Method and device for laser welding of at least two conductive pieces, and arrangement of at least two conductive pieces integrally connected to one another.

Abstract

The present invention relates to a method for laser welding of at least two conductive pieces (10, 16) and an arrangement of at least two conductive pieces (10, 16) integrally connected to one another.

Description

Technical Field

[0001] The present invention relates to a method for laser welding at least two conductor pieces having the features recited in claim 1, an arrangement of at least two conductor pieces integrally connected to each other having the features recited in claim 12, and a device for laser welding at least two conductor pieces having the features recited in claim 13.

[0002] Welding conductor pieces together using a laser beam is known from the prior art. Using a laser beam, a melt pool can be generated that extends across all of the conductor pieces to be welded. To do this, the laser beam is moved back and forth between the individual conductor pieces. This produces a weld bead that connects all of the conductor pieces to be welded together.

[0003] To reduce the processing time, the laser power is usually increased. A disadvantage is that there is a limit to the increase in laser power, otherwise it can lead to the weld bead being formed asymmetrically due to local heat input. Asymmetric weld beads tend to be inclined, resulting in a poor welding result. Furthermore, this can also lead to an increase in spatter, especially at the start of the process.

[0004] Another disadvantage is that there is usually a gap between the conductor pieces to be welded, and the laser beam necessarily moves over this. This allows radiation to enter the gap and interact with the material outside the welding zone (process zone). Interaction of the laser beam with the material outside the welding zone (for example, the conductor piece) is undesirable. Furthermore, the energy directed into the gap cannot be utilized in the welding process.

Background Art

[0005] Therefore, an object of the present invention is to provide a method and a device for laser welding at least two conductor pieces, and an arrangement of at least two conductor pieces integrally connected to each other, in which the above disadvantages are eliminated.

[0006] Summary of the Invention The above objective is achieved by a method for laser welding at least two conductive pieces having the features described in claim 1.

[0007] The conductive pieces can be conductive elements made of metal (e.g., copper). The conductive pieces can be placed within the stator of an electromachine. The conductive pieces can be designed for placement within the stator of an electromachine. When placed within the stator and electrically connected to one another, the conductive pieces can be used to generate the magnetic field required for the operation of the electromachine.

[0008] The conducting piece can be a "hairpin," which has two elongated (substantially parallel) legs connected to each other by a connector. The shape of the hairpin is usually corresponding to a hairpin. In other words, the hairpin has a (substantially) U-shape. The conducting piece may also be a "special pin" having only one leg. Combinations of "hairpins" and "special pins" are also conceivable. The conducting piece may have a rectangular cross-section.

[0009] The method is, The steps include: providing an elongated first conductor piece having a first end and a first end face.

[0010] The step of providing an elongated second conductor piece having a second end and a second end face. The first end face is positioned adjacent to the second end face.

[0011] Conductor pieces can be arranged on a circular path within the stator, with the ends of the conductor pieces protruding from the stator. The ends protruding from the stator can be aligned parallel to each other, and in particular, oriented along the axial direction of the stator.

[0012] The step of providing at least two, and in particular at least four, laser spots on a first end face and / or a second end face.

[0013] Each laser spot has a core region and a ring region. The average laser power density of the core region is higher than the average laser power density of the ring region. The core region can be circular in shape. The ring region can be ring-shaped. Other geometric shapes of the core region and / or ring region, such as oval or elliptical, are also conceivable.

[0014] A step of moving the laser spot. The laser spot can be moved on a first end face and / or a second end face. The laser spot generates a common molten pool that extends at least partially, and especially completely, on the first end face and the second end face.

[0015] This allows the heat input to be more evenly distributed across the end faces of the conductive pieces, enabling the use of more laser power. This reduces downtime and therefore processing time. In addition, the melting of the end faces becomes more uniform, resulting in greater gap tolerance, less splatter and / or pores, and an overall more stable process result. By equalizing the heat input, a more uniform molten pool can be generated, resulting in more uniform and symmetrical molten beads.

[0016] Further developments suggest that this method is The procedure may include the step of moving each of the laser spots along a path. Each laser spot can move along its own path. It is also conceivable to move the laser spots along a common path. Each path can extend over a first end face and a second end face. In other words, each path can extend over both end faces. This allows the laser spots to be moved, in particular, over both end faces. The laser spots can be moved across the gap between the first end face and the second end face. Each path can be at least partially, and in particular entirely, a straight line, a circle, and / or an ellipse. Other geometric embodiments of each path (e.g., rectangle, semicircle, etc.) are also conceivable. At least two paths, and in particular all paths, can be oriented parallel to each other.

