Laser joining device comprising laser triangulation sensor, laser joining method which can be carried out using said device, and use thereof in the production of batteries

Abstract

One aspect of the invention relates to a laser joining device (10) for joining workpieces (14, 14.1, 14.2; 18) at multiple joining points (22.1, 22.2, 22.3,..., 22.n), comprising a laser triangulation sensor (24) for determining the position of the joining points (22.1, 22.2, 22.3,..., 22.n) and a joining laser beam source (26) which emits a joining laser beam (28) onto a joining point (22.1, 22.2, 22.3,..., 22.n) through an emission region (30). The aim of the invention is to improve the laser joining device for a large-scale industrial production. This is achieved in that a measuring laser (46) of the laser triangulation sensor (24) is provided on a first side of the joining laser beam source (26) and emits a measuring laser beam (48) onto the workpiece (14, 14.1, 14.2) such that the measuring beam crosses an emission region (30), which is oriented so as to emit the joining laser beam (28) onto the first joining point (22.1), in order to determine the position of a second joining point (22.2) to be subsequently processed, said second joining point lying laterally from the emission region (30) on a second side opposite the first side. A photoreceiver (30) of the laser triangulation sensor (14) is provided on the second side of the joining laser source (26) and detects light projected onto the second joining point (22.2) by means of the measuring laser beam (48).

Description

Laser joining device with laser triangulation sensor, laser joining process that can be carried out with it and use in battery production The invention relates to a laser joining device for joining a workpiece to at least one other workpiece at multiple joining points in industrial large-scale production, in particular for joining battery cells with connection elements. The invention further relates to a battery unit manufacturing device comprising such a laser joining device. The invention further relates to a laser joining method for joining a workpiece to at least one other workpiece at multiple joining points in industrial large-scale production, in particular for joining battery cells with connection elements. The invention further relates to a manufacturing method for producing a battery unit using such a laser joining method. The invention further relates to a computer-implemented controller and a computer program for a laser joining device. For the technological background, please refer to the following literature:

