Device and method for cutting through a workpiece by means of a laser beam

Abstract

The invention relates to a device (10) for cutting through a workpiece (12), in particular a cell connector of a battery-cell assembly (14), by means of a laser beam (16) and to a method for cutting through a workpiece (12), in particular a cell connector of a battery-cell assembly (14), by means of a laser beam (16).

Description

[0001] Title: Device and method for cutting a

[0002] workpiece using a laser beam

[0003] Description

[0004] The invention relates to a device for severing a workpiece, in particular a cell connector of a battery cell arrangement, by means of a laser beam having the features of the preamble of claim 1 and to a method for severing a workpiece, in particular a cell connector of a battery cell arrangement, by means of a laser beam having the features of claim 10.

[0005] Battery cells, particularly those used in the automotive industry, can be arranged in a battery cell array and electrically connected to one another. Metal cell connectors are typically used to electrically connect the individual battery cells. When disassembling such a battery array, these cell connectors must be cut to separate the individual battery cells.

[0006] The cell connectors can be cut using a laser. When cutting through a cell connector, the laser beam can pass through the cut and damage the battery cells, which are usually located beneath the cell connector, or their components. A damaged battery cell can pose a hazard (fire and explosion hazard). It is therefore extremely important not to damage the battery cells, which are usually located beneath the cell connector, or their components.

[0007] It is therefore an object of the present invention to provide a device and a method for severing a workpiece, in particular a cell connector of a battery cell arrangement, by means of a laser beam, wherein damage to the components arranged behind the workpiece in the direction of the laser beam is avoided.

[0008] The above object is achieved by a device for severing a workpiece by means of a laser beam having the features of claim 1. The workpiece can be a cell connector of a battery cell arrangement.

[0009] The device comprises a laser device for generating and / or focusing the laser beam. The laser device is set up such that the (generated) laser beam on the workpiece has a beam diameter of less than or equal to 100 pm (micrometers), in particular less than or equal to 50 pm. The laser device is further set up such that the (generated) laser beam has a divergence which has a half aperture angle of greater than or equal to 80 mrad. Preferably, the laser beam further has a beam parameter product in the range from 0.38 mm*mrad (millimeters * milliradians) to 16 mm*mrad.

[0010] The laser device can be configured such that the laser beam has a beam parameter product of 0.6 mm*mrad for a single-mode laser (beam). The laser device can be configured such that the laser beam has a beam parameter product of 6 mm*mrad, in particular 4 mm*mrad, for a multi-mode laser (beam).

[0011] This makes it possible to provide a laser intensity that, thanks to the small laser spot on the surface of the workpiece, is sufficiently high to separate it. Due to the large divergence, the laser intensity on the surface of the battery cell components located behind the workpiece in the direction of the laser beam can be kept as low as possible to avoid damaging them. The risk of ignition of insulation material and / or fire or explosion of the battery cells can be eliminated or at least reduced.

[0012] The cutting process can be performed completely automatically (without manual intervention). This allows for lower heat input compared to other processes (e.g., plasma cutting). Furthermore, chip formation can be prevented compared to other processes (e.g., milling) (chip-free cutting of the cell connectors). No foreign substances, such as coolants or other operating materials, are required, which must be used with other processes.

[0013] The beam parameter product (SPP) can be described by the following formula:

[0014] SPP = a * (dO / 2)

[0015] Where a is half the aperture angle of divergence and dO is the beam diameter of the (focused) laser beam on the workpiece.

[0016] The above formula can be transformed as follows: a = SSP / (dO / 2)

[0017] The half-angle a of the divergence becomes large when either the beam parameter product (SSP) is large or the beam diameter at the focus dO becomes small. The beam diameter dO can be defined as follows: dO = dLLK * m

[0018] Here, dLLK represents the diameter of the fiber optic cable and m the image ratio. The beam diameter at focus dO therefore becomes small when, in particular, the image ratio becomes small. The following formula can be set up for half the aperture angle a of the divergence: a = SSP / (dLLK * m / 2) The image ratio m can be described by the following formula: m = f / f C where f represents the lens focal length and fC the collimation focal length. The image ratio m becomes small in particular when the lens focal length f becomes small and / or the collimation focal length fC becomes large.

[0019] By varying or adjusting in particular the lens focal length f and / or the collimation focal length fC, the half aperture angle a or the divergence can be adjusted as desired.

