Laminated Core and Method for Producing Same

Abstract

The laminated core (12) comprises laminations (10), which are arranged one over the other and which are each connected to each other by means of a first connection (9, 15). In addition, at least some of the laminations (10) are connected to each other by means of a second connection (11). By using two connections, the advantages thereof can be bundled, whereby the number and/or size of the connection points can be reduced while the requirement for the laminated core (12) remains the same or very high requirements for the laminated core (12) can be met or even increased. Advantageously, an adhesive is used as one of the connections (11), while the other connection (9, 15) can be a form-fitting connection. The adhesive (11) is applied to the lower side (13) and/or upper side (14) of the laminations (10) before or after the punching of the laminations (10). However, the two connections can also be formed by two adhesive systems. Finally, the connections (9, 10; 11) can also be formed by at least one weld seam and additionally by an adhesive.

Claims

1.-19. (canceled)

20. A laminated core comprising laminations arranged on top of each other, the laminations connected to each other by a first connection, respectively, wherein at least some of the laminations are connected to each other by a second connection, respectively.

21. The laminated core according to claim 20, wherein the first connection is a force-locked connection.

22. The laminated core according to claim 21, wherein the laminations include a first lamination and a second lamination next to the first lamination, wherein the force-locked connection comprises at least one projection in the first lamination and at least one depression in the second lamination, wherein the at least one projection engages with friction fit the at least one depression.

23. The laminated core according to claim 22, wherein the at least one projection is an embossment in the first lamination.

24. The laminated core according to claim 20, wherein the second connection is a material fusion connection.

25. The laminated core according to claim 24, wherein the material fusion connection is an adhesive connection formed by at least one partial adhesive application.

26. The laminated core according to claim 20, wherein the first and the second connections are provided approximately in the same area on the laminations.

27. The laminated core according to claim 20, wherein the first and the second connections are provided in different areas of the laminations.

28. The laminated core according to claim 20, wherein the first and the second connections are material fusion connections formed at least by a first adhesive system and a second adhesive system.

29. The laminated core according to claim 28, wherein the first adhesive system is fast-curing.

30. The laminated core according to claim 29, wherein the second adhesive system is permanent resistant.

31. The laminated core according to claim 20, wherein the first connection is at least one weld connection and the second connection is formed by at least one at least partial adhesive connection.

32. The laminated core according to claim 31, wherein the at least one weld connection is at least one weld seam.

33. The laminated core according to claim 31, wherein the at least one at least partial adhesive connection is formed by at least one partial adhesive application.

34. A method for producing a laminated core according to claim 20, the method comprising: punching laminations from a metal strip and providing the laminations with projections and depressions; forming a laminated core by subsequently stacking the laminations and force-locking the laminations with each other by engagement of the projections in the depressions; before or after punching, applying an adhesive onto a bottom side and/or a top side of the laminations.

35. The method according to claim 34, wherein the adhesive is applied in an area away from the projections and depressions.

36. The method according to claim 34, wherein the adhesive is applied onto the projections.

37. A method for producing a laminated core according to claim 20, the method comprising: punching laminations from a metal strip; subsequently stacking the laminations to a laminated core, applying two adhesive systems to a bottom side and/or a top side of the laminations.

38. A method for producing a laminated core according to claim 20, the method comprising: punching laminations from a metal strip; subsequently stacking the laminations to a lamination core and connecting the laminations by material fusion to each other by at least one weld seam; before or after punching the laminations, applying an adhesive onto a bottom side and/or a top side of the laminations.

Description

[0035] The invention will be explained with the aid of embodiments illustrated in the drawings in more detail. It is shown in:

[0036] FIG. 1 in schematic illustration a punching operation for performing the method according to the invention;

[0037] FIG. 2 in schematic illustration a punching tool with an adhesive unit arranged upstream;

[0038] FIGS. 3a and 3b a station in the adhesive unit and various stations in the punching tool according to FIG. 2;

[0039] FIG. 4a to 4c different stages for producing a laminated core according to a first embodiment of the method according to the invention;

[0040] FIG. 5a to 5c different stages for producing a laminated core according to a second embodiment of the method according to the invention;

[0041] FIGS. 6a and 6b different stages for producing a laminated core according to a third embodiment of the method according to the invention;

[0042] FIG. 7a to 7b different stages for producing a laminated core according to a fourth embodiment of the method according to the invention.

