US1972706A - Heat exchanger - Google Patents

Description

Sept. 4, 1934.

R. c. ENGELMAN 1,972,706

HEAT EXCHANGER Original Filed March 20, 1931 5 SheetsShet- 1 INVENTOR OR EY R. c. ENGELMAN HEAT EXCHANGER Sept; 4, 1934.

Original Filed March 20, 1951 5 Sheets-Sheet 2 INVENTOR Ruhr? fi'qgelmaiz g A BY Sept. 4, 1934. R. c. ENGELMAN HEAT EXCHANGER 5 Sheets-Sheet 3 Original Filed March 20. 1931 Sept- 1934. R. c. ENGELMAN' 1,972,706

HEAT EXCHANGER Original Filed March-20, 1931 5 Sheets-Sheet 4 INVENTOR Ruler afi'z gelmqk BY PMMW 1 ATTORNEY Sept. 4, 1934.

R. c. ENGELMAN 1,972,706

HEAT EXCHANGER Original Filed March ZO, 1931 5 Sheets-sheaf 5 j INVENTOR' K0501? aZ'nyeZma/t Wm M ATTORNEY Patented Sept. 4, 1934 UNlTED STATESPATENT OFFICE Robert C. Engelman,

Bradford, Pa., assignor to S. R. Dresser Manufacturing Company, Bradford, Pa., a corporation of Pennsylvania Original application March 20, 1931, Serial No.

6, 1931, Serial No. 1933 12 Claims. (01. 251-124) I My invention consists in the novel features hereinafter described, reference being had to the accompanying drawings, which show several embodiments of my invention selected by me for purposes of illustration, and said invention is fully disclosed in the following description and claims.

This application is a division of my application for improvements in Method of casting fin heating units, filed byme 'on the 20th day of March, 1931, and given Serial Number 523,971,

therewith to forman integral and is directed to the heat exchangers produced by the process therein described and claimed.

My invention relates to heat exchangers, comprising a tubular cast metal body, provided with laterally extending spaced sheet metal fins united structure. Such heat exchangers have been made heretofore by assembling as a built up metallic structure a plurality of apertured spaced metal fin plates, in such manner as to form an exterior mold wall or member, inserting a removable core within said exterior mold wall, supporting the built up structure with the axes of the core and mold wall in vertical position, metal between said mold wall and core and united to the metallic built up structure, as disclosed in Letters Patent No. 1,742,556, granted January 7th, 1930, to John 'Otto Olson, reissued May 19th, 1931, Reissue Nc. 18,078. These heat exchangers may also be produced by providing the built up metallic structure forming the exterior mold wall with a hollow metal core, and pouring the cast metal in like manner, to unite it with the built up metallic structure, and also-to the core, as disclosed in the application of Louis P. Whitaker, filed January 31st, 1931, Serial No. 5123577, which has now matured into Patent No. 1,902,349, issued March 21, 1933, and these heat exchangers may also be produced by forming the built up structure so that it will provide both an exterior mold wall and an interior mold wall (or core) and pouring the cast metal in like manner to unite it to both mold walls of the metallic built up structure, as disclosed in the application of the said Louis P. Whitaker, filed January 31st, 1931, Serial No. 512,576, which has now matured into Patent No. 1,896,501, issued February 2, 1933.

The object of my present invention is to provide heat exchangers formed in part of previand pouring molten Divided and this application October 567,152. Renewed June 20,

ously fabricated metal and in part of cast metal united therewith to form an integral structure, which can be very cheaply and rapidly manufactured, with substantial certainty that they will be free from defects, in which a comparatively thin cast wall maybe formed, and intimately united with the previously fabricated portions, and in which the hollow cast metalbody is provided at one side with a rib extending longitudinally of the unit, and extending between and 60 united to .the opposite edges of slots formed in the previously fabricated fin elements, contributingstrength to the entire unit and facilitatin the transmission of heat from a fluid within the hollow body, to the fln elements, or vice versa. 6

