Method for producing electromagnetic component for electric machine, and electric machine

Abstract

The invention relates to a method for producing an electromagnetic component for an electric machine. In particular, the electromagnetic component to be manufactured may be a laminated core, such as a stator core or a rotor core, and is preset for use with an electric machine, such as an electric motor. The method comprises the following steps: A) providing a plate as a raw material; b) blanking a plurality of sheets from the plate; c) carrying out heat treatment on the sheet; and D) joining the heat-treated sheets into a component or a section of the component. In addition, the invention also relates to a motor.

Description

[0001] This application is a divisional application of a Chinese invention patent application with an application date of January 17, 2020, a national application number of 202080032103.X (PCT / EP2020 / 051176), and an invention name of “Method for manufacturing electromagnetic components for electric motors, in particular laminated cores, such as stator cores or rotor cores”. Technical Field

[0002] The invention relates to a method for producing an electromagnetic component for an electrical machine, such as a motor or a generator, in particular a laminated core, wherein the laminated core is designed, for example, as a stator core or a rotor core. Background Art

[0003] The way in which electric machines, such as electric motors, function has been known for a long time. Electric motors are gaining more and more importance, not only against the background of their increasing use in individual private transportation, but also with regard to the keyword "electric vehicle". The important components of every electric motor are the stator and the rotor, where the term "stator" refers to the fixed part of the motor and the term "rotor" refers to the moving part of the motor.

[0004] A challenge in providing electric motors is to increase the effectiveness of the electric motor, such as the power per unit volume provided and / or the efficiency, at an economically reasonable cost.

[0005] The idea for providing a highly efficient electric motor is to manufacture the stator and / or the rotor or parts of the stator and / or the rotor as a so-called stator core or rotor core. In this case, the component is composed of individual so-called laminae as a laminated core (also called a laminae pack). The term "lamina" refers to a molded part taken out of an electrical steel sheet or strip. A common method for this is to punch out the laminae. Thereafter, a laminae pack is formed from a plurality of thin laminae by stacking the laminae on top of each other and partially or preferably completely insulating them electrically from each other.

[0006] The production of such a component, in particular such a laminated core, always includes the steps of producing the lamellae and connecting them to one another. The connection is preferably carried out in such a way that after the connection, the lamellae are electrically insulated from one another in sections (preferably completely), i.e. preferably, no two adjacent lamellae are electrically connected to one another.

[0007] The production of the individual laminae is usually carried out by means of stamping. The stamped laminae can be connected to form a laminated core by a number of known methods, for example by screwing, by placing clamps, by welding or by stamping and stacking. However, due to the mechanical effects that occur during the process of establishing the connection, each of the manufacturing methods mentioned, which are familiar to the person skilled in the art, is accompanied by an adverse effect on the general electromagnetic properties of the finished laminated core after the connection. In particular, mechanical stresses are inevitably unavoidable at least to a certain extent during the mechanical connection process, which can have an adverse effect on the magnetic properties and the course of the magnetic field lines in the laminated core, thereby directly having an adverse effect on the performance of the electric motor comprising the laminated core. The electrical connection between two or more laminae that usually occurs during the stamping and stacking process leads to additional losses.

[0008] An excellent possibility to reduce the adverse effects of mechanical action on the lamellae and at the same time achieve good insulation between the lamellae is to use adhesives as a means of connection. These adhesive systems also have insulating properties similar to those of electrical insulation varnishes.

[0009] For this purpose, a treatment method known to the person skilled in the art is the use of so-called baking varnishes. For example, DE 38 29 068 C1 describes the use of baking varnishes for bonding punched electrical steel sheets. A treatment method using baking varnishes is: coating a sheet, in particular a sheet strip; subsequently punching out individual sheets from the sheet; positioning the individual sheets relative to each other in an orientation relative to each other; and subsequently subjecting the resulting sheet stack to a heat treatment for a defined period of time and at a defined temperature. In many cases, during the heat treatment, the sheets are pressed against each other, for example by applying forces, preferably with uniform surface forces, to the end faces in the axial direction of the laminated core pointing to the interior of the laminated core. Typical reaction temperatures are 150° C. to 250° C., typical baking varnish reaction times are 30 to 150 minutes, followed by a cooling phase, wherein the exact parameters naturally depend on the specific baking varnish used, the geometry of the components and the bonding equipment. In general, excellent electromagnetic properties of the stator core and / or rotor core can be achieved by this treatment method. Summary of the invention

[0010] Against the background of the desire for further increased performance, the object of the present invention is to provide an electromagnetic component and an electric machine with improved conversion of electromagnetic energy into mechanical energy.

[0011] The method according to the invention comprises the following steps:

[0012] A) providing a sheet material as a raw material, in particular a sheet material not coated with an adhesive,

[0013] B) Punching out multiple sheets from the sheet,

[0014] C) heat treating the slice,

[0015] D) Joining the heat-treated laminae to form a laminated core or to form sections of a laminated core.

[0016] For example, the steps can be implemented in a so-called in-line method, but it is also possible to implement them in stations that proceed in sequence.

[0017] The term "sheet" generally refers to rolled products made of metallic materials and may refer in particular to metal strips, steel strips or electrical steel strips, for example, made of soft magnetic raw materials, in addition to thin metal sheets or thick metal sheets.