[0043] For producing the laminated core, a metal strip 1 is employed that is wound as a coil onto a reel 2. The metal strip 1 can be a coated or uncoated, wide or narrow strip. The metal strip 1 is advantageously passed through a straightening apparatus 3 so that in the downstream punching press 4 the laminations can be punched cleanly from the metal strip 1. In the punching press 4, there is at least one punching tool 5 that has at least one adhesive unit 6 arranged upstream thereof, integrated therein, or arranged downstream thereof.

[0044] The laminations can be punched from the metal strip 1 in one or several tracks so that the material waste is minimal.

[0045] By means of the adhesive unit 6, in a way still to be described, adhesive is applied onto the metal strip in such a way that laminations resting on each other within the laminated core can be reliably and fixedly connected to each other. The adhesive is applied partially onto the laminations, for example, punctiform.

[0046] In the first station of the punching tool 5 the inner diameters 7 are punched as well as the embossments 9 for the punch stacking connection which surround the inner diameters 7 at a spacing. In the second station of the punching tool 5, a circular ring-shaped lamination 10 is punched whose outer diameter is illustrated by the dashed line. The punched-out lamination 10 is pushed out of the metal strip 1 and pressed into an assembly unit in which the laminations in a way known in the art are layered, resting on top of each other, to a laminated core 12.

[0047] By means of the punching process according to FIGS. 1 to 3, the laminated cores are produced whose laminations 10 are connected to each other by a hybrid connection within the core 12. In this embodiment, the hybrid connection between the laminations 10 is comprised of a force-locked connection as well as a material fusion connection between the laminations 10 resting on top of each other.

[0048] In order to produce this hybrid connection, during the first stroke of the punching tool 5 the adhesive 11 is applied onto the metal strip 1 at the required location, the inner diameter 7 is punched, and the embossments 9 are produced. Subsequently, the metal strip is transported farther by an advancing length.

[0049] During the next stroke of the punching press 4, the adhesive 11 is applied by means of the adhesive unit 6 at the required location of the metal strip. In the first station of the punching tool 5, the inner diameters 7 are punched as well as the embossments 9 generated and in the second punching station the annular lamination 10 is punched out. It is pushed out in the way known in the art from the metal strip 1 and pushed downwardly into the bottom die of the punching press 4 in which the laminations are stacked to the laminated core 12 in the way known in the art. Subsequently, the metal strip 1 is further transported by an advancing length. Subsequently, during the next stroke of the punching press 4, the adhesive is applied at the required location onto the metal strip 1, in the first station of the punching tool 5 the inner diameter 7 is punched out as well as the embossments 9 produced and in the second punching station the annular lamination 10 is punched out and pushed downward into the bottom die. In this way, the laminations 10 are sequentially punched out of the metal strip 1 which is further transported between sequential punching strokes by one advancing length, respectively. In the bottom die, the connection of the laminations 10 resting on top of each other takes place by adhesive connection and by form-fit connection by means of the embossments 9 which have been embossed into the laminations 10.

[0050] FIG. 4 shows in schematic illustration the different stages during manufacture of the laminated core 12 formed by the hybrid connection. First, the adhesive 11 is applied to the metal strip 1 and is preferably an adhesive drop applied at suitable locations of the metal strip. Since the individual laminations are connected to each other with form fit within the laminated core 10 by the embossments 9, the adhesive points 11 are applied onto the metal strip 1 in the area outside of the embossments 9. So that the adhesive 11 does not interfere with the process for producing the embossments 9, the adhesive is applied, for example, to the bottom side 13 of the metal strip 1.

[0051] The adhesive 11 can be applied in any suitable way onto the metal strip 1. It is preferred when the adhesive 11 is applied contactless to the metal strip 1.

[0052] The embossments 9 are produced by a deformation process in that the appropriate plungers, distributed about the circumference, plastically deform the metal strip 1 locally. The embossments 9 project past the bottom side 13 of the metal strip. At the level of the embossments 9, corresponding depressions 15 are formed on the top side 14 of the metal strip 1 (FIG. 4b). After punching out the annular laminations 10 from the metal strip 1, they are assembled in the bottom die of the punching press 4 to laminated core 12. The laminations 10 are placed in such a way on top of each other that the embossments 9 of the respective upper lamination 10 engages the depressions 15 of the respective lower lamination 10, as indicated in FIG. 4c in an exemplary fashion for two laminations 10 resting on top of each other. The adhesive 11 is located at the bottom side 13 of the respective upper lamination 10 in the area outside of the embossments 9. For example, a drop of the adhesive 11 can be present, respectively, between neighboring embossments 9 in circumferential direction. The adhesive 11 is applied such that it is slightly thicker than the resulting gap between the respective lower lamination 10 and the upper lamination 10. In this way, the adhesive 11 upon joining the laminations 9 is spreading so that a secure adhesive connection of the laminations 9 resting on top of each other within the laminated core is formed (FIG. 4c).

