RU2809519C1 - Tape core - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: strip core comprises a substantially rectangular strip core body in side view. The main body of the strip core includes a portion in which the anisotropic electrical steel sheets in which the flat portions and the corner portions are continuously alternated in the longitudinal direction, and the angle formed by the two adjacent flat portions, with each of the corner portions between them, is 90°, are laid in the thickness direction of the sheet, and has a substantially rectangular laminated structure in side view. Each of the corner portions has two or more curved portions having a curved shape in a side view of the anisotropic electrical steel sheets, and the sum of the bending angles of the curved portions in one corner portion is 90°. Each curved part in the side view has an internal radius of curvature r of 1-5 mm. Sheets of anisotropic electrical steel have a chemical composition containing, wt.%, Si: 2.0-7.0%, with a residue of Fe and impurities, and a texture oriented in the Goss orientation. More than half of the measured values obtained at a variety of different positions along the thickness of the laminate are 0.20-0.70 for the interlayer friction coefficients, which are the dynamic coefficients of friction of the laminate anisotropic electrical steel sheets in at least some of the flat parts, and their average the value is 0.20-0.70.

EFFECT: reducing the noise in the core.

3 cl, 7 dwg, 7 tbl

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

[0001]

The present invention relates to a strip core. Priority is claimed to Japanese Patent Application No. 2020-178891, filed on October 26, 2020, the contents of which are incorporated herein by reference.

BACKGROUND OF THE ART

[0002]

The anisotropic electrical steel sheet is a steel sheet containing 7 mass% or less of Si, and has a secondary recrystallization texture in which the secondary recrystallization grains are concentrated in the {110}<001> orientation (Goss orientation). The magnetic properties of anisotropic electrical steel sheets are significantly affected by the degree of concentration in the {110}<001> orientation. In recent years, in anisotropic electrical steel sheets that have been put into practical use, the angle between the crystal direction <001> and the rolling direction is controlled to be in the range of approximately 5°.

[0003]

Sheets of anisotropic electrical steel are laminated and used in the metal cores of transformers, etc. In addition to the main magnetic properties of high magnetic flux density and low magnetic losses, low magnetostriction is also required, which causes vibration and noise. As is known, crystal orientation has a strong correlation with these properties, and, for example, Patent Documents 1-3 disclose techniques for precise control of orientation.

[0004]

In addition, Patent Document 4, which discusses the influence of deformation and the like occurring during processing, discloses a technique for improving properties by controlling the dynamic coefficient of friction of the surface of an anisotropic electrical steel sheet. Patent documents 5 and 6, etc. reveal techniques for reducing noise by controlling the dynamic coefficient of friction of the surface of steel sheets laminated in the form of a core.

[0005]

In addition, in the prior art for producing a strip core, as described, for example, in Patent Document 7, it is widely known to wind a steel sheet into a cylindrical shape and then press the cylindrical laminated body without modification, so that its corner parts have a constant curvature , shaping it into a substantially rectangular shape and then annealing it to relieve stress and maintain its shape.

[0006]

On the other hand, as other methods for manufacturing the strip core, techniques such as those described in Patent Documents 8-10 have been disclosed, in which portions of the steel sheet that will be the corner portions of the strip core are bent in advance so as to form a relatively small bending area with a radius curvatures of 3 mm or less, and bent steel sheets are laminated to form a strip core. According to these production methods, the conventional large-scale pressing process is not required, the steel sheets are precisely bent to maintain the shape of the metal core, and the stress generated during processing is also concentrated only in the curved parts (corner parts). For this reason, it becomes possible to eliminate the stress relief due to the above-mentioned annealing process, the industrial benefits are great, and the application of this method is progressing.

