[Technical Field of the Invention]
[0001]
The present invention relates to a method of manufacturing a laminated core.
Priority is claimed on Japanese Patent Application No. 2020-104252, filed
June 17, 2020, the content of which is incorporated herein by reference.
[Background Art]
[0002]
A laminated core used in a motor (rotating electrical machine) is
manufactured by punching an electrical steel sheet into a predetermined shape and
laminating the punched steel sheet in a die. Recently, in order to reduce iron loss in
motor products, an electrical steel sheet having a reduced thickness is used for these
products. However, in the electrical steel sheet having a reduced thickness, there is a
problem that does not occur in a method of manufacturing a laminated core in the
related art. For example, the number of times of punching increases. The reason for
this is that, when the sheet thickness of the electrical steel sheet is reduced to half of
that in the related art, the number of times of punching is doubled. In order to secure
productivity equivalent to that in the related art, it is necessary to increase the punching
speed. It is necessary to reduce the sheet thickness of the electrical steel sheet to
narrow a clearance of a punching die, and there is a limit in increasing the punching
speed in order to secure the lifetime of the punching die.
[0003]
Patent Document 1 describes a method of manufacturing a laminated core.
Patent Document 1 describes a technique of bonding two or more electrical steel sheets
- 1 -
and punching the laminate in order to improve productivity. However, in Patent
Document 1, the laminate is heated to completely cure or incompletely cure an
adhesive layer formed between the electrical steel sheets. Therefore, the productivity
cannot be sufficiently improved.
[Prior Art Document]
[Patent Document]
[0004]
[Patent Document 1] Japanese Unexamined Patent Application, First
Publication No. 2005-191033
[Disclosure of the Invention]
[Problems to be Solved by the Invention]
[0005]
The present invention has been made in consideration of the above-described
circumstances, and an object thereof is to provide a method of manufacturing a
laminated core having excellent productivity.
[Means for Solving the Problem]
[0006]
The summary of the present invention is as follows.
(1) According to one aspect of the present invention, there is provided a
method of manufacturing a laminated core by punching electrical steel strips including
an insulation coating to obtain core single sheets and laminating the core single sheets,
the method including:
pressurizing two or more electrical steel strips using a guide roller to
temporarily bond the electrical steel strips immediately before the punching; and
obtaining the core single sheets by performing the punching after inserting the
- 2 -
two or more electrical steel strips after the temporary bonding into a punching die.
(2) In the method of manufacturing a laminated core according to (1), a
surface temperature of the two or more electrical steel strips during the temporary
bonding may be 15ac to 50°C.
(3) In the method of manufacturing a laminated core according to (1) or (2),
an applied pressure during the pressurization by the guide roller may be 2.0 to 10.0
MPa.
(4) In the method of manufacturing a laminated core according to any one of
(1) to (3), after the punching, the core single sheets may be heated to 180°C to 250°C
to mainly bond the core single sheets.
(5) In the method of manufacturing a laminated core according to any one of
(1) to (4), the insulation coating may have adhesiveness.
[Effects ofthe Invention]
[0007]
In the above-described aspect according to the present invention, a method of
manufacturing a laminated core having excellent productivity can be provided.
[Brief Description of the Drawings]
[0008]
FIG. 1 is a cross-sectional view showing a rotating electrical machine
including a laminated core.
FIG. 2 is a side view showing the laminated core.
FIG. 3 is an A-A cross-sectional view of FIG. 2.
FIG. 4 is a plan view showing a material for forming the laminated core.
FIG. 5 is a B-B cross-sectional view of FIG. 4 .
FIG. 6 is an enlarged view showing a C portion of FIG. 5.
- 3 -
FIG. 7 is a side view showing a manufacturing device used for manufacturing
the laminated core.
FIG. 8 is a flowchart showing a method of manufacturing the laminated core
according to the embodiment.
[Embodiments ofthe Invention]
[0009]
Hereinafter, a method of manufacturing a laminated core according to one
embodiment of the present invention will be described with reference to the drawings.
First, a laminated core manufactured using the method of manufacturing a laminated
core according to the embodiment, a rotating electrical machine including the
laminated core, and a material for forming the laminated core will be described. In
the embodiment, an electric motor, specifically an AC motor, more specifically a
synchronous motor, and still more preferably a permanent magnet motor will be
described as an example of the rotating electrical machine. As this electric motor, for
example, an electric vehicle is suitably adopted.
