IE20060730A1 - A method of manufacturing a boiler shell - Google Patents

Abstract

A method of robotically welding a boiler shell for an enclosed boiler having at least one water carrying interior tank requiring stiffening is disclosed. the method includes providing a jig having a rectangular framework and a clamping means to hold the component parts of a boiler being manufactured rigidly and in proper relation to one another in the jig. the present invention ensures that the interior tank and other component parts of the boiler shell are hold in their correct position during delivery to the robotic welding machine, and during robotic welding. <Figure 1>

Description

"A Method of Manufacturing a Boiler Shell" 060730 Introduction h:»TCl_^S2^L·. ί -F2^M v 1°/ ^.

The present invention relates to a method of robotically welding a boiler shell for an enclosed boiler having at least one a water carrying interior tank requiring stiffening.

The manufacture of boiler shells for enclosed boilers typically requires initially forming the separate component parts of the boiler shell and then manually positioning and welding the component parts together to form the boiler shell. An example of such a boiler shell is disclosed in EP0616676B (Alley Enterprises Limited), see in particular Figs. 11, which boiler shell is shown to comprise hollow walls and an interior tank for carrying water to be heated.

It will however be appreciated that the formation of such boiler shells from component parts is an extremely time consuming and intensive process as operatives are required to manually hold each separate component in its correct relative position and then weld the surfaces of the components to form the boiler. The throughput of boiler shells formed according to this process is generally quite low.

One approach to increasing the throughput of boiler shells, and overcoming the above problems, is use a robotic welding machine to efficiently weld the components of the boiler shell together. However, in order for such machines to operate correctly it is essential that the component parts of the boiler shell are initially accurately aligned and spot welded prior to delivery to the robotic welding machine as any misalignments will result in the machine failing to correctly weld the boiler shell. Additionally, the further problem of water leakage from the water carrying structures of the boiler shell may also arise in such circumstances.

However, even once tack welded it is common for the internal components, and in particular, the interior tank in the boiler shell, to move on delivery to the robotic welding machine and indeed during the robotic welding process. This again will result in the robotic welding machine failing to correctly weld the boiler shell. 060730 -2It is a therefore one object of the present invention to provide a method of robotically welding a boiler shell for an enclosed boiler which goes someway toward overcoming at least the above problems, and/or which will provide the public and/or industry with a useful choice.

It is acknowledged that the term ‘comprise’ may, under varying jurisdictions be provided with either an exclusive or inclusive meaning. For the purpose of this specification, and unless otherwise noted explicitly, the term comprise shall have an inclusive meaning - i.e. that it may be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components. Accordingly, the term ‘comprise’ is to be attributed with as broader interpretation as possible within any given jurisdiction and this rationale should also be used when the terms ‘comprised’ and/or ‘comprising’ are used.

Further aspects of the present invention will become apparent form the ensuing description which is given by way of example only.

