Leveling device for a press for simultaneously compressing several stacks of laminated sheets for a rotor of an electric machine

Abstract

Leveling device (1) for a press for simultaneously compressing several stacks (2, 3) of sheet metal packages (4, 5) for an electric machine, wherein the stacks (2, 3) are hydraulically supported on hydraulically communicating cylinder-piston units (6, 7) such that by applying a pressing force to one of the stacks (2, 3) it can be hydraulically balanced by a movement of the pistons (9, 10) and a height difference between the stacks (2, 3) can be leveled and the stacks (2, 3) can be compressed with the same pressing force, wherein the cylinder-piston units (6, 7) have annular pistons (9, 10) which are guided in annular cylinders (11, 12) and define annular pressure chambers (13, 14) in these cylinders, wherein the latter can be pressurized with hydraulic fluid and are connected to each other via a hydraulic connection (8). communicate.

Description

[0001] The invention relates to a leveling device for a press for simultaneously compressing several stacks of laminated cores for an electric machine. The invention further relates to a press with such a leveling device. The invention also relates to a method for simultaneously producing several stacks of laminated cores for an electric machine using such a press.

[0002] WO 2021 / 115 520 A1 discloses a injection mold for manufacturing a rotor with several axially stacked modules, each with a magnet carrier and a plurality of magnets attached thereto. The injection mold has at least two injection plates prepared for feeding plastic to achieve plastic injection molding of the magnets.

[0003] DE 10 2020 204 002 A1 describes a pressing device with spring-mounted compensating plates that compensate for height differences in a stack of sheets during pressing. A pressure-distributing and thermally conductive intermediate layer ensures that the pressing pressure is evenly distributed across the entire lamination group.

[0004] DE 10 2021 111 612 A1 discloses a joining tool for pressing laminated cores onto a shaft. A contact ring with an elastic element compensates for runout deviations of the laminated core, ensuring that the axial joining force acts uniformly around the circumference and that the core is pressed on without tilting.

[0005] DE 699 12 143 T2 discloses a stamping stacking process for producing long stacks of sheet metal. Individual sheets are stamped sequentially, immediately stacked on top of each other in the press, and joined by means of positive-locking interlocking elements. Techniques such as twisting lamellae within the stack serve to compensate for tolerances in order to obtain a precise, flat stack of sheet metal with a consistent thickness.

[0006] WO 94 / 05 487 A1 describes a leveling device for presses with multiple workpieces. The lower plate is divided into separate support plates mounted on movable cylinder units. These plates are hydraulically connected and automatically compensate for height differences between several stacks of workpieces being pressed simultaneously – each plate receives the same force thanks to a common hydraulic pressure, thus ensuring that all stacks are compressed with identical pressure.

[0007] CN 2 09 937 811 U shows a hydraulic active leveling system for the press beam of large forging presses. The upper beam is held by several main and return cylinders. Sensors detect misalignments; a proportional valve system controls the cylinder pressures so that the beam remains parallel despite eccentric loading. Different stack heights under the beam are thus leveled, and all areas are subjected to the same pressing force.

[0008] The invention is therefore based on the objective of proposing a leveling device, a pressing device and a method of the aforementioned type, which enable the simultaneous production of several stacks of laminated cores for a rotor of an electric machine in a structurally simple and space-reducing manner.

[0009] The problem is solved by the features of claim 1 and alternatively by the features of claim 8 or 9. Further advantageous and claimed embodiments are described in the respective dependent claims, the description, and the drawings.

[0010] Accordingly, a leveling device for a press for the simultaneous compression of several stacks of laminated cores for the rotor of an electric machine is proposed. The stacks are hydraulically supported on hydraulically communicating cylinder-piston units, so that by applying a pressing force to one of the stacks, this force can be hydraulically balanced by moving the pistons, thus leveling any height difference between the stacks and allowing both stacks to be compressed with the same pressing force.

[0011] In a structurally simple and cost-effective manner, differences in stack height caused by component tolerances during stacking of the laminated cores can be compensated for. Consequently, a single press can simultaneously compress multiple stacks of laminated cores for an electric machine rotor, each with the same pressing force.

[0012] Furthermore, the press device ensures a reliable seal for the simultaneous injection of plastic into the stacks, specifically for attaching magnets to the sheet metal bundles. This reliably prevents over-molding and plastic leakage.

[0013] In a particularly advantageous manner, the stacks can each be stored on a piston movable in the stacking direction of the hydraulically communicating hydraulic cylinder-piston units and can be moved in the stacking direction with the respective piston to level a height difference between the stacks.

