Manufacturing method and manufacturing device for laminated core

Abstract

When manufacturing a laminated core by heating a laminate 2 having a plurality of core sheets 1a laminated via adhesive layers 11b, four heating elements 30 that radiate near-infrared rays are provided so as to surround the laminate 2. Each heating element has a temperature coefficient of 0.38<0.88((W-D1) / W) 0.22 ×((L-D1) / L) 0.20 ≦1.0". In the above formula, W represents the distance between the opposing heating elements 30, D1 represents the diameter of the laminate 2, and L represents the length of the heating element 30.

Description

[Technical Field]

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

[0002] Laminated cores having a configuration in which multiple electromagnetic steel sheets are stacked are used as cores for rotating electrical machines, etc. One known method for manufacturing laminated cores is to punch core sheets of a predetermined shape from a steel strip to which an adhesive is applied, and then bond the resulting multiple core sheets together 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 an outline punch are forced into an outline punching die. The thin core sheets forced into the outline punching die are stacked on top of the thin core sheets punched out previously, and are then forced one after the other into a squeeze ring below the outline punching die. The thin core sheets forced into the squeeze ring are pressed against the inner circumferential surface of the squeeze ring while moving, thereby adhering to one another. At this time, the adhesive between each thin core sheet is hardened by the heat of a heater, and a laminated core is formed in which a predetermined number of thin core sheets are fixed together.

[0004] Unlike the method disclosed in Patent Document 1, a method has also been used in which a heater is not placed around the squeeze ring, but the adhesive is cured using a heating furnace. In this method, multiple core sheets (thin iron core plates) are temporarily bonded together by pressing them together in the squeeze ring. The temporarily bonded multiple core sheets (laminate) are then transported to a heating furnace and heated to cure the adhesive between the core sheets. This results in a laminated core. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-297758 Summary of the Invention [Problem to be solved by the invention]

[0006] Conventionally, when curing the adhesive in a squeeze ring or a heating furnace as described above, for example, a far-infrared heater has been used, but when using a far-infrared heater, it is difficult to heat the adhesive in a short time.

[0007] Therefore, the inventors attempted to use a near-infrared heater to cure the adhesive when bonding multiple core sheets together, and as a result, it was possible to heat the adhesive in a shorter time than when using a far-infrared heater, and it was possible to efficiently manufacture laminated cores.

[0008] However, it has been found that when a near-infrared heater is used to harden the adhesive between core sheets, the flatness of the laminated core (the difference between the maximum and minimum values ​​in the thickness distribution of the laminated core) may deteriorate. The inventors of the present invention have conducted research into the cause of this and found that when a near-infrared heater is used, temperature differences tend to occur depending on the position on the periphery of the core sheet during heating. In other words, temperature deviations tend to occur in the circumferential direction on the periphery of the core sheet. It is believed that this temperature deviation causes the flatness of the laminated core to deteriorate.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method and apparatus for manufacturing a laminated core that can suppress deterioration of flatness. [Means for solving the problem]

[0010] (1) A method for manufacturing a laminated core according to one embodiment of the present invention is a method for manufacturing a laminated core by heating a plurality of core sheets laminated together via adhesive layers, When the plurality of core sheets are heated by near-infrared rays radiated from a heating element, When the near-infrared rays are directly irradiated onto the plurality of core sheets, the plurality of core sheets are used as the target, and when the near-infrared rays are irradiated onto a squeeze ring that holds the plurality of core sheets, the squeeze ring is used as the target, When the object has a circular or octagonal or more polygonal outer circumferential surface as viewed from the stacking direction of the plurality of core sheets, four heat source units are provided so as to be located on both sides of the object in a first direction and on both sides of the object in a second direction perpendicular to the first direction, When viewed from the stacking direction, a pair of heat source parts of the four heat source parts are provided to face each other in the first direction and extend in the second direction, and another pair of heat source parts of the four heat source parts are provided to face each other in the second direction and extend in the first direction, Each of the heat source units is provided with one or more of the heat generating elements, When viewed from the stacking direction, the heat source parts are arranged so as to satisfy the following formula (i). 0.38<0.88((WD) / W) 0.22 ×((LD) / L) 0.20 ≦1.0 (i) However, in the above formula, W indicates the distance between the heat source part and the heat source part opposite it, D indicates the diameter of the object if the outer peripheral surface is circular when viewed from the stacking direction, or indicates the diameter of a circle circumscribing the outer peripheral surface of the object if the outer peripheral surface is polygonal when viewed from the stacking direction, and L indicates the total length of the one or more heating elements in the longitudinal direction of the heat source part.

[0011] (2) A method for manufacturing a laminated core according to another embodiment of the present invention is a method for manufacturing a laminated core by heating a plurality of core sheets laminated via adhesive layers while holding them with a squeeze ring having a rectangular shape as viewed from the lamination direction of the plurality of core sheets, When the plurality of core sheets are heated by near-infrared rays radiated from a heating element, When viewed from the stacking direction, a direction perpendicular to one side of the squeeze ring is defined as a first direction, and a direction perpendicular to the first direction is defined as a second direction. Four heat source units are provided so as to be located on both sides of the squeeze ring in the first direction and on both sides of the squeeze ring in the second direction, When viewed from the stacking direction, a pair of heat source parts of the four heat source parts are provided to face each other in the first direction and extend in the second direction, and another pair of heat source parts of the four heat source parts are provided to face each other in the second direction and extend in the first direction, Each of the heat source units is provided with one or more of the heat generating elements, When viewed from the stacking direction, the heat source parts are arranged so as to satisfy the following formula (ii). 0.63<1.03((WM) / W) -0.16 ×((LM) / L) 0.30 ≦1.0 (ii) In the above formula, W represents the distance between the heat source and the heat source facing it, M represents the length of the squeeze ring in a direction perpendicular to the longitudinal direction of the heat source, and L represents the total length of the one or more heating elements in the longitudinal direction of the heat source.

[0012] (3) A method for manufacturing a laminated core according to another embodiment of the present invention is a method for manufacturing a laminated core by heating a plurality of core sheets laminated via adhesive layers while holding them with a rectangular squeeze ring having a pair of short sides and a pair of long sides as viewed from the lamination direction of the plurality of core sheets, When the plurality of core sheets are heated by near-infrared rays radiated from a heating element, two heat source portions are provided on the outside of the pair of short sides of the squeeze ring so as to extend along the pair of short sides, respectively, when viewed from the stacking direction; Each of the heat source units is provided with one or more of the heat generating elements, When viewed from the stacking direction, the two heat source parts are arranged so as to satisfy the following formula (iii). 0.24<1.27((WM) / W)-13.7 ×((LN) / L) 14.7 ≦1.0 (iii) However, in the above formula, W represents the distance between the two heat source parts, M represents the length of the long side, L represents the total length of the one or more heating elements in the longitudinal direction of the heat source part, and N represents the length of the short side.

[0013] (4) In the above manufacturing method, the heating element may be provided in each of the heat source parts so as to extend in the length direction of the heat source part.

[0014] (5) In the above manufacturing method, a plurality of the heat generating elements may be provided in each of the heat source portions so as to extend in the stacking direction and to be aligned along the length direction of the heat source portion.

[0015] (6) In the above manufacturing method, the near-infrared rays emitted from the heating element may be irradiated as parallel or divergent light.

[0016] (7) Another embodiment of the laminated core manufacturing apparatus of the present invention is an apparatus for manufacturing a laminated core by heating a plurality of core sheets that are laminated via adhesive layers and have a circular or polygonal outer surface with an octagon or greater shape when viewed from the lamination direction, four heat source units provided so as to be located on both sides of the plurality of core sheets in a first direction and on both sides of the plurality of core sheets in a second direction perpendicular to the first direction, when viewed from the stacking direction of the plurality of core sheets; When viewed from the stacking direction, a pair of heat source parts of the four heat source parts are provided to face each other in the first direction and extend in the second direction, and another pair of heat source parts of the four heat source parts are provided to face each other in the second direction and extend in the first direction, Each of the heat source units is provided with one or more heating elements that radiate near-infrared rays, A laminated core manufacturing device, wherein, when viewed from the stacking direction, each of the heat source parts is arranged so as to satisfy the following formula (i): 0.38<0.88((WD) / W)0.22 ×((LD) / L) 0.20 ≦1.0 (i) However, in the above formula, W indicates the distance between the heat source part and the heat source part opposite it, D indicates the diameter of the multiple core sheets when the outer surface is circular when viewed from the stacking direction, or the diameter of the circle circumscribing the outer surface when the outer surface is polygonal when viewed from the stacking direction, and L indicates the total length of the one or more heating elements in the longitudinal direction of the heat source part.

[0017] (8) A laminated core manufacturing apparatus according to another embodiment of the present invention is an apparatus for manufacturing a laminated core by heating a plurality of core sheets laminated together via an adhesive layer, a squeeze ring that holds the core sheets while stacking the core sheets in a predetermined stacking direction, and has an outer peripheral surface that is circular or polygonal having octagonal or greater sides when viewed from the stacking direction; four heat source units provided so as to be located on both sides of the squeeze ring in a first direction and on both sides of the squeeze ring in a second direction perpendicular to the first direction, as viewed from the stacking direction; When viewed from the stacking direction, a pair of heat source parts of the four heat source parts are provided to face each other in the first direction and extend in the second direction, and another pair of heat source parts of the four heat source parts are provided to face each other in the second direction and extend in the first direction, Each of the heat source units is provided with one or more heating elements that radiate near-infrared rays, When viewed from the stacking direction, the heat source parts are arranged so as to satisfy the following formula (i). 0.38<0.88((WD) / W) 0.22 ×((LD) / L) 0.20 ≦1.0 (i) In the above formula, W represents the distance between the heat source part and the heat source part facing it, D represents the diameter of the squeeze ring if the outer peripheral surface is circular when viewed from the stacking direction, or the diameter of the circle circumscribing the outer peripheral surface if the outer peripheral surface is polygonal when viewed from the stacking direction, and L represents the total length of the one or more heating elements in the longitudinal direction of the heat source part.

[0018] (9) A laminated core manufacturing apparatus according to another embodiment of the present invention is an apparatus for manufacturing a laminated core by heating a plurality of core sheets laminated together via an adhesive layer, the apparatus comprising: a squeeze ring that holds the core sheets while stacking the core sheets in a predetermined stacking direction and has a rectangular shape when viewed from the stacking direction; When viewed from the stacking direction, a direction perpendicular to one side of the squeeze ring is defined as a first direction, and a direction perpendicular to the first direction is defined as a second direction, and four heat source units are provided so as to be located on both sides of the squeeze ring in the first direction and on both sides of the squeeze ring in the second direction, When viewed from the stacking direction, a pair of heat source parts of the four heat source parts are provided to face each other in the first direction and extend in the second direction, and another pair of heat source parts of the four heat source parts are provided to face each other in the second direction and extend in the first direction, Each of the heat source units is provided with one or more heating elements that radiate near-infrared rays, When viewed from the stacking direction, the heat source parts are arranged so as to satisfy the following formula (ii). 0.63<1.03((WM) / W) -0.16 ×((LM) / L) 0.30 ≦1.0 (ii) In the above formula, W represents the distance between the heat source and the heat source facing it, M represents the length of the squeeze ring in a direction perpendicular to the longitudinal direction of the heat source, and L represents the total length of the one or more heating elements in the longitudinal direction of the heat source.

[0019] (10) A laminated core manufacturing apparatus according to another embodiment of the present invention is an apparatus for manufacturing a laminated core by heating a plurality of core sheets laminated together via an adhesive layer, the apparatus comprising: a rectangular squeeze ring that holds the core sheets while stacking the core sheets in a predetermined stacking direction and has a pair of short sides and a pair of long sides when viewed from the stacking direction; two heat source units provided on the outside of the pair of short sides of the squeeze ring so as to extend along the pair of short sides, respectively, when viewed from the stacking direction; Each of the heat source units is provided with one or more heating elements that radiate near-infrared rays, The laminated core manufacturing device, wherein the two heat source parts are arranged so as to satisfy the following formula (iii) when viewed from the stacking direction: 0.24<1.27((WM) / W) -13.7 ×((LN) / L) 14.7 ≦1.0 (iii) However, in the above formula, W represents the distance between the two heat source parts, M represents the length of the long side, L represents the total length of the one or more heating elements in the longitudinal direction of the heat source part, and N represents the length of the short side.

[0020] (11) The heating element may be provided in each of the heat source parts so as to extend in the length direction of the heat source part.

[0021] (12) In the manufacturing apparatus described above, a plurality of the heating elements may be provided in each of the heat source sections so as to extend in the stacking direction and to be aligned along the length of the heat source section.