[0001] EP 3 345 717 A1 [2] Wikipedia - Electro-optical distance measurement - retrieved on 22.02.2024 from https: / / de.wikipedia.org / w / index.php?title=Elektrooptische_Entfernungsme ssung&oldid=234403368 [3] Wikipedia - Optical coherence tomography - retrieved on 22.02.2024 from https: / / de.wikipedia.org / w / index.php?title=Optische_Kohärenztomographie &oldid=241491501 [4] Wikipedia - Line laser - retrieved on 22.02.2024 from https: / / de.wikipedia.org / w / index.php?title=Linienlaser&oldid=224274646 [5] Wikipedia - Light section - retrieved on 22.02.2024 from https: / / de.wikipedia.org / w / index.php?title=Lichtschnitt&oldid=231765993 [6] Website of Delvotec, accessed on 25.03.2024 from https: / / www.fkdelvotec.com / leistungen / training [7] Trumpf website, accessed on March 25, 2024, from https: / / www.trumpf.com / de_DE / produkte / laser / sensorik / bildverarbeitung- schneid-schweissanwendung / [8] Trumpf website, accessed on March 25, 2024, from https: / / www.trumpf.com / de_DE / produkte / laser / sensorik / 3d- merkmalserkennung / [9] Website of Micro-Epsilon, accessed on March 25, 2024, from https: / / www.micro-epsilon.de / 2d-3d-rnesstechnik / 3d-sensoren / scancontrol- 3d-laserscanner / Preferred embodiments of the invention relate to laser joining devices and laser joining methods and their application, in particular in the industrial large-scale production of components with electrical connection elements, such as in particular battery units. Industrial image processing systems are used for position tracking of laser welding systems, as described in [1], [6]-[8], for example. The task of the image processing system is to determine the position of the workpieces and to track the position of the clamping system and the laser welding beam to the target position. Some laser welding systems use 2D camera systems. This allows the position of the components to be controlled parallel to the optical beam path (off-axis) or using the optical beam path (on-axis) of the laser welding system. Furthermore, 3D position tracking using the OCT system from Trumpf is conceivable. Reference [6] shows a 2D off-axis solution. The 2D camera and lighting require the system to be shut down. The camera then captures the image and detects the position of the joint. Disadvantages of the 2D off-axis system are that the laser head must remain stationary to generate the image, so that the measurement for tracking leads to a loss of cycle time. Furthermore, it is very difficult to obtain stable features on the sheet metal components. Complex and large-scale illumination technology is necessary, but poor detection performance is to be expected. Reference [7] shows an on-axis solution. The camera is mounted on the side of the laser welding head and uses the same optical beam path as the high-power laser (joining laser beam source). Some disadvantages of the 2D on-axis system are that lasering is not possible during image acquisition; this results in a reduction in the processing time of the high-power laser. Furthermore, it is very difficult to create stable features on the sheet metal components. Complex and large-scale lighting technology is required, and poor detection performance is to be expected. Reference [8] shows a 3D system on a laser welding scanner using an OCT system. The system consists of a 2D on-axis camera + distance sensor (optical coherence tomography = OCT). The distance measurement is also performed on-axis. The process is as follows: The laser welding head is positioned over the component to be welded. A cyclic distance measurement generates a 3D height profile. This profile can then be used to track the position of the weld seam. The distance sensor must be moved to the correct position using a second galvanometer scanner and is therefore complex, technically expensive, and time-consuming to control. Furthermore, position determination is part of the laser's main processing time. One of the disadvantages of a 3D-based OCT system is that OCT only offers point-based distance measurement; an additional galvanometer scanner is required to move the measuring point over the component.Many components are required, which is expensive and very complex in terms of control technology. Furthermore, the point laser's "field of view" is limited to a very limited area around the focal point of the high-power laser. Furthermore, the scanning frequency of the OCT sensor, for example, is limited to just 250 kHz. References [5] and [9] describe a light section sensor, also called a laser triangulation sensor or laser scanner. The known light section sensors consist of a line laser and a camera module. Both components are housed in a common housing. The image of the line laser on a workpiece is captured by a camera. When the sensor is moved relative to the component, a 3D image can be created from each profile line. The object of the invention is to improve a laser joining device with the features of the preamble of claim 1 for industrial large-scale production. To achieve this object, the invention provides a laser joining device according to claim 1. A battery unit manufacturing device with such a laser joining device, a laser joining method, a battery unit manufacturing method as well as a control system and a computer program therefor are the subject of the further independent claims. Advantageous embodiments are the subject of the subclaims. According to a first aspect thereof, the invention provides a laser joining device for joining a workpiece to at least one other workpiece at multiple joining points in industrial mass production, comprising a laser triangulation sensor configured to determine the position of joining points, and a joining laser beam source configured to emit a joining laser beam through an emission region onto a joining point whose position has been determined by the laser triangulation sensor. The laser triangulation sensor comprises a measuring laser for emitting a measuring laser beam onto the workpiece and a photoreceiver for receiving light from the measuring laser beam on the workpiece to determine the position of the workpiece.According to the invention, the measuring laser is arranged on a first side of the joining laser beam source and is designed to radiate the measuring laser beam onto the workpiece in such a way that it crosses the radiation region aligned for radiating the joining laser beam onto a first joining point or still aligned onto an intermediate region between previously machined joining points, into a region of a second joining point to be subsequently machined, which region lies on a second side opposite the first side laterally of the radiation region. The photoreceiver is arranged on the second side of the joining laser source and is designed to receive the light projected onto the workpiece at the second joining point by the measuring laser beam in order to determine the position of the second joining point for subsequent processing. In some embodiments, the measuring laser beam can thus cross the radiation area of the joining laser beam that is still aligned with a previously processed joint. The measuring laser beam can also already be aligned with the next joint even if the joining laser is not yet aligned with the joint currently being processed. The emission range of the joining laser beam describes an area within which the joining laser beam can be emitted by the joining laser beam source, depending on its orientation. The emission range is particularly conical, with the tip of the cone corresponding to the exit point of the joining laser beam from the joining laser beam source. The