[0014] According to the invention, the cylinder-piston units have annular pistons guided in annular cylinders, which define annular pressure chambers within these cylinders. These pressure chambers can be pressurized with hydraulic fluid and communicate with each other via a hydraulic connection. The annular design allows for a uniform pressure distribution within the cylinders and on the pistons. Furthermore, easy adaptation to the installation conditions is possible; in particular, additional components can be arranged in the installation spaces radially enclosed by the cylinder-piston units. Consequently, a very compact arrangement is also possible.

[0015] A particularly simple embodiment of the invention can be achieved if preferably the annular cylinders each have a U-shaped cross-sectional profile, wherein the U-legs and the U-base connecting them define an annular pressure chamber and this is limited at the open U-side by the respective engaging annular piston.

[0016] It is further advantageous if the annular cylinders preferably enclose a central free space radially. This allows for centrally located free space within the cylinder-piston units for the arrangement of additional components. Consequently, a very compact arrangement can be achieved.

[0017] Preferably, at least one component of a clamping device for central alignment and centering of the sheet metal packages of the respective stacks is arranged in the free space.

[0018] A further embodiment of the invention provides for a crossbeam spanning the diameter of each annular piston in the force flow between the stacks and the respective piston. This crossbeam is designed to receive and evenly distribute the forces introduced by each stack to the respective piston. In this way, a uniform force transmission from the stacks to the pistons via the crossbeams is achieved, regardless of the stack dimensions.

[0019] Preferably, the crossbeams with an annular bearing surface rest on the annular support surface of the respective piston. Preferably, the bearing surface completely covers the support surface of the respective piston.

[0020] It is also advantageous if the crossbeams preferably have a concave curvature on the inner surface facing the respective piston. This allows for greater stability and strength of the crossbeams when supporting the loads introduced from the stacks. Furthermore, this creates free installation space for arranging additional components, in particular a clamping device for aligning and centering the sheet metal stacks during their compression. A further optimized design with regard to stability, strength, and installation space can be achieved if the curvature preferably extends from the radially inner edge of the bearing surface of the respective crossbeam.

[0021] The problem according to the invention is also solved by a pressing device for simultaneously compressing several stacks of sheet metal packages for an electric machine, with a leveling device described above. This results in the advantages already described above.

[0022] Preferably, the pressing device includes pressure means for simultaneously compressing several stacks of sheet metal packages. Preferably, a pressure plate is provided as the pressure means. The pressure plate preferably has several injection openings for filling the stacks with plastic to fix several magnets within the sheet metal packages.

[0023] The problem according to the invention is further solved by a method for the simultaneous production of several stacks of sheet metal packages for an electric machine using a previously described pressing device. This achieves the advantages already mentioned above.

[0024] In a particularly advantageous way, the stacks are compressed simultaneously with the same pressing force in the pressing device and simultaneously filled with plastic for fastening magnets in the sheet metal stacks.

[0025] Further claimed features of the invention will become apparent from the following description and from the drawings, which further explain the present invention. The drawings show: Fig. 1 a perspective view of a leveling device according to the invention for a press for simultaneously compressing two stacks of sheet metal packages for an electric machine, Fig. 2 a cutaway view of a press device according to the invention for simultaneously compressing two stacks of sheet metal packages for an electric machine with the leveling device.

[0026] The figures show, by way of example, various views of a leveling device 1 and a pressing device according to the invention for simultaneously compressing preferably two stacks 2, 3 or sheet metal bundles 4, 5 for an electric machine. The method according to the invention is also illustrated by these figures.

[0027] The stacks 2, 3 and the laminated cores 4, 5 can be used for a rotor or a stator of the electric machine. The laminated cores 4, 5 consist of stacked and interconnected laminations, each with a central bore 45, 46.

[0028] The in Fig. 1 and Fig. The leveling device 1 shown in 2 serves to compensate for a height difference between the stacks 2, 3 in a press device for the simultaneous compression of the stacks 2, 3 with the same pressing force, which is caused in particular by component tolerances of the stacked sheet metal packages 4, 5 or sheets.

[0029] The leveling device 1 comprises two hydraulic cylinder-piston units 6, 7, each assigned to a stack 2, 3, which have a Fig. 1 and Fig. The two depicted hydraulic connections communicate hydraulically with each other. Fig. Figure 2 shows the hydraulic connection 8 schematically indicated by dashed lines. The cylinder-piston units 6, 7 thus form a closed hydraulic system. They are arranged directly next to each other to save installation space. Each unit comprises annular pistons 9, 10, which are guided in annular cylinders 11, 12. Pressure chambers 13, 14 are defined as annular spaces within the cylinders 11, 12 by the pistons 9, 10 and the cylinders 11, 12.

