IES83750Y1 - A method of manufacturing a wrap-around back boiler - Google Patents

Abstract

ABSTRACT An enclosure sheet (30) is bent and provided with openings (363738) for communication between maintanks of which the enclosure sheet (30) forms front and auxillary links (20,2l,22). It is also provided with slots (35) to receive tabs (34) on the tanks (20,2l,22). The tanks (20,2l,22) are mounted on the enclosure sheet (30) and welded. This accurate placement allows the use of automatic welding.

Description

The present invention relates to a wrap-around back boilers for domestic fireplaces.

Such a wrap-around back boiler comprises generally a main rear tank having spaced- apart enclosure and rear sides, and bottom and top sides bridging the enclosure and rear sides; a pair of outwardly directed main side tanks connected to the rear tank and defining therewith a channel-shaped firebed and flue enclosure, each main side tank having spaced-apart enclosure and rear sides and bottom, top and front sides bridging the enclosure and rear sides; a plurality of auxiliary tanks connected to and contacting an enclosure side of at least one of the main tanks and extending into the enclosure; a removable or movable front bridging member extending between at least two of the additional tanks in close proximity thereto; and the main tanks, additional tanks and front bridging member together defining a tortuous flue gas passageway which extends from an inlet adjacent a firebed to a discharge outlet leading to an exhaust flue, which passageway often includes at least three interconnected rising and falling legs.

Such wrap-around back boilers are, for example, described in UK Patent No. 2151014 (Stephen William Grant), the patentee of which is the inventor of the present application. These wrap-around back boilers were used extensively for hot water supply systems and in central heating systems in the past. However, their use for central heating systems had gradually been superseded over the years but now these wrap-around back boilers are becoming increasingly popular. They are becoming very popular in smaller apartments and houses, either as stand alone units or for use in conjunction with central heating systems, in the sense that many people wish to still have an open fire but appreciate that they do not need all the heat given out by the fire to heat the room.

Originally, fuel conservation and the relatively high cost of fuel led to the concentration by designers on improving the thermal efficiency of such wrap-around back boilers. This, for example, was the reason why the back boiler, as described in asset British Patent Specification Nos. 2151014 and 2167169was exceedingly popular.

The particular back boiler of British Patent No. 2151014 is exceedingly efficient in use and can be relatively easily cleaned. However, while it’s popularity has increased, the complexity of the back boiler has made it relatively expensive to manufacture. This has become particularly the case since there is a considerable amount of welding required in the production of a wrap around back boiler of the type hereinbefore described. The construction is such that it does not lend to any automatic welding operation since the manner in which it is constructed is such that tolerances of manufacture are relatively large and thus do not allow the use of automatic welding and the’ like. Further, because of the particular construction of back boiler, they can only be welded, even manually, by the use firstly of tack welding and then subsequent, by welding in a very constricted space, all of which is both time consuming and difficult. Further, the actual construction of the boiler is such that it is a very difficult task to weld the boiler manually. This would not be any difficulty whatsoever if automatic welding could be used. However, if automatic welding is to be used, then much more accurate methods of constructing the boiler need to be provided. It would probably be possible to provide very elaborate and intricate jigs and fixtures to allow the welding of the boiler, however, the cost of such jigs and fixtures would be such as to render the operation uneconomic.

The present invention is directed towards overcoming some of these problems.

S.ta1emen.ts_of_Ln:Len1i.o.n According to the invention, there is provided a method of manufacturing a wrap- around back boiler of the type comprising: a main rear tank having a spaced-apart enclosure and rear sides, and bottom and top sides bridging the enclosure and rear sides; a pair of outwardly directed main side tanks connected to the rear tank and defining therewith a channel-shaped firebed and flue enclosure, each main side tank having spaced-apart enclosure and rear sides and bottom, top and front sides bridging the enclosure and rear sides; a plurality of auxiliary tanks connected to and contacting an enclosure side of at least one of the main tanks and extending into the enclosure; a removable or movable front bridging member extending between at least two of the additional tanks in close proximity thereto; and . the main tanks, additional tanks and front bridging member together defining a tortuous flue gas passagewaywhich extends from an inlet adjacent a firebed to a discharge outlet leading to an exhaust flue, and which includes at least three interconnected rising and falling legs; the method comprising the steps, not necessarily sequentially of: cutting an enclosure sheet to form at least the enclosure sides of the main tanks; cutting openings in the enclosure sheet for communication between the auxiliary and main tanks; cutting short through slots in the enclosure sheet where the auxiliary tanks contact the enclosure sides; forming auxiliary tanks as sub-assemblies with an opening where ‘rt connects with one of the main tanks, each auxiliary tank being formed with protruding tabs around the periphery of the opening for engagement within respective slots in the enclosure sheet; forming the main tanks by bending the enclosure sheet and welding it to at least one other main tank sheet; offering up the auxiliary tanks to the main tanks and engaging the tabs within respective slots to assemble the boiler; and welding between the contacting surfaces of the auxiliary tanks and the enclosure sheet.

