Methods for quality assurance in laser beam welding and welding device for laser beam welding

Abstract

Method (12) for quality assurance in laser beam welding of at least two components (2, 3), comprising the following steps: A: Arranging the at least two components (2, 3) in a welding device (1), B: Producing a weld (10) to join the at least two components (2, 3) using a laser beam (9) while the at least two components (2, 3) are arranged in the welding device (1), C: Capturing the actual geometry (11) of the weld (10) while the at least two components (2, 3) are arranged in the welding device (1), D: Evaluating the captured actual geometry (11) and identifying the weld (10) as a good weld (10) or as a poor weld (10) while the at least two components (2, 3) are arranged in the welding device (1), E: In the event that the weld (10) has been identified as a poor weld (10) in step D,Correcting the weld joint (10) by temporarily at least partially melting the weld joint (10) using the laser beam (9) while the at least two components (2, 3) are arranged in the welding device (1), characterized in that: - in step C, a three-dimensional outer contour (16) is detected as the actual geometry (11) of the weld joint (10); - in step D, the detected actual geometry (11) is evaluated by comparing the detected actual geometry (11) with a target geometry (17) defined by an outer contour area (18) limited by a lower limit (19) for a minimum three-dimensional outer contour (16) of a good weld joint (10) and by an upper limit (20) for a maximum three-dimensional outer contour (16) of a good weld joint (10); - in step D, the weld joint (10) is identified as a good weld joint (10).if the detected three-dimensional outer contour (16) lies within the outer contour area (18), and is identified as a poor weld (10), if the detected three-dimensional outer contour (16) lies outside the outer contour area (18).

Description

[0001] The present invention relates to a method for quality assurance during laser beam welding of at least two components. The invention also relates to a welding device for laser beam welding of at least two components.

[0002] Two or more components can be joined together mechanically and electrically by means of a weld. Laser beam welding can be used in the series production of such welds. The components to be welded together can have different dimensions and / or can be subject to relatively large manufacturing tolerances. This can lead to different characteristics of the melt produced during laser beam welding with predetermined welding parameters, so that the welds produced in this way can turn out differently and, in particular, inhomogeneously. This can also lead to unfavorable constellations that result in an inadequate mechanical and / or electrical connection between the components. This applies in particular to the series production of hairpin connections in an electric motor.Hairpin technology uses plug-in coils, also known as hairpins, to create a winding in an electric motor or generator. The individual plug-in coils, or hairpins, consist of three-dimensionally shaped flat copper wires and must be electrically and mechanically connected at their ends. Laser welding is the preferred method for this. To ensure that the electrical machine ultimately functions properly for a predetermined operating time, high-quality welds are required.

[0003] DE 10 2024 001 049 A1 discloses a method for quality assurance during laser beam welding of at least two components. A laser beam is used to create a weld between the components, and the resulting molten pool is monitored. If the molten pool exceeds a predefined geometric limit, the laser beam is adjusted to prevent the molten pool from further exceeding the predefined geometric limit. In this case, quality assurance and adjustment of the welding parameters take place during the creation of the respective weld.

[0004] The present invention addresses the problem of providing an improved or at least a different embodiment for a method for quality assurance in laser beam welding and for a welding device for laser welding, which is characterized in particular by the high quality of the welded joints produced. In particular, a method and a device for quality assurance in laser welding are to be provided that enable series-compatible, process-reliable laser welding of joints between components, in particular with different cross-sections, wherein it should preferably be possible to influence the welding parameters during the welding process.

[0005] This problem is solved according to the invention by the subject matter of the independent claim. Advantageous embodiments are the subject matter of the dependent claims.

[0006] The invention is based on the general idea of ​​measuring and evaluating the weld after it has been produced in order to be able to decide whether the weld that has just been produced is a good weld or a bad weld. If a good weld is determined, quality assurance and thus the welding process can be ended. However, if the weld is a bad weld, the invention proposes that the bad weld be at least partially re-melted using the laser beam and then allowed to solidify again. In other words, a bad weld is temporarily at least partially re-melted. This allows the geometry of the weld to be corrected. As a result, the quality of the produced welds is improved.

