US1167556A - Method of forming sheet metal. - Google Patents

Description

0. 1. GRUEHN. METHOD 0F FORMING SHEET METAL. APPLlcATxoN mio lune' 1|, 19.14.

il, Patented. Jan. 11, 1916.

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OTTO J. GROEHN, OF'DETROIT, MICHIGAN, SSIGNOR TO BRISCOE MANUFACTURING COMPANY, OF DETROIT, MICHIGAN, A CORPORATION 0F MICHIGAN.

METHOD OF FORMING SHEET METAL.

Specification of Letters Patent.

Patenten aan. it, raie.

Application led June 11, 1914. l Sera11\To. 844,447."

To all whom it may) concern.'

Be itknownthat I, OTTO J. GROEHN, a citizen of the United States of America, residing at Detroit, in the county of Wayne and State of Michigan, have invented certain new and useful Improvements in Methods of Forming Sheet Metal, of which the following is a specification, referenceV being had therein to the accompanyingl drawings.

The invention relates to the manufacture In the present state' of the art automobile fenders are commonly formed from sheet metal which is curved in one plane only and may therefore be readily formed from a flat blank withoutv drawing or flowing of the metal. There is, however, a demand for fenders which are concavo-convex in cross section, as well as being curved longitudinally in conformity to the wheel but such constructions cannot be made by the process commonly used. It is possible to produce such form by suitable drawing dies, but this requires heavy and expensive machinery, and on account of the large number of sizes and variations and frequent change inV shape, such a process is not a commercial success. The present invention overcomes these diliculties by the formation of the desired shapes by a rolling or .progressive treatment of lthe blank; and further, by a method of holding the blank during the rolling or forming action so as to prevent buckling or deformation of any part thereof.

The invention further comprises the supplementing of the progressive forming step `by die operations for completing the article in certam portions thereof.

nal section showing themanner of rolling and forming sheet metal; Fig. 2 is a cross section through a machine 1n which the metal is rolled; Fig. 3 is a section showing the manner of die-fashioning portions of the blank; Fig. 4 is a view similar to Fig. TL-showing ,a modified construction; Fig. 5

` 1s a cross section through the blank before .the following operation; and Fig. 6 is a j plan view of the blank.

In forming-of larticles from. flat sheet metal vblanks so as to produce warped or transversely-curved surfaces, it is essential to draw or elongate certain portions of the blank, or to contract or-upset other portions.

With relatively light gage sheet metal `it is difficult to avoid the wrinkling of the portions of the blank which are subjected to compression stresses, and also to prevent distorting of the blank by the drawing stresses. To take a specific instance, a wheel fender which is curved longitudinally. substantially concentric with the wheel and 4transversely to lhave'- a convex cross section,

the longitudinal center of the blank mustl be drawn or expanded while the marginal -portions will be subjected to compression stresses. Furthermore, the drawing of the central portion, which should be in a longitudinal direction, will react transversely of the blank to produce a distortion thereof.

To avoid the result just described, I provide in my improved process, means for holding the marginal portions of the blank in such a manner that they are prevented on the one hand from wrinklingby any upsetting stresses, and o n the other hand are held from displacement laterally of the .blank under any drawing stress applied to the central -portion thereof. Various specific means may be employed for obtaining this result, but preferably that shown in Figs. l to 3, in which A is the blank and B B are hooked flanges bent from the opposite ed e portions. These flanges B B are forme primarily forobtaining a retaining engagement with the guides during the drawing operation, but they also perform a function in the fashioned article as a means of attachment to the depending vertical flanges of the fender.

The flat blank being first formed with these reversely-bent edges, as shown in Fig. 3, is

then passed through a drawing machine coml In the drawings: Figure 1 is a longitudiriod of engagement with these rolls, as well as for a certain distance before and after engagement, the hooks B and B are engaged with marginal retaining guides E and E. These are so fashioned as to receive the hooks of the blank and to hold the adjacent portion between parallel contacting surfaces. This will prevent the drawing of the blank inward and will also prevent the buckling of the margin portions under the influence of the bulging portion of the roll. The portion of each of the guides E and E beyond the rolls extends at an angle to the original plane and is preferably curved to correspond to the longitudinal contour to be imparted to the product. It is not, however, necessary that the contour of the guide should exactly conform to the contour of the nished product, as the angleat the point of longitudinal bending is the controlling factor, and thus with the same guide variations in the curve may `be produced by an angular adjustment with respect to the original plane of the blank.

To facilitate the feeding of the blanks between the rolls C and D, a central tongue F is formed at the entrance end, which may be more readily deflected downward into engagement with the convex portion of the roll, and when thus engaged will draw the whole blank into engagement. The opposite end of the blank may be correspondingly recessed at G, to permit the tongue of a following blank to engage therewith, and the following blank will thus propel the advance blank until disengaged from the rolls and guides. Where the bulging contour is comparatively flat, it is preferably held from distortion by a shoe H arranged adjacent to 'the delivery side of the rolls C and D. To complete the article, it is necessary tov form the end portions thereof, and this is preferably accomplished by pressing between dies, such as I and I', shown in Fig. 3. In

place of forming the blank with the hooked ianges at opposite edges, the blank may be attached to marginal guide strips J and J as shown in Fig. 4, and these strips may be held from inward movement by abutting against the ends of the rolls or by any other suitable means.

What I claim asmy invention is 1. The method of fashioning sheet metal blanks to warped or transversely-curved forms, comprising the progressive bulging of the central portion of the blank to stretch the metal longitudinally and transversely, and the holding of the marginal portions of the blank from inward movement during this operation to prevent buckling.l

2. Themethod of fashioning sheet metal blanks to warped or transversely-curved forms, comprising the progressive bulging of the central portion of a sheet metal strip, and ther holding from inward movement and the guiding of the marginal portions of said strip to prevent buckling and to determine the longitudinal contour.

3. The method of fashioning sheet metal blanks to warped or transversely-curved forms, comprising the formation of marginal flanges longitudinally of the fiat sheet metal strip, the bending of said strip to bulge the central portion thereof, and the holding of the marginal portions during said bending movement to prevent drawing toward each other and to hold the same from buckling.

4. The method of fashioning sheet metal .blanks to warped or transverselycurved forms, comprising the forming of a sheet metal strip with hooked flanges upon opposite edges thereof, feeding said strip longitudinally and simultaneously bulging the central portion thereof, the bending of the strip longitudinally during its feeding movement to conform to a predetermined curve,

and the guiding of the hooked flanges at the margin of said strip to prevent movement toward each other and to hold the same from buckling.

In testimony whereof I affix my signature in presence of two witnesses. I OTTO J. GROEHN.

Witnesses:

HARRY LUMPKIN, ARTHUR F. RoHRBACH.

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