US2237535A - Method of making welded connections for sheet metal articles - Google Patents

Description

' A ril 8, 1941.

F G. WAHL 2.237.535

METHOD OF MAKING WELDED CONNECTIONS FOR SHEET METAL ARTICLES Filed Dec. 9, 1938 Pig. 8.

INVENTOR. f76d 6. Q) a 7/ Z Patented Apr. 8, 1941 METHOD OF MAKING WELDED CONNEC- TION S FOR SHEET METAL ARTICLES Frederick G. Wahl, Detroit, Mich, asslgnor of onehalf to Gordon M. Evans, Detroit, Mich.

Application December 9, 1938, Serial No. 244,813

3 Claims.

This invention relates to'the making of articles Irom sheet metal or the like wherein two or more pieces are joined together at a seam and particularly where the article thus formed is to be finished with a surface of porcelain or the like.

The invention can be disclosed and described in connection with the making of relatively deep receptacles, such as for example, the tub portion of a washing machine, although, of course,

the invention is not limited to such an article. It has been the practice to'- make the tub of a washing machine from a single piece of metal subjected to a. drawing operation, and then the shaped article, in many cases, is given an application of porcelain. There is'a considerable draw in the metal in this case and fairly thick sheet stock has to be employed to stand the draw. Also, the drawing machinery is expensive and large, with the result that there is a considerable outlay for equipment.

This invention aims to provide a method wherein an article'such as a deep receptacle can be made from two or more pieces -of sheet metal without any substantial drawingjaction. Thus lighter stock can be used and theinitial capital expenditure for equipment is materially reduced and, moreover, very little sheet metal is wasted in the process. To these ends sheet metal parts may be suitably fashioned by a rolling or forming operation or by a stamping operation, or both, and parts to be united are provided with flanges arranged to abut each other. lflhese flanges are then welded together, but where the flanges meet, a groove or crack is formed, and

this will not properly take a surface finish of porcelain or the like. To overcome this, the metal of the parts is worked with a spreading action to open up the crack or groove and flatten it out, as far as the weld will permit. This minimizes the dimensions of the crack or groove to, such an extent that a finish of porcelain or the like can be satisfactorily applied.

In the accompanying drawing:

Fig. 1 is a perspective view of a sheet of metal fashioned into cylindrical form with the edges welded together.

. Fig. 2 is a cross sectional view of the cylinder with its ends fashioned properly to constitute Fig. 4 is a further enlarged sectional view showing the welded seam.

Fig. 5 is a View enlarged to the size of Fig. 3

illustrating a working operation or spreading operation.

Fig. 6 is a view enlarged to the size of Fig. 4 showing the seam structure after the spreading operation.

Fig. '7 is a diagrammatic view illustrating a finishing operation.

Fig. 8 is anenlarged view showing the surface finish of porcelain or the like.

Fig. 9 is a view similar to Fig. 5 showing a modified arrangement.

The vessel or tub may be fashioned from a sheet of metal such as steel fashioned into cylindrical form with the edges butt welded'together. The cylindrical form is shown in Fig. 1, and the cylindrical form I becomes the side walls of the receptacle. The butt weldat-the edges is suitably trimmed and finished. Due to the fact that sheet stock is rolled into cylindrical form relatively light gauge stock may be used. The cylindrical form may next be subjected to a suitable forming operation to fashion the upper edge in the proper manner, as for example, in the form of an inwardly extending roll 2. The opposite end may be fashioned with an inwardly extending portion or a suitable radius as illustrated at 3, and the extreme end is formed with an outwardly projecting flange I.

The bottom of the receptacle may be a sheet metal stamping 5 which may also be of relatively light gauge stock due to the fact that the stamping is so shallow, and the bottom is provided with a flange 8 arranged to abut against the flange 4 as illustrated. The flanges l and 6 are properly located relative to each other and are to be welded together. Prior to the complete welding operation, however, the flanges may be tacked or temporarily connected by spaced'welds.

- The bottom 5 preferably has its outer mne on a radius to somewhat match the radius 3 of the body. r

The next step in the making of the receptacle is that of welding the flanges 4 and 6, and this may be done by opposed roller electrodes 1 and 8. The receptacle may be revolved on its axis with .the flanges moving between the electrodes to form a continuous fiuid tight weld entirely around the vessel. This weld is indicated by the overhatch 9 in the enlarged Fig. 4. However, it

' will be noted that quite a substantial groove or crack is left on the interior of the vessel, as odicated at III. This cannot be properly fill-tuned it is not a sanitary arrangement in a thing such as a tub'for a washing machine.

Accordinglmthe metal is now worked or spread to minimize the dimensions of this groove. This may be done after the manner illustrated in Fig.

5. The apparatus used for this purpose is sub- -ject to variation insofar as this invention is noncerned, but one way of accomplishing this spreading action is to use a roller 05 disposed to engage the metal on the inside of the seam and a roller l6 arranged to engage the metal on the outside and having a groove H for the reception of the flange constituted by the overlapping parts 4 and t.- The flange, however, does notseat in the bottom of the'groove H, with the result that the vessel and the rollers are. more or less in a floating position relative to each other. The rollers l5 and it are urged toward each other with pressure, and a relative rotary motion is caused between the vessel and the rollers.

shell I and the bottom 5 on opposite sides of the seam is worked and spread apart. This spreading; action will continue until the metal spreads to the point where the weld prevents further spreading. In other words, as Fig. 4 is viewed,

the metal portions on opposite sides of the groove are spread outwardly away from each other, and more or less flattened. The weld line in Fig. 4 is indicated at X; by weld lines we mean the innermost portions of the flanges 4 and 6 which are weld united. The spreading continues and the, weld line is caused to shift toward the sides of the receptacleor the metal stock, at which time the weld connection is drawn taut, so to speak,

and further spreading stopped. As a result, the 40 inner surfaces of the sheet I and sheet 5 come together in a substantially flush manner with the weld connection joining the same and lying substantially atthe line Y in Fig. 6.

