Method for producing a laser beam weld and a welding device for this purpose

Abstract

The invention relates to a method (3) for producing a laser beam weld (7) between at least two components (4a, 4b). A focused laser beam (6a) is generated by the laser unit (2), and the weld (7) between the components (4a, 4b) is produced using this focused laser beam (6a). Then, a defocused laser beam (6b) is generated by the laser unit (2), and the weld (7) is post-processed with the defocused laser beam (6b) so that defects in the weld (7) can be melted and welded onto the weld (7). The invention also relates to the welding device (1) for carrying out the method (3).

Description

[0001] The invention relates to a method for producing a laser beam weld between at least two components using a welding device with a laser unit. The invention also relates to the welding device for carrying out the method.

[0002] When creating a material-bonded connection between two components using laser beam welding, defects can occur in the weld seam. These defects can render the manufactured component unusable.

[0003] DE 10 2024 001 049 A1 discloses a method for quality assurance in laser beam welding of at least two components. In this method, a laser beam is used to create a weld joint between the components, and the resulting weld pool is monitored.

[0004] DE 10 2009 057 997 A1 discloses a method for welding two metal components. In this method, the metal components to be joined are melted in a welding area using a laser beam, forming a weld seam. Subsequently, the surface of the weld seam is smoothed by further energy input, partially melting the weld seam in the surface area.

[0005] The object of the invention is therefore to provide an improved or at least alternative embodiment of a method of the generic type, in which the described disadvantages are overcome. The object of the invention is also to provide a welding device for carrying out the method.

[0006] This problem is solved according to the invention by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

[0007] The method according to the invention is designed for producing a laser beam weld between at least two components using a welding device with a laser unit. In this method, steps a), b), c), and d) are carried out sequentially. In step a), the laser unit generates a laser beam focused on a weld line representing the weld seam to be produced. In step b), the laser beam focused on the weld line is moved along the weld line, thereby producing the weld seam between the components. In step c), the laser unit generates a laser beam that is not focused on the weld seam being produced, i.e., a defocused laser beam. The laser beam is focused in such a way that...In measure b), the laser beam is defocused so that the weld produced in measure b) is not melted, and at least one defect that occurred in the weld produced in measure b) is melted. In measure d), the laser beam, which is not focused on the weld produced, or the defocused laser beam, is moved at least section by section along the weld produced. This melts the at least one defect that occurred in the weld produced in measure b) and welds it to the weld.

[0008] Defects in the form of spatter, adhering material, or material ejection can occur at the weld seam. In some applications, these defects are unacceptable due to high residual contamination requirements for the welded components. Measures c) and d) allow for the reworking of these defects, thereby improving the weld seam. In measure c), the laser beam is not focused on the weld seam, resulting in an enlarged laser spot and a significant reduction in energy per unit area. Consequently, in measure d), the weld seam cannot be melted because the energy of the unfocused (or defocused) laser beam is insufficient. However, the defects themselves, such as spatter, adhering material, or material ejection, can be melted and welded onto the weld seam. This allows the defects to be reworked.Material from defects no longer detaches when the welded components are used, thus improving the overall weld quality. Another advantage is that post-processing of the weld can be carried out without requiring additional space. Furthermore, the process is flexible and can be used on all metallic joints – for example, between similar materials (e.g., Al-Al) and dissimilar materials (e.g., Al-Cu). The same scanner optics of the welding fixture can be used for both creating the weld and for post-processing the weld. Post-processing of the weld is also less time-consuming, and no additional pressure piece is required.

[0009] In measure a), the laser unit can focus the laser beam on a first point, and in measure c), the laser unit can focus the laser beam on a second point that differs from the first point. The second point can be located above the first point and at a distance of between 5 mm and 10 mm, particularly preferably between 7 mm and 8 mm, from the first point, with respect to the weld seam. This allows the laser beam, focused on the second point, to reach the weld seam in a defocused state, thus reducing the energy input into the weld seam, preventing the weld seam and at least one defect from melting.

[0010] In measure d), the weld seam created in measure b) can be completely traced with the laser beam that is not focused on the weld seam, or with the defocused laser beam. This allows the entire weld seam to be freed from defects or reworked. In measure d), the weld seam created in measure b) can be traced along the same contour as the weld line in measure b). In other words, the laser unit can trace the same path with the defocused laser beam as with the focused laser beam. This significantly simplifies the rework of the weld seam.

[0011] The invention also relates to a welding device with a laser unit, wherein the welding device is designed or set up to carry out the method described above.

[0012] Further important features and advantages of the invention will become apparent from the dependent claims, the drawings and the associated description of the figures based on the drawings.

