Device and method for cleaning a tool for laser welding

Abstract

The invention relates to a method for cleaning an inner lateral surface (7) of a tool (6) for laser welding, wherein the tool (6) is brought to a cleaning position and cleaned there, wherein, for the purpose of cleaning the tool (6) in the cleaning position, a plunger (30) and the tool (6) are placed in contact against one another and pressed against one another, and the plunger (30) is excited to plunger vibrations (34.1) of at least 1 kHz and strikes the tool (6) in such a way that the tool (6) itself is excited to broadband tool vibrations (34.2) and as a result of said broadband tool vibrations (34.2) adhesions (25) present on the inner lateral surface (7) of the tool (6) are dislodged. The invention further relates to a device for cleaning a tool (6) for laser welding, and to the use of the device for the method.

Description

[0001] Device and method for cleaning a tool for laser welding

[0002] The invention relates to a method for cleaning an inner surface of a tool for laser welding, wherein the tool is fixed to a movable welding head of the laser welding system as part of the laser welding system during laser welding and is moved into a cleaning position for the purpose of cleaning, decoupled from the welding head, and then cleaned. The invention further relates to a device for cleaning a tool for laser welding and the use of the device for the method.

[0003] In joining technology, it is known to create a material-bonded connection between components using a laser beam in a process called deep penetration welding. These components are made of materials such as copper, aluminum, steel, or corresponding alloys. Due to the nature of the process, tools used in laser welding become contaminated during the welding process. Typically, spatter from the molten metal adheres to an inner surface of the tool, which serves as a hold-down device to press the components against each other, or as a shielding tool to prevent extensive contamination of the components themselves. Therefore, the tools used for laser welding must be cleaned regularly or as needed.In practice, at least the coarse deposits must be removed after a usage time of approximately 10 to 30 minutes to ensure the tool's functionality and a high quality of the weld joint in the long term.

[0004] In practice, chemical cleaning of the tool is possible. Chemical cleaning yields good results, particularly in the reliable and thorough removal of stubborn copper residues. However, this process takes several minutes and involves the use of reactive chemicals that are complex to handle and dispose of. Therefore, chemical cleaning is typically performed offline and only for basic tool preparation. Cleaning tools during an ongoing process is rarely feasible.

[0005] Satisfactory cleaning results can also be achieved by mechanically blasting the inner surface of the tool with a fluid or particle jet. However, integrating this blasting process into the ongoing manufacturing process is difficult, making it unsuitable for frequent, rapid cleaning of the tool during production. Furthermore, as with chemical cleaning, waste products are generated that must be handled separately, and there is a risk of environmental contamination with the blasting media. Finally, the accessibility of the inner surface of the tool is often limited, further restricting the applicability of this cleaning method.

[0006] It is also known to clean the inner surface of the tool mechanically, particularly by brushing or milling. Brushing has the disadvantage that stubborn residues cannot be removed, or cannot be removed completely or reliably. Milling requires a complex cleaning device. Moreover, the relative movement between the milling cutter and the tool must be determined, controlled, and maintained very precisely to avoid damage to the tool or the milling cutter. In addition, copper, as a typical material for the components to be welded, is highly prone to smearing. The cutting edges of the milling cutter then become clogged quickly, and the cleaning effect is significantly reduced.

[0007] The object of the present invention is to provide an improved method and a device for cleaning a tool for laser welding.

[0008] To solve the problem, the invention in conjunction with the preamble of claim 1 is characterized in that, for the purpose of cleaning the tool, a plunger and the tool are placed in contact with each other in the cleaning position and pressed against each other, and that the plunger is excited to plunger vibrations with a frequency of at least 1 kHz and strikes against the tool in such a way that the tool itself is excited to broadband tool vibrations and that adhesions present on the inner surface of the tool are flaked off by these broadband tool vibrations.

