JP2017222911A - Iron core, cold re-rolled steel sheet, cold re-rolled steel sheet manufacturing method, and iron core manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an iron core which has excellent magnetic properties and dimensional accuracy, and whose space factor decrease is suppressed.SOLUTION: An iron core composed of a steel sheet in which an area ratio of a crystal grain having a crystal orientation of {100}<001>(±30°) is 50% or more, and an area ratio of a crystal grain having a crystal orientation of {110}<110>(±30°) is 20% or more.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an iron core, a re-cold rolled steel sheet, a method for producing a re-cold rolled steel sheet, and a method for producing the iron core.

In recent years, with increasing demand for prevention of global warming and energy saving, unidirectional electrical steel sheets, which are core materials, also have high iron loss and high magnetic flux density in a low excitation field. Magnetic properties are required.
In order to realize such magnetic characteristics, it is effective to integrate the <001> axis, which is the easy axis of iron, in the direction of the magnetic field used.

A general grain-oriented electrical steel sheet has a {110} <001> orientation (Goss orientation), that is, a texture in which the {110} plane is parallel to the steel sheet and the <001> axis converges in the rolling direction. .
Thereby, the unidirectional electrical steel sheet can exhibit extremely high magnetic properties in the rolling direction. For this reason, the unidirectional electrical steel sheet is suitable for applications in which magnetic flux flows only in the rolling direction, such as a wound iron core, and is used as a useful magnetic material.

  On the other hand, in recent years, there has been a demand for a bi-directional electrical steel sheet suitable for applications that are excellent not only in one direction but also in magnetic characteristics in a direction perpendicular thereto. The bi-directional electrical steel sheet has a {100} <001> (so-called cube orientation) texture. In the bi-directional electrical steel sheet, the <001> axis is oriented in both the rolling direction in the steel sheet surface and the direction perpendicular to the rolling direction (direction orthogonal to the rolling direction), and two directions orthogonal to the steel sheet surface. It is an electrical steel sheet that exhibits excellent magnetic properties.

It is known that a bi-directional electrical steel sheet is obtained by the manufacturing method disclosed in Patent Documents 1 to 3, for example.
For example, it is known that a bi-directional electrical steel sheet can be obtained by a method by cross rolling (Patent Document 1). In this method, after the silicon steel material is cold-rolled in one direction, cold rolling is further performed in a direction intersecting with the cold-rolling direction, and then short-time annealing and about 900 ° C. to 1300 ° C. are performed as finish annealing. This is a method of performing high temperature annealing.
However, performing cross rolling before finish annealing requires rolling in the width direction in the state of a coil in commercial production, and a special device is required.

Moreover, as another manufacturing method for obtaining a bidirectional magnetic steel sheet, a manufacturing method (Patent Document 2) using high-temperature annealing that causes de-C or de-C and de-Mn has been proposed.
However, this method requires annealing in a vacuum, and a special device is still required.

Furthermore, as a manufacturing method for obtaining a bi-directional electrical steel sheet having a small crystal grain size, the directional electrical steel sheet after secondary recrystallization is carburized, annealed at 100 ° C. to 400 ° C., and 50% or more in the rolling direction. A method of performing recrystallization annealing after rolling at a rolling reduction (Patent Document 3) is known.
However, in this method, cementite precipitates due to carburization and the iron loss is inferior.

Japanese Patent Publication No. 35-002657 Japanese Patent Laid-Open No. 07-173542 Japanese Patent No. 4826312

  By the way, since the bi-directional electrical steel sheet is an electrical steel sheet that exhibits excellent magnetic properties in two directions perpendicular to the plane of the steel plate, it may be applied to applications that require excellent magnetic properties in both orthogonal directions. Has been. As such an application, for example, it has been proposed to apply as an iron core material in which the direction of magnetic flux flow is orthogonal between the tooth portion and the yoke portion.

  However, the bi-directional electrical steel sheets disclosed in Patent Documents 1 to 3 have too high a degree of integration of {100} <001> orientations that are generated. For this reason, when these conventional bi-directional electrical steel sheets are applied as the iron core of a motor, the problem that the dimensional accuracy at the time of punching is low, and the problem that the plate thickness is reduced at the time of bending and the space factor is reduced. was there. When the bi-directional electrical steel sheet is used as the iron core of a motor, stamping is mainly performed. If the dimensional accuracy at the time of punching is low, the motor efficiency decreases. Further, when the motor iron core is a spirally wound iron core, bending may be performed. If the {100} <001> orientation of the bi-directional electrical steel sheet is large, the plate thickness is reduced during bending, and the space factor tends to decrease. A decrease in the space factor leads to a decrease in motor efficiency.

  Thus, when using a conventional bi-directional electrical steel sheet as an iron core, it not only has excellent magnetic properties in two orthogonal directions, but also has excellent dimensional accuracy, and a decrease in space factor was suppressed. In fact, the technology to obtain the iron core has not been established.

  The present invention has been made in view of the above, and provides an iron core having excellent magnetic properties, excellent dimensional accuracy, and suppressing a decrease in the space factor. The present invention also provides a re-cold rolled steel sheet suitable for producing an iron core having these characteristics and a method for producing the same. Furthermore, the manufacturing method of the iron core which has the said characteristic is provided.

In order to solve the above-mentioned problems, the present inventors have conducted intensive research from the viewpoint of making an iron core having excellent magnetic characteristics in two orthogonal directions with excellent dimensional accuracy and suppressing a decrease in the space factor. Repeated.
As a result, the inventors of the present invention have an area ratio of 50% or more of crystal grains having a crystal orientation within ± 30 degrees from {100} <001> that is the main orientation, and the slip plane of the crystal that is the secondary orientation is By having an iron core made of a steel sheet having a texture with an area ratio of crystal grains having a crystal orientation within ± 30 degrees from {110} <110> parallel to the plate thickness, it has excellent magnetic properties. At the same time, it was found that the dimensional accuracy was excellent and the decrease in the space factor was suppressed.

  The present invention has been made based on the above findings, and the gist thereof is as follows.

<1> The area ratio occupied by crystal grains of {100} <001> (± 30 °) is 50% or more, and the area occupied by crystal grains of {110} <110> (± 30 °) crystal orientation An iron core made of a steel sheet with a ratio of 20% or more.
<2> The iron core according to <1>, wherein the steel sheet has an average crystal grain size of 350 μm or less.
<3> The steel sheet is mass%,
C: 0.0100% or less,
Si: 2.00% to 4.00%,
Mn: 0.5% or less,
Sb: 0.2% or less,
Sn: 0.2% or less,
Ni: 0.5% or less,
Cu: 0.5% or less,
Cr: 0.5% or less,
P: 0.3% or less,
And Al: Iron core as described in <1> or <2> which contains 0.5% or less and contains Fe and an impurity element as a remainder.

<4> {110} <110> (± 30 °) A re-cold rolled steel sheet in which the area ratio occupied by crystal grains having a crystal orientation is 85% or more and the number of shear bands is 30 pieces / mm or more.
<5> By mass%
C: 0.0100% or less,
Si: 2.00% to 4.00%,
Mn: 0.5% or less,
Sb: 0.2% or less,
Sn: 0.2% or less,
Ni: 0.5% or less,
Cu: 0.5% or less,
Cr: 0.5% or less,
P: 0.3% or less,
And Al: The re-cold-rolled steel sheet as described in <4> containing 0.5% or less and containing Fe and an impurity element as a remainder.

