PACKAGING OF COMPOSITE MATERIAL LABELS BY WELDING

Description

[0001] The invention relates to a method for packaging at least two lamellae made of a composite material by gas-shielded fusion welding, a lamella package produced according to this method, and its use.

[0002] Laminating refers to the joining of individual layers, so-called laminations, into a stack. This creates an ordered stack of laminations arranged on top of each other, which are fixed in a way that prevents them from shifting relative to one another. Such processes are described, for example, in US 2016 / 121421A1 and DE 102012001744A. Laminating is used particularly in the manufacture of electric motors. In the further processing of electrical steel, e.g., into a motor, the individual stator and rotor laminations are laminated into stacks, as described, for example, in DE 102016005329 A1.

[0003] Cutting lamellae and stacking are described in the literature for single-layer (monolithic) electrical steel. Due to the complexity of the processes and their dependence on factors such as thickness, strength, and especially the presence of a polymer, the suitability of the process and the transferability of the parameters to non-monolithic sheet metal are not given.

[0004] Welding composite laminations, which, in addition to an electrically insulating lacquer layer (i.e., insulation), also contain a polymer damping layer with a thickness in the micrometer range between two electrical bands, presents several challenges. This additional organic layer is highly critical for welding such assemblies. Besides outgassing and consequently unsatisfactory welds, complete separation between the laminations can also occur. Furthermore, damage to the damping layer to an extent that negatively affects the properties of the entire lamination assembly, i.e., the motor or generator, must be strictly avoided.

[0005] The object of the present invention was to provide a welding-based packaging process that overcomes the disadvantages of the prior art. In particular, methods for processing composite materials were to be provided. Furthermore, the invention aimed to create the possibility of producing packages using existing equipment and methods in order to avoid costly modifications to the process steps in the manufacturing process and in subsequent applications.

[0006] The problems are solved by the inventive method according to claim 1. The electrical steel strip layer is hereinafter also referred to as electrical steel, electrical sheet, or sheet. The polymer layer is also referred to as polymer layer or polymer layer. The two electrical steel strip layers do not have the same properties, such as thickness, alloy composition, magnetic and mechanical properties. In a special case, both electrical steel strip layers exhibit the same properties.

[0007] Fusion welding is selected from the group of welding processes containing or consisting of: MAG welding, TIG welding, plasma welding and laser beam welding.

[0008] Another embodiment relates to a process in which the fusion welding is a tungsten inert gas welding, preferably TIG welding or laser welding.

[0009] One embodiment of the invention is directed to a method in which the lamellae are packaged to form a lamella pack of an electrical consumer or generator.

[0010] A lamella, as defined in the invention, is a semi-finished product that is produced directly from a separation process without any further processing steps. Such separation processes include, for example, punching or laser cutting.

[0011] The composite material is available as a starting material in the form of coils or circuit boards.

[0012] In another version, the individual slats are stacked on top of each other before packaging.

[0013] The lamella can have a complex outline. This is characterized by a closed polyline representing a continuous sequence of line segments, wherein at least two straight line segments of different lengths are present and optionally at least one curved line segment or combinations thereof. Alternatively, the semi-finished products have an additional feature of a relatively large area, preferably an area greater than 15 cm², 20 cm², 25 cm², particularly preferably greater than 40 cm², 50 cm², in particular 75 cm² or 100 cm², and preferably less than 10,000 cm², particularly preferably less than 1,000 cm², in particular less than 500 cm², 250 cm², 200 cm².

[0014] A composite material to be used according to the invention has the following features: Preferably, the composite material has specific remagnetization losses at P1.0; 50 Hz in the range of 0.7 to 7 W / kg and at P1.5; 50 Hz in the range of 1.9 to 15 W / kg and / or a polarization at J2500 in the range of 1.49 T to 1.7 T and at J5000 in the range of 1.6 T to 1.8 T, determined in accordance with DIN EN 60404-2.

[0015] In a preferred embodiment, the composite material exhibits specific remagnetization losses at P1.0; 50 Hz in the range of 0.8 to 3.5 W / kg and at P1.5; 50 Hz in the range of 2.0 to 8.0 W / kg and / or a polarization at J2500 in the range of 1.49 to 1.71 T and at J5000 in the range of 1.60 to 1.80 T, determined in accordance with DIN EN 60404-2.

