METHOD FOR PRODUCING A LAMINATION STACK, LAMINATION STACK AND ELECTRIC MACHINE

Abstract

The invention relates to a method for producing a lamination stack, e.g. a stator package or a rotor package. The method comprises the following steps: A) providing a metal sheet (1) with an adhesive coating; B) transporting the metal sheet in an in-line system comprising a cutting means (4), a separating means (6) and an activation means (5, 5a 5b); C) cutting a molded part (2) with the cutting means (4); D) activating the adhesive coating; E) separating the molded part (2); F) placing the molded part (2); G) repeating steps C) to F), wherein the adhesive coating of some molded parts (8) is provided with a treatment fluid by means of a treatment device (9) in order to allow for target breaking points for separating a molded part stack (3, 3′). In some cases a subsequent compaction can be carried out by a compaction station (7). The invention also relates to a lamination stack and an electric machine.

Claims

1. A method for producing a lamination stack for an electric machine, comprising the following steps: A) providing a metal sheet provided with an at least partially curable polymer-based adhesive coating or a plurality of metal sheets provided with an at least partially curable polymer-based adhesive coating, B) transporting the metal sheet into an inline system comprising: at least one cutting means, a separating means and an activating means for activating the adhesive coating, C) cutting a molded part from the metal sheet provided in step A using the at least one cutting means, D) activating the adhesive coating of the molded part using the activating means for activating the adhesive coating of the molded part, E) separating the molded part from the metal sheet using the separating means, F) placing the molded part in a positioning area for forming a molded part stack, G) repeating steps C) to F) to continuously fill the positioning area with molded parts, wherein after a predefined number of molded parts has been reached, with regard to the next molded part, before carrying out step F) said next molded part is provided at least in areas with a treatment fluid using a treatment device to reduce the effect of the adhesive coating on this subsequent molded part such that the adhesive coating of this subsequent molded part, in the positioning area as a result of the reduced adhesive coating, causes improved separability of a stack section below the adhesive coating of reduced effect from a stack section above the adhesive coating of reduced effect.

2. The method according to claim 1, wherein the activating means comprises a first infrared illuminant and the adhesive coating is illuminated with infrared radiation and thereby activated.

3. The method of claim 2, wherein the activating means comprises a second infrared illuminant, the first infrared illuminant and the second infrared illuminant emitting infrared radiation of different wavelengths to activate the adhesive coating at different activation depths.

4. The method of claim 3, wherein the first infrared illuminant has a wavelength between 780 nm and 1200 nm emits and the second infrared illuminant has a wavelength between 1200 nm and 3000 nm.

5. The method according to claim 1, wherein the activating means comprises an induction heater.

6. The method according to claim 1, wherein the treatment fluid is a separating fluid and the treatment device is a coating unit with which the separating fluid is applied to the adhesive coating as a treatment of the adhesive coating, or the treatment fluid is a cooling fluid and the treatment device is a wetting unit with which the cooling fluid is applied to the adhesive coating as a treatment of the adhesive coating.

7. The method according to claim 1, wherein the treatment fluid is a separating liquid in the form of stamping oil.

8. The method according to claim 1, wherein after a stack section has been separated, the stack section is post-compacted in a press with a pressure on the end face.

9. The method according to claim 1, wherein the adhesive coating is applied to the metal sheet as an aqueous dispersion and/or the adhesive coating has a complex viscosity that is at least 8 Pa x s immediately prior to the onset of chemical crosslinking.

10. The method according to claim 1, wherein the adhesive coating contains: 60 parts by weight of an epoxy resin in solid resin form, 0.5-5 parts by weight of a latent curing agent, 1-5 parts by weight of a latent accelerator.

11. The method according to claim 1, wherein the metal sheet provided in step A) is provided with the adhesive coating on both sides.

12. The method according to claim 1, wherein the latent accelerator contains a urea derivative.

13. The method of claim 12, wherein the urea derivative a substance ##STR00003## containing R: hydrogen or a group according to ##STR00004## where n=0 or 1, X=0 or S, R1, R2 and R3 are each hydrogen, a halogen, nitro group, a substituted or unsubstituted alkyl group, alkoxyl group, aryl group or aryloxyl group, R4 is an alkyl group, alkenyl group, cycloalkyl group, cycloalkenyl group, aralkyl group optionally substituted by a halogen, hydroxyl or cyano, methyl, ethyl, propyl, butyl, R5 is the same as R4 or is an alkoxyl group, R5 optionally forming a heterocyclic ring with R4, or is an N,N-dimethyl-N′-(3,4-dichlorophenyl)urea or an N,N-dimethyl-N′-(3-chloro-4-methylphenyl)urea or an N,N-dimethyl-N′-(3-chloro-4-methoxyphenyl)urea or an N,N-dimethyl-N′(3-chloro-4-ethylphenyl)urea or an N,N-dimethyl-N′-(4-methyl-3-nitrophenyl)urea or an N-(N′-3,4-dichlorophenylcarbamoyl)morpholine or an N,N-dimethyl-N′(3-chloro-4-methylphenyl)thio-urea.

