Laminated core, and manufacturing apparatus and manufacturing method therefor

Abstract

A manufacturing apparatus 100 comprises a punch 12, a punching die 14, a first holding part 16, a second holding part 18, and a heating part 20. A plurality of core sheets 1a are punched from a steel strip 1 by the punch 12 and the punching die 14, the plurality of punched core sheets 1a are pressed downward by the punch 12 while the outer peripheral parts of the plurality of core sheets 1a are pressed from the side by the first holding part 16, and the plurality of core sheets 1a being pressed downward by the punch 12 are heated by the heating part 20 while being held in the second holding part 18. The first holding part 16 holds the plurality of core sheets 1a at a temperature lower than the softening temperature of an adhesive layer 11b, and the heating part 20 heats the plurality of core sheets 1a held in the second holding part 18 to a temperature equal to or higher than the softening temperature.

Description

Laminated core, and manufacturing device and method thereof

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

[0002] Conventionally, laminated cores having a configuration in which a plurality of electromagnetic steel sheets are laminated have been used as cores for rotating electrical machines, etc. One known method for manufacturing laminated cores is to punch core sheets of a predetermined shape from a steel strip to which an adhesive has been applied, and then bond the resulting core sheets together to manufacture the laminated core.

[0003] For example, in the manufacturing method of a laminated core disclosed in Patent Document 1, core sheets punched out of a strip-shaped steel sheet by an outline punching punch are forced into an outline punching die. The core sheets forced into the outline punching die are stacked on top of the previously punched core sheets, and are then sequentially forced into a squeeze ring below the outline punching die. The core sheets forced into the squeeze ring are pressed against the inner circumferential surface of the squeeze ring while moving, thereby adhering to one another. At this time, the adhesive between each core sheet is hardened by the heat of a heater, and a laminated core is formed in which a predetermined number of core sheets are fixed together.

[0004] JP 2009-297758 A

[0005] The method disclosed in Patent Document 1 allows for the continuous punching of the thin core plates using a punching die and the continuous application of pressure and heat to the multiple thin core plates in a squeeze ring, thereby enabling efficient production of laminated cores.

[0006] However, as a result of research by the inventors, it was found that when multiple iron core thin plates are pressurized and heated simultaneously as described above, compressive residual stress occurs in the resulting laminated iron core, which can increase iron loss.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a laminated core with low iron loss, as well as a method and apparatus for manufacturing the same.

[0008] A laminated core according to one embodiment of the present invention is a laminated core in which a plurality of electromagnetic steel sheets are laminated together via an adhesive layer, and is characterized in that the iron loss degradation rate of the laminated core relative to two layers of electromagnetic steel sheets separated from the laminated core is 10% or less.

[0009] The electromagnetic steel sheets at one end in the lamination direction of the laminated core may be formed with a plurality of protrusions that protrude outward in the lamination direction.

[0010] A method for manufacturing a laminated core according to one embodiment of the present invention is characterized in that, in a manufacturing apparatus comprising a punch, a punching die arranged below the punch, a first holding section arranged below the punching die, a second holding section arranged below the first holding section, and a heating section arranged around the second holding section, the punch and the punching die are used to punch out multiple core sheets from a steel strip having a thermosetting adhesive layer on its surface, the punch presses the multiple core sheets downward while the first holding section applies pressure to the outer peripheries of the punched multiple core sheets from the sides, the punch presses the multiple core sheets downward, the multiple core sheets pressed downward by the punch are held in the second holding section and heated by the heating section, the first holding section holds the multiple core sheets at a temperature below the softening temperature of the adhesive layer, and the heating section heats the multiple core sheets held in the second holding section to a temperature equal to or higher than the softening temperature of the adhesive layer.

[0011] Furthermore, an apparatus for manufacturing a laminated core according to one embodiment of the present invention is an apparatus for manufacturing a laminated core by punching a plurality of core sheets from a steel strip having an adhesive layer on its surface and bonding the obtained plurality of core sheets to each other, and comprises: a punch; a punching die arranged below the punch; a first holding section arranged below the punching die; a second holding section arranged below the first holding section; and a heating section arranged around the second holding section, wherein the apparatus punches a plurality of core sheets from the steel strip using the punch and the punching die; the punch presses the plurality of core sheets downward while the first holding section presses the outer peripheries of the punched core sheets from the sides; the punch presses the plurality of core sheets downward while holding the plurality of core sheets pressed downward by the punch in the second holding section and heats them using the heating section; the first holding section holds the plurality of core sheets at a temperature below the softening temperature of the adhesive layer; and the heating section heats the plurality of core sheets held in the second holding section to a temperature equal to or higher than the softening temperature of the adhesive layer.

[0012] The length in the vertical direction of the portion of the first holding portion that contacts the core sheet may be 5 mm or more.

[0013] The punch may press the core sheets with a pressure of 2.0 MPa or less.

[0014] The heating unit may include an infrared heating device.

[0015] According to the present invention, a laminated core with low core loss can be obtained.

[0016] FIG. 1 is a schematic cross-sectional view showing a laminated core manufacturing apparatus according to a first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view showing the vicinity of the surface of a steel strip. FIG. 3 is a diagram for explaining a method for measuring iron loss. FIG. 4 is a diagram for explaining a laminated core manufacturing method according to a first embodiment of the present invention. FIG. 5 is a diagram for explaining a laminated core manufacturing method according to a first embodiment of the present invention. FIG. 6 is a diagram for explaining a laminated core manufacturing method according to a first embodiment of the present invention. FIG. 7 is a diagram showing a modified example of the manufacturing apparatus. FIG. 8 is a diagram showing another modified example of the manufacturing apparatus. FIG. 9 is a diagram showing another modified example of the manufacturing apparatus. FIG. 10 is a diagram showing a modified example of a laminated core. FIG. 11 is a schematic cross-sectional view showing a laminated core manufacturing apparatus according to a second embodiment of the present invention.

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laminated core and a manufacturing apparatus and method thereof according to embodiments of the present invention will be described below with reference to the drawings.

[0018] (First Embodiment) Fig. 1 is a schematic cross-sectional view showing a laminated core manufacturing apparatus according to a first embodiment of the present invention. The manufacturing apparatus 100 is an apparatus that punches out a plurality of core sheets 1a from a steel strip 1 transported in a predetermined direction and bonds the obtained plurality of core sheets 1a to one another to manufacture a laminated core 2. In this embodiment, the laminated core 2 has a cylindrical shape and is used as a stator core in a rotating electric machine. Note that the laminated core 2 may also be a laminated core used as a rotor core in a rotating electric machine. Furthermore, the laminated core 2 may also be one of a plurality of divided cores that make up a stator core. Furthermore, the laminated core 2 may also be a core for a device other than a rotating electric machine.