In carrying my invention into effect, I form a metallic built up structure comprising spaced metal fin plates, and metal spacing elements (formed integrally with the plates, or separately therefrom) with similarly shaped apertures in 70 each, having an open slot extending to the exterior edge of the'plate or spacing element. These apertures and slotsare capable of being aligned when assembled in the built up structure to form an exterior mold wall having a longitudinally. extending gate opening extending to the outer edges of the fin. plates and from end to end of the unit. The inner mold wall may be formed by a removable core, of any desired material, by a metallic tube intended to be united with the cast metal and built up structure, or the core may be formed integrally with portions of theouter mold wall, i. e., integral with the spacing elements, or fin plates, or integral with both the spacing elements and fin plates. The assembled built up structure and '85 core (however formed) are then held in position with the axes of the exterior mold wall and core horizontal, or substantially horizontal, and the open gate extending substantially vertically from the exterior mold wall, and the cast metal is poured into the gate opening, until the entire mold and a portion of the gateway, or the entire gate-. way, is filled. The'cast metal, it will be noted, may thus be introduced into the mold throughout its entire length at the same time, or substantially the same time, and has only to pass through the gate opening and around the core, so that the mold is filled very quickly, the contained air having opportunity to escape between the parts of the built up structure, and the cast metal throughout the'entire length of the mold is substantially at the same temperature, and will cool and contract with substantial uniformity.

When the cast metal cools, there will be formed a hollow cast metal body united with the fin plates to form an integral body, and providing a longitudinal continuous cast metal rib atone side of the hollow body, corresponding in width to the gate opening formed in the parts of the builtup structure. This rib provides an important element of strength in the structure, and strengthens not only the hollow body, but also reinforces the spaced fin plates, and it also assists in the rapid transfer of heat from the interior of the hollow body to the fin plates, and vice versa. As a matter of fact, the walls of the hollow body may -be cast thinner than would be desirable if the rib were not present, so that the presence of this rib does not necessarily increase or materially increase the amount of cast metal in the finished article, or the weight of the finished article, while it adds greatly to its strength to resist rough usage, particularly in handling and transportation.

My invention also comprises certain novel features of construction and combination of parts hereinafter fully described and particularly pointed out in the claims.

Referring to the accompanying drawings,

Fig. 1 represents a built up metallic structure comprising fin plates and spacing elements constructed in accordance with my invention and providing an open gateway extending longitudinally thereof, and held in assembled relation in a jig or casting-fixture, in association with a removable core preparatory to receiving the molten metal.

Fig. 2 is an end elevation of the parts shown in Fig. 1, with the end plate of the jig removed.

Fig. 3 is an end elevation of the removable core showing the end opposite that illustrated in Fig. 2.

Fig. 4 is a partial side elevation, partly in section of the completed heat exchanger.

Fig. 5 is a top plan view of the same.

Fig. 6 is an end elevation of the heat exchanger taken from'the left hand end of Fig. 4.

Fig. '7 is a vertical transverse sectional view of the heat exchanger on line 7--7 of Fig. 4.

Fig. 8 is a detail perspective of one of the finplates shown in the preceding figures, having a spacing element formed integral therewith, a portion of the figure being broken away, and an adjacent plate being partially indicated in dotted lines.

of fin plate.

Fig. 10 is a partial view, similar to Fig. 1, showing a slightly'different form of fin plate, and a metallic tubular core to be permanently united to the cast metal and built up metallic structure.

Fig. 11 is a partial elevation, partly in section, and illustrating one end of the completed unit formed in the manner indicated in Fig. 10.

Fig. 12 is a perspective view of one of the fin plates illustrated in Figs. IOTand 11, showing portions ofan adjacent fin plate in dotted lines.

Fig. 13 is a perspective view, partly in section, illustrating a modified form of metallic tubular core formed in section.

v Fig. 14 is a perspective view, partly in section, showing a metallic tubular core formed by winding a metallic strip spirally upon a mandrel.

Fig. 15 is a view similar to Fig. 10, showing a built up structure formed of fin plates provided Fig. 9 is a similar view showing a modified form.

with integral spacing elements and integral core elements connected by a perforated flange.

