JP7379914B2 - Manufacturing method of laminated structure and laminated structure - Google Patents

Description

The present invention relates to a method for manufacturing a laminated structure and a laminated structure.

2. Description of the Related Art Conventionally, stators used in rotating electric machines such as electric motors have used stator cores that are made of a laminated structure in which a plurality of metal plates are laminated.

A stator core made of a laminated structure is formed by forming a plurality of blocks in which a plurality of metal plates are laminated, laminating the plurality of blocks, and fixing adjacent blocks to each other in the lamination direction. Welding is generally used to fix the blocks in the stator core (for example, see Patent Document 1).

Patent No. 4855123

In the stator core described above, an insulating coating is provided on the surface of the metal plates to suppress short circuits between the metal plates and suppress iron loss (eddy current loss). However, when welding is performed to fix the blocks together, a plurality of metal plates are short-circuited through the welded portion, resulting in increased iron loss.

In order to suppress iron loss, it is conceivable to reduce the size of the welded portion (spot diameter), but in this case, the strength of fixing the blocks together (strength against twisting and peeling) decreases.

In addition, it is possible to improve the fixing strength between blocks by providing many small welds, but in this case, the number of welds increases, making welding work extremely time-consuming and costly. It will increase.

Therefore, an object of the present invention is to provide a method for manufacturing a laminated structure and a laminated structure that can improve the fixing strength between blocks and suppress core loss.

In order to solve the above-mentioned problems, the present invention includes a block forming process of forming a plurality of blocks made by laminating a plurality of metal plates, and a step of laminating the plurality of blocks and welding the blocks adjacent to each other in the lamination direction. A method for manufacturing a laminated structure comprising a welding step, in which the length of the welded portion formed by the welding along the circumferential direction of the block is along the stacking direction of the block. The present invention provides a method for manufacturing a laminated structure, in which the welding is performed so that the welding length is longer than the original length.

Moreover, for the purpose of solving the above problems, the present invention provides a laminated structure in which a plurality of blocks each having a plurality of laminated metal plates are laminated, and the blocks adjacent to each other in the lamination direction are welded to each other, wherein the welding The present invention provides a laminated structure in which the length of the welded portion formed along the circumferential direction of the block is longer than the length of the welded portion along the lamination direction of the block.

According to the present invention, it is possible to provide a method for manufacturing a laminated structure and a laminated structure that can improve the fixing strength between blocks and suppress iron loss.

FIG. 2 is a diagram showing a stator core according to the present embodiment, in which (a) is a plan view and (b) is a side view. 1(a) is an enlarged view of part A in FIG. 1(b), and FIG. 1(b) is a cross-sectional view taken along line BB. It is a figure explaining the caulking of a metal plate. FIG. 2 is a diagram illustrating a conventional welded part, in which (a) is a side view showing the welded part when the spot diameter is increased, (b) is a cross-sectional view taken along the line C-C, and (c) is the welded part when the spot diameter is decreased. (d) is a sectional view taken along the line DD. FIG. 3 is a diagram illustrating control of spot shape by a caps magnetic field, in which (a) is a side view and (b) is a cross-sectional view taken along the line EE. (a) is a front view showing an example of an electrode used for welding, (b) is a side view thereof, and (c) is a front view showing another example of the electrode. FIG. 7 is a side view showing a modified example of a welded portion.

[Embodiment]
Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a diagram showing a stator core as a laminated structure according to the present embodiment, in which (a) is a plan view and (b) is a side view. FIG. 2(a) is an enlarged view of section A in FIG. 1(b), and FIG. 2(b) is a cross-sectional view taken along the line BB.

As shown in FIGS. 1 and 2, the stator core 1 includes a cylindrical base portion 11, a plurality of teeth portions 12 protruding radially inward from the inner peripheral surface of the base portion 11, and a cylindrical base portion 11. It integrally includes a plurality of fixed portions 13 that protrude outward. In the illustrated example, the stator core 1 has 48 teeth portions 12 and four fixed portions 13. The four fixed parts 13 are formed at equal intervals in the circumferential direction of the base part 11, and each fixed part 13 has a bolt insertion hole 13a through which a bolt for fixing the stator core 1 to the housing is inserted. It is formed. A stator is constructed by winding an unillustrated magnetic coil around each tooth portion 12 of the stator core 1.