[0019] Below, a brief description of the steel strip 1 will be given, followed by a detailed description of the laminated core 2 and the manufacturing apparatus 100. Figure 2 is an enlarged cross-sectional view showing the vicinity of the surface of the steel strip 1.

[0020] As shown in Figure 2, the steel strip 1 comprises a base steel sheet 11a and an adhesive layer 11b. In this embodiment, a non-oriented electrical steel sheet is used as the base steel sheet 11a, but a directional electrical steel sheet may also be used as the base steel sheet 11a. In this specification, the term "electrical steel sheet" refers to the base material portion (base steel sheet) excluding the insulating coating, etc. The adhesive layer 11b is formed on the surface of the base steel sheet 11a. In this embodiment, the adhesive layer 11b is formed on both sides of the base steel sheet 11a, but the adhesive layer 11b may also be formed on only one surface of the base steel sheet 11a.

[0021] The base steel plate 11a has a chemical composition containing basic elements, optional elements as needed, and the balance being Fe and impurities. In this embodiment, the base steel plate 11a has a chemical composition containing, for example, in mass %, as basic elements, Si: 1.0 to 4.5%, Al: 0.1 to 1.5%, and Mn: 0.2 to 4.0%.

[0022] The adhesive layer 11b is formed so as 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 properties in addition to adhesive properties. In this embodiment, the adhesive layer 11b is, for example, an insulating coating containing an epoxy resin and an epoxy resin curing agent.

[0023] The epoxy resin may be, for example, an epoxy resin having two or more epoxy groups per molecule. Examples of such epoxy resins include bisphenol A epoxy resins, bisphenol F epoxy resins, phenol novolac epoxy resins, cresol novolac epoxy resins, alicyclic epoxy resins, glycidyl ester epoxy resins, glycidyl amine epoxy resins, hydantoin epoxy resins, isocyanurate epoxy resins, acrylic acid-modified epoxy resins (epoxy acrylates), phosphorus-containing epoxy resins, and their halides (e.g., brominated epoxy resins) or hydrogenated versions. The epoxy resins may be used alone or in combination.

[0024] Examples of epoxy resin curing agents include aromatic polyamines, acid anhydrides, phenolic curing agents, dicyandiamide, boron trifluoride-amine complexes, and organic acid hydrazides. Examples of aromatic polyamines include metaphenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone. Examples of phenolic curing agents include phenol novolac resins, cresol novolac resins, bisphenol novolac resins, triazine-modified phenol novolac resins, and phenol resole resins. Phenol-based curing agents are preferred, and phenol resole resins are more preferred. One type of epoxy resin curing agent may be used alone, or two or more types may be used in combination.

[0025] Although detailed description is omitted, the adhesive layer 11b may be, for example, an insulating coating containing an acrylic resin and an acrylic resin curing agent.

[0026] Although detailed description is omitted, another insulating coating may be formed between the base steel sheet 11a and the adhesive layer 11b. Examples of materials that can be used to form the insulating coating include (1) inorganic compounds, (2) organic resins, and (3) mixtures of inorganic compounds and organic resins. Examples of inorganic compounds include (1) composites of dichromate and boric acid, (2) composites of phosphate and colloidal silica, (3) phosphates, (4) Zr compounds, and (5) Ti compounds. Examples of organic resins include epoxy resins, acrylic resins, acrylic-styrene resins, polyester resins, silicone resins, and fluororesins.

[0027] (Configuration of Laminated Core) As described above, the laminated core 2 has a configuration in which a plurality of core sheets 1a punched from the steel strip 1 are stacked. More specifically, the laminated core 2 has a configuration in which a plurality of base steel sheets (electromagnetic steel sheets) 11a punched into a predetermined shape are laminated and bonded to each other with adhesive layers 11b. The laminated core can be obtained, for example, by stacking a plurality of core sheets 1a each having an adhesive layer 11b formed on its surface, and applying pressure, heat, etc. to bond and fix the core sheets 1a to each other via the adhesive layers 11b.

[0028] (Method for Measuring Iron Loss Deterioration Rate) In this embodiment, the laminated core 2 is manufactured so that the iron loss deterioration rate of the laminated core 2 is 10% or less with respect to the two-layer (two sheets in this embodiment) base steel plates 11a (core sheets 1a) taken out from the laminated core 2. The iron losses of the laminated core 2 and the two-layer base steel plates 11a are measured as follows.

[0029] First, the iron loss of the laminated core 2 is measured. As described above, the laminated core 2 used for measurement may have a configuration in which a plurality of (two or more) base steel sheets (electromagnetic steel sheets) 11a punched into a predetermined shape are laminated and bonded to each other with adhesive layers 11b. The laminated core 2 may be obtained, for example, by the method described above, and may be subjected to a predetermined heat treatment (stress relief annealing, etc.). The dimensions of the laminated core used for measurement are not particularly limited. The number of laminations of the electromagnetic steel sheets constituting the laminated core is also not particularly limited, but a laminated core consisting of, for example, two electromagnetic steel sheets may be used. In this embodiment, the iron loss W of the laminated core 2 is measured using a magnetic property measuring device (BST-L) manufactured by BROCKHAUS. １５／５０ (W / kg) is measured.

[0030] Next, the 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 are two core sheets separated from the laminated core 2 and from which the adhesive layer has been removed by a method described below. 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 front side of the laminated core 2 are the two-layer core sheets 1a to be measured for iron loss. Note that the two-layer core sheets 1a (two in this embodiment) to be measured for iron loss are preferably the two-layer core sheets 1a on one side in the thickness direction of the laminated core 2 or the two-layer core sheets 1a on the other side in the thickness direction of the laminated core 2. However, as shown in FIG. 10 (described later), if a protrusion 3 is formed to separate multiple laminated cores 2, the two-layer core sheets 1a on the side where the protrusion 3 is not formed are used for iron loss measurement. The dimensions of the two-layer core sheet 1a to be measured for iron loss are not particularly limited, but the core sheet 1a removed from the laminated core 2 by the method described below may be used as is.

