|Publication number||US3656879 A|
|Publication date||Apr 18, 1972|
|Filing date||Apr 29, 1970|
|Priority date||Jan 14, 1969|
|Publication number||US 3656879 A, US 3656879A, US-A-3656879, US3656879 A, US3656879A|
|Inventors||Vries Hendrik De Jr|
|Original Assignee||N L Applic Sa|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (2), Referenced by (9), Classifications (17)|
|External Links: USPTO, USPTO Assignment, Espacenet|
United States Patent 151 msoew De Vries, J [451 Apr. 18, W72
[ METHOD OF MANUFACTURING A  References Cited BURNER AND A BURNER THUS Y MANUFACTURED v I FOREIGN PATENTS OR APPLICATIONS  Inventor: Hendrik De Vries, Jr., Nijmegen, N etherg ss lands  Assignee: N. L. Application S.A., Fribourg, Switzer- Primary yJ land Attorney-Schmidt, Johnson, Hovey & Williams  Filed: Apr. 29, 1970 57 ABSTRACT PP N04 2,703 A gas burner comprising a tube having a gas supply connection, there being a sleeve partly engaging the outside of the  Foreign Application i i Data tube and partly spaced therefrom whereby to define a space between the sleeve and the tube presenting a gas expansion July 14, 1969 Netherlands ..6,9l0,775 h b outlet ts i the tube and means placing the Jan. 14, 1969 Netherlands ..6,900,55 5 hamber i communication with the parts, The burner is manufactured by forming an outlet port in a tube, forming a US. Cl. R, R, longitudinal groove in the tube and placing a leeve having 7 239/554 grooves therein over the tube whereby to create the gas ex- [5 1] int. ansion chamber and placing the same in communication with  Field of Search 1/349; 239/554, 567; h l
26 Claims, 15 Drawing Figures PATENTEDAPR 18 I972 SHEET 2 0F 6 IIIII FIG 7 PATENTEBAPR 18 are SHEET 3 0F 6 METHOD MANUFACTURING A BURNER AND A BURNER THUS MANUFACTURED According to this invention a burner comprises a tube having a gas supply connection and a sleeve partly engaging the outside of the tube and being partly located at a distance from the tube, the arrangement being such that gas can flow from the connection into the tube and into the space between the sleeve and the tube, outlets being provided in the tube portion not engaged by the sleeve, the sleeve and the tube being so formed that the said space constitutes a gas expansion chamber, and grooves being provided through which gas can pass from the expansion chamber, thence between'the tube and sleeve, to atmosphere in the region of the outlet ports.
In this manner a burner can be obtained which is particularly suitable for slowly burning types of gas, for example, natural gas, while in addition the burner operates noiselessly, because pre-mixing of combustion air, which produces comparatively high noise, is not employed. Moreover, the gas can flow at full pressure to the outlet ports so that the burner has the advantage of an optimum flame pulse, it being thus possible to design compact gas-consuming apparatus. The burner also pennits ready cleaning of the grooves forming auxiliary gas dosing ports, these grooves being readily accessible.
A further advantage of the burner of the invention over burners with pre-mixing of primary combustion air is that the risk of dust being sucked in by the combustion air is avoided. I
A burner in accordance with the invention can be manufactured in a simple manner by slipping onto a tube having at least one outlet port a sleeve having a longitudinal slot and formed so that the parts bounding the longitudinal slot intimately engage the tube, an intermediate piece interconnecting the parts bounding the longitudinal slot being located at a distance from the tube wall opposite that part of the tube wall where the outlet ports are provided, and grooves being provided between the parts bounding the longitudinal slot and the opposite parts of the tube, which grooves form connections between the expansion chamber and the edges of the longitudinal slot.
