Magnetic body thin sheet producing method

Abstract

To provide a magnetic body thin sheet producing method by which bending of a magnetic body thin sheet can be restrained.SOLUTION: A production method for a magnetic body thin sheet 1 according to the present disclosure includes a bending step of bending a bridge portion B of the magnetic body thin sheet 1 in the length direction of the bridge portion B, a thickening step of thickening a center portion of the bridge portion B in the width direction by pressing both ends of the bridge portion B in the width direction in a state where both ends of the bridge portion B in the length direction are locked, and a crushing step of crushing the thickened portion formed in the thickening step to have the original thickness by pressing the thickened portion in a state where both ends of the bridge portion B in the length direction are locked.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a thin magnetic plate.

Background Art

[0002] Patent Document 1 discloses the structure of a rotor core formed by laminating a plurality of thin magnetic plates. In the rotor core structure disclosed in Patent Document 1, a bridge pressing portion is formed on a bridge portion provided on the thin magnetic plate. Further, on the extension line in the longitudinal direction of the bridge portion, a protruding portion protruding in the direction opposite to the depression direction of the bridge pressing portion is formed. The protruding portion absorbs the force that tends to extend in the radial direction of the thin magnetic plate and suppresses the warping of the thin magnetic plate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the rotor core structure disclosed in Patent Document 1, since the thin magnetic plate has a protruding portion, there is a risk that the strength of the thin magnetic plate may decrease due to buckling or the like of the protruding portion. As a solution to such a problem, a method of processing the thin magnetic plate into a flat shape by crushing the protruding portion using a punch can be considered.

[0005] For example, first, the bridge portion is built up to work-harden the bridge portion. Thereby, the strength of the bridge portion is improved. Next, one surface of the built-up bridge portion is pressed by a punch to project the bridge portion from the magnetic thin plate. Thereby, a projecting portion is formed on the bridge portion. By doing so, the force that tries to extend in the radial direction of the magnetic thin plate in the bridge portion is eliminated, so that the warping of the magnetic thin plate is suppressed. Then, the other surface of the projecting portion is pressed by a punch to crush the projecting portion, thereby processing the magnetic thin plate into a flat shape. Thereby, since the projecting shape of the magnetic thin plate is eliminated, the strength of the magnetic thin plate is improved. By using the method as described above, it is possible to suppress the warping of the magnetic thin plate while improving the strength of the bridge portion.

[0006] However, when such a method is used, since there is a gap between the punch and the thin-walled portion around the projecting portion, it is difficult to sufficiently crush the bending of the magnetic thin plate. If the bending cannot be sufficiently crushed, minute undulations remain in the product, which may interfere during the lamination of the magnetic thin plates to form gaps, and the strength of the magnetic thin plates may decrease.

[0007] An object of the present disclosure is to provide a method for manufacturing a magnetic thin plate capable of reducing the bending of the magnetic thin plate in view of the above-described problems.

Means for Solving the Problems

[0008] A method for manufacturing a magnetic thin plate according to the present disclosure is a method for manufacturing a magnetic thin plate that forms a rotor core, and includes a bending step of bending a bridge portion included in the magnetic thin plate in a length direction of the bridge portion, a bulking step of pressing both end portions in a width direction of the bridge portion while restraining both end portions in the length direction of the bridge portion to bulk up a central portion in the width direction of the bridge portion, and a crushing step of pressing a bulking portion formed in the bulking step while restraining both end portions in the length direction of the bridge portion to crush the bulking portion to an original thickness.

Effects of the Invention

[0009] According to the present disclosure, it is possible to provide a method for manufacturing a thin magnetic plate capable of reducing the bending of the thin magnetic plate.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are denoted by the same reference numerals. For the sake of clarity of explanation, duplicate explanations are omitted as necessary.

[0012] (Configuration of the thin magnetic plate) FIG. 1 is a plan view showing the configuration of a thin magnetic plate 1 manufactured using the method for manufacturing a thin magnetic plate according to the present embodiment. The right-handed xyz orthogonal coordinates shown in FIG. 1 and other drawings are for convenience in explaining the positional relationship of the components. Usually, the positive direction of the z-axis is vertically upward, the xy plane is a horizontal plane, and is common among the drawings.

