Method for producing a component of an electric motor, electric motor component and electric motor

Abstract

The invention relates to the production of a component of an electric motor, in particular a stator or a rotor, wherein a layer structure is generated using additive manufacturing as follows: different layers (3, 4), namely a first type of layers (3) made of filaments containing plastic and metal and a second type of layers (4) made of filaments containing plastic and ceramic, are produced alternately by additive manufacturing; the layer assembly (2) produced from the various layers (3, 4) is heated to a first temperature (T1), at which the plastic is removed from the layers (3, 4); the layer assembly (2) is further heated, whereby the metal of the first type of layers (3) is sintered and an electrically insulating ceramic layer is obtained from the second type of layers (4). The invention also relates to an electric motor component produced subsequently and to an electric motor.

Description

Technical Field

[0001] The invention relates to a method for producing a component, in particular a rotor or a stator, of an electric motor. The invention further relates to an electric motor component having a layer structure made of layers of different compositions and to an electric motor. Background Art

[0002] DE 10 2016 119 650 A1 describes a method for producing a soft magnetic core material for motors and actuators, wherein the core material is constructed from layers of different material components using an additive manufacturing method. In this case, the material component can have a ceramic component. The component based on a metal material can have a silicon content of 6.5% or more. Additive manufacturing should be able to use powdered starting materials. After forming, the powder from the additive method can be partially blown out. It is intended that the porosity of the workpiece, i.e., a component of the motor, is minimized by sintering, which is also mentioned in DE 10 2016 119650 A1.

[0003] A further method for producing components of an electric machine is disclosed in DE 10 2017 220 735 A1. In this case, the individual sheet metal layers of the stator should be producible using a three-dimensional generative manufacturing method, so that no compressive or tensile stresses occur in the angled regions of the sheet metal layers. A laser sintering method is mentioned as an example of a generative manufacturing method. Insulating foils or insulating varnishes are suggested as insulating materials between the sheet metal layers. Overall, the machine according to DE 10 2017 220 735 A1 is a transverse flux machine.

[0004] DE 10 2017 222 635 A1 describes a stator of an electric machine with a cooling system. In this case, it is provided that the cooling channel walls are produced by an additive method. As a result, it should no longer be necessary to additionally seal the cooling channel walls to the stator plate.

[0005] From EP 3 255 758 A1 a rotor for a reluctance machine is known, which is produced at least partially by additive manufacturing. A shapeless substance such as a liquid or powder or a neutral shape material such as a tape or a wire should be able to be used as a starting material for additive manufacturing. The finished rotor manufactured by means of the additive method has alternating conductor layers and insulating layers in the axial direction. The intermediate insulating rod should also be able to be manufactured in an additive manner.

[0006] WO 2019 / 022973 A1 relates to the additive manufacturing of vehicle components. Here, the use of the ADAM method (atomic diffusion additive manufacturing) is proposed. A typical ADAM method uses a starting material comprising metal and plastic, wherein the plastic is melted away. The remaining metal is densified by sintering.

[0007] For example, methods and devices for fiber-reinforced production are described in documents WO 2017 / 123726 A1 and EP 3 444 102 A1.

[0008] The filaments described in US Pat. No. 10,016,942 B2 and intended for use in additive processes are believed to be virtually pore-free and comprise a polymer surrounding a multi-strand core.

[0009] WO 2018 / 102739 A1 explains options for sintering components produced generatively by a densification linking platform.

[0010] Regarding additive manufacturing, US2018 / 0236546 A1 proposes sintering at two temperature levels, wherein the first temperature level is 500 degrees Celsius to 700 degrees Celsius and the second temperature level is 1000 degrees Celsius to 1200 degrees Celsius.

[0011] WO 2016 / 146374 A1 discloses a 3D printing method for embedding a component in a 3D printing material. The embedded component may differ from the surrounding 3D printing material in terms of its thermal or magnetic properties.

[0012] WO 2014 / 0172148 A1 describes the possibility of producing coated filaments for extrusion-based 3D printing methods. Here, coating the filaments outside the printer in a separate method is provided.

