Laminated iron core manufacturing method and laminated iron core structure

Abstract

[Problem]: To provide: a laminated iron core manufacturing method in which, in a step for outer diameter punching in a progressive die device, an anaerobic photocurable adhesive having both photocuring characteristics and anaerobic-curing characteristics is applied to an iron core thin plate that is to be punched out, and reliable and stable adhesion is performed during a simple step; and a laminated iron core structure. [Solution]: A manufacturing method for manufacturing a laminated iron core by using a progressive die device, wherein, in a step for outer diameter punching with a punch and die in the progressive die device, a notch is made in a side surface of an iron core thin plate, an anaerobic photocurable adhesive is applied to an upper surface and to the notch of the iron core thin plate, a pressing force is applied to a laminate of stacked iron core thin plates to fix the lamination surface of the laminate by virtue of anaerobic curing characteristics, and a side surface of the laminate is irradiated with light to fix the side surface of the laminate by virtue of photocuring characteristics.

Description

Manufacturing method of laminated iron core and laminated iron core structure

[0001] The present invention relates to a manufacturing method and laminated core structure for laminated cores used in motor stators, rotors, etc., and in particular to a manufacturing method and laminated core structure for a laminated core in which, in the outer diameter punching process, which is the final process in a progressive die device, notches are formed in the side of the thin core plate and an anaerobic / light-curing adhesive that has both light-curing and anaerobic-curing properties is applied to the upper surface and notches of the punched thin core plate, firmly bonding the laminated core anaerobically and with light, and to a firmly bonded laminated core structure.

[0002] Conventionally, laminated motor cores, which are annular laminated cores formed by stacking multiple core pieces (or thin plates), have been used for motor stators and the like. Laminated cores for motors are generally manufactured using a progressive die machine from electromagnetic steel hoop material (thin steel strip). In the progressive die machine, the hoop material is sequentially punched to form pilot holes, slots, and inner teeth, continuously forming thin core plates. After punching the outer diameter, a predetermined number of thin core plates are stacked and fixed with adhesive to produce the laminated core.

[0003] Figure 1 is a schematic flow chart of the progressive process for manufacturing a laminated iron core 19, Figure 2 is a plan view showing an example of an iron core thin plate 2 after outer diameter punching, which is the final stage of the progressive process, and Figure 3 is a schematic diagram of a typical progressive die device 3.

[0004] In the first half of the punching process shown in Figure 1, the hoop material 1 is punched in the following order: pilot hole P (#1), inner diameter pilot hole d1 and small hole h for the outer groove (#2), slot portion S (#3), inner diameter d (#4), and inner diameter groove (teeth) m (#5), thereby forming the basic shape of the core sheet 2 excluding the outer diameter. During this process, the hoop material 1 is intermittently transferred within the progressive die device 3 shown in Figure 3, and punched sequentially by punches 5 to 9 attached to the upper die 4, which moves vertically. The punching process is performed by lowering a stripper plate 10 attached to the upper die 4 and bringing the hoop material 1 into contact with the upper surface 11a of the lower die 11.

[0005] Once the first half punching steps (#1 to #5) are completed, the adhesive application step (#6) is carried out. At this time, adhesive is applied to the hoop material 1 by an adhesive applicator 12 installed in the upper die 4 of the progressive die device 3. The adhesive is applied in spots to multiple locations (e.g., about six equally spaced locations) corresponding to the magnetic pole portions J and yoke portions Y between the slot portions S shown in Figure 2. The locations to which the adhesive is applied vary depending on the motor structure and manufacturing method, but if greater strength is required, the number of adhesive surfaces (points) can be increased.

[0006] After the adhesive application step (#6) is completed, the outer diameter punching step (#7) is carried out. At this time, the outer diameter punching punch 13 attached to the upper die 4 of the progressive die device 3 punches out the outer shape D, producing the iron core thin plate 2 as shown in FIG.

[0007] Once the core thin plates 2 are obtained in the outer diameter punching process (#7), the rotary stacking process (#8) is carried out by the rotary drive device 17. At this time, as shown in FIG. 3 , they are stacked on top of the group of core thin plates 15 that have already been punched and stacked inside the rotary die 14, and then they are sequentially pushed into the mold 16 below the rotary die 14. Here, the rotary drive device 17 can rotate the rotary die 14 holding the group of core thin plates 15 by a predetermined angle before the newly punched core thin plates 2 are stacked on top of the group of core thin plates 15. This allows the rotational position of each core thin plate 2 to be changed while being stacked, eliminating the effects of slight thickness deviations that may occur in the core thin plates 2 and enabling the thickness of the product (laminated core) to be controlled with high precision.

