Motor core manufacturing method

Abstract

To provide a manufacturing method for a motor core which can improve reading precision of a display part after annealing.SOLUTION: A manufacturing method for a stator core includes: a display part forming step for forming a display part which displays identification information for identifying the stator core at one end face of the stator core; and an annealing step for annealing the stator core after the display part forming step. In the annealing step, the stator core is annealed in a state in which one end face is overlapped on a mounting face on which the stator core is placed.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a motor core.

Background Art

[0002] Patent Document 1 describes a stator core formed by laminating a plurality of iron core pieces. On the upper end surface of the stator core described in Patent Document 1, a display portion for displaying identification information of the stator core is provided. The display portion is, for example, a barcode or a two-dimensional code. By photographing the display portion as an image with a camera and performing image processing on the image, the identification information of the stator core is read.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In such a manufacturing process of the stator core, annealing is performed in order to improve the magnetic characteristics of the stator core and reduce iron loss. Here, when annealing the stator core described in Patent Document 1, the following disadvantages may occur. That is, after forming the display portion on the upper end surface of the stator core, the stator core is annealed, so that an oxide film is formed on the surface of the stator core. For this reason, there is a possibility that the reading accuracy of the display portion may decrease due to the change in the hue of the display portion caused by the oxide film.

Means for Solving the Problems

[0005] A method for manufacturing a motor core to solve the above problems is a method for manufacturing a motor core, comprising: a display unit forming step of forming a display unit on one end face of the motor core to display identification information for identifying the motor core; and an annealing step of annealing the motor core after the display unit forming step, wherein in the annealing step, the motor core is annealed with the one end face overlapping a mounting surface on which the motor core is placed.

[0006] According to this method, since the motor core is annealed with one end face on which the display unit is formed overlapping the mounting surface, the end face is less exposed to the atmospheric gas compared to when the motor core is annealed with that end face facing upwards. As a result, the formation of an oxide film on the end face is suppressed. This prevents the hue of the display unit from changing due to the oxide film. Therefore, the readability of the display unit after annealing can be improved. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a perspective view of a stator core according to one embodiment. [Figure 2] Figure 2 is a cross-sectional view showing an enlarged portion of the cross-section along line 2-2 in Figure 1. [Figure 3] Figure 3 is a flowchart showing the manufacturing procedure for the stator core shown in Figure 1. [Figure 4] Figure 4 is a cross-sectional view showing the crimping process. [Figure 5] Figure 5 is a cross-sectional view showing the display unit formation process. [Figure 6] Figure 6 is a cross-sectional view showing the annealing process. [Modes for carrying out the invention]

[0008] The following describes one embodiment in which the motor core manufacturing method is implemented as a stator core manufacturing method, with reference to Figures 1 to 6. <Stator Core 10> First, the stator core 10 of this embodiment will be described with reference to Figures 1 and 2.

[0009] Please note that in some drawings, parts of the structure may be exaggerated or simplified for the sake of clarity. As shown in Figure 1, the stator core 10 is substantially cylindrical with a central hole 10A. The stator core 10 is formed by a laminate in which multiple iron core pieces 20 made of electrical steel sheets are stacked in the axial direction of the stator core 10.

[0010] In the following explanation, the direction in which the iron core pieces 20 are stacked will simply be referred to as the stacking direction, the radial direction of the stator core 10 will simply be referred to as the radial direction, and the circumferential direction of the stator core 10 will simply be referred to as the circumferential direction.

[0011] The stator core 10 has an annular yoke 12 and a plurality of teeth 13 that extend radially inward from the yoke 12 and are formed at intervals from one another in the circumferential direction.

[0012] Between adjacent teeth 13 in the circumferential direction, slots 14 are formed that open radially inward and extend radially. The outer circumferential surface of the stator core 10 is provided with a plurality of mounting portions 15 for fixing the stator core 10 to a case of a rotating electric machine (not shown). The mounting portions 15 protrude radially outward from the yoke 12 and are spaced apart from each other in the circumferential direction. The stator core 10 of this embodiment is provided with three mounting portions 15. The mounting portions 15 have mounting holes 15a formed through them in the stacking direction. In the stator core 10 of this embodiment, one mounting hole 15a is provided for each mounting portion 15. The stator core 10 and the case are fixed by bolts (not shown) inserted through each mounting hole 15a.

