CN115800648A - Method for producing an axial flux machine, axial flux machine and drive motor unit - Google Patents

Abstract

The invention relates to a method for producing an axial flux electric machine, wherein the axial flux electric machine has a disk-shaped rotor, a disk-shaped first and second stator element, and a cylindrical jacket-shaped bushing, wherein the method has the following steps: providing a bushing in the providing step, wherein the bushing has first and second stops; in a first pressing step, the first stator element is pressed into the bushing up to a first stop; loading the rotor into the liner in a loading step; determining the axial distance between the second end face of the rotor and the second stop in a first measuring step; determining the radial dimension of the second stator element in a second measuring step; in a pressing step, the second stop is pressed by a pressing die according to the axial distance determined in the first measuring step, wherein the radial dimension of the pressing die corresponds to the radial dimension of the second stator element; in a second pressing step, the second stator element is pressed into the bushing to the finish-pressed stop. The invention also relates to an axial flux machine and a drive motor unit.

Description

Method for producing an axial flux machine, axial flux machine and drive motor unit

Technical Field

The invention relates to a method for producing an axial flux electric machine, wherein the axial flux electric machine has a disk-shaped rotor, disk-shaped first and second stator elements, and a cylindrical jacket-shaped sleeve, wherein the rotor is arranged between the two stator elements in the axial direction of the axial flux electric machine and the sleeve surrounds the rotor and the two stator elements in the radial direction.

Background

In axial flux machines, forces on the rotor are caused by the axial magnetic field elements, i.e. extending in the direction of the axis of rotation, in contrast to the significantly wider radial current machines. The two most common structural forms are here: a machine having a single rotor surrounded by two stators (double stators) in the axial direction, and a machine having a stator disposed between the two rotors (double rotors). Compared to radial flow machines, axial flux machines achieve a very compact construction with a small axial dimension and a high torque density, so that they are particularly suitable for applications in which installation space and weight are important. In addition to electric machines in which the stator and the rotor are mounted in a housing and are designed as an integral unit, so-called frameless designs are also known from the prior art, in which the rotor and the stator are mounted directly in the mechanical system, for example in a robot joint.

It is important in the installation of frameless electric machines to precisely adjust the axial play between the stator and the rotor. In an arrangement with two stators, the distance between the two stators must be set to a precise degree, which must be maintained even under the influence of the magnetic forces occurring in the rotor. For this purpose, for example, two stators can be pressed into a bushing which has a stop introduced by turning and in this way achieves a relatively precise positioning. However, fluctuations in the axial dimension, which are caused by manufacturing technology, occur in the stator, so that fluctuations in the axial extent of the recess occur despite the stop. The fluctuation of this clearance not only has a serious influence on the efficiency and the running performance of the engine, but also may cause problems when later installed in a mechanical device. Furthermore, fluctuations in the outer diameter of the stator occur, so that the press connection between the stator and the bushing cannot be set smoothly.

Disclosure of Invention

On this basis, the object of the invention is to provide a method by means of which the dimensional fluctuations can be compensated and the axial play can be set precisely.

The object of the invention is achieved by a method for producing an axial flux machine, wherein the axial flux machine has a disk-shaped rotor, a first and a second disk-shaped stator element and a cylindrical jacket-shaped bushing, wherein the rotor is arranged between the two stator elements in the axial direction of the axial flux machine and the bushing surrounds the rotor and the two stator elements in the radial direction, wherein the method has the following steps:

providing the bushing in the providing step, wherein the bushing has a first and a second stop, which are spaced apart from each other in the axial direction and extend respectively circumferentially over at least a part of an inner circumference of the bushing;

in a first pressing step, the first stator element is pressed into the bushing up to a first stop, so that an axially outwardly directed end face of the first stator element forms a first end face of the axial flux machine;

-in the step of inserting the rotor into the bushing such that the first end face of the rotor rests on the axially inwardly directed end face of the first stator element;

in a first measuring step, the axial distance between the second end face of the rotor and the second stop is determined;

-determining the radial dimension of the second stator element in a second measuring step;

in a pressing step, the second stop is pressed by a pressing tool according to the axial distance determined in the first measuring step, wherein the pressing tool is selected such that the radial dimension of the pressing tool corresponds to the radial dimension of the second stator element determined in the second measuring step;

in a second pressing step, the second stator element is pressed into the bushing up to the finish-pressed stop, so that the axially outwardly directed end face of the second stator element forms a second end face of the axial flux machine.