[0017] The laser spots can be positioned in a fixed configuration relative to each other while moving across the end face. The laser spots can be held in a fixed position relative to each other. The distance between the laser spots can be kept constant. It is also conceivable that the distance between the laser spots may vary or change, particularly continuously.

[0018] The laser spot can be positioned in a fixed configuration. The laser spot configuration can be moved translationally along a common path. Alternatively, the laser spot configuration can be rotated along the (common) path around an axis, particularly the optical axis, while moving.

[0019] This allows the heat input to be distributed more evenly across the first and second end faces.

[0020] Further developments suggest that this method is The procedure may include the step of moving each of the laser spots along a path, where each path extends only over a first end face or a second end face. In other words, each path may extend only over a first end face or only over a second end face. Each laser spot may move along its own path. Each path does not extend, in particular, across the gap between the two end faces. This also makes it possible to move individual laser spots only over the first end face or only over the second end face. In particular, the laser spots do not move over the gap between the two end faces. Each path may be at least partially, and in particular entirely, a straight line, a circle, and / or an ellipse. Other geometric embodiments of each path (e.g., rectangle, semicircle, etc.) are also conceivable. At least two paths, and in particular all paths, may be oriented parallel to each other.

[0021] This prevents one of the laser spots from moving across the gap located between the two endfaces. This prevents any radiation from being directed into the gap. This prevents the laser radiation from interacting with material outside the welding or process zone. All of the laser energy can be used for the welding process.

[0022] Further developments in the method allow the laser spot to be moved by the scanner optics. The scanner optics can have an imaging ratio of 1.7:1.

[0023] Alternatively, it is assumed that the laser spot can be generated using a fixed optical system. It is assumed that the laser spot can be moved by moving the fixed optical system.

[0024] This allows the laser spot to be moved using a simple method.

[0025] According to a further development of the method, at least two, in particular all, laser spots can be designed in the same way. It is also envisaged that the shape of at least two, in particular all, laser spots may be different.

[0026] This simplifies the generation of individual laser spots and / or makes the energy distribution more uniform.

[0027] According to a further development of the method, the ring regions of at least two, in particular all, laser spots can overlap each other.

[0028] Due to the overlapping of the ring regions, the energy input can be further optimized.

[0029] According to a further development of the method, the core regions of at least two, in particular all, laser spots can be arranged at a certain distance from each other. The distance between the laser spots can be at least 20% of the diameter of the laser spots. The core regions of at least two, in particular all, laser spots cannot be arranged overlapping each other. In other words, the core regions preferably do not overlap.

[0030] The spaced-apart core regions enable the energy intensity to be dispersed over a larger surface, and thus the energy input is further optimized.

[0031] It is envisaged that at least two, in particular all, laser spots can be arranged at a certain distance from each other. At least two, in particular all, laser spots can be arranged without overlapping each other. In other words, the laser spots preferably do not overlap.

[0032] The core regions and / or ring regions of at least two, in particular all, laser spots can be arranged at a certain distance from each other. The ring regions of at least two adjacent laser spots can (have at least one common point and) touch (at their respective outer diameters).

[0033] It is assumed that at least two, and in particular all, laser spots may be arranged so that their core regions and / or their ring regions overlap. For example, the ring regions of at least two (adjacent), and in particular all, laser spots can overlap. It is assumed that the ring regions of laser spots overlap with the core regions of adjacent laser spots.

[0034] This allows the energy input to be distributed as optimally as possible on the corresponding surface.

[0035] Further development of the method suggests that at least two, and in particular all, laser spots can be generated using optical multifibers. These optical multifibers can be designed as 2-in-1 fibers. At least two, and in particular all, laser spots can be configured similarly. In particular, the laser spots can have (substantially) identical beam characteristics.

[0036] A 2-in-1 fiber can have a fiber core diameter of 50 μm (micrometers) and a fiber ring diameter of 200 μm.

[0037] To generate a laser spot, a laser with a beam quality of SPP (Beam Parameter Product) of 4 mm * mrad (millimeters * milliradians) or less can be used.

[0038] To generate a laser spot, a multimode NIR (near-infrared) laser with a power of 4 kW (kilowatts) or more, particularly 8 kW, and preferably more than 12 kW, can be used.

[0039] Alternatively, a laser with wavelengths in the visible range, particularly green or blue (VIS laser), can be used.

[0040] This allows for the generation of the first and second laser spots in the simplest possible way.

