Laminated core

Abstract

To provide a stacked core that suppresses the generation of NV when a motor is operating while increasing a binding force between steel sheets.SOLUTION: The laminated core is formed by laminating steel sheets. A steel sheet 2 includes a caulking portion 11 that has a first spherical head part 21 formed in a convex-concave shape on a plate surface of the steel sheet by being pressed in a laminating direction and a second spherical head part 22 formed in a convex-concave shape on the plate surface of the steel plate at a position close to the first spherical head part 21 by being pressed in the laminating direction which is the same direction as that of the first spherical head part 21. On the caulking portion 11 in the steel sheet 2, a portion of a deformation in the laminating direction that occurs when forming the first spherical head part 21 and a portion of a deformation in the laminating direction that occurs when forming the second spherical head part 22 overlap each other.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to laminated cores. [Background technology]

[0002] In recent years, laminated cores have been used in rotors and stators used in motors. These laminated cores are made by laminating multiple steel plates together by crimping them together. Patent Document 1 describes crimping a stator, and the crimp shape is a simple flat extrusion shape. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-095181 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, the fastening force between steel sheets can be increased by increasing the crimp depth, but if it is too deep, part of the steel sheet may break.On the other hand, if the fastening force is weakened by making the crimp shallow, even a slight imbalance can cause gaps between the laminations, which can cause noise vibration (NV) when the motor using this laminated core is in operation.

[0005] The present disclosure provides a laminated core that increases the fastening force between steel sheets and suppresses the generation of NV during motor operation. [Means for solving the problem]

[0006] The laminated core according to the present disclosure is a laminated core formed by stacking steel plates, wherein the steel plates are provided with a crimping portion having a first ball head portion formed in an uneven shape on the plate surface of the steel plate by pressing in the stacking direction, and a second ball head portion formed in an uneven shape on the plate surface of the steel plate by pressing in the stacking direction in the same direction as the first ball head portion, in a position close to the first ball head portion, and wherein the crimping portion is such that a portion of the deformation in the stacking direction that occurs in the steel plate when forming the first ball head portion and a portion of the deformation in the stacking direction that occurs in the steel plate when forming the second ball head portion overlap each other. This makes it possible to form deep crimped portions in the stacking direction in the steel plate. Effect of the Invention

[0007] According to the present disclosure, it is possible to provide a laminated core that increases the fastening force between steel plates and suppresses the occurrence of NV during motor operation. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a top view of a laminated core according to the present disclosure. [Diagram 2] 4A to 4C are diagrams showing the shape of a crimped portion according to the present disclosure. [Diagram 3] FIG. 4 is a diagram showing the inflow and outflow directions of material in a crimping portion according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] First embodiment Hereinafter, the laminated core according to the present embodiment will be described with reference to the drawings. Fig. 1 is a top view of the laminated core 1. In other words, Fig. 1 is a view showing the steel plates 2 arranged at the ends of the laminated core 1 in the lamination direction from the viewpoint of the top surface direction. Note that the lamination direction of the laminated core 1 is the up-down direction, and may be described as the Z direction or height. The horizontal direction perpendicular to the lamination direction is the radial direction, and may be described as the XY direction.

[0010] As shown in Fig. 1, typically, a laminated core 1 has a plurality of holes for inserting the shaft core and windings, and also has a plurality of crimping portions 11 for crimping the steel plates stacked in the vertical direction together. As shown in Fig. 1, typically, the steel plate has a plurality of crimping portions 11 formed on the same circumference centered at the center of the steel plate.

[0011] Fig. 2 is a diagram showing an example of the shape of the crimped portion 11. Specifically, Fig. 2(a) is a cross-sectional view showing the crimped portion 11 and its vicinity from a radial perspective, and shows a state in which the steel sheet 2 is pressed by ball head punches 31 and 32 described later to form the crimped portion 11. Fig. 2(b) is a plan view showing the crimped portion 11 formed on the steel sheet 2 and its vicinity from a top view of the sheet surface of the steel sheet 2. Fig. 2(c) is a side view showing an outline of the entire device 3 in which the ball head punches 31 and 32 shown in Fig. 2(a) are provided.