[0018] The sheets are punched out of the sheet. The punching in step B) is preferably carried out by means of a punching tool. Such a punching tool is a tool which punches out sheets, preferably more than one sheet (e.g. four sheets) at the same time, from the sheet. The punching of the sheets by the punching tool is preferably carried out in such a way that a plurality of connecting tabs, e.g. three connecting tabs, are still present between the respectively punched sheets and the sheet originally to be transported to the punching tool, so that the punched sheets are still a one-piece component of the sheet. This serves to make it possible to transport the sheets together with the sheet (in particular a sheet strip) further through the in-line facility.

[0019] However, it can also be provided that the separation of the lamellae from the sheet metal takes place immediately following the punching.

[0020] The important inventive concept is that after the sheets are cut and before they are joined, a heat treatment of the sheets is provided. The heat treatment means, in particular, heating the sheets to a predetermined temperature or a predetermined temperature corridor, maintaining this temperature for a predetermined period of time, and preferably slowly cooling the sheets in an oven.

[0021] The heat treatment may be carried out in a furnace section as part of an in-line process or alternatively in an intermediate step taking place in a closed furnace.

[0022] It has been found that the losses occurring in the electric machine can be significantly reduced when using a stator and / or rotor consisting of a laminated core produced according to the invention, i.e. during its production, a heat treatment of the sheets is carried out after the sheets are stamped and before they are joined. The inventors attribute this to the fact that, due to the stamping, internal stresses and plastic deformations are introduced into the sheets, which have an adverse effect on the course of the magnetic lines of force in the finished laminated core. In particular, in embodiments in which one of the materials mentioned below is used as a starting material and one of the preferred adhesives mentioned below is used, an outstanding synergistic effect is achieved, which is beneficial for the production of excellent electromagnetic components, because the high reactivity and storage stability of the adhesive occur with very good magnetic material properties.

[0023] In a first alternative development of the method, the lamellae joining sequence implemented for each lamella of the plurality of lamellae comprises the following steps:

[0024] D1) applying a heat-activatable adhesive on the surface of the sheet to form an adhesive coating,

[0025] D2) optionally, inspecting the adhesive coating by means of optical inspection methods,

[0026] D3) Activation of adhesive of the adhesive coating, wherein the sheets containing the activated adhesive are then positioned one above the other in a positionally and / or angularly oriented manner and a pressure directed in the axial direction is exerted on the end faces.

[0027] After step C), all steps D1) to D3) are of course carried out in the order D1), D2), D3), so that the raw material for joining the sheets is already heat-treated sheets.

[0028] The application of adhesive can be implemented in particular as completely or substantially completely applying adhesive on the surface of the sheet. In the sense of this improvement, the term "substantially" 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%, in particular 96%, 97%, 98%, 99% or 100% of the area of ​​at least one side of the sheet is covered with adhesive.

[0029] It can be provided that the adhesive applied to the foil is subjected to a heat treatment in a drying region, which is designed, for example, as a separate drying unit or as a drying section of an in-line facility, in order to dry the adhesive.

[0030] Preferably, this method variant is carried out in an inline facility, in a so-called inline process. However, sequential variants are also possible, as long as the important aspect of joining after heat treatment is taken into account.

[0031] The term "inline facility" means that a plurality of processing stations, ie at least those mentioned above, are arranged in a predetermined sequence and that a sheet material, such as an electrical steel strip, introduced into the inline facility is automatically processed in the predetermined stations.

[0032] Preferably, the activation is brought about by irradiating the adhesive coating with infrared radiation by means of a device for emitting infrared radiation.

[0033] The device for emitting infrared radiation can in particular be designed as an NIR emitter, ie a light-emitting device designed to emit electromagnetic radiation in the NIR wavelength spectrum, ie electromagnetic radiation with a wavelength between 780 nm and 3 μm.

[0034] In a preferred method direction, the irradiation of the molded part is carried out in the NIR wavelength range, preferably using wavelengths between 0.8 μm and 1.2 μm, and particularly preferably achieving a maximum luminous power at NIR radiation with a wavelength between 0.85 μm and 0.9 μm.

[0035] When the method is implemented in an inline facility, the inline facility preferably comprises an extrusion punch, which is a punch that, after activation of the adhesive, sequentially separates a sheet still connected to a sheet (in particular a sheet strip) by one or more tabs from the sheet by a force acting perpendicularly to the sheet surface by separating one or more tabs.

[0036] The flakes must be gathered within a short period of time after activation and then one must wait for the adhesive to dry and harden.

[0037] When using a suitable adhesive composition, the board has a surface with a short activation time of, for example, 0.5 to 1 second and a short curing time of only a few seconds.

[0038] It can be provided that (expressed in the process sequence) the device for emitting infrared radiation is arranged after the punching tool, preferably between the punching tool and the extrusion punch, and comprises:

[0039] - at least one upper light emitting device, which is directed towards the first sheet surface in the stamping direction, or

[0040] at least one lower lighting device which is directed opposite to the punching direction towards the second foil surface which is present on the side opposite the punching tool, or

[0041] - It comprises both at least one upper light emitting device and at least one lower light emitting device.