[0010]
(Rotating Electrical Machine 1 0)
As shown in FIG. 1, the rotating electrical machine 10 includes a stator 20, a
rotor 30, a case 50, and a rotating shaft 60. The stator 20 and the rotor 30 are housed
in the case 50. The stator 20 is fixed to the inside of the case 50.
In the embodiment, an inner rotor type where the rotor 30 is positioned inward
in a radial direction of the stator 20 is adopted as the rotating electrical machine 10.
However, an outer rotor type where the rotor 30 is positioned outside the stator 20 may
be adopted as the rotating electrical machine 10. In addition, in the embodiment, the
rotating electrical machine 10 is a 12-pole 18-slot three-phase AC motor. However,
- 4 -
the number of poles, the number of slots, the number of phases, and the like can be
appropriately changed.
For example, when an excitation current having an effective value of 10 A and
a frequency of 100 Hz is applied at each of the phases, the rotating electrical machine
10 can rotate at a rotation speed of 1000 rpm.
[0011]
The stator 20 includes a laminated core for bonding a stator (hereinafter, stator
core) 21 and a winding (not shown).
The stator core 21 includes an annular core back portion 22 and a plurality of
tooth portions 23. Hereinafter, a central axis 0 direction of the stator core 21 (or the
core back portion 22) will be referred to as the axial direction, a radial direction
(direction perpendicular to the central axis 0) of the stator core 21 (or the core back
portion 22) will be referred to as the radial direction, and a circumferential direction
(direction around the central axis 0) of the stator core 21 (or the core back portion 22)
will be referred to as the circumferential direction.
[0012]
The core back portion 22 is formed in a toric shape in a plan view when the
stator 20 is seen from the axial direction.
The plurality of tooth portions 23 protrude inward in the radial direction
(toward the central axis 0 of the core back portion 22 in the radial direction) from an
inner circumference of the core back portion 22. The plurality of tooth portions 23
are disposed at regular angular intervals in the circumferential direction. In the
embodiment, 18 tooth portions 23 are provided at intervals of a central angle of 20
degrees around the central axis 0 . The plurality of tooth portions 23 are formed in
the same shape and the same size. Accordingly, the plurality of tooth portions 23
- 5 -
have the same thickness.
The winding is coiled around the tooth portions 23. The winding may be in
a concentrated winding state or in a distributed winding state.
[0013]
The rotor 30 is disposed inward in the radial direction with respect to the
stator 20 (stator core 21). The rotor 30 includes a rotor core 31 and a plurality of
permanent magnets 32.
The rotor core 31 is formed in an annular (toric) shape that is disposed on the
same axis as the stator 20. In the rotor core 31, the rotating shaft 60 is disposed.
The rotating shaft 60 is fixed to the rotor core 31.
The plurality of permanent magnets 32 are fixed to the rotor core 31. In the
embodiment, one set including two permanent magnets 32 forms one magnetic pole.
Plural sets of permanent magnets 32 are disposed at regular angular intervals in the
circumferential direction. In the embodiment, 12 sets of permanent magnets 32 (24
permanent magnets 32 in total) are provided at intervals of a central angle of 30
degrees around the central axis 0.
[0014]
In the embodiment, an embedded magnet motor is adopted as the permanent
magnet motor. In the rotor core 31, a plurality of through-holes 33 that penetrate the
rotor core 31 in the axial direction are formed. The plurality of through-holes 33 are
provided corresponding to the arrangement of the plurality of permanent magnets 32.
Each of the permanent magnets 32 is fixed to the rotor core 31 in a state where it is
disposed in the corresponding through-hole 33. The fixing of the rotor core 31 to
each of the permanent magnets 32 can be realized, for example, by bonding an outer
surface of the permanent magnet 32 and an inner surface of the through-hole 33 using
- 6 -
an adhesive. As the permanent magnet motor, a surface magnet motor may be
adopted instead of the embedded magnet type.
[0015]
Both of the stator core 21 and the rotor core 31 are the laminated cores. For
example, as shown in FIG. 2, the stator core 21 is formed by laminating a plurality of
core single sheets 40 in a laminating direction.