[0031] In this embodiment, the laminated core 2 is heated in a heating furnace at 400°C for 12 hours to carbonize the adhesive layer 11b, and the two core sheets 1a on the surface side of the laminated core 2 are separated. Then, the surfaces of the two core sheets 1a separated from the laminated core 2 are washed with acetone to completely remove the adhesive layer 11b from the surface of each core sheet 1a. Thereafter, the two core sheets 1a (base steel sheets 11a) from which the adhesive layer 11b has been removed are overlapped, and the iron loss W is measured using a magnetic property measuring device (BST-L) manufactured by BROCKHAUS. １５／５０The measured values ​​of the iron loss degradation rate (W / kg) are measured. When the two core sheets 1a are separated from the laminated core 2 and the adhesive layer 11b is removed as described above, the iron loss of the base steel sheet 11a (core sheet 1a) is prevented from increasing during the separation of the core sheets 1a and the removal of the adhesive layer 11b. This prevents the compressive residual stress imparted to the core sheet 1a by the pressure and heat treatment during laminated core manufacturing and by the adhesive layer 11b during bonding. Therefore, the iron loss of the two base steel sheets 11a separated from the laminated core 2 and having 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 plates 11a) before they are bonded together. By calculating the iron loss degradation rate of the laminated core 2 based on the two core sheets 1a (base steel plates 11a), the effects of the pressure and heat treatment during laminated core manufacturing and the adhesive layer 11b on iron loss degradation can be appropriately evaluated.

[0032] If the adhesive layer 11b cannot be removed using the heating conditions described above, the laminated core 2 can be immersed in a solvent to dissolve the adhesive layer 11b and separate the two core sheets 1a on the surface side of the laminated core 2. This method also prevents an increase in iron loss in the base steel sheet 11a while removing the compressive residual stress generated in the base steel sheet 11a during laminated core manufacturing (bonding). The solvent to be used can be determined based on the composition of the adhesive layer 11b. For example, if an epoxy resin is used for the adhesive layer 11b, a ketone-based solvent (anon, methyl ethyl ketone, etc.) can be used. The composition of the adhesive layer 11b can be inspected using a known method. Known solvents can also be used to dissolve the adhesive layer 11b.

[0033] In the laminated core 2 according to this embodiment, the iron loss degradation rate of the laminated core 2 relative to the iron loss of the two-layer (two in this embodiment) base steel plates 11a measured as described above is 10% or less. Specifically, the iron loss degradation rate calculated by the following formula (a) is 10% or less. Iron loss degradation rate (%) = ((iron loss of laminated core - iron loss of two-layer base steel plates) / iron loss of two-layer base steel plates) × 100 (a)

[0034] If the laminated core is one of multiple split cores that make up a stator, the iron loss of the laminated core is measured as follows. As shown in Figure 3(a), if a closed magnetic circuit can be formed by one split core 2a and the U-shaped measurement head 5 of the magnetic property measuring device, the iron loss measured for the split core 2a alone is taken as 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 taken as the iron loss of the two-layer base steel plate.

[0035] On the other hand, as shown in Figure 3(b), if a closed magnetic circuit cannot be formed using one split core 2b and the measuring head 5, multiple split cores 2b are connected so that a closed magnetic circuit can be formed. The iron loss measured with multiple split cores 2b connected is taken as the iron loss of the laminated core. In this case, the two core sheets on the surface side are separated from each split core 2b, and the separated multiple core sheets (six in this example) are connected in the same manner as in Figure 3(b), and the iron loss measured is taken as the iron loss of the two-layer base steel sheet.

[0036] If the split cores are already incorporated into the stator core of a rotating electrical machine, the stator core is first removed from the rotating electrical machine and disassembled into the split cores, after which the iron loss is measured using the method described above with reference to FIG.

[0037] (Configuration of the Manufacturing Apparatus) Next, the manufacturing apparatus 100 will be described in detail. As shown in FIG. 1 , the manufacturing apparatus 100 according to this embodiment includes a base unit 10, a punch 12, a punching die 14, a first holding unit 16, a second holding unit 18, and a heating unit 20. Although not shown, in the manufacturing apparatus 100, predetermined processing (such as the formation of slots) is performed on the steel strip 1 by other punches and dies, etc., also upstream of the punch 12 and the punching die 14 in the conveying direction of the steel strip 1. For example, as shown in FIG. 10 (described later), when multiple protrusions 3 are to be formed on the uppermost core sheet 1a (base steel plate 11a) of the laminated core 2, press working is performed to form the protrusions on the area of ​​the steel strip 1 that will be punched out as the core sheet 1a having the protrusions 3.

[0038] The punch 12 is arranged above the base portion 10 and is movable back and forth in the vertical direction. The punching die 14 is arranged below the punch 12. The punching die 14 has a cylindrical shape corresponding to the outer shape of the laminated core 2. In this embodiment, the opening edge 14a on the upper end side of the punching die 14 functions as a cutting blade. In this embodiment, the opening edge 14a has a circular shape. In this embodiment, the punch 12 and the punching die 14 repeatedly perform outer shape punching processing on the steel strip 1 being transported in a predetermined direction, and multiple core sheets 1a are punched out of the steel strip 1.

[0039] 1, an imaginary line A extending in the vertical direction through the center of the opening edge 14a of the punching die 14 is shown by a dashed line. In the following, the radial direction means a direction perpendicular to the imaginary line A. In addition, in the following, the circumferential direction means the circumferential direction of an imaginary circle centered at the center of the opening edge 14a when viewed from above.

[0040] The first holding portion 16 is disposed below the punching die 14. In this embodiment, the first holding portion 16 is fixed to the base portion 10 using an attachment member (not shown). In this embodiment, the first holding portion 16 includes a plurality of holding members 16a and a plurality of pressing devices 16b.

[0041] The plurality of holding members 16a are arranged in a line in the circumferential direction. Each holding member 16a is provided so as to be movable in the radial direction. A pressing device 16b is provided for each holding member 16a. The pressing device 16b is a device that moves the holding members 16a in the radial direction. In this embodiment, the pressing device 16b includes, for example, a hydraulic device, and moves the pressing device 16b in the radial direction by hydraulic pressure.

[0042] The first holding unit 16 may be configured to apply pressure from the side (radially outward) to the multiple core sheets 1a punched by the punch 12 and the punching die 14. Therefore, for example, one of the multiple holding members 16a may be fixed so as not to move in the radial direction. In this case, the pressing device 16b does not need to be connected to the fixed holding member 16a. The configuration of the first holding unit is not limited to the above example, and the first holding unit can be configured using various known squeeze ring configurations.