[0009] The particular advantage of the invention lies in the fact that a tool for laser welding that is contaminated on its inner surface can be cleaned quickly and thoroughly. Unlike chemical cleaning, the tool does not need to be completely disassembled or replaced. It is merely decoupled from the welding head to prevent the broadband tool vibrations generated during cleaning from being transmitted to and damaging other components of the welding head or the laser welding system. The cleaning is therefore preferably carried out within the laser welding system during a brief interruption of the laser welding process.

[0010] The cleaning method according to the invention takes advantage of the fact that, due to the required mechanical and thermal stability, the laser welding tool is typically made of a metallic or ceramic material and exhibits high rigidity. It is typically ring- or tube-shaped and has a outer body that surrounds a through-hole defined by an inlet and an outlet, through which the laser beam is guided during laser welding. The high rigidity of the tool ensures that the plunger, excited to vibrate at 1 kHz or higher, always briefly detaches from the tool and re-engages. The high frequency and force of the impulses transmitted from the plunger to the tool then cause the deposits on the inner surface of the tool to be detached or spalled off. The frequency of the plunger vibrations is advantageously below 500 kHz.

[0011] Cleaning the inner surface of the tool using the method according to the invention can be carried out independently of the geometry of the inner surface. Therefore, no complex motion control and / or kinematics are required, as with cleaning using brushes or milling machines, nor are additional operating materials necessary, as with chemical cleaning or known blasting methods. Furthermore, conically shaped inner surfaces, as well as inner surfaces with undercuts that are difficult to clean mechanically by other means, can be cleaned reliably and quickly in a simple manner. Moreover, the entire inner surface is cleaned simultaneously. The tool can thus be cleaned within a short time. The cleaning method according to the invention is therefore particularly suitable for regular, frequent, and rapid intermediate cleaning of the laser welding tool.

[0012] In a preferred embodiment of the invention, the ram is pressed against the tool with its outer surface. The ram is, for example, elongated and slender. Testing of the method has shown that the contact of the ram's outer surface with the tool can be achieved in a simple yet reliable manner. The requirements for the ram's movement are comparatively low. Furthermore, the outer surface of the ram is typically larger than its end face, resulting in greater tolerance with respect to the ram's positioning.

[0013] According to an advantageous further development of the invention, the plunger is excited to vibrations in the ultrasonic range of 18 kHz or more. The use of ultrasonic vibrations advantageously allows for short cleaning process times. At the same time, the use of ultrasonic vibrations leads to good cleaning results despite the short process times.

[0014] According to an advantageous embodiment of the invention, the plunger is excited to bending vibrations, and in particular ultrasonic bending vibrations. Advantageously, these bending vibrations, especially in conjunction with the plunger's outer surface contacting the tool, lead to very good cleaning effects. The tool can thus be cleaned quickly and effectively. At the same time, proven and tested technologies, also used in ultrasonic wire bonding or typical smartwelder applications, can be employed to excite the ultrasonic bending vibrations.

[0015] Surprisingly, testing of the inventive method has shown that a remarkably thorough cleaning of the inner surface can be achieved within very short periods. Cleaning intervals of just a few hundred milliseconds are sufficient to remove the deposits, allowing the tool to continue to be used for laser welding. In the production operation of the laser welding system, the tool is typically cleaned every 10 to 30 minutes. The cleaning itself can then be carried out very quickly. A process has proven particularly advantageous in which the plunger is intermittently excited to vibrate for approximately 100 ms at a time over a period of a few hundred milliseconds, and the excitation is then briefly suspended.

[0016] The tool can be cleaned regularly, for example, at predetermined intervals. For instance, it can be cleaned after a specified number of welds and / or after a certain cumulative welding time. Alternatively, the tool can be visually inspected for contamination during operation of the laser welding system and cleaned as needed.

[0017] According to an advantageous further development of the invention, the ram is vibrated with a constant vibration amplitude. This ensures constant energy transfer. The cleaning success can thus be accurately predicted based on experience, and the required cleaning time can be determined in advance.