The lamination thickness (overall length along the central axis 0) of each of
the stator core 21 and the rotor core 31 is, for example, 50.0 mm. The outer diameter
of the stator core 21 is, for example, 250.0 mm. The inner diameter of the stator core
21 is, for example, 165.0 mm. The outer diameter of the rotor core 31 is, for example,
163.0 mm. The inner diameter of the rotor core 31 is, for example, 30.0 mm. These
values are exemplary, and the lamination thickness and the outer diameter or inner
diameter of the stator core 21 and the lamination thickness and the outer diameter or
inner diameter of the rotor core 31 are not limited to only these values. Here, the
inner diameter of the stator core 21 is based on tip end portions of the tooth portions 23
in the stator core 21. That is, the inner diameter of the stator core 21 is the diameter
of an imaginary circle inscribed in the tip end portions of all of the tooth portions 23.
[0016]
Each of the core single sheets 40 that form the stator core 21 and the rotor
core 31 is formed, for example, by punching a material! shown in FIGS. 4 to 6. The
material 1 is a steel sheet (electrical steel sheet) as a base metal of the core single sheet
40. Examples of the material 1 include a strip-shaped steel sheet or a cut sheet.
Although the description of the laminated core is ongoing, the material 1 will
be described below. In the present specification, the strip-shaped steel sheet as the
base metal of the core single sheet 40 will also be referred to as the material 1 or the
- 7 -
electrical steel strip 1. A steel sheet obtained by punching the materiall or the
electrical steel strip 1 in a shape used for the laminated core will also be referred to as
the core single sheet 40.
[0017]
(Material 1)
The material 1 is handled, for example, in a state where it is coiled around a
coillA. In the embodiment, a non-oriented electrical steel sheet is adopted as the
material 1. A non-oriented electrical steel strip of JIS C 2552:2014 is adopted as the
non-oriented electrical steel sheet. However, a grain-oriented electrical steel sheet
may be adopted as the material 1 instead of the non-oriented electrical steel sheet. In
this case, a grain-oriented electrical steel strip of JIS C 2553:2019 is adopted as the
grain-oriented electrical steel sheet. In addition, a non-oriented thin electrical steel
strip and a grain-oriented thin electrical steel strip of JIS C 2558:2015 can be adopted.
[0018]
Upper and lower limits of an average sheet thickness tO of the material I are
set, for example as follows in consideration that the material 1 is used as the core
single sheet 40.
As the sheet thickness of the material 1 decreases, the manufacturing cost of
the material 1 increases. Therefore, in consideration of the manufacturing cost, the
lower limit of the average sheet thickness tO of the material I is 0.10 mm, preferably
0.15 mm, and more preferably 0.18 mm.
On the other hand, when the thickness of the material 1 is excessively large,
the manufacturing cost is improved. When the material 1 is used as the core single
sheet 40, the eddy-current loss increases, and core iron loss deteriorates. Therefore,
in consideration of the core iron loss and the manufacturing cost, the upper limit of the
- 8 -
average sheet thickness tO of the material! is 0.65 mm, preferably 0.35 mm, and more
preferably 0.30 mm.
The average sheet thickness tO of the material! that satisfies the abovedescribed
range is, for example, 0.20 mm.
[0019]
The average sheet thickness tO of the material! includes not only the
thickness of a base steel sheet 2 described but also the thickness of an insulation
coating 3. In addition, a method of measuring the average sheet thickness tO of the
material 1 is, for example, the following measurement method. For example, when
the material 1 is coiled in a shape of the coil lA, at least a part of the material! is
uncoiled in a flat shape. In the material 1 that is uncoiled in a flat shape, a
predetermined position of the material 1 in a longitudinal direction (for example, a
position distant from an end edge of the material 1 in the longitudinal direction by a
length corresponding to 10% of the overall length of the material 1) is selected. At
this selected position, the material 1 is divided into five regions in a width direction
thereof. At four portions as boundaries of the five regions, the sheet thickness of the
material 1 is measured. The average value of the sheet thicknesses at the four
portions can be obtained as the average sheet thickness tO of the material 1.
