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Publication numberUS2205893 A
Publication typeGrant
Publication dateJun 25, 1940
Filing dateSep 3, 1937
Priority dateSep 3, 1937
Publication numberUS 2205893 A, US 2205893A, US-A-2205893, US2205893 A, US2205893A
InventorsMagnus Unger
Original AssigneeGen Electric
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method of corrugating a heatradiating tube
US 2205893 A
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Description  (OCR text may contain errors)

June 25, 1940. M, UNGER METHOD OF CORRUGATING A HEAT-RADIATING TUBE Filed Sept. 5, 1937 2 Sheets-Sheet 1 Fi m Fig. 9

fil ml mm 6 m ew m vn 1 hw H M by )V June 25, 1940. M. UNGER 2,205,893

METHOD OF CORRUGATING A HEAT-RADIATING TUBE Filed Sept. 5. 1957 '2 Sheets-Sheet 2 Inventor": Mangus Un er; b #W a M 9 His Attorneg.

Patented June 25, 1940 PATENT METHOD OF CORRUGATING A HEAT- RADIATING TUBE Magnus Unger, Pittsfield, Masa, assignor to General Electric Company, a corporation of New York Application September 3, 193?, Serial No. 162,250

2 Claims.

My invention relates to a method of forming metal tubes for heat radiators. The invention provides a tube particularly adapted for use in a heat radiator for cooling the insulating liquid in which electrical apparatus such as transformers are immersed. Heat-radiating tubes of round cross-section are often used in heat radiators. By corrugating the tube, however, the amount of liquid in the tube is substantially reduced with little corresponding reduction in the rate at which heat is dissipated. The corrugated tube is therefore substantially as efiicient in dissipating heat as is the round tube and a considerably smaller quantity of expensive insulating liquid is required. The general object of the invention is to provide an improved method of forming a heat-dissipating metal tube.

The invention will be better understood from the following description taken in connection with the accompanying drawings in which Fig. 1 is a sectional view of part of a liquid-immersed transformer provided with a heat radiator including heat-radiating tubes formed in accordance with the invention; Fig. 2 is an explanatory detail view, partly in section; Figs. 3, 4, 5 and 6 are views indicating steps in the preferred form of the process for forming a heat-insulating tube in accordance with the invention; Figs. 7, 8, 9 and 10 are views indicating steps in a modified form of the process; Figs. 11 to 18 inclusive are views indicating steps in another form of the process; Fig. 19 is a perspective view of a portion of a partly-formed tube and parts of a die used in the process.

Like reference characters indicate similar parts in the different figures of the drawings.

The heat-radiating tubes ill, formed in accordance with the invention, are shown in Fig. 1 as being assembled between an upper header l l and a lower header l2 to form a radiator for cooling the insulating liquid l3 in which a transformer it is immersed. The ends of a round tube are reduced in diameter by any desired method, such as the swaging method disclosed in my Patent No. 1,895,947, issuedv January 31. 1933, and assigned to the General Electric Company. The round tube with its reduced ends is then placed between two die members l5, as indicated in Figs. 3 and 19. The preferred form of die is shown in Figs. 3, 4, 5, 6 and 19. The two die members l5 are alike and are approximately as long as the tube ill. The face of each die member is formed with a groove or channel IS with symmetrical convex sides. The round tube lll with its reduced ends is placed between the die mem- 55 bers IS with no internal support for the tube,

iii)

as indicated in Figs. 3 and 19. The die members are then forced toward each other as indicated in Fig. 4. Two convex sides of each die member apply pressure in parallel directions to two spaced longitudinal portions of the tube with which they are in contact. This-presses the two sides of the tube next to the die members it toward each other and produces two sharp, longitudinal convex bends ll along the sides of the tube, the diameter of the tube in the direction of the presto sure being reduced and its diameter at right angles thereto being increased. The die members are now separated and the tube it turned ninety degrees with its sharp bends ii in the bottoms of the grooves l6 of the die members, still in with no internal support for the tube, as shown in Fig. 5. The increased diameter of the tube is then reduced until the two diameters are substantially equal by pressing the die members it together, as indicated in Fig. 6. to form two more an longitudinal, sharp convex bends it in the tube it, the longitudinal bends I1 and I8 being of course uniformly spaced and the convex bends being joined by concave tube portions l9 formed by the convex sides of the grooves it of the die g5 members. The grooves l6 and their convex side faces are preferably so spaced and proportioned that when the die members I5 are pressed together, as indicated in Figs. 4 and 6, the convex side faces of the grooves it will just meet the so outer surfaces of the reduced end portions of the tube ill. The convex side faces of the grooves it thus serve to assure proper alignment of the tube ill along the axis of the die and consequent symmetrical formation of the tube when the die pg members are pressed together.

