Laminate core and production method therefor

Abstract

To provide a laminate core in which, even if a high strength silicon steel sheet, or particularly a high strength silicon steel sheet having a sheet thickness of less than 0.2 mm is used, a great caulk fastening force and excellent magnetic characteristic are obtained by combination use of caulk fastening and adhesion, and the outermost peripheral length is 315 mm or less, and a production method for the laminate core.SOLUTION: A laminate core is formed by stacking a plurality of silicon steel sheets 25. The laminate core includes the stacked silicon steel sheets, and has an adhesive between the stacked silicon steel sheets. The silicon steel sheets are provided with a caulk fastening part. The laminate core has an outermost peripheral length of 315 mm or less.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a laminated core having a maximum outer periphery length of 315 mm or less, which is manufactured using thin, high-strength silicon steel sheets (particularly, less than 0.2 mm thick, YS≧350 MPa), and a method for manufacturing the same. [Background technology]

[0002] When manufacturing laminated cores using standard silicon steel sheets (Si content 4% or less, thickness 0.2 mm or more), crimping is often used. However, high-strength silicon steel sheets, due to the high content of added elements such as Si, tend to be hard and have a high Young's modulus, which makes them prone to springback after processing. Therefore, there is a concern that the crimped portion, which was fastened inside the die due to the pressure from the surroundings, may loosen due to springback when ejected from the die, reducing the fastening force of the crimp. In particular, for silicon steel sheets less than 0.2 mm thick, the thin sheet thickness results in a shallow crimp depth, which tends to weaken the fastening force of the crimp. While the crimping depth is typically the same as the sheet thickness, the thin sheet thickness reduces the contact area at the crimped portion. Furthermore, for cores of the same stack height, thinner sheets require more laminates, which tends to weaken the fastening force of the laminated core.

[0003] As described above, when manufacturing a laminated core using silicon steel plates having a thickness of less than 0.2 mm, it is difficult to manufacture a laminated core that is fastened only by crimping, and a method of using both crimping and adhesive is known.

[0004] For example, Patent Document 1 describes a method for obtaining high core strength by gluing the crimped portions of a laminated core having a diameter and maximum length exceeding 100 mm. Also, when manufacturing a laminated core using silicon steel plates less than 0.2 mm thick, they are often fastened by gluing.

[0005] Patent Document 2 describes a method for manufacturing a laminated core by applying adhesive after punching and lamination, and Patent Document 3 describes a laminated core manufacturing device that performs adhesive application, outline punching, and lamination as part of a series of processes on a laminated core manufacturing line. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-164389 [Patent Document 2] Patent No. 4987215 [Patent Document 3] Japanese Patent Application Laid-Open No. 2013-48555 Summary of the Invention [Problem to be solved by the invention]

[0007] However, Patent Document 1 does not disclose anything about small laminated cores with a diameter and maximum length of 100 mm or less. The restriction of 100 mm or less limits the number and location of crimps due to area constraints, resulting in the problem of insufficient core strength. Furthermore, with the method described in Patent Document 1, it is difficult to apply a sufficient amount of adhesive around the crimped portion. Furthermore, even if crimping is used, in cases where a crimping method creates cut end surfaces at the crimped portion (such as V-shaping), the cut end surfaces may come into contact and short-circuit at the crimped portion, forming a magnetic path and deteriorating the magnetic properties of the laminated core.

[0008] Furthermore, the methods described in Patent Documents 2 and 3 are designed assuming that the steel plate is flat, making it difficult to apply adhesive to the back surface of the steel plate, which has unevenness due to the crimping used in the present invention.

[0009] The present invention has been made in view of the above, and aims to provide a laminated core having an outermost circumference of 315 mm or less, which can obtain high crimping force and excellent magnetic properties by combining crimping and adhesive fastening, even when using high-strength silicon steel sheets, especially high-strength silicon steel sheets with a thickness of less than 0.2 mm, and a method for manufacturing the same. [Means for solving the problem]

[0010] The present inventors have conducted extensive research to achieve the above-mentioned object and have found the following. (1) When manufacturing a laminated core with an outermost circumference of 315 mm or less using high-strength silicon steel plates, the springback that occurs during crimping can be suppressed by using both adhesive and crimping as a fastening method for the laminated core, and a laminated core with sufficient fastening strength can be obtained. (2) In particular, when manufacturing laminated cores using only crimping with thin silicon steel sheets, such as those with a thickness of less than 0.2 mm, the large number of laminated sheets results in a small crimp depth per sheet, which tends to result in a small crimping force.By using both adhesive and crimping, it is possible to obtain the desired crimping force, as well as suppress the formation of magnetic paths caused by contact and short-circuiting between the cut end faces at the crimped portion, thereby improving the magnetic properties of the laminated core. (3) Furthermore, by applying adhesive to the crimped fastening portion, sufficient fastening force can be obtained in the crimped fastening. (4) In the press process for manufacturing the fastening core by crimping, by placing an independent adhesive application device inside the mold, adhesive can be applied to the convex portion (protrusion forming portion) such as the crimped portion before the process of fastening the crimped portion.