[0022] (13) In the above manufacturing apparatus, the near-infrared rays emitted from the heating element may be irradiated as parallel or divergent light. [Effects of the Invention]

[0023] According to the present invention, deterioration of the flatness of the laminated core can be suppressed. [Brief explanation of the drawings]

[0024] [Figure 1A] FIG. 1A is a plan view of the laminate. [Figure 1B] FIG. 1B is a side view of the laminate. [Figure 2A] FIG. 2A is a plan view showing the positional relationship between the laminate and a plurality of heating elements. [Figure 2B] FIG. 2B is a side view showing the positional relationship between the laminate and a plurality of heating elements. [Figure 3] FIG. 3 is a diagram for explaining the contents of the study by the inventors. [Figure 4] FIG. 4 is a diagram showing the relationship between the position in the circumferential direction of the outer peripheral surface of the laminate and the average view factor. [Figure 5] FIG. 5 is a plan view showing the positional relationship between a circular squeeze ring and a plurality of heating elements. [Figure 6] FIG. 6 is a diagram showing an example of a rectangular squeeze ring used when manufacturing a split core. [Figure 7] FIG. 7 is a plan view showing the positional relationship between a rectangular squeeze ring and a plurality of heating elements. [Figure 8] FIG. 8 is a plan view showing the positional relationship between a rectangular squeeze ring and a plurality of heating elements. [Figure 9] FIG. 9 is a schematic cross-sectional view showing a manufacturing apparatus used in the manufacturing method of the laminated core according to the first embodiment of the present invention. [Figure 10] FIG. 10 is an enlarged cross-sectional view showing the vicinity of the surface of the steel strip. [Figure 11] FIG. 11 is a schematic diagram showing a heating furnace. [Figure 12A] FIG. 12A is a plan view showing the stack and a plurality of heat source units. [Figure 12B] FIG. 12B is a side view showing the stack and multiple heat sources. [Figure 12C] FIG. 12C is a diagram for explaining the centers of the plurality of heat sources. [Figure 13] FIG. 13 is a plan view showing the stack and a plurality of heat sources. [Figure 14A] FIG. 14A is a plan view showing a stack and a plurality of heat source units. [Figure 14B] FIG. 14B is a side view showing the stack and multiple heat sources. [Figure 14C] FIG. 14C is a diagram for explaining the centers of the plurality of heat sources. [Figure 15] FIG. 15 is a diagram showing a manufacturing apparatus used in a manufacturing method of a laminated core according to the second embodiment of the present invention. [Figure 16A] FIG. 16A is a plan view showing a squeeze ring and multiple heat sources. [Figure 16B] FIG. 16B is a side view showing a squeeze ring and multiple heat sources. [Figure 17] FIG. 17 is a plan view showing the positional relationship between a squeeze ring having a polygonal outer peripheral surface and a plurality of heat sources. [Figure 18A] FIG. 18A is a plan view showing a squeeze ring and multiple heat sources. [Figure 18B] FIG. 18B is a side view showing a squeeze ring and multiple heat sources. [Figure 19] FIG. 19 is a plan view showing a squeeze ring and a plurality of heat sources. [Figure 20A] FIG. 20A is a plan view showing a squeeze ring and multiple heat sources. [Figure 20B] FIG. 20B is a side view showing a squeeze ring and multiple heat sources. [Figure 21] FIG. 21 is a plan view showing a squeeze ring and a plurality of heat sources. [Figure 22] FIG. 22 is a diagram for explaining the measurement positions for the flatness of the laminate. DETAILED DESCRIPTION OF THE INVENTION

[0025] (Study on how to prevent deterioration of the flatness of laminated core) Near-infrared heaters have a higher radiation energy density than resistance heaters. Therefore, when using a near-infrared heater to heat a laminate (multiple core sheets), unless the near-infrared heater is positioned appropriately according to its size, temperature deviations tend to occur in the circumferential direction of the core sheets, as described above. As a result, the flatness of the manufactured laminated core deteriorates. Therefore, the present inventors conducted detailed studies on the appropriate positioning of the near-infrared heater. The following describes the results of the study by the present inventors in detail.

[0026] (Consideration 1) 1A and 1B are schematic diagrams showing an example of a laminate. Specifically, FIG. 1A is a plan view of the laminate, and FIG. 1B is a side view of the laminate. The laminate 50 shown in FIGS. 1A and 1B has a configuration in which multiple annular core sheets 50a are stacked. Note that FIG. 1A shows a first direction X and a second direction Y that are perpendicular to each other. Furthermore, FIG. 1B shows, in addition to the first direction X, a third direction Z that is perpendicular to the first direction X and the second direction Y. The third direction Z coincides with the stacking direction of the laminate 50 (multiple core sheets 50a). The first direction X, the second direction Y, and the third direction Z are also shown appropriately in other drawings.

[0027] Although not shown in the drawings, an adhesive layer is provided on the surface of the core sheet 50a. Also, although not described, the laminate 50 is manufactured by pressing a plurality of core sheets 50a together using a known squeeze ring.

[0028] The present inventors first investigated the case where a heat source is arranged around the laminate 50 to heat the laminate 50. Specifically, as shown in Figures 2A and 2B, four heating elements 61 to 64 that radiate near-infrared rays are arranged around the laminate 50, and the inventors investigated the circumferential temperature deviation that occurs on the outer peripheral surface 50b of the laminate 50. Note that Figure 2A is a plan view showing the laminate 50 and the heating elements 61 to 64, and Figure 2B is a side view showing the laminate 50 and the heating elements 61 to 64. The heating elements 61 to 64 are each a filament of a near-infrared heater (for example, a nichrome wire).

[0029] 2A and 2B are schematic diagrams showing the positional relationship between the laminate 50 and the heating elements 61 to 64, and the heating elements 61 to 64 shown in Fig. 2 do not accurately represent the shapes of the actual heating elements. Furthermore, although not shown to avoid cluttering the drawings, the heating elements 61 to 64 are each supported by a case having a reflective surface that can reflect near-infrared rays emitted from the heating elements 61 to 64 toward the laminate 50.

[0030] As shown in FIGS. 2A and 2B, the heating elements 61 and 63 are disposed so as to extend in the first direction X with the laminate 50 sandwiched therebetween, and the heating elements 62 and 64 are disposed so as to extend in the second direction Y with the laminate 50 sandwiched therebetween. The laminate 50 is disposed so as to be located at the center of the heating elements 61 to 64. The lengths of the heating elements 61 to 64 are equal to each other. The distance between the heating elements 61 and 63 in the second direction Y and the distance between the heating elements 62 and 64 in the first direction X are equal to each other. In other words, FIGS. 2A and 2B show that the heating elements 61, 62, 63, and 64 are each rod-shaped, and that the heating elements are disposed on the sides of a square surrounding the laminate 50 when viewed from the third direction Z (the stacking direction of the laminate 50). When viewed from the third direction Z, the long sides of the rod-shaped heating elements 61 and 63 coincide with the first direction X, and the long sides of the rod-shaped heating elements 62 and 64 coincide with the second direction Y.

[0031] In the following description, referring to FIG. 2A, four regions of the laminate 50 defined by an imaginary line v1 passing through the center of the laminate 50 and extending in the first direction X, and an imaginary line v2 passing through the center of the laminate 50 and extending in the second direction Y, are referred to as regions 51 to 54. In this specification, "planar view" refers to a view from the stacking direction of the laminate (multiple core sheets). When the heating elements 61 to 64 are arranged as shown in FIGS. 2A and 2B, each of the regions 51 to 54 is primarily heated by the two heating elements arranged nearby. For example, the region 51 is primarily heated by the heating elements 61 and 62.

[0032] Radiation heat transfer is dominant in the heat transfer from the heating elements 61 to 64 to the laminate 50. Therefore, the present inventors investigated the influence that variations in radiation heat transfer from the heating elements 61 to 64 to the laminate 50 have on temperature changes at the outer peripheral surface 50b of the laminate 50. Specifically, the present inventors evaluated variations in radiation heat transfer to the laminate 50 using the view factor from the heating elements 61 to 64 to the outer peripheral surface 50b of the laminate 50.

[0033] 2A and 2B, the outer peripheral surfaces 51a to 54a of the regions 51 to 54 are heated under the same conditions. Therefore, by evaluating the variation in radiant heat transfer to any one of the outer peripheral surfaces 51a to 54a, the variation in radiant heat transfer to the entire outer peripheral surface 50b can be understood. Therefore, the following describes the variation in radiant heat transfer to the outer peripheral surface 51a of the region 51.

[0034] As described above, the region 51 is mainly heated by the heating elements 61 and 62. First, the inventors calculated the geometric factor from the heating element 61 to an arbitrary point P on the outer peripheral surface 51a of the region 51 and the geometric factor from the heating element 62 to the arbitrary point P.

[0035] The inventors also defined the average geometric factor F from the heating elements 61, 62 to an arbitrary point P on the outer peripheral surface 51a by the following formula (1) using the calculated geometric factors. F=(A 61 F 1P +A 62 F 2P ) / A 51 ···(1) In the above formula (1), A 61 indicates the area of ​​the radiation surface of the heating element 61 that radiates near-infrared rays reaching point P, and A 62 indicates the area of ​​the radiation surface of the heating element 62 that radiates near-infrared rays reaching point P, and A 51 indicates the area of ​​the outer peripheral surface 51a of the region 51. 1P is the geometric factor from the part of the radiation surface of the heating element 61 that radiates near-infrared rays reaching point P to point P, and F 2Pis the geometric factor from the part of the radiation surface of the heating element 62 that radiates near-infrared rays that reach point P to point P.

[0036] The portion of the radiation surface of the heating elements 61, 62 that radiates near-infrared rays reaching point P can be identified by the intersection of a tangent to the outer peripheral surface 51a at point P and the radiation surface of the heating elements 61, 62. For example, if point P for calculating the average geometric factor F using the above formula (1) is point P1 shown in FIG. 3, then the portion of the radiation surface of the heating element 61 that radiates near-infrared rays reaching point P is a range of length L1 from one end of the heating element 61 (the end on the heating element 62 side in the first direction X). Also, the portion of the radiation surface of the heating element 62 that radiates near-infrared rays reaching point P is a range of length L2 from one end of the heating element 62 (the end on the heating element 61 side in the second direction Y).

[0037] Furthermore, for example, when the point P for calculating the average view factor F by the above formula (1) is the point P2 shown in FIG. 3, the range of the radiation surface of the heating element 61 from one end of the heating element 61 to the length L3 is the portion that radiates the near-infrared rays that reach the point P. Also, the entire radiation surface of the heating element 62 is the portion that radiates the near-infrared rays that reach the point P. In this way, the area A in the above formula (1) 61 ,A 62 increases or decreases depending on the position of point P.

[0038] The inventors calculated the geometric factor F for each position in the circumferential direction of the outer circumferential surface 51a. 1P ,F 2P and calculated the average geometric factor F using the above formula (1). Fig. 4 shows an example of the relationship between the position in the circumferential direction of the outer peripheral surface 51a and the calculated average geometric factor F. In Fig. 4, the horizontal axis indicates the position in the circumferential direction of the outer peripheral surface 51a, and the vertical axis indicates the average geometric factor F calculated using the above formula (1). Note that the horizontal axis in Fig. 4 represents the position in the circumferential direction of the outer peripheral surface 51a as an angle, with the position where the virtual line v1 (see Fig. 2A) and the outer peripheral surface 51a intersect being set to 0° and the position where the virtual line v2 and the outer peripheral surface 51a intersect being set to 90°.

[0039] As shown in FIG. 4, the average geometric factor F was smallest at the center (45° position) of the outer peripheral surface 51a in the circumferential direction, and was largest near both ends (0° and 90° positions) of the outer peripheral surface 51a in the circumferential direction.

[0040] Next, the inventors investigated the relationship between the average geometric factor F and the temperature change of the outer peripheral surface 51a. Specifically, the temperatures of the heating elements 61 to 64 were set to 100°C (for 3 minutes) and then to 190°C (for 3 minutes), and the temperature changes at the 0°, 45°, and 90° positions on the outer peripheral surface 51a were investigated. As a result, the temperature rise rate at the 45° position was slower than at the 0° and 90° positions. The inventors further conducted a similar investigation by changing the diameter D1 (see FIG. 2A) of the laminate 50, the length L (see FIG. 2A) of the heating elements 61 to 64, and the distance W (see FIG. 2A) between the opposing heating elements 61 (62) and 63 (64). As a result, similar to the above investigation results, the temperature rise rate at the 45° position, where the average geometric factor F is low, was slower than at the 0° and 90° positions, where the average geometric factor F is high. The distance W between the heat generating element 61 and the heat generating element 63 in the second direction Y and the distance W between the heat generating element 62 and the heat generating element 64 in the first direction X were set equal to each other.

[0041] Based on the above findings, the present inventors have considered that if the variation in the average geometric factor F in the circumferential direction of the outer peripheral surface 50b of the laminate 50 can be reduced, it will be possible to suppress the occurrence of temperature deviation in the circumferential direction on the outer peripheral surface 50b when the laminate 50 is heated. Therefore, the present inventors have considered that the minimum value F of the average geometric factor F in the circumferential direction of the laminate 50 can be reduced. min and the maximum value F max We conducted studies to reduce the ratio of

[0042] First, the inventors investigated the minimum value F of the average geometric factor F under a plurality of conditions in which the diameter D1, the length L, and the distance W were changed in the heating elements 61 to 64 and the laminate 50 shown in FIGS. 2A and 2B. min and the maximum value F max The diameter D1, length L, distance W, and minimum value F under each condition were calculated. min and the maximum value F max Based on the minimum Fmin and the maximum value F max The ratio Y (= F min / F max ) was calculated using the following formula (2). Y=0.88((W-D1) / W) 0.22 ×((L-D1) / L) 0.20 ···(2)

[0043] The inventors also measured the flatness of the laminate 50 under multiple conditions in which the diameter D1, length L, and distance W were changed, by heating the laminate 50 to harden the adhesive layer between the core sheets 50a, and then cooling it to room temperature. min and the maximum value F max The relationship between the ratio Y and the flatness of the laminate 50 was investigated. As a result, it was found that the deterioration of the flatness of the laminate 50 can be suppressed when the condition of the following formula (3) is satisfied. 0.38 <Y≦1.0 ···(3)

[0044] The following formula (4) can be derived from the above formulas (2) and (3): That is, by arranging the heating elements 61 to 64 so as to satisfy the condition of the following formula (4), deterioration of the flatness of the laminate 50 can be suppressed. 0.38<0.88((W-D1) / W) 0.22 ×((L-D1) / L) 0.20 ≦1.0 (4)

[0045] (Consideration 2) Next, the inventors investigated the case where a heat source is arranged around a squeeze ring to heat laminate 50. Specifically, as shown in Fig. 5, the inventors investigated conditions for suppressing deterioration of the flatness of laminate 50 when laminate 50 is held inside cylindrical squeeze ring 55 and four heating elements 61 to 64 are arranged around squeeze ring 55. Note that in the example shown in Fig. 5, as in the above-described example, the distance W between heating elements 61 and 63 in the second direction Y is equal to the distance W between heating elements 62 and 64 in the first direction X.