[0042] The light emitting device does not have to be aligned at right angles to the surface of the sheet, but may be aligned at other angles.

[0043] Whether the first and / or second foil surface is illuminated by the lighting means naturally depends on whether a foil coated on one side or on both sides is used. In the first case as well as in the second case, foils with a single-sided adhesive coating can be used, and in particular in the third case, foils with a double-sided adhesive coating can be used, which have the advantage that foils arranged one above the other adhere very well to one another.

[0044] In a second alternative development of the method, the sheet joining is carried out in another way, namely sequentially for each sheet of the plurality of sheets by the following steps:

[0045] D1) applying a heat-activatable adhesive to the surface of the sheet to form an adhesive coating, optionally followed by a heat treatment to dry the adhesive coating,

[0046] D2) optionally, inspecting the adhesive coating by means of optical inspection methods,

[0047] D3) positioning the sheets so as to overlap one another in a positionally and / or angularly oriented manner,

[0048] D4) on the end face side, applying a pressure directed in the axial direction to the lamellae positioned one above the other,

[0049] D5) Heating the sheets positioned one above the other and at least temporarily under pressure at a predetermined temperature for a predetermined period of time in order to activate the adhesive of the adhesive coating.

[0050] If necessary, thermal drying of the adhesive coating can be effected in a drying station after step D1) and before or after step D2).

[0051] The second alternative modification of the method differs from the first alternative modification in particular in that the applied adhesive is not thermally activated by means of thermal activation of the individual foils, for example by infrared radiation, before the individual foils are assembled, but is thermally activated after the foils are assembled, i.e. by heating in an oven.

[0052] In both alternative developments, the application of the heat-activatable adhesive is preferably achieved by providing the adhesive as an aqueous dispersion which is applied to the sheet. Preferably, the application is achieved by means of spraying, but it is also possible to achieve coating by means of a roll-to-roll process, in particular by rollers facing each other.

[0053] The application of adhesive can be implemented in particular as completely or substantially completely applying adhesive on the surface of the sheet. In the sense of this improvement, the term "substantially" 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%, in particular 96%, 97%, 98%, 99% or 100% of the area of ​​at least one side of the sheet is covered with adhesive.

[0054] It can be provided that the adhesive applied to the foil is subjected to a heat treatment in a drying region, which is designed, for example, as a separate drying unit or as a drying section of an in-line facility, in order to dry the adhesive.

[0055] This refers to a process which is similar to the known baking varnish process and which differs from the first alternative in the process for activating the adhesive.

[0056] The predetermined period of time in step D5 is preferably between 5 minutes and 60 minutes, particularly preferably between 10 minutes and 40 minutes.

[0057] As the predetermined temperature, a temperature between 100° C. and 250° C., preferably between 100° C. and 200° C., particularly preferably between 100° C. and 150° C. is predefined in step D5 .

[0058] In the two alternative developments described above, an electrical component, a stator core or a part of a stator core is produced by bonding together lamellae which have been subjected to a heat treatment after punching out and before bonding. According to the inventors, the improvement of the magnetic properties of the individual lamellae described at the outset due to stress relief and / or recrystallization or grain growth, in particular in the edge region of the lamellae, is thus combined with a method for joining the lamellae due to the heat treatment, which cannot be achieved without permanent shape changes, electrical connections between the lamellae or the application of forces to one or more lamellae of the electrical component or stator core. As a result, an electrical component, in particular a stator core or a laminated core, is provided which is particularly suitable for use in electric machines, in particular high-efficiency electric machines, in particular electric machines with high efficiency.

[0059] In a development of the method, at least one electromagnetic component is manufactured according to a method described above and at least one electromagnetic component is manufactured by conventional methods. This makes it possible to manufacture the electric machine according to the desired properties of the electromagnetic component. For example, for a fast-rotating and efficient electric motor, the rotor is stamped and stacked and thus has at least the original mechanical properties of the raw material and thus has a relatively high (operating) strength with respect to plastic deformation or bursting. In contrast, the stator is annealed and bonded by means of the method described above and thus has the relatively lowest losses.

[0060] In other words: it can be provided that an electric motor is provided, which comprises: a first electromagnetic component manufactured by the method according to the present invention or its improved solution, and a second electromagnetic component manufactured by a conventional method, which particularly means: it is manufactured from thin sheets punched out of a sheet and joined (particularly bonded, for example bonded by means of baking varnish), but no heat treatment of the thin sheets is performed after punching out and before joining, similar to step C of the method according to the present invention or its improved solution. This means that the first electromagnetic component comprises the thin sheets heat-treated in step C), while the second electromagnetic component comprises the thin sheets that are not heat-treated after punching out. In particular, the first electromagnetic component can be the stator of the electric motor, and the second electromagnetic component can be the rotor of the electric motor. The advantage of this treatment method is that the stator has excellent electromagnetic properties that can be achieved according to the present invention, while for the rotor, since annealing is abandoned, the mechanical properties important for the rotor as a rotating component, especially the strength, are avoided from being reduced.

[0061] The facts mentioned below apply to the first alternative refinement, the second alternative refinement, and to all variants and refinements thereof.