[0013] Independent of the additive manufacturing method, electrical steel is often used to produce components for electric machines. The coated electrical strip described in DE 10 2018 209 553 A1 can have a total alloy content of silicon and aluminum of equal to or greater than 1%, 2%, 3% or 4%. The values ​​0.8%, 1.5%, 2% and 3% are mentioned as possible silicon proportions.

[0014] Another electrical strip described in DE 10 2018 201 622 A1 has a silicon content of 2.3% to 2.7% and an aluminum content of 0.3% to 0.8%, both silicon content and aluminum content being expressed in weight percent. Summary of the invention

[0015] The invention is based on the object of further developing the production of components, in particular rotors and stators, for electric motors compared to the prior art both from a production engineering and physical point of view.

[0016] This object is achieved by a method according to the invention for producing a component for an electric motor. The object is also achieved by an electric motor component according to the invention. The electric motor component can be a stator or a rotor, and in the case of a linear motor, the electric motor component can also be a rotor. The object is also achieved by an electric motor according to the invention. In particular, the electric motor can be a synchronous electric motor or an asynchronous electric motor. In the following, the embodiments and advantages of the invention explained in conjunction with the electric motor component also apply analogously to the production method and the electric motor, and vice versa.

[0017] The electric motor components are manufactured by the following steps:

[0018] The different layers, namely a first type of layers made of filaments containing plastic and metal and a second type of layers made of filaments containing plastic and ceramic, are additively produced in an alternating manner.

[0019] the layer assembly produced in the first step is heated to a first temperature, at which the plastic is removed from the layers, in particular by diffusion,

[0020] The layer arrangement is brought to an elevated temperature level again, the metal of the layers of the first type is sintered, and an electrically insulating ceramic layer is obtained from the layers of the second type.

[0021] The first type of layers serve as flux conducting layers in the finished electric motor component, which are separated from each other by the second type of layers, namely insulating layers. The various filaments that construct these layers are generally referred to as plastic / metal filaments or plastic / ceramic filaments, the composition of the filaments being simply referred to as "plastic", optionally including other components. In any case, the filaments used to construct the layer assembly are linear in shape, and the diameter of the plastic / metal filaments can be different from the diameter of the plastic / ceramic filaments.

[0022] After the assembly of the device formed from the various layers has been completed, the entire layer assembly can be heat treated by different method variants while maintaining a defined temperature profile. In any case, immediately before the temperature increase or at any later time, the plastic parts are at least largely removed from all layers - not necessarily at the same time - so that the metal of the first type of layer is sintered and a ceramic is produced from the second layer, also during the sintering process.

[0023] In general, the filament-based production of electric motor components, in particular stators or rotors, results in a layered structure in which the electrically conductive layers and the magnetically conductive layers, i.e. the layers of the first type, are electrically insulated from one another by ceramic layers and are mechanically firmly connected to one another. By using filaments as precursor products, significantly higher geometrical precision can be achieved compared to powdered starting materials. The multi-stage heating of the layer assembly also ensures that the workpiece, i.e. the electric motor component to be produced, is already stabilized before sintering and that undesirable influences, such as those caused by diffusion, are minimized. The thickness of each layer of the finished product, i.e. the component suitable for installation in an electric motor, can be adjusted as required and does not exceed 0.15 mm, for example.

[0024] According to a possible procedure, after having reached the first temperature level, the workpiece reaches an intermediate temperature level, which is closer to the first temperature level than to the second temperature level, i.e. the temperature level selected for sintering. In other words: the first temperature level is divided into two levels, which can be close to each other, but can be clearly distinguished from each other and set successively. The divided temperature levels applied before sintering have the effect of first changing only one of the layer types and then changing the other layer type. For example, the plastic parts of all layers of the first type are first removed, while the plastic parts of the layers of the second type are not yet affected at this time, thereby ensuring that the metal parts of all layers of the first type remain completely separated from each other. With the subsequent slow increase in temperature to the intermediate level, the layers of the first type are practically no longer changed. On the contrary, at this process stage, the plastic is removed from the layers of the second type, and this is not disadvantageous in the case where the plastic partially enters the layers of the first type.