[0007] In detail, a method for quality assurance during laser beam welding of at least two components is proposed, which method comprises at least five steps A, B, C, D and E. In step A, the at least two components are arranged in a welding device. In step B, a weld for connecting the at least two components is produced by means of a laser beam, while the at least two components are arranged in the welding device. In step C, an actual geometry of the weld is recorded, while the at least two components are arranged in the welding device. Step C is carried out after step B, i.e. after the weld has been produced. In step D, the recorded actual geometry is evaluated. Furthermore, in step D, the weld is identified as a good weld or a bad weld.The evaluation of the actual geometry and the identification of the welded joint take place while the at least two components are arranged in the welding device. In step E, if the welded joint was identified as a poor welded joint in step D, the welded joint is corrected by temporarily at least partially remelting the welded joint using the laser beam, while the at least two components are still arranged in the welding device.

[0008] According to an advantageous embodiment, it can be provided that after step E the method from step C, including step C, is repeated. In other words, according to step C, the actual geometry of the weld joint corrected by the temporary melting is now recorded, whereby this is also carried out while the at least two components are arranged in the welding device. This is followed by the evaluation according to step D of the recorded actual geometry and the identification of the corrected weld joint according to step D. If the corrected weld joint is still identified as a bad weld joint, step E is also repeated. In other words, the renewed at least partial melting of the weld joint is repeated until the weld joint can be identified as a good weld joint.

[0009] In another embodiment, an additional step F is provided, in which, if the welded joint has been identified as a good welded joint in step D, the method is terminated so that the at least two components can be removed from the welding device. In the case of an assembly, such as an electrical machine, in which a plurality of components are to be electrically and mechanically connected to one another in the welding device by means of a plurality of separate welded joints, the assembly is only removed from the welding device once all welded joints have been identified as good welded joints.

[0010] In another embodiment, it can be provided that in step E at least one melting parameter for operating the laser beam is determined depending on the actual geometry, and that the laser beam is operated according to the at least one melting parameter to melt the welded joint. The respective melting parameter is a welding parameter and can differ from at least one connection parameter, which also represents a welding parameter and is used to operate the laser beam during production of the welded joint. To produce the welded joint, the laser beam is therefore operated according to the at least one connection parameter. Depending on the actual geometry, the respective melting parameter can vary. For example, the actual geometry of the welded joint may be too large, so that the respective melting parameter is selected such that the welded joint is reduced in size.If, however, the weld is too small, the melting parameter can be selected to enlarge the weld. Typical melting parameters include the position of the laser beam at or within the weld, as well as the energy introduced into the weld using the laser beam. The energy can be controlled, for example, by the duration of the laser beam exposure to the weld and / or the energy density of the laser beam. The energy density of the laser beam can be achieved, for example, using power and / or pulse width modulation.

[0011] According to an advantageous embodiment, it can be provided that in step C a three-dimensional outer contour is recorded as the actual geometry of the weld joint. In step D the evaluation of the recorded actual geometry can take place by comparing the recorded actual geometry with a predetermined target geometry, which can be stored in a memory, for example. The target geometry can be defined by an outer contour range, which can be limited by a lower limit for a minimum three-dimensional outer contour of a good weld joint and by an upper limit for a maximum three-dimensional outer contour of a good weld joint. In step D the weld joint can be identified as a good weld joint if the recorded three-dimensional outer contour lies completely within the outer contour range.The weld can, however, be identified as a poor weld if the detected three-dimensional outer contour lies at least partially outside the outer contour area.