14. The method according to claim 1, wherein steps C) to F) are carried out with a rise rate of at least 80/min.

15. The method according to claim 1, wherein stack sections which are separated from one another due to an adhesive coating of reduced effect, or which are provided with target breaking points, are removed separately from the molded part stack formed by filling the positioning area with molded parts.

16. A lamination stack for an electric machine, produced as a stacked section, using a method according to claim 15, in particular designed as a stator or as a rotor.

17. An electric machine, in particular electric motor, having a stator and/or a rotor according to claim 16.

18. The electric machine according to claim 17, comprising a stator and a rotor, wherein the stator is partly or completely the lamination stack and the rotor is partly or completely a component manufactured by means of punch-stacking.

19. The method according to claim 1, wherein the lamination stack is either a stator core or a rotor package.

20. The method according to claim 1, wherein the activating means is disposed between the at least one cutting means and the separating means for activating the adhesive coating.

21. The method according to claim 1, wherein the molded part is designed as a stator lamella or as a rotor lamella.

22. The method according to claim 12 wherein the urea derivative is or inlcudes 4,4′-methylene-bis-(phenyldimethylurea).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0160] FIG. 1 is a schematic view of a lamination stack for an electric motor according to one embodiment of the subject disclosure.

[0161] FIGS. 2A and 2B show the results of tests for various samples (Samples 0, 1, 2 and 3), particularly showing storage time versus shear value.

[0162] FIG. 3 shows a sample according to the subject disclosure against a sample with a conventional baking coating, particularly showing a significantly higher complex viscosity for the sample according to the subject disclosure.

DETAILED DESCRIPTION

[0163] It goes without saying that the features mentioned above and below can be used not only in the combination indicated but also in other combinations or in isolation.

EXAMPLES

[0164] An example of a first embodiment of the method for producing a lamination stack for an electric motor is shown in FIG. 1. A metal sheet already coated with an adhesive is provided, namely as a non-grain-oriented electrical steel strip 1, coated with an adhesive of the type provided according to embodiments described herein. This strip is transported into an inline system. In a first station, a number of punches 4 cut out molded parts 2 which are designed as rotor lamella or stator lamella. In a subsequent station, the molded part is irradiated using a means designed as an NIR emitter for outputting infrared radiation 5, and the resulting heating activates the adhesive coating of the molded part. The activation means 5 has a first infrared illuminant 5a and a second infrared illuminant 5b. The illuminant 5a emits radiation at wavelengths of 780 nm and 1200 nm, while the second illuminant emits radiation at wavelengths of 1200 nm and 3000 nm. By irradiating at different wavelengths, a more uniform activation of the adhesive coating is achieved in the direction perpendicular to the sheet surface, with the higher efficiency also allowing a higher rise rate, since a shorter period of time is required to activate the adhesive coating.

[0165] Certain lamellae are coated using the treatment device 9 designed as a coating roller, in order to function as a target breaking point between individual lamination stacks in the subsequent molded parts stack. Whenever a specified number of molded parts has been reached, the coating roller 9 moves to the metal sheet, in the representation shown into the plane of the paper, and coats the next molded part after the specified number reached in order to reduce or completely eliminate the effect of the adhesive coating. The coated molded part then has a target breaking point at which the molded parts stack can be separated into stack sections, preferably in a continuously running process, and each of the stack sections represents the finished lamination stack. In the manufacture of the molded parts stack, the lamella 8 was a lamella that corresponded to a predefined number of molded parts that had been reached. For this reason, it was coated with a punching oil using the coating roller 9 adapted as a treating device, and thereby it has a reduced adhesive strength.

[0166] The molded part is then pressed out using the separating means 6 designed as a cutting die and collected and pre-fixed in a positioning area to form a stack 3 in a positioned and/or angularly-aligned manner, i.e. the lamellae provided with an activated adhesive coating adhere to one another simply because of their own weight.

[0167] In the state of removal, the lamination stack is the stack section of the molded parts stack that has been removed at the target breaking point 8 and has a reduced-effective adhesive coating on lamina 8. The stack sections can either be removed by their own weight or separated from the molded parts stack by means of equipment or manual support. In the present example, there are two separate stack sections which are post-compacted in a subsequent step as stack section 3′ in compaction station 7.

[0168] Finally, in a compaction station, compaction with a compaction ram 7 takes place until the adhesive has cured and the finished lamination stack can be removed.

[0169] Examples of a metal sheet according to the subject disclosure and its advantageous behavior for the method according to the subject disclosure are given in tests that were carried out.

[0170] The following samples were produced:

[0171] Sheets made from electrical steel strip M800-50A (according to EN 10027-1) with the material code 1.0816 (according to EN 10027-2), thickness 0.5 mm, length×width: 200×150 mm.

[0172] Samples 0, 1, 2 and 3 were prepared. Samples 0, 1 and 2 are comparative samples, they are coated with an adhesive.

[0173] Sample 3 is an advantageous sample.