The invention will now be described by way of example with reference to the accompanying drawings, in which:
FIG. 1 is a perspective view of part of a burner;
FIG. 2 is a perspective view showing the formation of circular grooves in the tube;
FIG. 3 is a perspective view showing a different method of fonning the circular grooves;
FIG. 4 is a bottom plan of a burner, the sleeve being omitted and the burner being provided on one side with a connecting piece for a supply pipe;
FIG. 5 is a side elevation of the burner shown in FIG. 4, with the sleeve in position;
FIG. 6 is a top plan of the burner of FIG. 4, with the sleeve in position;
FIG. 7 is a top plan of several burners;
FIG. 8 is a side elevation of the burner of FIG. 7;
FIG. 9 is a side elevation of a second embodiment of a burner;
FIG. 10 is a section through a third embodiment of a burner;
FIG. 11 is a perspective view of part of a fourth'embodiment of a burner;
FIG. 12 is a side elevation of the burner of FIG. 11, part of the sleeve being broken away;
FIG. 13 is a bottom plan of the part of the burner shown in FIG. 12; l
FIG. 14 is a perspective view ofpartof a fifth embodiment of a burner; and
FIG. 15 is partly a sectional and partly a side elevation of the burner of FIG. 14.
As shown in FIG. 1, the burner comprises a tube 1 having a plurality of circular indents or grooves 2. The bottom side of the tube has a longitudinal groove or depression 3, in which a few openings 4 are provided. The top side of the tube has a thinner portion 5 obtained by removing material to form a face 6 on the tube. This thinner portion 5 has a plurality of gas outlet ports 7 of very small diameter. For natural gas this diameter will be of the order of 0.2 mm. The ports 7 are located in the same planes as the grooves 2. The openings 4 are of larger diameter than the ports 7, but the openings 4 are provided in a smaller number, for example, only one.
The tube 1 is partly surrounded as shown by a sleeve 8 having a longitudinal slot, the sleeve 8 being arranged so that the outlet ports 7 open to atmosphere between the sleeve parts engaging the tube so as to engage it intimately and bounding the longitudinal slot, while an intermediate or central piece of the sleeve forms, together with the depression 3, a chamber 9 which communicates with the outlet opening(s) 4 and the flow channels formed by the indents 2. The space serves as an expansion space for the gas supplied.
The burner operates as follows: The gas to be burnt is supplied at a reduced pressure to the interior of the tube I and can flow out from the ports 7. The rate of flow of gas from the ports 7 exceeds, however, the rate of combustion of the gas, so
that a flame emanating from an outlet port 7 would extinguish itself, except that some of the gas also flows through the opening(s) 4 to the expansion space 9 from where the gas can escape along the indents 2 and, owing to the matching proportioning of the opening(s) 4 and the grooves 2, at a considerably lower pressure, and can be ignited as auxiliary flames 10, which can ignite the gas emanating from the ports 7 continuously to form main flames 11. Since the gas is conducted without reduction of pressure to the ports 7, main flames 11 of a high flame pulse are produced, so that a very compact apparatus can be designed. The gas does not contain premixed combustion air, so that the flames burn substantially silently. With this arrangement is is possible to clean the depressions or indents, because they are readily accessible.
FIGS. 2 and 3 illustrate two possibilities for forming the circular indents 2. As shown in FIG. 2, a commercially available tube 1 is pressed against an auxiliary roller 12, which is provided with circular ridges l3 equally spaced apart. The tube 1 and roller 12 are rolled one along the other under pressure so that the ridges l3 produce the indents 2.
FIG. 3 shows a further possibility of forming the indents 2. The tube 1 is rolled over a plate 14 provided at regular intervals with parallel ridges 15. The tube is rolled in the direction of the ridges 15, which thus produce the circular indents 2. The grooves may alternatively be provided by a chipping operation on a kind of lathe. The longitudinal groove 3 may be rolled in the tube. The face 6 may be provided by milling or .abrading a local part of the tube, but in a variant a hollow groove may be milled out so that the thickness of the material is reduced. This has the advantage that the small outlet ports need be pierced only through a thin layer of metal and rupture or wear of the drills used is reduced, the diameter of the drills being about 0.2 mm. After this pre-treatment of the tube, the sleeve can be slipped onto it.
FIGS. 4, 5 and 6 show a burner manufactured as described above and provided at one end with a connecting piece I6 for a gas supply pipe, the other end of the tube being closed by pinching in the manner usually applied to a tube of toothpaste. This closure is designated 17. FIG. 4 does not show the sleeve 8 in order to show the position of the longitudinal groove 3 and an opening 4. The burner shown in FIGS. 4, 5 and 6 is preferably connected with a horizontal gas supply tube, with which a plurality of the burners may be connected, so that a burner assembly is obtained suitable for use, for example, in a gas geyser or a central-heating boiler. As compared with the power involved the structure can be very compact so that the Construction of the whole heating apparatus is compact.