[0043] The second retaining portion 18 is disposed below the first retaining portion 16. In this embodiment, the second retaining portion 18 is formed as a separate member from the first retaining portion 16. In this embodiment, the second retaining portion 18 is disposed coaxially with the first retaining portion 16. In this embodiment, the second retaining portion 18 has multiple retaining members 18a that are disposed so as to be movable in the radial direction. Although not shown, a biasing device is provided for each retaining member 18a. In this embodiment, the biasing device includes, for example, an elastic member such as a spring, and biases the retaining members 18a radially inward (toward the imaginary line A). Note that the configuration of the second retaining portion is not limited to the above example, and the second retaining portion can be configured using various known squeeze ring configurations. For example, each retaining member 18a may be formed of multiple members stacked vertically and connected to each other.

[0044] The heating unit 20 is disposed around the second holding unit 18. In this embodiment, the heating unit 20 is disposed below the first holding unit 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 member 18a. The configuration of the heating unit 20 is not limited to the above example, and various heating devices capable of heating the second holding unit 18 (holding member 18a) or the core sheet 1a held by the second holding unit 18 can be used as the heating unit. For example, a high-frequency induction heating device disposed to surround the second holding unit 18 may be used as the heating unit.

[0045] (Manufacturing Method of Laminated Core) Next, a description will be given of a manufacturing method of the laminated core 2 using the above-described manufacturing apparatus 100. In this embodiment, a steel strip 1 is fed in a predetermined direction from a coil (hoop material) (not shown) by a feed mechanism (roller, etc.) (not shown), while a plurality of core sheets 1a are punched out of the steel strip 1 by a punch 12 and a punching die 14 (opening edge 14a).

[0046] As shown in Figure 4, the punched core sheets 1a are stacked in order inside the punching die 14. Note that although the outer periphery of the core sheet 1a punched from the steel strip 1 comes into contact with the inner peripheral surface of the punching die 14, in this embodiment, the punching die 14 does not apply a large amount of pressure to the core sheet 1a. Therefore, the core sheet 1a punched from the steel strip 1 by the punch 12 and the punching die 14 (opening edge 14a) moves downward inside the punching die 14 without being held by the inner peripheral surface of the punching die 14.

[0047] 5, as more core sheets 1a are punched out from the steel strip 1, a plurality of core sheets 1a are successively pushed into the first holding section 16. In this embodiment, each time a new core sheet 1a is punched out by the punch 12 and the punching die 14, one core sheet 1a is pushed from the punching die 14 into the first holding section 16.

[0048] As described above, the first holding portion 16 is configured to be able to apply pressure to the core sheets 1a from the sides (radially outward). In this embodiment, the multiple core sheets 1a are maintained in a state where they are pressed from the sides within the first holding portion 16. Therefore, the pressure generated between vertically adjacent core sheets 1a when the punch 12 presses the multiple core sheets 1a downward can be maintained within the first holding portion 16. As a result, the multiple core sheets 1a are pressed in the vertical direction, and vertically adjacent base steel plates 11a within the first holding portion 16 are pressure-bonded via the adhesive layer 11b. In this embodiment, a pressure greater than the pressure generated between vertically adjacent core sheets 1a due to the weight of the multiple core sheets 1a itself can be generated and maintained between vertically adjacent core sheets 1a within the first holding portion 16. Vertically adjacent core sheets 1a pressed in the first holding unit 16 are fixed together with a weaker adhesive force than the core sheets 1a after being heated and pressed in the second holding unit 18 (described later). In other words, vertically adjacent core sheets 1a are bonded (temporarily bonded) together in the first holding unit 16. The pressure applied by the punch 12 to the core sheets 1a is preferably set to 2.0 MPa or less, and more preferably close to the pressure required to punch the core sheets 1a (punching pressure: e.g., approximately 0.1 MPa). The pressure may be set to, for example, 1.8 MPa or less, or 1.0 MPa or less. It may also be set to 0.1 MPa or more. The pressure applied by the first holding unit 16 (in this embodiment, the holding member 16a) to the outer periphery of the core sheet 1a is set to, for example, a magnitude sufficient to prevent 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 portion 16 is greater than the weight of the core sheet 1a.

[0049] As described above, no large pressure is applied to the core sheets 1a from the inner peripheral surface of the punching die 14. Therefore, even if pressure is generated between adjacent core sheets 1a in the vertical direction within the punching die 14 as a result of the punch 12 pressing the multiple core sheets 1a downward, this state is not maintained. Therefore, the multiple core sheets 1a are not pressure-bonded to each other within the punching die 14.

[0050] In this embodiment, the first holding unit 16 holds the multiple core sheets 1a at a temperature below the softening temperature of the adhesive layer 11b. This prevents the adhesive layer 11b between a pair of vertically adjacent base steel sheets 11a from softening before the pair is pressure-bonded together within the first holding unit 16. Holding the multiple core sheets 1a in the first holding unit 16 at a temperature below the softening temperature of the adhesive layer 11b reduces compressive residual stress in the resulting laminated core and suppresses increases in iron loss, even when the multiple core sheets 1a are simultaneously pressurized and heated. The holding temperature of the multiple core sheets 1a in the first holding unit 16 is not limited as long as it is below the softening temperature of the adhesive layer 11b. For example, the holding temperature may be at least 10°C lower than the softening temperature of the adhesive layer 11b, or may be 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 unit 16 is not particularly limited, but may be, for example, 0°C or higher, or about room temperature (20°C) or higher, or 40°C or higher. The holding temperature (temperature of the adhesive layer 11b) of the multiple core sheets 1a in the first holding unit 16 can be measured by embedding a thermocouple thermometer or a radiation thermometer in the first holding unit 16. In this embodiment, the output of the heating unit 20 is controlled based on the holding temperature (temperature of the adhesive layer 11b) measured as described above so that the temperature of the core sheets 1a (adhesive layer 11b) in the first holding unit 16 is below the softening temperature. Alternatively, the vertical length of the first holding unit 16 may be adjusted, or a heat insulating section may be provided at the boundary between the first holding unit 16 and the second holding unit 18. Furthermore, a heating test of the heating unit 20 may be conducted in advance to simulate the temperature rise behavior of the adhesive layer 11b due to heating by the heating unit 20. The output of the heating unit 20 may then be controlled based on the temperature rise behavior of the adhesive layer 11b obtained by the simulation. The temperature inside the first holding portion 16 may rise due to the influence of the temperature inside the second holding portion that is provided continuously with the first holding portion 16, but by using the method described above, the temperature inside the first holding portion 16 can be controlled to be below the softening temperature of the adhesive layer 11b.In this embodiment, the holding temperature in the first holding unit 16 only needs to be below the softening temperature of the adhesive layer 11b, and the effects of this embodiment are not affected by the presence or absence of a heating unit in the first holding unit 16 or the intentional heating of the core sheet 1a. On the other hand, from the perspective of further reducing the compressive residual stress generated in the core sheet 1a, it is preferable that the first holding unit 16 suppresses the heating of multiple core sheets 1a. For example, in order to simplify the device and further reduce the compressive residual stress generated in the core sheet 1a, it is preferable not to provide a heating unit 20 in the first holding unit 16. For this reason, in this embodiment, the heating unit 20 is positioned below the lower end of the first holding unit 16.