[0020] According to a further development, the laser device for generating the laser beam can comprise a laser beam source. The laser beam source can be designed as a pulsed laser beam source. The laser beam source can be a

[0021] (ns (nanosecond) pulsed) laser beam source. The laser beam source can have a power in a range from 70 W (watts) to 1000 W, in particular in a range from 500 W to 600 W. The laser beam source can in particular have a pulse duration in a range from 3 ns to 2000 ns, in particular in a range from 50 ns to 500 ns. The laser beam source can have a repetition rate in a range from 1 kHz (kilohertz) to 4 MHz (megahertz), in particular in a range from 20 kHz to 80 kHz.

[0022] This allows the laser power to be optimally adjusted. This allows as much energy as possible to be applied to the workpiece to be cut, while simultaneously applying as little energy as possible to the battery components located behind the workpiece in the beam direction.

[0023] According to a further development, the laser device for generating the laser beam can have a laser beam source. The laser beam source can be designed as a fiber laser. The laser beam source can be designed as a single-mode laser. The laser beam source can be designed as a CW (continuous wave) laser. The laser beam source can have a power in a range from 0.5 kW (kilowatts) to 5 kW, in particular in a range from 0.5 kW to 2 kW. The laser beam source designed as a single-mode laser can have a beam quality that has a diffraction index M 2 of less than 1 .7 .

[0024] This allows the laser power to be optimally adjusted. This allows as much energy as possible to be applied to the workpiece to be cut, while simultaneously applying as little energy as possible to the battery components located behind the workpiece in the beam direction.

[0025] According to a further development, the laser device for generating the laser beam can have a laser beam source. The laser beam source can be designed as a disk laser. The laser beam source can be designed as a multi-mode laser. The laser beam source can be designed as a CW laser. The laser beam source can have a power in a range from 0.5 kW to 24 kW, in particular in a range from 2 kW to 8 kW.

[0026] This allows the laser power to be optimally adjusted. This allows as much energy as possible to be applied to the workpiece to be cut, while simultaneously applying as little energy as possible to the battery components located behind the workpiece in the beam direction.

[0027] According to a further development, the laser beam source can be designed as an infrared laser. The laser beam source designed as an infrared laser can have a wavelength in a range from 800 nm (nanometers) to 1200 nm, in particular from 1030 nm or 1070 nm.

[0028] This allows the laser power to be further optimized and adjusted. This allows as much energy as possible to be delivered to the workpiece being cut, while simultaneously delivering as little energy as possible to the battery components located behind the workpiece in the beam direction.

[0029] According to a further development, the laser beam source can be designed as a laser with a wavelength in the visible range. The laser beam source can be designed as a VIS (visible) laser. The wavelength of the VIS laser can be 551 nm (green).

[0030] This allows an optimal energy input into the workpiece to be cut when using a VIS laser.

[0031] According to a further development, the device can comprise a scanner optics system for moving the laser beam across the workpiece. The scanner optics system can be configured to move the laser beam across the workpiece at a speed in a range from 10 m / min (meters per minute) to 80 m / min, in particular in a range from 20 m / min to 60 m / min. The laser spot can be moved across the workpiece using the scanner optics system. The laser beam can be aligned on the workpiece using the scanner optics system.

[0032] The scanner optics can have an imaging ratio in a range of 1:1 to 5:1, in particular in a range of 1.5:1 to 2:1.

[0033] This allows for optimal energy input into the workpiece to be cut using a scanner optic. Remote cutting can also be implemented using simple means.

[0034] According to a further development, the device can comprise a fixed optics system for fixed alignment of the laser beam. The laser beam can be moved on the workpiece by moving the workpiece and / or the fixed optics system (relative to each other).

[0035] The fixed optics can include a cutting nozzle for aligning and / or focusing the laser beam (on the workpiece). The fixed optics can include a gas supply for supplying an (inert) cutting gas. The cutting gas can be nitrogen, in particular. The cutting gas can be supplied, in particular, into the area of ​​the focused laser beam on the workpiece.

[0036] The fixed optics can achieve an image ratio in a range of 1:1 to 5:1, particularly in a range of 1.5:1 to 2:1. This allows for optimal energy input into the workpiece to be cut using a fixed optics system. Furthermore, the cutting result can be optimized by adjusting the cutting nozzle and / or the cutting gas.

