Hold-down system for joint pairs in closely spaced integral joining operations, and use of the hold-down system

Abstract

The present invention relates to a hold-down system (10) having high functional integration for joint pairs (35) in closely spaced integral joining operations, in particular welding operations. The hold-down system comprises at least one clamping element (15), at least one actuator (17) for controllably holding down the joint pair (35) by means of the at least one clamping element (15), at least one hold-down mask (19) connected to the at least one clamping element (15), and at least one suction channel (20) integrated into the at least one clamping element (15). The at least one clamping element (15) performs the hold-down operation force- and / or travel-controllably, and surrounding atmosphere (29) is suctioned into the suction channel (20) via a process region (27) in the hold-down mask (19). The invention also relates to the use of the hold-down system (10) according to the invention.

Description

[0001] Hold-down system for joining pairs in close-lying material-bonded joining processes and its use

[0002] The present invention relates to a hold-down system with a high degree of functional integration for joining pairs in closely spaced, material-to-material joining processes, in particular welding processes. It comprises at least one clamping element, at least one actuator for controllably holding down the joining pair by means of the at least one clamping element, at least one hold-down mask connected to the at least one clamping element, and at least one extraction channel integrated into the at least one clamping element. The hold-down is operated by means of the at least one clamping element in a force- and / or displacement-controllable manner, and a surrounding atmosphere is extracted into the extraction channel via a process area in the hold-down mask. The invention also relates to the use of the hold-down system according to the invention.

[0003] State of the art

[0004] Various devices and methods for the material-to-material joining of joining pairs are known in the literature, including the laser welding of battery cell connectors. To ensure the quality of the joining processes, the joining partner must be held down and thus clamped onto the joint. Complete masks with or without over-springs are typically used for this purpose to clamp the connectors to the cells. However, with increasing material thicknesses and the resulting necessary hold-down forces, as well as the increasing number of rows per module and the one-sided position of both poles, this type of clamping is generally no longer usable. Likewise, high cell height tolerances have a negative impact on the homogeneous distribution of clamping forces. Clamping all joints of a system simultaneously can lead to very high forces, which are detrimental to the system technology and the workpiece (e.g., the battery cell).Therefore, individual hold-down systems are being developed to hold down the cell connectors of each cell individually. However, this requires constant repositioning of the hold-down devices, which increases idle time. Parallelization using hold-down devices that can be individually positioned in XYZ directions is possible, but leads to significant challenges in terms of coordination, kinematics, and vibration damping. Common to all systems is the need to minimize wear on the hold-down device and emission agglomerations in order to maximize tool life. This often leads to hold-down geometries that do not allow adjacent cells to be clamped simultaneously.

[0005] DE 10 2021 001 676 A1 discloses a welding device for use in a laser welding process. The welding device has a first surface facing a laser beam optics, a second surface facing away from the laser beam optics, at least one welding recess, and at least one gas flow channel extending at least partially within an interior of the welding device. Furthermore, the welding recess penetrates the welding device between the first surface and the second surface, with the gas flow channel opening into the welding recess.

[0006] DE 10 2020 006 655 A1 also relates to a welding device for use in a laser welding process, wherein the welding device has a first surface facing a laser beam source, a second surface facing away from the laser beam source, at least one welding recess, an air duct, and at least one extraction duct. The at least one welding recess penetrates the welding device between the first surface and the second surface, the air duct intersects the at least one welding recess in a cutting area, and the at least one extraction duct leads away from the cutting area.

[0007] The invention described here addresses these challenges and demonstrates a way to optimize the hold-down tool life, improve welding quality, and facilitate the modular parallelization of many closely spaced hold-down functions. Disclosure of the Invention

[0008] According to the invention, a hold-down system with a high degree of functional integration is proposed for joining pairs in closely spaced, material-to-material joining processes, in particular welding processes. This system comprises at least one clamping element, at least one actuator for the controllable hold-down of the joining pair by means of the at least one clamping element, at least one hold-down mask connected to the at least one clamping element, and at least one extraction channel integrated into the at least one clamping element. The hold-down is operated by means of the at least one clamping element in a force- and / or displacement-controlled manner, and the surrounding atmosphere is extracted into the extraction channel via a process area in the hold-down mask.

