Method for reshaping and introducing a winding into a rotor body or stator body

Abstract

The invention relates to a method for reshaping a winding (20) and introducing the winding (20) into a rotor body or stator body (100). In order to enable a compact structure of a stator or rotor of an electric machine with advantageous electromagnetic properties, the following method steps are proposed: • preforming a stranded wire (25) to create the winding, such that straight sections (22, 22', 22", 22'") of the stranded wire (25) are connected via bent winding head sections (24) of the stranded wire (25) so as to form a wave winding or loop winding, • introducing the winding into the rotor body or stator body (100) such that the straight sections come to lie in the slots (102) and the winding head sections (24) of the winding protrude on axial end faces of the rotor body or stator body (100), and • compacting the winding head sections (24) so as to reduce their axial protrusion.

Description

[0001] Method for forming and inserting a winding into a rotor or stator body

[0002] The invention relates to a method for forming a winding and inserting the winding into a rotor or stator body.

[0003] Continuous copper coil windings are used for rotors or stators. A distinction is made between concentrated and distributed windings. The latter are characterized by a nearly sinusoidal magnetic field in the air gap, which has a positive effect on the torque curve of the machine. Disadvantages, however, are a larger winding head and higher phase resistance compared to concentrated winding.

[0004] Particularly in high-power electrical machines, so-called flat wire windings are frequently used. These consist of solid conductor wires with a rectangular cross-section, which often allow optimal utilization of the available slot cross-section in the rotor or stator. However, at high conductor current frequencies, current displacement effects (skin effect, proximity effect) mean that the conductor cross-section is no longer fully utilized, thus resulting in additional ohmic losses.

[0005] In this context, EP 3 934 067 A1 discloses a winding for an electrical machine comprising a profiled stranded wire with a rectangular cross-section. Due to the large number of electrically insulated, comparatively thin individual strands of the profiled stranded wire, the current displacement effect and the associated losses are reduced.

[0006] Distributed windings for electrical machines are often manufactured as flat winding mats in the form of wave windings or loop windings and then drawn into the slots of stators or rotors. Wave windings consist of a number of interwoven conductor wires that are bent several times in opposite directions, so that parallel, straight wire sections or wire webs of the conductor wires, intended to fill the slots of stator or rotor bodies, are connected by roof-like winding heads that protrude beyond the front sides of the manufactured rotors or stators. To produce the wave winding as an initially flat winding mat, a flat and rotatable winding template and a wire handling device can be used.

[0007] DE102015120963A1 describes, by way of example, a method for producing wave windings.

[0008] After the flat winding mat has been produced on a winding template, it can be stripped off the template and transferred to a magazine. A magazine can, for example, be designed as an elongated linear magazine. It preferably has several receptacles for the conductor wires in the longitudinal direction. Alternatively, a magazine can also be designed as a rotary magazine. The receptacles are each formed between two webs, resulting in groove-shaped receptacles. In the case of a linear magazine, these groove-shaped receptacles often run perpendicular to the longitudinal direction in a width direction of the linear magazine. Typically, a linear magazine has a greater length in the longitudinal direction than its width in the width direction.The winding mat can be compressed in the magazine and safely transferred from the manufacturing process step to a further process step in which the winding mat is drawn into a rotor or stator body. A magazine should ensure that the individual wires of the winding mat, and in particular the straight wire sections of the winding mat intended for insertion into slots, do not shift against one another during handling and compression. If a wave winding as described above is inserted into a magazine, and in particular into a linear magazine, the result is that in a starting area and an end area of ​​the wave winding only individual conductor wires lie in the slots of the linear magazine, whereby in a partial area of ​​the linear magazine several conductor wires can lie one above the other in the slots of the linear magazine.

[0009] The present invention relates to the optimization of a wave winding intended to be used as a coil winding in a rotor or stator. Due to the essentially cylindrical shape of rotors or stators, they have slots that either have parallel slot flanks. Alternatively, these slots are designed such that the tooth flanks of the teeth arranged between the slots are parallel. In the latter case, conical or trapezoidal slot cross-sections result, viewed in cross-section or axially with respect to the rotational axis of the rotor or stator. An advantage of this latter embodiment is that the magnetic resistance of each tooth is the same when viewed in the radial direction.

[0010] When filling the slots, it is desirable to achieve the highest possible fill factor, ie, the slots should be filled as completely as possible with the conductor wires in order to use the available installation space as completely as possible for electromagnetically relevant components (conductor wires). In this context,

[0011] US 2016 / 0 056 696 A1 discloses a method in which straight sections of a wave winding are inserted into receptacles of a magazine and are formed onto the receptacles by reshaping the conductor wires.

