US2983300A

US2983300A - Manufacture of heat exchange structures

Info

Publication number: US2983300A
Application number: US815598A
Authority: US
Inventors: Roy W Abbott
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1959-05-25
Filing date: 1959-05-25
Publication date: 1961-05-09
Anticipated expiration: 1978-05-09

Description

y 9, 1961 R. w. ABBOTT 2,983,300

MANUFACTURE OF HEAT EXCHANGE STRUCTURES Filed May 25, 1959 4 Sheets-Sheet 1 F'IGI INVENTOR ROY W. ABBOTT BY W H l 5 ATTORNEY May 9, 1961 R. w. ABBOTT 2,933,300

MANUFACTURE OF HEAT EXCHANGE STRUCTURES Filed May 25, 1959 4 Sheets-Sheet 2 F'IG.2

INVENTOR F- 3 R'ov w. ABBOTT H l 5 ATTORNEY May 9, 1961 Filed May 25, 1959 FM IO R. W. ABBOTT MANUFACTURE OF HEAT EXCHANGE STRUCTURES 4 Sheets-Sheet 3 INVENTOR.

ROY w. ABBOTT ATTORNEY y 1951 R. w. ABBOTT 2,983,300

MANUFACTURE OF HEAT EXCHANGE STRUCTURES Filed May 25, 1959 4 Sheets-Sheet 4 FIG. 6

FIG. )2

INVENTOR.

ROY w. ABBOTT HIS ATTORNEY United States Patent MANUFACTURE OF HEAT EXCHANGE STRUCTURES Roy W. Abbott, Jetfersontown, Ky., assign'or to General Electric Company, a corporation of New York Filed May as, 1959, Ser. No. 815,598

12 Claims. c1. 153-2 The present invention relates to the manufacture of heat exchange structures and more particularly to the manufacture of such structures from heat exchange tubing of the type including a central tube surrounded by a multiplicity of narrow individual fin sections, or

. spine sections, extending from the surface thereof.

One form of heat exchange tubing with which the present invention is particularly concerned is manufactured by helically wrapping onto a tubing an 'L-shaped strip of fin stock with one leg of the L-shaped fin being in flatwise engagement upon the tubing and with the other leg of the L-shaped fin being serrated into a plurality of individual or spine-like fin sections. The spinelike fin sections spread during wrapping so that each section extends radially outward from the tubing. For ease of description, the above-described type of heat exchange tubing will hereinafter be referred to in the specification and claims as spine fin tubing. Because of the manner of forming the spine sections of spine fin tubing, they are easily bent or collapsed whenever force is applied upon the individual spine sections in the direction normal to the bend in the L-shaped fin structure. More specifically, these spine sections are easily bent or collapsed Whenever they encounter a force applied in a direction along the axis of the tubing. For this reason, much difiiculty is encountered in fabricating spine fin tubing into heat exchange structures having a plurality of passes of tubing. That is, it is difficult to wind or form overlapping coils of this type of heat exchange tubing one upon the other because the outwardly extending spine sections of the adjacent passes of tubing interlock during the winding of the coils and the winding or coiling force along the axis of the tubing causes these interlocking spine sections to collapse or bend over against the tube surface. Because a component of force along the axis of the tubing is always present during a winding or coiling operation, one coil of tubing cannot be formed directly over a previous coil. 7

It is an object of the present invention to provide an improved method for fabricating coiled heat exchange structures from spine fin tubing,

It is another object of the present invention to provide a method of manufacturing a heat exchange structure from spine fin tubing in which the structure comprises at least one row of overlapping coils gradually increasing in circumference with the individual fin sections of the adjacent coils interlocking to maintain the structure in substantially flat shape.

It is a further object of the present invention to provide a machine for manufacturing a heat exchange 2,983,300 Patented May 9, 196 1 structure having a plurality of overlapping coils of spine fin tubing.

Further objects and advantages of the invention will become apparent as the following description proceeds and the features of novelty which characterize the 'invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

In carrying out the objects of the present invention there is provided a method of manufacturing a heat exchange structure comprising the steps of providing a length of spine fin tubing, forming this length of spine fin tubing into a plurality of helical coils with the first coil of relatively small circumference and With each succeeding coil increasing in outer circumference over that of the preceding coil but having an inner circumference slightly less than the outer circumference of the preceding coil, and compressing the coils axially relative to each other to telescope the inner coils into the outer coils with the spine sections of the adjacent coils sliding between each other and interlocking to hold the coils overlapped in a single row and substantially fiat in shape.