Now it may well be, and perhaps will be, that 3 the weld line X will vary in its position. In some spots the weld line may be in the position show'n in Fig. 4, and in other spots on the same job the weld line may be further outward ontowards the ends. of the flanges and in still other spots be further inward toward the groove. Due to the floating arrangement of the spreading rollers, there is a little greater spreading action where the weld line is positioned more toward the outer edge of the flange, resulting perhaps these slight variations are not visible to the eye,

other smoothly with a weld line therebetween. The receptacle may now be finished by finishing the roll at the upper edge or other suitable or desirable finishing operations and the receptacle is ready to be cleaned or pickled and then given I abase coatof porcelain. This is illustrated in Fig. 7 where the material is sprayed on to the shell by a suitable gun 20. As is well known to those versed in the art, the tub may now be baked at a suitable'temperature and subsequently a finish coat of porcelain sprayed-over, the base In this action the metal of both the 25 X the radii that the initial groove is formed. The

- coat and then the vessel subjected to another baking operation. The porcelain-applies evenly over the surfaces and over the smooth weld line X so that in the finished job no weld on the intefior is appreciably visible. In Fig. 8 a more or less diagrammatic illustration is given showing the finished job with the porcelain coating 2!. Y

' A variation in the spreading step is illustrated in Fig. 9: The interior roller l 5 may be the same as that shown in Fig. :5, but exterior v rollers 22 and 23 are applied to the flange with pressure. Relative rotation between the roller assembly and the vessel' causes the metal to spread to minimize the dimensions of the crack or groove and result in the structure as shown in Fig. 6.

In the initial fashioning of the flanges on the sheet metal parts, it is desirable to have a considerable radius at the juncture between the sheet metal body and the flange, as this is good practice in sheet metal working, as the metal mightbe ruptured or sheared if an attempt be made to form a sharp bend or break line. It is due to the opposing curved surfaces formed on working and spreading of the metal so reduces the dimensions of the groove that a finish of porcelain or the like may be satisfactorily applied, whereas the finish could not be'satisfactorily applied with a groove of the initial dimensions. Furthermore, the provision of initial relatively long radii .at the flanges is desirable as such a formation lends itself to the spreading action, and in fact facilitates the spreadingprocess. I

In the finished article there is, of course, the

\ projecting exterior flange which may, if desired.

be trimmed to reduce its width, but-which may be concealed in any suitable way, as for example, by the attachment of the legs for the tub, or the projecting flange may be made more or less orna- -mental by merely disposing a head or rubber or the like over it.

It has been ,found expedient to locate the flanges I and 6 at a corner of the vessel. In this way, the adjacent metal takesa direction away from the welding rolls I and 8, as shown in Fig. 3, whereby the weld between the flanges 4 and 6 may be taken well inwardly of the flange toward the body 'of the vessel. However, it is within .the invention to locate the fianges'in parts which are not angularly disposed relative to each other. Furthermore, by placing the flanges at a corner or the like, especially where there is considerable I radius in the ifitimate job, as shown in Fig. 7, the bulging effect which may be produced by the spreading is more or less absorbed in the curvatur and loses any visible'identity. The initial radius given to .the body'of the vessel at 3 and-the initial radius adjacent the 'edgesof the bottom may be somewhat less than that of the Eultimate radius. This is shown in an exa erated manner as will be evidenced by comparison of Figs. 2 and 7.' In the spreading and bulging operation', the radii may be slightly increased and.

the resultant curvature of the adjacent parts of the body and bottom may be substantially the same. The invention is not limited to a porcelain finish, but is applicable to .other finishes a crack or groove is undesirable.

lclaimz 1. The method of making a receptacle which comprises fashioning a sheet metal blank into a tubular body having a circumferentially smooth where wall at least adjacent one end, forming a flange at said end of the body with they flange meeting' the tubular wall of the body on a curve, fashioning a bottom from sheet metal and forming a flange on the peripheral edge of the bottom with the flange meeting the metal in the bottom on a curve, placing the body and the bottom together with the flanges in abutting relationship withthe curved portions defining a groove, welding the interracial surfaces of the flanges together, working the metal of the body and the bottom adjacent the flanges to cause a spreading action substantially until the weld connection is drawn taut to reduce the dimensions of said groove .to such a size asto present a surface for the reception of a finish such as porcelain or the like.

2. The method of making a receptacle which comprises, fashioning a sheet metal blank into a tubular body having a circumferentially smooth wall at least adjacent one end, forming a circum a curve, placing the bottom and the body together with the flanges in abutting relationship, with the curve portions defining a groove, welding the interfacial areas of the flanges together, working the metal at and adjacent the curved portions to cause a spreading action until the weld connection is substantially drawn taut to thereby reduce the dimensions of the groove to such a size as to present a surface for the reception of a finish such as porcelain or the like.

3. The methed of uniting two sheet metal parts in a seam adapted to receive a finish such as porcelain or the like which comprises, forming a flange on the edge of one sheet metal part with the flange joining the body of the parton a curve, forming a flange on the other sheet metal part with the flange joining the body of the part on a curve, placing the flanges together in abutting relationship, welding the interfacial surfaces of the flanges together with the curves defining a groove, working the metal in and adjacent the curves to cause a spreading action substantially until the weld connection is drawn taut to thereby' reduce the dimensions of the groove to such a size as to receive the said finish.

FRED G. WAHL.

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