Methods for joining components by laser welding and laser welding equipment

Abstract

The invention relates to a method for joining components (14, 16) by laser welding using a laser welding device (12), in which a first component (14) and a second component (16) are arranged next to each other at their respective side surfaces (18, 20) and are welded together by generating an energy input through laser welding at their respective end regions (15, 17), wherein the first component (14) receives an increased first energy input (E1) during laser welding compared to a second energy input (E2) for the second component (16). For the welding of the two components (14, 16) together, a continuous weld path (S3) with homogeneous path fractions on both components (14, 16) is generated, whereby a second laser power on the path fraction of the second component (14) is lower than a first laser power on the first component (16). According to the invention, an image recognition method is carried out for component identification using an optical detection device (30) and at least one gap (28) between the components (14, 16) is also detected using the image recognition method and the laser power is modulated depending on the gap (28).

Description

[0001] The invention relates to a method for joining components according to the preamble of claim 1.

[0002] Laser welding of components, including busbars and hairpins, is already a known process. German patent DE 102018009954 A1 discloses a welding process in which the laser beam is deliberately passed through the combined melt again after melting to improve the mixing of the two molten materials, thus ensuring the mixing and bonding of the respective melts.

[0003] German patent DE 10 2019 216 194 A1 discloses a method for welding copper bars using laser welding. The two bars are positioned flush against each other to form a common welding surface. A moving focal spot of a welding beam is applied to the welding surface to locally melt the copper material and create a weld structure that overlaps both end faces. The focal spot is guided in a spiral pattern within an outer contour of the welding surface.

[0004] The generic patent US 2016 / 0016261 A1 discloses a system and method for precision laser welding. The laser pulses exhibit varying intensities across the material joint, thus varying the power density to compensate for differences in material properties. This results in a uniform weld pool alloy despite differing material properties.

[0005] From EP 3 292 940 A1, a laser welding process for flat wires is known in which the side surfaces of the flat wires are butted together and a laser beam is directed onto at least one of the end surfaces of the two flat wires to weld the side surfaces together. For this purpose, the laser beam is guided in a loop within the end surface of the first flat wire to form a weld pool. By gradually increasing the diameter of the loop-shaped laser path, the weld pool is brought towards the side surfaces, thus welding the two side surfaces of the flat wires together. Finally, the loop-shaped laser path can also extend at least partially beyond the end surface of the first flat wire and continue onto the end surface of the second flat wire to form a common weld pool.

[0006] In addition, DE 10 2004 043 076 A1 discloses a method for monitoring a laser beam processing operation. This involves taking into account a multitude of process parameters during monitoring, including the positioning and alignment of a laser head attached to a robot arm relative to at least one workpiece to be processed, a deflection device and a focusing device for guiding the laser beam, as well as the surface of the workpiece itself. The processing zone, the surface of the workpiece, and the point of impact of the laser beam can be observed with a camera. The acquired signals are then processed in a control unit and compared with target signals, so that in the event of deviations, a control signal can be generated for the robot arm, the deflection device, and the focusing device of the laser beam, thus reducing deviations from the target signal.

[0007] The object of the invention is to provide a way to make the welding of two components particularly simple and efficient, especially by saving on complicated process steps.

[0008] This problem is solved according to the invention by a method with the features of claim 1. Advantageous embodiments of the method according to the invention are to be regarded as advantageous embodiments of the laser welding device according to the invention, wherein the means of the laser welding device are used to carry out the process steps. Furthermore, advantageous developments of the invention are described by the dependent claims, the following description, and the figures.

[0009] One aspect of the invention relates to a method for joining components by laser welding using a laser welding device. The method involves welding components, particularly hairpins and / or busbars, together using a laser welding device, where the components have different material thicknesses. In this method, a first component and a second component are positioned next to each other at their respective surfaces and welded together by generating energy through laser welding in their respective end regions. In other words, the components are brought together, for example by means of a clamping device, whereby the components are positioned next to each other in the region of their respective surfaces.By generating a laser beam or by generating the energy input, it is intended that the components in the area of ​​the surfaces are at least partially melted in order to fuse them together and thus enable contact.

[0010] To achieve the objective of the invention, it is provided that the first component receives a higher initial energy input during laser welding compared to a second energy input for the second component. Thus, it is provided that two different energy inputs are used, with the first energy input being greater than the second. The first energy input is applied to the first component and the second to the second component. In particular, it is provided that the second component is designed as a hairpin and is welded to a relatively larger first component, such as a busbar.

[0011] The aim is therefore to provide an efficient and straightforward method for welding two components, with a particular focus on avoiding complicated processes or complex process steps. To achieve this, a two-stage approach is pursued, utilizing two different energy inputs.

