US2266834A - Blowpipe nozzle - Google Patents

Description

Patented Dec. 23, 1941 2,266,834 nnowrrrn NOZZLE Wesley S. Walker, Pelham, N. Y., and Wilgot J.

Jacobsson, Scotch Plains, N. 1., assign orsto The Linde Air Products Company, a corporation of Ohio Original application May 9, 1931, Serial No.

536,254. Divided and this application November 26, 1937, Serial No. 176,400

\ 13 Claims.

Our invention relates to a blowpipe nozzle adapted to remove defective and excess metal from the surface of large masses of metal. Our blowpipe nozzle is particularly useful for removing seams or other defects from steel slabs, blooms, or billets. It is important that all defective metal portions in the surface of such masses of metal be removed before they are initially rolled and before each succeeding rolling process. When metal containing surface fissures or other surface defects is rolled, the defects are not eliminated and they are sometimes rolled into the body of the metal in the form of concealed. unbonded scams or cracks. Also, when the surface of metal having steep projections thereon or grooves therein with steep sides is rolled out, the sides of these irregular surfaces fold over and include oxides within the folds and cause concealed cracks in the body of the metal in the same way. In order to eliminate the defects and the formation of seams within the body of the metal, it is necessary to remove the defective metal portions sothat only sound bonded metal remains and so that theslopes of the depressions and elevations that may be left on the surface of the billet will be so gradual that these slopes will not be folded over and rolled into the body of the metal when it is rolled.

We have discovered that much time and labor can be saved by removing the defective surface portions of the steel or iron thermochemically with the use of an oxidizing stream of gas, and

that the desired contour of the groove cut by the oxidizing gas can be obtained with a blowpipe nozzle constructed to permit the passage of a suitable volume of gas at a relatively low orifice velocity, such as, for example, about 585 feet per second, and that the contour of the out can be controlled by the shape of the orifice and the velocity of the oxidizing stream issuing therefrom. Velocities of the gas stream commonly used for oxygen cutting or severing of metals are equal to or higher than the velocity that is produced by gas flowing through a passage of uniform cross-sectional area. Therefore, the relatively low orifice velocity desired for removing surfac metal is one which is below that commonly used for cutting kerfs.

The method of employing our nozzle for thermochemically removing surface metal from steel bodies to form shallow grooves is covered in our copending divisional application Serial No. 337,- 632 filed May 28, 1940. Another method of thermochemically removing surface metal from new surface, and the body produced by such method is covered in the copending application Serial No. 107,334 filed October 24, 1936 by H. W. Jones, H. W. Cowin and W. J. Jacobsson.

One of the objects of our invention is to construct a blowpipe nozzle adapted to deliver a suitable volume of oxygen at a relatively low orifice velocity for removing surface metal.

Another object of our invention is to construct a blowpipe nozzle having passages for a combustible gas mixture, and an enlarged oxygen passage adapted to permit the oxygen to expand in the nozzle toward th discharge orifice and to permit the end of the nozzle to be trimmed off without enlarging the discharge orifices of the passages.

Another object of our invention is to construct a blowpipe nozzle adapted to discharge a crosssectlonally oblong or sheet-like stream of oxygen enveloped in a flame.

The above and other objects of our invention will be best understood by referring to the following description and accompanying drawing, in which:

Fig. 1 is a longitudinal cross-sectional view of our blowpipe nozzle in an incomplete stage of manufacture and having a circular discharge orifice;

Figs. 2 and 3 are end views of the discharge orifice and the coupling ends of the nozzle shown in Fig. 1, respectively;

Figs. 4 and 5 are, respectively, a longitudinal cross-sectional view and a view of the discharge orifice end of a nozzle having its discharge end face inclined to the axis of the nozzle and having an oblong oxygen orifice in said face according to our invention;

Fig. 6 is a longitudinal cross-sectional view of a modification of our blowpipe nozzle having its discharge end face perpendicular to the axis of the nozzle and having an oblong or transversely elongated discharge orifice in said face;

Fig. 7 is a. longitudinal cross-sectional view taken on line of Fig. 6; and

Fig. 8 is a view of the discharg orifice end of the nozzle shown in Figs. 6 and 7.

