Methods for determining the position of components in a joining process

Abstract

Method for determining the position of components for a joining process in which at least two joining partners (1) are positioned relative to each other and / or relative to a joining tool, in particular a laser welding device (3), and subsequently joined, in particular welded, comprising the steps - Acquisition of topographic coarse data by camera-based image recognition of surface areas of the joining partners (1) relevant to the joining process and / or a joining joint (11) formed by the joining partners (1); - Assessment of the suitability of the topographic rough data as a basis for process control for the joining process, and, -- if the assessment is positive, determination of position data by evaluating the rough data and using it in process control, or, -- if the assessment is negative, - Acquisition of topographic fine data by optical scanning of the relevant surface areas of the joining partners (1) and / or the joining joint (11) by a measuring beam (53); - Determination of position data by evaluating the coarse and fine data or by evaluating the fine data and using the position data in the process control of a joining process, characterized in that the determination of the position data is iterative, by repeatedly acquiring and evaluating topographic coarse data and / or topographic fine data, and in a joining process following the position determination, continuous quality monitoring is carried out by optical scanning of the relevant surface areas of the joining partners (1) and / or the joining joint (11) by the measuring beam (53).

Description

[0001] The invention relates to a method for determining the position of components in a joining process.

[0002] When components are joined, for example by laser welding, the correct positioning of the components relative to each other is crucial for the quality of the joint. Purely camera-based component recognition or position detection is often insufficient. The subsequent joining operation, for example by laser welding, may not take place at all or may only occur incorrectly due to insufficient positional accuracy (e.g., of the laser beam), which can lead to very poor-quality joints, for example, in terms of strength.

[0003] In the prior art, it is known to illuminate the joint and detect it using a camera. A disadvantage is that, in poor illumination or overexposure, the contours cannot be clearly identified, so that the components cannot be positioned correctly relative to each other or the joint cannot be correctly detected.

[0004] DE 10 2017 201 730 A1 relates to a device and a welding method in which at least two components are positioned relative to each other in an butt joint arrangement and joined together by a weld seam. For this purpose, a weld pool is generated at a weld point in the components using a welding device and the weld point is moved relative to the components based on control parameters. A time-of-flight detection device captures an observation window on the components that at least partially precedes the weld point, and corresponding image data is generated. By evaluating the time-of-flight image data, corresponding topographic data of the component arrangement are determined, and the control parameters of the welding device are adjusted based on the topographic data.

[0005] WO 2021 / 023 368 A1 discloses an OCT system with an optical coherence tomograph for recording a height profile of a workpiece surface by optically scanning the workpiece surface, comprising a camera for recording an image of the workpiece surface and a display for jointly, in particular superimposed, displaying the recorded image and the recorded height profile of the workpiece surface.

[0006] The object of the invention is to provide a method for determining the position of components in the joining process, which allows for a correct determination of the position of the components relative to each other.

[0007] The problem is solved according to the invention by a method having the features of claim 1.

[0008] An advantageous embodiment of the invention is the subject of the sub-claim.

[0009] The problem is solved procedurally by a method for determining the position of components for a joining process in which at least two joining partners are positioned relative to each other and / or relative to a joining tool, in particular a laser welding device, and are subsequently joined, in particular welded, and which comprises the following steps: - Acquisition of topographic rough data through camera-based image recognition of surface areas of the joining partners relevant to the joining process and / or a joint formed by the joining partners; - Assessment of the suitability of the topographic rough data as a basis for process control for the joining process, and, -- if the assessment is positive, determination of position data by evaluating the rough data and using it in process control, or, -- if the assessment is negative, - Acquisition of topographical detail data by optical scanning of the relevant surface areas and / or the joint using a measuring beam; - Determination of position data through combined evaluation of rough and fine data and use of the position data in the process control of a joining process.

[0010] On the device side, the problem is solved by a joining device, in particular a laser welding device, comprising a welding laser for generating a welding laser beam and a welding optic for aligning the welding laser beam, which further comprises the following communicating components: - a camera designed to acquire topographic coarse data of relevant surface areas of the joining partners and / or a joint formed by the joining partners, - a measuring scanning unit designed to acquire topographic fine data by optically scanning the relevant surface areas and / or the joint using a measuring beam, and - a computing and control unit designed to determine position data by evaluating the rough data and / or the fine data and to use the position data in the process control of a joining process.

[0011] According to the invention, a multi-stage recognition process takes place: A preliminary, camera-based image recognition process, for example through triangulation, is used to roughly determine the position of the components relative to each other.

[0012] Then, if necessary, the components or the joint are additionally scanned using a measuring beam, for example a measuring laser beam, for fine position determination.

[0013] Finally, the position of the components is uniquely determined through a combined evaluation of the previously recorded data from the two upstream processes in a control and computing unit.

[0014] In a special version, additional scanning using a measuring beam only takes place if camera images from the first step are insufficient in terms of accuracy, thus ensuring the shortest cycle time with the highest process reliability.

[0015] In one embodiment, the measuring beam can be an OCT (optical coherence tomography) beam.

[0016] The process can, for example, be carried out in several iteration steps.

