US3188725A - Method of making a heat exchanger - Google Patents

Description

June 15, 1965 c. BAILYS I 3,183,725

A METHOD OF MAKING A HEAT EXCHANGER Original Filed July 26, 1957 2 Sheets-Sheet 1 June 15, 1965 c. BAILYS 3,188,725 METHOD OF MAKING A HEAT EXCHANGER Original Filed July 26, 1957 2 Sheets-Sheet 2 fnuerzZ'bi-v Ca l #3019:

United 3,188,725 METHOD OF MAKING A HEAT EXCHANGER Carl L. Bailys, Detroit, Mich., assignor to Borg-Warner This application is a division of an earlier filed case 1 Serial Number 674,516, filed July 26, 1957 entitled Heat Exchanger, and now US. Patent 2,991,047.

This invention relates to heat exchangers and, more particularly, to a heat exchanger of the tube sheet type fabricated from a plurality of sheets of metal selectively bonded each to the other at predetermined zones to define intermediate unbonded zones which may be complementally shaped, as by hydroforming and the like, to form spaced tubes for passage of fluid.

This invention is primarily directed to a heat exchanger of the stated type in which a portion of the web between the tubes remains unbonded, in which a plurality of fins are formed in the web and in which the several plies forming the fins are separated to form singlethickness panels so that the total heat exchange surface area is substantially increased.

A primary object of the invention is, therefore, to provide a heat exchanger of the stated type having all of the advantages of the multiple-sheet construction, yet exhibiting a substantial increase in heat transfer area.

Another object of the invention is to provide a heat exchanger of the multiple-sheet type having a plurality of parallel integral tubes separated by webs having a plurality of angularly extending integral fins in heat conductive relation thereto, in which the several plies forming the fins are separated to reduce the effective thickness of the fins and to form passages therebetween for the flow of air to that efficient heat transfer is afforded.

Another object of the invention is to provide a heat exchanger of the type described, in which the fins are integral with the tubes, in intimate heat conducting relation thereto and are so formed to effect turbulence in the heat exchange fluid during the course of its passage therethrough.

A further object of the invention is to provide a heat exchanger; of the stated type characterized by ease of manufacture, efficiency and facility of use, convenience in form, and improved functional characteristics.

A more particular object of the invention is to provide a heat exchanger of the tube sheet type in which a plurality of sheets of similar metal are integrally bonded at preselected zones, in which tubular passages are formed in certain of said unbonded zones for the flow of heat exchange fluid, in which the sheets in others of said unbonded zones are slit or partially severed therefrom to form strips which are bent to assume an angular relation with respect to the plane of the sheets thus forming a plurality of openings for the fiow of heat exchange fluid and in which each strip is separated to form a plurality of single fins for secondary heat exchange between the tubular passages and fluid flowing through the fins.

3,188,725 Patented June 15, 1965 the fin formation is effected in such a manner that torsional stresses are substantially reduced and in which the formation of single-thickness fins is. facilitated.

Other objects and features of the invention will be readily apparent to those skilled in the art from the specification and appended drawings illustrating certain preferred embodiments in which:

FIGURE 1 is a front elevational view of a heat exchanger made in accordance with the present invention;

FIGURE 2 is an edge view showing a preform of the present heat exchanger, in an intermediate state of formation, in which parallel bonded zones of a multiplesheet unit are illustrated.

FIGURE 3 is a view similar to FIGURE 2, but showing a heat exchanger preform in the next subsequent stage of development in which certain of the unbonded zones are formed into spaced parallel tubes for passage of fluid;

FIGURE 4 is an enlarged fragmentary sectional plan view of a heat exchanger fin made in accordance with the present invention;

FIGURE 5 is a sectional plan view taken substantially on line 5-5 of FIGURE 4; and

FIGURE 6 is an enlarged elevational sectional view taken substantially on line 6-6 of FIGURE 4.

Referring now to the drawings and more particularly to FIGURE 1, the heat exchanger of the present inven-- tion is in the form of a tube sheet indicated generally by reference numeral 10 and in the illustrated embodiment includes a first sheet 6 of metal, such as aluminum or the like, and a second sheet 8 of similar metal bondedto the sheet 8 at predetermined zones to define headers consisting of an upper manifold 12 and a lower manifold 14, and a fin unit or matrix 16 interposed therebetween and having a plurality of integrally formed parallel tubes 18 connecting the manifold 12 and the manifold 14 and spaced each from the other by webs 19.

