GB2442483A - Method of manufacturing a boiler shell - Google Patents

Abstract

The method is for robotically welding a boiler shell for an enclosed boiler having at least one water carrying interior tank requiring stiffening. The method includes providing a jig 1 having a rectangular framework 2 and a clamping means 11 to hold the component parts of the boiler being manufactured rigidly and in proper relation to one another in the jig. The method ensures that the interior tank and other component parts of the boiler shell are held in their correct position during delivery to a robotic welding machine, and during robotic welding.

Description

iA Method of Manufacturing a BoUer Shell"

Introduction

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

The manufacture of boiler shells for enclosed boilers typically requires initially fornrnng the separate component parts of the boiler shell and then manuafly positioning and welding the component parts together to Form Ihe bolter 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 10 be heated.

Ii will however be appreciated that the Fornialion of such boiler shells from component parts is an extremely time consuming and intensive process as operalives 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 bofler 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 taHing to correctly weld the boiler shell. Additionally, the further problem of water leakage from the water carrying structures of ttie 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 mach!ne failing to correctly weld the boiler shelL II is a Iherelore 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 w4ll 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 nieantng, For Ihe purpose or this specification, and unless otherwise noted explicitly, the terra comprise shall have an inclusive meaning i.e. that it may be taken to mean an inclusion of not only the listed components ii directly relerences. but also other nonspecified 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.

Futiher aspects of the present invention will become apparent form the ensuing

description which is given by way of example only

Statements of tnpqion

According to the invention, there is provided a method ol 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 ig having: a substantially rectangular framework having a tap 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 paris for the boiler shell to be placed in the jig and the assembled boiler shell to be renioved from the jig; clamping means to hold the paris rigidly and in a proper relation to one another in the gig, whereby at Feast one ci the framework walls has a plurality of through bores through whicn a connecton means is passed to ccnnect at east some o the parts together to assemble the boiler shell for roboticaUy 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 intenor wet! and side interior waits of the boer 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 waler carrying interior tank is to contact the interior enclosure sheet; (iii) arranging the interior sheet relative to the exterior sheet in the jig to Fomi a U-shaped channel having two hollow side walls spaced apart by a hollow rear wait for cartying 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 wUhin the openings in the tear 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 ci the side facing peripheral edges of the lank front plate to form the hiterior tank; (v) cutting a burner plate sheet to form a substantially fiat rectangular burnp.r plate and an outer burner tray hcvinq 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 ci the bore in the burner plate, (vi) positioning the burner plate across an open face of the U-shaped 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 cyJindrcal 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 pluraltty ci 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 thefl; (x) moving at least one framework wall of the jig to enable the damping means to engage with and hold the parts ot 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 waR to connect at least some of the conlacting surfaces of the parts in the jig, and (xii) removing the assembled boiler shefi from the jig and delivering to a welding staUon to be robotically welded: anti wherS, subsequent to step (iv) and prior to step (Xii), the additional S steps are performed ci: (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 farmed 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 lank and an interior side wall to stiffen the interior tank, whereby on removal of the boiler shell from the jg there is minimum relative movement of the boiler shell parts, The present invention provides numerous advantages over prior art methods of forming boiler sheils. 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 wilt 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 wiR ensure that operatives will be able to ouckIy identify the surfaces of the boec shell components which are to be joined.

Preferably 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 Invenflon, the method further comprises the step of providing the jig with braking means so that the position ci the framework can be locked in any desired posit;on when rotated.

In another embodiment of the invention, the method further comprises the step of culling 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 or example only, with reference to the accompanying drawings, in which: Figs. 1 and 2 are perspective views ci 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 or a boiler shell from those parts according to the invention.

With nitiat reference to Figs. I 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 walt 5. a back wall 6 and two side walls 7, & At least one of the framework vaUs 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 I and the assembled boiler shell 10 (see Ag. 2) to be removed From the g 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 arc closed. In (tie 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 thefl 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 at the parts in the jig 1 are to be connected by the connection means. In the instance shown1 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 wails 3, 4. 5. 6. 7, 8. Accordingly, operatives will know the specific contacting surfaces at 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 Ic be rotated. In the embodiment showr the jig framework 2 is fixed to an axle 17 which s rotatably mounted Ic 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 Ihe jig framework 2. The braking means also comprises a lever arm 20 which is acluated by an operator at ds proximal end and terrmnaies in a locking member 21 at ts distal end In use, en operator actuates the lever arni 20 to cause tho tnckinq member 21 to engage between adjacent cog teeth in the cog 19 to ri turn lock the rotational posItion of the framework 2. Appropriate actuation ci the lever arm 20 wUl remove the locking member 21 from the cog 19 to perrrut rotation of the Framework 2.

