Laminated core and its manufacturing apparatus and manufacturing method

Abstract

A manufacturing device (100) comprises a punch (12), a blanking die (14), a first holding support (16), a second holding support (18), and a heating unit (20). A plurality of core sheets (1a) are blanked from a steel strip (1) by the punch (12) and the blanking die (14), and while the outer periphery of the blanked plurality of core sheets (1a) is pressed from the side by the first holding support (16), the plurality of core sheets (1a) are pressed downward by the punch (12), and the plurality of core sheets (1a) pressed downward by the punch (12) are held and supported within the second holding support (18) and heated by the heating unit (20). The first holding support member (16) maintains a plurality of core sheets (1a) at a temperature below the softening temperature of the adhesive layer (11b), and the heating member (20) heats a plurality of core sheets (1a) held and supported within the second holding support member (18) to a temperature above the softening temperature.

Description

Technology Field

[0001] The present invention relates to a laminated core, an apparatus for manufacturing the same, and a method for manufacturing the same. Background Technology

[0002] Conventionally, laminated cores having a configuration in which multiple electrical steel sheets are laminated are used as cores for rotary electric machinery and the like. As one method for manufacturing a laminated core, a method is known in which a core sheet of a predetermined shape is blanked from a steel strip coated with an adhesive, and the resulting multiple core sheets are bonded together to manufacture the laminated core.

[0003] For example, in the method for manufacturing a laminated iron core disclosed in Patent Document 1, an iron core sheet blanked from a strip-shaped steel plate by an outer blanking punch is pressed into an outer blanking die. The iron core sheet pressed into the outer blanking die is laminated on top of the iron core sheet that was previously blanked and is sequentially pressed into the lower squeeze ring of the outer blanking die. The iron core sheets pressed into the squeeze ring are pressed against the inner circumference of the squeeze ring and move to come into close contact with each other. At this time, the adhesive between each iron core sheet is cured by heating with a heating heater, and a laminated iron core is formed in which a predetermined number of iron core sheets are fixed together. Prior art literature

[0004] Japanese Patent Publication No. 2009-297758 The problem to be solved

[0005] In the method disclosed in Patent Document 1, blanking of iron core sheets by a blanking die and pressing and heating of a plurality of iron core sheets within a squeeze ring can be performed continuously. By doing so, laminated iron cores can be manufactured efficiently.

[0006] However, as a result of research by the inventors, it was found that when pressing and heating a plurality of iron core thin plates are performed simultaneously as described above, compressive residual stress occurs in the obtained laminated iron core, and iron loss may increase.

[0007] Therefore, the present invention aims to provide a low iron loss laminated core, and a method for manufacturing the same and a manufacturing apparatus. means of solving the problem

[0008] A laminated core according to one embodiment of the present invention is,

[0009] It is a laminated core in which multiple electrical steel sheets are laminated through an adhesive layer, and

[0010] It is characterized by the iron loss degradation rate of the laminated core for the two layers of electrical steel sheets separated from the laminated core being 10% or less.

[0011] On the electrical steel sheet at one end portion in the lamination direction of the above-mentioned laminated core, a plurality of convex portions protruding outwardly in the lamination direction may be formed.

[0012] A method for manufacturing a laminated core according to one embodiment of the present invention is,

[0013] A manufacturing apparatus comprising a punch, a blanking die disposed below the punch, a first holding support disposed below the blanking die, a second holding support disposed below the first holding support, and a heating member disposed around the second holding support.

[0014] A plurality of core sheets are blanked from a steel strip having a thermosetting adhesive layer on its surface by the above punch and the above blanking die, and

[0015] While pressing the outer periphery of the blanked plurality of core sheets from the side by the first holding support member, the plurality of core sheets are pressed downward by the punch, and

[0016] The plurality of core sheets, which are pressed downward by the above punch, are held and supported within the second holding support and heated by the heating unit, and

[0017] In the first holding support above, the plurality of core sheets are maintained at a temperature below the softening temperature of the adhesive layer, and

[0018] The heating unit is characterized by heating the plurality of core sheets held and supported within the second holding support to a temperature higher than the softening temperature of the adhesive layer.

[0019] In addition, a manufacturing apparatus for a laminated core according to one embodiment of the present invention is,

[0020] A device for manufacturing a laminated core by blanking a plurality of core sheets from a steel strip having an adhesive layer on its surface and bonding the obtained plurality of core sheets together.

[0021] Punch,

[0022] A blanking die positioned below the above punch,

[0023] A first holding support member positioned below the blanking die,

[0024] A second holding support member positioned below the first holding support member, and

[0025] A heating unit disposed around the second holding support member.

[0026] Equipped,

[0027] A plurality of core sheets are blanked from a steel strip by the above punch and the above blanking die, and

[0028] While pressing the outer periphery of the blanked plurality of core sheets from the side by the first holding support member, the plurality of core sheets are pressed downward by the punch, and

[0029] The plurality of core sheets, which are pressed downward by the above punch, are held and supported within the second holding support and heated by the heating unit, and

[0030] In the first holding support above, the plurality of core sheets are maintained at a temperature below the softening temperature of the adhesive layer, and

[0031] The heating unit is characterized by heating the plurality of core sheets held and supported within the second holding support to a temperature higher than the softening temperature of the adhesive layer.

[0032] In the first holding support member, the vertical length of the portion in contact with the core sheet may be 5 mm or more.

[0033] The above punch may press the plurality of core sheets with a pressing force of 2.0 MPa or less.

[0034] The above heating unit may include an infrared heating device. Effects of the invention

[0035] According to the present invention, a laminated core with low iron loss is obtained. Brief explanation of the drawing

[0036] FIG. 1 is a schematic cross-sectional view illustrating a manufacturing apparatus for a laminated core according to a first embodiment of the present invention. Figure 2 is an enlarged cross-sectional view illustrating the vicinity of the surface of the steel band. Figure 3 is a diagram illustrating a method for measuring iron loss. FIG. 4 is a drawing for explaining a method for manufacturing a laminated core according to a first embodiment of the present invention. FIG. 5 is a drawing for explaining a method for manufacturing a laminated core according to a first embodiment of the present invention. FIG. 6 is a drawing for explaining a method for manufacturing a laminated core according to a first embodiment of the present invention. Figure 7 is a drawing illustrating a modified example of a manufacturing device. Figure 8 is a drawing illustrating another variation of the manufacturing device. FIG. 9 is a drawing illustrating other variations of the manufacturing device. Figure 10 is a drawing illustrating a modified example of a laminated core. FIG. 11 is a schematic cross-sectional view illustrating a manufacturing apparatus for a laminated core according to a second embodiment of the present invention. Specific details for implementing the invention

[0037] Hereinafter, a laminated core, a manufacturing apparatus, and a manufacturing method relating to an embodiment of the present invention will be described using drawings.