[0011] The present invention has been made based on the above findings. That is, the gist and configuration of the present invention are as follows. [1] A laminated core made by laminating multiple silicon steel plates, A laminated core having a maximum outer circumference of 315 mm or less, which has laminated silicon steel plates, an adhesive between the laminated silicon steel plates, and a crimped fastening portion on the silicon steel plates. [2] The laminated core according to [1], wherein the adhesive is provided at least in the crimped fastening portion. [3] The laminated core according to [1] or [2], wherein the adhesive is insulating. [4] The laminated core according to any one of [1] to [3], wherein the thickness of the silicon steel plate is less than 0.2 mm. [5] The laminated core according to any one of [1] to [4], wherein the silicon steel plate has a yield strength of 350 MPa or more. [6] A method for producing the laminated core according to any one of [1] to [5], a die having a molding step and a punching step for manufacturing the laminated core, the die having a molding step and a punching step, and a step of applying the adhesive to the silicon steel plate including the crimped portion from the back side in the punching direction after forming a protrusion on the silicon steel plate by crimping and before punching out the outer shape of the silicon steel plate. [7] The method for manufacturing a laminated core according to [6], wherein a dispenser independent of the mold is disposed within the mold, and adhesive is applied to the silicon steel plate from the dispenser in a non-contact manner. [Effects of the Invention]

[0012] According to the present invention, a laminated core having a high crimping force and excellent magnetic properties can be obtained. [Brief explanation of the drawings]

[0013] [Figure 1] 10 is an example showing the laminated core for evaluation and the position of the crimping fastening. [Figure 2] 3 is a flowchart illustrating a method for manufacturing a laminated core according to an embodiment of the present invention. [Figure 3] 1A and 1B are diagrams showing an example of a manufacturing process for a laminated core according to an embodiment of the present invention, in which (a) is a top view and (b) is a side view. [Figure 4] FIG. 1 is a schematic diagram of an adhesive application device. [Figure 5] 1 is an example showing a schematic cross-sectional view of a laminated core manufactured using V-caulking. [Figure 6]1 is a cross-sectional view of a laminated core manufactured using dowel crimping; DETAILED DESCRIPTION OF THE INVENTION

[0014] The following describes an embodiment of the present invention. However, the present invention is not limited to this embodiment. In addition, in the drawings, the same parts are denoted by the same reference numerals.

[0015] The silicon steel sheets used in the laminated core of the present invention may be ordinary silicon steel sheets.

[0016] The thickness is not particularly limited, but the thinner the silicon steel sheets that are stacked, the better the magnetic properties become, so a thickness of less than 0.2 mm is preferable, and steel sheets with a thickness of 0.1 to 0.15 mm are particularly useful.

[0017] The yield strength of silicon steel sheet is not particularly limited, but it is preferable that it be 350 MPa or more for the following reasons. Thinner sheets are desirable because magnetic properties improve as the sheet thickness decreases. However, steel sheets used for motor rotors, for example, are required to have a certain strength because high stress is applied to the rotor due to the centrifugal force applied to the magnet. Although there is no particular upper limit, from the viewpoint of workability and toughness, it is preferable that the yield strength be 750 MPa or less.

[0018] The laminated core of the present invention is manufactured by using both an adhesive and crimping, that is, it is a laminated core in which an adhesive is applied between silicon steel plates and the plates are crimped.

[0019] The adhesive is preferably applied to the crimped fastening portion, but is not limited thereto. The reason why it is preferable to apply the adhesive only to the crimped fastening portion is that it can further suppress springback of the silicon steel sheet after ejection from the mold, maximize the effectiveness of the crimping, and strengthen the fastening force of the crimped fastening portion. Furthermore, it has the advantage of reducing the amount of adhesive used compared to when the entire surface is bonded. By reducing the amount of adhesive used, the space occupied by the adhesive can be reduced, thereby maintaining a higher core space factor. Furthermore, applying an insulating adhesive to the crimped fastening portion also prevents short circuits at the crimped fastening portion. These effects prevent deterioration of the magnetic properties of the laminated core. Furthermore, to optimize the amount of adhesive used and achieve excellent crimping force, the area where the adhesive is applied is preferably 80% or more and 150% or less of the crimped fastening portion. More preferably, the area where the adhesive is applied is 100% or more and 120% or less of the crimped fastening portion.