The method according to the invention is based on the fine pressing of the second stop in such a way that the second stop is adapted to the specific dimensions of the assembly consisting of the bushing, the rotor and the first stator element, whereby a uniform and precisely set overall clearance is obtained when subsequently the second stator element is pressed in by means of the fine-pressed second stop. By a suitable choice of the pressing die, it is possible in this way to compensate not only for manufacturing-related deviations in the axial dimensions of the component, but also for diameter fluctuations of the second stator element.

The resulting axial-flux electric machine is substantially cylindrical in configuration, wherein the first and second stator elements form two end faces of the axial-flux electric machine. The geometric description of an axial flux machine and its components is based on the following reference system: the central axis of the axial flux machine coincides with the axis of rotation of the rotor and defines an axial direction, a radial direction running perpendicular thereto and a circumferential direction around the central axis. The midpoint of the arrangement is formed by a point on the central axis which is located exactly between the two stator elements, so that a distinction can be made between an inwardly directed orientation (i.e. towards the midpoint or central axis) and an outwardly directed orientation (away from the midpoint or central axis) with respect to the axial direction and the radial direction, respectively. The rotor and the two stator elements (double stator) are designed in the form of a disk, are aligned parallel to one another and are spaced apart from one another with respect to the axial direction, wherein the distance between the rotor and the two stator elements defines the entire axial gap of the axial flux machine. The double stator and the rotor form in particular a frameless axial flux machine and have a certain axial and in particular radial play relative to one another, so that the play is precisely adjusted when the axial flux machine is mounted on a machine provided for this purpose. The entire gap provided is divided into a gap between the first stator element and the rotor and another gap between the second stator element and the rotor by an adjustment made during mounting.

In the method according to the invention, a bushing is first provided, which has two stops on its cylindrical inner wall, which in particular each project radially inward and extend over at least a part of the inner circumference of the bushing. In particular, the first and/or second stop can extend over the entire inner circumference of the bushing. In particular, the two stops each have a contact surface which is directed outward in the axial direction and with which the respective stator element can be brought into mechanical contact during the pressing-in process. The first stator element is pressed into the first end-side opening of the bushing until it comes into contact with the first stop. The rotor is then fitted into the bushing such that the rotor rests on the inner end face of the first stator element. Preferably the rotor is arranged when fitted such that it is held in position by magnetic forces between the first stator element and the permanent magnets of the rotor. In a first measuring step, the axial distance between the axially outwardly directed end face of the rotor and the second stop is then determined, wherein the edge of the first end-side opening of the bushing is preferably placed on the support element in order to precisely position and secure the bushing with respect to the axial direction. The determined axial distance yields the axial free space of the rotor between the stator elements, i.e. the entire gap provided for the two axial gaps between the rotor and the double stator when the axial flux machine is installed in the machine. The axial distance can thus be used to determine how much the axial position of the second stop needs to be corrected by fine-pressing in order to make the entire recess correspond to the predetermined theoretical dimension. In addition, in a second measuring step, the radial dimension (outer diameter) of the second stator element is determined, whereby the die used in the subsequent pressing step can be selected such that it suitably widens the inner diameter of the sleeve for receiving the second stator element. In the pressing step, the second stop is correspondingly pressed in an axial direction and the inner diameter of the bushing is widened by the pressing tool. In a second subsequent pressing step, the second stator element is pressed into a second end-side opening of the bushing, which is opposite the first end-side opening, until the second stator element comes into contact with the finish-pressed second stop.

