US3673846A

US3673846A - Heat exchangers

Info

Publication number: US3673846A
Application number: US32533A
Authority: US
Inventors: Henry John Levington; Charles Keith Clark
Original assignee: Associated Engineering Ltd
Current assignee: Associated Engineering Ltd
Priority date: 1969-05-09
Filing date: 1970-04-28
Publication date: 1972-07-04
Anticipated expiration: 1989-07-04
Also published as: SE396893B; GB1301665A

Abstract

This invention relates to an apparatus for producing a heat exchanger fin structure of the type disclosed in FIGS. 1 to 3 of copending U.S. Pat. application Ser. No. 755077. The apparatus comprises means for feeding the corrugated strip forming the fin structure along the direction of the longitudinal plane of the structure to pass restraining means engaging with the corner of an area forming a fin to temporarily restrain or stop the motion of a fin area until at least the next following fin area is inclined towards the restrained area, whereafter the restraining means yield to allow the thus converged fins so formed to pass said means, whereby the resulting corrugated structure has the adjacent fins, extending from either side of a region converging towards each other.

Description

O United States Patent 1 1 3,673,846

Levington et al, July 4, 1972 1 HEAT EXCHANGERS 2,909,138 10/1959 Lawson ..72/l86 [72] Inventors: Henry John Levington; Charles Keith fi g Clark both of Leamington S a En land i i p g l,0l8,399 2/l9l2 Llvmgston 72/l87 73 1 Assignee: Associated Engineering Limited, Leaming- 3 1946 Watt et ton Spa, Engkmd 3,160,132 12/1964 Mowatt ,.l l3/l 18 [22] Filed: April 28, 1970 Primary Examiner-Lowell A. Larson {211 App], N0: 32 533 ArtorneyHolcombe,Wetherill & Brisebois [57] ABSTRACT {30] Fol-fig Application Prmmy Data This invention relates to an apparatus for producing a heat May 9, 1969 Great Britain ..23,835/69 exchanger fin structure of the type disclosed in FIGS, 1 to 3 of copending US. Patv application Ser, No. 755077, The ap- {521 U.S.Cl ,72/326,72/384 72/405 paratus comprises means for feeding the corrugated strip 113/11 R forming the fin structure along the direction of the longitu [51] Int. Cl B211! 53/04 dinal P of the Structure to P restraining means engaging 581 Field of Search ..72 1 so, 187, 381, 383, 384, with the comet Oran area forming a fin to temporarily rcslrain 72/385. 325, 306, 379, 404, 405, 326' ll3/l 18 R 1 or stop the motion ofa fin area until at least the next following fin area is inclined towards the restrained area, whereatter the restraining means yield to allow the thus converged fins so [56] Re'erences Cited formed to pass said means, whereby the resulting corrugated structure has the adjacent fins, extending from either side of 21 UNITED STATES PATENTS region converging towards each other,

767,883 8/1904 Grafton ..72/l87 15 Claims, ll Drawing Figures is L 4 6 7 2 G av -rm i 22444 l HEAT EXCHANGERS The present invention relates to a method and apparatus for forming a heat exchanger fin structure of the type disclosed in FIGS. 1 to 3 of our co-pending U.S. Pat. application Ser. No. 755077 and now US. Pat. No. 3,521,707.

Such a fin structure comprises a metal strip, for example a strip of aluminum foil having a thickness of approximately 0.005 inch, which is shaped to a corrugated form having areas forming fins alternating with and extending between regions intended to be bonded to heat-exchange members, which regions lie in two planes respectively located on opposite sides of the median longitudinal plane of the corrugated structure and having the fins inclined with respect to each other such that the adjacent fins extending from either side of a region converge towards each other.

According to the present invention, the strip is first shaped to form a corrugated structure with the fins extending from either side of a region diverging from each other, or being substantially normal to the said regions, whereafter this corrugated structure is fed along the direction of the longitudinal plane of the structure to pass between resilient restraining means located at least on one side of said corrugated structure and which engage with the corners between an area forming a fin and a region to temporarily restrain or stop the motion of a fin area until at least the next following fin area is inclined towards the restrained area, whereafter the resilient restraining means yield to allow the thus converged fins so formed to pass said means, whereby the resulting corrugated structure has the adjacent fins, extending from either side of a region, converging towards each other.

The corrugated structure may be driven towards the restraining means by means of rotating endless belts arranged on opposite sides of the structure, so that it passes between the belts which frictionally engage with the said regions or the side edges of the structure to move the structure through the gap between the belts, as they are driven in rotation.