FIGS. 7 and 8 show a further embodiment of the invention. A number of tubes 1, provided on two sides with indents 2, longitudinal grooves 3 (now shown), faces 6 and outlet ports 4 and 7 in the manner described above, are connected with a main supply pipe 18, which communicates with the interiors of the tubes 1. The tubes 1 are arranged so that they project on either side equal distances beyond the pipe 18. The two ends of each tube 1 are pinched to form closures 17. On either side of the pipe 18, a sleeve 8 is slipped on to each tube 1. In this way a battery or multiple burner is formed which may be employed also in a gas geyser or a heating boiler, and whose structure is also very compact.
FIG. 9 shows a further embodiment of the invention, particularly suitable for converting town-gas burners into naturalgas burners. A tube 1, formed in the manner described above, is provided at the centre with a connecting piece 19 which may be screwed onto existing gas pipes after an existing burner has been unscrewed. This connecting piece 19 communicates with the interior of the tube 1. In this case the expansion chambers 9 are provided with an inlet port 21, which is provided at one end of the longitudinal groove. The ends of the tube 1 are closed by caps 20.
The upper side of the tube 1 has two faces 22 and 23 milled at a given angle to each other, so that a double row of V- shaped flames is obtained. It is possible to retain a horizontal face 24 on the upper side, so that W-shaped flames can be produced, as shown.
An important advantage of the burners described above resides in the facts that the basic material is cheap and commercially available and that machining can be carried out by simple means. Other advantages are that the burners can be compact, and gas can burn noiselessly, because it is not previously mixed with combustion air. A further advantage is that the burner may be manufactured in a great length and be cut to desired lengths. The range of uses is therefore wide.
The burner shown in FIGS. 11 to 13 comprises a tube 25, which is milled or smoothed on the upper side for obtaining a comparatively thin upper portion 26. The upper portion 26 is provided with bores 27, which together form a row of outlet ports extending in the longitudinal direction of the tube. The diameter of these ports may be small and in the case of natural gas will be of the order of 0.2 mm. Approximately diametrically opposite the outlet ports 27 one or more flow ports 28 are provided in the wall of the tube. The diameter of a port 28 exceeds that of a port 27, but, in general, the number of ports 28 will be considerably less than the number of ports 27. In many cases a single port 28 will be sufficient, if the length of the tube is not too great.
The tube 25 is slipped into a sleeve 29, which then partly surrounds the tube 25 and is provided with a longitudinal slot extending in the direction of the length of the tube. The elongated slot is bounded by two parts 30 and 31 of the sleeve, which parts intimately fit around the tube 25. The parts 30 and 31 are interconnected by an intermediate piece 32, which is located at a distance from the tube 1 so that between the intermediate piece 22 and the opposed tube portion a chamber 33 is formed. The parts 30 and 31 are also provided with depressions or indents 34, which form channels or grooves extending between the chamber 33 and the edges of the parts 30 and 31 bounding the elongated slot of the sleeve 29. The depressions 34 are preferably located so that their longitudinal axes are located in planes at right angles to the axis of the tube 25. When the tube is slipped into the sleeve 29 it can be arranged that the prolongations of the longitudinal axes of two depressions 34 in the parts 30 and 31 intersect at least approximately the center line of an outlet port 27. Each flow port 28 is arranged so that it opens out into the chamber 33.
A gas supply connection may be provided at one end of the tube 1. A further possibility for connection of a gas supply pipe is illustrated in FIGS. 12 and 13, from which it will be apparent that prior to the application of the sleeve a plate 35 is secured to the tube 1, which plate is located in the chamber 33 when the sleeve 29 is arranged in place. The dimensions of the plate are such that the portions of the chamber 33 located on either side of the plate 35 are in open communication with each other. The wall of the sleeve 29, the plate 35 and the tube 25 may be provided with registering holes 36 for connecting a gas supply duct.