[0016] In a particularly preferred embodiment, the composite material exhibits specific remagnetization losses at P1.0; 50 Hz in the range of 1.0 to 1.5 W / kg and at P1.5; 50 Hz in the range of 2.4 to 3.3 W / kg and / or a polarization at J2500 in the range of 1.49 to 1.57 T and at J5000 in the range of 1.60 to 1.65 T, determined in accordance with DIN EN 60404-2.

[0017] Preferably, the composite material exhibits specific remagnetization losses at P1.0; 400 Hz in the range of 8 to 120 W / kg; at P1.5; 400 Hz from 18 to 360 W / kg; and / or a polarization at J2500 in the range of 1.45 T to 1.75 T and at J5000 in the range of 1.45 T to 1.85 T and at J10,000 in the range of 1.50 and 1.95 T determined in accordance with DIN EN 60404-2.

[0018] In a preferred embodiment, the composite material exhibits specific remagnetization losses at P1.0; 400 Hz in the range of 10 to 25 W / kg; at P1.5; 400 Hz from 25 to 49 W / kg; and / or a polarization at J2500 in the range of 1.45 T to 1.75 T and at J5000 in the range of 1.45 T to 1.85 T and at J10,000 in the range of 1.50 and 1.95 T determined in accordance with DIN EN 60404-2.

[0019] Preferably, the composite material has a minimum yield strength in the longitudinal direction at room temperature of 190 to 6510 MPa and a maximum tensile strength of 310 to 7640 MPa and a minimum elongation at break A80 of 6 to 48 % measured according to DIN EN ISO 6892-1 and a hardness Hv5 of 100 - 250.

[0020] In a preferred embodiment, the composite material has a minimum yield strength in the longitudinal direction at room temperature of 310 to 510 MPa and a maximum tensile strength of 400 to 640 MPa and a minimum elongation at break A80 of 7 to 32 % measured according to DIN EN ISO 6892-1 and a hardness Hv5 of 130 - 250.

[0021] The material exhibits anisotropy at P1,0; 400 Hz in the range of 6 to 17%.

[0022] The composite material to be used according to the invention has a comparable iron fill factor (as described below) in the application area of ​​a stator and / or rotor package or generator package.

[0023] Preferably, the iron fill factor in a stator and / or rotor package using the composite material according to the invention is between 85.0% and 99.7%, more preferably 93.0% to 99.0%, even more preferably 98.0% to 99.0% and most preferably 98.3% to 98.8%.

[0024] The use of the composite material not only actively reduces the structure-borne noise generated in the electric motor, but also, for example, by varying the thickness of the electrical steel strip used, generates either a further cost advantage and / or an increased efficiency of the electric motor or generator.

[0025] The composite material prevents and / or dampens the generated vibrations at their source. This prevents their transmission to the housing and adjacent components. The structure-borne noise generated by the electric motor, as well as the airborne noise generated by the housing, is significantly reduced. Consequently, the overall acoustic emissions of the electric motor are reduced.

[0026] The specific remagnetization losses of electrical steel strips depend strongly on the thickness and cross-section of the strips used. As a general rule, the smaller the thickness of the electrical steel strip, the lower the eddy current losses and thus the specific remagnetization losses. Remagnetization losses increase disproportionately, especially at high electrical frequencies. By using the composite sheet according to the invention, two electrical steel strips of the same quality, each 0.25 mm thick, can be bonded together, compared to a monolithic electrical steel strip with a thickness of, for example, 0.5 mm. With regard to a specific motor type, this can either significantly increase the motor's efficiency or enable the construction of a smaller motor with the same efficiency. The latter would result in a weight advantage. Furthermore, the use of a lower-quality electrical steel strip is also possible.

[0027] In practice, both the composite materials themselves and the components manufactured from them sometimes come into contact with various, sometimes highly aggressive, oils that can attack the polymer layer, leading to damage and even delamination. It is therefore desirable that the polymer layer be resistant to such technical oils.

[0028] Alternatively, the polymer layer is a viscoelastic material and contains or consists essentially of a viscoelastic polymer. For the purposes of the invention, the term "essentially" means that at least 50%, 55%, 60%, 65%, 70%, 72%, 74%, 76%, 78%, preferably 80%, 82%, 84%, 86%, 88%, particularly preferably 90%, 91%, 92%, 93%, 94%, 95%, and especially 96%, 97%, 98%, 99%, or 100% (by volume or weight) of a material, such as the viscoelastic material in this case, consists of a specific substance, here a viscoelastic polymer.