As a further aspect of the present invention there is provided a machine for manufacturing a heat exchange structure from a length of spine fin tubing according to the above-described method. The machine comprises a pyramid-shaped coil forming fixture having a collapsible coil forming member. The coil forming member comprises a length of spring-like material helically wound into a plurality of coils each increasing in circumference over the previous coil and overlapping the previous coil. The coil forming member presents a continuous peripheral winding surface, with the surface of each successive coil being radially displaced from the surface of the preceding coil by an amount slightly less than the diameter of the spine fin tubing to beformed. On the small circumference end of the coil forming member, means are provided for attaching the end of a length of spine fin tubing. The fixture is mounted for rotation by a suitable source of power in order to 'wind the length of spine fin tubing thereon into a plurality of helical coils gradually increasing in circumference. Means are provided for collapsing the coil forming member so that the transverse edges of the respective coils cooperate to provide a fiat pressing surface normal to the axis of the coiled heat exchange tubing. Adjacent the small end of the coil forming member is a compression means or compression surface normal to the axis of the coil forming member which cooperates with the collapsed coil forming member to compress the coiled tubing so that the inner coils of tubing are telescoped into the outer coils of tubing to form a heat exchange structure having a substantially fiat shape with the spine sections thereof interlocking.

For a better understanding of the invention, reference may be had to the accompanying drawings in which:

Fig. l is a plan view of a machine for manufacturing a heat exchanger according to the method of the present invention;

Fig. 2 is a partial view of the machine of Fig. 1 showing the forming fixture in the collapsed state and pressing the tubing into a single row of coils;

Fig. 3 is a partial cross-sectional view of the machine '5 of the member 6 by rotating the wrapping fixture.

of Fig. 1 showing in detail the mechanism for collapsing the coil forming member;

Fig. 4 is an elevation view of a machine having two coil forming members arranged to form a heat exchange structure having two rows of coils;

Fig. 5 is an elevation view of the machine of Fig. 4 showing spine fin tubing helically wrapped onto the coiling members of the machine;

Fig. 6 illustrates the machine of Fig. 4 with the coiling members collapsed and compressing the spine fin tubing intotworowsofcoils; 4 r

Fig. 7 is an elevation view taken along line of Fig. 6, showing the flat coil structure formed by the machine of the present invention; Y

a Fig. 8 is a side elevation view showing a core of spine fin tubing adapted for use in the machine of'Fig. 4 for manufacturing a heat exchange structure having two rows of coiled spine fin tubing;

--Fig. 9 is a cross-sectional view of the core taken along line 99 ofFig. 8; e

Fig. 10 is a partial cross-sectional" view of the-core showing one side of the core wrapped transversely to the reverse bend in the core;

Fig. 11 illustrates two adjacent heat exchange tubes with the spine sections thereof extending radially outward therefrom and illustrating the manner in which the fin sections interlock; and

Fig. 12 is a top view of portions of the heat exchange tubes of Fig. 11 further illustrating the manner in which the spine sections interlock during compression of the coils of tubing.

Referring now to Fig. 1 there is shown a machine for winding heat exchange tubing of the spine fin type into a plurality of helical coils and for pressing these coils into a single row or pass of coiled tubing. The illustrated machine comprises a support or base structure 2 which supports the machine for rotation about an axis normal to the support. The main portion of the machine includes a winding or coiling fixture 3 including a "backing plate 4 which supports a pyramid-shaped coilforming member 6. The coil-forming member 6 comprises a length of spring-like material of rectangular cross-section which is coiled into a plurality of helical coils gradually increasing in circumference from one end to the other with the largest coil of the member being connected to the backing plate 4. The outer surface or peripheral surface of coil forming member 6, generally designated 5 in the drawings, forms a smooth coil winding surface for winding a length of spine fin tubing 7 onto the coil forming member to form a plurality of helical coils of tubing gradually increasing in circumference from one end to the other.

As may be seen in Fig. 1, the coil forming fixture 3 is supported for rotation by the base 2 which supports a spindle. 12 in cantilever fashion for rotation about a horizontal axis. A length 7 of heat exchange tubing is first attached to the inner or smallest coil (obscured in Fig. l by the tubing 7) of the coil forming member 6 and is continuously wrapped onto the peripheral surface In the illustrated embodiment of the invention, power is supplied by a motor 14 for rotating the wrapping fixture 3. More specifically, the motor 14 supplies power through a gear 15 to the drive sprocket 16 which is connected by means of a chain 17 to the drive sprocket 18 positioned around the spindle 12 of the wrapping fixture.