[0025] The subsequent sintering can occur at a constant temperature level or at a divided level after the previous treatment, i.e. the removal of the plastic. Sintering can also mean a process that is carried out at a uniform temperature level or using different temperatures set in succession. For example, a temperature level is first selected that completes the sintering of the essentially metal layer, i.e. the first type of layer. This will result in a reduction in the volume of the entire component. Since sintering has not yet occurred in the ceramic component, i.e. in the second type of layer, the ceramic material adapts to the changes in the size of the metal layer during this processing stage. Subsequently, a temperature level called an elevated level is set that completes the sintering process in the second type of layer, which is the final ceramic layer formed by these layers. The boundary surface between the metal layer and the ceramic layer is ultimately constructed in the following manner: on the one hand, there is a firm interlocking between the layers, and on the other hand, there will be no excessive fluctuations in the layer thickness.

[0026] Compared to electric motor components produced from conventional electrical steel sheets, the electric motor component according to the invention has the particular advantage that there is greater freedom in the composition of the layers. In particular, the metal is formed from an iron alloy containing more than 6.5% by weight of silicon and aluminum in the range of 1% to 5% by weight. The silicon content is preferably in the range of more than 6.5% by weight to 10% by weight. Such a composition of the metal used can only be used completely by using a generative production method, since rolling is not possible here. As a result, a higher magnetic flux density is obtained than with known electrical steel sheets, and the performance of the electric motor is significantly improved.

[0027] When the layers are built up during manufacturing, they are advantageously in a horizontal orientation. Optionally, manufacturing is followed by a final processing step which may include heat treatment and / or mechanical processing, such as grinding.

[0028] The electric motor according to the invention comprises at least one electric motor component according to the invention in the form of a rotor or a stator. In particular, the electric motor is a synchronous electric motor or an asynchronous electric motor. Furthermore, the electric motor can be a linear motor, wherein the electric motor component is a rotor. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In the following, several exemplary embodiments of the invention are explained in more detail with the aid of the accompanying drawings.

[0030] In the attached picture:

[0031] Figure 1 shows a cross-sectional view of an electric motor component,

[0032] Figure 2 The electric motor components are shown in a perspective view,

[0033] Figure 3 The essential features of the method for producing an electric motor component are shown in the flow chart.

[0034] Figures 4 to 6 Different variants of temperature control in the manufacture of electric motor components are shown. DETAILED DESCRIPTION

[0035] Unless otherwise specified, the following description relates to all exemplary embodiments. In all drawings, components or parameters that correspond to each other or have substantially the same effect are marked with the same reference numerals.

[0036] The electric motor component, generally designated 1, is part of a stator of an electric motor, not shown in greater detail. The electric motor component 1 has a layer assembly 2, which is formed of a first type of layer 3 and a second type of layer 4. In the finished electric motor component 1, the first type of layer 3 is a metal layer and the second type of layer 4 is a ceramic layer. Figure 2 The support structure 5 that can be seen in the drawing is not critical.

[0037] In the production of the layer assembly 2, the principle of the ADAM method known per se is used. In a first method step S1, a first type of layer 3 is built up from plastic / metal filaments. Then, in step S2, a second type of layer 4 is built up from plastic / ceramic filaments, i.e. applied to the previously produced first type of layer 3. Steps S1, S2 are repeated alternately until the layer assembly 2 is completed.

[0038] The layer assembly 2 is then heat treated in step S3, which will be discussed in more detail below. Figure 3 In the figure, the kiln is indicated by 6. After the heat treatment is completed, the layer assembly 2 is subjected to post-treatment in step S4, which step may include surface treatment. Step S5 marks the end of the method.

[0039] exist Figures 4 to 6 In the figure, three different variants of the temperature control in method step S3 are outlined. All three variants have in common that the temperature T of the workpiece, i.e. the temperature T of the layer assembly 2, is first raised to a first temperature level T1, at which the plastic components are removed. The significantly higher temperature level T2 reached in all variants causes the sintering process.