The burner shown in FIGS. 11 to 13 can be manufactured in a simple manner, since the tube 25 may be a commercially available tube and the sleeve 29 can be shaped readily in the desired form by means'of rollers and can be provided with the depressions or indents 34. Piercing of the outlet ports 27 and of the flow port(s) 28 in the tube 25 can be readily carried out by drilling. An advantage is that the upper side of the tube 25 is flattened so that the wall thickness of the tube 25 at the area of the outlet ports 27 is comparatively small which reduces drill wear. Flattening of the upper side is not absolutely necessary. After the tube 25 and the sleeve 29 have been machined in the manner described above, the tube 25 need only be slipped into the sleeve 29 in the correct position so that the depressions 34 are opposite the outlet ports 27. The outlet ports 27 may be made in the tube 25 both before or after application of the sleeve. Then a gas supply connection can be established with the tube 25, or a number of these burners may be assembled to form a grating or the like, which is connected with a common supply pipe, after which the burner is ready for use. The ends of the tube and the ends of the chamber 33 must be closed effectively and this may be achieved by pinching one end of the tube 25 as in the preceding embodiments.
The burner operates as follows:
The gas to be burnt is supplied without reduction of pressure to the interior of the tube 25 and can escape to the outside via the outlet ports 27. The rate of flow of the gas from the ports is, however, higher than the rate of combustion of the gas, so that without further precautions the gas escaping from the outlet ports 27 would not burn. However, a portion of the gas supplied to the tube also passes through the port(s) 28 into the chamber 33, which fonns an expansion space, from where the gas can escape at considerably reduced pressure through the depressions or grooves 34, the port(s) 28 and the grooves 34 being suitably proportioned. The gas slowing from the grooves or auxiliary gas passages 34 can be ignited so that auxiliary flames 37 are formed. By means of these auxiliary flames 37 the gas flowing from the outlet ports 27 is ignited and kept burning, so that main flames 38 are formed. Since the gas is fed without reduction of pressure to the outlet ports 27, main flames 38 having a high flame pulse are produced.
The burner shown in FIGS. 14 and 15 comprise a tube 40, which is milled or flattened on the upper side to obtain a comparatively thin upper portion 41. The upper portion 41 is provided with bores 42 which form a row of outlet ports extending in the longitudinal direction of the tube. The diameter of these ports may be small and, for example, with natural gas, will be of the order of 0.2 mm. The wall portion 43 of the tube located approximately diametrically opposite the outlet ports 42 is flattened so that this portion is parallel to a plane at right angles to the center lines of the row of outlet ports 42.
The tube 40 is slipped into a sleeve 44, which partly surrounds the tube and which is provided with an elongated slot extending in the direction of length of the tube and bounded by the edges of two parts 45 and 46 of the sleeve 44. The parts 45 and 46, fitting intimately around the tube 40, are interconnected by a U-shaped intermediate piece fonned by two limbs 47 and 48 lying on the edges of the parts 45 and 46 and a web 49 interconnecting the lower edges of the limbs and extending at right angles to them and parallel to the portion 43 of the tube 40.
The intermediate piece 47, 48, 49 encloses an insert of generally V-shaped section and formed by two plates 50 and 51 lying abutting the limbs 47 and 48 as shown, the plates terminating at a given distance above the web 49 in upwardly inclined, converging plates 52 and 53, integral with the plates 50 and 51. The upper ends of the plates 52 and 53, which ends are near the portion 43 of the tube 40, are interconnected by a plate 54 engaging the portion 43 and integral with the plates 52 and 53. The plates 52 and 53 are provided with ports 55 so that the plates 52 and 53 form a kind of perforated grating.
In the parts 45 and 46 of the sleeve 44 engaging the tube 40 depressions or indents 56 are provided, which form flow channels via which the chamber formed by the intermediate piece 44 and the wall portion 43 of the tube communicates with atmosphere.
The burner also has a supply pipe 57 which extends across the chamber bounded by the intermediate piece 44 and into the interior of the tube 40. The portion of the supply pipe 57 in the tube 40 has a bore 58 of comparatively large diameter forming an outlet port. The portion of the supply pipe 57 in the chamber bounded by the intermediate'piece 44 is provided with two smaller outlet ports 59.