[0046] When the heating elements 61-64 are arranged around the cylindrical squeeze ring 55, it is believed that the occurrence of circumferential temperature deviation on the outer peripheral surface 55a of the squeeze ring 55 can be suppressed by suppressing variations in radiant heat transfer from the heating elements 61-64 to the outer peripheral surface 55a of the squeeze ring 55. It is also believed that the occurrence of circumferential temperature deviation on the outer peripheral surface 50b of the stack 50 can be suppressed by suppressing the occurrence of temperature deviation on the outer peripheral surface 55a of the squeeze ring 55. As a result, it is believed that deterioration in the flatness of the stack 50 can be suppressed.

[0047] In a cross section perpendicular to the axial direction of the squeeze ring 55, the outer peripheral surface 55a has a circular shape, similar to the outer peripheral surface 50b in a cross section perpendicular to the stacking direction of the stack 50. Therefore, the geometric factor from the heating elements 61 to 64 to the outer peripheral surface 55a of the squeeze ring 55 can be evaluated in the same way as the geometric factor from the heating elements 61 to 64 to the outer peripheral surface 50b of the stack 50.

[0048] Therefore, the minimum value F of the average geometric factor from the heating elements 61 to 64 to the outer peripheral surface 55a of the squeeze ring 55 is min and the maximum value F max The ratio Y (= F min / F max ) can be expressed in the same way as the above-mentioned formula (2). Specifically, it can be expressed by the following formula (5) using the diameter D2 of the squeeze ring 55, the length L of the heating elements 61 to 64, and the distance W between the opposing heating elements. Y=0.88((W-D2) / W) 0.22 ×((L-D2) / L) 0.20 ···(5)

[0049] Furthermore, as described above, it is believed that deterioration of the flatness of the laminate 50 can be prevented by suppressing the occurrence of temperature deviation on the outer peripheral surface 55a of the squeeze ring 55. Therefore, it is believed that deterioration of the flatness of the laminate 50 can be suppressed by arranging the heating elements 61 to 64 so as to satisfy the condition of the following formula (6), which is defined similarly to the above formula (4). 0.38<0.88((W-D2) / W) 0.22×((L-D2) / L) 0.20 ≦1.0 (6)

[0050] (Study 3) When manufacturing a laminated core, a squeeze ring having a rectangular outer edge in a plan view may be used depending on the shape of the laminated core to be manufactured, rather than a cylindrical squeeze ring as shown in FIG. 5.

[0051] Fig. 6 is a diagram showing an example of a squeeze ring used when manufacturing split cores. Fig. 6 is a plan view showing the laminate (split core) and the squeeze ring. The squeeze ring 70 shown in Fig. 6 has a block portion 72 having a hollow portion 72a in the center, holding members 74a to 74d provided on the block portion 72, and biasing devices 76a to 76c provided on the block portion 72. The laminate 78 is held by the squeeze ring 70 within the hollow portion 72a.

[0052] Although detailed description will be omitted, the laminate 78 has a configuration in which a plurality of core sheets 78a punched into a predetermined shape are stacked. An adhesive layer is provided on the surface of the core sheets 78a, and the plurality of core sheets 78a are pressure-bonded to one another by the squeeze ring 70. Hereinafter, the stacking direction of the plurality of core sheets 78a will also be referred to as the stacking direction of the laminate 78.

[0053] The block portion 72 has a rectangular shape when viewed from the stacking direction of the laminate 78. Specifically, the outer peripheral surface 73 of the block portion 72 has four side surfaces 73a to 73d. In this example, the outer peripheral surface 73 of the block portion 72 forms a rectangular shape having a pair of long sides 731a, 731c and a pair of short sides 731b, 731d when viewed from the stacking direction of the laminate 78.

[0054] The holding members 74a to 74d are provided to hold the stack 78 inside the hollow portion 72a. Specifically, the holding members 74b and 74c are provided to sandwich the stack 78 from both sides in the first direction X, and the holding members 74a and 74d are provided to sandwich the stack 78 from both sides in the second direction Y. The biasing devices 76a to 76c include elastic members such as springs, and bias the holding members 74a to 74c toward the stack 78.

[0055] To efficiently heat the squeeze ring 70, it is possible to arrange the heating elements 61-64 so that they are parallel to the side surfaces 73a-73d, as shown in FIG. 7 . Arranging the heating elements 61-64 as shown in FIG. 7 suppresses variations in radiant heat transfer from the heating elements 61-64 to the outer peripheral surface 73 of the squeeze ring 70, thereby suppressing circumferential temperature deviations on the outer peripheral surface 73 of the squeeze ring 70. Furthermore, suppressing temperature deviations on the outer peripheral surface 73 of the squeeze ring 70 suppresses circumferential temperature deviations on the outer peripheral surface of the laminate 78. As a result, it is possible to prevent deterioration of the flatness of the laminate 78. Therefore, the inventors of the present invention investigated circumferential temperature deviations on the outer peripheral surface 73 of the squeeze ring 70 when four heating elements 61-64 are arranged around the squeeze ring 70 as shown in FIG. 7 .

[0056] 7, side surfaces 73a and 73c are heated under the same conditions. Side surfaces 73b and 73d are heated under the same conditions. Therefore, the following describes the variation in radiant heat transfer to side surfaces 73a and 73b.

[0057] First, radiative heat transfer to the side surface 73a will be described. The side surface 73a is mainly heated by the heating element 61. The side surface 73a is also heated by portions of the heating elements 62 and 64 that protrude closer to the heating element 61 than the side surface 73a in the second direction Y. Therefore, the inventors calculated the geometric factor from the heating element 61 to an arbitrary point P on the side surface 73a, the geometric factor from the heating element 62 to the arbitrary point P, and the geometric factor from the heating element 64 to the arbitrary point P.

[0058] Furthermore, the inventors calculated the average geometric factor F from the heating elements 61, 62, and 64 to an arbitrary point P on the side surface 73a by the following formula (7) using the calculated geometric factor. 73a The following was stipulated. F 73a =(A 61 F 1P +A 62a F 2Pa +A 64a F 4Pa ) / A 73a ···(7) In the above formula (7), A 61 represents the area of ​​the radiation surface of the heating element 61, and A 62a indicates the area of ​​the portion of the radiation surface of the heating element 62 that protrudes toward the heating element 61 beyond the side surface 73a, and A 64a indicates the area of ​​the radiation surface of the heating element 64 that protrudes toward the heating element 61 beyond the side surface 73a, and A 73a indicates the area of ​​the side surface 73a. 1P is the view factor from the radiation surface of the heating element 61 to point P, and F 2Pa is the geometric factor from the portion of the radiation surface of the heating element 62 that protrudes toward the heating element 61 beyond the side surface 73a to the point P, and F 4Pa is the geometric factor from the portion of the radiation surface of the heating element 64 that protrudes toward the heating element 61 side beyond the side surface 73a to the point P.

[0059] The inventors calculated the view factor F for each position in the first direction X of the side surface 73a. 1P ,F 2Pa ,F 4Pa Calculate the average view factor F using the above formula (7). 73aFurthermore, the inventors calculated the dimensions of the squeeze ring 70 (length of the long side M x , length of short side M y ), the length L of the heating elements 61 to 64, and the distance W between the opposing heating elements x ,W y Under multiple conditions with different values, the average view factor F 73a The minimum value of F 73amin and the maximum value F 73amax The lengths L and M under each condition were calculated. x ,M y , distance W x ,W y , minimum value F 73amin and the maximum value F 73amax Based on the minimum F 73amin and the maximum value F 73amax Ratio to Y 73a (=F 73amin / F 73amax ) was calculated using the following formula (8). Y 73a =1.03((W y -M y ) / W y ) -0.16 ×((LM y ) / L) 0.30 ···(8)

[0060] Radiant heat transfer to side surface 73b can be considered similar to radiant heat transfer to side surface 73a. Specifically, side surface 73b is mainly heated by heating element 62. Side surface 73b is also heated by portions of heating elements 61 and 63 that protrude closer to heating element 62 than side surface 73b in the first direction X.

[0061] Therefore, the average geometric factor F from the heating elements 61 to 63 to an arbitrary point P (not shown) on the side surface 73b is 73b can be expressed by the following equation (9) by rearranging it in the same way as the above equation (7). F 73b =(A 61b F 1Pb +A 62 F 2P +A63b F 3Pb ) / A 73b ···(9) In the above formula (9), A 61b indicates the area of ​​the portion of the radiation surface of the heating element 61 that protrudes toward the heating element 62 beyond the side surface 73b, and A 62 represents the area of ​​the radiation surface of the heating element 62, and A 63b indicates the area of ​​the portion of the radiation surface of the heating element 63 that protrudes toward the heating element 62 beyond the side surface 73b, and A 73b indicates the area of ​​the side surface 73b. 1Pb is the geometric factor from the part of the radiation surface of the heating element 61 that protrudes further toward the heating element 62 than the side surface 73b to a point P on the side surface 73b, and F 2P is the view factor from the radiation surface of the heating element 62 to point P on the side surface 73b, and F 3Pb is a geometric factor from a portion of the radiation surface of the heating element 63 that protrudes toward the heating element 62 side beyond the side surface 73b to a point P on the side surface 73b.

[0062] Also, the average view factor F 73b The minimum value of F 73bmin and the maximum value F 73bmax Ratio to Y 73b (=F 73bmin / F 73bmax ) can be expressed by the following equation (10) by rearranging it in the same way as the above equation (8). Y 73b =1.03((W x -M x ) / W x ) -0.16 ×((LM x ) / L) 0.30 ···(10)

[0063] Furthermore, the inventors have determined that the lengths L and M x ,M y and distance W x ,W y Under a plurality of conditions in which the ratio Y was changed, the laminate 78 was heated to harden the adhesive layer between the core sheets 78a, and after cooling to room temperature, the flatness of the laminate 78 was measured. 73a , ratio Y 73band the flatness of the laminate 78. As a result, it was found that the deterioration of the flatness of the laminate 78 can be suppressed when the conditions of the following expressions (11) and (12) are satisfied. 0.63 <Y 73a ≦1.0 (11) 0.63 <Y 73b ≦1.0 (12)

[0064] (Consideration 4) Next, the inventors have investigated the case where the squeeze ring 70 is heated by two heating elements 62, 64, as shown in Fig. 8. In the example shown in Fig. 8, the heating element 62 is provided so as to face the side surface 73b in the first direction X, and the heating element 64 is provided so as to face the side surface 73d. Note that the lengths M, N and distance W in Fig. 8 are the same as the length M in Fig. 7. x ,M y and distance W x correspond to each.

[0065] 8, the side surfaces 73b and 73d are heated by the front-facing heating elements 62 and 64. In this case, temperature deviation in the second direction Y is unlikely to occur on the side surfaces 73b and 73d.

[0066] On the other hand, no heating element is provided in front of the side surfaces 73a and 73c, and the side surfaces 73a and 73c are heated from the sides by the heating elements 62 and 64. For this reason, temperature deviations are more likely to occur on the side surfaces 73a and 73c than on the side surfaces 73b and 73d. For example, the temperature of the central portions of the side surfaces 73a and 73c in the first direction X may decrease.

[0067] For this reason, when the heating elements 62, 64 are arranged as shown in Fig. 8, it is important to suppress the temperature deviation in the first direction X on the side surfaces 73a, 73c by suppressing the variation in the radiant heat transfer from the heating elements 62, 64 to the side surfaces 73a, 73c. ​​Therefore, the inventors have studied the temperature deviation in the first direction X that occurs on the side surfaces 73a, 73c when two heating elements 62, 64 are arranged as shown in Fig. 8.

[0068] 8, the side surfaces 73a and 73c are heated under the same conditions. Therefore, the following will describe variations in the radiant heat transfer to the side surface 73a.

[0069] 8, the side surface 73a is heated by the portions of the heating element 62 and the heating element 64 that protrude outward from the side surface 73a in the second direction Y. Therefore, the inventors calculated the geometric factor from the heating element 62 to an arbitrary point P on the side surface 73a and the geometric factor from the heating element 64 to the arbitrary point P.

[0070] Furthermore, the inventors calculated the average geometric factor F from the heating elements 62 and 64 to an arbitrary point P on the side surface 73a by the following equation (13) using the calculated geometric factor. 73A The following was stipulated. F 73A =(A 62a F 2Pa +A 64a F 4Pa ) / A 73a ···(13) In the above formula (13), A 62a indicates the area of ​​the radiation surface of the heating element 62 that protrudes outward from the side surface 73a in the second direction Y, and A 64a indicates the area of ​​the radiation surface of the heating element 64 that protrudes outward from the side surface 73a in the second direction Y, and A 73a indicates the area of ​​the side surface 73a. 2Pa is the geometric factor from the portion of the radiation surface of the heating element 62 that protrudes outward from the side surface 73a in the second direction Y to the point P, and F 4Pa is the geometric factor from the portion of the radiation surface of the heating element 64 that protrudes outward beyond the side surface 73a in the second direction Y to the point P.

[0071] The inventors calculated F 2Pa ,F 4Pa Calculate the average view factor F using the above equation (13). 73AFurthermore, the inventors calculated the average geometric factor F under a plurality of conditions in which the dimensions of the squeeze ring 70 (length of the long side M, length of the short side N), the length L of the heating elements 62, 64, and the distance W between the opposing heating elements 62, 64 were changed for the heating elements 62, 64 and the squeeze ring 70 shown in FIG. 73A The minimum value of F 73Amin and the maximum value F 73Amax The lengths L, M, N, distance W, and minimum value F under each condition were calculated. 73Amin and the maximum value F 73Amax Based on the minimum F 73Amin and the maximum value F 73Amax Ratio to Y 73A (=F 73Amin / F 73Amax ) was calculated using the following formula (14). Y 73A =1.27((WM) / W) -13.7 ×((LN) / L) 14.7 ···(14)

[0072] The inventors also heated the laminate 78 under multiple conditions in which the lengths L, M, N, and distance W were changed to harden the adhesive layer between the core sheets 78a, and after cooling to room temperature, measured the flatness of the laminate 78. Then, for each condition, the ratio Y 73A The relationship between the thickness of the laminate 78 and the flatness of the laminate 78 was investigated. As a result, it was found that the deterioration of the flatness of the laminate 78 can be suppressed when the condition of the following formula (15) is satisfied. 0.24 <Y 73A ≦1.0 (15)

[0073] The laminated core manufacturing method and manufacturing apparatus according to the present invention have been completed based on the above findings. Hereinafter, a laminated core manufacturing method and manufacturing apparatus according to an embodiment of the present invention will be described with reference to the drawings.