<6> Cold rolling so that the reduction ratio is 20% to 50% in a direction orthogonal to the rolling direction of the unidirectional electrical steel sheet having crystal grains accumulated in the {110} <001> orientation. <4> or <5> The manufacturing method of the re-cold-rolled steel plate which has a process of obtaining the re-cold-rolled steel plate as described in <5>.

<7> An iron core in which the re-cold rolled steel sheets according to <4> or <5> are laminated.

<8> Cold rolling so that the rolling reduction is 20% to 50% in a direction orthogonal to the rolling direction of the unidirectional electrical steel sheet having crystal grains accumulated in the {110} <001> orientation, <4> or <5> obtaining the re-cold rolled steel sheet according to
Punching the re-cold rolled steel sheet to obtain a punched member;
A step of laminating and integrating the punched members and annealing in a temperature range of 700 ° C. or higher;
The manufacturing method of the iron core of any one of <1>-<3> which has these.
<9> The method for manufacturing an iron core according to <8>, wherein the temperature range is 700 ° C to 1000 ° C.

<10> Cold rolling so that the reduction ratio is 20% to 50% in a direction orthogonal to the rolling direction of the unidirectional electrical steel sheet having crystal grains accumulated in the {110} <001> orientation, <4> or <5> obtaining the re-cold rolled steel sheet according to
Punching the re-cold rolled steel sheet to obtain a punched member;
The method for producing an iron core according to <7>, further comprising a step of stacking and integrating the punched members.
<11> The method for manufacturing an iron core according to <10>, further including a step of annealing in a temperature range of 700 ° C. to 1000 ° C. after the step of stacking and integrating.

<12> The area ratio occupied by crystal grains having a crystal orientation of {100} <001> (± 30 °) is 50% or more, and the crystal grains having a crystal orientation of {110} <110> (± 30 °) Punching a bi-directional electrical steel sheet having an area ratio of 20% or more, and obtaining a punched member;
A step of stacking and integrating the punched members;
The manufacturing method of the iron core of any one of <1>-<3> which has these.

  ADVANTAGE OF THE INVENTION According to this invention, it has the outstanding magnetic characteristic, Furthermore, it can provide the iron core which was excellent in dimensional accuracy, and the fall of the space factor was suppressed. Moreover, the re-cold-rolled steel plate suitable for manufacturing the iron core which has these characteristics, and its manufacturing method can be provided. Furthermore, the manufacturing method of the iron core which has the said characteristic can be provided.

It is a schematic diagram which shows the (001) pole figure of the steel plate used for the iron core of this invention. It is a schematic diagram which shows the (001) pole figure of the conventional bi-directional electrical steel sheet. It is a (001) pole figure of the steel plate used for the iron core in the example of the present invention. It is a schematic diagram showing an example of the iron core of this invention. It is a schematic diagram showing another example of the iron core of this invention.

Hereinafter, the present invention will be described in detail.
In addition, in this specification, the numerical range represented using "to" means the range which includes the numerical value described before and behind "to" as a lower limit and an upper limit.

  In the iron core of the present invention, the area ratio occupied by crystal grains of {100} <001> (± 30 °) is 50% or more, and the crystal grains of {110} <110> (± 30 °) crystal orientation It consists of a steel plate with an area ratio of 20% or more. In other words, the steel sheet constituting the iron core (the steel sheet constituting the iron core in the state of the iron core) has an area ratio occupied by crystal grains of {100} <001> (± 30 °) in a crystal orientation of 50% or more. Yes, it has crystal grains in which the area ratio of crystal grains of {110} <110> (± 30 °) crystal orientation is 20% or more.

In the steel sheet constituting the iron core of the present invention, the average crystal grain size of the steel sheet constituting the iron core is preferably 350 μm or less, preferably 300 μm or less, in terms of reducing high-frequency iron loss of 200 Hz or more, preferably 150 μm. More preferably, it is as follows.
On the other hand, the lower limit of the average crystal grain size is not particularly limited, but if the average crystal grain size is too small, the magnetic properties will be lowered, so it is preferable to set it to 20 μm or more.

The measuring method of the average crystal grain size of the steel sheet constituting the iron core is as follows.
The test piece is cut so that the plate thickness cross section can be observed, and the grain boundary is corroded by the nital etching so as to be expressed. Thereafter, the crystal grain size of 100 or more crystal grains is measured by a line segment method to determine the average crystal grain size.

The steel sheet constituting the iron core may have the following chemical composition. For example, in mass%, C: 0.0100% or less, Si: 2.00% to 4.00%, Mn: 0.5% or less, Sb: 0.2% or less, Sn: 0.2% or less Ni: 0.5% or less, Cu: 0.5% or less, Cr: 0.5% or less, P: 0.3% or less, and Al: 0.5% or less, and the balance Fe And an impurity element.
In the present specification, an impurity refers to a component contained in a raw material or a component mixed in a manufacturing process and not intentionally included in a steel plate.

Next, the steel plate used for the iron core of the present invention will be described.
As a suitable steel plate used for the iron core of the present invention, the area ratio of crystal grains having a crystal orientation of {100} <001> (± 30 °) is 50% or more, and {110} <110> (± 30 There is a bi-directional electrical steel sheet having a texture in which the area ratio of crystal grains having a crystal orientation of 20) is 20% or more.
Note that {100} <001> (± 30 °) represents within ± 30 degrees from {100} <001>, and {110} <110> (± 30 °) represents {110} <110> to ± Represents within 30 degrees.
First, regarding the crystal grains having a crystal orientation within ± 30 degrees from {100} <001> and the crystal grains having a crystal orientation within ± 30 degrees from {110} <110> of the steel sheet used in the iron core of the present invention, This will be described with reference to the drawings.

  FIG. 1 is a schematic diagram showing an example of a (001) pole figure of a steel plate used for the iron core of the present invention. The steel plate used for the iron core of the present invention has, for example, a crystal orientation 1 (hereinafter referred to as “{100”) of {100} <001> (± 30 °) as the main orientation, as shown in the (001) pole figure shown in FIG. } <Referred to as <001> near azimuth 1>) and crystal orientation 2 of the {110} <110> (± 30 °) which is the sub-azimuth (hereinafter referred to as “near {110} <110>”) (Referred to as “azimuth 2”).

  In the steel sheet used for the iron core of the present invention, the crystal grains of {100} <001> vicinity orientation 1 are 50% or more in terms of the area ratio to the total crystal grains, and the crystals of {110} <110> vicinity orientation 2 The grains have a crystal orientation that is 20% or more in terms of the area ratio with respect to all crystal grains. The steel plate used for the iron core of the present invention has one or more visual fields having such crystal orientation when the thickness center layer is observed.

On the other hand, FIG. 2 is a schematic diagram showing a (001) pole figure of a conventional bi-directional electrical steel sheet. As shown in the (001) pole figure shown in FIG. 2, the conventional bi-directional electrical steel sheet has crystal grains in the {100} <001> neighborhood orientation 1, but in the {110} <110> neighborhood orientation. Does not have crystal grains.
Note that the conventional bi-directional electrical steel sheet shown in FIG. 2 is not subjected to strain relief annealing.

