Metal fusion bonding – Means to apply vibratory solid-state bonding energy to work
Reexamination Certificate
1998-12-22
2001-01-16
Ryan, Patrick (Department: 1725)
Metal fusion bonding
Means to apply vibratory solid-state bonding energy to work
C228S110100, C228S111000
Reexamination Certificate
active
06173878
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a device for connecting metallic materials, in particular electrical conductors such as flexible cables, by means of ultrasound with a transducer which generates ultrasonic oscillations of a wavelength lambda and containing a sonotrode with a sonotrode head, as well as a converter, wherein the transducer is seated at a distance of at least lambda/4 in respect to the sonotrode head.
Conventional transducers for generating ultrasonic oscillations comprise a converter for converting electric oscillations into ultrasonic oscillations of a desired frequency and amplitude, a booster, as well as a sonotrode with a sonotrode head having an electrode, or respectively a work surface, wherein the contact with the materials to be welded takes place for welding metal elements, such as flexible cables. Since the welding surface, or respectively the welding point, extends parallel in respect to the sonotrode oscillation axis, the seating must not only absorb axial and radial forces, but also bending moments.
In this connection it is known to seat a transducer, comprising a converter, a booster and a sonotrode, in oscillation nodes extending in the booster as well as in the sonotrode. This in turn means a long structure of the transducer.
With a booster-less embodiment of a transducer, which therefore only contains a converter and a sonotrode, a partition can be formed between the converter and the sonotrode, in which a diaphragm spring is clamped, by means of which the transducer is seated. Moreover, a support in the oscillation node (
FIG. 9
) extending in the sonotrode is provided. In this case the diaphragm spring extends in the oscillation maximum. Not only is a radially large structure necessary because of the use of the diaphragm spring, but also an axially flexible seating. In connection with a further booster-less oscillation embodiment, seating is provided in the oscillation neutral point in the converter, as well as support in the oscillation zero point of the sonotrode (FIG.
10
). It has been found here that the zero point seating in the converter leads to considerable problems.
In connection with a further known transducer, which includes a converter, booster and sonotrode, the booster and the sonotrode are respectively seated, or respectively supported, in the oscillation zero point (FIG.
7
). The use of the booster results in a long structure. Moreover, transducers are known having partitions between the converter and the booster on the one hand, and the booster and the sonotrode on the other hand, from which diaphragm spring extend (FIG.
8
). Since seating takes place in the oscillation maximum, the transducer is very flexibly supported. In addition, a large radial structure results because of the diaphragm spring used.
A device of the type known at the outset is known from DE 35 08 122 C2. Here, the sonotrode is supported by a plurality of locking screws, which are aligned perpendicularly in relation to the longitudinal axis of the sonotrode, which themselves do not absorb the occurring axial and radial forces, as well as bending moments, to the required degree. It is therefore necessary to additionally support the converter or booster. In actual use this takes place in the booster.
SUMMARY OF THE INVENTION
The present invention is based on the problem of further developing a device of the type mentioned at the outset in such a way that, along with a short construction, the appearing axial and radial forces, as well as the bending moments, are absorbed to the extent necessary. However, sufficient rigidity should also be provided in order to compensate static forces.
In accordance with the invention, the problem is essentially solved in that the transducer is exclusively supported at a distance of lambda/4 in respect to the sonotrode head by means of a seating for absorbing radial and axial as well as bending moments and torsion moments.
By means of the teaching of the invention there is the possibility of making available a booster-less and therefore compact transducer having a single seating which extends in the area of the sonotrode, namely in the first oscillation node from the direction of the sonotrode head.
By means of the teaching of the invention, a transducer is made available for the first time for welding metal elements together, which has a single seating, which is a possibility which up to now was only available in connection with plastic welding, namely in the oscillation zero point of a booster which, however, causes a long structure of the transducer, since the seating point is 3·lambda/4 away from the sonotrode head. Furthermore, the seating need not absorb any bending moments, since in plastic welding the oscillation axis of the sonotrode extends perpendicularly in relation to the surfaces to be welded. For this reason, transducers intended for metal welding were always seated in two areas.
In accordance with a preferred embodiment of the invention it is provided that the seating has a first section which radially projects from the sonotrode and which makes a transition into a second section, which extends in the longitudinal direction of the transducer and is spaced apart from the latter. The transducer itself is then fixed in place by means of the second section and at a distance from the first section, because of which an elastic uncoupling takes place from the occurring transverse forces, or respectively transverse stretching, which occur in the oscillation node because of stretching, or respectively compression, of the sonotrode. In particular, the first section is a circumferential ring, or respectively a circumferential disk, and the second section is a hollow cylinder, which can be designed as one piece or as separate elements, which are then connected with each other, for example screwed together.
The first section can be embodied integrally with the sonotrode. But alternatively there is also the possibility of designing the sonotrode in several pieces, and to clamp the first section into a partition extending at a distance lambda/4 from the sonotrode head, from which section the second section for elastic coupling starts, which extends along the transducer. Because of the embodiment of the sonotrode in several pieces there is the advantage, that worn elements can be exchanged without problems, without the entire sonotrode needing to be replaced. The individual sonotrode elements can be screwed together.
In accordance with an alternative solution suggestion it is provided that the sonotrode has a partition, which divides it into two axial sections and from which a radially extending disk-shaped element starts, which itself is fixed in place in areas extending diametrically in relation to the sonotrode. In this case the areas themselves are clamped between cheeks which preferably are made of plastic, so that the transverse forces, or respectively transverse stretching, occurring because of the stretching and compression of the sonotrode, can be absorbed. In particular, each area extends in an oscillation node of the disk-shaped element.
REFERENCES:
patent: 4646957 (1987-03-01), Nuss
patent: 4867370 (1989-09-01), Welter et al.
patent: 4869419 (1989-09-01), Nuss
patent: 5192015 (1993-03-01), Ingle et al.
patent: 5323952 (1994-06-01), Kato et al.
patent: 5360155 (1994-11-01), Ooki et al.
patent: 5771100 (1998-06-01), Patrikios
Dennison, Scheiner Schultz & Wakeman
Elve M. Alexandra
Ryan Patrick
Schunk Ultraschalltechnik GmbH
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