Manufacturing apparatus and method for laminated core

Abstract

A manufacturing apparatus 100 comprises: a punch 12; a punching die 14 disposed under the punch 12; a first holding part 16 disposed under the punching die 14; a second holding part 18 disposed under the first holding part 16 and composed of a member different from the first holding part 16; and a heating part 20 disposed around the second holding part 18 under the first holding part 16. 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 core sheets 1a are pressed downward by the punch 12 while the outer peripheral parts of the plurality of punched 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 inside the second holding part 18.

Description

[Technical field]

[0001] The present invention relates to an apparatus and method for manufacturing a laminated core. [Background technology]

[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. As one method for manufacturing laminated cores, a method is known in which a core sheet of a predetermined shape is punched out of a steel strip to which an adhesive is applied, and the obtained plurality of core sheets are bonded to each other to manufacture the laminated core.

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

[0004] [Patent Document 1] JP 2009-297758 A Summary of the Invention [Problem to be solved by the invention]

[0005] The method disclosed in Patent Document 1 allows the punching of the thin core plates by the punching die and the application of pressure and heat to the multiple thin core plates in the squeeze ring to be carried out continuously, which makes it possible to efficiently manufacture laminated cores.

[0006] However, as a result of research by the present inventors, it has been found that when multiple iron core thin plates are pressurized and heated simultaneously as described above, compressive residual stress is generated in the obtained laminated iron core, which may increase iron loss.

[0007] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to provide an apparatus and method for manufacturing a laminated core that can suppress the occurrence of iron loss. [Means for solving the problem]

[0008] A manufacturing apparatus according to an embodiment of the present invention comprises: 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 configured as a separate member from the first holding portion; and a heating section disposed around the second holding section below the first holding section; 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 method is characterized in that the multiple core sheets pressed downward by the punch are heated by the heating section while being held in the second holding section.

[0009] In addition, a manufacturing method according to one embodiment of the present invention includes the steps of: 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 made of a separate member from the first holding section, and a heating section disposed below the first holding section and around the second holding section, punching a plurality of core sheets from a steel strip having an 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 method is characterized in that the multiple core sheets pressed downward by the punch are heated by the heating section while being held in the second holding section.

[0010] The adhesive layer may be a thermosetting adhesive layer.

[0011] The first holding portion and the second holding portion may be connected via a connecting portion.

[0012] The first holding portion may have a vertical length of 5 mm or more.

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

[0014] The heating section may include an infrared heating device. Effect of the Invention

[0015] According to the present invention, it is possible to suppress the occurrence of iron loss in a laminated core. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a laminated core manufacturing apparatus according to one embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged cross-sectional view showing the vicinity of the surface of the steel strip. [Diagram 3] FIG. 3 is a diagram for explaining a method for manufacturing a laminated core according to an embodiment of the present invention. [Figure 4] FIG. 4 is a diagram for explaining a method for manufacturing a laminated core according to an embodiment of the present invention. [Diagram 5] FIG. 5 is a diagram for explaining a method for manufacturing a laminated core according to an embodiment of the present invention. [Figure 6] FIG. 6 is a diagram showing a modified example of the manufacturing apparatus. [Figure 7] FIG. 7 is a diagram showing another modified example of the manufacturing apparatus. [Figure 8] FIG. 8 is a diagram showing another modified example of the manufacturing apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a laminated core manufacturing apparatus and method according to an embodiment of the present invention will be described with reference to the drawings.

[0018] FIG. 1 is a schematic cross-sectional view showing a manufacturing apparatus for a laminated core according to an embodiment of the present invention. The manufacturing apparatus 100 is an apparatus for punching out a plurality of core sheets 1a from a steel strip 1 conveyed in a predetermined direction, and manufacturing a laminated core 2 by bonding the obtained plurality of core sheets 1a to each other. In this embodiment, the laminated core 2 has, for example, a cylindrical shape and is used as a stator core in a rotating electric machine. The laminated core 2 may be a laminated core used as a rotor core in a rotating electric machine. The laminated core 2 may also be a split core. The laminated core 2 may also be a core of a device other than a rotating electric machine.