[0038] (First embodiment)

[0039] FIG. 1 is a schematic cross-sectional view illustrating a manufacturing apparatus for a laminated core according to a first embodiment of the present invention. The manufacturing apparatus (100) is an apparatus that blanks a plurality of core sheets (1a) from a steel band (1) conveyed in a predetermined direction and manufactures a laminated core (2) by bonding the obtained plurality of core sheets (1a) together. In this embodiment, the laminated core (2) has a cylindrical shape and is used as a stator core in a rotary electric machine. Additionally, the laminated core (2) may be a laminated core used as a rotor core in a rotary electric machine. Additionally, the laminated core (2) may be one of a plurality of segmented cores constituting a stator core. Additionally, the laminated core (2) may be a core of a device other than a rotary electric machine.

[0040] Below, after briefly describing the steel strip (1), a detailed description of the laminated core (2) and the manufacturing device (100) will be provided. FIG. 2 is an enlarged cross-sectional view showing the vicinity of the surface of the steel strip (1).

[0041] As shown in FIG. 2, the steel plate (1) comprises a base steel plate (11a) and an adhesive layer (11b). In this embodiment, a non-oriented electrical steel plate is used as the base steel plate (11a), but an oriented electrical steel plate may also be used as the base steel plate (11a). Furthermore, in this specification, the term "electrical steel plate" refers to the base portion (base steel plate) excluding insulating films, etc. The adhesive layer (11b) is formed on the surface of the base steel plate (11a). In this embodiment, the adhesive layer (11b) is formed on both sides of the base steel plate (11a), but the adhesive layer (11b) may be formed on only one side of the base steel plate (11a).

[0042] The chemical composition of the base steel sheet (11a) contains basic elements, optional elements as needed, and the remainder is Fe and impurities. In this embodiment, the chemical composition of the base steel sheet (11a) contains, for example, Si: 1.0 to 4.5%, Al: 0.1 to 1.5%, and Mn: 0.2 to 4.0% in mass% as basic elements.

[0043] The adhesive layer (11b) is formed to cover the entire surface of the base steel plate (11a). A thermosetting resin is used as the adhesive layer (11b). In this embodiment, the adhesive layer (11b) has insulating performance in addition to adhesive ability. In this embodiment, the adhesive layer (11b) is, for example, an insulating film containing an epoxy resin and an epoxy resin curing agent.

[0044] As an epoxy resin, for example, an epoxy resin having two or more epoxy groups in one molecule may be used. Examples of such epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, alicyclic epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, hydantoin type epoxy resin, isocyanurate type epoxy resin, acrylic acid modified epoxy resin (epoxyacrylate), phosphorus-containing epoxy resin, and their halides (brominated epoxy resin, etc.) or hydrogenated derivatives. As for the epoxy resin, one type may be used alone, or two or more types may be used in combination.

[0045] Examples of epoxy resin curing agents include aromatic polyamines, acid anhydrides, phenolic curing agents, dicyandiamides, boron trifluoride-amine complexes, organic acid hydrazides, etc. Examples of aromatic polyamines include metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, etc. Examples of phenolic curing agents include phenol novolak resin, cresol novolak resin, bisphenol novolak resin, triazine-modified phenol novolak resin, phenol resol resin, etc. As an epoxy resin curing agent, a phenolic curing agent is preferred, and a phenol resol resin is more preferred. As an epoxy resin curing agent, one type may be used alone, or two or more types may be used in combination.

[0046] Additionally, although a detailed description is omitted, the adhesive layer (11b) may be, for example, an insulating film containing an acrylic resin and an acrylic resin curing agent.

[0047] Additionally, although a detailed description is omitted, another insulating film may be further formed between the base steel plate (11a) and the adhesive layer (11b). As a material constituting the insulating film, for example, (1) an inorganic compound, (2) an organic resin, (3) a mixture of an inorganic compound and an organic resin may be applied. Examples of inorganic compounds include (1) a complex of dichromate and boric acid, (2) a complex of phosphate and colloidal silica, (3) a phosphate, (4) a Zr compound, (5) a Ti compound. Examples of organic resins include epoxy resin, acrylic resin, acrylic styrene resin, polyester resin, silicone resin, fluoropolymer resin, etc.

[0048] (Composition of stacked cores)

[0049] As described above, the laminated core (2) has a configuration in which a plurality of core sheets (1a) blanked from a steel strip (1) are laminated. More specifically, the laminated core (2) has a configuration in which a plurality of base steel sheets (electrical steel sheets) (11a) blanked into a predetermined shape are laminated by bonding them together with an adhesive layer (11b). The laminated core is obtained, for example, by laminating a plurality of core sheets (1a) having an adhesive layer (11b) formed on their surface, applying pressure and heating, and fixing the core sheets (1a) together through the adhesive layer (11b).

[0050] (Method for measuring iron loss deterioration rate)

[0051] In this embodiment, the laminated core (2) is manufactured such that the iron loss degradation rate of the laminated core (2) with respect to the two layers (two sheets in this embodiment) of base steel plates (11a) (core sheet (1a)) removed from the laminated core (2) is 10% or less. The iron loss of the laminated core (2) and the two layers of base steel plates (11a) is measured as follows.

[0052] First, the iron loss of the laminated core (2) is measured. The laminated core (2) used for measurement may have a configuration in which a plurality (two or more) base steel sheets (electrical steel sheets) (11a), blanked into a predetermined shape as described above, are bonded together by an adhesive layer (11b). The laminated core (2) may be obtained, for example, by the method described above, and may have undergone a predetermined heat treatment (such as stress relief annealing). The dimensions of the laminated core used for measurement are not particularly limited. The number of layers of electrical steel sheets constituting the laminated core is not particularly limited, but for example, a laminated core consisting of two electrical steel sheets may be used. In this embodiment, the iron loss W of the laminated core (2) is measured by a magnetic property measuring device (BST-L) manufactured by BROCKHAUS. 15 / 50 Measure (W / kg).

[0053] Next, a two-layer core sheet (1a) to be measured for iron loss is removed from the laminated core (2). The two-layer core sheet (1a) to be measured is a two-layer core sheet from which the adhesive layer has been removed and which has been separated from the laminated core (2) by a method described later. As described above, in this embodiment, the laminated core (2) has a cylindrical shape, and each core sheet (1a) has an annular shape. Therefore, in this embodiment, the two core sheets (1a) on the surface side of the laminated core (2) become the two-layer core sheet (1a) to be measured for iron loss. Furthermore, it is preferable that the two-layer core sheet (1a) (two sheets in this embodiment) to be measured for iron loss be either the two-layer core sheet (1a) on one side in the thickness direction of the laminated core (2), or the two-layer core sheet (1a) on the other side in the thickness direction of the laminated core (2). However, as shown in FIG. 10 described later, if a convex portion (3) for separating a plurality of laminated cores (2) is formed, a two-layer core sheet (1a) on the side where the convex portion (3) is not formed is used as the target for iron loss measurement. In addition, the dimensions of the two-layer core sheet (1a) to be the target for iron loss measurement are not particularly limited, but the core sheet (1a) removed from the laminated core (2) by the method described later can be used as is.