[0030] Cylinders 11 and 12 each have a U-shaped cross-sectional profile ( Fig. 1 and Fig. 2), wherein the U-shaped legs 15, 16, 17, 18 radially define the respective pressure chamber 13, 14 at the cylinder base, and the U-shaped base 19, 20 connecting them. At the open U-shaped side of the respective cylinder 11, 12, the respective pressure chamber 13, 14 is closed off by the respective movable, engaging annular piston 9, 10.

[0031] The cylinders 11, 12 are each constructed in two parts, with a U-shaped base section 15, 16, 17, 18, 19, 20 and an annular cover 47, 48. The base section comprises the U-shaped legs 15, 16, 17, 18, which each form the radial cylinder side walls, and the connecting U-shaped base 19, 20, which each forms the respective cylinder base.

[0032] The annular covers 47, 48 each rest on the open side of the respective cylinder 11, 12 on the end face of the free end of the respective radially outer cylinder side wall 15, 17 ( Fig. 1 and Fig. 2) and are each attached to it via screws 49.

[0033] The pistons 9, 10 each protrude with their free ends from the open ends of the cylinders 11, 12. At their protruding ends, they are radially recessed on the outer diameter. The covers 47, 48 each project slightly radially inward beyond the radially outer cylinder sidewall 15, 17 and engage in the recessed area of ​​the respective piston 9, 10. In this way, the covers 47, 48 also form a stop for the respective piston 9, 10 at the open end of the cylinder 11, 12.

[0034] To prevent the pistons 9, 10 from rotating, a locking element 59, in particular a pin, is provided which engages radially in a circumferential manner on radially opposite projections 60, 61 on the respective cover 47, 48 and on the respective piston 9, 10.

[0035] A radial hydraulic connection 21, 22 is provided on each of the radially outer cylinder side walls 15, 17 of cylinders 11, 12, to which the hydraulic connection 8 for supplying hydraulic fluid to the respective pressure chamber 13, 14 is connected. The hydraulic connection 8 is screwed to the respective hydraulic connection 21, 22 of cylinders 11, 12 ( Fig. 1) For filling both cylinders 11, 12 with hydraulic fluid, the hydraulic fluid connection 8 has a filling port 50 with shut-off valve.

[0036] The pistons 9, 10 each protrude with free ends from the respective cylinders 11, 12 and form flat annular support surfaces 23, 24 there to support a stack 2, 3 of sheet metal packages 4, 5 ( Fig. 1 and Fig. 2) In the force flow between the pistons 9, 10 and the respective stack 2, 3, a crossbeam 25, 26 is provided in each case ( Fig. 1) It serves to absorb and evenly distribute the forces introduced by the respective stacks 2, 3 onto the respective pistons 9, 10.

[0037] The crossbeams 25, 26 each span the diameter of the pistons (9, 10) and cover the respective central free space 52, 53 enclosed radially inside by the cylinders 11, 12. They each rest with an annular bearing surface 27, 28 on the respective annular support surface 23, 24 of the respective piston 9, 10 and completely cover it. In this way, complete surface contact is achieved. On the side facing away from the pistons 9, 10, the crossbeams 25, 26 each form a flat support surface 29, 30 for supporting the stacks 2, 3.

[0038] Accordingly, the stacks 2, 3 are each supported on the pistons 9, 10 via the crossbeams 25, 26 and are floatingly mounted via these through the cylinder-piston units 6, 7.

[0039] The crossbeams 25, 26 each have a concave curvature 51 extending from the radially inner edge 62, 63 of the respective support surface 29, 30 on the inner surface facing the respective piston 9, 10. This provides the crossbeams 25, 26 with greater stability and strength when supporting the loads introduced from the stacks 2, 3. Furthermore, the curvature 51 creates additional free space for arranging further components adjacent to the spaces 52, 53.

[0040] The leveling device 1 is as described in Fig. 2 is shown in a press device which has a pressure means 31 for simultaneously compressing the two stacks 2, 3 sheet metal packages 4, 5. The pressure means 31 is a pressure plate with a flat contact surface 32 for simultaneous contact with both stack ends 33, 34 and for simultaneously pressing them together.

[0041] Fig. Figure 2 shows the pressing device with the stacks 2, 3, which are each arranged in the force flow between the pressing means 31 and the pistons 9, 10 of the communicating hydraulic cylinder-piston units 6, 7 of the leveling device 1, which are movable in the stack direction. The movement of the pistons 9, 10 is indicated by double arrows.