[0062] Preferably, the inspection of the adhesive coating in step D2 is performed using an optical inspection method. In particular, the method can be automated so that the thin sheet is used in the joining only when the optical inspection method recognizes that the thickness distribution of the adhesive coating is sufficiently uniform, otherwise the thin sheet is removed from the method as waste.

[0063] As an optical inspection method, a thermal image of the adhesive coating, preferably of the adhesive coating that has not yet dried, is particularly preferably acquired by means of a thermal imager. Samples that are only insufficiently coated with adhesive can thus be reliably identified and sufficient mechanical stability of the laminated core can be ensured. It is up to the person skilled in the art who is entrusted with the implementation of the invention to decide when a sample is considered to be insufficiently coated, which is not relevant for the basic mode of operation of the described further development of the method according to the invention.

[0064] In order to position the sheets one above the other in a positionally and / or angularly oriented manner, the sheets are preferably introduced into a receiving device in which the positioning area is located. The positioning area facilitates the positionally and / or angularly oriented positioning of the sheets introduced therein relative to the sheets already located in the positioning area, so that a stack of sheets oriented to one another and provided with activated adhesive is ultimately obtained.

[0065] The positioning area can be, for example, a cylindrical tube, which is designed, for example, as a cylindrical hollow tube with a jacket-like cross section, which corresponds essentially to the cross section of the molded part and is oriented therewith in the predetermined positioning. In order to apply the required pressure, a pressure die is provided, which exerts an axial force on the lamella stack on the end side.

[0066] Applying pressure directed in the axial direction to overlapping sheets refers to applying a pressure, preferably with a uniform surface pressure, in a direction perpendicular to the sheet surface, on the end face side of the core of the joined sheets to squeeze the individual sheets relative to each other.

[0067] Preferably, the sheet metal is a slab or an electrical steel strip made of electrical steel strip, wherein particularly preferably the sheet metal consists of non-grain-oriented electrical steel strip.

[0068] Preferably, a raw material is used which contains, in addition to Fe and unavoidable impurities, the following elements (all data are in wt.%):

[0069] 0.1 to 3.50 Si,

[0070] 0.01 to 1.60 Al,

[0071] 0.07 to 0.65 Mn,

[0072] Optionally, a P of up to 0.25.

[0073] In the context of the present application, when specifying metal alloys, it is to be understood that the weight percentage data of all constituents including unavoidable impurities add up to 100 wt.%.

[0074] Preferably, the raw material is a non-grain-oriented steel which, in addition to Fe and unavoidable impurities, contains the following elements (all data are in wt.%):

[0075] 0.1 to 3.50 Si,

[0076] 0.01 to 1.60 Al,

[0077] 0.07 to 0.65 Mn,

[0078] Optionally, a P of up to 0.25.

[0079] Particularly preferably, in addition to any of the above conditions, the following conditions are also observed (all data are in wt.%):

[0080] 2.3 to 3.40 Si,

[0081] 0.3 to 1.1 Al,

[0082] 0.07 to 0.250 Mn,

[0083] Optionally, up to 0.030% P, with the remainder being Fe and unavoidable impurities.

[0084] Preferably, the non-grain-oriented electrical steel strip or the non-grain-oriented sheet has specific hysteresis losses in the range of 0.7 to 7 W / kg at P1.0 / 50 Hz and in the range of 1.8 to 15 W / kg at P1.5 / 50 Hz, measured according to DIN EN 60404-2, and / or a polarization intensity in the range of 1.45 T to 1.71 T at J2500 and in the range of 1.6 T to 1.8 T at J5000.

[0085] In a preferred embodiment, the non-grain-oriented electrical steel strip or non-grain-oriented sheet has specific hysteresis losses in the range of 0.8 to 3.5 W / kg at P1.0 / 50 Hz and in the range of 1.9 to 8.0 W / kg at P1.5 / 50 Hz, measured according to DIN EN 60404-2, and / or a polarization intensity in the range of 1.47 to 1.71 T at J2500 and in the range of 1.58 to 1.80 T at J5000.

[0086] In another preferred embodiment, the non-grain-oriented electrical steel strip or non-grain-oriented sheet has specific hysteresis losses in the range of 1.0 to 1.5 W / kg at P1.0 / 50 Hz and in the range of 2.2 to 3.3 W / kg at P1.5 / 50 Hz, measured according to DIN EN 60404-2, and / or a polarization intensity in the range of 1.47 to 1.57 T at J2500 and in the range of 1.58 to 1.65 T at J5000.

[0087] Preferably, the non-grain-oriented electrical steel strip or non-grain-oriented sheet has specific hysteresis losses in the range of 8 to 120 W / kg at P1.0 / 400 Hz, measured according to DIN EN 60404-2; specific hysteresis losses in the range of 18 to 360 W / kg at P1.5 / 400 Hz; and / or a polarization intensity in the range of 1.45 T to 1.75 T at J2500, a polarization intensity in the range of 1.45 T to 1.85 T at J5000, and a polarization intensity in the range of 1.50 to 1.95 T at J10000.

[0088] In another preferred embodiment, the raw material has specific hysteresis losses in the range of 10 to 25 W / kg at P1.0 / 400 Hz; specific hysteresis losses in the range of 25 to 49 W / kg at P1.5 / 400 Hz; and / or a polarization strength in the range of 1.45 T to 1.75 T at J2500, a polarization strength in the range of 1.45 T to 1.85 T at J5000, and a polarization strength in the range of 1.50 to 1.95 T at J10000, as determined in accordance with DIN EN 60404-2.

