US2627652A - Method of making an element having a fin - Google Patents

Description

Feb. 10, 1953 s. M. SCHWELLER 2,627,652

METHOD OF MAKING AN ELEMENT HAVING A FIN Filed Sept. 29. 1949 2 SHEETS-SHEET l IN V EN TOR. SYL vrsnw 1 J'cmveu. m.

lf/J A TTUE/YEYS Feb. 10, 1953 s. M. SCHWELLER 2,627,652

METHOD OF MAKING AN ELEMENT HAVING A FIN Filed Sept. 29. 1949 2 SHEETS-SHEET 2 I l I I 1 INVENTOR. in vayrel-Srnwa; Ex.

Ill LL 1/1: A TTakNEYS Patented Feb. 10, 1953 I METHOD OF MAKING AN ELEMENT HAVING A FIN Sylvester M. Schweller, Dayton, Ohio, assignor to I General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application September 29, 1949, Serial N 118,487

1 Claim.

This invention relates to refrigeration and particularly to heat exchangers employed in refrigerating systems.

An object of my invention is to provide an im- Fig. 10 is an enlarged view of a thin disc-like portion removed from the metal piece in accordance with the present method; and

Fig. 11 is a sectional view of the disc-like porproved and lower cost. heat transfer device or tion shown in Fig. 10. heat exchanger. Referring to the drawings, for illustrating my Anot r Obj c of my invention is to prov a invention, 1. have shown in Fig. 1 thereof a rec- W cost fin element adapted to be mounted on a tangular or square-shaped piece [5 of aluminum fluid conduit of a heat exchan r a an which may be cut from sheets or ribbon-like rolls proved method of fabricating the fin. of thin aluminum. The piece [5 may be substan- A still further object of y invention is to P tially pure aluminum known to the trade as Comd a improved method o making a fi mercial Aluminum and consisting of 2% copperj ment-from thin sheet metal stock and to provide 1,()% iron and silicon; .05% manganese; .10% the fin element W th a c a pertion adapted to zinc; .05% each of the alloys and the remainder embrace a conduit of a heat exchan r. pure aluminum. This metal in addition to'being A more specific object of my in n n is to of' high heat conductivitmsuitable for use in fabricate a fin element from a substantially heat transfer devices and of low cost, is also qua piece o ma l a le sh t m al by causin readily malleable and suitable to be worked or the metal to fiow and forma thin circular-shaped deformed under pressure. The metal piece l5 fin portion and an integral central collar portion (see Fig. 2) is approximately 3 2" in thickness. extending outwardly beyond each side thereof to A fin element 16 produced by deforming piece provide means for spacing the fins of the elements 15 in the manner or by the method hereinafter from one another on a conduit of a heat e described is shown in Figs. 3 and 4, and includes changer. a circular fin portion [1, having a central hole [8 Further objects an advantages f he present therein bounded by a collar H) which projects invention will be apparent from e following (1 outwardly from each side of the fin portion ll. s p reference b n ad t th a mpa y- The fin portion 11 of element I6 is preferably, ing drawings, wherein a preferred form of the although not necessarily, tapered by being thicker present invention is clearly shown. adjacent collar l9 than at its outer edge. A plu- In the drawings: rality of the fin elements l6 are strung or mount- Fig. l is a view of a square piece of sheet metal ed on a conduit 2| (see Fig. 5) of a heat transto be formed into fin element in accordance with for device, or heat exchanger such, for example, my method; as a condenser or evaporator employed in re- Fig. 2 is an end view of the metal piece shown frigerating and the like systems. Fin elements in Fig. 1; It may be secured'in intimate thermal contact Fig. 3 is a side View of a fin element made in with the wall of conduit 2|, for increasing the accordance with my present method; heat transfer surface thereof, in any suitable or Fig. 4 is a sectional view of the fin element conventional manner. The fin portion ll of eleshown in Fig. 3; ment l6 extends outwardly from the collar IS in- Fig. 5 is a side view partly in section of afinned 4o termediate its ends and the collar I9 is of utconduit of aheat exchanger; most importance since it provides a large area Fig. 6 is a vertical sectional view of a two-part to pick up heat from the wall of condenser condie employed in the present method, showing the duit 2! and also serves tospace the fin portions metal piece disposed in a cavity of one part of I! of elements Hi from one another. The spacing the die; collar l9 furthermore eliminates the use of ex- Fig. 7 is a fragmentary view of a part of the die pensive rack or rack-like tools or dies, for spacing taken on the line 1-1 of Fig. 6; fin elements on a conduit prior to or at th time Fig. 8 is an enlarged fragmentary vertical secfin elements are bonded 0r secured thereto. tional view of the die showing the metal of the I have illustrated only the die parts employed metal piece flowing into a confined space within to carry out the method of fabricating fin elethe die; ments as hereinafter described, since the con- Fig. 9 is an enlarged fragmentary vertical sec' struction and Operation of punch or pressing tional view of the die showing the metal of the machines litilizedito move the die parts relative metal piece flown into the desired shape to form to one another are conventional and well known. a fin element of the present disclosure In Fig. 6 of the drawings I show a die comprising an upper part and a lower part generally represented by the arrows and reference characters 25 and 26 respectively. These parts are secured to relatively movable members 27 and 28 respectively of a punch or pressing machine. The punch or press moves the upper member 2? downwardly so as to bring the die parts 25 and 26 into cooperative relation with one another. Upper die member 25 comprises a plate 3| rigidly mounted upon the upper member 21 and a plurality of screws 32 in plate 3! are threaded into another plate or die element 33 carried by and movable relative to plate 3!. A spring 36 surrounds each screw 32 for a purpose to be hereinafter described. The mounting of plate 3| to member 27 looks an element comprising a head 35 and a plunger 37 thereto. The plunger 31 extends through plate 3! into a hole provided in plate 33 and is adapted to project beyond the plate 33 when this plate is moved a predetermined distance relative to plate St. A plurality of dowel pins or the like 38 may be employed in addition to the screws 32 for guiding the movement oi plate 33 relative to plate St. The lower face 39 of plate 33 is provided with a cut-out portion or groove ll and has a circular boss d2 projecting therefrom for a purpose to be hereinafter described. The hole in plate 33 in which plunger 3? moves is provided at its lower end with an enlarged portion or counterbore 43 to be presently described.

