Method for producing an annular winding head support, and winding head support

Abstract

The invention relates to a method for producing an annular winding head support for a rotor (1) of a rotating electric machine. The aim of the invention is to be able to produce a winding head support in a simple manner also for particularly large machines. To this end, it is provided according to the invention that ring segments (6) are formed, wherein the ring segments (6) are connected to a ring (2) forming the winding head support. The invention also relates to an electric machine comprising a stator and a rotor (1), the rotor (1) having at least one winding head on the end side, wherein a winding head support is provided in order to absorb centrifugal forces occurring during operation.

Description

[0001] Method for producing an annular winding head support and winding head support

[0002] The invention relates to a method for producing an annular winding head support for a rotor of a rotating electrical machine.

[0003] Furthermore, the invention relates to a winding head support for a rotor of an electrical machine comprising at least one ring.

[0004] Winding head supports for rotors of electrical machines and methods for manufacturing them are known from the prior art. Such winding head supports are used to absorb the centrifugal forces acting on a winding head of the rotor due to rotation, thus preventing undue deformation of the winding head. Winding head supports of the prior art are generally formed from a high-strength material, usually a high-strength, non-magnetizable steel, and often have one or more rings, as described, for example, in document AT 508622 A1. Such rings are typically formed by forging and rolling, and optionally by other processes to achieve particularly high strength.

[0005] However, such winding head supports can only be manufactured up to a maximum size specified by a given rolling device. Furthermore, the maximum size of such winding head supports is also limited by the transport distance from a production facility to a location where the electrical machine is to be operated, usually a power plant. Thus, to date, winding head supports can only be manufactured up to a maximum inner diameter of approximately 6 m, which can also become a limiting factor in machine design.

[0006] This is where the invention comes in. The object of the invention is to provide a method of the type mentioned above, with which a winding head support can be produced independently of limitations imposed by a forging or rolling device. Furthermore, such a winding head support is to be specified.

[0007] The first object is achieved according to the invention by a method of the type mentioned at the outset, in which ring segments are formed, after which the ring segments are connected to form a ring forming the winding head support.

[0008] Within the scope of the invention, it was recognized that by producing corresponding ring segments, forging or rolling equipment suitable for producing complete rings with the corresponding diameter is no longer required; instead, it is sufficient to provide equipment with which only the ring segments are formed. The ring segments can, in principle, be produced in any manner known from the prior art, for example, by machining or forming. It is also possible in principle to connect the individual ring segments in any manner known from the prior art, in particular by form-fitting, force-fitting, or material-fitting.

[0009] The individual ring segments no longer extend around the entire circumference of the ring, but each form only a portion of the circumference, making them very easy to manufacture. Typically, the ring is divided into ring segments along planes, each plane containing a rotation axis of the ring.

[0010] To achieve particularly high efficiency and ensure the manufacturability of a corresponding winding head support at low cost, it is preferred to use approximately identical ring segments. This achieves a high degree of component uniformity in production, enabling particularly simple manufacturing. Typically, one of the ring segments extends over a range of 20 degrees to 180 degrees of an entire ring, so that the ring can be formed, for example, from two to 18 ring segments with essentially identical dimensions.

[0011] Particularly preferably, two to ten, in particular three or four, ring segments are formed, each extending over equal parts of the circumference of the ring. It is understood that a circumferential area covered by a ring segment corresponds to the entire circumference of the ring divided by the number of ring segments; with three segments, this corresponds to approximately 120 degrees per ring segment.

[0012] It is advantageous if the ring segments are formed from plate-shaped elements by forming, in particular by cold forming, preferably by bending. Production can then be achieved, for example, by first cutting sheets with appropriate external dimensions from a plate-shaped material, such as a sheet of appropriate thickness and material, after which the sheets are formed, usually by cold forming or bending, in order to transform the initially approximately flat sheets into corresponding circular segments with a radius corresponding to the winding head support to be formed. The forming process can result in additional hardening, in particular work hardening.

[0013] In principle, the ring segments can be made of any material suitable for absorbing the mechanical and thermal loads occurring in a winding head support, such as a metal, a composite material, or a fiber composite material. It is particularly preferred that the ring segments comprise or consist of a steel, in particular austenitic steel. A non-magnetizable steel is typically used to avoid electrical losses in the winding head whenever possible.

[0014] As stated, the ring segments can be connected to form the ring in a variety of ways. Particularly when the ring segments are made of steel, such as austenitic steel, it is preferred that the ring segments be connected by welding. This connection can be achieved by both fusion welding and pressure welding, such as friction stir welding.