[0054] In this embodiment, the adhesive layer (11b) is carbonized by heating the laminated core (2) in a heating furnace at 400°C for 12 hours, thereby separating the two core sheets (1a) on the surface side of the laminated core (2). Then, the surface of the two core sheets (1a) separated from the laminated core (2) is cleaned with acetone, and the adhesive layer (11b) is completely removed from the surface of each core sheet (1a). After that, the two core sheets (1a) (base steel plate (11a)) from which the adhesive layer (11b) has been removed are overlapped, and the iron loss W is measured by a magnetic property measuring device (BST-L) manufactured by BROCKHAUS. 15 / 50(W / kg) is measured. In addition, when two core sheets (1a) are separated from the laminated core (2) and the adhesive layer (11b) is removed as described above, the compressive residual stress applied to the core sheet (1a) by the adhesive layer (11b) during bonding can be removed by the pressurization and heat treatment during the manufacture of the laminated core and by the adhesive layer (11b) while preventing an increase in the iron loss of the base steel sheet (11a) (core sheet (1a)) during the separation of the core sheet (1a) and the removal of the adhesive layer (11b). Therefore, the iron loss of the two base steel sheets (11a) separated from the laminated core (2) and the adhesive layer (11b) removed as described above is considered to be equivalent to the iron loss of the two core sheets (1a) (base steel sheet (11a)) before they were bonded together. By calculating the iron loss deterioration rate of the laminated core (2) based on these two core sheets (1a) (base steel plate (11a)), the effects of iron loss deterioration caused by the pressurization and heat treatment when manufacturing the laminated core (2) and the adhesive layer (11b) can be appropriately evaluated.

[0055] In addition, if the adhesive layer (11b) cannot be removed according to the heating conditions above, the adhesive layer (11b) is dissolved by immersing the laminated core (2) in a solvent, thereby separating the two core sheets (1a) on the surface side of the laminated core (2). In this case as well, the compressive residual stress generated in the base steel plate (11a) during the manufacture (bonding) of the laminated core can be removed while preventing an increase in iron loss of the base steel plate (11a). The solvent used can be determined according to the composition of the adhesive layer (11b). For example, if an epoxy-based resin is used as the adhesive layer (11b), a ketone-based solvent (anone, methyl ethyl ketone, etc.) may be used. In addition, the composition of the adhesive layer (11b) can be inspected by a known method. In addition, a known solvent may also be used for dissolving the adhesive layer (11b).

[0056] In the laminated core (2) according to the present embodiment, the iron loss deterioration rate of the laminated core (2) with respect to the iron loss of the two layers (two sheets in the present embodiment) of the base steel plate (11a) measured as above is 10% or less. Specifically, the iron loss deterioration rate calculated by the following formula (a) is 10% or less.

[0057] Iron loss deterioration rate (%) = ((Iron loss of laminated core - Iron loss of base steel plate of layer 2) / Iron loss of base steel plate of layer 2) × 100 … (a)

[0058] In addition, if the laminated core is one of a plurality of split cores for constituting a stator, the iron loss of the laminated core is measured as follows. As shown in FIG. 3(a), if a closed magnetic path can be formed by a single split core (2a) and a U-shaped measuring head (5) of a magnetic property measuring device, the iron loss measured by the split core (2a) alone is considered the iron loss of the laminated core. In this case, the iron loss of the two core sheets on the surface side separated from the split core (2a) is considered the iron loss of the two layers of base steel plates.

[0059] Meanwhile, as shown in FIG. 3(b), if a closed magnetic path cannot be formed by a single split core (2b) and a measuring head (5), a plurality of split cores (2b) are connected so that a closed magnetic path can be formed. Then, the iron loss measured in the state where the plurality of split cores (2b) are connected is taken as the iron loss of the laminated core. In this case, two core sheets on the surface side are separated from each split core (2b), and the iron loss measured by connecting the separated plurality (six sheets in this example) core sheets in the same manner as FIG. 3(b) is taken as the iron loss of the two-layer base steel plate.

[0060] In addition, if the split core is embedded as a stator core of a rotary electric machine, first, the stator core removed from the rotary electric machine is disassembled into a plurality of split cores. Then, the iron loss is measured by the above method described using FIG. 3 (a) or FIG. 3 (b).

[0061] (Configuration of the manufacturing device)

[0062] Next, the manufacturing apparatus (100) will be described in detail. As shown in FIG. 1, the manufacturing apparatus (100) according to the present embodiment is equipped with a base part (10), a punch (12), a blanking die (14), a first holding support part (16), a second holding support part (18), and a heating part (20). Also, although not shown, in the manufacturing apparatus (100), a predetermined processing (such as the formation of a slot) is performed on the steel strip (1) by other punches and dies, etc., even upstream of the punch (12) and the blanking die (14) in the conveying direction of the steel strip (1). For example, as shown in FIG. 10 described below, when a plurality of convex portions (3) are formed on the core sheet (1a) (base steel plate (11a)) at the top of the laminated core (2), press processing is performed to form convex portions on the area that is blanked as the core sheet (1a) having convex portions (3) among the steel strips (1).

[0063] The punch (12) is positioned above the base portion (10) so as to be able to move up and down. The blanking die (14) is positioned below the punch (12). The blanking die (14) has a tubular shape corresponding to the outer shape of the laminated core (2). In this embodiment, the opening edge (14a) on the upper side of the blanking die (14) functions as a cutting edge. In this embodiment, the opening edge (14a) has a circular shape. In this embodiment, the outer shape blanking process is repeatedly performed on the steel strip (1) being conveyed in a predetermined direction by the punch (12) and the blanking die (14), and a plurality of core sheets (1a) are blanked from the steel strip (1).

[0064] In FIG. 1, a virtual line A extending in the vertical direction through the center of the opening edge (14a) of the blanking die (14) is shown as a dashed line. Hereinafter, the diameter direction refers to a direction perpendicular to the virtual line A. Also, hereinafter, the circumference direction refers to the circumferential direction of a virtual circle centered on the center of the opening edge (14a) when viewed from above.

[0065] The first holding support member (16) is positioned below the blanking die (14). In this embodiment, the first holding support member (16) is fixed to the base member (10) using an installation member not shown. In this embodiment, the first holding support member (16) is equipped with a plurality of holding support members (16a) and a plurality of pressing devices (16b).

[0066] A plurality of retaining support members (16a) are arranged side by side in the circumferential direction. Each retaining support member (16a) is provided to be movable in the radial direction. A pressing device (16b) is provided for each retaining support member (16a). The pressing device (16b) is a device that moves the retaining support member (16a) in the radial direction. In the present embodiment, the pressing device (16b) includes, for example, a hydraulic device, and moves the pressing device (16b) in the radial direction by hydraulic pressure.

[0067] Additionally, the first holding support member (16) may be configured to press a plurality of core sheets (1a) blanked by the punch (12) and the blanking die (14) from the side (outer in the diameter direction). Accordingly, for example, any of the holding support members (16a) may be fixed so as not to move in the diameter direction. In this case, a pressing device (16b) does not need to be connected to the fixed holding support member (16a). Furthermore, the configuration of the first holding support member is not limited to the example described above, and the first holding support member may be configured using various known squeeze ring configurations.

