Device and method for welding light metal components

Abstract

A method for welding light metal components (10, 11) with a laser beam (12) from a laser beam source (13), comprising the steps of: - guiding the laser beam (12) by means of a steering unit (14) into a welding area (15) on the light metal components (10, 11) for welding the light metal components (10, 11) together, and - guiding the laser beam (12) by means of the steering unit (14) into a pretreatment area (16) on the light metal components (10, 11) for pretreating the light metal components (10, 11) to be welded in the pretreatment area (16), wherein the pretreatment area (16) is located in a welding direction (17) in front of the welding area (15), - wherein the laser beam (12) for welding the light metal components (10, 11) alternately shines into the welding area (15) and into the pretreatment area. (16) is directed, and- wherein the laser beam (12) is used to detach surface particles (25) on the light metal components (10,11) and / or for removing material (18) from a surface layer (19) of the light metal components (10, 11) from the light metal components (10, 11) into the pretreatment area (16), characterized in that the laser beam (12), when directed into the welding area (15), is emitted from the laser beam source (13) with a higher output power than when directed into the pretreatment area (16).

Description

[0001] The present invention relates to a method for welding light metal components with a laser beam from a laser beam source, wherein the laser beam is directed alternately and successively by means of a steering unit into a welding area for welding the light metal components and into a pretreatment area for pretreating the light metal components. The invention further relates to a device and a computer program for carrying out such a method, as well as a storage medium on which such a computer program is stored.

[0002] Various laser welding processes for different metal components are known in the art. Besides welding iron and / or steel components, the welding of lightweight metal components, such as aluminum components, is becoming increasingly popular, particularly in automotive manufacturing and industrial sectors where lightweight construction and corrosion resistance are important. Aluminum components can have a so-called passivation layer on their surface. This passivation layer interferes with the laser welding process of these lightweight metal components and, in particular, prevents reliable welding. Therefore, when laser beam welding such lightweight metal components, and especially when filler material is added, the passivation layer present on the component surface must be removed.In known systems, the removal of the passivation layer takes place either by means of a separate laser treatment or by means of a continuous depassivation system, in each case before the actual welding process. A system for the generic pretreatment of metal components can be found in German patent application DE 10 2018 212 810 A1. This application describes a method for welding a galvanized automotive component, in which a welding surface of the galvanized automotive component is pretreated and a connecting element is then welded to the welding surface. For the pretreatment, the zinc layer in the area of ​​the welding surface is removed by means of a laser device up to a predetermined maximum layer thickness. Performing such pretreatment costs time and therefore money.Furthermore, providing a separate laser unit and / or a depassivation system for pretreating the lightweight metal components involves high investment and maintenance costs. Depassivation systems also represent a significant environmental burden. If such pretreatment is omitted, only a relatively low process speed can be achieved. Additionally, extra seals are required at the joint between the lightweight metal components to ensure corrosion protection. Using steel components has disadvantages regarding component weight and corrosion resistance.

[0003] The object of the present invention is to at least partially address the problem described above. In particular, it is the object of the present invention to provide a method and a device for improved welding of lightweight metal components.

[0004] The aforementioned problem is solved by the claims. In particular, the aforementioned problem is solved by the method according to claim 1, the computer program product according to claim 7, the storage medium according to claim 8, and the device according to claim 9. Further advantages of the invention will become apparent from the dependent claims, the description, and the figures. Features described in connection with the method naturally also apply in connection with the computer program product, the storage medium, and the device according to the invention, and vice versa, so that the disclosure of the individual aspects of the invention always makes and / or can make reciprocal references.

[0005] According to a first aspect of the present invention, a method for welding light metal components with a laser beam from a laser beam source is provided. The method comprises the following steps: - Guiding the laser beam by means of a steering unit into a welding area on the light metal components for welding the light metal components together, and - Guiding the laser beam by means of the steering unit into a pretreatment area on the light metal components for pretreatment of the light metal components to be welded in the pretreatment area, wherein the pretreatment area is located in a welding direction in front of the welding area, - wherein the laser beam for welding the light metal components is alternately directed into the welding area and into the pretreatment area, - and wherein the laser beam is directed from the lightweight metal components to the pretreatment area for the purpose of dissolving surface particles on the lightweight metal components and / or removing material from a surface layer of the lightweight metal components.