joining laser beam is particularly designed as a substantially point-shaped laser and thus has a particularly linear contour. The laser triangulation sensor is, in particular, a light section sensor. In some embodiments, the measuring laser is a line laser. A light section sensor enables a large field of view and high resolution within this field of view. Furthermore, the light section sensor enables data acquisition during movement. This means that the light section sensor enables on-the-fly data acquisition. As a result, it is not necessary to stop the laser joining device for position determination using the laser triangulation sensor. In other words, the laser triangulation sensor, in particular designed as a light section sensor, enables position determination while the laser joining device is moving, thus shortening the cycle times for the laser joining device. A measuring laser designed as a line laser is particularly suitable for the light section method because it enables on-the-fly data acquisition. It should be noted that the laser triangulation sensor described above and below, in particular according to the invention, differs from known light-section sensors in that the measuring laser and the photoreceiver are not arranged in a common housing, but can be provided separately from one another on the laser joining device. In other words, the term "laser triangulation sensor" according to the underlying inventive concept refers to the combination of the measuring laser with the photoreceiver, whereby the measuring laser and the photoreceiver can be arranged separately, i.e. independently of one another, in particular at different positions, on the laser joining device. In some embodiments, the photoreceiver is embodied as a camera, in particular a 2D camera. In some embodiments, a camera system comprising the camera and an image evaluation unit is provided. The combination of the camera, in particular the 2D camera, as a photoreceiver and a line laser as a measuring laser enables 3D data acquisition. As a result, the laser joining device is preferably embodied with an image evaluation system with which the position of a joining point to be subsequently processed can be determined, in particular three-dimensionally. In embodiments of the invention, such a position determination of a subsequent joining point can take place simultaneously or overlapping, in particular at least partially overlapping, with the processing of a previous joining point. In this way, a cycle time loss due to the position determination by the measuring laser can be reduced or even eliminated. In some embodiments, the joining laser beam source comprises a laser scanner configured to direct the joining laser beam to the position of the joining point to be machined, as determined by the laser triangulation sensor. In some embodiments, the laser joining device is configured such that the joining laser beam or at least the emission region and the measuring laser beam intersect during operation. In some embodiments, the laser joining device has a relative movement device for relatively moving a laser head comprising the joining laser beam source and the laser triangulation sensor relative to the workpiece. In some embodiments, the relative movement device is configured to move the laser head along a movement path relative to the workpiece. In some embodiments, the photoreceiver is arranged on the side of the laser head facing forward in the direction of movement, and the measuring laser is arranged on the side of the laser head facing rearward relative to the direction of movement and is configured to guide the measuring laser beam forward in front of the emission region through the emission region arranged between the photoreceiver and the measuring laser. In some embodiments, the relative movement device is configured to track or adjust the relative position of the laser head and the workpiece according to the position determination made by the laser triangulation sensor in the direction of movement upstream of the emission area. It can therefore be said that the relative movement device is configured to adjust the relative position of the laser head and the workpiece according to the position determined by the laser triangulation sensor. In some embodiments, the relative movement device is designed to move the laser head relative to the workpiece in order to move the emission region from the first joining point to the second joining point. In other words, the relative movement device is designed to move the laser head accordingly such that the emission region of the joining laser source is moved relative to the workpiece from the first joining point to the second joining point. In particular, the first joining point can be an already joined joining point, and the second joining point can be a joint still to be joined, the position of which was determined in particular by the laser triangulation sensor, while the first joint was joined by means of the joining laser beam emitted by the joining laser beam source. In some embodiments, the laser joining device has a clamping device with a plurality of clamping units that can be moved in their position for locally clamping the workpiece to be joined to the at least one other workpiece at different joining points. In some embodiments, the clamping device is designed to clamp the workpiece to be joined and the further workpiece or at least one of the further workpieces at the first joining point during joining under the influence of the joining laser beam by means of a first clamping unit, and during this joining process to position a second clamping unit for clamping the workpiece to be joined to the further workpiece or to another further workpiece depending on the position determination of the second joining point at the second joining point. The workpiece referred to in this context as the "workpiece to be joined" can always be the same during a processing process of the laser joining device, or it can involve different workpieces.For example, it is conceivable that battery cells that are to be connected to a battery module or battery pack via cell connectors are connected to one another via one or more cell connectors, wherein the at least one cell connector (or correspondingly the plurality of cell connectors) can be assumed to be the "workpiece to be joined". In this case, the at least one battery cell is to be assumed to be the "at least one further workpiece" and correspondingly several battery cells are to be assumed to be the "further workpieces". Furthermore, in this example, it is conceivable that the at least one cell connector (or correspondingly the plurality of cell connectors) as the workpiece to be joined is to be connected not only to battery cells, but also to at least one so-called summation current connector, which is generally arranged at the ends of the battery module or battery pack. This means that for the application example of manufacturing a battery module or a battery pack (also: battery cluster), the component referred to here as the “at least one further workpiece” can be designed as a battery cell or as a summation current connector. According to a further aspect, the invention provides a battery unit manufacturing device for manufacturing a battery unit having a plurality of electrically connected battery cells, comprising a Laser joining device according to one of the preceding embodiments for joining battery cells with connection elements. According to a further aspect, the invention provides a laser joining method for joining a workpiece to at least one further workpiece at a plurality