Lower die part 25 comprises a base 4%, secured to member 23 and having a large hole l; there in, a plate 49 resting on top of base 46 and another plate 51 supported upon plate 49. Both plates '39 and 53 and base d6 are rigidly secured to one another and to member 28 by suitable bolts and screws (not shown) which pass through the plates and base and are threaded or an chored in the member 28. Top plate M of die part 25 is bored out as at 56 and intermediate plate 453 is bored out as at 51 for the reception of a shouldered movable element 58. A plurality of springs 59, located in counterbores 68 provided in plate d9, normally hold the movable element 58 in its upper position as shown in Fig. 6 of the drawings, with its top surface spaced below the top surface 62 of die plate '6 so as to provide a circular cavity El in the face surface of this die plate for a purpose to be presently described. The element 58 is provided with a hole, centrally thereof, corresponding to and aligned with a central hole provided intermediate plate 49, for the reception of a plunger 63 of a shaft member 64 which'is movable relative to plates 49 and El and base 46 of die part 26. Shaft member '64 'has' an enlarged shouldered portion 66 thereon which moves along and is guided by the wall surface of hole 41. A strong spring 8'1 is interposed between the shouldered portion 68 of shaft Stand the face of member 28 to normally force shaft 64, its shouldered portion 66 and its plunger portion 63 upwardly into the position shown in Fig. 6 of the drawings. The upper end of the hole in element 53 is provided with an enlarged portion or 'counterbore 69 so as to match or correspond to the counterbore 43 in the plunger holof lower plate 33 in the die part 25. "A'tube Tl fits in a groove 32 provided in the face- 62 of plate 5! of lower die part 26 and is rigidly held in place on diev part 26 by a metal strap 13 and screws M (see- Fig. 7). One end of the tube "H terminates adjacent the wall of cavity El in die'part 2'6 and its other end is connected to a source" of supply of air under pressure for a purpose to be hereinafter described. The elements of die parts 25 and 26 are normally held in the position shown in Fig. 6 of the drawings with the faces 39 and 62 respectively thereof spaced from one another a suitable distance to permit access by the operator of the punch press to the die cavity 6!.