[0051] In order to prevent the adhesive layer 11b between a pair of vertically adjacent core sheets 1a (base steel sheets 11a) from softening before the pair is pressed together, the vertical length of the portion of the first holding portion 16 that contacts the core sheet 1a (the length of the holding member 16a in this embodiment) is preferably 5 mm or more, and more preferably 10 mm or more. The upper limit of the vertical length of the portion of the first holding portion 16 that contacts the core sheet 1a is not particularly limited, but may be, for example, 160 mm or less, or may be 20 mm or less. In this case, sufficient time can be ensured for the first holding portion 16 to press the core sheets 1a together, so that the core sheets 1a can be more appropriately pressed together before the adhesive layer 11b softens.

[0052] The softening temperature of the adhesive layer 11b can be measured by TMA (thermomechanical analysis). Specifically, a cut plate measuring 7 mm x 7 mm or less is taken from the steel strip 1, and the softening temperature of the adhesive layer 11b is measured using the cut plate in a penetration mode. The needle load is set to 0.5 kgf to 2.0 kgf, and the heating rate is set to 15°C / min. The needle load is adjusted appropriately based on the needle penetration depth. Specifically, the measurement is first performed with a needle load of 0.5 kgf. If the needle penetration depth does not match the thickness of the adhesive layer 11b, the needle load is increased and the measurement is repeated until the needle penetration depth and the thickness of the adhesive layer 11b match. For example, the needle load is set to 1.5 kgf and the measurement is repeated. The needle load required to match the needle penetration depth to the thickness of the adhesive layer 11b also varies depending on the hardness of the adhesive layer 11b.

[0053] 6, as more core sheets 1a are punched out from the steel strip 1, the multiple core sheets 1a are sequentially pushed into the second holding section 18. In this embodiment, each time a new core sheet 1a is punched out by the punch 12 and the punching die 14, one core sheet 1a is pushed from the first holding section 16 into the second holding section 18.

[0054] The core sheet 1a pressed into the second holding section 18 is held from the side (radially outward) by the second holding section 18 (plurality of holding members 18a), heated by the heating section 20, and pressed by the punch 12. In this embodiment, the heating section 20 heats the plurality of core sheets 1a held in the second holding section 18 to a temperature equal to or higher than the softening temperature of the adhesive layer 11b. This softens and hardens the adhesive layer 11b of each core sheet 1a in the second holding section 18, and the plurality of core sheets 1a are fixed to one another. The plurality of core sheets 1a are pressed into the second holding section 18 one by one from the bottom, and are heated in order from the one pressed into the second holding section 18. Therefore, the stacked plurality of core sheets 1a are heated sequentially from the bottom to the top, gradually heating from the bottom. In this embodiment, the heating unit 20 heats the second holding unit 18 so that the temperature of the adhesive layer 11b in the second holding unit 18 rises to a temperature equal to or higher than the softening temperature. In this embodiment, the lateral pressure applied from the second holding unit 18 to the laminated core 2 is set to a magnitude sufficient to prevent the laminated core 2 from falling. In this embodiment, the pressure is set so that the static friction force generated between the laminated core 2 and the second holding unit 18 is greater than the weight of the laminated core 2. The heating temperature in the second holding unit 18 may be any temperature equal to or higher than the softening temperature of the adhesive layer 11b. For example, the heating temperature may be 10°C or higher than the softening temperature of the adhesive layer 11b, or 40°C or higher than the softening temperature of the adhesive layer 11b. The upper limit of the heating temperature in the second holding unit 18 is not particularly limited, but may be, for example, 200°C or lower. Furthermore, when the adhesive forming the adhesive layer 11b is a thermosetting resin, the heating unit 20 heats the multiple core sheets 1a held in the second holding unit 18 to a temperature equal to or higher than the curing temperature of the adhesive layer 11b.

[0055] When an infrared heating device is used as the heating unit 20, the temperature of each core sheet 1a can be gradually increased from the outer periphery toward the center. This allows the adhesive layer 11b of each core sheet 1a to be gradually hardened from the outer periphery toward the center. In this case, it is possible to prevent the adhesive from leaking out from between adjacent base steel plates 11a in the second holding unit 18. From this perspective, 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.

[0056] Finally, as shown in FIG. 1 , the multiple core sheets 1a fixed together within the second holding unit 18 are ejected from the second holding unit 18 as the laminated core 2. In this manner, the laminated core 2 is obtained. In this embodiment, the thickness of the core sheets 1a (steel strips 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 the laminated core 2 using only the force of the biasing device provided in the second holding unit 18. In such cases, it is preferable to support the laminated core 2 from below using a support device 26, as shown in FIG. 9 (described later).

[0057] Effect of the Present Embodiment In the manufacturing apparatus 100 according to the present embodiment, the first holding unit 16 holds the plurality of core sheets 1 a at a temperature below the softening temperature of the adhesive layer 11 b. This prevents the adhesive layer 11 b from softening before adjacent core sheets 1 a in the vertical direction are pressed together in the first holding unit 16, and reduces the compressive residual stress that occurs in the core sheets 1 a when the plurality of core sheets 1 a are pressed and heated.