[0029] The polymers can be isotropic in one alternative and anisotropic in another, particularly with regard to their elastic properties.

[0030] In one embodiment of the present invention, viscoelastic polymers are used, selected from the group comprising or consisting of: urethane rubbers, fluorine-based elastomers, fluorine-based rubbers, silicone rubbers, nitrile rubbers, butyl rubbers, acrylic rubbers, natural rubbers, styrene-butadiene rubbers, polyesters, polyurethanes, polyamides, ethylene-vinyl acetate copolymers, polyvinyl butyral, polyvinyl butyral-polyvinyl acetate copolymers and epoxy-acrylate networks and combinations thereof; preferably polyesters, polyurethanes, polyamides and combinations thereof.

[0031] In another embodiment, thermoplastic polymers are used, selected from the group consisting of polyacrylates, polycarbonates, polyetherimides, polyesters, polysulfones, polystyrenes, acrylonitrile butadiene styrene block copolymers, polypropylenes, acetal polymers, polyamides, polyvinyl chlorides, polyethylenes, polyurethanes and combinations thereof; preferably containing or consisting of polyesters, polyurethanes, polyamides and combinations thereof.

[0032] Alternatively, the polymers can also be crosslinked to increase their strength. These are typically classified as thermosetting or radiation-curable resins. Such a resin is in a thermoplastic state before the composite material is manufactured. During the manufacturing process, the thermosetting or radiation-curable resin is typically cured to a solid state and / or crosslinked. Depending on the specific resin used, it may contain at least one curing agent, such as a catalyst, which, upon exposure to a suitable energy source (such as heat energy or radiation like IR, UV, X-rays, or electron radiation), initiates the polymerization of the thermosetting resin. Particularly preferred viscoelastic polymers are those based on acrylates.

[0033] According to the invention, mixtures of any of the aforementioned polymers or their starting materials can also be used.

[0034] In one embodiment, a particularly preferred embodiment of the present invention, an acrylate-based copolymer, preferably high-molecular-weight and / or cross-linked, is used as the polymer. In particular, a copolymer is preferably used according to the invention, consisting of a copolymerized mixture of at least one alkyl acrylate ester monomer unit and / or one alkyl methacrylate ester monomer unit, both having an alkyl group with 1 to 12 carbon atoms, a glycidyl monomer unit, an unsaturated carboxylic acid monomer unit, and a cross-linking agent. No swelling of the polymer layer or delamination of the composite material is observed.

[0035] For the purposes of the invention, "acrylate-based" means that the starting material used is essentially an acrylate (with the definition of "essentially" as described above; additionally, in an alternative, the percentages refer to the molar ratio). According to the invention, an acrylate is defined as a starting material selected from the group consisting of or comprising: acrylic acid, methacrylic acid, (meth)acrylic acid esters with an alkyl group having one to twelve carbon atoms, preferably four to twelve; or mixtures thereof.

[0036] In a more preferred embodiment, the cross-linked high molecular weight acrylate-based copolymer consists exclusively of the two components, the copolymerized mixture and the cross-linker.

[0037] In a further preferred embodiment, the copolymerized mixture consists of at least one alkyl acrylate ester monomer unit and / or alkyl methacrylate ester monomer unit, both having an alkyl group with 1 to 12 carbon atoms, a glycidyl monomer unit and an unsaturated carboxylic acid monomer unit.

[0038] Preferably, the glycidyl monomer unit is selected from the group consisting of or comprising allyl glycidyl ether, glycidyl acrylate ester, glycidyl methacrylate ester and / or mixtures thereof.

[0039] Preferably, the alkyl acrylate ester monomer unit and / or alkyl methacrylate ester monomer unit has an alkyl group with 4 to 12 carbon atoms.

[0040] Provided that the polymer layer has a glass transition temperature above -15 °C, an alkyl acrylate ester monomer unit and / or an alkyl methacrylate ester monomer unit with an alkyl group having 1 to 4 carbon atoms can be added to the mixture to be copolymerized, according to a preferred embodiment.