BIBLIOGRAPHY

PATENT DOCUMENTS

[0007]

[Patent Document 1]

Japanese Unexamined Patent Application, First Publication No. 2001-192785

[Patent Document 2]

Japanese Unexamined Patent Application, First Publication No. 2005-240079

[Patent Document 3]

Japanese Unexamined Patent Application, First Publication No. 2012-052229

[Patent Document 4]

Japanese Unexamined Patent Application, First Publication No. H11-124685

[Patent Document 5]

International Patent Application No. WO2018/123339

[Patent Document 6]

Japanese Unexamined Patent Application, First Publication No. 2011-90456

[Patent Document 7]

Japanese Unexamined Patent Application, First Publication No. 2005-286169

[Patent Document 8]

Japanese Patent No. 6224468

[Patent Document 9]

Japanese Unexamined Patent Application, First Publication No. 2018-148036

[Patent Document 10]

Australian Published Patent Application No. 2012337260

SUMMARY OF THE INVENTION

PROBLEMS SOLVED BY THE INVENTION

[0008]

It is an object of the present invention to provide a strip core produced by a method of bending steel sheets in advance so that a relatively small bending area with a radius of curvature of 5 mm or less is formed, and laminating the bent steel sheets to form a strip core, thereby minimizing the generation of noise caused by the combination the shape of the metal core and the steel sheets used.

REMEDIES FOR SOLVING THE PROBLEM

[0009]

The inventors of the present invention have studied in detail the noise characteristics of a metal core of a transformer produced by a method of bending steel sheets in advance so as to form a relatively small bending area having a radius of curvature of 5 mm or less, and laminating (layering) the bent steel sheets to form a strip core. As a result, they discovered that even when the material used is steel sheets with essentially the same crystal orientation control and essentially the same amount of magnetostriction measured for a single sheet, there may be a difference in the noise of the metal core.

[0010]

As a result of investigating the cause of this problem, it was found that the difference in problematic noise is influenced by the surface condition of the materials, and that the extent of this phenomenon also varies depending on the sizes and shapes of the cores.

In this regard, various steel sheet production conditions and core shapes were studied and their effects on noise were classified. As a result, it has been found that steel sheets produced under specific production conditions can be used as metal core materials with specific sizes and shapes to minimize the noise of the metal cores.

[0011]

To achieve this goal, the present invention uses the following aspect.

That is, one aspect of the present invention is a strip core including: a substantially rectangular strip core body in side view, which includes a portion in which anisotropic electrical steel sheets, in which flat portions and angular portions are continuously alternated longitudinally direction, and the angle between two flat portions adjacent to each other, with each of the corner portions therebetween being 90°, is laid in the thickness direction of the sheet, and which has a substantially rectangular laminated structure in side view, each of the corner portions having two or more curved parts having a curved shape in the side view of the anisotropic electrical steel sheets 1, the sum of the bending angles of the curved parts existing in one corner part is 90°, each curved part in the side view has an inner radius of curvature r of 1-5 mm, anisotropic electrical steel sheets have a chemical composition containing, in wt.%, Si: 2.0-7.0%, with the remainder of Fe and impurities, and have a texture oriented in the Goss orientation, with more than half of the measured values obtained in many different positions along the thickness of the laminate, are 0.20-0.70 for the interlayer friction coefficients, which are the dynamic friction coefficients of the laminate anisotropic electrical steel sheets in at least some of the flat parts, and their average value is 0.20-0 ,70.

[0012]

In addition to this, in this aspect, it is preferable that the standard deviation of the magnetostriction λpp of the anisotropic electrical steel sheets be 0.01×10 ^-6 -0.10×10 ^-6 .

However, the standard deviation is determined by the range of the magnetostriction value measured on flat areas of each of a plurality of randomly selected anisotropic electrical steel sheets taken from laminated anisotropic electrical steel sheets.

[0013]

Moreover, in this aspect, it is preferable that, in flat portions, the proportion of the area in which the anisotropic electrical steel sheets face each other with an interlayer friction coefficient of 0.20 or more is 50% or more of the total area in which the anisotropic electrical steel sheets laminated and facing each other.