[0013] A display unit 16 for displaying identification information for identifying the stator core 10 is formed on one end face 10a in the stacking direction of the stator core 10. The display unit 16 is provided on the surface of the yoke 12. The display unit 16 only needs to be able to display the identification information by a combination of light and dark patterns, and may be a one-dimensional code (barcode) or a two-dimensional code such as a QR code (registered trademark).

[0014] <Iron core piece 20> As shown in Figures 1 and 2, the core piece 20 has a plurality of first core pieces 21 that are stacked in a continuous manner, and a single second core piece 25 that is stacked on one side (the upper side in Figures 1 and 2) of the plurality of first core pieces 21.

[0015] Multiple first iron core pieces 21 have essentially the same structure. Therefore, this document will describe one first iron core piece 21, and detailed descriptions of the remaining first iron core pieces 21 may be omitted.

[0016] As shown in Figure 2, the first core piece 21 has a dowel 22 that bulges toward the second core piece 25 in the stacking direction. The dowel 22 is formed on the yoke 12 of the first core piece 21 and is provided in multiples spaced apart from each other in the circumferential direction (see Figure 1). The dowel 22 has a convex portion 22a that protrudes from one surface of the first core piece 21 and a concave portion 22b provided on the other surface of the first core piece 21 at the position where the convex portion 22a is formed. Adjacent first core pieces 21 in the stacking direction are joined together by crimping them together with the dowel 22. Specifically, adjacent first core pieces 21 in the stacking direction are joined together by the convex portion 22a of the dowel 22 of one first core piece 21 fitting into the concave portion 22b of the dowel 22 of the other first core piece 21 and crimping them together.

[0017] The second core piece 25 has holes 26 into which the convex portions 22a of the dowels 22 of the first core piece 21 adjacent to the second core piece 25 are inserted. The holes 26 are formed in the yoke 12 of the second core piece 25 and are provided in a plurality at intervals in the circumferential direction (see FIG. 1). The holes 26 are provided at positions overlapping the dowels 22 in the stacking direction. The holes 26 are rectangular in shape extending in the circumferential direction. The end face (the upper side in FIGS. 1 and 2) of the second core piece 25 forms one end face 10a of the stator core 10.

[0018] The dowels 22 and the holes 26 are provided outside the display portion 16 in the radial direction. Next, referring to FIGS. 3 to 6, the manufacturing procedure of the stator core 10 will be described. As shown in FIG. 3, the manufacturing process of the stator core 10 includes a press lamination process, a caulking process, a display portion forming process, and an annealing process.

[0019] <Press Lamination Process> First, in the press lamination process, by pressing a workpiece made of electromagnetic steel sheet with a press device not shown, a plurality of core pieces 20 are punched out from the workpiece and laminated.

[0020] The press lamination process includes a dowel forming process and a hole forming process. Both the dowel forming process and the hole forming process are performed before the punching process of punching out the core pieces 20 from the workpiece.

[0021] In the dowel forming process, by pressing the workpiece with a press device, dowels 22 are formed for each of the first core pieces 21. In the hole forming process, by pressing the workpiece with a press device, holes 26 are formed for the second core pieces 25. ​​​​​​As shown in Figure 4, in the crimping process, first, the stator core 10 is placed on the upper surface of the lower die 32. At this time, the stator core 10 is placed on the lower die 32 with its other end face 10b overlapping the upper surface of the lower die 32. Then, the upper die 31 is placed on one end face 10a of the stator core 10, i.e., the upper surface. Then, the upper die 31 is pushed toward the lower die 32, thereby pressing the stator core 10 in the stacking direction. This crimps adjacent dowels 22 in the stacking direction and inserts dowels 22 adjacent to holes 26 into holes 26 in the stacking direction (this completes the crimping process). At this time, the upper die 31 presses one end face 10a, crushing the dowels 22 that protrude outward from the holes 26 (this completes the dowel crushing process).

