US1316636A - Method of forming sheet metal. - Google Patents

Description

F. M. OPITZA METHOD OF FORMING SHEET METAL.

I APPLICATION FILED OCT. 1', I918, 7 1,316,636. PatentedSvpt. 23, 1919.

1Q) 21 W1 22 1Q 22) 225 25 I m 5 2 9.16 QZ'QUenZ w flf, $40.16; k

' a pleasing appearance of the radiator.

niurrnn s rarjas earner ora ion.

FEED M. O'PITZ, 0F RACINE, WISCONSIN, A$IGNOB TO PERFEX RADIATOR COMPAN Y, 01? RACHE, WISCQNSIN, A CORPORATION OF WISCONSIN.

METHOD 0F FORMING SHEET METAL .epplicetionfiled October 31, 1918.

my first papers, residing at Racine, in the county of Racine and State of Wisconsin, have invented aicertain new and usefullmprovement in Methods of Forming Sheet Metal, of which the following is a full, clear,

concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to a method of forming sheet metal.

While the invention is particularly-useful in connection with the formation of radiator tubes. 1 do not intend to limit the invention to such use or purpose only.

adiator tubes made up of single pieces pen'ding case, Serial No. 200.252, filed March 5. 1917, of which the present application is an improvement.

For the sake of efficient operation, it is desirable to make the tubes with as large a superficial radiation area as possible and to bring all parts of the Water or the cooling medium near the radiating surfaces to cool the contents of the tubes. It is also desir able that the Walls of the tubes through which transfer of heat is to be accomplished should be as thin as mechanical strength will permit. To be able to make the tube out of sheet metal is desirable, because of the cheapness of such sheet metal and because of. the strength of the tubes when thus formed. There is also a strong: demand for To meet these requirements 1 form the tubes outof sheet metal with lateral corrugations ofsuch form as to provide. when these tubes are assembled into a core, a umber of round cylindrical passages for the air between the corrugations of adiacent tubes The par: tlifllltll formation which I employ gives the appearance of a solid block with a large number of closel grouped cylindr cal air passages through the core with a of vertical fins or flanges between rowe of our Specification of Letters Patent.

Patented se t. as, rare.

Serial No. 25?,764.

cular holes where the fold or seam along the front face of each tube. is made. The holes of one vertical row are offset by one-half the pitch distance with respect to the holes of adjacent rows so that a maximum num-,

ber of holes is possible.

This arrangement requires the ofl'settmg of the corrugations of the tube and such offsetting has heretofore been a practical diliiculty because of the uneven drawing of the metal, as heretofore practised.

To form the circular holes it is necessary that the tubes have lateral corrugations forming complete halves of the sides of the holes, The tubes are made of a thickness substantially equal to the diameter of the holes and semi-circular depressions lie on each side of the central flange or seam. The front and rear faces of the tubes are made to lie as nearly as possible in planes parallel to the front and rear faces of the core in the preferred form of my invention, although this is not essential; The corrugations are, in the preferred form of my invention, at rig'ht'angles to the face of the core, but this also may be varied.

I am aware that heretofore tubes have been made with corrugations along the sides and that said tubes have been made of a single sheet of metal, but no one heretofore has produced a tube havingcomplete semicircular depressions to form complete circular holes so that the air within the hole is in contact with the coolingmedium on all sides.

Furthermore the production of a semi-circular depression with a substantially square integral end flange is novel and has not herenovel principle of working the sheet metal,

i and it is with the application of this novel principle of working sheet metal that the present application is concerned.

I have found that where it is desired to produce a corrugated metal tube or part of a tube in which the side Walls are to be corrugated and the end walls are to be plain,

- that the metal along the margins which form the end walls may be shrunk sufliciently to supply the extra material or metal required to form the corrugations. I

This is opposed to the teachings of the maintained at their original thickness and the parts to he corrugated are stretched in order to supply the surplus required for the corrugations.