[0037] According to a further development, the device can comprise an optical sensor for detecting the position of the laser beam and / or the workpiece. The optical sensor can be camera-based. The optical sensor can be designed as a camera. The optical sensor can be configured to monitor the position of the laser beam and / or the workpiece.

[0038] This allows the position of the laser beam and / or the workpiece to be detected and / or controlled using simple means.

[0039] The above object is further achieved by a method for severing a workpiece by means of a laser beam having the features of claim 10. The workpiece can be a cell connector of a battery cell arrangement.

[0040] The procedure includes the following steps:

[0041] Generating and focusing a laser beam, in particular by means of a laser device.

[0042] The laser beam on the workpiece has a beam diameter of less than or equal to 100 pm, in particular less than or equal to 50 pm. Furthermore, the laser beam has a divergence with a half-beam angle of greater than or equal to 80 mrad. Furthermore, the laser beam can have a beam parameter product in a range from 0.38 mm*mrad to 16 mm*mrad.

[0043] The laser beam can have a beam parameter product of 0.6 mm*mrad for a single-mode laser (beam). The laser beam can have a beam parameter product of 6 mm*mrad, in particular 4 mm*mrad, for a multi-mode laser (beam).

[0044] This makes it possible to provide a laser intensity that, thanks to the small laser spot on the surface of the workpiece, is sufficiently high to separate it. Due to the large divergence, the laser intensity on the surface of the battery cell components located behind the workpiece in the direction of the laser beam can be kept as low as possible to avoid damaging them. The risk of ignition of insulation material and / or fire or explosion of the battery cells can be eliminated or at least reduced.

[0045] Cutting can be carried out completely automatically (without manual intervention). This allows for lower heat input compared to other processes (e.g., plasma cutting). Furthermore, chip formation can be prevented compared to other processes (e.g., milling) (chip-free cutting of the cell connectors). No foreign substances, such as coolants or other operating materials, are required, which must be used with other processes.

[0046] According to a further development, the method may comprise the step of: moving the laser beam and / or the workpiece in order to generate a feed (movement) of the laser beam focused on the workpiece.

[0047] The feed rate can be in a range from 10 m / min to 80 m / min, in particular in a range from 20 m / min to 60 m / min.

[0048] This allows the cutting of the workpiece to be further optimized and a clean cutting joint to be achieved.

[0049] According to a further development, the procedure may include the step :

[0050] Supplying an (inert) cutting gas. The cutting gas can be nitrogen. The cutting gas can be supplied, in particular, into the area of ​​the focused laser beam on the workpiece.

[0051] By supplying the cutting gas, the cutting result or the cutting joint can be optimized.

[0052] According to a further development, the procedure may include the step :

[0053] Determining the position of the (focused) laser beam and / or the workpiece. The position can be determined using an optical sensor.

[0054] This allows for position detection and / or monitoring to be implemented using simple means. According to a further development, a device as described above can be used to carry out the method.

[0055] With regard to the advantages that can be achieved, reference is made to the relevant explanations of the device. The measures described in connection with the device and / or those explained below can be used to further refine the method.

[0056] Further features, details and advantages of the invention will become apparent from the wording of the claims and from the following description of exemplary embodiments with reference to the drawings. They show:

[0057] Fig. 1 is a schematic representation of a battery cell arrangement with a workpiece;

[0058] Fig. 2 is a schematic representation of a device for cutting the workpiece according to Figure 1 and

[0059] Fig. 3 is a schematic representation of a laser beam generated by the device according to Fig. 2.

[0060] In the following description and in the figures, corresponding components and elements bear the same reference symbols. For the sake of clarity, not all reference symbols are shown in all figures.

[0061] Figure 1 shows a schematic representation of a battery cell arrangement 14 with a workpiece 12. The workpiece 12 is embodied as a cell connector of the battery cell arrangement 14. The battery cell arrangement 14 comprises two battery cells 13, which are electrically connected to one another by means of the workpiece 12.

[0062] Figure 2 shows a schematic representation of a device 10 for severing the workpiece 12 according to Figure 1. The device 10 is configured to sever the workpiece 12 by means of a laser beam 16.

