Method for producing a joining composite comprising a base body and at least one sheet metal stack

Abstract

The invention relates to a method (2) for producing a joining assembly (1) with a base body (3) and at least one laminated core (4). The base body (3), the at least one laminated core (4), a solder stop material (5), and a solder material (6) are provided. The solder stop material (5) is applied to the base body (3) at at least one measuring point (13), and the solder material (6) is placed between the base body (3) and the at least one laminated core (4). Subsequently, the at least one laminated core (4) and the base body (3) are soldered together using the solder material (6). The invention also relates to the joining assembly (1) produced by the method (2).

Description

[0001] The invention relates to a method for producing a joining assembly comprising a base body and at least one sheet metal stack. The invention also relates to the joining assembly produced by the method, comprising the base body and the at least one sheet metal stack.

[0002] Axial flux machines are frequently used in vehicle manufacturing. Such an axial flux machine typically comprises a rotor with a supporting base body and a laminated core. During rotor production, the base body and the at least one laminated core are brazed together and subsequently post-processed to reduce any distortion of the joint that occurred during brazing. However, this post-processing alters the originally defined thickness of the base body and the at least one laminated core. Since the exact position of the joining plane between the at least one laminated core and the base body is no longer known after post-processing, the thickness of the base body and the thickness of the at least one laminated core are unknown. The thickness of the at least one laminated core, however, is functionally relevant for the axial flux machine.In particular, the thickness of at least one laminated core must be known to ensure smooth running and a long service life during continuous operation of the axial flux machine. Since gaps between the base body and the at least one laminated core are filled with solder during the soldering process and additionally with a lamination material after soldering, the thickness of the laminated core cannot be determined non-destructively using measurement techniques.

[0003] DE 10 2023 105 141 A1 discloses a method for manufacturing a rotor of an electric machine, comprising a rotor shaft, a first laminated core, magnets, and further laminated cores. During manufacturing, the rotor shaft is connected to the first laminated core, and then the magnets and the further laminated cores are arranged relative to the rotor shaft and the first laminated core in such a way as to reduce the predicted imbalance. For this purpose, the rotor shaft with the first laminated core, the magnets, and the further laminated cores are geometrically measured and weighed.

[0004] EP 4 456 389 A1 discloses a method for manufacturing a stator or a rotor of a radial flux machine. In the method, guide elements are fixed in slots of a laminated core of the stator or the rotor by means of fixing elements in such a way that the laminated core and the guide elements cannot be damaged when the stator or the rotor is moved during manufacturing.

[0005] DE 10 2022 201 479 A1 discloses a rotor for an electric machine. The rotor comprises a rotor shaft extending along an axial direction and having an outer circumferential surface. Furthermore, the rotor comprises a sleeve-shaped bushing body extending along the axial direction and arranged radially on the outside of the rotor shaft. The rotor also comprises a hollow cylindrical rotor lamination stack extending along the axial direction. The rotor lamination stack is also arranged radially on the outside of the bushing body. Advantageously, an outer diameter of the rotor shaft, measured perpendicular to the axial direction, has a larger overlap than an inner diameter of the sleeve-shaped bushing body, also measured perpendicular to the axial direction, by a predetermined first fit dimension.Furthermore, the outer diameter of the bushing body, measured perpendicular to the axial direction, is designed with a larger overlap value than the inner diameter of the rotor lamination stack, also measured perpendicular to the axial direction, by a predetermined second fit dimension. According to the invention, the interference of the first fit dimension is greater than the interference of the second fit dimension.

[0006] The object of the invention is therefore to provide an improved or at least alternative embodiment of a method of the generic type, in which the described disadvantages are overcome. The object of the invention is also to provide a corresponding joining compound produced by the method.

[0007] This problem is solved according to the invention by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

[0008] The method according to the invention is designed for producing a joining assembly comprising a base body and at least one laminated core. The joining assembly is, in particular, a rotor of an axial flux machine. The method includes steps a), b), c), d), and e). The sequence of these steps may deviate from that described here, as soon as it is practically feasible. In step a), the base body, the at least one laminated core, a solder stop material, and a solder material are provided. The base body has an interior open on at least one side and a joining surface arranged within this interior, and the at least one laminated core has an external joining surface. In step b), the solder stop material is applied locally to the joining surface of the base body at at least one measuring point.The solder stop material can, in particular, prevent the solder material from wetting the at least one measuring point during the soldering of the at least one laminated core and the base body. In measure c), the solder material is arranged on the joining surface of the base body and / or on the connecting surface of the at least one laminated core. In particular, the solder material can be arranged on the joining surface such that the at least one measuring point is not covered by the solder material or is free of it. In measure d), the at least one laminated core is arranged on the base body, wherein the connecting surface of the at least one laminated core is arranged facing the joining surface of the base body and the at least one measuring point is not covered by the at least one laminated core, or is free of it, at least partially. In measure e), the at least one laminated core and the base body are soldered together using the solder material.