[0041] According to a preferred embodiment, the cross-linked high-molecular-weight acrylate-based copolymer comprises a copolymerized mixture of at least 55 to 85 wt.% of an alkyl acrylate ester monomer unit and / or an alkyl methacrylate ester monomer unit, both having an alkyl group with 4 to 12 carbon atoms, 0 to 35 wt.% of an alkyl acrylate ester monomer unit and / or an alkyl methacrylate ester monomer unit, both having an alkyl group with 1 to 4 carbon atoms, 0.01 to 2 wt.% of a glycidyl monomer unit, 1 to 15 wt.%, more preferably 3 to 13 wt.% of an unsaturated carboxylic acid monomer unit, and 0.05 to 1 wt.% of a cross-linking agent. Preferably, the copolymerized mixture has a mean molar mass in the range of 500 to 1500 kDa, more preferably 600 to 1000 kDa, even more preferably 700 to 900 kDa, and most preferably 800 kDa ± 20 kDa. The mean molar mass is determined by GPC.Polystyrene standard was used for calibration.

[0042] Preferably, the alkyl acrylate ester monomer unit and / or alkyl methacrylate ester monomer unit, comprising an alkyl group with 4 to 12 carbon atoms, is selected from 2-ethylhexyl acrylate, isooctyl acrylate, butyl acrylate, 2-methyl butyl acrylate, 4-methyl-2-pentyl acrylate, isodecyl methacrylate, methyl acrylate, ethyl acrylate, methyl methacrylate and / or a mixture thereof.

[0043] Preferably, the unsaturated carboxylic acid monomer unit is selected from acrylic acid, methacrylic acid, fumaric acid, and / or a mixture thereof. Preferred mixtures consist of acrylic acid and methacrylic acid, acrylic acid and fumaric acid, or methacrylic acid and fumaric acid.

[0044] According to a preferred embodiment, the copolymerization is carried out using a solvent mixture, preferably a mixture of ethyl acetate and acetone. Preferably, the solvent mixture has a ratio that allows reflux in the range of 68 to 78 °C.

[0045] Preferably, the solids content during copolymerization is in the range of 40 to 60 wt.%.

[0046] For copolymerization, AIBN is preferably used as a radical initiator.

[0047] Furthermore, the copolymerization is preferably carried out under a nitrogen atmosphere, so that a high molecular weight copolymer, preferably with an average molar mass of ≥ 500 kDa, is obtained.

[0048] Preferably, the crosslinking agent is selected from aluminium acetylacetonate (AIACA), ferrous acetylacetonate (FeACA), titanium acetylacetonate (TiACA) or zirconium acetylacetonate (ZrACA).

[0049] According to a further preferred embodiment, the electrical tape layer has a thickness of at least 0.05 mm, preferably 0.1 mm, particularly preferably 0.2 mm, 0.25 mm, 0.27 mm, in particular 0.3 mm, 0.32 mm, 0.35 mm, 0.4 mm, or 0.5 mm and a maximum of 1.5 mm, preferably 1 mm, particularly preferably 0.75 mm, in particular 0.65 mm.

[0050] To produce the composite material to be used according to the invention, two electrical tape layers of the same thickness or of different thicknesses can be used.

[0051] Preferably, the electrical steel is a non-grain-oriented electrical steel.

[0052] The invention can be represented on the basis of any non-grain-oriented electrical tape or sheet. Preferably, the non-grain-oriented electrical steel strip or sheet consists of a steel containing, in addition to iron and unavoidable impurities, 0.1 to 3.50 wt.% Si, 0.01 to 1.60 wt.% Al, 0.07 to 0.65 wt.% Mn and up to 0.25 wt.% P, and having a specific electrical resistance of 0.13 to 0.70 µΩm at a temperature of 50 °C; particularly preferably, it consists of a steel containing, in addition to iron and unavoidable impurities, 2.3 to 3.40 wt.% Si, 0.3 to 1.1 wt.% Al, 0.07 to 0.250 wt.% Mn and up to 0.030 wt.% P, and having a specific electrical resistance of 0.40 to 0.70 µΩm at a temperature of 50 °C.

[0053] In another variant, the non-grain-oriented electrical steel strip or sheet consists of a steel which, in addition to iron and unavoidable impurities, contains 1.20 to 2.50 wt.% Si, 0.10 to 0.60 wt.% Al, 0.10 to 0.30 wt.% Mn and up to 0.070 wt.% P, as well as a specific electrical resistance of 0.29 to 0.44 µΩm at a temperature of 50 °C.