Fig. 16 is a partial elevation, partly in section, of the completed heat exchanger comprising the built up structure illustrated in Fig. 15.

Fig. 17 is a perspective view, partly broken away, of one of the fin plates illustrated in Figs. 15 and 16, portions of an adjacent fin plate being indicated in dotted lines.

Referring to the embodiment of my invention 3 illustrated in Figs. 1 to 8, and the manner in which the same is carried into effect, I first form a plurality of fin plates and spacing elements so constructed that they may be readily assembled to produce'the desired number of spaced plates for a unit of predetermined length, and form an exterior mold wall surrounding a central chamber, and having a gate opening extending longitudinally throughout the entire series of assembled plates, and open at one edge of each of the same. The preferred form of fin plate which I employ is illustrated in Fig. 8. While the spacing elements which alternate with the fin plates may be made separately therefrom, I find it more convenient to form the spacing element integral with each plate and produce the same by die stamping, or in any other usual or preferred manner. The fin plate, as shown in Fig. 8, comprises the plate proper,

, indicated at 1, provided with an aperture, 2, having an open slot, 3, extending to the upper edge of the plate. Portions of the metal surrounding the edges of the aperture, 2, and slot, 3, are bent into position, substantially perpendicular to the plate, to form a spacing element, 4, which utilizes both the aperture, 2, and the slot, 3. The spacing element, or flange, 4, is also provided in this instance throughout that portion thereof which surrounds the opening, 2, with an inwardly bent interlocking flange, 5, extending in a plane substantially parallel to the plane of the plate, 1, as .clearly indicated in Figs. 1 and. 4, at the lower portions thereof, these interlocking portions being intended to extend into or become embedded in the cast metal. I prefer to dispense with these interlocking portions, 5, throughout the vertical 12f; portions of the spacing flanges, 4, for the reason that by so doing the width of the slot, 3, between the flanges. 4, 4, may be made narrower than would be the case if a sufiicient amount of metal to provide these portions of flanges had to be cut in the formation of the slot, 3. In some instances, however, the interlocking flanges, 5, may be continued throughout the entire spacing flange, 4, as is indicated in Fig. 9, in which the corresponding parts are given the same reference characters, with the addition of the letter a. At the intersection of the spacing flange or element; 4, with the main body of the plate, throughout the slot, 3, and aperture, 2, I prefer to provide a minute recess or inwardly curved portion, indicated at'6, and clearly shown in Fig. 8, to receive the exterior edge of the flange, 4, of the adjacent plate,' indicated in dotted lines in Fig. 8, which permits the nesting of the plates of the series to the extent indicated, and very materially assists in holding 14o them in proper registration when they are assembled, In order to protect the exterior edges of the plates when in the assembled relation, they are provided with auxiliary spacing elements at a distance from the spacing flange, or element, 4, and such auxiliary spacing elements are most conveniently formed by bending a marginal portion of the plate at each side thereof, substantially perpendicular to the body of the plate, as indicated at 7, 7, in Fig. 8. These flanges, '7, will en- 1211 from the casting,

gage the next adjacent plate, as indicated by the dotted lines in Fig. 8, so that at each side of the built up structure, these flanges will present asubstantial continuous surface, avolding sharp corners and also reinforcing the exterior margins of the plates. In some instances the marginal portions of the plates may be further bent inwardly parallel to the plate to form a second flange, 8a, as indicated in Fig. 9, to provide a broader bearing surface to engage the next adjacent plate.

It will be understood that the plates are formed of any suitable metal having a melting point higher than the melting point of the metal to be poured. I find it satisfactory to employ plates of sheet steel, iron, copper, and in some cases aluminum or aluminum alloy, although other metals may be employed. For the cast metal I find it convenient to use aluminum or aluminum alloy, which has a lower melting point than steel, iron or copper, although any suitable casting metal can be employed. Where the casting metal is an aluminum alloy, and it is desired to use plates of aluminum alloy, this can also be readily done by employing an alloy for the plates having a higher melting point than the alloy used for the casting metal.