[0012] In this process, the first component is subjected to an increased initial energy input during laser welding. This energy input is stronger than the second energy input for the second component. The purpose of this initial energy input is to melt, or at least partially melt, the first component in order to then effectively weld it to the second component. This high energy input can be achieved, for example, by introducing a laser beam into the first component.

[0013] The second energy input, which is weaker than the first, is applied to the second component. This second component is specifically designed as a hairpin. This second energy input aims to melt the second component at its connection point with the larger first component, thereby ensuring a reliable weld.

[0014] Using a lower energy input for the second component aims to reduce the energy required to melt it while simultaneously welding it to the first, particularly due to its thinner material. The idea is to adjust the energy input so that the second component is melted sufficiently to create a strong bond with the first, but not so much as to cause unwanted overheating or damage, such as excessive melting of the second component's material. Excessive energy input can lead to over-melting or material loss in the second component, potentially compromising weld quality and causing contact problems between the components.Furthermore, excessive energy input can cause the material of the second component to melt too much and no longer bond effectively with the first component. This can lead to insufficient contact and a weak electrical connection.

[0015] In other words, the invention proposes that when welding components with differing thicknesses or sizes, more energy is directed onto the thicker component (the first component) in the welding area. This ensures that the first component melts first, followed by the smaller component (the second component or a hairpin), thus resulting in better bonding of the molten materials. This allows the molten materials to bond efficiently and prevents the smaller component from melting so prematurely that it cannot bond with the larger component (the second component), which would otherwise melt later. To implement the different energy levels, a special welding path or laser beam guide path is also proposed.

[0016] In other words, the invention describes a special welding process in which energy is distributed selectively and differentiated across the components to improve the molten metal and the overall weld quality. This leads to more efficient fusion and preparation of the joint between the two components. The weld bed is primarily prepared on the larger component, the first component, to better integrate the molten metal from the smaller component, the second component.

[0017] In a first advantageous embodiment of the invention, it is provided that the first component is melted first by means of the corresponding first energy or by means of the corresponding first energy input. In particular, a chronological sequence is to be represented, wherein the first component, namely the larger one, is melted first or at least partially melted, so that the second component, which has a smaller thickness or dimensions, is not melted too much. In this way, it is ensured that the second component, which is generally thinner or smaller, does not melt excessively and that the desired connection between the components is effectively prepared.

[0018] In a further advantageous embodiment of the invention, it is provided that first the first component is melted by means of a first weld bead applied to it to provide a first melt, and subsequently the second component is melted by means of a second weld bead applied to it to provide a second melt, and finally the melts are joined together. Here, it is provided that the first component is melted with a predetermined weld bead, in particular an S-bead, and then the second weld bead, for example also an S-bead, is applied to the second component, whereby the first component is already melted while the second, smaller component is being melted. The two melts then join together to form a single melt.

[0019] In a further advantageous embodiment of the invention, it is provided that first the first component is melted by means of a first weld bead on the first component to provide a first melt, and subsequently the second component is melted by means of a second weld bead to provide a second melt, and that the melts are simultaneously joined. Here, it is provided that the two components are joined by simultaneously generating a first melt on the first component and a second melt on the second component. In order to avoid subjecting the melt of the second, smaller component to excessive dynamics and excessive melting, a lower energy input is applied, whereby both melts are joined simultaneously.This eliminates a process step, particularly saving time, with the two energy inputs being generated by, for example, different laser beams. Simultaneously, the clamping device can hold the two components together, thus enabling the fusion of the respective molten materials.

[0020] In a further advantageous embodiment of the invention, a continuous weld path is generated for the welding process, comprising a first path on the first component and a second path, shorter than the first, on the second component. To avoid using two laser beams or two energy inputs, the second, smaller component is subjected to a shorter energy input path, thus precisely adapting the fusion to the component proportions. However, the laser beam can remain on the first component for a longer period, thereby traversing a longer weld path to melt it. The two molten materials then merge to form a single, unified weld.

[0021] According to the invention, a continuous weld path with homogeneous sections is generated on the components for welding them together. This is achieved using a first laser power applied to the section of the first component and a second laser power, lower than the first, applied to the section of the second component. The laser power reflects the energy input. The process is designed to follow the same path or section on both components, with the power input being higher on the second component than on the first, thus resulting in a higher energy input on the second component than on the first.

[0022] According to the invention, the continuous weld bead is also provided for to be closed and / or to be executed multiple times in an identical manner. This means that the weld bead follows a predetermined path, for example a circular path, although a circular path would also be possible.

[0023] According to the invention, an image recognition method using an optical detection device is used for component identification. Such an optical detection device, for example a camera, can, in particular, film or photograph the area of ​​the melt and process such images or data to enable at least semi-automatic, and especially fully automatic, execution of the method. Component identification makes it possible to consistently identify the first and second components and thus ensure adherence to the specified welding paths and the energy inputs at the specified times and distances.