[0074] (First embodiment) 9 is a schematic cross-sectional view showing a laminate manufacturing apparatus used in the laminated core manufacturing method according to the first embodiment of the present invention. The manufacturing apparatus 100 according to this embodiment is an apparatus for manufacturing a laminate 2 by punching out a plurality of core sheets 1a from a steel strip 1 conveyed in a predetermined direction and bonding the obtained plurality of core sheets 1a together.

[0075] As will be described later, in this embodiment, a laminated core is manufactured by heating the laminate 2 manufactured by the manufacturing apparatus 100 in a heating furnace. The laminated core manufactured in this embodiment has, for example, a cylindrical shape and is used as a stator core in a rotating electric machine. The laminated core may also be a cylindrical laminated core used as a rotor core in a rotating electric machine. The laminated core may also be a core for a device other than a rotating electric machine.

[0076] Below, the steel strip 1 will be described, followed by a description of the manufacturing apparatus 100. Figure 10 is an enlarged cross-sectional view showing the vicinity of the surface of the steel strip 1.

[0077] (Steel strip) As shown in FIG. 10, the steel strip 1 comprises a base steel sheet 11a and an adhesive layer 11b. In this embodiment, a non-oriented electrical steel sheet is used as the base steel sheet 11a, but a directional electrical steel sheet may also be used as the base steel sheet 11a. The adhesive layer 11b is formed on the surface of the base steel sheet 11a. In this embodiment, the adhesive layer 11b is formed on both sides of the base steel sheet 11a, but the adhesive layer 11b may also be formed on only one surface of the base steel sheet 11a.

[0078] The base steel plate 11a has a chemical composition containing basic elements, optional elements as needed, and the balance being Fe and impurities. In this embodiment, the base steel plate 11a has a chemical composition containing, for example, in mass %, as basic elements: Si: 1.0 to 4.5%, Al: 0.1 to 1.5%, and Mn: 0.2 to 4.0%.

[0079] The adhesive layer 11b is formed so as to cover the entire surface of the base steel plate 11a. For example, a thermosetting resin is used as the adhesive layer 11b. In this embodiment, the adhesive layer 11b has insulating properties in addition to adhesive properties. In this embodiment, the adhesive layer 11b is, for example, an insulating coating containing an epoxy resin and an epoxy resin curing agent.

[0080] The epoxy resin may be, for example, an epoxy resin having two or more epoxy groups per molecule. Examples of such epoxy resins include bisphenol A epoxy resins, bisphenol F epoxy resins, phenol novolac epoxy resins, cresol novolac epoxy resins, alicyclic epoxy resins, glycidyl ester epoxy resins, glycidyl amine epoxy resins, hydantoin epoxy resins, isocyanurate epoxy resins, acrylic acid-modified epoxy resins (epoxy acrylates), phosphorus-containing epoxy resins, and their halides (e.g., brominated epoxy resins) or hydrogenated derivatives. The epoxy resins may be used alone or in combination.

[0081] Examples of epoxy resin curing agents include aromatic polyamines, acid anhydrides, phenolic curing agents, dicyandiamide, boron trifluoride-amine complexes, and organic acid hydrazides. Examples of aromatic polyamines include metaphenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone. Examples of phenolic curing agents include phenol novolac resins, cresol novolac resins, bisphenol novolac resins, triazine-modified phenol novolac resins, and phenol resole resins. Phenol-based curing agents are preferred, and phenol resole resins are more preferred. One type of epoxy resin curing agent may be used alone, or two or more types may be used in combination.

[0082] Although detailed description is omitted, another insulating coating may be formed between the base steel sheet 11a and the adhesive layer 11b. Examples of materials that can be used to form the insulating coating include (1) inorganic compounds, (2) organic resins, and (3) mixtures of inorganic compounds and organic resins. Examples of inorganic compounds include (1) composites of dichromate and boric acid, (2) composites of phosphate and colloidal silica, (3) phosphates, (4) Zr compounds, and (5) Ti compounds. Examples of organic resins include epoxy resins, acrylic resins, acrylic-styrene resins, polyester resins, silicone resins, and fluororesins.

[0083] (Configuration of manufacturing equipment) Next, the manufacturing apparatus 100 will be described. As shown in Figure 9, the manufacturing apparatus 100 according to this embodiment includes a base 10, a punch 12, a punching die 14, and a squeeze ring 16. Although not shown, in the manufacturing apparatus 100, predetermined punching processing (such as forming a slot) is also performed on the steel strip 1 by another punch and die upstream of the punch 12 and punching die 14 in the conveying direction of the steel strip 1.

[0084] The punch 12 is arranged above the base portion 10 and is movable back and forth in the vertical direction. The punching die 14 is arranged below the punch 12. The punching die 14 has a cylindrical shape corresponding to the outer shape of the laminate 2. In this embodiment, the opening edge 14a on the upper end side of the punching die 14 functions as a cutting blade. In this embodiment, the opening edge 14a has a circular shape. In this embodiment, the punch 12 and the punching die 14 repeatedly perform outer shape punching processing on the steel strip 1 being transported in a predetermined direction, and multiple core sheets 1a are punched out of the steel strip 1.

[0085] The squeeze ring 16 is disposed below the punching die 14. In this embodiment, the squeeze ring 16 is fixed to the base 10 using an attachment member (not shown). The squeeze ring 16 is configured to apply pressure from the side (radially outward) to the multiple core sheets 1a punched by the punch 12 and punching die 14. In this embodiment, both the punching die 14 and the squeeze ring 16 have inner peripheral surfaces with circular cross sections, but the inner diameter of the squeeze ring 16 is set smaller than the inner diameter of the punching die 14. Note that the base 10, punch 12, and punching die 14 can be configured using the same components as those of known laminated core manufacturing devices, so detailed description will be omitted. Below, a brief description of the operation of the manufacturing device 100 will be given.

[0086] In this embodiment, 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) while the steel strip 1 is fed in a predetermined direction from a coil (hoop material) not shown.

[0087] The punched core sheets 1a are stacked one after the other in the punching die 14. Note that although the outer periphery of the core sheet 1a punched from the steel strip 1 comes into contact with the inner peripheral surface of the punching die 14, in this embodiment, the punching die 14 does not apply a large amount of pressure to the core sheet 1a. Therefore, the core sheet 1a punched from the steel strip 1 by the punch 12 and the punching die 14 (opening edge 14a) moves downward within the punching die 14 without being held by the inner peripheral surface of the punching die 14.

[0088] As more core sheets 1a are punched out from the steel strip 1, a plurality of core sheets 1a are successively pushed into the squeeze ring 16. In this embodiment, each time a new core sheet 1a is punched out by the punch 12 and the punching die 14, one core sheet 1a is pushed from the punching die 14 into the squeeze ring 16.

[0089] As described above, the squeeze ring 16 is configured so that it can apply pressure to the core sheets 1a from the sides (radially outward). In this embodiment, the multiple core sheets 1a are maintained in a state where they are pressed from the sides within the squeeze ring 16. Therefore, the pressure generated between vertically adjacent core sheets 1a when the punch 12 presses the multiple core sheets 1a downward can be maintained within the squeeze ring 16. As a result, vertically adjacent base steel plates 11a within the squeeze ring 16 are pressure-bonded via the adhesive layer 11b. That is, vertically adjacent core sheets 1a are temporarily bonded to each other within the squeeze ring 16. The multiple core sheets 1a temporarily bonded to each other within the squeeze ring 16 are discharged from the squeeze ring 16 as a stack 2.

[0090] 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 laminate 2 is, for example, 0.1 kg to 6.0 kg. When manufacturing a larger laminate 2, for example, a laminate 2 with a mass exceeding 6.0 kg, it is preferable to pass the laminate 2 through the squeeze ring 16 while supporting it from below with a support device (not shown).

[0091] The laminate 2 manufactured as described above is transported to a heating furnace. In the heating furnace, the laminate 2 is heated as an object, whereby the adhesive layer 11b of each core sheet 1a is cured and the multiple core sheets 1a are fixed to each other. This completes the laminated core. That is, in this embodiment, the heating furnace is a manufacturing device that heats multiple core sheets stacked via adhesive layers to manufacture a laminated core. Hereinafter, heating of the laminate 2 in the heating furnace will be described in detail.

[0092] (Configuration of heating furnace) Fig. 11 is a schematic diagram showing a heating furnace. As shown in Fig. 11, the heating furnace 20 has a housing 20a that houses the laminate 2 therein. A plurality of heat source units 22 are provided inside the housing 20a. In this embodiment, the laminate 2 is housed in the heating furnace 20 so that the stacking direction of the plurality of core sheets 1a (see Fig. 9) is the vertical direction. Note that, hereinafter, when simply referred to as the stacking direction, it means the stacking direction of the plurality of core sheets.

[0093] 12A and 12B are schematic diagrams showing the positional relationship between the laminate 2 and the plurality of heat source sections 22 in the heating furnace 20. Specifically, FIG. 12A is a view of the laminate 2 and the plurality of heat source sections 22 as seen from the stacking direction, and FIG. 12B is a view of the laminate 2 and the plurality of heat source sections 22 as seen from a direction perpendicular to the stacking direction. Note that FIG. 12A shows a first direction X and a second direction Y that are perpendicular to each other as seen from the stacking direction. Furthermore, FIG. 12B shows a third direction Z that is perpendicular to the first direction X and the second direction Y in addition to the first direction X. The third direction Z coincides with the stacking direction of the laminate 2.

[0094] 11, 12A, and 12B, in this embodiment, the heat source units 22 are arranged in multiple stages at intervals in the vertical direction so as to surround the stack 2 housed in the housing 20a. In this embodiment, four heat source units 22 are provided in each stage. As shown in FIG. 12A, two of the four heat source units 22 in each stage are provided so as to sandwich the stack 2 in the first direction X, and the other two heat source units 22 are provided so as to sandwich the stack 2 in the second direction Y.

[0095] When viewed from the stacking direction, each heat source section 22 is provided to extend in the first direction X or the second direction Y. In this embodiment, each heat source section 22 is provided to extend linearly in the first direction X or the second direction Y. In this embodiment, the four heat source sections 22 in each stage are arranged on the same plane perpendicular to the stacking direction. Furthermore, when viewed from the stacking direction, the four heat source sections 22 in each stage are respectively arranged on each side of an imaginary square 500 that surrounds the object to be heated (in this embodiment, the stack 2). In this embodiment, the center of the square 500 coincides with the center of the object to be heated (in this embodiment, the stack 2). In this embodiment, each heat source section 22 is formed by one rod-shaped heating element 30 provided to extend in the first direction X or the second direction Y. Therefore, the four heating elements 30 in each stage are arranged on the same plane perpendicular to the stacking direction. Furthermore, when viewed from the stacking direction, the four heating elements 30 on each stage are arranged on each side of an imaginary square 500 that surrounds the stack 2. The same applies to the embodiments shown in Figures 16A, 17, 19, and 20A described below.

[0096] The laminate 2 is heated by near-infrared rays emitted from each heating element 30. The heating elements 30 emit near-infrared rays with a wavelength of, for example, 750 to 1000 nm. The energy density (lamp power density) of the heating elements 30 is, for example, preferably 5 W / mm or more, more preferably 7 W / mm or more. The heat source unit is preferably configured so that the near-infrared rays emitted from the heating elements are irradiated onto the object to be heated (multiple core sheets or squeeze rings) as parallel or divergent light. This also applies to the embodiments described below. In this specification, parallel light means light that travels without diverging radially or converging. Known means can be used to convert the near-infrared rays emitted from the heating elements into parallel light, so a detailed description will be omitted.

[0097] 12A and 12B are schematic diagrams showing the positional relationship between the laminate 2 and the heat source section 22 (heat generating element 30), and the heat generating element 30 shown in Figures 12A and 12B does not accurately represent the shape of the actual heat generating element 30. Although a detailed description will be omitted, the heat generating element 30 is configured in the same manner as the heat generating elements 61 to 64 described above.

[0098] 12A, in this embodiment, the stack 2 is provided at the center of the four heat source parts 22 (heat generating elements 30). In other words, the distances from the center of the stack 2 to the four heat source parts 22 are equal when viewed from the stacking direction. In this embodiment, the distance W between the heat source parts 22 facing each other in the first direction X when viewed from the stacking direction is x and the distance W between the heat source parts 22 facing each other in the second direction Y. y is equal to.

[0099] When the four heat source parts 22 are actually arranged around the laminated body 2, the distance W between a pair of heat source parts 22 facing each other in the first direction X is x and the distance W between a pair of heat source parts 22 facing each other in the second direction Y. y In such a case, it is difficult to completely match the distance W between the pair of heat sources facing each other among the four heat sources. x and the distance W between another pair of opposing heat sources. y The difference between these is preferably within 10 mm, and more preferably within 5 mm, as in the embodiments shown in Figures 14A, 16A, 17, 18A, 19, and 20A, which will be described later.