[0009] Hold-down devices are generally known in the field and are used, for example, in material-to-material joining processes to bring the components to be joined (joining pairs) into contact with one another during the process, i.e. to hold them down together. The distance at which joining processes are to be carried out within one or more workpieces depends on the positioning of the components to be joined. The decisive factor is the center-to-center distance between these positions, which determines how close the material-to-material joins and thus the hold-down functions are to one another. The hold-down system according to the invention enables the hold-down of joining pairs that are intended for material-to-material joining processes classified by experts as being at close distances, in particular with center-to-center distances of 10 mm - 100 mm, preferably 10 mm - 50 mm, particularly preferably 10 mm - 30 mm.

[0010] In addition, the hold-down system according to the invention is characterized by functional integration, in particular a high level of functional integration compared to the known prior art, whereby the functions required for holding down during material-to-material joining processes are located compactly on the hold-down system or within the hold-down system. Such functions include, for example, guiding the system (establishing the necessary movement tolerances), adjusting (performing a movement along one or more axes), isolating certain components, constructing the mask and adjusting it, suction during the process, and / or sensor technology, in particular force and / or displacement sensors or position sensors.

[0011] The at least one clamping element used in the hold-down system according to the invention is preferably a clamping finger, but other designs are also possible, for example clamping brackets or toggle lever clamps.

[0012] The at least one actuator of the hold-down system according to the invention can be designed, for example, pneumatically, electromechanically, hydraulically, thermomechanically (shape memory actuator with reset via, for example, a spring) or piezoelectrically.

[0013] In an advantageous embodiment of the hold-down system according to the invention, it additionally comprises at least one guide system for the at least one clamping element. Such a guide system improves both the force absorption and the positional stability of the clamping element and thus the overall precision of the hold-down system.

[0014] In further advantageous embodiments of the hold-down system according to the invention, the at least one hold-down mask is either designed to be replaceable or permanently installed once. The replaceable hold-down mask can in particular be quickly exchangeable, which can be achieved, for example, by sliding it in, placing it on top, locking it, and / or clamping it. Permanently installed hold-down masks can, for example, be clamped, screwed, and / or glued once. In addition, the at least one hold-down mask is designed to be rotatable in an advantageous embodiment. Preferably, the at least one hold-down mask is designed to be replaceable, particularly preferably replaceable and rotatable. Due to the simple and flexible exchangeability of the hold-down mask, it can be quickly specified for the respective product, i.e., adapted to the respective workpiece to be joined. Automated changing is also conceivable in this case.

[0015] The hold-down mask rotates around its vertical axis (Z-direction). An additional drive (e.g., pneumatic, electromechanical, piezoelectric) is provided for this purpose. This drive directly drives the hold-down mask in rotation or, via a mechanical coupling (e.g., rack, slide rod, spindle, worm, gear), leads to a rotational movement of the hold-down mask. The rotation of the hold-down mask can further increase flexibility with regard to the variance and arrangement of workpieces or joining pairs.

[0016] In a further advantageous embodiment of the hold-down system according to the invention, the at least one clamping element has an additional spring element on a hold-down mask and / or in the area of ​​an actuator. This can counteract possible impacts or excessive hold-down forces, thus protecting both the hold-down system and the workpiece, and compensating for any shape and position tolerances.

[0017] In a further advantageous embodiment of the hold-down system according to the invention, a shielding gas is supplied near the at least one hold-down mask, preferably via a hose connection or an outlet hole. Nitrogen or argon, for example, can be used as the shielding gas. This also enables the processing of sensitive materials and increases the precision and quality of the bonded joining process.

[0018] Furthermore, the invention relates to a use of the hold-down system according to the invention for the integral joining, in particular welding, in particular laser welding, of connectors, in particular cell connectors for battery systems or battery modules. The use is not limited to the aforementioned embodiments, but can be used for other integral joining methods (e.g., resistance welding, gas pressure welding, friction welding, diffusion welding, ultrasonic welding, explosive welding, electron beam welding) as well as for other connection systems.

[0019] In an advantageous embodiment of the use of the hold-down system according to the invention, the hold-down mask has an electrical insulation function between simultaneously held-down positions on a joining partner, in particular between two poles, and / or to the overall system. In principle, an insulation function can be implemented anywhere on the hold-down system; however, it is preferably attached directly to the hold-down mask. Insulation is necessary, for example, during joining processes on batteries when both poles of a battery are held down, but can also be used in other processes and increases safety during use of the hold-down system. The insulation is achieved using separating layers or separating materials known in the art, for example, plastics or ceramics.