[0012] A welding device according to the invention, which is suitable for laser beam welding of at least two components, comprises a component holder for positioning the at least two components in the welding device, a laser welding device for generating a laser beam for producing a welded joint for connecting the at least two components to one another, a measuring device for detecting an actual geometry of the welded joint, an evaluation device for evaluating the actual geometry and for identifying the welded joint as a good welded joint or as a bad welded joint, and a control device which is coupled to the laser welding device, to the measuring device and to the evaluation device and which is configured to carry out the method of the type described above.The control device can then control the laser welding device for generating the laser beam to remelt the poor weld joint according to step D. Thus, the same laser welding device is used to create and correct the weld joint.

[0013] In the present context, a ‘configuration’ is synonymous with a ‘design’ and / or ‘arrangement’ and / or ‘programming’, so that the phrase ‘configured so that’ is synonymous with the phrase ‘designed so that’ and / or ‘arranged so that’ and / or ‘programmed so that’.

[0014] The measuring device for recording the actual geometry of the weld joint works optically and can in particular have a camera.

[0015] Further important features and advantages of the invention emerge from the subclaims, from the drawings and from the associated description of the figures based on the drawings.

[0016] It is understood that the features mentioned above and those to be explained below can be used not only in the respective combination specified, but also in other combinations or on their own, without departing from the scope of the invention as defined by the claims. Components mentioned above and those to be mentioned below of a higher-level unit, such as a device, apparatus, or arrangement, which are designated separately, may form separate parts or components of this unit or be integral areas or sections of this unit, even if this is shown differently in the drawings.

[0017] Preferred embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description, wherein the same reference numerals refer to the same or similar or functionally identical components.

[0018] They show, schematically, Fig. 1 a highly simplified view of a welding device, Fig. 2 a diagram illustrating a comparison of an actual geometry with a target geometry in the case of a poor weld joint, Fig. 3 a diagram as in Fig. 2, but with a good weld, Fig. 4 a flowchart illustrating a quality assurance procedure.

[0019] Accordingly Fig. 1 comprises a welding device 1, which is used for laser beam welding of at least two components 2, 3, a component holder 4, a laser welding device 5, a measuring device 6, an evaluation device 7 and a control device 8. The component holder 4 serves to position the at least two components 2, 3 in the welding device 1. The at least two components 2, 3 can be of different sizes. In a preferred application, the component holder 4 can be configured such that an assembly can be positioned therein, which contains a plurality of components 2, 3 that must be welded. For example, the assembly can be formed by a stator of an electrical machine. The individual components 2, 3 can then be plug-in coils or hairpins of a stator winding, which must be welded together at their ends, in particular in pairs.

[0020] The laser welding device 5 is configured to generate a laser beam 9 suitable for producing a welded joint 10 that electrically and mechanically connects the at least two components 2, 3. The measuring device 6 is configured to detect an actual geometry 11 of the welded joint 10. The measuring device 6 can preferably operate optically and, in particular, can have a camera for this purpose. Fig. 1, an optical scanning of the actual geometry 11 of the welded joint 10 is indicated by dashed lines. The evaluation device 7 is configured to evaluate the actual geometry 11 and can identify the welded joint 10 as a good welded joint or as a bad welded joint. The evaluation device 7 can be configured as software and / or as hardware. In particular, it can be implemented in the control device 8 at least partially in software and / or integrated in hardware. The control device 8 is coupled in a suitable manner to the laser welding device 5, to the measuring device 6 and to the evaluation device 7. The control device 8 is also configured to carry out a method 12, which is described below with reference to Fig. 4 is explained in more detail.

[0021] According to Fig. 4, the method 12, which serves for quality assurance during laser beam welding of the at least two components 2, 3, comprises a step A in which the at least two components 2, 3 are arranged in the welding device 1, namely in the component holder 4. The method 12 further comprises a step B, which is carried out after step A, in which the welded joint 10 for connecting the at least two components 2, 3 is produced by means of the laser beam 9. The at least two components 2, 3 are located in the welding device 1 or in the component holder 4. The production of the welded joint 10 can be carried out in particular according to the method known from DE 10 2024 001 049 A1 mentioned at the outset, which is hereby added in its entirety with regard to step B by express reference to the content of the present disclosure.