[0018] According to an advantageous further development of the invention, a resonance control and / or an amplitude control for the vibration amplitude is used for the vibration excitation of the plunger. This advantageously makes it possible to design the process in a well-controlled, stable and reproducible manner.

[0019] According to an advantageous embodiment of the invention, the plunger is positioned against an outer surface of the tool such that a contact point is provided opposite the inner surface of the tool which contains the deposits. A particularly good cleaning effect is advantageously achieved when the contact point is located a short distance from the deposits.

[0020] According to an alternative embodiment of the invention, the plunger can be excited to longitudinal vibrations. This can advantageously result in design-related benefits with regard to the plunger's arrangement. In particular, the space requirement can be reduced.

[0021] In an advantageous embodiment of the invention, the pressure force exerted on the plunger is detected. For example, a sensor can be provided to determine this pressure force. By detecting the pressure force, the cleaning process can be monitored, controlled, and regulated. Furthermore, the pressure force is an important process parameter that allows for the evaluation of the cleaning effectiveness during the process.

[0022] To solve this problem, the invention provides the features of claim 11. The device for cleaning the tool for laser welding, which can be integrated into a laser welding system, therefore comprises a plunger that can be excited to plunger vibrations at a frequency of 1 kHz or higher, means of movement configured to bring the plunger and the tool to be cleaned into a mounting position, an electromechanical transducer configured to excite the plunger to plunger vibrations, a control unit and an amplifier interacting with the electromechanical transducer, which are configured to electrically excite the electromechanical transducer to mechanical vibrations, as well as means for providing a pressing force configured to press the plunger and the tool to be cleaned against each other.

[0023] A force actuator or a spring, for example, serves as the means to provide the required clamping force. The tool can be moved, for instance, by means of a motion kinematic system provided by the laser welding system and, for cleaning purposes, brought into the cleaning position and decoupled from the welding head there. The motion elements are then provided by the laser welding system and are also used by the device for cleaning the laser welding tool. Overall, the device can be spatially integrated into the laser welding system or be a functional part of it. The coupling means for fixing the tool to the welding head are specifically part of the laser welding system and not part of the device for cleaning the tool.

[0024] According to the invention, the plunger of the device for cleaning the tool and the tool itself are arranged to be relatively movable relative to each other. For example, it can be provided that the tool is moved into the cleaning position and that the plunger is then moved and pressed against the tool. Alternatively, the plunger can be fixed in place and the means of movement move the tool into the contact position. Finally, the plunger and the tool can each be arranged to be movable and moved towards each other when they are brought into the contact position.

[0025] According to a preferred embodiment of the invention, the device includes a position detection unit configured to detect the position of the tool to be cleaned, and in particular its cleaning position. The device's position detection unit can then, for example, monitor and detect when the cleaning position has been reached, either optically or via sensors. The information about when the cleaning position has been reached can be used to ensure that the cleaning process only starts after the tool has reached its cleaning position, into which it was moved by the motion module.Similarly, the position detection unit can be provided as a shared part of the device and the laser welding system and serve for the continuous detection of the tool's position during laser welding, during the repositioning and repositioning of the tool, when moving the tool into the cleaning position and / or during cleaning.

[0026] According to an advantageous embodiment of the invention, the electromechanical transducer provides means for fixing the plunger, which are designed such that the plunger is excited to bending vibrations by the electromechanical transducer. In particular, a receptacle for the plunger can be provided as a means for fixing the plunger on the electromechanical transducer, which is designed such that the plunger, for example, extending longitudinally, extends perpendicular to a direction of vibration of the electromechanical transducer. The longitudinally vibrating electromechanical transducer then excites bending vibrations in the plunger extending perpendicular to the direction of vibration of the electromechanical transducer.

[0027] According to an advantageous embodiment of the invention, the electromechanical transducer, the control unit, and the amplifier are configured to excite the plunger to vibrations in the ultrasonic range of 18 kHz or more. The electromechanical transducer is then designed as a transducer that utilizes, for example, piezoelectric wall elements to generate the ultrasonic vibrations. Advantageously, the use of ultrasonic vibrations allows for efficient cleaning of the tool in a very short time.