Although not shown in the drawings, a rotating electrical machine is constructed by providing a stator in which a magnetic coil is wound around each tooth portion 12 of the stator core 1, a rotor having a shaft inserted through its center and holding a plurality of permanent magnets. Ru. A rotating electric machine is installed in, for example, an electric vehicle or a so-called hybrid vehicle, as a motor that generates driving force, as a generator that converts the rotational force of a shaft into electrical energy, or as a motor generator that has both functions.

The stator core 1 as a laminated structure according to the present embodiment is constructed by laminating a plurality of blocks 3 in which a plurality of thin metal plates (stator plates) 2 are laminated, and welding adjacent blocks 3 together in the lamination direction. be done. In the illustrated example, the stator core 1 is configured by stacking six blocks 3.

As the metal plate 2, it is preferable to use an electromagnetic steel plate such as a silicon steel plate having an insulating layer (insulating coating) 21 on the front and back surfaces. Among iron losses, eddy current loss is heat loss due to induced current generated by changes in magnetic flux, and is known to be proportional to the square of the thickness of the member through which the eddy current flows. Therefore, by stacking a large number of thin metal plates 2 with the insulating layer 21 in between, it becomes possible to suppress eddy current loss as a whole. The thickness of the metal plate 2 is, for example, 0.25 mm.

As shown in FIG. 3, a block 3 is constructed by stacking a predetermined number (for example, about 40 metal plates) of metal plates 2, and interconnecting and integrating the metal plates 2 in the thickness direction by caulking. There is. In this embodiment, a through hole 20 is formed in the metal plate 2 located at the bottom of the block 3, and a convex portion 22 formed by caulking the metal plate 2 located above the through hole 20 is formed in the through hole 20. It is embedded. Further, by crimping the metal plate 2, a recess 23 is formed above the protrusion 22, and the protrusion 22 of the metal plate 2 located above the recess 23 is fitted into the recess 23. Such a crimping method is called dowel crimping. However, the means for connecting the metal plates 2 is not limited to dowel caulking, and may be, for example, V-protrusion caulking. Note that in FIG. 3, the insulating layer 21 is omitted.

The plurality of blocks 3 are stacked in the same direction as the stacking direction of the metal plates 2, and adjacent blocks 3 in the stacking direction are welded and fixed to each other. The stator core 1 has a welded portion 14 recessed inward in the radial direction on its outer circumferential surface, and welding of adjacent blocks 3 in the stacking direction is performed in this welded portion 14 . In the illustrated example, a total of four welded parts 14 are provided, one each between circumferentially adjacent fixed parts 13. However, the present invention is not limited thereto, and, for example, two welded parts 14 may be provided between circumferentially adjacent fixed parts 13, for a total of eight welded parts 14. Hereinafter, the welded portion will be referred to as a welded portion 4.

By the way, for example, FIG. 4(a). As shown in (b), when a relatively large welded part 4 is formed by increasing the spot diameter during welding, the welded part 4 that penetrates between the blocks 3 becomes larger, and the fixation strength of the blocks 3 against twisting and peeling increases. Although this increases the number of metal plates 2 that are electrically short-circuited by the welded portion 4, this increases iron loss (eddy current loss).

On the other hand, for example, as shown in FIGS. 4(c) and 4(d), when the spot diameter during welding is made small to form a relatively small welded part 4, the metal plate is electrically short-circuited by the welded part 4. Although the number of blocks 2 is reduced and iron loss (eddy current loss) is suppressed, the welded portion 4 that penetrates between the blocks 3 becomes smaller, and the strength of fixing the blocks 3 to each other against twisting or peeling becomes low. Although it is possible to form a large number of small welded parts 4 in the circumferential direction, in this case, it is necessary to change the press die and provide a large number of welded parts 14, and welding takes time and effort.

Therefore, in the stator core 1 according to the present embodiment, the length w of the welded portion 4 formed by welding along the circumferential direction of the block 3 (hereinafter simply referred to as the circumferential direction) is set in the stacking direction of the block 3 (hereinafter referred to as (simply referred to as the stacking direction). More specifically, in this embodiment, the welded portion 4 is formed to have an elliptical shape, with its minor axis direction coinciding with the stacking direction of the blocks 3.

