Motor core manufacturing method

Abstract

To realize a manufacturing method of a motor core capable of securing sufficient fastening force of caulking even when an electrical steel is thin.SOLUTION: In a manufacturing method of a motor core, when a caulking part (11) for caulking and fastening an electrical steel (100) is formed, the caulking part (11) has a caulking straight part (11a), a caulking taper part (11b) arranged on both sides of the caulking straight part (11a), and a caulking shoulder part (11c) that is a step part between a plane part (12) of another area with respect to the caulking part (11) and an end part of the caulking taper part (11b). When a board thickness of the plane part (12) is supposed to be T, a height of the caulking shoulder part (11c) is supposed to be A, and a height of the caulking straight part (11a) is supposed to be B, following equations 1 to 3 are satisfied. B-A≤T...(equation 1) 0.9T≤B≤1.2T...(equation 2) 0<A≤0.2T...(equation 3)SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a motor core, for example, a method for manufacturing a motor core by stacking electromagnetic steel sheets. [Background technology]

[0002] The electromagnetic steel sheets that form the motor core may be crimped together in a stacked state, as disclosed in Patent Document 1. In such cases, the motor core manufacturing method of Patent Document 1 applies a force to the crimped portion that has a component directed from the center of the motor core toward the outer periphery, thereby reducing the effect of compressive stress that occurs in the yoke portion of the motor core due to shrink fitting. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6779565 Summary of the Invention [Problem to be solved by the invention]

[0004] The present applicant has discovered the following problem: When the electromagnetic steel sheet is thin, it is necessary to ensure the depth of the crimped portion in order to ensure the crimping fastening force while suppressing fracture of the peripheral edge of the crimped portion. However, with the motor core manufacturing method of Patent Document 1, when the crimped portion is formed while suppressing fracture of the peripheral edge of the crimped portion, the depth of the crimped portion is shallow, and there is a possibility that sufficient crimping fastening force cannot be ensured.

[0005] The present disclosure has been made in consideration of such problems, and provides a manufacturing method for a motor core that can ensure sufficient crimping fastening force even when the electromagnetic steel sheets are thin. [Means for solving the problem]

[0006] A method for manufacturing a motor core according to one aspect of the present disclosure is a method for manufacturing a motor core by stacking electromagnetic steel sheets, the method comprising: When forming a caulking portion for caulking and fastening the electromagnetic steel sheet, the caulking portion includes a caulking straight portion, caulking taper portions disposed on both sides of the caulking straight portion, and a caulking shoulder portion which is a step portion between the flat portion in another region and the end of the caulking taper portion with respect to the caulking portion. When the plate thickness of the flat portion is T, the height of the caulking shoulder portion with respect to the flat portion is A, and the height of the caulking straight portion with respect to the flat portion is B, the following (Formula 1) to (Formula 3) are satisfied. B - A ≤ T ··· (Formula 1) 0.9T ≤ B ≤ 1.2T ··· (Formula 2) 0 < A ≤ 0.2T ··· (Formula 3)

[0007] In the above method for manufacturing a motor core, it is preferable that the plate thickness of the flat portion is 0.1 mm or less.

[0008] In the above method for manufacturing a motor core, the clearance between the caulking punch and the die for forming the caulking portion is preferably 0.03T or more and 0.1T or less.

[0009] In the above method for manufacturing a motor core, the electromagnetic steel sheet is preferably an Fe - Co alloy.

Advantages of the Invention

[0010] According to the present disclosure, a method for manufacturing a motor core capable of ensuring sufficient caulking fastening force even when the electromagnetic steel sheet is thin can be realized.

Brief Description of the Drawings

[0011] [Figure 1] It is a perspective view schematically showing a state of caulking and fastening an electromagnetic steel sheet. [Figure 2] It is a cross - sectional view schematically showing a state of forming a caulking portion on a workpiece. [Figure 3] It is a different cross - sectional view schematically showing a state of forming a caulking portion on a workpiece. [Figure 4]FIG. 4 is a cross-sectional view schematically showing a fastening state of a crimped portion when electromagnetic steel sheets are stacked. [Figure 5] 10 is a different cross-sectional view schematically showing the fastening state of the crimped portion when the electromagnetic steel sheets are stacked. FIG. [Figure 6] FIG. 10 is a diagram showing the relationship between the crimping depth, the fastening force, and the defect rate. DETAILED DESCRIPTION OF THE INVENTION

[0012] Specific embodiments to which the present disclosure is applied will be described in detail below with reference to the drawings. However, the present disclosure is not limited to the following embodiments. In addition, the following description and drawings have been simplified as appropriate for clarity of explanation.

