METHOD AND DEVICE FOR LASER WELDING CONDUCTOR WIRES

Abstract

The present invention relates to a method for laser welding conductor wires (5, 7), in particular conductor wires (5, 7) arranged in slots (2) of a core (3) of a dynamo electric machine, such as a stator core, to form a winding and a device (35) for laser GC welding conductor wires (5, 7). A first end (4) of a first conductor wire (5) and a second end (6) of a second conductor wire (7) are arranged adjacent to each other. A laser beam is applied to a first end surface (8) of the first conductor wire (5) and a second end surface (10) of the second conductor wire (7) to weld together the first end (4) of the first conductor wire (5) and the second end (6) of the en second conductor wire (7). The first end surface (8) and the second end surface (10) point upwards, preferable the first end surface (8) and the second end surface (10) are axial end surfaces. A laser beam (31) is applied in a first substantially closed path (21) within the first end surface (8) to form a first molten pool (25). The laser beam (31) is applied in a second substantially closed path (22) within the second end surface (10) to form a second molten pool (26). The laser beam (31) is applied in a third substantially closed path (23) to the first end surface (8) and to the second end surface (10) connecting the first and second molten pool.

Claims

1-10. (canceled)

11. A method for laser welding conductor wires to form a winding, wherein a first end of a first conductor wire and a second end of a second conductor wire are arranged adjacent to each other, and a laser beam is applied to a first end surface of the first conductor wire and a second end surface of the second conductor wire to weld together the first end of the first conductor wire and the second end of the second conductor wire, the first end surface, and the second end surface, the method comprising: applying a laser beam in a first substantially closed path within the first end surface to form a first molten pool; and after applying the laser beam in the first substantially closed path, performing, in either order: (a) applying the laser beam in a second substantially closed path within the second end surface to form a second molten pool; and (b) applying the laser beam in at least one of (1) a path starting at the first molten pool and extending to the second end surface, and (2) a third substantially closed path extending over the first end surface and the second end surface; wherein: the first and second molten pools are connected by the at least one of (1) the path starting at the first molten pool to the second end surface, and (2) the third substantially closed path extending over the first end surface and the second end surface.

12. The method according to claim 11, wherein the conductor wires are arranged in slots of a core of a dynamo electric machine.

13. The method according to claim 11, wherein the first end surface and the second end surface point upwards.

14. The method according to claim 11, wherein the first end surface and the second end surface are axial end surfaces.

15. The method according to claim 11, wherein after forming the first molten pool the laser beam is guided to the second end surface in a straight path.

16. The method according to claim 11, wherein at least one of the first closed path and the second closed path are circular.

17. The method according to claim 11, wherein the third path is elliptical.

18. The method according to claim 11, wherein any one or more of: the applying the laser beam in the first substantially closed path within the first end surface to form the first molten pool, the applying the laser beam in the second substantially closed path within the second end surface to form the second molten pool, the applying the laser beam in the path starting at the first molten pool and extending to the second end surface, or the applying the laser beam in the third substantially closed path extending over the first end surface and the second end surface, is repeated at least one time.

19. The method according to claim 11, further comprising applying the laser beam in a fourth substantially closed path to the first end surface and to the second end surface surrounding the first closed path, the second closed path and third closed path.

20. The method according to claim 19, wherein the fourth closed path is elliptical.

21. The method according to claim 11, wherein at least one of the cross-sectional area of the first end of the first conductor wire and the cross-sectional area of the second end of the second conductor wire get smaller towards the axial end.

22. A device for laser welding conductor wires to form a winding, for laser welding conductor wires to form a winding, wherein a first end of a first conductor wire and a second end of a second conductor wire are arranged adjacent to each other, and a laser beam is applied to a first end surface of the first conductor wire and a second end surface of the second conductor wire to weld together the first end of the first conductor wire and the second end of the second conductor wire, the first end surface, and the second end surface, the device comprising: at least one laser tool for one or more of generating or applying a moveable laser beam to a first end surface of a first conductor wire and a second end surface of a second conductor wire for welding together the first end of the first conductor wire and the second end of the second conductor wire; and a control unit having an output in operative connection with the laser tool; wherein: the control unit is configured for controlling the laser tool to cause the laser tool to apply the laser beam in a first substantially closed path within the first end surface to form a first molten pool, and the control unit is further configured to cause the device to perform, in either order after applying the laser beam in the first substantially closed path, one or more of the following: (a) applying the laser beam in a second substantially closed path within the second end surface to form a second molten pool; and (b) applying the laser beam in at least one of (1) a path starting at the first molten pool and extending to the second end surface, and (2) a third substantially closed path extending over the first end surface and the second end surface; wherein: the first and second molten pools are connected by the at least one of (1) the path starting at the first molten pool to the second end surface, and (2) the third substantially closed path extending over the first end surface and the second end surface.

