Metal deforming – With means to drive tool – Including link-actuated tool support
Patent
1996-11-15
1998-07-28
Jones, David
Metal deforming
With means to drive tool
Including link-actuated tool support
72314, 2924358, 100271, 100280, B21J 918
Patent
active
057849196
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a prebending unit, especially a corner bending unit, for providing a reciprocating movement or a tool holder pivotally joined to a foundation, said tool holder being supported in such a manner as to be displaceable by means of an operating device coupled to a drive device along a predetermined path of movement between a starting position and a work position.
BACKGROUND OF THE INVENTION
Bending units of the above mentioned type are well known in a number of different designs. They are used to prebend a margin flange of one sheet metal panel around the edge of another panel, especially at the corner portions of the panels, with final bending taking place separately to achieve a clinchor welt joining the two panels to each other. Operations of this type are for example common in the auto industry in the manufacture of doors, engine hoods and similar body parts. Conventionally, a bending unit of the type described here is driven by means of an hydraulic cylinder which actuates a pivotally mounted tool holder. Extension and retraction of the piston rod of the hydraulic cylinder actuates the tool holder to impart a desired movement to the tool and produce the required force so that the tool can carry out the desired bending operation.
This arrangement makes it possible to achieve a pressing force of about 10,000-12,000N, which is quite sufficient for the purpose. A disadvantage of an hydraulically driven cylinder is that there is always a certain amount of leakage of hydraulic fluid, thus soiling the components and increasing the risk of accidents due to fluid spillage on the floor.
The purpose of the present invention is therefore to achieve a prebending unit of the type described by way of introduction, which is cleaner and which generates the required pressing force by converting distance into force without the above mentioned disadvantages, and which is of simple construction and reliable function. This is achieved according to the invention in a prebending unit of the type described by way of introduction, which is characterized in that the operating device comprises an operating means and parallel links joined to a knee-joint mechanism, which has a link, one end of which is joined to a pivot point located on the tool holder, said pivot point being common to the link and the parallel link, the other end of said link being joined to a first pivot point on a triangle link, that a second pivot point on the triangle link is joined to a pivot point which is fixed in the foundation and which is common to the triangle link and the parallel link, that the operating means is joined to a third pivot point on the triangle link and that the knee-joint mechanism actuated by the operating means can be moved from a bent-out position where the tool holder is in its starting position, to a completely extended position where the tool holder is in its work position and then be returned to the bent-out position.
Advantageous embodiments of the device according to the invention are disclosed in the subclaims.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described in more detail below with reference to the accompanying schematic drawings, which show one embodiment of the invention and in which
FIG. 1 is a sideview or a prebending unit according to the invention shown in its starting position,
FIG. 2 is a sideview corresponding to FIG. 1 but with the prebending unit shown when the tool has just reached the workpiece,
FIG. 3 is a sideview corresponding to FIG. 1 but with the prebending unit shown in a work position,
FIG. 4 is a partially sectioned view of the prebending unit according to FIG. 1 as seen from above.
DETAILED DESCRIPTION OF THE INVENTION
The corner bending unit 2 shown in the drawings is constructed of a foundation 4 which is fixed to a frame (not shown), which supports a counter surface 6 for a workpiece 8 with a margin flange 10, which is to be bent in towards the major portion of the workpiece 8 with the aid of a bending tool 12.
The tool 12 is s
AB Volvo
Jones David
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