I assemble the required number of fin plates in spaced relation, with the aperture, 2, and slots, 3, thereof in alignment to form a built up structure in which the spacing flanges, 4, will form an exterior mold wall, and the built up structure is preferably clamped in assembled relation by any suitable means. For example, in Fig. 1, I have shown a jig or casting frame comprising a bottom plate, 9, side plates, 10, and end plates, 11, 11a, secured together in any desired manner, and of a length to receive the built up structure for a heat exchanger unit of predetermined length, and

support a core in operative relation to the built up structure. The end plates, 11, 11a, are preferably provided with recesses, indicated at 12, 12a, communicating with the space between the exterior mold 'wall formed by the built up structure and the core, in order to produce a neat finish at each end of the unit. In Fig. 1, I have shown the end plates, 11, 11a, provided with means for supporting a removable metal core, indicated at 13, which has a cross sectional area corresponding with the main apertures in the plates, and sufficiently smaller to provide a cast wall of the desired thickness, the exterior face ofthe mold wall being separated not only from the exterior mold wall itself, but from the inner edges of the inwardly projecting flanges, 5, as clearly indicated in the drawings. As shown in Fig. 1, the core, 13, which will be provided with the usual draw or taper to permit it to be withdrawn is provided at one end with a cylindrical projection, 13a, which engages an aperture, 14, in the end wall, 11, of the jig, to support the core at that end, and alsoto form a circular aperture in the east end portion, which may afterwards be threaded to receive a pipe connection, and for this reason the end of the core is recessed, as indicated at 132). The opposite end of the core is adapted to enter an aperture or recess, 14a, in the end wall, 11a, of the same cross section as the core itself. The end plates, 11 and 11a, are conveniently detachably connected with the bottom and side walls of the jig, for example, by screws indicated at 15, to facilitate the assembling of the parts and the removal of the unit after casting. The jig is also preferably provided with a pair of gate bars, indicated at 16,

spacing elements thereof, will be 16, having beveled portions, 16a, and also detachably connected with the othenportions of the jig, these gate bars forming a gate, indicated at 17, in line with the longitudinal gate opening formed by the slots, 3, in the plates.

The parts being assembled as shown in Fig. 1, the cast metal is poured into the gate, 1'7, preferably simultaneously throughout the length of the gate, although the molten metal may be poured in from a ladle, which is moved longitudinally of the gate or back and forth above the same. The molten metal will immediately fill the entire space between the core and the exterior mold wall formed by the built up structure, and in this instance will also fill the spaces, 12,

12a, in the end walls of the jig and will also fill the longitudinal gate aperture, and may extend upwardly far enough to fill the entire gate, 1'7, between the gate bars, 16,50 that its upper surface will occupy the position indicated by the dotted line, 18, in which case the excess metal above the upper edges of the plates will be removed at the point indicated by the dotted line, 19, by sawing, milling, chipping or in any other desired manner.

The built up structure and core, and infact the jig, also may be subjected to heat, either before or during the pouring of the cast metal, or at both times, as preferred. It will also be understood that as the cast metal enters the mold area, gases can readily escape at the points of contact between the members of the built up structure without permitting the casting metal to escape from the mold. By this method of casting the metal can be poured throughout the entire length of the mold at substantially the same time so that it will be at uniform temperature throughout the length of the mold,'thus facilitating the casting of the hollow body surrounding the core, and a further advantage of this method is that the cast metal has only a short distance to flow, substantially equal to the vertical transverse diameter of the core, which is only a fraction of the length of the unit. There is, therefore, no tendency for the cast metal to cool in entering the mold, or until the mold is entirely filled and the cast metal being of substantially uniform temperature throughout, will cool and contract uniformly. It will be. seen that the cast metal unites with the exterior mold wall formed by the built up metallic structure, andthat the inwardly projecting flanges, 5, of the plates. or the embedded in the cast metal wall. There will also be formed a longitudinal rib extending along the upper side of the hollow cast metal body and united to the adjacent portions of the flanges, 4, which form the gate opening, and this rib will serve to materially strengthenthe unit and permit of the casting of a thinner wall for the hollow body than would otherwise be necessary.

