WO2000047940A1

WO2000047940A1 - A radiator

Info

Publication number: WO2000047940A1
Application number: PCT/IE2000/000022
Authority: WO
Inventors: Padraic O'reilly; Michael Meagher
Original assignee: Baggrave Ltd.
Priority date: 1999-02-12
Filing date: 2000-02-14
Publication date: 2000-08-17
Also published as: IES20000093A2; AU2569100A; EP1155274A1; IE20000094A1

Abstract

A fluid-filled radiator is manufactured from a plurality of relatively shallow tubular panel elements (61 to 64) by arranging the panel elements edge to edge and inserting at least one reinforcing member (20) into each end of each panel element, the reinforcing members fitting closely between the opposite major surfaces of the panel elements. A plurality of individual bridging members (90) are resistance welded to each end of each adjacent pair of panel elements, each bridging member extending from a major surface of one panel element to a major surface of the adjacent panel element. The reinforcing members (90) prevent the collapse of the panel elements under the pressure of the resistance welding.

Description

A RADIATOR

This invention relates to a method of manufacturing a radiator for use, for example, in a central heating system, and to a radiator made by such method.

There are various welding techniques known for the manufacture of a radiator for use in a central heating system. These techniques include projection welding, laser welding and MIG welding. This invention is chiefly, though not exclusively, concerned with the manufacture of a radiator by projection welding.

Projection welding is widely used in the manufacture of tubular steel radiators. The main advantages of the process are that large volumes can be produced and that a very consistent high quality weld can be achieved between the various components.

Projection welding is a form of resistance welding. Resistance welding is defined as "a group of welding processes that produces coalescence of the welding surfaces with the heat obtained from resistance of the work-piece to the flow of the welding current in a circuit of which the work is a part, and by the application of pressure" .

With projection welding, the welds are located at predetermined points by projections, embossments or insertions.

By way of explanation, Figures 1 and 2 show a typical projection welding set-up. Where the two work-pieces 1,2 meet, the contact area 5 of the projections is relatively small. Thus when a squeezing force is applied via electrodes 3, 4 there is a high load concentration at this point. If a current is then applied between the electrodes 3,4, the greatest electrical resistance will occur at the projections causirig a sharp localised increase in heat and thus collapse of the projection. The lower work-piece will heat sufficiently to allow the projection to coalesce with it thus forming weld nuggets 6. The electrode force is maintained after welding has taken place to allow for fusion during cooling.

Thus the main factors affecting a projection weld are: projection design force applied weld current, and material thickness.

In Figures 3, 4 and 5, there is shown a front view, top view and side view of a known horizontal panel radiator 7 manufactured in accordance with the known projection welding technique. The panel radiator 7 comprises a plurality of tubes 3 connected to a pair of header tubes 9. A detailed description of said known radiator

7 is not required save to say that there is liquid communication between the header tubes 9 and the tubes

8 as well as ports in the header tubes 9 for liquid communication to the pipes of a central heating system. The nature of the projecting welding technique is such that, because each tube 8 is welded separately and directly to the header tubes 9 and because of the electrical nature of the welding technique, it is necessary that each tube 8 be electrically isolated from its immediate neighbour. This is achieved by providing a gap 10 between the tubes 8 as will be observed in Figure 3 of the drawings. If tubes 8 were touching during projection welding, each header tube 9, which is electrically common to all tubes 8 would mean that the easiest path for current to flow would be from tube 8 to adjacent tube 8 rather than the desired path of tube 8 to header tube 9.

Another problem associated with the manufacture of radiators is the requirement to use header tubes 9 of varying lengths depending on the number of tubes 8 employed. While this problem is not too serious when a significant number of radiators of the same number of tubes 8 is being manufactured on a production line, the problem becomes significant from a stock control/stock availability point of view when the radiators being manufactured on the production line have a different number of tubes therein. It will be appreciated that, for each radiator, a pair of header tubes of a specific length for that radiator is required. As such radiators can have from as few as two tubes 8 per radiators to as many as sixteen or even eighteen tubes 8 per radiator, it will be appreciated that stock availability and control of header tubes 9 in those circumstances can lead to increased production cost. Furthermore, regardless of whether the production line is producing a significant number of radiators having the same number of panels 8 or radiators having a varying number of such panels 8, it is necessary to manufacture and retain in stock as many as fifteen or seventeen different lengths of header tubes 9.