[0012] As shown in Figures 2(a) and 2(b), the crimping portion 11 is formed such that the first ball head portion 21 and the second ball head portion 22 are close to each other. For example, as shown in Figure 2(c), the device for forming the crimping portion 11 is provided with an upper die 3a that moves up and down and a lower die 3b that is a fixed part, and the upper die 3a is provided with two ball head punches in parallel. The first ball head portion 21 and the second ball head portion 22 are pressed in the same direction at the same time toward the downward direction, which is the stacking direction, as the upper die 3a descends, and are formed in an uneven shape on the plate surface of the steel plate 2.

[0013] Since the first ball head portion 21 and the second ball head portion 22 are close to each other, the crimped portion 11 is formed in such a state that a part of the deformation in the stacking direction that occurs when the first ball head portion 21 is formed in the steel plate 2 and a part of the deformation in the stacking direction that occurs when the second ball head portion 22 is formed overlap each other. That is, a part of the periphery of the edge of the first ball head portion 21 that is closer to the second ball head portion 22 and a part of the periphery of the edge of the second ball head portion 22 that is closer to the first ball head portion 21 overlap each other.

[0014] Typically, as shown in Figure 2(a), if a specified position outside the location where the crimped portion 11 is formed is defined as part A, and the highest position in the vertical direction between the first ball head portion 21 and the second ball head portion 22 is defined as part B, parts of the unevenness changes in the Z direction caused by the formation of the first ball head portion 21 and the second ball head portion 22 overlap each other so that the height of part B is lower than the height of part A.

[0015] Here, the operation of forming the crimped portion 11 by the device provided with the ball-head punches 31, 32, and the outflow of material and the inflow of material from the surroundings that occur when the crimped portion 11 is formed will be described.

[0016] Fig. 3 is a diagram showing the direction of flow of material constituting the steel sheet 2 into and out of the crimped portion 11 when the sheet surface of the steel sheet 2 is pressed by the ball-head punches 31, 32. Fig. 3(a) is a cross-sectional view showing the crimped portion 11 and its vicinity from a radial perspective, with the movement of the material indicated by arrows, and Fig. 3(b) is a diagram showing the crimped portion 11 and its surroundings from a top view similar to Fig. 2(b), with the movement direction of the material indicated by arrows.

[0017] Here, the direction in which the first ball head portion 21 and the second ball head portion 22 are connected and which is horizontal is defined as the X direction, and the horizontal direction perpendicular to the X direction is defined as the Y direction. In the following description, point B between the first ball head portion 21 and the second ball head portion 22 is defined as the center of the steel plate 2 and is located inside the steel plate 2.

[0018] When the steel plate 2 is pressed by the ball-head punches 31, 32 to form the crimped portion 11, material flows into the crimped portion 11 from the periphery.

[0019] 3(a), when the ball head punch 31 presses the steel sheet 2, material flows into the first ball head portion 21 from direction a, which is the outer side in the X direction. Similarly, when the ball head punch 32 presses the steel sheet 2, material flows into the second ball head portion 22 from direction d, which is the outer side in the X direction.

[0020] 3(b), in the Y direction, material flows into the first ball head 21 from the outer b and f directions, and material flows into the second ball head 22 from the outer c and e directions. That is, material flows into the first ball head 21 and the second ball head 22 from the surroundings.

[0021] On the other hand, at this time, in part B, which is the position between the first ball head head 21 and the second ball head head 22, a force acts on both the first ball head head 21 side and the second ball head head 22 side, causing the material to flow, and the material is stretched in the X direction, resulting in a state of plane strain.

[0022] Furthermore, at this time, material flows toward part B from directions g and h, which are on the outer side in the Y direction at the position of part B. This flow of material in the Y direction into part B is promoted by the flow of material into first ball head part 21 from directions b and f, and the flow of material into second ball head part 22 from directions c and e.

[0023] Therefore, in part B, the material flows out in the X direction and the material flows in the Y direction.

[0024] If we only consider the plane strain in the X direction at part B, part B will be in a state where it is outside the forming limit, that is, where the thickness is reduced to the point where it may break. On the other hand, in the Y direction, material will flow from the g and h directions toward part B in an amount greater than the thickness reduction caused by the strain in the X direction. Therefore, the steel plate 2 can form the crimped part 11 with a deep uneven shape in the Z direction without breaking at part B.

[0025] In this way, the steel plates 2 are formed with uneven crimping portions 11 that protrude significantly in the stacking direction, and the fastening force between the stacked steel plates 2 can be strengthened. Therefore, a laminated core in which the generation of NV is suppressed can be provided even when the motor is made to have a high output.