[0058] Here, the inventors conducted detailed studies and found that when multiple core sheets 1a are simultaneously heated and pressurized at a temperature equal to or higher than the softening temperature of the adhesive layer 11b, compressive residual stress (radially inward residual stress) may occur in the core sheets 1a. Specifically, when multiple core sheets 1a are heated and pressurized at a temperature equal to or higher than the softening temperature of the adhesive layer 11b, softening of the adhesive layer 11b between a pair of vertically adjacent core sheets 1a progresses before the pair of core sheets 1a is pressed. In this case, compressive residual stress is likely to occur in the base steel plate 11a due to the difference in thermal expansion between the adhesive layer 11b and the base steel plate 11a above or below it, and the contraction of the adhesive layer 11b.

[0059] On the other hand, it has been found that compressive residual stress generated in the core sheets 1a due to pressure and heating can be reduced by first holding and pressurizing adjacent core sheets 1a at a temperature below the softening temperature of the adhesive layer 11b, and then heating and pressurizing adjacent core sheets 1a at a temperature equal to or higher than the softening temperature of the adhesive layer 11b. Furthermore, when multiple core sheets 1a pressed vertically are heated sequentially, starting from the bottom core sheet 1a, the adhesive layer 11b and the base steel plates 11a above and below it expand and contract in a mutually conforming manner. In this case, the generation of compressive residual stress in the base steel plates 11a is further suppressed. Therefore, in the manufacturing apparatus 100 according to this embodiment, as described above, the first holding unit 16 pressurizes the multiple core sheets 1a while holding them at a temperature below the softening temperature of the adhesive layer 11b. Then, in the second holding unit 18, the multiple core sheets 1a are heated and pressurized at a temperature equal to or higher than the softening temperature of the adhesive layer 11b, thereby adhering and fixing the multiple core sheets 1a to each other. This prevents the adhesive layer 11b from softening before adjacent core sheets 1a in the vertical direction are pressed together in the first holding section 16. As a result, compressive residual stress in each base steel sheet 11a in the first holding section 16 is suppressed, thereby reducing iron loss of the laminated core 2. In the manufacturing apparatus 100 according to this embodiment, the punching die 14, the first holding section 16, and the second holding section 18 are arranged successively in the vertical direction. In this configuration, the core sheets 1a pressed downward by the punch 12 are heated one by one from the bottom in the second holding section 18 to a temperature above the softening temperature of the adhesive layer 11b. By gradually heating the core sheets 1a from the bottom in the second holding section 18 to a temperature above the softening temperature of the adhesive layer 11b, compressive residual stress in each base steel sheet 11a can be reduced, thereby further reducing iron loss of the laminated core 2.

[0060] Typically, to obtain a laminated core with an appropriate shape, it is necessary to apply a large pressure exceeding 2.0 MPa from the punch to the multiple core sheets to cure the adhesive layer. However, in this case, the frictional force between the adhesive layer and the base steel sheet increases, generating compressive residual stress in the base steel sheet, thereby increasing iron loss. In contrast, in this embodiment, the multiple core sheets 1a are heated while the outer peripheries of the multiple core sheets 1a are laterally held (pressurized in this embodiment) by the second holding unit 18. This allows the adhesive layer 11b between the multiple core sheets 1a (base steel sheets 11a) to cure without applying large pressure to the multiple core sheets 1a in the stacking direction. This prevents the frictional force between the adhesive layer 11b and the base steel sheet 11a from increasing, and sufficiently suppresses the generation of compressive residual stress in the base steel sheet 11a. As a result, even when the pressure applied by 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 with an appropriate shape.

[0061] In the manufacturing apparatus 100 according to this embodiment, the first holding portion 16 and the second holding portion 18 are configured as separate members. More specifically, the portion of the first holding portion 16 that contacts the core sheet 1a (in this embodiment, holding member 16a) and the portion of the second holding portion 18 that contacts the core sheet 1a (in this embodiment, holding member 18a) are configured as separate members. This suppresses heat transfer from the second holding portion 18 to the first holding portion 16, thereby suppressing a temperature rise in the first holding portion 16. As a result, a temperature rise in the multiple core sheets 1a within the holding member 16a can be easily suppressed.

[0062] (Modification) In the above embodiment, a case where one adhesive layer 11b is provided on the surface of the base steel plate 11a has been described, but multiple layers (multiple types) of adhesive layers may be provided on the surface of the base steel plate. In this case, the first holding unit holds multiple core sheets so that all of the adhesive layers have a temperature below the softening temperature. The heating unit heats the multiple core sheets held in the second holding unit so that all of the adhesive layers have a temperature equal to or higher than the softening temperature. This also applies to the embodiments described below.

[0063] In the above-described embodiment, the first retaining portion 16 and the second retaining portion 18 are provided independently of each other. However, as shown in FIG. 7 , the first retaining portion 16 and the second retaining portion 18 may be connected to each other by a plurality of connecting portions 22. In this case, the first retaining portion 16 and the second retaining portion 18 can be interlocked, thereby simplifying the configuration of the first retaining portion 16 and the second retaining portion 18 (the configuration for pressing the retaining members 16 a and 18 a). The connecting portions 22 may be recessed and protruding portions formed on the retaining members 16 a and 18 a. In this case, the retaining members 16 a and 18 a can be fixed together by, for example, crimping the recessed and protruding portions. The connecting portions 22 may also be fastening members such as bolts and nuts.

[0064] In the above-described embodiment, the second holding portion 18 is disposed directly below the first holding portion 16. However, as shown in FIG. 8 , the first holding portion 16 and the second holding portion 18 may be connected via a heat insulating member 24 having a lower thermal conductivity than the holding member 18a (the portion of the second holding portion 18 that contacts the core sheet 1a). In this case, heat transfer from the second holding portion 18 to the first holding portion 16 can be sufficiently suppressed, and a temperature rise in the first holding portion 16 can be sufficiently prevented. In this embodiment, the heat insulating member 24 forms a connecting portion that connects the first holding portion 16 and the second holding portion 18.

[0065] In the above-described embodiment, the plurality of core sheets 1a are supported by applying pressure to the plurality of core sheets 1a from the sides in the first holding section 16 and the second holding section 18. However, as shown in Fig. 9, the plurality of core sheets 1a may be further supported from below by a support device 26. This allows the plurality of core sheets 1a to be supported more stably. The support device 26 is a device that supports the plurality of core sheets 1a from below by, for example, hydraulic pressure or the elastic force of an elastic member such as a spring.

