Method for producing a rigid connection between a laminated core and an inner hollow component
Patent Information
- Application Number
- EP2023785973
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-09-14
- Filing Date
- 2023-09-14
- Publication Date
- 2025-07-23
AI Technical Summary
Existing methods for establishing a connection between a laminated core and an internally hollow component, such as in electrical machine rotors, face issues with dimensional accuracy, risk of short circuits, and contamination due to high-pressure expansion, which compromises the electromagnetic properties and requires complex cleaning.
Incorporating an elastic deformation element within the internally hollow component to control its expansion from the inside out, applying radial pressure to avoid axial forces on the sheet metal parts and prevent contamination, while ensuring a stable and reproducible connection.
This method minimizes damage to the laminated core, maintains its electromagnetic properties, and reduces the need for cleaning, achieving a robust and reliable connection with reduced risk of contamination and improved forming behavior.
Smart Images
Figure 1.1
Abstract
Description
[0001] Method for producing a fixed connection between a laminated core and an internally hollow component
[0002] Technical area
[0003] The invention relates to a method for producing a fixed connection between a laminated core, which has a plurality of sheet metal parts firmly connected to one another, in particular by a material bond, and an internally hollow component, in which the internally hollow component is provided in a recess in the laminated core and is widened from the inside outwards in its longitudinal section lying within the laminated core in order to thereby produce the fixed connection between the component and the laminated core.
[0004] State of the art
[0005] In order to create a stable connection between a hollow shaft and a laminated core made up of sheet metal parts or laminations of a rotor of an electrical machine, DE102018218322A1 proposes expanding the hollow shaft inserted into a recess in the laminated core over its entire length by applying high pressure. The hollow shaft is then formed according to the star-shaped recess in the cross-section. The disadvantage is that the individual bonded sheet metal parts experience not only radial but also axial forces during the expansion of the hollow shaft, which compromises the dimensional accuracy of the sheet metal parts and increases the risk of short circuits between them. A deterioration in the electromagnetic properties of the laminated core is therefore to be expected. Furthermore, pressure medium escaping during internal high-pressure forming can lead to contamination of the laminated core, which can, for example, cause undesirable corrosion of the laminated core.Therefore, complex cleaning measures are usually required for sheet packages manufactured in this way.
[0006] Description of the invention
[0007] The object of the invention is therefore to modify a prior art method for producing a fixed connection between a laminated core and a hollow component in such a way that this mechanical connection can be produced with as little damage to the laminated core as possible, and with as little impairment as possible to its electromagnetic properties. Furthermore, this method should reduce the need for cleaning the laminated core produced with it.
[0008] The invention solves the problem by the features of claim 1.
[0009] By inserting an elastic deformation element into the internally hollow component and using this deformation element to expand the internally hollow component from the inside outward in a partial section of the longitudinal section by exerting pressure, whereby during expansion, the deformation element rests against the internally hollow component with a contact surface located in the region of the partial section, a controlled expansion of the hollow shaft can be achieved according to the invention in specific sections. This is because expansion occurs from the inside outward in a partial section of the longitudinal section covered by the laminated core. The internally hollow component is thus partially expanded in the longitudinal section covered by the laminated core.For example, this makes it possible to avoid unwanted, perhaps only specific, contact between the joining partners – which occurs, for example, during high-pressure forming with relatively uncontrolled expansion and thus leads to an increased risk of axial compressive forces on the sheet metal parts of the laminated cores. With the radial compressive forces according to the invention, there is no risk of fractures in the adhesive joints between the sheet metal parts. Therefore, by exploiting the robustness of the sheet metal parts against radial compressive forces, a reproducible, strong connection (positive and / or non-positive) between the laminated core and the internally hollow component can be created with little risk of damage. This also allows, for example, an interference fit that can transmit relatively hollow torques – which is required, for example, in a shaft connection between the internally hollow component and the laminated core.
[0010] In addition, such expansion of the internally hollow component with an elastic deformation element can prevent contamination of the laminated core with a hydraulic fluid used in the internal high-pressure process.
[0011] Using the method according to the invention, laminated cores can therefore be produced with less damage and free of contamination.
[0012] The contact surface on the hollow component can be full-surface, which applies more even load to the hollow component and can lead to improved forming behavior. It can also be provided that the contact surface runs around the hollow component, which applies more even load to the hollow component and can lead to further improved forming behavior.
[0013] For example, the deformation element exerts pressure on the hollow component exclusively in a radial outward direction, ensuring essentially radial compressive forces on the sheet metal parts of the laminated core. This further reduces the risk of damage.
[0014] Preferably, the contact surface is spaced from both ends of the section at a distance corresponding at least to the wall thickness of the internally hollow component in the region of the respective end of the section. This avoids, among other things, the risk of axial compressive forces acting on the sheet metal parts of the laminated core. A particularly strong, positive and / or force-fitting connection can be achieved if, after the internally hollow component has been expanded, it rests against the recess over its entire surface in the section.