[0013] <Embodiment> First, a brief description will be given of the manufacturing method of the motor core of this embodiment. The manufacturing method of the motor core of this embodiment is suitable for manufacturing, for example, a stator core or rotor core of a motor, and involves crimping electromagnetic steel sheets as core pieces. In particular, the manufacturing method of the motor core of this embodiment is suitable for manufacturing a motor core using a sheet-shaped workpiece made of an Fe-Co alloy with a thickness of 0.1 mm or less.

[0014] Fig. 1 is a perspective view that schematically shows how electromagnetic steel sheets are crimped together. Fig. 1 shows a simplified view of the area around the crimped portion of electromagnetic steel sheet 100. A method for manufacturing a motor core sequentially performs, for example, a punching process in which a workpiece is moved progressively while punching out a hole at a first predetermined position (e.g., a position corresponding to a slot, etc.) in the workpiece, a crimping process in which a crimped portion is formed at a second predetermined position in the workpiece, and a lamination process in which electromagnetic steel sheets are punched out of the workpiece while crimping the punched electromagnetic steel sheets 100 together, as shown in Fig. 1.

[0015] Next, the flow of forming the crimped portion on the workpiece by the above-mentioned crimping process and the shape of the formed crimped portion will be described. First, the configuration of the crimping device for forming the crimped portion on the workpiece will be briefly described.

[0016] 2 and 3 show a schematic diagram of forming a crimped portion on a workpiece, with FIG. 2 being a cross-sectional view of the workpiece at a position corresponding to the II-II position in FIG. 1, and FIG. 3 being a cross-sectional view of the workpiece at a position corresponding to the III-III position in FIG. 1.

[0017] Here, in the following description, for clarity, a three-dimensional (XYZ) coordinate system will be used. As shown in Figure 2, the crimping device 1 includes a stripper 2, a die 3, a crimping punch 4, and a push-up unit 5.

[0018] The stripper 2 has a through portion 2a having a peripheral shape corresponding to the peripheral shape of the crimped portion 11 formed on the workpiece 10 when viewed from the Z-axis direction. The stripper 2 is movable, for example, in the Z-axis direction.

[0019] The die 3 also has a through portion 3a whose peripheral shape corresponds to the peripheral shape of the crimped portion 11 to be formed in the workpiece 10 when viewed from the Z-axis direction. The die 3 is disposed on the negative side of the Z-axis relative to the stripper 2. At this time, when viewed from the Z-axis direction, the through portion 2a of the stripper 2 and the through portion 3a of the die 3 are disposed so as to overlap each other.

[0020] The crimping punch 4 is movable in the Z-axis direction while being passed through the through-hole 2a of the stripper 2. The end of the crimping punch 4 on the negative Z-axis side is substantially inverted trapezoidal when viewed from the X-axis direction, and is substantially rectangular when viewed from the Y-axis and Z-axis directions.

[0021] The push-up portion 5 is movable in the Z-axis direction while being passed through the through-hole 3a of the die 3. When the workpiece 10 is fed after the crimped portion 11 has been formed in the workpiece 10, the push-up portion 5 pushes the workpiece 10 up toward the + side of the Z axis via the crimped portion 11.

[0022] Next, a flow of forming the crimped portion 11 in the workpiece 10 using the above-mentioned crimping device 1 will be described. First, the fed workpiece 10 is sandwiched between the stripper 2 and the die 3. Next, the crimping punch 4 is moved toward the negative Z-axis, and the negative Z-axis portion of the crimping punch 4 protrudes from the stripper 2 toward the negative Z-axis, pressing the workpiece 10 into a second predetermined position, thereby forming the crimped portion 11 in the workpiece 10.

[0023] At this time, since the end portion of the Z-axis negative side of the crimping punch 4 is approximately inverted trapezoidal, as shown in Figure 2, the crimping portion 11 has a crimping straight portion 11a, a crimping tapered portion 11b, and a crimping shoulder portion 11c when viewed from the X-axis direction.

[0024] The Z-axis positive side surface and the Z-axis negative side surface of the crimped straight portion 11a are disposed approximately parallel to the XY plane as shown in Fig. 2. The crimped straight portion 11a is disposed, for example, at approximately the center of the crimped portion 11 in the Y-axis direction.