[0015] To achieve particularly high strength of the winding head support, heat treatment can be performed after joining the ring segments. During heat treatment, stresses introduced by the preceding process steps can also be reduced, for example, through stress relieving.

[0016] In particular, to reduce any remaining imbalance or to achieve a maximum tolerable imbalance, it is advantageous if the ring is machined after joining the ring segments, especially after heat treatment, in order to achieve defined dimensions. The ring formed by the joined ring segments or the winding head support can be machined for this purpose, for example, by turning and / or milling.

[0017] A winding head support according to the invention can basically be used for electrical rotating machines of very different sizes. Such a winding head support is particularly advantageously used on particularly large machines, especially since it can easily avoid problems that would otherwise arise with correspondingly large, one-piece rings during production and transport. It is therefore preferably provided that the ring segments and the ring have an inner radius of more than 0.5 m, preferably more than 2 m, in particular more than 3 m. This makes it easy to form rings with an inner diameter of, for example, 6 m or more. Depending on the transport route to a system on which the corresponding electrical machine is to be used, it can also be provided that the individual ring segments are only joined together on site to form a ring or ring.be assembled to form a winding head support so that they can be transported to the system individually and thus in a space-saving manner.

[0018] The further object is achieved according to the invention by a winding head support of the type mentioned above, in which the ring is formed by connected ring segments. It is particularly preferred that the winding head support be manufactured using a method according to the invention.

[0019] Such a winding head support is particularly easy to manufacture compared to winding head supports of the prior art and, in particular, does not require forging and rolling equipment designed to produce one-piece rings with a corresponding diameter.

[0020] It is preferably provided that the ring segments are connected by welding.

[0021] It is advantageous if the winding head support has at least one ring with an inner diameter of more than 1 m, in particular more than 4 m, preferably more than 6 m.

[0022] In an electrical machine with a stator and a rotor, the rotor having a winding head on one side, with a winding head support provided to absorb centrifugal forces occurring during operation, it is preferably provided that the winding head support is designed according to the invention. Particularly preferably, all annular winding head supports of the machine are designed according to the invention.

[0023] It is understood that the winding head support or the ring is arranged on the rotor in such a way that a rotation axis of the ring essentially coincides with a rotor axis.

[0024] Further features, advantages, and effects of the invention will become apparent from the following exemplary embodiments. Reference is made to the drawings, which show:

[0025] Fig. 1 shows an electrical machine designed as an asynchronous machine;

[0026] Fig. 2 shows a winding head support of the prior art;

[0027] Fig. 3 and 4 winding head supports according to the invention;

[0028] Fig. 5 is a flow chart of a method according to the invention.

[0029] Fig. 1 shows a rotor 1 of an electrical machine, designed here as an asynchronous machine, which can be used, for example, in a hydroelectric power plant as a motor or generator. The rotor 1 has a rotor shaft and a rotor core 3 in which a rotor winding is arranged. The rotor winding projects beyond the rotor core 3 at the end, forming winding heads. In order to support the winding heads against centrifugal forces occurring during operation due to rotation of the rotor 1 about a rotor axis 4, ring-shaped winding head supports are provided. The winding head supports can have an outer ring and an inner ring, whereby only the rings 2 of the winding head support, designed as outer rings, are visible in Fig. 1. A basic structure of a winding head support with an outer ring and an inner ring is known, for example, from document AT 508622 A1.

[0030] Fig. 2 shows a detailed view of an approximately hollow-cylindrical ring 2 of a winding head support of the prior art, which could be used, for example, as an outer ring in the rotor 1 shown in Fig. 1. As can be seen, this winding head support is formed in one piece. The production of such rings 2 is associated with considerable effort, particularly for rotors 1 with large diameters, and generally requires appropriately dimensioned rolling and forging equipment. Transporting such rings 2 is also only possible with considerable effort.

[0031] 3 and 4 show winding head supports according to the invention, wherein the winding head support shown in Fig. 3 is designed in three parts and the winding head support shown in Fig. 4 is designed in four parts. As can be seen, the winding head support, which is again approximately hollow-cylindrical or annular, consists of several ring segments 6 of equal size, which are connected to form a ring 2. The individual ring segments 6 each extend around a portion of a circumference of the ring 2, which portion corresponds to a total circumference divided by the number of ring segments 6. Accordingly, the ring segments 6 shown in Fig. 3 each extend over approximately 120 degrees, and the ring segments 6 shown in Fig. 4 each extend over approximately 90 degrees. As a result, these ring segments 6 are easier to manufacture and can be transported in a smaller space than the finished ring 2.