of joining points in industrial large-scale production, comprising the steps: a) determining a position of a first joining point by means of laser triangulation; b) joining the workpiece to the at least one further workpiece by emitting a joining laser beam from a joining laser beam source through an emission region onto the first joining point as a function of its position determination in step a); c) determining a position of a second joining point and d) joining the workpiece to the at least one further workpiece at the second joining point by emitting the joining laser beam from the joining laser beam source onto the second joining point through the emission region as a function of its position determination in step c). According to the invention, steps b) and c) are carried out simultaneously or overlapping, in particular at least partially overlapping, wherein step c) comprises the steps c1) emitting a measuring laser beam by means of a measuring laser which is arranged on a side of the joining laser beam source facing away from the second joining point, so that the measuring laser beam crosses the joining laser beam or at least the emission region and strikes the workpiece in the region of the second joining point and c2) taking an image of the light of the measuring laser beam striking the second joint and evaluating the image to determine the position of the second joint. In some embodiments, the laser joining method comprises the step: e) Relative positioning of the joining laser beam source and the workpiece depending on the position determination by the laser triangulation. In some embodiments, the laser joining method comprises the step: f) tracking the joining laser beam source between steps b) and d) depending on step c). This means that after completion of the joining process for joining the workpiece to the at least one further workpiece at the first joining point, the joining laser beam source is moved in accordance with the position determination carried out in step c) in such a way that the joining laser beam source is positioned in such a way that in step d) the workpiece at the second joining point is joined to the at least one further workpiece by emitting the joining laser beam. In some embodiments, the laser joining method comprises the step: g) locally clamping the workpiece to the at least one further workpiece at the first joining point during step b) by means of a first clamping unit. In some embodiments, the laser joining method comprises the step: h) during or overlapping, in particular at least partially overlapping, step b), positioning a second clamping unit at the second joining point as a function of step c) in order to clamp the workpiece to the at least one further workpiece for carrying out step d). According to a further aspect, the invention provides a manufacturing method for producing a battery unit comprising a plurality of connecting elements interconnected battery cells, wherein the manufacturing method comprises carrying out the laser joining method according to one of the preceding embodiments in order to join the respective battery cell to at least one connection element. According to a further aspect, the invention provides a computer-implemented controller, in particular with a processor and memory, for a laser joining device according to one of the preceding embodiments. The controller is configured to cause the laser joining device to perform the laser joining method according to one of the preceding embodiments. According to a further aspect, the invention provides a computer program containing instructions which cause a laser joining device according to one of the preceding embodiments to carry out the laser joining method according to one of the preceding embodiments. The laser joining method according to one or more of the aforementioned method-related embodiments can be carried out in particular by the laser joining device according to one or more of the aforementioned embodiments. In particular, automatic execution at high cycle speeds for large-scale production is provided. Some embodiments relate to a laser triangulation system for 3D on-the-fly position tracking in laser welding applications. The laser triangulation system is particularly advantageous in laser bonders for bonding cell contact systems (CCS), which are used to electrically contact battery cells of a battery unit. An advantageous field of application is electromobility. In particular, embodiments of the invention can be used in the production of battery units for electric vehicles, in particular BEVs or PHEVs or full hybrid vehicles. One of the keys to more cost-effective electric vehicles is improving large-scale production so that more battery units can be produced in a shorter time can be manufactured. Some embodiments of the invention enable faster production. Some embodiments of the invention enable a more compact design. Some embodiments eliminate at least one, several, or all of the disadvantages mentioned above with regard to the prior art. In some embodiments, precise acquisition of 3D information in the area of a joint to be subsequently processed, for example, for a subsequent clamping process for a subsequent joining, is already possible when the joining laser beam source is aligned to a previous joining point. Precise, particularly exact, height determination allows the clamping device to be positioned more quickly (cycle time reduction). Furthermore, the welding geometry can be adjusted vertically, thereby improving the joint quality. Possible clamping devices with clamping units are known, for example, from the literature reference [1]. Some embodiments provide a high-resolution 3D system that enables stable detection performance regardless of fluctuations in the cell interconnect material (e.g., due to changes in rolling direction, surface treatment by grinding or embossing, laser-based cleaning processes). In some embodiments, a 2D camera is used as the camera, which, when combined with a line laser and image processing, becomes a 3D system. One possible application of the laser joining device and the laser joining process is in the area of assembly machines for the production of battery packs based on round cells (cell-to-pack; example of a battery unit manufacturing device). Some embodiments fulfill one, several or all of the following requirements placed on a laser joining device in industrial large-scale production, for example in battery unit production: • Maximum permissible detection error by the camera system <= +-0.2 mm • Travel speed ~ 100 mm / s • Evaluation time < 300 ms • On-the-fly processing, i.e. simultaneous image acquisition / image processing / laser process • Scanning area width > 160 mm • The required acquisition speed of the 3D points results from the traversing speed and the required accuracy, e.g. as follows: o Area that must be scanned per second, e.g. 100 mm x 160 mm o Necessary resolution to achieve the required accuracy, e.g. <= 75 pm (rule of thumb: tolerance / lateral resolution >5) o Measuring points per second, e.g. (100 mm / 0.075 mm) * (160 mm / 0.075 mm) = 1333 * 2133 = 2,843,733 measuring points / second Particularly due to component variation and the requirement for on-the-fly processing, position tracking based on 2D images is not sufficiently reliable. Therefore, using a 2D on-axis or off-axis camera alone is not effective, as 3D data is required to achieve sufficient process reliability. While an OCT system provides 3D data, its scanning frequency of 250,000 measurement points per second is not high enough. A line-cut sensor provides the necessary data rate, but