[0019] Below, a brief description will be given of the steel strip 1, followed by a detailed description of 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 FIG. 2, the steel strip 1 includes a base steel sheet 11a and an adhesive layer 11b. In this embodiment, a non-oriented electromagnetic steel sheet is used as the base steel sheet 11a, but an oriented electromagnetic steel sheet may also be used as the base steel sheet 11a. In this specification, the electromagnetic steel sheet means the base material portion (base steel sheet) excluding the insulating coating and the like. 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 be formed on only one surface of the base steel sheet 11a.

[0021] The chemical composition of the base steel sheet 11a contains basic elements, optional elements as necessary, and the balance being Fe and impurities. In this embodiment, the chemical composition of the base steel sheet 11a contains, 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 an insulating performance in addition to an adhesive function. In this embodiment, the adhesive layer 11b is, for example, an insulating coating containing an epoxy resin and an epoxy resin curing agent.

[0023] As the epoxy resin, for example, an epoxy resin having two or more epoxy groups in one molecule can be used. As such epoxy resin, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, alicyclic epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, hydantoin type epoxy resin, isocyanurate type epoxy resin, acrylic acid modified epoxy resin (epoxy acrylate), phosphorus-containing epoxy resin, and their halides (brominated epoxy resin, etc.) or hydrogenated products can be mentioned. As the epoxy resin, one type may be used alone, or two or more types may be used 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 resol resins. Examples of epoxy resin curing agents include phenolic curing agents, and more preferably phenol resol resins. Examples of epoxy resin curing agents include one type alone, and two or more types may be used in combination.

[0025] Although detailed description is omitted, another insulating coating may be formed between the base steel sheet 11a and the adhesive layer 11b. Examples of the material constituting the insulating coating include (1) inorganic compounds, (2) organic resins, and (3) mixtures of inorganic compounds and organic resins. Examples of the 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 the organic resins include epoxy resins, acrylic resins, acrylic styrene resins, polyester resins, silicone resins, and fluororesins.

[0026] (Configuration of manufacturing equipment) 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 section 10, a punch 12, a punching die 14, a first holding section 16, a second holding section 18, and a heating section 20. Although not shown, in the manufacturing apparatus 100, a predetermined punching process (such as the formation of slots) is performed on the steel strip 1 by another punch and die, even upstream of the punch 12 and the punching die 14 in the conveying direction of the steel strip 1.

[0027] The punch 12 is disposed above the base portion 10 so as to be movable up and down. The punching die 14 is disposed 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, an 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 transported in a predetermined direction, and multiple core sheets 1a are punched out from the steel strip 1.

[0028] 1, an imaginary line A that passes through the center of the opening edge 14a of the punching die 14 and extends in the vertical direction 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 a circumferential direction of an imaginary circle centered on the center of the opening edge 14a when viewed from above.

[0029] 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.

[0030] The multiple 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 member 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.

[0031] The first holding section 16 may be configured so as to pressurize the core sheets 1a punched by the punch 12 and the punching die 14 from the side (outside in the radial direction). Therefore, for example, any 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 section is not limited to the above example, and the first holding section can be configured using the configuration of various known squeeze rings.

[0032] The second holding portion 18 is disposed below the first holding portion 16. The second holding portion 18 is configured by a separate member from the first holding portion 16. In this embodiment, the second holding portion 18 is provided coaxially with the first holding portion 16. In this embodiment, the second holding portion 18 has a plurality of holding members 18a that are provided so as to be movable in the radial direction. Although not shown, a biasing device is provided for each holding member 18a. In this embodiment, the biasing device includes, for example, an elastic member such as a spring, and biases the holding member 18a toward the radial inside (the imaginary line A side). Note that the configuration of the second holding portion is not limited to the above example, and the second holding portion can be configured by utilizing the configuration of various known squeeze rings.

[0033] The heating section 20 is disposed around the second holding section 18 below the first holding section 16. In this embodiment, the heating section 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 section 20 is not limited to the above example, and various heating devices capable of heating the second holding section 18 (holding member 18a) or the core sheet 1a held by the second holding section 18 can be used as the heating section. For example, a high-frequency induction heating device provided to surround the second holding section 18 may be used as the heating section.