[0006] In tests conducted within the scope of the present invention, it was discovered that by selectively and alternately deflecting the laser beam into the welding area and the pretreatment area, the need for a separate laser source and / or a separate pretreatment process on the lightweight metal components can be eliminated. This makes the process particularly cost-effective. Compared to conventional welding processes for welding or joining lightweight metal components, the process can also be carried out much more quickly. Furthermore, the complexity of the overall joining process can be reduced. In particular, simplified logistics and warehousing with regard to component buffers and / or the transport of the required components can be achieved.

[0007] According to the invention, a method for joining materials by fusion welding using a laser beam with the addition of filler material, particularly adapted to the joining partner, is proposed. That is, the filler material can be adapted to the respective joining partner or the respective light metal components. When the laser beam is directed by the steering unit into the pretreatment area, which is located in a welding direction in front of the welding area, the laser beam is deflected in a feed direction. That is, a corresponding laser beam deflection is carried out in the feed direction of the laser beam.

[0008] The removal of surface particles from light metal components can refer, for example, to the removal of oil coatings from the light metal components or from at least one of the light metal components. The removal of material from the surface layer of the light metal components can refer, in particular, to the removal of corrosion protection coatings or passivation layers resulting from a forming process.

[0009] Welding of light metal components refers specifically to the welding of a first light metal component to a second light metal component, optionally with additional filler material. The welding area can be understood as the area on the light metal components, or on at least one of the light metal components, where the light metal components are welded together. The welding area can thus be referred to as the weld pool. The pretreatment area in the welding direction and / or the feed direction prior to the welding area is the area on at least one of the light metal components where the pretreatment of the at least one light metal component takes place. During the course of the process or a corresponding welding operation, the pretreatment area can transform into the welding area.This means that as soon as the pretreatment area has been pretreated as desired and / or according to the invention, and a processing optic for emitting the laser beam moves in the welding direction, the pretreatment area can be considered a welding area in which the light metal components are or can be welded together, and in front of which a new pretreatment area is then located in the welding direction.

[0010] The alternating welding and pretreatment processes take place within a manufacturing process to create a welded joint between the lightweight metal components. Furthermore, the welding and pretreatment occur almost simultaneously during the manufacturing process. This alternating welding and pretreatment can be understood to mean that a pretreatment process is repeatedly performed after each welding operation, followed by another welding operation, and so on, until the desired weld is complete and / or the lightweight metal components are fully welded together. Directing a laser beam alternately into a welding area and a pretreatment area is already known in the prior art.However, until now this procedure has only been used when using iron and / or steel parts to preheat the pretreatment area, where the laser beam penetrates significantly deeper into the pretreatment area and is intended to specifically change the molecular structure of the welded components.

[0011] The term "area" on the light metal components can be understood as an area and / or a point, particularly directly on at least one of the light metal components, i.e., an area and / or the point where the laser beam strikes the at least one light metal component. The pretreatment area is preferably larger than the welding area. This means that the laser beam can be moved over a larger area on the light metal components for pretreatment than for welding. Welding can be carried out with the addition of filler materials to the welding area. For pretreatment, the laser beam should not heat the component unnecessarily.Accordingly, the laser beam and / or its effects should not penetrate too deeply into the surface layer of the lightweight metal components, for example, not deeper than 500 µm, and in particular not deeper than 300 µm, for example, in a range between 10 nm and 400 nm, and especially in a range between 10 nm and 50 nm. The aim is to remove and / or detach only those particles from the lightweight metal components that could hinder subsequent welding. A lightweight metal component can be understood as a component that, based on its overall weight and / or overall size, is made predominantly of lightweight metal. Metals and alloys with a density of less than 5.0 g / cm³ can be defined as lightweight metals. 3The laser beam consists of focused electromagnetic waves. Therefore, magnesium, titanium, beryllium, lithium, and preferably aluminum components, as well as their alloys, are particularly suitable as lightweight metal components.

[0012] According to a further embodiment of the present invention, in a method the steering unit has at least two steering mirrors and the laser beam is alternately directed by the at least two steering mirrors into the welding area and the pretreatment area. Using the at least two steering mirrors, a flexible and relatively free laser beam movement can be generated, with which the detachment of surface particles and / or the removal of material from the surface layer can be effectively carried out. The steering unit can have a first steering mirror for directing the laser beam in a first direction and a second steering mirror for directing the laser beam in a second direction.A guiding mirror can be understood to be, in particular, a deflecting mirror for redirecting the laser beam from the direction from which the laser beam originates to another direction in which the laser beam is to travel. The two guiding mirrors can each have a mirror surface, the mirror surfaces of which can be aligned towards each other to direct the laser beam into the welding area and the pretreatment area, so that the laser beam can be guided from the mirror surface of the first guiding mirror to the mirror surface of the second guiding mirror. The at least two guiding mirrors can be moved and / or deflected independently of each other in different directions to achieve the desired deflection of the laser beam.