[0042] Stacks 2 and 3 are shown here as examples, each supported on the respective traverse 25 and 26 by a thermal insulation plate 35 and 36 and a transport plate 37 and 38, respectively, and via these supports rest on the pistons 9 and 10, allowing movement in the stacking direction. The movement of the pistons 9 and 10 and of the stacks 2 and 3 in the stacking direction is indicated by double arrows. The thermal insulation plates 35 and 36 serve to insulate the stacks 2 and 3, which are heated during the manufacturing process. The transport plates 37 and 38 allow the stacks 2 and 3 to be easily transported and arranged between different production stations during manufacturing.

[0043] To simultaneously compress two stacks 2, 3 sheet metal packages 4, 5 with different stack heights for an electric machine, the press device is activated ( Fig. 2) As a result, the pressure means 31 with the pressure plate move vertically downwards in the plane of the image with a predetermined pressing force towards the stacks 2, 3 until the pressure surface 32 rests on the stack end 33, 34 of the stack 2, 3 with the greater stack height H. The greater stack height H is, as already explained above, due to a slight height difference, in particular due to component tolerances of the stacked sheets or sheet stacks. Fig. 2. This is exemplified by stack 2 in the image plane on the left, i.e., stack 3 in the image plane on the right has a smaller stack height.

[0044] The pressing force is transmitted via the stack 2, which has the greater stack height H, and the traverse 23 to the piston 9 of the first cylinder-piston unit 6, and the larger stack 2 moves vertically downwards in the plane of the image with the piston 9, as indicated by arrows ( Fig. 1 and Fig. 2) This causes the hydraulic fluid present in the pressure chamber 13 of the cylinder 11 of the first cylinder-piston unit 6 to be forced from the cylinder 11 via the hydraulic fluid connection 8 into the cylinder 12 of the second cylinder-piston unit 7, as indicated by arrows ( Fig. 1).

[0045] Accordingly, the pressure chamber 14 of the second cylinder-piston unit 7 is pressurized with hydraulic fluid and the piston 10 and the stack 3, which has a smaller stack height and is supported by the traverse 26, are moved vertically upwards in the plane of the image, as indicated by arrows ( Fig. 1 and Fig. 2), until the stack end 32 rests against the pressure surface 32 of the pressure plate 31 and the height difference between the stacks 2, 3 is equalized.

[0046] Conversely, if the second stack 3 in the image plane has a greater stack height H to the right than the first stack 2, the compensation of the stack height difference proceeds analogously in the opposite direction.

[0047] In this way, the leveling device 1 allows the pressing force between the stacks 2, 3 to be hydraulically tared via the hydraulically communicating cylinder-piston units 6, 7, similar to a scale, and any difference in stack height between the stacks 2, 3 can be hydraulically leveled by the movement of the pistons 9, 10. Consequently, in the pressing device, both stacks 2, 3, which are horizontally at the same height against the contact surface 32 of the pressure plate 31, can be compressed with the same pressing force.

[0048] Under high pressure, approximately 50 tons, both stacks 2, 3 are compressed simultaneously with the same pressure. This results in a high seal between the pressure medium or pressure plate 31 and the respective stack ends 33, 34 of the two stacks 2, 3. This enables uniform injection of plastic through injection ports 39 on the pressure plate 29 under high pressure simultaneously into both stacks 2, 3. Fig. 2).

[0049] The plastic injection serves to fix magnets arranged in provided cavities in the sheet metal stacks 4, 5 of the stacks 2, 3.

[0050] Distribution channels (not shown) are provided for distributing the injected plastic in the stacks 2, 3. These channels are located at the stack ends 33, 34 and are connected to the injection openings 39 on the pressure plate 31 during compression ( Fig. 2) Carrier plates 43, 44 arranged between the individual sheet metal stacks 4, 5 guide the plastic to the next sheet metal stack 4, 5

[0051] Once the plastic injection is complete, the compression process is stopped. The pressure devices 31 then move up, and the system can level itself again. The stacks 2 and 3 can be removed from the press on the transport plates 37 and 38.

[0052] The annular cylinders 11, 12 each enclose a free space 52, 53 with the radially inner cylinder side wall 16, 18, as a central hole in which components of a clamping device 54 for the central alignment and centering of the sheet metal packages 4, 5 of the respective stacks 2, 3 are arranged ( Fig. 1) The respective free space 52, 53 is increased by the respective concave curvature 51 on the inner surface of the crossbeams 25, 26 resting on the support surfaces 23, 24 of the pistons 9, 10.