Referring to Figs. 1 to 3, the blowpipe nozzle I 0 has an inlet end suitably formed to be attached to the head (not shown) of a suitable blowpipe. The external threads I! on the coupling nut l3 cooperate with internal threads in the blowpipe head to' maintain the inlet portion ll of a central oxygen passage l5 and the inlet portions l6 of the ring of combustible gas steel bodies to form a relatively wide and flat as mixtur passages II in the nozzle in communication with corresponding oxygen and combustible gas supply passages in the blowpipe head. The combined area of the combustible mixture passages ll is made sufficient to maintain a flame of sufficient size and intensity to heat the metal quickly to the ignition temperature to start the scarflng cut, the heat of the flame thereafter assisting in producing a clean cut or channel by adding heat to the oxygen and the burning metal. The gas mixture passages H are arranged in a ring around the central oxygen passage I5. The passages are straight and are of the same cross-sectional area and shape as the discharge orifices for a substantial distance backward from the orifices which are placed close to each other to give a flame of substantially uniform intensity throughout, and to heat the surface of the metal uniformly and thereby prevent small sub-channels from being formed in the surfaces of the scarf cut by the oxygen stream. As a specific example, a nozzle having an oxygen orifice .438" in diameter, and six combustible gas orifices each .055" in diameter has operated satisfactorily, but a greater number is preferable for smoother work. Where the number of orifices is'increased, the area of each may be decreased to maintain th quantity of combustible gases discharged within the proper limits to prevent waste.

The oxygen passage I5 in the nozzle I is enlarged adjacent to the inlet I4 by a gradually tapered or flared portion I9 which extends divergently toward the discharge orifice 20. In order that the gas stream passing through the passage I5 may have the desired relatively low velocity, it is apparent that the gradually flared portion I9 should be proportioned to have a sufficient degree of expansion to cause the velocity of the gas stream to be reduced. The tapered portion terminates in a plane a substantial distance from the discharge orifice 20, and the bore from the termination of the taper I9 to the discharge orifice is straight and of the same crosssectional area as the discharge orifice.

During the operation of the nozzle, the outlet orifices and especially the orifices of the combustible gas mixture passages may become obstructed due to the melting of the orifice end of the nozzle by the intense heat of the flame and due to the adherence. to the end of the nozzle of portions of molten surface metal that is being removed from the work piece. tions greatly interfere with the flow of oxygen and the combustible gas mixture and thereby change the desired ratio of flow of these gases and also reduce the rate of generation of preheat at the orifice end of the nozzle. In order to free the orifices from these obstructions, it is desirable to trim the face of the orifice end of the nozzle. This may be done many times before the nozzle is otherwise unfit for use. Therefore, in order that the area of the combustible gas orifices and the area of the oxygen orifices, and the ratio of these orifices to each other may not be changed when the end of the nozzle is trimmed, the area of the passages adjacent to the end of the nozzle is made of uniform cross-section.

Another advantage derived from making the oxygen passage straight adjacent to the end of the outlet orifice and of the same area and shape as the outlet orifice, is that the parallel walls of the passage lessens the tendency of the stream of oxygen to spread after it has been discharged from the outlet orifices. This action confines most of the oxygen to the groove being cut and thereby reduces the amount of oxygen These obstrucwhich is wasted due to dispersion upwardly and produces a more efficient oxidation of the metal.

