Method for manufacturing a burner gas manifold and an improved manifold thus obtained

Abstract

A method for manufacturing a burner gas manifold (1), said manifold (1) comprising a tubular body (2) in which there is present at least one partitioning member (23) which partitions the internal cavity (9) of the manifold into a plurality of chambers (24, 25) where the gas is delivered through corresponding ducts (17). Such partitioning member (23) is introduced into the manifold by a slot (22) provided for in a wall (6) of the tubular body (2) and it is welded to the manifold (1) for example by laser welding. A manifold thus made is also claimed herein.

Description

[0001] METHOD FOR MANUFACTURING A BURNER GAS MANIFOLD AND AN IMPROVED MANIFOLD THUS OBTAINED

[0002] The present invention relates to a method for manufacturing a gas burner gas manifold, and a manifold thus made .

[0003] As known, a burner gas manifold is a component for a product ( for example a gas boiler ) through which the gas is distributed to various noz zles of the burner .

[0004] Such manifold may take various shapes , such as for example a tubular shape (with circular or polygonal cros ssection ) , and it internally comprises a longitudinal chamber which receives gas from at least one duct fixed out side the body of the manifold . Noz zles which allow the gas present in the chamber of the manifold to reach various element s of the burner at which the flame is generated, for example burner plates , are connected in such chamber .

[0005] The noz zles are usually spaced apart consistently ( for example 17 mm) , a distance usually present even between the burner plates ( or similar element s ) .

[0006] In order to split the use of the burner and allow the use of only some of such burner plates to generate the flame when needed and desired, it is known to partition the chamber of the manifold into a plurality of part s ( each of which receives gas from a duct thereof ) for example by using one or more partitioning septa or baf fles arranged in such chamber . This allows to solely convey the gas into a section or portion of the chamber of the manifold and therefore solely supply part of the noz zles of the burner ; this is done (by a burner control member ) so as to have a low-power operation of the burner when the user select s a particular temperature , for example to have specific temperature conditions required in an environment heated through a heating system having a boiler with a split-type burner or have a specific temperature of the water heated by a hot water heater provided with such burner .

[0007] In order to partition the chamber of the manifold into two or more part s ( into two part s in the example below) , it is known to insert a partitioning septum or baf fle into the manifold at an open end thereof (before arranging corresponding bracket s which close them and which allow to support the manifold at the two ends of the manifold) . Such insertion is carried out using an appropriate manipulator . The partitioning septum or baf fle is therefore braze-welded to the manifold .

[0008] Such operation reveals numerous drawbacks . First and foremost , the manipulator which introduces the part itioning septum must have a specific conformation so as to obtain a correct movement of the septum of the chamber of the manifold so as to prevent the j amming thereof or an incorrect arrangement in such chamber .

[0009] In addition, the braze-welding operation could result in the spreading of the material used for the welding in the chamber pos sibly af fecting the holes designed for the noz zles and the resulting dif ficulty in arranging the noz zles in the appropriate desired manner .

[0010] Besides this , braze-welding is an energy consuming proces s given that it requires using a furnace (usually gas- heated) adapted to bring the material used for braze-welding to high temperatures ( around 1000 ° C ) . Such furnace operates continuously and even when it is not operative ( for example because it is undergoing maintenance ) it should be kept at a minimum temperature so as to avoid long heating procedures when starting it .

[0011] All this leads to a high consumption of energy and gas . Furthermore , the furnaces mentioned above are tunnel furnaces which occupy a significantly large area in a factory where the manifolds are produced . Besides this , there also arises an inherent dif ficulty in braze-welding because it should be carried out in a protected atmosphere that is non- oxidative and therefore by using facilities and gases that af fect the operating cost s .

[0012] Lastly, such furnaces require significant maintenance of the internal systems for moving the pieces being proces sed and a large number of workpieces must be used for brazewelding, also for the reasons mentioned above . Therefore , it is important to provide for a painstaking, yet expensive , management of said furnaces .

