IE78827B1 - Heat exchanger panels - Google Patents

Abstract

A method of and apparatus for manufacturing a heat exchanger panel are disclosed. A pair of shells 10, 11 is formed from a sheet of metal, and the shells are subsequently folded about the longitudinal axis of the junction to provide a panel having a seamless upper edge. The junction of the shells 10, 11 and a portion of a corner 20, 21 are formed without seams at one end at least of the junction by working the metal plastically with one or more forming tools so as to form a seamless corner portion adjacent an upper extremity of a side edge seam provided by the contiguous edges of the folded over shells.

Description

The invention relates to heat exchanger panels and their manufacture. More particularly, it relates to central heating radiator panels, whose front walls and rear walls are each formed from profiled sheet metal shells, (hereinafter referred to as shells), with fluid channels separated from one another by flutings, the two shells being pressed from the same sheet, folded over about a common junction with formation of the channels, and welded together.

Central heating radiator panels (hereinafter referred to as panels) of the above-mentioned kind are well known. They have no prominent upper edge, but instead a relatively smooth upper surface without a welded seam. This feature is claimed to have safety advantages over central heating radiator panels made from two shells with a welded seam on the upper edge.

The side edges and lower edge of panels of the former type typically comprise welded seams between abutting flanges formed on each shell. The welded seams of the side edges and lower edges cross each other to form sealed junctions on the lower corners of the panel. The welded seams are mechanically trimmed along their length to provide a neat perimeter.

The intersections between the weld seams on the side edges and the unseamed upper edge, (hereinafter referred to as the corners or corner regions), are closed off and sealed w by several different methods.

In one well known method, the material of the corner regions is shaped such that holes are provided at each corner when the shells are folded over and seam welded. These holes whose axes are parallel to the longitudinal axis of the upper surface, are then fitted with metal caps and sealed to the panel by manual oxy-acetylene welding.

In another well known method, the material of the corner regions is shaped such that when the shells are folded over and seam welded, the ends of the upper edge and rebates of the side edge flanges co-operate to form a Y or T shaped seam at each corner, and are sealed by manual oxy-acetylene welding.

The complete specification of Irish Patent Application No. 1220/85 (Baufa-Werke Rinker GmbH) as laid open to public inspection discloses a panel and method for closing and sealing the corners by welding a curved cross-sectional seam.

The present invention provides a method of manufacturing a heat exchanger panel comprising forming a pair of shells from a sheet of metal, and subsequently folding the shells about the longitudinal axis of the junction to provide a panel having a seamless upper edge characterised by forming the junction of the shells and a portion of a comer without seams at one end at least of the junction- by working the metal plastically with one or more forming tools so as to form a seamless corner portion adjacent an upper extremity of a side edge seam provided by the contiguous edges of the folded over shells.

Additionally, the method comprises sealing or partially sealing the intersection of the seamless comer portion with the upper extremity of the side edge seam by the side edge sealing means.

Additionally, the side edge sealing means comprises resistance seam welding.

Additionally, the method comprises forming a notch at one 5 or each end of the sheet of metal along the longitudinal axis of the junction of the shells.

Additionally, the method comprises forming the seamless corner portion in one or more forming actions prior to folding the shells so that the metal is more plastically compressed or gathered in the corner than along the junction of the shells between the corners.

Additionally, the method comprises forming a corrugation along the junction of the shells and folding the shells about the longitudinal axis of the corrugation.

Additionally, the method comprises further forming the corner during the folding over of the panels by working the material plastically with forming tools having shapes corresponding to the shapes required on the seamless corner region.

Additionally, the method comprises forming the corrugation narrower than the width of the finished upper edge of the panel and gradually widening the corrugation during the folding over of the shells simultaneously with the gradual plastic forming of the corner regions.