It is an object of the present invention to provide an improved method of manufacturing a radiator in which these disadvantages may be avoided or mitigated. According to an aspect of the invention, there is provided a method of manufacturing a radiator as claimed in claim 1. In a further aspect of the invention, there is provided a method for the manufacture of a radiator as claimed in claim 2 and/or claims depending therefrom.

The invention also provides a radiator made by the method as claimed in claim 1 or as claimed in claim 2 and/or claims depending therefrom.

The invention is also directed to apparatus for carrying out the disclosed method (s) and including apparatus parts for performing each described method step, be it by way of hardware components, a computer programmed by appropriate software, by any combination of the two or in any other manner

The invention will be understood in greater detail from the following description of preferred embodiments thereof given by way of example only and with reference to the accompanying drawings in which:

Figure 6 is a perspective view of a reinforcing and flow control device for use in a first embodiment of the invention;

Figure 7 is a plan view of the device of Figure 6 of the drawings; Figure 8 is a cross-sectional view of the device of Figure 7 of the drawings taken along the line A-A and viewed in the direction of the associated arrows;

Figure' 9 is a cross-sectional view of the device of

Figure 7 of the drawings, taken along the line B-B and viewed in the direction of the associated arrows;

Figure 10 is a cross-sectional view of a second embodiment of a reinforcing and flow control device, which view is similar to that of Figure 8 of the drawings ;

Figure 11 is a cross-sectional view of the device of Figure 10 of the drawings which view is similar to that of Figure 9 of the drawings;

Figures 12-14 show the manufacturing steps in the production of a radiator in accordance with a first embodiment of the invention;

Figure 15 shows a cross-sectional view of part of a radiator made according to the invention;

Figure 16 shows a cross-sectional view of part of a radiator made according to the invention;

Figure 17 is a front view of a radiator made according to the invention;

Figure 18. is a plan view of the radiator of Figure 17; Figure 19 is a side elevation of the radiator of Figure 17;

Figure 20 is a partial rear view of the radiator of Figure 17;

Figures 21-35 show schematic views of radiators each constructed from a varying number of radiator panels and showing the direction of flow of fluid therein;

Figure 36 is an end view of two radiators made according to the invention connected together to form double panel radiator;

Figure 37 shows four radiators made according to the invention connected together to form a four panel radiator; and

Figure 38 is a perspective view of a further embodiment of a reinforcing and flow control device;

Figure 39 is a plan view of the device of Figure 38;

Figure 40 is a perspective and exploded view of part of a radiator made according to the invention which employs the device of Figure 38 of the drawings;

Figure 41 is a cross-section view taken along the A-A of Figure 40 and viewed in the direction of the associated arrows;

Figure 42 is a schematic v ew of the assembled radiator of Figure 40 of the drawings; Figs. 43A and 43B are plan and side views respectively of a further embodiment of reinforcing member;

Figs. '44A and 44B are rear elevations of radiators manufactured using reinforcing members as shown in Fig. 43;

Fig. 45 is a plan view of the top end of a three panel radiator each of whose three panels is constructed from multiple panel elements as shown in Figs. 44A or 44B;

Fig. 46 illustrates how the reinforcing members of Fig. 43 may be retained in position in the panel elements;

Fig. 47 shows an alternative projection welding appararus to that shown in Fig. 13;

Fig 48 is a cross-sectional view of an alternative embodiment of a bridging member for use in the radiator according to the invention; and

Fig 49 is an underneath plan view of the member of Fig 47 of the drawings.