[0009] In the method according to the invention, the joint can be produced with at least one measuring point that is not wetted by the solder material and not covered by the at least one laminated core. In particular, the solder stop material can prevent solder accumulation at the at least one measuring point during soldering, so that the joining surface of the base body remains free of solder material at the at least one measuring point even after soldering. This allows the actual thickness of the base body to be measured or recorded accurately at the at least one measuring point without distortion of the measurement by solder accumulation. Based on the recorded thickness of the base body, the thickness of the at least one laminated core can also be accurately determined or calculated. Advantageously, the determination of the thickness of the at least one laminated core can be carried out non-destructively and in a simplified manner.

[0010] In one possible embodiment of the method, measure f) can be carried out after measure e). In measure f), at least one gap formed within the interior of the base body between the base body and the at least one sheet metal stack, and which is not filled with the solder material and the solder stop material, can be filled with a lamination material or a filler material.

[0011] In one possible embodiment of the method, the joint can be post-processed in step g) after step e). If step f) is carried out in the method, step g) can be performed, in particular, after step f). Post-processing the joint can, in particular, reduce or eliminate any distortion or warping of the joint that may have occurred during soldering by removing material. Post-processing the joint can be carried out, for example, by machining.

[0012] In one possible embodiment of the method, the thickness of the at least one sheet metal stack can be determined at at least one of the measuring points, particularly non-destructively, according to measure e) in measure h). For this purpose, the total thickness of the joint can be determined, particularly at the at least one measuring point or immediately adjacent to the at least one measuring point, and the thickness of the base body can be determined at the at least one measuring point. As already described above, the joining surface of the base body remains free of the brazing material at the at least one measuring point, so that the thickness of the base body can be determined accurately and without distortion. Preferably, the thickness of the base body can be determined or measured using an ultrasonic method. This can be determined via the transit time or the speed of sound.The thickness of at least one sheet metal stack can then be determined at at least one measuring point as the difference between the total thickness of the joined assembly and the thickness of the base body at that measuring point, and a predetermined thickness of the brazing material. Advantageously, the thickness of the at least one sheet metal stack can also be measured at several measuring points.

[0013] The total thickness of the joined assembly is determined by the sum of the thicknesses of the base body, the at least one sheet metal stack, and all intervening layers. The total thickness of the joined assembly and / or the thickness of the base body and / or the thickness of the at least one sheet metal stack can be defined, in particular, perpendicular to an outer surface of the base body opposite the joining surface and / or perpendicular to an outer surface of the at least one sheet metal stack opposite the joining surface. If measure g) is carried out in the method, the outer surface of the base body may not be parallel to its joining surface and / or the outer surface of the at least one sheet metal stack may not be parallel to its joining surface. In this case, the thickness of the base body and the thickness of the at least one sheet metal stack may differ at different measuring points. However, the total thickness of the joined assembly can be constant or nearly constant.

[0014] In one possible embodiment of the method, in measure a), the base body can be made of a metallic material, preferably an iron-based material, and / or the at least one laminated core can be made of a metallic material, preferably an iron-based material. In measure a), the solder material can be provided in the form of a metallic solder, preferably a nickel-based or copper-based solder. A metallic material includes, in particular, metals and metal alloys. The solder stop material in measure a) can be provided in the form of a non-metallic material, preferably a titanium dioxide-based material. The solder stop material can, in particular, be designed such that it cannot form a metallic bond to the base body and / or to the at least one laminated core.This prevents the joining surface of the base body, which is coated with the solder stop material, from being wetted by the solder material and allows it to remain free of solder. In other words, the thickness of the base body is not altered by adhering or metallurgically bonded solder material at that point.