[0053] The clamping device 54 comprises a conical mandrel 55 and a collet 56, which includes the mandrel 55 with two collet arms 57, 58 ( Fig. 2) This collet and the collet 56 are arranged in the central bores 45, 46 of the lamination stacks 4, 5 of the stacks 2, 3. Before compression, to clamp the stacks 2, 3, the collet 53 is pulled vertically downwards in the plane of the image by the clamping device 54. This causes the collet arms 57, 58 to widen in a radially outward direction and align the lamination stacks 4, 5 with their central bores 45, 46 coaxially centered. Reference symbol list 1 leveling device 2 stacks 3 stacks 4 sheet metal package 5 sheet metal package 6-cylinder piston unit 7-cylinder piston unit 8 Hydraulic connection 9 pistons 10 pistons 11 cylinders 12 cylinders 13 Printing room 14 Printing room 15 U-shaped legs, radially outer cylinder side wall 16 U-shaped legs, radial inner cylinder side wall 17 U-shaped legs, radially outer cylinder side wall 18 U-shaped legs, radial inner cylinder side wall 19 U-base, cylinder base 20 U-base, cylinder base 21 Hydraulic medium connection cylinder 22 Hydraulic medium connection cylinder 23 Support surface, piston 24 Support surface, piston 25 traverse 26 traverse 27 contact area 28 contact surfaces 29 Support surface traverse 30 Support surface traverse 31 Contact material, contact plate 32 Contact surface 33 Stack end 34 Stack end 35 Thermal insulation board 36 Thermal insulation board 37 Transport plate 38 Transport plate 39 injection ports 40 - 41 - 42 - 43 Carrier plate 44 Carrier plate 45 central bore 46 central bore 47 lids 48 lids 49 screw 50 filling connection 51 Curvature 52 free space 53 Free space 54 Clamping device 55 mandrel 56 Collet 57 Pliers arm 58 Pliers arm 59 locking element 60 bulge 61 Bulge 62 Rand 63 Rand

Claims

Leveling device (1) for a press for simultaneously compressing several stacks (2, 3) of sheet metal packages (4, 5) for an electric machine, wherein the stacks (2, 3) are hydraulically supported on hydraulically communicating cylinder-piston units (6, 7) such that by applying a pressing force to one of the stacks (2, 3) they can be hydraulically balanced by a movement of the pistons (9, 10) and a height difference between the stacks (2, 3) can be leveled and the stacks (2, 3) can be compressed with the same pressing force, wherein the cylinder-piston units (6, 7) have annular pistons (9, 10) which are guided in annular cylinders (11, 12) and define annular pressure chambers (13, 14) in these cylinders, wherein the latter can be pressurized with hydraulic fluid and are connected to each other via a hydraulic connection (8). communicate. Leveling device (1) according to claim 1, characterized in that the stacks (2, 3) can each be mounted on a piston (9, 10) movable in the stacking direction of the hydraulically communicating cylinder-piston units (6, 7) and can be moved with the respective piston (9, 10) in the stacking direction to level a height difference between the stacks (2, 3). Leveling device (1) according to one of the preceding claims, characterized in that the annular cylinders (11, 12) each have a U-shaped cross-sectional profile, wherein the respective U-legs (15, 16, 17, 18) and the U-base (19, 20) connecting them each define the respective pressure chamber (13, 14) and this is limited at the respective open U-side by the respective engaging annular piston (9, 10). Leveling device (1) according to one of the preceding claims, characterized in that the annular cylinders (11, 12) each radially enclose a central free space (52, 53). Leveling device (1) according to claim 4, characterized in that at least one component of a clamping device (54) for central alignment and centering of the sheet metal packages (4, 5) of the respective stacks (2, 3) is arranged in the free space (52, 53). Leveling device (1) according to one of the preceding claims, characterized in that in the force flow between the stacks (2, 3) and the respective annular piston (9, 10) a traverse (25, 26) spanning the diameter of the piston is arranged, which is provided for receiving and uniformly distributing the forces introduced by the respective stacks (2, 3) onto the respective piston (9, 10). Leveling device (1) according to claim 6, characterized in that the crossbeams (25, 26) each have a concave curvature (51) on the inner surface facing the respective piston (9, 10). Pressing device for simultaneously compressing several stacks (2, 3) of sheet metal packages (4, 5) for an electric machine, with a leveling device (1) according to one of the preceding claims. Method for the simultaneous production of several stacks (2, 3) of sheet metal packages (4, 5) for an electric machine, with a press device according to claim 8 .

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