ROTOR SHEET, METHOD FOR MANUFACTURING A ROTOR SHEET AND ELECTRICAL MACHINE

Description

[0001] The invention relates to a rotor lamination, a method for producing a rotor lamination and an electrical machine.

[0002] Magnetic sheets for electrical machines can now be manufactured using screen printing and / or stencil printing. First, a metal powder is processed into a printing paste, and this printing paste is then processed into a green body, i.e., a thick film, using screen and / or stencil printing. The green body is then sintered into a structured metallic sheet using thermal treatment, i.e., debinding and sintering.

[0003] In particular, magnetic sheets made of pure iron can be easily manufactured this way. However, for magnetic sheets in the form of rotor laminations, which are intended to be used at high target speeds and / or operated at rapidly changing speeds, the mechanical properties of pure iron are not sufficient. In particular, the tensile strength of pure iron is often insufficient to withstand the centrifugal forces and other acceleration forces that occur. DE 10 2009 042607 A1 and JP 3 705450 B2 are state of the art.

[0004] Nevertheless, the soft magnetic properties of pure iron are particularly good compared to alternative materials. Therefore, the object of the invention is to create an improved rotor lamination that can withstand high speeds and significant speed changes, while also exhibiting sufficiently good magnetic properties.

[0005] This object of the invention is achieved with a rotor lamination having the features specified in claim 1, with a method for producing a rotor lamination having the features specified in claim 6, and with an electrical machine having the features specified in claim 11. Preferred developments of the invention are specified in the associated subclaims.

[0006] The rotor lamination according to the invention comprises at least a first material and a second material, in which the first material is at least partially soft magnetic and the second material has a higher mechanical tensile strength than the first material, wherein the first and second materials are integrally bonded to one another, sintered together. The term "sintered together" is expediently understood to mean co-sintered. In this way, the rotor lamination according to the invention is advantageously a sintered product which has both sufficiently high mechanical tensile strength to reliably withstand high rotor speeds and also sufficiently good soft magnetic properties to produce a rotor lamination that can be used in a high-performance electrical machine.The rotor lamination according to the invention can advantageously be formed with a wide selection of magnetically active materials for the first material and / or mechanically stabilizing materials for the second material. Furthermore, there is considerable freedom in shaping the first material and the second material. Advantageously, the rotor lamination according to the invention can also be formed in a structurally conforming manner, ie, a significant reduction in the first soft magnetic material compared to conventional rotor laminations is not required according to the invention.

[0007] In the rotor lamination according to the invention, the first material preferably comprises pure iron and / or the second material comprises steel. Steel advantageously exhibits particularly high mechanical tensile strength. Pure iron is advantageously magnetically soft.

[0008] In the rotor lamination according to the invention, the first material and the second material expediently differ in their thermal

[0009] The coefficients of expansion differ from each other by a maximum of 10 10 -6 / K, preferably by a maximum of 5 10 -6 / K, suitably by a maximum of 2 10 -6 / K, ideally by a maximum of 1 10 -6 / K. This ensures the stability of the mechanical joint both during sintering and during operation.

[0010] In the rotor lamination according to the invention, the first and second materials are preferably positively connected to one another. In this embodiment, the connection between the first and second materials is additionally stabilized by the positive connection.

[0011] The rotor lamination according to the invention has a circular geometry and / or a rotational symmetry and the second material preferably forms radially extending struts which taper in the radial direction, in particular at a radially outer end.

[0012] Additionally or alternatively, the second material occupies a smaller mass and / or volume fraction than the first material. In this refinement, the magnetic properties of the rotor lamination are advantageously predominantly dominated by the first material, while the second material can be limited to a volume or mass fraction sufficient for mechanical stability.

[0013] In the rotor lamination according to the invention, the first material has grooves within which the second material is located. Advantageously, the first and second materials are flush on the surface.

[0014] In the rotor lamination according to the invention, the second material is suitably arranged on both sides of the first material.

[0015] In the method according to the invention for producing a rotor lamination according to the invention as described above, the first and second materials are co-sintered.

