JP2021069200A - Laminated steel sheet and manufacturing method of the same - Google Patents

Abstract

To provide a laminated steel sheet in which an adhesive film is hardly broken and a manufacturing method of the same.SOLUTION: A split core 42F includes a plurality of steel sheets 42A stacked in a first direction 102A, and an adhesive film 47 interposed between the adjacent steel sheets 42A adjacent to each other in the first direction 102A to bond the adjacent steel sheets 42A to each other. Each of the plurality of steel sheets 42A above has a first main surface and A first bulging portion that bulges out from the first main surface in the first direction above in a dome-shaped manner and contacts the adjacent steel sheets in the first direction.SELECTED DRAWING: Figure 5

Description

The present invention relates to a laminated steel sheet in which a plurality of steel sheets are bonded with an adhesive, and a method for manufacturing the laminated steel sheet.

Laminated steel plates are used for the cores of rotating electric machines such as electric motors and generators. The laminated steel sheet is manufactured, for example, as follows. That is, in the molding process, the strip-shaped steel plate is punched into a predetermined shape to generate a plurality of steel plates. In the bonding process, an adhesive is applied to each steel sheet. In the laminating step, a plurality of steel sheets are laminated via adhesives (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2009-072794

In the above-mentioned laminated steel sheets, the thickness of the adhesive film interposed between the steel sheets depends on, for example, the force applied to each steel sheet in the laminating direction, but the thickness of the adhesive film between the steel sheets should be constant. It is difficult. The adhesive strength of the steel sheet by the adhesive also depends on the thickness of the film. Therefore, if the thickness of the adhesive between the steel plates varies, the adhesive strength of the steel plates also varies. As a result, when an external force is applied to the laminated steel sheets, the steel sheets at locations where the adhesive force is weak may peel off from each other.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a laminated steel sheet in which an adhesive film is hard to break and a method for manufacturing a laminated steel sheet.

(1) The first aspect of the present invention is a laminated steel plate, which is interposed between a plurality of steel plates laminated in the first direction and adjacent steel plates which are two adjacent steel plates in the first direction. It is provided with an adhesive film that adheres the adjacent steel plates to each other. Each of the plurality of steel plates has a first main surface, a first bulging portion that bulges in a dome shape from the first main surface in the first direction and abuts on the adjacent steel plates in the first direction. Has.

According to the above configuration, since the gap between the adjacent steel plates is kept constant by the first bulging portion, the variation in the film thickness of the adhesive film is suppressed.

(2) Each of the plurality of steel plates bulges in a dome shape from the second main surface opposite to the first main surface and from the second main surface in the second direction opposite to the first direction. It has a second bulging portion. The amount of swelling of the second bulging portion in the second direction is smaller than the amount of swelling of the first swelling portion in the first direction. The first bulging portion of one of the adjacent steel plates abuts on the other peripheral portion of the second bulging portion of the adjacent steel plate.

According to the above configuration, it is difficult for the other to be misaligned with respect to one of the adjacent steel sheets.

(3) Each of the plurality of steel plates has a dome-shaped recessed portion in the second direction opposite to the first direction from the first main surface. The first bulging portion surrounds the recessed portion in a plan view from the first direction.

(4) Each of the plurality of steel plates has a dome-shaped recess in the first direction from the second main surface opposite to the first main surface. The first bulging portion of one of the adjacent steel plates abuts on the other recessed portion of the adjacent steel plate.

(5) Each of the plurality of steel sheets has a plurality of the first bulging portions. The plurality of first bulging portions are positioned symmetrically with respect to a predetermined reference line.

According to the above configuration, since the gap is kept constant over the entire adjacent steel sheet by the plurality of first bulging portions, the variation in the film thickness of the adhesive film is suppressed.