[0013] The thin magnetic plate 1 according to the present embodiment is a thin magnetic plate forming a rotor core of a motor. The thin magnetic plate 1 is, for example, a disk-shaped thin plate. The thin magnetic plate 1 may be, for example, a steel plate. The thin magnetic plate 1 forms a rotor core by being laminated in a plurality of sheets in the z-axis direction. In the thin magnetic plate 1, a configuration including magnet holes 11a, 11b, and 11c, magnetic flux leakage suppression holes 12a, 12b, and 12c, and a bridge portion B is repeated, for example, 8 times along the circumferential direction of the thin magnetic plate 1.

[0014] The magnet holes 11a are provided along the circumferential direction at the outer edge of the thin magnetic plate 1. The magnet holes 11b and 11c are provided along the radial direction on both sides of the magnet hole 11a. Permanent magnets are inserted into the magnet holes 11a, 11b, and 11c respectively during the formation of the rotor core and sealed with resin. The magnetic flux leakage suppression holes 12a and 12b are adjacent to both ends of the magnet hole 11a. The magnetic flux leakage suppression hole 12c is provided between the inner circumferential side ends of the magnet holes 11b and 11c. The magnetic flux leakage suppression holes 12a, 12b, and 12c suppress the leakage of magnetic flux from the permanent magnets provided in the magnet holes 11a, 11b, and 11c during the formation of the rotor core.

[0015] The bridge portions B are provided between the magnetic flux leakage suppression hole 12c and the magnet hole 11b, and between the magnet hole 11c and the magnetic flux leakage suppression hole 12c respectively at both circumferential ends of the magnetic flux leakage suppression hole 12c. The bridge portions B are provided so as to extend in the x-axis direction, that is, the radial direction of the thin magnetic plate 1. The bridge portions B reinforce the strength of the rotor core. The length direction of the bridge portions B is parallel to the x-axis, and the width direction is parallel to the y-axis.

[0016] (Manufacturing method of the thin magnetic plate) With reference to FIGS. 2 and 3, the manufacturing method of the thin magnetic plate 1 will be described. FIG. 2 is a flowchart showing the flow of the manufacturing method of the thin magnetic plate 1. The manufacturing method of the thin magnetic plate 1 according to the present embodiment includes a bending step (S1), a thickening step (S2), and a pressing step (S3).

[0017] FIG. 3 is a diagram for explaining each step of the flowchart shown in FIG. 2. FIGS. 3(1) to (3) correspond to the bending step, the thickening step, and the pressing step shown in FIG. 2 respectively. The left columns of FIGS. 3(1) to (3) are cross-sectional views in the width direction of the bridge portion B, and the right columns are cross-sectional views in the length direction of the bridge portion B. For example, the left column is a cross-sectional view when cut in the yz plane passing through the center in the length direction of the bridge portion B. The right column is a cross-sectional view when cut in the zx plane passing through the center in the width direction of the bridge portion B.

[0018] Figure 3 shows the punches P1 to P3, the plate holders A1 to A3, and the dies D1 to D2 of the press device that performs the manufacturing method according to the present embodiment, together with a cross-sectional view of the bridge portion B. The punches P1 to P3 are punches for processing the bridge portion B. The plate holders A1 to A3 are members for fixing the magnetic thin plate 1. The dies D1 and D2 are members for supporting the magnetic thin plate 1.

[0019] (Bending process) First, in the bending process of step S1, the bridge portion B provided in the magnetic thin plate 1 is bent in the length direction of the bridge portion B. Specifically, the plate holders A1 and the die D1 sandwich and fix both ends in the length direction of the bridge portion B. Thereby, the plate holders A1 and the die D1 restrain both ends in the length direction of the bridge portion B. The punch P1 presses the bridge portion B in the negative z-axis direction and bends the bridge portion B.

