PRODUCING A ROTOR BY MEANS OF ADDITIVE MANUFACTURING

Abstract

The invention relates to a method for producing a rotor of an electric machine, which rotor is preferably designed as a squirrel-cage rotor. The end rings and/or squirrel-cage bars are produced by means of a metal powder application method. The invention further relates to an end ring for a rotor of an electric machine, said end ring in particular being produced by means of said method.

Claims

1.-16. (canceled)

17. A method for producing a rotor of an electric machine, said method comprising: arranging a rotor core concentrically to a rotor axis; forming the rotor core at an axial end of grooves in the rotor core with an annular recess in concentric relation to the rotor axis for connecting the grooves; and creating a short-circuit ring by filling the grooves and the annular recess through an additive manufacturing process with an electrically conducting material based on a material mixture of a material with a first strength and a material with a second strength which is higher than the first strength, with a smooth material transition from the material with the first strength to the material with the second strength being created in an axial direction and/or radial direction of the short-circuit ring such that a material strength increases from an inner radius to an outer radius of the short-circuit ring, wherein the additive manufacturing process establishes in the short-circuit ring a retaining structure or a lattice which is made of the material with the second strength.

18. The method of claim 17, wherein the additive manufacturing process includes a metal powder application process.

19. The method of claim 17, wherein the electrically conducting material is copper or aluminum or alloys thereof.

20. The method of claim 17, wherein the grooves are filled with premanufactured material and the annular recess is filled by a metal powder application process for creating the short-circuit ring.

21. The method of claim 17, wherein an opening and/or a cavity and/or a channel is left in the short-circuit ring as the annular recess is filled with the electrically conducting material.

22. The method of claim 17, wherein the retaining structure or the lattice in the short-circuit ring is made of titanium or steel.

23. The method of claim 17, wherein the short-circuit ring has a surface structure.

24. The method of claim 23, wherein the surface structure is configured in the form of a blade and/or a balancing element.

25. The method of claim 17, further comprising joining the short-circuit ring by a material-fit connection to a shaft.

26. The method of claim 17, wherein the material with the first strength is copper or aluminum and the material with the second strength is steel or titanium.

27. A rotor of an electric machine, comprising: a rotor core arranged concentrically to a rotor axis, said rotor core having grooves and an annular recess at each axial end of the grooves in concentric relation to the rotor axis for connecting the grooves; and a short-circuit ring formed by filling the grooves and the annular recess with electrically conducting material using an additive manufacturing process with a material mixture of a material with a first strength and a material with a second strength which is higher than the first strength, said short-circuit ring having openings left therein.

28. The rotor of claim 27, wherein the openings are configured as slots.

29. The rotor of claim 27, wherein the short-circuit ring has cavities and/or channels.

30. The rotor of claim 27, wherein the material with the first strength is copper or aluminum, and the material with the second strength is steel or titanium.

31. The rotor of claim 27, wherein the short-circuit ring has a material transition from the material with the first strength to the material with the second strength in an axial direction and/or radial direction of the short-circuit ring.

32. The rotor of claim 27, wherein the short-circuit ring includes a retaining structure or a lattice formed by the additive manufacturing process of the material with the second strength.

33. The rotor of claim 32, wherein the retaining structure or the lattice is made of titanium or steel.

34. The rotor of claim 27, wherein the short-circuit ring has a surface structure in the form of a blade and/or a balancing element.

35. The rotor of claim 27, further comprising a shaft joined to the short-circuit ring by a material-fit connection and made of steel.

36. An electric machine, comprising a rotor, said rotor comprising a rotor core arranged concentrically to a rotor axis, said rotor core having grooves and an annular recess at each axial end of the grooves in concentric relation to the rotor axis for connecting the grooves; and a short-circuit ring formed by filling the grooves and the annular recess with electrically conducting material using an additive manufacturing process with a material mixture of a material with a first strength and a material with a second strength which is higher than the first strength, said short-circuit ring having openings left therein.