[0008] The rotary drive device 17 can also stack the iron core thin plates 2 by dropping them directly downwards without rotating them.

[0009] Once the rotational stacking step (#8) is completed, a heating step (#9) is carried out by a heating device 18. As shown in FIG. 3, the heating device 18 is provided below the mold 16, and the group of core sheets 15 is heated as it moves downward. After heating by the heating device 18, the group of core sheets 15 is separated at the position of each measuring core sheet, and a laminated core 19 as shown in FIG. 4 is formed, which is made up of a predetermined number of core sheets 2. This laminated core 19 is placed on a belt conveyor 20 located below the lower mold 11, and is transported to the next step as appropriate.

[0010] 4 simply shows the outline of the laminated core 19, and does not correspond to the shape of the core thin plates 2 in FIG.

[0011] Japanese Patent Publication No. 2005-340691 Japanese Patent No. 5276303 Japanese Patent No. 6868719 Japanese Patent Publication No. 2009-124828 Japanese Patent Publication No. 2017-216873

[0012] Conventional methods of bonding and fixing laminated cores can be broadly divided into two: one method, as shown in Figure 3, in which the bonding is performed in a progressive die device 3, and another method, in which the cores are stacked on a formwork and then impregnated with adhesive. The method of bonding in a progressive die device 3 requires the progressive die device 3 to be equipped with a dedicated nozzle (discharge port) for introducing adhesive and an adhesive supply device, and bonding is performed in strict synchronization with the operation of the die and press processing device. This results in a complex configuration of the progressive die device 3, as well as the need for operation synchronized with the press and dedicated die maintenance, resulting in increased operating costs. Furthermore, the method of impregnating the cores with adhesive after stacking them on a formwork requires impregnation, drying, and removal processes after stacking the cores, which also creates problems in terms of cost and maintenance.

[0013] In addition to the above-mentioned examples, two-component mixing curing techniques are also widely used for bonding within the progressive die assembly 3. In this two-component mixing method, the first component (primary component) is applied to the top surface (the upper die side of the progressive die assembly 3), while the second component (secondary component) is applied in multiple dots from the bottom surface. This results in a large amount of wasted adhesive, resulting in a large amount of wasted adhesive. Specifically, in this two-component mixing method, the primary component (two-component mixing type) is applied to the top surface of the material sheet (e.g., an electromagnetic steel sheet) that is fed into the progressive die assembly 3, and the secondary component is applied just before pressing within the die. The advantage of this two-component mixing method is that it utilizes press pressure during pressing. Since the secondary component is applied just before pressing during the final outer diameter punching process, the primary component is not applied to areas where other forming loads are applied, so there is no hardening and no adverse effects on other processes. This allows the stacked core to be removed from the die without falling apart.

[0014] If this two-component mixing method is applied as a single-component application, the applied adhesive will drip and drag in the feed direction just before the final process. If the adhesive gets on unintended areas and hardens, it could cause malfunctions in moving parts or harden scrap material, resulting in processing problems. To avoid this problem, application at the final process is essential. If a slow-acting adhesive is used, depending on the product, the laminate will be ejected from the mold within a few tens of seconds and will not harden, causing the laminate to break apart and fail as a finished product. Fast-acting adhesives, such as Aron Alpha (registered trademark), cannot be used because the process itself is a pressing environment, which would interfere with release from the mold and punch.

[0015] The iron cores are laminated in a progressive die device 3 at a high SPM (Shots Per Minute), with individual iron core thin plates (cores) punched out with a punch being laminated together. Conventionally, the mainstream method of preventing loosening was by crimping. In recent years, the movement toward carbon neutrality has become more active, and electrification has progressed, with motors coming into the spotlight as a driving means. Naturally, there is an increasing need for increased volume, higher efficiency, lighter weight, and more compactness, and there is also a strong desire to reduce manufacturing costs and the amount of material resources used.

