. For example, torches with greater preheat gas ilow capacity than could be supplied by standard Oxy-acetylene cutting torches are required. This is due to the fact that greater volumes of both fuel gas and preheat oxygen are required to provide the equivalent heat output or preheat llame effectiveness produced using acetylene as the fuel.

In oxygen cutting operations, the objective is to raise the temperature of the material to be cut to its ignition point in the shortest possible time to initiatethe cutting action and then to maintain the material in the area of the cut at this ignition temperature as the cutting action progresses across the material.

To accomplish this objective in the most efficient manner, there is an optimum combination of `cutting torch injector and throat that will provide the best operation for a given preheat gas flow and pressure range and a given type of fuel gas; that is, the injector of a low pressure injector-type torch is tailored to supply a lim-ited range of preheat flows with a given type of fuel gas. There is one optimum throat diameter in combination with this injector which will provide the optimum performance.

Should the preheat flow range required for a particular cutting operation be either above or below that for which the throat was designed, the result will be a sacrifce in performance by way of longer initial preheat time, longer cutting time to complete the cut, and a poor quality cut. This is due to the fact that the primary function of the throat section of an injector-type torch is to provide just the right build-up of gas velocity directly downstream of the injector to produce the most efficient aspiration of fuel gas into the mixed gas ow (combined oxygen and fuel gas preheat gas).

lf the diameter of the throat section is less than the optimum, the effect is to destroy the injector aspirating efficiency due to a choking oi of the injector through a buildup of gas pressure just ahead of the throat section. If the diameter of the throat is greater than the optimum, there will be an insufficient build-up of gas velocity for maximum eiciency of aspiration. Similar results will be had with the use of a fuel gas other than that for which the injector and throat were designed.

In standard cutting torch apparatus, while the injector unit is easily replaced, the throat is an integral part of the torch assembly and not an easily replaced item. That is, it is necessary to disasscmble the torch head from the cutting oxygen tube and mixed gas tube, install a new mixed gas tube containing the desired size throat, and then reassemble the head in order to replace the throat section of the torch. As a result, a given standard cutting torch readily provides optimum operation only for one "ice type of fuel gas and then only for a limited range of preheat gas ows. In order to go from one fuel gas to another orto enlarge the preheat ow range of ya given fuel gas in order to cut material either thinner or thicker than that for which the torch was originally intended, a different throat section has to be installed in the torch in the time consuming manner outlined above to obtain optimum operation.

Because of this lack of ready adaptability to suit varying cutting requirements on the part of standard cutting torches, it is necessary for the user to either stock a multiplicity of cutting torches, the number depending upon the range of cutting applications prevailing in his particular shop, or sutfer a sacrifie in eiciency of operation in terms of longer cutting times and poorer cut quality. Either result is undesirable from an economics point of view. Stocking a multiplicity of torches involves a large initial capital outlay as Well as large continuing maintenance costs. If eiciency of operation is sacrificed, poor quality cuts may well result in an increase in subsequent machining required as well as higher labor costs due to the increase in labor time required to complete a given cutting operation.

The cutting torch of this invent-ion supplies the desired degree of versatility in performance by providing a torch which is readily converted to produce the optimum operating performance over a Wide range of preheat gas ows and types of fuel gas. This has been accomplished according to the invention by making the throat section of the torch an integral part of an easily replaceable injector-throat assembly. Thus, it is possible to adapt the cutting torch of the invention to provide the opimum operating conditions required for a given application merely by inserting an injector-throat assembly specifically ,tai-

lored for the particular fuel gas and preheat llow needed.l

Therefore, instead of stocking a multiplicity of cutting torches, it is merely necessary for the user, having a variety of cutting operations to perform, to stock a sufficient number of injector-throat assemblies to cover his range of operations.

An additional advantage gained from having-the throat section of the torch an integral part of the injector-throat assembly is that the end clearance between the forward end of the injector unit and the mouth of the throat section is maintained at a fixed value. This end clearance is a critical factor in maintaining preheat flame stability;

that is, resistance to backfire and flashback; and there is an optimum clearance which provides the greatest degree of stability.

In the drawings: L

FIG. 1 is a plan of a blowpipe embodying the invention;

FIGS. 2 and 3 are front and rear portions of a longitudinal cross section through the blowpipe shown in FiG. l;

FIG. 4 is a cross section through the valve block;

FIG. 5 is an enlarged cross section of the central portion of the blowpipe; and

FIG. 6 is a cross section taken along line 6-6 of FIG. 5.

The cutting blowpipe shown in the drawings comprises a nozzle head H connected by a cutting oxygen tube C and a preheat gas conduit M to a valve block B to which oxygen is supplied at inlet O and fuel gas at inlet A.

Oxygen enters the valve block B from the inlet O through a passage 10V into chamber 1I, from which its passage to the cutting oxygen tube C and the preheat gas conduit M is regulated by valves 12 and 13 respectively.

Thus the combustion-supporting oxygen passes from the chamber 1li to a duct 14 in the valve block, the far end of which provides a valve seat and is closed by the valve 13. This valve is carried by a threaded Valve stem 15 operated by a handle 16 to move against the valve seat associated. with the duct-14 or to be retracted from this seat into a valvevchamber l-l whichfis formed in thevalve block B.