[0012] The invention is based on the object of enabling a compact design of a stator or rotor of an electrical machine with advantageous electromagnetic properties.

[0013] This object is achieved by a method having the features of claim 1, a stator having the features of claim 11, and a rotor having the features of claim 12. Further embodiments of the invention are set forth in the dependent claims. The method according to the invention serves for forming and inserting a winding into a slotted rotor or stator body of an electrical machine.

[0014] In a first method step, a stranded wire is provided. The stranded wire is preferably provided in the form of a twisted stranded wire, in which the individual, electrically insulated wires have a twist. The advantage of such a twist is that the individual wires continuously change their position with respect to the cross-sectional area of ​​the conductor bundle over the axial extent of a conductor bundle formed into a stranded wire. A wire arranged centrally at one axial point is positioned at another axial point in the outer region of the conductor bundle and can therefore transfer the heat generated in the wire to the slot flanks of the rotor or stator. In this way, the twist contributes to improved thermal conductivity compared to a conductor bundle with wires arranged in parallel. The stranded wire structure can comprise either a single strand or a single twist.Twist step of a stranded wire or a multi-stage structure with several stranding and twisting steps, which then differ in the twisting direction of individual or stranded wire and the entire strand.

[0015] The particularly twisted stranded wire is then pre-formed into the winding, wherein the straight sections of the stranded wire are connected via bent winding head sections of the stranded wire to form a wave or loop winding.

[0016] The preformed winding is then inserted into the rotor or stator body. The straight sections are positioned in the slots, while the winding head sections protrude from the axial end faces of the rotor or stator body.

[0017] The invention is based on the finding that there is considerable potential for reducing the axial length of a stator or rotor with distributed winding and a stranded wire structure according to the invention. In principle, a distributed winding has a greater axial length, i.e., in the area of ​​the end winding heads, than a concentrated winding. As a rule, flat wire windings or bar windings, which have a comparatively high degree of rigidity, are often used, particularly for high-power electrical machines such as those used for traction drives in electromobility, i.e., for example, with a continuous power of > 50 kW. In such windings, the winding heads are preformed during the production of the flat winding mat.After inserting the winding mat into the stator or rotor, the formability of the winding heads is only possible to a very limited extent, since the high rigidity of the conductors would require very high bending forces, which, among other things, poses the risk of damaging the winding insulation.

[0018] In contrast, the inventive design of the winding based on a stranded wire allows for compaction of the winding head sections after the winding has been inserted into the rotor or stator body. This is due to the significantly higher flexibility of the stranded wires. The final compaction step significantly reduces the axial projection of the winding heads, making it possible to provide an electrical machine with a distributed winding and a significantly reduced axial length compared to the prior art.

[0019] If the stranded wire is provided as a profiled stranded wire, e.g., with a rectangular cross-section, a very high slot fill factor can be achieved. The stranded wire can be preconfigured as a profiled stranded wire or, alternatively, formed into the desired profile in a magazine with appropriate slotted receptacles.

[0020] Before inserting the winding into the rotor or stator body, the following process steps can be carried out:

[0021] • Inserting the winding into a magazine, whereby the straight sections of the stranded wire are inserted into slot-shaped receptacles of the magazine, pressing the stranded wires in the receptacles of the magazine, whereby the stranded wires are formed to the receptacles.

[0022] In particular, the straight wire sections of the stranded wires are pressed into the receptacles of the magazine, thereby forming the straight wire sections and molding the stranded wires with the straight wire sections to the receptacles. In particular, the magazine can be designed as a linear magazine. Alternatively, the magazine can be designed as a rotary magazine.

[0023] The method described above offers the advantage that the magazine, with its receptacles, serves as a kind of template for forming the stranded wire winding. The respective receptacles of the magazine preferably have the same cross-section as the slots of the rotor or stator, into which the winding is drawn after forming and removal from the magazine.

[0024] According to a further embodiment of the method, the stranded wires are formed into a substantially conical cross-section in the receptacles. This is particularly advantageous when the tooth flanks of the rotor or stator, which is intended for the winding, are parallel. The parallelity of the tooth flanks has the advantage that the magnetic conductance of the tooth flanks remains essentially constant along their radial extent. Due to the parallel tooth flanks, however, the slot flanks of a substantially cylindrical rotor or stator body are not parallel, resulting in a substantially trapezoidal slot cross-section.