  Thus, the steel sheet used for the iron core of the present invention has crystal orientations in both the {100} <001> neighborhood orientation 1 which is the main orientation and the {110} <110> neighborhood orientation 2 which is the sub orientation. In that respect, the conventional bi-directional electrical steel sheet is different.

Here, the area ratio occupied by the crystal grains of the crystal orientation of {100} <001> (± 30 °) and the crystal orientation of {110} <110> (± 30 °) of the steel sheet used for the iron core of the present invention. A method for measuring the area ratio occupied by crystal grains will be described.
In the following description, the area ratio occupied by crystal grains having a crystal orientation of {100} <001> (± 30 °) and the area occupied by crystal grains having a crystal orientation of {110} <110> (± 30 °) The ratio may be referred to as “area ratio of crystal grains of {100} <001> (± 30 °)” and “area ratio of crystal grains of {110} <110> (± 30 °)”, respectively. .

These area ratios are obtained by the following method.
The crystal orientation of the steel sheet used for the iron core of the present invention is observed using an electron beam backscatter diffraction method (EBSD). In {} of the crystal orientation, the Miller index in the normal direction of the rolling surface is shown, and in <>, the direction parallel to the rolling direction in cold rolling before secondary recrystallization is shown by the Miller index.

The details of the EBSD measurement conditions are as follows.
・ Measurement device: Scanning electron microscope (SEM-EBSD) with electron beam backscatter diffraction device
(SEM model number "JSM-6400" (manufactured by JEOL))
・ Step interval: 10μm
・ Magnification: 100 times ・ Measurement object: Center layer of rolled surface of steel sheet ・ Measurement area: 7500 μm × 7500 μm
-Number of crystal grains measured: 1000

  For all crystal grains measured under the above measurement conditions, all crystal grains are {100} <001> (± 30 °) and {110} <110> (± 30 °). The area ratio to is obtained. The area ratio is expressed as an average value.

In terms of particularly excellent magnetic properties of the iron core, the area ratio of crystal grains of {100} <001> (± 30 °) is preferably 50% or more, and more preferably 70% or more. The upper limit is not particularly limited, but is preferably 80% or less from the viewpoint of suppressing the decrease in the dimensional accuracy of the iron core and the space factor.
Further, in terms of the magnetic properties and dimensional accuracy of the iron core, and the suppression of the decrease in the space factor, the steel sheet used for the iron core has an area ratio of crystal grains of {110} <110> (± 30 °) of 20%. It is preferable that it is above, and it is more preferable that it is 30% or more. The upper limit is preferably 49% or less in terms of magnetic properties.

  In the iron core of the present invention, the steel sheet used in the iron core has the above-described configuration, so that the dimensional accuracy is particularly excellent and the reduction in the space factor is suppressed. The reason for this is not clear, but is presumed as follows.

The present inventors consider that the steel sheet used for the iron core has {110} <110> crystal grains to improve the dimensional accuracy. When a steel sheet for obtaining an iron core is punched (for example, circular), if the steel sheet has only {100} <001> crystal grains, the processing anisotropy of the steel sheet is strong, so that the dimensional accuracy of the iron core is difficult to be obtained. However, it is considered that the dimensional accuracy is improved when the steel plate for obtaining the iron core has {110} <110>.
Moreover, the iron core of the present invention has a high r value ((width reduction amount) / (thickness reduction amount) at the time of tensile processing) of the steel sheet for obtaining the iron core in that the decrease in the space factor is suppressed. The present inventors believe that this is due to this. It is known that the r value of {100} <001> is lower than the r value of {110} <110>. A steel plate for obtaining an iron core has {110} <110> crystal grains, and thus has an r value higher than that of a conventional bi-directional electrical steel plate. That is, it is considered that the steel plate having {110} <110> crystal grains is less likely to reduce the thickness at the time of bending. Thereby, the fall of the space factor of an iron core is suppressed.
In addition, it is described in Japanese Patent No. 3631523 that {110} <110> oriented grains are suitable for a bending process such as a spiral like a spirally wound iron core.

  In the steel sheet used for the iron core of the present invention, the area ratio occupied by crystal grains of {100} <001> (± 30 °) is 50% or more, and {110} <110> (± 30 °). The area ratio of crystal grains in the crystal orientation may be 20% or more, and the chemical composition is not particularly limited. The chemical composition of the steel sheet is, for example, mass%, C: 0.0030% or less, Si: 2.00% or more and 4.00% or less, Mn: 0.5% or less, Sb: 0.2% or less, Sn : 0.2% or less, Ni: 0.5% or less, Cu: 0.5% or less, Cr: 0.5% or less, P: 0.3% or less, and Al: 0.5% or less In addition, the steel sheet is composed of Fe and impurity elements as the balance.

  Among these elements, C is a component that lowers iron loss and is an element that causes magnetic aging, so it is preferable that the C content be 0.0100% or less (0.0000% to 0.0100%). .

In addition, Si is a component having an action of reducing iron loss by increasing eddy current loss by increasing electric resistance, and also has an action of improving punching accuracy by increasing a yield ratio. . In order to exhibit these effects, it is preferable to contain 2.00% or more.
On the other hand, when the content of Si is excessively increased, the magnetic flux density is decreased and the hardness is increased, and the punching accuracy is likely to be decreased. Moreover, in the manufacturing process of a steel plate (bidirectional electrical steel plate), workability such as cold rolling may be reduced and the cost may be high, so 4.00% or less is preferable.

  The steel sheet may contain elements such as Mn, Sb, Sn, Ni, Cu, Cr, P, and Al in addition to the above-described C and Si. These components may be contained in the general amounts as described above. Specifically, Mn: 0.5% or less, Sb: 0.2% or less, Sn: 0.2% or less, Ni: 0.5% or less, Cu: 0.5% or less, Cr: 0.5 % Or less, P: 0.3% or less, and Al: 0.5% or less. And the remainder contains Fe and impurity elements. However, the lower limit of Mn, Sb, Sn, Ni, Cu, Cr, P, and Al is 0.0%.

Here, as a suitable iron core of this invention, the iron core shown in FIG. 4 and FIG. 5 is mentioned, for example.
The iron core 100 shown in FIG. 4 is a schematic diagram showing an example of the iron core of the present invention. The iron core 100 shown in FIG. 4 represents a split iron core. As shown in FIG. 4, the iron core 100 includes a yoke portion 17 on an arc and a punching member 11 for a split iron core including a tooth portion 15 projecting radially inward from the inner peripheral surface of the yoke portion 17. Have The iron core 100 is formed as a laminated body 13 in which a plurality of punched members 11 for a split iron core are connected in an annular shape, and are laminated and integrated. Note that the punching member 11 for the split iron core is not limited to the shape, the number, the number of stacked layers, and the like shown in FIG. 4, and may be designed according to the purpose.