[0066] In the above-described embodiment, all of the core sheets 1a (base steel plates 11a) constituting the laminated core 2 have the same shape. However, the shape of the laminated core 2 is not limited to the above example, and some of the core sheets 1a of the laminated core 2 may have a different shape from the other core sheets 1a. For example, as shown in FIG. 10 , a plurality of protrusions 3 protruding outward in the lamination direction may be formed on the core sheet 1a (base steel plate 11a) at one end in the lamination direction (the upper end in this embodiment). When a plurality of laminated cores 2 are continuously manufactured, forming the plurality of protrusions 3 on the core sheet 1a at the upper end of each laminated core 2 as described above allows the plurality of laminated cores 2 to be easily separated. As a result, a plurality of laminated cores 2 can be manufactured efficiently.

[0067] 11 is a schematic cross-sectional view showing a laminated core manufacturing apparatus according to a second embodiment of the present invention. The manufacturing apparatus 100a according to this embodiment differs from the manufacturing apparatus 100 shown in FIG. 1 in that a first holding portion 60 is provided instead of the first holding portion 16, and a second holding portion 80 is provided instead of the second holding portion 18.

[0068] In this embodiment, the first holding unit 60 has multiple holding members 16a and multiple pressing devices 16b, similar to the first holding unit 16 described above, and the second holding unit 80 has multiple holding members 18a, similar to the second holding unit 18 described above. However, in this embodiment, the portion of the first holding unit 60 that contacts the core sheet 1a and the portion of the second holding unit 80 that contacts the core sheet 1a are made of the same material. Specifically, each holding member 16a and the holding member 18a located below it are made of the same material. Note that in this embodiment, the holding members 16a are portions that hold the multiple core sheets 1a at a temperature below the softening temperature of the adhesive layer 11b. Furthermore, in this embodiment, the upper end of the holding 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.

[0069] In this embodiment, too, the vertical length of the portion of the first holding section 60 that contacts the core sheet 1a (in this embodiment, the length of the holding member 16a) is preferably 5 mm or more, and preferably 10 mm or more. Furthermore, the vertical distance between the upper end of the portion of the first holding section 60 that contacts the core sheet 1a (in this embodiment, the upper end of the holding member 16a) and the upper end of the heating section 20 is preferably 5 mm or more, and preferably 10 mm or more. Also in this embodiment, too, the pressure applied by the punch 12 to the multiple core sheets 1a is preferably set to 2.0 MPa or less, and may be set to 1.8 MPa or less, and more preferably close to the pressure required to punch the core sheets 1a (punching pressure: for example, approximately 0.1 MPa). Therefore, the pressure applied by the punch 12 to the multiple core sheets 1a may be, for example, 0.1 MPa or more. The pressure applied from the first holding part 60 (holding member 16a in this embodiment) to the outer periphery of the core sheet 1a is set to a magnitude that 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 part 60 is greater than the weight of the core sheet 1a.

[0070] In the manufacturing apparatus 100a according to this embodiment, similarly to the manufacturing apparatus 100 according to the first embodiment, a plurality of core sheets 1a are punched out of a steel strip 1 using a punch 12 and a punching die 14. The punched core sheets 1a are pressed downward by the punch 12 while the outer peripheries of the punched core sheets 1a are pressed from the side in the first holding unit 60, thereby crimping the plurality of core sheets 1a together. The plurality of core sheets 1a crimped together in the first holding unit 60 are then heated by the heating unit 20 in the second holding unit 80 to a temperature equal to or higher than the softening temperature of the adhesive layer 11b. This softens and hardens the adhesive layer 11b of each core sheet 1a in the second holding unit 80, thereby securing the plurality of core sheets 1a together. The secured core sheets 1a are then ejected from the second holding unit 80 as a laminated core 2.

[0071] In the manufacturing apparatus 100a according to this embodiment, the multiple core sheets 1a are also held at a temperature below the softening temperature of the adhesive layers 11b in the first holding unit 60. This prevents the adhesive layers 11b from softening before vertically adjacent core sheets 1a are pressed together in the first holding unit 60. As a result, the generation of compressive residual stress in each base steel plate 11a can be suppressed, and the iron loss of the laminated core 2 can be reduced.

[0072] Furthermore, in the manufacturing apparatus 100a according to this embodiment, the first holding unit 60 and the second holding unit 80 can be interlocked, so that the configuration of the first holding unit 60 and the second holding unit 80 (the configuration for pressing the holding members 16a and 18a) can be simplified. In the manufacturing apparatus 100a shown in FIG. 11, the pressing device 16b is attached to the holding member 16a, but the pressing device 16b may also be attached to the holding member 18a. In this case, the pressing device 16b can move the holding member 16a in the radial direction via the holding member 18a.

[0073] In this embodiment, the core sheets 1a are heated while the outer peripheries of the core sheets 1a are laterally held (pressurized in this embodiment) by the second holding unit 80. This allows the adhesive layer 11b between the core sheets 1a (base steel plates 11a) to harden without applying large pressure to the core sheets 1a in the stacking direction. In this case, the frictional force between the adhesive layer 11b and the base steel plates 11a can be prevented from increasing, and the generation of compressive residual stress in the base steel plates 11a can be sufficiently suppressed. This allows the core sheets 1a to be properly bonded together and a laminated core 2 with an appropriate shape to be obtained, even when the pressure applied by the punch 12 to the core sheets 1a is low, at 2.0 MPa or less.

[0074] Although detailed description will be omitted, another holding portion (for example, a known squeeze ring) may be provided below the second holding portion 80.

[0075] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0076] The laminated cores of Examples 1 to 7 and Comparative Examples 1 to 4 were manufactured using a manufacturing apparatus similar to the manufacturing apparatus 100 shown in FIG. 1 . The position of the heating unit 20 was adjusted as appropriate. The laminated cores of Comparative Examples 5 and 6 were manufactured using a manufacturing apparatus similar to the manufacturing apparatus 100 shown in FIG. 1 , except that it did not include the first holding unit 16. In both the Examples and Comparative Examples, the laminated cores were constructed using two annular core sheets. The holding temperature of the first holding unit 16 was elevated due to the influence of the heating temperature of the adjacent second holding unit 18. A non-oriented electrical steel sheet was used as the base steel sheet. The adhesive layers of the laminated cores of Examples 1 to 3 and 6 and Comparative Examples 1, 2, and 5 were formed using an epoxy-based resin and an amine-based curing agent, while the adhesive layers of the laminated cores of Examples 4, 5, and 7 and Comparative Examples 3, 4, and 6 were formed using an acrylic-based resin and an amine-based curing agent.