[0016] Given this background, motors are required to rotate at higher speeds. In response to this demand for greater efficiency, the electromagnetic steel sheets used in motor cores are becoming thinner every year, a trend that is only accelerating. Furthermore, new materials, even ultra-thin materials like amorphous alloys, are now being considered. As laminated materials become thinner, it is obvious that crimped structures no longer provide the necessary holding strength, and adhesive bonding is considered a viable alternative. Furthermore, crimping generates distortion at the crimp and its surrounding area, and accumulates distortion in the surrounding area, primarily resulting in increased iron loss and reduced motor efficiency. Adhesive bonding of laminated cores is also an effective solution. However, adhesive bonding increases costs, requires additional equipment for application and drying, and requires synchronization of maintenance and the pressing process, resulting in both raw material and operating costs. As the need for adhesive bonding of laminated cores increases, cost reduction is also a major requirement.

[0017] The present invention has been made in light of the above-mentioned circumstances, and its object is to provide a method for manufacturing a laminated core that ensures reliable and strong bonding by applying an anaerobic-light-curing adhesive that combines anaerobic curing properties, which have a slow-acting anaerobic hardening function, and light-curing properties, which have a fast-acting light-curing function, to the thin core sheets that are punched out in the outer diameter punching process of a progressive die device, and a laminated core structure in which the top and bottom surfaces and the side surfaces are bonded with the anaerobic-light-curing adhesive. In this method, an anaerobic-light-curing adhesive that combines anaerobic curing properties, which have a slow-acting anaerobic hardening function, and light-curing properties, which have a fast-acting light-curing function, is used, and during the outer diameter punching process, the final step of the progressive die device, notches for bonding are formed on the outer diameter periphery, and the anaerobic-light-curing adhesive is spot-applied to the top surface, and the anaerobic-light-curing adhesive is also applied to the notches in the thin core sheets. Then, pressure is applied to promote anaerobic hardening, and the adhesive is slowly used to promote adhesion between the top and bottom surfaces of the laminate, while light is irradiated onto the sides to quickly harden the adhesive and strengthen the bond, completing the anaerobic hardening while preventing the laminated core from coming apart, thereby achieving strong lamination and adhesion.

[0018] The present invention relates to a manufacturing method for manufacturing a laminated iron core using a progressive die device, and the above-mentioned object of the present invention is achieved by manufacturing a laminated iron core by forming notches in the sides of the thin iron core plates during the outer diameter punching process using the punch and die of the progressive die device, applying an anaerobic light-curing adhesive to the upper surface of the thin iron core plates and to the notches, applying a pressing force to a stack of stacked thin iron core plates to bond the stacking surfaces of the stack using the anaerobic curing properties of the anaerobic light-curing adhesive, and irradiating the sides of the stack with light to bond the sides of the stack using the light-curing properties of the anaerobic light-curing adhesive.

[0019] Furthermore, the above-mentioned object of the present invention is achieved by the fact that the top surface of the thin iron core plate and the bottom surface of the adjacent thin iron core plate are sequentially bonded together using the anaerobic curing properties of an anaerobic, light-curing adhesive, and the adhesive grooves consisting of notches provided on the side surfaces of the thin iron core plates are bonded together using the light-curing properties of the anaerobic, light-curing adhesive.

[0020] According to the laminated core manufacturing method of the present invention, in the final outer diameter punching process of the progressive die device, an anaerobic / photo-curing adhesive that combines fast-acting photo-curing properties and slow-acting anaerobic curing properties is applied to the notches on the top surface and side of the punched core thin plates. This allows the laminated core to be bonded and fixed on two surfaces, the top and bottom surfaces and the side surfaces, without requiring a particularly complex progressive die device structure, resulting in a strong laminated core. Furthermore, because an anaerobic / photo-curing adhesive is used as the adhesive and is applied to the surfaces and side surfaces of the core thin plates, a strong laminated core can be manufactured effectively and economically.

[0021] The adhesive applied to the sides of the thin core plates is a temporary fixation, and its main purpose is to prevent the laminated core from falling apart until the slow-acting anaerobic curing between the top and bottom surfaces is complete. This effect allows the adhesive to be applied to the top surfaces of the thin core plates and the temporary fixation light curing to be completed in the final process, preventing the laminate from falling apart when it is output from the mold. Naturally, there is no need to apply the primary agent (adhesive) to the entire surface, which reduces the amount of adhesive used. While conventional methods do not harden, the primary agent remains within the mold, and special cleaning of the entire mold is required for periodic removal or when disassembling the mold for maintenance. However, this invention does not require such maintenance or cleaning.