The two stator elements are in particular of identical design and have a succession of stator teeth in the circumferential direction, wherein each stator tooth is formed by a magnetizable tooth body which is surrounded by an electrically contactable coil winding. The tooth body is preferably made of Soft Magnetic Composite (SMC) and is preferably arranged in a recess of a disk-shaped Circuit Board (PCB), in particular a Multilayer Circuit Board (Multilayer PCB), on which the coil windings are arranged, in particular constructed therein. The tooth body is connected to the annular ground element on one side of the circuit board or is formed in one piece therewith. The grounding element is in particular glued to one of the two faces of the circuit board. The stator elements are in particular oriented during the pressing-in such that the grounding elements point axially outward. Preferably, the circuit board has a centrally arranged circular through hole. The rotor preferably has a base body comprising a sleeve, on which the circle segment-shaped permanent magnets are arranged in the circumferential direction, the permanent magnets forming the poles of the rotor.

According to an advantageous embodiment of the method according to the invention, the axial play between the rotor and the stator element pressed into the bushing is determined in a third measuring step following the second pressing step. The entire available gap between the rotor and the double stator results in particular from the axial play. It can then be checked from the measured values whether the manufactured axial-flux machine corresponds to a theoretical preset set for the respective application.

According to an advantageous embodiment of the invention, the rotor is inserted into the bushing in the insertion step in such a way that the sleeve of the rotor passes through the through-opening arranged in the center of the first stator element, wherein the rotor is placed in particular on an axially inwardly directed end face of the first stator element in such a way that the magnets of the rotor are in mechanical contact with the stator teeth of the first stator element. In particular, the rotor is arranged on the first stator element in the insertion step. In particular, in the insertion step, the rotor is arranged on the first stator element in such a way that the rotor is held in position by the magnetic force between the first stator element and the permanent magnets of the rotor. Preferably the through hole is a right circular opening. In particular, the second stator element likewise has a through-opening and is arranged in the second pressing step in such a way that the sleeve of the rotor passes through the through-opening.

According to an advantageous embodiment of the invention, the first and/or second stop is designed as a projection or step and has a contact surface extending perpendicular to the axial direction, wherein the first or second stator element, when pressed in, makes mechanical contact with the contact surface. Alternatively, the second stop is pressed with a contact surface extending perpendicular to the axial direction only during the coining. In particular, the first and/or the second stop is a gradient between a first and a second inner diameter of the bushing, wherein the inner diameter between the first and the second stop is greater in the axially inner region than in the axially outer region, so that a contact surface extending perpendicular to the axial direction results in the transition between the two diameters. The projection or step extends in particular over the entire inner circumference of the bushing. Alternatively, the first and/or second projection can also be formed in each case as a plurality of projections or steps which are arranged at the same height with respect to the axial direction and are spaced apart from one another in the circumferential direction. In this case, each projection or each step extends over only a part of the inner circumference, so that the contact surface is formed by a plurality of partial surfaces that are spaced apart from one another, wherein the respective stator element comes into contact with all partial surfaces during pressing.

According to an advantageous embodiment of the invention, the first and/or second stop of the bushing is formed by a turning method in a machining step carried out before the providing step. In particular, contact surfaces of the first and second stop extending perpendicular to the axial direction are also formed in the turning method. According to an alternative embodiment, the bushing is provided as a deformation element. Preferably, the bushing is first shaped with a uniform wall thickness and the first and/or second stop is formed by deformation before the providing step. In particular, the first and/or second stop can be formed as a radial locking portion facing the center axis. In particular, the locking portions are spaced apart from one another in the circumferential direction and are preferably distributed uniformly over the inner circumference.