This is a very efficient way of setting up the boiler for welding with automatic welding. it is possible to accurately position all the parts of the boiler. in one way of carrying out the invention, when an auxiliary bridging tank is connected between the main side tanks and spaced-apart from the main rear tank, the method comprises: forming the auxiliary bridging tank with openings at both ends for connection to each main side tank and forming a protruding tab at only a distal end thereof; cutting a receiving hole in the enclosure sheet for reception of the auxiliary bridging tank; and on constructing the main tanks, inserting the distal end of the auxiliary bridging tank through the receiving hole in the enclosure sheet, after the enclosure sheet has been bent and before at least the main side tank rear side is placed in position to engage the distal end with the enclosure sheet by means of the tab and the proximal end by the side edges of the receiving hole.

This accommodates quite considerable changes in dimensions of the auxiliary bridging tank, without disturbing the accuracy of positioning. in another embodiment of the invention, there is formed a pair of spaced-apart tabs and the slot is formed as an open slot in the periphery of a hole cut in the enclosure sheet.

In this latter way of carrying out the invention, the enclosure sheet may additionally be bent to form the front sides of each main side tank. in one way of carrying out the invention, there are three main tank sheets, two sheets being bent to form the rear, bottom and top sides of each main side tank and the other sheet being bent to form the rear, bottom and top side of the main rear tank. in the method according to the present invention, on engaging the tabs within respective slots, each tank is tack welded in position and when the boiler is fully assembled, an automatic welding apparatus is used to weld the boiler. in another method according to the invention, grate mounting ledges are secured to the enclosure sheet prior to forming the main tanks.

Finally, theinvention provides a boiler manufactured in accordance with the method.

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The invention will be more clearly understood from the following description of a method of carrying out the invention, given by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of a wrap-around back boiler manufactured in accordance with the method of the invention, Fig. 2 is a perspective partially cut-away view of the boiler of Fig. 1 with -portion of the boiler removed, Fig. 3 is a front partially sectional view of the boiler, Fig. 4 is a side partially sectional view of the boiler, and Fig. 5 is an exploded sectional view of various sheets of metal forming part of the boiler which illustrate the method.

Referring to the drawings and initially to Figs. 1 to 4 thereof, there is illustrated a wrap-around back boiler, indicated generally by the reference numeral 1. The wrap- around back boiler 1 comprises a main rear tank 2 and a pair of outwardly directed main side tanks 3 which form extension of the rear tank 2. The main rear tank 2 has spaced-apart enclosure sides 4 and rear sides 5, top side 6 and bottom side 8 (see Fig. 4). Each main side tank 3 has spaced-apart enclosure sides 10, rear sides 11, bottom side 12, top side 13 and front side 14. A removable front plate 15 defines a combustion gas flue enclosure and a lower portion forms a firebed enclosure mounting a standard grate 16 supported on mounting lugs 17. There is a plurality of auxiliary tanks connected to and contacting an enclosure side of at least one of the main tanks and extending into the enclosure. in this embodiment, there is an upper auxiliary central tank 20, side auxiliary tank 21 and an auxiliary bridging tank 22. A damper 25 is also illustrated.

While the operation of the boiler, in accordance with the invention, does not form part of this invention, it will be seen from Figs. 3 and 4, how, in use, when a fire is lit on the grate 16, the combustion gases pass through the various gas passageways, defined by the main rear tank 2, main side tank 3 and auxiliary tanks 20, 21 and 22.

These are shown by the arrows in Figs. 2, 3 and 4.

Referring now to Fig. 4, there is illustrated an enclosure sheet, indicated generally by the reference numeral 30, which is already shown partly bent to form the enclosure sides of the main tanks, namely, sides 4 and 10, as well as the front side 14. There is also illustrated three main tank sheets, namely, main side tank forming sheets 31 and a main rear tank forming sheet 32. There is also illustrated the auxiliary tanks , 21 and 22, almost fully assembled. A door retaining plate 18 is also provided but only shown in Fig. 5. it will be noted that each auxiliary side tank 20 and 21 are shown as formed as sub- assemblies, each having an opening 33, while the auxiliary bridging tank 22 has two openings 32, only one of which is shown. The openings 32 are used for communication with the main tanks. Each of the auxiliary tanks 20, 21 and 22 is formed with protruding tabs 34 for engagement within slots 35 and 36 in the enclosure sheet 30. The slots 36 are longer than the slots 35 with respect to the tabs 34 to facilitate inter-engagement. it will also be noted that the enclosure sheet 30 has holes 37 for communication with the respective auxiliary tanks 20 and 21. There are holes 38 for engagement with the auxiliary bridging tank 22 which are larger than the other holes 37. One of the holes 38 has open slots 39 for reception of tabs 34 on the auxiliary bridging tank 22. The hole 38 is made to allow the auxiliary bridging tank 22 to be slid therein.

