DE102011084157B3 - Ultrasonic welding device and method for welding workpieces - Google Patents

Abstract

The ultrasonic welding apparatus (1) has an anvil means (21) for holding a first workpiece (31), a vibration generator (13) for generating mechanical vibrations, a sonotrode (11) mechanically coupled to the vibration generator (13) for transmission the mechanical vibrations on a second workpiece (32), and a holding device (12) for holding the second workpiece (32), on. The holding device (12) is mechanically coupled to the vibration generator (13) such that during operation of the vibration generator (13), the holding device (12) oscillates synchronously with the sonotrode (11).

Description

The present invention relates to an ultrasonic welding apparatus and a method for welding workpieces.

Ultrasonic welding devices are used to weld workpieces by means of ultrasonic vibration. The ultrasonic vibration is generated by a vibration generator and transmitted via a sonotrode to a second workpiece. The second workpiece is in contact with a first workpiece, wherein the first workpiece is prevented from swinging by an anvil. In the area of the contact surface between the first and the second workpiece, due to frictional heat, a strong increase in temperature occurs, which leads to a permanent welded connection of the first and the second workpiece in the region of the contact surface.

In the ultrasonic welding device described above, however, there may be inaccuracies in the relative position of the two welded workpieces.

It is the object of the present invention to provide an ultrasonic welding apparatus and a method for operating the ultrasonic welding apparatus, with which more precise welded joints are made possible.

The object is achieved by an ultrasonic welding device and a method for operating the ultrasonic welding device according to the independent patent claims. Advantageous embodiments of the present invention are the subject of the dependent claims.

An ultrasonic welding apparatus according to claim 1 comprises an anvil means for holding a first workpiece, a vibration generator for generating mechanical vibrations and a sonotrode. The sonotrode is mechanically coupled to the vibration generator for transmitting the mechanical vibrations to a second workpiece. The ultrasonic welding apparatus further comprises a holding device for holding the second workpiece. The holding device is mechanically coupled to the vibration generator such that, during operation of the vibration generator, the holding device oscillates synchronously with the sonotrode.

The mechanical vibrations are preferably ultrasonic vibrations which are generated by the vibration generator. The sonotrode can transmit the vibrations from the vibration generator to the second workpiece and thus cause the second workpiece to vibrate.

The invention is based on the finding that inaccuracies in the resulting welded joint, in particular with regard to the relative position of the two welded workpieces, often caused by an imprecise positioning of the second workpiece before the welding process and / or slippage of the second workpiece relative to the sonotrode during the welding process become.

According to the invention, the second workpiece can therefore be brought into an exact and reproducible position relative to the sonotrode and the first workpiece by means of the holding device. Further, the second workpiece may be held in position relative to the sonotrode during the welding operation. Slippage of the second workpiece relative to the sonotrode during welding is thereby prevented.

The holding device thus ensures an exact and reproducible welding of the first workpiece with the second workpiece. This allows a more precise welded connection.

In one embodiment of the ultrasonic welding device according to claim 2, the holding device is designed such that the holding device can be brought into a releasable positive connection with a structure of the second workpiece such that at least two mechanical translational degrees of freedom of the second workpiece can be blocked.

A structure here means a shaping of the boundary surfaces (for example elevations and recesses) of the second workpiece.

In other words, the holding device is designed such that the second workpiece can be fixed relative to the holding device at least within the oscillation plane of the sonotrode.

As a result, an exact and reproducible positioning of the second workpiece is achieved relative to sonotrode. Furthermore, sufficient fixation of the second workpiece relative to the sonotrode during welding is made possible with little effort.

An ultrasonic welding apparatus according to claim 3 has a pin which is formed such that the pin can be at least partially inserted in a recess of the second workpiece.

The pin preferably has a cylindrical shape. However, the pin can also have any other shape. The pin is preferably designed such that it can be brought in the region of the insert over its entire surface in a detachable positive-locking contact with the second workpiece. By using such a pin, the second workpiece can be accurately and reproducibly positioned relative to the sonotrode in a simple and cost-effective manner and be sufficiently fixed during welding.

In one embodiment of the ultrasonic welding device according to claim 4, the pin has a conical shape. The pin is resiliently mounted by means of a spring device, that the pin can be pressed with a spring force against the second workpiece.