(6) The second aspect of the present invention is a molding step of forming a first bulging portion that bulges in a dome shape in the first direction from the first main surface of each of the plurality of steel sheets, and the molding step. The coating step of applying an adhesive to the steel sheet that has undergone the coating step, and the molding step of the steel sheet that has undergone the molding step so that the first bulging portion of the steel sheet that has undergone the coating process abuts against another steel sheet that has undergone the molding process. It includes a laminating step of laminating another steel sheet on the steel sheet that has undergone the coating step.

According to the above step, the first bulging portion is formed in the molding step, and the first bulging portion is brought into contact with another steel plate in the laminating step, so that the gap between the adjacent steel plates becomes constant and the film thickness due to the adhesive is fixed. Variation can be reduced.

According to the present invention, it is possible to provide a laminated steel sheet in which the adhesive film is hard to break and a method for manufacturing the laminated steel sheet.

It is a schematic diagram which shows the structure of the rotary electric machine 10 which concerns on embodiment of this invention. It is a schematic view when the vertical cross section of the rotary electric machine 10 along the line II-II of FIG. 1 is seen from the axial direction 102. It is a perspective view of the split core 42F shown in FIG. (A) is a view when one steel plate 42A shown in FIG. 3 is viewed from the first direction 102A, and (B) is a view when the steel plate 42A is viewed from the second direction 102B. FIG. 3 is a cross-sectional view taken along the line VV of FIG. 3 when viewed from the direction of arrow A. (A) is a flowchart showing a manufacturing method of a split core 42F, and (B) is a schematic diagram showing a configuration of a manufacturing apparatus 25. (A) and (B) are schematic views showing the first modification example and the second modification example of the divided core 42F, respectively. It is a schematic diagram which shows the modification of the stator core 42.

Hereinafter, the rotary electric machine 10 using the laminated steel plate according to the embodiment of the present invention will be described. It goes without saying that the embodiments described below are merely examples of the present invention, and the embodiments can be appropriately changed without changing the gist of the present invention.

[Rough configuration of rotary electric machine 10]
As shown in FIG. 1, the rotary electric machine 10 is an electric motor, specifically, an inner rotor type brushless motor 30. The brushless motor 30 includes a rotor 31, a shaft 32, a stator 33, and the like inside the housing 36.

[Rotor 31]
In FIGS. 1 and 2, the rotor 31 is rotatable around the axis 104 of the shaft 32 (see alternate long and short dash line in FIG. 1). The rotor 31 includes a rotor core 49. The rotor core 49 is a laminated body in which a plurality of thin steel plates having a substantially annular shape are laminated in the axial direction 102. Specifically, the steel sheet is an electromagnetic steel sheet having an insulating film formed on its surface. The rotor core 49 has a substantially cylindrical shape, and has an outer peripheral surface 53 and an inner peripheral surface 55. The outer peripheral surface 53 and the inner peripheral surface 55 are substantially cylindrical surfaces having different diameters from each other. The outer peripheral surface 53 and the inner peripheral surface 55 share an axis 104 as a central axis. The inner peripheral surface 55 defines the through hole 54.

As shown in FIG. 2, the rotor 31 is a surface magnet type or an embedded magnet type, and has eight magnets 40. Each magnet 40 is a permanent magnet. The eight magnets 40 are arranged on the rotor core 49 at equal angular intervals in the circumferential direction 105 about the axis 104 in a plan view from the axial direction 102. More specifically, the eight magnets 40 are arranged so that the north and south poles alternately appear on the outer peripheral surface 53 in the circumferential direction 105.

[Shaft 32]
As shown in FIG. 1, the shaft 32 has a cylindrical shape that is longer than the rotor 31 in the axial direction 102. The shaft 32 is inserted into the through hole 54. Both ends of the shaft 32 project from the through hole 54 in the axial direction 102. In this state, the shaft 32 is fixed to the inner peripheral surface 55 of the rotor core 49. The shaft 32 is supported by the housing 36 via two bearings 52 provided in the housing 36 on both sides in the axial direction 102. As a result, the shaft 32 can rotate with respect to the housing 36 in the circumferential direction 105 together with the rotor 31. One end of the shaft 32 in the axial direction 102 protrudes from the housing 36 in the axial direction 102.