This burner can be manufactured in a simple manner because the various parts can be readily shaped by rolling, while the various bores and connections can be provided in a comparatively simple manner.
ln operation the gas to be burnt is supplied at non reduced pressure via the supply pipe 57, the gas flowing at this pressure into the tube 40 and from there through the ports 42 to atmosphere. The rate of escape of the gas from the ports 42 exceeds, however, the rate of combustion of the gas so that without further steps the gas flowing from the outlet ports 42 would not burn. A portion of the gas supplied by the pipe 57 also flows through the ports 59 to the space formed by the expansion chamber, bounded by the intermediate piece 44. From this chamber the gas can flow through the flow channels 56, while a uniform distribution among the channels 56 is obtained by the perforated partitions or gratings 52 and 53. The gas flows from the channels 56 at a comparatively low rate owing to the reduction of pressure in the expansion chamber, and can be ignited, so that auxiliary flames are obtained which ignite the gas flowing from the outlet ports 42, which gas is then kept burning. Since the gas is supplied without pressure reduction to the outlet ports 42 main flames having a high flame pulse are obtained.
Since the gas is not previously mixed with combustion air, the burner will operate quietly. Since the gas can flow at full pressure to the outlet ports and since a high flame pulse is obtained, a comparatively compact structure of the combustion chamber, and hence a compact construction of the gas consuming apparatus, may be obtained. The auxiliary gas passages obtained by the indents 56 are readily accessible and can be cleaned readily. Since no combustion air is previously mixed with the gas, there is no risk that dust carried along by the combustion air will block the outlet ports. Owing to the ample size of the expansion chamber, bounded by the intermediate piece 44 and the wall portion 43 of the tube 40, clogging of this chamber by deposition of substances in the gas is not likely to occur.
The height of the intermediate piece 44 at the wall 43 of the tube 40 is preferably about 60 percent of the diameter of the tube 40 and the width of the intermediate piece is preferably about 80 percent of that diameter. The height of the tube at right angles to the face 43 is preferably about 85 percent of the diameter of the tube.
The burners described above can be manufactured in a simple manner from conventional, commercially available material, such as pipes and/or plates, which need be subjected only to comparatively simple operations, while the various parts can be readily connected to each other.
What we claim is:
1. A burner comprising a tube having a gas supply connection and a sleeve partly engaging the outside of the tube and being partly located at a distance from the tube, the arrangement being such that gas can flow from the connection into the tube and into the space between the sleeve and the tube, outlet ports being provided in the tube portion not engaged by the sleeve, the sleeve and the tube being so formed that the said space constitutes a gas expansion chamber, and grooves being provided through which gas can pass from the expansion chamber, thence between the tube and sleeve, to atmosphere in the region of the outlet ports.
2. A burner as claimed in claim 1 wherein the grooves are arranged-so that the two openings of the grooves located one each side of the tube and an outlet port are located in a plane at right angles to the longitudinal axis of the tube.
3. A burner as claimed in claim 1 wherein the grooves are provided in the wall of the tube.
4. A burner as claimed in claim 1 wherein the grooves are provided in the parts of the sleeve engaging the tube.
5. A burner as claimed in claim 1 wherein the sleeve has an at least substantially circular section and the tube is provided with a longitudinal groove to form'the expansion chamber.
6. A burner as claimed in claim ll wherein the wall thickness of the tube at the area of the outlet ports is smaller than the wall thickness of the further part of the tube.
7. A burner as claimed in claim 1 wherein outlet ports are provided at regular intervals in the wall of the tube so that the outlet ports are located at least substantially in one row extending substantially in the direction of length of the tube.
8. A burner as claimed in claim 1 wherein there is an intermediate piece interconnecting the two sleeve parts intimately engaging the tube which is bent over relatively to said parts so that the intermediate piece is located at a distance from the tube wall so that between the tube wall and the intermediate piece an expansion chamber extends in the direction of length of the tube.
9. A burner as claimed in claim 8 wherein the portion of the tube wall located in the chamber has secured to it a plate to fonn a connection.
10. A burner as claimed in claim 9 wherein the width of the plate is smaller in sectional area than the width of the chamber.
11. A burner as claimed in claim 1 wherein the two sleeve parts engaging the tube are interconnected by means of an intermediate piece, the sectional area of which has the shape of a substantially rectangular U.
12. A burner as claimed in claim 1 wherein the wall portion of the tube provided with outlet ports and located between the sleeve parts engaging the tube is flattened.
13. A burner as claimed in claim 12 wherein the flattened part of the tube extends parallel to the web between the limbs of the intermediate piece.
14. A burner as claimed in claim 1 wherein a gas supply pipe is connected with the tube and the tube wall is provided with at least one opening through which gas can flow from the tube to the expansion chamber.