[0041] Further developments suggest that this method is The process may include a step of varying, in particular a step of vibrating, the average laser power density of at least one laser spot, which is part of the core region and / or ring region of the laser spot. It is assumed that multiple, in particular all, laser spots, the average laser power density of their respective core regions and / or respective ring regions, can be varied, in particular a step of vibrating.

[0042] Variations (or vibrations) in the average laser power density can be introduced, particularly during the welding process. The total laser power can be varied or vibrated during the welding process.

[0043] This makes it possible to increase or adjust the degree of mixing within the molten pool as required. This allows for further homogenization of the energy input.

[0044] Further development of the method suggests that at least two, and in particular all, laser spots can be generated by a laser beam. The individual laser beams can be guided parallel to each other.

[0045] At least two, and in particular all, laser spots can each be generated using a partial beam. The partial beams can be generated from a common laser beam, for example, by an optical beam splitter, wedge plate, etc. The partial beams can be guided parallel to each other.

[0046] This makes it as easy as possible to generate laser spots of similar shape.

[0047] This delicious, The process may include a step of determining the position of the laser spot on each end face. For this purpose, an optical sensor can be used. The optical sensor may be camera-based. The optical sensor may be configured as a camera. Alternatively, the sensor can be designed as an interference sensor system.

[0048] This enables the detection and / or control of the position of each laser spot. Therefore, any potential misalignment of each laser spot can be registered and / or corrected. This ensures and monitors the consistent quality of the welded connection.

[0049] Further developments suggest that this method is This may include a step of moving the laser spot by rotational motion around the optical axis.

[0050] This makes it possible to increase or adjust the degree of mixing within the molten pool as required. This allows for further homogenization of the energy input.

[0051] The above objective is further achieved by an arrangement of at least two conductive pieces integrally connected to one another, having the features described in claim 11. A physically joined connection is produced using the method described above. In particular, a physically joined connection is a welded connection.

[0052] For the advantages that can be achieved, refer to the embodiments relevant to this method. The measures described in relation to this method, and / or the measures described below, may be useful for further developing the arrangement.

[0053] The above objective is achieved by a device for laser welding of at least two conductive pieces having the features described in claim 13.

[0054] The device comprises at least one laser source. The laser source is configured to generate at least two, and more particularly, at least four, laser spots. Each laser spot has, in particular, a circular core region and, in particular, a ring-shaped ring region. The average laser power density of the core region is higher than the average laser power density of the ring region.

[0055] This device includes a control unit for controlling the device. This device and / or the control unit are configured to perform the methods described above. The control unit may be designed as a computer.

[0056] For the advantages that can be achieved, refer to the embodiments relevant to this method. The measures described in relation to this method and / or the measures described below may be useful for further developing this device.

[0057] A computer-readable storage medium is proposed, which, when executed by a computer, provides commands to cause the computer to perform the procedures described above. For the advantages that can be achieved, refer to embodiments relevant to this method. Measures described in connection with this method and / or those described below may help to further develop the storage medium.

[0058] A computer program is proposed that, when executed by a computer, includes commands to cause the computer to perform the method described above. For the advantages that can be achieved, refer to embodiments relevant to this method. The measures described in relation to this method and / or the measures described below may be useful for further developing the computer program.

[0059] A data carrier signal is proposed to characterize and / or transmit the computer program relating to the above design. The data carrier signal can be received, for example, via the computer's optical data interface. For the advantages that can be achieved, refer to the relevant embodiments relating to the computer program. Measures described in relation to the computer program and / or described below may be useful for further developing the data carrier signal.

[0060] Further features, details, and advantages of the present invention will become apparent from the following description of exemplary embodiments with reference to the drawings. [Brief explanation of the drawing]

[0061] [Figure 1] A schematic perspective view of the end portion, which has the end faces of two conductive pieces, is shown, and four laser spots move along the end face according to the first exemplary embodiment. [Figure 2] A schematic perspective view of the end portion, which has the end faces of two conductive pieces, is shown, and four laser spots move along the end face according to a second exemplary embodiment. [Figure 3] A schematic perspective view of the end portion, which has the end faces of two conductive pieces, is shown, and four laser spots move along the end face according to a third exemplary embodiment. [Figure 4] A schematic top view of the laser spot is shown.

[0062] In the following descriptions and figures, corresponding components and elements share the same reference numerals. For clarity, not all reference numerals are reproduced in all drawings.

[0063] A method according to the present invention for laser welding of at least two conductive pieces 10, 16 will be described below with reference to Figures 1 to 4.