[0013] Furthermore, in a method according to the present invention, it is possible that the laser beam, when directed into the welding area, is emitted from the laser beam source at a higher output power than when directed into the pretreatment area. For this purpose, specific power modulation of the laser source can be provided to output the laser beam at different output powers. Tests conducted within the scope of the present invention have shown that less output power or energy is required to detach surface particles and / or remove material from the surface layer than is necessary for welding. This also prevents the laser beam from penetrating too deeply into the lightweight metal components, or into at least one of the lightweight metal components, and thereby initiating a premature welding process.This allows for increased process reliability by using reduced output power during pretreatment.

[0014] Furthermore, in a method according to the invention, it is possible for the laser beam to be directed into the pretreatment area over a length in the range of 100 ms to 1000 ms, particularly in the range of 300 ms to 500 ms. This treatment time allows the desired surface treatment to be achieved without allowing the laser beam or the effects of the laser treatment to penetrate too deeply into the lightweight metal component. Undesirable, excessive preheating of the lightweight metal component, which could undesirably alter the material composition and / or molecular structure of the lightweight metal components, can thus be reliably prevented.

[0015] In a further embodiment of the present invention, the laser beam can be moved in a zigzag and / or circular motion across the light metal components in the pretreatment area. Such laser beam movements across the light metal components effectively remove interfering protective layers, base material, and / or filler material and flux from the pretreatment area. The zigzag and / or circular movements can be performed continuously and / or intermittently, once or repeatedly.

[0016] According to a further aspect of the present invention, a computer program product is provided which includes instructions that, when executed by a computer, cause the computer to perform the method described above. Furthermore, a storage medium, in particular a non-volatile storage medium, is provided on which a computer program product as described above is stored. Thus, the computer program product and the storage medium offer the same advantages as have been described in detail with reference to the method according to the invention.

[0017] The computer program product can be implemented as machine-readable instruction code in any suitable programming language, such as Java, C++, C#, and / or Python. The computer program product can be stored on a machine-readable storage medium, such as a data disk, a removable drive, volatile or non-volatile memory, or an onboard memory / processor. The instruction code can program a computer or other programmable devices, such as a control unit, to execute the desired functions. Furthermore, the computer program product can be made available on a network, such as the internet, from which it can be downloaded by a user as needed. The computer program product can be implemented using software, one or more specialized electronic circuits (i.e., in hardware), or in any hybrid form.by means of software components and hardware components, are implemented and / or are implemented.

[0018] According to a further aspect of the present invention, a device for welding light metal components is provided. The device comprises: - a laser beam source for emitting a laser beam, - a steering unit for directing the laser beam into a welding area on the light metal components for welding the light metal components together, and into a pretreatment area located in a welding direction in front of the welding area on the light metal components for loosening surface particles on the light metal components in the pretreatment area and / or for removing material from a surface layer of the light metal components in the pretreatment area, - wherein the steering unit is configured and designed to alternately direct the laser beam into the welding area and the pretreatment area for welding the light metal components.

[0019] The device according to the invention also offers the advantages described above. The laser beam source of the device can include a fiber optic cable and processing optics, wherein the fiber optic cable is connected to the processing optics to guide the light required for the laser beam. The laser beam source can be understood as a source for providing a laser beam and / or a light beam for generating the laser beam, for example, in the processing optics. The steering unit is preferably part of the processing optics. The processing optics can comprise a housing with a collimator unit arranged therein for generating a laser beam bundle with parallel or substantially parallel laser beams, at least one focusing unit arranged therein for combining the laser beam bundle into a focused laser beam, and a steering unit arranged therein.The steering unit is preferably arranged between the collimator unit and the at least one focusing unit. In particular, the steering unit is arranged in a laser beam direction downstream and / or below the collimator unit and upstream and / or above the focusing unit. The collimator unit can have at least one collimator lens for generating the laser beam bundle with parallel or substantially parallel laser beams. The focusing unit can have at least one focusing lens for combining the laser beam bundle into a focused laser beam that is directed back and forth between the welding area and the pretreatment area.