The tubular passages 18 of the present heat exchanger I may be integrally formed by the process of the Reynolds Metal Co. described in the February 1956, issue of the magazine Modern Metals, or by similar processes, such as the Roll-Bond process. In the present disclosure the term tube sheet has the same meaning as in those processes and refers to an integral combination of tubportions of the webs 19 joining adjacent tubes 18, are

slit along parallel lines to form contiguous strips. The strips of each web 19 are shaped, by bending or the like, to form a fin section 20 having a plurality of multiply fins 22 spaced each from the other to define openings 23 therebetween for free passage of cooling fluid, or

fiuid to be cooled, such as air or the like, in a direction substantially perpendicular to the plane of the web 19. It will be noted that the unbonded fin matrix constitutes substantially all of the unbonded areas between the conduits to enhance heat transfer. In the present instance, the fins 22 are angularly disposed with respect to the plane of the web 19 and are desirably bent into the conamenable to separation of the sheets 6 and 8 in the area heat transfer area is of the fins 22 so that the effective substantially increased.

' Referring now more particularly to FIGURES'4 and 5, each of the multi ply fins 22 includes separate panels 24 spaced each from the other to form therebetween passage 26 substantially equal in width to the openings 23. Each of the fin panels 24 may be considered a single-thickness fin and includes-a pair of curved portions 28 extending outwardly in both directions from the plane of the web 19, and a central portion 32 extending substantially perpendicular to the plane of the web 19 and joining the portions 28. It will be noted that the several fin panels 24 diverge each from the other to form the passage 26. The portions 32 are shown as beingparallel each to the other but it will be a-ppreciatedthat they may assume any relation. For instance, the portions 32 may be bowed.

ln forming the heat exchanger of the present invention, the sheets 6 and 8 are provided with a suitable parting compound along parallel paths. Certain of these paths are for the formation of the passages 18 while alternate paths are for the formation of the fins 22. The sheets are then juxtaposed and subjected to a hot rolling .by way of limitation and the scope of my invention is defined solely by the appended claims which should be construed as broadly as the prior art will permit.

I claim! 1. A method for making a heat exchanger of the tube sheettype comprising the steps of integrally bonding two sheets'of metal each to the other along parallel lines to form therebetween unbonded zones, expanding certain of said unbonded zones to form fluid passages, transversely slitting others of said unbonded zones between said fluid passages to form a series of strips, bending said strips to form a series of fins extending angularly to the plane of said sheets, such that each of said fins extend from both sides of the plane of said sheets, and separating the plies of said fins to form a plurality of multi-ply fins.

2. A method of making a heat exchanger of' the tube sheet type comprising the steps of integrally bonding two sheets of material each to the other along parallellines to form therebetween tube and fin unbonded zones, expanding said tube unbonded zones hydraulically to form fluid passages, transversely slitting said fin unbonded zones to operation to join the sheets in-the zones between the paths of parting compound. The passages 18 are then hydraulically formed inthe conventional manner so that the blank assumes the configuration shown in FIGURE 3.

The blank is then provided with a plurality of spaced parallel slits between each pair of tubes ,18. The'strips between each pair of slits are then bent to form the multiply fins 22. Then the fins'22 are split by means of a wedge, drift, or other suitable means to form the separate panels or single-thickness fins 24. It is contemplated that the panels 24 of the several fins 22 may be conveniently separated simultaneously.

It will be apparent from; the foregoing description that when the present device is used, for example, as 'a heat exchanger for an air conditioning systemithat fluid to be cooled or liquified may pass intothe upper manifold 12 and thence downwardly through the several tubes 18 to the manifold 14. During the course of 'its passage, the fluid is subject to heat exchange with air flowing through: the openings between the several multi-ply fins 22 and through the passages 26 defined by the several singlethickness panels forming a part of each fin 22. It will be appreciatedthat the air may be at a temperature level.

higher or lower than the temperature level of the fluid. The air flows into contact with the several tubes 18 to effect primary heat exchange, while secondary heat exchange is afforded by contact of the air with the several panels 24 of the fins 22. In the present construction free flow of heat between the tubes 18 and the fins 22 is made possible by the fact that the portions of the intervening. webs are integrally bonded, there being no solder or brazing therebetween to hinder this flow of heat. The gradual curvature .of the distorted portions28 assumes freedom from torsional stress in these areas.

