US2348663A - Method of forming sheet metal articles - Google Patents

Description

May 9, 1944.

D. w. THOMAS METHOD OF FORMING SHEET METAL ARTICLES Filed Sept. 19, 1940 2 Sheets-Sheet l Daz io lzkromas m M M May 9, 1944. D. w. THOMAS METHOD OF FORMING SHEET METAL ARTICLES Filed Sept. 19, 1940 2 Sheets-Sheet 2 Patented May 9, 1944 METHOD OF FORMING SHEET METAL ARTICLES David W. Thomas, Youngstown, Ohio, assignor to The Youngstown Metal Products Company, Youngstown, Ohio, a corporation of Ohio Application geptember 19, 1940, Serial No. 357,375

3 Claims. (Cl. 113-116) This invention relates to the manufacture of sheet metal articles and particularly to articles made by deep drawing. invention concerns the manufacture of articles such as stove tops, sinks, or the like, having angularly disposed portions, e. g., a horizontal working surface and a back atright angles thereto.

Sheet metal articles of the character specified have been made heretofore by drawing a sheet to form the back and working surface in'a common plane, with continuous flanges bent downwardly therefrom, and subsequently bending the back up to the proper angular position relative to the supporting surface. It has been impossible, however, to prevent buckling or tearing of the flanges adjacent the line of bend between the back and the work support and it has, therefore, been the practice to slit the flanges adjacent the line of bend and to fill in the resulting notches with patch pieces as disclosed in Corrigan Patent 1,635,311. The welding on of such patch pieces increases the cost of the articles but a more serious objection is that the welded joints are very difficult to enamel satisfactorily;

I have invented a novel method of making articles of the type mentioned without the necessity of opening up notches in the flanges which have to be filled in subsequently with patch pieces. The invention also contemplates a novel method of preparing metal blanks for unusually deep draws, in such manner as to eliminate buckling or tearing of the sheet and to permit smooth flow of the latter over the forming die. In a preferred practice of the invention, I subject a sheet to successive deep-drawing operations to provide a raised portion thereon adapted to formthe back of the finished article, and having side and top flanges. I then bend the side edges of the sheet to form flanges along the portion thereof which is to constitute the working surface, which flanges are substantially coplanar with. the side flanges of the raised portions. I prefer to draw a pair of stove top blanks, for example, from a single sheet by forming a well substantially centrally thereof. Between successive drawing operations, I form wide V notches with rounded bottoms adjacent the plane along which the two blanks simultaneously formed are eventually severed. This facilitates flow of the metal as the drawing proceeds without buckling or tearing. At the same time, the slits remaining after the drawing operations are in the plane of severance and do not, therefore, appear in the finished articles.

The several stages of the preferred practice More specifically, the

outlined above are illustrated in theaccompanying drawings, as well as the finished appearance of one form ofarticle, a stove top. for the manufacture of which the method is particularly adapted.

In the drawings,

Fig. 1 is a bottom plan view of a metal sheet after an initial deep-drawing operation has been performed thereon;

Fig. 2 is a view thereof partly in side elevation and partly in section along the plane of line 11-11 of Fig. 1;

Fig. 3 is an end elevation partly in section along the plane of line IIIIII of Fig. 1;

Fig. 4 is a view similar to Fig. 1 showing notches formed in the side edges of the sheet to facilitate further drawing thereof;

Fig. 5 is a view similar to Fig. 2 showing the appearance of the sheet after a further deepdrawing operation; v

Fig. 6 is a bottom plan view of the sheet as shown in Fig. 5.;

Fig. '7 is a view similar toFig. 2 showing the sheet after a further deep-drawing operation; Fig. 8 is a bottom plan view of the sheet after the third deep-drawing operation;

Fig. 9 is a view similar to Fig. 3 showing the article after the last deep drawing;

Fig. 10 is a side elevation of one of the blanks of the pair formed simultaneously, after severance;

Fig. 11 is a side elevation of a finished stove top-made from the blank shown in Fig. 10;

Fig. 12 is a plan view thereof and Fig. 13 is a front elevation.