[0089] Preferably, the non-grain-oriented electrical steel strip or non-grain-oriented sheet has a yield strength of 190 to 610 MPa, a maximum tensile strength of 310 to 740 MPa and an A80 minimum elongation at break of 6 to 48% in the longitudinal direction under standard conditions, measured according to DIN EN ISO 6892-1, and a Hv5 hardness of 100-250.

[0090] In a particularly preferred embodiment, the raw material has a yield strength of 310 to 600 MPa, a maximum tensile strength of 400 to 640 MPa and an A80 elongation at break of 7 to 32% and an Hv5 hardness of 130-250 in the longitudinal direction at room temperature, measured according to DIN EN ISO 6892-1.

[0091] Preferably, the material has an anisotropy at P1.0 / 400 Hz in the range of 5 to 17%.

[0092] However, the raw material may also be a soft magnetic raw material which, apart from Fe and unavoidable impurities, consists of (all data are in wt.%):

[0093] 0.1 to 4.0 Si,

[0094] 0.01 to 2.60 Al,

[0095] 0.07 to 3.0 Mn,

[0096] Optionally, a maximum of 0.5 P,

[0097] Optionally, up to 0.015 of B,

[0098] Optionally, up to 0.2% Sb,

[0099] Optionally, up to 0.01% Zn,

[0100] Optionally, up to 5 Cr,

[0101] Optionally, up to 5 Ni,

[0102] Optionally, up to 0.25 V,

[0103] Optionally, up to 0.5 Sn,

[0104] Optionally, up to 0.01 As,

[0105] Optionally, up to 0.3% Nb,

[0106] Optionally, up to 0.5 W,

[0107] Optionally, up to 0.85% Zr,

[0108] Optionally, up to 0.2% Mo,

[0109] Optionally, up to 1.0 Cu,

[0110] Optionally, up to 0.5 Ti,

[0111] Optionally, a maximum of 0.5 C,

[0112] Optionally, up to 0.01 Ce.

[0113] Suitable and preferred is a sheet material, in particular an electrical steel strip, having a thickness of between 0.05 and 2.5 mm, wherein a thickness of between 0.1 and 1.0 mm is preferred. Depending on the application of the electric machine, a thickness of between 0.5 and 1.0 mm is particularly preferably used.

[0114] According to one embodiment, a heat treatment in the form of stress relief annealing is carried out. This means in particular that the sheet is heated to a temperature below the Ac1 temperature of the material used respectively or to a temperature within a temperature corridor. As a temperature, for example, a temperature between 200° C. and 650° C. can be preset. The heating is achieved slowly, for example with a uniform preheating of less than 10 k / min. Thereafter, the temperature is generally maintained for a longer time, for example at least 30 minutes, preferably at least 1 hour, before slow cooling, for example in a protective gas atmosphere and / or before cooling in air. Therefore, stress relief annealing is a suitable method when the sheet material present as raw material already has the desired grain size.

[0115] Alternatively, a heat treatment in the form of a softening annealing can be performed. Heating is performed slowly, for example, with a uniform preheating of less than 10 k / min. Thereafter, before slow cooling, for example, in a protective gas atmosphere and / or before cooling in air, the temperature is maintained for a longer time, for example, at least 1 minute, preferably between 1 hour and 7 hours and more preferably between 1.4 hours and 4 hours. Alternatively, a heat treatment in the form of a recrystallization annealing can be performed. Heating is performed slowly, for example, with a uniform preheating of less than 10 k / min. Thereafter, before slow cooling, for example, in a protective gas atmosphere or before cooling in air according to the temperature, the temperature is maintained for a longer time, for example, at least 30 minutes, preferably between 1 hour and 7 hours and more preferably between 1.5 hours and 4 hours. Preferably, the temperature and the holding time depending on the temperature are selected according to whether grain growth is desired and which target particle size is desired under which raw material (alloy, type, particle size, geometry, etc.).

[0116] The temperature and time data defined above for the annealing step relate to a heat treatment carried out in an annealing furnace as a sequential heat treatment step. If the annealing is carried out in a continuous process, the annealing conditions will naturally be adjusted, which is undoubtedly possible for a person skilled in the art.

[0117] Particularly preferably, both surfaces of the foil are coated with a heat-activatable adhesive so that, when the foils are joined, adhesive surface abuts adhesive surface, which has the advantage of very good mutual adhesion.

[0118] As the adhesive, an adhesive containing the following substances is preferably used:

[0119] - 60 parts by weight of an epoxy resin in its solid resin form,

[0120] - 0.5 to 15 parts by weight of a latent curing agent,

[0121] - 1 to 15 parts by weight of a latent accelerator.

[0122] Preferably, the adhesive contains 1 to 10 parts by weight of a latent curing agent, particularly preferably 2 to 5 parts by weight of a latent curing agent.

[0123] The term "latent curing agent" refers to a substance which is used for curing epoxy resins but which must be activated in particular by supplying chemical and / or thermal energy for curing. The latent curing agent is added to the adhesive as a solid substance, for example in the form of a powder.