[0068] The second holding support member (18) is positioned below the first holding support member (16). In this embodiment, the second holding support member (18) is formed by a separate member from the first holding support member (16). In this embodiment, the second holding support member (18) is provided coaxially with the first holding support member (16). In this embodiment, the second holding support member (18) has a plurality of holding support members (18a) that are movable in the radial direction. Although not illustrated, a biasing device is provided for each holding support member (18a). In this embodiment, the biasing device includes, for example, an elastic member such as a spring, and biases the holding support member (18a) toward the inner side in the radial direction (virtual line A). Furthermore, the configuration of the second holding support member is not limited to the example described above, and the second holding support member can be configured using various known squeeze ring configurations. For example, each holding support member (18a) may be composed of a plurality of members that are stacked in the vertical direction and also connected to each other.

[0069] The heating unit (20) is positioned around the second holding support member (18). In this embodiment, the heating unit (20) is provided below the first holding support member (16). In this embodiment, the heating unit (20) includes a plurality of heating devices (20a). For example, an infrared heating device is used as the heating device (20a). In this embodiment, a heating device (20a) is provided for each holding support member (18a). Furthermore, the configuration of the heating unit (20) is not limited to the example described above, and various heating devices capable of heating the second holding support member (18) (holding support member (18a)) or the core sheet (1a) held and supported by the second holding support member (18) can be used as the heating unit. For example, a high-frequency induction heating device provided to surround the second holding support member (18) may be used as the heating unit.

[0070] (Method for manufacturing a laminated core)

[0071] Next, a method for manufacturing a laminated core (2) using the manufacturing device (100) described above will be explained. In this embodiment, a steel strip (1) is fed in a predetermined direction from a coil (hoop material) not shown by a feeding mechanism (roller, etc.) not shown, and a plurality of core sheets (1a) are blanked from the steel strip (1) by a punch (12) and a blanking die (14) (open edge (14a)).

[0072] As shown in FIG. 4, a plurality of blanked core sheets (1a) are sequentially stacked within a blanking die (14). Additionally, the outer periphery of the core sheet (1a) blanked from the steel strip (1) comes into contact with the inner surface of the blanking die (14), but in this embodiment, no significant pressure is applied to the core sheet (1a) from the blanking die (14). Because of this, the core sheet (1a) blanked from the steel strip (1) by the punch (12) and the blanking die (14) (open edge (14a)) is not held and supported by the inner surface of the blanking die (14) and moves downward within the blanking die (14).

[0073] As shown in FIG. 5, a plurality of core sheets (1a) are sequentially pressed into the first holding support (16) by further blanking the core sheet (1a) from the steel bar (1). In this embodiment, whenever a new core sheet (1a) is blanked by the punch (12) and the blanking die (14), one core sheet (1a) is pressed into the first holding support (16) from the blanking die (14).

[0074] As described above, the first holding support member (16) is configured to press the core sheet (1a) from the side (outer in the diameter direction). In this embodiment, a plurality of core sheets (1a) are maintained in a state of being pressed from the side within the first holding support member (16). Because of this, the pressure generated between the core sheets (1a) adjacent in the vertical direction by the punch (12) pressing the plurality of core sheets (1a) downward can be maintained within the first holding support member (16). As a result, the plurality of core sheets (1a) are pressed in the vertical direction, and the base steel plates (11a) adjacent in the vertical direction within the first holding support member (16) are compressed through the adhesive layer (11b). In this embodiment, a pressure greater than the pressure generated between adjacent core sheets (1a) in the vertical direction due to the self-weight of the plurality of core sheets (1a) can be generated and maintained between adjacent core sheets (1a) in the vertical direction within the first holding support member (16). Additionally, the adjacent core sheets (1a) in the vertical direction that are pressed within the first holding support member (16) are fixed with a weaker force (adhesive force) than the core sheets (1a) after being heated and pressed within the second holding support member (18) described later. That is, within the first holding support member (16), the adjacent core sheets (1a) in the vertical direction are bonded (temporarily bonded). Furthermore, it is preferable to set the pressure applied from the punch (12) to the plurality of core sheets (1a) to 2.0 MPa or less, and it is more preferable to make it close to the pressure required to blank the core sheets (1a) (blanking pressure: for example, about 0.1 MPa). The above-mentioned pressure may be set to, for example, 1.8 MPa or less, or 1.0 MPa or less. In addition, it may be set to 0.1 MPa or more.Additionally, the pressure applied from the first holding support member (16) (in this embodiment, the holding support member (16a)) to the outer periphery of the core sheet (1a) is set to a size that, for example, prevents the core sheet (1a) from falling. In this embodiment, the pressure is set such that the static friction force generated between the core sheet (1a) and the first holding support member (16) is greater than the weight of the core sheet (1a).

[0075] In addition, as described above, no significant pressure is applied to the core sheet (1a) from the inner surface of the blanking die (14). Therefore, even if pressure is generated between adjacent core sheets (1a) in the vertical direction within the blanking die (14) by the punch (12) pressing the multiple core sheets (1a) downward, that state is not maintained. Consequently, the multiple core sheets (1a) are not compressed against each other within the blanking die (14).

[0076] In this embodiment, the first holding support member (16) maintains a plurality of core sheets (1a) at a temperature below the softening temperature of the adhesive layer (11b). By doing so, the adhesive layer (11b) between a pair of base steel plates (11a) adjacent in the vertical direction within the first holding support member (16) is prevented from softening before the pair of base steel plates (11a) are compressed together. When the plurality of core sheets (1a) are maintained at a temperature below the softening temperature of the adhesive layer (11b) in the first holding support member (16), even when the pressure and heating of the plurality of core sheets (1a) are performed simultaneously, the compressive residual stress generated in the resulting laminated core can be reduced, and the increase in iron loss can be suppressed. In addition, the holding temperature of the plurality of core sheets (1a) in the first holding support (16) is not limited to being lower than the softening temperature of the adhesive layer (11b), but for example, it can be set to a temperature at least 10°C lower than the softening temperature of the adhesive layer (11b), or at least 30°C lower than the softening temperature of the adhesive layer (11b). The lower limit of the holding temperature in the first holding support (16) is not particularly limited, but for example, it can be 0°C or higher, or room temperature (20°C) or higher, or 40°C or higher. In addition, the holding temperature of the plurality of core sheets (1a) (temperature of the adhesive layer (11b)) in the first holding support (16) can be measured by embedding a thermocouple thermometer or a radiation thermometer in the first holding support (16). In this embodiment, in addition to controlling the output of the heating unit (20) so that the temperature of the core sheet (1a) (adhesive layer (11b)) within the first holding support member (16) becomes below the softening temperature based on the holding temperature (temperature of the adhesive layer (11b)) measured as above, the length of the first holding support member (16) in the vertical direction may be adjusted, or an insulating member may be provided at the boundary between the first holding support member (16) and the second holding support member (18).In addition, a heating test of the heating unit (20) may be performed in advance, and a simulation may be performed on the temperature rise behavior of the adhesive layer (11b) due to heating of the heating unit (20). Then, based on the temperature rise behavior of the adhesive layer (11b) obtained by the simulation, output control of the heating unit (20) may be performed. In addition, although the temperature within the first holding support unit (16) may rise under the influence of the temperature within the second holding support unit provided in series with the first holding support unit (16), the temperature within the first holding support unit (16) can be controlled to be below the softening temperature of the adhesive layer (11b) by the method described above. Furthermore, in this embodiment, the holding temperature in the first holding support unit (16) must be below the softening temperature of the adhesive layer (11b), and the effect of this embodiment is not affected by the presence or absence of a heating unit in the first holding support unit (16) and the presence or absence of intentional heating of the core sheet (1a). Meanwhile, in order to further reduce the compressive residual stress occurring in the core sheet (1a), it is desirable to suppress the heating of multiple core sheets (1a) in the first holding support member (16). For example, in order to simplify the device and further reduce the compressive residual stress occurring in the core sheet (1a), it is desirable not to provide a heating member (20) in the first holding support member (16). For this reason, in the present embodiment, the heating member (20) is positioned below the lower end of the first holding support member (16).