[0015] In one possible embodiment of the method, in measure a), the base body can be provided with an annular base, an outer wall, and an inner wall. The base can, in particular, have an outer rim and an inner rim. The outer wall can then encircle the base at its outer rim and project perpendicularly from the base. The inner wall can then encircle the base at its inner rim and project perpendicularly from the base in the same direction as the outer wall. The joining surface of the base body can be formed on the base between the outer wall and the inner wall. The interior of the base body can be annular and bounded by the base, the outer wall, and the inner wall. In measure a), the at least one sheet metal stack can be provided with an annular body and the annular joining surface formed on the annular body.In measure d), the at least one sheet metal stack can then be arranged on the base body such that a circumferential outer gap is formed between the at least one sheet metal stack and the outer wall of the base body, and a circumferential inner gap is formed between the at least one sheet metal stack and the inner wall of the base body. In measure b), the solder stop material can be arranged on the bottom of the base body adjacent to the outer wall in such a way that, according to measure d), the solder stop material is accessible from the outside via the outer gap. Alternatively or additionally, in measure b), the solder stop material can be arranged on the bottom of the base body adjacent to the inner wall in such a way that, according to measure d), the solder stop material is accessible via the inner gap. If measure f) is carried out in the process, the inner gap and / or the outer gap can be filled with the lamination material.

[0016] In one possible embodiment of the method, in measure b) the plumb stop material can be applied at least section by section in the form of a continuous line and / or a line applied segment by segment and / or a line applied point by point.

[0017] In one possible embodiment of the method, in measure b), the solder stop material can be arranged in an area located, according to measure d), between the joining surface of the at least one sheet metal stack and the joining surface of the base body. This allows, according to measure e), at least one predefined defect to be formed between the joining surface of the at least one sheet metal stack and the joining surface of the base body.

[0018] The invention also relates to a composite assembly comprising a base body and at least one laminated core. This composite assembly is particularly relevant as a rotor of an axial flux machine. According to the invention, the composite assembly is manufactured using the method described above. To avoid repetition, reference is made to the above explanations.

[0019] Further important features and advantages of the invention will become apparent from the dependent claims, the drawings and the associated description of the figures based on the drawings.

[0020] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0021] Preferred embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein identical reference numerals refer to identical or similar or functionally identical components.

[0022] They show, each schematically Fig. 1 a partial sectional view of a joining composite according to the invention after carrying out measures a), b), c) and during the execution of a measure d) of a method according to the invention; Fig. 2, Fig. 3 to Fig. 4 Top views of the joining compound according to the invention after carrying out measure d) of the method according to the invention; Fig. 5 a partial sectional view of the joining compound according to the invention after carrying out a measure e) of the method according to the invention; Fig. 6 a partial sectional view of the joining compound according to the invention after carrying out a measure f) of the method according to the invention; Fig. 7 a partial sectional view of the joining compound according to the invention after carrying out a measure g) of the method according to the invention; Fig. 8 a partial sectional view of the joining compound according to the invention after carrying out a measure h) of the method according to the invention.

[0023] Fig. Figure 1 shows a partial sectional view of a joining element 1 according to the invention during its manufacture using a method 2 according to the invention. The joining element 1 is primarily a rotor of an axial flux machine. The method 2 according to the invention comprises steps a), b), c), d), e), f), g), and h), which are carried out successively. Fig. Figure 1 shows the joint after carrying out measures a), b), c), and after carrying out measure d). The individual measures are explained in more detail below.

[0024] In measure a), a base body 3, at least one sheet metal stack 4, a solder stop material 5, and a solder material 6 are first provided. The base body 3 comprises an annular base 7 with an outer outer edge 7a and an inner inner edge 7b, an outer wall 8a, and an inner wall 8b. The outer wall 8a and the inner wall 8b project perpendicularly from the base 7 in the same direction. The outer wall 8a is formed around the outer edge 7a of the base 7, and the inner wall 8b is formed around the inner edge 7b of the base 7. An interior space 9, open on one side, is formed between the base 7, the outer wall 8a, and the inner wall 8b. The base body 3 also comprises an annular joining surface 10, which is formed on the base 7 within the interior space 9 and lies between the outer wall 8a and the inner wall 8b.The lamination stack 4 comprises a substantially ring-shaped body 11 and a substantially ring-shaped connecting surface 12 formed on the body 11. The base body 3 and the lamination stack 4 are made of a metallic material, preferably an iron-based material. The solder stop material 5 is a non-metallic material in its nature, preferably a titanium dioxide-based material. The solder material 6 is a metallic solder, preferably a nickel-based or copper-based solder.

[0025] In measure b), the solder stop material 5 is applied to the joining surface 10 of the base body 3. This defines one or more measuring points 13 in the joining assembly 1, the function of which is explained in more detail below. The solder stop material 5 can, in particular, prevent the measuring points 13 from being wetted by the solder material 6, so that the measuring points 13 remain free of the solder material 6 even after the base body 3 and the sheet metal stack 4 have been soldered together. In the example shown here, the solder stop material 5 is positioned adjacent to the outer wall 8a and the inner wall 8b on the joining surface 10 or on the base 7 of the base body 3 that forms the joining surface 10. Further details on this will be explained below. Fig. 2 to Fig. 4 explained in more detail. The solder stop material 5 does not completely cover the joining surface 10, so that a sufficiently large area of ​​the joining surface 10 is available for soldering the base body 3 to the sheet metal stack 4.