[0022] Furthermore, the present invention reduces the amount and type of adhesive used (from two-component to one-component), which reduces costs and makes management easier.Furthermore, since the adhesive liquid does not get on the waste material, there is an advantage in that it can suppress increases in costs for maintenance and waste material disposal.

[0023] 1 is a schematic flow chart showing an example of a progressive process. FIG. 2 is a plan view of the thin iron core plate after punching. FIG. 3 is a schematic configuration diagram of a progressive die device. FIG. 4 is a perspective view showing an example of a laminated iron core. FIG. 5 is a plan view showing an example of a thin iron core plate of the present invention. FIG. 6 is a perspective view showing a prototype of the laminated iron core of the present invention. FIG. 7 is a plan view for explaining the application of adhesive of the present invention. FIG. 8 is an external view showing a schematic method for manufacturing a laminated iron core (linear grooves) of the present invention. FIG. 9 is a flowchart showing an example of the operation of the present invention. FIG. 10 is an external view showing a schematic method for manufacturing a laminated iron core (spiral grooves) of the present invention. FIG. 11 is a schematic view showing an example of a punching process and a bonding process. FIG. 12 is a schematic view showing an example of a punching process and a bonding process.

[0024] The present invention is a manufacturing method for manufacturing a laminated iron core using a progressive die device, in which, during the outer diameter punching process using the punch and die of the progressive die device, a semicircular or triangular notch is made in the circular side of a thin iron core plate such as an electromagnetic steel plate, and an anaerobic, light-curing adhesive is applied to the upper surface and notch of the thin iron core plate. A pressing force is applied to the stack of stacked thin iron core plates to bond the stacking surfaces of the stack using the anaerobic curing properties of the anaerobic, light-curing adhesive, and light is irradiated onto the side of the stack to bond the side of the stack using the light-curing properties of the anaerobic, light-curing adhesive, resulting in the production of a firmly bonded laminated iron core.

[0025] That is, in the present invention, in the outer diameter punching process, which is the final process of the progressive die device, in addition to punching out the necessary teeth and other core shapes, a punch is also used to punch out notches 101, which are semicircular recesses as shown in Fig. 5(A), or notches 102, which are triangular recesses as shown in Fig. 5(B), on the periphery of the core thin plate 100. For example, the laminate 120, which has been punched out with notches 102 and dropped into a mold without rotation and stacked, has the external shape shown in Fig. 6, with linear adhesive grooves 102A formed on the side surface by the notches 102.

[0026] The shape of the notch provided on the periphery of the iron core thin plate 100 is not limited to a semicircular or triangular shape, and other shapes may be used as appropriate.

[0027] In forming such a laminate 120, in the present invention, when forming the laminate 120 in the outer diameter punching step, an anaerobic / photo-curing adhesive 110 having both photo-curing and anaerobic curing properties is applied to the upper surface and the notches 102 on the side of the core thin plates 100 as shown in Fig. 7. The anaerobic / photo-curing adhesive 110 is applied to the notches 102 of all the punched core thin plates 100, but is not applied to the upper surface of the last punched core thin plate 100.

[0028] As shown in Figure 8, the core thin plates 100, with the anaerobic photo-curing adhesive 110 applied to their upper surfaces and peripheral notches 102, are dropped one by one and placed in a mold, resulting in a laminated core prototype (laminated body). The anaerobic curing adhesive 110 is applied to the upper surfaces of the core thin plates 100 in spots from an outlet on the bottom of the punch at the same time as punching. In Figure 8, three spots are shown, but the amount and locations of application can be changed as needed; the more spots there are, the stronger the adhesive strength. Furthermore, because the notches 102 are small, the anaerobic curing adhesive 110 is applied to the notches 102 using a directional nozzle, and can be applied either when punching the core thin plates 100 or after stacking. When the thin iron core plates 100 with the anaerobic / light-curing adhesive 110 applied to their upper surfaces and notches 102 are stacked, the anaerobic / light-curing adhesive 110 has been applied to the upper surface of the previous thin iron core plate 100 that was dropped just before, so that adhesive 110 is sequentially adhered to the bottom surface of the thin iron core plate 100 that is being dropped this time as they are stacked. Since the anaerobic / light-curing adhesive 110 has also been applied to the notches 102 of the thin iron core plates 100, they are stacked with the anaerobic / light-curing adhesive 110 applied to the adhesive grooves as shown in Figure 8.