Referring now to the Figs. 6 to 11 of the drawings, a reinforcing and flow control device 20 comprises an element 21 which is substantially rectangular in plan view. It will be appreciated that any other suitable geometric shape may be used. The device 20 is a shallow body having substantially parallel obverse and reverse major surfaces 22 and 23 respectively, a first side edge 31, a second side edge 32, a third side edge 33 and a fourth side edge 34. In one embodiment of the device 20, there is provided a first hole 41 and a second hole 42. The holes provide communication between the obverse face 22 and the reverse face 23. The holes 41, 42 are, in this example, circular in plan view and of substantially equal diameter although this is not essential.

The holes 41, 42 are in fluid communication with each other by virtue of a first through bore 24. In addition, a second through bore 25 connects the second hole 42 to a port 26 in the first side edge 31.

Instead of providing holes 41, 42 which extend completely through the device 20, there may be provided, as an alternative, first and second recessed holes 51 and 52, which are provided in the obverse face 22 of the element 21 (Figures 10 and 11) .

With the exception of the provisions of recesses 51, 52, all other features of the device 20 of Figures 10 and 11 are the same as that described with respect to Figures 6-9 of the drawings, including any alternative constructions referred to therein.

It will also be appreciated that more than one second through bore and associated port may be provided. Further, each bore 24 and 25 may be replaced by a narrow channel in a surface 22 or 23 of the device 20.

It will be appreciated that the holes 41 and 42 (or the recesses 51 and 52) together with the bores 24 and 25 constitute a fluid conduit system in the device 20. The device 20 is comprised of a metal and should have sufficient strength to withstand simultaneously applied pressures thereto in the obverse face direction as well as the' reverse face direction.

Referring now to Figures 12-20 of the drawings, and in particular to Figures 17-20, there is shown a radiator 60 manufactured according to the invention using the known technique of projection welding. As will be observed from Figures 17-20, the radiator comprises four tubular panel elements viz . a first tubular panel element 61, a second tubular panel element 62, a third tubular panel element 63 and a fourth tubular panel element 64. Each tubular panel element 61-64 is relatively shallow compared to its width so as to have a pair of opposite substantially parallel major surfaces 65, 66 joined by relatively narrow substantially parallel edges 67, 68. In the radiator 60 the panel elements 61-64 are disposed in edge to edge contact. It will be appreciated that the radiator 60 may comprise as few as two tubular panel elements or more than four tubular panel elements. As each of the panels 61-64 is of similar construction, only one of them will be described in detail. The steps of manufacture of the radiator of Figure 17 are shown in Figures 12-14 of the drawings.

Referring now to Figures 12-14 of the drawings, there is shown in Figure 12 one end 161 of the first and second panel elements 61, 62. Each element 61 and 62 (and similarly the elements 63 and 64) has a front major surface 65 and a rear major surface 66, which surfaces 65 and 66 are contiguous with edges 67 and 68 to form an integral unit which defines what will ultimately be a chamber 69. The rear surface 66 has a first opening 71 and a second opening 72. The openings 71, 72' provide fluid communication between the rear surface 66 and the chamber 69. It will be appreciated that the openings 71, 72 may be formed by petal piercing as described later in the specification.

Because the panel elements are still open at each end, the initial step in the process of the manufacture of the radiator 60 is the insertion of a device 20 into the end of each panel element. For example, Fig. 12 shows a first such device 20 inserted into the chamber 69 at the end 161 of the panel element 62. It is preferable that the device 20 comprises through holes 41, 42 rather than recessed holes 51, 52. However, where the context permits, it is to be understood that where references are made to holes 41, 42, that reference can embrace in the alternative recessed holes 51, 52 respectively. Thus, when inserted into the chamber 69, the hole 41 is in register with the first opening 71 and the hole 42 is in register with the opening 72. The shape and configuration of the device 20 is such as to allow a space in the chamber 69 to allow fluid to flow from the port 26 to the chamber 69 or vice versa. The thickness of the device 20 is such that it fits closely between the opposite major surfaces 65, 66 of the panel elements to provide support for projection welding, as will be described. A similar device 20 is inserted m a similar fashion into each end of each of the panel elements 61, 62, 63 and 64 which will constitute the radiator 60.