[0020] Note that both ends in the length direction of the bridge portion B are portions located at both ends in the length direction of the bridge portion B. Both ends in the length direction of the bridge portion B are in contact with the central portion in the length direction of the bridge portion B. The central portion in the length direction of the bridge portion B is a portion located at the center in the length direction of the bridge portion B. The central portion in the length direction of the bridge portion B is in contact with both ends in the length direction of the bridge portion B. The lengths of both ends and the central portion in the length direction may be appropriately set based on the dimensions, materials, etc. of the bridge portion B. Also, both ends and the central portion in the width direction of the bridge portion B may be set in the same manner as described above. By replacing the "length direction" in the above description with the "width direction", both ends and the central portion in the width direction of the bridge portion B can be set.

[0021] (Incremental process) Next, in the thickening process of step S2, while restraining both end portions in the length direction of the bridge portion B, both end portions in the width direction of the bridge portion B are pressed, and the central portion in the width direction of the bridge portion B is thickened. Specifically, the plate presser A2 sandwiches and fixes both end portions in the length direction of the bridge portion B from the positive and negative directions of the z-axis. Thereby, the plate presser A2 restrains both end portions in the length direction of the bridge portion B. The punch P2 presses both end portions in the width direction of the bridge portion B from the positive and negative directions of the z-axis. Thereby, the punch P2 crushes both end portions in the width direction of the bridge portion B.

[0022] By crushing both end portions in the width direction of the bridge portion B, the bending of the bridge portion B is reduced, and the thickness of the central portion in the width direction of the bridge portion B increases. That is, the central portion in the width direction of the bridge portion B is thickened, and a thickened portion is formed. By thickening the central portion in the width direction of the bridge portion B in this way, the bridge portion B can be work-hardened. Thereby, the strength of the bridge portion B is improved.

[0023] (Crushing process) Then, in the crushing process of step S3, while restraining both end portions in the length direction of the bridge portion B, the thickened portion formed in the thickening process is pressed, and the thickened portion is crushed back to the original thickness. Specifically, the plate presser A3 and the die D2 sandwich and fix both end portions in the length direction of the bridge portion B from the positive and negative directions of the z-axis. Thereby, the plate presser A3 and the die D2 restrain both end portions in the length direction of the bridge portion B. The punch P3 presses the thickened portion located at the central portion in the width direction of the bridge portion B from the positive direction of the z-axis. Thereby, the punch P3 crushes the thickened portion and returns the thickened portion to the original thickness. The original thickness is the thickness of the central portion in the width direction of the bridge portion B before thickening. Note that it is not required that the thickness of the bridge portion B after the crushing process exactly matches the thickness of the original bridge portion B, and it is sufficient that the thickened portion is thinned to such an extent that the two can be regarded as the same.

[0024] The distance between both ends in the length direction of the bridge portion B is shortened in the bending process and increases in the thickening process and the pressing process. In the thickening process and the pressing process, the increase in the distance can be suppressed by using the plate holders A2 and A3. By offsetting the shortening in the bending process and the increase in the thickening process and the pressing process of the said distance to be equal, warping of the core plate can be prevented.

[0025] As described above, the method for manufacturing the magnetic thin plate 1 according to the present embodiment includes a bending process, a thickening process, and a pressing process. In the manufacturing method according to the present embodiment, since the magnetic thin plate 1 is manufactured in the order of the bending process, the thickening process, and the pressing process, after bending the bridge portion B in the length direction in the bending process, both ends in the width direction of the bridge portion B and the thickening portion are pressed. Thereby, warping of the magnetic thin plate 1 can be reduced and bending of the magnetic thin plate 1 can be reduced.

[0026] Note that the present disclosure is not limited to the above embodiment, and can be appropriately changed without departing from the gist.

Explanation of reference numerals

[0027] 1 Magnetic thin plate 11a~11c Magnet holes 12a~12c Magnetic flux leakage suppression holes A1~A3 Plate holders B Bridge portion D1, D2 Dies P1~P3 Punches

Claims

【Claim 1】 A method for manufacturing a thin magnetic plate forming a rotor core, a bending step of bending a bridge portion provided in the thin magnetic plate in the length direction of the bridge portion, a thickening step of pressing both end portions in the width direction of the bridge portion while restraining both end portions in the length direction of the bridge portion to thicken the central portion in the width direction of the bridge portion, and a crushing step of pressing the thickened portion formed in the thickening step while restraining both end portions in the length direction of the bridge portion to crush the thickened portion to the original thickness. A method for manufacturing a thin magnetic plate.

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