Method for molding magnetic thin plate

Abstract

The invention provides a technique capable of suppressing buckling during pressing of a bridge portion. A method for forming a magnetic thin plate, the magnetic thin plate having a plurality of openings into which a magnetic body is inserted and having a bridge portion located between a first opening and a second opening adjacent to each other, the method including: a first thickening step in which the first opening and the second opening are thickened, and a second thickening step in which the first opening and the second opening are thickened; a pressing part which clamps a first boundary part of the bridge part on the first opening part side and a second boundary part of the bridge part on the second opening part side and presses in the thickness direction of the magnetic thin plate; a second thickening step in which, after the first thickening step, a third boundary section on the first opening side smaller than the first boundary section and a fourth boundary section on the second opening side smaller than the second boundary section are sandwiched and pressed in the thickness direction; a bending step in which, after the second thickening step, the central portion of the bridge portion is pressed in one direction in the thickness direction to bend the central portion in one direction from the magnetic thin plate; and a flattening step.

Description

Technical Field

[0001] This disclosure relates to a method for forming thin sheets of magnetic materials. Background Technology

[0002] Techniques for forming thin sheets of magnetic materials used in motor rotor cores are known. Patent Document 1 describes a technique for pressing and solidifying bridging portions provided between magnet holes into which magnets are inserted. Existing technical documents Patent documents

[0003] Patent Document 1: Japanese Patent Application Publication No. 2017-085776 Summary of the Invention The problem that the invention aims to solve

[0004] When the bridging portion is wide, it may bend under pressure. Therefore, there is a need for a technology that can thicken the bridging portion over a larger area while suppressing bending. Technical means for solving problems

[0005] This disclosure was made to solve the above-mentioned problems and can be implemented in the following ways.

[0006] According to the present disclosure, a method for forming a magnetic body sheet is provided, the magnetic body sheet having a plurality of openings for inserting a magnetic body, and having a bridging portion located between adjacent first openings and second openings. The method for forming the magnetic sheet includes: a first thickening step, in which a first boundary portion on the first opening side of the bridging portion and a second boundary portion on the second opening side of the bridging portion are clamped and pressed along the thickness direction of the magnetic sheet; a second thickening step, after the first thickening step, in which a third boundary portion on the first opening side of the bridging portion with an area smaller than the first boundary portion and a fourth boundary portion on the second opening side of the bridging portion with an area smaller than the second boundary portion are clamped and pressed along the thickness direction; a bending step, after the second thickening step, in which the central portion of the bridging portion is pressed in one direction along the thickness direction to bend the central portion from the magnetic sheet in the one direction; and a flattening step, after the bending step, in which the entire surface of the bridging portion is clamped and pressed along the thickness direction to flatten the bridging portion. According to the forming method of this approach, the plate thickness is increased by the first thickening process, making it difficult to bend. Therefore, in the second thickening process, the bridging portion can be thickened over a larger area compared to the case where the thickening process is only one step.

[0007] Furthermore, this disclosure can be implemented in various ways, such as by a method of thickening a thin magnetic plate. Attached Figure Description

[0008] Figure 1 This is a diagram showing the general structure of a thin magnetic plate. Figure 2 This is a flowchart illustrating an example of the forming process. Figure 3 This is an explanatory diagram of the thickening process. Figure 4 This is an explanatory diagram of the bending and flattening processes. Detailed Implementation

[0009] A. Implementation method: Figure 1 This is a diagram showing a schematic configuration of the magnetic material sheet 100 in this embodiment. The magnetic material sheet 100 is used, for example, in the rotor core of a motor. The magnetic material sheet 100 has a plurality of openings 20 for inserting a magnetic material 10, and bridging portions 30 located between adjacent openings 20. In the bridging portions 30, the direction in which the openings 20 are arranged is also referred to as the width direction of the bridging portions 30.

[0010] Furthermore, in this disclosure, the opening 20 includes a hole-forming region for forming an opening for inserting the magnetic body 10. Additionally, the bridging portion 30 includes a bridging portion-forming region located between the hole-forming regions.

[0011] Figure 2 This is a flowchart illustrating an example of the forming process. The forming process involves pressing the bridging portion 30 with a forming apparatus 500 to solidify it. In this embodiment, this process is performed on the bridging portion forming region after a temporary opening has been formed in the hole forming region. After this process, an opening 20 is formed in the hole forming region containing the temporary opening. Hereinafter, the temporary opening will be simply referred to as opening 20, and the bridging portion forming region will be referred to as bridging portion 30.