According to an advantageous embodiment of the invention, the pressing tool has an upper tool and a lower tool, wherein in the pressing step the bushing rests on the lower tool with a circular ring-shaped surface extending perpendicular to the axial direction and the second stop is pressed by the upper pressing tool. In particular, the axial edge of the bushing resting on the lower die is configured without corners, whereby a secure axial fastening and positioning can be achieved. In particular, the pressing force is applied by the upper die, while the lower die supports the opposite edge of the bush.

According to an advantageous embodiment of the invention, the bushing has a run-out groove running obliquely to the radial direction and the axial direction on the inner edge between the contact surface of the second stop and the cylindrical inner surface of the bushing. The undercut improves the positioning of the second stator element on the one hand and also supports the plastic deformation of the second stop during the fine pressing. The undercut is preferably formed by a turning process in the machining step.

The bushing according to an advantageous embodiment of the invention has a circumferential recess for reducing process forces occurring during the pressing step, wherein the recess is arranged below the second stop in the axial direction. The term "below" is used here to indicate that it is located further inward in relation to the axial direction than the position of the second stop. The recess is preferably formed in the machining step by a turning method.

Another subject of the invention is an axial-flux electrical machine manufactured by means of an embodiment of the method according to the invention. All the embodiments and advantages described in relation to the method are analogously transferred to the axial-flux machine according to the invention and vice versa.

Drawings

Further details and advantages of the invention are described below with reference to the embodiments shown in the drawings. In which is shown:

fig. 1 illustrates the structure of one embodiment of an axial-flux electric machine according to the present invention;

FIG. 2 shows the steps of a design of the method according to the invention;

fig. 3 shows two variants of the pressing step;

fig. 4 shows a schematic view of a robot arm with a drive motor unit according to the invention.

Detailed Description

The basic structure of an axial-flux electrical machine 10 produced by means of the method according to the invention is represented in fig. 1 in a perspective sectional view. Axial flux machine 10 is formed from two stator elements 1, 2 pressed into a cylindrical jacket-shaped bushing 4 and one rotor 3 arranged between stator elements 1, 2. The bush 4 and the stator elements 1, 2 are shown here partially cut away to be able to see the rotor 3 arranged in the interior. For the description of the geometry, an axial direction 21 running parallel to the center axis of axial flux machine 10, a radial direction 22 running perpendicular to axial direction 21, and a circumferential direction 23 around the center axis are introduced.

In the embodiment shown, the rotor 3 is formed by a base body 32 arranged on a sleeve 33, which has a plurality of recesses in the circumferential direction 23, in which circular segment-shaped permanent magnets 31 are arranged, which form the poles of the rotor 3. The matrix 32 can be formed, for example, by a compact made of Soft Magnetic Composite (SMC). Each of the two identically constructed stator elements 1, 2 is formed by a disk-shaped Multilayer Printed Circuit Board (multiplayer Printed Circuit Board) 14, which has a plurality of recesses arranged in the circumferential direction 23, with the exception of a centrally arranged through-opening 16, through which the sleeve 33 of the rotor 3 passes, which recesses are surrounded by coils forming a layer of the Circuit Board 14 (recesses and coils are not visible in the figure). In the recess a magnetizable body 15 of SMC is arranged, which forms the stator teeth of the respective stator element 1, 2 (see fig. 2 a). On the side of the stator elements 1, 2 pointing axially outward, an annular grounding element 5 is respectively glued to the circuit board 14, which is connected to the tooth body 15 or preferably formed in one piece therewith.

Axial-flux electric machine 10 is shown in a frameless design, which has neither bearings for rotor 3 nor an additional housing, and in which stators 1, 2 and rotor 3 are mounted directly in the machine, for example in a hinge. In the installed state, two axial recesses 7 are formed by the axial distance between the stator elements 1, 2 and the rotor 3, which recesses must have a precisely set axial width for the smooth operation of the engine 10, which axial width is to be constant over the entire axial extent of the recesses 7 as far as possible. However, fluctuations can be caused by the dimensional changes of the stator elements 1, 2 caused by the production, which fluctuations can be avoided or compensated for by the method according to the invention.