[0013] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0014] Preferred embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein identical reference numerals refer to identical or similar or functionally identical components.

[0015] Each of these shows, schematically: Fig. 1 a view of a welding device according to the invention with a laser unit and two components to be welded during the execution of a measure a) of a method according to the invention; Fig. 2 a view of components after carrying out a measure b) of the inventive method; Fig. 3 a view of the welding device according to the invention with the laser unit and two welded components during the execution of a measure c) of the method according to the invention; Fig. 4 a view of components after carrying out a measure d) of the method according to the invention.

[0016] Fig. Figure 1 shows a view of a welding device 1 according to the invention with a laser unit 2 during the execution of step a) of a method 3 according to the invention and two components 4a and 4b to be welded. In the method 3, the components 4a and 4b are laser-welded using the welding device 1. For this purpose, in step a) of the method 3 shown here, the laser unit 2 generates a laser beam 6a focused on a weld line 5 or on a first point P1.

[0017] Fig. Figure 2 shows a view of components after carrying out measure b) of the inventive method 3. Referring also to Fig. 1. In measure b), the laser beam 6a, focused on the welding line 5 or on the first point P1, is moved along the welding line 5, thereby creating a weld seam 7 connecting the components 4a and 4b at the welding line 5. As in Fig. As shown in Figure 2, defects 8 in the form of spatter, adhesions or material ejections can occur at the weld seam.

[0018] Fig. Figure 3 shows a view of the welding device 1 according to the invention with the laser unit 2 during the execution of step c) of the method 3 according to the invention, and the components 4a and 4b. In step c), the laser unit 2 generates a laser beam 6b that is not focused on the weld seam 7 or on a second point P2. Point P2 can, for example, be located at a distance A of 7.5 mm above the first point P1. As a result, the laser beam 6b reaches the weld seam 7 in a defocused state, which enlarges the laser spot generated by the laser beam 6b on the weld seam 7 and reduces the energy per unit area. Consequently, the laser beam 6b cannot melt the weld seam 7, but it can melt the defects 8.

[0019] Fig. Figure 4 shows a view of components 4a and 4b after carrying out a measure d) of the inventive method 3. Referring also to Fig. In step d), the laser beam 6b is moved along the generated weld seam 7, melting the defects 8 and welding them to the weld seam 7. Since the laser beam 6b is not focused on the weld seam 7, the weld seam 7 is not remelted. This results in the following: Fig. 4 Weld seam 7 shown with two laser-welded components 4a and 4b, to which the defects 8 are welded and cannot detach from the weld seam 7 when the components 4a and 4b are used.

Claims

[1] Method (3) for producing a laser beam weld (7) between at least two components (4a, 4b) using a welding device (1) with a laser unit (2), wherein in the method (3): a. the laser unit (2) generates a laser beam (6a) focused on a welding line (5) embodying the weld seam (7) to be produced, b. the laser beam (6a) focused on the welding line (5) is moved along the welding line (5) and thereby the weld seam (7) is created between the components (4a, 4b) at the welding line (5), c. the laser unit (2) generates a laser beam (6b) that is not focused on the weld seam (7) produced, so that the weld seam (7) produced in measure b) is not melted and at least one defect (8) that has arisen on the weld seam (7) produced in measure b) is melted, and d. the laser beam (6b) which is not focused on the produced weld (7) is moved at least section by section along the produced weld (7) so that the at least one defect (8) that arose on the produced weld (7) in measure b) is melted and welded to the weld (7). [2] Method (3) according to claim 1, characterized by , - that in measure a) the laser unit (2) focuses the laser beam (6a) on a first point (P1) and in measure c) the laser beam (6b) on a second point (P2) that differs from the first point (P1), and - that the second point (P2) is located above the first point (P1) with respect to the weld (7) and at a distance (A) between 5 mm and 10 mm from the first point (P1). [3] Method (3) according to claim 2, characterized by, that the second point (P2) is located above the first point (P1) with respect to the weld (7) and at a distance (A) between 7 mm and 8 mm from the first point (P1). [4] Method (3) according to any of the preceding claims, characterized by , that in measure d) the weld seam (7) created in measure b) is completely traversed with the laser beam (6b) which is not focused on the weld seam (7) created. [5] Method (3) according to claim 4, characterized by , that in measure d) the weld seam (7) created in measure b) is traced along the same contour as the weld line (5) in measure b). [6] Welding device (1) with a laser unit (2), wherein the welding device (1) is configured to perform the method (3) according to one of the preceding claims.

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