The spring force preferably acts parallel to the surface normal of the vibration plane of the second workpiece.

By the spring means, the pin can be pressed in an advantageous manner with a defined and uniform force against the second workpiece. As a result, the contact between the pin and the second workpiece is reliably maintained even during welding, whereby a sufficient fixation of the second workpiece is achieved relative to the sonotrode.

Furthermore, the pin can be brought into a positive connection due to the conical shape with different recess sizes and recess shapes (for example, round, square, triangular). This allows greater tolerances in the manufacture of the pin and the recess.

In one embodiment of the ultrasonic welding device according to claim 5, the holding device is mechanically coupled via the sonotrode with the vibration generator.

The holding device is thus connected directly to the sonotrode. As a result, the second workpiece can be positioned with high accuracy relative to the sonotrode.

Furthermore, the vibration of the sonotrode will be transmitted directly to the fixture. The synchronicity of the vibration of the holding device to the vibration of the sonotrode can thereby be improved.

In one embodiment of the ultrasonic welding device according to claim 6, the holding device is designed such that the holding device can be released from the second workpiece before or during a welding operation.

The welding process is the period of time during which the vibration of the sonotrode has an effect on the two workpieces (heating and / or welding of the workpieces).

The second workpiece can continue to be positioned accurately and reproducibly relative to the sonotrode before the welding operation of the holding device. However, the connection between the second workpiece and the holding device can be released before or during the welding process, so that the second workpiece is held only by the sonotrode.

This is particularly advantageous if, due to the holding of the second workpiece by the holding device during the welding operation, the second workpiece can be deformed due to the ultrasonic vibrations used. However, an exact and reproducible positioning of the second workpiece before the welding process is still possible. The reliability of the ultrasonic welding device can thus be further increased.

In a method according to claim 7 for operating an ultrasonic welding device according to one of claims 1 to 5, the first workpiece is brought into connection with the anvil device in such a way that the first workpiece is held by the anvil device. The second workpiece is brought into connection with the holding device such that the second workpiece is held by the holding device and at the same time at least partially in contact with the sonotrode and the first workpiece. The sonotrode is then caused to vibrate by the vibration generator, so that the first workpiece is welded to the second workpiece in the region of the contact.

With regard to the advantages, reference is made to the embodiment of claims 1 to 5, which apply analogously.

In a method according to claim 8, the holding device is designed such that the holding device can be released from the second workpiece before or during the welding operation and the holding device is released from the second workpiece before or during the welding operation.

With regard to the advantages, reference is made to the embodiment of claim 6, which is valid in an analogous manner.

In the following the invention will be explained in more detail by means of embodiments with reference to the attached figures.

The figures show:

1 a schematic representation of an ultrasonic welding device with two workpieces to be welded;

2 a schematic representation (full section) of a pin and a workpiece;

3 a schematic representation of an ultrasonic welding device with spring means and two workpieces to be welded;

4 a schematic representation (full section) of a spring-mounted pin and a workpiece;

5 a schematic representation of an ultrasonic welding device with two to be welded workpieces.

1 shows a first embodiment of an ultrasonic welding device 1 with a skeleton 14 , a vibration generator 13 , a sonotrode 11 , a holding device 12 and an anvil device 21 ,

The anvil device 21 serves as a support and holder for a first workpiece 31 , The surface of the anvil device 21 may be roughened or have a structure to a frictional connection with the first workpiece 31 to reinforce. The anvil device 21 however, it may also have an additional retention mechanism.

On the skeleton 14 is the vibration generator 13 attached.

The vibration generator 13 is with the sonotrode 11 and the holding device 12 coupled, so that when operating the vibration generator 13 the holding device 12 synchronous to the sonotrode 11 swings.

The vibration generator 13 may preferably generate a mechanical ultrasonic vibration during operation (for example via a piezoelectric effect).

The sonotrode 11 can the generated mechanical vibrations of the vibration generator 13 on a second workpiece 32 transferred, leaving the second workpiece 32 synchronous with the sonotrode 11 vibrates in a plane of vibration (x, y). The transmission of the vibration via a non-positive connection of the sonotrode 11 with the second workpiece 32 , To strengthen the adhesion, the surface of the sonotrode 11 roughened in the region of the connection or have a structure.