[0024] According to the invention, the image recognition method is used to detect at least one gap between the components and to modulate the laser power depending on the size of the gap. Specifically, the laser power on the larger component is detected and controlled in such a way that the gap closes as it melts, or is bridged by the resulting melt. In particular, the laser power is regulated by the image recognition method in such a way that the gap is not directly exposed to the energy input.

[0025] Advantageously, a laser welding device for producing a joint between a first and a second component is known to those skilled in the art. This device allows the components, arranged at their respective surfaces, to be welded together by generating energy through laser welding in the area of ​​these surfaces. It is provided that during laser welding, an initial energy input can be generated at the first component, which is higher than the subsequent energy input for the second component. Furthermore, the laser welding system includes all the necessary components to carry out the process as described above, for example, an optical detection device for component identification using an image recognition method, which is particularly designed as a camera.

[0026] Further advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and from the drawings. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention.

[0027] This shows: Fig. 1 a perspective view of a possible design of a joining assembly of a first component and a second component before a method for joining the components using a laser welding device; Fig. 2 another perspective view of the joining process during the joining of the components; Fig. 3 another perspective view of the joined composite of the two components with the respective melts; Fig. 4 a cross-section of the joining of the components with the respective melt; Fig. 5. Another perspective view of the joining of the components during a process for joining the components using an optical detection device with regard to a gap between components; and Fig. 6 Another perspective view of the joining process during the procedure with a continuous weld bead.

[0028] In the figures, identical and functionally equivalent elements are provided with the same reference symbols.

[0029] Fig. Figure 1 shows a perspective view of a joining assembly 10 of a first component 14 and a second component 16, which are arranged next to each other on their respective side surfaces 18, 20, wherein the components 14, 16 have different dimensions.

[0030] The first component 14 has a cross-section of h_S x b_S and the second component 16 has a cross-section of b_H x h_H, where the cross-section of the first component 14 is larger than the cross-section of the second component 16.

[0031] In particular, the second component 16 is configured as a hairpin, and the first component 14 may, but need not, be configured as a hairpin and / or as a busbar. It is provided that an longitudinal extension direction of the first component 14 is oriented perpendicular to an longitudinal extension direction of the second component 16. Specifically, the longitudinal extension direction of the first component 14 is oriented along a longitudinal direction x of the overall system, and the longitudinal extension direction of the second component 16 is oriented along a vertical direction z of the overall system.

[0032] In particular, it is intended to join both components 14, 16 by means of a laser welding process using a laser welding device 12, in which the first component 14 and the second component 16 are arranged against each other at their side surfaces 18, 20 and held, for example, by means of a clamping device (not shown). Subsequently, the components 14, 16 are joined together at their respective end regions 15, 17.

[0033] The first component 14 shows the first side surface 18 and a width surface 25, between which a first edge 26 is formed in its own first end region 15. An end face 22 of the first component 14 is also shown.

[0034] The second component 16 does not show its own side surface, namely the second side surface 20, since this is oriented towards the first component 14. However, it has its own end surface, namely the second end surface 24, wherein a second edge 27 is formed between the second side surface 20 and the second end surface 24 in its own second end region 17 of the second component 16.

[0035] Edges 26 and 27 are joined and melted together by generating energy through laser welding to create the joint, thereby producing a melt 14a, 16a (not shown). These melts 14a, 16a are intended to fuse together and form a single melt to establish the desired contact between components 14, 16. A gap 28 may also exist between edges 26, 27.

[0036] In particular, it is planned to supply the first component 14 with an increased initial energy input E1 during laser welding compared to a second energy input E2 for the second component 16. Here, it is planned to target and apply different energy inputs E1, E2 to the respective components 14, 16 via laser welding or via the respective laser beam in order to generate different melting effects on the respective end regions 15, 17. Fig. Figure 2 shows another perspective view of the joint between the two components 14 and 16. The plan is for the first component 14 to be melted first by means of a first weld bead S1 on the first component 14 to provide a first melt 14a (not shown), and subsequently the second component 16 to be melted by means of a second weld bead S2 running mainly on it to provide a second melt 16a (also not shown). The melts 14a and 16a then fuse together.

[0037] Alternatively, it is also possible to carry out the melting of the respective melts 14a, 16a simultaneously with the joining of the respective melts 14a, 16a.