[0025] If the stranded wire is first preformed as a winding mat, the winding can then be rolled spirally before being inserted into the rotor or stator body, inserted axially into the rotor or stator body, and expanded radially into the slots of the rotor or stator body. This process is particularly suitable for the stator of an internal rotor machine or the rotor of an external rotor machine.

[0026] Alternatively, an embodiment of the invention is also advantageous in which the winding is incorporated into a segmented stator or rotor body. In this case, the individual segments can be engaged with a winding mat that has been rolled to essentially their final outer diameter and then connected to one another.

[0027] After the winding mat is inserted into the stator or rotor, the winding heads are compacted, which is achieved particularly effectively through the use of stranded wire. For this purpose, the winding head sections are preferably pressed axially against the rotor or stator body using a compacting press. Before pressing, a support finger can be mounted on each stator tooth to protect any slot insulation protrusion during the pressing process. This prevents damage to the slot insulation during the pressing process. Furthermore, the support fingers also protect the wire insulation from damage during the pressing process.

[0028] If a forming tool is arranged enclosing the winding head sections, radial spreading of the winding head sections during the pressing process can be limited and thus the radial installation space of the machine can be kept as compact as possible.

[0029] In an advantageous embodiment of the invention, compacting of the winding head sections in the radial direction in addition to the axially directed compacting is achieved by using a compacting press for axial pressing, which has bevels through which the winding head sections are pressed radially outwards, while the compacting press is moved axially in the direction of the rotor or stator package.

[0030] An even further reduction of the axial projection of the winding heads is achieved by, in an advantageous embodiment of the invention, rotating the compacting press by a predetermined angle of rotation relative to the stator or rotor body during the axial pressing process.

[0031] To reduce the springback of the stranded wire in the compacted state, an optional step after compacting the winding head sections to reduce axial overhang is to bake the winding to secure it. For example, a bonded connection is created by baking the wires together using a bonding varnish. This bonding varnish is usually thermally activated and liquefies.

[0032] Through diffusion into the cavities of the stranded conductor and subsequent curing, the previously created conductor structure solidifies in the winding head, and the resulting structure is mechanically stabilized. The bonding varnish is typically a layer of special varnish applied during the production of individual strands or individual wires.

[0033] Further features, details, and advantages of the invention will become apparent from the wording of the claims and from the following description of exemplary embodiments with reference to the drawings. They show:

[0034] Fig. 1 A, B: a schematic representation of the process sequence for two different variants of forming the stranded wires in a linear magazine;

[0035] Fig. 2: a schematic partial representation of a top view of the linear magazine with an inserted wave winding;

[0036] Fig. 3: a schematic partial axial sectional view of a part of a wave winding drawn into a rotor or stator body;

[0037] Fig. 4: a schematic sectional view of a stator body with inserted wave winding;

[0038] Fig. 5: a schematic sectional view of the stator body with inserted wave winding during compaction of the winding heads using a first embodiment of a compaction press; Fig. 6: a schematic sectional view of the stator body with inserted wave winding after compaction of the winding heads 24 using the first embodiment of the compaction press 40;

[0039] Fig. 7: another schematic sectional view of a stator body with inserted wave winding;

[0040] Fig. 8: a schematic sectional view of the stator body with inserted wave winding during compaction of the winding heads 24 with a second embodiment of a compaction press 40;

[0041] Fig. 9: a schematic sectional view of the stator body with inserted wave winding after compacting the winding heads 24 with the second embodiment of the compacting press 40;

[0042] Fig. 10A and 10B: a side view of the winding heads before and after compacting and

[0043] Fig. 11A, B and C: a side view of the winding heads during rotation of the compacting press during the pressing process.

[0044] Unless otherwise stated, the reference numerals are used consistently below. Unless otherwise stated, the reference numerals in the text always refer to all figures. Likewise, all reference numerals in the figures, unless otherwise stated, always refer to the entire following description of the exemplary embodiments.

[0045] In the following, Figure 1 shows a receptacle 12 with straight wire sections 22, 22', 22", 22'" of a winding 20 designed as a wave winding inserted therein. Figure 2 shows that a linear magazine 10 has several such receptacles 12 along its longitudinal direction L.