the design of previously known line-cut sensors is too large to be able to integrate them into the space available on the laser head, which is particularly small. In preferred embodiments of the invention, however, a laser triangulation sensor is divided into a measuring laser (in particular a line laser) and a photodetector (in particular a camera module). Due to the possibility of arranging the measuring laser and the photodetector independently of each other, and the possibility of crossing the welding laser with the measuring laser (e.g., line laser) of the laser triangulation sensor, the measuring laser can be positioned in a direction of movement of the laser head on one side of the welding laser. (joining laser) and the photodetector on the other side of the welding laser (joining laser), with the measuring laser being positioned such that the measuring laser beam runs diagonally from one side of the welding laser to the other side of the welding laser and strikes the workpiece there. This allows multiple use of the installation space for the radiation area of the welding laser, resulting in a very compact design. Although this method can lead to a certain distortion of the 3D image compared to previously known laser triangulation sensors, this can be compensated for, for example, by software compensation. An exemplary embodiment is explained in more detail below with reference to the attached drawings. They show: Fig. 1 is a plan view of a battery unit with a plurality of battery cells to be contacted by means of connection elements in a battery unit manufacturing device; Fig. 2 is a schematic plan view of a laser joining device for joining the connecting elements to the battery cells; and Fig. 3 is a schematic side view of a portion of the laser joining device; and Fig. 4 is a schematic side view as in Fig. 3 in a modified embodiment. In the following, an embodiment of a laser joining device 10 for joining a workpiece to at least one other workpiece at several joining points in industrial large-scale production is explained with reference to the drawings. The laser joining device 10 can be used for joining different workpieces. In the illustrated embodiment, the laser joining device 10 is used in a battery unit manufacturing device 12 to connect connecting elements 14, 14.1, 14.2 (example of workpiece) for contacting battery cells 18 with the battery cells 18 (example of further workpiece). Fig. 1 shows a top view of a battery unit 20 with multiple battery cells 18 in the battery unit manufacturing device 12, wherein the battery cell contacts are to be connected to connection elements 14.1, 14.2. The connection is effected by means of laser bonding or laser welding at different joining points 22.1, 22.2, 22.3, ..., 22.n. In this case, a large number of joining points 22.1, 22.2, 22.3, ..., 22.n must be processed during battery unit production. The laser welding device 10 is used for laser welding, an exemplary embodiment of which is shown in Figs. 2 and 3. According to Figures 2 to 4, the laser welding device 10 comprises a laser triangulation sensor 24 which is designed to determine the position of joining points 22.1, 22.2, 22.3, ..., 22.n, and a joining laser beam source 26 which is designed to emit a joining laser beam 28 through an emission region 30 onto a joining point 22.1, 22.n, the position of which has been determined by the laser triangulation sensor 24. The joining laser beam source 26 comprises, for example, a laser welding scanner arranged on a laser head 32. The laser head 32 is movable relative to the workpieces to be joined—e.g., connecting element 14, 14.1, 14.2 and battery cells 18—by means of a relative movement device 34 in order to move the emission region 30 of the joining laser beam source 26 from a previous joining point (e.g., first joining point 22.1) to a subsequent joining point (e.g., second joining point 22.2). An image processing system 36 is used for position tracking. The image processing system 36 determines the position of the workpieces 14, 18 and sets the irradiation area 30 to the desired position. In some embodiments, a clamping device (not shown, see, for example, [1]) is also set to a desired position. The image processing system 36 includes the laser triangulation sensor 24 with image evaluation unit 38. The image evaluation unit 38 can be part of a computer-implemented control system 40 with Processor and memory in which corresponding computer programs are stored. Fig. 1 shows a connection of round battery cells - example of battery cell 18 - to a cell contact system 42 with first and second connection elements 14, 14.1, 14.2. Positional tracking of a weld seam 44 is particularly necessary due to a high manufacturing tolerance of the cell contact system 42 and the size of the battery unit (battery pack, for example, 1500 x 2200 mm). 2 ). A typical accuracy requirement is +- 0.2 mm for the position of the weld seam 44 relative to the round battery cell 18 or the cell contact system 42. According to Fig. 2 and 3, to which reference is now again made, the laser triangulation sensor 24 has a measuring laser 46 for emitting a measuring laser beam 48 onto the workpiece - e.g. connecting element 14, 14.1, 14.2 - and a photoreceiver 50 for receiving light of the measuring laser beam 48 on the workpiece in order to determine the position of the workpiece. The measuring laser 46 is arranged on a first side (left in Figs. 2 and 3) of the joining laser beam source 26. The measuring laser 46 is configured to radiate the measuring laser beam 48 onto the workpiece in such a way that it crosses the radiation region 30, which is aligned for radiating the joining laser beam onto a first joining point 22.1, into a region of a second joining point 22.2 to be subsequently machined. The region of the second joining point to be subsequently machined is located on a second side opposite the first side (right in Figs. 2 and 3) to the side of the radiation region 30. The measuring laser 46 can thus already radiate the measuring laser beam 48 onto the area of the second joint 22.2 while the joining laser beam is radiating onto the first joint 22.1. The measuring laser beam 48 can also be radiated when joining is not in progress. The photoreceiver 50 is arranged on the second side (right of the emission area 30 in Fig. 2 and 3) of the joining laser beam source 26 and is for receiving the formed on the workpiece at the second joint 22.2 by the measuring laser beam 48 projected light in order to determine the position of the second joint 22.2 for subsequent processing. In the illustrated embodiment, the measuring laser 46 is a line laser. In preferred embodiments, the photoreceiver 50 is configured as a (2D) camera 52 of a camera system comprising the camera 52 and the image evaluation unit 38. In some embodiments, the joining laser beam source 26 and the laser triangulation sensor 24 are formed on the laser head 32, wherein the measuring laser 46 of the laser triangulation sensor 24 and the photoreceiver 50 of the laser triangulation sensor 24 are arranged on opposite sides laterally offset from the emission region 30 of the joining laser beam source 26 on the laser head 32. In Figs. 2 and 3, a laser welding scanner is shown as an example of the joining laser beam source 26. The laser triangulation sensor 24 with the measuring laser 46 designed as a line laser and the photoreceiver 50 designed as a camera unit is used to detect the components. The laser beam from the laser welding scanner and the laser beam from the line laser intersect. The image of the line laser on the surface of the workpiece 14 is captured by the