[Rough configuration of stator 33]
As shown in FIGS. 1 and 2, the stator 33 includes a stator core 42, 12 electrical insulators 45, and 12 coils 39. Note that FIG. 2 shows only three electrical insulators 45 and one coil 39.

[Stator core 42]
As shown in FIG. 2, the stator core 42 is arranged so as to surround the outer peripheral surface 53 of the rotor 31, and generally has a tubular shape. The stator core 42 has a stator yoke 43 and 12 teeth 44. In FIG. 2, reference numeral 44 is attached to only one tooth.

The stator yoke 43 has a tubular shape, and has an outer peripheral surface 61 and an inner peripheral surface 62. The outer peripheral surface 61 and the inner peripheral surface 62 are substantially cylindrical surfaces having different diameters from each other. The outer peripheral surface 61 and the inner peripheral surface 62 share an axis 104 as a central axis. The diameter of the inner peripheral surface 62 is larger than that of the outer peripheral surface 53 of the rotor 31.

The twelve teeth 44 have the same shape as each other. The twelve teeth 44 are arranged on the inner peripheral surface 62 at equal angular intervals in the circumferential direction 105 when viewed from the axial direction 102. Each tooth 44 extends from the inner peripheral surface 62 toward the axis 104 in parallel with the radial direction 103. The radial direction 103 is a direction orthogonal to the axis 104. Note that FIG. 2 and the like show only one example of the radial direction 103. The extending end of each tooth 44 is the tooth tip surface 44A. Each tooth tip surface 44A is separated from the outer peripheral surface 53 of the rotor 31 and each magnet 40. That is, each tooth 44 faces the outer peripheral surface 53 of the rotor 31 via a gap. In FIG. 2, reference numeral 44A is attached to only one tooth tip surface.

As shown in FIG. 2, the stator core 42 has 12 divided cores 42F divided for each tooth 44. In FIG. 2, reference numeral 42F is attached only to the three divided cores. The two divided cores 42F adjacent to each other in the circumferential direction 105 are adhered to each other by an adhesive (not shown) or the like. Each of the divided cores 42F has the same external dimensions as each other, and as shown in FIGS. 3 and 4, has a shape substantially symmetrical with respect to the reference surface 107 which is the central surface in the circumferential direction 105. ..

[Split core 42F (laminated steel plate)]
As shown in FIG. 3, each divided core 42F is an example of a laminated steel plate, and includes a plurality of steel plates 42A laminated in the axial direction 102. Each of the steel plates 42A is an electromagnetic steel plate and has main surfaces 46A and 46B (see FIG. 4) that are separated from each other in the axial direction 102. The main surface 46B is on the opposite side of the main surface 46A in the axial direction 102. The main surface 46A is the first example of the first main surface, and the main surface 46B is the first example of the second main surface. Hereinafter, in the axial direction 102, the direction from the main surface 46B to the main surface 46A is referred to as a first direction 102A, and the direction opposite to the first direction 102A is referred to as a second direction 102B. Each of the main surfaces 46A and 46B has the same outer shape when the divided core 42F is viewed from the axial direction 102. Insulating coatings are formed on the main surfaces 46A and 46B. As a result, in each of the divided cores 42F, the plurality of steel plates 42A are electrically insulated from each other. Each split core 42F further comprises an adhesive film 47 (see FIG. 5). As shown in FIG. 5, the adhesive film 47 is interposed between two adjacent steel plates 42A (hereinafter, also referred to as adjacent steel plates 42A) in the axial direction 102. Each adhesive film 47 adheres two adjacent steel plates 42A to each other.