After the cast metal is cooled, the unit is re moved from the jig or casting frame, and the core, 13, is removed from the cast portion of the unit. The completed unit will then appear as illustrated in Figs. 4 and 5, except that the hollow cast metal body, indicated at 20, and providing the chamber, 21, within the same, will be entirely open at the end, at the left in Fig. 4, from which the core is removed, and the aperture, 22, at the opposite end of the unit, formed by the projection, 13a, of the core, will be unthreaded. In Figs. 4 and 5, 23 represents the longitudinally extending rib along the upper portion of the hollow body, 20. When the unit is formed in the manner just described, it will be completed by inserting at the other end of the chamber, 21, a cast metal closure, 24, formed separately and fitting the core aperture in the casting, and welded in position, as indicated at 25. This closure, 24, is preferably provided with a pipe aperture, 26, which will be interiorly threaded, as shown in Fig. 4, and the pipe aperture, 22, at the other end of the casting will be likewise threaded, as shown.

It will be understood that it would be possible to use, in carrying out my process,.a destructible .core of usual core material, in which case the casting jig or frame would be provided at each end with end plates similar to the end plate 11 shown in Fig. 1 and the core would be formed at both ends in substantially the manner indicated at the right hand end of Fig. 1, and in such case the casting would have an integral wall at each end provided with a pipe aperture therein, through which the granular core could be withdrawn. I prefer, however, to employ a removable core of the kind illustrated in Fig. 1 and previously described, as no difficulty is experienced in closing the open end of the casting by welding therein the closure, 24, illustrated in Fig. 4. In this figure the union of the built up metallic structure comprising the fin plates and their spacing members with the cast metal wall to form an integral structure is clearly shown, and both Figs. 4 and-5 illustrate the position of the reinforcing rib, 23, and its relation to the unit.

Fig. 6 shows an end view of the finished unit taken from the left in Fig. 4, and Fig. '7 shows a transverse sectional view on the line 77 of Fig. 4, looking in the direction of the arrow. The. cross section of the hollow cast metal body may be of any desired form. In the present instance it is of a substantially egg-oval section, which is found advantageous in facilitating the upward passage -of the heated air between the fin plates of the unit and around the cast metal body, but the plates may be stamped or formed-so as to provide an exterior mold wall of different cross section and the core member will-in any case conform to the cross section of the exterior mold wall so formed.

My invention is also applicable to the production of a heat exchanger unit of the type shown in the application of L. P. Whitaker filed January 31, 1931 and given Serial No. 512,577, hereinbefore referred to, in which a non-removable tubular metal core is employed which becomes a part of the unitary structure after the casting is effected. Thus in Fig. 10, I have illustrated a portion of a casting jig showing therein a plurality of assembled fin plates, one of which is shown in detail in Fig. 12, in association with a tubular metal core, 113, adapted to be supported at each end by a portion, 114, on the end wall, 111, of the jig, said portion being surrounded by a recess, 114a, communicating with the space between the core and the exterior mold wall formed by the built'up metallic structure. In this instance the fin plates,

' indicated at 101, are each provided with the aperture, 102, and slot, 103, surrounded by a spacing flange, 104, the spacing flange of each plate being arranged to slightly nest in the spacing element of the adjacent plate, although this is not essential, and forming the gateway or gate opening by the registration of the portions, 104, on opposite sides of the slots, 103. The other parts illustrated in this figure corresponding with those shown in Fig. 1 are given the same reference numerals with the addition of 100.

It will be readily seen that when the cast metal is poured it will unite with the tubular metal core, 113, as well as the built up structure, in-- cluding the fin plates and spacing elements, into an integral structure, as indicated in Fig. 11, which shows one end portion of such structure, partly in elevation and partly in section, the cast metal portions being represented at 120, the interior chamber at 121, and the reinforcing rib at 123. In this case each end of the chamber, 121, will be closed by, means of a closure, 124, similar to that previously described and illustrated in Fig. 4, which in this instance will be fitted to enter the end of the hollow metal core, 113, and will be provided with the necessary pipe aperture, 126, which will be suitably threaded.