[0077] In addition, in order to prevent the adhesive layer (11b) between the pair of base steel plates (11a) adjacent in the vertical direction from softening before the pair of base steel plates (11a) are compressed together, the vertical length of the portion of the first holding support member (16) that contacts the core sheet (1a) (in this embodiment, the length of the holding support member (16a)) is preferably 5 mm or more, and preferably 10 mm or more. The upper limit of the vertical length of the portion of the first holding support member (16) that contacts the core sheet (1a) is not particularly limited, but, for example, it may be 160 mm or less, and may be 20 mm or less. In this case, sufficient time can be secured to compress the core sheets (1a) together in the first holding support (16), so the core sheets (1a) can be compressed more appropriately before the adhesive layer (11b) softens.

[0078] The softening temperature of the adhesive layer (11b) can be measured by TMA (thermomechanical analysis). Specifically, a cut plate of 7 mm × 7 mm or less is taken from the steel strip (1), and the softening temperature of the adhesive layer (11b) is measured in penetration mode using the taken cut plate. The needle load is set to 0.5 kgf to 2.0 kgf, and the heating rate is set to 15°C / min. In addition, the needle load is appropriately adjusted based on the penetration depth of the needle. Specifically, first, a measurement is performed with a needle load of 0.5 kgf, and if the penetration depth of the needle does not match the thickness of the adhesive layer (11b), the needle load is increased so that the penetration depth of the needle matches the thickness of the adhesive layer (11b), and the measurement is performed again. For example, the needle load is set to 1.5 kgf and the measurement is performed again. The needle load for matching the penetration depth of the needle to the thickness of the adhesive layer (11b) also varies depending on the hardness of the adhesive layer (11b).

[0079] As shown in FIG. 6, as core sheets (1a) are further blanked from the steel band (1), a plurality of core sheets (1a) are sequentially pressed into the second holding support (18). In this embodiment, whenever a new core sheet (1a) is blanked by the punch (12) and the blanking die (14), one core sheet (1a) is pressed from the first holding support (16) into the second holding support (18).

[0080] A core sheet (1a) pressed into the second holding support member (18) is held and supported from the side (outer in the diameter direction) by the second holding support member (18) (multiple holding support members (18a)), heated by the heating member (20), and also pressed by the punch (12). In this embodiment, the heating member (20) heats the multiple core sheets (1a) held and supported within the second holding support member (18) to a temperature higher than the softening temperature of the adhesive layer (11b). As a result, the adhesive layer (11b) of each core sheet (1a) within the second holding support member (18) softens and hardens, and the multiple core sheets (1a) are fixed to each other. Additionally, the multiple core sheets (1a) are pressed into the second holding support member (18) one by one from the lower side, and are heated sequentially starting from the one pressed into the second holding support member (18). Accordingly, the multiple stacked core sheets (1a) are heated sequentially from the one located on the lower side to the one located on the upper side, and are heated gradually from the lower side. In addition, in this embodiment, the heating unit (20) heats the second holding support unit (18) so that the temperature of the adhesive layer (11b) within the second holding support unit (18) rises to a temperature above the softening temperature. In addition, in this embodiment, the lateral pressure applied from the second holding support unit (18) to the stacked core (2) is set to a size that prevents the stacked core (2) from falling. In this embodiment, the pressure is set so that the static friction force generated between the stacked core (2) and the second holding support unit (18) is greater than the weight of the stacked core (2). Additionally, the heating temperature in the second holding support (18) may be a temperature higher than the softening temperature of the adhesive layer (11b), but for example, it may be a temperature 10°C or higher than the softening temperature of the adhesive layer (11b), or a temperature 40°C or higher than the softening temperature of the adhesive layer (11b). The upper limit of the heating temperature in the second holding support (18) is not particularly limited, but for example, it may be 200°C or lower.Additionally, if the adhesive forming the adhesive layer (11b) is a thermosetting resin, the heating unit (20) heats a plurality of core sheets (1a) held and supported by the second holding support unit (18) to a temperature higher than the curing temperature of the adhesive layer (11b).

[0081] Additionally, when an infrared heating device is used as the heating unit (20), each core sheet (1a) can be gradually heated from the outer periphery toward the center. By doing so, the adhesive layer (11b) of each core sheet (1a) can be gradually cured from the outer periphery toward the center. In this case, it is possible to prevent the adhesive from leaking between the upper and lower adjacent base steel plates (11a) within the second holding support (18). In this regard, it is preferable to use an infrared heating device as the heating unit (20). In this embodiment, for example, an infrared heating device that emits near-infrared rays with a wavelength of 750 to 1000 nm is used.

[0082] Finally, as shown in FIG. 1, a plurality of core sheets (1a) fixed to each other within the second holding support member (18) are discharged from the second holding support member (18) as a laminated core (2). In this way, a laminated core (2) is obtained. In addition, in this embodiment, the thickness of the core sheet (1a) (steel strip (1)) is, for example, 0.1 mm to 0.5 mm, and the mass of the laminated core (2) is, for example, 0.1 kg to 6.0 kg. When manufacturing a larger laminated core (2), for example, a laminated core (2) with a mass exceeding 6.0 kg, it may be difficult to hold and support the laminated core (2) solely by the force provided by the biasing device in the second holding support member (18). In such cases, it is preferable to support the laminated core (2) from below by a support device (26), as shown in FIG. 9 which will be described later.

[0083] (Effects of this embodiment)

[0084] In the manufacturing apparatus (100) according to the present embodiment, the first holding support member (16) maintains a plurality of core sheets (1a) at a temperature below the softening temperature of the adhesive layer (11b). By doing so, the adhesive layer (11b) can be prevented from softening before the core sheets (1a) adjacent in the vertical direction within the first holding support member (16) are pressed together, and the compressive residual stress generated in the core sheets (1a) by the pressing and heating of the plurality of core sheets (1a) can be reduced.

[0085] Here, as a result of a detailed examination by the inventors, it was found that when heating and pressurizing at a temperature higher than the softening temperature of the adhesive layer (11b) are simultaneously initiated for a plurality of core sheets (1a), residual stress in the compression direction (residual stress inward in the diameter direction) may occur in the core sheets (1a). Specifically, when a plurality of core sheets (1a) are heated to a temperature higher than the softening temperature of the adhesive layer (11b) and pressurized, the softening of the adhesive layer (11b) between a pair of core sheets (1a) adjacent in the vertical direction proceeds before the pair of core sheets (1a) are pressurized. In this case, residual stress in the compression direction is likely to occur in the base steel plate (11a) due to the difference in the amount of thermal expansion between the adhesive layer (11b) and the base steel plate (11a) above or below it, and the shrinkage of the adhesive layer (11b).