[0022] The method 12 further comprises a step C, which follows step B and in which the actual geometry 11 of the welded joint 10 is recorded. During step C, the at least two components 2, 3 are still arranged in the welding device 1 or in the component holder 4.

[0023] The method 12 also comprises a step D, which follows step C and in which the recorded actual geometry 11 is evaluated. As part of the evaluation, in step D, the weld joint 10 is also identified or classified or qualified as a good weld joint 10 or as a bad weld joint 10. During step D, the at least two components 2, 3 are also located in the welding device 1 or in the component holder 4. If it is determined in step D that the weld joint 10 is a bad weld joint 10, the method 12 follows a path 13, which represents the identification of the weld joint 10 as a bad weld joint 10, which in Fig. 4 is also symbolically indicated by a (-). In this case, the method 12 further comprises a step E, which follows step D and in which the poor weld 10 is corrected. The correction of the weld 10 is carried out by temporarily melting the weld 10, which is also carried out by means of the laser beam 9. During step E, the at least two components 2, 3 are also arranged in the welding device 1 or the component holder 4.

[0024] According to an advantageous embodiment, the method 12 is configured such that, after step E, it follows a return path 14 which leads back to step C. In other words, after step E, the method 12 is repeated from step C, including step C. Subsequently, in step C, the corrected weld joint 10 is recorded with regard to its actual geometry 11. Thereafter, in step D, the actual geometry of the corrected weld joint 10 is evaluated, wherein the corrected weld joint 10 can then be identified, classified, or qualified as a good weld joint 10 or still as a bad weld joint 10.

[0025] If it is determined in step D that the weld 10 is a good weld, the method 12 follows a path 15 which represents the identification of the weld 10 as a good weld 10, which is Fig. 4 is also symbolically indicated by a (+). The method 12 further comprises a step F, which is carried out when the welded joint 10 has been identified as a good welded joint 10 in step D. In step F, the method 12 is terminated. In this case, the at least two components 2, 3 can expediently be removed from the welding device 10 or from the component holder 4.

[0026] The production of the welded joint 10 according to step B is expediently carried out using at least one connection parameter with which the welding device 5 is operated to generate the laser beam 9. The respective connection parameter represents a welding parameter and can, for example, include a duration and an energy with which the laser beam 9 applies the at least two components 2, 3 to create the weld seam 10.

[0027] In step E, at least one melting parameter for operating the laser beam 9 can be determined depending on the determined actual geometry 11. During melting of the welded joint 10, the laser welding device 5 can be operated according to the respective melting parameter to generate the laser beam 9. The respective melting parameter also represents a welding parameter, in particular a time duration and energy. The respective melting parameter can differ from the connection parameter mentioned above.

[0028] In step C, a three-dimensional outer contour 16 can be determined as the actual geometry 11 of the weld joint 10. In the diagrams of the Fig. 2 and Fig. 3 shows two dimensions, namely the X-dimension and the Z-dimension of the three-dimensional outer contours 16 for two different welded joints 10. It is clear that the three-dimensional outer contour 16 also has the third dimension, here the Y-dimension. The representations of the Fig. 2 and Fig. 3 represent two-dimensional cross-sections of the three-dimensional outer contour 16 transverse to the Y dimension.