In Figs. 10 and 11 the metal core is shown as being formed of an integral tube of the required cross section. Iii some instances, however, the non-removable metal core may be formed of built up sections or rings, as indicated at 213 in Fig. 13, each of said rings having a recess portion, 213a, at one edge to receive the plain edge of an adjacent ring, so that the sections of the core can be nested, and this will assist in assem-' bling them and holding them in assembled relation during the casting operation, while the intersticesbetween the sections of the core will provide additional means for the escape of air and gases from the mold during the casting operation. .In Fig. 14 I have illustrated, at 313, another form of non-removable metallic core, which in this instance is formed by winding a metal strip, indicated at 313a, spirally around a mandrel, to produce the desired tubular cross section, the end portions of the strip being beveled, as indicated at 313b, so that the ends of the tube will be perpendicular to the axis thereof. In using this form of tubular, core, it will be seen that the interstices between the adjacent edges of the spiral strip will also provide means for the escape of air and gases from the mold.

My invention is also applicable to a unit such as is illustrated in the application of L. P. Whitaker filed January 31st, 1931, Serial Number 512,576, in which the built up structure forms not only the exterior mold wall, but also the interior mold wall. Thus, 'in Fig. 17, I have illustrated one of the fin plates, 401, which is provided with an integral spacing flange, 404, and an integral core section, 413, connected to the outer edge of the spacing flange, 404, by a flange, 405, parallel to the plane of the plate, and provided with a plurality of apertures, 405a, for the free distribution therethrough of the casting metal. The spacing flange, 404, surrounds the central aperture, 402, of the plate, and extends vertically to the upper edge of the plate, to form the open slot or gateway, 403, the plate being also provided with the auxiliary spacing flanges, 407. A plurality of these plates are assembled in a suitable jig or casting frame, in the manner indicated in Fig. 15, the parts cfwhich corresponding to those illustrated in Fig. 1, being given the same reference numerals with the addition of 40 0.

It will be seen that the spacing members, 404, form the exterior mold wall, while the core members, 413, form the core or inner mold wall, the mold space between said mold walls being in communication throughout the length of the unit by means of the apertures, 405a. The moltenmetal is poured through the longitudinal gateway, 403, and between the gate bars, 416, in a manner previously described, and the resulting structure is illustrated in Fig. 16, the end portions of the interior chamber, 402, being closed by the closure,

424, welded therein, as previously described, and provided with the pipe aperture, 426. In casting this form of heat exchanger, it will be noted that the interstices between the adjacent spacing flanges, 404, and core flanges, 413, will provide for the escape of air and gases both in an inwardly and an outwardly direction during the pouring of tegrated with the metallic built up structure, and provides the longitudinal reinforcing rib, 423, as shown in Fig. 16.

What I claim and desire Patent is:

1. A heat exchanger, comprising a hollow body of cast metal, provided with an exterior longitudinal reinforcing rib, parallel sheet metal plates, having spacing portions disposed angularly thereto, and united to said hollow body, the portions of said plates adjacent to said reinforcing rib, having spacing portions disposed angularly to the said plates and united to said rib.

2. A heat exchanger comprising a hollow body of cast metal provided with an exterior longitudinal reinforcing rib, parallel sheet metal plates projecting from said hollow body and having angularly disposed spacing portions united to the wall of said hollow body, said spacing portions having inwardly extending flanges embedded in said wall, portions'of said plates on opposite sides of said longitudinal rib being provided with angularly disposed spacing-portions unitedto said rib, said rib engaging spacing portions having inwardly extending portions embedded in said rib. l

'3. A heat exchanger comprising a hollow body of cast metal, parallel fin heating plates united with said hollow body and projecting therefrom, said hollow body being provided exteriorly with a longitudinal reinforcing rib, integral therewith and united to adjacent portions of the fin plates, said hollow body having at an end thereof a closure welded thereto.

to secure by Letters 4. A heat exchanger comprising a hollow body of cast metal, parallel fin heating plates united with said hollow body and projecting therefrom, said hollow body being provided exteriorly with a longitudinal reinforcing rib, integral therewith and united to adjacent portions of the fin plates, said hollow body having at an end thereof a separately formed closure of substantially the size of the bore of said tion therein.