Statements of Invention According to the invention, there is provided a method of robotically welding a boiler shell for an enclosed boiler having at least one a water carrying interior tank requiring stiffening, the method including providing a jig having: a substantially rectangular framework having a top wall and a base wall spaced apart by a front wall, a back wall and two side walls, in which at least one of the framework walls is able to be moved to enable separate component parts for the boiler shell to be placed in the jig and the assembled boiler shell to be removed from the jig; clamping means to hold the parts rigidly and in a proper relation to one another in the jig, whereby at least one of the framework walls has a plurality of through bores through which a connection means is passed to connect at least some of the parts together to assemble the 060730 -3boiler shell for robotically welding on removal from the jig, the method comprising the steps, not necessarily sequentially, of: (i) cutting an exterior enclosure sheet to form at least a rear exterior wall and side exterior walls of the boiler shell, and cutting an interior enclosure sheet to form at least a rear interior wall and side interior walls of the boiler shell, in which mounting ledges are formed adjacent a peripheral edge of each side interior wall; (ii) cutting a plurality of openings in the rear wall of the interior enclosure sheet where a water carrying interior tank is to contact the interior enclosure sheet; (iii) arranging the interior sheet relative to the exterior sheet in the jig to form a U-shaped channel having two hollow side walls spaced apart by a hollow rear wall for carrying water to be heated; (iv) forming two tank side plates, a tank base plate and a substantially L-shaped tank front plate, the tank side plates and tank base plate each having a pair of facing surfaces bounded by upper, lower and side peripheral edges, and the tank front plate having side facing peripheral edges, and in which a plurality of protruding tabs extend from the peripheral edges of the plates for engagement within the openings in the rear wall of the interior enclosure sheet, the plates then being arranged within the channel so that the peripheral edges of the tank side plates project outwardly of the side facing peripheral edges of the tank front plate to form the interior tank; (v) cutting a burner plate sheet to form a substantially flat rectangular burner plate and an outer burner tray having a I 06073ο -4rectangular base with upstanding side walls, and then cutting a through bore in a facing surface of the burner plate and the burner tray, the diameter of the bore in the outer burner tray being slightly greater than the diameter of the bore in the burner plate, (vi) positioning the burner plate across an open face of the Ushaped channel on the mounting ledges and then placing the outer burner tray on the inner burner plate to form an enclosed cavity there between; (vii) cutting a plurality of socket locating openings in the outer burner plate for communication between upright sockets placed on the outer burner plate and the cavity; (viii) positioning a burner ring in the form a cylindrical sleeve on the burner plate to form, with the bores in the burner plate and outer burner tray, an inlet for flames; (ix) cutting a baffle assembly mounting sheet to form a plurality of baffle assembly support plates, and then positioning each baffle assembly support plate formed within the U-shaped channel where baffle plate assemblies are to be supported within assembled the boiler shell; (x) moving at least one framework wall of the jig to enable the clamping means to engage with and hold the parts of the boiler shell positioned in the jig rigidly and in a proper relation to one another; (xi) passing the connection means though the bores in each framework wall to connect at least some of the contacting surfaces of the parts in the jig, and 060730 -5(xii) removing the assembled boiler shell from the jig and delivering to a welding station to be robotically welded; and wherein, subsequent to step (iv) and prior to step (xii), the additional steps are performed of: (xiii) forming a plurality of alignment and stiffening members, each member having at least one protruding tab extending from a proximal end and a distal end thereof, and (xiv) engaging each tab within one of a respective notch formed in the outwardly projecting peripheral edge of one of the tank side plates and a respective enclosed slot formed in the interior side wall so that each member extends between the interior tank and an interior side wall to stiffen the interior tank, whereby on removal of the boiler shell from the jig there is minimum relative movement of the boiler shell parts.

The present invention provides numerous advantages over prior art methods of forming boiler shells. In particular, the provision and placement of alignment and stiffening members between the walls of the boiler shell and the interior tank will ensure that the interior tank and other internal components of the boiler shell are held in their correct position during delivery to the robotic welding machine and during robotic welding. Such alignment and stiffening members will also ensure that the boiler shell components will retain there correct position during the robotic welding process.

In another embodiment of the invention, the method further comprises forming means on the jig for indicating which contacting surfaces of the parts in the jig are to be connected by the connection means.

Such a provision will ensure that operatives will be able to quickly identify the surfaces of the boiler shell components which are to be joined. t 060730 -6Preferably the connection means comprises at least one welding torch.

In another embodiment of the invention, the method further comprises mounting the jig framework so that it is able to be rotated.

Such a provision will ensure that the surfaces of the components requiring connecting will be presented to operatives in the most suitable positions for welding.

In another embodiment of the invention, the method further comprises the step of providing the jig with braking means so that the position of the framework can be locked in any desired position when rotated.

In another embodiment of the invention, the method further comprises the step of cutting an opening in the exterior sheet for communication between at least one water inlet socket placed on the exterior sheet and a cavity formed between the exterior and interior enclosure sheets.

Detailed Description of the Invention The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only, with reference to the accompanying drawings, in which: Figs. 1 and 2 are perspective views of a jig used in the formation of a boiler shell according to the invention, and Figs. 3 and 4 are perspective views showing separate component parts of a boiler shell and the progressive steps in the formation of a boiler shell from those parts according to the invention.

