US3010468A - Preheat flame control - Google Patents

Description

Nov. 28, 1961 B. H. ACOMB .PREHEAT FLAME CONTROL Filed Sept. 18, 1958 FUEL GAS PRE HEAT OX Y6 EN CUTTING OXYGEN INVENTOR BYRGN H ACOMB 5614/ TURNEY United States Patent 9 3,010,468 PREHEAT FLAME CONTROL Byron H. Acomb, Watchung, N.J., assignor to Union Carbide Corporation, a corporation of New York Filed Sept. 18, 1958, Ser. No. 761,805 7 Claims. (Cl. 137114) This invention relates to an improved preheat flame control apparatus for an oxygen cutting blowpipe, and more particularly concerns an improved control for automatically reducing the heating ability of a preheat flame when oxygen cutting gas is passed through the blowpipe.

In cutting metal with a stream of oxidizing gas, oxygen and a fuel gas such as acetylene are normally supplied to blowpipe to give a satisfactory preheat flame. The preheat flame heats the metal to its kindling temperature after which the cut is started by directing a stream of cutting oxygen at the heated spot. During the cutting operation, the preheating flame remains burning to make uptor the heat that is lost due to radiation, conduction, and the like. For rapid starts it is desirable to have a large preheating flame. However, once the flow of cutting gas has started, the quantity of preheating gases should be reduced in order to avoid meltover of the kerr top edges.

Heretofore, the usual means for switching from a high preheat flame to a low preheat flame involved a lever or switch which had to be manuaily'actuated by the operator. Not only is this inconvenient for the operator to operate, but in multiple blowpipe setups where each preheat flame has to be individually throttled, by the time the last preheat flame is adjusted, the work has progressed a considerable distance.

it is therefore an important object of the present invention to provide an improved preheat flame control for a blowpipe to produce a high preheat flame when the flow of cutting oxygen is shut off and a low preheat flame upon resumption of cutting oxygen flow.

Another object of the present invention is to provide for a blowpipe an improved oxygen control mechanism capable of producing a high preheat flame when the flow of cutting oxygen is shut ofl and a low preheat flame upon resumption of cutting oxygen flow, there being a substantimly constant pressure drop in the oxygen cutting hose during the flow of cutting oxygen through the oxygen control mechanism regardless of the quantity ofcutting oxygen flowing therethrough.

Yet another object of the present invention is to provide novel means in a preheat flame control apparatus for an oxygen cutting blowpipe which provides a substantially constant pressure drop of cutting oxygen in mechanism embodying the principles of the invention, and

FIGURE 2 is an enlarged sectional elevational view of the control mechanism of the invention.

In FIGURE 1 is shown a diagrammatic flow sheet of an oxygen cutting blowpipe installation embodying the features of the invention and comprising a gas control device 19 which admits cutting oxygen from a source of high pressure cutting oxygen 12 and preheat oxygen from a source of high pressure preheat oxygen 14, and controls the flow of preheat oxygen to a cutting torch or blowpipe "ice 16. Regulators 13a, 13b, and 130 control the flow of cutting oxygen, preheat oxygen, and fuel gas, respectively. The blowpipe 16 is preferably a 3-hose blowpipe of the fuel injection type, although other blowpipes suchas the mixer type are also susceptible of use in connection with the invention.

The present invention resides in the employment of a novel control mechanism for automatically adjusting the flow of preheat oxygen, making it possible to change from a high flow preheat flame when cutting oxygen is not consumed, to a low preheat flame when the cutting oxygen is being consumed.

Referring to FIGURE 2, the gas control device 16 of the invention comprises a hollow casing 20 made of any suitable material such as cast brass, consisting of a generally cup-shaped body 22 and a concavely-shaped cap 24 in threaded engagement therewith. The casing 20 is suitably fashioned to provide a cutting oxygen inlet 23 opening through a passage 3G in the cap 24 into a cutting oxygen dome or chamber 32. The cutting oxygen finds outlet from dome 32 in a manner to be explained hereinafter through a passage 34 to a cutting oxygen outlet 36.

Admission of preheat oxygen into the body 22 occurs through a preheat oxygen inlet 38 connected with a preheat port or passage lit-40a which traverses a vertical bore 42. The preheat passage 40a terminates in an outlet 44, through which delivery of the preheat oxygen is effected.

The dome 32 is divided into an upper section 46 and a lower section 48 by means of an annular, flexible diaphragm 50, preferably made of rubber or a flexible sheet metal, which diaphragm is clampingly held at its outer periphery between a shoulder 52 in cap 24 and a flange 54 in body 22. A seal ring 58 may be employed to seal the joint. A slip ring 56 may be employed to prevent damage to and twisting of the diaphragm when threading on the cap.