As shown in FIG. 4A, six recessed portions 71 are formed on the main surface 46A side of each steel plate 42A. Specifically, the six recessed portions 71 include recessed portions 71A to 71F. The recessed portions 71A and 71B are located at portions of the steel plates 42A that serve as the stator yoke 43. Specifically, the recessed portions 71A and 71B are formed near one end and the other end in the circumferential direction 105 of the portion to be the stator yoke 43, and at positions substantially symmetrical with respect to the reference surface 107. Further, each of the recessed portions 71A and 71B is located between the outer peripheral surface 61 and the inner peripheral surface 62 (see FIGS. 2 and 3) in the radial direction 103. The recessed portions 71C and 71D are arranged along the radial direction 103 at the portion serving as the teeth 44 in each of the steel plates 42A. Each of the recessed portions 71C and 71D has a shape substantially symmetrical with respect to the reference surface 107. The recessed portions 71E and 71F are located near the portion of the steel plate 42A that becomes the tooth 44 and the tooth tip surface 44A (see FIGS. 2 and 3). Specifically, the recessed portions 71E and 71F are formed in the portion to be the tooth tip surface 44A along the circumferential direction 105. Further, the recessed portions 71E and 71F are formed at positions substantially symmetrical with respect to the reference surface 107.

As shown in FIG. 5, each recessed portion 71 is recessed in a dome shape from the main surface 46A toward the second direction 102B. That is, each recess 71 has a hemispherical curved surface or a radial curved surface. Further, as shown in FIG. 4A, each recessed portion 71 has a circular outer shape in a plan view from the axial direction 102.

As shown in FIG. 4A, one bulging portion 72 is formed around the six recessed portions 71 on the main surface 46A side of each steel plate 42A. The bulging portion 72 is a first example of the first bulging portion. Each bulging portion 72 surrounds the corresponding recessed portion 71 over the entire circumference, and bulges in a dome shape from the main surface 46A toward the first direction 102A. Each bulging portion 72 has an annular shape in a plan view from the axial direction 102. The cross section of the bulging portion 72 along the circumferential direction 105 of each recessing portion 71 is generally arcuate or parabolic.

As shown in FIG. 4B, one bulging portion 73 is formed at a position corresponding to the six recessed portions 71 on the main surface 46B side of each steel plate 42A. The bulging portion 73 is a first example of the second bulging portion. Each bulging portion 73 bulges in a dome shape from the main surface 46B toward the second direction 102B. That is, each bulging portion 73 has a hemispherical curved surface or a radial curved surface. Further, each bulging portion 73 has a circular outer shape in a plan view from the axial direction 102.

In FIG. 5, the distance between the main surfaces 46A and 46B (hereinafter, also referred to as the thickness) is defined as A, and the distance between the main surface 46A and the apex of each bulging portion 72 (hereinafter, also referred to as the bulging amount). ) Is B, and the distance between the main surface 46B and the apex of each bulging portion 73 (hereinafter, also referred to as the bulging amount) is C. When A is, for example, 0.3 mm or less, B and C are values satisfying 1.0 μm ≦ B + C ≦ 100.0 μm. Further, the swelling amounts B and C are determined by the amount of the adhesive applied to the recessed portion 71 in the coating step described later. The amount of swelling B is further determined in advance by the adhesive strength of the adjacent steel plate 42A by the adhesive film 47. FIG. 5 shows an example in which the swelling amount B is smaller than the swelling amount C.

Further, the volume of the space obtained by cutting the recessed portion 71 and the bulging portion 72 along the main surface 46A is defined as D and E, and the volume of the space obtained by cutting the bulging portion 73 along the main surface 46B. Let F be. D to F are values that satisfy D> F and D = E + F. As a result, when the adjacent steel plate 42A is laminated so that one bulging portion 73 of the adjacent steel plate 42A fits inside the other bulging portion 72 in the laminating step in the manufacturing process of the laminated steel plate, the main surface of the adjacent steel plate 42A is laminated. There is a gap of distance B between 46A and 46B. Further, when the adhesive is applied to the recessed portion 71 in the coating step which is a step prior to the laminating step, an adhesive film 47 having a thickness B is formed between the main surfaces 46A and 46B of the adjacent steel plates 42A. Will be done.

