Method for manufacturing a laminated core, and laminated core

Abstract

The invention relates to a method for producing a laminated core (3) and to the laminated core (3), which comprises at least one cooling channel (18) that runs through the layers (3a, 3b, 3c, 3d) of the laminated core (3). The aim of the invention is to provide the laminated core (3) with a cooling channel (18) which is media-tight in order to prevent a leak. This is achieved in that on at least two layers (3a, 3b, 3c, 3d), the respective first or second sheet part (2a, 2b) has at least one bead (9), the at least two layers (3a, 3b, 3c, 3d) engage into one another by means of said beads (9), and the beads (9) run completely around the respective channel recess (16) of the first or second sheet part (2a, 2b) in question, thereby preventing the longitudinal axis (L) from being enclosed.

Description

[0001] Method for producing a laminated core and this laminated core

[0002] Technical area

[0003] The invention relates to a laminated core, in particular for an electrical machine, with a plurality of layers arranged one above the other, wherein the layers each have a single first sheet metal part or a plurality of second sheet metal parts arranged next to one another, with a hot-melt adhesive lacquer layer, for example baking varnish, provided between the layers, in particular a thermo-cured one, which connects the first or second sheet metal parts to one another in a material-to-body ratio and over the entire surface, and with at least one cooling channel which runs through the layers of the laminated core, for which purpose the respective first or second sheet metal parts have at least one channel recess, wherein the cooling channel is arranged eccentrically to a longitudinal axis of the laminated core running through the center of the laminated core.

[0004] State of the art

[0005] A reduced size and increased power density in laminated laminated cores requires cooling with a coolant, for example, using cooling channels through the laminated core – which requires gap-free layers, each containing a single first sheet metal part or several second sheet metal parts arranged side by side. For this purpose, it is known, for example, to bond stacked sheet metal parts together with a hot-melt adhesive layer between the layers. However, due to parameter fluctuations in the stacking process used to produce the laminated core, undesirable impairments to the properties of the hot-melt adhesive layer, or other negative influencing factors, the formation of gaps between the layers cannot be completely ruled out – especially when high fluid pressure is applied to the laminated core. Such laminated cores are therefore often not suitable for use in high-performance applications with intensive cooling requirements.

[0006] Description of the invention

[0007] It is therefore the object of the invention to modify the design of a laminated core of the type described at the outset in such a way that it can be stably subjected to liquid cooling even with high hydraulic pressure and is thus universally applicable.

[0008] The invention solves the problem by the features of claim 1.

[0009] The stability of the laminated core with respect to the penetration of liquid between the layers can be improved if the first or second laminated core in at least two layers has at least one bead, by means of which beads the at least two layers engage with each other. In addition, these beads completely surround the channel recess of the respective first or second laminated core, avoiding any inclusion of the longitudinal axis. By completely surrounding the channel recess, it can be ensured that there are at least no gaps in these areas of the bead when the laminated cores are stacked. In addition, this creates a type of barrier between the layers on the laminated core - which can ensure that even with gap-free laminated cores, these can withstand even higher hydraulic pressures, as is necessary, for example, for internal cooling of a stator and / or rotor laminated core in the high-performance range.Such beads can also be advantageously produced on the laminated core using known methods such as those used in clinching.

[0010] Preferably, each layer of the laminated core comprises a first sheet metal part. When using segmented layers, i.e., layers consisting of several second sheet metal parts arranged side by side, a sealing compound, preferably resin-based, can be applied to the abutting surfaces between the second sheet metal parts arranged side by side, which can, for example, further increase pressure resistance. The laminated core according to the invention is therefore not only robust, even usable at high hydraulic pressures, but can also be manufactured cost-effectively and reproducibly.

[0011] Preferably, the risk of disruption of the edge of the cooling channel due to the sheet metal forming of the bead can be kept low if a bead base of the bead extends at a distance, in particular a radial distance, from the channel recess of at least the sheet metal thickness of the first or second sheet metal part. Preferably, the distance, in particular a radial distance, corresponds to at least 5 times the sheet metal thickness of the first or second sheet metal part.

[0012] To ensure media tightness in the vicinity of the channel recess, the distance, in particular the radial distance, corresponds to a maximum of 20 times the sheet thickness of the first or second sheet metal part. It may already be sufficient if the distance, in particular the radial distance, corresponds to a maximum of 12 times the sheet thickness of the first or second sheet metal part. This can result in a distance, in particular the radial distance, in the range of 1 to 20 times the sheet thickness, 1 to 12 times the sheet thickness, 2 to 10 times the sheet thickness, 5 to 20 times the sheet thickness, or 5 to 12 times the sheet thickness.

