Laser welding equipment

Abstract

The present application relates to a laser welding device for welding at least two components, said welding being carried out along a welding path extending over a component surface of at least one of the components, in which method, at least three laser beams, in particular five to thirty laser beams, are directed consecutively consecutively onto the welding line at the same time and are moved at the same feed speed across the component surface in a welding direction extending along the welding line, whereby the welding line is passed by all laser beams one after the other at least in a length region, during the movement of the laser beams in the welding direction, laser power is continuously introduced into at least one of the components by means of each of the laser beams.

Description

Technical Field

[0001] This application relates to a method for welding at least two components, the welding being performed along a welding path (Schweißbahn) extending on the surface of at least one of the components, and also to a laser welding apparatus for welding two components. Background Technology

[0002] When welding components using a laser beam, a phenomenon known as "humping" may occur. Humping refers to the upward movement of molten material as it solidifies. This upward movement is particularly common at high welding speeds and is caused by the periodic contraction and accumulation of the molten material along the trailing edge. The higher the dynamics of the molten pool produced during melting, the greater the risk of humping. The risk is especially high in continuous welding methods with high welding speeds. Utility Model Content

[0003] The objective of this application is to enable the welding of at least two components at high welding speeds with a particularly low risk of hump phenomenon.

[0004] This application solves this problem. Other possible configurations of this application are given in the specification and drawings. The features, advantages, and possible configurations set forth in respect of one subject matter within the scope of the specification should be regarded, at least by analogy, as features, advantages, and possible configurations of other corresponding subjects and every possible combination of subjects.

[0005] This application relates to a method for welding at least two components, wherein the welding is performed along a welding path extending on the surface of at least one of the components. Welding is a set of joining methods for permanently joining two or more components. Laser welding is primarily used for welding components that should be joined with high welding speeds, narrow and slender weld shapes, and minimal thermal deformation. Laser welding is typically performed without the need for additional materials. In laser welding, laser radiation is focused by at least one optical device. In this method, at least three laser beams, particularly five to thirty laser beams, are simultaneously and sequentially directed onto the welding path. This means that at least three laser beams simultaneously strike the welding path and thus onto the surface of the at least one component. Here, the laser beams strike the welding path at different points. In this method, these laser beams are also arranged to move across the component surface with the same feed rate in the welding direction extending along the welding path. Therefore, the welding path is traversed sequentially by all the laser beams at least over a length region. The setup is such that, during the movement of the laser beam along the welding direction, laser power is continuously introduced into at least one of the components by means of each laser beam. This achieves the goal of continuously introducing laser power into the at least one component by means of all laser beams during the movement of the laser beam along the welding direction. Specifically, these laser beams are configured to move at the same feed rate, particularly in the same welding direction, thereby ensuring that the relative positions of the laser beams at each meeting point on the welding path remain unchanged during the welding of the components. The laser welding equipment providing the laser beams can operate in a continuous (Dauer-Betrieb) manner. This means that laser beams are generated uninterruptedly, i.e., continuously, and directed onto the welding path. This continuous operation can also be referred to as so-called continuous wave operation (CW operation). Because the at least three laser beams are directed sequentially onto the welding path along the welding direction, the molten material produced by welding solidifies particularly slowly at the trailing edge of the processing zone (because the molten pool becomes longer), thus particularly well avoiding the aforementioned hump phenomenon, even at high welding speeds.

[0006] In a possible extension of this application, the laser beams are arranged in a straight line, one after the other. This allows for the welding of straight and linear sections of the weld path, which can be achieved particularly quickly. The linear arrangement of these laser beams reliably lengthens the molten pool, especially from the first laser beam in the line to the last laser beam arranged along the welding direction. Consequently, the molten material solidifies particularly slowly at the trailing edge, thus effectively avoiding humps at high welding speeds.

[0007] In another possible configuration of this application, the parameters of at least one of the laser beams are adjusted to generate evaporation capillaries. These evaporation capillaries can also be referred to as keyholes. It is possible that the parameters of each laser beam are adjusted such that one of the laser beams preceding the welding path in the welding direction does not generate evaporation capillaries (e.g., in heat conduction-based welding), and at least one of the laser beams following the welding path in the welding direction generates evaporation capillaries, thereby achieving deep penetration welding. This effectively avoids the hump phenomenon.

