Method for repair welding of an electrically conductive joint

Abstract

Method for repair welding of an electrically conductive joint, wherein - a first contact weld (EN) produced by a first contact welding using laser beam welding is checked for the presence of bonding defects and / or ejections and / or pores using a QS system designed as a laser triangulation system (1), - if at least one bonding defect and / or at least one ejection and / or at least one pore was / is detected, at least one parameter for a laser beam post-treatment (LB) of the initial contact weld (EN) is selected on the basis of this detection, - the initial contact weld (EN) is smoothed by means of laser beam post-treatment (LB) with at least one selected parameter by means of beam oscillation of a laser beam, thereby producing an improved weld (VN), wherein the smoothing is carried out in such a way that defects are closed by melting material from edge areas of the initial contact weld and weld protrusions, if present, are eliminated, - the quality of the produced improved weld seam (VN) is checked with the QS system (1) designed as a laser triangulation system, - if it is detected that the improved weld (VN) has sagged due to smoothing, an adapted parameter set for a re-contact weld (LS) is selected depending on the thickness of the improved weld (VN), and - at the position of the first contact welding using laser beam welding, the renewed contact welding (LS) is carried out with the selected adapted parameter set.

Description

[0001] The invention relates to a method for repair welding of an electrically conductive connection.

[0002] As described in DE 10 2024 001 164 A1, a method for testing a weld produced by a laser welding process is known from the prior art. After the weld has been produced, the solidified weld is scanned along its longitudinal and lateral extent using a measuring beam. From the measured values ​​acquired during the scanning process, a true linear displacement (lengthwise) and a true lateral displacement (widthwise) are determined on the weld surface. The linear displacement is compared with a predetermined length limit, and the lateral displacement is compared with a predetermined width limit. If the length limit or the width limit is exceeded, the weld is considered defective.

[0003] WO 2024 / 120 894 A1 describes a method for corrective welding and a weld processing device for corrective welding. In the method for corrective welding of workpieces with a defective weld, the workpiece with the defective weld is provided, image data of the workpiece is acquired using a camera device, a first image analysis based on artificial intelligence is performed on the image data to identify the weld position, a second image analysis based on artificial intelligence is performed on the image data to identify a defect class of the weld, and the weld is checked, depending on the identified weld position and the identified defect class, whether corrective welding of the weld is possible.

[0004] German patent application DE 10 2024 002 017 A1 discloses a method for repairing welded electrical connections, in particular terminal contacts or connections in automotive traction batteries, and a computer program product. In the method, the connection point, with the old cell connector or contacting element removed, is leveled and / or smoothed using a defocused laser beam and / or beam oscillation. The laser beam is guided along a path that extends beyond the length and width of a previously existing weld. A new cell connector or contacting element is then positioned and welded onto the smoothed surface of the connection point.

[0005] The invention is based on the objective of providing a method for repair welding of an electrically conductive connection that is improved compared to the prior art.

[0006] The problem is solved according to the invention by a method for repair welding of an electrically conductive connection with the features of claim 1.

[0007] Advantageous embodiments of the invention are the subject of the dependent claims.

[0008] In a method according to the invention for repair welding an electrically conductive connection, a first contact weld seam produced by a first contact weld, in particular by laser beam welding, is checked for the presence of fusion defects and / or ejections and / or pores using a quality control system. The quality control system is also referred to, for example, as a quality assurance system. According to the invention, a laser triangulation system and, for example, additionally an OCT system (OCT = Optical Coherence Tomography) and / or a camera-based system, and thus advantageously also a corresponding quality control method to be carried out with it, are used as the quality control system.

[0009] If at least one bonding defect and / or at least one ejection and / or at least one pore has been detected, at least one parameter for post-treatment, in particular laser beam post-treatment, of the initial contact weld is selected based on this detection.

[0010] The initial contact weld is smoothed according to the invention by means of laser beam post-treatment, in particular with the at least one selected parameter, by means of beam oscillation of a laser beam. This processing step is therefore referred to below as smoothing. This results in an improved weld. The smoothing of the initial contact weld is carried out in particular by wobbling the laser beam, for example in a spiral or zigzag pattern. According to the invention, this smoothing is carried out in such a way that defects, for example holes and / or pores and / or the aforementioned defects detected in the initial contact weld, are closed by melting material from the edge regions of the initial contact weld and weld reinforcement, if present, is eliminated.