[0013] Comparable media-tightness around the channel recess can be achieved if the bead base runs at a substantially constant, particularly radial, distance from the channel recess. This also further improves the cooling channel's resistance to leakage.

[0014] The risk of the bead adversely affecting the contour of the channel recess during manufacturing can be reduced if the sheet metal section between the bead and the channel recess runs in the plane of the sheet. If the channel axis of the cooling channel runs parallel to the longitudinal axis of the laminated core, the complexity of manufacturing the interlocking beads can be reduced, which can lead to a more cost-effective laminated core.

[0015] The above can be further improved if the channel recess is curved and / or if the bead around the channel recess is curved.

[0016] This is especially true, for example, when the bead and the channel recess are concentric.

[0017] Alternatively, the bead could be designed as a round bead, a box bead, or a trapezoidal bead. This can also provide a sufficiently high barrier effect against the penetration of liquids – even at a comparatively high applied hydraulic pressure.

[0018] It is also conceivable for the beads to each have a bead height in the range of greater than or equal to 0.5 times to less than or equal to 2 times, in particular 1 time, the thickness of the sheet metal part. Furthermore, projections designed in this way are relatively easy to provide on the sheet metal part. The sheet metal part can, for example, have a thickness of 0.1 to 1 mm, in particular 0.2 to 0.5 mm.

[0019] Preferably, the sheet thickness of the first or second sheet part is from 0.1 mm to 0.35 mm, preferably from 0.2 mm to 0.3 mm.

[0020] The laminated core according to the invention can be particularly suitable for an electrical machine, for example as a stator or as a rotor.

[0021] The invention also aims to provide a method by which a laminated core with a leak-tight cooling channel can be reproducibly created. The invention achieves this objective by the features of claim 13.

[0022] By repeatedly incorporating at least one bead into the sheet metal or sheet metal strip through sheet metal forming, with these beads completely encircling the channel recess of the respective first or second sheet metal part while avoiding any inclusion of the longitudinal axis, the conditions for a particularly secure barrier against the penetration of liquid between the layers of the laminated core can be created. Furthermore, this process step can be easily provided for in the stacking of laminated cores using comparatively simple forming techniques that are also known from clinching - which also leads to advantages in handling for the process. The process according to the invention therefore makes it possible to create reproducible laminated cores without significant additional effort, which can reliably withstand liquid cooling with comparatively high hydraulic pressures.

[0023] Preferably, the sheet or sheet metal strip is provided with a full-surface, in particular thermosetting, hot-melt adhesive lacquer layer, in particular baking varnish, on both flat sides in order to further improve the media tightness of the cooling channel.

[0024] Short description of the drawing

[0025] The figures show, for example, the subject matter of the invention in more detail using several embodiments.

[0026] Fig. 1 is a schematic view of an apparatus for producing sheet packages from first or second sheet metal parts,

[0027] Fig. 2 is an enlarged partial view of four layers of the laminated core according to Fig. 1 and Fig. 3 is a partial plan view of the laminated core manufactured according to Fig. 1 with layers of first or second sheet metal parts.

[0028] Way of carrying out the invention According to the embodiment of Fig. 1, a device 1 for carrying out the method according to the invention is shown schematically. This device 1 is used for bundling laminated sheet metal packages 3 from laminated sheet metal parts 2a, 2b. For this purpose, a sheet metal strip 5, namely electrical steel strip (or from an electrical steel sheet in the case of a sheet), is unwound from a coil 4, which has on one flat side 7 of its two flat sides 6, 7 a full-surface hot-melt adhesive layer 8, namely self-bonding varnish, in the B-stage - only shown indicated in Fig. 1. It is conceivable that a full-surface hot-curing hot-melt adhesive layer 8, namely self-bonding varnish, is applied to both flat sides 6 and 7 - this, however, has not been shown. The sheet metal strip 5 has a strip thickness of 0.3 mm (millimeters).