[0063] The device 10 comprises a laser device 18 for generating and / or focusing the laser beam 16. The laser device 18 comprises a laser beam source 24.

[0064] The laser beam source 24 can be designed as a (ns-) pulsed laser beam source 24. The laser beam source 24 can have a power in a range from 70 W to 1000 W, in particular in a range from 500 W to 600 W. The laser beam source 24 can have a pulse duration in a range from 3 ns to 2000 ns, in particular in a range from 50 ns to 500 ns, and / or a repetition rate in a range from 1 kHz to 4 MHz, in particular in a range from 20 kHz to 80 kHz.

[0065] The laser beam source 24 can be designed as a fiber laser, in particular a single-mode laser. The laser beam source 24 can have a power in a range from 0.5 kW to 5 kW, in particular in a range from 0.5 kW to 2 kW. The laser beam source 24 designed as a single-mode laser can have a beam quality that has a diffraction index M 2 of less than 1.7. The laser beam source 24 can be designed as a disk laser, in particular a multi-mode laser. The laser beam source 24 can have a power in a range from 0.5 kW to 24 kW, in particular in a range from 2 kW to 8 kW.

[0066] The laser beam source 24 can be designed as an infrared laser with a wavelength in a range of 800 nm to 1200 nm, in particular of 1030 nm or 1070 nm.

[0067] The laser beam source 24 can be designed as a laser with a wavelength in the visible range, in particular of 515 nm.

[0068] In the present case, the device 10 has a scanner optics 26 for moving the laser beam 16 across the workpiece 12. The scanner optics 26 are configured to move the laser beam 16 across the workpiece 12 at a speed in a range of 10 m / min to 80 m / min, in particular in a range of 20 m / min to 60 m / min.

[0069] The scanner optics 26 can have an imaging ratio in a range from 1:1 to 5:1, in particular in a range from 1.5:1 to 2:1. Remote cutting of the workpiece 12 can be implemented by means of the scanner optics 26.

[0070] The device 10 can also include fixed optics for fixedly aligning the laser beam 16. The fixed optics can include a cutting nozzle for aligning and / or focusing the laser beam 16. The fixed optics can include a gas supply for supplying a cutting gas (e.g., nitrogen), in particular into the region of the focused laser beam 16 on the workpiece 12.

[0071] The fixed optics can have an imaging ratio in a range from 1 : 1 to 5 : 1 , in particular in a range from 1.5 : 1 to 2 : 1 .

[0072] The device 10 comprises an optical sensor 28. The position of the laser beam 16 and / or the workpiece 12 can be detected or monitored by means of the optical sensor 28.

[0073] Figure 3 shows a schematic representation of a laser beam 16 generated by the device 10 according to Figure 2. In Figure 3, the optical axis 21 of the laser beam 16 is shown by a dashed line. The laser beam direction 23 of the laser beam 16 is indicated in Figure 3 by an arrow.

[0074] The laser beam 16 is focused on the workpiece 12. The focused laser beam has a beam diameter of 20 on the workpiece 12. The beam diameter 20 can be less than or equal to 100 pm, in particular less than or equal to 50 pm.

[0075] The laser beam 16 has in this case half a

[0076] Aperture angle 22 of divergence of greater than or equal to 80 mrad. The beam parameter product of the laser beam 16 lies in a range from 0.38 mm*mrad to 16 mm*mrad.

[0077] The method for cutting a workpiece 12, in particular a cell connector of a battery assembly 14, by means of a laser beam 16 can be described with reference to Figures 1 to 3 as follows:

[0078] First, a laser beam 16 is generated by means of the laser device 18 and focused onto the workpiece 12. The laser beam 16 has a beam diameter 20, a beam parameter product, and / or a half aperture angle 22, as described above.

[0079] The laser beam 16 and / or the workpiece 12 can be moved to generate a feed (movement) of the laser beam 16 focused on the workpiece 12. The feed can be within a range as described above.

[0080] A cutting gas can be supplied. The cutting gas, in particular nitrogen, can be supplied into the area of ​​the focused laser beam 16 on the workpiece 12.

[0081] It can measure the position of the laser beam and / or the workpiece

[0082] 12. This can be done in particular by means of an optical sensor 28.

[0083] To carry out the method, a device 10 shown in Figure 2 (as described above) can be used.