The general principle involved is that where a plain sheet of metal is to be distorted out'of a plane shrinking of one part of the metal or sheet may be accomplished 10. under certain conditions with better eifcct and more easily than stretching or expand ing the other part. The decision between shrinking and stretching should be made upon the basis of the amount of metal that must be moved by one as against the other, and by any special diiiiculties which would be involved. .l-inother subsidiary principle that is involved relates --to the matter of forming the metal about-a sharp shoulder or projection. Where the shoulder or projec tion is of such a character or shape that the metal would be stretched along a sharp" line or point, I find that it is possible to shrink or fold the metal about the form or projection so as to leave the desired shape with out damage to the metal in any way.

In order to explain to those skilled in the art the manner in which these principles are to be applied in actual working of sheet metal, and to explain a specific embodiment of the invention, I shall now describe in connection with the accompanying drawings the manufacture of radiator tubes for forming the core of a radiator.

In the accompanying drawings- Figure 1- is an isometric view of apart of the core of a radiator employing tubes constructed in accordance with my invention;

Fig. 2 is a fragmentary front elevation of a Radiator core of the form shown in Fig. 1;

1g. 3 isometric projection of the sheet of metal formed according to the first step of my in-. vention'; Fig. 4: is a similar diagrammatic view in isometric projection showing the step of corrugating' the bottom and edge wall of each of the gutters or grooves shown in Fig. 3;

illustrating diagrammatically the manner in which the metal is shrunk along the fla g that is the marginalportion, and the end walls to form the semi-circular corrugation;

' 56 Fig. 6 is a front elevation of a part of the finished corrugation showing the manner in which the" metal has been folded along the end walls of the tube or part of the tube;

Fig. 7 is a fragmentary sectional view taken from the inside with respect to Fig. 6 showing the manner in which the'metal is folged inwardly along the end-walls of the t1! Fig. 8 is a sectional view taken on the I5 line 8--8 of ig. 6 showing the folding and is a diagrammatic illustration in' Fig. 5 is a fragmentary isometric view thickening of the metal "alone; the margin and end walls of. the tube;

Figs. B'tq 21 inclusive illustrate various steps in the manufacture of commercial radiator tubes. 7

Fig. 9 is a plan view of a sheet passing through the first stage of folding toform the margins and end walls of the tube; r

Fig. 10 is an end view of the same;

igs. 11 and 12 are a planview and an 5 end view respectively of the second step which consists in forming the corrugation in the sides of the tube and shrinking the ends and margin;

Figs. 13 and 14 are-plan view andend View respectively of the sheet after it has been moved forward one pitch distance in.

the dies.

liigs: 15 and 15 are planview and end view respectively of the sheet after it has advanced completely through the dies. show ing the creasing along the central margin for folding;

Fig. 17 is a plan view ofthe corrugated and creased sheet after it has been trinuned he in preparation for folding;

. Fig. 18 is an end view of the same taken from the left of Fig. 17;

Fig. 19 illustrates the step of folding the. central margin and-starting the foldofithc edge margin, which step is accomplished by a power press;

Fig. 20 is an end view of the tube after; the fold has been rrimpleted and the seam j has1 been closed at the one edge of the tuhet' led an i Fig. Zlis a side view of the completed tube taken from the left of Fig. 20.-

' The radiator which I preferably form is of the vertical tube type having suitable we headers at the upper and lower ends oi the tubes, these tubes being grouped together in contact to form a solid core, a section of which is illustrated in Fig. l. The 1 I core 1 comprises the series oi. tubes 2 which lit-1 have water passageways 3 passing vertically-g through the same. .The si walls of they tubes 2 are provided with the semi-circular depressions or corrugations i-{betiireen which,

remain the flat side walls 5 which are placed 3.3. in contact with adjacentsimilar walls 'off the tubes on each side of-the articular tube. These semi-circular deprcssiilns, when thus brought into register, form thevcylindricai V.

'holes or air passagew'ays 6 mm liwhich we the air for cooling the liquid within the core 1 passes, with the flanges or some? and 8, which are formed respectively it folding the sheet and by joining thememargins, as will be described later.

To form the tubes I provide WStflp of sheet metal of suitable width and thickness such as disclosed inmy copending applies its mimosa tion Serial No. 257,765, filed Uotober 11,

1918. The tube might be made up of two sheets of metal one for each side but preferably 1 form both sides simultaneously and form the tube by folding along a center margin, as will bedescribed later.

