US2829545A

US2829545A - Method of and apparatus for deforming sheet metal

Info

Publication number: US2829545A
Application number: US343302A
Authority: US
Inventors: Eckold Walter
Original assignee: Individual
Current assignee: Individual
Priority date: 1952-03-29
Filing date: 1953-03-19
Publication date: 1958-04-08
Anticipated expiration: 1975-04-08

Description

April s, 1958 w. ECKOLD 2,829,545

METHOD OF AND APPARATUS FOR DEFORM'ING SHEET METAL Filed March 19, 1953 2 Sheets-Sheet 1 Inveman' Wczzz'er Ec rozcz April 8, 1958 v w. ECKOLD 2,829,545

METHOD OF AND APPARATUS FOR DEFORMING SHEET METAL Filed March 19, 1953 2 Sheets-Sheet 2 Wa 2661 EM 02oz finished sheet metal articles.

United States Patent METHOD or AND APPARATUS FOR DEFORMING SHEET METAL Walter Eckold, St. Andreasberg, Sperrluttertal, Oberharz, Germany This invention relates to a method of and an apparatus for working out or re-forming plastic deformations in sheet metal.

Both manual and mechanical methods of deforming sheet metal are known. In manual deformation, chasing hammers have hitherto been generally employed, the principle of which has also been applied to mechanical deformation. Apart from its uneconomical nature, this primitive method is attended by noise which renders all communication between the works personnel extremely difiicult, particularly when a mechanical chasing hammer is employed.

In a further known method of producing deformations in sheet metal by hand, the metal sheets are driven into a block havinga hemispherical cavity by means of large wooden or rubber hammers. In the corresponding mechanical method, the sheet is driven by means of apunch having a hemispherical or spherical contact surface, in any desired number of working operations, into a die fashioned hemispherically to correspond with the form of a punch. Such tools, which consist mainly of wood, require a large mounting to accommodate varying diameters and are in addition subject to considerable wear. Moreover, the finished articles require additional finishing work, thus in many cases increasing the cost of the process.

Based on this experience, specially fashioned tools have already been developed which deform the material by drawing or swaging, but the application thereof has been limited to the deformation of the edge zones of semi- Here again, exceptionally high installation costs are involved in cases where the deforming work is carried out with the aid of presses or rolls.

The object of the invention is to make mechanical sheet-metal deformation more universally applicable by According to the invention, this is rendered possible by causing hollow punches having a strip-shaped contact surface and an external configuration adapted to the forms in question to act on the sheet-metal parts to be deformed, the said hollow punches producing a flow of the material in that part of the surface which is encompassed by the hollow punch in each case and thus gradually working out the desired forms, or smoothing out undesirable deformations, in a succession of working operations, the sheet metal being systematically guided.

The deformation produced by the hollow punch in each case is preferably assisted by a correspondingly shaped counter-punch, which may be constructed as a fixed or oppositely movable abutment.

The hollow punch for carrying out the described process of deformation may itself be rigid throughout or so constructed that its contact surface yields resiliently, resulting in a tendency of that part of the surface of the sheet metal which is encompassed by the hollow punch to contract or expand, depending on the direction of the springing action.

As examples of the invention several hollow punches will now be described in greater detail with reference to the accompanying drawings of which:

Figures 1 and 2 show hollow punches of frusto-conical form,

Figures 3 and 4 show modified punches with means for increasing the deformation,

Figures 5 and 6 show hollow punches capable of eifecting both swaging and drawing,

Figures 7 and 8 show further different punches,

Figures 9 and 10 show punches of differing profiles and Figures 11 and 12 show details of a complete punch assembly.

The hollow punches 1 and 2 illustrated in Figs. 1 and 2 are of frusto-conical form. Theannular contact surfaces 3 of the punch 1 shown in Fig. 1 contract inwardly somewhat under the pressure of the punch, While in the case of the punch 2 shown in Fig. 2 they expand outwardly. Due to this movement the fiow of the material within that part of the surface of the sheet metal which is encompassed by the hollow punch will be assisted by a swaging action in Fig. l and a drawing action in Fig. 2.

This slight deflection of the hollow punches is increased in the forms shown in Figs. 3 and 4 due to the formation of slots 6 in the jackets of the swaging tool 4 and of the drawing tool 5, whereby a greater deflection of the tools results from the same load.

Figs. 5 and 6 show two constructions of hollow punches by which a combined swaging and drawing action is produced. In the hollow punch 7 shown in Fig. 5, the outer contact surface 8 effects the swaging while the inner contact surface 9 effects the drawing. Conversely, in the hollow punch 10 shown in Fig. 6, the outer contact surface 11 effects a drawing and the inner contact surface 12 a swaging. Both actions are increased by slots 13.