[0015] Furthermore, it is conceivable that the recess in the laminated core has at least one undercut, and that the partial section of the longitudinal section lies within the longitudinal extent of the undercut in order to mechanically reinforce the firm connection between the laminated core and the internally hollow component.
[0016] If the undercut in the recess is provided completely around the circumference, this can further strengthen the positive connection and further increase the stability of the fixed connection between the sheet stack and the internally hollow component.
[0017] Preferably, the recess has a plurality of undercuts arranged axially and / or radially offset from one another at an angle to ensure the torsion resistance of the fixed connection between the laminated core and the internally hollow component.
[0018] If the undercut has a rounded contour, this can, for example, avoid singular loads on the sheet stack and thus further reduce any risk of damage.
[0019] In particular, the internally hollow component can be expanded with little risk of damage if an expansion lance with the deformation element is used.
[0020] High reproducibility in the process can result if the expansion lance has at least one axially movable pressure element, which preferably acts axially on the deformation element in order to deform it outwards in the radial direction. For example, a hollow shaft can be provided as an internally hollow component, which is provided in a central recess of the laminated core in order to create, for example, a rotor for an electrical machine.
[0021] Alternatively, it is conceivable to provide a connecting pin as an internally hollow component, which is provided in a preferably eccentric recess.
[0022] In this case, for example, a connection between laminated cores can be made by firmly connecting the connecting pin that is firmly connected to the laminated core to a second laminated core.
[0023] Short description of the drawings
[0024] The figures show, for example, the subject matter of the invention in more detail using several embodiments.
[0025] Fig. 1 is a sectional view of a device for carrying out a method for producing a fixed connection between a laminated core and an internally hollow component,
[0026] Fig. 1 a is a detailed view of Fig. 1 ,
[0027] Fig. 2 is a sectional view of the rotor manufactured according to Fig. 1 from a laminated core and a hollow shaft as an internally hollow component according to a first embodiment and
[0028] Fig. 3 is an exploded view of two laminated cores firmly connected to one another according to a second embodiment, produced with a device according to Fig. 1.
[0029] Way to implement the invention
[0030] Fig. 1 shows, for example, a device 1 for carrying out the method according to the invention. This device 1 serves to create a fixed connection between a laminated core 2 and an internally hollow component 3. The laminated core 2 comprises sheet metal parts 4 that are integrally connected to one another, for example, formed by a cured adhesive layer provided between the sheet metal parts 4, for example, a thermosetting hot-melt adhesive layer, in particular a self-bonding varnish.
[0031] The internally hollow component 3 of Figure 1 is a hollow shaft 3a, which is provided in a central recess 5 of the laminated core 2. The recess 5 completely penetrates the laminated core 2 as a cutout.
[0032] The firm mechanical connection between the internally hollow component 3 and the laminated core 2 is created by expanding the internally hollow component 3 - namely, the internally hollow component 3 is expanded from the inside to the outside in the longitudinal section A covered by the laminated core 2.
[0033] According to the invention, this expansion takes place only partially, namely in a partial section Ap in the covered longitudinal section A - as can be seen in Figure 1. For this purpose, an elastic deformation element 6, for example made of a plastic material, is introduced into the internally hollow component 3 and with this a pressure D is exerted on the internally hollow component 3 in a partial section Ap of the longitudinal section A in a radial outward direction, i.e. radial to the z-axis in the xy-plane, as shown in Fig. 1. The internally hollow component 3 is thus partially expanded in the longitudinal section A.
[0034] Therefore, forces acting on the lamination parts 4 of the laminated core 2 are essentially radially directed, which avoids forces in the axial direction, i.e., in the z-axis, during expansion and thus guarantees a high degree of freedom from damage to the laminated core 2. The electromagnetic properties of the laminated core 2 therefore remain virtually unaffected by the mechanically strong connection to the hollow shaft 3a, resulting in high reproducibility in the production of a short-circuit-free rotor, which rotor is shown in Fig. 2.
[0035] As can be seen from Fig. 1, the recess 5 has an undercut 7. Here, namely in the partial section Ap, which is covered by the undercut 7, the internally hollow component 3 is expanded by the deformation element 6. As can be seen in Fig. 1a, the deformation element 6 has a contact surface 8 on the internally hollow component 3, which is spaced 10 from the ends 9a, 9b of the partial section Ap. This space 10 corresponds at least to the wall thickness d of the internally hollow component 3 in this area. This also reduces, among other things, the risk of axial forces acting on the sheet metal parts 4 of the laminated core 2.
[0036] The undercut 7 is also provided circumferentially in the recess 5 - which creates a stable mechanical connection between the laminated core 2 and component 3. To ensure uniform expansion for this circumferential recess, the deformation element 6 also rests with the contact surface 8 on the internally hollow component 3.