[0020] In a further advantageous embodiment, the use of the hold-down system according to the invention serves to produce at least five material-to-material connections, preferably at least 10 material-to-material connections, in particular at least 100 material-to-material connections, between joining pairs within a workpiece. The use of the hold-down system according to the invention enables the material-to-material joining of many, particularly closely spaced, joints (see center-to-center distances, e.g., 10 mm - 100 mm) as well as a short cycle time. Such a cycle time is, for example, less than 1 s per joining process, in particular less than 0.2 s per joining process.

[0021] In a further advantageous embodiment, the use of the hold-down system according to the invention serves to create material-to-material connections between flexible joining partners with wall thicknesses of less than 3 mm, preferably less than 2 mm, particularly preferably 0.1 mm - 2 mm. The material of the workpiece itself and the joining partner is arbitrary (within the scope specified by the joining process).

[0022] In a further advantageous embodiment, the hold-down system according to the invention is used in conjunction with one or more other hold-down systems according to the invention. The number of connected hold-down systems is arbitrary.

[0023] Advantages of the invention

[0024] The focus of the present invention is on optimizing the service life of hold-down systems, the quality of the joining processes performed, and the simple modularized parallelization of many closely spaced hold-down functions. Furthermore, the system according to the invention addresses the problems that arise with prior art systems due to increasing material thicknesses and the associated required hold-down forces, the growing number of joining positions per workpiece (in particular, the growing number of cells per battery module), and the one-sided positioning of battery terminals (in joining processes on battery systems).

[0025] The design of the hold-down system according to the invention enables the holding-down of closely spaced joining pairs, in particular with center-to-center distances of 10 mm - 100 mm, preferably 10 mm - 50 mm, and particularly preferably 10 mm - 30 mm. The hold-down system according to the invention is characterized by a high degree of functional integration within the hold-down system, so that only small installation spaces are required (particularly with regard to the arrangement perpendicular to the preferred axis). Consequently, the hold-down system can be used for products with a small center-to-center distance between the individual joining points.

[0026] In addition, the compact design of the hold-down system according to the invention enables a reduction in idle times, as this opens up the possibility of simultaneous individual clamping and unclamping of individual joining pairs.

[0027] This high dynamics during clamping and unclamping, as well as during the repositioning of the hold-down system, due to its compact design, also reduces the overall cycle times when using the hold-down system. Such a cycle time is, for example, less than 1 second per joining operation, and in particular less than 0.2 seconds per joining operation.

[0028] Likewise, the force- and / or displacement-adjustable operation of at least one clamping element enables adaptation to height tolerances, which can have a negative impact on the homogeneous distribution of clamping forces in conventional systems. This effect is avoided by the inventive hold-down system with its individually adjustable hold-down mechanism. The hold-down is achieved by an individual hold-down actuator for each joining point, which can be operated with force and / or displacement control as required depending on the prevailing conditions in order to achieve the optimal clamping state while also avoiding overloading the surrounding system technology. At the same time, the use of an adjustable hold-down force per joining pair improves the quality of the joining process. Faulty joining processes (misjoinings) can be minimized.

[0029] The design of the hold-down system enables maximizing joining speed, especially welding speed, through wide, unobstructed beam angles of incidence on the joining pair. Due to reflection, typical beam angles of incidence during joining processes are in the range of up to 15° deviation from the normal. In the hold-down system according to the invention, angles of incidence in the range of 0° to 25° are possible, and in some designs, even wider ranges are possible.

[0030] Furthermore, the design of the hold-down system according to the invention is characterized by an extraction channel integrated into at least one clamping element. This design of the extraction channel and the suction areas enables the extraction of emissions close to the process, because the integration of the extraction channel into the clamping element allows emissions generated during the joining process to be removed close to the joining point. The optimized flow guidance enables the rapid removal of byproducts of the joining processes (e.g., splashes, smoke). This minimizes contamination of the surrounding areas, which also contributes to an overall improvement in the quality of the joining processes.

[0031] Another particularly advantageous feature is the possibility of interchangeability, allowing for product-specific adaptation of the hold-down mask. This is connected to the clamping element but can be replaced (automatically) as needed. The holder for the hold-down mask(s) is preferably designed to allow for simple, quick, and, if necessary, automated replacement of these hold-down masks. In addition to improving the hold-down function itself, this design minimizes idle time and downtime of the hold-down system, since the hold-down masks are most susceptible to mechanical wear due to the mechanical contact in the hold-down system.