[0038] In particular, it is intended that different weld beads S1 and S2 are applied, for example, in an S-shape, where the first weld bead S1 is represented as an S-shape or S-path with elongated straight sections aligned with the longitudinal direction of the first component 14. Specifically, the individual straight paths or parallel paths are arranged closely next to each other. The second weld bead S2, on the other hand, is represented in a figure-eight shape, thus creating a continuous weld bead. Specifically, the second weld bead S2 is applied to both components 14 and 16, resulting in a transition of the second weld bead S2 from the second component 16 to the first component 14. Other weld bead configurations are also possible.

[0039] Fig. Figure 3 shows a perspective view of the joining of components 14, 16, wherein the respective melts 14a, 16a are fused together to form a total melt, thereby enabling the electrical contact that is to be provided by the process.

[0040] Fig. Figure 4 shows a cross-section of the in Fig. Figure 3 shows the joining of components 14 and 16, with particular emphasis on the surfaces where the respective components 14 and 16 abut each other. The total melt from the respective melts 14a and 16a is shown to illustrate a particularly efficient and well-executed fusion or joining of the two components 14 and 16.

[0041] Fig. Figure 5 shows another perspective view of the joining assembly, where, in particular, an image recognition method is carried out using an optical detection device 30, as shown, for component identification. Using the optical detection device 30, which is designed, for example, as a camera, the area of ​​the fusion or the melts 16a, 14a can be recorded, positioning can take place, and, for example, a gap 28 can also be detected. It is specifically intended that, using the image recognition method, at least the gap 28 between the components can be detected and the laser power or the energy input can be modulated as a function of the gap 28.In addition, welding is provided here by means of a continuous welding path S3, the path of which runs along the first component 14 and the second component 16, whereby various setting options of the laser welding device are also possible here.

[0042] In particular, it is possible that for welding the components together, a continuous weld bead S3 is produced with a first section on the first component 14 and a second section on the second component 16 that is shorter than the first. Furthermore, it is possible that for welding the components together, a continuous weld bead S3 with homogeneous stretched sections is produced on components 14 and 16, but with a first laser power or energy input E1 applied to the stretched section of the first component 14 and a second laser power or energy input E2 applied to the stretched section of the second component 16 that is lower than the first laser power or energy input E1. The continuous weld bead S3 can be continuous and / or executed multiple times in an identical manner.

[0043] Fig.Figure 6 shows another perspective view of the joining of components 14, 16, with particular attention paid to the weld line S3, in particular the weld line S3 is shown here as an S-line which has a higher energy input E1 in the areas of the reversal P_1,1, P_1,2, P1,... in order to provide the melt 14a of the first component 14, while a lower energy input E2 is applied in the areas P_2,1, P_2,2, P_2,... in order not to make the melt 16a of the second component 16 excessively large.

[0044] In summary, the invention describes a method for laser welding current-carrying components or parts of, for example, an electric motor with different material thicknesses. Reference symbol list 10 Joining 12 Laser welding device 14 first component 14a first melt 15 first end area 16 second component 16b second melt 17 second end area 18 first side surface 20 second side surface 22 first front face 24 second front face 25 slab area 26 first edge 27 second edge 28 gaps 30 optical detection devices E1 first energy input E2 second energy input S1 first welded membrane S2 second welding layer h_S first height b_S first width h_H second height b_H second width Z Upward direction X Longitudinal direction Y transverse direction

Claims

[1] Method for joining components (14, 16) by laser welding using a laser welding device (12), in which a first component (14) and a second component (16) are arranged on each other at respective side surfaces (18, 20) and are welded together by generating an energy input by the laser welding at respective end regions (15, 17), wherein an increased first energy input (E1) is supplied to the first component (14) during laser welding compared to a second energy input (E2) for the second component (16), and for welding together, a continuous welding path (S3) with homogeneous sections on the components (14, 16) is generated, however, with a first laser power on the section of the first component (14) and a second laser power lower than the first laser power on the section of the second component (16), wherein the continuous welding path (S3) is closed and / or executed several times in an identical manner, characterized by , that for component identification, an image recognition method is carried out by means of an optical detection device (30) and by means of the image recognition method, at least one gap (28) between the components (14, 16) is detected and the laser power is modulated as a function of the gap (28). [2] Method according to claim 1, characterized by that the first component (14) is first melted by means of the corresponding first energy input (E1). [3] Method according to claim 1 or 2, characterized by that first the first component (14) is melted by means of a first welding track (S1) on the first component (14) to provide a first melt (14a) and subsequently the second component (16) is melted by means of a second welding track (S2) to provide a second melt (16a) and finally the melts (14a, 16a) are joined together. [4] Method according to one of the preceding claims, characterized by that first the first component (14) is melted by means of a first welding track (S1) on the first component (14) to provide a first melt (14a) and subsequently the second component (16) is melted by means of a second welding track (S2) to provide a second melt (16a) and at the same time the melts (14a, 16a) are joined together.

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