[Electrical insulator 45]
In FIGS. 1 and 2, the twelve electrical insulators 45 are realized by a resin mold fixed to the corresponding teeth 44. The resin mold is a molded product of a resin having electrical insulation. The twelve electrical insulators 45 cover a part of the surface of the stator core 42.

[Coil 39]
Each coil 39 is wound around each tooth 44 via an electrical insulator 45. Specifically, each coil 39 is wound around an intermediate portion of the electrical insulator 45. A U-phase, V-phase, and W-phase AC voltage is applied to each coil 39 by a controller (not shown). A rotating magnetic field is formed in the space surrounded by the twelve teeth 44. As a result, the rotor 31 rotates.

[Manufacturing method of split core 42F (laminated steel plate)]
Hereinafter, a method of manufacturing the split core 42F will be described with reference to FIG. As shown in FIG. 6A, the manufacturing method includes a first molding step (S1), a coating step (S2), a second molding step (S3), and a laminating step (S4).

As shown in FIG. 6B, the strip-shaped steel plate X is fed into the manufacturing apparatus 25. The strip-shaped steel plate X has a thickness of 0.3 mm or less. Insulating coatings are formed on both main surfaces of the strip-shaped steel plate X. The manufacturing apparatus 25 includes a first punch 251 and a first die 252. The first punch 251 and the first die 252 face each other in the direction corresponding to the axial direction 102. The shape of the first punch 251 further has a shape corresponding to the recessed portion 71. The first die 252 further has a shape corresponding to the bulging portion 73. The manufacturing apparatus 25 applies a predetermined pressure to the positions corresponding to the six recesses 71 in the strip-shaped steel plate X by the first punch 251 and the first die 252 (first molding step, S1). The predetermined pressure is derived in advance by experiments and simulations before manufacturing the split core 42F, and is a pressure at which the insulating film of the strip-shaped steel plate X does not break. By applying a predetermined pressure, the manufacturing apparatus 25 forms a recess portion 71 (see FIG. 5) having a volume D on the main surface 46A side (that is, the strip-shaped steel plate X) of the steel plate 42A, and has a volume F on the main surface 46B side. A bulge 73 (see FIG. 5) is formed. Since D> F, a bulging portion 72 (see FIG. 5) having a volume E (= DF) is formed around the recessed portion 71 on the main surface 46A side.

Next, the manufacturing apparatus 25 further includes a coating mechanism 253. The coating mechanism 253 applies an adhesive such as an epoxy resin adhesive to the recessed portion 71 of the steel plate 42A (that is, the strip-shaped steel plate X) that has undergone the molding step (S2, coating step).

The manufacturing apparatus 25 includes a second punch 254 and a second die 255. The shapes of the second punch 254 and the second die 255 correspond to the planar shape of the split core 42F seen from the axial direction 102. The manufacturing apparatus 25 punches the strip-shaped steel plate X that has undergone the coating process into the planar shape of the split core 42F by the second punch 254 and the second die 255 to form the steel plate 42A (second molding process, S3).

In the manufacturing apparatus 25, the steel plate 42A that has undergone the second molding step is laminated in the punch holes 256 of the second die 255. The manufacturing apparatus 25 further includes a laminating mechanism 257 below the second die 255. The steel plate 42A is laminated in the punch hole 256 in the axial direction 102 by the punch hole 256 and the laminating mechanism 257. At the time of laminating, one main surface 46A of the adjacent steel plate 42A faces the other main surface 46B of the adjacent steel plate 42A. More specifically, the bulging portion 73 of the main surface 46B fits into the space partitioned by the bulging portion 72 of the main surface 46A. As a result, the adhesive applied to the recessed portion 71 overflows from the bulged portion 72 and expands the gap between the main surfaces 46A and 46B toward the outside of the adjacent steel plate 42A. As a result, an adhesive film 47 is formed between the adjacent steel plates 42A, and these are adhered (lamination step, S4). By repeating S1 to S4, the split core 42F is manufactured.