[0032] Overall, the hold-down system according to the invention is characterized by its high degree of modularity. It is designed in such a way that it can be used for various joining processes, types of workpieces and joining partners, as well as other diverse requirements. The hold-down system can be used both as a stand-alone hold-down system and in conjunction with any number of hold-down systems.

[0033] Short description of the drawings

[0034] Embodiments of the invention are explained in more detail with reference to the drawings and the following description.

[0035] They show:

[0036] Figure 1 shows a schematic structure of a hold-down system and a workpiece; and

[0037] Figure 2 shows an example of the hold-down system.

[0038] Embodiments of the invention

[0039] In the following description of the embodiments of the invention, identical or similar elements are designated by the same reference numerals, whereby a repeated description of these elements is omitted in individual cases. The figures only schematically illustrate the subject matter of the invention.

[0040] Figure 1 shows a schematic structure of a hold-down system 10 and a workpiece 38, each in a side view. The individual components are arranged primarily along a preferred axis 11 and feature a high degree of functional integration. This allows joining processes to be performed perpendicular to the preferred axis 11 (out of the image plane) in a very confined space. The relative arrangement of the components is not critical and is shown as an example.

[0041] The components of the hold-down system 10 shown are a support element 13, an actuator 17, which can execute actuator movements 18 as shown, a guide system 23 in the illustrated guide direction 24, and a clamping element 15, which is connected to the actuator 17 and the (optional) guide. The support element 13 represents the mechanical basis for the hold-down system 10, to which the actuator 17 is attached. This can be designed, for example, pneumatically, electromechanically, hydraulically, thermomechanically, or piezoelectrically. The guide system 23, which is used to improve the positional stability of the hold-down system 10, is also connected to the support element 13. The clamping element 15 attached to the actuator 17 and the guide system 23 is shown as a clamping finger, but can also be present in other designs. Also located on the clamping element 15 itself is a hold-down mask 19, as well as an exhaust channel 20 inside.This area is designed such that the removal 21 of the surrounding atmosphere 29 takes place via the process area 27, which is located in the hold-down mask 19, into the extraction channel 20. The extraction channel 20 is integrated into the clamping element 15, and thus the extraction direction 22 also runs away from the process area 27. This design enables extraction close to the process, since the integration into the clamping element 15 allows emissions generated to be removed close to the joining point. This minimizes contamination of the surrounding areas, and the optimized flow guidance for removing byproducts of the material-to-material joining also improves the quality of the joining process.

[0042] Finally, the individual suction channels 20 of several hold-down systems 10 can be combined as one suction system.

[0043] The hold-down mask 19 can be designed to be quickly exchangeable or permanently installed once. Preferably, the hold-down mask 19 is designed to be exchangeable and preferably also rotatable. This always allows for the flexible use of product-specific hold-down masks 19, which optimizes the joining process and the joining result. Furthermore, simple, fast, and potentially automated changing of the hold-down masks 19 can minimize non-productive and downtimes of the hold-down system 10 and increase machine availability, since the hold-down masks 19 are often subject to severe mechanical wear. The hold-down mask 19 can be designed such that it always holds down only one joining point of a workpiece 38, in particular only one pole 43 of a battery system 39, or two joining points or poles 43 simultaneously.

[0044] Additional elements are over-springs 31, which are shown in the area of ​​the actuator 17 and the hold-down mask 19, but can also be installed at other locations in the hold-down system 10. Likewise in the area of ​​the hold-down mask 19, an electrical insulation 33, here in the form of a separating layer, is attached, but this is also possible at other or additional locations in the hold-down system 10. Such an insulation function is necessary in particular between simultaneously held-down positions on a joining partner 36, in particular between two poles 43 of a cell in a battery system 39. However, an insulation 33 can also be used in other processes and increases safety during use of the hold-down system 10. The insulation 33 is preferably attached directly to the hold-down mask 19, as shown, but in principle it can be implemented anywhere on the hold-down system 10.The insulation 33 is carried out using separating layers or separating materials known in the art, preferably non-conductive plastics and / or ceramics.