[0020] Figure 1 shows an example of a laminated core for evaluation and the positions of crimping. The laminated core for evaluation is a laminated core with an outer diameter of 20 mm, an inner diameter of 12 mm, and a stacking thickness of 7 mm. In Figure 1, V-crimping is performed at V-crimping position 1, but typically, when performing V-crimping as shown in Figure 5 or dowel crimping as shown in Figure 6, it is often performed at four positions. The crimping depth is preferably 0.1 to 0.3 mm, and more preferably 0.15 to 0.25 mm.

[0021] The size of the laminated core is such that the outermost circumference of the laminated core is 315 mm or less. This is equivalent to the diameter and maximum length of the laminated core being 100 mm or less. Here, if the laminated core is cylindrical, this refers to a diameter of 100 mm or less. If the laminated core is polygonal, this refers to a maximum length of 100 mm or less, which is the longest distance from one vertex to the opposite vertex across the center of the laminated core. Note that a cylindrical laminated core also includes a polygonal laminated core with a polygonal base. The outermost circumference of the laminated core is set to 315 mm or less for the following reasons: For example, as the core diameter increases, the teeth (a collective term for the portions of the motor core that protrude outward or inward from the annular portion) also become longer. If such teeth are to be secured by means of a small contact area, such as a crimped fastening portion, and then laminated, lifting occurs in areas other than the crimped fastening portion, making it impossible to manufacture the desired laminated core. A preferred length is 120 mm or less.

[0022] Laminated cores also include those formed by dividing the above-mentioned cylindrical or polygonal cores into equal parts with the center of the core as the axis. The number of divisions is not particularly limited, but most are divided into 3 to 20 equal parts, and more preferably into 3 to 8 equal parts. The divided cores are combined together to form a circular motor.

[0023] Another example of a laminated core is a folded core in which a plurality of T-shaped or I-shaped cores are connected in the horizontal direction.

[0024] Finally, the silicon steel plate is punched into a ring shape, a polygonal ring shape, or a divided shape as described above, and multiple silicon steel plates of the same shape are stacked to produce a laminated core.

[0025] The manufacturing method of the laminated core will be described in detail below with reference to FIGS.

[0026] Fig. 2 is a flowchart showing a manufacturing method of a laminated core according to an embodiment of the present invention. S1 is a step of punching out stator slots 20, S2 is a step of forming protrusions of V-shaped crimps 21, S3 is a step of applying adhesive using an adhesive applicator (dispenser) 24 installed outside the mold, S4 is a step of punching out the outer shape of the stator, and S5 is a step of stacking the steel plates whose outer shapes have been punched and fastening the stacked steel plates by crimping. Fig. 3 is a schematic example of a manufacturing process of a laminated core according to an embodiment of the present invention.

[0027] 2 and 3, the manufacturing method of the laminated core of this embodiment is carried out in the following order of steps S1 to S5 using a silicon steel sheet punching die 3. These steps include punching stator slots 20 from silicon steel sheet 2 (step S1), forming V-shaped crimp protrusions on the punched silicon steel sheet at V-shaped crimp fastening positions 1 in FIG. 1 (step S2), applying liquid adhesive to the back side of the punched silicon steel sheet in the punching direction using an adhesive applicator (dispenser) 24 (step S3), punching out the outline of the stator (step S4), stacking the punched steel sheets, and crimping the stacked steel sheets (step S5).

[0028] <Step S1> In step S1, the silicon steel plate described above is punched into a predetermined shape using a die, preferably at a punching speed in the range of 100 to 400 SPM.

[0029] <Step S2> In step S2, a silicon steel plate (core material) 2 punched into a predetermined shape is subjected to the formation of, for example, V-shaped protrusions at V-shaped fastening positions 1 in Fig. 1 (forming step). In Fig. 1, V-shaped fastening is performed at V-shaped fastening position 1, but typically, when V-shaped fastening as shown in Fig. 5 or dowel fastening as shown in Fig. 6 is performed, it is often performed at four positions. The depth of the fastening is preferably 0.1 to 0.3 mm, and more preferably 0.15 to 0.25 mm.

