Metal fusion bonding – Process – Using high frequency vibratory energy
Reexamination Certificate
1997-02-21
2001-04-10
Evans, Geoffrey S. (Department: 1725)
Metal fusion bonding
Process
Using high frequency vibratory energy
C228S180210
Reexamination Certificate
active
06213377
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an ultrasound welding process and an ultrasound welding device, and to a welding connection produced therewith.
In rotating electrical machines, such as starter drive motors for motor vehicles, it is known to insert commutators as connecting elements between rotating coils (armature winding) and the unmoving supply leads for them. To that end, the commutators have laminations insulated from one another that have contact regions, at which the beginning of one coil and the end of another coil of the armature winding are connected in accordance with the anchor wiring chosen. Thus at each contact region, there are two wire ends of the armature winding to be secured. To that end, it is known to secure the wire ends lying one above the other to the contact regions by means of a resistance diffusion welding process. To that end, one welding electrode of a welding device is connected to the commutator, and the other welding electrode is extended from outside to the outer wire end. A flow of electrical current then effects welding of the wire ends to one another and of the lower wire end to the contact region. A disadvantage here is that the wire ends require special preparation to enable them to be used for the resistance diffusion welding. As a rule, the wire ends are tin-plated for that purpose. Another disadvantage is that each lamination has to be electrically contacted individually, making it relatively time-consuming to secure all the wire ends to the commutator.
SUMMARY OF THE INVENTION
Accordingly, in accordance with the present invention all wire ends to be secured to at least one contact region are pressed against the contact region by means of the contact pressure force, and at the same time the sonotrode sets the lower wire end into oscillations transversely to the contact pressure force, and simultaneously the sonotrode sets the wire ends in oscillation transversely to the axial direction.
When the ultrasound welding process is performed in accordance with the present invention it offer the advantage over the prior art that all the wire ends can be secured simultaneously to the contact regions assigned to them, so that in the case of commutators, for instance, all the laminations of the commutator can preferably be electrically contacted simultaneously. Because the wire ends to be secured are pressed against the contact regions by means of a device that exerts a contact pressure force, and the sonotrode simultaneously causes the lower wire ends to oscillate transversely to the contact pressure direction, an excellent firmly-adhering welding connection can be established between the wire ends and the contact regions. All the welding connections are preferably produced in one operation: All the wire ends are simultaneously pressed against the contact regions each assigned to them, and the sonotrode simultaneously sets all the lower wire ends to oscillating. In a known manner, the oscillation of the lower wire ends leads to the exchange of lattice structures, thus producing a firm welding connection at the points where the wire ends lying one above the other and the lower wire end and the contact region touch. Because as a rule the wire ends are rounded, the touch points are relatively small, so that only a relatively small energy input via the sonotrode is necessary. Hence the sonotrode need be designed for merely a relatively small amplitude range of mechanical ultrasonic oscillation that is transmitted to the lower wire ends.
In an advantageous embodiment of the invention, the sonotrode is embodied as a torsion sonotrode, which advantageously has at least a number of receiving regions that corresponds to the number of wire ends to be secured simultaneously. With its receiving regions, the sonotrode can engage the lower wire ends positively, so that by means of torsional oscillation of the sonotrode, the lower wire ends can at the same time be set to oscillating. Because the sonotrode is designed as a torsion sonotrode, the total free space required for the torsion sonotrode is also relatively small, which allows a simultaneous engagement of all the lower wire ends. Because of the design of the torsion sonotrode, the ultrasound welding process can be incorporated in a simple way into production, for instance into a mounting cycle line for producing commutators for electrical machines or motors. Because of the simultaneous securing of all the wire ends, only a relatively short mounting time is needed to secure the wire ends, so that a short total cycle time can be adhered to.
It is also advantageous if the device for introducing a contact pressure force has radially shiftable clamping members that guide or grasp the outer wire ends and that are preferably pneumatically or hydraulically actuatable. Bringing the sonotrode to the lower wire ends can thus be coupled with the device for imposing the contact pressure force, so that overall a very compact ultrasound welding device that requires little free space is created. A substantially uniform introduction of force to all the wire ends to be secured can be achieved with the radially shiftable clamping members, which are preferably formed by clamping jaws of a clamping tube. By means of the clamping members, self-adjustment of the entire ultrasound welding device is simultaneously performed, thereby assuring that the sonotrode with its receiving regions can detect the lower wire ends exactly. To that end, the receiving regions may be embodied as sonotrode recesses that have an inlet phase, so that once again a self-adjusted positioning of the sonotrode is possible.
Further advantageous features of the invention will becomes apparent from the other characteristics recited in the dependent claims.
REFERENCES:
patent: 4369910 (1983-01-01), Hamano et al.
patent: 4758293 (1988-07-01), Samida
patent: 5198056 (1993-03-01), Stockli et al.
patent: 5236543 (1993-08-01), Riedel
patent: 5238170 (1993-08-01), Nuss
patent: 6140732 (2000-10-01), Morimoto et al.
Altpeter Arno
Schwerdtle Martin
Evans Geoffrey S.
Johns Jonathan
Robert & Bosch GmbH
Striker Michael J.
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