[0029] For example, it is mentioned that such a thermally activated and thus heat-curing hot-melt adhesive layer (often also called a hot-melt adhesive layer) is known under the term "baking varnish." For example, the hot-melt adhesive can be based on an epoxy resin. The hot-melt adhesive is preferably a bisphenol-based epoxy resin system with a hardener, for example, a dicyandiamide-based one. In particular, the hot-melt adhesive mentioned can be a bisphenol A-epichlorohydrin resin system with dicyanamide as the hardener. This two-stage curing epoxy resin system is in the B-stage on the sheet or sheet metal strip. This makes the partially cross-linked hot-melt adhesive reactive. By applying heat, the hot-melt adhesive in the B-stage reacts further and can thus be converted to the fully cross-linked C-stage – which is also referred to as caking or final curing.Typically, this partially cross-linked hot melt adhesive layer has a thickness of a few micrometers.

[0030] From the adhesive-coated sheet metal strip 5, several sheet metal parts 2a, 2b are separated, specifically punched, using a punching tool 11—in the exemplary embodiment, a progressive punching tool. Such punching can—generally mentioned—be cutting out, trimming, notching, trimming, dividing by pressing, etc. Laser cutting is also conceivable, although this is not shown. As can be further seen from Fig. 1, the punching tool 11 performs a cutting operation with several strokes 12. For this purpose, the cutting edges 13a, 13b in the upper tool 11a of the punching tool 11 interact with the respective dies 14a, 14b of the lower tool 11b of the punching tool 11, thus forming two punching stages 15a, 15b in the punching tool 11.

[0031] With the first cutting edge 13a of the upper tool 11a, a channel recess 16 is introduced, namely punched, into the sheet metal strip 5 - which can be seen from the punched-out remaining piece 17 in Fig. 1. The channel recess 16 is provided in the sheet metal strip 5 for each individual sheet metal part 2a, 2b in order to enable a cooling channel 18 through the entire sheet metal package 3.

[0032] The cutting edge 13b separates the sheet metal part 2a, 2b from the sheet metal strip 5. This is done by the punching stage 15b, which punches the sheet metal parts 2a, 2b free, pushes them into a stacking device 19 using the pressure of the upper tool 11a, and stacks them there. For this purpose, the stacking device 19 has a guide in the lower tool 11b. A counterholder 10, partially shown in Fig. 1, is also provided in the guide.

[0033] The stacking device 19 is actively heated to thermally activate the baked enamel layer of the sheet metal parts 2a, 2b and to create an adhesive bond, i.e., a material bond, between the sheet metal parts 2a, 2b. In this way, the hot-melt adhesive 8 is baked and converted into the C-state, which laminates the sheet metal parts 2a, 2b into a sheet stack 3.

[0034] The sheet metal parts 2a, 2b are thus bonded together over their entire surface. The adjacent sheet metal parts 2a, 2b are thus held together by a full-surface, material-to-material bond provided between them.

[0035] The cooling channel 18 is arranged eccentrically to a longitudinal axis L of the laminated core 3 running through the center of the laminated core 3, and thus does not run centrally through the laminated core 3. In the exemplary embodiments, the longitudinal axis L is the central longitudinal axis of the laminated core 3, i.e. a longitudinal axis L running through the center of the laminated core 2. In the exemplary embodiment, this longitudinal axis L is also, for example, an axis of symmetry of the laminated core. A receptacle 20 in the laminated core 3 runs centrally through the laminated core, since the laminated core 3 is used as a rotor for an electrical machine 100 and the receptacle 20 serves for a rotor shaft. However, it is also conceivable that the laminated core 3 is used as a stator, and the receptacle 20 is provided to accommodate a rotor (not shown).

[0036] According to the invention, the cooling channel 18 is improved in its media-tightness. This is achieved by introducing beads 9 into the sheet metal strip 5 through sheet metal forming. These beads 9 are created by hollow stamping at the forming stage 21 using a punch 22a and a die 22b. Each sheet metal part 2 of a laminated core 3 thus has a projection and a recess 9a, 9b due to the bead. The separated sheet metal parts 2a, 2b are then stacked to form a laminated core 3 with several layers 3a, 3b, 3c, 3d in such a way that several layers 3a, 3b, 3c, 3d of the laminated core 3 interlock via the beads 9 - as can be seen specifically in Fig. 2 for the first sheet metal parts 2a. Here it can be seen how a bead 9 with a projection 9a on a sheet metal part 2a engages in a complementary recess 9b of a bead 9 on an adjoining sheet metal part 2a.

[0037] These beads 9 are also specially designed - namely, these beads 9 completely surround the channel recess 16 of the respective first or second sheet metal part 2a, 2b, avoiding inclusion of the longitudinal axis L - as can be seen in Fig. 3. The longitudinal axis L running through the center M of the laminated core 3 therefore does not pass through the area spanned by this circumference.