[0011] The quality of the weld improvement, i.e., the resulting improved weld, is checked and specifically detected by the quality control system. Smoothing, particularly the plastic filling of pores and / or holes, can cause the resulting improved weld to sag compared to the initial contact weld, thereby reducing the original material thickness of the top sheet.

[0012] If it is detected that the improved weld has sagged due to smoothing, an adapted parameter set for a renewed contact welding, in particular by means of laser beam welding, is selected depending on a remaining weld thickness, i.e. depending on a weld thickness of the improved weld.

[0013] At the location of the first contact weld, a second contact weld is performed, particularly using laser beam welding, with the selected, adapted parameter set. The result is a so-called iO component, i.e., a correctly welded component.

[0014] Advantageously, the quality of a contact weld produced by the re-contact welding process is checked with the QS system, which confirms the presence of a flawless contact weld produced by the re-contact welding process and a required weld length and / or bonding area.

[0015] A device is designed and configured to carry out this method. The device includes, in particular, the quality control system, which is specifically designed and configured for quality inspection in the manner described, and at least one laser beam device, which is designed and configured for laser beam welding and / or laser beam post-treatment in the manner described. The described selection of the at least one parameter for laser beam post-treatment and / or the parameter set for laser beam welding can be performed, for example, by the quality control system and / or by the laser beam device and / or by another unit. The respective component is designed and configured accordingly to perform the selection in question.

[0016] This method is particularly advantageous for repairing defects that are known to occur in the weld seam when creating electrical connections between two components using laser beam welding, and which can, for example, render an entire battery module completely unusable. This applies especially to complex and interconnected cell contact units.

[0017] Due to severely limited welding areas, it is often disadvantageous to be unable to place a repair weld next to the initial contact. Over-welding is also not possible, as the risk of damaging the battery cell with the welding laser beam if it hits the defective area is high. Therefore, until now, no repair options were known for complete cell contact units due to the problems with the interconnected connectors and the confined contact points.

[0018] The described solution enables over-welding through targeted post-treatment of the initial contact, particularly the initial contact weld seam. This solution also allows for the repair of complete cell contacting units and related connections with confined contact areas.

[0019] The described solution enables repairs even with confined pole contacts through targeted preparation of the initial contact as described above, followed by welding. This reduces scrap.

[0020] The described solution can be flexibly implemented on all metallic connections, in particular on connections made of similar materials, for example aluminum, as well as on connections made of dissimilar materials, for example aluminum and copper.

[0021] The described solution, and in particular the described method, can advantageously be implemented using existing equipment. In particular, the same welding optics, especially a laser welding device, can be used for both seam preparation and repair welding.

[0022] The initial contact, weld preparation, and repair welding can advantageously be quality-checked using existing systems, particularly regarding the bond, pores, and / or holes. For example, as mentioned above, OCT and / or camera-based systems and methods and / or laser triangulation are used for this purpose.

[0023] The described solution opens up new design possibilities.

[0024] The smoothing process described can also be performed independently, i.e., solely for the direct repair of the original initial contact weld. In this case, for example, only the pores and / or holes are filled, provided the required bonding surface is achieved. Thus, an improvement in quality can be achieved even with this simple step, and the subsequent steps described after smoothing can be omitted.

[0025] Exemplary embodiments of the invention are explained in more detail below with reference to a drawing.

[0026] This shows: Fig. 1 schematically shows the process of a procedure for repair welding of an electrically conductive connection.

[0027] In Fig. Figure 1 schematically depicts an exemplary process for repair welding of an electrically conductive joint, where an orientation can be identified using an x-axis x and a z-axis z of a coordinate system. Fig. In particular, four main steps of the procedure are shown one after the other from left to right.

[0028] Links in Fig. Figure 1 shows a primary contact weld EN. It exhibits weld defects NF, particularly in the form of weld ejections, for example, in the form of pores and / or holes. It also exhibits a lack of weld fusion FN, i.e., a fusion defect.

[0029] In the process described here, this initial contact weld EN, produced by a first contact weld, in particular by means of laser beam welding, is in a Fig. 1. The first step shown on the left is checked with a QS system 1 for the presence of these seam defects NF, in particular ejections and / or pores, and binding defects.

[0030] In the example shown, QS system 1 is an OCT system. Below the initial contact weld EN, an OCT measurement signal waveform OCT_actual and a predefined sample signal waveform OCT_target are shown. From this, the missing weld junction FN and a deviation from a predefined minimum weld length l can be determined. min different seam length l ist The initial contact weld seam EN is visible.