[0064] This delicious, The following steps are included: providing an elongated first conductor piece 10 having a first end 12 and a first end face 14.

[0065] The step of providing an elongated second conductor piece 16 having a second end 18 and a second end face 20.

[0066] In this case, the ends 12 and 18 and the two end faces 14 and 20 are arranged adjacent to each other. The gap 15 is located between the two end faces 14 and 20.

[0067] In this case, the conductor pieces 10 and 16 have a rectangular cross-section. Therefore, the two end faces 14 and 20 also have a rectangular shape. Each of the two end faces 14 and 20 has four edges 17, which represent the outer boundaries of the respective end faces 14 and 20.

[0068] After two end faces 14 and 20 are provided, four laser spots 22 are generated on the end faces 14 and 20 in this case.

[0069] Each laser spot 22 has a circular core region 24 and a ring-shaped ring region 26 (see Figure 4). The average laser power density of the core region 24 is higher than the average laser power density of the ring region 26. In other words, the laser intensity of the core region 24 is higher than the laser intensity of the ring region 26.

[0070] The laser spot 22 moves over the two end faces 14 and 20. The laser spot 22 generates a common molten pool 28. The common molten pool 28 extends at least partially over the first end face 14 and the second end face 20. Molten beads are then formed from the common molten pool 28, which materially joins and connects the two ends 12 and 18.

[0071] The four laser spots 22 are positioned at a constant distance from each other. In other words, the 22 laser spots do not overlap. It is also assumed that the laser spots 22, their ring regions 26 and / or their core regions 24 may overlap. It is assumed that the ring regions 26 of the laser spots 22 may overlap, and the core regions 24 are spaced apart from each other.

[0072] The four laser spots 22 can be moved using a scanner optical system (not shown). It is also conceivable that the four laser spots 22 are generated by a fixed optical system, which can be moved to move the laser spots 22.

[0073] In this case, all four laser spots 22 are designed similarly.

[0074] The four laser spots 22 can be generated by optical multifibers, particularly 2-in-1 fibers (not shown).

[0075] Each laser spot 22 can be generated by a laser beam. The laser beams can be guided parallel to each other. Parallel laser beams can be designed, in particular, as partial beams of a common laser beam, which are preferably generated by a beam splitter (not shown).

[0076] The average laser power density of the laser spots 22, or their core regions 24 and / or their ring regions 26, can be varied, in particular, oscillated. It is also conceivable that an intensity gradient can be driven from the core region 24 to the ring region 26 (or vice versa). In other words, the average laser intensity can be continuously increased (e.g., at the end of the welding process) and / or decreased (e.g., at the start of the welding process) from the core region 24 to the ring region 26.

[0077] The position of the laser spot 22 on the end faces 14 and 20 may also be determined, particularly for position monitoring and control. This can be done using an optical sensor (not shown).

[0078] Figure 1 illustrates the movement of the laser spot 22 according to a first exemplary embodiment.

[0079] In this case, the laser spot 22 moves clockwise. Counterclockwise movement is also possible.

[0080] The four laser spots 22 are arranged in a rectangular (square) configuration. This configuration is assumed to be able to rotate during the movement of the laser spots 22, particularly around the optical axis. The four laser spots 22 are also assumed to be able to move translationally. In particular, the relative positions of the laser spots 22 to each other may be fixed or unchanging.

[0081] Each of the four laser spots 22 moves along a path 30 in this case. In other words, each of the four laser spots 22 moves along its own path 30. For clarity, the four paths 30 are shown in Figure 1 only by dashed lines.

[0082] In this case, the paths 30 overlap. It is also possible that the paths 30 do not overlap.

[0083] The path 30 extends in a circular shape across the first end face 14 and the second end face 20. Each of the paths 30 is assumed to have an elliptical range.

[0084] In this case, the laser spot 22 also moves across the gap 15. Because the laser spots 22 are spaced apart, not all of the laser spots 22 enter the gap 15 at the same time. In other words, at least one laser spot 22 is always at least partially positioned on the first end face 14 or the second end face 20.

[0085] Figure 2 illustrates the movement of the laser spot 22 according to a second exemplary embodiment. The second exemplary embodiment differs from the first exemplary embodiment shown in Figure 1 in the following manner.

[0086] The four laser spots 22 are moved along a common, circular path 30. The laser spots 22 are positioned at equal distances (or evenly spaced) from each other and distributed along the common path 30.

[0087] Figure 3 illustrates the movement of the laser spot 22 according to a third exemplary embodiment. The third exemplary embodiment differs from the first exemplary embodiment shown in Figure 1 in the following way.