[0023] Thus, in this embodiment, the crimping process also serves as the dowel crushing process. <Display part forming process> As shown in Figure 5, in the display unit formation process, first, one end face 10a of the stator core 10 is brought into contact with the output unit 41 of the laser device 40. Then, the laser is irradiated onto the end face 10a from the output unit 41 to form the display unit 16 on the end face 10a.

[0024] <Annealing process> As shown in Figure 6, in the annealing process, first, the stator core 10 is placed on the mounting surface 52a of the plate 52. The mounting surface 52a of the plate 52 is larger than one end face 10a of the stator core 10. Furthermore, it is preferable that the plate 52 be made of stainless steel, for example. At this time, the stator core 10 is placed with the entire end face 10a overlapping the mounting surface 52a.

[0025] Next, the conveying device 60 transports the plate 52 on which the stator core 10 is placed into the heating furnace 50. The conveying device 60 includes an endless belt 61 and a rotating shaft 62 that drives the endless belt 61.

[0026] The endless belt 61 is a mesh made of stainless steel. The inside of the heating furnace 50 is filled with a high-temperature atmospheric gas. The atmospheric gas is a low-dew-point DX gas, which is produced, for example, by incomplete combustion of city gas and dehumidification treatment.

[0027] The stator core 10 is annealed by being transported through the heating furnace 50 by the transport device 60. Thus, in the annealing process, the stator core 10 is annealed with one end surface 10a overlapping the mounting surface 52a on which the stator core 10 is placed.

[0028] Next, the operation of this embodiment will be described. The stator core 10 is annealed with one end face 10a of the stator core 10 on which the display unit 16 is formed superimposed on the mounting surface 52a. In this case, compared to annealing the stator core 10 with one end face 10a facing upward, the one end face 10a is less exposed to the atmospheric gas. As a result, the formation of an oxide film on the one end face 10a is suppressed. This prevents the hue of the display unit 16 from changing due to the oxide film.

[0029] Next, the effects of this embodiment will be described. (1) In the annealing process, the stator core 10 is annealed with one end surface 10a overlapping the mounting surface 52a on which the stator core 10 is placed.

[0030] This method achieves the above-mentioned effect, thereby improving the reading accuracy of the display unit 16 after annealing. (2) In the display section formation process, the display section 16 is formed on the end face 10a of the second iron core piece 25.

[0031] With this configuration, the stator core 10 can be realized as a laminate formed by stacking multiple first core pieces 21 and one second core piece 25, which constitutes one end face 10a of the stator core 10 and on which the display section 16 is formed.

[0032] In the crimping process, dowels 22 adjacent to each other in the stacking direction are crimped together, and dowels 22 adjacent to holes 26 in the stacking direction are fitted into holes 26, thereby forming the stator core 10.

[0033] Incidentally, when the stator core 10 is annealed, the multiple first core pieces 21 and second core pieces 25 attempt to undergo thermal deformation. However, since the first core pieces 21 are crimped together by dowels 22, the thermal deformation of their teeth 13 is restricted.

[0034] On the other hand, the second core piece 25 constitutes one end face 10a of the stator core 10, and since the dowel 22 of the adjacent first core piece 21 is simply fitted into the second core piece 25, there is a risk that the teeth 13 may warp due to thermal deformation.

[0035] In this regard, according to the above method, the stator core 10 is annealed in the annealing process with the second core piece 25 sandwiched between the mounting surface 52a and the first core piece 21. Therefore, the warping of the teeth 13 of the second core piece 25 during annealing can be suppressed.

[0036] (3) Before the annealing process, the dowel 22 protruding out of the hole 26 is pressed and crushed in the crimping process. In some cases, the dowel 22 of the first core piece 21 may protrude outward from the hole 26 of the second core piece 25. In this case, when the one end face 10a of the stator core 10 is placed on top of the mounting surface 52a, that is, when the second core piece 25 is placed on top, the tip of the dowel 22 comes into contact with the mounting surface 52a, creating a gap between the one end face 10a and the mounting surface 52a. As a result, during the annealing process, atmospheric gas enters the gap, making it easier for an oxide film to form on the one end face 10a.