  An iron core 300 shown in FIG. 5 is a schematic diagram showing another example of the iron core of the present invention. An iron core 300 shown in FIG. 5 represents a spirally wound iron core. As shown in FIG. 5, the iron core 300 includes a punching member 31 for a spirally wound iron core provided with a yoke portion 37 on the outer peripheral side and a teeth portion 35 protruding radially inward from the inner peripheral surface of the yoke portion 37. Have. The punching member 31 for the spirally wound iron core is subjected to helical bending so that the yoke portion 37 is on the outer peripheral side and the teeth portion 35 is on the inner peripheral side. The iron core 300 is formed as a laminated body 33 in which a plurality of punching members 31 are laminated and integrated. The punching member 31 for the spirally wound iron core is not limited to the shape shown in FIG. 4 and the number of stacked layers, and may be designed according to the purpose.

  Although the iron core shown in FIGS. 4 and 5 has been described above, the iron core of the present invention is not limited to these.

  Next, the suitable manufacturing method of the iron core of this invention is demonstrated. As a suitable manufacturing method of the iron core of this invention, the following manufacturing methods are mentioned, for example.

  The area ratio occupied by crystal grains of {100} <001> (± 30 °) is 50% or more, and the area ratio occupied by crystal grains of {110} <110> (± 30 °) is You may have the process of punching 20% of the bi-directional electrical steel sheet to obtain a punched member and the process of stacking and integrating the punched members to obtain an iron core. Note that the laminated and integrated iron core may be annealed to remove processing strain.

  Specifically, first, a unidirectional electrical steel sheet having crystal grains accumulated in the {110} <001> orientation is prepared. Cold rolling is performed so that the rolling reduction is 20% to 50% in a direction orthogonal to the rolling direction of the prepared unidirectional electrical steel sheet. After cold rolling, annealing is performed at a temperature range of 700 ° C. or more (preferably 700 ° C. or more and less than 1100 ° C.), and has {100} <001> (± 30 °) crystal grains of 50% or more, {110 } A bi-directional electrical steel sheet having 20% or more of <110> (± 30 °) crystal grains is obtained.

  A punching member is obtained from the bi-directional electrical steel sheet, and the punching members are laminated and integrated. What is necessary is just to manufacture an iron core by the method normally employ | adopted as the method of obtaining the punching member, and the method of laminating and integrating a punching member.

For example, when the iron core is a split iron core, this bi-directional electrical steel sheet is punched to obtain a punched member. Then, the punching members are combined and stacked, and stacked and integrated to obtain an iron core.
For example, the punching member may be a punching member having a predetermined shape having a teeth portion and a yoke portion. Further, the punching member having a predetermined shape punches a predetermined number of sheets. The punching member having a predetermined shape may be provided with an uneven portion for stacking and integrating when punching into a predetermined shape, for example. Next, a predetermined number of punched members are laminated in a predetermined number and laminated and integrated to obtain an iron core. In the lamination integration, for example, the concavo-convex portions formed on the punched plates are mechanically fitted to each other and fixed by caulking, and the punching members are stacked and integrated.

For example, when the iron core is a spirally wound iron core, the bi-directional electrical steel sheet is punched to obtain a punched member. Then, the punching member is subjected to a helical bending process to obtain a bending process member. Thereafter, the bent members are laminated and integrated to obtain an iron core.
A plurality of punching members for the spirally wound iron core are provided, for example, a yoke portion continuously extending in a direction along the longitudinal direction of the strip-shaped punching member and a one end side in the short side direction of the yoke portion. And a tooth portion. The punching member for the spirally wound iron core may be, for example, a length that can be spirally bent for one round, or a length that can be laminated while being spirally bent and wound. . The punching member may be formed with an uneven portion for stacking and integrating when punched into a predetermined shape, for example.
A punching member for a spirally wound iron core is formed into a bent member by spiral bending, and then the bent member is laminated and laminated to obtain an iron core. For example, the punching member may be bent in a spiral manner with the punching member in the plate surface direction, the teeth portion on the inside and the yoke portion on the outside. For the lamination of the bending members, a plurality of bending members may be laminated. In this case, the layers may be stacked by turning. Further, the bent member may be wound and laminated. In the lamination integration, for example, the concavo-convex portions formed on the punched plates are mechanically fitted to each other and fixed by caulking, and the punching members are stacked and integrated.
An iron core using a bi-directional electrical steel sheet is obtained through the above steps. That is, the iron core obtained using the bi-directional electrical steel sheet has excellent magnetic properties in two orthogonal directions.

  The chemical composition of the unidirectional electrical steel sheet used for obtaining the iron core is, for example, mass%, C: 0.0030% or less, Si: 2.00% or more and 4.00% or less, Mn: 0.00. 5% or less, Sb: 0.2% or less, Sn: 0.2% or less, Ni: 0.5% or less, Cu: 0.5% or less, Cr: 0.5% or less, P: 0.3% It is preferable that the steel plate contains less than 0.5% Al and 0.5% or less, and the balance is Fe and impurity elements.

Next, another preferred steel sheet used for the iron core of the present invention will be described.
As another preferred steel sheet used for the iron core of the present invention, for example, {110} <110> (± 30 °), in that the obtained iron core has excellent dimensional accuracy and suppresses a decrease in the space factor. The area ratio of crystal grains in the crystal orientation is 85% or more (preferably 90% to 100%, more preferably 95% to 100%), and the number of shear bands is 30 pieces / mm or more (preferably 40 pieces / piece). mm or more, more preferably 50 pieces / mm or more).

  In the re-cold rolled steel sheet, in addition to the area ratio occupied by crystal grains of {110} <110> (± 30 °) being 85% or more, the number of shear bands is 30 pieces / mm or more. Therefore, it is excellent in punching dimensional accuracy when performing punching and bending workability when performing bending. Therefore, by using a re-cold rolled steel sheet having these characteristics, the obtained iron core is excellent in dimensional accuracy, and a decrease in the space factor is suppressed.

  Here, the crystal orientation of the re-cold rolled steel sheet and the steel sheet annealed from the re-cold rolled steel sheet indicates that the face in {} is parallel to the steel sheet and the axis in <> is parallel to the re-rolling direction. . The crystal orientation is observed under the above-described conditions using EBSD.

  As a method for obtaining the re-cold rolled steel sheet, for example, the width direction of the cut sheet of the unidirectional electrical steel sheet having crystal grains accumulated in the {110} <001> orientation (relative to the rolling direction of the unidirectional electrical steel sheet) Cold rolling (hereinafter sometimes referred to as “cold rolling”). By this cold rolling, the area ratio of the crystal grains with the crystal orientation of {110} <110> (± 30 °) is 85% or more (for example, 95% or more), and the number of shear bands is 30 pieces / mm or more. A re-cold rolled steel sheet is obtained (for example, 40 pieces / mm or more). In this cold rolling, the rolling reduction is preferably in the range of 20% to 50%.