1y, there is provided a feeding head 21 supported by a shaft 22 and a worm shaft 23. Rotation of the worm shaft 23 causes the feeding head 21 to move to the left or tothe right according to the direction ofrotation of 4 the worm. Rotation of the worm shaft 23 is provided through worm sprocket 25 and a chain 24 which extends around the motor drive sprocket 16. In the illustrated embodiment of the invention, the length 7 of spine fin material is attached to the smallest coil of the coiling fixture 3 and the coil is rotated so that the upper portion of the fixture is rotated toward the viewer. The heat exchange tubing 7 is then wrapped around the surface of the coiling member and continuously moved to the right by the feeding head '21. [This movement of the feeding head 21 to the right causes the tubing to wind around the helical outer surface 5 of the coiling member 6 as the coiling surfaces are presented to the tubing.

As may best be seen in Fig. 3, the machine is provided with means for collapsing the coiling member 6 so that the transverse edges 8 of the forming coils present a pressing surface in a plane normal to the'axis of the membeL-"More specifically, therev are provided a plurality of

stop members

30, 31, 32, 33, 34 and 35, which are attached to the individual-forming coils of the springlike member 6 and cause the innermost forming coils of the member to telescope into the outermost forming coils as the backing plate 4 is moved toward the narrow or left hand portion of the fixture, as seen in' Fig. 3. A

pair of hydraulically operated pistons 37 (not shown in Fig. 3) force the backing plate 4 to the left so that the forming coils of the pyramid-shaped member 6 are telescoped into each other and arranged in a plane normal to the axis of the member.

Still referring to Fig. 3, the stop 351s connected to the smallest forming coil 38 of the spring-like member 6 and prevents movement of this forming coil 38 when the backing plate is moved to the left. The remaining stops 30, 31, 32, 33 and 34 each include a mos/able rod 28 which is connected at one end to a coil of the coiling next. to smallest coil 39 of the coil forming member 6,

permits movement of this forming coil 39 to the left only far enoughto cause it to completely overlap the smallest forming coil 38 so that the transverse edges 8 of both coils are in alignment. The rods 28'arc each stopped in succession by engagement of the respective adjusting nuts 29 with ends 36a of the stop brackets. When the adjusting nut 29 of each stop member engages the end 36a of the stop bracket the coil attached to the end of the rod 28 has moved to the left sufficiently to align its transverse edge 8 with the edges of the previously stopped coil. In this manner the stop members cause the larger forming coils to move into overlapping relationship with respect to the inner or smaller forming coils as thebacking plate 4 is moved toward the left. After all of the coils have been stopped in their movement to the left, the backing plate 4 moves over the-spring-like coiling member with the coiling member completely collapsing into the cavity 46 of the backing plate.

Referring now to Figs. .1 and 2, in order to compress i the helical coil of spine fin tubing, on the winding fixture during movement of the backing plate 4 to the left, there is provided a compressing means in the form of a plate 41 which is disposed normal to the axis of the coiling member 6 adjacent the smallest coil 38 of the member 6. The plate 41 remains stationary with respect to the coiling fixture 3 and, as-the successive forming coils of the spring-like member 6 are collapsed, the transverse edges 8 of each of the forming coils push the formed tubing off of the surface 5 of the preceding forming coil therebyforcing the tubing against the plate 41. When the backing plate 4 is moved to its furthermost position to the left and the spring-like member 6 is completely collapsed, the coils of spine fin tubing are pressed into a single pass or row of spiral coils 26. The coiling fixture 3 completely collapses into the cavity 40 so that the dis tance between the compression plate 41 and the backing plate 3 is equal to the diameter of the heat exchange tubing 7. After the coiled tubing is compressed, the compressing plate 41 is pivoted away from the fixture 3 on a hinge (not shown) and the single row of tubing is easily removed from the fixture. The collapsed coiling member 6 is then expanded to permit forming of another length of tubing thereon.

Referring now to Figs. 11 and 12, there are shown two adjacent sections 7a and 7b of spine fin tubing which are arranged in the position they occupy after the tubing has been compressed into a single row structure between the backing plate 4 and the compressing plate 41, as illustrated in Fig. 2. The spine fin tubing includes a central tube 9 having a plurality of radially extending fin sections 10 connected by a base flange 11 wrapped thereon. As will be noted in Figs. 11 and 12, the two sections are positioned closely enough together that the spine sections 10 overlap by an amount indicated by the letter x. As has been previously pointed out, these fin sections resist bending in a direction parallel to the fold 15 formed between the base flange 11 and the fin section 10 but are easily bent by any force directed against the fin sections 10 normal to the fold 15 or in a direction parallel to the axis of the tubing 9. If this spine fin tubing is wound With each successive coiloverlapping the previous coil, the spine sections interlock during winding and the winding force, which is along the axis of the tubing, causes the spine sections to collapse or bend about the told 15, so that they lay substantially flat against the tubing.