Additionally, the method comprises forming the corrugation narrower than the width of the finished upper edge of the panel in the corner regions and equal to the width of the finished upper edge of the panel in the central region between the corners with the two widths blended in intermediate regions and gradually widening the corrugation in the corner regions during the folding over of the shells simultaneously with the gradual plastic forming of the corner regions.

Additionally, the method comprises using lifting arms to assist in the movement of the shells, the lifting arms having contact surfaces for contacting the side edge flange regions and central regions of the shells to assist in maintaining the alignment of the side edge flange regions and central regions of the panel or to directly assist the folding operation.

The present invention also provides a heat exchanger panel having a seamless upper edge at the junction of a pair of folded over shells of sheet metal and at least one seamless corner portion at an end of the junction.

The present invention further provides an apparatus for manufacturing a heat exchanger panel comprising means for forming a pair of shells from a sheet of metal, and means for subsequently folding the shells about the longitudinal axis of the junction to provide a panel having a seamless upper edge characterised in that the apparatus includes one or more forming tools for forming the junction of the shells and a portion of a corner without seams at one end at least of the junction by working the metal plastically so as to form a seamless corner portion adjacent an upper extremity of a side edge seam provided by the contiguous edges of the folded over shells.

Additionally, the apparatus comprises means for forming the seamless corner portion in one or more forming actions prior to folding the shells, so that the metal is more plastically compressed or gathered in the corner than along the junction of the shells between the corners.

Additionally, the apparatus comprises means for forming a corrugation along the junction of the shells and means for folding the shells about the longitudinal axis of the corrugation.

Additionally, the apparatus comprises forming tools having shapes corresponding to the shapes required on the seamless corner region for further forming the corner during the folding over of the panels by working the material plastically.

Additionally, the apparatus comprises means for forming the corrugation narrower than the width of the finished upper edge of the panel and gradually widening the corrugation during the folding over of the shells simultaneously with the gradual plastic forming of the corner regions.

Additionally, the corrugation forming means is operable to form the corrugation narrower than the width of the finished upper edge of the panel in the corner regions and equal to the width of the finished upper edge of the panel in the central region between the corners with the two widths blended in intermediate regions and means for gradually widening the corrugation in the corner regions during the folding over of the shells simultaneously with the gradual plastic forming of the corner regions.

Additionally, the apparatus comprises lifting arms operable to assist in the movement of the shells, the lifting arms having contact surfaces for contacting the side edge flange regions and central regions of the shells operable to assist in maintaining the alignment of the side edge flange regions and central regions of the panel or to directly assist the folding operation.

An embodiment of the invention, comprising a central heating radiator panel, will now be described by way of example only.

Reference is made to the accompanying drawings in which: Figure 1 is a plan view of the two shells formed on a sheet of metal; Figures 1(a), 1(b) and 1(c) show an end view, a side view and a sectional view on A-A of the side view respectively of the corner region of a panel prior to the folding over operation; Figures 2(a), 2(b) and 2(c) show an end view, a side view and a sectional view on A-A of the side view respectively of the corner region of a panel following the folding over operation but before complete closure of the shells; Figures 3(a), 3(b) and 3(c) show an end view, a side view and a sectional view on A-A of the side view respectively of the corner region of a panel following complete closure of the shells; Figures 4(a) and 4(b) shown an end view and a side view respectively of the corner region of a panel following welding and trimming of the edge seams; Figure 5 is a sectional view on B-B of Figure 4(a); and Figure 6 is a sectional view on C-C of Figure 4(a).

Reference is now made to the drawings and in particular to Figures 1(a) to 1(c), in which a corner region of a panel is shown prior to the folding over operation.

At this stage, the profiled shells 10,11 have been formed on the sheet of metal 12 which is sheet steel of around 1.2 mm thickness. The corner regions 20, 21 are formed as shown in Figures 1(a) and 1(b) and the region between the two corners, corresponding to the upper edge of the panel, is formed with a corrugation 30 of profile as shown in Figure 1(c). It will be appreciated that the corner regions 20, 21 comprise seamless corner portions and that having been produced from flat sheet material the metal is more plastically compressed or gathered in the corners than along the corrugation 30 which comprises the junction of the shells between the corners.