[0054] The plastic layer has a thickness of at least 2 µm, preferably at least 3 µm, particularly preferably at least 4 µm, in particular at least 4.5 µm and of a maximum of 50 µm, preferably a maximum of 20 µm, particularly preferably 10 µm, 8 µm, in particular a maximum of 7.5 µm.

[0055] To prevent short circuits between two electrical tapes, the electrical tape layers are provided with an insulating layer to achieve electrical insulation. Preferably, the electrical tape layer has an insulating layer with a thickness of at least 0.5 µm, more preferably at least 1.0 µm, more preferably at least 1.5 µm up to a maximum of 10 µm, more preferably a maximum of 5 µm, more preferably up to 2.5 µm, and more preferably up to 1.5 µm.

[0056] The insulating layer can consist of an organic polymer such as an acrylate, alkyd, epoxy, melamine, phenolic, polyamide, polyester, or polyurethane resin, or a mixture thereof. According to another preferred embodiment, the organic polymer can contain further inorganic components, such as aluminum phosphate, pigments, and / or fillers (such as titanium dioxide, barium sulfate, calcium carbonate (kaolin), silicon dioxide, or zinc sulfide).

[0057] In a particularly preferred embodiment, the insulating layer consists of an adhesive that can be activated thermally, chemically or by radiation.

[0058] In one version, the individual lamellae are punched or separated from a starting material by means of laser cutting before welding.

[0059] An alternative method involves manufacturing the lamellae by laser beam cutting. Laser beam cutting is a process known to those skilled in the art. In this alternative, it is carried out with the following parameters: Device: Trumpf True Coax CO2 laser; laser power 1300 watts; wavelength 9300 nm. Parameter:

[0060] Power: contour-dependent, maximum 100%: 1300W; minimum 20%: 260W; preferably 40-80%; frequency: contour-dependent, maximum 10 kHz, minimum 1 kHz, preferably 2-8 kHz, particularly preferably 3-7 kHz; speed: maximum 25 m / min, minimum 5 m / min, preferably 10 m / min; gas pressure: 10-15 bar, preferably 12 bar; focus position: 0.5 mm to 1.0 mm, preferably 0.55 to 0.75 mm, particularly 0.65 mm; nozzle spacing: 0.5 mm to 1.0 mm, preferably 0.56 to 0.8 mm, particularly 0.7 mm.

[0061] In another version, the individual lamellae are stacked on top of each other before welding.

[0062] The invention relates to a method in which the laminations are electrically contacted with each other prior to MAG welding, TIG welding, plasma welding, preferably TIG welding. In one alternative, a copper strip is used for this purpose. In another alternative, a copper plate is used as an ignition aid.

[0063] Alternatively, contact is made using at least one adhesive tape which has an electrically conductive layer on the side facing the lamellae.

[0064] In another alternative, contact is made via fan-shaped metal rods, which in particular form a fan that continuously connects the individual lamellae analogously to the above and thus enables an electrical connection.

[0065] In another alternative, contact is made via at least one nose element of the lamellar geometry, which allows for optimal degassing and mass flow (heating and lowering of the nose).

[0066] Alternatively, welding is carried out using TIG under the following conditions: Robot system: Motoman HP20D with DK-250 Process: TIG Welding system: EWM Tetrix 350 AC / DC Torch system: Binzel machine torch Torch position: Perpendicular to the workpiece Electrode: Diameter: 1.6 to 3.2 mm, preferably 2.2 to 2.6 mm, particularly 2.4 mm; Spacing: 0.6 to 1 mm, preferably 0.7 to 0.9 mm, particularly 0.8 mm Current: 60–80 A, preferably 70 A Voltage: 9.5 to 11 V, preferably 10.2 V Welding speed: 5–15 cm / min, preferably 8–12 cm / min, particularly 10 cm / min Shielding gas: Argon, with up to 5% hydrogen 4.6 Shielding gas quantity: 8–10 liters / min. Position: PG, vertical position, downward welding.

[0067] Alternatively, welding is carried out using laser welding under the following conditions: Laser: IPG YLS 4000; Robot Reis RV16L; Optics BCO3; Laser power 1-3 kW, preferably 1.5 to 2.52 kW, particularly 2 kW; Welding speed 10 to 50 mm / s, preferably 15-30 mm / s, particularly 25 mm / s.

[0068] The invention also relates to a lamellar package manufactured in a process as described above.

