US2258456A - Blowpipe nozzle for thermochemically forming a groove in a ferrous metal body - Google Patents

Description

BLOWPIPE NOZZLE FOR THERMQCHEMICALLY FORMING A GROOVE IN A FERROUS'METAL BODY Filed Feb. 2, 1939 Oct. 7, 1941, E p JONES 2,258,456

2/ ufillllf illll A m 27 INVENTOR EVERETT P. JONES ATTORNEY Patented Oct. 7, 1 941 BLOWPIPE NOZZLE FOR THERMOCHEMI- CALLY FORMING A GROOVE IN A FER- ROUS METAL BODY Everett P. Jones, Elizabeth, N. J., assignor to Oxweld Acetylene Company, a corporation of West Virginia Application February 2, 1939, Serial hlo. 254,205

17 Claims.

This invention relates to a blowpipe nozzle for thermo-cheniically forming a groove in. a ferrous metal body.

, For forming shallow channels and generally removing surface metal from the surface of a ferrous metal body, it has been the practice to employ substantially straight nozzles for producing and applying a relatively low velocity oxidizing gas stream at an acute angle to the surface from which metal is to be removed as shown and described in United States Letters Patent No. 1,957,351, granted May 1, 1934, to Samuel R. 'Oldham. It is not possible to produce a relatively deep groove in a single passv of the nozzle when employing such nozzles and methods. It has also been proposed to produce a relatively deep groove by applying an oxidizing gas stream flowing at relatively low velocity progressively in the direction of the groove tobe out while maintaining the axis of the stream adjacent its point of issue from the nozzle substantially parallel to the axis of the groove and below the surface of the plate and near the bottom of the groove. To produce such a deep groove it has been proposed to employ a nozzle having an oxidizing gas passage which produces a relatively low velocity gas stream an'd'which is provided near. its outlet end with a shortterminal portion at an abrupt angle to the straight body portion of the nozzle. Such a nozzle is very diflicult to manufacture and has not proved entirely satisfactory tively enlarged oxygen passage therethrough provided with a. bend adjacent the outlet end of the nozzle and in which the passage has means near the discharge end for insuring a rapid expansion of th gas as it is discharged from the passage; to provide a nozzle for producing an oxidizing gas stream that is discharged therefrom with unequally distributed velocity of flow; and to provide such nozzle formed of substantially a single piece of metal.

These and other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawing.

Fig. 1 is a longitudinal sectional view of a nozzle embodying the principles of the present invention; I l

Fig. 2 is an end view of the inlet end of the nozzle shown in Fig. 1;'

Fig. 3 is an end view of the outlet end of the V nozzle shown in Fig. 1; and

I nozzle ill, the nut I2 secures thenozzle to a blowin operation. It is necessary that such a nozzle be constructed of separate portions joined toerties is produced by a nozzle having a smooth bend by providing th oxygen passage through "the nozzle with a restriction or metering orifice adjacent to or at the bend between the inlet 1 portion and the outlet portion of the passage.

The principal object of. the present invention is to provide an improved nozzle. particularly 7 suitable for forming deep grooves in a ferrous pipe head or adapter (not shown) so that the tapered seating surfaces l3 and M will engage with and form agas-tight seal with corresponding seating surfaces in the blowpipe head that supplies a central stream of oxidizing gas, which may be pure oxygen or a mixture of oxygen and air, and a stream of combustible gas, such as a mixture of oxygen and acetylene, to the nozzle.

The nozzle is provided with an axial oxidizing gas passage having an inlet portion IS. The inlet portion l5 of the nozzle is relatively large in diameter and extends from .the inlet end of the nozzle until the bend 16 near the outlet end of the nozzle is reached. The bore l5 may be of uniform diameter or be slightly tapering with the large end at the inlet. The axially straight body portion of the nozzle l1 tapers externally toward the outlet portion l8 which has a smaller diameter than the portion I11 and is disposed at an obtuse angle thereto. The bend 16 between portions l1 and I8 is not abrupt, but is relatively gradual and may therefore be produced by bending a straight nozzle.

vention are; to provide a nozzle having a .rela- The outlet portion l8 of the nozzle is provided with a relatively short cylindrical outlet channel l9 having a substantially fiat inner face 20 formed by a partition 2| provided between the inlet portion l5 and the outlet IQ of the passage. A metering passage 22 is drilled through the partition 2! providing communication between the inlet l5 and the outlet Hi. In the form of nozzle shown at Fig. 1, the partition 2| is partly to the left of and partly in the bend l6, the transverse plane of the line AA representing the forward end'of the curve.

s It is desirable that at least a portion of the metering passage 22 be slightly curved in order to increase the turbulence of the oxygen stream. In the form of nozzle shown in Fig. 1, a sufllcient degree of turbulence is provided by the curved entrance portion of the passage 22'. It has also been found desirabl to arrange the outlet portion of' the metering passage 22 slightly inclined downwardly to the axis of the bore If! so that the core of the oxygen stream which issues from the nozzle at .a higher velocity than the surrounding portions of the stream will be directed downwardly toward the bottom of the groove being cut. In this manner the bottom of the oxygen stream is provided with a somewhat higher velocity than the top which is advantageous. Itis believed that the improved results are due to a.

better scouring action in forcing the molten slag products of reaction up and out of th groove.