[0025] As shown in Fig. 2, the crimped tapered portions 11b are disposed on both sides of the crimped straight portion 11a in the Y-axis direction. Therefore, the surfaces of the crimped tapered portion 11b on the +Y-axis side on the +Z-axis side and the -Z-axis side are inclined surfaces that slope toward the +Z-axis side as they approach the +Y-axis side. Also, the surfaces of the crimped tapered portion 11b on the -Y-axis side on the +Z-axis side are inclined surfaces that slope toward the +Z-axis side as they approach the -Y-axis side.

[0026] 2, the crimping shoulder 11c is a step between the end of the crimping tapered portion 11b on the +Y-axis side or the -Y-axis side and the flat portion 12 of the workpiece 10 in a region other than the crimped portion 11. For example, the crimping shoulder 11c is a step between the end of the crimping tapered portion 11b on the +Y-axis side or the -Y-axis side on the +Z-axis side and the surface of the flat portion 12 of the workpiece 10 on the +Z-axis side.

[0027] Then, as shown in Fig. 2, when the plate thickness of the flat portion 12 of the workpiece 10 is T, the height of the caulking shoulder portion 11c with respect to the flat portion 12 (caulking shoulder height) is A, and the height of the caulking straight portion 11a with respect to the flat portion 12 (caulking forming depth) is B, the caulking portion 11 is formed so as to satisfy the following (Equation 1) to (Equation 3). B - A ≤ T ··· (Equation 1) 0.9T ≤ B ≤ 1.2T ··· (Equation 2) 0 < A ≤ 0.2T ··· (Equation 3)

[0028] By ensuring the caulking shoulder height in this way, while ensuring the caulking forming depth and ensuring the contact area (fastening area) between the caulking portions of adjacent electromagnetic steel sheets 100 in the Z-axis direction when caulking and fastening the electromagnetic steel sheet 100, the caulking portion 11 can be formed at the inclination angle of the caulking taper portion 11b where the periphery of the caulking portion 11 does not break.

[0029] Here, Figs. 4 and 5 schematically show the fastening state of the caulking portions when electromagnetic steel sheets are laminated. Fig. 4 is a cross-sectional view of the laminated electromagnetic steel sheets 100 at a position corresponding to the II-II position in Fig. 1, and Fig. 5 is a cross-sectional view of the laminated electromagnetic steel sheets 100 at a position corresponding to the III-III position in Fig. 1.

[0030] The convex portions formed on the Z-axis - side surface of the caulking portion 11 in the electromagnetic steel sheet 100 are fitted into the concave portions formed on the Z-axis + side surface of the caulking portion 11 in the adjacent electromagnetic steel sheet 100 on the Z-axis - side and caulked and fastened as shown in Figs. 4 and 5.

[0031] At this time, in the present embodiment, by ensuring the caulking shoulder height as described above, while ensuring the contact area between the caulking portions of adjacent electromagnetic steel sheets 100 in the Z-axis direction when caulking and fastening the electromagnetic steel sheet 100 by ensuring the caulking forming depth, the caulking portion 11 is formed at the inclination angle of the caulking taper portion 11b where the periphery of the caulking portion 11 does not break. Therefore, even if the electromagnetic steel sheet 100 is thin and a difficult-to-form material such as an Fe-Co alloy, sufficient caulking fastening force can be ensured without breaking the caulking portion 11.

[0032] Moreover, the manufacturing yield of the rotor core can be improved because the crimped tapered portion 11b can be formed at a gentle angle that does not break the periphery of the crimped portion 11. Also, the crimped portion 11 can be made smaller, and the resistance at the crimped portion 11 can be reduced.

[0033] At this time, it is preferable that the clearance C between the through portion 3a of the die 3 and the periphery of the crimping punch 4 is 0.03 T or more and 0.1 T or less. This allows the crimping punch 4 to be smoothly moved toward the negative side of the Z axis while suppressing breakage of the workpiece 10.

[0034] <Example> In the examples, as shown in Table 1, the crimping depth was changed in the range of 0.8T to 1.5T, and the crimping shoulder height was changed in the range of 0 to 0.2T, and the fastening force was measured and fracture of the crimped portion was observed.