[0014]

In addition to this, in this aspect, it is preferable that the interlayer friction coefficient of the laminated anisotropic electrical steel sheets in the region within 50% of the thickness of the laminated anisotropic electrical steel sheets from the inner side of the strip core in the flat parts is 0.20 to 0.70.

USEFUL EFFECTS OF THE INVENTION

[0015]

According to the above-described aspect of the present invention, in a strip core formed by laminating curved anisotropic electrical steel sheets, the generation of noise caused by the combination of the shape of the metal core and the steel sheets used can be effectively minimized.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]

Fig. 1 is a perspective view schematically showing one embodiment of a strip core in accordance with the present invention.

Fig. 2 is a side view of the strip core shown in the embodiment of FIG. 1.

Fig. 3 is a side view schematically showing another embodiment of a strip core in accordance with the present invention.

Fig. 4 is a side view schematically showing one example of a single-layer anisotropic electrical steel sheet constituting a strip core according to one embodiment of the present invention.

Fig. 5 is a side view schematically showing another example of a single-layer anisotropic electrical steel sheet constituting a strip core according to one embodiment of the present invention.

Fig. 6 is a side view schematically showing one example of a curved portion of an anisotropic electrical steel sheet constituting a strip core according to one embodiment of the present invention.

Fig. 7 is a schematic diagram showing the dimensions of the strip cores produced in the examples and comparative examples.

OPTIONS FOR IMPLEMENTING THE INVENTION

[0017]

Embodiments of tape cores in accordance with the present invention will now be described in detail. However, the present invention is not limited to the configurations disclosed in these embodiments, and can be modified in various ways without departing from the spirit of the present invention. The lower limits and upper limits are included in the numerical limit ranges described below. Numerical values expressed using the phrases “greater than” or “less than” are not included in the specified ranges. In addition, "%" referring to chemical composition means "% by weight" unless otherwise expressly stated.

In addition, the terms "parallel", "perpendicular", "identical" and "right angle", as well as the values of length and angle used in this description to define shapes, geometric conditions and their degrees, are not strictly bound meaning and should be interpreted as including the extent to which similar functions can be expected.

In addition, in this specification, "anisotropic electrical steel sheet" is sometimes simply described as "steel sheet" or "electrical steel sheet", and "tape core" is sometimes simply described as "core".

[0018]

The strip core according to one embodiment of the present invention is a strip core including: a substantially rectangular strip core body in a side view, which includes a portion containing anisotropic electrical steel sheets, in which flat portions and corner portions continuously alternated in the longitudinal direction, and the angle between two flat portions adjacent to each other with each of the corner portions therebetween being 90°, laid in the thickness direction of the sheet, and which has a substantially rectangular laminated structure in side view, each of the corner parts has two or more curved parts having a curved shape in the side view of anisotropic electrical steel sheets, the sum of the bending angles of the curved parts existing in one corner part is 90°, each curved part in the side view has an internal radius of curvature r of 1-5 mm , the anisotropic electrical steel sheets have a chemical composition containing, in wt.%, Si: 2.0-7.0%, with the balance of Fe and impurities, and have a texture oriented in the Goss orientation, with more than half of the measured values, obtained in many different positions along the thickness of the laminate, are 0.20-0.70 for the interlayer friction coefficients, which are the dynamic coefficients of friction of the laminate sheets of anisotropic electrical steel in at least some of the flat parts, and their average value is 0.20- 0.70.

[0019]

1. Shapes of strip cores and sheets of anisotropic electrical steel

First, the shapes of the tape cores in accordance with embodiments of the present invention will be described. The shapes of the anisotropic electrical steel strip cores and sheets described here are not particularly new. For example, these shapes simply correspond to the shapes of known anisotropic electrical steel strip cores and sheets described in prior art Patent Documents 8-10.