In the forms shown in Figs. 7 and 8, the hollow punch consists of a slotted ring which is constricted or widened out by a form of guiding in the mounting. in the form shown in Fig. 7, the widening is effected .by thin steel plates 15 fitted at an incline, while in the form shown in Fig. 8 the constriction is effected by the conical surfaces 16, which become effective under bearing pressure.

In Figs. 9 and 10, two constructional forms having a number of profiles are illustrated, the profiles Ibeing ovalin the punch 17 shown in Fig. 9 and extending in concentric circles in the punch 18 shown in Fig. 10. In contrast to the punch constructions hereinbefore described, the profiles here are rigid, so that the flow of material is initiated only by the pressure of the contact surface of the profiles on the sheet-metal articles.

'In the example shown in Figures 11 and 12., the annular contact surfact of the hollow punch is subdivided into twelve segments 21, each of which is mounted on one or more thin steel plates or laminations 22. The steel plates here bear in recesses 23 in the lower side of each segment 21 and in the upper side of an inserted ring 24, which is fitted by means of an extension 25 in the recess 26 in the supporting member 27.

The steel plates 22, which are in this case inwardly inclined for a swaging operation are embedded over their free length in a resilient mass 28 which, on removal of a vertically acting working pressure from the segments 21, returns the plates to their inclined initial position.

In order in this case to utilise the resiliency fully for the return of the steel plates, that is to say, to prevent them from yielding outwardly and inwardly, the resilient mass is encircled or internally supported by retaining rings 29. Finally, the sleeve 30 is pushed on to the tool.

In order to centre the ring of segments 21, a centering member 31 is also fitted in countersunk fashion, the centering member overlapping, and thus holding fast, by means of a projecting edge 32 an inner stepped portion 33 on the segments 21. Suflicient lateral clearance for the inwardly directed working movement of the segments 21 is left, which is filled by a rubber packing 34 which at the same time assists in the return of thesegments into their initial position.

Finally, narrow rubber strips 35 are disposed between the individual segments 21 in order to protect the interior of the tool against the ingress of dirt and moisture. Owing to the fact that the centering member is detachably fitted by means of a screw 36, the interchanging of the punch parts is made easier.

The invention is not limited to the embodiments described and illustrated by way of example. These are merely intended to show the underlying idea of the invention, residing in the subdivision of the more or less closed contact surface of the hollow punch into individual segments which carry out their working movements independently of one another and combine to produce the flow of the material in that part of the surface which is encompassed by the hollow punch.

The described hollow punches may work on smooth or profiled anvil surfaces or may co-operate with identically fashioned counter-punches, whereby the distortion is further assisted.

It is specifically to be noted that the construction of the hollow punches is not in any way limited and that the form thereof must be adapted to the particular deforming work to be performed. The only factor always essential to the method according to the invention resides in that the hollow punch, regardless of whether it is rigid, elastic or provided with guide means, encompasses throughout the deforming operation a part of the surface of the sheet metal article, within which a flow or displacement of the material is set up by the pressure alone or with the assistance of movements of the hollow punch itself resulting in a gradual working-out or smoothing out of plastic deformations.

What I claim is:

1. A tool for changing the dimensions of sheet metal along its planar extent comprising a shank, and an integral hollow cup-shaped punch composed of inner and outer trusts-conical continuous walls, said frusto-conical punch having one of its bases secured to said shank, and the other of its bases forming a continuous annular edge for engagement with a sheet of metal, the slant height of said frusto-conical punch and the thickness between the walls thereof being such that said continuous edge when forced against a sheet of metal will deform and change the planar dimension of the sheet of metal.

2. A tool according to claim 1, in which the annular edge constitutes the larger of said' bases to create a stretching action on thesheet of metal.

3. The tool according to claim 1, in which said annular edge constitutes the smallest of said bases to create a compressive action 011 the sheet of metal.

References Cited in the file of this patent UNITED STATES PATENTS 468,613 Frist Feb. 9, 1892 633,316 Heinz Sept. 19, 1899 1,012,992 Davis Dec. 26, 1911 2,010,996 Junkers Aug. 13, 1935 2,060,675 Kirchner Nov. 10, 1.936 2,407,573 .Nelson Sept. 10, 1946 2,428,173 Moore Sept. 30, 1947 2,649,820 Hunt Aug. 25, 1953