[0028] According to an advantageous embodiment of the invention, a force sensor is provided for detecting the contact force of the plunger. The force sensor is, for example, arranged between the force actuator and the electromechanical transducer and / or integrated into the electromechanical transducer or the force actuator. This facilitates a very compact design of the cleaning device. Furthermore, the contact force can be reliably determined by sensory input.

[0029] According to a further development of the invention, the device includes an extraction system designed to remove particles released during tool cleaning. The extraction system comprises, in particular, a pump for generating an airflow through the tool and a collection container for the released particles. Advantageously, the inclusion of the extraction system further improves the cleaning effect of the device. At the same time, the collection container and the directed airflow within the tool prevent contamination of the surrounding area. Optionally, a negative pressure chamber can be provided to prevent the undirected scattering of the released particles and thus contamination of the laser welding system and / or the components to be joined therein.

[0030] To solve the problem, it is provided that the device according to the invention is used to carry out a method according to the invention for cleaning an inner surface of a tool for laser welding.

[0031] Further advantages, features, and details of the inventive method and device for cleaning the laser welding tool can be found in the dependent claims and the following description. The features mentioned therein can be essential to the invention, either individually or in any combination. Thus, the disclosure relating to the individual aspects of the invention can always be referenced reciprocally. The drawings serve only as examples to clarify the invention and are not intended to be limiting.

[0032] They show:

[0033] Fig. 1 shows a schematic representation of a laser welding system during laser welding with a tool for laser welding in a first welding position,

[0034] Fig. 2 shows the laser welding system according to Fig. 1 during laser welding in a second welding position.

[0035] Fig. 3 shows the laser welding system according to Fig. 1 during laser welding in a third welding position; Fig. 4 shows the formation of spatter and adhesion to the tool of the laser welding system during laser welding.

[0036] Fig. 5 shows a schematic representation of the tool for laser welding before cleaning, with a plunger of a device according to the invention for cleaning the tool that has not yet been engaged.

[0037] Fig. 6 shows the tool according to Fig. 5 during cleaning with the plunger engaged.

[0038] Fig. 7 shows a schematic representation of a control unit and actuator system associated with the plunger for cleaning the tool.

[0039] Fig. 8 shows a schematic representation of a first embodiment of an extraction device for cleaning the tool and

[0040] Fig. 9 shows a schematic representation of a second embodiment of the extraction device.

[0041] Figures 1 to 3 show a simplified representation of a laser welding system. The laser welding system is used to weld two components 4 and 5 together. It comprises an optical unit 15, a tool 6, and a laser unit (not shown) that provides a collimated laser beam 1. The laser beam 1 strikes a height adjustment module 10 of the optical unit 15 and exits as a slightly focused laser beam 2. The slightly focused laser beam 2 is deflected in a positioning module 11 of the optical unit 15, which, in this exemplary embodiment, includes a first pivotable mirror 12 and a second pivotable mirror 13. It then strikes a lens 14 of the optical unit 15 and exits as a focused laser beam 3. A focal point of the focused laser beam 3 is located at the welding point.

[0042] To create a material-bonded connection between the joining partners 4 and 5 using the focused laser beam 3, and in particular to form a weld seam lying in an xy-plane 18, the laser beam is moved in the xy-plane 18 by the positioning module 11. For example, the first pivotable mirror 12 can be used to deflect the laser beam 2 in an x-direction of the xy-plane 18. The second pivotable mirror 13 then serves to deflect the laser beam 2 in a y-direction of the xy-plane 18.

[0043] The height adjustment module 10 serves, for example, to shift a focal point of the focused laser beam into a z-direction 16 extending perpendicular to the xy-plane 18 and thus to compensate for height differences at the joining partners 4,5 during laser welding.

