STATOR LAMINATE PACK WITH PRINTED EXTENSION

Description

[0001] The present invention relates to a laminated core for an electrical machine having a base element comprising a series of base dynamo laminations and a plurality of teeth distributed around its circumference, each for supporting a winding. Furthermore, the present invention relates to an electrical machine and a machine family comprising such a laminated core. Furthermore, the present invention also relates to a method for producing a laminated core for an electrical machine by punching or cutting out base dynamo laminations and forming a base element by arranging the punched or cut-out base dynamo laminations in a row, wherein the base element has a plurality of teeth distributed around its circumference, each for supporting a winding.

[0002] Electrical machines such as motors and generators typically have a stator with a laminated core. The laminated core usually has numerous teeth for individual windings and an annular yoke connecting all the teeth. Such a laminated core is typically composed of a multitude of laminations punched or cut from a high-permeability electrical or dynamo core.

[0003] Typically, each motor type requires a separate stator lamination cut. Each stator lamination is punched out according to the lamination cut. With a large number of motor types, this results in an equally large number of lamination cut variations that need to be punched. One reason for this is that different stator lamination cuts are required for different shaft heights and different designs (power, harmonics, etc.). Handling this large number of stator lamination cuts can pose a particular logistical challenge. A further challenge can arise if a fixed cooling concept is to be provided for lamination-cut-dependent cooling. Other problems could also arise for the large number of motor types with their own lamination cut.If the variance of the sheet metal cuts to be punched could be reduced for a large number of motor types, this would be advantageous, among other things, with regard to the changeover times of the punching tools. JP 2007325353 A, JP 2015171193 A, and EP 3076526 A1 describe a laminated core for an electrical machine to which no elements have been added by additive processes.

[0004] The object of the present invention is therefore to keep the number of sheet metal cuts for the stators of different types of electrical machines as low as possible.

[0005] According to the invention, this object is achieved by a laminated core and a method for producing a laminated core according to independent claims 1 and 14. Advantageous developments of the invention emerge from the subclaims.

[0006] According to the invention, a laminated core for an electrical machine is provided, comprising a base element comprising a series of basic dynamo laminations and a plurality of teeth distributed around its circumference, each of which supports a winding. The electrical machine is preferably an electric motor or a generator. The laminated core can be a stator laminated core or a rotor laminated core. The laminated core can also be a component of an active part of a linear motor.

[0007] The laminated core primarily comprises a "base element," which represents the actual stack of dynamo laminations. Within it, so-called "base dynamo laminations" are arranged in a row or stack. The base element thus comprises a stack of base dynamo laminations, each of which is a dynamo lamination, for example, punched out in a similar manner. The name "base dynamo lamination" simply means that it forms the "base element." The laminated base element has several teeth, each of which is intended to support a winding. These teeth can, for example, be evenly distributed around the circumference of the base element. In general, the teeth can be distributed on one active side of the base element. In principle, each tooth can have a tooth shank and a tooth tip, and optionally a specially shaped tooth root.The basic element represents the basic framework for the laminated core and has a high permeability and therefore a high magnetic quality due to the dynamo sheets.

[0008] In order to keep the number of sheet metal cuts for different types of electrical machines to a minimum, the basic idea of ​​the invention is to be able to use the base element for multiple types of electrical machines. Parts of the base element that are less magnetically important, such as edge regions, can be adapted or expanded using a 3D printing process or a general generative manufacturing process depending on the diameter of the electrical machine, efficiency, installation space, etc. For example, an extension section on one of the teeth of the base element can be formed onto the tooth using the generative manufacturing process. If necessary, the extension section can be completely surrounded by the base element or integrated into it. For example, the tooth shaft and / or a yoke back section and / or a tooth tip area can be supplemented or adapted using the extension section.

[0009] The extension section(s) can be inserted before and / or after packaging.

[0010] The generative manufacturing process can also be referred to as additive manufacturing or rapid prototyping. Based on data models, bodies are created or added from formless (liquids, gels, pastes, powders, and the like) or form-neutral (ribbon-shaped, wire-shaped, sheet-shaped, etc.) materials using chemical and / or physical processes.