With initial reference to Figs. 1 and 2, there is shown a jig, indicated generally by the reference numeral 1, having a substantially rectangular framework, indicated generally by the reference numeral 2, having a top wall 3 and a base wall 4 spaced apart by a front wall 5, a back wall 6 and two side walls 7, 8. 060730 -7At least one of the framework walls 3, 4, 5, 6, 7, 8 is able to be moved to enable the separate component parts (see Figs. 3 and 4) to be placed in the jig 1 and the assembled boiler shell 10 (see Fig. 2) to be removed from the jig 1 when formed.

Also shown is clamping means 11, which holds the component parts rigidly and in a proper relation to one another in the jig 1 when the walls 3, 4, 5, 6, 7, 8 of the jig 1 are closed. In the embodiment shown the clamping means 11 extends from side wall 7, however, it will be appreciated that further clamping means may also be provided on any of the framework walls 3, 4, 5, 6, 7, 8 to engage against the boiler shell components in the jig 1. Clamp 12 is also provided on the jig 1 to tightly secure the jig walls 3, 4, 5, 6, 7, 8 together. At least one of the framework walls 3, 4, 5, 6, 7, 8 has a plurality of through bores 13 formed therein through which a connection means (not shown), such as a welding torch, is passed to connect at least some of the contacting surfaces of the parts in the jig 1 together to assemble the boiler shell 10 for delivery to the a robotic welding machine on removal from the jig 1.

The jig 1 also comprises means (not shown) for indicating which contacting surfaces of the parts in the jig 1 are to be connected by the connection means. In the instance shown, such means are provided by elevated regions or spots (not shown) formed on the walls 3, 4, 5, 6, 7, 8 of the jig 1, as well as on the inner facing surfaces 15 of the through bores 13 formed in the walls 3, 4, 5, 6, 7, 8. Accordingly, operatives will know the specific contacting surfaces of the parts in the jig requiring connecting by the presence of such elevated regions or spots.

The jig framework 2 is mounted so that it is able to be rotated. In the embodiment shown, the jig framework 2 is fixed to an axle 17 which is rotatably mounted to an upright support 16. The jig 1 is also provided with braking means, indicated generally by the reference numeral 18 so that the framework 2 can be locked in any desired position when rotated. In the instance shown, the braking means 18 comprises a cog 19 which is fixed to the axle 17, which cog 19 rotates with the axle 17 on rotation of the jig framework 2. The braking means also comprises a lever arm 20 which is actuated by an operator at its proximal end and terminates in a locking member 21 at its distal end. In use, an operator actuates the lever arm 20 to cause the locking I 060730 -8member 21 to engage between adjacent cog teeth in the cog 19 to in turn lock the rotational position of the framework 2. Appropriate actuation of the lever arm 20 will remove the locking member 21 from the cog 19 to permit rotation of the framework 2.

It will therefore be appreciated that the initial step in the method of the present invention is to provide the jig described above.

Referring now to Figs. 3 and 4, with like parts using the same numeral identification system of Figs. 1 and 2, a boiler shell for an enclosed boiler having at least one a water carrying interior tank requiring stiffening is formed as follows.

In step (a) an exterior enclosure sheet 100 is cut to form at least a rear exterior wall 102 and side exterior walls 104 of the boiler shell 10. At step (b) an interior enclosure sheet 106 is cut to form at least a rear interior wall 108 and side interior walls 110 of the boiler shell 10. Mounting ledges 112 are formed adjacent a peripheral edge of each side interior wall 110 and a plurality of openings 114 are cut in the rear wall 108 of the interior enclosure sheet 106 where a water carrying interior tank is to contact the interior enclosure sheet 106. The interior sheet 106 is then arranged relative to the exterior sheet 100 in the jig (not shown) to form a U-shaped channel, indicated generally by the reference numeral 116, having two hollow side walls 118 spaced apart by a hollow rear wall 120 for carrying water to be heated.