The steps of one embodiment of the method according to the invention are represented in fig. 2a to 2f, the axial-flux electric machine 10 formed in this case being shown in each case as a full-section illustration. In fig. 2a, a first pressing step is shown, in which the first stator element 1 is pressed into the bushing 4. For this purpose, the bush 4 has a first and a second stop 11, 12, each in the form of a stepped projection, which extends around the entire circumference of the inner wall of the bush 4. The first stator element 1 is constituted by a circuit board 14 having a through hole 16 arranged at the center and a ground portion 5 having a tooth main body 15. The extrusion dies 41, 42 are formed by an upper die 42, against which the upper edge of the bushing 4 rests, and a lower die 41, which presses the first stator element 1 into the bushing 4 from below. The stator element 1 is pressed into a block up to the first stop 11, so that the outwardly pointing end face 1A of the first stator element 1 forms a first end face 10A of the axial flux machine 10.

As shown in fig. 2b, the rotor 3 is then inserted into the bushing 4 in an insertion step. The rotor 3 is formed by a sleeve 33 on which the rotor base 32 and the magnet segments 31 are arranged (see fig. 1). After installation, a first (in this case downwardly pointing) end face 3A of the rotor 3 rests on an axially inwardly pointing end face 1B of the first stator element 1. Here, as shown in particular here, the rotor magnet 31 rests directly on the stator teeth 15 and is held in position by magnetic force. In this arrangement the rotor 3 and the stator element 1 are in mechanical contact, i.e. there is no gap between the two parts.

As shown in fig. 2c, in a first measuring step, the axial distance 18 between the upwardly directed end face 3B of the rotor 3 and the second stop 2 is determined, wherein the lower edge of the bush 4 is placed on the support element 17 in order to precisely position the bush 4 with respect to the axial direction 21. Since the second stop 12 substantially determines the axial position of the second stator element 2 (see fig. 2 e) and in the present arrangement there is no clearance from the first stator element 1 at the underside of the rotor 3, the axial free space of the rotor 3 between the stator elements 1, 2 is obtained by the distance 18, in other words, the space available for the axial clearance 7 in the mounted state of the axial flux machine 10 is provided precisely. From this distance 18, it is therefore possible to determine how much the axial position of the stop 12 must be corrected downward by fine-pressing (see fig. 2 d) if necessary in order to maintain the theoretical size of the total gap.

Fig. 2d shows a pressing step, in which the second stop 12 is pressed by the pressing dies 43, 44 according to the axial distance 18 determined in the first measuring step, so that the pressed second stop 13 can be used for correct axial positioning of the second stator element 2 (see fig. 2 e). The pressing dies 43, 44 are formed by a lower die 43, which supports the bushing 4 from below, and an upper die 44, which is selected such that the outer diameter 45 of the upper die corresponds to the radial dimension 25 of the second stator element 2 which is to be pressed into the bushing 4 in the next step. In this way, in addition to the finish pressing of the stop 12, the inner diameter of the bush 4 can be widened, if necessary, by means of the die 44 in order to compensate for fluctuations in the radial dimension 25 of the second stator element 2.

As shown in fig. 2e, the second stator element 2 is pressed into the bushing in a second pressing step. The press tools 46, 47 are in turn formed by a lower tool 46 and an upper tool 47, the lower tool 46 supporting the bushing 4 from below, and the upper tool 47 pressing the second stator element 2 into the bushing 4 from above as far as the finish-pressed stop 13. The selection of the diameter 45 of the pressing tool 44 in the pressing step is such that the inner diameter of the bush 4 above the stop 13 matches the diameter 25 of the second stator element 2. By means of the precisely adjusted position of the finely pressed stop 13 in relation to the dimensions of the arrangement, the interior space between the two stator elements 1, 2 is configured in such a way that, when installed, by means of a corresponding positioning of the rotor 3, two uniform interspaces 7 are obtained between the rotor 3 and the double stators 1, 2, the axial width of the interspaces corresponding to the theoretical preset. In fig. 2e the section plane (as in fig. 2 d) extends through the base body 32 of the rotor 3, but the same spatial arrangement of the rotor 3, the first stator element 1 and the bushing 4 is shown, as in fig. 2a to 2d, wherein the section plane instead extends through the magnet segments 31 of the rotor 3 (see the sequence of the segments of the base body 32 and the permanent magnets 31 in the circumferential direction of the rotor 3 in fig. 1).