[0020] In a device according to the invention, the steering unit comprises at least two, and in particular exactly two, steering mirrors for alternately directing the laser beam into the welding area and the pretreatment area. The device thus has an integrated beam deflection unit. Furthermore, it is possible for the laser beam source in a device according to the invention to be configured and designed to output the laser beam at a higher output power when directed into the welding area than when directed into the pretreatment area. In addition, the steering unit in a device according to the present invention is configured and designed to direct the laser beam into the pretreatment area over a distance in a range between 100 ms and 1000 ms, and in particular in a range between 300 ms and 500 ms.Furthermore, the steering unit according to the invention is configured and designed to move the laser beam along the light metal components in the pretreatment area in a zigzag motion and / or a circular motion.

[0021] Further measures improving the invention will become apparent from the following description of various embodiments of the invention, which are schematically illustrated in the figures. All features and / or advantages arising from the claims, the description, or the figures, including design details and spatial arrangements, can be essential to the invention, both individually and in various combinations.

[0022] They each show schematically: Fig. 1 a device according to a preferred embodiment of the present invention, Fig. 2 a detail according to the invention of the in Fig. 1 device shown, Fig. 3 a block diagram to explain a method according to the invention, Fig. 4 a storage medium with a computer program product stored thereon for carrying out the method according to the invention, Fig. 5 a representation to explain a first method variant according to the present invention, Fig. 6 a representation to explain a second method variant according to the present invention, and Fig. 7 a representation to explain a third method variant according to the present invention.

[0023] Elements with the same function and mode of operation are each provided with the same reference symbols in the figures.

[0024] Fig. Figure 1 shows a device 30 for welding light metal components 10, 11. The device 30 has a laser beam source 13 with a fiber optic cable 32 and a processing optic 33 for emitting a laser beam 12. The device 30 further comprises a steering unit 14 integrated into the processing optics for steering the laser beam 12 into a welding area 15 on the light metal components 10, 11 for welding the light metal components 10, 11 together, and into a pretreatment area 16 located in a welding direction 17 in front of the welding area 15 on the light metal components 10, 11 for removing surface particles 25 on the light metal components 10, 11 in the pretreatment area 16 and / or for removing material 18 from a surface layer 19 of the light metal components 10, 11 in the pretreatment area 16.The steering unit 14 is configured and designed according to the illustrated embodiment to alternately direct the laser beam 12 successively into the welding area 15 and the pretreatment area 16 for welding the light metal components. For this purpose, the steering unit 14 comprises, as shown in . Fig. Figure 2 shows two guiding mirrors 20, 21 for directing the laser beam 12 from the laser beam source 13 alternately into the welding area 15 and into the pretreatment area 16. The two guiding mirrors allow the laser beam to be directed as shown in Figure 2. Fig. Figure 7 shows the laser beam being moved in a zigzag and / or circular pattern on the component surface. The steering unit 14 is configured and designed to direct the laser beam 12 into the pretreatment area 16 for approximately 400 ms and then back into the welding area 15 for welding.

[0025] The device 30 also includes a material feed unit 31 for supplying filler material for the welding process. The processing optics 33 comprise a collimator unit 28 with a collimator lens, a focusing unit 26 with a focusing lens, and a protective glass slider 27 with protective glass. The device 30 further comprises a computer 23 in the form of a control unit with a computer program 22 installed thereon, which is used to execute a subsequent operation with reference to Fig. The procedure described in section 3 is configured for welding the light metal components 10, 11 with the laser beam 12 from the laser beam source 13. According to the procedure, in a first step S1, the laser beam 12 is directed by the steering unit 14 into the welding area 15 on the light metal components 10, 11 in order to weld the light metal components 10, 11 together. In a second step S2, the laser beam 12 is directed by the steering unit 14 into a pretreatment area 16 on the light metal components 10, 11 in order to pretreat the light metal components 10, 11 to be welded in the pretreatment area 16, wherein the pretreatment area 16 is located in a welding direction 17 in front of the welding area 15.Here, the laser beam 12 is directed into the pretreatment area 16 to detach surface particles 25 on the light metal components 10, 11 and / or to remove material 18 from a surface layer 19 of the light metal components 10, 11. The removal of material 18 from a surface layer 19 of the light metal components 10, 11 into the pretreatment area 16 is described in [reference missing]. Fig. Figure 5 shows the dissolution of surface particles 25 on the light metal components 10, 11. Fig. Figure 6 illustrates this. The laser beam 12 is directed alternately into the welding area 15 and the pretreatment area 16 for welding the light metal components 10, 11. This means that steps S1 and S2 are performed repeatedly. When directed into the welding area 15, the laser beam 12 is emitted from the laser beam source 13 at a higher output power than when directed into the pretreatment area 16. Fig. Figure 4 shows a storage medium 24 on which a computer program product 22 is stored, comprising instructions that are executed during the execution of the computer program product 22 by the Fig. 1 computer shown 23 cause this to do with reference to Fig. to carry out the 3 described procedures.