[0034] (Laminated core manufacturing method) Next, a description will be given of a manufacturing method of the laminated core 2 using the above-mentioned 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 (rollers, 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).

[0035] As shown in Fig. 3, the punched core sheets 1a are stacked in sequence in the punching die 14. Note that 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, but in this embodiment, the punching die 14 does not apply a large 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 within the punching die 14 without being held by the inner peripheral surface of the punching die 14.

[0036] 4, by punching out more core sheets 1a from the steel strip 1, a plurality of core sheets 1a are successively pressed into the first holding portion 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 pressed into the first holding portion 16 from the punching die 14.

[0037] As described above, the first holding section 16 is configured to be able to pressurize the core sheet 1a from the side (radial outside). In this embodiment, the state in which the multiple core sheets 1a are pressed from the side is maintained in the first holding section 16. Therefore, the pressure generated between the vertically adjacent core sheets 1a by the punch 12 pressing the multiple core sheets 1a downward can be maintained in the first holding section 16. As a result, the multiple core sheets 1a are pressed in the vertical direction, and the vertically adjacent base steel plates 11a are pressure-bonded via the adhesive layer 11b in the first holding section 16. In this embodiment, a pressure greater than the pressure generated between the vertically adjacent core sheets 1a by the weight of the multiple core sheets 1a can be generated and maintained between the vertically adjacent core sheets 1a in the first holding section 16. In addition, the core sheets 1a adjacent to each other in the vertical direction pressurized in the first holding section 16 are fixed with a force (adhesive force) weaker than that of the core sheets 1a after being heated and pressurized in the second holding section 18 described later. That is, in the first holding section 16, the core sheets 1a adjacent to each other in the vertical direction are bonded (temporarily bonded). In addition, the pressure applied from the punch 12 to the multiple 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: for example, about 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. In addition, the pressure applied from the first holding section 16 (in this embodiment, the holding member 16a) to the outer periphery of the core sheet 1a is set to, for example, a magnitude that can 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.

[0038] As described above, no large pressure is applied to the core sheet 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 in the punching die 14 as a result of the punch 12 applying downward pressure to the multiple core sheets 1a, this state is not maintained. Therefore, the multiple core sheets 1a are not pressure-bonded to each other in the punching die 14.

[0039] As described above, the core sheet 1a is provided with a thermosetting adhesive layer 11b. In this embodiment, at least at the upper end in the first holding section 16, the temperature of the first holding section 16 is adjusted so that the adhesive layer 11b does not soften. For example, the temperature of the first holding section 16 is adjusted so that the adhesive layer 11b between a pair of base steel plates 11a adjacent to each other in the vertical direction is prevented from softening before the pair of base steel plates 11a are pressure-bonded to each other in the first holding section 16. More specifically, the first holding section 16 may hold the multiple core sheets 1a at a temperature lower than the softening temperature of the adhesive layer 11b. When the multiple core sheets 1a are held in the first holding section 16 at a temperature lower than the softening temperature of the adhesive layer 11b, even when the multiple core sheets 1a are pressurized and heated simultaneously, the compressive residual stress generated in the obtained laminated core can be reduced and an increase in iron loss can be suppressed. The holding temperature of the core sheets 1a in the first holding section 16 may be, for example, 10°C or more lower than the softening temperature of the adhesive layer 11b, and may be 30°C or more lower than the softening temperature of the adhesive layer 11b. The lower limit of the holding temperature in the first holding section 16 is not particularly limited, but may be, for example, 0°C or more, or about room temperature (20°C) or more, or 40°C or more. The holding temperature of the core sheets 1a in the first holding section 16 (temperature of the adhesive layer 11b) can be measured by embedding a thermocouple thermometer or a radiation thermometer in the first holding section 16. In this embodiment, based on the holding temperature (temperature of the adhesive layer 11b) measured as described above, the output of the heating section 20 is controlled so that the temperature of the core sheets 1a (adhesive layer 11b) in the first holding section 16 is lower than the softening temperature. In addition, the length of the first holding section 16 in the vertical direction may be adjusted, or a heat insulating section may be provided at the boundary between the first holding section 16 and the second holding section 18. Also, a heating test of the heating unit 20 may be performed in advance to simulate the temperature rise behavior of the adhesive layer 11b due to heating by the heating unit 20. Then, the output of the heating unit 20 may be controlled based on the temperature rise behavior of the adhesive layer 11b obtained by the simulation.The temperature in the first holding section 16 may rise due to the influence of the temperature in the second holding section provided continuously with the first holding section 16, but the above-mentioned method can control the temperature in the first holding section 16 to be lower than the softening temperature of the adhesive layer 11b. In this embodiment, the holding temperature in the first holding section 16 is only required to be lower than 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 section in the first holding section 16 and the presence or absence of intentional heating of the core sheet 1a. On the other hand, from the viewpoint of further reducing the compressive residual stress generated in the core sheet 1a, it is preferable that the first holding section 16 suppresses the heating of the 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 that the first holding section 16 does not include a heating section 20. For this reason, in this embodiment, the heating section 20 is positioned lower than the lower end of the first holding section 16.