[0029] Since the shapes of the teeth and the like required for the stator of a motor are punched into the core thin plate 100, the adhesive is applied in spots so as not to come into contact with or overlap these parts. In order to achieve this strong adhesion, it is desirable to apply the adhesive in many spots.

[0030] Then, a predetermined number of laminates 120 stacked on a mold are pressed downward to seal the laminates and seal off the air. The anaerobic curing action of the adhesive 110 hardens and bonds adjacent core thin plates 100 vertically. At the same time, or prior to this, visible or ultraviolet light is irradiated onto the adhesive 110 applied to the side adhesive grooves 102A, allowing the adhesive 110's rapid photo-curing action to quickly and linearly bond the side adhesive grooves 102A, thereby maintaining the integrity of the laminate. Because anaerobic curing is slow-acting and photo-curing is rapid-acting, the photo-curing of the side surfaces tends to complete first, followed by the anaerobic curing, resulting in a strong bond. In this way, a strong laminated core can be obtained, with the top and bottom surfaces of the laminate firmly bonded and the sides also bonded.

[0031] 9 is a flowchart showing an example of a manufacturing method of a laminated core according to the present invention, in which in an outer diameter punching step with a progressive die device, outer diameter punching is performed and notches 102 (or 101) as shown in FIG. 5(B) (or FIG. 5(A)) are formed to form the thin core plate 100 (step S10). Then, as shown in FIGS. 7 and 8, an anaerobic / light-curing adhesive 110 is spot-applied to the upper surface of the thin core plate 100 using a discharge port during punching (step S20), and the anaerobic / light-curing adhesive 110 is also applied to the notches 102 (or 101) using a nozzle from a die or the like (step S30).

[0032] The thin iron core plates 100 coated with the anaerobic / photo-curing adhesive 110 are sequentially stacked on a mold (step S40). When a predetermined number of sheets have been stacked, a top cover is placed on the thin iron core plates 100, and a pressing force is applied from above using a pressing means (not shown) (step S50). The anaerobic curing properties of the anaerobic / photo-curing adhesive 110 cause adjacent thin iron core plates 100 in the stack to harden and bond together, resulting in a slow-acting bond. At the same time, light (visible light or ultraviolet light) is irradiated onto the anaerobic / photo-curing adhesive 110 applied to the adhesive grooves 102A on the side surfaces of the stack. The photo-curing properties of the anaerobic / photo-curing adhesive 110 quickly harden and bond the sides of the thin iron core plates 100 in the stack, maintaining the shape of the stack (step S60). By stacking these thin iron core plates 100, applying pressure (anaerobic curing), and irradiating them with light (photocuring), a firmly bonded laminated iron core is manufactured (step S70), and then it is transported to a predetermined location on a belt conveyor or the like and used (step S80).

[0033] In the above-described embodiment, in the outer diameter punching process, the punched core thin plate 100 is dropped without being rotated, and linear adhesive grooves are formed as shown in Figures 6 and 8. However, it is also possible to stack the sheets while rotating them when dropping them, and form inclined or spiral adhesive grooves as shown in Figure 10.

[0034] In the above-described embodiments, one adhesive groove is used, but two or more adhesive grooves may be used. In this case, by providing adhesive grooves at opposing positions, well-balanced adhesion can be achieved.

[0035] Figures 11 to 13 show specific examples of adhesive application during the punching process. In the example shown in Figure 11, the die 142 does not have a rotation function. After being dropped straight down to the specified thickness H1, it is irradiated with light and rotated. An adhesive 110 outlet is provided on the bottom surface of the outer diameter punching punch 141, and adhesive 110 is supplied to the outlet via a pipe. Simultaneously with punching, adhesive 110 is spot-applied to the surface from the outlet on the bottom of the punch. The lower die 142 also has a nozzle for discharging adhesive 110, and adhesive 110 is supplied to the nozzle via a pipe. During punching using the die 142, adhesive 110 is applied to the side (notch) of the core thin plate 100 via the nozzle. The stacked laminate is then pressed against the container 140 for anaerobically curing, and the side surfaces are fixed by rotating and irradiating with light. In this example, since the die 142 does not have a rotation function, the laminated core in this case has the shape shown in Figure 8.