[0020]
Of course, the upper and lower limits of the average sheet thickness tO of the
material 1 can also be adopted as upper and lower limits of the average sheet thickness
tO as the core single sheet 40. A method of measuring the average sheet thickness tO
of the core single sheet 40 is, for example, the following measurement method. For
example, the lamination thickness of the laminated core is measured at four portions at
regular intervals in the circumferential direction (that is, at intervals of 90 degrees
- 9 -
around the central axis 0). Each of the measured lamination thicknesses at the four
portions is divided by the number of the laminated core single sheets 40 to calculate
the sheet thickness per sheet. The average value of the sheet thicknesses at the four
portions can be obtained as the average sheet thickness tO of the core single sheet 40.
[0021]
As shown in FIGS. 5 and 6, the material I includes the base steel sheet 2 and
the insulation coating 3. In the material I, both surfaces of the strip- shaped base steel
sheet 2 are covered with the insulation coating 3. In the embodiment, most of the
material 1 is formed of the base steel sheet 2, and the insulation coating 3 that is
thinner than the base steel sheet 2 is formed on the surface of the base steel sheet 2.
[0022]
The chemical composition of the base steel sheet 2 includes 2.5% to 4.5% of
Si by mass% as represented by mass% below. By adjusting the chemical composition
to be in this range, the yield strength of the material 1 (core single sheet 40) can be set
to be, for example, 380 to 540 MPa.
[0023]
Si: 2.5% to 4.5%
Al: 0.001% to 3.0%
Mn: 0.05% to 5.0%
Remainder: Fe and Impurities
[0024]
When the material 1 is used as the core single sheet 40, the insulation coating
3 exhibits insulation properties between the core single sheets 40 adj acent to each other
in the laminating direction. In addition, in the embodiment, the insulation coating 3
has adhesiveness such that the cor e single sheets 40 adjacent to each other in the
- 10 -
laminating direction are bonded to each other. The insulation coating 3 may have a
single layer configuration or a multilayer configuration. More specifically, for
example, the insulation coating 3 may have a single layer configuration having
insulation properties and adhesiveness or may have a multilayer configuration that
includes an underlayer insulation coating having excellent insulation properties and an
upper layer insulation coating having excellent adhesiveness.
[0025]
In the embodiment, the insulation coating 3 covers the entire surface of both
surfaces of the base steel sheet 2 without a gap. However, within a range where the
insulation properties or the adhesiveness are secured, a part of the insulation coating 3
does not need to cover both surfaces of the base steel sheet 2 without a gap. In other
words, a part of the insulation coating 3 may be intermittently provided on the surfaces
of the base steel sheet 2. However, in order to secure the insulation properties, both
surfaces of the base steel sheet 2 need to be covered with the insulation coating 3 such
that the entire surface is not exposed. Specifically, when the insulation coating 3 has
the single layer configuration having not only insulation properties but also
adhesiveness without including the underlayer insulation coating having excellent
insulation properties, the insulation coating 3 needs to be formed over the entire
surface of the base steel sheet 2 without a gap. On the other hand, when the
insulation coating 3 has the multilayer configuration that includes an underlayer
insulation coating having excellent insulation properties and an upper layer insulation
coating having excellent adhesiveness, both of the underlayer insulation coating and
the upper layer insulation coating are formed on the entire surface of the base steel
sheet 2 without a gap. In addition, even if the underlayer insulation coating is formed
on the entire surface of the base steel sheet without a gap and the upper layer insulation
- 11 -
coating is intermittently provided, both of insulation properties and adhesiveness can
be achieved at the same time.
[0026]
A coating composition for forming the underlayer insulation coating is not
particularly limited. For example, a general treatment agent such as a chromic acidcontaining
treatment agent or a phosphate-containing treatment can be used.
[0027]
The insulation coating having adhesiveness is formed by coating the base
steel sheet with a coating composition for an electrical steel sheet described below.
The insulation coating having adhesiveness is the insulation coating that has the single
layer configuration having not only insulation properties but also adhesiveness or the
upper layer insulation coating that is formed on the underlayer insulation coating.
The insulation coating having adhesiveness is in an uncured state or a semi-cured state
(B stage) before heating pressurization for manufacturing the laminated core, and
exhibits adhesiveness when the curing reaction progresses by heating during the
heating pressurization.
[0028]
A typical insulating film has insulation properties but does not have
adhesiveness. As described above the insulating film according to the embodiment is
largely different from the typical insulation coating and an adhesive layer formed of an
adhesive in that it has adhesiveness and insulation properties.