[0100] Furthermore, when actually arranging the four heat source sections 22 around the stack 2, it is difficult to perfectly align the center of the stack 2 with the center of the four heat source sections 22 as viewed from the stacking direction. In this embodiment, the centers of the four heat source sections 22 as viewed from the stacking direction refer to the center 402 of a rectangle 400 formed by four straight lines 400a, 400b, 400c, and 400d passing through the long side (inner edge) 301 of each heat generating element 30 on the inner side (the side facing the heated object) as viewed from the stacking direction, as shown in FIG. 12C . Each of the straight lines 400a, 400b, 400c, and 400d is parallel to the corresponding long side 301. In this case, the distance between the center of the heated object (in this embodiment, the stack 2) and the center of the four heat source sections 22 as viewed from the stacking direction is preferably within 20 mm, and more preferably within 10 mm. This also applies to the embodiments shown in FIGS. 16A, 17, 19, and 20A, which will be described later.

[0101] In this embodiment, in the heating furnace 20, the heat source parts 22 are arranged so as to satisfy the following formula (16). 0.38<0.88((W-D1) / W) 0.22 ×((L-D1) / L) 0.20 ≦1.0 (16) In the above formula (16), W represents the distance (mm) between a heat source 22 and another heat source 22 facing it, D1 represents the diameter (mm) of the laminate 2 (core sheet 1a), and L represents the length (mm) of the heat source 22. In this embodiment, each heat source 22 is formed by one heat generating element 30, so W represents the distance between the opposing heat generating elements 30, and L represents the length of the heat generating element 30 (length of the heat generating portion). With reference to FIG. 12A, for example, for a pair of heat generating elements 30 facing each other in the first direction X, W in the above formula (16) represents the distance W between the pair of heat generating elements 30 facing each other in the first direction X. x Furthermore, for example, for a pair of heating elements 30 facing each other in the second direction Y, W in the above formula (16) is the distance W between the pair of heating elements 30 facing each other in the second direction Y. y This also applies to the embodiments shown in Figures 16A, 17, 19 and 20A, which will be described later.

[0102] By arranging four heat source parts 22 around the laminate 2 so as to satisfy the above formula (16), it is possible to suppress the occurrence of circumferential temperature deviation on the outer peripheral surface 2a of the laminate 2. As a result, it is possible to suppress deterioration in the flatness of the laminate (laminated core) 2. The value of the middle part of the above formula (16) is preferably 0.40 or more, and more preferably 0.42 or more.

[0103] In this embodiment, the length L of the heat source 22 is greater than the diameter D1 of the laminate 2. This allows the laminate 2 to be heated efficiently.

[0104] For example, the length direction in the heat source arrangement in FIG. 12A is the direction of the arrow indicated by the symbol L, and the length of the heat source 22 is the length of the arrow indicated by the symbol L. In other words, the length of the heat source 22 means the length in the first direction X or the second direction Y. Also, for example, the measurement position of the distance between the heat sources 22 using the rod-shaped heating element 30 in FIG. 12A is the direction indicated by the symbol W. x ,W y The distance between the heat sources 22 is indicated by the arrow W x ,W y The same applies to the embodiments shown in Figures 16A, 17, 19 and 20A, which will be described later.

[0105] When actually installing multiple heat source parts, it is difficult to make each heat source part perfectly parallel to the first direction X or the second direction Y. In other words, it is difficult to arrange a pair of heat source parts facing each other perfectly parallel to each other. For this reason, the distance between one end of two opposing heat source parts in the length direction may not match the distance between the other end of the two opposing heat source parts in the length direction. In such cases, the average value of the distance between one end and the distance between the other end of the two opposing heat source parts is used as the value of W in the above formula (16). For example, in FIG. 12A, the distance W between two heat source parts 22 (heat generating elements 30) facing each other in the first direction X is xWhen measuring, the distance between the one ends 220 of the two heat source parts 22 (heat generating elements 30) in the longitudinal direction may not match the distance between the other ends 222. In this case, the average value of the distance between the one ends 220 and the distance between the other ends 222 is used as the value of W in the above formula (16). Note that, for opposing heat source parts, the difference between the distance between the one ends and the other ends in the longitudinal direction is preferably within 10 mm, and more preferably within 5 mm. The same applies to the embodiments described later.

[0106] Furthermore, when actually installing multiple heat source units, it is difficult to completely match the heights of the multiple heat source units (heat generating elements) on each tier. In each tier, the difference in height between the upper end positions of the multiple heat source units (heat generating elements) is preferably within 10 mm, and more preferably within 5 mm. Furthermore, it is difficult to make each heat source unit (heat generating element) completely parallel to the horizontal direction (the direction perpendicular to the third direction Z). The difference in height between one end and the other end of each heat source unit (heat generating element) is preferably within 10 mm, and more preferably within 5 mm. The same applies to the embodiments described below.

[0107] (Variation) Although the laminate 2 shown in FIG. 12A has a circular outer peripheral surface as viewed in the stacking direction, the present invention can also be applied to cases where the outer peripheral surface of the laminate 2 is not perfectly circular. In other words, the outer peripheral surface of the laminate may have convex portions protruding radially outward or concave portions recessed radially inward. That is, in this specification, the circular outer peripheral surface as viewed in the stacking direction includes a substantially circular outer peripheral surface on which convex portions protruding radially outward or concave portions recessed radially inward are formed. In such cases, the diameter D1 in the above formula (16) is defined for the portion of the outer peripheral surface of the laminate excluding the convex portions or concave portions. For example, as shown in FIG. 13, if the outer peripheral surface 2a of the laminate 2 has multiple convex portions 2b, the diameter D1 in the above formula (16) refers to the diameter of the laminate 2 as defined for the portion of the outer peripheral surface 2a excluding the convex portions 2b.

[0108] In the above embodiment, the heat source parts 22 are arranged in five stages, but the heat source parts 22 may be arranged in four stages or less, or six stages or more, depending on the dimensions of the laminate 2. For example, only four heat source parts 22 (heat generating elements 30) may be arranged around the laminate 2, similar to the heat generating elements 61 to 64 shown in FIG.

[0109] In the above embodiment, each heat source 22 is configured by one heat generating element 30 extending in the first direction X or the second direction Y, but the configuration of the heat source is not limited to the above example. For example, the heat source may be configured by a plurality of heat generating elements. An example will be described below.

[0110] 14A and 14B are schematic diagrams showing modified examples of heat source units arranged in a heating furnace. Specifically, FIG. 14A is a view of the stack 2 and the multiple heat source units 24 as viewed from the stacking direction, and FIG. 14B is a view of the stack 2 and the multiple heat source units 24 as viewed from a direction perpendicular to the stacking direction. Note that FIG. 14A shows a first direction X and a second direction Y that are perpendicular to each other as viewed from the stacking direction. Furthermore, FIG. 14B shows a third direction Z that is perpendicular to the first direction X and the second direction Y in addition to the first direction X. The third direction Z coincides with the stacking direction of the stack 2.

[0111] As shown in FIGS. 14A and 14B , in this embodiment, four heat source sections 24 are arranged to surround the stack 2. When viewed from the stacking direction, each heat source section 24 is provided to extend in the first direction X or the second direction Y. In this embodiment, each heat source section 24 is provided to extend linearly in the first direction X or the second direction Y. In this embodiment, each heat source section 24 is composed of a plurality of heat generating elements 30 arranged side by side in the first direction X or the second direction Y. Each heat generating element 30 is provided to extend in the third direction Z. In this embodiment, one heat source section 24 is composed of nine heat generating elements 30. In this embodiment, in each heat source section 24, the plurality of heat generating elements 30 are fixed to each other by a fixing member (not shown).

[0112] Two of the four heat source sections 24 are arranged to sandwich the stack 2 in the first direction X, and the other two heat source sections 24 are arranged to sandwich the stack 2 in the second direction Y. In other words, the four heat source sections 24 are arranged so that a heat source section 24 is located on both sides of the stack 2 in the first direction X and on both sides of the stack 2 in the second direction Y. In this embodiment, the heat source sections 24 located on both sides of the stack 2 in the first direction X are each arranged to overlap the stack 2 when viewed from the first direction X. Furthermore, the heat source sections 24 located on both sides of the stack 2 in the second direction Y are each arranged to overlap the stack 2 when viewed from the second direction Y. As shown in FIG. 14A , in this embodiment as well, the stack 2 is provided at the center of the four heat source sections 24, as in the above embodiment (see FIG. 12A ). In other words, as shown in FIGS. 14A and 14B, in this embodiment, each of the four heat source sections 24 is composed of nine rod-shaped heating elements 30. Each heat source section 24 is composed of nine heating elements 30 arranged so that the long side direction of each heating element 30 coincides with the stacking direction, and the entire heat source section 24 forms a single flat plate. Furthermore, as shown in FIG. 14A, the four flat plate-shaped heat source sections 24, as viewed from the stacking direction, are each arranged on each side of an imaginary square 500 that surrounds the object to be heated (the stack 2 in this embodiment). As described above, the center of the square 500 coincides with the center of the object to be heated (the stack 2 in this embodiment). The same applies to the embodiment shown in FIG. 18A, which will be described later.

[0113] In this embodiment, L in the above formula (16) means the total length of the plurality of heat generating elements 30 in the longitudinal direction of the heat source unit 24. Therefore, as shown in FIG. 14A, the length of the heat generating elements 30 in the longitudinal direction (first direction X or second direction Y) of the heat source unit 24 is defined as L 30 In this case, the value of L in the above formula (16) is the length L 30The value obtained by multiplying the value by nine is the value obtained by multiplying the value by nine. Note that the length direction of the heat source unit 24 in this embodiment is the direction of the arrow indicated by the symbol L30 in FIG. 14A, and the value of L (the length of the heat source unit 24) in the above formula (16) is the value obtained by multiplying the length of the arrow indicated by the symbol L30 by nine. Also, with reference to FIG. 14A, for example, for a pair of heat source units 24 facing each other in the first direction X, W in the above formula (16) is the distance W between the pair of heat source units 24 facing each other in the first direction X. x For example, for a pair of heat source parts 24 facing each other in the second direction Y, W in the above formula (16) is the distance W between the pair of heat source parts 24 facing each other in the second direction Y. y The measurement position of the distance between the heat sources 24 in FIG. 14A is indicated by the symbol W x ,W y The distance between the heat sources 24 is indicated by the arrow W x ,W y The length of the arrow indicated by the arrow. The length direction, the value of the length L, the distance W x ,W y The same applies to the embodiment shown in FIG. 18A, which will be described later.

[0114] In this embodiment, the centers of the four heat source sections 24 as viewed from the stacking direction can be considered to be the same as the centers of the four heat source sections 22 shown in FIG. 12. Specifically, as shown in FIG. 14C, the centers of the four heat source sections 24 are defined as centers 402 of quadrangles 400 formed by four straight lines 400a, 400b, 400c, and 400d passing through the long sides of the inner side (the heated object side) of each flat-plate-shaped heat source section 24 as viewed from the stacking direction. In this embodiment as well, the distance between the center of the heated object (in this embodiment, the stacked body 2) and the centers of the four heat source sections 24 as viewed from the stacking direction is preferably within 20 mm, and more preferably within 10 mm. This also applies to the embodiment shown in FIG. 18A described below.

[0115] In this embodiment as well, by arranging four heat source parts 24 around the periphery of the laminate 2 so as to satisfy the above formula (16), it is possible to suppress the occurrence of temperature deviation in the circumferential direction on the outer peripheral surface 2a of the laminate 2. As a result, it is possible to suppress deterioration in the flatness of the laminate (laminated core) 2. Also in this embodiment as well, by making the length of the heat source parts 24 longer than the diameter D1 of the laminate 2, it is possible to efficiently heat the laminate 2.

[0116] In the above-described embodiment, each heat source 24 is configured with nine heating elements 30, but each heat source 24 may be configured with eight or fewer heating elements 30, or may be configured with ten or more heating elements 30. The same applies to the embodiments described below.

[0117] (Second embodiment) Fig. 15 is a diagram showing a laminate manufacturing apparatus used in a laminated core manufacturing method according to a second embodiment of the present invention. Similar to the manufacturing apparatus 100 shown in Fig. 9, the manufacturing apparatus 100a shown in Fig. 15 is an apparatus for punching out multiple core sheets 1a from a steel strip 1 conveyed in a predetermined direction and bonding the resulting multiple core sheets 1a together to manufacture a laminated body 2. However, in this embodiment, the laminated core is manufactured by heating the laminated body 2 in the manufacturing apparatus 100a rather than in a heating furnace. This will be described in detail below.

[0118] As shown in FIG. 15, in this embodiment, the manufacturing apparatus 100a also includes a base unit 10, a punch 12, a punching die 14, and a squeeze ring 16, similar to the manufacturing apparatus 100 described above. Furthermore, in the manufacturing apparatus 100a according to this embodiment, a plurality of heat sources 22 are provided to surround the squeeze ring 16. In this embodiment, the squeeze ring 16 is heated as an object by the plurality of heat sources 22. This heats the laminate 2 passing through the squeeze ring 16. As a result, the adhesive layer 11b of each core sheet 1a hardens, and the plurality of core sheets 1a (see FIG. 9) are fixed to one another. After the plurality of core sheets 1a are fixed to one another, the laminate 2 is discharged from the squeeze ring 16 as a laminated core.

[0119] 16A and 16B are schematic diagrams showing the positional relationship between the squeeze ring 16 and the multiple heat source sections 22. Specifically, FIG. 16A is a view of the squeeze ring 16 and the multiple heat source sections 22 as viewed from the stacking direction of the laminated body 2, and FIG. 16B is a view of the squeeze ring 16 and the multiple heat source sections 22 as viewed from a direction perpendicular to the stacking direction of the laminated body 2. Note that FIG. 16A shows a first direction X and a second direction Y that are perpendicular to each other as viewed from the stacking direction. Furthermore, FIG. 16B shows a third direction Z that is perpendicular to the first direction X and the second direction Y in addition to the first direction X. The third direction Z coincides with the stacking direction of the laminated body 2.