It is also believed that improved results may be partly due to a lateral spreading of the oxygen stream caused by greater impingement of the oxygen against the lower side of the bore l9 than if the axes were made to coincide. The angle between the axes of the bore 19 and the outlet portion of the orifice 22 is indicated at B and will vary according to the conditions and results desired. The angle B should normally be less than 7 degrees.

The partition 2| maybe integral with the nozzle or may b an insert, as shown in Fig. 1, and secured therein in any suitable manner as by a press fit. The insert 2| is preferably made of a slightly harder metal than the body ll of the nozzle so that when the bend I6 is formed, the curvature of the passage 22 will be less than that of the nozzle and the outlet end portion of the orifice 22 will become inclined downwardly. The bending operation serves to firmly secure the insert 2| in the nozzle bore. Any change in crosssectional area that occurs in the bent portion of the inlet passage I5 has no effect because the bore i5 is originally made large enough in diameter. If desired, the end I8 of the nozzle may be made narrower by machining ofi portions of each side as shown at 23 of Fig. 3.

To provide heating flames for initially heating th metal to an ignition temperature and for aiding the grooving process, orifices for discharging combustible gas from the nd of the nozzle are provided. Such orifices are preferably grouped near the upper and lower sides of the oxygen outlet orifice IS, a greater number being preferably disposed near the lower. side. As shown in Fig. 3, three orifices 24 are above and four orifices 25 are below the outlet IS; The orifices 24 and 25 are drilled substantially parallel to the axis of the portion l6 until the beginning of the bend I6 is reached where they make communication with a corresponding number of slightly larger passages 26 and 21 that extend lengthwise through the nozzle to-a portion at the inlet end thereof between the seating surfaces l3 and 14. The passages 24, 25, 26, and

21, are preferably drilled prior to forming the bend l6, the passages 26 and 21 being of suflicient diameter so that distortion caused by bending will not restrict the cross-sectional area to an area less than that of the orifices 24 and 25. The passages through the nozzle may also, if necessary or desirable, be supported by suitable inserts during the bending operation, which inserts may be removed or withdrawn after such operation. In order to produce a deep groove with the abov described nozzle, the nozzle i0 is arranged with respect to the surface of the body so that the axis of the portion I8 is substantially parallel to the surface and the lower side of the portion I8 is near the bottom of the cut or groove that is being produced. The combustible gas issuing from the passages 24 and 25 produce high temperature flames which heat the metal directly ahead of the nozzle to the ignition temperature. The oxidizing gas is then supplied to the nozzle and issues from the orifice ill in a direction substantially parallel to the bottom of the groove to be made and towards the portions of metal to be removed. The oxidizing gas contacting with the heated metal causes the same to ignite and burn, producing a molten slag that is forced by the oxidizing gas upwardly to the surface of the metallic body. Such deflection of the oxidizing gas and slag is caused by the metal just underneath the metal that is being consumed, the unreacted metal acting as a baffle to cause the slag to be swept out of the cut and over the surface of the metal body. As the slag flows forwardly over successive portions of the metal to be removed it supplies heat thereto which therefore causes reaction to proceed with greater vigor so that the nozzle can be advanced to form the groove at a relatively greater rate. When start ing a groove on a flat surface instead of from the end of a surface, the nozzle is initially tilted upwardly toward the vertical so that the preheating flames may be better concentrated on the portion of the surface to be heated to the ignition temperature. When the oxygen is turned on and the grooving reaction started, the nozzle is tilted down until the axis of the outlet I9 is more nearly parallel to-the bottom of the groove. In order that the side walls of the groove being produced may be separated a sufficient distance to permit the nozzle to pass therebetween, it has been found essential that the oxidizing gas stream produced by the nozzle shall expand laterally a suflicient amount to consume a greater width of metal than the width of the nozzle. A nozzle having a plain cylindrical oxygen bore such as disclosed in the aforesaid patent to Oldham produces a cylindrical stream that will not cut a laterally wide enough groove. According to the present invention, it has been found that the desired degree of lateral expansion of the oxidizing gas stream can be obtained by locating the metering orifice 22 relatively close to the outlet end of thenozzle and particularly by arranging the orifice as previously described. The diameter and length of the metering orifice 22, the

diameter of the outlet l9, and the depth of the outlet I9 are proportioned relatively to each other so that the desired character of stream is obtained. For example, it has been found orifice 22 is between about 2 and 3 for satisfactory results.