In order to provide fluid interconnection between adjacent panel elements, bridging or fluid connecting members 90 are provided. As will be observed from Figures 12-14 and 16, the bridging member 90 essentially comprises a u-shaped tube having a first leg 91, a second leg 92 and a connecting portion 93. (In Figures 48 and 49, there is shown an alternative embodiment of a bridging member 90a in which the legs 91a, 92a only project a relatively short distance.) The free ends of the legs 91, 92 are shaped and sized so as to mate with the openings 72,71 respectively.

Thus, the bridging members 90 are offered to adjacent panel elements, such as those shown at 61, 62 in Fig. 12, so that the leg 91 is in register with the opening 72 of the first panel element 61 and the leg 92 is in register with the opening 71 of the immediately adjacent second panel element 62.

A similar exercise is performed for all the other panel elements and openings 71, 72 thereof except as follows. In a radiator 60 constructed from a plurality of panel elements 61-64, and with the devices 20 and bridging members 90 in place, there will be four ports not connected to bridging members 90. Each of these four parts will be located at a corner of the radiator 60. Into each of these ports, which will be the two ports 71 of the panel element 61 and the two ports 72 of the panel element 64, there is inserted a respective connector element 95. The connector element 95 permits fluid communication between the pipes (not shown) of a central heating system and the radiator 60.

The projection welding technique is shown in Figure 13. As wil'i be observed, the devices 20 are in place as are the bridging members 90.

Two electrodes 81, 82 (Fig. 13) of a projection welding mechanism are provided. The electrode 81 makes physical and electrical contact with the bridging member 90, and the electrode 82 makes physical and electrical contact with the front surfaces 65 of the panel elements 61, 62. In use, the electrode 81 or the electrode 82, or both, are moved in the direction of the arrows 100 and thus pressure is applied on accordance with the usual practice in projection welding. A DC or AC current is applied across the electrodes 81, 82 so as to cause the free ends of the legs 91, 92 to become rigidly welded to the rear surfaces 66 of the panels 61, 62.

It is preferred that the free end of each leg 91, 92 is shaped or tapered such that when, for example, the leg 91 is offered to the first panel element 61, the free end of the first leg 91 is now in physical contact with the obverse surface 66 at the aperture 72. There is thus provided a sealed continuous channel between the first panel element 61 and the second panel element 62 via the second aperture 72 of the first panel element 61, the first leg 91, connecting portion 93, second leg 92, and the first aperture 71 of the second panel element 62. The device 20 provides a suitable support or backing for the surfaces 65, 66 which prevents the surfaces 65, 66 from collapsing or being distorted due to the pressure applied by the electrodes 81, 82. Following the removal of the electrodes 81, 82, the radiator moves along a suitable conveyor belt 96 in the direction of the arrow 97 so that the legs 91, 92 of the next bridging member 90 may be welded in a similar fashion to the next set of openings 71, 82 of the panel elements 62, 63 in the manner previously described. It will be appreciated that a similar exercise is performed at the opposite end of each panel element 61- 64. The connector element 95 is applied to the relevant panel also by projection welding in a similar fashion.

It will be observed that the traditional header tube 9 located on each side of such a panel radiator has now been replaced by a plurality of bridging members 90 which rigidly connect the panel elements 61-64 together and which, together with the devices 20, enable fluid to flow to each panel element 61-64. The provision of the second through bore 25 permits fluid flow into, or out from, the panel element. As the diameter of the second bore 25 and its associated port 26 is considerably smaller in size than the diameter of the u-tube of the bridging member 90 and the holes 41 and 42, a greater volume of liquid per unit time will flow from one bridging member 90 to the next than to or from the main body of the chamber 69, thus providing efficient fluid flow for each panel element 61-64 and thus providing an effective radiator 60. In addition, because there are no conventional header tubes 9 present which, during the process of projection welding as previously described, required the panel elements to require a gap 10 therebetween, no such gap is now necessary because the electrical path is now concentrated between the bridging member 90 and the now ^■couching panel elements, for example 61, 62. However, the invention may still be used to manufacture radiators with such gaps if desired.