camera unit during the crossing, creating a 3D image. In some embodiments, the relative movement device 34 is configured to move the laser head 32 along a movement path. In some embodiments, the movement path is selected depending on the position determination by the laser triangulation sensor 24. In some embodiments, the photoreceiver 50 is arranged on the side of the laser head 32 facing forward in the direction of movement, and the measuring laser 46 is arranged on the side of the laser head 32 facing backward relative to the direction of movement. The measuring laser 46 is configured to To guide the measuring laser beam 48 through the emission region 30 forward in front of the emission region 30. The relative movement device 34 is designed to track the relative position of the laser head 32 and the workpiece 14, 14.1, 14.2 in accordance with the position determination carried out in the direction of movement in front of the emission region 30 by the laser triangulation sensor 24. Thus, by moving the laser head 32 by the relative movement device 34 and / or by moving the joining laser beam by the laser scanner, the emission region 30 can be moved from the first to the second joining point 22.1, 22.2. The clamping device provided in some embodiments, not shown in detail in the figures, has several clamping units which are movable in their position for locally clamping the workpiece 14.1, 14.2, 14 to be joined to the at least one further workpiece 18 at different joining points 22.1, 22.2, 22.3, ..., 22.n. The clamping device is designed to clamp the workpiece 14 and the further workpiece 18 or at least one of the further workpieces at the first joining point 22.1 during joining under the influence of the joining laser beam 28 by means of a first clamping unit and, during this joining process, to position a second clamping unit for clamping the workpiece 14 to the further workpiece or to another further workpiece depending on the position determination of the second joining point at the second joining point 22.2. Possible embodiments of the clamping device are known to the person skilled in the art from [1], wherein modifications and adaptations are familiar to the person skilled in the art. Fig. 4 shows a representation as in Fig. 3, wherein the camera 52 is angled and not as in Fig. 3 perpendicular to the joint to be subsequently processed 22.2, but rather aims obliquely at this joint 22.2. In some embodiments, an adjustment device 54 is thus provided for adjusting the camera angle. In the intended operation of the laser joining device 10, which is automatically controlled by the controller 40 - in particular a corresponding computer program loaded therein - during the production of a Battery unit 20 in industrial large-scale production, a laser joining process is carried out with the following steps: a) determining the position of the first joining point 22.1 by means of laser triangulation; b) joining the workpiece 14 to the at least one further workpiece 18 by emitting the joining laser beam 28 from the joining laser beam source 26 through the emission region 30 onto the first joining point 22.1 as a function of its position determination in step a); c) determining the position of the second joining point 22.2 and d) joining the workpiece 14 at the second joining point 22.2 to the at least one further workpiece 18 by emitting the joining laser beam 28 from the joining laser beam source 26 onto the second joining point 22.2 depending on their position determination in step c); wherein steps b) and c) are carried out simultaneously or overlapping, and wherein step c) comprises the steps c1) emitting the measuring laser beam 48 by means of the measuring laser 46, which is arranged on the side of the joining laser beam source 26 facing away from the second joining point 22.2, so that the measuring laser beam 48 crosses the joining laser beam 28 or at least the emission region 30 and strikes the workpiece 14 in the region of the second joining point 22.2 and c2) recording an image of the light of the measuring laser beam 48 striking the second joining point 22.2 and image analysis to determine the position of the second joining point 22.2. In some embodiments, the laser joining method comprises the further step: e) Relative positioning of the joining laser beam source 26 and the workpiece 14 depending on the position determination by the laser triangulation. In some embodiments, the laser joining method comprises the further step: f) tracking the joining laser beam source between steps b) and d) depending on step c). In some embodiments, the laser joining method comprises the further step: g) locally clamping the workpiece 14 to the at least one further workpiece 18 at the first joining point 22.1 during step b) by means of the first clamping unit. In some embodiments, the laser joining method comprises the further step: h) during or overlapping with step b), positioning the second clamping unit at the second joining point 22.2 as a function of step c) in order to clamp the workpiece 14 to the at least one further workpiece 18 for carrying out step d). One aspect of the invention relates to a laser joining device (10) for joining workpieces (14, 14.1, 14.2; 18) at a plurality of joining points (22.1, 22.2, 22.3, ... , 22.n) with a laser triangulation sensor (24) for determining the position of the joining points (22.1, 22.2, 22.3, ... , 22.n) and a joining laser beam source (26) which emits a joining laser beam (28) through an emission region (30) onto a joining point (22.1, 22.2, 22.3, ... , 22.n). To improve the laser joining device for industrial large-scale production, it is proposed that a measuring laser (46) of the laser triangulation sensor (24) is arranged on a first side of the joining laser beam source (26) and emits a measuring laser beam (48) onto the workpiece (14, 14.1, 14.2) in such a way that the measuring beam crosses an emission region (30) aligned for emitting the joining laser beam (28) onto a first joining point (22.1) in order to determine the position of a second joining point (22.2), which lies on a second side opposite the first side and laterally from the emission region (30). A photoreceiver (30) of the laser triangulation sensor (14) is arranged on the second side of the joining laser source (26) and detects light projected by the measuring laser beam (48) at the second joining point (22.2). In some embodiments, based on an image analysis of the Line laser projected light with a 2D camera by laser triangulation 3D camera system, which determines the position for the high-power laser on-the-fly. Compared to the 2D concept explained above, a more compact design is achievable with improved recognition performance thanks to 3D data (sheet metal parts are only partially recognizable in two dimensions). The 3D data results in a cycle time advantage, since target heights for the blank holder (e.g., a clamping unit) are already known in advance. List of reference symbols: 10 Laser joining device 12 Battery unit manufacturing device 14 connecting element 14.1 first connection element 14.2 second connection element 18 battery cells (e.g. round battery cells) 20 Battery unit (e.g. battery pack) 22.1 first joint 22.2 second joint 22.3 third joint 22. n nth joint 24 laser triangulation sensor 26 Joining laser beam source 28 joining laser beam 30 radiation area 32 laser head 34 Relative motion device 36 Image processing system 38 Evaluation unit 40 Control 42 Cell contact system 44 Weld seam (or weld spot) 46 measuring lasers 48 measuring laser beam 50 photo receivers 52 Camera 54 Adjustment device for adjusting the camera angle