The resilient restraining means may comprise a spring pressed member arranged on either side of the corrugated structure, the members being offset with respect to one another, each member having a shoulder portion which can engage with the corner between a fin area and a region but which is yieldable to allow the corrugated structure to pass therebetween upon a following fin area being inclined towards an area which is restrained by one or more of the resilient means.

Preferably the offset is half the length of a said region, measured in the direction of movement of the structure.

Advantageously each of the fin areas is provided with louvres and the louvres preferably project from both sides of the plane ofthe fin.

The invention also provides a press tool for forming a louvred corrugated structure from a strip of metal. The press tool may include a first section for forming the corrugations and completely fonning the louvres and a second section for locating the corrugated and louvred strips while a further louvred corrugation is formed by the first section. Alternatively, the press tool may include a first section for forming the corrugations and partially forming the louvres and a second section for completing the formation of the louvres. In another arrangement the press tool includes a first section for forming the corrugations, a second section for partially forming the louvres and a third section for completing the formation of the louvres.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic representation of one embodiment of a press tool for forming corrugations and louvres in a metal strip,

FIG. 2 is a section through a louvre in a partly-formed state,

FIG. 3 is a diagrammatic drawing of one embodiment of apparatus for carrying out the method of forming converging fins according to the invention,

FIG. 4 is a diagram of a section of the louvred and corrugated structure when partially formed.

FIG. 5 is a diagram of the structure as prepared for a subsequent operation,

FIG. 6 is a diagram illustrating the subsequent operation,

FIG. 7 is a diagram of the structure after the operation of FIG. 6,

FIG. 8 is a perspective view of the completed corrugated fin structure,

FIG. 9 is a section through a completed fin on the line IX- IX of FIG. 8,

FIG. 10 shows a modification to the press tool of FIG. I; and

FIG. II is a diagrammatic view of a modification to the apparatus of FIGS. 3 and 6.

Referring to FIG. 1, there is shown diagramatically one form of press tool for forming the corrugated structure and louvres. The continuous strip of metal 9 is fed in steps to the first tool section comprising a die cavity 10 and punch ll. When the punch 11 descends into the die cavity I0, with the strip 9 held by spring-loaded plunger 16, one corrugation, having fin areas I joined by a region 2, is formed in the strip. which is drawn into the die cavity. The corrugation so formed is ejected from the die by ejector l2, and the strip is stepped forward, by a gripper mechanism G on each side of the press tool, by a distance corresponding to the pitch of the corrugations, so that the corrugation so formed enters the next tool section comprising the die cavity 13 and punch I4. This die cavity and punch are fashioned to co-operate together to partly form the louvres 7 and 8 (see FIG. 8) in the fin areas I of each corrugation. The louvres formed project only into the die I3 as shown in FIG. 2. The louvred corrugation is stripped from the punch 14 by spring-urged plungers I6 and I7, which are carried by the punch housing 18. The mechanism allows the punches I], 14 to leave the strip before the ejector l5 ejects the part-louvred corrugation from the die 13. The corrugated strip is then transferred by the gripper mechanism G by one pitch to the next position, placing the part-louvred corrugation under the plunger l7. It is arranged that the plunger I7 enters the corresponding die 20 before the punches II and I4 are fully engaged, and provides a location and grip for the corrugated strip. The plunger I7 is also fashioned to complete the

louvres

7 and 8, in the fin area I of the corrugation, so that the louvres extend on both sides of each of the fins l as seen in FIG. 9. The corrugated and louvred structure so formed is then ejected from the third die 20 by ejector [9. The corrugated and louvred structure so formed can then be fed to the apparatus to be described with reference to FIG. 3. The three press tool sections I0 and 11, I3 and 14, I7 and 20 can be operated together so that whilst a corrugation is being formed by the first tool, part louvres are being formed by the second tool, and the complete louvres are being formed by the third tool, the strip being stepped forward during the period when the punches are raised clear of the dies.