Fig. 1 is a perspective view schematically showing one embodiment of a strip core. Fig. 2 is a side view of the strip core shown in the embodiment of FIG. 1. In addition to this, FIG. 3 is a side view schematically showing another embodiment of a strip core.

In this description, the side view refers to a view in the width direction (in the Y-axis direction in FIG. 1) of the long anisotropic electrical steel sheets constituting the strip core, and the side view is a view (in the Y-axis direction in FIG. 1) showing the shape visible from the side.

[0020]

Band cores in accordance with embodiments of the present invention include a substantially rectangular band core body in side view. The main body of the strip core has a substantially rectangular laminated structure in a side view, in which the anisotropic electrical steel sheets are laid in the sheet thickness direction. The strip core body may be used as a strip core without modification, or may optionally have known locks such as strapping tape for jointly securing a plurality of stacked anisotropic electrical steel sheets.

[0021]

In this description, the length of the main body of the strip core is not particularly limited, but even if the length of the metal core changes, the volume of the bent parts is constant, so that the magnetic loss occurring in the bent parts remains constant. The longer the length of the metal core, the smaller the volume fraction of the curved parts, and therefore the smaller the impact on magnetic loss degradation. Accordingly, the length of the metal core is preferably 1.5 m or more, and more preferably 1.7 m or more. In the present invention, the length of the strip core body is the circumferential length of the strip core body at a center point in the lamination direction in a side view.

[0022]

In addition, in this specification, the thickness of the laminated steel sheets of the strip core body is not particularly limited. Since the effect of the present invention is believed to be caused by the uneven distribution of the excitation magnetic flux in the metal core depending on the thickness of the laminated steel sheets in the central region of the core, as will be described below, the advantages of the present invention are likely to be obtained in the metal core with a large thickness of laminated steel sheets , where uneven distribution is likely to occur. For this reason, the thickness of the laminated steel sheets is preferably 40 mm or more, and more preferably 50 mm or more. In the present invention, the thickness of the laminated steel sheets of the strip core body is the maximum thickness in the lamination direction at the flat portion of the strip core body in a side view.

[0023]

Although tape cores in accordance with embodiments of the present invention can also be suitably used for any of the conventionally known applications, they have significant advantages in metal cores for power transformers where noise is a problem.

[0024]

As shown in FIG. 1 and 2, the strip core main body 10 includes a portion in which the anisotropic electrical steel sheets 1, in which the first flat portions 4 and the corner portions 3 alternate continuously in the longitudinal direction, and the angle formed by the two first flat portions 4 adjacent to each of the corner portions 3 between them is 90°, laid in the thickness direction of the sheet, and has a substantially rectangular laminated structure 2 in a side view. In this specification, the “first planar portion” and the “second planar portion” may be referred to simply as the “planar portion.”

Each of the corner portions 3 of the anisotropic electrical steel sheets 1 has two or more bent portions 5 having a curved shape in the side view of the anisotropic electrical steel sheets, and the sum of the bending angles of the bent portions in one corner portion 3 is 90°. The corner portion 3 has a second flat portion 4a between adjacent curved portions 5, 5. Accordingly, the corner portion 3 has a configuration including two or more curved portions 5 and one or more second flat portions 4a.

The embodiment in FIG. 2 is a case in which one corner portion 3 has two curved portions 5. The embodiment in FIG. 3 is a case in which one corner portion 3 has three curved portions 5.

[0025]

As shown in these examples, in the present invention, one corner portion may be formed with two or more curved portions, but each of the bending angles ɸ (ɸ1, ɸ2 and ɸ3) of the curved portion 5 is preferably 60° or less, and more preferably 45° or less in terms of minimizing magnetic losses by minimizing the generation of stresses caused by deformation during processing.