[0044] To ensure a high-quality connection between the joining partners 4 and 5, the joining partners 4 and 5 are pressed against each other. The tool 6 serves to press the joining partners 4 and 5 together. It has a through-hole extending in the z-direction 16 with an inlet opening 9 and an outlet opening 8 for the focused laser beam 3, as well as a outer body that is bounded on the inside by an inner surface 7 of the tool 6.

[0045] The movement of the focused laser beam 3 during the welding process is always such that the laser beam 3 is focused onto the joining partners 4, 5 in the area of ​​the exit aperture 8 and is spaced apart from an edge of the exit aperture 8 and the inner surface 7 of the laser welding tool 6. The exit aperture 8 thus also defines a movement area for the focused laser beam 3.

[0046] During the metallurgical bonding of the joining partners 4, 5, they are melted by the focused laser beam 3. A melt 20 of liquid metal forms, and within it a vapor capillary 21 (see Fig. 4). A vapor flare 22 is formed above the vapor capillary 21. When the melt 20 solidifies, a welded area 23 is formed in which the joining partners 4, 5 are metallurgically bonded.

[0047] Additionally, spatter 24 is generated during the welding process, detaching from the molten metal 20. If the spatter 24 strikes the inner surface 7 of the tool 6 and solidifies there, deposits 25 form. These deposits 25, which grow larger during the welding process, reduce the effective cross-sectional area of ​​the through-hole 8 of the tool 6 and thus restrict the movement range of the focused laser beam 3 during the welding process. To ensure the continued functionality of the laser welding system during laser welding, the deposits 25 must be removed from the inner surface 7 of the laser welding tool 6 from time to time. It has proven advantageous to at least roughly clean the inner surface 7 approximately every 10 to 30 minutes and, in addition, to subject the tool 6 to more thorough cleaning at longer intervals.

[0048] The invention provides for the regular, at least coarse, removal of the deposits 25 by mechanically exciting the tool 6 to vibrate, thereby blasting off or removing the deposits 25 in the area of ​​the inner surface 7. In the present case, the invention uses ultrasonic vibrations with a frequency of 18 kHz or more to remove the deposits 25. For this purpose, the tool 6 is moved into a cleaning position and decoupled from a welding head of the laser welding system, with which it is moved during laser welding. Subsequently, a plunger 30, capable of being excited to ultrasonic vibrations, is applied to the outside of the tool 6, pressed against the tool 6, and excited to plunger vibrations 34.1 in the ultrasonic range. As a result of the ultrasonic vibrations 34.1 of the plunger 30, which are transmitted to the tool 6, the tool 6 itself begins to vibrate in a broadband frequency. The tool vibrations 34.2 then dissolve the adhesions 25 in the area of ​​the inner surface 7 of the tool 6 and dissolved particles 26 are formed.

[0049] Figures 5 and 6 show a simplified illustration of the process of cleaning the tool 6 with the plunger 30. Initially, the plunger 30 is positioned at a distance from an outer surface of the tool 6. The plunger 6, which in this example is designed as an elongated, cylindrical plunger 6, is pressed against the tool 6 from the outside with its outer surface 36 and excited to vibrate in the ultrasonic range. As a result of the external excitation by the plunger 30, the tool 6 also vibrates and the deposits 25 are detached.

[0050] The tool 6, which is typically made of steel or a technical ceramic, exhibits high rigidity. Consequently, the plunger 30 impacts the tool 6 hard and at a high frequency. Each time the plunger 30 strikes the tool 6, an impulse is transferred to the tool 6, which propagates within the tool 6. However, the intensity decreases with increasing distance from the point of contact. For this reason, the plunger 30 preferably makes contact with the tool 6 in the area of ​​an adhesion 25 provided on the inner surface of the tool 6 opposite the outer surface of the tool 6.

[0051] Fig. 7 schematically shows the actuators and control unit associated with the plunger 30. As part of the device for cleaning the tool 6 for laser welding, a force actuator 39 is provided, which serves as a means of providing a contact force and is configured to move the plunger 30 along a guide element, exemplified as a linear guide 42. For the purpose of movement, the force actuator 39 acts on an electromechanical transducer 37, which in the present embodiment of the invention is designed as an ultrasonic transducer and to which the plunger 30 is attached.