[0029]
In addition, as a method of bonding the base steel sheets 2 on which the
insulation coating not having adhesiveness is formed, a method of bonding the base
steel sheets 2 using an adhesive formed of a thermosetting resin having adhesiveness
- 12 -
can be used. In the core single sheet 40 that is manufactured by bonding the base
steel sheets 2 using this method, two or more base steel sheets 2 are bonded before
punching. Therefore, although the base steel sheets 2 in the core single sheet 40 are
bonded, the two or more core single sheets 40 in the bonded state are not bonded to
each other. Therefore, a process of separately applying an adhesive to any one of
front and rear surfaces of the core single sheets 40 is necessary, and the productivity
deteriorates. When an adhesive is further used for the insulation coating having
adhesiveness and insulation properties, the space factor decreases, and thus a laminated
core having poor magnetic characteristics is obtained.
[0030]
The coating composition for an electrical steel sheet is not particularly limited,
and examples thereof include a composition including an epoxy resin and an epoxy
resin curing agent. That is, examples of the insulation coating having adhesiveness
include a film including an epoxy resin and an epoxy resin curing agent.
[0031]
As the epoxy resin, a general epoxy resin can be used. Specifically, any
epoxy resin having two or more epoxy groups in one molecule can be u sed without any
particular limitation. Examples of the epoxy resin include a bisphenol A epoxy resin,
a bisphenol F epoxy resin, a phenol novolac epoxy resin, a cresol novolac epoxy resin,
an alicyclic epoxy resin, a glycidyl ester epoxy resin, a glycidylamine epoxy r esin, a
hydantoin epoxy resin, an isocyanurate epoxy resin, an acrylic acid-modified epoxy
resin (epoxy acrylate), a phosphorus-containing epoxy resin, and a halide (brominated
epoxy resin) or a h ydrogenated product thereof. The epoxy resins may be used alone
or in combination of two or more kinds.
[0032]
- 13 -
The coating composition for an electrical steel sheet may include an acrylic
resm.
The acrylic resin is not particularly limited. Examples of a monomer used
for the acrylic resin include an unsaturated carboxylic acid such as acrylic acid or
methacrylic acid and a (meth)acrylate such as methyl (meth)acrylate, ethyl
(meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, cyclohexyl
(meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, or
hydroxypropyl (meth)acrylate. The (meth)acrylate refers acrylate or methacrylate.
The acrylic resins may be used alone or in combination of two or more kinds.
[0033]
The acrylic resin may include a constituent unit derived from another
monomer other than the acrylic monomer. Examples of the other monomer include
ethylene, propylene, and styrene. The other monomers may be u sed alone or in
combination of two or more kinds.
[0034]
When an acrylic resin is used, the other monomer is used for an acrylic
modified epoxy resin in which an acrylic resin is grafted with an epoxy resin. The
coating composition for an electrical steel sheet may include the other monomer as a
monomer for forming an acrylic resin.
[0035]
As the epoxy resin curing agent, a thermally curable curing agent having
latency can be u sed, and examples thereof include an aromatic polyamine, an acid
anhydride, a phenol curing agent, a dicyandiamide, a boron trifluoride-amine complex,
and an organic acid hydrazide. Examples of the aromatic polyamine include metaphenylenediamine,
diaminodiphenyl methane, and diaminodiphenyl sulfone.
- 14 -
Examples of the phenol curing agent include a phenol novolac resin, a cresol novolac
resin, a bisphenol novolac resin, a triazine-modified phenol novolac resin, and a phenol
resole resin. In particular, as the epoxy resin curing agent, a phenol curing agent is
preferable, and a phenol resole resin is more preferable. The epoxy resin curing
agents may be used alone or in combination of two or more kinds.
[0036]
The content of the epoxy resin curing agent in the coating composition for an
electrical steel sheet is preferably 5 to 35 parts by mass and more preferably 10 to 30
parts by mass with respect to 100 parts by mass of the epoxy resin.
[0037]
In the coating composition for an electrical steel sheet , an additive su ch as a
curing accelerator (curing catalyst), an emulsifier, or an antifoaming agent may be
mixed. The additives may be used alone or in combination of two or more kinds.
