Metal deforming – By use of non-deforming work-gripping clamp and relatively... – Clamp structure constitutes sole initial metal-deforming...
Patent
1992-04-07
1993-08-31
Crane, Daniel C.
Metal deforming
By use of non-deforming work-gripping clamp and relatively...
Clamp structure constitutes sole initial metal-deforming...
72 7, B21D 504
Patent
active
052398536
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a device for bending a metal sheet.
During the bending of sheet metal with conventional swivel bending machines, the bending jaw (and possibly also the lower jaw) have to be suitably adjusted in dependence upon the thickness of the respective metal sheet to be bent, which involves considerable apparatus and time expenditure. Furthermore, in the known bending process, the bending jaw slides along the sheet metal section to be bent during the bending operation, which results in undesired sliding friction and strain on the surface of the metal sheet.
In general, known swivel bending machines are adjusted prior to the bending such that the swivel axis of a bending jaw which is swivelled from the bottom upwards lies at a spacing above the upper or bending surface of the bending jaw which corresponds to approximately 1.5 times the thickness of the sheet metal. This spacing must be specified in advance to avoid undesired compression of the sheet metal during the swivel movement of the bending jaw. A further disadvantage of the known bending process is that ugly, irregularly rounded bending contours which, in particular, deviate from the circular shape often occur.
A device is known from U.S. patent application No. 4 557 132. In this known device, the swivel axis of the bending jaw is slidable in a relatively short, arcuate slot so that an edge of the bending jaw essentially always engages the same place on a sheet metal section to be bent. It is not possible to obtain certain, predetermined bending contours with the known machine. Also the bending jaw thereof has to be preset to the respective thickness of the metal sheet.
The object of the invention is to so improve a generic device that while reducing the slide path between bending jaw and bent sheet metal section, optional and uniform bending contours can be produced and the swivel axis of the bending jaw no longer has to be preset in dependence upon the thickness of the sheet metal.
The following description of a preferred embodiment serves in conjunction with the appended drawings to explain the invention in further detail. The drawings show:
FIG. 1 schematically the bending of a metal sheet and
FIG. 2 schematically a swivel bending machine.
FIG. 1 shows schematically the lower jaw 1, the upper jaw 2 and the bending jaw 3 of the bending machine known per se and not illustrated in further detail. A metal sheet 4 is clamped between lower jaw 1 and upper jaw 2 and protrudes with a sheet metal section 5 which is to be bent over the front edges of the jaws 1 and 2. The bending jaw 3 is mounted in the machine frame for swivel movement about an axis S which in FIG. 1 extends perpendicularly to the drawing plane.
In the embodiment of FIG. 1, the swivel axis S extends, as illustrated, within the metal sheet 4. With the conventional swivel bending machine, the metal sheet could not be bent with the swivel axis in such a position because the metal sheet would undergo considerable compression upon execution of the swivel movement of the bending jaw 3. Therefore, heretofore, the swivel axis S was always arranged somewhat outside the metal sheet 4 and above the upper or bending surface 6 of the bending jaw at a spacing which was approximately 1.5 times the thickness of the metal sheet 4.
In order to avoid compression of the sheet metal during the bending and to achieve a uniform, predetermined bending contour of the bent sheet metal section 5, in accordance with the invention the bending jaw 3 is adjusted during its swivel movement in dependence upon the bending angle which is passed through in a first direction of adjustment perpendicular to the swivel axis S and to its bending surface 6. This adjustment is indicated by the respective arrows A.sub.1 to A.sub.4 in FIG. 1.
Prior to commencement of the bending operation, the bending jaw 3 assumes the position corresponding to arrow A.sub.1. In a first phase of the bending operation, the bending jaw 3 is swivelled into the position corresponding to arrow A.sub.2 and simultaneously pushed back relativ
REFERENCES:
patent: 2782832 (1957-02-01), Shaw
patent: 4493200 (1985-01-01), Rhoades
patent: 4557132 (1985-12-01), Break
patent: 4768367 (1988-09-01), Favrin
Crane Daniel C.
Reinhardt Maschinenbau GmbH
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