Apparatus for mechanical joining

Details Apparatus for mechanical joining Apparatus for mechanical joining

1999-10-15

2001-06-05

Hughes, S. Thomas (Department: 3726)

Metal working

Means to assemble or disassemble

With control means energized in response to activator...

C029S283500, C029S521000

Reexamination Certificate

active

06240627

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATION
This application claims the benefit of priority from German Application No. 198 47 794.5, filed Oct. 16, 1998, the full disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an apparatus for mechanically joining metal sheets, which lie flat one upon the other.
In the case of mechanical joining by means of deformation, small three-dimensional formations are formed on sheet-metal parts, which are to be connected at connecting locations, under the action of tool sets, which each comprise a punch and die, said three-dimensional formations being the joining elements. These joining elements are formed in that, in a joining region, the sheet-metal material of the sheet-metal parts, which lie flat one upon the other, is jointly displaced out of a sheet-metal plane and upset. This is also referred to as clinching.
2. Description of the Background Art
A joining tool which can be used for this purpose is known, for is example, from EP 0 077932 B1. In this document, a joining region is bounded by a press-driven punch and a stationary die. If the punch is moved in the direction of the die the material of the metal sheets is deep-drawn in a cavity of the die. If the die-side metal sheet reaches the base of the cavity, which is formed by an anvil, and if the pressure on the punch is maintained or increased, the base of the press-joined joining section may spread out laterally since the material is upset and the walls which bound the die cavity laterally yield. It is also known, from EP 0 366 987 A1, that, in the case of such a joining tool, the punch has a stop which limits its penetration depth. The penetration-depth limitation, and thus a displacement-limiting means, of the punch ensures that the joining is not subjected to excessive stressing. However, it has proven disadvantageous that the known displacement-limiting means is fixed and subjects the joining tool to mechanical loading.
SUMMARY OF THE INVENTION
The object of the invention is thus to provide an apparatus for mechanical joining which is equipped with a displacement-limiting means which operates easily and quickly.
This provides an apparatus for mechanical joining which is equipped with a displacement-limiting means, for the driveable tool part, which acts directly on the drive and thus responds particularly quickly. Furthermore, the construction of the joining tool by the switching bolt and the switching linkage is not subjected to loading.
Furthermore, designing the displacement-limiting means with a valve for depth limitation which can be switched from a throughflow position into a blocking position, initiated by a switching bolt which is carried along by the driveable tool part and, upon reaching a selectable penetration depth, moves a catch, via the switching linkage, out of latching engagement, makes it possible for the penetration depths to be set differently. This improves the adaptation to different sheet-metal materials. Although the initiator for activating the displacement-limiting means is the displacement distance covered by the driveable tool part, displacement-distance measurement does not have to be carried out. The depth limitation is initiated by the penetration depths actually present in the case of each joining operation. This thus ensures that the predetermined penetration depth is not exceeded.
The switching linkage can easily be guided on the tool set without obstructing the construction of the latter. In this case, the switching linkage may be guided such that a catch provided on the switching linkage is supported on the tool set with spring prestressing. This can achieve the situation where the switching linkage being carried along by the switching bolt, this carry-along operation leading to the catch being moved away from the closing element of the valve for depth limitation in order to achieve disengagement, results in the spring prestressing being enhanced. Independent return of the catch into latching engagement following completion of the joining operation is made easier by this increased spring prestressing.
The catch is preferably designed as a pin-like latching element which can engage in a latching means via a rectilinear stroke movement in that it protrudes in a movement direction of the closing element. Even just a small stroke then causes latching engagement and disengagement.
The fluid supply is preferably equipped with a valve-control circuit which, in addition to the valve for depth limitation, has at least one start valve as a pilot valve, which can be actuated by means of a control lever in order to initiate a joining operation.
Furthermore, the fluid supply can be used for subjecting the driveable tool part to the action of a pressure-exerting force for prestressing the driveable tool part against the metal sheets at the beginning of the joining operation as well as for subjecting the driveable tool part to the action of a stripping force for stripping the metal sheets from the driveable tool part at the end of the joining operation. The respective drive means of the usually pneumatically or hydraulically operated tool set is thus used for driving a plurality of functional elements of the tool set, it being possible for a control sequence to be controlled by valves.
Further configurations of the invention can be gathered from the dependent claims and from the following description.
The invention is explained in more detail hereinbelow with reference to the exemplary embodiment illustrated in the attached drawings, in which:


REFERENCES:
patent: Re. 31535 (1984-03-01), Schleicher
patent: 3948427 (1976-04-01), Chaydon et al.
patent: 4569111 (1986-02-01), Mutou
patent: 5267383 (1993-12-01), Sawdon
patent: 5528815 (1996-06-01), Webb
patent: 5829299 (1998-11-01), Wessels
patent: 0 077 932 (1984-12-01), None
patent: 0 366 987 (1989-10-01), None

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