The holding device 12 can the second workpiece 32 hold by the holding device 12 with a structure of the second workpiece 32 is brought into a releasable positive connection. As the holding device 12 synchronous to the sonotrode 11 can swing relative to the sonotrode 11 at least two mechanical translational degrees of freedom of the second workpiece 32 be blocked within the vibration plane (x, y).

For this purpose, the holding device 12 preferably a pen 12a on which in 2 is shown in detail.

The pin is preferably made of rubber or plastic.

2 shows an embodiment with a cylindrical pin 12a , which partially into a recess of the second workpiece 32 is introduced in a form-fitting manner, so that it is in releasable contact with the recess in the region of the insert. The second workpiece 32 is thus relative to the pen 12a fixed in two directions of translation within the plane of oscillation (x, y).

3 shows a second embodiment of the ultrasonic welding device 1 , which in comparison to the first embodiment, a spring device 15 and a holding device 12 with a conical pin 12b having.

The spring device 15 is to one side with the vibration generator 13 and to an opposite side with the holding device 12 mechanically coupled.

The spring device 15 is preferably formed such that it does not resonate with a conventional ultrasonic vibration of the vibration generator 13 stands.

The holding device 12 is about the spring device 15 resiliently supported and presses with a spring force F of the spring device 15 against the second workpiece 32 ,

4 shows in one embodiment a full section through the spring device 15 , the holding device 12 with a conical pin 12b and the second workpiece 32 ,

The spring device 15 has an interior guide 17 , an outdoor tour 16 and a spring 18 on.

The exterior guide 16 is with the vibration generator 13 and the spring 18 mechanically coupled.

The feather 18 is with the inner guide 17 mechanically coupled.

The feather 18 acts with the spring force F on the inner guide 17 one.

At the spring 18 it is preferably a coil spring. However, it may also be any other type of spring (eg. Elastomer spring, leaf spring).

The feather 18 may preferably have an internal damping or an additional damping element (spring-damping system).

The inner guide 17 is within the outdoor tour 16 arranged and over the spring 18 spring-mounted. The inner guide 17 is also with the pen 12b mechanically coupled.

The inner guide 17 and the pin attached to it 12b can thus parallel to the axis of symmetry S along an inner wall of the outer guide 16 to be moved.

The pencil 12b has a conical shape, which is to the second workpiece 32 rejuvenated.

The pencil 12b is along a surface line (by the reference numerals 12b ' indicated) in positive contact with the second workpiece 32 , The pencil 12b is here with the spring force F against the second workpiece 32 pressed.

The second workpiece 32 preferably has a cylindrical recess. However, the recess may also have any other shape, for example, square, triangular or conical.

The further construction and the mode of operation of the second exemplary embodiment result analogously from the description of the first exemplary embodiment.

5 shows a third embodiment of an ultrasonic welding device 1 in which, in contrast to the first embodiment, the holding device 12 over the sonotrode 11 with the vibration generator 13 is mechanically coupled.

The ultrasonic welding device 1 also has a mechanism 19 on which between the sonotrode 11 and the pen 12 arranged and connected to these.

The mechanism 19 can the holding device 12 from the second workpiece 32 especially before or during the welding process. This can be done by the mechanism 32 the pencil 12 move so that the pen 12 from the second workpiece 32 is led out. The mechanism 19 is preferably electrically controllable.

The holding device 12 This can be done through the mechanism 19 preferably rigid with the sonotrode 11 get connected. The mechanism 19 However, may also have a spring-damping system, with which the vibrations of the sonotrode 11 controlled steamed on the pin 12 can be transmitted.

In the following, in a first method example, the operation of the ultrasonic welding device 1 be explained:
The first workpiece 31 and the second workpiece 32 consist of a weldable material, preferably of a metal or plastic.

The first workpiece 31 gets on the anvil device 21 placed. The first workpiece 31 stands at least in the area to be welded d in full-surface contact with the anvil device 21 and thereby can from the anvil device 21 be fixed at least temporarily.

The second workpiece 32 gets into the holding device 12 inserted and by the holding device 12 (or the pen 12a . 12b ) relative to the sonotrode 11 aligned and held. The second workpiece 32 stands at least in the area to be welded d with the first workpiece 31 and the sonotrode 11 in full contact.