Steps (c), (d), (e) and (f) together show the formation of the interior tank within the Ushaped channel 116. At steps (c) and (d) two tank side plates 122, 124 are formed, in step (e) a tank base plate 126 is formed, and in step (f) a substantially L-shaped tank front plate 128 is formed. The tank side plates 122, 124 and tank base plate 126 each have a pair of facing surfaces bounded by upper, lower and side peripheral edges 130(a)-(d), 131 (a)-(d). Additionally, the tank front plate 128 is formed with side facing peripheral edges 132(a)-132(b).

A plurality of protruding tabs extend from the peripheral edges 130, 131, 132 of the plates 122, 124,126 and 128 for engagement within the openings 114 in the rear wall 108 of the interior enclosure sheet 106. Once formed, the plates 122, 124, 126 and 128 are then arranged within the channel 116 so that the tabs protruding from the t °6O73o -9plates 122, 124, 126 and 128 engage within the openings 114 and the peripheral edges 130 of the tank side plates 122, 124 project outwardly of the side facing peripheral edges 132 of the tank front plate to form the interior tank 134.

At steps (g) and (h) a burner plate sheet (not shown) is cut to form a substantially flat rectangular burner plate 136 and an outer burner tray 138 having a rectangular base 140 with upstanding side walls 142. A through bore 144 is then cut in a facing surface of the burner plate 136. A further through bore 146 is also cut in the outer burner tray base 140 of the burner tray 138, wherein the diameter of the bore 146 in the outer burner tray base 140 is slightly greater than the diameter of the bore 144 in the burner plate 136. The burner plate is then positioned across an open face of the U-shaped channel 116 on the mounting ledges 112 and the outer burner tray 138 is placed on the inner burner plate to form an enclosed water carrying cavity there between. At step (h) a plurality of socket locating openings 148 are also cut in the outer burner plate 138, the openings for communication between upright water inlet sockets 150 placed on the outer burner plate 138 and the cavity, as shown in steps (m) and (n).

At step (i) a burner ring in the form of a cylindrical sleeve 145 is placed on the burner plate to form, with the bores 144, 146 in the burner plate 136 and outer burner tray 138, an inlet for flames.

In step (j), a baffle assembly mounting sheet is cut to form a plurality of baffle assembly support plates 152, each baffle assembly support plate formed being positioned within the U-shaped channel 116 where baffle plate assemblies (not shown) are to be supported within assembled the boiler shell. Additionally, a plurality of alignment and stiffening members 154 are formed, each member 154 having at least one protruding tab 156(a), 156(b) extending from a proximal end and a distal end thereof. Each tab 156(a), 156(b) is then engaged within one of a respective notch formed in the outwardly projecting peripheral edge 130(a) of one of the tank side plates 122, 124 and a respective enclosed slot 158, see step (i), formed in the interior side wall 110 so that each member 154 extends between the interior tank 134 and an interior side wall 110 to stiffen the interior tank 134, whereby on removal of the boiler shell from the jig there is minimum relative movement of the boiler shell 060730 -10parts.

Steps (k) and (I) together show the formation of a further water inlet, in which a notch 160 (see step (j)) is cut out of the exterior sheet 100 for communication between the hollow wall 118 and a socket mounting plate 162 mounting a further water inlet socket 164.

At least one of the framework walls 3, 4, 5, 6, 7, 8 (see Figs. 1 and 2) of the jig 1 are then moved to enable the clamping means to engage with and hold the parts of the boiler shell positioned in the jig rigidly and in a proper relation to one another. A connection means (not shown), such as a welding torch, is then passed though the bores 13 in each framework wall 3, 4, 5, 6, 7, 8 and then activated to connect at least some of the contacting surfaces of the parts in the jig 1. Finally, the assembled boiler shell is removed from the jig 1 and delivering to a welding station to be robotically welded.