[0029] The evaluation of the recorded actual geometry carried out in step D can be carried out in particular by comparing the recorded actual geometry 11 with a target geometry 17 which is stored in the Fig. 2 and Fig. 3 is indicated by broken lines. This target geometry 17 is defined by an outer contour area 18. This outer contour area 18 is in turn limited by a lower limit 19 and an upper limit 20, which in the example of the Fig. 2 and Fig. 3 are determined by the Z dimension. The lower limit 19 represents a minimum three-dimensional outer contour 16 of a good weld joint. The upper limit 20, on the other hand, represents a maximum three-dimensional outer contour 16 for a good weld joint 10. The identification of the weld joint 10 as a good weld joint 10 or as a bad weld joint 10 carried out in step D is expediently carried out by comparing the detected three-dimensional outer contour 16 with the outer contour area 18. If the detected outer contour 16 lies at least partially outside the outer contour area 18, a bad weld joint 10 exists. This case is in Fig. 2. In a hatched area 21, the detected outer contour 16 lies outside the outer contour area 18, namely above the upper limit 20. This means that this is a bad weld 10. If, on the other hand, the detected outer contour 16 lies completely within the outer contour area 18, this is a good weld 10. This case is shown in Fig. 3. The detected outer contour 16 runs completely below the upper limit 20 and above the lower limit 19, i.e., completely within the outer contour area 18. This represents a good weld joint 10. QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] DE 10 2024 001 049 A1 [0003, 0021]

Claims

[1] Method (12) for quality assurance during laser beam welding of at least two components (2, 3), comprising the following steps: A: Arranging the at least two components (2, 3) in a welding device (1), B: Producing a welded joint (10) for connecting the at least two components (2, 3) by means of a laser beam (9), while the at least two components (2, 3) are arranged in the welding device (1), C: detecting an actual geometry (11) of the welded joint (10) while the at least two components (2, 3) are arranged in the welding device (1), D: Evaluating the detected actual geometry (11) and identifying the welded joint (10) as a good welded joint (10) or as a bad welded joint (10), while the at least two components (2, 3) are arranged in the welding device (1), E: in the event that in step D the welded joint (10) has been identified as a poor welded joint (10), correcting the welded joint (10) by temporarily at least partially melting the welded joint (10) by means of the laser beam (9) while the at least two components (2, 3) are arranged in the welding device (1). [2] Method (12) according to claim 1, characterized by , - that after step E, the process (12) is repeated from step C. [3] Method (12) according to claim 1 or 2, characterized by following step: F: in the event that in step D the welded joint (10) has been identified as a good welded joint (10), terminating the method (12) and removing the at least two components (2, 3) from the welding device (1). [4] Method (12) according to one of the preceding claims, characterized by , - that in step E, at least one melting parameter for operating the laser beam (9) is determined as a function of the actual geometry (11), and that the laser beam (9) is operated to melt the weld joint (10) according to the at least one melting parameter. [5] Method (12) according to one of the preceding claims, characterized by , - that in step C a three-dimensional outer contour (16) is recorded as the actual geometry (11) of the weld joint (10), - that in step D, the evaluation of the recorded actual geometry (11) is carried out by comparing the recorded actual geometry (11) with a target geometry (17) which is defined by an outer contour area (18) which is limited by a lower limit (19) for a minimum three-dimensional outer contour (16) of a good weld joint (10) and by an upper limit (20) for a maximum three-dimensional outer contour (16) of a good weld joint (10), - that in step D the weld joint (10) is identified as a good weld joint (10) if the detected three-dimensional outer contour (16) lies within the outer contour area (18), and is identified as a bad weld joint (10) if the detected three-dimensional outer contour (16) lies outside the outer contour area (18). [6] Welding device (1) for laser beam welding of at least two components (2, 3), - with a component holder (4) for positioning the at least two components (2, 3) in the welding device (1), - with a laser welding device (5) for generating a laser beam (9) for producing a welded joint (10) for connecting the at least two components (2, 3) to one another, - with a measuring device (6) for detecting an actual geometry (11) of the weld joint (10), - with an evaluation device (7) for evaluating the actual geometry (11) and for identifying the weld joint (10) as a good weld joint (10) or as a bad weld joint (10), - with a control device (8) which is coupled to the laser welding device (5), to the measuring device (6) and to the evaluation device (7) and which is configured to carry out the method (12) according to one of the preceding claims.

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