It has been found that the diameter of the holes 41, 42 and the diameter of the u-tube should be approximately the same.

It will be appreciated that a fin element 160 may be provided and welded to the radiator 60 following the completion of the projection welding of the bridging member 90 and connector elements 95. In addition, as is usual in the manufacture of such radiators, the open ends of each panel element through which the devices 20 were inserted are closed off in a conventional fashion thereby providing a closed chamber 69 for each panel element 61-64.

It has been found that some form of flow control of fluid in the radiator is desirable. This can be achieved, for example, by the use of the device 20. Of course control of the flow of fluid in the radiator is dependent on where the fluid inlets and outlets are. Usually in such radiators, there are four possible locations for connection to a central heating system. This provides for three possibilities viz . : (a) top and bottom opposite ends - TBOE;

(b) bottom opposite ends - BOE; and

(c) top and bottom same end - TBSE . Connection to the radiator using Ventile, TKM, or other such standard methods is possible.

Thus, in Figure 21, there is shown a schematic of a radiator constructed in accordance with the invention. This is a four panel radiator 60 having an outlet port at 15; a closed or drain port at 16; an inlet port at 17; and an air vent at 18. Arrows 19 indicate the movement of fluid in the radiator. It will also be observed that all of the bridging members 90 are of the type which allow fluid to flow therethrough. If additional panel elements are added, the arrangement of the bridging members 90 does not need to be altered. This is known as a TBOE radiator.

In Figure 22, the inlet is now at 15; the outlet at 16; with the air vent at 17 and the closed port at 18. Again, the arrows 19 show the movement of fluid in the radiator and, as in Figure 21, all of the bridging members 90 function to conduct the flow fluid. In such a radiator, a flow regulation mechanism such as the device 20 is required. However, the arrangement of the bridging members 90 does not need to be altered with the addition of more panel elements . This is known as a BOE radiator.

Figures 23-35 are schematic drawings of TBSE radiators. Thus, in all of them, the inlet is at 18 with the outlet at 15. The port 16 functions as a closed or drain port; the port 17 functions as an air vent. The difference between the various fiσures is as follows. 00/47940 -_ g PCT/IEOO/00022

Figure 23 shows a two panel radiator which can only have one possible arrangement of the bridging member 90 in that it is located on the opposite side to the inlet and outlet ports at 18 and 15 respectively. The bridging member 94 has all of the features of the bridging member 90 except that it is blocked internally so that it cannot conduct fluid. Thus, to ensure that fluid travels correctly through the radiator of Figure 23, a fluid functioning bridging member 91 and a non- fluid functioning bridging member 94 are employed to achieve the desired effect.

Figure 24 and 25 show two possible arrangements of the use of a functioning bridging member 90 and the use of a non-functioning or baffled bridging member 94 in the case of a three panel radiator. As an alternative to using the baffled bridging member 94, the first opening 71 or the second opening 72 need not necessarily be present .

Thus, during the manufacture of a radiator according to the invention, each tubular panel element, for example, the tubular panel element 61, arrives at the work station for assembly with other similar panel elements to form the radiator, without either the first opening 71 or the second opening 72 being present. The operator, knowing at that stage as to the configuration of the radiator, would, using appropriate equipment, provide that panel element 61 with the required or designated recesses or openings 71, 72. Thus, all the bridging members used would be functional bridging members 90. Functional in this context means that the element 90 possesses the tube as observed in Figure 16 of the drawings. However, because of the absence of, for example, the opening 71 of the panel element 62 and the opening 72 of the panel element 61, liquid cannot flow at that location from the panel element 61 to the panel' element 62 or vice versa . In order to maintain the mechanical integrity of the radiator, it is desired to employ the bridging member 90 at that location. The advantage of using this technique is that the number of different types of components necessary for the manufacture of a radiator is reduced. In addition, there is more precise control of manufacture at the actual site of assembly of the radiator.