[0011] According to one embodiment, the extension section consists of or has several individual sections, each of which is separately formed onto a respective one of the base dynamo sheets using the additive manufacturing process. This means that an individual section is pressed or formed onto each base dynamo sheet using the additive manufacturing process, and the several individual sections form the extension section by being arranged one after the other or stacked together. This allows the individual sections to be formed individually on each sheet. In particular, the thickness of the individual sections can be varied. For example, an additively formed individual section can have a different thickness than a base dynamo sheet. The thickness of an individual section can also decrease towards the outside, for example.

[0012] The extension section can be made of a magnetically conductive material or comprise magnetically conductive particles. In this way, the base element can be supplemented by one or more magnetically effective extension sections. If appropriate, the material is the same as the base dynamo sheets. Likewise, the magnetically conductive particles can be made of the same material as the base dynamo sheets. In principle, however, the material of the extension sections can also be non-magnetic, so that the extension section merely serves a supporting function. If appropriate, the material of the extension section can also be selected to possess special physical properties such as high thermal conductivity, low density, and so on.

[0013] In an advantageous embodiment, one of the teeth has a yoke section and, projecting therefrom, a tooth shaft, wherein the at least one extension section is formed on the yoke section and / or the tooth shaft. In this way, the shape of a tooth shaft can be changed and, in particular, widened. In particular, material can be applied to both sides of the tooth shaft so that it has a greater width. Alternatively or additionally, the yoke section of a tooth can also be changed, adapted, or supplemented. For example, the yoke section of one tooth can be connected to the yoke section of an adjacent tooth using the generative manufacturing process. In this way, for example, numerous yoke sections of many teeth can be connected to form an annular yoke.

[0014] Furthermore, it can be provided that one of the teeth has a tooth tip, and the extension section forms at least part of the tooth tip. In this case, a part of the tooth tip can simply represent the distal end of the tooth shaft without any special shaping. A specially shaped or complete tooth tip is then only created by the extension section, which, as part of the tooth tip, is molded onto another tooth tip part that is integrally connected to the tooth shaft. Depending on the type of electrical machine, different tooth tips can be generatively formed.

[0015] In a special development of the laminated core, a cooling channel can be formed in the extension section. This means that cooling channels are added to or added to the base element using the generative manufacturing process. For example, one or more cooling channels can be accommodated in the extension section. In particular, these can be round cooling channels, the diameter of which is selected as required. The extension section can also have any connecting components for a cooling system. In this case, the material of the extension section(s) is advantageously selected to have high thermal conductivity. In particular, the material can also be matched to the cooling medium.

[0016] According to a further embodiment of the laminated core, the yoke section and / or the toothed shaft each have a recess which is completely or partially filled by the extension section. For example, the base element can have a recess which, in one type of electrical machine, remains unfilled, for example for weight reasons. In one or more other types of electrical machine, the recess is filled by the extension section, possibly also with one or more cooling channels. The degree of filling can again depend on the type of electrical machine. The recess in the yoke section or the toothed shaft can be, for example, wedge-shaped, circular segment-shaped, or trapezoidal.

[0017] In particular, the recess can be arranged asymmetrically to a central axis of the respective tooth shaft. This means that it does not necessarily have to be symmetrical to the tooth center. Furthermore, the recess can also simply serve to improve mechanical stability for the extension section. For example, it is advantageous if the tooth shaft has a recess in and around which the material for a tooth tip is printed. It can also be provided that the one or more recesses have undercuts to create any form-fitting connections.

[0018] In a further advantageous embodiment, the recess is filled with several different materials. Generally, the extension section(s) can be printed or manufactured from several different materials. Such a material composition of the extension section can be adapted to the physical requirements of the laminated core.

[0019] According to a further embodiment, the extension section is designed as a fastening element. The fastening element can be used to fasten the laminated core, for example, to a housing wall. The fastening element can be easily adapted to the respective housing used. If the electrical machine is housingless, the fastening element, which was attached to the laminated core using the generative manufacturing process, can also be used to create a fastening option on a foundation, a support, and the like. In a further advantageous embodiment, a sensor can be embedded in the recess with the help of the extension section. For example, a magnetic sensor, a temperature sensor, and the like can be integrated into the laminated core. The extension section can serve purely as a holding element but also as a transmission element for heat or electromagnetic waves.

[0020] Furthermore, it can be provided that the yoke section of one of the teeth is directly adjacent to a further yoke section of another of the teeth, and the extended section forms a wedge between the yoke section and the further yoke section. For example, a stator lamination ring can be punched out of a linear sheet section, with the individual yoke sections only connected to one another by a narrow web. The adjacent yoke sections can then be bent around the respective web to form the respective ring-shaped sheet. The triangles that open up during bending can then be filled using the generative manufacturing process. This results in a mechanically stable ring sheet.