15. A burner as claimed in claim 14 wherein both the tube and the expansion chamber communicate directly with a gas supply pipe.
16. A burner as claimed in claim 11 wherein a supply pipe is provided which extends transversely of the direction of length of the tube and which extends through the U-shaped intermediate piece as far as into the interior of the tube, whilst the end of the supply pipe located inside the tube and the portion of the supply pipe located in the expansion chamber are provided with an opening.
17. A burner as claimed in claim 16 wherein a perforated partition is provided between the grooves forming flow channels and the opening of the supply pipe located in the expansion chamber bounded by the tube.
18. A burner as claimed in claim 17 wherein the U-shaped intermediate piece comprises two apertured plates forming partitions, which extend from the limbs of the intermediate piece obliquely upwards up to the flattened tube portion, whilst the ends of the plates located near the flattened tube portion are interconnected by a plate engaging the flattened portion, whereas the ends remote from the flattened portion are integral with plates extending along the limbs of the intermediate piece up to the web between the two limbs.
19. A method of manufacturing a burner wherein a tube having at least one outlet port is engaged by a sleeve having an elongated slot, the sleeve and the tube being formed, and the sleeve being slipped onto the tube, so that the parts bounding the elongated slot intimately engage the tube and an intermediate piece interconnecting the said two parts is located at a distance from the tube and opposite that part of the tube in which the outlet port is provided, whilst between the said two parts and the opposite parts of the tube grooves are provided forming a communication between the space between the intermediate piece of the sleeve and the tube and the edges of the elongated slot.
20. A method as claimed in claim 19 wherein, before insertion of the tube into the sleeve, partly circular indents are made at regular intervals in the tube, and a longitudinal groove is also made therein.
21. A method as claimed in claim 20 wherein in the longitudinal groove one or more openings are made in the tube wall.
22. A method as claimed in claim 19 wherein, at the area of the smaller outlet ports the wall thickness of the tube is reduced for providing said ports.
23. A method as claimed in any of claims 18 to 22 wherein at least one end of the tube is closed by pinching it.
24. A method as claimed in claim 19 wherein, before the insertion of the tube into the sleeve, the sleeve parts engaging the tube are provided with grooves or depressions.
25. A method as claimed in claim 19 wherein, before the insertion of the tube, the intermediate piece inter-connecting the two sleeve parts engaging the tube is bent over relatively to the sleeve parts.
26. A method as claimed in claim 19 wherein, before application of the sleeve, the part of the tube located opposite the intermediate piece of the sleeve has secured to it a plate to establish a gas supply connection.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|FR1305269A *||Title not available|
|GB1148943A *||Title not available|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US3796535 *||Apr 25, 1972||Mar 12, 1974||Sourdillon Matricage Robinette||Gas burners, especially for domestic appliances|
|US4610063 *||Apr 3, 1985||Sep 9, 1986||Val Products, Inc.||Method for fabricating a watering system for fowl|
|US4723907 *||Jan 15, 1986||Feb 9, 1988||Furigas (Uk) Limited||Atmospheric gas burner|
|US5322224 *||Jul 7, 1993||Jun 21, 1994||Ruiz Edward F||Uniform gas flow linear burner|
|US7901376||Jul 5, 2007||Mar 8, 2011||Baxter International Inc.||Dialysis cassette having multiple outlet valve|
|US8613269 *||Mar 23, 2012||Dec 24, 2013||Pavel Shehter||Internal combustion engine with direct air injection|
|US20090012460 *||Jul 5, 2007||Jan 8, 2009||Baxter International Inc.||Dialysis cassette having multiple outlet valve|
|US20120285415 *||Mar 23, 2012||Nov 15, 2012||Pavel Shehter||Internal combustion engine with direct air injection|
|WO2001015827A1 *||Aug 23, 2000||Mar 8, 2001||Felss Geb||Device and method for forming a recess in a workpiece|
|U.S. Classification||431/349, 29/890.2, 239/554, 29/455.1|
|International Classification||B21D31/00, F23D14/46, B21D31/02, B21D17/02, B21D17/00|
|Cooperative Classification||B21D17/00, B21D31/02, B21D17/02, F23D14/46|
|European Classification||B21D17/00, B21D31/02, B21D17/02, F23D14/46|