[0086] Meanwhile, it was found that when the upper and lower adjacent core sheets (1a) are first pressed while maintaining a temperature below the softening temperature of the adhesive layer (11b), and then the upper and lower adjacent core sheets (1a) are heated and pressed to a temperature above the softening temperature of the adhesive layer (11b) to bond them, the compressive residual stress generated in the core sheets (1a) by the pressing and heating can be reduced. Furthermore, when a plurality of core sheets (1a) pressed in the upper and lower directions are heated sequentially starting from the lower core sheet (1a), the adhesive layer (11b) and the upper and lower base steel plates (11a) expand and contract to follow each other. In this case, the occurrence of compressive residual stress in the base steel plate (11a) is further suppressed. Therefore, in the manufacturing apparatus (100) according to the present embodiment, as described above, in the first holding support member (16), a plurality of core sheets (1a) are pressurized while maintaining a temperature below the softening temperature of the adhesive layer (11b). Then, in the second holding support member (18), the plurality of core sheets (1a) are heated and pressurized to a temperature above the softening temperature of the adhesive layer (11b), thereby bonding and fixing the plurality of core sheets (1a) to each other. By doing so, it is possible to prevent the adhesive layer (11b) from softening before the core sheets (1a) adjacent in the vertical direction within the first holding support member (16) are pressurized. As a result, the occurrence of residual stress in the compression direction in each base steel plate (11a) in the first holding support member (16) can be suppressed, and the iron loss of the laminated core (2) can be reduced. In addition, in the manufacturing apparatus (100) according to the present embodiment, a blanking die (14), a first holding support member (16), and a second holding support member (18) are arranged continuously in the vertical direction. In this configuration, a plurality of core sheets (1a) pressed into the lower side by a punch (12) are heated one sheet at a time from the lower side in the second holding support member (18) to a temperature higher than the softening temperature of the adhesive layer (11b).In the second holding support member (18), by gradually heating a plurality of core sheets (1a) from the lower side to a temperature above the softening temperature of the adhesive layer (11b), the compressive residual stress generated in each base steel plate (11a) can be reduced, and the iron loss of the laminated core (2) can be made smaller.

[0087] In addition, in order to obtain a laminated core of a suitable shape, it is necessary to cure the adhesive layer while applying a large pressure exceeding 2.0 MPa to a plurality of core sheets from a punch. However, in this case, the frictional force between the adhesive layer and the base steel plate increases, and compressive residual stress occurs in the base steel plate, thereby increasing iron loss. In contrast, in the present embodiment, the outer periphery of the plurality of core sheets (1a) is supported from the side (pressed in the present embodiment) by the second holding support member (18), and the plurality of core sheets (1a) are heated. By doing so, the adhesive layer (11b) between the plurality of core sheets (1a) (base steel plate (11a)) can be cured without applying a large pressure in the lamination direction to the plurality of core sheets (1a). In this case, the frictional force between the adhesive layer (11b) and the base steel plate (11a) can be prevented from increasing, and the occurrence of compressive residual stress in the base steel plate (11a) can be sufficiently suppressed. By doing so, even when the pressure applied from the punch (12) to the multiple core sheets (1a) is low at 2.0 MPa or less, the multiple core sheets (1a) can be properly bonded and a laminated core (2) of a suitable shape can be obtained.

[0088] In addition, in the manufacturing device (100) according to the present embodiment, the first holding support member (16) and the second holding support member (18) are formed by separate members. More specifically, the portion of the first holding support member (16) that contacts the core sheet (1a) (in the present embodiment, the holding support member (16a)) and the portion of the second holding support member (18) that contacts the core sheet (1a) (in the present embodiment, the holding support member (18a)) are formed by separate members. As a result, heat transfer from the second holding support member (18) to the first holding support member (16) is suppressed, and the temperature rise of the first holding support member (16) is suppressed. Consequently, the temperature rise of a plurality of core sheets (1a) within the holding support member (16a) can be easily suppressed.

[0089] (Variation example)

[0090] In the above-described embodiment, although the case in which a single adhesive layer (11b) is provided on the surface of the base steel plate (11a) was described, multiple layers (multiple types) of adhesive layers may be provided on the surface of the base steel plate. In this case, multiple core sheets are supported in the first holding support so that all adhesive layers reach a temperature below the softening temperature. Additionally, the heating unit heats the multiple core sheets supported in the second holding support so that all adhesive layers reach a temperature above the softening temperature. The same applies to the embodiments described later.

[0091] In the above-described embodiment, the first holding support member (16) and the second holding support member (18) are provided independently of each other, but as shown in FIG. 7, the first holding support member (16) and the second holding support member (18) may be connected to each other by a plurality of connecting members (22). In this case, since the first holding support member (16) and the second holding support member (18) can be linked together, the configuration of the first holding support member (16) and the second holding support member (18) (configuration for pressing the holding support member (16a) and the holding support member (18a)) can be simplified. Additionally, the connecting members (22) may be concave and convex portions formed on the holding support member (16a) and the holding support member (18a). In this case, for example, the holding support member (16a) and the holding support member (18a) can be fixed by caulking the concave and convex portions. In addition, the connecting part (22) may be a fastening member such as a bolt and a nut.

[0092] In the above-described embodiment, a second holding support member (18) is positioned directly below the first holding support member (16), but as shown in FIG. 8, the first holding support member (16) and the second holding support member (18) may be connected through an insulating member (24) having a lower thermal conductivity than the holding support member (18a) (the part of the second holding support member (18) that contacts the core sheet (1a)). In this case, the transfer of heat from the second holding support member (18) to the first holding support member (16) can be sufficiently suppressed, and the temperature rise of the first holding support member (16) can be sufficiently prevented. In addition, in this embodiment, the insulating member (24) forms a connecting part that connects the first holding support member (16) and the second holding support member (18).

[0093] In the above-described embodiment, a plurality of core sheets (1a) are supported by pressing the plurality of core sheets (1a) from the side in the first holding support member (16) and the second holding support member (18), but as shown in FIG. 9, the plurality of core sheets (1a) may be further supported from below by the support device (26). By doing so, the plurality of core sheets (1a) can be supported more stably. In addition, the support device (26) is a device that supports the plurality of core sheets (1a) from below by the elastic force of an elastic member, such as hydraulics or a spring, for example.

[0094] In the above-described embodiment, all core sheets (1a) (base steel plate (11a)) constituting the laminated core (2) have the same shape, but the shape of the laminated core (2) is not limited to the above-described example, and the shape of some core sheets (1a) of the laminated core (2) may be different from the shape of other core sheets (1a). For example, as shown in FIG. 10, a plurality of convex portions (3) protruding outward in the lamination direction may be formed on the core sheet (1a) (base steel plate (11a)) at one end (in this embodiment, the upper end) in the lamination direction. When manufacturing a plurality of laminated cores (2) continuously, by forming a plurality of convex portions (3) as described above on the core sheet (1a) at the upper end of each laminated core (2), the plurality of laminated cores (2) can be easily separated. As a result, a plurality of laminated cores (2) can be manufactured efficiently.