Referring now to FIG. 3, the strip of metal foil, e.g. aluminum foil having a thickness of 0.005 inch, is now in the form of a corrugated structure, comprising areas forming fins I alternating with and extending between regions 2 intended to be bonded to heat exchange members. The regions 2 lie altemately in two planes respectively located on opposite sides of the median longitudinal plane AA of the corrugated structure. For the sake of simplicity, the louvres formed in the fins l have been omitted from FIG. 3. This structure is fed through the gap between two endless belts 3, which pass over drive rollers 4 and have a section 30 in contact with the adjacent regions 2 of the corrugated structure. Thus, when the belts 3 are driven in rotation in opposite directions, the corrugated structure is fed through the gap between the belts in the direction of the arrows B. The corrugated structure is then fed through two restraining means comprising spring-urged plates 5 having shoulders 6 which can respectively engage with the comers 21 between each fin I and region 2 in order temporarily to restrain or stop the motion of the corrugated structure. The plates 5 are offset by a distance 0 equal to half the length of the regions 2 measured in the direction of motion. With this arrangement, as the corrugations pass between the belts 3 and approach the restraining means 5, they tend to close up on each other from their initial form in which the fins on either side of a region are divergent, and thereby cause at least the fin adjacent that held by the restraining means to incline towards the restrained fin. This closing up of the fins has the effect of stiffening the portion of the corrugated structure immediately preceding the restraining means and builds up a sufficient force to cause the plates 5 to yield to allow passage of the converged fins so formed. Thus, at the output side of the restraining means is formed a corrugated structure having the fins 1 extending from either side ofa region 2 converging towards each other. Although the corrugations are fully closed in passing through the apparatus, they then spring slightly open again as seen in FIG. 4. To ensure that the structure in its finished form has the corrugations substantially fully closed, the structure is then held in the fully closed position and subjected to a pressing operation, the pressure being applied substantially at right angles to the regions 2. The pressing operation is carried out on the fins, when in the configuration shown in FIG. 5, by a press tool shown in FIG. 6 having a base 30 and a top tool 31, the latter being provided with solid side strips 32 which contact the base 30 and control the height of the pressed corrugated structure. This emerges from the press tool with the regions 2 flattened, and the angles between regions 2 and fins l sharpened, as shown in FIG. 7.

FIG. 8 is a perspective view of a part of the resulting fin structure also showing the

louvres

7, 8. The louvres in each fin I are divided into two groups with the louvres 7 in one group inclined in the opposite direction to the louvres 8 in the other group and with all the louvres projecting from both sides of the plane of the fin.

FIG. 9 shows a section through the fin in the region of the louvres and also shows the saw-tooth shape of the louvreforming portions of the die cavity 13 and punch 14 which are employed so as completely to form the louvres so that they extend from both sides of the fins, as described hereinafter with reference to FIG. 10.

It will be understood that various modifications may be made. For example, other means may be used for forming corrugations in the strip besides the tool shown in FIG. 1. Moreover other arrangements of louvres may be provided instead of that specifically described.

In one modification of the press tool shown in FIG. 1 for forming the corrugations and louvres in the metal strip, the first tool section comprising die cavity 10 and punch ll are omitted and die cavity 13 and punch 14 are employed both to form the corrugations in the strip 9 and also simultaneously to partially form the louvres. The plunger 17 and die cavity 20 complete the formation of the louvres as previously.

A further modified form of the press tool is shown in FIG. l0, wherein corresponding parts hear the same reference nu merals as in FIG. I. In this construction the die cavity 13 and punch 14 are employed both to form the corrugations and completely to form the louvres so that they extend from both sides of the fins, as shown in FIG. 9. The ejector 12 is continued up to the line of the incoming foil strip 9 and is associated with a gate 120 to control the vertical movement of the strip. The ejector 12 works up and down in conjunction with ejectors l5 and 19. The plunger 17 is used only for location purposes and is relieved at 17a so as not to foul the louvres, but serves to clamp the fin sections into the die cavity 20 by engaging the flat portions of the fins.

In another modification shown in FIG. ll, the pressing operation described with reference to FIG. 6 may be carried out by arranging the press tool immediately following the spring-urged plates 5. In this case the side strips 32 (FIG. 6) are preferably attached to the base and the top plate 31a is spring-loaded by springs 34 and is hammered on to the side strips 32 by means ofa cam 33 driven, e.g., by an electric motor, at a speed of about I000 r.p.m, or higher. A further spring-urged plate 50 is positioned after the intermittent pressing or hammering station to maintain the fin form in the fully closed position during this operation,

in yet a further modification, the spring-urged plates 5 may be replaced by guide plates 25 (shown in broken lines in FIG. 11), movement of the strip being restrained by a single springurged plate 5a downstream of the intermittent pressing or hammering

station

30, 31a (or alternatively by two plates 50, one cooperating with each set of regions 2 of the strip).