[0008] In particular, it can be configured such that for all laser beams, the corresponding parameters are tuned so that each laser beam produces an evaporation capillary. This means, for example, based on the laser power selected for each laser beam and / or based on the selected distances between the images (Abbildung) of the laser beams incident on the welding path and each other, that each laser beam produces an evaporation capillary in at least one component of the component. The more laser beams that produce evaporation capillary cavities, the more effectively the hump phenomenon can be avoided.

[0009] In another possible configuration of this application, the distance between the center points of the images of two laser beams arranged successively along the welding path is greater than at least 20% of the width of the weld seam produced by the welding, perpendicular to the welding direction and extending on the surface of the component. Specifically, the distance between the center points of the images of two laser beams arranged successively along the welding path is greater than at least 25% of the width of the weld seam produced by the welding. The greater the distance between the center points of the images of two laser beams arranged directly and successively along the welding path, the more reliably a separate evaporation capillary can be generated for each laser beam. Here, the distance between laser beams directly adjacent to each other in the welding direction, or along the welding path, is at most large enough to maintain a coherent molten pool generated by all laser beams simultaneously directed onto the welding path. This allows for particularly reliable avoidance of hump phenomena even at very high welding speeds.

[0010] In another possible configuration of this application, the distance between the center points of the images of two laser beams arranged sequentially along the welding path is greater than the diameter of the corresponding images. This stabilizes at least one evaporation capillary, thereby stabilizing the energy input by each laser beam into the at least one component. Furthermore, this allows for precise weld penetration depths along the entire weld path, resulting in exceptionally high airtightness of the weld within the welding area. Moreover, if the distance between the center points of the images of laser beams directly adjacent to each other along the welding path is greater than the diameter of the corresponding images, a particularly long molten pool can be generated by these laser beams, thereby allowing for exceptionally high welding speeds when welding components due to a reduced risk of hump phenomena.

[0011] In another possible configuration of this application, the laser power difference between these laser beams is set to a maximum of 80%, and more particularly, a maximum of 20%. Specifically, these laser beams, simultaneously directed onto the welding path, have the same laser power. This allows the molten material to solidify particularly slowly at the trailing edge of the processing zone due to the elongated molten pool, thereby particularly well avoiding hump phenomena and welding components to each other at particularly high welding speeds.

[0012] In another possible configuration of this application, at least one of the laser beams comprises a core beam and a cladding beam annularly surrounding the core beam, wherein, in particular, the laser power of the core beam has at least 80% of the total laser power of the corresponding laser beam. This means that at most 20% of the total laser power of the corresponding laser beam is provided to the cladding beam of the corresponding laser beam. It can be configured that all laser beams each comprise a core beam and a cladding beam annularly surrounding the core beam. Specifically, the imaging of the cladding beam on the surface of the at least one component is arranged circumferentially, particularly annularly, around the imaging of the core beam on the surface of the at least one component.

[0013] In particular, it can be configured to periodically change the laser power of the core beam and / or the cladding beam, wherein laser power is continuously introduced into at least one component of the weldment through the laser beams during welding. In other words, the laser power of the core beam and / or the cladding beam can be pulsed or modulated. If it is configured such that both the laser power of the core beam and the laser power of the cladding laser beam are periodically varied, this variation of the respective laser power is adapted such that at each moment, laser power is introduced into at least one component of the weldment either through the core beam or through the cladding beam. For example, the core beam and the cladding beam can be pulsed to have temporally staggered peaks and thus be pulsed at temporally staggered intervals. By periodically changing the laser power of the core beam and / or the cladding beam, the molten pool can be stabilized particularly well.

[0014] This application also relates to a laser welding apparatus for welding at least two components, the welding being performed along a welding path extending on the surface of at least one of the components. The laser welding apparatus is configured to simultaneously direct at least three laser beams, particularly five to thirty laser beams, sequentially onto the welding path and move across the surface of the components in the welding direction extending along the welding path at the same feed rate. Thus, the welding path is traversed sequentially by all the laser beams at least over a length region. During the movement of the laser beams along the welding direction, laser power is coherently introduced into at least one of the components by each of the laser beams. In particular, the laser welding apparatus is configured to arrange the laser beams such that they produce a common, coherent molten pool. In particular, the laser welding apparatus is configured to perform the method already described in conjunction with the method for welding at least two components according to this application.

