Electricity: magnetically operated switches – magnets – and electr – Magnets and electromagnets – Work or object holding type
Reexamination Certificate
1999-07-07
2001-08-21
Barrera, Ramon M. (Department: 2832)
Electricity: magnetically operated switches, magnets, and electr
Magnets and electromagnets
Work or object holding type
C335S290000, C335S295000, C269S008000
Reexamination Certificate
active
06278350
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a holder device for workpieces in the form of metal sheets of magnetically attractable material whose edges are to be welded along a connecting path, comprising a magnetically activatable and de-activatable support face means for supporting the workpieces which are to be welded together.
PRIOR ART
In the automotive industry for example comparatively large pieces of sheet metal are required, which are converted in presses into the respective automobile parts. More particularly they are to have regions with different thicknesses for adaptation to loads occurring in the finished automobile part, such sheets are made up of individual smaller metal sheets, which are joined together at the edges by welding. Conventional thicknesses of sheet metal employed here are in a range of approximately 0.5 to 2.5 mm.
For this purpose in addition to mechanical clamps, with the aid of which the individual pieces of sheet metal are held in the positions for welding, it is a known practice to lay the various sheets on a magnetically activatable support face means while same is not magnetically activated, which after positioning of all sheets is magnetically activated so that the sheets are held on the support face means by magnetic force. After this the sheets are then welded together more especially by laser welding along the respective connecting path.
In such operations there is always a possibility of the first sheet, which has been placed on the support, being knocked aside by the next sheet to be put in place out of the intended setting so that the first sheet must be aligned again. This danger becomes even more serious because the individual sheets must be as close together as possible in order to prevent the formation of a gap which is to be avoided for the welding operation.
SHORT SUMMARY OF THE INVENTION
Accordingly one object of the present invention is to provide a holding device of the initially described type with which positioning of the individual metal sheets in relation to one another is facilitated.
In order to achieve these and/or other objects appearing from the present specification, claims and drawings, in the present invention the support face means is divided up into a plurality of face means fractions which are each constituted by a separate pole plate of magnetizable material, each pole plate having associated with it only an activatable and de-activatable magnet means, which is located underneath the pole plate on a support plate arrangement.
Using the holding device of the invention the following operation becomes possible:
On placing the first sheet in position all magnet means are still inactive. Once the first sheet has been placed in the correct position, those magnet means are activated, which are associated with the pole plates completely covered by the first plate. The first sheet is then held firmly in position owing to the magnetic force exerted on it. After this the next sheet is placed on top, may be thrust at the connecting path against the edge of the first sheet, which, which is already held fast and can not be dislodged. Then the magnet means underneath the second sheet and underneath the connecting path are activated. If further individual sheet are present, same may then be added in the same fashion.
Accordingly it is possible for the individual sheets to be rapidly and truly positioned.
It is convenient for the pole plates to be detachably connected with the support plate arrangement. This involves the following advantage:
In the support face means it is necessary for a groove to be provided extending along the respective connecting path so that the sheet edges to be welded together are exposed in a downward direction. Without such a groove there would be a danger of the two sheets not only being welded to one another but also to the support face means.
It may also be necessary for other recesses to be provided in the support face means, as for example in connection with the putting in place and removal of the workpieces.
If, as in the case of this type known system, of a continuous single-piece support face means, same must consequently be replaced completely on re-tooling the holding device, when sheets are to be welded together having different peripheral shapes so that the at least one groove present so far and the any other recesses present disappear and a number, equal to the number of new sheets, of grooves and possibly recesses must be produced. In comparison the holding device of the invention it is sufficient to replace only the pole plates having the grooves and possibly other recesses. All other pole sheets may continue to be utilized..
Further advantageous developments and convenient forms of the invention will be understood from the following detailed descriptive disclosure of one embodiment thereof in conjunction with the accompanying drawings.
REFERENCES:
patent: 137875 (1873-05-01), Jaques et al.
patent: 2561769 (1951-07-01), Anderson
patent: 3829805 (1974-08-01), Spodig
patent: 4023267 (1977-05-01), Pignataro
patent: 4777463 (1988-10-01), Cory et al.
patent: 959977 (1957-03-01), None
patent: 268418 (1989-05-01), None
patent: 4026156 (1991-05-01), None
patent: 19617179 (1996-11-01), None
patent: 19548618 (1997-08-01), None
Barrera Ramon M.
Browdy and Neimark
Schuler Automation GmbH & Co. KG
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