Here, when the unidirectional electrical steel sheet having crystal grains accumulated in the {110} <001> orientation is rotated 90 degrees in the thickness direction, the {110} <110> orientation is obtained. When the {110} <110> orientation is cold-rolled, {110} <110> is partially changed to {100} <001> according to the reduction ratio due to shear deformation.
At this time, when the rolling reduction is less than 20%, the amount of {100} <001> orientation is too small. For this reason, when an iron core is obtained using a re-cold rolled steel sheet in which the amount of {100} <001> orientation is too small, the obtained iron core has reduced magnetic properties. Moreover, since the number of shear bands of the re-cold rolled steel sheet is less than 30 / mm, the dimensional accuracy of the iron core is inferior.
On the other hand, when the rolling reduction is over 50%, the {110} <110> oriented grains change to {111} <110> having low magnetic properties, so that the magnetic properties of the obtained iron core are deteriorated. In addition, the dimensional accuracy and space factor of the iron core are reduced. Moreover, since the orientation of the re-cold rolled steel sheet after annealing is likely to change to {111} <211> having poor magnetic properties, the magnetic properties of the obtained iron core are further lowered.
In this manner, the unidirectional electrical steel sheet having crystal grains accumulated in the {110} <001> orientation was cold-rolled so that the rolling reduction was 20% to 50% in the direction orthogonal to the rolling direction. When a cold-rolled steel sheet is used, a re-cold-rolled steel sheet having the above characteristics can be obtained. And the iron core obtained using this re-cold-rolled steel plate is excellent in a magnetic characteristic and dimensional accuracy, and the fall of a space factor is suppressed.

In addition, the area ratio which the crystal grain of the crystal orientation of {110} <110> (± 30 °) occupies is measured by the method described above.
Further, the number of shear bands of the re-cold rolled steel sheet is measured as follows.
The test piece is cut in parallel to the rolling direction so that the plate thickness cross section can be observed, and the shear band is corroded by the nital etching to be expressed. A line segment of 1 mm is drawn at the center of the plate thickness of the photograph used for observing the crystal grain size. The intersections of the line segments and the shear bands are counted, and the number of intersections is expressed in units of pieces / mm. At this time, the shear band refers to etching traces in the form of diagonal lines inclined in the crystal grains by 10 ° to 70 ° from the rolling direction.

As the re-cold rolled steel sheet, if the area ratio occupied by crystal grains of {110} <110> (± 30 °) is 85% or more and the number of shear bands is 30 / mm or more, The chemical composition of the cold rolled steel sheet is not particularly limited. Examples of the re-cold rolled steel sheet include a re-cold rolled steel sheet having the following chemical composition.
By mass ratio, C: 0.0000% to 0.0030%, Si: 2.00% to 4.00%, Mn: 0.0% to 0.5%, Sb: 0.0% to 0.2% %, Sn: 0.0% to 0.2%, Ni: 0.0% to 0.5%, Cu: 0.0% to 0.5%, Cr: 0.0% to 0.5%, P: 0.0% to 0.3% and Al: 0.0% to 0.5%. The balance is a steel plate made of Fe and impurity elements.
The chemical composition of the re-cold rolled steel sheet is preferably within the above range in terms of the same chemical composition as exemplified by the preferred steel sheet (bidirectional electrical steel sheet) used for the iron core described above.

  In addition, as a suitable iron core obtained using a re-cold-rolled steel sheet, the iron core shown in above-mentioned FIG. 4 and FIG. 5 is mentioned, for example.

Next, another preferred method for producing the iron core of the present invention will be described.
Another preferred method for producing the iron core of the present invention is, for example, a rolling reduction of 20% in the direction orthogonal to the rolling direction of the unidirectional electrical steel sheet having crystal grains accumulated in the {110} <001> orientation. Cold-rolled to ˜50%, the area ratio occupied by crystal grains of {110} <110> (± 30 °) is 85% or more, and the number of shear bands is 30 pieces / mm or more A step of obtaining a re-cold rolled steel sheet, a step of punching the re-cold rolled steel sheet to obtain a punched member, and a step of stacking and integrating the punched members and annealing in a temperature range of 700 ° C. or higher.

First, a specific re-cold rolled steel sheet is obtained from a unidirectional electrical steel sheet.
Specifically, a steel sheet (hereinafter referred to as “cut sheet”) cut in the width direction of the coil of a unidirectional electrical steel sheet having crystal grains accumulated in the {110} <001> orientation is prepared. As the unidirectional electrical steel sheet, a steel sheet having no insulating coating and forsterite film may be prepared. Alternatively, a steel plate having an insulating coating and a forsterite film may be prepared, and the insulating coating and the forsterite film may be mechanically removed by cutting or the like.

In addition, as the unidirectional electrical steel sheet, the chemical composition of the unidirectional electrical steel sheet is not particularly limited as long as it has crystal grains accumulated in the {110} <001> orientation. The unidirectional electrical steel sheet having crystal grains accumulated in the {110} <001> orientation is preferably, for example, a unidirectional electrical steel sheet having the following chemical composition.
As such a unidirectional electrical steel sheet, by mass ratio, C: 0.0000% to 0.0030%, Si: 2.00% to 4.00%, Mn: 0.0% to 0.5% , Sb: 0.0% to 0.2%, Sn: 0.0% to 0.2%, Ni: 0.0% to 0.5%, Cu: 0.0% to 0.5%, Cr : 0.0% to 0.5%, P: 0.0% to 0.3%, and Al: 0.0% to 0.5%. The balance is a steel plate made of Fe and impurity elements.

  Next, cold rolling is performed in the width direction of the prepared cut plate (direction perpendicular to the rolling direction of the unidirectional electrical steel sheet) so that the rolling reduction is 20% to 50%, A re-cold rolled steel sheet similar to the cold rolled steel sheet is obtained. That is, in the re-cold rolled steel sheet, the area ratio occupied by the crystal grains of {110} <110> (± 30 °) is 85% or more, and the number of shear bands is 30 / mm or more.

Next, the re-cold rolled steel sheet is punched to obtain a punched member (punched plate). The punching member is punched into a predetermined shape according to the iron core suited to the purpose. The method for obtaining the punched member is not particularly limited, and may be performed by a method that is usually employed industrially.
In addition, the process of obtaining a punching member is, for example, a two-stage process including a process of obtaining a preliminary punching member larger than a punching member having a predetermined shape and a process of obtaining a punching member having a predetermined shape from the preliminary punching member. Also good.

When the iron core is a split iron core, examples of the punching member for the split iron core include a punching member having a divided shape having a teeth portion and a yoke portion.
When the iron core is a spirally wound iron core, the punching member for the spirally wound iron core is, for example, a belt-like punching member, and a yoke portion continuously extending in the direction along the longitudinal direction, and a short side of the yoke portion The punching member of the shape which has the teeth part which protruded in the one edge part side of the direction and was provided with two or more is mentioned. The punching member for the spirally wound iron core may be, for example, a length that can be spirally bent for one round, or a length that can be laminated while being spirally bent and wound. .
When these punching members are laminated and integrated, when punched into a predetermined shape having a tooth portion and a yoke portion, for example, an uneven portion for stacking and integrating may be formed.

Next, the punching member is laminated and integrated.
For example, when the iron core is a split iron core, a predetermined number of punched members for the split iron core are combined and connected in an annular shape, and are laminated. Then, for example, the concavo-convex portions formed on each punching plate are mechanically fitted and fixed to each other by caulking, and the punching members are laminated and integrated.