[0052] The electromechanical transducer 37 is electrically controlled by a control unit 41 via an amplifier 40. The electromechanical transducer uses, for example, piezoceramics as transducer elements, which, upon electrical control or excitation in the ultrasonic range, generate the mechanical ultrasonic vibrations. The electromechanical transducer 37 then excites the plunger 30 to plunger vibrations 34.1 in the ultrasonic range.

[0053] For example, the plunger 30 is excited to ultrasonic bending vibrations by the electromechanical transducer 37. Means for fixing the plunger 30 to the electromechanical transducer 37 are preferably designed such that the elongated plunger 30 is oriented perpendicular to a direction of vibration of the electromechanical transducer 37, wherein the electromechanical transducer 37 then provides longitudinal vibrations as a result of the electrical excitation, which cause the secondary vibrations 34.1 in the plunger 30.

[0054] To achieve a good and consistent cleaning effect, it has proven advantageous to keep the vibration amplitude constant. This ensures a constant energy transfer from the plunger 30 to the tool 30. Advantageously, the control unit 41 implements resonance and / or amplitude control for this purpose. The cleaning time is typically a few hundred milliseconds. Within these few hundred milliseconds, a particularly good cleaning result can be observed if the excitation is intermittent, for example, for 100 milliseconds at a time, and then briefly interrupted.

[0055] A further component of the device for cleaning the tool 6 may be a suction device. Two examples of this suction device are shown in Figures 8 and 9.

[0056] A first embodiment of the extraction device according to Fig. 8 comprises a pump 31 which is configured to provide a directed airflow 33 in the tool 6. The airflow 33 is designed such that the supply air enters the tool 6 via the outlet opening 8 and flows out via the inlet opening 9. The airflow 33 carries the dissolved particles 26 away from the tool 6.

[0057] To provide the directed airflow 33 and to prevent the dissolved particles 26 from contaminating the environment, a vacuum chamber 32 is connected to the tool 6, which also serves as a collection container for the dissolved particles 26. The vacuum chamber 32 is arranged between the pump 31 and within the tool 6.

[0058] Fig. 9 shows a second embodiment of the cleaning device. In this embodiment, the airflow 33 is reversed. The supply air enters the tool 6 via the inlet opening 9 and flows out through the outlet opening 8 into the vacuum chamber 32. Otherwise, the design and function of the cleaning device according to Fig. 9 correspond to that of Fig. 8.

[0059] Identical components and component functions are identified by the same reference symbols. Reference symbol list

[0060] 1 collimated laser beam

[0061] 2 slightly focused laser beams

[0062] 3 focused laser beam

[0063] 4 joining partners

[0064] 5 joining partners

[0065] 6 tools

[0066] 7 Inner surface

[0067] 8 Exit opening

[0068] 9 Entrance opening

[0069] 10 Height adjustment module

[0070] 11 Positioning module

[0071] 12 mirrors

[0072] 13 mirrors

[0073] 14 Lens

[0074] 15 optical units

[0075] 16 z-direction

[0076] 18 xy-plane

[0077] 20 Melt

[0078] 21 vapor capillaries

[0079] 22 steam torch

[0080] 23 welded area

[0081] 24 spritzers

[0082] 25 Adhesion

[0083] 26 dissolved particles

[0084] 30 pestles

[0085] 31 Pump

[0086] 32. Low-pressure chamber

[0087] 33 Airflow

[0088] 34.1 Ram vibration

[0089] 34.2 Tool vibration End face Cylindrical surface Electro-mechanical transducer Force sensor Force actuator Amplifier Control unit Linear guide