Figures 26 and 27 show two arrangements for a four panel radiator; Figures 28, 29 for a five panel radiator; Figures 30, 31 for a six panel radiator; Figures 32, 33 for a seven panel radiator; Figures 34, 35 for an eight panel radiator.

The following table serves to illustrate various examples of permutations and combinations of the case of functioning bridging members 90 and non-functioning bridging members 94 in the construction of various multipanel radiators to achieve the desired flow of fluid therein when they are TBSE type radiators.

Number of fluid functional and non-fluid functional bridges per panel for options A and B Table 1

With reference to Figure 36 and having constructed a radiator 60 according to the invention, two of them may be j oined to provide a pair of such radiators fed by two t-piece connectors 75 , 76 as is well known in the art . Similarly, as will be observed in Figure 37 , four such radiators 60 are connected by pipes 77 and t-piece connectors 75 , 76 . It will be appreciated that the number of tubes or panel elements may be greater than 14 in number.

Instead of providing the reinforcing devices 20 as previously described, a device 400 as shown in Figures 37-41 could be used.

The device 400 is not unlike the device 20. The device 400, in the example shown, is B-shaped in plan view. Thus, there is provided an obverse face 422; a reverse face 423; a first side edge 431 which is substantially straight; a second side edge 432 which is arc shaped; a third side edge 433 which is also arc shaped; and a fourth side edge 434 which connects the second and third side 432, 433, edges and is substantially in parallel spaced apart relationship relative to the first side edge 431. Where the first side edge 431 and the second side edge 432 meet, an arris 435 is generated. Similarly, where the first side edge 431 and the third side edge 433 meets an arris 436 is generated. Two holes 441, 442 are provided. As in the case of the device 20, the holes 441, 442 provide fluid communication between the obverse face 422 and the reverse face 423.

At least one radially disposed bore 444 is provided in the device 400 such that the bore 444 provides fluid communication between the hole 441 and externally of the device 400. A plurality of such bores 444 is desirable and each of them terminates in a respective opening 441 in the first side edge 431. Similarly, a bore 445 (or bores) provide fluid communication between the recess 442 and externally of the device 400 via respective openings 447 in the side edge 433. There should preferably be no openings in the first side edge 431. Each bore 444 and 445 may be replaced by a narrow channel in a surface 422 or 423 of the device 400.

With particular reference to Figure 40 of the drawings, there is shown the ends of two tubular elements 61, 62 each of which houses a respective device 400. It will be noted that the device 400 is offered to the chamber 69 such that the fourth side edge 434 faces outwardly. When the device 400 is inserted into the chamber 69, the openings 71, 72 are absent. When the device 400 is at the desired location in the chamber 69, a punching machine (not shown) provides the openings 71, 72 (either consecutively or simultaneously as desired) such that the opening 71 is in register with the hole 441 and the opening 72 is in register with the hole 442. The technique used is preferably petal piercing. This technique allows for the metal which is punched to form petals of which two petals 450, 451 are shown in Figure 41. Each of the metal petals 450, 451 is attached at one end to the obverse face 422. Thus, for example, the petal 450 is disposed at approximately 110° relative to the obverse face 422 with the free end thereof projecting downwardly into the hole 441. Thus, the device 400 is restricted from moving within the chamber 69 following the act of petal punching. This is highly desirable because, it is preferred that the length of the first side edge 431 as measured between the arris 435 and the arris 436 is less than the width of the chamber 69. Thus, if the device 400 is centrally located in the chamber 69, there will be a gap 440 generated between that portion of the first side edge 432 near the arris 435 as the inside wall of the chamber 69 opposite it.

With the devices 400 in place which act as reinforcing devices as well as fluid distribution or fluid control devices, the bridging member 90 (or 94 as desired) is offered to the panel elements 61, 62 as previously described and the rest of the radiator is assembled.