Claims

Claims:

1. Laser joining device (10) for joining a workpiece (14, 14.1, 14.2) at several joining points (22.1, 22.2, 22.3, ... , 22.n) in industrial large-scale production to at least one further workpiece (18), comprising a laser triangulation sensor (24) which is designed to determine the position of joining points (22.1, 22.2, 22.3, ... , 22.n), and a joining laser beam source (26) which is designed to emit a joining laser beam (28) through an emission region (30) onto a joining point (22.1, 22.2, 22.3, ... , 22.n), the position of which has been determined by the laser triangulation sensor (24), wherein the laser triangulation sensor (24) a measuring laser (46) for emitting a measuring laser beam (48) onto the workpiece (14, 14.1, 14.2) and a photoreceiver (30) for receiving light of the measuring laser beam (48) on the workpiece (14, 14.1, 14.2) in order to determine the position of the workpiece (14, 14.2, 14.2), characterized in that the measuring laser (46) is arranged on a first side of the joining laser beam source (26) and is designed to radiate the measuring laser beam (48) onto the workpiece (14, 14.1, 14.2) in such a way that it crosses the radiation region (30) aligned for radiating the joining laser beam (28) onto a first joining point (22.1) or onto intermediate regions between joining points (22.1), into a region of a second joining point (22.2) to be subsequently machined, which region lies on a second side opposite the first side laterally from the radiation region (30), and wherein the photoreceiver (30) is arranged on the second side of the joining laser source (26) and is designed to receive the photodetector (30) aligned onto the workpiece (14, 14.1, 14.2) at the second joining point (22.2). light projected by the measuring laser beam (48) is designed to determine the position of the second joining point (22.2) for subsequent processing.

2. Laser joining device (10) according to claim 1, characterized in that the measuring laser (46) is a line laser.

3. Laser joining device (10) according to one of the preceding claims, characterized in that the photoreceiver (30) is a camera (52) of a camera system which is provided with an image evaluation unit (38).

4. Laser joining device (10) according to one of the preceding claims, characterized in that the joining laser beam source (26) has a laser scanner which is designed to direct the joining laser beam (28) onto the position of the joining point (22.1, 22.2, 22.3, ..., 22.n) to be machined, which position is determined by the laser triangulation sensor (24).

5. Laser joining device (10) according to one of the preceding claims, characterized in that it is arranged such that the joining laser beam (28) or at least the emission region (30) and the measuring laser beam (48) intersect during operation of the measuring laser beam.