Operation of the apparatus, to carry out the method of making fin elements of the prescribed shape as herein disclosed, will now be described. The operator places one of the square metal pieces in the circular cavity iii of die part 2t so that the same rests on and is supported by movable element 58 (see Figs. 6 and 7). The operator then trips the press to cause the same to move upper die part downwardly toward the lower stationary part 25 of the die. For a better understanding of the operation of the device it is desired to point out that the force exerted by spring 6? is much greater than the combined force exerted by springs 34 and 59 and that the force exerted by springs is greater than the force exerted by springs 55. Movement of die part 25 downwardly into cooperative relation with die part 26 moves the face of boss 32 into the cavity 61 in die part 25 and. into engagement with the metal piece 55 to thus clamp the piece 5?. within a confined space in the die bounded by boss t2, movable element 53 and plate 5:. Further downward movement of the die part will cause boss 42. t move element 53, with metal piece it, therebetween, downwardly to compress springs whereupon the upper end of round plunger portion 63 of shaft will engage a cylindrical center portion of the underside of metal piece i5. Continued downward movement of die part 25 will compress springs 3-5 and permit relative movement between the plates. 31 and 33 whereupon the lower end of plunger 3.! will move into alignment with the face or boss 42 and thereby engage a cylindrical center portion of the upper side of metal piece l5 corresponding to the central portion thereof engaged by plunger 53. It being understood that the face 32 of plate and face 62 of plate 5! arestill spaced 9. substantial distance from one another, after the above described movements have taken place, so as to permit additional downward movement of die part 25 relative to die part 2 5. Therefore additional downward movement of die part 25 causes plungers 31 and 63 to apply force to the cylindrical center portion of metal piece to flow the. metal thereof later-ally or outwardly away from the central portion of piece it: into those portions of the confined space in the die bounded by the face walls of boss 42, movable element 58, walls of bore 56 and walls of the counterbores 43 and 59 as shown in Fig. 8 of the drawings. t will benoted by reference to the enlarged View Fig. 8, that the ends of plungers 3? and 63 are slightly rounded and that the pressure exerted, upon the piece 15 thereby causes substantiallyallof the metal t flow outwardly away from the plungers but for a thin disc-like portion Ti which in actual practice of the invention is approximately .008" in thickness at its outer. edge. It should also be noted that the face as of plate 33 on die part, 25 and the face 52 of plate 5| on die part 26 are still spaced from one another during the application of pressure, by the. plungers, to the central portion of metal piece 5 to cause the metal thereof to flow so as to permit further additional downward movement of die part 25 and consequently plunger 31 relative to die part 26. Thus further additional downward movement of die part 25, beyond that illustrated in Fig. 8, will cause plunger 31 and consequently plunger 63 to move down relative to other elements of the die and sever the disc-like part 11 from the piece 15 while at the same time applying pressure to the metal flowing from between the ends of plungers 31 and 63 to spread and fill the confined space between boss 42 and element 53 as shown in Fig. 9 of the drawings. The application of pressure to the metal flowing outwardly from the central portion of the piece l5 changes its form from a square shape to a circular shape. The further additional movement employed to fashion the piece 15 into the final shape thereof desired causes the shaft 64 in die part 25 to move against the force of spring 61 which spring therefore serves to cushion the final movement of the device. It is to be understood that in moving the face 39 of die part 25 into abutting relation with the face 62 of die part 23 the groove M in the face surface 39 serves to receive conduit 1| without damaging the same.

In Figs. 10 and 11 I have shown enlarged views of the small thin disc-like portion 11 which is severed from piece I5 and which represents all the waste metal involved in the present method of making the fin element 16. As before stated in actual practice the disc-like portion 11 is only approximately .008" thick at its edge and so thin in the center that the thickness thereof is incapable of being measured. In fact the flow of metal away from the central portion of piece 15 is frequently so rapid under the pressure applied thereto that a hole is formed in the disc 11.

After the fin element [6 has been formed by the method described the two-part die and elements thereof are returned to their normal position shown in Fig. 6. The member 21 is elevated to move die part 25 upwardly relative to die part 26 thereby withdrawing boss 42 from the cavity 6| and withdrawing plunger 31 from the collar portion IQ of fin element IS in die part 26. This permits spring 61 to return plunger 63 to its normal position and springs 59 to move element 58 upwardly to its normal position. During the return of these elements to their normal position illustrated in Fig. 6 of the drawings, air under pressure is conducted through 6 the tube 11 and directed into the cavity 6| of die part 26 and this air forces the fin element 16 and disc-like portion 11 out of the die.

From the foregoing it should be apparent that I have provided a novel method of making a. fin element with a minimum of waste. By my method the fin element may be fabricated from sheet or ribbon metal which is of low cost and provides a heat exchanger of high efficiency.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, as may come within the scope of the claim which follows.

What is claimed is as follows:

The method of making an element having a fin portion with a central hole therein bounded by a collar projecting from both sides of the fin portion which consists in, placing a malleable piece of metal in a cavity in one part of a single die set adapted to have parts thereof moved into cooperative relation with one another to provide a confined space of appropriate configuration for fashioning the piece into the shape desired, moving one part of the die set toward the other part thereof to cause portions of the die set to engage and apply pressure to a center portion of the piece to flow all the metal of the piece but a thin part outwardly away from said center portion into other portions of the confined space, continuing movement of parts of the same single die set further toward one another to cause portions of the die set to sever the thin part from the piece, and simultaneously therewith causing parts of the die set to apply additional pressure to the flowing metal to spread and fill the confined space in the die set.

SYLVESTER M. SCHWELLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,599,572 Lusher Sept. 14, 1926 1,971,083 Schlaa Aug. 21, 1934 2,227,440 Church Jan. 7, 1941 2,328,098 Remington et a1. Aug. 31, 1943 2,348,875 Beard May 16, 1944 2,413,591 Sturdy Dec. 31, 1946

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