5. A heat exchanger comprising a thin metal tube, a series or" parallel fin plates surrounding provided at one side thereof with aligned open slots extending to the outer edges of the plates, and a hollow body of cast metal uniting said tube and plates into an integral structure and provided with an integral longitudinal reinforcing rib extending through said slots, said plates being provided with angularly disposed spacing flanges extending around said tube at a distance therefrom and united to said hollow body, said plates having angularly disposed spacing fianges on opposite sides of said slots, united to the said longitudinal reinforcing rib.

8. A heat exchanger comprising a thin metal tube comprising a plurality of curved portions separate from each other along adjacent edges, a series of parallel fin plates surrounding said tube and providedat one side thereof with aligned open slots extending to the outer edges of the plates, and a hollow body of cast metal uniting the adjacent portions of the tube to each other the cast metal, which becomes in-' hollow body, and welded in posiand uniting said tube and plates into an integral structure and provided with an integral longitudinal reinforcing rib extending through said slots and united to the plates on opposite sides.

7. A heat exchanger comprising a thin metal tube, comprising a strip of metal formed into a series of spiral coils with their edges in contact, a series of spaced parallel fin plates surrounding said tube and provided at one side thereof with aligned open slots extending to the edges of the plates, and a body of cast metal uniting said tube and plates into an integral structure, and provided at one side with a longitudinal rib extending through said slots and united to said slots on opposite sides.

-8. A heat exchanger comprising a plurality of spaced apertured plates provided with integral spacing flanges, and coreflanges united by spaced connecting portions, said plates having aligned slots at one sideextending from therein to the edges of the plates, and ahollow body of castv metal located between the spacing flanges and core flanges of said plates and forming therewith an integral structure, said cast metal body having at one side thereof an integral longitudinal reinforcing rib extending through said slots.

9. A heat exchanger comprising a plurality of spaced apertured plates provided with integral spacing flanges, and core flanges, united by spaced connecting portions, said plates havinggaligned slots at one side extending from the apertures therein to the edges of the plates, the said spacing flanges having portions on opposite sides of saidslots, and a hollow body of cast metal located between the spacing flanges and the core flanges of said plates and forming therewith an integral structure, said cast metal body having at one side thereof an integral longitudinal reinforcing rib extending through said slots and integrated with the portions of the plates and spacing flanges on opposite sides thereof.

10. A heat exchanger comprising a hollow body of cast metal, a series of parallel apertured fin plates having aligned slots at one side extending from the apertures therein to their outer edges, and integral spacing flanges extending along the edges of the apertures and slots in said plates, the hollow body of cast metal being united to said plates and having a longitudinal reinforcing rib integral therewith extending through said aligned slots in said plates and united to the portions of the spacing flanges on opposite sides thereof.

11. A heat exchanger comprising a hollow body of cast metal, a series of parallel apertured fin plates having aligned ing from the apertures therein to their outer edges, and integral spacing flanges extending along the edges of the apertures and slots in said plates, the hollow body of cast metal bemg tudinal reinforcing rib integral therewith extending through said aligned slots in said plates and united to the portions of the spacing flanges on opposite sides thereof, the portions of said spacing flanges surrounding the apertures therein being provided withinwardly projecting flanges terminating adjacent to the inner ends of said slots, and projecting into the surrounding cast metal.

12. A heat exchanger comprising a thin metal tube composed of successive aligned portions having their edges in contact, a series of .spaced parallel apertured fin plates surrounding said tube the apertures slots at one side extendextending to t a hollow body and plates into i 2,9?2fi06 and. provided at one side'with aligned open slots he outer edges of the plates, end of cast metal uniting said tube an integral structure and pro= 5 vided with an integral longitudinal reinforcing rib extending through the aligned slots in said plates and united to the edges thereof said plates having arugula rly disposed spacing fies stir ROBERT C. ENGE.

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