The. sheet fed into suitable dies which form the sheet into the double gutter shown at the right of Fig.9 and shown in Fig. The two gutters 11 and 12 are formed with the side margins 13 and 14, respectively, and the central margin 15 which forms the folding margin to form the complete tube. While I have shown in Fig. 3 complete gutter formed in this manner, it will be understood that the step of corrugating the gutter as fast as it is formed is found in practice to be preferable, as these operations may be performed by a single pass through a suitable stampin or punch press, as isdescribed in my copencing application. The gutter 11 has the bottom Wall 16 which becomes the side ,Wttll of the tube when completed, and the end Walls 1? and 18 which become the front and rear end faces of the tube when completed.

The gutter 12 is similiarly formed with the bottom wall 19 and the end walls 20-and 21. A description of the operationof forming one gutter will suffice for both. The depth of the gutters 11 and 12 is substantially half of the thickness of the finished tube.

So far in forming the tube, the metal has not been disturbed, either by stretching or,

thereafter flattens out the margins and eX- tends the formation of the gutter. Reference is made to said application for a disclosure of a commercial form of corrugating die press. The corrugations 22 in the gutter 11 are offset with respect to the corrugations in the gutter 12 by one-half the pitch distance so that the circular holes 6 formed between tubes are staggered by the same amount. The first step in the corrugating dies forms a complete corrugation at 22 in the gutter 11 and belief a corrugation 1n the gutter 12, as s'hown inFigs. 1'1' and 12.

I Thereafter thesheet is advance d by a strip equal to the pitch distance between corrugations, the second step being illustrated in Figs. and. 14:.

The die which forms the gutters thousandths of an inch.

As these corrugations 22 are formed, the metal along the margins 13, 14 and 15,'and along'the end walls l7, 18, 20 and 21 is thickened by shrinking, this being indicated by the shading 23 and the increased thickness indicated in Figs. 12, 1% and 16. The

. thickness at the points indicated by the referthe central margin 15 is given a slight crease,

as indicated at 24:, by a suitable groove and projection upon the coiiperating part of the dies. Durin the corrugating operation the thickening o the metal along the margins and end Walls results in forming on the surfaces of these parts a great number of small surface Wrinkles which are indicated by the shading 23. The forming of the line 24 which is in the nature of a very slight crease is to insure that allpf the surface Wrinkles have been flattened out along the line where the folds is to'be formed. 24 which I term a crease need be formed only to the extent of insuring that there are no transverse wrinkles running across the central part, which creases, if theydid exist, would tend to form a ragged or uneven-fold. lhe flattening out of the surface Wrinkles caused by shrinkage of the sheet does not produce an absolutely flat surface, as the Wrinkles are still visible, but for practical purposes these surface irregularities are immaterial.

After the sheet has been completely corrugatedit is cut into suitable lengths, and the margins 13 and 14: which are to form the scam are then trimmed by runnin the sheet through a suitable shears Whic is guided along the central groove 25 formed between the Walls '18 and 20 It will be noted that the margin 13 is of less Width than the margin 14. This is for the pur pose of formin a folded seam. The corrugated sheet shown in Figs. 17 and 18is then placed in a suitable die and is folded along the line 24 on the central margin 15, as indicated in Fig. 19, and the edge of the margin 13 is bent up as shown at 26 in Fig. 19. The tube in the condition shown in Fig. 19 is then laid in a suitable die and is struck with another die which closes the seam 8 by folding the metal of flange 13 over the edge of the flange 14 into a folded seam, as

Hence this line shown in Fig. 20; A series of such tubes are then grouped together into a core, the front and rear faces preferably, but not necessarily, being dipped in solder to cause union between the ad acent portions and to close the folded seam 27 where themargins 13 and 14 have been joined.