[0037] In addition, the recess 5 has two axial undercuts 7, 11 arranged offset from one another at an angle a in order to increase the torsional stability between the laminated core 2 and the component 3.
[0038] Both undercuts 7, 11 also have a rounded outer contour 12, so that the hollow component 3 can slide over the outer contour 12 during expansion. This further deburrs the adhesive bond between the sheet metal parts 4.
[0039] This is all the more true when, during expansion of the internally hollow component 3, it is pressed into the recess 5, exclusively in the radial direction.
[0040] As shown in Fig. 1, the expansion takes place with an expansion lance 13, which encompasses the deformation element 6. The expansion lance 13 has two axially movable pressure elements 14a, 14b, which act axially with a force F on the elastic deformation element 6. As a result, the elastic deformation element 6 deforms radially outward. According to Fig. 3, a second embodiment shows a fixed mechanical connection between two laminated cores 16, 17, which is produced using the method according to the invention, as shown in Figs. 1 and 1a for the first embodiment.
[0041] Here, a connecting pin 3b is provided as an internally hollow component 3, each of which is provided in an eccentric recess 15 on the two laminated cores 16, 17. These eccentric recesses 15 are formed, for example, by continuous cutouts in the laminated cores 16, 17.
[0042] By expanding the connecting pins 5b according to the invention using the expanding lance 13 shown in Fig. 1, the two sheet packages 16, 17 are firmly connected to one another.
[0043] In general, it is noted that "in particular" can be translated into English as "more particularly." A feature preceded by "in particular" is to be considered an optional feature that can be omitted and thus does not constitute a limitation, for example, of the claims. The same applies to "vorzugsweise," translated into English as "preferably."
Claims
P a t e n t a n s p r ü c h e: 1 .Method for producing a fixed connection between a laminated core (2, 16, 17), which has a plurality of sheet metal parts (4) firmly connected to one another, in particular by means of a material bond, and an internally hollow component (3), in which the internally hollow component (3) is provided in a recess (5, 15) in the laminated core (2, 16, 17) and is widened from the inside outwards in its longitudinal section (A) lying within the laminated core (2, 16, 17) in order to thereby produce the fixed connection between the component (3) and the laminated core (2, 16, 17), characterized in that an elastic deformation element (6) is introduced into the internally hollow component (3) and with this deformation element (6) by exerting a pressure (D) the internally hollow component (3) is widened from the inside outwards in a partial section (Ap) of the longitudinal section (A), wherein during the expansion the deformation element (6) on the internally hollow Component (3) rests against a contact surface (8) which is located in the area of the partial section (Ap).
2. Method according to claim 1, characterized in that the contact surface (8) bears against the internally hollow component (3) over its entire surface, in particular in a closed, circumferential manner on the inside.
3. Method according to one of claims 1 to 2, characterized in that the deformation element (6) exerts a pressure (D) on the internally hollow component (3) exclusively in the radial outward direction.
4. Method according to one of claims 1 to 3, characterized in that the contact surface (8) has a distance (10) from each of the two ends (9a, 9b) of the partial section (Ap), which distance (10) corresponds at least to the wall thickness (d) of the internally hollow component (3) in the region of the respective end (9a, 9b) of the partial section (Ap).
5. Method according to one of claims 1 to 4, characterized in that after the expansion of the internally hollow component (3), the latter rests against the recess (5, 15) over its entire surface in the partial section (Ap).
6. Method according to one of claims 1 to 5, characterized in that the recess (5, 15) in the laminated core (2, 16, 17) has at least one undercut (7, 11), and that the partial section (AP) of the longitudinal section (A) lies within the longitudinal extent of the undercut (7, 11).
7. Method according to claim 6, characterized in that the undercut (7) in the recess (5, 15) is provided completely circumferentially.
8. Method according to one of claims 6 to 7, characterized in that the recess (5) has a plurality of undercuts (7, 11) arranged axially offset from one another and / or radially offset from one another at an angle.
9. Method according to one of claims 6 to 8, characterized in that the undercut (7, 11) has a rounded contour.
10. Method according to one of claims 1 to 9, characterized in that an expanding lance (13) is used with the deformation element (6).
11. Method according to claim 10, characterized in that the expanding lance (13) has at least one axially movable pressure element (14a, 14b) which preferably acts axially on the deformation element (6) in order to deform it outwards in the radial direction.
12. Method according to one of claims 1 to 11, characterized in that a hollow shaft (3a) is provided as an internally hollow component (3), which is provided in a central recess (5) of the laminated core (2).
13. Method according to one of claims 1 to 11, characterized in that a connecting pin (3b) is provided as an internally hollow component (3) which is provided in a preferably eccentric recess (15).
14. Method according to claim 13, characterized in that the connecting pin (5b) firmly connected to the laminated core (16) is firmly connected to a second laminated core (17).