The nozzle shown in Figs. 4 and 5 is completed by modifying the nozzle shown in Figs. 1 to 3. In this modification the discharge end of the nozzle is so shaped that it is adapted to discharge a stream of oxygen having an oblong cross-section which is capable of cutting a wider groove of greater mean radius of curvature per unit area of cross-section of the oxygen stream. Only the dissimilar features will be particularly described in reference to Figs. 4 and 5, and the corresponding parts will be designated by the same reference numerals with the addition of 100. The discharge end face of the nozzle III] is provided with an oblong oxygen orifice I20. This may be done by making a cylindrical tip with a circular bore as shown in Figs. 1 to 3 and dcforming or flattening the discharge end of the tip until the central oxygen passage assumes the oblong or s1otlike cross-sectional shape as shown in Fig. 5 where it is seen that the upper and lower walls of the orifice I20 are preferably flat and the side walls are preferably of semi-cylindrical contour. The oxidizing gas passage thus is relatively small at the inlet portion II4, expands to a maximum cross-sectional area at its intermediate portion H5 and is gradually reduced to a slightly smaller cross-sectional area in the slot-like orifice portion I20. In order to minimize the upward dispersion of the oxygen and to bring the upper heating flames issuing from the heating gas passages III closer to the metal being removed, the discharge end of the tip I I0 is cut on a bias by a plane containing the long axis of a section of the discharge orifice I20. A suitable angle for the plane of the cut is about 75 to the longitudinal axis of the oxygen paisage II5.

In Figs. 6 to 8 there is shown another modification of a blowpipe nozzle having an oblong or widened oxygen discharge orifice having rounded side walls. Only the details of parts of this nozzle which differ from the parts of the foregoing modifications will be described in detail. The members which correspond to the members of the modifications previously described will be designated by the same reference numerals with the addition of 200.

Exclusive of the coupling nut 2I3, this nozzle comprises three parts which are welded or silver soldered together, The stem 22I of the nozzle 2I0 is provided with a head 222 of the type having conical seats 223 to fit complementary seats (not shown) in a blowpipe head adapted to receive a nozzle head of this well-known construction. The stem 22I is provided with a plurality of combustible gas mixture passages 2I6 which deliver gas to a distributing chamber 224 surrounding the outer end of the stem 22I. The distributing chamber 224 is formed by cutting a circumferential groove 225 about the stem 22I at its outer end and enclosing this groove with a discharge orifice piece 226 which is secured to the end of the stem 22I and a ring 221 which is silver soldered to the end of the orifice piece 226 and to the outer wall of the stem 22I. A large number of equally spaced combustible mixture passages 2II are formed in the wall of the orifice piece 226 about a relatively wide oblong or slot-shaped oxygen passage 220. Preferably about 12 combustible gas mixture passages 2I'I are formed in the orifice piece 226 in order to envelop the stream of oxygen which may issue from the orifice piece 226 with a fiame of uniform crosssectional intensity. The mixture passages 2H on the broader sides of the orifice piece 226 converge toward the oxygen discharge orifice 220. In this modification, as in the other modifications, the combustible gas mixture passages 2H and the oxygen passage 220 in the orifice piece 228 are straight and have the same area ofcrosssection as their respective discharge orifices for a substantial distance backward therefrom, with the resulting advantages derived from these features which have been described in reference to the other modifications. The wide slot-like oxygen orifice 220 of the oxygen passage communicates through an enlarged cylindrical portion 2 [5 with a large divergent passage 2I9, smoothly connecting the portion 2I5 with the inlet portion 2| 4. It will be seen, therefore, that the relatively large oxygen passage of the nozzle is of either constant or gradually increasing crosssectional area from the inlet portion up to the outlet orifice 220 and that the maximum crosssectional area occurs in the cylindrical portion Hi, the cross-sectional area of the orifice 220 being slightly smaller. The slot-like orifice 220 is connected with the cylindrical portion 2 l 5 by a connecting portion 2l5' having side walls that diverge from the width of the large portion M5 to the width of the orifice 220 and upper and lower walls that converge from the height dimension of the portion 215 to the height dimension of the orifice 220. Although the taper of the portion 2l9 is sufficient to cause the gas stream to expand turbulently and thus reduce the velocity of fiow, an equalized velocity distribution is attained throughout the entire width of the outlet end of the orifice 220. Such equalized distribution may be attributed mainly to the enlarged intermediate portion which reduces turbulence in cooperation with the lateral expansion effected by the diverging side walls of the connecting portion 2 I5.