[0015] Other features of this application can be derived from the description of the accompanying drawings below and from the drawings. The features and combinations of features mentioned above in the specification, as well as the features and combinations of features shown separately in the accompanying drawings below and / or in the drawings, may be used not only in the corresponding combinations given, but also in other combinations or individually, without departing from the scope of this application. Attached Figure Description

[0016] The figure shows:

[0017] Figure 1 It is a schematic top view of the component surface, with multiple laser beams directed onto the component surface. Detailed Implementation

[0018] The attached image is in Figure 1The diagram shows a top view of the component surface 10 of component 12. Specifically, the two components 12 to be welded together extend along the [insert path here]. Figure 1 The components 12 are stacked together in a stacking direction extending in the plane of the diagram. Component 12 is particularly a corresponding battery component, especially a battery component for a vehicle battery in a motor vehicle. For example, at least one of the battery components can be a cell contact system. The components 12 stacked together in the stacking direction and to be welded to each other can be made of the same material or of different materials. Alternatively, at least one of the components 12 may be a component of a bipolar plate or a bipolar plate, particularly for fuel cells or electrolyzers.

[0019] In particular, two components 12 can be welded together using a laser welding device. The laser welding device is configured to provide multiple laser beams 14. For welding components 12, at least three laser beams 14 (currently more than three laser beams 14) are simultaneously directed sequentially onto the welding path 16. The setup is such that laser power is simultaneously introduced into at least one component 12 by all the laser beams 14 directed onto the welding path 16. It is also configured that during welding of components 12, laser power is continuously introduced into at least one component 12 by means of at least one of these laser beams 14, and in particular by means of all the laser beams 14. In particular, the laser beams 14 can operate within a continuous operating range, also known as so-called continuous wave operation.

[0020] By directing the laser beam 14 onto the welding path 16, a molten pool with melt is generated, thereby forming a weld 18 based on the solidification of the melt, through which the components 12 are held together. Currently, all laser beams 14 are arranged sequentially in a straight line along the welding path 16. For welding the components 12 together, all laser beams 14 are arranged to move along the welding path 16 in the welding direction 20 at the same feed rate. Therefore, the welding path 16 is irradiated sequentially by all laser beams 14 at at least most of its points. The sequential arrangement of the laser beams 14 along the longitudinal extension of the welding path 16 results in only one langezogenized molten pool being generated by all laser beams 14, thus the melt solidifies particularly slowly at the trailing edge of the processing zone. Therefore, even at high welding speeds, the so-called hump phenomenon can be reliably avoided.

[0021] exist Figure 1 In this process, the corresponding images 22 caused by each laser beam 14 on the component surface 10 of the component 12 can be identified particularly well. Here, the distance 24 between two images 22 that are directly adjacent to each other in the welding direction 20 extends from the center point of one of the observed images 22 to the center point of the other observed image 22, which in Figure 1The images can be identified particularly well. Currently, the distance 24 between the center points of each image 22 directly adjacent to each other in the welding direction 20 is greater than the diameter 26 of the corresponding image 22. Currently, all images 22 are configured to have at least substantially the same diameter 26. Furthermore, currently, all images 22 have at least substantially equal distances 24 to their corresponding next image 22. It is also currently configured that the distance 24 between the center points of each image 22 directly adjacent to each other in the welding direction 20 is greater than at least 20%, and particularly at least 25%, of the width 28 of the weld 18 produced by welding, which extends perpendicularly to the welding direction 20 on the component surface 10. The parameters of the laser beams 14 are configured such that at least two of these laser beams 14 produce each of an evaporation capillary. In particular, the parameters of the laser beams 14 are configured such that all laser beams 14 produce each of an evaporation capillary. It is currently configured such that the difference in laser power between each laser beam 14 is at most 80%, and more particularly at most 20%. In particular, it is configured such that all laser beams 14 have the same power as each other.