[0035] [Table 1]

[0036] In this example, the length of the crimped portion 11 in the X-axis direction was 0.5 mm, the length of the crimped portion 11 in the Y-axis direction was 3 mm, the thickness T of the flat portion 12 of the workpiece 10 was 0.1 mm, the length of the crimped straight portion 11a in the Y-axis direction was 1 mm, and the taper height obtained by subtracting the crimp shoulder height from the crimp forming depth (i.e., the above-mentioned BA value) was 0.1 mm, which was equal to the thickness T of the flat portion 12 of the workpiece 10. In addition, the punching load of the crimping punch 4 was 200 tons, the SPM (Shots Per Minute) of the crimping punch 4 was 100, and the temperature of the crimping punch 4 was 23°C when the workpiece 10 was punched.

[0037] 6 is a diagram showing the relationship between the crimping depth, the fastening force, and the defect rate. In this example, a product was deemed to be acceptable if the crimping force was 1 N or more and no fracture occurred in the crimped portion 11.

[0038] As shown in Table 1, when the crimping depth is 0.80T, 0.81T, or 0.84T, the product does not meet the requirements for an acceptable product. Also, as shown in Table 1, when the crimping depth is 1.29T, 1.40T, or 1.50T, the product does not meet the requirements for an acceptable product.

[0039] As shown in Table 1, when the crimping depth was 1.21T, 1.22T, 1.23T, 1.30T, and 1.39T, the conditions for an acceptable product were met. However, as shown in Figure 6, when the crimping depth was greater than 1.2T, there was a possibility that the crimped portion 11 would break.

[0040] On the other hand, as shown in Table 1, when the crimping depth is 0.98T, 0.99T, 1.01T, 1.09T, 1.10T, 1.11T, 1.12T, 1.18T, or 1.20T, the conditions for an acceptable product can be met, and as shown in Figure 6, there is no possibility that the fastening of the crimped portions 11 will come loose or that the crimped portions 11 will break.

[0041] From the above, it can be seen that when the taper height obtained by subtracting the crimp shoulder height from the crimp forming depth is equal to the plate thickness T of the flat portion 12 of the workpiece 10, if the crimp forming depth is in the range of 0.9T or more and 1.2T or less, and the crimp shoulder height is in the range of greater than 0 and less than 0.2T, an acceptable product can be reliably obtained.

[0042] The present disclosure is not limited to the above-described embodiments, and can be modified as appropriate within the scope of the present disclosure. [Explanation of symbols]

[0043] 1 Crimping device 2 stripper, 2a penetration 3 die, 3a penetration 4. Crimping punch 5 Push-up section 10 Workpiece 11 Crimping part 11a Crimped straight part 11b Caulking tapered part 11c Crimped shoulder 12 Plane part 100 Electrical steel sheet A Height of the crimp shoulder relative to the flat surface B Height of the crimped straight part relative to the flat part C Clearance between the die penetration and the periphery of the crimping punch T: Plate thickness of the flat part of the workpiece

Claims

1. A method for manufacturing a motor core by laminating electromagnetic steel sheets, comprising the steps of: When a crimping portion for crimping and fastening the electromagnetic steel sheets is formed, the crimping portion comprises a crimping straight portion, crimping tapered portions disposed on both sides of the crimping straight portion, and a crimping shoulder portion which is a step portion between a flat portion of another region of the crimping portion and an end of the crimping tapered portion, When the plate thickness of the flat portion is T, the height of the crimped shoulder portion relative to the flat portion is A, and the height of the crimped straight portion relative to the flat portion is B, the following (Equation 1) to (Equation 3) are satisfied: A method for manufacturing a motor core, wherein the length of the crimped portion in the first axial direction is 0.5 mm, the length of the crimped portion in the second axial direction perpendicular to the first axis is 3 mm, the value of T is 0.1 mm, the length of the crimped straight portion in the second axial direction is 1 mm, the above-mentioned value of B-A is 0.1 mm, the punching load of a crimping punch for forming the crimped portion is 200 tons, the SPM (Shots Per Minute) of the crimping punch is 100, and the temperature of the crimping punch is 23°C, and one of the electromagnetic steel sheets is punched out. B-A≦T...(Formula 1) 0.9T≦B≦1.2T...(Formula 2) 0<A≦0.2T...(Formula 3)

2. 2. The method for manufacturing a motor core according to claim 1, wherein a clearance between a crimping punch for forming the crimped portion and a die is 0.03T or more and 0.1T or less.

3. 3. The method for manufacturing a motor core according to claim 1, wherein the electromagnetic steel sheets are made of an Fe--Co alloy.

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