We claim:

1. Apparatus for producing a fin structure consisting of a metal strip shaped to a corrugated form having areas forming fins alternating with and extending between regions which lie in two planes respectively located on opposite sides of the median longitudinal plane of the corrugated structure and having the fins inclined with respect to each other, such that the adjacent fins extending from either side of a region converge towards each other; said apparatus comprising means for shaping the strip to form a corrugated structure with the fins extending from either side of a region diverging from each other, or being substantially normal to the said regions, and means for feeding said corrugated structure along the direction of the longitudinal plane of the structure to pass restraining means located at least on one side of said corrugated structure, each said restraining means engaging with the corner between an area forming a fin and a region to temporarily restrain or stop the motion of a fin area until at least the next following fin area is inclined towards the restrained area, whereafter the restraining means yield to allow the thus converged fins so formed to pass said means, whereby the resulting corrugated structure has the adjacent fins, extending from either side of a region, converging towards each other.

2. Apparatus as claimed in claim 1, wherein the corrugated structure is driven towards the restraining means by means of rotating endless belts arranged on opposite sides of the structure so that it passes between the belts which frictionally engage with the said regions to move the structure through the gap between the belts as they are driven in rotation.

3. Apparatus as claimed in claim 1, wherein the resilient restraining means comprise a spring-pressed member arranged on either side of the corrugated structure, the mem bers being offset with respect to one another and each member having a shoulder portion which can engage with the corner between a fin area and a region but which is yieldable to allow the corrugated structure to pass therebetween upon a following fin area being inclined towards an area which is restrained.

4. Apparatus as claimed in claim l, including means for providing each of the fin areas with louvres, wherein the louvres are formed by said means for shaping the strip to form a corrugated structure, said means including a press tool.

5. Apparatus as claimed in claim 4, wherein the press tool includes a first section for forming the corrugations and par tially forming the louvres and a second section for completing the formation of the louvres.

6. Apparatus as claimed in claim 4, wherein the press tool includes a first section for forming the corrugations, a second section for partially forming the louvres and a third section for completing the formation of the louvres.

7. Apparatus as claimed in claim 1, including means for subjecting the corrugated structure to a further operation to ensure that the structure in its finished form has the corrugations substantially fully closed.

8. Apparatus as claimed in claim 7, including means for subjecting said corrugated structure to an intermittent pressing operation, the pressure being applied substantially at right angles to said regions, and means for restraining the corrugated structure at a position beyond the station where the intermittent pressing operation is carried out, to assist in maintaining the corrugations in the fully closed position during this operation.

9. Apparatus for producing a fin structure consisting of a metal strip shaped to a corrugated form having areas forming fins alternating with and extending between regions which lie in two planes respectively located on opposite sides of the median longitudinal plane of the corrugated structure and having the fins inclined with respect to each other, said apparatus including punch and die means for shaping the strip to form a corrugated structure with the fins which extend from either side of a region diverging from each other, said punch having two flank faces each formed with serrations. and said die means having two flank faces formed with co-operating serrations, whereby on reciprocation of the punch relative to the die the strip is corrugated and at least partially formed with louvres and wherein the serrations of said die means consist solely of indentations and the serrations of said punch means consist solely of projections, so that louvres are formed in he strip which extend on one side only of the strip, said apparatus including further punch and die means for completing said louvres so that they extend on both sides of the strip.

l0. Apparatus for producing a fin structure consisting of a metal strip shaped to a corrugated form having areas forming fins alternating with and extending between regions which lie in two planes respectively located on opposite sides of the median longitudinal plane of the corrugated structure and having the fins inclined with respect to each other, such that the adjacent fins extending from either side of a region converge towards each other; said apparatus comprising means for feeding said corrugated strip in a direction parallel to said median longitudinal plane, means in contact with said corrugated strip to restrain movement thereof, said means compris ing a resiliently-loaded member having a shoulder which engages with successive corners between said fins and those regions which lie in one of said two planes, whereby to cause the corrugations to close up toward one another, at least the fin next to the restrained fin being thus caused to incline toward the restrained fin.

11, Apparatus as claimed in claim 10, wherein said means for feeding said corrugated strip comprises a pair of endless belts, each belt having a section in contact with a number of said regions.

[2. Apparatus as claimed in claim 10, wherein two said restraining means are provided, one co-operating with succes sive corners between the fins and those regions in one of said planes and the other co-operating with successive corners between the fins and those regions in the other of said planes,

the two restraining means being offset from one another relative to the direction of motion of the strip.

13. Apparatus for producing a fin structure consisting of a metal strip shaped to a corrugated form having areas forming fins alternating with and extending between regions which lie in two planes respectively located on opposite sides of the median longitudinal plane of the corrugated structure and having the fins inclined with respect to each other, such that the adjacent fins extending from either side of a region converge towards each other; said apparatus comprising means for holding said corrugated strip with the corrugations in a closed-up configuration, and pressing means comprising a base and a top tool, the base having a surface in one of the two planes and in contact with a number of the regions of the strip and the top tool having a surface in the other of the two planes and in contact with a number of the alternate regions of the strip and means to subject the strip to an intermittent pressure between the top tool and the base, the pressure being applied in a direction substantially at right angles to the regions.