[0026] In measure c), the soldering material 6 is arranged between the base body 3 or its joining surface 10 and the sheet metal stack 4 or its connecting surface 11. The soldering material 6 can be arranged or applied to the joining surface 10 or to the connecting surface 12.

[0027] In measure d), the sheet metal stack 4 is arranged in the interior 9 of the base body 3. The connecting surface 12 of the sheet metal stack 4 is advantageously positioned facing the joining surface 10 of the base body 3. The measuring points 13 are not covered, at least partially, by the sheet metal stack 4. For this purpose, the solder stop material 5 is arranged or applied accordingly to the joining surface 10 of the base body 3 in measure b). The joining joint 1 during the execution of measure d) is shown here. After measure d), the sheet metal stack 4 with its connecting surface 12 is positioned on the solder material 6, and the solder material 6 is positioned on the joining surface 10, so that soldering of the base body 3 and the sheet metal stack 4 is possible, as shown below. Fig. 5 will be explained in more detail.

[0028] Fig. 2 to Fig. Figure 4 shows top views of the joining element 1 according to the invention after carrying out measure d) of the method 2 according to the invention. Fig. 2 to Fig. 4 In particular, a ring-shaped form of the base body 3 and a ring-shaped form of the sheet metal stack 4 are recognizable. Referring to Fig. 2. In measure b), the plumb stop material 5 can be applied continuously along the outer wall 8a and / or along the inner wall 8b. Referring to Fig. 3. In measure b), the plumb stop material 5 can be applied at points along the outer wall 8a and / or along the inner wall 8b. Referring to Fig. 4. In measure b), the plumb stop material 5 can be applied segmentally along the outer wall 8a and / or along the inner wall 8b. A combination of the application methods according to Fig. 2 to Fig. 4 is also possible.

[0029] Fig. Figure 5 shows a partial sectional view of the joining element 1 according to the invention after carrying out step e) of the method 2 according to the invention. In step e), the base body 3 and the sheet metal stack 4 are soldered together using the solder material 6. Fig. Figure 5 shows that the joint 1 has warped due to high soldering temperatures. The warping is in Fig. 5. For clarity, the illustration is exaggerated. As in Fig. As can be seen from 5, the measuring points 13 are free of the solder material 6 or of accumulation of the solder material 6.

[0030] Fig. Figure 6 shows a partial sectional view of the joining element 1 according to the invention after carrying out measure f) of the method 2 according to the invention. In measure f), an outer gap 14a formed between the sheet metal stack 4 and the outer wall 8a and an inner gap 14b formed between the sheet metal stack 4 and the inner wall 8b are filled with a lamination material 15.

[0031] Fig. Figure 7 shows a partial sectional view of the joining element 1 according to the invention after carrying out measure g) of the method 2 according to the invention. In measure g), the distortion of the joining element 1 is reduced or eliminated by post-processing - for example by means of machining.

[0032] Fig.Figure 8 shows a partial sectional view of the joining assembly 1 according to the invention during the execution of step h) of the method 2 according to the invention. In step h), a total thickness D_GES of the joining assembly 1 and a thickness D_G of the base body 3 are determined. The total thickness D_GES of the joining assembly can be measured at the measuring points 13 or immediately adjacent to the measuring points 13 in a manner known to those skilled in the art. The thickness D_G of the base body 3 can, for example, be determined by means of an ultrasonic method. The thickness D_B of the sheet metal stack 4 at the measuring points 13 is then determined as the difference between the total thickness D_GES and the thickness D_G and a predetermined or known thickness D_L of the brazing material 6. D_B=D_TOTAL−D_G−D_L

[0033] Because no solder material 6 accumulates at measuring points 13 due to the solder stop material 5, the thickness D_G can be determined accurately and without distortion caused by the accumulation of solder material 6. Consequently, the thickness D_B of the laminated core 4 can be determined non-destructively, simply, and accurately at measuring points 13 using method 2.