When the nozzles described herein are used for making surface cuts, such as grooves or scarfs, the axis of the oxygen passage in each nozzle is held at an acute angle to the surface of the work and in a plane which will be included by the scarf and which is normal to the surface of the work. As the scarf is made the nozzle is advanced parallel to the surface in the direction of the inclination of the nozzle and toward the surface portions to be removed. When using the oblong or elongated orifice, one of the broader sides of the orifice is placed adjacent to the work, and when the nozzle having its end face inclined to the axis of the nozzle is used, the cut away side is placed adjacent to the work.

The speed of cutting and the contour of groove obtained with our nozzle depends upon the kind of metal being removed, the shape, volume and velocity of the discharged oxygen stream, and the rate of delivery and distribution of the combustible gas mixture. As a specific example in the process of removing seams from steel billets having about .4% of carbon and 1.05% chromium with the usual amounts of impurities it has been found that a nozzle having a circular oxygen orifice .438f in diameter, of the type shown in Figs. 1 to 3 when employing an oxygen discharge velocity of 585 ft. per sec., will successfully remove at a speed of 6 ft. per min. a seam /2 in. in depth and leave a groove 11/ in. in width at the top which is suitable to be rolled out without causing its sides to be folded over. In the above exampie the axis of the nozzle was held at an angle of about 38 with the surface of the work.

The figures given herein in reference to the modification of our nozzle disclosed in Figs. 1 to 3 are given as a specific example only, and it is to be understood that these figures may be varied within wide limits depending upon varying conditions and results desired. For example, the discharge velocity of the oxygen may be increased when it is desirable to increase the speed of cutting and the depth of the cut, and the velocity may be decreased to decrease the speed of cutting and the depth of the cut.

The curvature of the scarf may be controlled by the shape of the oxy en discharge orifice for any given projected length of orifice opening upon the work. It has been found that a nozzle having a circular orifice of a given diameter cuts a scarf with a smaller radius of curvature at the bottom than a nozzle having an oblong orifice with a major axis equal to the diameter of the circular orifice. The selection of a nozzle having a particular shape of orifice depends upon the class of work to be done. For example, in cutting out isolated seams, the circular orifice is suitable. In making broad surface cuts, as when the surface of the metal is skinned oil, the nozzle adapted todischarge an oblong or ribbon-like column of oxygen is preferable, because a greater area of surface metal can be removed per cubic foot of oxygen consumed. Furthermore, the surface of the metal is left in a smoother condition because wider scarfs, each having a greater radius of curvature, can be made. Therefore, there are fewer ridges formed by the juncture of one scarf with another, and the tendency to form fins or slivers along these ridges or at the marginal edges of the scarf is reduced.

Obviously, the advantages derived by bevelling the end of the nozzle, as described above in connection with the form of nozzle illustrated in Figs. 4 and 5, are also realized when the forward end face of the nozzle shown in Figs. 1 and 2 is likewise constructed to lie in a plane which makes an acute angle with the longitudinal axis of the cylindrical orifice portion 20. The end of the orifice portion 20 will then have an elliptical outline in this plane but the oxidizing gas stream produced will still be substantially cylindrical.

Other uses not mentioned herein may be found for our nozzle and the details thereof may be changed without departing from the scope of our invention as defined in the appended claims.

We claim:

1. A blowpipe nozzle for scarfing or gouging metal, said nozzle having an oxygen passage and a plurality of combustible gas Passages, the oxygen passage having an inlet, an enlarged intermediate portion, and an oblong outlet of substantially greater cross-sectional area than said inlet but not greater than that of said enlarged portion, said passage being constructed and arranged to reduce the velocity of the oxygen so as to issue as a ribbon-like stream having a relatively low velocity, and said combustible gas passages having their outlets arranged adjacent said oblong outlet.