[0021] Furthermore, an electrical machine with a laminated core of the described type, in particular a stator laminated core, can be provided. The electrical machine can be specifically an electric motor and in particular a synchronous machine, an asynchronous machine, or a reluctance machine.

[0022] Furthermore, according to the invention, a machine family with at least two different machines of the type mentioned can be provided. The machine family therefore has a first electrical machine and a second electrical machine with the laminated core according to the invention, wherein both electrical machines have the same basic element but different extension sections. This means that both electrical machines are based on the same stamped laminated core, wherein different extension sections are formed onto the laminated cores. For example, the first electrical machine can have a thicker tooth shaft than the second electrical machine. In another example, in the first electrical machine, a recess is filled with cooling channels, whereas in the second electrical machine the recess is filled without cooling channels.However, the feature "different extension sections" also means that one electrical machine has an extension section but not the other. For example, the first electrical machine may not have a specially shaped tooth tip, while the second electrical machine has a specially shaped tooth tip at the distal end of the tooth shaft as an extension section. The same can also apply to the design of the tooth shaft. While no extension is generatively formed on the tooth shaft of one electrical machine, such an extension can be provided on the tooth shaft of the other electrical machine.

[0023] The above object is also achieved according to the invention by a method for producing a laminated core for an electrical machine by Punching or cutting out basic dynamo sheets and forming a basic element by arranging the punched or cut out basic dynamo sheets in a row, wherein the basic element has a plurality of teeth for carrying a respective winding, and by forming an extension section onto one of the teeth of the basic element by means of a generative manufacturing process.

[0024] The advantageous features and possible variations described above in connection with the laminated core also apply mutatis mutandis to the process according to the invention. In this case, the corresponding functional features of the laminated core represent the respective process features.

[0025] The present invention will now be explained in more detail with reference to the accompanying drawings, in which FIG 1 shows a stator lamination or a stator lamination stack in plan view; FIG 2 shows a tooth of a stator lamination with extension sections according to a first embodiment; FIG 3 shows a tooth of a stator lamination with extension sections according to a second embodiment; FIG 4 shows a tooth of a stator lamination with extension sections according to a third embodiment; FIG 5 shows a stator lamination with extension sections according to a fourth embodiment; FIG 6 shows a linear, punched sheet metal strip with several teeth; FIG 7 shows a detail of FIG 6 between two teeth and FIG 8a part of a stator ring made of the linear sheet of FIG 6 and inserted extension sections.

[0026] The exemplary embodiments described in more detail below represent preferred embodiments of the present invention. It should be noted that the individual features can be realized not only in the described feature combinations, but also in isolation or in other technically reasonable combinations.

[0027] To manufacture a laminated core, and in particular a stator laminated core for an electrical machine (e.g., an asynchronous machine, a synchronous machine, a reluctance machine, etc.), not only are (punched) sheets arranged circumferentially and / or axially to form a base element. In addition, parts of the laminated core are printed, for example, using a 3D printing process. Thus, one or more extension sections are formed onto the base element using a generative manufacturing process.

[0028] In this way, a high variety of engine types, for example, can be provided without the manufacturer having to increase the variance of the punched sheet metal cuts. This results in the advantage of uniform sheet metal cuts for different axle sizes or for a certain range of axle heights (e.g., axle heights 15 to 350 millimeters; 360 to 1000 millimeters; greater than 1000 millimeters). Furthermore, there is the advantage of uniform sheet metal cuts for different designs, for example, with regard to power, harmonics, etc. A further advantage can be that an adaptive cooling concept can be implemented using the generative manufacturing process.

[0029] In one embodiment of the invention, a stator laminated core or stator comprises a base element. The base element, in turn, comprises a particularly axial arrangement of laminations or dynamo laminations. The laminations advantageously have high permeability and are therefore of high quality. This base element is supplemented by a generative manufacturing process, or AM (additive manufacturing), such as 3D printing. For example, AM can be used to individually design edge regions of the respective lamination and / or the stator laminated core.