14. Apparatus as claimed in claim 13 wherein said means to subject the strip to an intermittent pressure includes a cam arranged on each rotation to load the top tool relative to the base, and means to rotate the cam.

15. A press tool for forming a louvred corrugated structure from a strip of metal, including a first section comprising die means including a die cavity having a saw-tooth-section portion, the saw-teeth extending on both sides of the median plane of the face of the die cavity, and punch means having a corresponding saw-tooth-section portion to mate with the saw-tooth-section portion of the die cavity, whereby in a single operation the corrugations are formed, and the louvres are completely formed so that they extend from both sides of the strip of metal, said press tool also includin a second section comprising co'operatmg plunger means an second die cavity means in which the louvred corrugated strip is positioned and located, said plunger means and said second die cavity means being relieved to clear the louvres, whereby the plunger means and the second die cavity means engage only with flat portions of the strip to clamp the strip while the corrugations and louvres are formed in said first section.

Claims

3. Apparatus as claimed in claim 1, wherein the resilient restraining means comprise a spring-pressed member arranged on either side of the corrugated structure, the members being offset with respect to one another and each member having a shoulder portion which can engage with the corner between a fin area and a region but which is yieldable to allow the corrugated structure to pass therebetween upon a following fin area being inclined towards an area which is restrained.

4. Apparatus as claimed in claim 1, including means for providing each of the fin areas with louvres, wherein the louvres are formed by said means for shaping the strip to form a corrugated structure, said means including a press tool.

5. Apparatus as claimed in claim 4, wherein the press tool includes a first section for forming the corrugations and partially forming the louvres and a second section for completing the formation of the louvres.

9. Apparatus for producing a fin structure consisting of a metal strip shaped to a corrugated form having areas forming fins alternating with and extending between regions which lie in two planes respectively located on opposite sides of the median longitudinal plane of the corrugated structure and having the fins inclined with respect to each other, said apparatus including punch and die means for shaping the strip to form a corrugated structure with the fins which extend from either side of a region diverging from each other, said punch having two flank faces each formed with serrations, and said die means having two flank faces formed with co-operating serrations, whereby on reciprocation of the punch relative to the die the strip is corrugated and at least partially formed with louvres and wherein the serrations of said die means consist solely of indentations and the serrations of said punch means consist solely of projections, so that louvres are formed in he strip which extend on one side only of the strip, said apparatus including further punch and die means for completing said louvres so that they extend on both sides of the strip.

10. Apparatus for producing a fin structure consisting of a metal strip shaped to a corrugated form having areas forming fins alternating with and extending between regions which lie in two planes respectively located on opposite sides of the median longitudinal plane of the corrugated structure and having the fins inclined with respect to each other, such that the adjacent fins extending from either side of a region converge towards each other; said apparatus comprising means for feeding said corrugated strip in a direction parallel to said median longitudinal plane, means in contact with said corrugated stRip to restrain movement thereof, said means comprising a resiliently-loaded member having a shoulder which engages with successive corners between said fins and those regions which lie in one of said two planes, whereby to cause the corrugations to close up toward one another, at least the fin next to the restrained fin being thus caused to incline toward the restrained fin.

11. Apparatus as claimed in claim 10, wherein said means for feeding said corrugated strip comprises a pair of endless belts, each belt having a section in contact with a number of said regions.

12. Apparatus as claimed in claim 10, wherein two said restraining means are provided, one co-operating with successive corners between the fins and those regions in one of said planes and the other co-operating with successive corners between the fins and those regions in the other of said planes, the two restraining means being offset from one another relative to the direction of motion of the strip.

15. A press tool for forming a louvred corrugated structure from a strip of metal, including a first section comprising die means including a die cavity having a saw-tooth-section portion, the saw-teeth extending on both sides of the median plane of the face of the die cavity, and punch means having a corresponding saw-tooth-section portion to mate with the saw-tooth-section portion of the die cavity, whereby in a single operation the corrugations are formed, and the louvres are completely formed so that they extend from both sides of the strip of metal, said press tool also including a second section comprising co-operating plunger means and second die cavity means in which the louvred corrugated strip is positioned and located, said plunger means and said second die cavity means being relieved to clear the louvres, whereby the plunger means and the second die cavity means engage only with flat portions of the strip to clamp the strip while the corrugations and louvres are formed in said first section.