By first forming the coils of tubing into a helical structure and then compressing the coils in the manner of the present invention, a fiat coiled heat exchanger is fabricated without causing the individual spine sections to bend over against the tubing. This is because the coils of tubing, as represented by sections 7a and 7b, are moved with respect to each other in the direction indicated by the vertical arrows in Fig. 10 so that the spine sections 8 resist bending and merely slide into the space between the successive wraps of fins. Some of the "spine fins on each of the sections 7a and 7b collide during the compression operation and these are forced to give slightly one way or the other to permit the sections to move into alignment. However, the fin sections 10 only give slightly and are not caused to bend over against the tubing. As is evident from Fig. 12, the overlapping spine fins do not align exactly and become interlocked during the compression operation. This interlocking action prevents the sections from moving apart after the compressive force is removed.

In order to cause overlapping of the individual spine sections it is necessary to wind the successively larger coils of spine fin tubing so that the inner circumference of each successive coil is slightly less or smaller than the outer circumference of the preceding coil; This is accomplished by making the radial distance between the coiling surfaces, such as surfaces a and 5b of Fig. 1, slightly less than the overall diameter of the spine fin tubing to be formed. However, the amount of overlap between adjacent passes or sections of tubing, as shown by the overlap designated x in Fig. 11 cannot be greater than the length of an individual spine section 10. Thus, in this specification and in the claims annexed hereto, the terms slightly smaller or small amount mean a distance no greater than the length of an individual fin section when these terms are applied to the radial displacement between the outer and inner circumferences respectively of successively wound coils or when applied to the radial displacement between the outer surfaces of successively larger forming coils of the coiling member 6, such as surfaces 5a and 5b, in Fig. 1. Thus, by the statement that each coil inner surface is radially displaced from the outer surface of the preceding coil by a small amoun less than the diameter of the spine fin tubing, it is meant that the radial displacement is less than the overall diameter of the spine fin tubing by an amount no greater than the length of a fin section.

Referring now to Figs. 4, 5 and 6 there is shown a second machine, incorporating the fabricating concepts of the present invention, in which the coiling fixture comprises two oppositely arranged coiling or spring-like members 6 disposed to permit simultaneous winding of two lengths of spine fin tubing onto the fixture as the fixture is rotated in one direction. One length of tubing is formed exactly as that previously described with respect to the machine of Fig. 1 while the other length of tubing forms an identical coil except that it is pitched in the opposite direction. The coiled lengths of tubing are helically wrapped from the center in opposite directions and, in the illustrated embodiment, are connected at their innermost ends to form a continuous tubular member narrow in its center portion and progressively increasing in circumference toward both ends. Each of the oppositely disposed coiling members 6 are collapsible when the backing plates 4 of the coiling fixture are moved toward one another. Movement of the plates 4 by the hydraulic pistons 37 compresses the coiled tubular member and telescopes the inner coils within the outer coils to form two

rows

26 and 27 of spiral coils disposed in substantially fiat shape.

Fig. 6 illustrates the machine with the forming members collapsed and pressing the tubing into two adjacent spiral rows having an overall thickness slightly less than twice the diameter of the spine fin tubing. As pointed out with respect to the machine of Fig. l, the transverse edge of each coil of the coil forming member pushes or forces the previously formed coil of spine fin tubing off of the surface of the previous coil of the forming member so that each successively larger coil of tubing is forced over the outer circumference of the previously formed coil of tubing. The spines of the adjacent coils of heat exchange tubing interlock during the pressing operation and force the structure to maintain a substantially flat shape.

In Fig. 4, it will be noted that a preformed core section 43 of spine fin tubing is positioned between the oppositely arranged coiling members 6. Because it is desirable to have heat exchange tubing fill most of the space bounded by the outermost coil of the heat exchanger, the present invention contemplates use of a preformed core section 43 to form the innermost turns of the heat exchanger, The core section 43 is necessarily formed into a plurality of very tight turns by using an inner mandrel which prevents the tubing from collapsing on itself in the area of the turns. The manner or methods of forming tight turns in heat exchange tubing by means of inner mandrels are well known in the art and any suitable method may be employed.

The core section 43 which is more clearly illustrated in Figs. 8, 9 and 10, comprises a short length of tubing having a reverse bend 44 at its center portion and then having a few turns of tubing wrapped upon itself in a direction transverse to the reverse bend 44. Thus, referring to Figs. 8 and 10, the length of tubing on opposite sides of the reverse bend 44 is again provided with bends 46 of relatively short radius which reverse the tubing so that it passes over the reverse bend 44 in the center of the tubing. The tubing is then formed into larger radius bends 47 with the open ends 50 of the tubing folded to overlap the inner portions of the core.