[0017] The following advantages can be achieved through the proposed procedure: The invention enables very precise recognition of the component contours or the joint and thus an exact position determination, which is needed, for example, to guide a processing laser beam for welding.

[0018] The invention enables an increase in joining quality, which contributes to a reduction in scrap.

[0019] The measuring beam (e.g. OCT) can also be used as a measuring quality system after position detection during welding, thus providing a dual function.

[0020] The invention is particularly suitable for joining by means of laser beam welding, especially when welding connections on an electric motor (e.g. hairpins).

[0021] Due to the optional dual position detection (using image recognition and, if necessary, a measuring beam), there is great flexibility with regard to different materials and their (surface) properties; for example, both highly reflective and matte surfaces or component edges can be reliably detected.

[0022] The invention enables a reliable differentiation between components to be welded and their clamping tools or hold-down devices.

[0023] Exemplary embodiments of the invention are explained in more detail below with reference to drawings.

[0024] This shows: Fig. 1 the step of rough position determination, Fig. 2 the step of fine position determination, Fig. 3 the step of joining, and Fig. 4 an exemplary use case.

[0025] The Fig. Figures 1 to 3 show an exemplary device for carrying out the proposed method.

[0026] Two joining partners 1 are held in a clamping device 2, forming a joint 11. A joining device is arranged above the clamping device 2.

[0027] The joining device used is a laser welding device 3, which comprises a welding laser (not shown in detail) for generating a welding laser beam 32 and a welding optic 33 for aligning the welding laser beam 32, as shown in Fig. 3 is evident.

[0028] Furthermore, the laser welding device 3 includes a camera 4, which is designed to acquire topographic coarse data of relevant surface areas of the joining partners 1 and / or of the joining joint 11 formed by the joining partners 1, as shown in Fig. 1 is evident.

[0029] Furthermore, the laser welding device 3 includes a measuring scanning unit 5, which is designed to acquire topographical fine data by optical scanning of the relevant surface areas of the joining partners 1 and / or of the joining joint 11 formed by the joining partners 1 by a measuring beam 53 generated by a measuring beam unit 51 and directed by a deflecting mirror 52, as shown in Fig. 2 is evident.

[0030] Finally, the laser welding device 3 includes a computing and control unit 6, which is configured to determine position data by evaluating the coarse data and / or the fine data and to use the position data in process control, as shown in Fig. As can be seen in Figure 3, the processing and control unit 6 receives data from the camera 4 and the measuring and scanning unit 5 and performs data analysis. First, the data from camera 4 is analyzed to determine the position of the joining partners 1. However, if the image 41 captured by camera 4 is of insufficient quality, for example, because the material of the joining partners 1 reflected too much light and the image 41 is therefore overexposed, the joining partners 1 and the intervening joint 11 are additionally scanned by the measuring and scanning unit 5 to obtain height information, which is then supplied to the processing and control unit 6. Subsequently, the processing and control unit 6 performs a combined analysis of the coarse data from camera 4 and the fine data from the measuring and scanning unit 5.

[0031] How Fig. Figure 3 shows that the position data obtained in this way can subsequently be used in the process control of the laser welding. At the same time, the measuring beam 53 can be used for continuous quality monitoring during welding.

[0032] Fig. Figure 4 shows a realistic application scenario for the proposed method.

[0033] Four joining partners 1 are positioned forming three joining joints 11. In the upper part of the Fig. Figure 4 shows an overexposed image 41 taken by camera 4, from which the exact course of the joints 11 is not apparent. A measuring line 54 is drawn in image 41. If the arrangement of the joining partners 1 is scanned along this measuring line 54 by a measuring beam 53 (not shown here), information about the height profile of the arrangement is obtained, i.e., height measurements plotted against the path, which allows the welding positions 34 to be determined.

Claims

[1] Method for determining the position of components for a joining process in which at least two joining partners (1) are positioned relative to each other and / or relative to a joining tool, in particular a laser welding device (3), and subsequently joined, in particular welded, comprising the steps - Acquisition of topographic coarse data by camera-based image recognition of surface areas of the joining partners (1) relevant to the joining process and / or a joining joint (11) formed by the joining partners (1); - Assessment of the suitability of the topographic rough data as a basis for process control for the joining process, and, -- if the assessment is positive, determination of position data by evaluating the rough data and using it in process control, or, -- if the assessment is negative, - Acquisition of topographic fine data by optical scanning of the relevant surface areas of the joining partners (1) and / or the joining joint (11) by a measuring beam (53); - Determination of position data by evaluating the rough and fine data or by evaluating the fine data and using the position data in the process control of a joining process, characterized by , that the determination of the position data is iterative, by repeatedly acquiring and evaluating coarse topographic data and / or fine topographic data, and by continuously monitoring quality in a joining process following the position determination through optical scanning of the relevant surface areas of the joining partners (1) and / or the joining joint (11) by the measuring beam (53). [2] Method according to claim 1, characterized by, that the measuring beam (53) is generated by a measuring scanning unit (5) and that the acquisition of topographic fine data is carried out by means of optical coherence tomography OCT.

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