[0013] An ob j ect of the present invent ion is to provide a method for manufacturing burner gas manifolds which is improved with respect to the prior art manufacturing methods .

[0014] In particular, an ob j ect of the invention is to provide a method of the type mentioned above whose implementation has significantly lower cost s compared to the welding operating cost s currently envisaged for manufacturing gas manifolds .

[0015] Another ob j ect of the present invention is to provide a method of the type mentioned above that allows to produce any number of manifolds without repercus sions at economic level and without the need for facilities that occupy significant space in a manufacturing plant .

[0016] A further ob j ect is to provide a method of the type mentioned above which allows to obtain gas manifolds for supplying burners in which the flame can be generated automatically also at three sections of the burner .

[0017] A further ob j ect of the present invention is to provide a burner gas manifold that is more cost-ef fective compared to the current manifolds obtained using the braze-welding method and wherein the noz zles can be approached to each other so as to allow to provide combustion chambers for corresponding gas burners that are very compact .

[0018] These and other ob j ect s which shall be more apparent to the person skilled in the art are attained by a method for manufacturing a gas manifold and a manifold thus obtained according to the corresponding attached claims .

[0019] For a better understanding of the present invention, the following drawings are attached hereto, purely by way of non-limiting example , wherein : figure 1 shows a gas manifold according to the invention in exploded view; figure 2 shows the gas manifold of figure 1 as sembled; figure 3 shows a cros s-sectional view according to line 3-3 of figure 2 with a part of the manifold shown in exploded view; figure 4 shows a cros s-sectional view according to line 3-3 of figure 2 ; figure 5 shows a sectional view according to line 5-5 of figure 1 ; and figure 6 shows a view of figure 5 from the left side .

[0020] With reference to the figures mentioned above , a gas manifold according to the invention is generally indicated with 1 . It compri ses a tubular body 2 , with polygonal cros ssection in the case shown, having two opposite ends 3 and 4 and walls 5 , 6 , 7 and 8 delimiting an internal cavity 9 . A plurality of first through holes 10 for corresponding noz zles 11 which are connected to the tubular body 2 of the manifold in any known manner and which trans fer the gas from the gas manifold to a burner, is provided for in the wall 5 .

[0021] Second through holes 15 adapted to house ends 1 6 of duct s 17 adapted to introduce gas into the manifold 1 are provided for in the wall 6 . Such ends 1 6 of the duct s 17 are fixed to the body 2 of the manifold . Members 1 9 adapted to close the ( open ) ends 3 and 4 mentioned above with a part 20 thereof and having bracket s 21 for fixing to any known support body (not shown ) , are provided for at the ends 3 and 4 of the tubular body 2 .

[0022] Furthermore , a through slot 22 ( arranged with longitudinal axis K lying on a plane orthogonal to the longitudinal axis W of the tubular body 2 ) which, preferably, reaches the adj acent walls 5 and 6 is provided for in the wall 6 . Such slot 22 is adapted to house , pas sing through, a partitioning member 23 adapted to partition the cavity ( or chamber ) 9 of the manifold into two part s 24 and 25 into each of which a corresponding hole 15 , and therefore a duct 17 , opens .

[0023] A reces s ( respectively 305 , 307 , 308 ) is provided for at the through slot or opening 22 , in the walls 5 , 7 and 8 ; such reces ses define a seat 30 for the partitioning member 23 into which the latter is slidably inserted penetrating into the cavity or chamber 9 of the tubular body 2 through the slot 22 .

[0024] Such insertion is carried out when implementing the method according to the invention which, in a first step, specifically provides for creating said slot 22 in the wall 6, the slot having ends 65 , 67 close to the walls 5 and 7 of the tubular body 2 .

[0025] Therefore , the reces ses 305 , 307 and 308 are created, that is the seat 30 for the partitioning member 23 is provided . These reces ses are required for the gas sealing close to the partitioning member . However, they may also not be present should such sealing be achieved due to appropriate internal tolerances of the tubular body 2 .