In forming the

bends

46 and 47, it is convenient to make the bends over a form which makes

small openings

48 and 49 on the under side of the bends. These

openings

48 and 49 may be used for mounting the core 43 onto the coil winding machine. Thus, as may be seen in Fig. 7, which shows a cross section of the machine and a coil of tubing, the core 43-is mounted on pegs or

rods

51 and 52 which extend from one of the coil winding members 6 of the machine. In order to insert the core 43 onto the pegs, the opposite sides of the machine are separated. After the core has been inserted the opposite sides of the machine are brought togther again into their Winding positiorn Lengths 7 ofheat exchange tubing are then brazedor connected in any suitable manner to the open ends 50 of the core member 43. These lengths 7 of heat exchange tubing are then fed through a pair of feeding heads (not shown) .which feed the lengths of tubing onto the coiling surfaces of the coiling fixtures 3 as the coiling fixture is rotated. The coil forming members 6 then form the coil structure illustrated in Fig. 5, with the core 43 arrangedto fill the center of the heat exchange structure. Then the opposite coiling fixtures are collapsed and the helically wound outer coils of heat exchange tubing 7 are pressed inwardly toward the center of the fixture. The smallest coils 42 of tubing formed on the coil forming members 6 are pressed over the core 43 which then forms the center of the structure as is illustrated by the spiral coiled structure shown in Fig. 7.

The abovedescribed machines 'each utilize in their method of forming heat exchage structures from lengths of spine fin tubing, the steps of first helically winding spine fin tubing into a plurality of coils each increasing in circumference over the previous coil and then, compressing the helically formed coils, telescoping the inner coils into the larger coils, forming a row, or rows, of

tubing each of which is held in substantially flat shape by the interlocking action of the spine fin sections. It is this concept of telescoping the inner coils into the larger coils in a direction normal to the major axis of the tubing, or along the line parallel to the bend in the L-shaped spine fin sections, that enables the heat exchange structure to be formed in this manner. Obviously, this method of forming these structures can be performed on fixtures other than those described. For instance, the helical coil may first be formed on a noncollapsible coil forming member having a substantially smooth coiling surface and then removed from this coiling member and placed in a press adapted to press the opposite ends of the coiled structure together to telescope the smaller coils into the outer coils. It is, however, important that the length of heat exchange material be first coiled into a plurality of helical coils with subsequent coils gradually increasing in circumference over the previous coils and with each subsequent coil having a circumference slightly smaller than the outer circumference .of the preceding coil so that, when the coiled structure is compressed, the spine fins of the adjacent coils interlock and hold the structure in substantially flat shape. i

By the present invention, there has been provided a method for fabricating coiled heat exchangestructures from spine fin material which method completely elimi nates the collapsing or bending of the spine sections of the tubing in the overlapped portions of the structure. -As a further aspect of this invention, a machine is provided upon which the steps called for in the above-mentioned method are easily carried out and adapted to mass production manufacturing techniques.

While in accordance with the patent statutes therehas been described what at present is considered to be the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention and it is, therefore, the aim of the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

.What I. claim as new and desire to secure by Letters Patent of the United States is: a a

l. The method of manufacturing a heat exchange structure comprising providinga length at heat exchange tubing having a multiplicity of spine sections extending radially outward from the surface thereof, forming said length of heat exchange tubing into a plurality of helically wound coils withsubsequent coils being greater in circumference than each preceding coil but each subsequent coil having an inner circumference slightly smaller than the outercircumference of the preceding coil, and compressing said coils axially relative to each other thereby to telescope the outer helical coils onto the inner helical coils'to. form a heat exchange structure having a single row of coils with said spine sections of said adjacent coils interlocking to maintain said structure in substantially flat shape.

2. The method .of manufacturing a heat exchange structure comprising the steps of providing a length of'heat exchange tubing having a multiplicity of spine sections extending radially outward from the surface thereof, forming said length of heat exchange tubing into a helically coiled member including a plurality of helically wound coils with each subsequent co l having a greater outer circumference than the preceding coil but with the inner circumference of each subsquent coil being radially disposed a small amount less than the outer circumference of the preceding coil and compressing one end of said coiled member relative to the other end thereby to telescope the outer helical coils onto the inner helical coils to form a heat exchange structure having a singlerow of coils with said spine sections of said heat exchange tubing interlocking to maintain said coils in said single row. i