I shall now endeavor, in connection with Figs. 3 to 18 inclusive, to make clear the movement of the metal in forming the corrugated tubes. When the double gutter, as shown in Fig. 3, is formed, the metal is novwhere warped as the margins 13, 1a and 15 lie in substantially the same plane, and the end walls 17, 18, 20 and 21 lie in substantially parallel planes except for the small amount of taper necessary in practice to give clearance to the dies. This taper has been somewhat exaggerated in the draw: ings. Considering the utter 11 shown in Fig. 3, independently o? the gutter 12, as

it is obvious that the formation of one is similar to the other, in order to secure the corrugations 4 there must be greater lineal length of material in the bottom wall 16 than in the flanges 13 and 15 for the very obvious reason that the circumference of the semicircle is considerably greater than the diameter of the semicircle. In order to pro-' duoe this surplus of material either the metal in the bottom wall 16 and in a part of the end walls 17 and 18, must be sufiiciently stretched to produce this surplus or 'the surplus of metal must be secured in some other manner. Independently of which way it is secured, I believe that I am the first to form an open trough or gutter and then corrugate the bottom of the gutter with the corrugations running. through the end walls.

The particular manner in which I secure 4 the surplus metal for forming the corrugations is by shrinking the metal along the margins 13 andvl5 and, to a certain extent, the end walls 17 and 18. Consider the gutter 11 after it has been corrugated, and it will be seen that the part of it, as shown in exploded or dissected form-in Fig. 4, will consist ofthickened margins 13' and 15 and thickened end walls 17 and 18' and the corrugated side walls 16' of original thickness.

It is at once a parent, on comparing Figs. 3 and 4, that t e end walls 17 and. 18 mnst take up a relatively large proportion of-the in the metal which it must undergo, it will be seen that the length as shown in full lines must be contracted to the length shown between dotted lines 28 and 29, and the edge 30 of the bottom wall 16 must be drawn in to the dotted lines, must be displaced later.- ally in orderto permit the corrugations to run through the end. wall. As the cylindrical die member pushes the bottom wall upward and crushes the end walls 17 and 18, the metal within those portions of the end Walls is partly taken up by thickening of the metal between corrugation-s in the end walls and is also partly taken up by crumpling or folding as is indicated in Fi s. 6, 7 and 8. There is both an outward fol ing, as Shown at reference numeral 33, and an inwardiclding as shown at reference numeral 34 in ,Figs. 6, 7 and 8. This disposition of the metal can be clearly seen in the tubes after they are formed.

As I have above explained, there is a tendency for surface wrinkles to form along the margins and along the end walls. This may be permitted to a greater or less extent, depending upon the closeness of the fit of the die. s

I do not intend to be limited to the precise details shown and described as my invention, as relating tothe formation of corrugated tubes and the like, 1s broadly new.

I claim:

1. "In the method of forming a corrugated metal tube, the combination of the following steps :first forming a gutter having bottom walls and end walls and marginal portions,

and then corrugating the bottom wall with corrugations which runthrough theend wall. 2. The method of forming a corrugated metal tube having uncorrugated portifis Y which comprises shrinking the uncorruga portions to, provide a surplus of metal re? quired along the corrugated portions.

3. The method of forminga metal tube having corrugations along-part of its walls which comprises shrinking the unmrrugated portion of the walls andsimultaneously increasing the thiclmess thereof while maintainingthe portions of the walls to be corrugated at substantially the original thickness. v q

' 4. The method of forming a metal tube having corrugations along part of its walls which comprises shrinking the uncorrugated portion ofthe walls and simultaneously increasing thethickness thereof while maintaining the portions of the walls to be corrugated at substantially the original thickness,

and oorrugating said latterfportion. .5. The method of forming a sheet metal tube having corrugated side faces and in.-

corrugated end faces which comprises, the following steps: eor'rugating the side fag-res while mamtammg them atsubstanti'ally r. The method of forming a corrugated metal tube having uncorrugated portions whichcomprises shrinking the uncorrugated portions and simultaneously increasing the thickness thereof while maintaining the portions to be corrugated at substantially the original thickness, corrugating said latter portions and then forming a seam along the uncorrugated portions.

8. In a method of the class described, the

following steps; shrinking the marginal portion of a sheet of metal to produce a fullness or surplus of metalat other portions, and corrugating said other portions to take up fullness or surplus thereof. 9. The method of forming a tube of the lass described, whichconiprises the follow: 'ng steps: forming a plain sheet into a gutcrhaving a flat bottom wall and flat side valls at. substantially right angles to the ottom wall and flat marginal flanges lying substantially parallel to the bottom Wall, fore shortenin the entire gutter and simultaneously forming corrugations in the 'bottom wall of the gutter, said corrugations ex tending into and through theside walls of the gutter.