Claims

[1] Method (2) for producing a joining composite (1) comprising a base body (3) and at least one sheet metal stack (4), comprising the following measures: a) Providing the base body (3) which has an interior space (9) open at least on one side and a joining surface (10) arranged within the interior space (9), and the at least one sheet metal stack (4) which has an external joining surface (12), and a solder stop material (5) and a solder material (6); b) Applying the solder stop material (5) to the joining surface (10) of the base body (3) at at least one measuring point (13); c) Arranging the solder material (6) on the joining surface (10) of the base body (3) and / or on the connecting surface (12) of the at least one sheet metal stack (4); d) Arranging the at least one sheet metal stack (4) on the base body (3), wherein the connecting surface (12) of the at least one sheet metal stack (4) is arranged facing the joining surface (10) of the base body (3) and the at least one measuring point (13) is not covered at least partially by the at least one sheet metal stack (4); and e) Soldering the at least one sheet stack (4) and the base body (3) together using the solder material (6). [2] Method (2) according to claim 1, characterized by , that after measure e) in measure f) at least one with the solder material (6) unfilled gap formed within the interior (9) of the base body (3) between the base body (3) and the at least one sheet metal stack (4), is filled with a lamination material (15). [3] Method (2) according to claim 1 or 2, characterized by, that after measure e) the joining compound (1) is reworked in measure g). [4] Method (2) according to any of the preceding claims, characterized by , that after measure e) and in particular after measures f) and g) in measure h) the thickness (D_B) of the at least one sheet metal stack (4) is determined, wherein - a total thickness (D_GES) of the bonded joint (1) is determined, - a thickness (D_G) of the base body (3) at at least one measuring point (13), preferably non-destructively using an ultrasonic method; and - the thickness (D_B) of the at least one sheet metal stack (4) is determined as a difference between the total thickness (D_GES) of the joining composite (1) and the thickness (D_G) of the base body (3) at the at least one measuring point (13) and a predetermined thickness (D_L) of the solder material (6). [5] Method (2) according to any of the preceding claims, characterized by , - that in measure a) the base body (3) is made of a metallic material, preferably an iron-based material, and / or the at least one sheet metal stack (4) is made of a metallic material, preferably an iron-based material; and / or - that in measure a) the solder mask material (5) is provided in the form of a material that is non-metallic in nature, preferably a titanium dioxide-based material; and / or - that in measure a) the solder material (6) is provided in the form of a metallic solder, preferably in the form of a nickel-based solder or a copper-based solder. [6] Method (2) according to any of the preceding claims, characterized by , - that in measure a) the base body (3) is provided with an annular base (7) having an outer outer edge (7a) and an inner inner edge (7b), with an outer wall (8a) that surrounds the base (7) at its outer edge (7a) and extends perpendicularly from the base (7), and with an inner wall (8b) that surrounds the base (7) at its inner edge (7b) and extends perpendicularly from the base (7) in the same direction as the outer wall (8a), - that in measure a) the basic body (3) is provided with the joining surface (10) formed on the floor (7) between the outer wall (8a) and the inner wall (8b) and the annular interior space (9) bounded by the floor (7), the outer wall (8a) and the inner wall (8b), - that in measure a) at least one sheet metal package (4) with an annular body (11) and the annular connecting surface (12) formed on the annular body (11) is provided; - that in measure d) the at least one sheet metal stack (4) is arranged on the base body (3) such that a circumferential outer gap (14a) is formed between the at least one sheet metal stack (4) and the outer wall (8a) of the base body (3) and / or a circumferential inner gap (14b) is formed between the at least one sheet metal stack (4) and the inner wall (8b) of the base body (3). [7] Method (2) according to claim 6, characterized by , - that in measure b) the plumb stop material (5) is arranged adjacent to the bottom (7) of the base body (3) and to the outer wall (8a) in such a way that the plumb stop material (5) is accessible from the outside via the outer gap (14a) after measure d), and / or - that in measure b) the plumb stop material (5) is arranged adjacent to the bottom (7) of the base body (3) and to the inner wall (8b) in such a way that the plumb stop material (5) is accessible via the inner gap (14b) according to measure d). [8] Method (2) according to any of the preceding claims, characterized by , that in measure b) the plumb stop material (5) is applied at least section by section in the form of an uninterrupted line and / or a line applied segment by segment and / or a line applied point by point. [9] Method (2) according to any of the preceding claims, characterized by , that in measure b) the solder stop material (5) is arranged in an area arranged according to measure d) between the connecting surface (12) of the at least one sheet metal package (4) and the joining surface (10) of the base body (3), so that according to measure e) at least one defect is formed between the connecting surface (12) of the at least one sheet metal package (4) and the joining surface (10) of the base body (3). [10] Joining assembly (1) with a base body (3) and at least one sheet metal stack (4), wherein the joining assembly (1) is produced in the method (2) according to one of the preceding claims.

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