[0037] In this regard, according to the above method, during the crimping process, the dowel 22 protruding outward from the hole 26 of the second iron core piece 25 is pressed and crushed. As a result, a gap is less likely to form between the one end surface 10a and the mounting surface 52a, and thus the formation of an oxide film on the one end surface 10a can be suppressed.

[0038] (4) In the annealing process, the stator core 10, which is placed on the plate 52, is transported by a mesh-like endless belt 61 inside the heating furnace 50. By using a conveying device 60 having a mesh-like endless belt 61, the endless belt 61 can be heated and cooled quickly.

[0039] However, if the stator core 10 is placed directly on the conveying surface 61a of the endless belt 61, there is a risk that the mesh shape of the endless belt 61 will be transferred to the high-temperature stator core 10. In this regard, with the above configuration, the stator core 10 is placed on the conveying surface 61a of the endless belt 61 via the stainless steel plate 52, thus avoiding the occurrence of the aforementioned problems.

[0040] <Example of changes> This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0041] • In this embodiment, a method is shown in which the crimping process also serves as the dowel crushing process, but the crimping process and the dowel crushing process may be performed as separate processes. In this embodiment, the press lamination process, the crimping process, and the display unit formation process are performed in order, but for example, the crimping process may be performed after the display unit formation process.

[0042] In this embodiment, the stator core 10 is positioned such that the second core piece 25 is located at the upper end during the crimping process, but the stator core 10 may also be positioned such that the second core piece 25 is located at the lower end.

[0043] In this embodiment, the display section 16 is provided on the second core piece 25, but the display section 16 may also be provided on the end face of the first core piece 21. In this case, during the annealing process, the stator core 10 should be annealed with the other end face 10b on which the display section 16 is provided superimposed on the mounting surface 52a.

[0044] In this embodiment, the annealing process was performed using a conveying device 60 having a mesh-like endless belt 61, but a conveying device 60 having a sheet-like endless belt without a mesh can also be used. In this case, the plate 52 can be omitted.

[0045] The present invention can also be embodied as a method for manufacturing a rotor core. [Explanation of symbols]

[0046] 10… Stator core 10A…Center hole 10a...One end surface 10b...Other end surface 12… York 13... Teeth 14…Slot 15…Mounting part 15a...Mounting hole 16…Display section 20… Iron core piece 21…First iron core piece 22... Double 22a... protruding part 22b…recess 25...Second iron core piece 26…hole 31...Upper mold 32…Lower mold 40…Laser device 41…Output section 50...Heating furnace 52... Plate 52a... Mounting surface 60…Conveyor device 61... Endless belt 61a... Conveying surface 62…Rotation axis

Claims

1. A method for manufacturing a motor core, A display unit forming step involves forming a display unit on one end face of the motor core to display identification information for identifying the motor core, The process includes an annealing step in which the motor core is annealed after the display unit forming step, In the annealing process, the motor core is annealed with one end face overlapping the mounting surface on which the motor core is placed. A method for manufacturing a motor core.

2. Prior to the display unit forming step, the process includes a press lamination step in which a workpiece is pressed to punch out multiple iron core pieces from the workpiece and then laminated. The plurality of iron core pieces include a plurality of first iron core pieces that are stacked in a continuous manner, and a single second iron core piece that is stacked on one side of the plurality of first iron core pieces. The press lamination process includes a dowel forming step for each of the first core pieces, which forms a dowel that bulges toward the second core piece in the lamination direction of the core pieces, and a hole forming step for the second core piece, into which the dowel of the first core piece adjacent to the second core piece is fitted. The process is followed by a crimping step in which dowels adjacent to each other in the lamination direction are crimped together, and dowels adjacent to each other in the lamination direction are fitted into the holes. In the display portion forming step, the display portion is formed on the end face of the second iron core piece as one end face. A method for manufacturing a motor core according to claim 1.

3. Prior to the annealing process, a dowel crushing process is provided in which the dowel protruding from the hole is pressed and crushed. A method for manufacturing a motor core according to claim 2.

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