By shortening the length h of the welded portion 4 in the stacking direction, the number of metal plates 2 that are electrically short-circuited by the welded portion 4 is reduced, and iron loss (eddy current loss) is suppressed. Furthermore, by increasing the length w in the circumferential direction of the welded portion 4, the welded portion 4 that penetrates between the blocks 3 becomes larger, and the strength of fixing the blocks 3 to each other against twisting or peeling increases. In other words, according to the present embodiment, it is possible to suppress iron loss (eddy current loss) and improve the strength of fixing the blocks 3 together. In this embodiment, since there is no need to increase the number of welding locations, the conventional press mold can be used as is, and the effort and time required for welding can be reduced.

(Method for manufacturing stator core 1)
The method for manufacturing the stator core 1 as a laminated structure according to the present embodiment includes a block forming step of forming a plurality of blocks 3 in which a plurality of metal plates 2 are laminated; and a welding step of welding the blocks 3 together.

In the block forming step, the block 3 is formed by stacking a predetermined number of metal plates 2 punched by press working and crimping and fixing the stacked metal plates 2.

In the welding process, first, a plurality of blocks 3 obtained in the block forming process are stacked, but if the blocks 3 are stacked in the same direction, there is a risk of tilting due to manufacturing tolerances, etc. Lamination (rolling) is performed while rotating at a rotation pitch (for example, 90 degrees).

After that, blocks 3 adjacent to each other in the stacking direction are welded to each other. At this time, welding is performed so that the length w along the circumferential direction of the welded portion 4 formed by welding is longer than the length h along the stacking direction. Specifically, in the welding process, the blocks 3 adjacent to each other in the stacking direction are spot welded by TIG (Tungsten Inert Gas) welding, and the spot shape of the welding arc in the spot welding is made into an elliptical shape.

As a method of making the spot shape elliptical, for example, as shown in FIGS. 5A and 5B, there is a method of controlling the shape of the welding arc using a cup type magnetic field. In this method, four magnets 52 are arranged at equal intervals in the circumferential direction with the electrode 51 as the center, and the magnetic poles on the electrode 51 side are made different from each other in the circumferentially adjacent magnets 52. In the electromagnetic field caused by the welding arc, a magnetic field is generated in a counterclockwise direction, as shown by the dashed arrow in FIG. 5(b). Here, when four magnets 52 are arranged, at positions where the magnetic field by the magnets 52 (solid arrows) and the magnetic field by the arc are in the same direction (positions above and below the electrodes 51 in FIG. 5(b)), the composite magnetic field (white arrows) ) increases, and the composite magnetic field (white arrows) decreases at positions where the magnetic field by the magnet 52 (solid arrow) and the magnetic field by the arc are in opposite directions (positions on the left and right of the electrode 51 in FIG. 5(b)). The larger the combined magnetic field, the greater the electromagnetic pinch force directed toward the center of the arc column. Therefore, the arc expands at positions where the combined magnetic field is small, and narrows at positions where the combined magnetic field is large. Thereby, the spot shape of the welding arc can be made into an elliptical shape.

Another method for making the spot shape elliptical is to modify the shape of the electrode 51, as shown in FIGS. 6(a) and 6(b). 6(a) is a front view of the electrode 51, and FIG. 6(b) is a side view of the electrode 51. Generally, it is known that the larger the tip angle of the electrode 51 (the more obtuse the angle), the easier the arc is to concentrate on one point, and the smaller the tip angle (the more acute the angle), the easier it is for the arc to spread. By increasing the tip angle θ of the electrode 51 in a front view and decreasing the tip angle φ of the electrode 51 in a side view, the spot shape can be made into an elliptical shape. Note that, as shown in FIG. 6C, the spot shape can also be made into an elliptical shape by using an electrode 51 having a plurality of protrusions 51a.

The stator core 1 as a laminated structure according to this embodiment is obtained by welding between the blocks 3 with the spot shape of the welding arc set to an elliptical shape.

(Modified example)
In this embodiment, a case has been described in which the welded portion 4 is formed in an elliptical shape, but the shape of the welded portion 4 does not necessarily have to be strictly elliptical, and some deformation or distortion is allowed. Further, the shape of the welded portion 4 does not have to be an ellipse, and may be, for example, an ellipse (rounded rectangle) or a rectangle. Furthermore, as shown in FIG. 7, for example, the welded portion 4 may have a shape in which a plurality of small diameter circles are connected in the circumferential direction of the block 3. For example, by using the electrode 51 having a plurality of protrusions 51a shown in FIG. 6(c) and appropriately adjusting the distance between the protrusions 51a, the welded portion 4 as shown in FIG. 7 can be obtained.