[0038] The complete and—as shown, continuous circulation around the channel axis K—as well as the interlocking of layers 3a, 3b, 3c, 3d create a barrier to fluid penetration. The laminated core 3 can therefore be reliably exposed to liquid cooling—for example, with water—and comparatively high hydraulic pressures. Thus, the laminated core 3 is particularly suitable as a stator or rotor, especially when small dimensions and high electrical power are required from an electrical machine, such as an electric motor and / or generator.

[0039] The circulation also occurs at a sufficient radial distance A between a bead base 9c of the bead 9 and the channel recess 18, as can be seen in Fig. 3. The radial distance A here is 2 mm (millimeters) for a sheet thickness d of 0.3 mm. Thus, this radial distance A is always greater than 5 times the sheet thickness d, but never greater than 12 or 20 times this sheet thickness d – which reliably prevents leakage at the cooling channel 18. However, it is also conceivable that the radial distance A is 0.3 mm, i.e., a sheet thickness d, which has not been shown.

[0040] It can also be seen from Fig. 3 that the bead base 9c of the bead 9 runs at a substantially constant radial distance A from the channel recess 16. The bead 9 and channel recess 16 are elliptically curved and concentric, as shown. Other configurations, such as circular configurations, are conceivable. Furthermore, a varying distance is also conceivable, although this has not been illustrated in detail.

[0041] According to the course of the channel recess 16, the radial distance A is to be considered as a minimum distance A between the edge of the channel recess 16 and the bead base 9c of the bead 9. The minimum distance A thus avoids disturbance of the edge of the cooling channel 16 due to previous processing steps.

[0042] A sheet metal section 24 also runs between the bead 9 and the channel recess 16 in the sheet metal plane E, as shown in Fig. 2, in order to avoid any impairment of the dimensional accuracy of the cooling channel 18 during sheet metal forming.

[0043] According to Figs. 2 and 3, a first sheet metal part 2a is provided in each layer 3a, 3b, 3c, 3d. However, it is also conceivable—as shown in dashed lines in Fig. 3—to provide second sheet metal parts 2b arranged side by side in a layer 3a, 3b, 3c, 3d, namely two second sheet metal parts 2b. The second sheet metal parts 2b abut one another in the layer 3b shown in Fig. 3 at their abutting surface 23, shown in dashed lines. A resin-based sealing compound (not shown) can be provided between the second sheet metal parts 2b at the abutting surface 23.

[0044] According to the invention, different designs of the beads 9, or their projections and recesses 9a, 9b, are possible. According to Fig. 2a, the beads 9 are formed by a round bead. Such a round bead can be characterized (compared to a box bead, trapezoidal bead, etc.) for a more uniform pressure application of the adhesive between the sheet metal parts 2a, 2b during stacking.

[0045] It has been found to be sufficient in the structural design of the beads 9 if the bead height h is substantially equal to the thickness d of the sheet metal part 2. In this case, a sheet metal part 2a, 2b engages at most with an adjoining sheet metal part 2a, 2b - which not only simplifies the sheet metal stack 3, but also facilitates the stacking process.

[0046] Fig. 3 is also schematically defined as part of an electrical machine 100, in which a cooling liquid 25 flows through the cooling channel 18 to cool the laminated core 3. The laminated core 3 according to the invention withstands liquid cooling even under high hydraulic pressure and thus allows high power densities in this electrical machine 100 with small dimensions.

[0047] As can also be seen from Figures 2 and 3, the sheet metal section 24 of the first or second sheet metal part 2a, 2b, which determines the constant section A, runs flat.

[0048] Furthermore, Fig. 2 shows that the channel axis K of the cooling channel 18 runs parallel to the longitudinal axis L of the laminated core 3. Not shown is the embodiment in which the channel recess 16 is circular and / or the bead 9 is annular. In this case, the bead 9 is arranged coaxially with the channel recess 16. However, any configurations are conceivable, which are not shown.