[0040] From the viewpoint of preventing the temperature of the upper end of the first holding portion 16 from increasing due to heating by the heating section 20, the vertical length of the first holding portion 16 (more specifically, the length of the portion in contact with the core sheet 1a; in this embodiment, the length of the holding member 16a) is preferably 5 mm or more, and more preferably 10 mm or more. In this case, the core sheets 1a can be more appropriately pressed together in the first holding portion 16 before the adhesive layer 11b softens. There is no particular limit to the upper limit of the vertical length of the first holding portion 16, but it may be, for example, 160 mm or less, and may be 20 mm or less.

[0041] 5, as more core sheets 1a are punched out from the steel strip 1, the multiple core sheets 1a are successively 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.

[0042] The core sheet 1a pressed into the second holding section 18 is held from the side (radial outside) by the second holding section 18 (multiple holding members 18a), heated by the heating section 20, and pressed by the punch 12. In this embodiment, the multiple core sheets 1a are heated by the heating section 20, and the adhesive layer 11b of each core sheet 1a is softened and hardened in the second holding section 18. As a result, the multiple core sheets 1a are fixed to each other in the second holding section 18. In addition, the multiple core sheets 1a are pressed into the second holding section 18 one by one from the lower side, and are heated in order from the one pressed into the second holding section 18. Therefore, the multiple stacked core sheets 1a are heated in order from the one located on the lower side to the one located on the upper side, and are gradually heated from the lower side. In this embodiment, the heating section 20 heats the second holding section 18 so that the temperature of the adhesive layer 11b in the second holding section 18 rises to a temperature equal to or higher than the softening temperature. In this embodiment, the pressure applied from the second holding part 18 to the laminated core 2 from the side is set to a magnitude that can 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 part 18 is greater than the weight of the laminated core 2. The heating temperature in the second holding part 18 may be a temperature equal to or higher than the softening temperature of the adhesive layer 11b, but may be, for example, a temperature 10°C or higher than the softening temperature of the adhesive layer 11b, or may be, for example, 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 part 18 is not particularly limited, but may be, for example, 200°C or lower. In addition, when the adhesive forming the adhesive layer 11b is a thermosetting resin, the heating part 20 heats the multiple core sheets 1a held by the second holding part 18 to a temperature equal to or higher than the hardening temperature of the adhesive layer 11b.

[0043] When an infrared heating device is used as the heating section 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 cured from the outer periphery toward the center. In this case, it is possible to prevent the adhesive from leaking out from between the base steel plates 11a adjacent to each other vertically in the second holding section 18. From this viewpoint, it is preferable to use an infrared heating device as the heating section 20. In this embodiment, for example, an infrared heating device that radiates near-infrared rays having a wavelength of 750 to 1000 nm is used.

[0044] Finally, as shown in FIG. 1, the multiple core sheets 1a fixed to each other in the second holding section 18 are discharged from the second holding section 18 as the laminated core 2. In this manner, the laminated core 2 is manufactured. 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 having a mass exceeding 6.0 kg, it may be difficult to hold the laminated core 2 only with the force of the biasing device provided in the second holding section 18. In such a case, it is preferable to support the laminated core 2 from below by a supporting device 26, as shown in FIG. 8 described later.