In use, and for example, fluid enters the opening 71, flows into the hole 441 and exits the openings 446 via the bores 444. Some of the fluid will flow into that part of the chamber via the gap 440 on each side of the device 400. However, as this gap 440 is relatively narrow and restricted, most of the fluid enters the bores 445 via the openings 447 and flows into the opening 442. From there, the fluid exits the opening 442 and flows into the leg 91 of the bridging member 90 via the opening 72. The fluid flow then continues as previously described above.

A further reinforcing member is shown in plan and side view respectively in Figs. 43A and 43B. The reinforcing member is a sintered body 600 in the form of a shallow ring having substantially parallel opposite major surfaces 600A and 600B, a relatively large central hole 602 and four equiangularly spaced narrower radial bores (or channels) 604 extending from the hole to the edge of the ring. In use in the construction of a radiator, two of the devices 600 replace a single one of the previously described devices 20 or 400, as seen in schematic form, and by way of example only, in the TBOE radiator shown in Fig. 44A. Here, a respective device 600 is located in register with each leg 91, 92 of the bridging member 90, the holes 602 and bores 604 allowing fluid flow both through the bridging member and also too and from the chamber 69. Another example is seen in the TBSE radiator of Fig. 44B. In this case one of the bridging members 94 needs to be baffled so that no fluid can pass through it. This can be achieved as previously described by blocking the bridging member internally or by omitting one or both of the apertures 71 or 72. However, it can alternatively be done by replacing one of the associated devices 600 with a plain disc of the same external dimensions, i.e. omitting the hole 602 and bores 604, as will be described. Since the devices 600 are a close fit in the panel elements 61-64, this effectively blocks the flow through the bridging member .

In all cases the devices 600 provide flow preferentially between bridging members 90 than into or out of the main body of the panel element, as previously described.

Fig. 45 is a side view of the top end of a three panel radiator each of whose three panels is constructed, for example, from multiple panel elements as shown in Figs. 44A or 44B. In Fig. 45 only the top element 61 is shown in each case. Here a T-piece 606 connects the right pair of panel elements 61 while a straight tube 608 connects the left pair. The open ends of the T- piece 606 and tube 608 are projection welded to apertures (not shown) in the major surfaces of the elements 61 in similar manner to that described for the bridging members 90, each in register with one of the reinforcing devices 600. Thus, due to the presence of the relatively large holes 602 in the centre of the devices 600, fluid introduced into the T-piece as represented by the arrow 610 can pass freely to each radiator panel for distribution through the bores 604.

Fig. 46 illustrates how the reinforcing members 600 may be retained in position in the panel elements 60 to 64 by a plurality, in this case four, of dimples 612 formed in the inside surface of the panel elements.

Fig. 46 also shows the use of a non-apertured disc 600A to baffle flow through one of the bridging members 90, as previously referred to.

In Fig. 13 a projection welding apparatus was used which used upper and lower electrodes with the current flowing from one to the other across the bridging member 90 and panel elements 61, 62. This has two possible problems. First, there can be an unequal current distribution due to unequal force applied to the two legs 91, 92 of the bridging member 90. Secondly, there can be an unequal current distribution due to a Faraday cage effect in the bridging member. This means that current could flow around the outer shell of the bridging member, so that the inner edges of the projection welds may not have a good quality and thus may be weak. Fig. 47 shows an alternative projection welding apparatus to that shown in Fig. 13 which can overcome or mitigate this problem. Here, both electrodes 82A, 82B are at the bottom, one in contact with one of a pair of adjacent panels, say the panel 61, and the other in contact with the other panel 62. These electrodes are mounted on a common base 700 but are electrically isolated by insulation 702. In addition, there are now two force applying members 81A, 8IB which in use are brought into contact with the opposite ends of the bridging member 90, one directly over the leg 91 and the other directly over the leg 92. Each force applying member can be individually pressed onto the bridging member; thus this allows the force on each leg 91, 92 to be independently adjusted so that they can be made equal. Further, the current flows through first one leg 91 and then the other, so that it does not have to flow around the upper shell of the bridging member as before.