[0046] Figure 1A and Figure 1B each show a schematic representation of the process sequence for two different variants of forming stranded wires 25 in the linear magazine 10. The process provides that straight wire sections 22, 22', 22", 22'" of the stranded wires 25 of the winding 20 are first inserted into a linear magazine 10. The linear magazine 10 has receptacles 12 for this purpose, wherein the receptacles 12 are delimited in the longitudinal direction L of the linear magazine by webs 14, 14'. The receptacles 12 have an opening 16 through which the straight wire sections 22, 22', 22", 22'" can be inserted into the receptacles 12, so that the straight wire sections 22, 22', 22", 22'" lie in the receptacles 12 perpendicular to the longitudinal direction L of the linear magazine, i.e. in a width direction B.In this embodiment, the receptacle 12 has a receiving space with a conical cross-section, wherein the width of the receptacle 12 is greater in the region of the opening 16 of the receptacle 12 than in a lower region of the receptacle 12.

[0047] According to the process sequence shown in Figure 1A, the stranded wires 25 with their straight sections 22, 22', 22", 22'" are inserted into the receptacle 12, wherein the wire width 26 essentially corresponds to the width of the receptacle 12 in the upper region and the width of the receptacle 12 decreases with increasing depth of the receptacle and is smaller than the wire width 26.

[0048] In Figure 1B, the stranded wires 25 with their straight sections 22, 22', 22", 22'" are inserted into the receptacle 12, wherein the width of the receptacle 12 decreases with increasing depth of the receptacle 12 and the wire width 26 essentially corresponds to the width of the receptacle 12 in the lower region. In the region of the receptacle 12 that is close to the opening 16, the width of the receptacle 12 is greater than the wire width 26.

[0049] In the subsequent step 2), the wave winding with its straight wire sections 22, 22', 22", 22'" located in the receptacles 12 of the linear magazine 10 is pressed by means of a pressing tool 30, whereby the stranded wires 25 are reshaped and the stranded wires 25 with their straight wire sections 22, 22', 22", 22'" are formed onto the receptacles 12 and in particular onto the webs 14, 14'.

[0050] For the variant shown in Figure 1A, a wire width 26 was selected that corresponds approximately to the average width of the holder 12. This ensures that, after pressing, the lowest possible degree of deformation is achieved across all deformations of the conductor wires 25, thereby minimizing stress on the insulation of the stranded wires 25. The lower straight wire section 22' is compressed in the direction of the holder width or in the longitudinal direction L of the linear magazine 10, and the upper wire section 22 is stretched in the direction of the holder width or in the longitudinal direction L of the linear magazine 10.

[0051] For the variant shown in Figure 1B, the width of the receptacle 12 or the extension of the receptacle in the longitudinal direction L of the linear magazine was selected such that the wire width 26 is less than or equal to the smallest width of the tapered receptacle 12. This results in all straight wire sections 22, 22' being stretched in the longitudinal direction L of the linear magazine 10. There is no displacement of the straight wire sections 22, 22' perpendicular to this, which advantageously prevents insulation damage.

[0052] In step 3), the final state of the formed stranded wires 25 in the linear magazine 10 is shown. In a subsequent step not shown, the conductor wires 25 or the wave winding 20 are removed from the linear magazine 10 and transferred into a drawing-in tool or into a rotor or stator body 100.

[0053] It can be seen that the lower straight wire section 22' in Figure 1A was stretched in the longitudinal direction L of the linear magazine, and the upper straight wire section 22 in Figure 1A was compressed in the longitudinal direction L of the linear magazine 10 by the forming process. In Figure 1B, both straight wire sections 22, 22' were compressed in the longitudinal direction L by the forming process, resulting in a lower overall height of the wire package compared to the design of the linear magazine 10 in Figure 1A.

[0054] The person skilled in the art will recognize that more than two layers of straight wire sections 22, 22', 22", 22'" can also be placed in the respective receptacle 12 of the linear magazine 10. The pressing takes place in step 2) with a suitable pressing tool 30, which engages in the receptacles 12 and there effects the deformation of the straight wire sections 22, 22', 22", 22'" or conductor wires 25 by molding them onto the webs 14, 14' of the receptacles 12. The forming can be carried out for all receptacles 12 (in Fig. 1 only one receptacle 12 of the linear magazine 10 is shown as a representative example) simultaneously, for example by means of a press die, but it is also conceivable that the straight wire sections 22, 22', 22", 22'" are rolled into the receptacles 12 of the linear magazine 10 by a roller equipped with press webs.Of course, the variants with regard to the design of the width of the receptacles 12 to the wire width 26, as shown in Figures 1A and 1B, can occur together within a linear magazine 10, wherein the width of the receptacles 12 can also change in the course of the linear magazine 10, i.e. along its longitudinal direction L.