2. A blowpipe nozzle for scarfing or gouging metal, said nozzle having an oxygen passagecomprising an inlet and an oblong outlet orifice of greatercross-sectional area than said inlet, said outlet orifice lying in a plane inclined to the axis of said passage to provide an extended wall adjacent one side of said passage, said extended wall forming one of the long sides of said oblong outlet orifice.

3. A blowpipe nozzle for removing metal from the surface of metal bodies by directing a low velocity oxygen stream at an acute angle to heated portions of said surface to be removed, said nozzle having an oxidizing gas outlet passage defined by walls symmetrical about an axis, a forward end fade bevelled so that the outlet oriflce end of said passage lies in a plane inclined to said axis thereby providing an extended wall on one side of said orifice, passage means associated with said outlet passage having walls constructed and arranged for supplying oxidizing gas thereto equally at all port-ions of the entrance thereof ata pressure such that a uniform low velocity stream issues from said outlet passage, said passage means comprising an inlet portion of relatively smaller cross-sectional area than said outlet orifice and intermediate connecting wall portions expanding toward said outlet passage at a rate sufilcient to reduce the velocity of flow and expanding laterally to the width of said outlet passage and heating gas passages having outlet orifices in said plane adjacent said oxidizing gas orifice and adapted to direct heating flames against surface portions to be removed 4. A blowpipe nozzle for removing metal from the surface of metal bodies by directing a low velocity oxygen stream at an acute angle to heated portions of said surface to be removed, said nozzle having an oxidizing gas outlet passage deilned by walls symmetrical about an axis, the outlet orifice portion of said passage being relatively wide but transversely narrow in right section, a forward end face bevelled so that the outlet orifice of said passage lies in a plane parallel to the major transverse dimension of the orifice and inclined to said axis, passage means associated with said outlet passage having walls constructed and arranged for supplying oxidizing gas thereto equally at all portions of the entrance thereof at a pressure such that a uniform low velocity stream issues from said outlet orifice, said walls comprising intermediate wall portions expanding toward said outlet passage at a rate sufficient to reduce the velocity of flow and connecting wall portions expanding laterally to the width of said outlet orifice, and means for supplying combustible gas comprising passages having outlet orifices in said plane adjacent at least a wide side of said oxidizing gas orifice and adapted to direct heating fiames against the surface portions to be removed.

5. A blowpipe device for scarfing or gouging ferrous metal bodies, said blowpipe device having a relatively large oxygen passage therethrough and a plurality of combustible gas passages adjacent said oxygen passage, said oxygen passage having an outlet orifice elongated transversely of the axis of said nozzle, and an inlet portion of smaller cross-sectional area than said outlet orifice, said oxygen passage between said inlet portion and said outlet orifice being enlarged and having a portion gradually flared toward said outlet, said oxygen passage including said fiared portion having walls expanding sufficiently to reduce the velocity of flow of oxygen passed therethrough and connecting wall portions expanding laterally to the width of said orifice to then distribute the velocity of fiow so as to issue with a relatively low velocity substantially uniformly distributed along said elongated outlet orifice, and said combustible gas passages having outlets arranged adiacent a wide side of said outlet orifice.

6. A blowpipe nozzle for thermo-chemically removing surface metal from ferrous metal bodies, said nozzle having a relatively large oxygen passage therethrough, said passage having an inlet portion, an outlet orifice portion that is transversely elongated and slot-like, and a portion between said inlet portion and said slot-like orifice in axial alignment therewith that is enlarged to have a crosssectional area greater than the cross-sectional area of said inlet portion and also greater than the cross-sectional area of said outlet orifice, said passage having walls arranged to cause an oxygen stream passed therethrough I to expand at a rate su-fiicient to reduce the velocity of flow and then convert said stream into a substantially ribbon-like stream of greater width than thickness measured transversely of the direction of fiow.