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

Claims (5)

1. A method of robotically welding a boiler shell for an enclosed boiler having at least one a water carrying interior tank requiring stiffening, the method including providing a jig having: a substantially rectangular framework having a top wall and a base wall spaced apart by a front wall, a back wall and two side walls, in which at least one of the framework walls is able to be moved to enable separate component parts for the boiler shell to be placed in the jig and the assembled boiler shell to be removed from the jig; clamping means to hold the parts rigidly and in a proper relation to one another in the jig, whereby at least one of the framework walls has a plurality of through bores through which a connection means is passed to connect at least some of the parts together to assemble the boiler shell for robotically welding on removal from the jig, the method comprising the steps, not necessarily sequentially, of: (i) cutting an exterior enclosure sheet to form at least a rear exterior wall and side exterior walls of the boiler shell, and cutting an interior enclosure sheet to form at least a rear interior wall and side interior walls of the boiler shell, in which mounting ledges are formed adjacent a peripheral edge of each side interior wall; (ii) cutting a plurality of openings in the rear wall of the interior enclosure sheet where a water carrying interior tank is to contact the interior enclosure sheet; (iii) arranging the interior sheet relative to the exterior sheet in the jig to form a U-shaped channel having two hollow side walls °6073q -12spaced apart by a hollow rear wall for carrying water to be heated; (iv) forming two tank side plates, a tank base plate and a substantially L-shaped tank front plate, the tank side plates and tank base plate each having a pair of facing surfaces bounded by upper, lower and side peripheral edges, and the tank front plate having side facing peripheral edges, and in which a plurality of protruding tabs extend from the peripheral edges of the plates for engagement within the openings in the rear wall of the interior enclosure sheet, the plates then being arranged within the channel so that the peripheral edges of the tank side plates project outwardly of the side facing peripheral edges of the tank front plate to form the interior tank; (v) cutting a burner plate sheet to form a substantially flat rectangular burner plate and an outer burner tray having a rectangular base with upstanding side walls, and then cutting a through bore in a facing surface of the burner plate and the burner tray, the diameter of the bore in the outer burner tray being slightly greater than the diameter of the bore in the burner plate, (vi) positioning the burner plate across an open face of the Ushaped channel on the mounting ledges and then placing the outer burner tray on the inner burner plate to form an enclosed cavity there between; (vii) cutting a plurality of socket locating openings in the outer burner plate for communication between upright sockets placed on the outer burner plate and the cavity; (viii) positioning a burner ring in the form a cylindrical sleeve on the burner plate to form, with the bores in the burner plate and ° 6 O?3o -13outer burner tray, an inlet for flames; (ix) cutting a baffle assembly mounting sheet to form a plurality of baffle assembly support plates, and then positioning each baffle assembly support plate formed within the U-shaped channel where baffle plate assemblies are to be supported within assembled the boiler shell; (x) moving at least one framework wall of the jig to enable the clamping means to engage with and hold the parts of the boiler shell positioned in the jig rigidly and in a proper relation to one another; (xi) passing the connection means though the bores in each framework wall to connect at least some of the contacting surfaces of the parts in the jig, and (xii) removing the assembled boiler shell from the jig and delivering to a welding station to be robotically welded; and wherein, subsequent to step (iv) and prior to step (xii), the additional steps are performed of: (xiii) forming a plurality of alignment and stiffening members, each member having at least one protruding tab extending from a proximal end and a distal end thereof, and (xiv) engaging each tab within one of a respective notch formed in the outwardly projecting peripheral edge of one of the tank side plates and a respective enclosed slot formed in the interior side wall so that each member extends between the interior tank and an interior side wall to stiffen the interior tank, whereby on removal of the boiler shell from the jig there is minimum relative movement of the boiler shell parts. 06073ο -142.

A method as claimed in claim 1, further comprising forming means on the jig for indicating which contacting surfaces of the parts in the jig are to be connected by the connection means.

3. A method as claimed in claim 1 or 2, further comprising the mounting the jig framework so that it is able to be rotated.

4. A method as claimed in any preceding claim, further comprising the step of 10 providing the jig with braking means so that the position of the framework can be locked in any desired position when rotated.

5. A method substantially as herein described with reference to and as illustrated in the accompanying diagrams.