[0012] Figure 3 and Figure 4 A simplified top view and a simplified cross-sectional view of the object area of ​​the bridging portion 30 in each step of the forming process are shown. Figure 3 The AA section shown is Figure 1 The AA section view of the magnetic thin plate 100 is a section view along the width direction of the magnetic thin plate 100. Figure 4 The BB section shown is Figure 1 The BB section of the magnetic thin plate 100 is a cross-sectional view along the length of the magnetic thin plate 100. Additionally, Figure 3 and Figure 4The black arrows shown indicate the direction of pressure.

[0013] The forming apparatus 500 includes a thickening device 200, a bending device 300, and a flattening device 400. The thickening device 200 has a first pressing part 210, a second pressing part 220, a third pressing part 230, and a fourth pressing part 240. The bending device 300 has a first clamping part 310, a first die 320, and a first punch head 330. The flattening device 400 has a second clamping part 410, a second die 420, and a second punch head 430.

[0014] First, in step S100, the thickening device 200 as follows Figure 3 As shown in (A), a "first thickening process" is performed in which the first boundary portion 31 and the second boundary portion 32 of the bridging portion 30 are clamped and pressed from two directions in the thickness direction of the bridging portion 30. The first boundary portion 31 is the region of the bridging portion 30 located on the side of the first opening 21 in the width direction of the bridging portion 30, and is the region that includes the boundary between the bridging portion 30 and the first opening 21. The second boundary portion 32 is the region of the bridging portion 30 located on the side of the second opening 22 in the other width direction of the bridging portion 30, and is the region that includes the boundary between the bridging portion 30 and the second opening 22. The first interval L1 between the boundary of the first boundary portion 31 on the side of the second boundary portion 32 and the boundary of the second boundary portion 32 on the side of the first boundary portion 31 is the size of the displacement of the bridging portion 30 within the displacement range in which the bridging portion 30 does not buckle.

[0015] The first pressing part 210 clamps the first boundary part 31 and presses it along the thickness direction of the magnetic sheet 100. The second pressing part 220 clamps the second boundary part 32 and presses it along the thickness direction of the magnetic sheet 100. That is, in the first thickening process, the thickening device 200 does not press the portion between the first boundary part 31 and the second boundary part 32 in the bridging part 30.

[0016] In step S110 (refer to) Figure 2 In the case of thickening device 200, Figure 3 As shown in (B), a "second thickening process" is performed in which the third boundary portion 33 and the fourth boundary portion 34 in the bridging portion 30 are clamped and pressed from two directions in the thickness direction of the bridging portion 30. Furthermore, the processes of step S100 and step S110 are also referred to as a "thickening process".

[0017] The third boundary portion 33 is the region on the side of the first opening 21 in the bridging portion 30, and is the region that includes the boundary between the bridging portion 30 and the first opening 21. The third boundary portion 33 is a region with an area smaller than the first boundary portion 31. The fourth boundary portion 34 is the region on the side of the second opening 22 in the bridging portion 30, and is the region that includes the boundary between the bridging portion 30 and the second opening 22. The fourth boundary portion 34 is a region with an area smaller than the second boundary portion 32.

[0018] The second interval L2 between the boundary of the third boundary portion 33 on the fourth boundary portion 34 side and the boundary of the fourth boundary portion 34 on the third boundary portion 33 side is the size within which the displacement of the bridging portion 30 is within the displacement range. Furthermore, the second interval L2 is greater than the first interval L1.

[0019] The third pressing part 230 clamps the third boundary part 33 and presses it along the thickness direction of the magnetic body plate 100. The fourth pressing part 240 clamps the fourth boundary part 34 and presses it along the thickness direction of the magnetic body plate 100.

[0020] In step S120 (refer to) Figure 2 In the bending device 300, for example Figure 4 As shown in (C), a "bending process" is performed in which the central portion 36 of the bridging portion 30 is pressed in one direction along the thickness direction, thereby bending the central portion 36 from the magnetic sheet 100 in one direction. More specifically, the two ends of the bridging portion 30 in the length direction are clamped by the first clamping part 310 and the first punch 320. The central portion 36 of the bridging portion 30, which is not clamped by the first clamping part 310 and the first punch 320, does not contact the first punch 320. The central portion 36 is pressed in one direction along the thickness direction and protruded by the first punch head 330.