The corrugation 30 and corner regions 20,21 can be formed concurrently with the shell pressing operations, and are carried out in accordance with the known methods for metal forming. Forming of the corner regions 20,21 involves a considerable degree of drawing and plastic deformation of the material.

The formed profiled shells 10,11 are then placed face-down in a press (the details of which are not shown), with the corrugation 30 entering a longitudinal female die tool, positioned underneath, and a longitudinal punch tool, positioned above. These are used to carry out the folding over operation whereby the punch descends, enters the corrugation 30 and pushes the centre of the sheet downwards causing the portion of the shells outside the centre to react against the longitudinal edges of the die and rotate upwards.

The punch is of approximate semicircular face shape along its centre section, with its radius corresponding to the required inside radius of the finished panel upper edge.

At its extremities, the punch is terminated and shaped to correspond with the inside shape of the required panel corners 20,21. Similarly, the die is partly shaped at its extremities to correspond to the outside shape of the panel corners 20,21. In particular, the die is shaped to support the flange regions adjacent the corners both at the end of the press stroke and to some degree during it. Because, however, the material is in tension during the folding over operation in the region of the seamless corner bosses, it is not necessary for the die to make contact or be shaped in those regions.

The corrugation 30 is made narrower than the width of the punch or the width into which it is shaped in the folding over operation. The principle reasons for this are twofold. Firstly, it allows the punch gradually to enter the corrugation 30 and maintain a downward force on the material to power the folding over operation as the comer regions 20,21 are gradually formed. Secondly, it promotes tensile forces in the end wall portion of the corner regions 20,21 and thus helps to counteract the compressive forces which result from the folding over of the rebates of the side edge flanges.

Referring now to Figures 2(a), 2(b) and 2(c), the corner region is shown folding over to an angle of around 80° each side. It is not possible to close fully the corner region or shells to 90° in a single operation due to the presence of the punch and connection parts to the press.

During the aforementioned entry and gradual progression of the punch into the corrugation 30 and as the shells 10,11 and side flanges 13,14 simultaneously rotate upwards, each corner region 20,21 is further plastically deformed, particularly in the region along the flange rebates 25 adjoining the extremity of the corrugation 30. However, along the corrugation 30 between the corner regions 20,21, relatively little plastic deformation takes place and forming is principally by bending.

The folding over operation is also assisted by lifting arms (not shown) with longitudinal pads along each side of the die. The pads make contact with the shells a small distance from the die. As the folding over operation proceeds, the pads move upwards to assist the lifting and rotating effect on the shells 10,11 caused by the action of the punch and die. They have two principle benefits. Firstly, they reduce the risk of distortion of the shells during the folding over operation by coordinating the movement of the side flange regions and central regions of the shells, as these regions might otherwise move at different rates due to the disparity in the forces generated in the corner and central regions during the folding over operation. Secondly, they generally assist the folding operation and also reduce the risk of excess forces being applied to the workpiece by the punch and die. These may allow the operation to be carried out more effectively and more quickly.

It has been found that slight but visible linear marks along the upper edge of the panel may result from the corrugation forming and folding process. These are caused partly by the bending and subsequent re-straightening of the 90° bends along the edges of the corrugation and partly by distortion formed in the sides of the corrugation by the action of the wider folding punch as it enters the corrugation. The extent of these marks depends on many factors including the hardness of the panel material and the amount of assistance given to the early stages of the folding operation by the lifting arms.

Elimination of the marks is assisted by providing radii which are larger than the conventional size on the 5longitudinal edges of the female folding die tool and also by providing large radii on the 90° longitudinal bends along the corrugation 30.