[0032] Typically, the individual ring segments 6 are formed by cold forming from austenitic, high-strength, and non-magnetic sheets, so that these sheets have a corresponding radius, which in the case of the winding head supports shown in Figs. 3 and 4 can be, for example, 3 m or more, in order to form a ring 2 with an inner diameter 7 of, for example, 6 m. The individual ring segments 6 are then connected, usually by welding, after which heat treatment and final mechanical processing can be carried out. Accordingly, Figs. 3 and 4 show weld seams 5 on the contact surfaces between the ring segments 6, which weld seams 5 run approximately parallel to the rotor axis 4, which corresponds to an axis of the ring.

[0033] Fig. 5 shows a flow diagram of a method according to the invention for producing a winding head support such as those shown in Figs. 3 and 4. In a first method step S1, flat, plate-shaped elements or sheets are cut from an austenitic, non-magnetic, and high-strength steel, for example by laser cutting. After that, in a second method step S2, the cut sheets are formed by rolling, bending, and / or cold forming until they have a desired radius of, for example, 3 m for a ring 2 with an inner diameter 7 of 6 m. During the forming process, the material can also be further hardened.

[0034] In a next, third process step S3, the individual ring segments 6 are connected by welding to form the ring 2. Division planes that divide the ring 2 into the individual ring segments 6 typically contain the rotor axis 4, which is why the weld seams 5 typically run parallel to the rotor axis 4. However, other division planes, such as inclined ones, are also possible.

[0035] In a further, fourth process step S4, the ring 2 is heat-treated, which depends on the material used, usually an austenitic, non-magnetic, high-strength steel.

[0036] In a further, fifth process step S5, a final mechanical processing is carried out in order to achieve exact dimensions of the winding head support and, in particular, to reduce imbalance.

[0037] It is understood that the individual process steps can be implemented both in a production plant and on-site at a construction site where a power plant with an electrical machine is located, where the rings 2 are to be used as winding head supports. Of course, it is also possible to perform only some of the process steps in a production facility and, for example, to carry out a connection of the individual ring segments 6 and the subsequent process steps at a single site in order to reduce the dimensions of the objects to be transported.

[0038] With a winding head support produced according to the invention, it is particularly possible to form particularly large rotors 1 for electrical machines such as asynchronous machines, especially since, in contrast to one-piece winding head supports, no devices are required which enable the production of components which have a size corresponding to a diameter of the rotor 1.

[0039] It is therefore particularly possible to manufacture winding head supports with a diameter of 6 m or more in a particularly simple manner. Furthermore, winding head supports manufactured according to the invention can also be formed on-site at a construction site, making transport even over difficult terrain easy, especially since only the individual ring segments 6, but not the entire winding head support with a correspondingly large diameter, need to be transported.

Claims

Patent claims 1. Method for manufacturing an annular winding head support for a rotor (1) of a rotating electrical machine, characterized in that ring segments (6) are formed, after which the ring segments (6) are joined to form a ring (2) forming the winding head support.

2. Method according to claim 1, characterized in that approximately identical ring segments (6) are used.

3. Method according to claim 1 or 2, characterized in that two to ten, in particular three or four, ring segments (6) are formed, each of which extends over equal parts of a circumference of the ring (2).

4. Method according to one of claims 1 to 3, characterized in that the ring segments (6) are formed from plate-shaped elements by forming, in particular by cold forming, preferably by bending.

5. Method according to one of claims 1 to 4, characterized in that the ring segments (6) comprise or consist of a steel, in particular an austenitic steel.

6. Method according to one of claims 1 to 5, characterized in that the ring segments (6) are joined by welding.

7. Method according to one of claims 1 to 6, characterized in that a heat treatment is carried out after joining the ring segments (6).

8. Method according to one of claims 1 to 7, characterized in that the ring (2) is mechanically machined after joining the ring segments (6), in particular after heat treatment, especially by a machining process, in order to achieve defined dimensions.

9. Method according to one of claims 1 to 8, characterized in that the ring segments (6) and the ring (2) have an inner radius of more than 0.5 m, preferably more than 2 m, in particular more than 3 m.

10. Winding head support for a rotor (1) of an electric machine comprising at least one ring (2), characterized in that the ring (2) is formed by connected ring segments (6), in particular manufactured according to a method according to one of claims 1 to 9.

11. Winding head support according to claim 10, characterized in that the ring segments (6) are connected by welding.

12. Winding head support according to claim 10 or 11, characterized in that the winding head support has at least one ring (2) with an inner diameter (7) of more than 1 m, in particular more than 4 m, preferably more than 6 m.

13. Electric machine with a stator and a rotor (1), wherein the rotor (1) has at least one winding head at its end, wherein a winding head support is provided to absorb centrifugal forces occurring during operation, characterized in that the winding head support is designed according to one of claims 10 to 12.

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