[Action / effect of split core 42F (laminated steel plate)]
According to the split core 42F, when the steel plates 42A are laminated in the axial direction 102 in the laminating step, the bulging portion 72 formed on one of the adjacent steel plates 42A comes into contact with the other main surface 46B of the adjacent steel plates 42A. As a result, the distance between one main surface 46A of the adjacent steel plate 42A and the other main surface 46B of the adjacent steel plate 42A becomes the height B of the bulging portion 72. As a result, the variation in the film thickness of the adhesive film 47 is suppressed, and the adhesive film 47 is less likely to break.

Further, the bulging amount B of the bulging portion 72 is larger than the bulging amount C of the bulging portion 73. In this case, in the laminating step, the bulging portion 72 comes into contact with the periphery of the bulging portion 73 on the main surface 46B regardless of the depth of the recessed portion 71. As a result, the position of the other side of the adjacent steel plate 42A is unlikely to shift with respect to one side.

Further, the bulging portions 72 are formed at a plurality of locations on the main surface 46A side. As a result, the distance between one main surface 46A of the adjacent steel plate 42A and the other main surface 46B of the adjacent steel plate 42A, that is, the variation in the film thickness of the adhesive film 47 can be suppressed over a wide region. Further, a plurality of recessed portions 71 (specifically, recessed portions 71A, 71B, etc.) are located symmetrically with respect to the reference surface 107. That is, the plurality of bulging portions 72 are located symmetrically with respect to the reference plane 107. Thereby, the variation in the film thickness of the adhesive film 47 can be further suppressed.

[First modification of the split core 42F]
In the embodiment, the recessed portion 71 and the bulging portion 72 are formed on the main surface 46A side of each steel plate 42A, and the bulging portion 73 is formed on the main surface 46B side. However, the present invention is not limited to this, and as shown in FIG. 7A, the bulging portion 73 may not be formed on the main surface 46B side.

[Second modification of the split core 42F]
In addition, as shown in FIG. 7B, the bulging portion 72 is not formed on the main surface 46A side, but the recessed portion 71 is formed on the main surface 46A of each steel plate 42A, and the main surface of each steel plate 42A is formed. The bulging portion 73 may be formed on the 46B. Here, let G be the distance (hereinafter, also referred to as depth) between the main surface 46A and the bottom of the recessed portion 71. The bulging amount C of the bulging portion 73 is larger than the depth G. In this case, the bulging portion 73 fits into the recessed portion 71, so that the distance between one main surface 46A of the adjacent steel plate 42A and the other main surface 46B becomes substantially constant. This also makes it possible to suppress variations in the distance between one main surface 46A of the adjacent steel plate 42A and the other main surface 46B. The main surface 46B is a second example of the first main surface, and the main surface 46A is a second example of the second main surface. The bulging portion 73 is a second example of the first bulging portion, and the recessed portion 71 is a second example of the recessed portion. Further, the bulging amount C of the bulging portion 73 may be smaller than the depth G, and the diameter of the bulging portion 73 may be larger than the diameter of the recessed portion 71. In this case, the bulging portion 73 comes into contact with the peripheral edge of the recessed portion 71, and the distance between one main surface 46A of the adjacent steel plate 42A and the other main surface 46B becomes substantially constant.

The steel plate 42A as in the first modification and the second modification can be implemented by appropriately adjusting the shapes of the first punch 251 and the first die 252 and a predetermined pressure.

[Modification example of stator core 42]
As shown in FIG. 8, the stator core 42 is not divided into split cores 42F, and even if the stator core 42 is formed by laminating steel plates 42A having an outer shape when viewed in a plan view from the axial direction 102 in the axial direction 102. Good.

[Other variants]
In the embodiment, the stator core 42 has 12 split cores 42F. However, the present invention is not limited to this, and the stator core 42 may be divided into three or more divided cores 42F. Further, a plurality of teeth may be formed on one divided core.