Referring now in detail to the drawings, a metal sheet I0 of suitable gauge and dimensions is subjected to a deep-drawing operation to form a well ll substantially centrally thereof. The well has a bottom l2, sides l3 and ends H. Alternatively, the well ll may be described as a raised portion having a top l2, sides l3 and ends l4, depending on whether the sheet is viewed with the displaced portion extending upwardly or downwardly from the general plane thereof. The well or raised portion II is preferably elongated transversely of the sheet, as indicated in Fig. 3. According to the usual die-drawing procedure, the displaced metal is pressed downwardly from the original plane of the sheet.

During the initial deep-drawing operation, beads or grooves l5 are formed along the side edges of the-sheet ID by the usual splines and grooves in the dies to restrain inward flow of certain portions of such edges on subsequent deep-drawing operations as'will be more fully described hereafter.

The deep-drawing and grooving of the sheet- II is eflected by known apparatus which requires no illustration or description further than to state that it includes a suitable press, a die ring,

a holding ring and a punch.

After the initially fiat sheet of metal stock has been converted by the first deep-drawing operation to the condition illustrated in Figs. .1 through 3, I form notches I along the side edges of the sheet. The notches it have the shape of a wide v with their bottoms rounded as at IT. The notches II are located along the side edges of the sheet so as to be substantially symmetrical with the central transvers'e plane through the well Ii, indicated at I 8. The notches permit relatively easy flow of the metal in the side edges of the sheet adjacent said central transverse plane since they leave no excess which might tend to wrinkle or buckle. The metal in the side edges spaced from said plane'is slightly restrained against flow by the grooves or beads Ii, at least as compared to themetal adjacent the sides l3 of the well Ii. The shape of the notches l6, furthermore, permits smooth flow of the metal adjacent the central transverse plane as further deep-drawing operations are performed. As shown in the drawings the portions of the sheet adjacent thenotches are maintained in substantially their original plane they are drawn in.

After the partially formed sheet, comprising a pair of blanks, has been notched at H, it is subjected to a further deep-drawing. operation to increase the depth of the well il. Figs. 5 and served that the resulting well Ii is deeper than the well II but otherwise has about the same dimensions as the latter. As clearly shown in Fig. 6, the second deep-drawing operation causes the notches ii to close partially by reason of the flow of the metal of the side edges of the sheet into the ends of the well as the depth of the draw is increased. The sides of the notches it, in fact, are actually brought into abutment over a portion of their length forming seams is lying substantially in the central, transverse plane it. This results from shaping the notches to remove just the amount of metal necessary to avoid any excess which might cause wrinkling or buckling.

The partially drawn sheet shown in Figs. 5 and 6 is next' subjected to a further deep-drawing operation to convert it to the condition illustrated in Figs. 7, 8 and 9. The third deep-drawing operation. like the second, further increases the depth of the well Ii" without materially changing the other dimensions thereof. The notches ii are further closed and the seams l9 lengthened. In some cases, the second deepdrawing operation may be omitted and the sheet converted directly from the condition shown in Figs. 1 to 3 to that shown in Figs. 7 to 9.

After the final deep-drawing operation, the

just inside the ribs l5 and severed along the central transverse plane I8, producing a pair of blanks such as that shown in Fig. 10. As shown, each blank has a substantially plane portion 2| adapted to form the working surface of the finished article, i. e., stove top, sink, or the like. It also has an upwardly extending back 22 having side flanges 23 and a top flange ished stove top, the end edge of the plane porin any openings with patch pieces as has been I the practice heretofore. In forming the fintion 2| is bent downwardly as at 21 to form a resulting article is trimmed along the side edges front flange continuous with the flanges 26. The edges of the side flanges 2i and the front flange, 21 are bent inwardly to form stiffening flanges 20 and 29. The rear edges of the sides "and top 24 of the back 22 are also flanged as at 200 to provide increased rigidity.