6. Laser joining device (10) according to one of the preceding claims, characterized by a relative movement device (34) for the relative movement of a laser head (32) comprising the joining laser beam source (26) and the laser triangulation sensor (24) relative to the workpiece (14, 14.1, 14.2).

7. Laser joining device (10) according to claim 6, characterized in that the relative movement device (34) is designed to move the laser head (32) along a movement path relative to the workpiece (14, 14.1, 14.2), that the photoreceiver (50) is arranged on the side of the laser head (32) directed forward in the direction of movement and the measuring laser (46) is arranged on the side of the laser head (32) directed backward relative to the direction of movement is arranged and is designed to guide the measuring laser beam (48) through the emission region (30) forwards in front of the emission region (30), and that the relative movement device (34) is designed to track the relative position of the laser head (32) and the workpiece (14, 14.1, 14.2) in accordance with the position determination carried out in the direction of movement in front of the emission region (30) by the laser triangulation sensor (24).

8. Laser joining device (10) according to claim 6 or 7, characterized in that the relative movement device (34) is designed to move the laser head (32) for moving the radiation region (30) from the first joining point (22.1) to the second joining point (22.2) relative to the workpiece (14, 14.1, 14.2).

9. Laser joining device (10) according to one of the preceding claims, characterized by a clamping device with several clamping units which can be moved in their position for locally clamping the workpiece (14, 14.1, 14.2) to be joined to the at least one further workpiece (18) at different joining points (22.1, 22.2, 22.3), wherein the clamping device is designed to clamp the workpiece (14, 14.1, 14.2) and the further workpiece (18) or at least one of the further workpieces (18) at the first joining point (22.1) during joining under the action of the joining laser beam (28) by means of a first clamping unit and, during this joining process, a second clamping unit for clamping the workpiece (14, 14.1, 14.2) to the further workpiece (18) or to another further workpiece (18) depending on the position determination of the second Joint to be positioned at the second joint (22.2).

10. Battery unit manufacturing device (12) for manufacturing a battery unit (20) having a plurality of electrically interconnected battery cells (18), comprising a laser joining device (10) according to one of the preceding claims for joining battery cells (18) with connection elements (14, 14.1, 14.2).

11. Laser joining method for joining a workpiece (14, 14.1, 14.2) at a plurality of joining points (22.1, 22.2, 22.3, ..., 22.n) in industrial large-scale production to at least one further workpiece (18), comprising a) determining a position of a first joining point (22.1) by means of laser triangulation; b) joining the workpiece (14, 14.1, 14.2) to the at least one further workpiece (18) by emitting a joining laser beam (28) from a joining laser beam source (26) through an emission region (30) onto the first joining point (22.1) as a function of its position determination in step a); c) determining a position of a second joining point (22.2) and d) joining the workpiece (14, 14.1, 14.2) at the second joining point (22.2) to the at least one further workpiece (18) by radiating the joining laser beam (28) from the joining laser beam source (26) onto the second joining point (22.2) depending on their position determination in step c); characterized in that steps b) and c) are carried out simultaneously or overlapping, wherein step c) comprises the steps c1) emitting a measuring laser beam (48) by means of a measuring laser (46) which is arranged on a side of the joining laser beam source (26) facing away from the second joining point (22.2), so that the measuring laser beam (48) crosses the joining laser beam (28) or at least the emission region (30) and strikes the workpiece (14, 14.1, 14.2) in the region of the second joining point (22.2), and c2) recording an image of the light of the measuring laser beam (48) striking the second joining point (22.2) and image analysis to determine the position of the second joining point (22.2).

12. Laser joining method according to claim 11, comprising at least one or more of the steps: e) relative positioning of the joining laser beam source (26) and the workpiece (14, 14.1, 14.2) as a function of the position determination by the laser triangulation; f) tracking the joining laser beam source (26) between steps b) and d) as a function of step c); g) locally clamping the workpiece (14, 14.1, 14.2) to the at least one further workpiece (18) at the first joining point (22.1) during step b) by means of a first clamping unit; h) positioning a second clamping unit at the second joining point (22.2) as a function of step c) during or overlapping with step b) in order to clamp the workpiece (14, 14.1, 14.2) to the at least one further workpiece (18) for carrying out step d).

13. A manufacturing method for producing a battery unit comprising a plurality of battery cells (18) interconnected by means of connecting elements (14, 14.1, 14.2), wherein the manufacturing method comprises carrying out the laser joining method according to one of claims 11 or 12 in order to join the respective battery cell (18) to at least one connecting element (14, 14.1, 14.2).

14. Computer-implemented control (40) for a laser joining device (10) according to one of claims 1 to 9, characterized in that the control (40) is configured to cause the laser joining device (10) to carry out the laser joining method according to one of claims 11 or 12.

15. A computer program containing instructions which cause a laser joining device (10) according to one of claims 1 to 9 to carry out the laser joining method according to one of claims 11 or 12.

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