The center of the diaphragm 59 is closed by a valve 69 and a valve seat 62 arrangement. The valve seat 62 is provided with a threaded cylindrical wall 64. The 'inner margin of diaphragm 5G is clamped between an annulus or diaphragm plate 66 and the valve seat 62 as by means of a clamping nut 68 in threaded engagement with the cylindrical wall 64. The valve 60 has a stem 70 which passes downwardly through a central opening in the valve seat 62, and extends across the lower dome section 48 into the vertical bore 42. The stem 76 is provided with a conical tip or end 72 adapted to seat against a shoulder 74 in the bore 42 and close the traversing preheat oxygen passageway 49-4012. Adjustment of the conical tip 72 to fully or partially, open or close, the passageway 4040a is accomplished by means of a preheat adjusting or limiting member comprising a handle 76 having an elongated shank or limit 78 threaded into the body 22 and adjustably extending into the bore 42 where it is adapted to engage the conical tip 72. Packing 79 may be employed to hold the limit 78 in adjusted position. A suitable seal, such as an O-ring 81 carried by stem 70, seals the cutting oxygen in the dome 32 from the preheat oxygen in the passage 404-4la.

The valve 60 is held in closed position by a light spring disposed loosely about the stem 70 and exerting spring pressure against a spring retainer 82 on said stem and the underside of the valve seat 62. A second spring 84 of larger diameter than spring 81 fitting loosely the cylindrical wall '64 of valve seat 62, and a recess 86 in the body 22 will under all conditions permit sutficient opening of the Valve 66 which in the present instance is accomplished by depression of the valve seat 62 against the forces of the springs 84 and 80. The springs 84- and 80 may have any desired spring tensions, which tensions determine approximately the differential in pressure on opposite sides of the diaphragm necessary to open the valve 60'. Opening of the valve 60 enables cutting oxygen to flow through relatively large openings 88 in valve seat 62. A pin open ing or bleeder hole 90 in the valve 6% permits pressure equalization on both sides of the diaphragm 50 when the valve is closed.

In operation the blowpipe is prepared for service by first shutting all valves at the blowpipe and then turning the handle 76 of the limit 78 fully in, thereby limiting the vertical movement of the conical tip 72 with respect to the shoulder 74 and fully opening the perheat port 40-4ila to the flow of preheat oxygen issuing from preheat oxygen source 14. At the same time, the stem '70 and the valve 69 are lifted a corresponding distance, along with the valve seat 62 and the diaphragm Sit, by reason of the tension in the spring 84. After setting the desired pressures atthe three regulators 13a, 13b, and

' 130, the blowpipe is is lighted and the resulting hot,

preheat flame adjusted by means of a preheat valve 92 and a fuel valve 94- on the blowpipe 16. Thereafter, the cutting oxygen valve 96 at the blowpipe is opend, relieving the pressure in the lower section 48 of the dome 32 and causing a pressure differential to exist on opposite sides of the diaphragm 5i Thereupon the force of the cutting oxygen pressure acting upon the upper surface of the diaphragm depresses the diaphragm, allowing cutting oxygen to flow through the valve seat openings 88 and through delivery passages 34 and 36 to the blowpipe 16, and establishing a substantially constant pressure differential in the dome 32 corresponding approximately to the force necessary to overcome the tension in the springs 84 and 80.

Because of the relatively large size of the valve seat opening 88 and the relatively small separation distance between the valve 60 and valve seat 62 required to establish the requisite pressure drop, the functioning of the diaphragm valve 6% is virtually independent of the amount of cutting oxygen flow therethrough. Consequently, a single cutting oxygen valve 60 having a relatively constant pressure drop can be used to supply a multiple cutting blowpipe setup without further changes in the upstream pressure setting other than pressure drops caused by the hose each time the number of blowpipes is changed.

The preheat flame which during this proceeding has remained unchanged because of the raised position of the conical tip 72 is now throttled to a soft flame by backing out limit 78, which action lowers the valve 60, valve seat 62, and diaphragm 50, as a unit, but does not afiect the flow of cutting oxygen past the valve 60 since the pressure differential across the diaphragm remains unchanged. Following this, the flow of cutting oxygen is shut off at the blowpipe whereupon the Valve seat 62 rises to close the cutting oxygen valve 60 and the pressure in the lower dome section 48 becomes equalized with the pressure in the upper section 46 by reason of the bleeder hole 90. Equalization of the pressure causes the diaphragm 50 to rise to a stable or equilibrium position,

thereby raising the conical tip 72 and restoring a hot preheat flame condition.

Upon resumption of the flow of cutting oxygen, the relief of the pressure on the underside of the diaphragm causes downward movement of the diaphragm and the conical end strikes the limit 78-, thereby automatically adjusting the flow of preheat oxygen to the previously adjusted rate.

An obvious advantage of the invention is that once the preheat flame control mechanism has been initially pressure diflierential across the diaphragm 50 is virtually independent of the quantity of cutting oxygen flow and remains substantially constant regardless of the number of blowpipes serviced by the diaphragm valve 60.

From the above description it will therefore be seen that the present invention provides improved means for rapid and efiicient preheating when cutting with an oxygen fuel gas cutting torch, which automatically throttles the preheat oxygen from a high flow for initial preheating to a normal working flow when the torch cutting oxygen valve is opened. The reduction in the heating ability of the preheat flame during oxygen cutting prevents kerf meltover and assures the production of clean, sharpedged cuts.