When the iron core is a spirally wound iron core, the punched member for the spirally wound core is bent to obtain a bent punched member (hereinafter also referred to as “bending member”). In the bending process, for example, the bending process is performed with respect to the plate surface direction of the punching member so that the yoke part is on the outer peripheral side and the teeth part is on the inner peripheral side. And a bending process member is laminated | stacked. The bending member may be laminated by laminating a predetermined number of bending members subjected to one round of bending. In this case, the layers may be stacked by turning. Further, the bent member may be wound and laminated. After that, for example, by caulking, the laminated bending members are mechanically fitted and fixed to each other, and the bending members are laminated and integrated.
In addition, although the method of laminating and integrating by caulking is described as an example, the method of laminating and integrating is not particularly limited, and may be performed by a method that is usually employed industrially.

Next, annealing is performed on the laminated body integrated. The annealing temperature is preferably 700 ° C. or higher, and preferably 800 ° C. or higher, in that the magnetic properties of the obtained iron core are superior. The upper limit of the annealing temperature range is not particularly limited, but if the annealing temperature is too high, the magnetic properties of the resulting iron core may be inferior, so the upper limit of the annealing temperature range is less than 1100 ° C. (preferably 1000 ° C. or lower).
An iron core using a re-cold rolled steel sheet is obtained through the above steps.

  Here, in the re-cold rolled steel sheet, the area ratio occupied by the crystal grains of {110} <110> (± 30 °) is 85% or more, and the number of shear bands is 30 / mm or more. In this re-rolled steel sheet, the area ratio of crystal grains within ± 30 degrees from the {100} <001> orientation is less than 15%. The steel sheet after recrystallizing the re-cold rolled steel sheet can increase the area ratio of crystal grains within ± 30 degrees from the {100} <001> orientation to 50% or more. At this time, it is desirable to set the recrystallization ratio to 100%. In order to recrystallize the re-cold rolled steel sheet, it is preferable to perform annealing in a temperature range of 700 ° C. or higher (preferably 700 ° C. to 1000 ° C.). The steel plate after recrystallization by this annealing has 50% or more of {100} <001> (± 30 °) crystal grains and 20 crystal grains of {110} <110> (± 30 °). % Or more. That is, the iron core obtained using the re-cold rolled steel sheet has excellent magnetic properties in two orthogonal directions due to the above annealing.

In addition, the iron core of this invention is good also as what laminated | stacked the re-cold-rolled steel plate. When making the iron core laminated with the re-cold rolled steel sheet, as a manufacturing method of this iron core, in the direction orthogonal to the rolling direction of the unidirectional electrical steel sheet having crystal grains accumulated in the {110} <001> orientation, Cold rolling so that the reduction ratio is 20% to 50%, the area ratio occupied by crystal grains of {110} <110> (± 30 °) is 85% or more, and the number of shear bands is It includes a step of obtaining a re-cold rolled steel sheet of 30 pieces / mm or more, a step of punching the re-cold rolled steel plate to obtain a punched member, and a step of stacking and integrating the punched members.
Moreover, you may anneal the iron core which laminated | stacked this re-cold-rolled steel plate in the temperature range of 700 to 1000 degreeC, for example. By annealing in this temperature range, the steel sheet constituting the iron core has 50% or more of {100} <001> (± 30 °) crystal grains, and {110} <110> (± 30 °) crystals. It has 20% or more of grains. That is, the iron core has excellent magnetic properties in the two orthogonal directions described above.

  As described above, as the preferred steel sheet for obtaining the iron core of the present invention, the description has been given taking the example of the bi-directional electrical steel sheet and the re-cold rolled steel sheet, but the crystal with the crystal orientation of {100} <001> (± 30 °) If an iron core made of a steel sheet having an area ratio of grains of 50% or more and an area ratio of grains of {110} <110> (± 30 °) crystal orientation of 20% or more can be obtained, It is not limited to steel plates.

  In addition, in the method of obtaining an iron core using the conventional bidirectional magnetic steel plate, the special apparatus for obtaining a bidirectional magnetic steel plate was required. On the other hand, the iron core of the present invention does not require a special device for obtaining a bidirectional magnetic steel sheet, and an iron core having excellent magnetic properties in two directions can be easily produced.

  As described above, according to the present invention, the iron core has excellent magnetic properties, excellent dimensional accuracy, and suppression of a decrease in the space factor. ) Is desirable. According to the present invention, it is possible to satisfactorily meet the urgent demand for high efficiency and miniaturization in the field of electrical equipment, and its industrial value is extremely high.

  The present invention is not limited to the above. The above is an exemplification, and any technology that has substantially the same configuration as the technical idea described in the claims of the present invention and has the same operational effects can be used. To be included in the scope.

  Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. It is obvious for those skilled in the art that various modifications or modifications can be conceived within the scope of the idea described in the claims, and these naturally belong to the technical scope of the present invention. It is understood.

Example 1
-Confirmation of main direction and sub-direction-
A confirmation test is performed on the steel sheet constituting the iron core of the present invention having a main orientation and a sub-orientation.
First, a cut plate of a unidirectional electrical steel sheet having a thickness of 0.30 mm containing, in mass%, C: 0.0030%, Si: 3.10%, and Mn: 0.1% is prepared. Next, the insulating coating is removed with an aqueous sodium hydroxide solution and the forsterite film is removed with sulfuric acid. Thereafter, cold rolling is performed at a rolling reduction of 40% with respect to the width direction of the cut plate from which the insulating coating and the forsterite film have been removed to obtain a re-cold rolled steel sheet. This re-cold rolled steel sheet has 91% of crystal grains within 30 ° from {110} <110>, and the number of shear bands is 72 / mm.
This re-rolled steel sheet is annealed at 850 ° C. for 1 second in a nitrogen atmosphere. After the annealing, the steel sheet is air-cooled.

The center layer of the steel sheet after annealing is observed by EBSD under the measurement conditions described above.
FIG. 3 shows a (001) pole figure of the steel plate after the annealing. As shown in FIG. 3, in the steel sheet after annealing, crystal grains are observed in two orientations: a {100} <001> neighborhood orientation 1A which is a main orientation and a {110} <110> neighborhood orientation 2A which is a sub orientation. The The area ratio of each crystal grain in the steel sheet used for this iron core is 61% for grains within 30 ° from {100} <001>, and 37% for grains within 30 ° from {110} <110>. It is.

  Moreover, a strip | belt-shaped punching member is pierce | punched from said re-cold-rolled steel plate so that several teeth part may be formed with respect to the direction along a cold rolling direction. This strip-shaped punching member has a yoke portion that continuously extends in a direction along the longitudinal direction, and a plurality of teeth portions that protrude toward one end in the short direction of the yoke portion. Next, the band-shaped punched member is bent to obtain a bent member. In the bending process, a spiral bending process is performed so that the strip-shaped punching member makes one round, and the yoke part is on the outer peripheral side and the teeth part is on the inner peripheral side. Thereafter, the bending members are laminated and caulking is performed to obtain a laminated body that is laminated and integrated. Then, this laminated body is annealed for 1 second on each temperature condition of 850 degreeC in nitrogen atmosphere, and an iron core is obtained. After annealing, the iron core is air-cooled.