The invention is not limited to the embodiments described herein which may be modified or varied without departing from the scope of the invention.

Claims

1. A method of manufacturing a radiator, comprising providing at least one relatively shallow tubular panel element having a pair of opposite major surfaces joined by relatively narrow edges; inserting at least one reinforcing member into at least one end of the panel element, such member fitting closely between the opposite major surfaces of the panel element and resistance welding a fluid connecting element to a major surface at the said end of the panel element; the reinforcing member (s) preventing the collapse of the panel element (s) under the pressure of the resistance welding.

2. A method of manufacturing a radiator, comprising providing a plurality of relatively shallow tubular panel elements each having a pair of opposite major surfaces joined by relatively narrow edges; arranging the panel elements edge to edge; inserting at least one reinforcing member into each end of each panel element, such member fitting closely between the opposite major surfaces of the panel element; and resistance welding a plurality of individual bridging members to each end of each adjacent pair of panel elements; each bridging member extending from a major surface of one panel element to a major surface of the adjacent panel element and at least one of the bridging members providing a fluid connection between the pair of panel elements by communicating with the interior of each panel element via a respective aperture in the major surface thereof, the reinforcing members preventing the collapse of the panel elements under the pressure of the resistance welding.

3. A method as claimed in claim 2, wherein the reinforcing members associated with each bridging member which provides said fluid communication include conduit means in register with the aperture in the respective panel element to allow fluid flow between the bridging member and the interior of the panel element.

4. A method as claimed in claim 3, wherein at least one panel element has two neighbouring panel elements, one on either side, and at least one end of the at least one panel element is joined to each neighbour by a respective bridging member providing fluid connection between the panel element and the neighbour via a respective aperture in the major surface of the tubular panel element, and wherein a single reinforcing member is located in the said at least one end of the panel element behind both apertures and has conduit means to allow fluid flow between the apertures and between each aperture and the interior of the panel element.

5. A method as claimed in claim 4, wherein the reinforcing member comprises a shallow body having opposite major surfaces which are substantially parallel to the opposite major surfaces of the tubular panel element, and wherein the conduit means includes two holes in one of the major surfaces of the body, each of said holes being in register with a respective aperture in the major surface of the tubular panel element.

6. A method as claimed in claim 5, wherein the conduit means further includes a first bore or channel in the body extending between the two holes and a second bore or channel in the body extending from one of the holes to the edge of the body.

7. A method as claimed in claim 5, wherein the conduit means further includes a first bore or channel in the body extending from one of the holes to the edge of the body and a second bore or channel in the body extending from the other of the holes to the edge of the body.

8. A method as claimed in claim 3, wherein at least one panel element has two neighbouring panel elements, one on either side, and at least one end of the at least one panel element is joined to each neighbour by a respective bridging member providing fluid connection between the panel element and the neighbour via a respective aperture in the major surface of the tubular panel element, and wherein two reinforcing members are located in the said at least one end of the panel element each behind a respective aperture and each having conduit means to allow fluid flow between the aperture and the interior of the panel element.

9. A method as claimed in claim 8, wherein each reinforcing member comprises a shallow body in the form of a ring with a central hole and at least one radial bore or channel extending from the hole to the edge of the ring.

10. A method as claimed in any one of claims 5 to 9, including the step of making the apertures in the major surface of the panel elements by punching with the reinforcing member (s) in position in the end of the panel' element such that remnants of the major surface which are forced into the holes in the body(s).

11. A method as claimed in any of claims 2-10, wherein the at least one reinforcing member is constructed and arranged in the end of the panel element such that a greater volume of fluid per unit time fluid flows from one bridging member to the next than into or out of the main body of the panel element.

12. A method as claimed in any of claims 2-12, wherein the adjacent edges of the panel elements are in contact.

13. A radiator made by the method as claimed in claim 1.

14 A radiator made by the method as claimed in claim 2 or any of claims 3-12.