[0124] The term "latent accelerator" refers to a substance that accelerates the curing of epoxy resins by latent curing agents. With regard to accelerators, the term "latent" also means that the accelerator must also be activated by chemical energy and / or thermal energy in advance in order to achieve its function. The latent accelerator is added to the adhesive as a solid substance in the form of a powder, for example.

[0125] The composition given above refers to a mixture of components present as solids in given weight parts mixed into an adhesive mixture, which in dispersion and / or solution, becomes an adhesive that can form an adhesive coating by means of a suitable liquid. The adhesive comprising the given components is preferably present as a dispersion of the composition given above in a dispersion medium, in particular as an aqueous dispersion, in a usable state, i.e. in a form suitable for coating.

[0126] Since the foils are coated with a heat-activatable adhesive, extremely high-quality electromagnetic components, in particular stator cores or rotor cores, can be produced in a flexible manner. Since the adhesive must first be heat-activated, the adhesive function can be performed at the desired time or in the desired method step after the foils have been removed from the sheet and after they have been coated with the adhesive, for example by punching. The foils must be assembled within a short period of time after activation, and then it is necessary to wait for the adhesive to dry and harden. Only in this way can a defect-free, non-delaminating and geometrically precise, mechanically stable core be produced.

[0127] By means of the adhesive composition implemented as described above, the sheet has a surface having a short activation time of, for example, 0.5 to 1 second and a short curing time of only several seconds, respectively. These properties are accompanied by relatively high heat resistance and relatively high insulation and aging properties.

[0128] The epoxy resin present in the preferably used adhesives comprises one or more epoxy resin components which comprise more than one epoxy group, wherein preferably at least one epoxy resin has a softening point above 50°C.

[0129] The epoxy resin can be, for example, an aliphatic, alicyclic or aromatic epoxy resin. The aliphatic epoxy resin contains a component carrying an aliphatic group and at least two epoxy resin groups. In a preferred design of the present invention, the epoxy resin is a bisphenol A epoxy resin.

[0130] As the latent curing agent, a substance which preferably undergoes a curing reaction with the epoxy resin of the adhesive at a temperature in the range of 80° C. to 200° C. or a mixture of a plurality of such substances is used.

[0131] The curing agent may include dicyandiamide, aziridine derivatives, triazine derivatives, imidazoline, imidazole, o-tolylbiguanide, cyclic amidine, organic hexafluoroantimonate compounds or hexafluorophosphate compounds or BF3-amine complexes. These compounds may be used alone or in combination.

[0132] In one configuration, the adhesive may contain 1 to 10 parts by weight of a latent accelerator, preferably 1 to 5 parts by weight of a latent accelerator, particularly preferably 2 to 5 parts by weight of a latent accelerator, and particularly preferably 2 to 4 parts by weight of a latent accelerator.

[0133] In another preferred embodiment, it is provided that the adhesive also comprises 0.2 to 8 parts by weight, preferably 0.2 to 4 parts by weight of an absorbing additive. According to this extended concept, the absorbing additive that can be provided is selected from the group of lamp blacks (flame blacks) and / or the group of water-soluble pigments.

[0134] The term "absorbing additive" refers to a substance that absorbs thermal radiation. Substances that absorb thermal radiation have the advantage, in particular, that a more efficient method is achieved in which thermal activation of the adhesive is achieved by means of electromagnetic radiation, in particular by irradiation with light in the IR wavelength range, preferably in the NIR wavelength range.

[0135] Preferably, the adhesive contains one or more insulating additives known to those skilled in the art, wherein the term "insulating additive" refers to an additive specifically provided to increase the electrical resistance of the adhesive. The insulating additive can be contained in the adhesive in an amount of 1 to 10 parts by weight, preferably 1 to 5 parts by weight.

[0136] Preferably, the latent accelerator comprises a urea derivative.

[0137] Particularly preferably, the urea derivative is N,N-dimethylurea or N,N′-dimethylurea or a difunctional urea derivative preferably comprising two urea groups as functional groups, specifically, particularly preferably 4,4′-methylenebis(phenyldimethylurea), or a mixture of a plurality of the above.

[0138] The latent accelerator contained in the binder preferably consists of at least 50 wt.%, more preferably at least 90 wt.%, more preferably at least 98 wt.% of 4,4'-methylenebis(phenyldimethylurea), and very preferably consists entirely of it.

[0139] It can be provided that the adhesive coating is applied to the thin sheet on one side or on both sides. If the adhesive coating is applied on both sides, the thickness of the coating can be the same, but different thicknesses can also be provided.

[0140] The preferred adhesive coating thickness, i.e., the coating thickness on one side in the case of single-sided adhesive or the total thickness of the adhesive coating on both sides in the case of double-sided adhesive coating, is between 1 μm and 20 μm, preferably between 2 and 10 μm, and particularly preferably between 4 and 8 μm.

[0141] All of the binders mentioned as being advantageous for use also have the advantage that they can be provided as aqueous dispersions which are therefore suitable for application to the foil, for example by means of spraying.

[0142] In addition, it is particularly advantageous that, due to the high reactivity of the adhesive, only a relatively short and low heat input to the adhesive coating is required to join the foils, so that in particular, step C) carried out according to the invention is and always is important for the mechanical properties of the foils, so that by optimizing a single step, the mechanical properties of the finished component can ultimately be set to a large extent.