The marks may also be concealed by providing the upper edge igof the panel with decorative longitudinal steps or embossments in the same regions. The steps or embossments may be formed in the shell pressing operation and may be additionally formed in the folding operation. -] 5Elimination of the marks is also assisted by modifying the corrugation 30 such that it retains the feature of being narrower than the width of the folding punch in the two corner regions 20, 21, but blends out to the full width of the folding punch in the region between the two corner 2oregions 20, 21. The blend region in each case extends to a distance approximately equal to one or two punch widths from the extreme end of the corner bosses of the comer regions 20, 21. Where the corrugation 30 is thus modified, the folding punch will enter the corrugation but will not 25contribute to the folding and rotation upwards of the shells in the region between the two comer regions 20, 21 during the initial part of the folding process. Instead, this folding and rotation upwards is achieved by the lifting arms and is also assisted by the movement of the comer 30regions and the flanged end edges of the panel which continue, as before, to fold and rotate upwards due to the action of the folding punch and die.

Following completion of the folding over operation, the panel is subjected to side forces to close fully the shells together. Reference is made to Figures 3(a), 3(b) and 3(c) showing the corner region fully closed.

The flanges of the side edges are subsequently sealed by resistance seam welding, using rotating wheel electrodes on either side of the abutting flanges. The intersection of the comer region and upper extremity of the side edge is sealed when the electrodes cross the extremity of the seam. Alternatively, the resistance seam welding may be stopped just short of the intersection which is in this instance sealed in a separate fusion welding operation.

The consistent position and short length of the required weld would also facilitate automation of this alternative process.

The side edge seam is subsequently trimmed along its length and the upper extremity in the corner region is further trimmed to avoid the creation of a sharp corner. Reference is made to Figures 4(a) and 4(b) showing the completed welded and trimmed comer. Reference is also made to Figure 5 and Figure 6 which show sectioned views on Figure 4(a) by way of further explanation.

The edges of the material are also provided with small notches 50 (see Figure 1) at the centre of each corner region. The notches facilitate the forming of the comer shape and also promote sharper bending at the apex of the extremities of the flanges of the side edges of the folding over and final shell closing operations, which is advantageous for resistance weld sealing. The notches should not be so deep that they extend beyond the distance into the material where the material is not later removed in the trimming operations.

The preferred embodiment and method has important advantages over the prior art. It eliminates the high labour and material costs involved in closing and sealing the panel corner regions by welding methods including manual oxy-acetylene. It allows a neater and more consistent corner region to be achieved on the finished panel.

It will of course be understood that the invention is not limited to the specific details described herein, which are given by way of example only, and that various modifications and alterations are possible within the scope of the invention as defined in the appended claims.

Claims (21)

CLAIMS :

1 . A method of manufacturing a heat exchanger panel comprising forming a pair of shells from a sheet of metal, and subsequently folding the shells about the longitudinal axis of the junction to provide a panel having a seamless upper edge characterised by forming the junction of the shells and a portion of a corner without seams at one end at least of the junction by working the metal plastically with one or more forming tools so as to form a seamless corner portion adjacent an upper extremity of a side edge seam provided by the contiguous edges of the folded over shells.

2. A method of manufacturing a heat exchanger as claimed in Claim 1, comprising sealing or partially sealing the intersection of the seamless corner portion with the upper extremity of the side edge seam by the side edge sealing means.

3. A method of manufacturing a heat exchanger as claimed in Claim 2, in which the side edge sealing means comprises resistance seam welding.

4. A method of manufacturing a heat exchanger as claimed in any one of the preceding claims, comprising forming a notch at one or each end of the sheet of metal along the longitudinal axis of the junction of the shells.

5. A method of manufacturing a heat exchanger according to any one of the preceding claims, comprising forming the seamless corner portion in one or more forming actions prior to folding the shells so that the metal is more plastically compressed or gathered in the corner than along the junction of the shells between the corners.