[0026] Obviously, the slot 22 and said seat 30 are provided as a function of the dimensions of such partitioning member 23 and in a position in the tubular body 2 such to def ine the part s 24 and 25 with desired axial length ( along the longitudinal axis W of the tubular body 2 ) as a function of the desired splitting for generating the flame by the burner .

[0027] Thus done , the partitioning member is introduced into the slot 22 by sliding it in the reces ses 305 and 307 until it reaches the reces s 308 . At this point , the partitioning member 23 is fixed, that is welded to the tubular body 2 . Such fixing or welding is carried out through an autogenous fusion welding, such as a laser welding, arc welding or through any other method falling within said definition (plasma, TIG, MIG or MAG welding) .

[0028] For instance , for example considering that such autogenous fusion welding is carried out using a laser, the laser welding operation is carried out "by transparency" at the sides 5 , 7 and 8 that is by penetrating the laser beam from out side the tubular body 2 according to a butt joint on the side 6 . This causes a localised melting of the (metal ) material with which such body is made and the immediate cooling thereof . This fixes the partitioning member 23 in the seat 30 .

[0029] The above (that is the action of the laser ) also result s in the melting of the peripheral part s of the partitioning member 23 in the seat 30 , a melt ing which is followed by a cooling of such material which is bound to that of the tubular body 2 in the cooling step . This result s in the laser welding fixing of the partitioning member in the seat 30 .

[0030] A subsequent pas s through of the laser along the edges of the slot 22 on the wall 6 and at it s ends 65 and 67 result s in the localised melting of the material s of the partitioning member and of the tubular body 9 and the closure of such slot obtaining a butt j oint welding .

[0031] Obviously, the materials of such tubular body 2 and of the partitioning member 23 are the same ( for example steel ) or they are compatible to have their intimate melting .

[0032] The laser used for the welding (by penetration or transparency) is for example a fibre laser .

[0033] The advantage of laser welding lies in the fact that only the areas to be melted, and therefore welded, are heated; this avoids any subsequent erroneous positioning of the tubular body 2 , therefore avoiding any deformation of the tubular body . Furthermore , through locali sed laser welding, no molten materials spread along the wall 5 of the tubular body 2 preventing the molten material from penetrating into the holes 10 closest to the welding area at least partially occluding them ( like it may happen in brazewelding) .

[0034] Specifically due to the accuracy and precision of laser welding and given that there is no dispersion of molten material along the wall 5 of the tubular body 2 , the holes 10 may be approached to the seat 30 for the partitioning member 23 . This allows to provide for a spacing between the holes 10 smaller than the usual 17 mm of the prior art solutions , up to 10 mm . This result s in the pos s ibility of reducing the length of the manifold 1 along it s longitudinal axis W and the pos sibility of having a longitudinally compact burner, which is more compact than a burner containing a septum fixed therein for braze-welding .

[0035] Furthermore , having the option of approaching the noz zles also allows to arrange multiple partitioning members in the tubular body 2 and creating, for example , three part s of the cavity or chamber of the manifold 9 ; this allows to have a further option of splitting the operation of the burner .

[0036] The method for manufacturing a gas manifold as described allows to provide a method that is much les s energy consuming than the braze-welding proces s of the prior art for partitioning the cavity or chamber of the manifold into at least two part s 24 and 25 . Furthermore , the invention does not need the pre-heating of the prior art laser device which carries out the welding, just like such device does not occupy the spaces of a braze-welding furnace , to the benefit of the dimensions of the manufacturing plant .

[0037] Lastly, using the method according to the invention, gas manifolds can be produced in limited numbers to be used, for example , for manufacturing samples .

[0038] A preferred embodiment of the invention where the inventive method is carried out using a laser has been described . However, as shown, also other autogenous fusion welding methods known to the person skilled in the art , such as gas , electric arc, plasma, TIG, MIG and MAG welding can be used .

[0039] Furthermore , in the light of the description, other solutions ( like the one where the slot 22 is obtained in a wall of the tubular body 2 other than the wall 6 ) which still fall within the scope of protection of the invention as defined by the claims that follow may be obtained in any case .