Claims

Patent claims 1. A method for cleaning an inner surface (7) of a tool (6) for laser welding, wherein the tool (6) is fixed to a movable welding head of the laser welding system as part of a laser welding system during laser welding and is moved into a cleaning position for the purpose of cleaning, decoupled from the welding head, and cleaned in the cleaning position, characterized in that, for the purpose of cleaning the tool (6), a plunger (30) and the tool (6) are brought into contact with each other and pressed against each other in the cleaning position, and that the plunger (30) is excited to plunger vibrations (34.1) of at least 1 kHz and strikes the tool (6) in such a way that the tool (6) itself is excited to broadband tool vibrations (34.2), and by these broadband tool vibrations (34.2) adhesions (25) present on the inner surface (7) of the tool (6) are loosened.

2. Method according to claim 1, characterized in that the plunger (30) is applied to the tool (6) with a cylindrical surface (36) thereof.

3. Method according to claim 1 or 2, characterized in that the plunger (30) rests against the tool (6) from the outside, preferably at the level of the attachments (25).

4. Method according to one of claims 1 to 3, characterized in that a pressing force applied to the plunger (30) is detected and / or follows a predetermined force-time profile.

5. Method according to one of claims 1 to 4, characterized in that the vibration excitation of the plunger (30) takes place over a period of at least 5 ms up to preferably a maximum of 10,000 ms, particularly preferably over a period of at least 100 ms up to a maximum of 2000 ms.

6. Method according to one of claims 1 to 5, characterized in that the vibration excitation of the plunger (30) is designed as an ultrasonic excitation with frequencies of 18 kHz or more, wherein the plunger (30) is excited to ultrasonic vibrations (34.1).

7. Method according to one of claims 1 to 6, characterized in that the vibration excitation of the plunger (30) is carried out with a constant amplitude and / or intermittently.

8. Method according to one of claims 1 to 7, characterized in that the plunger (30) and the tool (6) are first placed in contact with each other and pressed against each other, and that the plunger (30) is then excited to the plunger vibrations (34.1).

9. Method according to one of claims 1 to 8, characterized in that the plunger (30) is excited to bending vibrations.

10. Method according to one of claims 1 to 9, characterized in that particles (26) detached from the inner surface (7) are suctioned off.

11. Device for cleaning a tool (6) for laser welding comprising a plunger (30) that can be excited to plunger vibrations (34.1) of 1 kHz or higher, Moving means, designed to move the plunger (30) and the tool to be cleaned (6) into a mounting position, an electro-mechanical transducer (37), designed to excite the plunger (30) to the plunger vibrations (34.1), a control unit (41) and one with the electromechanical converter cooperating amplifier (40), configured to electrically excite the electro-mechanical converter (37), Means for providing a pressing force, designed to press against each other the plunger (30) and the tool to be cleaned (6).

12. Device according to claim 11, characterized in that a force actuator (39) is provided as a means for providing the pressing force and / or that a force sensor (38) is provided, wherein the force sensor (38) is configured to determine the pressing force of the plunger (30).

13. Device according to claims 11 to 12, characterized in that a position detection unit is provided, wherein the position detection unit is configured to detect a position of the tool (6) to be cleaned and in particular the cleaning position of the tool (6) to be cleaned.

14. Device according to one of claims 11 to 13, characterized in that the plunger (30) is held movable and that the device provides guide means which are designed to guide the plunger (30) during its movement.

15. Device according to one of claims 11 to 14, characterized in that an extraction device is provided, wherein the extraction device is configured to extract particles (26) released during the cleaning of the tool (6) and wherein the extraction device comprises a pump (31) for providing an airflow (33) through the tool (6) and a collection container for the released particles (26) and optionally a vacuum chamber (32).

16. Device according to one of claims 11 to 15, characterized in that means for fixing the plunger (30) to the electromechanical transducer (37) are provided, wherein the means are designed such that the electromechanical transducer (37) excites the plunger (30) to bending vibrations.

7. Use of a device according to one of claims 11 to 16 for carrying out a method for cleaning an inner surface (7) of a tool (6) for laser welding according to one of claims 1 to 10.

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