US3481173A - Means for forming heat exchange elements - Google Patents

Description

Dec. 2, 1969 E. E. RHODES MEANS-FOR FORMING HEAT EXCHANGE ELEMENTS Filed Nov. 30, 1967 INVENTOR. BY gddgm ATTORNEYS United States Patent U.S. Cl. 72187 1 Claim ABSTRACT OF THE DISCLOSURE The method of forming a heat exchange element for use in heat exchange with a water pass tube of a heat exchange unit such as an automobile radiator or heater which comprises passing a deformable strip of sheet metal between rotating roll dies which initiate folding of said strip at evenly spaced intervals and deform the intervening strip material so as to provide evenly spaced segments having a plurality of deformations and separated by alternately reversed, partially folded, connecting members, increasing the closure of the resultant folds of said connecting members with plaiting means and passing the folds of said strip through shaping means adapted to provide the crown line of said connecting members with a flattened line surface for continuous line contact with said water pass tube while maintaining an even height to said folds.

Although details of construction may vary, an engine cooling radiator ordinarily includes an inlet tank and an outlet tank for suitable connection with the water jacket of the engine, and a core or heat dissipating unit interposed between two tanks for the travel of water in thin streams from one tank to the other through a number of spaced passageways or water tubes of suitable heat exchange material. Between each pair of these water conduits flows an air stream to take up or absorb heat carried by the water. A heat exchange fin strip or spacer element is generally folded back and forth and interposed between the water tubes for cooperation therewith to divide the intervening space into a number of small aircells.

Ordinarily, the opposite edges or front and rear faces of the core are dipped first in a flux and then in molten solder to seal the margins of the walls of the Water tubes where necessary and to join the fin strips to the walls. If the water tubes and fin strips are evenly formed so as to make possible continuous contact from edge to edge, there will be an inward capillary flow of solder toward the center of the core and a positive bond will result throughout substantially the entire depth of the core to insure the free flow of heat into the fins.

It is one object of this invention to provide even folds in said fin strip and to provide the terminal edge of each convolution with a flattened line surface adapted to make continuous line contact with the Water pass tubes with which the strip is to be sealed.

Other objects and advantages of this invention will be obvious to those skilled in the art from the detailed description which follows when read in conjunction with the accompanying drawings.

FIGURE 1 is a semidiagrammatic side view of a fin forming apparatus which can be used to form strip material in accordance with this invention; and

FIGURE 2 is a perspective view of a radiator fin strip formed in accordance with this invention.

Referring now to FIGURE 1, a roll 11 supports metal strip stock 13 and is positioned to permit the feeding of strip stock 13 to a roll die 15 which is constructed and arranged to provide strip stock 13 with regularly spaced deformations and to initiate the bending of the strip stock into evenly spaced convolutions. Strip stock 13 may be of any suitable metal or alloy having good heat exchange characteristics, e.g. copper, aluminum, brass, etc. Roll die 15 comprises a pair of matched fin-forming rolls 17 and 19 each of which comprises a plurality of abutting gearlike wheels or blades which in operational position are in mesh with the corresponding wheels or blades of the companion roll upon the strip stock passing therebetween.

A variety of devices have been designed for providing regularly spaced impressions upon a stri material and/ or plaiting such material to form alternately reversely folds of even length. Typical of these are the devices illustrated and/or described in U.S. Patents 1,012,568; 1,148,670; 1,212,482; 1,617,163; 1,640,147; 1,937,466; 2,141,235;

2,252,209; 2,329,789; 2,443,377; 2,483,694; 2,035,403 and The construction of the roll die which I prefer to use is described in detail in U.S. Patent 3,214,954.

The fin strip shown in FIGURE 2 is of folded or corrugated outline providing a series of planar based fins 16 between folds or curved connecting members 18. A typical strip material is about .003 inch in thickness. Each fin has a plurality of slits with metal adjacent each slit turned out of the base plane of the fin to provide each fin with plurality of louvers 20. Such deformations are designedly provided to assist in the control and direction of air flow through the radiator core. In the plaiting of such strips, the alignment of such louvers, or other deformations as the case may be, must be maintained if the fin strip is to function in the intended manner, in a radiator assembly.