[0026] The invention allows for further design principles in addition to those illustrated. That is, the invention should not be considered limited to the embodiments explained with reference to the figures. Reference symbol list 10 first lightweight metal component 11 second light metal component 12 Laser beam 13 Laser beam source 14 Steering unit 15 Welding area 16 Pretreatment area 17 Welding direction 18 Material 19 Surface layer 20 first steering mirror 21 second steering mirror 22 Computer program product 23 computers 24 storage devices 25 surface particles 26 Focusing unit 27 protective glass drawers 28 Collimator unit 30 Device 31 Material feeding unit 32 fiber optic cables 33 Processing optics QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 102018212810 A1

[0002]

Claims

[1] Method for welding light metal components (10, 11) with a laser beam (12) from a laser beam source (13), comprising the steps: - Directing the laser beam (12) by means of a steering unit (14) into a welding area (15) on the light metal components (10, 11) for welding the light metal components (10, 11) together, and - Directing the laser beam (12) by means of the steering unit (14) into a pretreatment area (16) on the light metal components (10, 11) for a pretreatment of the light metal components (10, 11) to be welded in the pretreatment area (16), wherein the pretreatment area (16) is located in a welding direction (17) in front of the welding area (15), - wherein the laser beam (12) is directed alternately into the welding area (15) and into the pretreatment area (16) for welding the light metal components (10, 11), and - wherein the laser beam (12) is directed from the light metal components (10, 11) into the pretreatment area (16) to dissolve surface particles (25) on the light metal components (10, 11) and / or to remove material (18) from a surface layer (19) of the light metal components (10, 11). [2] Method according to claim 1, characterized by , that the steering unit (14) has at least two steering mirrors (20, 21) and the laser beam (12) is directed alternately one after the other by the at least two steering mirrors (20, 21) into the welding area (15) and into the pretreatment area (16). [3] Method according to any of the preceding claims, characterized by , that when the laser beam (12) is directed into the welding area (15), it is emitted from the laser beam source (13) with a higher output power than when it is directed into the pretreatment area (16). [4] Method according to any of the preceding claims, characterized by, that the laser beam (12) is directed into the pretreatment area (16) over a length in a range between 100 ms and 1000 ms. [5] Method according to any of the preceding claims, characterized by , that the laser beam (12) is moved in a zigzag and / or circular pattern on the light metal components (10, 11) in the pretreatment area (16). [6] Computer program product (22), comprising instructions which, when the computer program product (22) is executed by a computer (23), cause it to execute the method according to any of the preceding claims. [7] Storage medium (24) with a computer program product (22) stored thereon according to claim 6. [8] Device (30) for welding light metal components (10, 11), comprising: - a laser beam source (13) for emitting a laser beam (12), - a steering unit (14) for directing the laser beam (12) into a welding area (15) on the light metal components (10, 11) for welding the light metal components (10, 11) together, and into a pretreatment area (16) located in a welding direction (17) in front of the welding area (15) on the light metal components (10, 11) for removing surface particles (25) on the light metal components (10, 11) in the pretreatment area (16) and / or for removing material (18) from a surface layer (19) of the light metal components (10, 11) in the pretreatment area (16), - wherein the steering unit (14) is configured and designed to direct the laser beam (12) alternately into the welding area (15) and into the pretreatment area (16) for welding the light metal components. [9] Device (30) according to claim 8, characterized by, that the steering unit (14) has at least two steering mirrors (20, 21) for steering the laser beam (12) alternately into the welding area (15) and into the pretreatment area (16). [10] Device (30) according to one of claims 8 to 9, characterized by , that the laser beam source (13) is configured and designed to output the laser beam (12) at a higher output power when directed into the welding area (15) than when directed into the pretreatment area (16). [11] Device (30) according to any one of claims 8 to 10, characterized by , the steering unit (14) is configured and designed to direct the laser beam (12) over a length in a range between 100 ms and 1000 ms into the pretreatment area (16). [12] Device (30) according to any one of claims 8 to 11, characterized by, the steering unit (14) is configured and designed to move the laser beam (12) in a zigzag and / or circular pattern on the light metal components (10, 11) in the pretreatment area (16).

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