[0088] Each of the four laser spots 22 moves along a path 30, which in this case is circular. Each path 30 extends only over either the first end face 14 or the second end face 20.

[0089] In this case, two paths 30 run on the first end face 14, and two further paths 30 run on the second end face 20. In this case, the paths 30 do not run over the gap 15. The paths 30 do not intersect or come into contact with each other. The paths 30 are spaced apart from each other.

[0090] Since path 30 does not pass over gap 15, each laser spot 22 also does not move over gap 15. Therefore, the two laser spots 22 move only over the first end face 14, and the two further laser spots 22 move only over the second end face 20.

[0091] In particular, the laser spot 22 always maintains a constant distance from the edge 17. The laser spot 22 can be kept at a constant distance from the gap 15. This prevents (or at least reduces) the possibility of the laser spot 22 entering the gap 15. Figure 4 schematically shows a plan view of the laser spot 22. This can be one of the laser spots 22 shown in Figures 1-3.

Claims

1. A method for laser welding at least two conductive pieces (10, 16), - A step of providing an elongated first conductor piece (10) having a first end (12) and a first end face (14), - A step of providing an elongated second conductor piece (16) having a second end (18) and a second end face (20), wherein the first end face (14) is positioned adjacent to the second end face (20), - At least two, and in particular at least four laser spots (22), - The laser spot (22) each has a core region (24) that is particularly circular and a ring region (26) that is particularly annular, and the average laser power density of the core region (24) is higher than the average laser power density of the ring region (26), the step of generating the laser spot (22) on the first end face (14) and / or the second end face (20), A method comprising the step of moving the laser spot (22) such that the laser spot (22) generates a common molten pool (28) that extends at least partially, and in particular fully, over the first end face (14) and the second end face (20).

2. The method according to claim 1, characterized by the step of moving each of the laser spots (22) along a path (30), each of which the path (30) extends over the first end face (14) and the second end face (20), and in particular, the cross-section of each of the path (30) is straight, circular, and / or elliptical.

3. The method according to claim 1, characterized by the step of moving each of the laser spots (22) along a path (30), each of which the path (30) extends only on the first end face (14) or the second end face (20), and in particular the cross-section of each of which the cross-section is straight, circular, and / or elliptical.

4. The method according to any one of claims 1 to 3, characterized in that the laser spot (22) is moved by a scanner optical system.

5. The method according to any one of claims 1 to 4, characterized in that at least two, and in particular all, laser spots (22) are similarly designed.

6. The method according to any one of claims 1 to 5, characterized in that the ring regions (26) of at least two, in particular all, laser spots (22) overlap each other.

7. The method according to any one of claims 1 to 6, characterized in that at least two, in particular all, of the core regions (24) of the laser spots (22) are spaced apart from each other, and in particular the distance between the laser spots (22) is at least 20% of the laser spot diameter.

8. The method according to any one of claims 1 to 7, characterized in that at least two laser spots (22), in particular all of the laser spots (22), are generated by optical multifibers, in particular 2-in-1 fibers.

9. The aforementioned method, The method according to any one of claims 1 to 8, characterized by comprising the step of varying, in particular the step of vibrating, the average laser power density of the at least one laser spot in the core region (24) and / or ring region (26) of the at least one laser spot (22).

10. The method according to any one of claims 1 to 9, characterized in that at least two, in particular all, laser spots (22) are each generated by a laser beam, and the laser beams are guided parallel to each other.

11. The aforementioned method, - The method according to any one of claims 1 to 10, characterized by including the step of moving the laser spot (22) by rotational motion around the optical axis.

12. An arrangement of at least two conductive pieces (10, 16) integrally connected to each other, wherein the integral connection is generated by the method according to any one of claims 1 to 11.

13. A device for laser welding of at least two conductive pieces (10, 16), - A laser source configured to produce laser spots (22) having at least two, and in particular at least four, laser spots (22), each of which has a core region (24) that is particularly circular and a ring region (26) that is particularly annular, wherein the average laser power density of the core region (24) is higher than the average laser power density of the ring region (26), A device comprising a control unit for controlling the device, wherein the device and / or the control unit are configured to perform the method according to any one of claims 1 to 11.

14. A computer-readable storage medium comprising a command, wherein, when executed by a computer, the command causes the computer to perform the method according to at least one of claims 1 to 11.

15. A computer program comprising a command, wherein, when the computer program is executed by a computer, the command causes the computer to perform the method according to at least one of claims 1 to 11.

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