  In the obtained iron core, a steel plate is collected from the teeth portion and the yoke portion, and the center layer of the plate thickness is observed by EBSD under the measurement conditions described above. The area ratio of the crystal grains in the collected steel sheet is 61% for grains within 30 ° from {100} <001> and 37% for grains within 30 ° from {110} <110>.

  Thus, it turns out that the iron core obtained using said re-rolled steel plate has the crystal grain of the crystal orientation corresponding to the main orientation and sub-orientation of the steel plate obtained by annealing a re-cold rolled steel plate.

(Example 2)
-Effect of rolling reduction and annealing conditions-
First, a 0.30 mm unidirectional electrical steel sheet containing C: 0.0002% and Si: 3.09% by mass% is prepared. Next, the insulating coating is removed with an aqueous sodium hydroxide solution, and the forsterite film is removed with sulfuric acid. Then, cold rolling is performed at a rolling reduction of 10% to 60% with respect to the width direction of the cut plate from which the insulating coating and the forsterite film have been removed to obtain a re-cold rolled steel sheet.

  A strip-shaped punching member is punched out from the re-cold rolled steel sheet so that a plurality of teeth are formed in the direction along the cold rolling direction. This strip-shaped punching member has a yoke portion that continuously extends in a direction along the longitudinal direction, and a plurality of teeth portions that protrude toward one end in the short direction of the yoke portion. Next, the band-shaped punched member is bent to obtain a bent member. In the bending process, a spiral bending process is performed so that the strip-shaped punching member makes one round, and the yoke part is on the outer peripheral side and the teeth part is on the inner peripheral side. Thereafter, the bending members are laminated and caulking is performed to obtain a laminated body that is laminated and integrated. Then, this laminated body is annealed for 1 second on each temperature conditions of 600 to 1100 degreeC in nitrogen atmosphere, and an iron core is obtained. After annealing, the iron core is air-cooled.

Each evaluation of a magnetic characteristic is performed about the iron core obtained by the said method. In the iron core obtained by the above method, a steel plate is collected from the tooth portion and the yoke portion, and the thickness center layer is observed by EBSD under the measurement conditions described above. Furthermore, in the iron core obtained by the above method, a steel plate is collected and the average crystal grain size is measured. Moreover, each evaluation of a punching precision and bending workability is performed about a re-cold-rolled steel plate.
The EBSD observation and the average crystal grain size are measured by the method described above.
Magnetic properties are measured by B ₅₀ (T) (magnetic flux density at a magnetizing force of 5000 A / m) and W _10/400 (W / kg) (iron loss at a magnetic flux density of 1.0 T and a frequency of 400 Hz).
B ₅₀ (T) and W _10/400 (W / kg) are average values of the direction along the radial direction of the iron core and the circumferential tangential direction.
Dimensional accuracy and bending workability are evaluated by the following operation method.
In addition, the dimensional accuracy and space factor of an iron core are evaluated by evaluating the dimensional accuracy and bending workability of a re-cold rolled steel sheet.

-Punching accuracy A ring-shaped sample having an inner diameter of 100 mm and an outer diameter of 120 mm is punched, and an average difference from a perfect circle (deviation from a perfect circle) is obtained. If the average difference is 2 μm or less, the dimensional accuracy of the obtained iron core is considered good.

-Bending workability A steel plate having a width of 20 mm and a length of 800 mm is produced, and bending is performed with an inner diameter of 200 mm and an outer diameter of 240 mm. The thickness change (%) at that time is measured. If the plate thickness change amount is 6% or less, it is considered that the decrease in the space factor of the obtained iron core is suppressed. However, if cracking is likely to occur during bending, warm working at 300 ° C. or lower may be performed.

As shown in Table 1, numerals 2-2 to the code 2-6 is within the scope of the present invention, these core has a high magnetic flux density B _50, punching accuracy and, bending workability is good. The steel plate of the core 2-1 has a small area ratio of crystal grains of {100} <001> (± 30 °). Therefore, the iron core of the code 2-1 is low flux density _{B 50.} Moreover, since the code | symbol 2-1 has few shear bands of a re-cold-rolled steel plate, its dimensional accuracy is inferior. Furthermore, since there are few shear bands, the area ratio of the {100} <001> (± 30 °) crystal grains after recrystallization is reduced, and the magnetic properties of the iron core are inferior.
The steel sheets of the cores 2-7 and 2-8 have {100} <001> (± 30 °) crystal grain area ratio and {110} <110> (± 30 °) crystal grain area ratio. Few. Therefore, the core code 2-7 and codes 2-8 lower magnetic flux density _{B 50.} Further, the re-cold rolled steel sheet 2-7 has a small area ratio of crystal grains of {110} <110> (± 30 °). Therefore, bending workability is inferior. Furthermore, in the steel sheet having the core 2-8, the non-recrystallized portion remains, so the W _{10/400 of} the core is remarkably inferior.
Moreover, as shown in Table 1, when the rolling reduction is too low, the steel sheet of the iron core has a small area ratio of crystal grains of {100} <001> (± 30 °). When the rolling reduction is too high or the annealing temperature is too low, the steel sheet of the iron core has {100} <001> (± 30 °) crystal grain area ratio and {110} <110> (± 30 °) crystal. The area ratio of grains is small. Furthermore, when the rolling reduction is the same and the annealing temperature is high, the steel sheet of the iron core tends to have a large average grain size.
In addition, although the steel plate of the iron core of a code | symbol 2-6 is in the scope of the present invention, the crystal grain size is as coarse as 320 μm. Therefore, the iron loss is higher than that of the core 2-3 of the same re-cold rolling condition, which is disadvantageous in terms of magnetic characteristics.

(Example 3)
-Effects of chemical composition-
First, a cut plate of a unidirectional electrical steel sheet (noted as a steel sheet) having a chemical composition shown in Table 2 in mass% and having a thickness of 0.30 mm is prepared. Next, the insulating coating is removed with an aqueous sodium hydroxide solution, and the forsterite film is removed with sulfuric acid. Thereafter, cold rolling is performed at a rolling reduction of 40% in the width direction of the cut plate from which the insulating coating and the forsterite film have been removed, to obtain a re-cold rolled steel sheet.

  A strip-shaped punching member is punched out from the re-cold rolled steel sheet so that a plurality of teeth are formed in the direction along the cold rolling direction. This strip-shaped punching member has a yoke portion that continuously extends in a direction along the longitudinal direction, and a plurality of teeth portions that protrude toward one end in the short direction of the yoke portion. Next, the band-shaped punched member is bent to obtain a bent member. In the bending process, a spiral bending process is performed so that the strip-shaped punching member makes one round, and the yoke part is on the outer peripheral side and the teeth part is on the inner peripheral side. Thereafter, the bending members are laminated and caulking is performed to obtain a laminated body that is laminated and integrated. This laminated body is annealed at 850 ° C. for 1 second in a nitrogen atmosphere to obtain an iron core. After annealing, the iron core is air-cooled.

  Each evaluation is performed by the same evaluation method as Example 2 about the re-cold-rolled steel sheet and iron core obtained by the said method.