(Actions and effects of embodiments)
As described above, in the present embodiment, in the welding process, the length of the welded portion 4 formed by welding along the circumferential direction of the block 3 is longer than the length of the block 3 along the stacking direction. Welding is done in this way. As a result, the number of metal plates 2 that are electrically short-circuited by the welded portion 4 is reduced to suppress iron loss (eddy current loss), and the welded portion 4 that enters between the blocks 3 is enlarged to prevent twisting. It becomes possible to increase the strength of fixing the blocks 3 to each other against peeling off. In other words, according to the present embodiment, it is possible to improve the strength of fixing the blocks 3 to each other and to suppress iron loss.

Although the embodiments of the present invention have been described above, the embodiments described above do not limit the invention according to the claims. Furthermore, it should be noted that not all combinations of features described in the embodiments are essential for solving the problems of the invention.

The present invention can be modified and implemented as appropriate without departing from the spirit thereof. For example, in the above embodiment, a case has been described in which the laminated structure is the stator core 1, but the present invention is also applicable to a rotor. That is, when a rotor is constructed by laminating a plurality of blocks each made of a plurality of laminated metal plates and welding the blocks adjacent to each other in the lamination direction, the welded portion formed by welding is formed along the circumferential direction of the block. The length may be longer than the length along the stacking direction of the blocks.

Further, in the above embodiment, welding is performed by TIG welding, but the welding is not limited to this, and it is also possible to perform welding by, for example, laser welding. In this case, by controlling the focal point shape to an elliptical shape using an appropriate optical system, or by performing welding multiple times while shifting the welding position in the circumferential direction, the The length along the block 3 is preferably longer than the length along the stacking direction of the block 3.

DESCRIPTION OF SYMBOLS 1... Stator core (laminated structure), 11... Base part, 12... Teeth part, 13... Fixed part, 13a... Bolt insertion hole, 14... Welded part, 2... Metal plate, 20... Through hole, 21... Insulation Layer, 22...Protrusion, 23...Concave part, 3...Block, 4...Welding part, 51...Electrode, 51a...Protrusion, 52...Magnet

Claims (4)

a block forming step of forming a plurality of blocks made by laminating a plurality of metal plates;
A method for manufacturing a laminated structure comprising a welding step of laminating a plurality of the blocks and welding the blocks adjacent to each other in the lamination direction,
In the welding step, the welding is performed such that the length of the welded part formed by the welding along the circumferential direction of the block is longer than the length along the stacking direction of the block, and The adjacent blocks are spot welded to each other,
In the spot welding, the spot shape of the welding arc is elliptical,
In the spot welding, the tip angle is different in a front view seen from the stacking direction of the block and a side view seen from the circumferential direction of the block , and the tip angle in the front view is smaller than the tip angle in the side view. and controlling the spot shape by the size of the tip angle of the electrode in front view and side view.
Method for manufacturing a laminated structure. a block forming step of forming a plurality of blocks made by laminating a plurality of metal plates;
A method for manufacturing a laminated structure comprising a welding step of laminating a plurality of the blocks and welding the blocks adjacent to each other in the lamination direction,
In the welding step, the welding is performed such that the length of the welded part formed by the welding along the circumferential direction of the block is longer than the length along the stacking direction of the block,
The shape of the welded part is a shape in which a plurality of circles are connected in the circumferential direction of the block , and the direction in which the plurality of circles are connected is perpendicular to the stacking direction of the blocks,
Method for manufacturing a laminated structure. The laminated structure is a stator core used in a rotating electric machine,
A method for manufacturing a laminated structure according to claim 1 or 2. A laminated structure in which a plurality of blocks each having a plurality of laminated metal plates are laminated, and the blocks adjacent to each other in the lamination direction are welded to each other,
The length of the welded part formed by the welding along the circumferential direction of the block is longer than the length along the stacking direction of the block,
The shape of the welded part is a shape in which a plurality of circles are connected in the circumferential direction of the block, and the direction in which the plurality of circles are connected is perpendicular to the stacking direction of the blocks,
Laminated structure.

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