[0031] If, as in the example shown, at least one fusion defect and / or at least one ejection and / or at least one pore has been detected, at least one parameter for a post-treatment, in particular laser beam post-treatment LB, of the first contact weld EN is selected on the basis of this detection.

[0032] The initial contact weld EN is then carried out in a Fig. In the second step shown in Figure 1, the laser beam is smoothed by means of laser beam post-treatment LB, in particular with the at least one selected parameter, by beam oscillation of a laser beam, thereby producing an improved weld seam VN. The smoothing of the initial contact weld seam EN is carried out in particular by wobbling the laser beam, for example in a spiral or zigzag pattern. This smoothing is carried out in such a way that defects, for example holes and / or pores and / or the aforementioned defects detected in the initial contact weld seam EN, are closed by melting material from the edge regions of the initial contact weld seam EN and weld reinforcements, if present, are eliminated.

[0033] The quality of the weld improvement, i.e., the improved weld VN produced, is then subsequently measured in a Fig. The third step shown in Figure 1 is checked and, in particular, detected using the QS system 1. Smoothing, especially the plastic filling of pores and / or holes, can cause the resulting improved weld VN to sag compared to the initial contact weld EN, thereby reducing the original material thickness of a top sheet, as shown in Figure 1. Fig. Figure 1 shows that the QS system 1 is used to detect, in particular, any remaining weld thickness, especially an available sheet thickness t.

[0034] If it is detected that the improved weld VN has sagged due to smoothing, as in Fig. As shown in Figure 1, depending on the remaining weld thickness, i.e., depending on the weld thickness of the improved weld VN, and / or depending on the available sheet thickness t, an adapted parameter set for a re-contact welding LS, in particular by means of laser beam welding, is selected.

[0035] Then, in a Fig. In the fourth step shown in Figure 1, at the position of the first contact weld, a second contact weld (LS) is performed using the selected, adapted parameter set, particularly by means of laser beam welding. The result is a so-called iO component, i.e., a correctly welded component.

[0036] Advantageously, in a further step, the quality of a contact weld produced by the re-contact welding LS is checked with the QS system 1, thereby verifying the presence of a defect-free contact weld produced by the re-contact welding LS and the required weld length, in particular the specified minimum weld length l. min , and / or the tying area can be confirmed.

[0037] In the example shown, it is determined in this way that the OCT measurement signal profile OCT_actual now essentially corresponds to the specified pattern signal profile OCT_target and the suture length l ist at least the specified minimum seam length l min This corresponds to, in the example shown, even being larger than the specified minimum seam length l. minFurthermore, in the example shown, it is determined that there is no longer a missing seam connection FN, but rather a completed connection VA has been achieved.

Claims

[1] Method for repair welding of an electrically conductive joint, wherein - a first contact weld (EN) produced by a first contact welding using laser beam welding is checked for the presence of bonding defects and / or ejections and / or pores using a QS system designed as a laser triangulation system (1), - if at least one bonding defect and / or at least one ejection and / or at least one pore was / is detected, at least one parameter for a laser beam post-treatment (LB) of the initial contact weld (EN) is selected on the basis of this detection, - the initial contact weld (EN) is smoothed by means of laser beam post-treatment (LB) with at least one selected parameter by means of beam oscillation of a laser beam, thereby producing an improved weld (VN), wherein the smoothing is carried out in such a way that defects are closed by melting material from edge areas of the initial contact weld and weld protrusions, if present, are eliminated, - the quality of the produced improved weld seam (VN) is checked with the QS system (1) designed as a laser triangulation system, - if it is detected that the improved weld (VN) has sagged due to smoothing, an adapted parameter set for a re-contact weld (LS) is selected depending on the thickness of the improved weld (VN), and - at the position of the first contact welding by means of laser beam welding, the renewed contact welding (LS) is carried out with the selected adapted parameter set. [2] Method according to claim 1, characterized by , that the quality of a contact weld produced by the re-contact welding (LS) is checked with the QS system (1) designed as a laser triangulation system. [3] Method according to any one of the preceding claims, characterized by , that an OCT system and / or a camera-based system is used as a QS system (1). [4] Method according to any one of the preceding claims, characterized by , that the smoothing of the initial contact weld (EN) is carried out by wobbling the laser beam.

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