[0021] In step S130 (refer to) Figure 2 In the ), the flattening device 400, for example Figure 4 As shown in (D), a "flattening process" is performed to flatten the bridging portion 30 by clamping and pressing the entire surface 37 of the bridging portion 30 from two directions in the thickness direction. More specifically, the two ends of the bridging portion 30 in the length direction are clamped by the second clamping part 410 and the second die 420. The entire surface 37 of the bridging portion 30 is disposed on the second die 420. The central portion of the bridging portion 30, which is not clamped by the second clamping part 410 and the second die 420, is pressed along the thickness direction by the second punch head 430. The flattening process preferably returns the thickness of the bridging portion 30, which has increased through the thickening process of steps S100 and S110 and the bending process of step S120, to its original thickness. In addition, in the flattening process, it is preferable to press from a direction opposite to the direction in which the bridging portion 30 is pressed in the bending process of step S120.

[0022] According to the forming method of this embodiment described above, the bridging portion 30, which has been thickened by the first thickening process, is thickened by the second thickening process. Since the plate thickness increases by the first thickening process, making it difficult to bend, the bridging portion 30 can be thickened over a larger area in the second thickening process compared to the case where the thickening process is only one step. In addition, the gap between the third pressing portion 230 and the fourth pressing portion 240, i.e., the second gap L2, can be widened without bending the bridging portion 30. Furthermore, since the bridging portion 30 can be thickened over a larger area, the tedious work of setting steps on the pad of the punching device can be omitted when forming the opening 20 in the hole forming area using a punching device after the forming process.

[0023] B. Other implementation methods: (B1) In the above embodiment, the forming process is performed on the bridging portion forming region after a temporary opening is formed in the hole forming region. However, it is not limited to this; the forming process may also be performed on the bridging portion 30 after the opening 20 is formed.

[0024] (B2) In the above embodiment, the forming process is divided into two steps: a first thickening step and a second thickening step, to thicken the bridging portion 30. However, it is not limited to this; the thickening process may also be divided into three or more steps.

[0025] (B3) In the second thickening process of the above embodiment, in addition to the third boundary portion 33 and the fourth boundary portion 34 in the bridging portion 30, the middle portion of the bridging portion 30 located between the third boundary portion 33 and the fourth boundary portion 34 may also be clamped and pressed from two directions in the thickness direction of the bridging portion 30. The interval between the third boundary portion 33 and the middle portion and the interval between the fourth boundary portion 34 and the middle portion are respectively the size of the displacement of the bridging portion 30 within the displacement range.

[0026] (B4) In the above embodiments, the bending device 300 and the flattening device 400 may be the same device. In addition, the first pressing part 310 and the second pressing part 410 may be the same device, the first punch 320 and the second punch 420 may be the same device, and the first punch head 330 and the second punch head 430 may be the same device.

[0027] This disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from its spirit. For example, technical features in the embodiments that correspond to the technical features in the various embodiments described in the "Summary of the Invention" section can be appropriately replaced or combined to solve some or all of the above-described problems or to achieve the above-described effects. In addition, technical features can be appropriately deleted as long as they are not described as essential features in this specification. Explanation of reference numerals in the attached figures

[0028] 10…Magnetic body, 20…Opening, 21…First opening, 22…Second opening, 30…Bridging part, 31…First boundary part, 32…Second boundary part, 33…Third boundary part, 34…Fourth boundary part, 36…Central part, 37…Full surface, 100…Magnetic body sheet, 200…Thickening device, 210…First pressing part, 220…Second pressing part, 230…Third pressing part, 240…Fourth pressing part, 300…Bending device, 310…First clamping part, 320…First die, 330…First punch head, 400…Clamping device, 410…Second clamping part, 420…Second die, 430…Second punch head, 500…Forming device.

Claims

1. A forming method of a magnetic thin plate having a plurality of opening portions for inserting a magnetic body, and having a bridge portion between adjacent first and second opening portions, the forming method comprising: a first thickening process of clamping a first boundary portion of the first opening portion side in the bridge portion and a second boundary portion of the second opening portion side in the bridge portion and pressing in a thickness direction of the magnetic thin plate; a second thickening process of clamping a third boundary portion of the first opening portion side in the bridge portion which is smaller in area than the first boundary portion and a fourth boundary portion of the second opening portion side in the bridge portion which is smaller in area than the second boundary portion and pressing in the thickness direction after the first thickening process; a bending process of pressing a central portion of the bridge portion in one direction in the thickness direction to bend the central portion from the magnetic thin plate in the one direction after the second thickening process; and a flattening process of clamping an entire surface of the bridge portion and pressing in the thickness direction to flatten the bridge portion after the bending process. ​ ​ ​ ​ ​

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