3. The method of manufacturing a heat exchange structuref comprising the steps of providing two lengths of heat exchange tubing having a multiplicity of spine sections extending radially outwardfrom the surfaces thereof, forming each of said lengths of heat exchange tubing into a plurality of helical coils with each subsequent coil having a greater outer circumference than the outer circumference of the preceding coil but with each subsequent 'coil having an inner circumference less .than the outer circumference of the preceding coil, connecting the innermost ends of said lengths of tubing to form a continuous tubular member narrow in its center portion and progressively increasing in circumference toward both ends, and compressing the ends of said tubular member relative to each other thereby to telescope the outer helical coils onto the inner helical coils to form a heat exchange structure having two rows of coils connected at their inner ends and with said spine sections of said heat exchange tubing interlocking to hold said coils in alignment and to maintain said structure in a substantially fiat shape. 1

'4. .The method of manufacturing a heat exchange structure comprising the steps of providing a lengthof heat exchange tubing having a multiplicity of spine sections extending radially outward from the surface thereof, reverse bending said length of heat exchange tubing forming equal portions of said tubing on opposite sides of the bend, forming said equal portions of said tubing into a plurality of helical coils with each subsequent coil having a greater outer circumference than that of the preceding coil but each subsequent coil having an inner circumference less than the outer circumference of the preceding coil, said helical coils extending in opposite directions from the bend in said heat exchange tubing to form a continuous tubular member narrow in its center portion and progressively increasing in circumference toward both ends, and compressing said tubular member from both ends inwardly toward the center portion to telescope the outer helical coils onto the inner helical coils to form a heat exchanger structure having two rows to maintain said structure insubstantially' flat shape.

5. The method of manufacturing a heat exchange structure comprising the steps of providing a short length of heat exchange tubing having a multiplicity of spine sections extending radially outward from the surface thereof, forming a core member from said short length of heat exchange tubing by reversely bending said tubing and then winding opposite sides of said tubing tightly upon themselves in a direction transverse to that of said reverse bend, providing two relatively long lengths of said aforementioned type of heat exchange tubing, forming said long lengths of heat exchange tubing into a plurality of helical coils with each subsequent coil having a greater outer circumference than the outer circumference of the preceding coil, each subsequent coil having an inner circumference less than the outer circumference of the preceding coil, connecting the inner ends of each of said lengths of tubing to the ends of said core to form a continuous tubular member narrow at its center and progressively increasing in circumference toward both ends, and compressing the opposite ends of said tubular member relative to each other thereby to telescope the outer helical coils onto the inner helical coils to form a heat exchange structure having two rows of coils connected through said core member at their inner ends and having said spine sections of said heat exchange tubing interlocking to maintain said structure in a substantially fiat shape.

6. The method of manufacturing a heat exchange structure from heat exchange tubing of the type having a multiplicity of spine sections extending radially outward from the surface thereof comprising the steps of providing a core from a short length of said tubing by reverse bending said short length of tubing and then Winding opposite sides of said tubing tightly upon themselves in a direction transverse to that of said reverse bend, connecting first and second lengths of said heat exchange tubing to opposite ends of said core, forming said first and second lengths of heat exchange tubing into a plurality of helical coils extending in opposite directions from said core, each subsequent coil on opposite sides of said core being of greater outer circumference than the outer circumference of the preceding coil but each subsequent coil having an inner circumference less than the outer circumference of the preceding coil, said helical coils on opposite sides of said core having an inner circumference slightly less than the outer circumference of said core, and compressing said coils from said both ends inwardly toward said core to telescope the outer helical coils onto the inner helical coils and to move said innermost coils over said core thereby forming a heat exchange structure having two rows of coils with said spine sections of said heat exchange tubing interlocking to maintain said structure in a substantially fiat shape.

7. A machine for manufacturing a heat exchange structure from heat exchange tubing of the type including a multiplicity of spine sections extending radially outward from the surface thereof comprising a substantially pyramid-shaped coil forming fixture including a springlike member of rectangular cross section helically coiled upon itself with the smallest coil at one end and with each subsequent coil overlapping only a portion of the preceding coil, said coils thereby providing a continuous peripheral tube coiling surface that gradually increases in circumference from end of said member toward the other end, said surface of each of said coils being radially displaced from the preceding coil surface by a small amount less than the diameter of said heat exchange tubing to be wrapped, means for attaching one end of a length of heat exchange tubing onto the smallest coil of said forming fixture, means for rotating said coil forming fixture to wrap said length of heat exchange tubing onto said peripheral tube coiling surface of said forming fixture, a compression plate positioned transversely to the axis of said coil forming fixture adjacent the smallest coil thereof, means for moving said coil forming fixture toward'said compression plate, stop means attached to successive coils of said spring-like member for collapsing said spring-like member when said coil forming fixture is moved toward said compression plate with the smaller coils of said member telescoping into said larger coils so that the transverse edges of said coils cooperate to provide a flat pressing surface normal to the axis of said coil member thereby compressing said coils of said heat exchange tubing between said compression plate and said pressing surface to telescope said innermost coils of said heat exchange tubing within said outermost coils of said heat exchange tubing thereby forming a heat exchange structure having a single row of coils with the spine sections thereof interlocking to maintain said structure in substantially flat shape.