[0045] Below the hold-down system 10, a workpiece 38 is shown on which the points to be joined are located. In this case, this is a battery system 39 which is to be held down and joined in a materially bonded manner using a connector 41, namely a cell connector 42. The joining partners 36 are therefore a pole 43 of the battery system 39 and a cell connector 42, which together form the joining pair 35 and are positioned below the hold-down mask 19. The hold-down mask 19 can be designed such that it only holds down one pole 43 of the battery system 39 or several, in particular two, poles 43 simultaneously. In the case shown, the materially bonded joining is carried out by means of laser welding, so that a laser 45 is placed above the hold-down system 10.In addition, the use of other material-bonded joining processes (e.g. resistance welding, gas pressure welding, friction welding, diffusion welding, ultrasonic welding, explosive welding, electron beam welding) is also possible.

[0046] The design of the hold-down system 10 allows for wide free angles of incidence 47 (at least 0-25°) for the joining process, which are defined as the angle between the laser beam 46 and the solder.

[0047] Figure 2 shows an exemplary embodiment of the hold-down system 10, which particularly illustrates the arrangement of the components in the hold-down system 10 and the functional integration of the hold-down system 10. As in Figure 1, the hold-down system 10 comprises a carrier element 13, an actuator 17, a guide system 23 and a clamping element 15, on which the hold-down mask 19 and the suction channel 20 are also located. An insulation 33 is also attached to the hold-down mask 19, and a spring element 31 is attached to each of the hold-down mask 19 and the actuator 17. The hold-down mask 19 is preferably designed such that it is product-specifically adapted to the workpiece 38 to be joined or held down. For this purpose, it can be exchangeable and mechanically rotatable about its vertical axis (Z-direction). For joining with high throughput and for a large number of joining points, it is possible to use several hold-down systems 10 combined in a composite.Such a connection is made perpendicular to the preferred axis 11 (along the plane from the.

[0048] screen area).

[0049] The invention is not limited to the embodiments described here and the aspects highlighted therein. Rather, numerous modifications are possible within the scope of the claims, which are within the scope of one skilled in the art.

Claims

Claims 1. A hold-down system (10) with a high degree of functional integration for joining pairs (35) in closely spaced material-to-material joining processes, in particular welding processes, comprising at least one clamping element (15), at least one actuator (17) for controllably holding down the joining pair (35) by means of the at least one clamping element (15), at least one hold-down mask (19) connected to the at least one clamping element (15), at least one extraction channel (20) integrated into the at least one clamping element (15), wherein the hold-down is operated in a force- and / or displacement-controllable manner by means of the at least one clamping element (15), and a surrounding atmosphere (29) is extracted into the extraction channel (20) via a process region (27) in the hold-down mask (19).

2. Hold-down system (10) according to claim 1, wherein it additionally comprises at least one guide system (23) for the at least one clamping element (15).

3. Hold-down system (10) according to claim 1 or 2, wherein the at least one hold-down mask (19) is designed to be replaceable or is permanently installed once.

4. The hold-down system (10) according to any one of claims 1 to 3, wherein the at least one hold-down mask (19) is rotatable.

5. Hold-down system (10) according to one of claims 1 to 4, wherein the at least one tensioning element (15) has an additional spring element (31) on a hold-down mask (19) and / or in the region of an actuator (17).

6. Hold-down system (10) according to one of claims 1 to 5, wherein protective gas is supplied near the at least one hold-down mask (19), preferably via a hose connection or an outlet bore.

7. Use of the hold-down system (10) according to one of claims 1 to 6 for the material-to-material joining, in particular welding, in particular laser welding, of connectors (41), in particular cell connectors (42) for battery systems (39) or battery modules.

8. Use of the hold-down system (10) according to claim 7, wherein the hold-down mask (19) has an electrical insulation function between simultaneously held-down positions on a joining partner (36), in particular between two poles (43), and / or to the overall system.

9. Use of the hold-down system (10) according to claim 7 or 8 for producing at least five material-locking connections, preferably at least 10 material-locking connections, in particular at least 100 material-locking connections, between joining pairs (35) within a workpiece (38).

10. Use of the hold-down system (10) according to one of claims 7 to 9 for producing material-locking connections between flexible joining partners (36) with wall thicknesses of less than 3 mm, preferably less than 2 mm, particularly preferably 0.1 mm - 2 mm.

11. Use of the hold-down system (10) according to one of claims 7 to 10 in conjunction with one or more further hold-down systems (10).

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