[0055] For the sake of clarity, Figure 2 shows a schematic partial top view of the linear magazine 10 with the inserted winding 20 in its wave winding design. It can be seen that the wave winding with the straight wire sections 22 of the conductor wires is inserted into the receptacles 12 of the linear magazine 10. The receptacles 12 are each delimited by webs 14, 14'. In the course of the stranded wires 25, the respective straight wire sections 22 are adjoined by winding heads 24 of the wave winding, which, in this embodiment, are located outside the receptacles 12 and outside the linear magazine 10. The winding heads 24 are each located outside the receptacles 12 in the width direction B of the linear magazine 10.After later insertion into a rotor or stator body, the winding overhangs 24 protrude beyond the latter when viewed axially, thus initially increasing the axial installation space required by an electrical machine, which, for example, represents a severely limiting factor when used as an electric traction drive for electric or hybrid vehicles. Cooling of the winding overhangs thus protruding also often presents a particular challenge, as there is no thermal connection between the conductors and the stator or rotor laminated core. Figure 3 shows a schematic, partial axial sectional view of part of the winding 20 inserted into a rotor or stator body 100. The winding 20 is here inserted into a slot 102, wherein the slot 102 is delimited on both sides by teeth 106, 106' with parallel tooth flanks 108, 108', resulting in a radially different slot width, which in the exemplary embodiment shown increases with increasing radius.The slot 102 is bounded radially outwardly by a slot base 104 and radially inwardly by yoke sections 107, 107' of the teeth 106, 106'. The wave winding almost completely fills the slot 102 with the straight wire sections 22, 22', 22", 22'" formed according to the method described above. Here, not just two layers of stranded wires 25, but four layers of stranded wires 25 or straight wire sections 22, 22', 22", 22'" are drawn into a slot 102 of a rotor or stator body 100.

[0056] In one variant, these four layers may each have already been formed in the receptacles 12 of the linear magazine 10, or the wave winding was formed in two layers, with the winding 20 then being drawn into the essentially cylindrical rotor or stator body 100 in two revolutions. It is understood that the forming in the linear magazine 10 must then take place according to the later layer in the rotor or stator body, with the receptacle geometry changing accordingly along the longitudinal direction L of the linear magazine 10 in order to be adapted to the radially changing slot cross-section of the rotor or stator body 100. For this purpose, the linear magazine 10 can have a fixed geometry, or, within certain limits, have movable or replaceable webs 14, 14' or boundaries of the receptacles 12.

[0057] Figure 4 shows a schematic sectional view of a stator body 100 with inserted wave winding. The straight wire sections (22, 22', 22", 22'") of the stranded wires 25 rest in the slots 102 of the stator body, and winding overhangs 24 protrude axially above the stator body 100 by a height h1. Figure 5 shows a schematic sectional view of the stator body 100 with inserted wave winding during compaction of the winding overhangs 24 using a first embodiment of a compaction press 40. Next to the compaction press 40, a forming tool 42 designed as an open diameter ring is arranged radially enclosing the winding overhangs 24, as well as support fingers 41. A support finger 41 is mounted on each stator tooth. Its function is to protect a slot insulation paper (not shown) from damage during compaction.The support fingers 41 define the bending area of ​​the winding head 24 at a defined distance from the stator body 100, so that bending of the slot insulation on the stator body 100 is prevented.

[0058] To compact the winding heads 24, the compacting press 40 is moved axially toward the stator body, so that the winding heads 24 are compressed from the first height h1 to the second height h2. This final state is shown in Figure 6.

[0059] Figure 7 shows another schematic sectional view of a stator body 100 with an inserted wave winding and axially protruding winding heads. In addition to the initial height h1 of the winding heads 24, the radial initial width w1 is also shown.

[0060] Figure 8 shows a schematic sectional view of the stator body 100 with inserted wave winding during compaction of the winding heads 24 using a second embodiment of a compaction press 40. This second embodiment of the compaction press 40 has bevels 43 which, when the compaction press 40 is pressed axially against the stator body 100, not only cause axial compression but also radial compression of the winding heads 24. Figure 9 shows that at the end of the compaction process, the winding heads have reduced both in terms of their axial extent (from h1 to h2) and in terms of their radial extent (from w1 to w2). Figures 10A and 10B show a side view of the winding heads before and after compaction. Here, too, the reduction of the axial conductor height in the winding head from h1 to h2 is visible.Figures 11A, 11B, and 11C, on the other hand, show a side view of the winding heads 24 during rotation of the compacting press 40 during the pressing process. By applying a predetermined angle of rotation, which accompanies the axial pressing process of the compacting press 40 similar to a screwing process, the conductor profile in the winding head 24 can be modified such that its axial expansion is further reduced.