[0022] Currently, all laser beams 14 are configured to have the same beam diameter in a common plane perpendicular to the beam direction. This means that all images 22 have at least substantially the same diameter 26. Therefore, particularly thin welds 18 can be produced and the heat input required for welding the component 12 is particularly small. Alternatively, the maximum single beam diameter of the laser beam 14 may be at most ten times larger than the minimum single beam diameter of the laser beam 14.

[0023] It is possible that at least one of the laser beams 14, and in particular all of the laser beams 14, each comprises a core beam and a cladding beam that annularly surrounds the core beam. To generate each laser beam 14 having a core beam and a cladding beam, two sub-laser beams having the same optical axis and different beam diameters can be superimposed on each laser beam 14. By providing each laser beam 14 having a core beam and a cladding beam, the resulting evaporation capillaries can be stabilized particularly well. In particular, the power share in the core beam is configured to account for at least 80% of the total power of the corresponding laser beam 14. These laser beams 14, comprising the corresponding core beam and cladding beam, can be provided using corresponding optical cables employing a two-in-one technology (i.e., having a ring fiber and a core fiber), wherein the two-in-one main beam can be split into multiple single beams.

[0024] In particular, a continuous-wave laser beam source selectively having modulated or pulsed laser power is provided as a laser welding device, wherein the modulation amplitude is at most 10% of the maximum power. This method is particularly suitable for bipolar plates in fuel cells or electrolyzers because it can produce tight welds and achieve particularly high productivity with particularly low heat input. Alternatively, the method can also be used to weld two battery components, especially cell contacts made of at least two different materials, because it enables welding with particularly few intermetallic phases and forms particularly strong welds with particularly low heat input. Furthermore, alternatively, the method can be used to weld foil stacks having at least one foil comprising aluminum. This method enables the production of thin welds 18 with short interaction times, thereby particularly reducing the risk of crack formation. Therefore, this method enables welding at particularly high welding speeds, where the required heat input is particularly low. Furthermore, particularly good hermeticity is achieved through precise welding. In the case of hybrid connections, particularly good restriction of intermetallic phase formation can be achieved. Furthermore, this method can reduce crack formation, especially in the case of overlapping aluminum foils.

[0025] Therefore, this method can be used for laser welding of thin metal foils made purely of iron, aluminum, or copper, or for hybrid joining. Specifically, the sheet thickness of at least one joint and thus at least one of the components 12 is in the range of 7 to 1000 micrometers, particularly for electrode foils in the range of 7 to 20 micrometers, and particularly for conductors in the range of 75 to 500 micrometers. As the laser beam source for generating the laser beams 14, a single-mode laser having 100 to 3000 watts per beam source or a multimode laser having 1000 to 24000 watts per beam source can be used. In particular, the total power of all laser beams 14 on component 12 is 1000 to 6000 watts. The laser power of each laser beam 14 is in the range of 10 to 8000 watts, particularly in the range of 50 to 700 watts. Laser welding equipment may include at least one optical element for splitting at least one laser input beam into multiple single beams. The laser welding equipment may include, for example, a multifocal lens or optical wedge, particularly diffractive or refractive optical elements. It is possible that these laser beams 14 are provided by one laser beam source and one optical device, or by at least two laser beam sources and one optical device, or by one laser beam source and at least two optical devices, or by at least two laser beam sources and at least two optical devices. The product of the beam parameters of the laser beams 14 is particularly in the range of 0.38 mm*mrad to 16 mm*mrad, particularly in the case of single-mode lasers, particularly in the range of 0.4 mm*mrad to 0.6 mm*mrad, or for multimode lasers, in the range of 2 mm*mrad to 4 mm*mrad. The diameter 26 of each imaging 22 is particularly in the range of 10 micrometers to 300 micrometers, particularly in the case of single-mode lasers, in the range of 30 micrometers to 50 micrometers, and for multimode lasers, in the range of 50 micrometers to 170 micrometers. In particular, all the images 22 of the laser beam 14 have a diameter 26 that is in the range of 0.1 to 10 times the diameter of the foremost laser beam 14 in terms of the welding direction 20, and in particular, the diameter 26 is the same as the diameter of the foremost laser beam 14.