[0053] The embossments 9 are designed such that they engage with press fit the depressions 15 of the respective lower lamination. In this way, a laminated core 12 is formed whose laminations 10 by means of the embossments 9 are fixedly connected to each other wherein the adhesive 11 contributes additionally to the connection of the laminations 10 resting on top of each other. The described hybrid connection enables reducing the number and/or the size of the connecting locations without having to fear limitations with regard to the functionality of the produced laminated core 12.

[0054] In the described embodiment, the laminated core 12 is produced within the punching press 4. In principle, the laminated core can also be produced outside of the punching press 4. Also, it is possible to apply the adhesive onto the metal strip outside of the punching press 4 and not within it.

[0055] In the described laminated core 12, the adhesive points 11 are provided in distribution about the circumference of the annular lamination 10 so that a secure adhesive connection between the laminations 10 resting on top of each other is ensured.

[0056] The adhesive 11 can be applied not only punctiform but also areally onto the lamination 10.

[0057] FIG. 5 shows a further possibility of a hybrid connection between laminations 10 resting on top of each other within a laminated core 12. In this embodiment, first the inner diameters 7 (FIG. 3) are punched into the metal strip 1 as well as the embossments 9 applied which project past the bottom side 13 of the lamination 10. Only subsequently, the adhesive 11 is applied onto the bottom side 13. In contrast to the previous embodiment, the adhesive 11 is applied in the area of the embossments 9 onto the bottom side 13 of the lamination 10. In this way, the embossments 9 are enveloped by the adhesive 11. The embossments 9 are again distributed about the circumference of the annular lamination.

[0058] After punching from the metal strip 1, the laminations 10 are stacked in the punching press 4, or also outside thereof, for forming the laminated core 12 (FIG. 5c). The embossments 9 of the respective upper lamination 10 engage the corresponding depressions 15 of the respective lower lamination 10. The laminations are stacked with pressure application in accordance with the preceding embodiment. The embossments 9 engage with friction the depressions 15 of the respective lower lamination 10 so that a force-locked connection in axial direction of the laminated core 12 between the laminations 10 resting on top of each other is achieved. At the same time, upon placement of the respective upper lamination 10. the adhesive 11 is displaced such that it is also positioned outside of the embossments 9 and connects the laminations 10 positioned underneath with each other. The adhesive 11 surrounds in this context the respective embossment 9 (FIG. 5c).

[0059] In this embodiment, the hybrid connection between the individual laminations 10 of the laminated core 12 is also comprised of the form-fit/friction connection between the embossments 9 and the depressions 15 as well as the adhesive connection 11.

[0060] In this embodiment, the adhesive 11 can be applied also within or outside of the punching press 4. In this variant, first the embossment process is carried out in order to generate the embossments 9 on the metal strip 1. Only subsequently, the adhesive 11 is applied. In the embodiment according to FIG. 4, on the other hand, first the adhesive 11 is applied before the metal strip 1 is embossed for producing the embossments 9.

[0061] The height of the laminated core 12 is determined in that a lamination 10 is formed with through holes. This is indicated in an exemplary fashion by the dashed lines in FIG. 4c.

[0062] For forming the next laminated core 12, a cover sheet is therefore first produced that comprises through holes. Then, in the described way the laminations can be placed on this cover sheet until again a cover sheet with through holes determines the height of the lamination stack 12. In this embodiment, the height of the laminated core 12 is also determined in that the employed adhesive is formed by interruption of application.

[0063] In the embodiment according to FIG. 6, the hybrid connection between the laminations resting on top of each other is produced by two adhesive connections. First, in the adhesive unit 6, the adhesive 16 and the adhesive 17 are arranged in the area of the inner diameter 7 in distribution about the circumference of the annular lamination 10 on the metal strip 1 (FIG. 3b). In this embodiment, the adhesive 16 acts as a fast connection in order to enable parts handling of the laminated core 12 directly after punching. The adhesive 17 serves as a permanent resistant connection with optimal properties of the laminated core 12 and cures with time delay in the gap between the upper lamination 10 and the lower lamination 10 of the laminated core 12.