[0095] (Second embodiment)

[0096] FIG. 11 is a schematic cross-sectional view illustrating a manufacturing apparatus for a laminated core according to a second embodiment of the present invention. The manufacturing apparatus (100a) according to the present embodiment differs from the manufacturing apparatus (100) shown in FIG. 1 in that a first holding support member (60) is provided instead of a first holding support member (16), and a second holding support member (80) is provided instead of a second holding support member (18).

[0097] In this embodiment as well, the first holding support member (60) has a plurality of holding support members (16a) and a plurality of pressing devices (16b), similar to the first holding support member (16) described above, and the second holding support member (80) has a plurality of holding support members (18a), similar to the second holding support member (18) described above. However, in this embodiment, the portion in the first holding support member (60) that contacts the core sheet (1a) and the portion in the second holding support member (80) that contacts the core sheet (1a) are composed of the same member. Specifically, each holding support member (16a) and the holding support member (18a) located below it are composed of the same member. Furthermore, in this embodiment, the holding support member (16a) is a portion that maintains a plurality of core sheets (1a) at a temperature below the softening temperature of the adhesive layer (11b). In addition, in this embodiment, the upper portion of the retaining support member (18a) is the portion that contacts the core sheet (1a) when the temperature of the core sheet (1a) reaches the softening temperature of the adhesive layer (11b).

[0098] In this embodiment as well, the vertical length of the portion of the first holding support member (60) that contacts the core sheet (1a) (in this embodiment, the length of the holding support member (16a)) is preferably 5 mm or more, and preferably 10 mm or more. In addition, the vertical distance between the upper end of the portion of the first holding support member (60) that contacts the core sheet (1a) (in this embodiment, the upper end of the holding support member (16a)) and the upper end of the heating member (20) is preferably 5 mm or more, and preferably 10 mm or more. In addition, in this embodiment as well, the pressing force applied from the punch (12) to the plurality of core sheets (1a) is preferably set to 2.0 MPa or less, may be set to 1.8 MPa or less, and is more preferably set close to the pressure required to blank the core sheet (1a) (blanking pressure: for example, about 0.1 MPa). Accordingly, the pressure applied from the punch (12) to the multiple core sheets (1a) may be, for example, 0.1 MPa or more. In addition, the pressure applied from the first holding support member (60) (in this embodiment, the holding support member (16a)) to the outer periphery of the core sheet (1a) is set to a size that, for example, prevents the core sheet (1a) from falling. In this embodiment, the pressure is set so that the static friction force generated between the core sheet (1a) and the first holding support member (60) becomes greater than the weight of the core sheet (1a).

[0099] In the manufacturing apparatus (100a) according to the present embodiment, a plurality of core sheets (1a) are blanked from a steel strip (1) by means of a punch (12) and a blanking die (14), just as in the manufacturing apparatus (100) according to the first embodiment described above. While pressing the outer periphery of the blanked plurality of core sheets (1a) from the side in the first holding support member (60), the plurality of core sheets (1a) are pressed downward by means of the punch (12), thereby compressing the plurality of core sheets (1a). The plurality of core sheets (1a) compressed in the first holding support member (60) are heated to a temperature above the softening temperature of the adhesive layer (11b) by means of a heating unit (20) in the second holding support member (80). As a result, the adhesive layer (11b) of each core sheet (1a) softens and hardens in the second holding support member (80), and the plurality of core sheets (1a) are fixed to each other. After that, multiple core sheets (1a) fixed to each other are discharged from the second holding support (80) as a stacked core (2).

[0100] In the manufacturing apparatus (100a) according to the present embodiment, in the first holding support member (60), a plurality of core sheets (1a) are maintained at a temperature below the softening temperature of the adhesive layer (11b). By doing so, it is possible to prevent the adhesive layer (11b) from softening before the core sheets (1a) adjacent in the vertical direction within the first holding support member (60) are pressed against each other. As a result, the occurrence of residual stress in the compression direction in each base steel plate (11a) can be suppressed, and the iron loss of the laminated core (2) can be reduced.

[0101] In addition, in the manufacturing device (100a) according to the present embodiment, the first holding support member (60) and the second holding support member (80) can be linked together, so the configuration of the first holding support member (60) and the second holding support member (80) (configuration for pressing the holding support member (16a) and the holding support member (18a)) can be simplified. In the manufacturing device (100a) shown in FIG. 11, the pressing device (16b) is installed on the holding support member (16a), but the pressing device (16b) may also be installed on the holding support member (18a). In this case, the pressing device (16b) can move the holding support member (16a) in the radial direction through the holding support member (18a).

[0102] In this embodiment as well, the outer periphery of the multiple core sheets (1a) is supported from the side (pressed in this embodiment) in the second holding support member (80), and the multiple core sheets (1a) are heated. By doing so, the adhesive layer (11b) between the multiple core sheets (1a) (base steel plate (11a)) can be cured without applying a large pressure in the stacking direction to the multiple core sheets (1a). In this case, the frictional force between the adhesive layer (11b) and the base steel plate (11a) can be prevented from increasing, and the occurrence of compressive residual stress in the base steel plate (11a) can be sufficiently suppressed. By doing so, even when the pressure applied from the punch (12) to the multiple core sheets (1a) is low at 2.0 MPa or less, the multiple core sheets (1a) can be properly bonded to obtain a laminated core (2) of a suitable shape.

[0103] Additionally, although a detailed description is omitted, another holding support (e.g., a known squeeze ring) may be provided below the second holding support (80).

[0104] The present invention will be explained more specifically below by way of examples, but the present invention is not limited to these examples.

[0105] Examples

[0106] The laminated cores of Examples 1 to 7 and Comparative Examples 1 to 4 were manufactured using a manufacturing apparatus having the same configuration as the manufacturing apparatus (100) shown in FIG. 1. Additionally, the position of the heating unit (20) was appropriately adjusted. Furthermore, the laminated cores of Comparative Examples 5 and 6 were manufactured using a manufacturing apparatus having the same configuration as the manufacturing apparatus (100) shown in FIG. 1, except that it does not have a first holding support unit (16). In both the Examples and Comparative Examples, the laminated core was composed of two annular core sheets. Additionally, the holding temperature in the first holding support unit (16) was a temperature raised by the influence of the heating temperature of the adjacent second holding support unit (18). As the base steel sheet, a non-oriented electrical steel sheet was used. The adhesive layer of the laminated core of Examples 1 to 3, 6 and Comparative Examples 1, 2, and 5 was formed by an epoxy-based resin and an amine-based curing agent, and the adhesive layer of the laminated core of Examples 4, 5, 7 and Comparative Examples 3, 4, and 6 was formed by an acrylic-based resin and an amine-based curing agent.