[0030] <Step S3> In the present invention, step S3, in which adhesive is applied after forming the protrusions by crimping and before the crimping process, is particularly important. In the die used to punch and form silicon steel sheets, a small space is provided immediately before the crimping process. This small space is used to install an adhesive applicator 24 that applies adhesive to the backside of the steel sheet. Figure 4 shows a schematic diagram of the adhesive applicator (dispenser) 24. The adhesive applicator (dispenser) 24 is composed of an auxiliary outlet part 11 equipped with a heating mechanism and air pressure control, a dispenser main body 18, an adhesive storage section 14, and an adhesive supply section 15. The dispenser main body 18 is equipped with an adhesive outlet 12. It is preferable to position the dispenser independently of the die within the die. When operating alone, this applicator mainly applies instant adhesive through the adhesive outlet 12. On the other hand, for applications requiring heat resistance, for example, a heat-resistant adhesive is required, so another dispenser body 19 is placed in parallel and heat-resistant adhesive is dispensed from adhesive outlet 13. Both adhesive outlets 12 for the instant adhesive and 13 for the heat-resistant adhesive are applied. The instant adhesive is sent from adhesive storage unit 14 to adhesive supply unit 15 and dispensed from adhesive outlet 12 attached to dispenser body 18. Similarly, heat-resistant adhesive is sent from adhesive storage unit 16 to adhesive supply unit 17 and dispensed from adhesive outlet 13 attached to dispenser body 19. The adhesive applicator (dispenser) 24 is preferably small, preferably smaller than 100 mm x 100 mm x 100 mm. The areas where adhesive is applied to the backside of the steel sheet are 22 and 22(a) shown in S3 of Figure 3. Furthermore, a device that can apply adhesive to the steel plate without contact is desirable, and the timing of applying the adhesive can be adjusted by the feed speed (pitch) of the steel plate.

[0031] Conventional die-bonding methods use an adhesive application mechanism prior to the beveled area, which applies adhesive to the backside of the steel sheet. After the beveled area is reached, the sheet is laminated and bonded within the die. This mechanism is designed to accommodate flat steel sheets, making it difficult to apply adhesive to the backside of a steel sheet with irregularities caused by crimping, as in the present invention. In contrast, the present invention uses a non-contact adhesive spray to apply adhesive to the backside of the steel sheet, making it possible to apply adhesive to the irregular backside of the steel sheet. In particular, even when applying adhesive only to the crimped area, applying the above method allows for precise application of the appropriate amount of adhesive, resulting in improved fastening strength and prevention of magnetic property degradation. Furthermore, compared to when the steel plates are bonded inside a die used to punch the steel plates, the equipment requires less space.

[0032] <Step S4> In step S4, the outer shape 23 of the stator is punched out. The punching speed is preferably in the range of 100 to 400 SPM.

[0033] <Step S5> In step S5, the punched silicon steel sheets 2 are stacked and the stacked punched silicon steel sheets 2 are crimped together. In order to prevent warping of the laminated core when stacking the punched silicon steel sheets 2, it is also possible to manufacture the laminated core by supporting the laminated core in the die with a hydraulic cylinder. [Example]

[0034] The effects of the present invention will be specifically explained below based on examples, but the present invention is not limited to these examples.

[0035] Using a mold with the layout shown in Figure 3, a laminated core with the shape shown in Figure 1, equipped with crimping and adhesive, was fastened to silicon steel plates. Specifically, a silicon steel plate with a thickness of 0.1 mm was punched, and a V-shaped protrusion was formed in one location in the center of the core on the silicon steel plate with the stator slot punched out. Then, adhesive was applied using an adhesive applicator installed outside the mold, the stator outline was punched out, and the punched steel plate was stacked and V-fastened. Various levels of adhesive application were prepared: one in which adhesive was applied to the entire steel plate, one in which adhesive was applied only to the crimped areas, and especially, the levels in which adhesive was applied only to the crimped areas, with the adhesive applied to the area of ​​the crimped areas at area ratios of 60%, 85%, and 120%.

[0036] Table 1 shows the fastening strength, iron loss, and adhesive usage of the laminated core manufactured as described above. For comparative examples, the results of a laminated core manufactured using only crimping and a laminated core manufactured using only full surface bonding are also shown. For fastening strength and iron loss, the results of crimping only were used as the standard, and the rate of change relative to the results of crimping only was calculated, and a relative evaluation was made. For adhesive usage, the results of full surface bonding only were used as the standard, and the rate of change relative to the results of full surface bonding was calculated, and a relative evaluation was made.