23. The device according to claim 22, wherein the control unit is configured for controlling the laser tool to cause the laser tool to apply the laser beam in a fourth substantially closed path to the first end surface and to the second end surface surrounding one or more of the first closed path, the second closed path, or third closed path.

Description

[0108] FIG. 1 a perspective view of a part of a stator;

[0109] FIG. 2 a schematic drawing of welding paths;

[0110] FIG. 3 a schematic drawing of a device.

[0111] FIG. 1 shows a part of a stator 1 in a perspective view. Conductor wires 5, 7 are arranged in slots 2 of a stator core 3. Pairs of conductor wires 5, 7 have to be connected to form a stator winding.

[0112] The stator core 3 is arranged such that the direction of the stator axis A is aligned with the gravitational vector.

[0113] A first end 4 of a first conductor wire 5 and a second end 6 of a second conductor wire 7 are arranged adjacent to each other in radial direction.

[0114] A first end surface 8 of the first conductor wire 5 and a second end surface 10 of the second conductor wire 7 point upwards.

[0115] A laser beam 31 (see FIG. 3) is applied to the first end surface 8 and the second end surface 10 to weld together the first end 4 of the first conductor wire 5 and the second end 6 of the second conductor wire 7.

[0116] FIG. 2 is a schematic drawing of welding paths 20, 21, 22, 23, 24.

[0117] In a first step (i) a laser beam 31 (see FIG. 3) is applied within the first end surface 8 in a first circular path 21. The circular path 21 is repeated for several times. Once a first molten pool 25 (see FIG. 3) is formed, the laser beam 31 (see FIG. 3) is moved to the second end surface 10 via a straight path 20, while the laser beam 31 is still applied.

[0118] In a second step (ii) the laser beam 31 (see FIG. 3) is applied in a second circular path 22 within the second end surface to form a second molten pool 26 (see FIG. 3).

[0119] In a further step (iv) the laser beam 31 (see FIG. 3) is applied in a third elliptical path 23 to the first end surface 8 and to the second end surface 10 connecting the first and second molten pool and welding together a first radial surface 9 of the first conductor wire 5 and a second radial surface 11 of the second conductor wire 7.

[0120] The third elliptical path may be repeated for at least 1-2 times to increase the depths of penetration of the molten pool in the area of the first radial surface 9 and the second radial surface 11.

[0121] The laser beam 31 (see FIG. 3) is then guided to a fourth elliptical path 24 along a straight path 28. The laser beam 31 (see FIG. 3) is applied to the fourth elliptical path 24 to complete the welding. The fourth elliptical path may be repeated for several times, for example for 4-5 times.

[0122] FIG. 3 shows a schematic drawing of a device 35 according to the invention.

[0123] The device 35 comprises a laser tool 30 for generating and applying a moveable laser beam 31 to the first end surface 8 of the first end 4 of the first conductor wire 5 and the second end surface 10 of the second end 8 of the second conductor wire 7. The device 35 further comprises a control unit 32 having an output line 33 connected to the laser tool 30. The control unit 32 is configured for controlling the laser tool 30 which is arranged above the first end surface 8 and to the second end surface 10 such that the laser beam 31 is applied to the first end surface 8 and to the second end surface 10 in paths as shown in FIG. 2.

[0124] The first end 4 of the first conductor wire 5 and the second end 6 of the second conductor wire 7 are tapered.

[0125] Thus, the cross-sectional area 27 gets smaller is axial direction A toward the axial end.

[0126] Thus, there is a gap 29 between the first radial side surface 9 and the second radial side surface 11.

[0127] Until a first molten pool 25 is achieved, the laser beam 31 is not passed through the gap 29, thus avoiding reaching areas having a greater distance to the laser tool 30 and where there is no well-defined power input.

[0128] This method allows to weld also conductor wires 5, 7 that are not perfectly in contact with each other. At least one well defined molten pool 25 may be generated and from there molten material may be transported towards the other conductor wire.

[0129] This is particularly advantageous in the welding of conductor wires 5, 7 where the ends 4, 6 are very distant from each other.

[0130] A process of this type is more controlled because it may be de-cided how much of melted material is generated in the molten pools 25, 26 before establishing a connection between the molten pools 25, 26.

[0131] A fiber laser may be used providing a wavelength of 1000 nm. The laser beam may be moved with a velocity of 150-350 mm/s.