[0026] Currently, these laser beams 14 are arranged linearly, specifically without lateral offset. If at least one of the laser beams 14 is arranged with lateral offset, this lateral offset is less than or equal to the maximum beam diameter of all the images 22 of the laser beam 14. It is possible that the laser welding equipment uses infrared lasers with wavelengths in the range of 800 nm to 1200 nm, particularly with wavelengths of 1030 nm or 1070 nm. Alternatively or additionally, the laser welding equipment may have a VIS (visible light) laser with wavelengths in the range of 400 nm to 450 nm for blue light and / or in the range of 515 nm for green light.

[0027] Currently, feed rates range from 100 mm / s to 10,000 mm / s, particularly from 300 mm / s to 4,000 mm / s. As scanner optics, laser welding equipment can especially have PFO33-2 scanner optics with an imaging ratio of 1:1 to 5:1, particularly 1.5:1 to 2:1. Alternatively or additionally, laser welding equipment can have flight optics (BEO) with an imaging ratio of 1:1 to 5:1, particularly 1.5:1 to 2:1.

[0028] Overall, this application demonstrates how to achieve multi-point “inline” laser welding.

[0029] List of reference numerals

[0030] 10 Component Surfaces

[0031] 12 components

[0032] 14 laser beams

[0033] 16 Welding routes

[0034] 18 welds

[0035] 20 Welding direction

[0036] 22 imaging

[0037] 24 distance

[0038] 26 diameter

[0039] 28 width

Claims

1. A laser welding apparatus for welding at least two components (12), characterized in that, The welding is performed along a welding path (16) extending on the surface (10) of at least one of the components (12), the laser welding apparatus being configured to simultaneously direct at least three laser beams (14) sequentially onto the welding path (16) and move across the surface (10) of the component at the same feed rate in a welding direction (20) extending along the welding path (16), whereby the welding path (16) is traversed sequentially by all the laser beams (14) at least in a length region, wherein, during the movement of these laser beams (14) along the welding direction (20), laser power is coherently introduced into at least one of the components (12) by means of each of these laser beams (14).

2. The laser welding equipment according to claim 1, Its features are, These laser beams (14) are arranged in a straight line, one after the other.

3. The laser welding equipment according to claim 1 or 2, Its features are, At least for one of these laser beams (14), the corresponding parameters are adjusted to produce evaporation capillaries.

4. The laser welding equipment according to claim 3, Its features are, For all laser beams (14), the corresponding parameters are adjusted such that each laser beam (14) produces an evaporation capillary.

5. The laser welding equipment according to claim 1 or 2, Its features are, The distance between the center points of the imaging (22) of two laser beams (14) arranged successively along the welding path (16) is greater than at least 20% of the width (28) of the weld (18) produced by the welding, which is perpendicular to the welding direction (20) and extends on the surface (10) of the component.

6. The laser welding equipment according to claim 1 or 2, Its features are, The distance between the center points of the images (22) of two laser beams (14) arranged successively along the welding route (16) is greater than the diameter of the corresponding image (22).

7. The laser welding equipment according to claim 1 or 2, Its features are, The difference in laser power between these laser beams (14) is at most 80%.

8. The laser welding equipment according to claim 1 or 2, Its features are, At least one of these laser beams (14) includes a core beam and a cladding beam that surrounds the core beam in a ring, wherein the core beam is configured to have at least 80% of the total laser power of the laser beam (14).

9. The laser welding equipment according to claim 8, Its features are, The laser power of the core beam and / or the laser power of the cladding beam are periodically varied, wherein, during welding, the laser power is continuously introduced into at least one of the components (12) by means of the laser beam (14).

10. The laser welding equipment according to claim 1 or 2, Its features are, The laser welding equipment is configured to simultaneously direct five to thirty laser beams (14) one after another onto the welding path (16) and move across the surface of the component (10) at the same feed rate in the welding direction (20) extending along the welding path (16).

11. The laser welding equipment according to claim 1 or 2, characterized in that, The difference in laser power between these laser beams (14) is at most 20%.

Images