[0016] Advantageously, in the method according to the invention, the first material is first manufactured as a green part, followed by the second material being applied to the first material, and the first and second materials are subsequently co-sintered. Alternatively, and equally advantageously, the second material is first manufactured as a green part, followed by the first material being applied to the second material, and the first and second materials are subsequently co-sintered.

[0017] In the method according to the invention, the first material is first manufactured as a green part and the second material is manufactured as a green part. The first and second materials are then positively bonded, in particular laminated, to one another, and then the first and second materials are co-sintered. In this development, the first and second materials can each be prefabricated as a green part, thus allowing for a particularly high degree of freedom in shaping.

[0018] In the method according to the invention, the green part(s) is / are preferably manufactured by tape casting and / or by screen and / or stencil printing and / or by slip casting and / or by punching and / or water jet cutting and / or hot stamping and / or binder jetting and / or by additive manufacturing. The aforementioned manufacturing method(s) are advantageously known for providing green parts, so that conventional manufacturing methods can generally be used as far as possible to carry out the method according to the invention. Advantageously, the method according to the invention is cost-effective and can be implemented in large series.

[0019] In the method according to the invention, a material from the group of first and second materials is preferably applied to another material from the group of first and second materials by means of tape casting and / or by means of screen and / or stencil printing and / or by means of slip casting and / or by means of punching and / or water jet cutting and / or hot stamping and / or binder jetting and / or by means of additive manufacturing and / or by means of spraying and / or roll coating. The electrical machine according to the invention is in particular a motor and / or generator and has a rotor lamination according to the invention as described above.

[0020] The invention is explained in more detail below with reference to exemplary embodiments illustrated in the drawings. In the drawings: Fig. 1 shows a rotor sheet according to the invention manufactured according to the invention with a first and a second material schematically in a plan view, Fig. 2 shows the rotor sheet according to the invention according to Fig. 1schematically in cross section, Fig. 3 shows a further embodiment of a rotor lamination according to the invention manufactured according to the invention schematically in a plan view, Fig. 4 shows a further embodiment of a rotor lamination according to the invention manufactured according to the invention schematically in a plan view, and Fig. 5 shows a further embodiment of a rotor lamination according to the invention manufactured according to the invention schematically in a plan view.

[0021] The Fig. 1The rotor lamination 10 according to the invention shown has a substantially circular cross-sectional contour 20 and forms a mathematically vertical cylinder with a circular base. The outer radius of the circular base is at least one order of magnitude larger than the thickness of the cylinder. The rotor lamination 10 has a central passage 25, which extends through the rotor lamination 10 in the direction of a cylinder axis of the circular-cylindrical shape of the rotor lamination. The passage 25 is designed to pass through a rotor shaft to which the rotor lamination 10 can be connected.

[0022] The rotor lamination 10 comprises a first material 30, which is formed from soft magnetic pure iron. The first material 30 has grooves 40 on each of its two opposite circular sides, within which a second material 50 is located. In the illustrated embodiment, the second material 50 is made of steel, which has a significantly higher mechanical tensile strength than pure iron. The second material 50 is flat and flush with the first material 30 on the circular sides of the rotor lamination 10.

[0023] The second material 50 of the rotor lamination 10 according to the invention surrounds the passage 25 in a circular ring shape and also extends radially from the passage 25 with eight spokes 60 in a star-like manner to the outer circumference of the circular cross-sectional contour 20. In principle, a different number of spokes can also be present in further exemplary embodiments not specifically shown.

[0024] In Fig. 1 In the embodiment shown, the spokes 60 formed with second material 50 extend with a constant width in a direction perpendicular to the radial direction R and parallel to the annular sides of the rotor sheet 10. In Fig. 3 In the illustrated embodiment of a rotor lamination 310, the spokes 70 can also taper in the radial direction.

[0025] In Fig. 4In the illustrated embodiment of a rotor lamination 410, in addition to the spokes 70 tapering in the radial direction R as shown in Fig. 3 shown also several, in the representation acc. Fig. 4 three concentric rings 80 made of second material, which are also located in grooves 40 of the first material 30.