6. A method of manufacturing a heat exchanger according to Claim 5, comprising forming a corrugation along the junction of the shells and folding the shells about the longitudinal axis of the corrugation.

7. A method of manufacturing a heat exchanger according to Claim 5 or Claim 6, comprising further forming the corner during the folding over of the panels by working the material plastically with forming tools having shapes corresponding to the shapes required on the seamless corner region.

8. A method of manufacturing a heat exchanger according to Claim 6 or Claim 7, comprising forming the corrugation narrower than the width of the finished upper edge of the panel and gradually widening the corrugation during the folding over of the shells simultaneously with the gradual plastic forming of the corner regions.

9. A method of manufacturing a heat exchanger according to Claim 6 or Claim 7, comprising forming the corrugation narrower than the width of the finished upper edge of the panel in the corner regions and equal to the width of the finished upper edge of the panel in the central region between the corners with the two widths blended in intermediate regions and gradually widening the corrugation in the comer regions during the folding over of the shells simultaneously with the gradual plastic forming of the corner regions.

10. A method of manufacturing a heat exchanger according to any one of the preceding claims comprising using lifting arms to assist in the movement of the shells, the lifting arms having contact surfaces for contacting the side edge flange regions and central regions of the shells to assist in maintaining the alignment of the side edge flange regions and central regions of the panel or to directly assist the folding operation.

11. A heat exchanger panel having a seamless upper edge at the junction of a pair of folded over shells of sheet metal and at least one seamless corner portion at an end of the junction.

12. Apparatus for manufacturing a heat exchanger panel comprising means for forming a pair of shells from a sheet of metal, and means for subsequently folding the shells about the longitudinal axis of the junction to provide a panel having a seamless upper edge characterised in that the apparatus includes one or more forming tools for forming the junction of the shells and a portion of a corner without seams at one end at least of the junction by working the metal plastically so as to form a seamless corner portion adjacent an upper extremity of a side edge seam provided by the contiguous edges of the folded over shells.

13. Apparatus for manufacturing a heat exchanger according to Claim 12, comprising means for forming the seamless corner portion in one or more forming actions prior to folding the shells, so that the metal is more plastically compressed or gathered in the corner than along the junction of the shells between the corners.

14. Apparatus for manufacturing a heat exchanger according to Claim 13, comprising means for forming a corrugation along the junction of the shells and means for folding the shells about the longitudinal axis of the corrugation.

15. Apparatus for manufacturing a heat exchanger according to Claim 13 or Claim 14, comprising forming tools having shapes corresponding to the shapes required on the seamless corner region for further forming the corner during the folding over of the panels by working the material plastically.

16. Apparatus for manufacturing a heat exchanger according to Claim 14 or Claim 15, comprising means for forming the corrugation narrower than the width of the finished upper edge of the panel and gradually widening the corrugation during the folding over of the shells simultaneously with the gradual plastic forming of the corner regions.

17. Apparatus for manufacturing a heat exchanger according to any one of Claims 14 to 16, in which the corrugation forming means is operable to form the corrugation narrower than the width of the finished upper edge of the panel in the corner regions and equal to the width of the finished upper edge of the panel in the central region between the corners with the two widths blended in intermediate regions and means for gradually widening the corrugation in the corner regions during the folding over of the shells simultaneously with the gradual plastic forming of the corner regions.

18. Apparatus for manufacturing a heat exchanger according to any one of Claims 12 to 17 comprising lifting arms operable to assist in the movement of the shells, the lifting arms having contact surfaces for contacting the side edge flange regions and central regions of the shells operable to assist in maintaining the alignment of the side edge flange regions and central regions of the panel or to directly assist the folding operation.

19. A method of manufacturing a heat exchanger substantially as herein described with reference to the accompanying drawings.

20. A heat exchanger panel substantially as herein described with reference to, and as shown in the accompanying drawings.

21. Apparatus for manufacturing a heat exchanger substantially as herein described with reference to, and as shown in the accompanying drawings.