[0107] For the laminated cores of Examples 1 to 7 and Comparative Examples 1 to 6 manufactured, the iron loss degradation rate was measured by the method described above. Specifically, first, the iron loss W of the laminated cores of Examples 1 to 7 and Comparative Examples 1 to 6 was measured. 15 / 50 (W / kg) was measured using a magnetic property measuring device (BST-L) manufactured by BROCKHAUS. Next, the adhesive layer was carbonized by heating the laminated core at 400°C for 12 hours in a furnace, and the two core sheets of the laminated core were separated. Then, the surfaces of the two separated core sheets were cleaned with acetone to completely remove the adhesive layer from the surface of each core sheet. Afterward, the two core sheets (base steel plates) were stacked, and the iron loss W was measured using a magnetic property measuring device (BST-L) manufactured by BROCKHAUS. 15 / 50(W / kg) was measured. In addition, the iron loss degradation rate of each laminated core of the examples and comparative examples was calculated using the above-described equation (a). Furthermore, when comparing the iron loss of a three-layer or higher laminated core manufactured under the same conditions with the iron loss of a two-layer laminated core, the iron loss of the two-layer laminated core is typically higher. For this reason, the iron loss degradation rate of the two-layer laminated core was evaluated in the examples and comparative examples. If the iron loss degradation rate of the two-layer laminated core obtained by the above-described equation (a) is 10% or less, it is believed that the iron loss degradation rate of a three-layer or higher laminated core manufactured under the same conditions as that laminated core will also be 10% or less. Additionally, the magnetic flux density during iron loss measurement was set to 1.5T, and the frequency was set to 50Hz. The type of resin in the adhesive layer, the softening temperature of the adhesive layer, the manufacturing conditions of the laminated core, the iron loss measurement results, and the results of calculating the iron loss degradation rate are shown in Table 1 below.

[0108]

[0109] In addition, the softening temperature of the adhesive layer in Table 1 was measured by taking a cut plate from the steel strip that serves as the material for the core sheet and using TMA (thermomechanical analysis). In addition, the holding temperature of the first holding support in Table 1 refers to the maximum temperature of the core sheet within the first holding support (16). In addition, the heating temperature of the second holding support in Table 1 refers to the maximum temperature of the core sheet within the second holding support (18). However, for Comparative Examples 5 and 6, the heating temperature of the second holding support refers to the temperature of the core sheet at the upper end within the second holding support (18). In addition, for Comparative Examples 1 to 4, the minimum temperature of the core sheet within the first holding support (16) was all above the softening temperature. The temperature of the core sheet within the first holding support (16) was measured by arranging a plurality of thermocouple thermometers in the first holding support (16) so that they are positioned side by side in the vertical direction. Likewise, a plurality of thermocouple thermometers were arranged in the second holding support (18) so as to be positioned side by side in the vertical direction, and the temperature of the core sheet within the second holding support (18) was measured.

[0110] As shown in Table 1, in Examples 1 to 7, where the core sheet in the first holding support (16) was maintained at a temperature below the softening temperature of the adhesive layer, the iron loss degradation rate of the laminated core was 10% or less, and iron loss degradation could be suppressed. In particular, in Examples 1 to 5, where the pressure applied from the punch (12) to the core sheet was set to 2.0 MPa or less, the iron loss degradation rate of the laminated core was 7% or less, and iron loss degradation could be sufficiently suppressed.

[0111] Meanwhile, in Comparative Examples 1 to 4, where the core sheet was maintained at a temperature higher than the softening temperature of the adhesive layer within the first holding support (16), the iron loss degradation rate of the laminated core was 14% or higher. In addition, in Comparative Examples 5 and 6, where the first holding support (16) was not provided and the core sheet was maintained at a temperature higher than the softening temperature of the adhesive layer in the upper part of the second holding support (18), the iron loss degradation rate of the laminated core was 18% or higher. Thus, in Comparative Examples 1 to 6, the iron loss degradation of the laminated core increased compared to Examples 1 to 7. Industrial applicability

[0112] According to the present invention, a laminated core with low iron loss can be manufactured. Explanation of the symbols

[0113] 1: Gangdae 2: Stacked Core 3: Convex part 10: Bass section 12: Punch 14: Blanking Die 16, 60: 1st holding support 18, 80: Second holding support section 20: Heating part 22: Connection 24: Insulating element 26: Support device 100, 100a: Manufacturing device

Claims

Claim 1 A laminated core in which a plurality of electrical steel sheets are laminated through an adhesive layer, wherein the iron loss degradation rate of the laminated core with respect to two layers of electrical steel sheets separated from the laminated core is 10% or less. Claim 2 A laminated core according to claim 1, wherein a plurality of convex portions protruding outwardly in the lamination direction are formed on the electrical steel sheet at one end portion in the lamination direction. Claim 3 A manufacturing apparatus comprising a punch, a blanking die disposed below the punch, a first holding support disposed below the blanking die, a second holding support disposed below the first holding support, and a heating unit disposed around the second holding support, wherein a plurality of core sheets are blanked from a steel strip having a thermosetting adhesive layer on its surface by the punch and the blanking die, the outer periphery of the blanked plurality of core sheets is pressed from the side by the first holding support, the plurality of core sheets are pressed downward by the punch, the plurality of core sheets pressed downward by the punch are held and supported from the side within the second holding support and heated by the heating unit, the first holding support maintains the plurality of core sheets at a temperature below the softening temperature of the adhesive layer, and the heating unit heats the plurality of core sheets held and supported within the second holding support to a temperature above the softening temperature of the adhesive layer. Claim 4 A method for manufacturing a laminated core according to paragraph 3, wherein the vertical length of the portion in contact with the core sheet in the first holding support is 5 mm or more. Claim 5 A method for manufacturing a laminated core, wherein, in claim 3 or 4, the punch presses the plurality of core sheets with a pressing force of 2.0 MPa or less. Claim 6 A method for manufacturing a laminated core, wherein, in paragraph 3 or 4, the heating unit comprises an infrared heating device. Claim 7 An apparatus for manufacturing a laminated core by blanking a plurality of core sheets from a steel strip having an adhesive layer on its surface and bonding the obtained plurality of core sheets together, comprising a punch, a blanking die disposed below the punch, a first holding support disposed below the blanking die, a second holding support disposed below the first holding support, and a heating unit disposed around the second holding support. A plurality of core sheets are blanked from a steel strip by the punch and the blanking die. The outer periphery of the blanked plurality of core sheets is pressed from the side by the first holding support, and the plurality of core sheets are pressed downward by the punch. The plurality of core sheets pressed downward by the punch are held and supported from the side within the second holding support while being heated by the heating unit. In the first holding support, the plurality of core sheets are maintained at a temperature below the softening temperature of the adhesive layer. The heating unit holds and supports the plurality of core sheets within the second holding support, and the adhesive layer A manufacturing device for laminated cores that heats to a temperature above the softening temperature. Claim 8 A manufacturing apparatus for a laminated core according to claim 7, wherein the vertical length of the portion in contact with the core sheet in the first holding support is 5 mm or more. Claim 9 A manufacturing apparatus for a laminated core, wherein, in claim 7 or 8, the punch presses the plurality of core sheets with a pressing force of 2.0 MPa or less. Claim 10 In claim 7 or 8, the heating unit comprises an infrared heating device, forming a manufacturing apparatus for a laminated core.

Images