It will be understood from the foregoing description that the finished article produced by my invention has a supporting surface, the metal of which is for the most part in the same plane as it was in the original sheet of metal stock, and a back portion which has-been drawn out .of the general plane of the original sheet and extends generally at right angles to the supporting surface. This is in contrast to articles having a supporting surface and back formed by conventional practice, wherein the -metal forming the back is in substantially its original plane and is simply bent up at right angles to the supporting surface.

It will be apparent that the invention is characterized by important advantages over the conventional practice in that it provides a simple, direct method of forming articles having a support-' ing surface and a back with continuous flanges, without the necessity of applying patch pieces to fill out notches opened up during the forming operations, thereby eliminating the cost of applying such pieces and the unsightly appearance presented by the resulting joints, even when enameled over. In addition, the invention is applicable generally in the deep drawing art to cause the proper flow of metal from the edge portions of a sheet into the deeply drawn portion, without buckling or tearing. While I have disclosed the invention in detail with special reference to the manufacture of stove tops, it may also be utilized in the manufacture of other articles such as sinks, bath-tubs, etc. In the manufacture of the lastnamed, particularly, the notching of the edges of a sheet as disclosed herein, is of particular advantage, because of the long dee draw which must be made in a sheet of stock to form the body of a tub.

Although I have described and illustrated a preferred practice of my invention, it will be recognized that changes in the procedure disclosed may be made without departing from the spirit of the invention or the scope of the appended claims. As an example, while I have disclosed a method of forming stove stop blanks in pairs, it is evident that they may also be formed singly by appropriately modifying the operations described.

I claim:

1. In a method of making sheet-metal articles, the steps including subjecting a metal sheet to a deep-drawing operation to form an elongated well therein spaced from the edges of the sheet, cutting V-shaped notches in the edges of the sheet at points adjacent the longitudinal central plane through the well to remove excess metal and prevent wrinkling or buckling on further drawing,

subjecting the well to a further deep-drawing operation and confining the portions of the sheet adjacent the notches substantially in their original plane so that the edges or each notch come together progressively as the metal adjacent the notches is drawn inwardly, without wrinkling or buckling.

2. In a method 01 making pairs of blanks by deeply drawing a metal sheet successively, the steps including subjecting the sheet to a die-drawing operation to form a well spaced from the sheet edges, forming opposed notches in the side edges of the sheet and substantially in alinement with a central transverse plane through said well, subiecting the well to a further die-drawing operation to increase the depth of the well, while maintaining the portions of the sheet adjacent the notches in their original plane whereby the edges of each in two the sheet and the well formed therein, along said first mentioned plane.

3. In a method of forming a raised back integral with a sheet-metal working surface such as -a stove top, the steps including deeply drawing the portion of a metal sheet spaced from the edges thereof to form a generally rectangular well extending transversely of the sheet and having a bottom, sides and ends, said sides and bottom forming said backs and horizontal flanges at the top thereof, respectively, for two such surfaces disposed back-tc-back, cutting the sheet in two along the median longitudinal plane through said well, bending down the edges of the sheet adjacent said ends to form flanges along the side edges of said'surlace co-planar with the ends of said well, leaving a portion of each hall of the sheet in its original plane to form said surface, and bending down the edge thereof parallel to the back.

DAVID W. THOMAS.

CERTI FI GATE 0F CO ERECTION PatentNo. 2,5h8,665. May 9, 191 1;.

DAVID W. THOMAS.

It is hereby.certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, sec- 0nd column, line 7, for "havings" read --having--; line 6 for "stop read --top--; and that the said Letters Patent should be read with this correction thereinthat the sane may conform to the record of'the case in the Patent Office.

Signed and sealed this 1st day of August, A, D. 19111;.

LeslieFrazer (Seal) Acting Commissioner of Patents.

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