Claims

CLAIMS1. A method for manufacturing a gas manifold for a burner, said gas manifold (1) having a tubular body (2) provided with walls (5, 6, 7, 8) , a first wall (5) being provided with a plurality of first through holes (10) for corresponding nozzles (11) of the burner, in a second wall (6) there being provided for second through holes (15) for ducts (17) for introducing gas into a cavity (9) inside the tubular body (2) of the gas manifold where the first through holes (10) for the nozzles (11) of the burner also open, said internal cavity (9) being partitioned into at least two parts (24, 25) , characterised in that it provides for: a) creating at least one through slot (22) in a wall (6) of the walls (5, 6, 7, 8) of the tubular body (2) of the gas manifold, b) inserting a partitioning member (23) into such through slot (22) so that said partitioning member partitions the internal cavity (9) of the tubular body (2) of the gas manifold into the two parts (24, 25) , c) carrying out an autogenous fusion welding of such partitioning member (23) to the walls (5, 6, 7, 8) of the internal cavity (9) of the tubular body (2) of the gas manifold mentioned above, d) carrying out an autogenous fusion welding of such partitioning member (23) along the through slot (22) mentioned above, said autogenous fusion weldings being alternatively a laser, electric arc, gas, TIG, MIG, MAG or plasma welding.

2. The method according to claim 1, characterised in that a recess (305, 307, 308) adapted to house the partitioning member (23) is provided for inside the cavity (9) of the tubular body (2) of the gas manifold in at least one of the walls (5, 7, 8) other than the wall in which thethrough slot (22) is provided, the partitioning member (23) being slidably inserted into said at least one recess and a through slot being welded therein.

3. The method according to claim 2, characterised in that a recess (305, 307, 308) is provided for in each wall (5, 7, 8) delimiting the recess (9) at the through slot (22) , each recess (305, 307, 308) defining a seat (30) for said partitioning member (23) and in which such partitioning member is welded.

4. The method according to claim 1, characterised in that said through slot (22) has a longitudinal axis (K) lying on a plane perpendicular to a longitudinal axis (W) of the tubular body (2) of the gas manifold.

5. The method according to claim 1, characterised in that there is provided for associating the nozzles (11) of the burner with the through holes (10) of the tubular body (2) of the gas manifold maintaining such nozzles of the burner at a distance equal to or greater than 10 mm.

6. A burner gas manifold comprising a tubular body (2) of the gas manifold having an internal cavity (9) having a longitudinal axis (W) , said tubular body (2) having walls (5, 6, 7, 8) , in a first (5) of such walls (5, 6, 7, 8) there being provided for a plurality of first holes (10) for nozzles (11) of the burner, in a second wall (6) there being provided for a plurality of second walls (15) for connecting the ducts (17) adapted to deliver gas to the internal cavity (9) mentioned above where the nozzles (11) of the burner also open, said internal unit being partitioned into at least two parts (24, 25) , in said internal cavity there being provided for a partitioning member (23) adapted to partition such internal cavity (9) into said two parts (24, 25) , characterised in that a wall (6) of said walls (5, 6, 7, 8) of the tubular body (2) has a through slot (22) which isadapted to house said partitioning member (23) , said partitioning member being welded to the walls (5, 6, 7, 8) of the tubular body (2) of the gas manifold through autogenous fusion welding, said welding being alternatively a laser or electric arc, gas, plasma, TIG, MIG or MAG welding .

7. The gas manifold according to claim 6, characterised in that said partitioning member (23) is welded along said through slot (22) .

8. The gas manifold according to claim 6, characterised in that a recess (305, 307, 308) is provided for inside the internal cavity (9) in each wall (5, 7, 8) which delimits such cavity other than the one provided with the through slot (22) , each recess (305, 307, 308) defining a seat (30) for said partitioning member and in which said partitioning member is welded through autogenous fusion welding.

9. The gas manifold according to claim 6, characterised in that the nozzles (11) of the burner are spaced apart from each other by a distance equal to or greater than 10 mm.

Images