10. In the method of forming a tube of the class described. the combination of the following steps: forming a plain sheet into a. gutter having a. bottom wall and side walls, said walls being substantiall at right angles to the bottom .Wall, fore-s ortening the gutter to thicken the side walls of the gutter and corrugating the bottom wall-o" the gutter while maintaining the metal said corrugations at substantially the original thickness.

11. The method of forming a tube of the class described, the combination of the following steps: bending a plain sheet into the form of a gutter having bottom Walls and side walls, the side walls lying at substantially right angles to the general plane of the bottom wall of the gutter and pressing the bottom wallinwardly in a semicircular depression, said pressure being extended through the side walls to crush them edgewise to form a complete transverse semicircular corrugation.

12. The method of forming a sheet of metal into a tube which includes the following steps, forming the sheet into sidewalls,

end walls and a joining margin, and forming cornug'ationsin the side walls extending through the end walls.

l3. Inthemethod of formin a sheet into a tube; the lcembination of tie following steps: forming the sheet metal into a gutter having a bottom wall and side walls at substantially right angles to the bottom wall, then forcing a portion of the side wall inwardly to form a continuous groove transverse to the gutter and simultaneously crushing the side walls edgewise to form a fold of the metal at each end of the groove.

'14. In the method of forming a sheet of metal into a tube, the combination of the following steps: forming the sheet into a gut ter havin a bottom wall and side walls at substantidlly right angles to the bottom.

* wall, then pressing edgewise with a rounded forming tool upon the side walls and simultaneously. pressing the bottom wall in- I wardly to form a complete transverse groove across the gutter.

15. The method of forming tube iron:

sheet metal which comprises forming the sheet into a pair of gutters with margins. at their outer edges and niiargins between them, then forming a crease longitudinally centrally of said central margins, then told ing the two gutters along said crease into the form of a tube, then joining the edges of said gutter to form a closed seam.

16. The method of forming a tube which comprises folding a sheet of metal rentinuously and progressively into a pair of gutters joined by an integral margin, than oorrugating said gutters and simultaneously shrinking the metal along the central ma in, then. creasing the central mar inand ending the two gutters toward each other and sea ing the free edges of the same.

1'3. A radiator tube formed of sheet metal comprising unita j front and rear faces of greater thickness t ian the original sheet and corrugated side walls of a thickness substantially equalto or very slightly less than that of the original sheet,

Mill

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18. In a radiator, a tube havin front and.

rear faces and side walls, said si e walls being corrugated in substantially semicircular rugations.

19. In a radiator, a tube having front and 1 rear faces and side walls, said side walls being corrugatedin substantially semi-circular corrugations, said front and rear faces having folds of metal about the ends of the corrugations, said front and rear faces lying at substantially right angles to the side walls.

20. In a radiator, a tube having front and rear faces and side walls, said side walls being corrugated insubstantially semi-circular corrugations, -said out and rear corrugations, said front and rear faceshav- .ing folds of metal about the ends of the cor- Vends Ofthe'cQI rRgatiOns; 1 ant? and wai 6 gamma faces be" thikened byshrihkage of tha 22. The method of forming out of sheet metal aniafi1gg flds .of .meta1 mm he .nmm} a wrmgnted wbe havmg sicie walls which om-prises laterally 21\. I;[n the process desaribed, thasteps of displacing @sarts .0f the metal which form 1 I forming a .Sheet inbo; a'pair 0f gutters with the side we Is, and simultxz necusly crushing a folding margm'fiatween the two gutters together the adjacent parts of the metal 8h1:ink'ing 3 113; of the gathers, includmg the forming the and walls.

fo'lding margmto thi n the metal thereat In WAEIIBSS Whmufil heiemito subscribe" smoothingout the metal along a folding lins y hams this 8th day. of October, A. D. 2

on. :said margin and folding,- said gutters o- 1918.

ward each'other on said line; I FRED M. OPITZ.

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