[0030] For the AM process, the base element is fixed, for example, in an auxiliary structure. Alternatively or additionally, a punched package of the base element is conceivable, so that the base element has a basic stability from the outset, which simplifies handling and the further manufacturing process. Using AM (hereinafter referred to as additive manufacturing processes), the diameter of the stator, for example, can be changed. Depending on the expected maximum flux, the stator yoke can also be enlarged to prevent the yoke from becoming saturated. This means that AM can also be used to adjust the power of the electric machine (efficiency considerations). In addition to the yoke, a tooth shaft, a tooth tip, and / or a coolant can also be adapted using AM. Weight optimization is also possible.For example, with the same motor housing, the stator of a machine with a lower maximum power can be made lighter, but still be adapted to a large installation space within a large housing.

[0031] In the following, individual concrete examples are shown using the attached figures. For example, FIG 1 A classic stator lamination section 1 in a top view. Such a lamination section 1 is punched out of a dynamo lamination, for example. Stacked axially, a multitude of such laminations form a lamination stack, which is also referred to here as the basic element.

[0032] An electrical machine in a machine family can be manufactured using such a basic element or stator lamination stack in its unaltered form. For another member of the machine family, the lamination stack can be modified using a generative manufacturing process or supplemented with appropriate extension sections, as shown in the following examples. This results in different types of electrical machines or motors for the machine family based on the basic element.

[0033] The FIG 1 The plan view of the lamination or laminated core shown is suitable for tooth windings, distributed windings (single-layer or multi-layer), lap windings, and the like. For the sake of simplicity, only a single lamination or lamination section 1 will be considered as a representative of a laminated core.

[0034] A sheet metal cut 1 has a large number of teeth 2,which here protrude radially inward. The teeth 2 are separated from each other by grooves 3. The sheet metal section 1 has an overall annular shape, with the individual teeth 2 pointing toward a central axis 4.

[0035] Each tooth has a tooth shaft 5 and a yoke section 6. The individual yoke sections 6 of all teeth combine to form a closed, annular yoke. From each yoke section 6 of a tooth, the respective tooth shaft 5 of the tooth protrudes perpendicular to the axis 4. At the distal end, i.e., the inward-facing end, of each tooth shaft 5 is a tooth head 10, which can be specially shaped or simply represent the end of the tooth shaft 5.

[0036] FIG 2 shows a single tooth 2 of a sheet metal cut. The tooth shaft 5 protrudes vertically from the yoke section 6. The tooth tip 10 is not specially shaped here and ends straight without expansion at the tooth shaft 5. The boundaries of the yoke section 6 in the radial direction and in the circumferential direction can assume a punching angle α. This punching angle is crucial for the formation of a rounded sheet according to FIG 1 .

[0037] The width D of the toothed shaft 5 can be increased by AM, for example, to D' on one or both sides. This can be done, for example, depending on the current, voltage, and / or magnetic flux of the designed electrical machine. For example, AM can be used to form or press an extension section 13 onto the side of the toothed shaft 5. In the specific example of FIG 2 Such extension sections 13 are even attached to both sides of the tooth shaft 5.

[0038] Furthermore, in the present example, the yoke section 6 in the base element has a recess 7. This recess 7 is located in a region of reduced flux. Depending on the expected maximum flux, the recess 7 can be filled with a flux-conducting material to prevent saturation by AM. It can be partially or completely filled with such a filling, which also represents an extension section 13.

[0039] Depending on the required cooling, cooling channels 8 can be formed in the extension section 13 in varying numbers and shapes using AM. This applies not only to the filling of the recess 7, but also to the extension sections 13 on the tooth shaft 5.

[0040] The areas of the sheet which are created by AM, i.e. the extension sections 13, are formed in layers according to the invention in order to reduce losses due to eddy currents.

[0041] The specified layering can correspond to the layering of the electrical steel sheets or differ from it (for example, fewer layers by creating thicker layers). At the edges of teeth 2, layer thicknesses significantly thinner than the sheet thickness are also possible using the AM process, thus further reducing eddy current losses. For example, layer thicknesses in the µm range can easily be achieved using AM processes.