[0040] exist Figure 4 In the simplest variant shown, the temperature level T1 remains constant during the time period t1 to t4. In this case, a constant temperature level T2 is maintained during the time period t5 to t8.

[0041] In accordance with Figure 5 In a method variant of the present invention, the lower temperature levels are divided: the first temperature level T1 is maintained only in the time period t1 to t2. An intermediate temperature level T11 is set in the time period t3 to t4, which is substantially closer to the first temperature level T1 than the second temperature level T2. In general, in the time period t1 to t4, plastic components are removed from both layer types 3, 4, wherein the temperature levels T1, T11 are set such that plastic components are removed successively from the different layer types 3, 4. With regard to the heat treatment at the second temperature level T2, according to Figure 4 Variations and bases Figure 5 There are no differences between the variants.

[0042] Regarding the treatment at temperature levels T1 and T11, according to Figure 6 The method variant corresponds to the Figure 5 There is a difference only at the higher temperatures: after the second temperature level T2 has been kept constant from t5 to t6, the temperature T is set to the excessive temperature level T22 in the time period t7 to t8. This division into higher temperature levels ensures that the sintering processes in the layer types 3, 4 proceed in a defined manner one after the other.

[0043] By reference Figures 4 to 6 With each of the method variants explained, a layer thickness of less than 0.15 mm, for example a layer thickness of only 0.125 mm, can be achieved.

[0044] Description of Reference Numerals

[0045] 1 Component of electric motor, electric motor component 2 Layer assembly 3 First type of layer, metal layer 4 Second type of layer, ceramic layer 5 Support structure 6 Kiln t Time t0 ... t9 Time point T Temperature T1 First temperature level T11 Intermediate temperature level T2 Second temperature level T22 Excessive temperature level S1 ... S5 Method steps.

Claims

1. A method for producing a component (1) for an electric motor, the method comprising the following steps: - alternately additively producing different layers (3, 4), namely a first type of layers (3) made of filaments comprising plastic and metal and a second type of layers (4) made of filaments comprising plastic and ceramic, - heating the layer assembly (2) produced from the various said layers (3, 4) to a first temperature (T1), at which the plastic is removed from the said layers (3, 4), - Further heating of the layer assembly (2), whereby the metal of the first type of layer (3) is sintered and an electrically insulating ceramic layer is obtained from the second type of layer (4).

2. The method according to claim 1, characterized in that: After the first temperature (T1) is set, before sintering, an intermediate temperature level (T11) is set, at which the plastic is further removed from the layer assembly (2).

3. The method according to claim 1 or 2, characterized in that: The layers (3, 4) are sintered at two temperature levels (T2, T22) set successively.

4. The method according to claim 1 or 2, characterized in that: The plastic composition of the various filaments constituting the layers (3, 4) differs from one another.

5. The method according to claim 1 or 2, characterized in that: The metal is formed from an iron alloy containing more than 6.5% by weight of silicon and in the range of 1% to 5% by weight of aluminum.

6. An electric motor component (1) having a layer assembly (2) consisting of a metal layer (3) and a ceramic layer (4) produced by a method according to one of claims 1 to 5.

7. The electric motor component (1) according to claim 6, characterized in that The thickness of the metal layer (3) does not exceed 0.15 mm.

8. The electric motor component (1) according to claim 6 or 7, characterized in that The thickness of the ceramic layer (4) does not exceed 0.15 mm.

9. The electric motor component (1) according to claim 6 or 7, characterized in that The mass content of silicon in the metal layer (3) is greater than 6.5% by weight, and the mass content of aluminum is in the range of 1% to 5% by weight.

10. The electric motor component (1) according to claim 9, characterized in that The mass content of silicon in the metal layer (3) is in the range of greater than 6.5% by weight to 10% by weight.

11. An electric motor comprising at least one electric motor component (1) according to one of claims 6 to 10 in the form of a rotor or a stator.

12. The electric motor according to claim 11, characterized in that The electric motor is a synchronous electric motor or an asynchronous electric motor.

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