7. A blowpipe nozzle for thermo-chemically removing surface metal from ferrous metal bodies; said nozzle having a relatively large oxygen passage therethrough, said passage having an inlet portion, an outlet orifice portion that is transversely elongated and slot-like and has a crosssectional area larger than the cross-sectional area of said inlet, and a portion between said inlet portion and said slot-like orifice which is enlarged to have a cross-sectional area greater than the cross-sectional area of said inlet portion and also greater than the cross-sectional area of said outlet orifice, said passage having walls arranged to cause an oxygen stream passed therethrough to expand at a rate sufiicient to reduce the velocity of flow and then convert said stream into a substantially ribbon-like stream of greater width than thickness measured transversely of the direction of flow.

8. A blowpipe device for thermo-chemically removing surface metal from ferrous metal bodies, said blowpipe device having a relatively large oxygen passage therethrough, said passage having an inlet portion, an outlet orifice of larger cross-sectional area than said inlet portion and a portion between said inlet portion and said outlet orifice that is enlarged to have a crosssectional area greater than the cross-sectional area of said inlet portion, and also greater than the cross-sectional area of said outlet orifice, said passage having walls arranged to cause an oxygen stream passed therethrough to expand at a rate sufiicient to reduce the velocity of flow and then distribute the gas to flow with equal velocity throughout the entire width of said orifice.

9. A blowpipe device for thermo-chemically removing surface metal from ferrous metal bodies, said blowpipe device having a relatively large oxygen passage therethrough; said passage having an inlet portion, an outlet orifice portion that is transversely elongated and slot-like, an intermediate portion flaring from said inlet portion toward said slot-like orifice, another enlarged intermediate portion at the large end of said first-mentioned intermediate portion having a cross-sectional area greater than the crosssectional area of said inlet portion, and a connecting portion in axial alignment with said outlet orifice portion having side walls diverging from the width of said enlarged portion to the width of said slot-like orifice and upper and lower walls that converge from the height dimension of said enlarged portion to the height dimension of said slot-like orifice; said passage being arranged to cause an oxygen stream passed therethrough to expand at a rate suflicient to reduce the velocity of flow and then convert said stream into a substantially ribbon-like stream of greater width than thickness measured transversely of the direction of flow.

10. A blowpipe device for thermo-chemically removing surface metal from ferrous metal bodies, said blowpipe device having a relatively large oxygen passage therethrough, said passage comprising an inlet portion, an outlet orifice portion that is transversely elongated and slot-like, and an enlarged intermediate portion, the walls of said intermediate portion adjacent said inlet being divergent to a degree which causes the oxygen to expand at a rate suflicient to reduce the velocity of flow, said intermediate portion having side walls adjacent said orifice which diverge to the width of said orifice, the degree of divergence of said side walls and the enlargement of said intermediate portion being suflicient to efiect equalization of said reduced flow velocity along the width of slot-like orifice.

11. A blowpipe device for thermo-chemically removing surface metal from ferrous metal bodies, said blowpipe device having a relatively large oxygen passage therethrough having an inlet, an outlet orifice that is transversely elongated and slot-like, a large intermediate portion between said inlet and said outlet orifice, and a connectin: portion in axial alignment with said outlet orifice and said intermediate portion and having side walls diverging from the width of said intermediate portion to the width of said slotlike orifice and upper and lower walls that converge from the height dimension of said intermediate portion to the height dimension of said slot-like orifice, whereby an oxygen stream passed therethrough is converted into a substantially ribbon-like stream flowing with substantially equal velocity throughout its width.

12. A unitary blowpipe nozzle, which comprises an elongated nozzle body, a longitudinal passage extending through said body, said passage having an inlet, an intermediate portion, and an outlet orifice that has a transversely wide and slot-like cross-sectional shape, said inlet and said outlet orifice being respectively or smaller crosssectional area than the intermediate portion of said passage, and said outlet and intermediate portions being in axial alignment.

13. A unitary blowpipe nozzle, which comprises an elongated nozzle body, a longitudinal passage extending through said body, said passage having an inlet, an intermediate portion provided with tapered side walls, and a restricted outlet orifice that is transversely wide and slot like, and in axial alignment with said intermediate portion, said outlet orifice having a smaller crosssectional area than said intermediate portion.

WESLEY S. WALKER. WILGOT J. JACOBSSON.

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