The preheat flame control apparatus of the invention is admirably suited for use with three-hose cutting blowpipes of the injector type supplied from separate preheat oxygen, cutting oxygen, and fuel regulators, since the flow of preheat oxygen in the blowpipe automatically establishes the ratio of fuel gas to preheat oxygen in the preheat flame gas mixture. It should be noted, however, the invention is also susceptible of use in connection with blowpipes of the mixer and other types. In addition, the invention can be installed and operated in all positions and can be operated either at the blowpipe or back at the regulator station. Moreover, the shut-oft of cutting oxygen can be upstream or downstream of the preheat flame control apparatus.

It will be understood that modifications and variations may be effected without departing from the spirit and scope of the invention.

What is claimed is:

l. A preheat oxygen control comprising a casing, a cutting oxygen chamber in said casing, a flexible diaphragm mounted across said cutting oxygen chamber and having an aperture therein, inlet and outlet means on the upper and lower sides of said diaphragm respectively for delivering and discharging cutting oxygen, a valve construction mounted in the aperture of said daphragrn and including .a valve cooperating with a valve seat bounding the aperture of said diaphragm on the upper side of said apertured diaphragm, said valve having a member extending through said valve seat for reciprocal movement with said valve and having means for equalizing the pressures across said valve and means for constanttly urging said valve to said valve seat, means in said casing for resiliently supporting said diaphragm and valve construction against free downward movement, a bore in said casing for receiving said valve member, a preheat oxygen passage traversing said bore and sealed from said cutting oxygen chamber, means provided on said valve member cooperating with said preheat oxygen passage to throttle the flow of preheat oxygen therethrough and adjustable means for stopping the downward movement of said valve member means whereby preheat oxygen flow is controlled by cutting oxygen flow with a substantially constant pressure drop thereacross.

2. A preheat flame control device comprising a casing having a cutting oxygen chamber therein, an apertured diaphragm mounted across said cutting oxygen chamber, an inlet on one side of said diaphragm and an outlet from said cutting oxygen chamber on the other side of said diaphragm, a valve construction including a valve having a bleeder hole and cooperating with a valve seat bounding the aperture of said diaphragm on said one side of said diaphragm, said valve having a stem extending through said aperture and valve seat, a spring acting between said valve stem and diaphragm, constantly urging said valve to said valve seat, a conical tip provided on said valve stem, a spring means in said casing for resiliently supporting said diaphragm against free downward movement, a bore in said casing for receiving said valve stem, a preheat oxygen passage traversing said bore and cooperating with said conical tip on said valve stem to throttle the flow of preheat oxygen through said preheat oxygen passage and means positioned in said bore for providing an adjustable stop for said conical tip on said valve stem whereby preheat oxygen flow is controlled by cutting oxygen fiow with a substantially constant pres sure drop across said diaphragm.

3. Apparatus according to claim 2, and a bleeder hole in said valve for equalizing the pressure across said diaphragm when the delivery of cutting oxygen is stopped, whereby said spring means moves sm'd valve construction and automatically restores fill flow of preheat oxygen in said passage.

4. Apparatus according to claim 2, said preheat oxygen control apparatus being for a single blowpipe.

5. Apparatus according to claim 2, said preheat oxygen control apparatus being for a multiple blowpipe setup.

6. A flow control device comprising a casing having an inlet and a first cutting oxygen chamber for receiving cutting oxygen from said inlet and a second cutting oxygen chamber having a delivery outlet, cutting oxygen valve means moveably mounted between said chambers, means associated with said valve means for equalizing the pressures across said valve means when there is no demand for oxygen, a preheat oxygen passage traversing said casing and sealed from said first and second chambers, a preheat oxygen control valve associated with said cutting oxygen valve means to be moveable therewith and cooperating with said preheat oxygen passage to obstruct the flow of preheat oxygen therethrough, and means for opening said cutting oxygen valve means and for controlling the movements of said preheat oxygen control valve when said valve means moves in response to the flow of cutting oxygen from said second chamber.

7. A gas flow control device comprising a casing having an inlet and a first cutting oxygen chamber for receiving cutting oxygen from said inlet and a second cutting oxygen chamber having a delivery outlet for supplying cutting oxygen to the point of use; a flexible diaphragm mounted between said chambers and having an aperture therein; valve means mounted in said apertured diaphragm to be moveable therewith and including means for equalizing the pressures across said valve means when there is no demand for cutting oxygen; a preheat oxygen passage traversing said casing and sealed from said first and second chambers; a preheat oxygen control valve associated with said cutting oxygen valve means to move therewith and cooperating with said preheat oxygen passage to obstruct the flow of preheat oxygen therethrough; means for limiting the movement of said preheat oxygen control valve and opening said valve means when said diaphragm, valve means and preheat oxygen control valve are motivated by the delivery of cutting oxygen from said second cutting oxygen chamber.

Reierences Cited in the file of this patent UNITED STATES PATENTS 363,643 Jacobs May 24, 1887 498,897 Von Ey June 6, 1893 1,766,648 Keller June 24, 1930 2,020,773 Ernst Nov. 12, 1935

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