A modified form of the process of forming the tube It is indicated in Figs. '7. 8, 9 and 10, Where the round tube Ill is first pressed between two die members 20 with their faces having grooves M with plane side faces. The die members 20 are then separated, the tube It] turned through ninety degrees and the die members 20 again pressed together to give the tube ill a square cross-section except that the corners are slightly rounded. The M tube If! is next pressed between two die members 22 having faces with grooves 23 with convex side faces, as shown in Fig. 9. In this step of the process the die members 22 are not pressed quite together but only until the two longitudinal, m sharp bends 24 are produced. The die members 22 are then separated, the tube turned through ninety degrees and the die members 22 again pressed together, as shown in Fig. 10;, to give the tube I9 its final symmetrical configuration with bers 26, as indicated in Fig. 11, and the die members pressed toward each other, as indicated in Fig. 12, until the two longitudinal bends 21 are formed in the tube. These longitudinal bends 21, however, are not as sharp as is finally desired. The die members 26 are then separated, the tube turned through ninety degrees, as indicated in Fig. 13, and the die members 26 again pressed partly together, as indicated in Fig. 14, until two more longitudinal bends 28 are formed but not with the finally desired degree of sharpness. The die members are then separated, the tube l0 turned through ninety degrees, as indicated in Fig. 15, and the die members then pressed together, as shown in Fig. 16, to give the longitudinal bends 28 their finally desired sharpness. The die members 26 are then again separated, the tube l0 turned through ninety degrees, as

indicated in Fig. 17, and the die members 26 again pressed together to give the longitudinal bends 2'! their final degree of sharpness as shown in Fig. 18 and the tube l0 its final symmetrical configuration. In this form of the method, indicated in Figs. 11 to 18 inclusive, the longitudinal sharp bends in the tube are produced more gradually with less tendency to crack the tube than in the preferred form indicated in'Figs. 3 and 6 and the greater number of steps involved may be adopted if found desirable.

The invention provides a very rapid and efflcient but simple method for producing a corrugated heat-radiating tube by pressing corrugations into the outer surface of the tube but without the necessity of providing any internal support for the inner surface of the tube. The invention has been explained by describing and illustrating a corrugated heat-radiating tube and steps for producing it but it will .be apparent that changes may be made without departing from the spirit of the invention and the scope of the appended claims. 7

What I claim as new and desire to obtain by Letters Patent 01' the United States is:

1. The method of corrugating a heat-radiating tube of round cross section, said method including the steps of applying pressure 'in parallel directions to two spaced longitudinal portions of each of the opposite sides of the tube andwith no internal support-for the inner surface of the tube to collapse the tube and form a first pair of relatively sharp convex bends in diametrically opposite portions of the tube between said two sides, rotating said tube through a right angle and then applying pressure to two spaced longitudinal portions of the tube at the two convex bends to collapse the tube and form asecond pair of relatively sharp convex bends in diametrically opposite portions of the tube at right angles with respect to said first pair of bends.

2. The method of corrugating a heat-radiating tube of round cross section, said method including the steps of applying a first pressure in parallel directions to two spaced longitudinal portions of each of the opposite sides of the tube and with no internal support for the inner surface of the tube to collapse the tube and form two longitudinal concave portions in each of the I opposite sides of said tube and forming a first pair of relatively sharp longitudinal convex bends in diametrically opposite portions of the tube between said two opposite sides, applying a second pressure in parallel directions at right angles to said first pressure at said concave portions on opposite sides of said first pair of bends to further collapse the tube and form a second pair of relatively sharp convex bends in diametrically opposite portions of the tube at right angles with respect to said first pair of convex bends.

MAGNUS UNGER.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2591442 *Feb 9, 1946Apr 1, 1952Simplex Electric Co LtdMethod of making electric heating elements
US2742946 *Nov 18, 1949Apr 24, 1956United States Steel CorpMethod of and apparatus for forming a composite tubular support
US2758491 *Dec 6, 1951Aug 14, 1956Aircraft Marine Prod IncCrimping dies for electrical connectors
US2972781 *Nov 5, 1957Feb 28, 1961Kahn David IncMethod of deforming plastic articles
US3260098 *Sep 6, 1963Jul 12, 1966Gill John BTool for closing and opening a metal tube
US3266287 *Mar 29, 1962Aug 16, 1966Gill John BApparatus for closing and opening a metal tube
US3583188 *Feb 20, 1969Jun 8, 1971Nakamura MasanobuAutomobile rear axle housing and method of making same
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US4513601 *Sep 29, 1982Apr 30, 1985Cycles PeugeotMethod for locally deforming a round tube into a tube comprising planar surfaces and a forming punch for carrying out said method
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Classifications
U.S. Classification72/370.2, 72/370.16, 29/890.45, 72/416, 72/370.23, 72/404
International ClassificationB21D15/00, B21D15/02
Cooperative ClassificationB21D15/02
European ClassificationB21D15/02