After passing between rolls 17 and 19, the now facially deformed, partially folded strip 13 passes over a platen or table 21 and is engaged by the teeth of a starwheel impeller 23. Impeller 23 may comprise two or more tooth-bearing "wheels 25 in parallel relationship which are spaced apart so as to engage and exert force against portions of each fin which are located between or to the side of the aforementioned louvers or other deformations. Impeller 23 forces partially folded strip 13 against and eventually through a spring actuate-d restrictor 31. Restric tor 31 comprises a bracket support post 33 which in turn is supported by platen 21. A horizontally positioned pivot pin 35 is rigidly aflixed to post 33 and pivotably supports bracket 37. Pivotably secured to bracket 37 by pivot pin 39 is upper shoe 41. Bracket 37 is under a downward directed pressure exerted by spring 43 which has one end resting within a cylindrical depression 45 in bracket 37 and the opposite end afiixed to bracket 47 which in turn has one end connected to the top of post 33 and has a spring 49 interposed therebetween. Bracket 47 is provided with a wing nut assembly 51 for adjusting the pressure of spring 43 against bracket 33. Lower shoe 55 extends through an opening in platform 21 and is under constant pressure from spring 57 which is supported by rod 59. Rod 59 in turn is supported by platen 21.

The spring 43 is adjusted to provide the desired amount of resistance to the passage of partially folded strip 13 between upper shoe 41 and lower shoe 55. Impeller 23 engages and forces the partially folded strip 13 into the mouth of the passageway between upper shoe 41 and lower shoe 55 and hence into contact with upper shoe 41 and lower shoe 55. The folds in strip 13 become more accentuated as pressure is built up by the constant feed of strip material by impeller 23 which eventually creates a 'wedging pressure that is sufficient to overcome the pressure exerted against the strip by springs 43 and 57 with a release of a section of strip 13. When the pressure from the build-up of strip 13 between impeller 23 and restrictor 31 is released, springs 43 and 57 again restrict further movement of strip 13 between the upper and lower shoes until such build-up is repeated. In the course of building up sufiicient pressure to force the upper and lower shoes apart, the folding of strip 13, initiated by rolls 17 and 19, is increased. This method of plaiting or gathering of strip material is known to the art and if employed as the sole means of plaiting tends to disadvantageously distort the fin strip because of the pressure required to effect a sufficient bending of the metal strip into the desired folds or corrugations. In accordance with this invention, it is preferred to retain restrictor 31 in the system but to reduce the pressure required to effect a release of strip material from between upper shoe 41 and lower shoe 55. By this method, some additional folding deformation is gained without undesirable distortion.

The strip 13 then passes directly from the spring actuated restrictor 31 to plaiting mechanism 61 which includes plaiting rolls 63 and 65. In another embodiment, not separately shown, restrictor 31 is eliminated and the partially folded strip is passed directly to rolls 63 and 65.

Rolls 63 and 65 alternately engage alternate and opposite folds of strip 13. The configuration of rolls 63 and 65 in cooperation with the pressures exerted upon strip 13 by their counterrotation increase the closure of the partially formed folds While shaping the connecting members 18 to the desired even curvature. In this embodiment, roll 65 rotates clockwise 'while roll 63 rotates counterclockwise.

Rolls 63 and 65 are spaced apart but aligned in a manner such as to mesh if brought into contact by vertical displacement, i.e. the teeth or lands thereof are maintained out of interdigital relationship as illustrated in FIGURE 1 but aligned to admit of interdigitation if said rolls were to be moved towards each other while maintaining such alignment. In other words, when one of the teeth or lands of roll 65 is nearest to roll '63, a longitudinal bisector of such tooth and transverse bisector of such roll is in line with the corresponding bisector of one of the grooves or channels of roll 63.

The lands or teeth of rolls 63 and 65 upon engaging one of the partial folds of strip 13 provide line contact across the full width of strip 13 and impel the strip between the counterrotating rolls 63 and 65.

The rolls 63 and 65 are spaced apart a distance sufficient to prevent cooperative pressures from the paired plaiting rolls causing significant deformation of the essentially planar based fins. Preferably, the rolls are aligned and spaced apart in a manner such as to permit such fins to pass between the rolls in substantially parallel relationship with each other. This facet of the spacing can be controlled by controlling the distance between the rolls. In addition, protection of the fin deformations requires that attention be given to the depth of the grooves and/or to the height of the lands or teeth. Only the curved connecting members and that portion of the planar base between the connecting member 18 and the fin louvers 20 comes into contact with the impelling land or tooth. Thus, the facial configuration of the fin is preserved both by avoiding direct contact with the teeth of the plaiting roll and by proper spacing of the plaiting rolls to avoid buckling, jamming, etc.