Fig. 4 illustrates a slightly different form of nozzle in which the partition l2l is located on the outlet side of the bend H6, and in which the metering orifice passage I22 is not bent. This relative location of the orifice I22 has an-advantage for certain purposes becausethe portipns I of the oxygen passage, namely, the orifice I22 and the outlet H9, which provide .the desired characteristics in the oxygen stream are not distorted by the bending operation in the process of manufacture. The formof nozzle shown in Fig. 4 has been found suitable particularly for very small sizes for making small grooves.

' The effect of the oxygen passage on the character of the stream produced may be explained as follows:

It appears that the oxygen passes through the metering orifice 22 with a relatively high velocity substantially equal to the acoustic velocity. As the oxygen passes from the metering passage 22 to the outlet passage IE! it expands very suddenly, which expansion involves a phenomenon termed compression shock that causes a sudden reduction of velocity and considerable turbulence. The length of the outlet end I9 is sufiicient to control this turbulence without eliminating entirely the lateral expanding tendency of the stream. Therefore, the stream acts upon the side walls of the groove adesired amount to provide the desired clearance for the nozzle.

In the nozzles described herein, the bend is on the upstream side of the discharge end of the metering passage and may be said to be in the effective region of the metering passage because the bend is thus positioned to cause the effect of the change of direction of flow of the stream to cooperate with the effects produced by the metering passage discharging substant ally longitudinally into the enlargedoutlet portion to provide the desired characterof .fiame machining stream, however, it is also contemplated that for certain effects it may be desirable to have the partition 2| and orifice 22 entirely within the bend I6 al- I though the curve of the orifice 22 may have a greater radius than the bend I6 in order that the core of the oxygen stream produced may be downwardly inclined from the.axis of the bore I9.

The embodiments of the invention herein illustrated and described are presented to indicate how the principles of the invention may be applied. Certain novel features may be used with lindrical outlet portion extending a relatively short distance back from the outletend of the nozzle, a restricted metering passage in said oxygen passage discharging into said outlet portion at least a portion of said metering passage being slightly bent, and an inlet portion for conducting oxygen to said metering passage.

2. A blowpipe nozzle for fiame machining having. an oxidizing gas passage extending there- .through terminating in a discharge orifice, said discharge orifice extending backwardly from the forward end'of the nozzle a relatively short distancc a relatively narrow metering orifice at the inlet end of said discharge orifice, said passage also having a relatively long inlet portion conducting gas to said metering orifice, and said nozzle being provided with an obtuse angle bend in the effective region of said metering orifice.

3. A blowpipe nozzle for flame machining having an oxidizing gas passage therethrough terminating in a discharge portion, said discharge portion extending backwardly from the forward end of the nozzle a relatively short distance, a relatively narrow metering passage at the inlet end of said discharge portion, said nozzle also having inlet means for conducting gas to said metering passage and being provided with an obtuse angle bend in the effective'region of said metering passage, said metering passage having a length greater than its diameter and at least a portion thereof being longitudinally curved.

4. A blowpipe nozzle for flame machining hav-' ing an oxidizing gas passage extending therethrough terminating in a discharge portion, said discharge portion extending backwardly from the forward end of the nozzle a relatively short distance, a relatively narrow metering orifice at the inlet end of said discharge portion, said nozzle also having inlet means for conducting oxidizing gas to said metering orifice and being provided with an obtuse angle bend in the effective region of said metering orifice, said metering orifice being disposed entirely on the discharge side of said obtuse angle bend.

5. A blowpipe nozzle for fiame machining having an oxidizing gas passage extending therethrough terminating in a discharge portion, said discharge portion extending backwardly from the forward end of the nozzle a relatively short distance, a relatively narrow metering orifice at the inlet end ofsaid discharge portion, said nozzle also having inlet means for conducting oxidizing gas to said metering orifice and being provided with an obtuse angle bend in the effective region of said metering orifice, the side walls of said discharge portion being substantially parallel and terminated at the inlet end thereof by a substantially square inner face in the center of which said metering orifice discharges.

6. A blowpipe nozzle for flame machining having an oxidizing gas passage extending therethrough terminating in a discharge portion, said discharge portion extending backwardly'from the forward end of the nozzle a relatively short di'stance, a relatively narrow metering orifice at the inlet end of said discharge portion, said nozzle also having inlet means for conducting oxidizing gas to said metering orifice and being provided with an obtuseangle bend in the effective region of said metering orifice, and heating gas orifices adjacent said oxygen discharge orifice said heating gas orifices being arranged into two groups, one group of three heating gas orifices being above and the other group of four heating gas orifices being below said discharge orifice.