As shown in Table 3, the steel sheets constituting the iron core are {100} <001> (± 30 °) crystal grains, regardless of the chemical composition of the unidirectional electrical steel sheet used for obtaining the re-cold rolled steel sheet. And the area ratio of crystal grains of {110} <110> (± 30 °) are within the scope of the present invention. And the iron core which consists of a steel plate whose area ratio of the crystal grain of {100} <001> (± 30 degrees) and the area ratio of the crystal grain of {110} <110> (± 30 degrees) is in the range of the present invention. Shows that the magnetic flux density B ₅₀ is high. Further, a re-cold rolled steel sheet having an area ratio of crystal grains of {110} <110> (± 30 °) of 85% or more and the number of shear bands of 30 pieces / mm or more has punching accuracy and bending workability. Is found to be good. Thereby, it turns out that the fall of a dimensional accuracy and a space factor is suppressed for the iron core obtained using this cold-rolled steel plate.
However, if the recommended range of chemical components is deviated, another problem occurs. The steel sheet of reference number 3-9 has a large amount of C and is not suitable for application to a motor core because it causes magnetic aging. Moreover, since the steel plate of 3-10 has many Si and workability | operativity at the time of cold rolling falls, it is not suitable for commercial production. Since the steel sheet of reference number 3-11 has a small amount of Si and undergoes phase transformation, it is not suitable for commercial production of a unidirectional electrical steel sheet. Therefore, it is difficult to produce an iron core commercially using these steel plates, and even if the iron core can be produced, it is difficult to obtain stable and sufficient performance as the iron core.

Example 4
-Confirmation of main direction and sub-direction by other examples-
Even if the iron core of the present invention is manufactured from a bi-directional electrical steel sheet having a main orientation and a sub-orientation, a confirmation test is performed on the steel sheet constituting the iron core having a main orientation and a sub-direction.
A cut plate of a unidirectional electrical steel sheet having a thickness of 0.30 mm containing C: 0.0030%, Si: 3.10%, and Mn: 0.1% in mass% is prepared. Next, the insulating coating is removed with an aqueous sodium hydroxide solution and the forsterite film is removed with sulfuric acid. Thereafter, cold rolling is performed at a rolling reduction of 40% with respect to the width direction of the cut plate from which the insulating coating and the forsterite film have been removed. Thereafter, the cold-rolled sheet is annealed at 850 ° C. for 1 second in a nitrogen atmosphere. After the annealing, the steel sheet is air-cooled to obtain a bi-directional electrical steel sheet.

  The central layer of this steel sheet is observed by EBSD under the measurement conditions described above. As a result, the area ratio of crystal grains in this bi-directional electrical steel sheet is 61% for grains within 30 ° from {100} <001>, and for grains within 30 ° from {110} <110> 37%.

  From this bi-directional electrical steel sheet, a strip-shaped punching member is punched so that a plurality of teeth are formed in the direction along the cold rolling direction. This strip-shaped punching member has a yoke portion that continuously extends in a direction along the longitudinal direction, and a plurality of teeth portions that protrude toward one end in the short direction of the yoke portion. Next, the band-shaped punched member is bent to obtain a bent member. In the bending process, a spiral bending process is performed so that the strip-shaped punching member makes one round, and the yoke part is on the outer peripheral side and the teeth part is on the inner peripheral side. Thereafter, the bent members are laminated, caulked, and laminated and integrated to obtain an iron core.

  In the iron core obtained by the above method, a steel plate is taken from the tooth portion and the yoke portion of the iron core, and the thickness center layer thereof is observed by EBSD under the measurement conditions described above. As a result, the area ratio of crystal grains in the collected steel sheet was 61% for grains within 30 ° from {100} <001>, and 37% for grains within 30 ° from {110} <110>. is there.

  Thus, the iron core obtained using the bi-directional electrical steel sheet having the main orientation and the sub-azimuth hardly changes the orientation by bending, and the main orientation and sub-azimuth corresponding to the bi-directional electrical steel sheet It can be seen that

Claims (12)

  The area ratio occupied by crystal grains of {100} <001> (± 30 °) is 50% or more, and the area ratio occupied by crystal grains of {110} <110> (± 30 °) is An iron core made of steel sheet that is 20% or more.   The iron core according to claim 1, wherein the steel sheet has an average crystal grain size of 350 μm or less. The steel sheet is in mass%,
C: 0.0100% or less,
Si: 2.00% to 4.00%,
Mn: 0.5% or less,
Sb: 0.2% or less,
Sn: 0.2% or less,
Ni: 0.5% or less,
Cu: 0.5% or less,
Cr: 0.5% or less,
P: 0.3% or less,
And Al: 0.5% or less, and the iron core according to claim 1 or 2 containing Fe and an impurity element as a balance.   A re-cold rolled steel sheet in which the area ratio of crystal grains having a crystal orientation of {110} <110> (± 30 °) is 85% or more and the number of shear bands is 30 pieces / mm or more. % By mass
C: 0.0100% or less,
Si: 2.00% to 4.00%,
Mn: 0.5% or less,
Sb: 0.2% or less,
Sn: 0.2% or less,
Ni: 0.5% or less,
Cu: 0.5% or less,
Cr: 0.5% or less,
P: 0.3% or less,
And Al: 0.5% or less is contained, and the re-cold-rolled steel sheet according to claim 4 containing Fe and an impurity element as a balance.   Cold rolling in a direction perpendicular to the rolling direction of the unidirectional electrical steel sheet having crystal grains accumulated in the {110} <001> orientation so that the reduction ratio is 20% to 50%. A method for producing a re-cold rolled steel sheet, comprising a step of obtaining the re-cold rolled steel sheet according to 4 or 5.   An iron core in which the re-cold rolled steel sheets according to claim 4 or 5 are laminated. 5. Cold rolling so that the rolling reduction is 20% to 50% in a direction orthogonal to the rolling direction of the unidirectional electrical steel sheet having crystal grains accumulated in the {110} <001> orientation, Or a step of obtaining a re-cold rolled steel sheet according to 5,
Punching the re-cold rolled steel sheet to obtain a punched member;
A step of laminating and integrating the punched members and annealing in a temperature range of 700 ° C. or higher;
The manufacturing method of the iron core of any one of Claims 1-3 which have these.
  The said temperature range is 700 to 1000 degreeC, The manufacturing method of the iron core of Claim 8. 5. Cold rolling so that the rolling reduction is 20% to 50% in a direction orthogonal to the rolling direction of the unidirectional electrical steel sheet having crystal grains accumulated in the {110} <001> orientation, Or a step of obtaining a re-cold rolled steel sheet according to 5,
Punching the re-cold rolled steel sheet to obtain a punched member;
The method for manufacturing an iron core according to claim 7, further comprising: stacking and integrating the punched members.   It is a manufacturing method of the iron core of Claim 10, Comprising: The manufacturing method of the iron core which further has the process of annealing in a 700 to 1000 degreeC temperature range after the said lamination | stacking integration process. The area ratio occupied by crystal grains of {100} <001> (± 30 °) is 50% or more, and the area ratio occupied by crystal grains of {110} <110> (± 30 °) is Punching a bi-directional electrical steel sheet that is 20% or more to obtain a punched member;
A step of stacking and integrating the punched members;
The manufacturing method of the iron core of any one of Claims 1-3 which have these.