[0049] 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 . Laminated core, in particular for an electrical machine, with a plurality of layers (3a, 3b, 3c, 3d) arranged one above the other, wherein the layers each have a single first sheet metal part (2a) or a plurality of second sheet metal parts (2b) arranged next to one another, with a particularly thermo-cured, hot-melt adhesive lacquer layer (8), for example baking varnish, provided between the layers (3a, 3b, 3c, 3d), which connects the first or second sheet metal parts (2a, 2b) to one another in a material-to-body and full-surface manner, and with at least one cooling channel (18) which runs through the layers (3a, 3b, 3c, 3d) of the laminated core (3), for which purpose the respective first or second sheet metal parts (2a, 2b) have at least one channel recess (16), wherein the cooling channel (18) is arranged eccentrically to a longitudinal axis (L) of the laminated core (3) running through the center of the laminated core (3), characterized in that at least two layers (3a, 3b, 3c, 3d) each comprise the first or second sheet metal part (2a,2b) have at least one bead (9), by means of which beads (9) the at least two layers (3a, 3b, 3c, 3d) engage with each other, and that these beads (9) each completely run around the channel recess (16) of the respective first or second sheet metal part (2a, 2b), avoiding inclusion of the longitudinal axis (L).

2. Laminated core according to claim 1, characterized in that a bead base (9c) of the bead (9) runs at a, in particular radial, distance (A) from the channel recess (16) of at least one, in particular at least 5 times one, sheet thickness (d) of the first or second sheet part (2a, 2b).

3. Laminated core according to claim 2, characterized in that the, in particular radial, distance (A) corresponds to at most 20 times, in particular 12 times, the sheet thickness (d) of the first or second sheet part (2a, 2b).

4. Laminated core according to claim 1, 2 or 3, characterized in that the bead base (9c) of the bead (9) runs at a substantially constant, in particular radial, distance (A) from the channel recess (16).

5. Laminated core according to one of claims 1 to 4, characterized in that the sheet metal section (24) runs between the bead (9) and the channel recess (16) in the sheet metal plane (E).

6. Laminated core according to one of claims 1 to 5, characterized in that the channel axis (K) of the cooling channel (18) runs parallel to the longitudinal axis (L) of the laminated core (3).

7. Laminated core according to one of claims 1 to 6, characterized in that the channel recess (16) and / or the bead (9) is or are curved around the channel recess (16).

8. Laminated core according to one of claims 1 to 7, characterized in that the bead (9) and the channel recess (16) run concentrically.

9. Laminated core according to one of claims 1 to 8, characterized in that the bead (9) is designed as a round bead, box bead or trapezoidal bead.

10. Laminated core according to one of claims 1 to 9, characterized in that the beads (9) each have a bead height (h) in the range of greater than or equal to 0.5 times to less than or equal to 2 times, in particular 1 time, the thickness (d) of the sheet metal part (2a, 2b).

11. Laminated core according to one of claims 1 to 10, characterized in that the sheet thickness (d) of the first and / or the second sheet parts (2a, 2b) is or are from 0.1 mm to 0.35 mm, preferably from 0.2 mm to 0.3 mm.

12. Electrical machine with a laminated core (3) according to one of claims 1 to 11 and with a cooling liquid (25) in the cooling channel (18) of the laminated core (3).

13. A method for producing a laminated core (3) having a cooling channel (18) with improved media tightness, according to one of claims 1 to 11, wherein a sheet or sheet strip (5), in particular electrical sheet or electrical sheet strip, is provided with a full-surface and, in particular thermosetting, hot-melt adhesive lacquer layer (8), in particular baking varnish, on at least one flat side (6, 7) of which flat sides (6, 7) a channel recess (16) is introduced into the sheet or sheet strip (5) several times by a separating process and at least one bead (9) is introduced by sheet metal forming, sheet metal parts (2a, 2b) are separated from the sheet or sheet strip (5), of which a plurality of first or second sheet parts (2a, 2b) each have at least one bead (9) and a channel recess (16), the separated sheet parts (2a, 2b) are combined to form a laminated core (3) with a plurality of layers (3a, 3b, 3c, 3d) are stacked in such a way that several layers (3a, 3b, 3c,3d) of the laminated core (3) by means of the beads (9) of the sheet metal parts (2a, 2b) which engage with one another, wherein the layers (3a, 3b, 3c, 3d) each comprise a single first sheet metal part (2a) or several second sheet metal parts (2b) arranged side by side, wherein these beads (9) completely encircle the channel recess (16) of the respective first or second sheet metal part (2a, 2b) while avoiding inclusion of the longitudinal axis (L), and subsequently the hot-melt adhesive layer (8) is thermally activated in order to bond the sheet metal parts (2a, 2b) together in a material-to-material manner and over their entire surface to form the laminated core, in particular to bond them end-to-end.

14. Method according to claim 13, characterized in that the sheet or sheet metal strip (5) is provided with a full-surface, in particular thermosetting, hot-melt adhesive lacquer layer (8), in particular baking varnish, on both flat sides (6, 7).

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