[0042] FIG 3 shows how FIG 2 only a single tooth 2 of a stator lamination or stator lamination stack. In particular, it can be part of a lamination section according to FIG 1 The tooth 2 has a tooth shaft 5, a yoke section 6 and a tooth head 10. As in the example of FIG 2 a portion of the tooth tip 10 of tooth 2 is initially straight in its stamped form, so that the tooth shaft 5 and its distal end, namely the portion of the tooth tip 10, are rectangular. The portion of the tooth tip 10 is then widened by AM. This creates, for example, tooth tip extensions 9 as additional parts of the tooth tip on both opposite sides of the central portion of the tooth tip 10, which also represent widened sections. These tooth tip extensions 9 protrude essentially perpendicularly from the tooth shaft 5. This allows a winding to be held in a form-fitting manner between the yoke 6 and the tooth tip extension 9. Furthermore, magnetically conductive particles can be provided in the tooth tip extensions 9 in order to further optimize the air gap field in the slot area.

[0043] The shape and size of the toothed shaft can be designed depending on the motor type (power, speed, harmonics, detent, efficiency, weight, continuous load, peak load, etc.). AM allows the cross-section of the stator to vary along the motor's length. This also allows the axial alignment and thickness of the slotted grooves to be adjusted.

[0044] Instead of the triangular recess according to FIG 2 tooth 2 of FIG 3 in its yoke 6 opposite the tooth shaft 5 a circular segment-shaped recess 7. This is in turn filled completely or partially by AM or another generative manufacturing process. In the example of FIG 3 The recess 7 was completely filled with an extension section 13. In the present example, only a single cooling channel 8 runs through it.

[0045] FIG 4 shows a further embodiment of a tooth 2 of a stator lamination or stator lamination stack. While the tooth head 10 in the example of FIG 3 at the distal end with the sheet metal cut, was used in the example of FIG 4 the tooth tip 10 also in radial direction (compare circular sheet section 1 of FIG 1 ). The correspondingly formed tooth tip extension 9, which represents part of the tooth tip, not only protrudes essentially perpendicularly from the tooth shaft 5, but also extends it in the tooth tip area. This allows the distance between the stator and rotor to be varied.

[0046] In the present case, the yoke section also has a recess 7 opposite the toothed shaft 5. The recess 7 is trapezoidal in shape. It is also completely filled with AM, forming an extended section 13. Three cooling channels of different cross-sections are provided within it. For example, the extended section 13 contains two round cooling channels 8 and one oval cooling channel 8. However, the shape of the cooling channels 8 can be varied as desired.

[0047] FIG 5 shows a further embodiment of a tooth 2 of a stator lamination or a stator lamination stack for an electrical machine. In addition to the recess 7 in the yoke, a recess 11 is also provided in the tooth tip 10 or tooth shank 5, which can be at least partially filled by AM. Both recesses 7 and 11 are wedge-shaped or triangular, respectively. The tooth tip extension 9, which represents an extension section formed by means of the generative manufacturing process, just like the extension section 13 on the yoke section 6, extends in the present case both in the circumferential direction and in the radial direction beyond the tooth shank 5 and, due to the recess 11, even into the tooth shank 5.

[0048] The geometry and number of recesses 7, 11 in tooth 2 can be varied as desired. Likewise, the number of cooling channels 8 in recesses 7, 11 or in the extension sections 13 and 9 can be adapted to the respective circumstances. In individual cases, recesses 7, 11 may not be provided or filled. This allows both electrical / magnetic properties and mechanical properties to be adapted and modified. Crucial dimensions can be the thickness D of tooth shaft 5 or the width E between recess 7 and the yoke section-tooth shaft edge for the magnetic flux. These can be varied by appropriate extension sections.

[0049] The recesses 7, 11 can be symmetrical and / or asymmetrical. An asymmetric recess can be advantageous, for example, for a preferred direction of rotation.

[0050] Furthermore, AM can be used to at least partially fill a cavity with the same or different materials. Furthermore, AM can be used to fill different cavity sizes with different materials. The materials can differ, for example, in terms of weight, permeability, and / or electrical and thermal conductivity.

[0051] Using AM, fastening elements can also be attached to the stator (not shown in the figures). Furthermore, sensors (e.g., Hall sensors, temperature sensors, humidity sensors, etc.) can be embedded into the stator using AM (also not shown in the figures).

[0052] Based on the FIG 6 bis 8 A special process is now presented with which a correspondingly specific stator core can be produced. FIG 6 a linear sequence of teeth 2. Between them are notches 14. The notches 14 can, in particular, run perpendicular (punching angle 90°) to the edge of the respective yoke section 6 of the adjacent teeth 2. Each notch 14 does not completely cut through the overall yoke formed by the yoke sections 6 of each tooth 2.