The heat exchanger of the present invention exhibits important advantages over prior constructions in that the conduction of heat from the walls defining the passages 18 to the fins 22 is facilitated, since both sides of the fin panels 24 are exposed to the flow of air. Since the thickness of each section is only a fraction of the thickness of the composite blank, the passage of heat from the fin panels is enhanced. The present heat exchanger is a' unitary structure which may be conveniently formed- According to the present method, the passages 18 may be formed after the slitting step, if desired.

While'I'have described my invention in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not form a series of contiguous parallel strips, bending said strips to form angularly extending fins and to form openings encompassing the major area of said fin unbonded zone therebetween, and separating the sheets of said fins to form separatesingle-thickness multi-ply fins.

3. A method of making a heat exchanger of the sheettube type wherein two plies of heat conductive sheet material are bonded together at certain areas, comprising the following steps: 'sandwiching strips of separation material between said two plies of heat conductive sheet material to define spaced apart fluid 'header patterns and a plurality of spaced apart conduit patterns and to define web patterns in a zone intermediate said spaced apart conduit patterns and separated from said conduit patterns and separated from said header patterns and bonding said plies together at zones not protected by the separation material to accomplish thereat total integration of one ply to the other ply and forming a sheet-tube means; expanding certain of said unbonded zones hydraulically" to form fluid head rs interconnected by a system of conduits and having sa conduits each separated by webbing comprising said two plies. in contiguous unexpanded and unbonded relation; providing slits in said web,- bings extending laterally through both of the plies and extending along'the plane of the webbing substantially between the bonded zones circumscribing each said webbing, said slits being provided in a pattern to form generally elongate panels each having opposite ends integrally connected to the sheet-tube means; turning said panels with the said two plies in contiguous relation from the plane of .the webbing about a longitudinal axis of the panels in a direction transverse to the plane of the webbing to permit heat exchange fluid to pass through the plane of the webbing; and separating the contiguous plies ,of said turned panels to form regularly laterally spaced heat exchanger fins which maximize the efficiency of the device.

4. A method of making a heat exchanger of the sheet- 7 tube type wherein two plies of heat conductive sheet material arej'bonded together at certain areas, comprising the following steps: sandwiching strips of separation material between said two plies of heat conductive sheet material to definespaced apart conduit patterns and to define web patterns in a zone intermediate saidspaced apart conduit patterns and separated from said spaced apart conduit patterns and bonding said plies together webbing substantially between the bonded zones circumscribing each said webbing to form a plurality of double ply panels; turning said panels with said two plies in contiguous relation from the plane of the webbing in a direction transverse to the plane of the webbing to permit 5 heat exchange fluid to pass through said webbing plane; and laterally separating the contiguous plies of said turned panels to form regularly spaced heat exchanger fins which maximize the efficiency of the device.

6 References Cited by the Examiner UNITED STATES PATENTS 2,759,247 8/56 Grenell et a1 29-1573 2,856,164 10/58 Adams 2 9l57.3 2,999,308 9/61 Pauls 29--157.3

WHITMORE A. WILTZ, Primary Examiner.

HYLAND BIZOT, Examiner.

Claims (1)

1. A METHOD FOR MAKING A HEAT EXCHANGER OF THE TUBE SHEET TYPE COMPRISING THE STEPS OF INTEGRALLY BONDING TWO SHEETS OF METAL EACH TO THE OTHER ALONG PARALLEL LINES TO FORM THEREBETWEEN UNBONDED ZONES, EXPANDING CRETAIN OF SAID UNBONDED ZONES TO FORM FLUID PASSAGES, TRANSVERSELY SLITTING OTHERS OF SAID UNBONDED ZONES BETWEEN SAID FLUID PASSAGES TO FORM A SERIES OF STRIPS, BENDING SAID STRIPS TO FORM A SERIES OF FINS EXTENDING ANGULARLY TO THE PLANE OF SAID SHEETS, SUCH THAT EACH OF SAID FINS EXTEND FROM BOTH SIDES OF THE PLANE OF SAID SHEETS, AND SEPARATING THE PLIES OF SAID FINS TO FORM A PLURALITY OF MULTI-PLY FINS.

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