The valve block B has a through bore 19 aligned with preheat gas conduit M, and a cross passage 18? connects the valve chamber 17 with the back end of the bore 1.9. Accordingly, by turning the handle 16,` combuston-sup porting oxygen may be' permitted to` iiow into the valve chamber 17` and thence through the cross passage 18 to the back end ot the bore.19l

The: flow of fuel gas from inlet A to the forward end of bore 19 in the valve block B, through passages not shown, isregulated by valve 50, similar in construction tovalve 1'3.

According to the present invention, the preheat gasconduit M is a continuous tube from the valve block B, to which it is gas-tightly connected as by silver soldering at' 21, to the nozzle head H to which it is gas-tightly connected as by silver soldering at 22; The injector throat assembly inserted through the bore 19 in the. valve block B1 and; preheat gas conduit;v M` comprises` a throat section 20;. annjector 23,'` a'preheat oxygen tube 24, andl an injector sealing member 25,` allrigidly connected together.

'Ihethroat'sectionf 20 has a central' passage Z8 with a'. front portion: 29 expanding forwardly in conical formI toward: theV headf H, and a backf portion: 30 expanding rearwardly in conical form and terminating` in a cylindricall entrance 32 havingfan annular rimr 33.

The. injector 23 has aconical'nose 34' entering the` conical` rear passage portion 30 of the throat* section with a ixed optimum clearance, and al cylindrical? portion 35 ex tendingrearwardlyv and having radiali tins 346 fitting inside the cylindrical' entrance 32 of the throat section: The injector'also has an annular groove 37 intersectingy the fins' 36.l 'I"l1e:sectionsl 39of'the tins 36 to the rear of annular groove 37 arerlateallyextended to contact the cylindricall wall of the. preheaty gas tube M. The forward. faces' of tliese fin` extensions' adjacent the groove` 37' are fused to the rear annular rim 33- of the throat section as by silver solder 38. The arcuate passages 51 between the tins 36 provide communication for fuel gas ow from the annulrpassage 54, between the oxygen tube 24 and the preheat gas conduit M, to the. tixed optimum clearance between the conical nose 34 of the injector and the conical rear passage portion 30 of the throat section.

The injector 231 also has. acentral passage 40' aligned' with the throat passage and terminating in a rear socket 42; The: front end of the oxygen tube 24 is tted into tliisIsocket and silver soldered intothe sealing member 25l in registry'with axialpassage53 inthe sealing member 25. 01 ring 52 is an annular groove in the periphery ofy sealing member 25 seals off the oxygen inlet into the rear of bore 19 from the fuel gas inlet in the forward end of bore 19.

Thus, preheat oxygen entering the rear of'bore 1-9v passes successively through axial passagel 53 in scaling member 25, oxygen tube 24, central passage 40 in the injector 23 to the central passage 28 in the throat section 20, Fuel 4. gas entering the forward end of bore 19 iiows through annular passage 54 to arcuate passages 51 and thence to the clearance between conical nose 34 and conical rear passage portion 30 where it is aspirated into the central passage 28 in the throat section 20 to become mixed with the preheat oxygen.

Thisinjector throatassembly ofthroat section 20, injector 23, tube 24 and, sealing member 25 is inserted through the bore 19' with the front end of the throat section 20 abutting the inside ofthe nozzle head H. The nut 45 is tightened to compress spring 46 to hold the assembly iny position under spring pressure and still allow for heat expansion of the parts;

It will be seen that by having the throat section 20, injector 23, preheat oxygen tube 24 and sealing member 25- all rigidly connected together not only provides for their readyY removability from the cutting torch as an integral assembly but also ensures maintaining a tixed optimum clearance between the conical nose 34 on the injector 23 and the conical rear passage portion 30 of the throat section 20 necessary to maintain preheatv flame stability.

What is claimed is:

In a cutting blowpipe having a valve block and a nozzle head, a preheat tube connecting said valve block to said nozzle head, and1 a removable injector-throat as sernbly unit ins'erted through said valve block into said preheat gas tube; said unit comprising a throat section separate from saidpreheat gas tube and of a diameter to slide inside' thereofv forwardly toward' said nozzle head;` said throat section having an axial passage expanding rearwardly in conical form and terminatingin a cylindrical entrance having an annular rim; an injector having a conicalE nose' entering saidA conical form` with a' clearance and'y a cylindrical" portion extending rearwardly therefrom inside of's'aid cylindrical entrance, and a rear portion of larger diameter iitting inside said preheat tube,` said injector also having an axial passage aligned with said throat passage, saidY injector also having longitudinally extending fuel gas passages outside of and surrounding said axialE passage, said rear portion of said injector having a forward face outside of said surrounding passages and rigidly and permanently secured to said annular rim` of said throat section, whereby removal of said injector out through' said valve block carries said throat section therewith.

References Cited in the file of this patent UNITED STATES PATENTS 2,198,341 Iacobsson- Apr. 23, 1940` 2,198,342A Jacobsson etal. Apr. 23, 1940 2,267,104 Iacobsson et al. Dec. 23, 1941 FOREIGN PATENTS 492,560 Germany Feb. 26, 1930 594,992 Great Britain July 29, 1953

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