[0143] For example, the possibility of a different sheet material selection, a higher degree of structural freedom in the sheet material design, results in possible advantages for the electromagnetic, mechanical and thermal motor design, as well as advantages with regard to possible component tolerances and media and / or heat conduction. Further advantages result in component and motor production (for example when working with compact and robust components) and in mechanical processing. Further advantages for a motor comprising one of the sheets according to the invention or one of its developments are: higher power and efficiency, lower required installation space, better geometrical properties (for example, which can be achieved, in particular with a constant surface pressure, by means of recompression towards the stop, with the advantage of better dimensional accuracy of the electromagnetic component) and acoustic advantages depending on the design.

[0144] It can be provided that a surface inspection system, for example a thermal imager, is arranged directly after the coating station, which optionally includes a layer thickness measuring system, which monitors the coating process and, as a byproduct, enables additional quality control for larger defects and holes in the electrical steel strip. In order to detect holes, a light source can also be integrated into the foil holder, so that if there are holes, the sensor detects these and automatically rejects the foil from the process.

[0145] In the positioning station, measuring coils for verifying the electromagnetic properties of the core can be included, so that the influences and measured dimensions can be detected by sensors and saved in a database, or alternatively or additionally forwarded to another system via an interface. Furthermore, it can be provided, for example, that an identification number of the sheet or electrical component is written, for example, into the adhesive coating, by means of a laser.

[0146] It can be provided that after the method for producing the laminated core is completed, its edges are cleaned in order to remove any adhesive residues on the edges of the laminated core or on the sides of the laminated core. The cleaning can be carried out chemically and / or mechanically. BRIEF DESCRIPTION OF THE DRAWINGS

[0147] Further details, features and advantages of the subject matter of the invention emerge from the following description made with reference to the drawing, in which an embodiment of the invention is shown by way of example.

[0148] It goes without saying that the features mentioned above and explained below can be used not only in the respectively stated combination but also in other combinations or alone.

[0149] In the attached picture:

[0150] As an implementation scheme, Figure 1 A schematic diagram showing a first improved solution of the present invention is shown,

[0151] As an implementation scheme, Figure 2 A schematic diagram shows an alternative development of the present invention. DETAILED DESCRIPTION

[0152] exist Figure 1 Schematically shown in FIG. 1 , as a raw material, a sheet 1 designed as a non-grain-oriented electrical steel strip is provided. A plurality of thin sheets 2 are punched out of the sheet by a punching tool 4, which in the embodiment shown are collected in a stack 3. After punching, the thin sheets are heat treated in a furnace 5. The exact type of heat treatment is the responsibility of the person skilled in the art and depends in particular on the raw material; in the case where grain growth is no longer desired, the heat treatment can in particular be a stress relief annealing known to the person skilled in the art, i.e., slow heating to a temperature corridor below Ac1, keeping in this temperature corridor for a long time (e.g. 60 minutes), and slow cooling due to room temperature. By carrying out the heat treatment, the internal stresses still present in the obtained thin sheets due to punching, especially in the edge region, are eliminated or at least largely eliminated. Starting with the thin sheets obtained in this way, the heat-treated thin sheets can be joined to form a laminated core or to form sections of a laminated core. In order to join the thin sheets, each of the plurality of thin sheets is transported sequentially to different processing stations by a conveyor belt. In the first work station 6, the adhesive present as an aqueous dispersion is applied over the entire surface by means of a spray device 6'. The foil thus also has a heat-activatable adhesive coating. Directly after the coating, the applied coating is checked for sufficient defect-freeness in an inspection station 7 by means of a thermal imaging camera 7' and a connected evaluation device, and rejects are sorted out if necessary. Optionally, a drying station can also be provided to dry the adhesive coating.

[0153] Thereafter, in an activation station, the wafer provided with a substantially defect-free coating is irradiated with NIR radiation under a NIR lighting device 8 ′, preferably with an emission power between 5 kW and 20 kW, in order to activate the adhesive of the adhesive coating.

[0154] After the activation of the adhesive, the sheets containing the activated adhesive are positioned 3' on top of each other in a positionally and / or angularly oriented manner. Thereafter, the pressing die 9 applies a pressure to the stack 3' of sheets on the end face side, which pressure is directed to axially compress the laminated core. Preferably, a uniform surface pressure is applied here, so that the force applied in the axial direction is the same at any location on the end face.

[0155] exist Figure 2 Another embodiment is shown in FIG. Figure 1 The embodiment shown in FIG. 1 differs in that no activation station 8 is provided. Instead, a plurality of sheets coated at station 6 and tested at station 7 are positioned one above the other in a positionally and / or angularly oriented manner, and the sheets are heated in an oven 9 to a temperature between 100° C. and 250° C. and kept there for a sufficiently long time, for example at least 30 minutes, in order to activate the adhesive. At the same time, the laminated core is compressed by means of pressure exerted by a punch 9.