[0120] 12A and 12B, in this embodiment, the heat source portions 22 are arranged in multiple stages (four stages in FIG. 16B) spaced apart in the vertical direction. Four heat source portions 22 are provided in each stage. Of the four heat source portions 22 in each stage, two heat source portions 22 are provided so as to sandwich the squeeze ring 16 in the first direction X, and the other two heat source portions 22 are provided so as to sandwich the squeeze ring 16 in the second direction Y. In other words, the four heat source portions 22 are provided so that one heat source portion 22 is located on both sides of the squeeze ring 16 in the first direction X and one heat source portion 22 is located on both sides of the squeeze ring 16 in the second direction Y. In this embodiment, the heat source portions 22 located on both sides of the squeeze ring 16 in the first direction X are each provided so as to overlap the squeeze ring 16 when viewed from the first direction X. Furthermore, the heat source parts 22 located on both sides of the squeeze ring 16 in the second direction Y are each provided so as to overlap the squeeze ring 16 when viewed from the second direction Y.

[0121] When viewed from the stacking direction, each heat source 22 is provided to extend in the first direction X or the second direction Y. In this embodiment, each heat source 22 is provided to extend linearly in the first direction X or the second direction Y. In this embodiment, similar to the embodiment shown in FIGS. 12A and 12B , each heat source 22 is configured by one heating element 30 provided to extend in the first direction X or the second direction Y. The squeeze ring 16 is heated by near-infrared rays radiated from each heating element 30.

[0122] As shown in FIG. 16A , a squeeze ring 16 is provided at the center of four heat source portions 22 (heat generating elements 30). In other words, the distances from the center of the squeeze ring 16 to the four heat source portions 22 are equal to each other when viewed from the stacking direction (the axial direction of the squeeze ring 16). Furthermore, similar to the embodiment described above and shown in FIGS. 12A and 12B , the distance between the heat source portions 22 facing each other in the first direction X is equal to the distance between the heat source portions 22 facing each other in the second direction Y when viewed from the stacking direction. When actually arranging the four heat source portions 22 around the squeeze ring 16, it is difficult to perfectly align the center of the squeeze ring 16 with the centers of the four heat source portions 22 when viewed from the stacking direction. In such a case, as described above, the distance between the center of the squeeze ring 16 and the centers of the four heat source portions when viewed from the stacking direction is preferably within 20 mm, and more preferably within 10 mm.

[0123] 16A and 16B, in this embodiment, the four heat source parts 22 are each composed of four rod-shaped heating elements 30. When viewed from the stacking direction, each heat source part 22 is configured by aligning the long side direction of the heating element 30 with the first direction X or the second direction Y, and arranged to form a single flat plate. Furthermore, when viewed from the stacking direction, each of the four heat source parts 22 is arranged on a side of a square surrounding the squeeze ring 16.

[0124] In this embodiment, the heat source parts 22 are arranged so as to satisfy the following formula (17). 0.38<0.88((W-D2) / W) 0.22 ×((L-D2) / L)0.20 ≦1.0 (17) As shown in FIG. 16A, in the above formula (17), W represents the distance (mm) between the heat source 22 and the heat source 22 facing it, D2 represents the diameter (mm) of the squeeze ring 16, and L represents the length (mm) of the heat source 22. In this embodiment, each heat source 22 is formed by one heating element 30, so W represents the distance between the heating elements 30 facing each other, and L represents the length of the heating element 30. Note that the length direction of the heat source 22 in this embodiment is the direction of the arrow indicated by the symbol L in FIG. 16A, and the value of L (the length of the heat source 22) in the above formula (17) is the length of the arrow indicated by the symbol L itself. In other words, the length of the heat source 22 means the length in the first direction X or the second direction Y. Furthermore, referring to FIG. 16A, for example, for a pair of heating elements 30 facing each other in the first direction X, W in the above formula (17) is the distance W between the pair of heating elements 30 facing each other in the first direction X. x Furthermore, for example, for a pair of heating elements 30 facing each other in the second direction Y, W in the above formula (17) is the distance W between the pair of heating elements 30 facing each other in the second direction Y. y means.

[0125] By arranging the four heat sources 22 around the squeeze ring 16 so as to satisfy the above formula (17), it is possible to suppress the occurrence of circumferential temperature deviation on the outer peripheral surface 16a of the squeeze ring 16. This makes it possible to suppress the occurrence of circumferential temperature deviation on the outer peripheral surface 2a of the laminate 2, which is heated by heat transfer from the squeeze ring 16. As a result, it is possible to suppress deterioration in the flatness of the laminate (laminated core) 2. The value of the middle part of the above formula (17) is preferably 0.40 or more, and more preferably 0.42 or more.

[0126] In this embodiment, the length L of the heat source 22 is greater than the diameter D2 of the squeeze ring 16. This allows the squeeze ring 16 to be heated efficiently.

[0127] 12A and 12B, in this embodiment, the distance between the ends of two opposing heat sources in the longitudinal direction may not coincide with the distance between the ends of the two opposing heat sources in the longitudinal direction. In such cases, the average of the distances between the ends of the two opposing heat sources and the distances between the ends of the two opposing heat sources is used as the value of W in the above formula (17), as in the above embodiment.

[0128] (Variation) 16A has a circular outer peripheral surface (outer peripheral edge) when viewed in the stacking direction (axial direction of the squeeze ring 16), but the shape of the squeeze ring to which the present invention can be applied is not limited to the above example. For example, the present invention can also be applied to squeeze rings having an outer peripheral surface (outer peripheral edge) that is an octagon or more polygonal shape when viewed in the stacking direction (axial direction of the squeeze ring), or an elliptical outer peripheral surface. An example will be described below.

[0129] FIG. 17 is a diagram showing the positional relationship between a squeeze ring having a polygonal outer peripheral surface and multiple heat sources. When using a squeeze ring 17 having a polygonal outer peripheral surface 17a as shown in FIG. 17, the diameter of a circumscribed circle C circumscribing the outer peripheral surface 17a of the squeeze ring 17 as viewed in the stacking direction (the axial direction of the squeeze ring 17) is defined as the diameter D2 in the above formula (17). By defining the diameter D2 in this manner and arranging four heat sources 22 around the squeeze ring 17 so as to satisfy the above formula (17), it is possible to suppress the occurrence of a circumferential temperature deviation on the outer peripheral surface 17a of the squeeze ring 17. This suppresses the occurrence of a circumferential temperature deviation on the outer peripheral surface 2a of the laminate 2, which is heated by heat transfer from the squeeze ring 17. As a result, it is possible to suppress deterioration in the flatness of the laminate (laminated core) 2. This also applies to the embodiments described below. In this specification, the circumscribing circle of the squeeze ring means an imaginary circle that has the center of gravity of the squeeze ring as its center and passes through the position on the squeeze ring that is farthest from the center of gravity when viewed from the stacking direction.

[0130] In the above-described embodiment, the heat source sections 22 are arranged in four stages, but depending on the dimensions of the squeeze ring, the heat source sections 22 may be arranged in three stages or less, or in four stages or more.

[0131] In the above-described embodiment, each heat source 22 is configured by one heating element 30 extending in the first direction X or the second direction Y. However, the heat source may be configured similarly to the examples shown in Figures 14A and 14B. A brief explanation will be given below with reference to the drawings.

[0132] Fig. 18A is a view of the squeeze ring 16 and the multiple heat source parts 24 as viewed from the stacking direction, and Fig. 18B is a view of the squeeze ring 16 and the multiple heat source parts 24 as viewed from a direction perpendicular to the stacking direction. Fig. 18A also shows a first direction X and a second direction Y that are perpendicular to each other as viewed from the stacking direction. Fig. 18B also shows a third direction Z that is perpendicular to the first direction X and the second direction Y in addition to the first direction X. The third direction Z coincides with the stacking direction of the laminate 2.

[0133] 18A and 18B , in this embodiment, four heat source sections 24 are arranged to surround the squeeze ring 16. Each heat source section 24 is composed of nine heating elements 30 arranged to extend in the third direction Z. Two of the four heat source sections 24 are arranged to sandwich the squeeze ring 16 in the first direction X, and the other two heat source sections 24 are arranged to sandwich the squeeze ring 16 in the second direction Y. In other words, the four heat source sections 24 are arranged so that one heat source section 24 is located on both sides of the squeeze ring 16 in the first direction X and one heat source section 24 is located on both sides of the squeeze ring 16 in the second direction Y. In this embodiment, the heat source sections 24 located on both sides of the squeeze ring 16 in the first direction X are arranged so as to overlap the squeeze ring 16 when viewed from the first direction X. Furthermore, the heat source parts 24 located on both sides of the squeeze ring 16 in the second direction Y are each provided so as to overlap the squeeze ring 16 when viewed from the second direction Y. In this embodiment, as in the above embodiment (see FIG. 16A), the squeeze ring 16 is provided at the center of the four heat source parts 24.

[0134] In this embodiment, L in the above formula (17) means the total length of the plurality of heat generating elements 30 in the longitudinal direction of the heat source unit 24. Therefore, as shown in FIG. 18A, the length of the heat generating elements 30 in the longitudinal direction (first direction X or second direction Y) of the heat source unit 24 is defined as L 30 In this case, the value of L in the above formula (17) is the length L 30 This is the value obtained by multiplying by 9.

[0135] In this embodiment as well, by arranging four heat sources 24 around the laminate 2 so as to satisfy the above formula (17), it is possible to suppress the occurrence of circumferential temperature deviation on the outer peripheral surface 16a of the squeeze ring 16. This suppresses the occurrence of circumferential temperature deviation on the outer peripheral surface 2a of the laminate 2, which is heated by heat transfer from the squeeze ring 16. As a result, it is possible to prevent deterioration of the flatness of the laminate 2 (laminated core). Also in this embodiment, by making the length of the heat source 24 greater than the diameter D2 of the squeeze ring 16, it is possible to efficiently heat the laminate 2. Note that, although not shown, the four heat sources 24 may be similarly arranged when using a squeeze ring 17 (see FIG. 17) having an outer peripheral surface 17a (see FIG. 17) that is an octagon or higher polygon or an ellipse.

[0136] In the above-described embodiment, the squeeze ring holds the laminate having a circular outer peripheral surface, but the shape of the laminate held by the squeeze ring is not limited to the above-described example. Although a detailed description is omitted, for example, as shown in Fig. 19, even when a squeeze ring 18 is used to hold the laminate 3 as a divided core, multiple heat sources 22 may be arranged to surround the squeeze ring 18, as in the embodiment shown in Figs. 16A and 16B. Furthermore, although not shown, four heat sources 24 may be arranged to surround the squeeze ring 18, as in the embodiment shown in Figs. 18A and 18B.

[0137] Although the squeeze rings 16, 17, and 18 have a circular outer peripheral surface, the present invention can also be applied to cases where the outer peripheral surfaces of the squeeze rings 16, 17, and 18 are not perfectly circular. In other words, the outer peripheral surfaces of the squeeze rings may be provided with convex portions that protrude radially outward or concave portions that recess radially inward. In such cases, the diameter D2 in the above formula (17) is defined for the portion of the outer peripheral surface of the squeeze ring excluding the convex portions or concave portions.

[0138] (Third embodiment) In the above-described embodiment, a squeeze ring having a circular outer peripheral surface as viewed from the stacking direction is used. However, the present invention is also applicable to a squeeze ring having a rectangular outer peripheral surface as viewed from the stacking direction of the laminate.

[0139] 20A and 20B are diagrams showing a squeeze ring 19 used in a manufacturing method of a laminated core according to a third embodiment of the present invention. As shown in FIG. 20A, in this embodiment, a squeeze ring 19 holds laminates 3 as split cores. FIG. 20A also shows a first direction X and a second direction Y that are perpendicular to each other when viewed from the stacking direction of the laminates 3. FIG. 20B also shows a third direction Z that is perpendicular to the first direction X and the second direction Y in addition to the first direction X. The third direction Z coincides with the stacking direction of the laminates 3.

[0140] In a manufacturing apparatus using a squeeze ring 19, similar to the manufacturing apparatus 100a shown in FIG. 15, a plurality of core sheets 3a punched out by a punch and a punching die are pressed together inside the squeeze ring 19. The squeeze ring 19 is heated as an object by a plurality of heat sources 22 provided so as to surround the squeeze ring 19. This heats the laminate 3 passing through the squeeze ring 19. As a result, the adhesive layer of each core sheet 3a hardens, and the plurality of core sheets 3a are fixed together. After the plurality of core sheets 3a are fixed together, the laminate 3 is discharged from the squeeze ring 19 as a laminated core (divided core).

[0141] When viewed from the stacking direction of the laminate 3, the outer peripheral surface of the squeeze ring 19 forms a rectangle having a pair of long sides 19a and a pair of short sides 19b. x and the length of the short side 19b M y20A, in this embodiment, when viewed from the stacking direction (axial direction of the squeeze ring 19), the first direction X is a direction parallel to the long sides 19a, and the second direction Y is a direction parallel to the short sides 19b. In this embodiment, the squeeze ring 19 has a pair of side surfaces 191a perpendicular to the second direction Y and a pair of side surfaces 191b perpendicular to the first direction X. Note that the squeeze ring 19 is configured in the same manner as the squeeze ring 70 shown in FIG. 6, and therefore a detailed description of the squeeze ring 19 will be omitted.