[0038]
Upper and lower limits of an average thickness tl of the insulation coating 3
are set, for example as follows in consideration that the material 1 is used as the core
single sheet 40. When the material 1 is used as the core single sheet 40, the average
thickness t1 of the insulation coating 3 (the thickness per single surface of the core
single sheet 40 (material!)) is adjusted such that the insulation properties and the
adhesiveness of the laminated core single sheets 40 can be secured.
[0039]
In the insulation coating 3 having the single layer configuration, the average
thickness t1 of the insulation coating 3 (the thickness per single surface of the core
single sheet 40 (material!)) can be, for example, 1.5 11m or more and 8.0 11m or less.
In the insulation coating 3 having the multilayer configuration, the average
- 15 -
thickness of the underlayer insulation coating can be, for example, 0.3 11m or more and
1.2 11m or less and is preferably 0.7 11m or more and 0.9 11m or less. The average
thickness of the upper layer insulation coating can be, for example, 1.5 11m or more and
8.0 11m or less.
As a method of measuring the average thickness tl of the insulation coating 3
in the material!, the average thickness tl can be obtained by obtaining the thicknesses
of the insulation coating 3 at a plurality of positions and obtaining the average value of
the thicknesses as in the average sheet thickness tO of the material 1.
[0040]
Of course, the upper and lower limits of the average thickness tl of the
insulation coating 3 in the material 1 can also be adopted as upper and lower limits of
the average thickness tl of the insulation coating 3 as the core single sheet 40. A
method of measuring the average thickness tl of the insulation coating 3 in the core
single sheet 40 is, for example, the following measurement method. For example,
among the plurality of core single sheets 40 forming the laminated core, the core single
sheet 40 that is positioned on the outermost side in the laminating direction (the core
single sheet 40 having a surface that is exposed in the laminating direction) is selected.
On the surface of the selected core single sheet 40, a predetermined position in the
radial direction (for example, a position at the exact center of an inner circumference
and an outer circumference of the core single sheet 40) is selected. At the selected
position, the thickness of the insulation coating 3 in the core single sheet 40 is
measured at four portions at regular intervals in the circumferential direction (that is, at
intervals of 90 degrees around the central axis 0). The average value of the measured
thicknesses at the four portions can be obtained as the average thickness t 1 of the
insulation coating 3.
- 16 -
The reason for measuring the average thickness tl of the insulation coating 3
in the core single sheet 40 that is positioned on the outermost side in the laminating
direction is that the insulation coating 3 is formed such that the thickness of the
insulation coating 3 does not substantially change depending on lamination positions in
the laminating direction of the core single sheets 40.
[0041]
By punching the materiall, the core single sheet 40 is manufactured, and the
laminated core (stator core 21 or the rotor core 31) is manufactured u sing the core
single sheet 40.
[0042]
(Laminating Method of Laminated core)
Hereinafter, the laminated core will be described again. A plurality of core
single sheets 40 forming the stator core 21 are laminated through the insulation coating
3 as shown in FIG. 3.
[0043]
The core single sheets 40 adjacent to each other in the laminating direction are
bonded over the entire surface using the insulation coating 3. In other words, a
surface (hereinafter, referred to as "first surface") of the core single sheet 40 facing the
laminating direction is a bonding region over the entire surface. In this case, the core
single sheets 40 adjacent to each other in the laminating direction do not need to be
bonded over the entire surface. In other words, on the first surface of the core single
sheet 40, a bonding region 41a and a non-bonding region (not shown) may be mixed.
[0044]
In the embodiment, a plurality of core single sheets forming the rotor core 31
are fixed to each other using a fastener 42 (dowel) shown in FIG. 1. However, a
- 17 -
plurality of core single sheets forming the rotor core 31 may also have a laminate
structure in which they are fixed using the insulation coating 3 as in the stator core 21.
In addition, the laminated core such as the stator core 21 or the rotor core 31
may be formed by so-called rotation lamination.
[0045]
(Method of Manufacturing Laminated Core)
Hereinafter, a method of manufacturing a laminated core according to one
embodiment of the present invention will be described with reference to FIGS. 7 and 8.