[0069] A further object is a lamella pack consisting of at least 2 lamellae of a composite material comprising a 1st and a 2nd electrical steel layer and a plastic layer arranged in between, characterized in that the pack has at least one weld seam which contacts each individual lamella of the pack and is arranged substantially perpendicular to the lamella surface.

[0070] Alternatively, the welded lamellar assembly has at least 2, preferably 4, particularly preferably 6 and at most 50, preferably 20, particularly preferably 12 welds. In particular, the lamellar assembly has exactly 4, 6, or 8 welds, preferably 6.

[0071] In another alternative, the lamella package has a transport device.

[0072] The invention also relates to a stator stack and a rotor stack containing a laminate stack as described above.

[0073] The present invention also relates to the use of a laminated core as described above in electrical consumers or generators. For example, the laminated cores are used in electric motors and generators.

[0074] Therefore, the invention also relates to the use of a laminated core manufactured according to the invention in a stator. Furthermore, the invention relates to the use of a laminated core manufactured according to the invention in a rotor. Thus, the invention relates to the use of a laminated core manufactured according to the invention in an electric motor or generator.

[0075] Such a stator and / or rotor assembly can preferably have a homogeneous or heterogeneous structure. A homogeneous structure consists of a plurality of layers of the composite material. A heterogeneous structure consists of a plurality of layers, i.e., laminations, of the composite material to be used according to the invention and monolithic electrical steel strip layers arranged between them. For example, the structure can have an arrangement in which every third layer consists of a monolithic electrical steel strip. Alternatively, the package can also have only one, at least one, at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 40, 50, 100, 500, 1000, 10000, 20000, 30000, 50000 or more layers, up to 100000 individual slats (layers).

[0076] Another item is an electric motor containing a stator and / or rotor assembly as described above.

[0077] A further subject matter is the use of a lamellar pack according to the invention in a generator as well as a generator containing such a lamellar pack.

[0078] In addition to or as a joining method, riveting, screwing, soldering, gluing or welding are used according to the invention.

[0079] Surprisingly, it was found that the packaging method according to the invention ensures a secure bond between the lamellae without causing any adverse changes in their properties. In particular, the magnetic, acoustic, and insulating properties of the composite material are not negatively affected compared to the prior art.

[0080] The inventive method, in particular due to the combination of starting material with packaging steps, also allows non-monolithic sheet metal to be processed analogously to monolithic sheet metal.

[0081] The method according to the invention enables the use of thin electrical tapes and the exploitation of the associated advantages, in particular with regard to the magnetic properties, in existing devices, work processes and processing techniques designed for monolithic sheet metal without or with only minor modifications.

[0082] The present method allows for the production and further processing of twice as many individual laminations or rotor / stator stacks with the same number of cutting and packing steps compared to previously known methods. Stacks with high-quality seams and no seam breaks can be produced.

Claims

1. Method for packaging at least 2 laminations made of a composite material by gas-shielded MAG welding, TIG welding or plasma welding, characterized in that the composite material comprises a first and a second electrical steel strip layer and a plastic layer arranged therebetween, and at least one outer side of each lamination has an insulation layer, and prior to MAG welding, TIG welding or plasma welding the laminations are electrically contacted with one another.

2. Method according to any one of the preceding claims, characterized in that the fusion welding is tungsten inert gas (TIG) welding.

3. Method according to any one of the preceding claims, characterized in that the laminations are packaged into a lamination stack of an electrical consumer or generator.

4. Method according to any one of the preceding claims, characterized in that the first and second electrical steel strip layer each have a thickness of at least 0.05 mm and at most 1.5 mm.

5. Method according to any one of the preceding claims, characterized in that the first and second electrical steel strip layer are each a non-grain-oriented electrical steel strip.

6. Method according to any one of the preceding claims, characterized in that the plastic layer has a thickness of at least 2 µm and at most 50 µm.

7. Method according to any one of the preceding claims, characterized in that both outer sides of each lamination each have an insulation layer.

8. Method according to any one of the preceding claims, characterized in that prior to welding the individual laminations are punched or separated from a starting material by laser cutting.

9. Method according to any one of the preceding claims, characterized in that prior to welding the individual laminations are stacked on one another.

10. Lamination stack produced in a method according to any one of claims 1 to 9.

11. Stator stack or rotor stack comprising a lamination stack according to claim 10.

12. Electric motor comprising a stator stack and / or rotor stack according to claim 11.

13. Generator comprising a lamination stack according to claim 10.