Finally, as shown in fig. 2f, in a third measurement step following the production process, the axial gap 26 is measured and checked whether the desired setpoint value is maintained. The bush 4 is placed on the support element 17 and is acted upon from above by a force 19 acting in the axial direction 21, while the rotor 3 moves back and forth in the assembly of the bush 4 and the stator 1, 2.

Fig. 3a and 3b show two variants of the pressing step (see fig. 2 d). The two figures each show a sectional view of the bush 4, wherein the radially outwardly pointing face of the bush 4 is shown on the right in the figures. In both cases the bushing 4 rests flat on the lower die 46 and is secured in this way in the axial direction 21. The axially lower edge of the bush 4 has for this purpose a circular ring-shaped surface 8 extending perpendicularly to the axial direction, i.e. is formed without corners. The axial force required for coining the second stop 12 is applied from above by the upper die 47. The contour of the stop 12 is shown in detail in the two figures in enlarged detail. The bush has, on its inner edge between the contact surface 27 of the second stop 2 and the cylindrical inner surface 9 of the bush 4, a circumferential undercut 28 extending obliquely to the radial direction 22 and the axial direction 21, which not only improves the positioning of the second stator element 2, but also simplifies the plastic deformation of the stop 2 during fine pressing. In the variant shown on the right, the bushing 4 has, in addition to the undercut 28, a circumferential recess 29 arranged below the stop 2, which serves to reduce the process forces occurring during the pressing step.

In fig. 4, a schematic illustration of a robot arm 30 is represented, in the joints of which an embodiment of the drive motor unit 20 according to the invention is constructed. The drive motor unit 20 has an embodiment of the axial-flux motor 10 according to the present invention and a transmission, respectively, via which torque for rotating the hinge portion of the robot arm 30 is generated. The axial flux machine can also be part of an integrated drive unit with the axial flux machine 10, the transmission, the joint bearing and the torque sensor, which is inserted into the robot arm 30 in a preassembled form as an integrated component.

List of reference numerals

1. First stator element

1A outwardly directed end face of a first stator element

1B inwardly directed end faces of first stator elements

2. Second stator element

2A outwardly directed end face of the second stator element

3. Rotor

First end face of 3A rotor

Second end face of 3B rotor

4. Bushing

5. Ground part

7. Axial gap

8. Placing surface

9. Inner surface of the bush

10. Axial flux electric machine

First end face of 10A axial flux electric machine

Second end face of 10B axial flux machine

11. First stop

12. Second stop

13. Second stop by fine pressing

14. Circuit board

15. Stator tooth

16. Central through hole of circuit board

17. Supporting element

18. Distance between rotor and second stop

19. Force of

20. Drive motor unit

21. Axial direction of the shaft

22. Radial direction

23. In the circumferential direction

25. Radial dimension of the second stator element

26. Axial clearance

27. Contact surface of the stop

28. Tool withdrawal groove

29. Notch (S)

30. Robot arm

31. Permanent magnet

32. Rotor base body

33. Sleeve of rotor

41. Lower die for pressing in first stator element

42. Upper die for pressing in first stator element

43. Lower die for precisely pressing bushing

44. Upper die for precisely pressing bushing

45. Radial dimension of die

46. Lower die for pressing in a second stator element

47. Upper die for pressing in a second stator element

Claims (10)