FIG 7 is a side view showing a manufacturing device used for manufacturing the
laminated core. FIG 8 is a flowchart showing the method of manufacturing the
laminated core according to the embodiment. Hereinafter, in the description of the
manufacturing method, first, a manufacturing device 100 for manufacturing the
laminated core (hereinafter, simply referred to as "manufacturing device 1 00") will be
described.
[0046]
In the manufacturing device 100, two materials 1 are temporarily bonded
using a guide roller 2A while feeding the materials 1 from two coils 1A (hoops) to the
upstream side (the right side in FIG 7) in a conveyance direction. Next, while further
feeding the two materials 1 that are temporarily bonded to the upstream side in the
conveyance direction, the materials 1 are punched multiple times using a die disposed
at each of stages, and thus are gradually formed in a shape of the core single sheet 40.
The punched core single sheets 40 are laminated, are conveyed to a heating device (not
shown), and are pressurized while being heated. As a result, the core single sheets 40
adjacent to each other in the laminating direction are bonded using the insulation
coating 3 (that is, a portion of the insulation coating 3 that is positioned in the bonding
- 18 -
region 4la is caused to exhibit adhesiveness), and thus main bonding is completed.
[0047]
In FIG. 7, the manufacturing device 100 includes the two coils lA. However,
the manufacturing device 100 may include three or more coils lA.
In addition, the manufacturing device 100 includes plural stages of punching
stations llO. The punching stations llO may be two stages or may be three or more
stages. The punching station ll 0 on each of the stages includes: a female die lll that
is disposed below the material 1; and a male die 112 that is disposed above the material
1. The plural stages of punching stations llO will also be collectively referred to as
"punching die".
[0048]
The method of manufacturing the laminated core according to the
embodiment is a method of manufacturing a laminated core by punching electrical
steel strips including an insulation coating to obtain core single sheets and laminating
the core single sheets, the method including: pressurizing two or more electrical steel
strips using a guide roller to temporarily bond the electrical steel strips immediately
before the punching; and obtaining the core single sheets by performing the punching
after inserting the two or more electrical steel strips after the temporary bonding into a
punching die.
Hereinafter, the details will be described.
[0049]
(Temporary Bonding by Pressurization)
First, two or more materials 1 (electrical steel strips) are pressurized using the
guide roller 2A to temporarily bond the materials 1 immediately before the punching
by the punching die. The materials 1 that are temporarily bonded include the
- 19 -
insulation coating 3 on both surfaces thereof. It is preferable that the insulation
coating 3 is formed such that the average thickness t1 is in the above-described range.
In addition, as described above, the insulation coating 3 has insulation properties and
adhesiveness.
The guide roller 2A is a roller for conveying the materials 1 to the punching
die and is disposed on the upstream side (the left side in FIG 7) in the conveyance
direction of the punching die. In addition, "immediately before the punching"
represents that any treatment is not performed before the punching after the temporary
bonding.
[0050]
In the embodiment, the temporary bonding represents that the two or more
materials 1 before punching are pressurized and bonded without being heated. "After
the temporary bonding" represents a state where the materials are temporarily bonded.
The two or more materials 1 that are temporarily bonded are heated as described below
to mainly bond the materials 1 after the punching.
In the embodiment, when the two or more materials 1 are bonded, an adhesive
is not used. When the materials are bonded using an adhesive instead of the
temporary bonding by the pressurization, the space factor decreases. Therefore, a
laminated core having poor magnetic characteristics is obtained. Therefore, it is not
desirable to use an adhesive.
[0051]
As described above, in the embodiment, the two or more materials 1 do not
need to be heated during the temporary bonding. In order to heat the materials 1
during the temporary bonding, a heating device is necessary, and a long period of time
is required for heating the materials 1. Therefore, the productivity significantly
- 20 -
deteriorates. The surface temperature of the two or more materials 1 during the
temporary bonding only has to be a normal temperature and may be, for example,
15ac to 5oac. The surface temperature of the materials 1 can be obtained by
measuring the temperatures of center portions of the two or more materials 1 in the
width direction during the temporary bonding using an infrared radiation-type
thermometer and calculating the average value of the measured temperatures.
[0052]
The applied pressure by the guide roller 2A during the temporary bonding is
preferably 2.0 to 10.0 MPa. By adjusting the applied pressure to be in the abovedescribed
range, the two or more materials 1 can be temporarily bonded with reliability.