[0037] <Method for evaluating fastening strength> The fastening strength was evaluated by applying double-sided tape (3M Scotch Super Strong Double-Sided Tape Premier Gold (registered trademark) Multi-purpose product number: SPG-19) to the top and bottom surfaces of the laminated core, and measuring the breaking strength when the laminated core was broken when it was pulled apart in the vertical direction using a tabletop tensile tester (load cell for measuring load). The fastening strength of a laminated core manufactured using a conventional manufacturing method using only crimping was set at 1.0, and a fastening strength of over 1.0 was judged to have passed the test.

[0038] <Iron loss evaluation method> Iron loss was evaluated by winding a laminated core and exciting it with an AC magnetic field of maximum magnetic flux density 1T and frequency 400Hz (W10 / 400).The iron loss of a laminated core laminated using a manufacturing method that only involves crimping is set at 1.00, and an iron loss of less than 1.00 was deemed to have passed the standard.

[0039] As can be seen from the results in Table 1, all of Nos. 3 to 6, which are laminated cores that combine crimping and bonding according to the present invention, had a fastening strength of over 1.0 and an iron loss of less than 1.00. In contrast, No. 1, a laminated core that is only crimped and No. 2, which is only fully bonded, which are comparative examples, failed to pass either the fastening strength or the iron loss. Furthermore, Nos. 3 to 6, which are invention examples, used an amount of adhesive of 1.000 or less, and in particular, Nos. 4 to 6, which were bonded only at the crimped portions, used an amount of adhesive of 0.100 or less, demonstrating excellent fastening strength and iron loss, as well as a significant reduction in the amount of adhesive used compared to fully bonded cores.

[0040] [Table 1] [Explanation of symbols]

[0041] 1 V-crimping position 2 Silicon steel sheet after punching 11 Auxiliary parts for discharge port 12 Adhesive outlet 13 Adhesive outlet 14 Adhesive reservoir 15 Adhesive supply section 16 Adhesive reservoir 17 Adhesive supply section 18 Dispenser body 19 Dispenser body 20 Stator slot 21 V-crimp 22, 22(a) Adhesive application area 23 Outline after punching 24 Adhesive application device (dispenser) 25 Silicon steel plate 26 Silicon steel sheet after punching 27 Laminated steel plates

Claims

1. A laminated core made by laminating multiple silicon steel plates, A laminated core having a maximum outer periphery length of 315 mm or less, which has laminated silicon steel plates, an adhesive between the laminated silicon steel plates, and a crimped fastening portion on the silicon steel plates.

2. 2. The laminated core according to claim 1, wherein the adhesive is provided at least in the crimped fastening portion.

3. 2. The laminated core according to claim 1, wherein the adhesive is insulating.

4. 3. The laminated core according to claim 2, wherein the adhesive is insulating.

5. 2. The laminated core according to claim 1, wherein the thickness of said silicon steel plates is less than 0.2 mm.

6. 3. The laminated core according to claim 2, wherein the thickness of said silicon steel plates is less than 0.2 mm.

7. 4. The laminated core according to claim 3, wherein the thickness of said silicon steel plates is less than 0.2 mm.

8. 5. The laminated core according to claim 4, wherein the thickness of said silicon steel plates is less than 0.2 mm.

9. 9. The laminated core according to claim 1, wherein the silicon steel plates have a yield strength of 350 MPa or more.

10. A method for producing the laminated core according to any one of claims 1 to 8, comprising the steps of: a die having a molding step and a punching step for manufacturing the laminated core, the die having a molding step and a punching step, and a step of applying the adhesive to the silicon steel plate including the crimped portion from the back side in the punching direction after forming a protrusion on the silicon steel plate by crimping and before punching out the outer shape of the silicon steel plate.

11. A method for manufacturing the laminated core according to claim 9, comprising the steps of: a die having a molding step and a punching step for manufacturing the laminated core, the die having a molding step and a punching step, and a step of applying the adhesive to the silicon steel plate including the crimped portion from the back side in the punching direction after forming a protrusion on the silicon steel plate by crimping and before punching out the outer shape of the silicon steel plate.

12. The method for manufacturing a laminated core according to claim 10, wherein a dispenser independent of the mold is disposed within the mold, and the adhesive is applied to the silicon steel plate from the dispenser in a non-contact manner.

13. The method for manufacturing a laminated core according to claim 11, wherein a dispenser independent of the mold is disposed within the mold, and the adhesive is applied to the silicon steel plate from the dispenser in a non-contact manner.

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