It wiil therefore be appreciated that the initial step in the method ci 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 Feast 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 Ushaped channel, indicated generally by the reference numeral 116, having two hollow side walls 116 spaced aparl 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 U-shaped 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 126 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(aHd). 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 106 ci 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 plates 122, 124, 126 and 128 engage within the openings 114 anti the peripheral edges 130 ci Ihe tank side plates 122, 124 project outvrdly or the side facing peripheral edges 132 of the lank front plate to form the interior lank 134.

S 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 136 having a rectangular base with upstanding side walls 142. A through bore 144 is then cut hi a facing surface ci the burner plate 136, A further through bore 146 is also cut in the outer burner tray base 140 of the burner tray 136, 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 (ace of the Ushaped 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 (nfl) 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 o( 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 enciosed slot 156, see step (i), formed in the interior side wall 110 so that each member 154 extends between the interior tank 1:34 and an interor side wall 110 to stiffen the interior tank 134, whereby on removal of the boiler shell from the jig there is minirnunl relative movement of the boiler shell parts.

Steps (K) arid (I) together show the formation or a further water inlet, in which a notch (see step (j)) is cut out of the exterior sheet 100 for communicallon between the S hollow wall 118 and a socket mounting plate 162 mounting a further waler 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 Larch, 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, Ii -

Claims (6)

1, A method of robotically warding a boiler shell for an endosed boiler having at least one a waler carrying interior lank requiring stiffening, the method including providing a jig having: a substantially rectangular tramewo;k having a top wall and a base wall spaced apart by a front wail, 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 paris 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 lbs boi!er shell for roboucally welding on removal from the jig, the method comprising the steps, not necessarily sequentially, of; (i) cutting an exteror enclosure sheet to form at least a rear exterior wall and side exterior walls of the boiler shell, and cijfling an interior enclosure sheet to forni at least a rear interior wall and side interior walls of the boiler shell. in which mounting ledges are formed adjacent a peripheral edge ol 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; (ill) arrangnq the interior sheet relative lo the exterior sheet in the ig to form a U-shaned channel havinq two hollow side was -12 -spaced apart by a holiow rear wall for carr)ing watet to be heated; (iv) forming two tank side plates, a tank base plate arid a substantially L-shaped tank front plater the tank side plates and tank base prate each having a pair of facing surfaces bounded by upper, lower and side peripheral edges, and the tank front Plate having side lacing peripheral edges, and in which a plurality of protruding tabs extend from the peripheral edges of the plates for engagement wilhln 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 wahs, and then cutting a through bore in a (acing 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 U-shaped channel on the mounting ledges and then placing the outer burner tray on the inner burner plate to form an enclosed cavity there between; (vu) cutting a plurality of socket locating openings in the cuter burner plate for communication beten upnght sockets p!aced on the outer burner plate and the cavity; (wi) positioning a burner ring in the form a cyundricat sleeve on the burner plate to form. wit the bores ir the burner!ie and -13-outer burner tray, an inlet for flames; (ix) cutting a baffle assenibly 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 wilh 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 Ihough the bores in each framework wall to connect at least some of the contacting surfaces ot 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 pr!or to step (xii), the additional steps are performed of: (xiii) forming a plurality ol alignment and stiffening members1 each member having at Feast one protruding tab extending from a proximal end and a distal end thereof, and (xiv) engaging each tab within one of a respeclivt 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 Ihat each member extends between the interior tank and an Lnterior side wall to stiffen the interior tank, whereby on removal of the boiler shell from the jg there s rrin!mum re'ative movement of the hoer sh&l parts.

2. A method s c'aimed in claim 1, further comprising forming means on the jig for indicating which contacting surfaces ci the parts in the jig are to be connected by the connection means.

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

A method as claimed in any preceding claim, lurther comprising Ihe step of proding the jig wIh braking means so Ihat the position of the framework can be locked in any desired position when rotated.

5. A method as claimed in any preceding claim, further comprising the step of culling an opening in the exterior sheet for communication between at least one water inlet socket p!aced on the exterior sheet and a cavity formed between the exterior and interior enctosure sheets,

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