[0142] 16A and 16B, in this embodiment, the heat source sections 22 are arranged in multiple stages (four stages in FIG. 20B) spaced apart from one another in the vertical direction. Four heat source sections 22 are provided in each stage. Also, as in the embodiment shown in FIGS. 16A and 16B, each heat source section 22 is provided to extend in the first direction X or the second direction Y. In this embodiment, each heat source section 22 is provided to extend linearly in the first direction X or the second direction Y. Two of the four heat source sections 22 in each stage are provided to sandwich the squeeze ring 19 in the first direction X, and the other two heat source sections 22 are provided to sandwich the squeeze ring 19 in the second direction Y. In other words, the four heat source sections 22 are provided so that a heat source section 22 is located on both sides of the squeeze ring 19 in the first direction X and on both sides of the squeeze ring 19 in the second direction Y. In this embodiment, two of the four heat source portions 22 are arranged parallel to the short sides 19b, and the other two heat source portions 22 are arranged parallel to the long sides 19a. The heat source portions 22 located on both sides of the squeeze ring 19 in the first direction X are arranged so as to overlap the squeeze ring 19 when viewed from the first direction X. Furthermore, the heat source portions 22 located on both sides of the squeeze ring 19 in the second direction Y are arranged so as to overlap the squeeze ring 19 when viewed from the second direction Y. As in the above-described embodiment, each heat source portion 22 is formed by one heating element 30. When viewed from the stacking direction, the long side of each heating element 30 is parallel to the first direction X or the second direction Y. In other words, when viewed from the stacking direction, the long side of the heating element 30 is parallel to the long side 19a or the short side 19b of the squeeze ring 19. The squeeze ring 19 is heated by near-infrared rays radiated from each heating element 30.

[0143] 20A, squeeze ring 19 is provided at the center of four heat source parts 22 (heat generating elements 30). In other words, when viewed from the stacking direction, the distances from the center of squeeze ring 19 to the four heat source parts 22 are equal to each other.

[0144] In this embodiment, the heat source parts 22 are arranged so as to satisfy the following formula (18). 0.63<1.03((WM) / W) -0.16 ×((LM) / L) 0.30 ≦1.0 (18) In the above formula (18), W represents the distance (mm) between a heat source 22 and another heat source 22 facing that heat source 22, M represents the length (mm) of the squeeze ring 19 in a direction perpendicular to the longitudinal direction of the heat source 22, and L represents the length (mm) of the heat source 22. In this embodiment, each heat source 22 is formed by one heat generating element 30, so W represents the distance between the opposing heat generating elements 30, and L represents the length of the heat generating element 30. Referring to FIG. 20A, in this embodiment, the longitudinal direction is the direction of the arrow indicated by the symbol L, and the length of the heat source 22 is the length of the arrow indicated by the symbol L. In other words, the length of the heat source 22 means the length in the first direction X or the second direction Y. The measurement position of the distance between the heat sources 22 is indicated by the symbol W. x ,W y The distance between the heat sources 22 is indicated by the arrow W x ,W y The length of the arrow indicated by

[0145] In addition, in Figure 20A, if, of the four heat source sections 22, two heat source sections 22 parallel to the long sides 19a are each designated as first heat source sections 22a and two heat source sections 22 parallel to the short sides 19b are each designated as second heat source sections 22b, the first heat source sections 22a are arranged to satisfy the following formula (18a) and the second heat source sections 22b are arranged to satisfy the following formula (18b).

[0146] 0.63<1.03((W y -M y ) / W y ) -0.16 ×((LM y ) / L) 0.30 ≦1.0 (18a) 0.63<1.03((W x -M x ) / W x ) -0.16 ×((LM x ) / L) 0.30 ≦1.0 (18b) However, in the above formula, W y indicates the distance (mm) between the first heat source parts 22a, and M y indicates the length of the short side 19b (mm), and W x indicates the distance (mm) between the second heat source parts 22b, and M x indicates the length (mm) of the long side 19a, and L indicates the length (mm) of the heat generating element 30 (first heat source part 22a or second heat source part 22b).

[0147] By arranging four heat sources 22 around the squeeze ring 19 so as to satisfy the above formula (18), it is possible to suppress the occurrence of temperature deviation in the circumferential direction on the outer peripheral surface of the squeeze ring 19. This makes it possible to suppress the occurrence of temperature deviation in the circumferential direction on the outer peripheral surface of the laminate 3, which is heated by heat transfer from the squeeze ring 19. As a result, it is possible to suppress deterioration in the flatness of the laminate 3 (laminated core). Note that the values ​​of the middle sides of the above formulas (18), (18a), and (18b) are preferably 0.67 or more, and more preferably 0.70 or more.

[0148] In this embodiment, the length L of the heat source portion 22 is greater than the lengths of the long sides 19a and short sides 19b of the squeeze ring 19. This allows the squeeze ring 19 to be heated efficiently.

[0149] 12A and 12B, in this embodiment, the distance between the ends of two opposing heat sources in the longitudinal direction may not coincide with the distance between the ends of the two opposing heat sources in the longitudinal direction. In such cases, the average of the distances between the ends of the two opposing heat sources and the distances between the ends of the two opposing heat sources is used as the value of W in the above formula (18), as in the above embodiment.

[0150] In addition, in the example shown in FIG. 20B, the heat source parts 22 are arranged in four tiers, but depending on the dimensions of the squeeze ring, the heat source parts 22 may be arranged in three tiers or less, or in four tiers or more.

[0151] 18A and 18B, four heat source portions 24 may be arranged to surround the squeeze ring 19. Specifically, when viewed from the stacking direction, a pair of heat source portions 24 may be arranged parallel to a pair of long sides 19a, and a pair of heat source portions 24 may be arranged parallel to a pair of short sides 19b. In this case, too, by arranging the four heat source portions 24 around the squeeze ring 19 so as to satisfy the above formula (18), it is possible to suppress the occurrence of circumferential temperature deviation on the outer peripheral surface of the squeeze ring 19. Note that when four heat source portions 24 are provided to surround the squeeze ring 19, L in the above formula (18) represents the total length of the multiple heating elements 30 in the longitudinal direction of the heat source portions 24, as in the above embodiment.

[0152] Although squeeze ring 19 has four flat side surfaces, the present invention can also be applied to cases where each side surface of the squeeze ring is not completely flat. In other words, each side surface of the squeeze ring may have a protrusion or recess. In such cases, the length M in the above formula (18) is defined for the portion excluding the protrusions or recesses formed on each side surface of the squeeze ring.

[0153] (Fourth embodiment) Fig. 21 is a diagram showing a squeeze ring and a plurality of heat sources used in a laminated core manufacturing method according to a fourth embodiment of the present invention. The laminated core manufacturing method according to this embodiment differs from the laminated core manufacturing method according to the third embodiment in the following respects. As shown in Fig. 21, in this embodiment, heat sources 22 are not provided on either side of the squeeze ring 19 in the second direction Y. In other words, in this embodiment, heat sources 22 are provided only on the outside of a pair of short sides 19b in the first direction X.

[0154] In this embodiment, the two heat source units 22 in each stage are arranged on the same plane perpendicular to the stacking direction. Furthermore, the two heat source units 22 in each stage are arranged on sides of an imaginary square 500 that surrounds the object to be heated (in this embodiment, squeeze ring 19) when viewed from the stacking direction. In this embodiment, the center of square 500 coincides with the center of the object to be heated (squeeze ring 19).

[0155] In this embodiment, the heat source parts 22 are arranged so as to satisfy the following formula (19). 0.24<1.27((WM) / W) -13.7 ×((LN) / L) 14.7 ≦1.0 (19) In the above formula (19), W represents the distance (mm) between opposing heat sources 22 in the first direction X, M represents the length (mm) of the long side 19a of the squeeze ring 19, L represents the length (mm) of the heat source 22, and N represents the length (mm) of the short side 19b of the squeeze ring 19. In this embodiment, each heat source 22 is formed by one heating element 30, so W represents the distance between opposing heating elements 30, and L represents the length of the heating element 30. With reference to FIG. 21 , in this embodiment, the length direction is the direction of the arrow indicated by the symbol L, and the length of the heat source 22 is the length of the arrow indicated by the symbol L. Furthermore, the measurement position of the distance between the heat sources 22 is the position of the arrow indicated by the symbol W, and the distance between the heat sources 22 is the length of the arrow indicated by the symbol W.

[0156] By arranging two heat sources 22 on both sides of the squeeze ring 19 in the first direction X so as to satisfy the above formula (19), it is possible to suppress the occurrence of temperature deviation in the first direction X on the outer peripheral surface of the squeeze ring 19. This makes it possible to suppress the occurrence of temperature deviation in the circumferential direction on the outer peripheral surface of the laminate 3, which is heated by heat transfer from the squeeze ring 19. As a result, it is possible to suppress deterioration in the flatness of the laminate 3 (laminated core). Note that the value of the middle side of the above formula (19) is preferably 0.37 or more, and more preferably 0.49 or more.

[0157] In this embodiment, the length L of the heat source portion 22 is greater than the length of the short side 19b of the squeeze ring 19. This allows the squeeze ring 19 to be heated efficiently.

[0158] 12A and 12B, in this embodiment, the distance between the ends of two opposing heat sources in the longitudinal direction may not coincide with the distance between the ends of the two opposing heat sources in the longitudinal direction. In such cases, the average of the distances between the ends of the two opposing heat sources and the distances between the ends of the two opposing heat sources is used as the value of W in the above formula (19), as in the above embodiment.

[0159] Also in this embodiment, the heat source parts 22 may be arranged in one stage in the third direction Z, or may be arranged in multiple stages.

[0160] 18A and 18B may be disposed on both sides of the squeeze ring 19 in the first direction X, respectively. Specifically, a pair of heat source sections 24 may be disposed so as to be parallel to a pair of short sides 19b when viewed from the stacking direction. In this case, too, by disposing the pair of heat source sections 24 so as to satisfy the above formula (19), it is possible to suppress the occurrence of temperature deviation on the outer peripheral surface of the squeeze ring 19. Note that, when a heat source section 24 is provided, L in the above formula (19) means the total length of the multiple heating elements 30 in the longitudinal direction of the heat source section 24, as in the above embodiment. [Example]

[0161] The effects of the manufacturing method of the laminated core according to the present invention will be explained below using examples, but the present invention is not limited to the following examples.

[0162] Example 1 A plurality of laminates 2 (thickness: 60 mm) obtained by temporarily bonding a plurality of core sheets 1a to each other by the method described in Fig. 9 were each heated by four heating elements 30 as shown in Fig. 12A. Specifically, the length L, diameter D1, and distance W x ,Wy A plurality of laminates 2 were heated at different distances, and the flatness of each laminate 2 was compared. x ,W y The heating elements 30 were all equal. In FIG. 12B, multiple heating elements 30 are arranged in the third direction Z, but in this example, the number of heating elements 30 in the third direction Z was one. That is, similar to the heating elements 61 to 64 shown in FIG. 2B, four heating elements 30 were arranged in one layer. The laminate 2 to be heated in this example was the stator of a rotating electrical machine. As the heating elements 30, HYP-28NS manufactured by Hibeck Co., Ltd. (length: 280 mm, lamp output density: 7 W / mm, rated voltage: 200 V, rated power: 1960 W) and a custom-made product (length: 260 mm, lamp output density: 7 W / mm, rated voltage: 200 V, rated power: 1820 W) were used. The base steel plate was 25HX1300 manufactured by Nippon Steel Corporation, and the adhesive layer material was an epoxy-based thermosetting resin. The base steel plate and adhesive layer are the same as those in the examples described below.

[0163] The laminate 2 was heated to 200°C by the heating element 30 to cure the adhesive layer. The temperature of the laminate 2 was then lowered to room temperature, and the flatness of the laminate 2 was then measured. Flatness is the difference between the maximum and minimum values ​​in the distribution of the thickness of the laminate 2 (the distance between one surface and the other surface of the laminate 2 in the stacking direction). In this example, the thickness of the laminate 2 was measured with a vernier caliper at 16 locations (at 22.5° intervals in the circumferential direction) on the outer periphery of the laminate 2 and at 8 locations (at 45° intervals in the circumferential direction) on the inner periphery. Note that, assuming the radius of the laminate 2 is R, the measurement position on the outer periphery was approximately 0.8R from the center of the laminate 2, and the measurement position on the inner periphery was approximately 0.4R from the center of the laminate 2. In this example, a flatness of 0.25 mm or less was considered good. Table 1 below shows the test conditions (length L, diameter D1, distance W), the value of the middle part of the above formula (16), and the flatness evaluation results for Example 1. In Table 1 below, "A" in the column for flatness indicates that the flatness was 0.25 mm or less, and "B" indicates that the flatness was more than 0.25 mm. In addition, the column for W indicates the distance W x ,W y Indicates the value of

[0164] [Table 1]

[0165] As shown in Table 1, in Test Nos. 3 to 8, which satisfied the condition of the above formula (16), the flatness was 0.25 mm or less. This result shows that by heating the laminate 2 so as to satisfy the above formula (16), it is possible to suppress deterioration of the flatness of the laminate 2 due to heating.

[0166] Example 2 As shown in Fig. 20A, four heating elements 30 were arranged around the squeeze ring 19, and the squeeze ring 19 was heated while the core sheets 3a were pressed together by the squeeze ring 19. Specifically, x ,M y , distance W x ,W y A plurality of laminates 3 (thickness: 60 mm) were heated at different temperatures, and the flatness of each laminate 3 was compared. While FIG. 20B shows a plurality of heating elements 30 arranged in the third direction Z, in this example, the number of heating elements 30 in the third direction Z was one. The laminate 3 to be heated in this example was a divided core of a stator of a rotating electrical machine. The heating elements 30 used were a HYP-28NS manufactured by Hibeck Co., Ltd. (length: 280 mm, lamp output density: 7 W / mm, rated voltage: 200 V, rated power: 1960 W) and a HYP-32NS manufactured by Hibeck Co., Ltd. (length: 320 mm, lamp output density: 7 W / mm, rated voltage: 200 V, rated power: 2240 W).