It does not require any description to explain how the enclosure sheet 30 can be cut and bent to form the enclosure sides 10 and the front side 14. Similarly, each of the sheets 31 can be bent to form the rear side 5, bottom side 8 and top side 6 of each main side tank 3 and the sheet 32, as can be easily seen, can be bent to form the rear bottom side 8 and top side 6 of the main rear tank 2.

To assemble the boiler prior to welding, the tank 20 is offered up to the enclosure sheet 30 and will be secured thereto by the tabs 34 engaging the slots 35. The tanks 21 are then placed in position. The relatively long slots 36 allow the tanks 21 to be manipulated into position. Then the auxiliary bridging tank 22 is slid, with its proximal end, through the hole 38 to engage against the hole 37 with the tabs 34 retaining the proximal end of the auxiliary bridging tank 22 in position, while the distal end is mounted within the hole 38. As each part is inserted into position, it is preferably tack welded but only shown in Fig. 5. Then, the door retaining plate 18 and sheets 31 and 32 are tack welded in position and then the auxiliary tanks 20, 21 and are tack welded into position. However, it will be appreciated that with this construction, it is possible to use automatic welding and other similar techniques. It will also be appreciated that all the other parts of the boiler may be welded in position during some stage of the operation.

In the specification the terms “comprise, comprises, comprised and comprising" or any variation thereof and the terms “include, includes, included and including” or any variation thereof are considered to be totally interchangeable and they should all be afforded the widest possible interpretation and vice versa.

The invention is not limited to the embodiment hereinbefore described, but may be varied in both construction and detail within the scope of the appended claims.

Claims (4)

1. A method of manufacturing a wrap-around back boiler of the type comprising: a main rear tank having a spaced-apart enclosure and rear sides, and bottom and top sides bridging the enclosure and rear sides; a pair of outwardly directed main side tanks connected to the rear tank and defining therewith a channel-shaped firebed and flue enclosure, each main side tank having spaced-apart enclosure and rear sides and bottom, top and front sides bridging the enclosure and rear sides; a plurality of auxiliary tanks connected to and contacting an enclosure side of at least one of the main tanks and extending into the enclosure; a removable or movable front bridging member extending between at least two of the additional tanks in close proximity thereto; and the main tanks, additional tanks and front bridging member together defining a tortuous flue gas passageway which extends from an inlet adjacent a firebed to a discharge outlet leading to an exhaust flue, and which includes at least three interconnected rising and falling legs; the method comprising the steps, not necessarily sequentially of: cutting an enclosure sheet to form at least the enclosure sides of the main tanks; ‘ cutting openings in the enclosure sheet for communication between the auxiliary and main tanks; cutting short through slots in the enclosure sheet where the auxiliary tanks contact the enclosure sides; forming auxiliary tanks as sub-assemblies with an opening where it connects with one of the main tanks, each auxiliary tank being formed with protruding tabs around the periphery of the opening for engagement within respective slots in the enclosure sheet; forming the main tanks by bending the enclosure sheet and welding it to at least one other main tank sheet; offering up the auxiliary tanks to the main tanks and engaging the tabs within respective slots to assemble the boiler; and in which one of the auxiliary tanks is an auxiliary bridging tank connected between the main side tanks and spaced-apart from the main rear tank, the method further comprising:

2. forming the auxiliary bridging tank with openings at both ends for connection to each main side tank and forming a pair of spaced-apart protruding tabs at only a distal end thereof; cutting a receiving hole in the enclosure sheet for reception of the auxiliary bridging tank and an open slot in the periphery of the hole to receive each tab; and on constructing the main tanks, inserting the distal end of the auxiliary bridging tank through the receiving hole in the enclosure sheet, after the enclosure sheet has been bent and before at least the main side tank rear side is placed in position to engage the distal end with the enclosure sheet by means of the tab and the proximal end by the side edges of the receiving hole; and welding between the contacting surfaces of the auxiliary tanks and the enclosure sheet. A method as claimed in claim 1, in which: 20 the enclosure sheet is cut and bent to form at least the enclosure sides; the auxiliary tanks are placed in position; the auxiliary tanks are welded to the enclosure sheet; and the remainder of the boiler is formed.

3. A method as claimed in claim 1 or 2, in which there are three main tank sheets, two sheets being bent to form the rear, bottom and top sides of each main side tank and the other sheet being bent to form the rear, bottom and top side of the main rear tank.

4. A method substantially as described herein with reference to