[0045] (Effects of this embodiment) In the manufacturing apparatus 100 according to this embodiment, when the heating unit 20 heats the multiple core sheets 1a held in the second holding unit 18, the second holding unit 18 is also heated. The first holding unit 16 is provided above the second holding unit 18, and the temperature of the first holding unit 16 also rises as heat is transferred from the second holding unit 18 to the first holding unit 16.

[0046] However, in the manufacturing apparatus 100 according to this embodiment, the first holding section 16 and the second holding section 18 are configured by different members, and heat transfer from the second holding section 18 to the first holding section 16 can be suppressed. This sufficiently suppresses the first holding section 16 (holding member 16a) from reaching the softening temperature of the adhesive layer 11b or higher. In other words, it is possible to prevent the adhesive layer 11b from softening before the core sheets 1a adjacent to each other in the vertical direction in the first holding section 16 are pressed together. As a result, it is possible to reduce the compressive residual stress generated in the core sheets 1a by pressing and heating the multiple core sheets 1a.

[0047] Here, the inventors conducted detailed studies and found that when heating and pressurizing a plurality of core sheets 1a at a temperature equal to or higher than the softening temperature of the adhesive layer 11b are started simultaneously, compressive residual stress (radial inward residual stress) occurs in the core sheets 1a. Specifically, when heating and pressurizing the core sheets 1a are started simultaneously, 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 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.

[0048] On the other hand, it was found that when adjacent core sheets 1a are heated and pressurized at a temperature equal to or higher than the softening temperature of the adhesive layer 11b after pressing adjacent core sheets 1a at a temperature lower than the softening temperature of the adhesive layer 11b, the compressive residual stress generated in the core sheets 1a due to pressing and heating can be reduced. When multiple core sheets 1a pressed in the vertical direction are heated in order from the lower core sheet 1a, the adhesive layer 11b and the base steel plates 11a above and below expand and contract so as to follow each other. In this case, the generation of compressive residual stress in the base steel plate 11a is further suppressed. Therefore, in the manufacturing apparatus 100 according to this embodiment, as described above, the first holding portion 16 and the second holding portion 18 are configured by different members to suppress the heat transfer from the second holding portion 18 to the first holding portion 16, and the temperature rise of the first holding portion 16 is suppressed. In addition, in the second holding section 18, the core sheets 1a are heated and pressed at a temperature equal to or higher than the softening temperature of the adhesive layer 11b, thereby bonding and fixing the core sheets 1a together. This makes it possible to prevent the adhesive layer 11b from softening before the core sheets 1a adjacent in the vertical direction in the first holding section 16 are pressed together. As a result, it is possible to suppress the occurrence of compressive residual stress in each base steel plate 11a in the first holding section 16, and to reduce the iron loss of the laminated core 2. In addition, 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 continuously arranged in the vertical direction. In this configuration, the core sheets 1a pressed downward by the punch 12 are heated one by one from the lower side in the second holding section 18 to a temperature equal to or higher than the softening temperature of the adhesive layer 11b. In the second holding portion 18, the multiple core sheets 1a are gradually heated from the lower side to a temperature above the softening temperature of the adhesive layer 11b, thereby reducing the compressive residual stress generated in each base steel plate 11a and further reducing the iron loss of the laminated core 2.

[0049] In addition, in order to obtain a laminated core of an appropriate shape, it is usually necessary to harden the adhesive layer while applying a large pressure of more than 2.0 MPa from the punch to the multiple core sheets. However, in this case, the frictional force between the adhesive layer and the base steel plate becomes large, and compressive residual stress occurs in the base steel plate, so that iron loss increases. In contrast, in this embodiment, the multiple core sheets 1a are heated while the outer peripheries of the multiple core sheets 1a are held (pressurized in this embodiment) from the sides in the second holding section 18. This makes it possible to harden the adhesive layer 11b between the multiple core sheets 1a (base steel plate 11a) without applying a large pressure to the multiple core sheets 1a in the stacking direction. In this case, it is possible to prevent the frictional force between the adhesive layer 11b and the base steel plate 11a from increasing, and it is possible to sufficiently suppress the generation of compressive residual stress in the base steel plate 11a. As a result, even if the pressure applied from the punch 12 to the multiple core sheets 1a is as low as 2.0 MPa or less, the multiple core sheets 1a can be properly bonded to obtain a laminated core 2 of an appropriate shape.