[0167] The squeeze ring 19 was heated to 200°C by the heating element 30 to cure the adhesive layer of the laminate 3. After the temperature of the laminate 3 was lowered to room temperature, the flatness of the laminate 3 was measured. The flatness is the difference between the maximum and minimum values ​​of the thickness distribution of the laminate 3 (the distance between one surface and the other surface of the laminate 3 in the stacking direction). FIG. 22 is a diagram for explaining the measurement position of the flatness of the laminate 3. FIG. 22 shows a plan view of the laminate 3 (viewed from the stacking direction). Also shown in FIG. 22 are a center line CL, a virtual line VL, and measurement points m1 to m5. The center line CL is the center line of the laminate 3 in a planar view. The virtual line VL is a circular arc that passes through the measurement point m1 and is parallel to the outer circumferential arc 3b of the laminate 3 (the portion that forms the outer periphery of the stator) in a planar view. Measurement points m1 to m3 are located on the center line CL, and measurement points m4 and m5 are located on the virtual line VL. When the length of the center line CL is A, the distance between the outer circumferential arc 3b and the measurement point m1 is 0.15A, and the distance between the measurement point m1 and the measurement point m2 and the distance between the measurement point m2 and the measurement point m3 are each 0.35A. When the length of the outer circumferential arc 3b in a plan view is K, the length of the portion of the virtual line VL between the measurement point m1 and the measurement point m4 and the length of the portion between the measurement point m1 and the measurement point m5 are each 0.25K. In this example, the thickness of the laminate 3 was measured with a vernier caliper at five points, the measurement points m1 to m5. In this example, a flatness of 0.25 mm or less was determined to be good. Table 2 below shows the test conditions (lengths L, M x ,M y , distance W x ,W y ), the value of the midpoint of the above formula (18a), the value of the midpoint of the above formula (18b), and the evaluation results of flatness are shown below. In Table 2 below, "A" in the flatness column indicates that the flatness was 0.25 mm or less, and "B" indicates that the flatness was more than 0.25 mm.

[0168] [Table 2]

[0169] As shown in Table 2, in Test Nos. 9 to 12, which satisfied both the conditions of the above formulas (18a) and (18b), the flatness was 0.25 mm or less. This result shows that by heating the squeeze ring 19 (laminate 3) so as to satisfy both the conditions of the above formulas (18a) and (18b), it is possible to suppress deterioration of the flatness of the laminate 3 due to heating.

[0170] Example 3 As shown in FIG. 21 , heating elements 30 were placed on both sides of a squeeze ring 19 in the first direction X, and the squeeze ring 19 was heated while pressing the core sheets 3 a together with the squeeze ring 19. Specifically, multiple laminates 3 (thickness: 60 mm) were heated while changing the lengths L, M, and N and the distance W shown in FIG. 21 , and the flatness of each laminate 3 was compared. In this example, the number of heating elements 30 in the third direction Z was set to one. The laminate 3 to be heated in this example was a divided core of a stator of a rotating electrical machine. The heating element 30 used was a HYP-28NS (length: 280 mm, lamp power density: 7 W / mm, rated voltage: 200 V, rated power: 1960 W) manufactured by Hibeck Co., Ltd.

[0171] The squeeze ring 19 was heated to 200°C by the heating element 30 to cure the adhesive layer of the laminate 3. After the temperature of the laminate 3 was lowered to room temperature, the flatness of the laminate 3 was measured in the same manner as in Example 2. In this example, a flatness of 0.25 mm or less was determined to be good. Table 3 below shows the test conditions (lengths L, M, N, distance W), the value of the middle part of equation (19), and the flatness evaluation results for Example 3. In Table 3 below, "A" in the flatness column indicates that the flatness was 0.25 mm or less, and "B" indicates that the flatness was greater than 0.25 mm.

[0172] [Table 3]

[0173] As shown in Table 3, in Test Nos. 14 to 16, which satisfied the condition of the above formula (19), the flatness was 0.25 mm or less. This result shows that by heating the squeeze ring 19 (laminate 3) so as to satisfy the condition of the above formula (19), it is possible to suppress deterioration of the flatness of the laminate 3 due to heating. [Industrial Applicability]

[0174] According to the present invention, deterioration of the flatness of the laminated core can be suppressed. [Explanation of symbols]

[0175] 1 Steel strip 1a, 3a core sheet 2,3 Laminate 10 Base 11a Base steel plate 11b Adhesive layer 12 Punch 14 Punching die 16, 17, 18, 19 Squeeze Ring 20 Furnace 22,24 Heat source part 30 Heating element 100,100a manufacturing equipment

Claims

1. A method for manufacturing a laminated core by heating a plurality of core sheets laminated together via an adhesive layer, comprising: When the plurality of core sheets are heated by near-infrared rays radiated from a heating element, When the near-infrared rays are directly irradiated onto the plurality of core sheets, the plurality of core sheets are used as the target, and when the near-infrared rays are irradiated onto a squeeze ring that holds the plurality of core sheets, the squeeze ring is used as the target, When the object has a circular or octagonal or more polygonal outer peripheral surface as viewed from the stacking direction of the plurality of core sheets, four heat source units are provided so as to be located on both sides of the object in a first direction and on both sides of the object in a second direction perpendicular to the first direction, When viewed from the stacking direction, a pair of heat source parts of the four heat source parts are provided to face each other in the first direction and extend in the second direction, and another pair of heat source parts of the four heat source parts are provided to face each other in the second direction and extend in the first direction, Each of the heat source units is provided with one or more of the heat generating elements, A method for manufacturing a laminated core, wherein, when viewed from the stacking direction, each of the heat source parts is arranged so as to satisfy the following formula (i): 0.38<0.88((W-D) / W) ０．２２ ×((L-D) / L) ０．２０ ≦1.0 ・・・(i) However, in the above formula, W indicates the distance between the heat source part and the heat source part opposite it, D indicates the diameter of the object if the outer peripheral surface is circular when viewed from the stacking direction, or indicates the diameter of a circle circumscribing the outer peripheral surface of the object if the outer peripheral surface is polygonal when viewed from the stacking direction, and L indicates the total length of the one or more heating elements in the longitudinal direction of the heat source part.

2. A method for manufacturing a laminated core, comprising: heating a plurality of core sheets laminated via an adhesive layer while holding the plurality of core sheets by a squeeze ring having a rectangular shape as viewed from the lamination direction of the plurality of core sheets; When the plurality of core sheets are heated by near-infrared rays radiated from a heating element, When viewed from the stacking direction, a direction perpendicular to one side of the squeeze ring is defined as a first direction, and a direction perpendicular to the first direction is defined as a second direction. Four heat source units are provided so as to be located on both sides of the squeeze ring in the first direction and on both sides of the squeeze ring in the second direction, When viewed from the stacking direction, a pair of heat source parts of the four heat source parts are provided to face each other in the first direction and extend in the second direction, and another pair of heat source parts of the four heat source parts are provided to face each other in the second direction and extend in the first direction, Each of the heat source units is provided with one or more of the heat generating elements, A method for manufacturing a laminated core, wherein, when viewed from the stacking direction, each of the heat source parts is arranged so as to satisfy the following formula (ii): 0.63<1.03((W-M) / W) －０．１６ ×((L-M) / L) ０．３０ ≦1.0 ・・・(ii) However, in the above formula, W represents the distance between the heat source part and the heat source part facing it, M represents the length of the squeeze ring in a direction perpendicular to the longitudinal direction of the heat source part, and L represents the total length of the one or more heating elements in the longitudinal direction of the heat source part.

3. A method for manufacturing a laminated core, comprising: heating a plurality of core sheets laminated via an adhesive layer while holding the plurality of core sheets by a rectangular squeeze ring having a pair of short sides and a pair of long sides when viewed from the lamination direction of the plurality of core sheets; When the plurality of core sheets are heated by near-infrared rays radiated from a heating element, two heat source portions are provided on the outside of the pair of short sides of the squeeze ring so as to extend along the pair of short sides, respectively, when viewed from the stacking direction; Each of the heat source units is provided with one or more of the heat generating elements, A method for manufacturing a laminated core, wherein, when viewed from the stacking direction, the two heat source portions are each arranged so as to satisfy the following formula (iii): 0.24<1.27((W-M) / W) －１３．７ ×((L-N) / L) １４．７ ≦1.0 ・・・(iii) However, in the above formula, W indicates the distance between the two heat source parts, M indicates the length of the long side, L indicates the total length of the one or more heating elements in the longitudinal direction of the heat source part, and N indicates the length of the short side.

4. The method for manufacturing a laminated core according to claim 1 , wherein the heating element is provided in each of the heat source portions so as to extend in the longitudinal direction of the heat source portion.

5. 4. The method for manufacturing a laminated core according to claim 1, wherein a plurality of the heating elements are provided in each heat source portion so as to extend in the stacking direction and to be aligned along the longitudinal direction of the heat source portion.

6. The method for manufacturing a laminated core according to claim 1 , wherein the near-infrared rays emitted from the heating element are irradiated as parallel or divergent light.

7. An apparatus for manufacturing a laminated core by heating a plurality of core sheets that are laminated via an adhesive layer and have a circular or polygonal outer surface with an octagon or greater number of sides as viewed from the lamination direction, four heat source units provided so as to be located on both sides of the plurality of core sheets in a first direction and on both sides of the plurality of core sheets in a second direction perpendicular to the first direction, when viewed from the stacking direction of the plurality of core sheets; When viewed from the stacking direction, a pair of heat source parts of the four heat source parts are provided to face each other in the first direction and extend in the second direction, and another pair of heat source parts of the four heat source parts are provided to face each other in the second direction and extend in the first direction, Each of the heat source units is provided with one or more heating elements that radiate near-infrared rays, A laminated core manufacturing device, wherein, when viewed from the stacking direction, each of the heat source units is arranged so as to satisfy the following formula (i): 0.38<0.88((W-D) / W) ０．２２ ×((L-D) / L) ０．２０ ≦1.0 ・・・(i) However, in the above formula, W indicates the distance between the heat source part and the heat source part opposite it, D indicates the diameter of the multiple core sheets when the outer surface is circular when viewed from the stacking direction, or the diameter of the circle circumscribing the outer surface when the outer surface is polygonal when viewed from the stacking direction, and L indicates the total length of the one or more heating elements in the longitudinal direction of the heat source part.

8. An apparatus for manufacturing a laminated core by heating a plurality of core sheets laminated together via an adhesive layer, comprising: a squeeze ring that holds the core sheets while stacking the core sheets in a predetermined stacking direction, and has an outer peripheral surface that is circular or polygonal having octagonal or greater sides when viewed from the stacking direction; four heat source units provided so as to be located on both sides of the squeeze ring in a first direction and on both sides of the squeeze ring in a second direction perpendicular to the first direction, as viewed from the stacking direction; When viewed from the stacking direction, a pair of heat source parts of the four heat source parts are provided to face each other in the first direction and extend in the second direction, and another pair of heat source parts of the four heat source parts are provided to face each other in the second direction and extend in the first direction, Each of the heat source units is provided with one or more heating elements that radiate near-infrared rays, A laminated core manufacturing device, wherein, when viewed from the stacking direction, each of the heat source units is arranged so as to satisfy the following formula (i): 0.38<0.88((W-D) / W) ０．２２ ×((L-D) / L) ０．２０ ≦1.0 ・・・(i) In the above formula, W represents the distance between the heat source part and the heat source part facing it, D represents the diameter of the squeeze ring if the outer peripheral surface is circular when viewed from the stacking direction, or the diameter of the circle circumscribing the outer peripheral surface if the outer peripheral surface is polygonal when viewed from the stacking direction, and L represents the total length of the one or more heating elements in the longitudinal direction of the heat source part.

9. An apparatus for manufacturing a laminated core by heating a plurality of core sheets laminated together via an adhesive layer, comprising: a squeeze ring that holds the core sheets while stacking the core sheets in a predetermined stacking direction and has a rectangular shape when viewed from the stacking direction; When viewed from the stacking direction, a direction perpendicular to one side of the squeeze ring is defined as a first direction, and a direction perpendicular to the first direction is defined as a second direction, and four heat source units are provided so as to be located on both sides of the squeeze ring in the first direction and on both sides of the squeeze ring in the second direction, When viewed from the stacking direction, a pair of heat source parts of the four heat source parts are provided to face each other in the first direction and extend in the second direction, and another pair of heat source parts of the four heat source parts are provided to face each other in the second direction and extend in the first direction, Each of the heat source units is provided with one or more heating elements that radiate near-infrared rays, A laminated core manufacturing device, wherein, when viewed from the stacking direction, each of the heat source units is arranged so as to satisfy the following formula (ii): 0.63<1.03((W-M) / W) －０．１６ ×((L-M) / L) ０．３０ ≦1.0 ・・・(ii) However, in the above formula, W represents the distance between the heat source part and the heat source part facing it, M represents the length of the squeeze ring in a direction perpendicular to the longitudinal direction of the heat source part, and L represents the total length of the one or more heating elements in the longitudinal direction of the heat source part.

10. An apparatus for manufacturing a laminated core by heating a plurality of core sheets laminated together via an adhesive layer, comprising: a rectangular squeeze ring that holds the core sheets while stacking the core sheets in a predetermined stacking direction and has a pair of short sides and a pair of long sides when viewed from the stacking direction; two heat source units provided on the outsides of the pair of short sides of the squeeze ring so as to extend along the pair of short sides, respectively, when viewed from the stacking direction; Each of the heat source units is provided with one or more heating elements that radiate near-infrared rays, A laminated core manufacturing device, wherein, when viewed from the stacking direction, the two heat source units are each positioned so as to satisfy the following formula (iii): 0.24<1.27((W-M) / W) －１３．７ ×((L-N) / L) １４．７ ≦1.0 ・・・(iii) However, in the above formula, W indicates the distance between the two heat source parts, M indicates the length of the long side, L indicates the total length of the one or more heating elements in the longitudinal direction of the heat source part, and N indicates the length of the short side.

11. 11. The laminated core manufacturing device according to claim 7, wherein the heating element is provided in each of the heat source parts so as to extend in the longitudinal direction of the heat source part.

12. 11. The laminated core manufacturing device according to claim 7, wherein a plurality of the heating elements are provided in each heat source section so as to extend in the stacking direction and to be aligned along the longitudinal direction of the heat source section.

13. 11. The laminated core manufacturing device according to claim 7, wherein the near-infrared rays emitted from the heating element are irradiated as parallel or divergent light.

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