Rolls 63 and 65 are provided with guide bars 75 and 77 which serve as strippers when strip 13 has passed between rolls 63 and 65. Thus, if strip 13 after passing through the zone of greatest restriction betwen rolls 63 and 65 attempts to cling to one of the rolls, it is stripped from such roll by the corresponding strippers. Restrictor 31 and plaiting mechanism 61 are more fully described and illustrated in my US. Patent 3,318,128.

Glides 75 and 77 direct the folded strip 13 from rolls 63 and 65 to shaping means 81 which is adapted to fiatten the crown line or longitudinal bisector of said connecting member 18 thereby forming a flattened line surface 22 along the full distance of said crown line that is to contact the water tubes of the heat exchange device. Ordinarily, surface 22 will extend the full length of the crown line. Surface 22 is formed to admit of continuous line contact between each of the end members 18 and a flat side surface of a water tube.

Shaping means 81 comprises a vertically adjustable, stationary anvil 83 and vertically reciprocal hammer means 85. In the illustrated embodiment, hammer means 85 comprises a first support 87 and a second support 89. Adjustably mounted near the top of support 87 via bolts 91 and 93 is guide 95. Near the lower part of support 87 there is mounted a fixed clevis 97. Pivotably mounted on support 89 is shaft 99. Fixedly secured to shaft 99 is drive wheel .101 and pulley 103. Pulley 103 is provided with a drive belt 105 which is connected to a conventional power source, not shown.

Drive arm 107 is pivotably connected with drive Wheel 101 via pin 109. Pin 109 is positioned off center with respect to the face of drive wheel 101. Arm 107 is pivotably connected to arm 111 via pin 113. Arm 111 is pivotably connected to and supported by clevis 97 via pin 115.

Pin 113 also pivotably connects arm 107 with arm 117. The opposite end of arm 117 is pivotably connected with slide member .121 via pin 119. At the opposite end of slide member 121 there is fixedly mounted a hammer head 123. Slide 121 is slidably connected with guide 95 through which it reciprocates vertically as drive wheel 101 and pulley 103 are caused to rotate via drive belt 105. The rotation of drive wheel 101 sets in motion the eccentric drive means formed by wheel .101, arms 107, 111 and 117 and imparts reciprocating motion to slide 121 and hammer head 123. In the preferred embodiment, anvil 83 and hammer head 123 each have a curved working surface to limit each thrust of opposing pressure on strip 13 to a predetermined number of end members 18. The pressure applied to strip .13 when hammer head 123 is in its uppermost position is insufiicient to cause retained buckling deformation to fins 16 and sufficient to cause a flattened line surface along the crown line of the end members receiving such pressure. The exact amount of pressure to be applied will require routine adjustment. This requirement will vary somewhat with the thickness and composition of the strip material employed.

As strip 13 passes from between anvil 83 and hammer head 123, it passes between parallel guides 125 and 127 to collection means not shown.

Having thus described a preferred embodiment of this invention with particularity, it becomes obvious that modifications can be made in the same without departing from the spirit and scope of the invention as set forth in the appended claim.

I claim:

1. A device for forming a heat exchange element from a deformable strip of sheet metal which comprises in combination:

(a) rotating roll dies to imitiate folding of said strip at evenly spaced intervals and deform the intervening strip material so as to provide evenly spaced segments having a plurality of deformations and separated by alternately reversed, partially folded, connecting members,

(b) plaiting means to increase the closure of the resultant folds of said connecting members, and

(c) shaping means including reciprocating hammer means in cooperation with anvil means and adapted to provide oppositely directed pressures along the crown lines of oppositely directed connecting member folds to form a flattened line surface on said connecting members along said crown lines, said hammer means and said anvil means being further characterized in that said anvil means and said hammer means have oppositely disposed convex working surfaces constructed and arranged to limit each thrust of opposing pressures therefrom to a predetermined number of said crown lines.

(References on following page) 5 6 References Cited 2,413,179 12/1946 Grandmont et a1. 113118 3,191,418 6/1965 Modine 72187 UNITED STATES PATENTS 1 0133 99 2 1912 Livingston 72 7 CHARLES W. LANHAM, Primary Examiner 1,937,466 11/ 1933 Smith et a1. 72187 5 L A. LARSON, Assistant Examiner

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