8. A machine for manufacturing a heat exchange structure from heat exchange tubing of the type including a multiplicity of spine sections extending radially outward from the, surface thereof comprising a substantially pyramid-shaped coil forming fixture including a spring-like member of rectangular cross-section helically coiled upon itself with the smallest coil at one end and with each subsequent coil overlapping only a portion of the preceding coil, said coils thereby providing a continuous peripheral coiling surface that gradually increases in circumference from one end of said member toward the other end, said surface of each of coils being radially displaced from the preceding coil surface by a small amount less than the diameter of said heat exchange tubing to be wrapped, means for attaching one end of a length of heat exchange tubing onto the smallest coil of said forming fixture, means for rotating said coil forming fixture to wrap said length of heat exchange tubing onto said peripheral tube coiling surface of said forming fixture, tube feeding means for maintaining said tubing in alignment with said peripheral coiling surface on said coils of said spring-like member as said tubing is wrapped onto said surface, a compression plate positioned transversely to the axis of said coil forming fixture adjacent the smallest coil thereof, means for moving said coil forming fixture relative to said compression plate, stop members attached to successive coils of said spring-like member for collapsing said spring-like member when said forming fixture is moved toward said compression plate with the smaller coils of said member telescoping into said larger coils so that the transverse edges of said coils cooperate to provide a hat pressing surface normal to the axis of said spring-like member whereby said innermost coils of said heat exchange tubing are telescoped within said outermost polls of said heat exchange tubing between said compression plate and said pressing surface of said spring-like member thereby forming a heat exchange structure having a single row of coils with the spine sections thereof interlocking to maintain said structure in substantially fiat shape.

9. A machine for manufacturing a heat exchange structure from heat exchange tubing of the type including a multiplicity of spine sections extending radially outward from the surface thereof comprising a substantially pyramid-shaped coil forming fixture including a backing plate member mounted for rotation about a substantially horizontal axis and a spring-like member of rectangular cross-section extending horizontally outward from said backing plate member, said spring-like member being helically coiled upon itself with the smallest coil at one end and with each subsequent coil overlapping only a portion of'the preceding coil, said coils having their outer surface forming a continuous tube coiling surface that gradually increases in circumference from one end of said spring-like member toward the other end, said surface of each of said coils being radially displaced from the preceding coil surface by a small amount less than the diameter of said heat exchanger tubing to be wrapped, said spring-like member having its largest coil thereof at- 7 ll tached to said backing plate member and adapted to fit within a cavity formed therein to receive said spring-like member, said cavity having its-outer circumference large; enough to receive the largest coil of said spring-like mem-; ber, means for attaching one end of a length of heat ex-: change tubing onto the smallest coil of said forming fix ture, means for rotating said coil. forming fixture thereby to wrap a length of heat exchange tubing on the peripheral coiling surface of said coils of said spring-like memher, a compression plate positioned parallel to said back 10 ing plate adjacent the smallest coil of said spring-like member, means for moving said coil forming fixture toward said compression plate, stop members attached to successive coils of said spring-like member for collapsing said spring-like member with the smaller coils of said member telescoping into said larger coils and with said larger coil fitting within said cavity of said backing plate so that the transverse edges of said coils and said backing plate cooperate to provide a flat pressing surface normal to the axis of said coiled member whereby said innermost coils of said heat exchange tubing are telescoped within said outermost coils of said heat exchange tubing between; said compression plate and said pressing surfaces of said: spring-like member and said backing plate thereby forming a heat exchange structure having a single row of coils with the spine sections thereof interlocking to main tain said structure in substantially flat shape.