[0053] As the enlarged section VII in FIG 7 As shown in Figure 1, the notch 14 represents an elongated punched-out section that does not extend completely to the edge of the respective yoke sections 6. This creates a web 12 between the tip of the notch 14 and the edge of the adjacent yoke sections 6, which can serve as a hinge. This allows stator laminations for the base element to be punched in a linear form and then formed into a circular shape, as shown in FIG 8 Depending on the desired diameter of the stator core, a row of teeth 2 of the appropriate length can be manufactured and cut. The number of tooth elements determines the respective diameter of the stator core. The punched core elements can be stacked first and then bent, or vice versa.

[0054] In FIG 8 It is shown that bending the individual teeth 2 around the respective webs 12 creates wedge-shaped recesses 15. Using AM, the recesses 15 can be filled with corresponding extension sections 16. The extension sections 16 should have a sufficiently high permeability to fulfill the yoke functionality. If necessary, appropriate cooling devices such as cooling channels can also be integrated into the wedge-shaped recesses 15 using AM.

Claims

1. Laminated core for an electric machine having - a base element, which has - a sequence of base electrical steel laminations and - multiple teeth (2) for carrying one winding each, characterized by - an extension section (9, 13, 16), which is integrally formed on one of the teeth (2) of the base element by a generative manufacturing method, wherein the generative manufacturing method is an additive method or rapid prototyping, wherein the extension section (9, 13, 16) consists of multiple individual sections, each individual one of which is separately integrally formed on a respective one of the base electrical steel laminations by the generative manufacturing method, such that the expansion sections are formed in the manner of layers.

2. Laminated core according to Claim 1, wherein the extension section (9, 13, 16) is formed from a magnetically conductive material or has magnetically conductive particles.

3. Laminated core according to either one of the preceding claims, wherein one of the teeth (2) has a yoke portion (6) and a tooth shaft (5) protruding therefrom, and the at least one extension portion (9, 13, 16) is integrally formed on the yoke portion (6) and / or the tooth shaft (5).

4. Laminated core according to any one of the preceding claims, wherein one of the teeth (2) has a tooth head (10) and the extension portion (9, 13, 16) forms at least a part of the tooth head (10).

5. Laminated core according to any one of the preceding claims, wherein a cooling channel (8) is formed in the expansion section (9, 13, 16).

6. Laminated core according to any one of Claims 3 to 5, wherein each yoke section (6) and / or tooth shaft (5) has a recess (7, 11), which is completely or partially filled by the extension section (9, 13, 16).

7. Laminated core according to Claim 6, wherein the recess (7, 11) is arranged asymmetrically with respect to a central axis of the respective tooth shaft (5).

8. Laminated core according to Claim 6 or 7, wherein the recess (7, 11) is filled with several different materials.

9. Laminated core according to any one of the preceding claims, wherein the expansion section (9, 13, 16) is in the form of a securing element.

10. Laminated core according to any one of Claims 6 to 9, wherein a sensor is embedded in the recess (7, 11) by means of the extension section (9, 13, 16).

11. Laminated core according to any one of Claims 6 to 10, wherein an additional yoke section (6) of one of the teeth (2) directly adjoins the yoke section (6) of another of the teeth (2), and the extension section (9, 13, 16) forms a wedge between the yoke section (6) and the additional yoke section (6).

12. Electric machine having a laminated core according to any one of the preceding claims, which electric machine is designed, in particular, as a synchronous machine, an asynchronous machine or a reluctance machine.

13. Machine family having at least - a first electric machine in the style of the electric machine of Claim 12, and - a second electric machine in the style of the electric machine of Claim 12, wherein the electric machines, in particular both electric machines, have the same base element, but different extension sections (9, 13, 16).

14. Method for producing a laminated core for an electric machine by - punching or cutting out base electrical steel laminations and - forming a base element by stringing together the punched or cut-out base electrical steel laminations, wherein - the base element has multiple teeth (2) for carrying one winding each, characterized by integrally forming an extension section (9, 13, 16) on one of the teeth (2) of the base element by a generative manufacturing method, wherein the generative manufacturing method is an additive method or rapid prototyping, wherein the extension section (9, 13, 16) consists of multiple individual sections, each individual one of which is separately integrally formed on a respective one of the base electrical steel laminations by the generative manufacturing method, such that the expansion sections are formed in the manner of layers.