Description

[0032] The invention is described and explained in more detail below on the basis of the exemplary embodiments shown in the figures, in which:

[0033] FIG. 1 shows an embodiment of a rotor joined to a shaft, which rotor includes a rotor core and two short-circuit rings,

[0034] FIG. 2 shows an embodiment of the rotor core, which has grooves,

[0035] FIG. 3 shows an embodiment of the rotor joined to the shaft, wherein the two short-circuit rings have openings,

[0036] FIG. 4 shows an embodiment of a material gradient in the short-circuit ring, wherein the transition between the materials is smooth,

[0037] FIG. 5 shows an embodiment of the short-circuit ring provided with at least one cavity and at least one channel,

[0038] FIG. 6 shows the procedure of the manufacturing method.

[0039] FIG. 1 shows an embodiment of a rotor joined to a shaft 1, which has a rotor core 3 and a short-circuit ring 2 at each of its axial ends. In addition, the axial direction 6 and the radial direction 7 are shown, as well as the inner radius 14 and the outer radius 15 of the short-circuit ring. Preferably, the rotor is designed as a squirrel-cage rotor and comprises squirrel-cage bars, which extend in the axial direction 6 or obliquely substantially in the axial direction 6, as well as short-circuit rings 2 on the axial ends of the squirrel-cage bars, which short-circuit said bars. According to the invention, it is possible for only the squirrel-cage bars or only the short-circuit rings 2 or the squirrel-cage bars and the short-circuit rings 2 to be manufactured by means of the MPA method. Advantageously, the squirrel-cage bars are premanufactured, preferably from copper or aluminum, and inserted into the rotor core 3 and subsequently the short-circuit rings 2 are affixed by means of an MPA method. A short-circuit ring 2 produced by means of the MPA method offers the advantage that cavities, channels and openings can be inserted in particular. A material gradient is also possible, in which a transition between two materials with different strength is brought about in the axial 6 and/or radial direction 7.

[0040] FIG. 2 shows an embodiment of the rotor core 3, which is joined to a shaft 1 and has grooves 4 in the axial direction 6. The grooves can be filled with premanufactured squirrel-cage bars and subsequently the short-circuit rings are affixed via the MPA method.

[0041] FIG. 3 shows an embodiment of the rotor joined to the shaft 1. The short-circuit rings 2 are provided with openings 5, which are preferably designed as slots, and serve for cooling purposes.

[0042] FIG. 4 shows an embodiment of a material gradient in a short-circuit ring 2, in which a transition from a material with a first strength, in particular copper or aluminum, to a material with a higher strength compared to the first, in particular steel or titanium, is created in the radial direction 7 (see FIG. 1). At the inner radius 14 of the short-circuit ring 2, which borders on the shaft 1, an electrically conductive material such as copper is attached in order to short-circuit the squirrel-cage bars introduced into the grooves. At the outer radius 15, material is introduced which is resistant to centrifugal forces, such as steel. In FIG. 5, a smooth transition 11 between the two materials 8 and 9 is shown. A material gradient which has a smooth transition 11 of two or more materials 8 and 9 is also possible in the axial direction 6. Since the short-circuit rings 2 are affixed to the respective axial ends of the rotor by means of the MPA method, a material-fit connection to the shaft 1 is possible.

[0043] FIG. 5 shows an embodiment of the short-circuit ring 2 provided with cavities 12 and channels 13. The cavities are situated particularly closer to the outer radius 15 than to the inner radius 14, in order to shift the center of mass close to the shaft 1 and thus to reduce centrifugal forces. The channels are particularly well-suited for use as thermosiphons, in order to preferably benefit the heat flow in the direction of the shaft 1.

[0044] FIG. 6 describes a procedure of a manufacturing method for a rotor according to the invention of an electric machine. In accordance with one preferred type of production of the rotor designed as a squirrel-cage rotor, a rotor lamination, which possesses grooves, is provided in method step S1. Subsequently in method step S2, copper bars, which have already been premanufactured, are inserted into the available grooves. These fulfill the function of the squirrel-cage bars of the squirrel-cage rotor. Following this, in method step S3, short-circuit rings are affixed to the axial ends of the squirrel-cage bars by means of an MPA method.