10. A machine for manufacturing a heat exchange structure from heat exchange tubing of the type including a multiplicity of spine sections extending radially outward from the surface thereof comprising a base plate mounted on a spindle for rotation about'a horizontal axis, a sub-I stantial pyramid-shaped coil forming fixture having a backing plate movably supported in spaced parallel re lationship with said base plate and having extending hori zontally outward therefrom in a direction away from said base plate a spring-like member of rectangular'cros's-sec tion helically coiled upon itself, said spring-like member having its smallest coil at its outer end and having each subsequent coil overlapping only a portion of the preceding coil, said coils thereby providing a continuous pe ripheral tube coiling surface gradually increasing in cir-' cumference from the outer end of said member toward its connecting end with said backing plate, said surface; of each of said coils being radially displaced from the preceding coil surface by an amount less than the diame ter of said heat exchange tubing to be wrapped, said back ing plate having a cavity therein adapted-to circumscribe' the largest coil of said spring-like member, means for rotating said'base plate and said forming fixture for 5 wrapping a length of heat exchange tubing on said coil ing surface of said spring-like member, means for moving said backing member and said spring-like member away from said base plate, a plurality of stop members connect; ing at one end to the individual coils of said spring-like member and having their outer ends extending to said" base plate, all of said stop members except said stop members connected to the smallest coil' of said spring like member being slidably connected to 'said base plate for permitting limited movement of said remaining coils 50 of said spring-like member in a direction away from said base plate during movement of said backing plate away from said base plate, said stop members successively stopping the movement of said remaining coils as their transverse edges move into alignment with the next pre 5 ceding coil thereby causing said spring-like member to present a transverse pressing surface normal to the axis" of said coiling fixture, a compression plate positioned" transversely to the axis of said coil forming fixture ad jacent the smallest coil thereof, said compression plate and the transverse edges of said coils of said spring-like member cooperating to telescope the innermost coils of said heat exchange tubing within said outermost coils of said heat exchange tubing as said coil forming fixtureiis movedaway from said base plate thereby forming aheat i3 exchange structure having a single row of coils with the spine sections thereof interlocking ,to maintain said structure in substantiallyflat shape. r p

' 11'. A machine for manufacturing a heat exchange structure from heat exchange tubing of the type including a multiplicity of spine sections extending radially outward from the surface thereof comprising a pair of substantially pyramid-shaped coil forming fixtures each having a' spring-like member of rectangular cross-section helically coiled upon itself with the smallest coil at one end and with each subsequent coil overlapping only a portion of the preceding coil, said coils thereby providing a continuous peripheral tube coiling surface that gradually increases in circumference from one end of said member toward the other end, said surface of each of said coils being radially displaced from the preceding ,coil surface by a small amount less than the diameter of said heat exchange tubing to be wrapped, each of said fixtures i being arranged along a horizontal axis with the smallest coil of each of said fixtures arranged adjacent each other, means for rotating said coil forming fixtures to wrap separate lengths .of heat exchange tubing onto the peripheral tube coiling surfaces of said oppositely disposed coil forming fixtures, means for moving said coil form-' ing fixtures toward one another, stop members attached to successive coils of said spring-like members for limiting movement of said coils ofsaid spring-like members and collapsing said successive coils of said spring-like members so that the smaller coils of said members telescope into said larger coils to align the transverse edges of all of said coils of said oppositely disposed spring-like members to provide flat pressing surfaces normal to the axis of said coiled members whereby said innermost coils of said heat exchange tubing wrapped on the coiling surface of said coil forming fixtures are telescoped within the outermost coils of said heat exchange tubing while said spring-like members of each of said fixtures form pressing surfaces moving toward each other'topress said coils of tubing together thereby forming a heat exchange structure having two rows of coils with the spine sections, thereof interlocked to maintain said structure in substantially flat shape. 7

12. A machine for manufacturing a heat exhange structure from heat exchange tubing of the type including a multiplicity of spine sections extending radially outward from the surface thereof comprising a pair of substantially pyramid-shaped coil forming fixtures each having a spring-member of rectangular cross-section helically coiled upon itself with the smallest coil at one end and with each subsequent coil overlapping only a portion of the preceding coil, said coils of each of said fixtures thereby providing a continuous peripheral tube coiling surface that gradually increases in circumference from,

one end of said member toward the other end, said said oppositely disposed fixtures, the tube feeding means for maintainingsaid separatelengths of tubing in alignment withsaid peripheral coiling surfaces of said springlike members as said separate lengths of tubing are wrapped onto said surfaces thereof, means for moving said coil'forming fixtures toward one another, stop members, attached to successive coils .of each of said spring-like members for limiting the movement of said successive coils of said spring-like members Whensaid forming tures are moved toward one another so that saidsmaller coils of each of said spring-like members telescope into said larger coils to align the transverse edges of said coils ofoppositely disposed spring-like members to pro vide fiat pressing surfaces normal to the axis of said coil members whereby said innermost coils of said heat exchange tubing are telescoped within the outermost coils of said heat exchange tubing while said spring-like members of each of said fixtures collapse to form pressing surfaces moving toward each other to press said coils of tubing together thereby forming a heat exchange structure having two rows of coils with the spine sections thereof interlocked to maintain said structure in substantially flat shape.

References Cited in the file of this patent UNITED STATES PATENTS Stambaugh Aug. 15, 1905 Humphrey Dec. 2-8, 1915 Price Feb. 19, 1924 Summers Apr. 21, 1931 Bilger et a1 May 2, 1939