Metal deforming – By use of non-deforming work-gripping clamp and relatively... – Plural or complex apparatus
Patent
1996-07-29
1998-04-21
Crane, Daniel C.
Metal deforming
By use of non-deforming work-gripping clamp and relatively...
Plural or complex apparatus
72315, 72323, 2924358, B21D 3902
Patent
active
057406910
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/GB95/00289, filed Feb. 13, 1995.
This invention relates to hemming sheet metal and more particularly to a method and apparatus for forming a hem on an edge of an opening in a sheet of a fabricated sheet metal member such as a vehicle body panel.
BACKGROUND TO THE INVENTION
Door, hood and trunk deck lids of vehicles have been formed of one unitary outer skin of sheet metal joined around its periphery to a second inner reinforcing panel of sheet metal by hemming a generally upturned flange along each edge of the outer sheet over an adjacent edge of the inner panel.
Historically this hemming has been accomplished in two separate stages. Prior to performing the first stage, the reinforcing panel is nested within the outer panel fixtured on an anvil die on a base of a prehemming machine. Upon fixturing the assembly, a tool of the machine,.commonly referred to as a hemming steel, engages and bends an edge of the outer panel to an acute included angle with respect to the outer panel. After the prehemming of all edges to be joined, both panels are released, transferred to and fixtured in a second hemming machine where a second tool completely bends the prehemmed edge of the outer panel over the peripheral edge of the reinforcing panel to secure and attach the panels together as a unitary structural member for assembly on a vehicle.
Typically, a plurality of both prehemming and final hemming machines are respectively grouped around the periphery of a panel to perform all prehemming and hemming operations for one assembly either sequentially or substantially simultaneously.
More recently, hemming machines have been designed which perform both the prehem and final hem operation in a single machine tool station. Hemming machines of this type vary in the kind of mechanism used and the manner of carrying out the hemming operations. Representative of these hemming machines are US Patents: Kollar et al U.S. Pat. No. 3,191,414; E R St. Denis U.S. Pat. No. 3,276,409; Dacey Jr U.S. Pat. No. 4,706,489 and Dacey Jr U.S. Pat. No. 5,083,355.
Hitherto hemming machines have been used for hemming on external edges. Internal edges have either not been hemmed or have been hemmed on separate machines.
A press for prehemming and final hemming a sheet received on an anvil with separate prehemming and final hemming tools or steels has been proposed in which each of the tools or steels is driven through linkage powered by the same prime mover, such as a cylinder or a screw and servo motor. Each steel is mounted on a separate carrier or subframe pivotally mounted by links in a main frame and each driven through separate toggle joints to produce the force for bending the sheet by the steels. Preferably, to provide a more compact structure the pre-hem carrier is also eccentrically as well as pivotally mounted on the main frame. Preferably, the toggle joints are connected through rocker arms to the prime mover and the linkage provides a dwell in the movement of the prehemming steel so that it does not interfere with movement of the final hemming steel.
SUMMARY OF THE INVENTION
According to one aspect of the present invention there is provided a press for prehemming and final hemming the internal upturned lip of an aperture in a sheet metal component comprising an anvil on which the sheet metal component is held down so that the upturned lip to be hemmed is substantially in alignment with an edge of an opening in the anvil, and a composite hemming tool carried by a tool carrier and adapted to perform prehemming and final hemming steps, characterised by a single drive means which protrudes up from the press through the opening in the anvil so that a lower inclined leading edge of the tool substantially registers with the upturned lip to be hemmed, said single drive means being so operable as to firstly force the tool towards and into engagement with the lip so as to bend the lip over until it is bent through substantially 90.degree. from its upturned position, and thereafter to move the tool in a generally
REFERENCES:
patent: 3092057 (1963-06-01), Warshilek
patent: 3147726 (1964-09-01), Tribe
patent: 3466661 (1969-09-01), Phillips
patent: 3598073 (1971-08-01), Denis
patent: 4346579 (1982-08-01), Takatsu
patent: 4706489 (1987-11-01), Dacey
patent: 5038597 (1991-08-01), Dorsett
patent: 5086638 (1992-02-01), David
Kovarovic Josef
Kowalewsky John Ralph
Sloat Gerrit Wesley
Crane Daniel C.
Western Atlas U.K. Limited
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