[0026] The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the present invention. In other words, the above description has been omitted or simplified as appropriate for the purpose of clarity, and a person skilled in the art can easily modify, add, or convert each element of the embodiment within the scope of the present invention.

[0027] The laminated core 1 is best suited for use as a rotor core in a motor, because the rotor rotates and requires a strong fastening force between the laminated steel plates 2.

[0028] On the other hand, the laminated core 1 may be a stator core. However, in this case, the fitting length becomes longer, which is a trade-off in that the eddy current loss at the crimped portion becomes larger, so even when forming the crimped portion 11 in which the first ball head portion 21 and the second ball head portion 22 partially overlap as described above, it is necessary to adjust the size of the crimped portion 11 so that it is not formed too deep in the Z direction.

[0029] The contribution of eddy current loss in the rotor to torque is small, being negligible at about 2% of that in the stator. Therefore, in this respect, the laminated core 1 described above, which has crimped portion 11 with large unevenness in the Z direction, is suitable for use as a rotor core.

[0030] Moreover, an IPM (Interior Permanent Magnet) motor, which is an embedded magnet type, is the most suitable motor for using this laminated core 1. However, the formation of the above-mentioned crimped portion 11 can also be applied to the rotor of an induction motor, an outer rotor motor, and an axial gap motor. That is, if the rotor is used in a state where steel plates are stacked, a strong fastening force is required between the steel plates, so it is effective to form the crimped portion 11 where a part of the first ball head portion 21 and the second ball head portion 22 overlap each other.

[0031] In addition, it is optimal to use an electromagnetic steel sheet for the steel sheet 2, but in recent years, the use of low-loss amorphous foil has been considered. Here, amorphous foil is characterized by being very hard and lacking in ductility, so that currently, in the amorphous foil, it is difficult to provide a deep crimping portion 11 in the Z direction with a state in which the first spherical head portion 21 and the second spherical head portion 22 overlap each other. However, if an amorphous foil with ductility is developed in the future, it will be possible to provide a crimping portion 11 in which a portion of the first spherical head portion 21 and the second spherical head portion 22 overlap each other, thereby strengthening the fastening force between the plates.

[0032] Moreover, the motor described above is not limited to a drive motor used in a vehicle, etc., but can be used for a laminated core used in a motor used in a spot-use motor such as a motor for driving a wiper. For example, among these spot-use motors, there are motors using SPC (Steel Plate Cold), and since this SPC has ductility equal to or greater than that of an electromagnetic steel plate, it is possible to form the crimped portion 11 by overlapping a part of the first ball head portion 21 and the second ball head portion 22. In this way, the steel plate 2 described above is not limited to an electromagnetic steel plate, and can be changed as appropriate.

[0033] Furthermore, the dimensions of the R dimension and the crimping depth of the first ball head portion 21 and the second ball head portion 22 can be set arbitrarily.

[0034] In addition, although one crimping portion 11 has been described as being formed with two ball heads 21, 22 in close proximity to each other, the number of ball heads constituting one crimping portion 11 is not limited to two and may be, for example, three or four.

[0035] Here, if the number of ball heads constituting one crimped portion 11 is increased, the fitting length increases accordingly, enabling stronger fastening between the steel plates 2. On the other hand, if the number of ball heads constituting one crimped portion 11 is increased, the inflow of material from the periphery into the crimped portion 11 is promoted, making holes for inserting magnets arranged around the crimped portion 11 more likely to deform in size.

[0036] Therefore, it is often optimal for one crimp portion 11 to be composed of two ball head portions 21, 22, but the number of ball head portions constituting one crimp portion 11 can be appropriately changed depending on the condition of the steel plate 2. [Explanation of symbols]

[0037] 1 Laminated core 2 steel plate 11 Crimping part 21 First Ball Head 22 Second Ball Head 31 Ball Head Punch

Claims

[Claim 1] A laminated core formed by laminating steel plates, The steel plate is A first ball head portion formed in an uneven shape on the plate surface of the steel plate by pressing in the stacking direction; a second ball head portion that is positioned adjacent to the first ball head portion and that is formed in an uneven shape on the sheet surface of the steel sheet by pressing in the stacking direction in the same direction as the first ball head portion, The crimped portion is In the steel plate, a part of the deformation in the stacking direction caused when the first ball head portion is formed and a part of the deformation in the stacking direction caused when the second ball head portion is formed overlap each other. Laminated core.

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