[0064] The application of the two adhesives 16 and 17 in this embodiment can be done within the punching press 4 but also outside of it. The adhesive 16 is preferably applied contactless and punctiform to the upper lamination side 14 and/or lower lamination side 13. The adhesive 17 is preferably applied areally onto the upper lamination side 14 and/or lower lamination side 13. The resulting material fusion connection of the adhesive 16 can be enclosed by the second material fusion connection, resulting from the adhesive 17, completely between the lower lamination 10 and the upper lamination 10. In a beneficial embodiment, the adhesive 16 and the adhesive 17 can be mixed with each other. Mixing of the two adhesives 16 and 17 or adhesive systems can be realized during the punching operation or outside thereof.

[0065] In the manufacture of the sheet metal packet of two laminations 10 connected to each other with material fusion, the adhesive 16 and/or adhesive 17 are applied onto the metal strip 1 and the inner diameter 7 is applied in a first stroke of the punching press 4. Subsequently, it is further transported by an advancing length. With the next stroke of the punching press 4, the two adhesives 16 and 17 are applied again onto the metal strip 1, the inner diameter 7 is punched in the first station in of the punching tool 5, and the lamination 10 is cut out of the metal strip 1 in the second station of the punching tool.

[0066] In this embodiment, the height of the laminated core 12 is determined in that the employed adhesives are formed by interruption of application. In this way, on the uppermost lamination 10 no subsequent lamination 10 can be attached.

[0067] In the embodiment according to FIG. 7, the hybrid connection between the laminations 10 resting on top of each other is generated by weld connections 18 and an adhesive connection 19. On the metal strip 1, first the adhesive 19 is applied in the adhesive unit 6 at the required location on the metal strip (FIG. 7a).

[0068] In this embodiment, the weld connection 18 acts as a fast connection in order to enable parts handling of the laminated core 12 directly after punching. The adhesive 19 serves as a permanent resistant connection with optimal properties of the laminated core 12 and cures with time delay in the gap between the respective upper lamination 10 and the respective lower lamination 10 of the laminated core 12.

[0069] The application of the weld seam 18 is realized in the joining unit of the punching tool. The application of the adhesive 19 in this embodiment can take place within the punching press 4, but also outside of it. The adhesive 19 is preferably applied contactless and punctiform onto the upper lamination side 14 and/or lower lamination side 13.

[0070] The height of the laminated core 12 in this embodiment is determined in that the application of the weld seam and of the adhesive are interrupted. Accordingly, on the uppermost lamination 10 of the laminated core 12 no subsequent lamination 10 can be attached.

[0071] The described hybrid connection enables reducing the number and/or the size of the connecting locations without having to fear limitations with regard to the functionality of the produced laminated core 12.

[0072] In the described embodiments, the laminations 10 are illustrated as rings only in an exemplary fashion. The laminations can, of course, also have any other suitable shape. In the described way, individual teeth can thus be stacked to the individual tooth cores wherein the individual tooth cores subsequently are joined to a stator core or rotor core. Such laminated cores are used, for example, for rotors and/or stators of electric motors.

[0073] However, the laminations can also be provided in an exemplary fashion with an

[0074] E shape or comb shape or can have other shapes.

[0075] In the described embodiments, the different connecting types of the laminations 10 among each other can be produced simultaneously but also temporally in sequence. Also, these different connecting types can be provided at the same or at different locations in the laminated core 12. For hybrid connections that comprise an adhesive connection as well as a force-locked connection, the friction/form-fit connections 9, 15 provide already a good handling of the laminated core when the adhesive is not yet completely cured. The minimal tensile strength of the force-locked connection 9, 15 is compensated by the higher tensile strength of the adhesive connection. Conversely, the reduced impact resistance and peel resistance of the adhesive connection is compensated by the form-fit/force-locking action between the embossments 9 and the depressions 15 of neighboring laminations 9. In case of hybrid connections that comprise two material fusion connections, the respective adhesive system properties can be combined so that a very fast and permanent connection between the laminations is produced. In the hybrid connection that comprises two material connections of welding and adhesive action, the respective properties can be combined also so that a fast and permanent connection between the laminations is generated.