[0050] (Modification) In the above-described embodiment, the first holding portion 16 and the second holding portion 18 are provided independently of each other. However, as shown in FIG. 6, the first holding portion 16 and the second holding portion 18 may be connected to each other by a plurality of connecting portions 22. In this case, the first holding portion 16 and the second holding portion 18 can be interlocked, so that the configuration of the first holding portion 16 and the second holding portion 18 (the configuration for pressing the holding member 16a and the holding member 18a) can be simplified. The connecting portions 22 may be recesses and protrusions formed on the holding member 16a and the holding member 18a. In this case, for example, the holding member 16a and the holding member 18a can be fixed by crimping the recesses and the protrusions. The connecting portions 22 may be fastening members such as bolts and nuts.

[0051] In the above embodiment, the second holding portion 18 is disposed directly below the first holding portion 16, but 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, the transfer of heat from the second holding portion 18 to the first holding portion 16 can be sufficiently suppressed, and a rise in temperature of the first holding portion 16 can be sufficiently prevented. In this embodiment, the heat insulating member 24 constitutes a connecting portion that connects the first holding portion 16 and the second holding portion 18.

[0052] In the above embodiment, the multiple core sheets 1a are supported by applying pressure to the multiple core sheets 1a from the sides in the first holding section 16 and the second holding section 18, but as shown in Fig. 8, the multiple core sheets 1a may be further supported from below by a support device 26. This allows the multiple core sheets 1a to be supported more stably. The support device 26 is a device that supports the multiple core sheets 1a from below by, for example, hydraulic pressure or the elastic force of an elastic member such as a spring. [Industrial Applicability]

[0053] According to the present invention, a laminated core with small core loss can be manufactured. [Explanation of symbols]

[0054] 1 Steel strip 2 Laminated core 10 Base 12 Punch 14 Punching die 16 1st holding part 18 Second holding part 20 Heating section 22 Connecting part 24 Thermal insulation materials 26 Support device

Claims

1. 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 configured as a separate member from the first holding portion; and a heating section disposed around the second holding section below the first holding section; 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 with a pressure force sufficient to prevent the core sheets from falling, while pressing the core sheets downward with the punch; A laminated core manufacturing apparatus, wherein the plurality of core sheets pressed downward by the punch are held in the second holding section and heated by the heating section.

2. The manufacturing apparatus according to claim 1 , wherein the adhesive layer is a thermosetting adhesive layer.

3. The manufacturing apparatus according to claim 1 , wherein the first holding unit and the second holding unit are connected via a connecting unit.

4. The manufacturing apparatus according to claim 1 or 2, wherein the first holding portion has a vertical length of 5 mm or more.

5. The manufacturing apparatus according to claim 1 , wherein the heating unit includes an infrared heating device.

6. 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 made of a separate member from the first holding section, and a heating section disposed below the first holding section and around the second holding section, punching a plurality of core sheets from a steel strip having an 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 with a pressure force sufficient to prevent the core sheets from falling, while pressing the core sheets downward with the punch; A method for manufacturing a laminated core, comprising: heating the plurality of core sheets pressed downward by the punch by the heating section while holding them in the second holding section.

7. The manufacturing method according to claim 6 , wherein the adhesive layer is a thermosetting adhesive layer.

8. The manufacturing method according to claim 6 or 7, wherein the first holding portion and the second holding portion are connected via a connecting portion.

9. The manufacturing method according to claim 6 or 7, wherein the first holding portion has a vertical length of 5 mm or more.

10. The method according to claim 6 or 7, wherein the punch presses the core sheets with a pressure of 2.0 MPa or less.

11. The manufacturing method according to claim 6 or 7, wherein the heating unit includes an infrared heating device.

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