[0174] The samples prepared are sheets of the type mentioned above which have been coated with adhesive using an application roller according to the following parameters:

TABLE-US-00001 Parts by weight of epoxide resin Parts by Parts by Sample (present as weight of weight of name solid resin) curing agent accelerator Selected accelerator Sample 60 3.5 4.5 Conventional 0 accelerator (DYHARD URAcc57, brand name) Sample 60 3.5 3.0 Conventional 1 accelerator (DYHARD URAcc13, brand name) Sample 60 3.5 3.0 Conventional 2 accelerator (DYHARD URAcc13, brand name) Sample 60 3.5 3.0 4,4′-methylene-bis- 3 (phenyldimethylurea)

[0175] Layer thicknesses

[0176] Sample 0: 1st surface: 6 μm, 2nd surface 0 μm,

[0177] Sample 1: 1st surface: 6 μm, 2nd surface 0 μm,

[0178] Sample 2: 1st surface: 4 μm, 2nd surface 2 μm,

[0179] Sample 3: 1st surface: 4 μm, 2nd surface 2 μm.

[0180] A plurality of specimens of each of the sample types was prepared. To test the long-term stability, 18 sandwich structures each were made of two identical samples.

[0181] Two samples of the same type were bonded using a plate press with a plate area of 200 mm×200 mm with a surface pressure of 3 N/mm.sup.2, the adhesive being activated in an oven by heating to 120° C. and holding at 120° C. for 30 minutes. Then 8 samples were placed in an oven and stored there at 40° C. A sample was taken every week and a shear value test was performed (based on DIN EN 1465). In addition, a shear value test was performed every week on specimens stored at room temperature. The results of the test are shown in FIGS. 2a and 2b.

[0182] It can be seen from the results that, at room temperature, the composition used according to the subject disclosure has better shear values than the reference samples sample 0, sample 1 and sample 2. Sample 0 tested after six weeks had a significantly reduced shear value; after 8 weeks, sample 0 had a shear value of 0.

[0183] Storage at 40 degrees Celsius results in a shear value of 0 for the reference sample 0 after one week at the latest, i.e. the sample has no storage stability at 40 degrees Celsius. After 2 weeks, sample 1 and sample 2 had an almost unchanged good shear value of over 7.0 N/mm.sup.2, but began to degrade noticeably after three weeks of storage.

[0184] In all cases, the shear value of sample 2 with a surface coated on both sides is higher than the shear value of sample 1 with a surface coated on one side. This is proof of the particularly advantageous effects associated with metal sheet coated on both sides.

[0185] In particular, it can be seen that sample 3 has the best storage stability with an almost unchanged good shear value after 4 weeks at 40 degrees Celsius storage. The only sample that could be obtained was a sandwiched sheet which, even after four weeks of storage at 40 degrees Celsius, still had an unchanged good shear value. At the time of submission of the application, the tests were still ongoing.

[0186] In addition, tests were carried out on the finished sandwiches, they were heated to test temperatures and then, after briefly holding them under heat, also subjected to a shear value test.

TABLE-US-00002 Shear values Sample number [N/mm.sup.2] mean Sample 2 Sample 3 value from 3-fold Standard Standard test in each case [N/mm.sup.2] dev. [N/mm.sup.2] dev. RT 5.55 0.88 6.01 0.26 50 degrees 5.08 1.32 5.85 0.11 Celsius 100 degrees 5.38 0.27 5.59 0.12 Celsius 150 degrees 4.89 0.42 5.22 0.08 Celsius 200 degrees 4.66 0.46 4.96 0.04 Celsius

[0187] The results show that both sample 2 and sample 3 can withstand high temperatures of up to 200° C. over a certain period of time without losing their mechanical stability. In particular, it can be seen that the shear values of sample 3 are significantly higher than those of comparison sample 2.

[0188] Sample 0 was subjected to the temperature test as a reference, it was shown that a shear value of about 0.90 NI/mm.sup.2 was obtained after heating to 150° C. On the basis of sample 3, it was thus found that the metal sheets according to the subject disclosure are suitable for the production of more temperature-stable lamination stacks compared to metal sheets that are already known.

[0189] In FIG. 3 it can be seen from tests that have been carried out that the advantageous adhesive, which has the same composition as that used in sample 3, has significantly higher complex viscosities than commercially available baking coatings, even at temperatures in the region of 100 degrees Celsius. In particular, the complex viscosity immediately before the cross-linking reaction, at a value of 10.74 Pa×s, is significantly higher than the values achieved with a conventional baking coating. This favors the fact that metal sheets provided with such an adhesive coating can be used advantageously for a method according to the subject disclosure and in particular also for its development, which provides for post-compacting, since the adhesive does not liquefy, but at most a transition into a paste-like behavior takes place. As a result, no appreciable flow of adhesive from the lamination stack can be observed, along with the corresponding advantages, in particular for good adhesion, which can be verified with top-pull tests, for example.

[0190] Other tests, not shown, showed in long-term tests lasting 70 days that sample 3 was qualitatively equivalent to each of samples 0 to 2 in terms of its oil resistance, i.e. in shear value tests there was no reduction in adhesion of the lamellae to each other after 70 days of storage in an oil at 150 degrees Celsius.

[0191] It will be appreciated that various implementations of the above-disclosed and other features and functions, or alternatives or varieties thereof, may be desirably combined into many other different systems or applications. Also that various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.