1. Method for producing an axial flux machine (10), wherein the axial flux machine (10) has a disk-shaped rotor (3), a disk-shaped first and second stator element (1, 2) and a cylindrical jacket-shaped bushing (4), wherein the rotor (3) is arranged between the two stator elements (1, 2) in an axial direction (21) of the axial flux machine (10) and the bushing (4) surrounds the rotor (3) and the two stator elements (1, 2) in a radial direction (22), wherein the method has the following steps:

-providing a bushing (4) in a providing step, wherein the bushing (4) has a first and a second stop (11, 12) which are spaced apart from each other in an axial direction (21) and which extend respectively circumferentially over at least a part of an inner circumference of the bushing (4);

-in a first pressing step the first stator element (1) is pressed into the bushing (4) up to the first stop (11) such that an axially outwardly directed end face (1A) of the first stator element (1) forms a first end face (10A) of the axial flux machine (10);

-in a loading step, loading the rotor (3) into the bushing (4) such that a first end face (3A) of the rotor (3) rests on an axially inwardly directed end face (1B) of the first stator element (1);

-determining an axial distance (18) between a second end face (3B) of the rotor (3) and the second stop (12) in a first measuring step;

-determining a radial dimension (25) of the second stator element (2) in a second measurement step;

-fine-pressing the second stop (12) in a pressing step by means of a pressing die (43, 44) according to the axial distance (18) determined in the first measuring step, wherein the pressing die (43, 44) is selected such that a radial dimension (45) of the pressing die (43, 44) corresponds to a radial dimension (25) of the second stator element (2) determined in the second measuring step;

-pressing the second stator element (2) into the bushing (4) up to a finish-pressed stop (13) in a second pressing step, such that an axially outwardly directed end face (2A) of the second stator element (2) forms a second end face (10B) of the axial flux machine (10).

2. Method according to claim 1, characterized in that the axial play (26) between the rotor (3) and the stator element (1, 2) pressed into the bushing (4) is determined in a third measuring step following the second pressing step.

3. Method according to claim 1 or 2, characterized in that in the insertion step the rotor (3) is inserted into the bushing (4) such that a sleeve (33) of the rotor (3) passes through a through hole (16) arranged in the center of the first stator element (1), wherein the rotor (3) is placed in particular on an axially inwardly directed end face (1B) of the first stator element (1) such that magnets (31) of the rotor (3) are in mechanical contact with stator teeth (15) of the first stator element (1).

4. Method according to one of the preceding claims, characterized in that the first and/or second stop (11, 12) is configured as a projection or step and has a contact surface (27) extending perpendicularly to the axial direction (21), wherein the first and/or second stator element (1, 2) forms a mechanical contact with the contact surface (27) upon pressing-in.

5. Method according to any one of the preceding claims, characterized in that in a machining step carried out before the providing step, the first and/or second stop (1, 2) of the bush (4) is formed by a turning method.

6. Method according to one of the preceding claims, characterized in that the pressing die (43, 44) has an upper die (44) and a lower die (43), wherein in the pressing step the bushing (4) rests on the lower die (46) with a circular ring-shaped face (8) running perpendicular to the axial direction (21) and the second stop (2) is coined by an upper pressing die (47).

7. Method according to claim 4, characterized in that the bushing (4) has a run-out (28) on the inner edge between the contact surface (27) of the second stop (2) and the cylindrical inner surface (9) of the bushing (4) which runs obliquely with respect to the radial direction (22) and the axial direction (21).

8. Method according to any one of the preceding claims, characterized in that the bushing (4) has a circumferential recess (29) for reducing process forces occurring in the pressing step, wherein the recess (29) is arranged in the axial direction (21) below the second stop (2).

9. Axial-flux electric machine (10) manufactured according to the method of any one of claims 1 to 8.

10. Drive motor unit (20), in particular for a robotic articulated arm (30), having an axial flux motor (10) according to claim 9.

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