[0036] The step d2 is provided to allow the adhesive to collect there.

[0037] The example in Fig. 12 has a configuration similar to that in Fig. 11, but the die 142A has a rotation function, and the falling core thin plate 100 is rotated as it falls, and adhesive 110 is applied to the side surfaces. The specified thickness H1 is achieved by rotating the thin plate. In this case, the laminated core takes the form shown in Fig. 10, for example. In this example, the laminates stacked in the container 140 are rotated or moved to another position by a rotation mechanism or a movement mechanism, and then adhered.

[0038] 13, no adhesive is supplied to die 142A, and after lamination, the laminated core as shown in Fig. 6 is moved to and accommodated in container 140, and adhesive is applied to the adhesive grooves of the laminated core. In this case, die 142A has the shape shown in Fig. 8 if it does not have a rotation function, and the shape shown in Fig. 10 if it does have a rotation function.

[0039] In the above description, an anaerobic light-curing adhesive is used as the adhesive, but ultraviolet anaerobic curing adhesives and visible light anaerobic curing adhesives are also commercially available; for example, "BU-810" manufactured by Toa Gosei Co., Ltd. can be used.

[0040] Furthermore, although the laminated core has been described above as having a circular ring shape, it can also be applied to a disk or a rectangle. The material has been described as being an electromagnetic steel sheet, but it can also be applied to an amorphous material, and any soft magnetic material will do.

[0041] 1 Hoop material 2 Iron core thin plate 3 Progressive die device 4 Upper die 5 to 9 Punch 10 Stripper plate 11 Lower die 12 Adhesive application device 13 Outer diameter punching punch 14 Rotary die 15 Iron core thin plate group 16 Formwork 17 Rotation drive device 18 Heating device 19 Laminated iron core 20 Belt conveyor 100 Iron core thin plate 101, 102 Notch 102A Adhesive groove 110 Anaerobic / photocuring adhesive 120 Laminated body 130 Vibrator 140 Container 141 Outer diameter punching punch 142, 142A Die 143 Rotation mechanism (or movement mechanism)

Claims

1. A manufacturing method for manufacturing a laminated iron core using a progressive die device, characterized in that in the outer diameter punching process of the punch and die of the progressive die device, notches are made in the sides of the iron core thin plates, and an anaerobic, light-curing adhesive is applied to the upper surface of the iron core thin plates and to the notches, a pressing force is applied to the stack of stacked iron core thin plates to fix the stacking surfaces of the stack using the anaerobic curing properties of the anaerobic, light-curing adhesive, and light is irradiated onto the sides of the stack to fix the sides of the stack using the light-curing properties of the anaerobic, light-curing adhesive, thereby manufacturing a laminated iron core.

2. A method for manufacturing a laminated core as set forth in claim 1, wherein the application of the anaerobic light-curing adhesive to the upper surfaces of the thin core plates and the notches is carried out during the punching-out process of the thin core plates.

3. A method for manufacturing a laminated iron core as described in claim 1 or 2, wherein the application of the anaerobic, light-curing adhesive to the upper surface of the iron core thin plate is carried out in a spot manner using an outlet provided on the bottom surface of the punch, and the application of the anaerobic, light-curing adhesive to the notches in the iron core thin plate is carried out using a nozzle provided on the surface of the die.

4. A method for manufacturing a laminated core according to claim 3, wherein the irradiation of the side surfaces of the laminate with light is carried out in conjunction with a press machine.

5. A method for manufacturing a laminated core according to claim 3, wherein the thin core plates are dropped into a folder and then irradiated with light after reaching a specified height.

6. A method for manufacturing a laminated core according to claim 1 or 2, wherein the material of the laminated core is a soft magnetic material.

7. A method for manufacturing a laminated core according to claim 1 or 2, wherein the shape of the notch is semicircular or triangular.

8. A laminated core structure characterized in that the top surface of a thin core plate and the bottom surface of an adjacent thin core plate are sequentially bonded together using the anaerobic curing properties of an anaerobic, light-curing adhesive, and adhesive grooves consisting of notches provided on the side surfaces of the thin core plates are bonded together using the light-curing properties of the anaerobic, light-curing adhesive.

9. The laminated core structure according to claim 8, wherein the shape of the notch is semicircular or triangular.

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