[0077] The iron loss deterioration rate was measured by the above-mentioned method for the laminated cores manufactured in Examples 1 to 7 and Comparative Examples 1 to 6. Specifically, first, the iron loss W １５／５０ The iron loss (W / kg) was measured using a magnetic property measuring device (BST-L) manufactured by BROCKHAUS. Next, the laminated core was heated in a heating furnace at 400°C for 12 hours to carbonize the adhesive layer, and the two core sheets of the laminated core were separated. The surfaces of the separated two core sheets were then washed with acetone to completely remove the adhesive layer from the surface of each core sheet, and the two core sheets (base steel sheets) were then overlapped, and the iron loss W was measured using a magnetic property measuring device (BST-L) manufactured by BROCKHAUS. １５／５０The iron loss degradation rate (W / kg) of each laminated core was measured. The iron loss degradation rate of each laminated core in the examples and comparative examples was calculated using the above formula (a). When comparing the iron loss of a three-layer or more laminated core with that of a two-layer laminated core manufactured under the same conditions, the iron loss of the two-layer laminated core is usually greater. 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 a two-layer laminated core calculated using the above formula (a) is 10% or less, it is likely that the iron loss degradation rate of a three-layer or more laminated core manufactured under the same conditions as that laminated core will also be 10% or less. The magnetic flux density during iron loss measurement was set to 1.5 T, and the frequency was set to 50 Hz. 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 calculated iron loss degradation rate are shown in Table 1 below.

[0078]

[0079] The softening temperatures of the adhesive layers in Table 1 were measured by thermomechanical analysis (TMA) using cut sheets taken from the steel strips used to make the core sheets. The holding temperature of the first holding section in Table 1 refers to the maximum temperature of the core sheet within the first holding section 16. The heating temperature of the second holding section in Table 1 refers to the maximum temperature of the core sheet within the second holding section 18. However, for Comparative Examples 5 and 6, the heating temperature of the second holding section refers to the temperature of the core sheet at the upper end of the second holding section 18. In Comparative Examples 1 to 4, the minimum temperatures of the core sheet within the first holding section 16 were all above the softening temperature. The temperature of the core sheet within the first holding section 16 was measured using multiple thermocouples arranged vertically within the first holding section 16. Similarly, the temperature of the core sheet within the second holding section 18 was measured using multiple thermocouples arranged vertically within the second holding section 18.

[0080] As shown in Table 1, in Examples 1 to 7, in which the core sheet was held in the first holding portion 16 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 was suppressed. In particular, in Examples 1 to 5, in which the pressure applied by 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 was sufficiently suppressed.

[0081] On the other hand, in Comparative Examples 1 to 4, in which the core sheet was held at a temperature equal to or higher than the softening temperature of the adhesive layer within the first holding portion 16, the iron loss degradation rate of the laminated core was 14% or higher. Also, in Comparative Examples 5 and 6, in which the first holding portion 16 was not provided and the core sheet was held at a temperature equal to or higher than the softening temperature of the adhesive layer at the upper end within the second holding portion 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 was greater than in Examples 1 to 7.

[0082] According to the present invention, a laminated core with low iron loss can be manufactured.

[0083] REFERENCE SIGNS LIST 1 steel strip 2 laminated core 3 convex portion 10 base portion 12 punch 14 punching die 16, 60 first holding portion 18, 80 second holding portion 20 heating portion 22 connecting portion 24 heat insulating member 26 supporting device 100, 100a manufacturing device

Claims

1. A laminated core in which a plurality of electromagnetic steel sheets are laminated with adhesive layers interposed therebetween, A laminated core, wherein the iron loss degradation rate of the laminated core with respect to two layers of electromagnetic steel sheets separated from the laminated core is 10% or less.

2. The laminated core according to claim 1 , wherein the electromagnetic steel sheets at one end in the lamination direction have a plurality of protrusions formed thereon that protrude outward in the lamination direction.

3. A manufacturing apparatus including a punch, a punching die disposed below the punch, a first holding section disposed below the punching die, a second holding section disposed below the first holding section, and a heating section disposed around the second holding section, punching a plurality of core sheets from a steel strip having a thermosetting adhesive layer on a surface thereof by the punch and the punching die; The punch presses the outer periphery of the punched core sheets from the side by the first holding part, while pressing the core sheets downward by the punch; The plurality of core sheets pressed downward by the punch are heated by the heating section while being held in the second holding section; In the first holding section, the plurality of core sheets are held at a temperature lower than the softening temperature of the adhesive layer, A method for manufacturing a laminated core, wherein the heating section heats the multiple core sheets held in the second holding section to a temperature equal to or higher than the softening temperature of the adhesive layer.

4. The method for manufacturing a laminated core according to claim 3 , wherein a length in a vertical direction of the portion of the first holding portion that contacts the core sheet is 5 mm or more.

5. The method for manufacturing a laminated core according to claim 3 or 4, wherein the punch presses the plurality of core sheets with a pressure of 2.0 MPa or less.

6. The method for manufacturing a laminated core according to claim 3 or 4, wherein the heating unit includes an infrared heating device.

7. An apparatus for manufacturing a laminated core by punching out a plurality of core sheets from a steel strip having an adhesive layer on its surface and bonding the obtained plurality of core sheets to each other, comprising: punch, A punching die disposed below the punch; A first holding portion disposed below the punching die; A second holding portion disposed below the first holding portion; and A heating unit disposed around the second holding unit; Equipped with punching a plurality of core sheets from the steel strip with the punch and the punching die; The punch presses the outer periphery of the punched core sheets from the side by the first holding part, while pressing the core sheets downward by the punch; The plurality of core sheets pressed downward by the punch are heated by the heating section while being held in the second holding section; In the first holding section, the plurality of core sheets are held at a temperature lower than the softening temperature of the adhesive layer, The heating section heats the plurality of core sheets held in the second holding section to a temperature equal to or higher than the softening temperature of the adhesive layer.

8. 8. The laminated core manufacturing device according to claim 7, wherein a length in a vertical direction of the portion of the first holding portion that contacts the core sheet is 5 mm or more.

9. 9. The laminated core manufacturing apparatus according to claim 7, wherein the punch presses the core sheets with a pressure of 2.0 MPa or less.

10. The laminated core manufacturing apparatus according to claim 7 or 8, wherein the heating section includes an infrared heating device.