[0061] All features and advantages resulting from the claims, the description and the drawings, including construction details, spatial arrangements and method steps, may be essential to the invention both alone and in various combinations.

[0062] 1 List of reference symbols

[0063] 10 magazines, linear magazine

[0064] 12 recordings

[0065] 14, 14' jetty

[0066] 16 Opening

[0067] 20 windings

[0068] 22, 22', 22", 22'" Straight wire section

[0069] 24 winding heads

[0070] 25 stranded wire

[0071] 26 wire width

[0072] 27 single wires

[0073] 28 pre-formed stranded wire

[0074] 29 loose stranded wire

[0075] 30 pressing tools

[0076] 40 compacting press

[0077] 41 supporting fingers

[0078] 42 mold tool

[0079] 43 slopes

[0080] 100 rotor or stator bodies

[0081] 102 grooves

[0082] 104 groove base

[0083] 106, 106' tooth

[0084] 107, 107' yoke section

[0085] 108, 108' tooth flank L longitudinal direction

[0086] B Width direction

Claims

Patent claims 1. Method for forming and inserting a winding (20) into a rotor or stator body (100) of an electrical machine equipped with slots (102), comprising the following method steps: • Preforming a stranded wire (25) to form the winding in such a way that straight sections (22, 22', 22", 22'") of the stranded wire (25) are connected to a wave or loop winding via bent winding head sections (24) of the stranded wire (25), • Inserting the winding into the rotor or stator body (100) in such a way that the straight sections come to lie in the slots (102) and the winding head sections (24) of the winding protrude on the axial end faces of the rotor or stator body (100) and • Making the winding head sections (24) more compact so that their axial projection is reduced.

2. Method according to claim 1, wherein a profiled stranded wire is used as the stranded wire (25).

3. Method according to claim 1 or 2, wherein the following method steps are carried out before the winding is introduced into the rotor or stator body (102): • Inserting the winding into a magazine (10), whereby the straight sections (22, 22', 22", 22'") of the stranded wire (25) are inserted into slot-shaped receptacles (12) of the magazine (10), • Pressing the stranded wires (25) into the receptacles (12) of the magazine, whereby the stranded wires (25) are formed onto the receptacles (12).

4. Method according to claim 3, wherein the stranded wires (25) are formed into a conical cross-section in the receptacles (12).

5. Method according to one of the preceding claims, wherein for compaction the winding head sections (24) are pressed axially against the rotor or stator body (100) using a compacting press (40).

6. The method according to claim 5, wherein prior to pressing, a support finger (41) is mounted on each stator tooth, which support finger protects a slot projection of a slot insulation during the pressing process.

7. The method according to claim 5 or 6, wherein a forming tool (42) is arranged to enclose the winding head sections (24) in order to limit radial spreading of the winding head sections (24) during the pressing process.

8. Method according to one of claims 5 to 7, wherein the compacting press (40) is rotated by a predetermined angle of rotation relative to the stator or rotor body (100) during the axial pressing process.

9. Method according to one of the preceding claims, wherein a compacting press (40) is used for axial pressing, which has bevels (43) by means of which the winding head sections (24) are pressed radially outwards, while the compacting press (40) is moved axially in the direction of the rotor or stator package (100).

10. Method according to one of the preceding claims, wherein after compacting the winding head sections (24) to reduce the axial overhang, the winding is baked to fix the winding.

11. Stator of an electrical machine with a stator body with slots (102) and with a winding made of stranded wire (25), in which straight sections (22, 22', 22", 22'") of the stranded wire are connected via bent winding head sections (24) of the stranded wire (25) to form a wave or loop winding, the straight sections (22, 22', 22", 22'") come to lie in the slots (102) and the winding head sections (24) of the winding protrude on axial end faces of the stator body, wherein the winding head sections (24) are compacted.

12. Rotor of an electrical machine with a rotor body with slots (102) and with a winding made of stranded wire (25), in which straight sections (22, 22', 22", 22'") of the stranded wire are connected to a wave or loop winding via bent winding head sections (24) of the stranded wire (25), the straight sections (22, 22', 22", 22'") come to lie in the slots (102) and the winding head sections (24) of the winding protrude on axial end faces of the rotor body, wherein the winding head sections (24) are compacted.

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