[0026] According to the invention, the Figures 1 to 4 The rotor laminations 10, 310, 410 shown are manufactured by first producing the first material 30 as a green part by screen and / or stencil printing. The green part is formed from the first material 30 in such a way that it has grooves 40. The second material 50 is then introduced into these grooves 40 by spraying. Subsequently, the first material 30 and the second material 50 are sintered together.

[0027] In principle, in further embodiments not specifically shown, the first material 30 can be manufactured as a green part by means of tape casting and / or by means of slip casting and / or by means of punching and / or water jet cutting and / or hot stamping and / or binder jetting and / or by means of additive manufacturing.

[0028] In further embodiments not specifically shown, the second material 50 can be applied to the first material by roll coating or by one of the manufacturing methods mentioned in the previous paragraph with regard to the first material 30.

[0029] In principle, in further exemplary embodiments not specifically illustrated, the first material 30 and the second material 50 can each be manufactured as a green part. Subsequently, the second material 50 is introduced into grooves 40 of the first material 30, and the first material 30 and the second material 50 are sintered together.

[0030] In the Fig. 5 In the exemplary embodiment shown, in addition to the first soft magnetic material and the second material with a higher tensile strength of the first material, a third material 120 is also present, wherein the third material 120 forms a non-magnetic support structure of the rotor lamination 510. The first material 30 and the third material 120 form a two-component magnetic lamination 520, in which the second material 50 represents additional stabilization of the two-component magnetic lamination 520. In the rotor lamination 510, the two-component magnetic lamination 520 thus replaces the first material 30 of the previously described exemplary embodiments.

Claims

1. Rotor lamination (10, 310, 410, 510) having at least a first material (30) and a second material (50), in which the first material (30) is at least partially soft magnetic and the second material (50) has a higher mechanical tensile strength than the first material (30), and in which the rotor lamination (10, 310, 410, 510) has a circular geometry and / or rotational symmetry and the second material forms radially extending struts (60, 70) which taper in the radial direction (R), in particular at a radially outer end, and in which the first material (30) has grooves (40) within which the second material is located, characterised in that the first and the second material (50) are connected to one another with a material bond, sintered to one another.

2. Rotor lamination (10, 310, 410, 510) according to claim 1, in which the first material (30) is pure iron and / or the second material (50) is a steel.

3. Rotor lamination according to one of the preceding claims, in which the first material (30) and the second material (50) differ from one another in respect of their coefficients of thermal expansion by no more than 10 · 10-6 / K, preferably by no more than 5 · 10-6 / K, suitably by no more than 2 · 10-6 / K, ideally by no more than 1 · 10-6 / K.

4. Rotor lamination according to one of the preceding claims, in which the first (30) and second material (50) are connected to one another with a positive fit.

5. Rotor lamination according to one of the preceding claims, in which the second material (50) is disposed on both sides of the first material (30).

6. Method for manufacturing a rotor lamination according to one of the preceding claims, in which the first (30) and the second material (50) are connected to one another with a material bond, wherein firstly, the first material (30) is produced as a green part and the second material (50) is produced as a green part, and thereafter first (30) and second material (50) are connected to one other with a positive fit, in particular laminated, and subsequently co-sintered.

7. Manufacturing method according to the preceding claim, in which the first material (30) is initially produced as a green part and subsequently the second material (50) is applied to the first material (30) and the first (30) and second material (50) are then co-sintered, or the second material (50) is initially produced as a green part and subsequently the first material (30) is applied to the second material (50) and then the first (30) and second material (50) are co-sintered.

8. Method according to one of the preceding claims, in which the green part or parts is / are produced by means of tape casting and / or by means of screen and / or stencil printing and / or by means of slip casting and / or by means of punching and / or water jet cutting and / or hot stamping and / or binder jetting and / or by means of additive manufacturing.

9. Method according to one of the preceding claims, in which one of first (30) and second material (50) is applied to another of first (30) and second material (50) by means of tape casting and / or by means of screen and / or stencil printing and / or by means of slip casting and / or by means of punching and / or water jet cutting and / or hot stamping and / or binder jetting and / or by means of additive manufacturing and / or by means of spraying and / or roll coating.

10. Electric machine, in particular a motor and / or generator, having a rotor lamination (10, 310, 410, 510) as claimed in one of claims 1-5.