7. A blowpipe nozzle for flame machining having an oxidizing gas passage extending therethrough" terminating in a discharge orifice, said discharge orifice extending backwardly from the forward end of the nozzle a relatively short distance, a relatively narrow metering orifice at the inlet end of said discharge orifice, said nozzle also having inlet means for conducting oxidizing gas to said metering orifice, and said oxidizing gas passage being provided with an obtuse angle bend in the effective region of said metering orifice, the ratio between the diameter of said discharge orifice and the diameter of said metering orifice being between 2 and 3.

8. A blowpipe nozzle for flame machining grooves comprising a body portion having an oxygen passage therethrough, said oxygen passage having an outlet portion extending a relatively short distance back from the outlet end of the nozzle, a metering passage in said oxygen passage for discharging oxygen into said outlet portion at a slight inclination to the axis of said outlet portion, and an inlet portion for conducting oxygen to said metering passage.

9. A blowpipe nozzle for flame machining deep grooves comprising a main body portion and a short end portion at an obtuse angle thereto, said nozzle having an oxygen passage therethrough, said oxygen passage having a cylindrical outlet portion extending a relatively short distance back from the outlet end of the nozzle, and a relatively long inlet portion for conducting oxygen to said outlet portion, said inlet portion being relatively narrow where it discharges into said outlet portion and entering said outlet portion at a slight inclination to the axis of said outlet portion.

10. A blowpipe nozzle for flame machining having an oxidizing gas passage extending therethrough and terminating in a discharge orifice, said discharge orifice extending backwardly from the forward end of the nozzle a relatively short distance; a relatively narrow metering passage at the inlet end of said discharge orifice, said nozzle also having a relatively long inlet portion con- I ducting gas to said metering passage, and said nozzle being provided with an obtuse angle bend in the region of said metering passage, the metering passage being partially within the bend and having a portion on the outlet side of the bend inclined downwardly from the axis of said discharge orifice.

11. A blowpipe nozzle for flame machining having an oxidizing gas passage extending therethrough terminating'in a discharge portion, said discharge portion extending backwardly from the forward end of the nozzle a relatively short distance, said oxidizing gas passage having a relatively narrow metering orifice at the inlet end of said discharge portion, said nozzle also having inlet means for conducting oxidizing gas to said metering orifice and being provided with an obtuse angle bend in the effective region of said metering orifice, said' discharge portion having a length between 2 to 5 times its diameter,

.12. A blowpipe nozzle for flame machining grooves comprisinga body portion having an oxygen passage therethrough, said oxygen passage having an outlet portion extending a relatively short distance back from the outlet end of the nozzle, the length of said outlet portion being between 2 to 5 times its diameter; a metering passage in said oxygen passage discharging into said outlet portion at a slight inclination to the axis of said outlet portion, the ratio between the diameter of said outlet portion and the diameter of said metering passage being between 2 and 3; and an inlet portion conducting oxygen to said metering passage.

13. A blowpipe nozzle for flame machining comprising a body portion having an oxygen pas sage therethrough, said oxygen passage having an outlet portion extending a distance back from the outlet end of the nozzle, the oxygen passage also having therein a metering passage arranged to discharge oxygen into said outlet portion at an inclination to the axis of said outlet portion, and an inlet portion for conducting oxygen to said metering passage.

14. A blowpipe nozzle comprising a body having a passage provided with an inlet portion and an outlet portion, a partition separating said inlet and outlet portions, said partition having a metering passage therein arranged to discharge substantially axially into said outlet portion, and said body having an obtuse angle bend in the effective region of said metering passage and substantially on the upstream side of said partition thereby providing an inlet body portion and an outlet body portion disposed at an obtuse angle with respect thereto.

15. A blowpipe nozzle as claimed in claim 14, in which said body comprises metal, and said partitioncomprises an insert of metal harder than that of said body.

16. A blowpipe nozzle as claimed in claim 14, in which said partition is integral with said nozzle.

17. A blowpipe nozzle for flame machining comprising a main body portion and a relatively short end portion at an obtuse angle thereto, said nozzle having an oxygen passage therethrough, said oxygen passage having an enlarged outlet portion extending back from the outlet end of the "nozzle a distance which is more than two and less than five times the width of said outlet portion; said oxygen passage having a relatively restricted metering orifice at the inlet end of said outlet portion arranged for discharging oxygen into and substantially along the axis of said outlet portion, said orifice being in the downstream efiective region of the bend of said nozzle; and inlet means in the main body portion of the nozzle for conducting an adequate flow of oxygen to said metering orifice.

EVERETT P. JONES.

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