In the above-described embodiment, the split core 42F is described as an example of the laminated steel plate, but the rotor 31 may be the laminated steel plate made of the steel plate 42A described in the embodiment. Further, the use of the laminated steel plate is not limited to the electric motor, and may be used, for example, as a core of a generator or a core of an angle sensor.

Further, although the manufacturing apparatus 25 of the embodiment includes the coating mechanism 253, the coating mechanism 253 may be independent of the press mechanism for punching the electromagnetic steel sheet into a predetermined shape. In this case, the coating step (S2) is performed after laminating the steel sheets on the die. That is, the steel plates laminated by the laminating mechanism 257 of the manufacturing apparatus 25 are not bonded to each other, and in the laminated steel plates taken out from the laminating mechanism 257, the adjacent steel plates 42A are separated from each other, and an adhesive is formed between the adjacent steel plates 42A. After being coated, the bulging portion 72 formed on one side of the adjacent steel plate 42A is brought into contact with the other main surface 46B of the adjacent steel plate 42A again to form an adhesive film 47 having a certain thickness. It is formed.

10 ... Rotary machine 30 ... Brushless motor 42 ... Stator core 42F, 48 ... Split core (laminated steel plate)
42A ... Steel plate, adjacent steel plate 43,81 ... Stator yoke 44,82 ... Teeth 44A, 82A ... Tooth tip surface 46A, 46B ... Main surface 47 ... Adhesive film 71 ... Recessed parts 71, 71A to 71F ... Recessed parts 72, 73 ... Swelling parts (first bulging part, second bulging part)
S1 ... 1st molding process S2 ... Coating process S3 ... 2nd molding process S4 ... Laminating process

Claims (6)

Multiple steel plates laminated in the first direction and
An adhesive film is provided between adjacent steel plates, which are two adjacent steel plates adjacent to each other in the first direction, to bond the adjacent steel plates to each other.
Each of the above-mentioned plurality of steel sheets
The first main surface and
A laminated steel plate having a first bulging portion that bulges from the first main surface in a dome shape in the first direction and abuts on the adjacent steel plates in the first direction. Each of the above-mentioned plurality of steel sheets
The second main surface on the opposite side of the first main surface,
It has a second bulging portion that bulges in a dome shape from the second main surface in a second direction opposite to the first direction.
The amount of swelling of the second bulging portion in the second direction is smaller than the amount of swelling of the first swelling portion in the first direction.
The laminated steel sheet according to claim 1, wherein the first bulging portion of one of the adjacent steel sheets abuts on a peripheral portion of the second bulging portion on the other second main surface of the adjacent steel sheet. Each of the plurality of steel plates has a recessed portion that is recessed in a dome shape from the first main surface in the second direction opposite to the first direction.
The laminated steel sheet according to claim 1 or 2, wherein the first bulging portion surrounds the recessed portion in a plan view from the first direction. Each of the plurality of steel plates has a recessed portion that is recessed in a dome shape in the first direction from the second main surface opposite to the first main surface.
The laminated steel sheet according to claim 1, wherein the first bulging portion of one of the adjacent steel sheets abuts on the other recessed portion of the adjacent steel sheet. Each of the plurality of steel sheets has a plurality of the first bulging portions, and the plurality of first bulging portions are positioned symmetrically with respect to a predetermined reference line. The laminated steel sheet according to any one of 4 to 4. A molding step of forming a first bulging portion that bulges in a dome shape in the first direction from the first main surface of each of the plurality of steel plates by applying a predetermined pressure to each of the positions of the plurality of steel plates.
A coating process of applying an adhesive to the steel sheet that has undergone the molding process, and
The other steel sheet that has undergone the molding process is transferred to the steel sheet that has undergone the coating process so that the first bulging portion of the steel sheet that has undergone the coating process comes into contact with another steel sheet that has undergone the molding process. A method for manufacturing a laminated steel sheet, comprising a laminating process for laminating.

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