Claims

Patent claims 1. Device (10) for severing a workpiece (12), in particular a cell connector of a battery cell arrangement (14), by means of a laser beam (16), comprising a laser device (18) for generating and / or focusing the laser beam (16), characterized in that the laser device (18) is set up such that the laser beam (16) on the workpiece (12) has a beam diameter (20) of less than or equal to 100 gm, in particular less than or equal to 50 gm, and a divergence with a half aperture angle (22) of greater than or equal to 80 mrad.

2. Device (10) according to claim 1, characterized in that the laser device (18) for generating the laser beam (16) has a laser beam source (24), wherein the laser beam source (24) is designed as a pulsed laser beam source (24), a power in a range from 70 W to 1000 W, in particular in a range from 500 W to 600 W, a pulse duration in a range from 3 ns to 2000 ns, in particular in a range from 50 ns to 500 ns, and / or a repetition rate in a range from 1 kHz to 4 MHz, in particular in a range from 20 kHz to 80 kHz.

3. Device (10) according to claim 1, characterized in that the laser device (18) for generating the laser beam (16) has a laser beam source (24), wherein the laser beam source (24) is designed as a Fiber laser, in particular a single-mode laser, and / or has a power in a range of 0.5 kW to 5 kW, in particular in a range of 0.5 kW to 2 kW.

4. Device (10) according to claim 1, characterized in that the laser device (18) for generating the laser beam (16) has a laser beam source (24), wherein the laser beam source (24) is designed as a disk laser, in particular a multi-mode laser, and / or has a power in a range from 0.5 kW to 24 kW, in particular in a range from 2 kW to 8 kW.

5. Device according to one of claims 2 to 4, characterized in that the laser beam source (24) is designed as an infrared laser with a wavelength in a range of 800 nm to 1200 nm, in particular of 1030 nm or 1070 nm.

6. Device according to one of claims 2 to 4, characterized in that the laser beam source (24) is designed as a laser with a wavelength in the visible range, in particular of 515 nm.

7. Device (10) according to one of the preceding claims, characterized in that the device (10) comprises a scanner optics (26) for moving the laser beam (16) over the workpiece (12), in particular wherein the scanner optics (26) are designed to move the laser beam (16) over the workpiece (12) at a speed in a range of 10 m / min to 80 m / min, in particular in a range of 20 m / min to 60 m / min, in particular wherein the scanner optics (26) has an imaging ratio in a range of 1:1 to 5:1, in particular in a range of 1.5:1 to 2:

1.

8. Device (10) according to one of claims 1 to 7, characterized in that the device (10) comprises a fixed optics for the fixed alignment of the laser beam (16), wherein the fixed optics comprises a cutting nozzle for aligning and / or focusing the laser beam (16), in particular wherein the fixed optics comprises a gas supply for supplying a cutting gas, in particular into the region of the focused laser beam (16) on the workpiece (12), wherein the fixed optics preferably has an imaging ratio in a range from 1:1 to 5:1, in particular in a range from 1.5:1 to 2:

1.

9. Device (10) according to one of the preceding claims, characterized in that the device (10) comprises an optical sensor (28) for detecting the position of the laser beam (16) and / or the workpiece (12).

10. Method for severing a workpiece (12), in particular a cell connector of a battery cell arrangement (14), by means of a laser beam (16), comprising the steps: Generating and focusing a laser beam (16), in particular by means of a laser device (18), wherein the laser beam (16) on the workpiece (12) has a beam diameter (20) of less than or equal to 100 pm, in particular of less than or equal to 50 pm, and a Divergence with a half aperture angle (22) of 80 mrad .

11. Method according to claim 10, characterized by the step: Moving the laser beam (16) and / or the workpiece (12) in order to generate a feed rate of the laser beam (16) focused on the workpiece (12), wherein the feed rate is in a range from 10 m / min to 80 m / min, in particular in a range from 20 m / min to 60 m / min.

12. Method according to claim 10 or 11, characterized by the step: Supplying a cutting gas, in particular into the area of ​​the focused laser beam (16) on the workpiece (12).

13. Method according to one of claims 10 to 12, characterized by the step: Determining the position of the laser beam (16) and / or the workpiece (12), in particular by means of an optical sensor (28).

14. Method according to one of claims 10 to 13, characterized in that a device (10) according to one of claims 1 to 9 is used to carry out the method.

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