[0156] The embodiment of the entire method is carried out in an online process or a continuous process. Figure 1 Neutralization Figure 2 The method shown in FIG. 1 is equally worthy of execution, in particular, the flakes are not collected in a stack 3, but remain fixed on one or more tabs, in particular three tabs, on the sheet so that it can be transported through the entire process by transporting the sheet. Moreover, instead of the oven 5, for example, a continuous heating oven can be used, and in step station 8 ( Figure 1 ) or at station 7( Figure 2 ), the tabs are removed from the sheet by separating the tabs with a so-called extrusion punch known to those skilled in the art. As long as the person skilled in the art implements the boundary conditions required according to the invention or for further developments, these processes are functionally equivalent.

Claims

1. A method for manufacturing an electromagnetic component for an electric machine, wherein the method comprises the following steps: A) Provide plates as raw materials, B) punching out a plurality of thin sheets from the sheet, C) subjecting the sheet to a heat treatment, D) joining the heat-treated sheets to form the component or to form sections of the component, Characterized in that the joining of the sheets implemented for each of the plurality of sheets sequentially comprises the following steps: D1) applying a heat-activatable adhesive to the surface of the sheet substantially over the entire surface to form an adhesive coating, D2) positioning the sheets so as to overlap one another in a positionally and angularly oriented manner, D3) applying a pressure directed in the axial direction to the sheets positioned one above the other on the end face side, D4) heating the sheets positioned one above the other and at least temporarily under pressure at a predetermined temperature for a predetermined period of time in order to activate the adhesive of the adhesive coating.

2. The method according to claim 1, wherein after step D1) and step D2) beforehand, in a drying zone, the adhesive coating is thermally dried.

3. The method according to claim 1, wherein after step D1) and step Prior to D2), the adhesive coating is inspected by means of an optical inspection method.

4. The method according to any one of claims 1 to 3, wherein the time period predetermined in step D4) is between 5 minutes and 60 minutes.

5. The method according to any one of claims 1 to 3, wherein the temperature predetermined in step D4) is between 100°C and 250°C.

6. The method according to claim 3, wherein the thin sheet is used in the joining only if the optical inspection method detects a sufficiently uniform thickness distribution of the adhesive coating, otherwise the thin sheet is removed from the method as waste. 7 . The method according to claim 3 , wherein as an optical inspection method, a thermal image of the adhesive coating is detected by means of a thermal imager.

8. The method according to claim 1, wherein the sheet material is - slabs or strips made from electrical steel strip, or - Slabs or strips made of soft magnetic raw materials.

9. The method of claim 1 wherein the sheet is made from non-grain oriented electrical steel strip.

10. The method according to claim 8 or 9, wherein the plate material, in addition to Fe and unavoidable impurities, is composed of the following, all data being in wt. %: 0.1 to 3.50 Si, 0.01 to 1.60 Al, 0.07 to 0.65 Mn, The total amount of all components including inevitable impurities is 100 wt.%.

11. The method of claim 10, wherein the sheet further comprises up to 0.25 wt. % phosphorus.

12. The method according to claim 10, wherein in step C), A heat treatment in the form of a stress relief annealing, or Heat treatment is performed between Ac1 and Ac3.

13. The method according to any one of claims 1 to 3, wherein the application of the heat-activatable adhesive is effected on both surfaces of the foil.

14. The method according to any one of claims 1 to 3, wherein the heat-activatable adhesive comprises: 60 parts by weight of epoxy resin, 0.5 to 15 parts by weight of a latent curing agent, 1 to 15 parts by weight of a latent accelerator.

15. The method according to any one of claims 1 to 3, wherein the electrical machine is an electric motor.

16. The method according to any one of claims 1 to 3, wherein the electromagnetic component is a laminated core.

17. The method according to any one of claims 1 to 3, wherein the electromagnetic component is a stator core or a rotor core.

18. The method according to any one of claims 1 to 3, wherein the period of time predetermined in step D4) is between 10 and 40 minutes.

19. The method according to any one of claims 1 to 3, wherein the temperature predetermined in step D4) is between 100°C and 200°C.

20. The method according to any one of claims 1 to 3, wherein the temperature predetermined in step D4) is between 100°C and 150°C.

21. The method according to claim 3, wherein as an optical inspection method, a thermal image of the adhesive coating that has not yet dried is detected by means of a thermal imager.

22. A motor, comprising: A first electromagnetic component and a second electromagnetic component, wherein the first electromagnetic component is manufactured by the method according to any one of claims 1 to 21, and wherein the second electromagnetic component is formed by joining thin sheets as a laminated core, wherein the thin sheets of the second electromagnetic component are not subjected to any heat treatment after punching out the sheet provided as the raw material and before joining to form the second electromagnetic component.

23. The motor according to claim 22, wherein the second electromagnetic component is a laminated core formed by bonding thin sheets.

24. An electric machine as claimed in claim 22, wherein the sheet material is electrical steel strip as defined in claim 9 or claim 10.

25. The electric machine of claim 22, wherein the first electromagnetic component is a stator of the electric machine and the second electromagnetic component is a rotor of the electric machine.

26. An electrical component or a laminated core, which is produced by the method according to any one of claims 1 to 21 and is designed as a stator or a rotor.

27. An electrical machine comprising the electrical component according to claim 26.

28. The electric machine according to claim 27, wherein the electric machine is designed as an electric motor for a passenger car, a truck, a motor two-wheeled vehicle, a small electric car, an airplane or a drone.

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