Subsequently, an ultrasonic vibration by the vibration generator 13 generated and the welding process started. The ultrasonic vibration is via the sonotrode 11 on the second workpiece 32 transfer. The second workpiece 32 thus oscillates relative to the first workpiece 31 in the oscillation plane (x, y). The first workpiece 31 can from the anvil device 21 At least temporarily be prevented from swinging. Due to the resulting surface friction between the first workpiece 31 and the second workpiece 32 the workpieces heat up 31 and 32 in the area to be welded d. The ultrasonic vibration is generated until a welding of the first workpiece 31 with the second workpiece 32 takes place (for example, by melting the surfaces of the workpieces 31 and 32 in the area d).

After the welding of the workpieces 31 and 32 The welding process is terminated by the vibration generator 13 is switched off, so that the ultrasonic vibration stop.

The holding device 12 holds the second workpiece during the entire welding process 32 relative to the sonotrode 11 in position, whereby a more precise weld joint with respect to the positioning of the two welded workpieces is achieved relative to each other.

In a second method example, an ultrasonic welding device 1 used according to the third embodiment.

The second method example is similar to the first method example. However, the holding device becomes 12 before or during the welding operation of the second workpiece 32 about the mechanism 19 solved. After loosening stands the second workpiece 32 no longer in contact with the holding device 12 so that the second workpiece 32 at least temporarily during the welding process only from the sonotrode 11 is held.

Claims (8)

Ultrasonic welding device ( 1 ) with - an anvil device ( 21 ) for holding a first workpiece ( 31 ), - a vibration generator ( 13 ) for generating mechanical vibrations, - a sonotrode ( 11 ), which with the vibration generator ( 13 ) is mechanically coupled, for transmitting the mechanical vibrations to a second workpiece ( 32 ), - a holding device ( 12 ) for holding the second workpiece ( 32 ), wherein the holding device ( 12 ) in such a way with the vibration generator ( 13 ) is mechanically coupled, that during operation of the vibration generator ( 13 ) the holding device ( 12 ) in synchronism with the sonotrode ( 11 ) vibrates. Ultrasonic welding device ( 1 ) according to claim 1, wherein the holding device ( 12 ) is designed such that the holding device ( 12 ) with a structure of the second workpiece ( 32 ) can be brought into a positive connection in such a way that at least two mechanical translational degrees of freedom (x, y) of the second workpiece ( 32 ) are blockable. Ultrasonic welding device ( 1 ) according to claim 2, wherein the holding device ( 12 ) a pen ( 12a . 12b ), which is designed such that the pin ( 12a . 12b ) at least partially into a recess of the second workpiece ( 32 ) is insertable. Ultrasonic welding device ( 1 ) according to claim 3 with a spring device ( 15 ), whereby the pen ( 12b ) has a conical shape and by means of the spring device ( 15 ) is resiliently mounted such that the pin ( 12b ) with a spring force (F) against the second workpiece ( 32 ) is depressible. Ultrasonic welding device ( 1 ) according to one of claims 1 to 4, wherein the holding device ( 12 ) via the sonotrode ( 11 ) with the vibration generator ( 13 ) is mechanically coupled. Ultrasonic welding device ( 1 ) according to one of claims 1 to 5, wherein the holding device ( 12 ) is formed such that the holding device of the second workpiece ( 32 ) before or during a welding process is solvable. Method for operating an ultrasonic welding device ( 1 ) according to one of claims 1 to 6, wherein - the first workpiece ( 31 ) in conjunction with the anvil device ( 21 ) is brought that the first workpiece ( 31 ) from the anvil device ( 21 ), - the second workpiece ( 32 ) in connection with the holding device ( 12 ) is brought that the second workpiece ( 32 ) by means of the holding device ( 12 ) relative to the sonotrode ( 11 ) is positioned and at least temporarily held, and at least partially with the first workpiece ( 31 ) and the sonotrode ( 11 ), - a welding process is started by the sonotrode ( 11 ) by the vibration generator ( 13 ) is vibrated. Method for operating an ultrasonic welding device ( 1 ) according to claim 7, wherein the holding device ( 12 ) is formed such that the holding device of the second workpiece ( 32 ) can be solved before or during the welding process and the holding device ( 12 ) before or during the welding operation of the second workpiece ( 32 ) is solved.

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