In the embodiment of FIG. 2, in which one corner part has two curved parts, it is possible to set, for example, ɸ1=60° and ɸ2=30° or ɸ1=45° and ɸ2=45° from the point of view of reducing magnetic loss. Moreover, in the embodiment of FIG. 3, in which one corner portion has three curved portions, it is possible to set, for example, ɸ1=30°, ɸ2=30° and ɸ3=30° from the viewpoint of reducing magnetic loss. In addition, from the point of view of production efficiency, it is preferable that the bending angles be equal. Therefore, it is preferable to set ɸ1=45° and ɸ2=45° in the case where one corner part has two curved parts, and it is preferable to set, for example, ɸ1=30°, ɸ2=30° and ɸ3=30° from the point of view of reduction magnetic losses in the embodiment of FIG. 3, in which one corner portion has three curved portions.

[0026]

The curved portion 5 will be described in more detail with reference to FIG. 6. Fig. 6 is a diagram schematically showing one example of a bent portion (curved portion) of an anisotropic electrical steel sheet. The bending angle of the bent part means the angular difference between the front straight part and the rear straight part in the bending direction on the curved part of the anisotropic electrical steel sheet, and is expressed as angle ɸ, which is the complementary angle to the angle formed by the two virtual lines Lb-extent1 and Lb-extent2. obtained by extending the straight portions, which are the surfaces of the flat portions on both sides of the curved portion on the outer surface of the anisotropic electrical steel sheet.

Here, the point at which the extended straight line is separated from the surface of the steel sheet is the boundary between the flat part and the curved part on the outer surface of the steel sheet (points F and G in Fig. 6).

[0027]

In addition, straight lines perpendicular to the outer surface of the steel sheet respectively extend from points F and G, and their intersections with the inner surface of the steel sheet are point E and point D, respectively. Each of points E and D is the boundary between the flat part and the curved part on the inner surface of the steel sheet.

In this description, in the side view of the anisotropic electrical steel sheet, the bent portion is the part of the anisotropic electrical steel sheet surrounded by the above-mentioned points D, E, F and G. In FIG. 6, the surface of the steel sheet between point D and point E, that is, the inner surface of the curved portion, is designated as La, and the surface of the steel sheet between points F and G, that is, the outer surface of the curved portion, is designated as Lb. In addition, the intersection on arc DE inside the curved part of the steel sheet when points A and B are connected by a straight line is designated as C.

[0028]

In addition to this, the inner radius of curvature r in a side view of the curved portion 5 is shown in FIG. 6. The radius of curvature r of the curved part 5 is obtained by approximating the above La with an arc passing through point E and point D. A smaller radius of curvature r indicates a larger curvature of the curved part 5, and a larger radius of curvature r indicates a smaller curvature of the curved part 5.

In the strip core according to an embodiment of the present invention, the radius of curvature r in each curved portion 5 of each anisotropic electrical steel sheet 1 laminated in the sheet thickness direction can be varied to some extent. This variation may be a variation due to molding precision, and it is possible that unintentional variation may occur due to handling during blending. Such unintentional error can be minimized to approximately 0.2 mm or less in current normal industrial production. Where such variations are large, a representative value can be obtained by measuring the radius of curvature of a sufficiently large number of steel sheets and averaging them. In addition, it is possible to deliberately change the radius of curvature for some reasons, and the present invention does not exclude such a shape.

[0029]

The method for measuring the inner radius of curvature r of the curved portion 5 is not particularly limited, and the inner radius of curvature can be measured using a commercially available microscope (Nikon ECLIPSE LV150) with a magnification of 200x. In particular, the center point of curvature A is obtained from the observation results. As a way to achieve this, for example, if the intersection of line segment EF and line segment DG extended inward on the side opposite point B is defined as A, the size of the inner radius of curvature r corresponds to the length of line segment AC.

Herein, the noise of the strip core can be minimized by setting the inner radius of curvature r of the curved portion within the range of 1-5 mm and combining with a specific anisotropic electrical steel sheet with a controlled interlayer friction coefficient described below. The effect of the present invention is more pronounced when the inner radius of curvature r of the curved portion is preferably 3 mm or less.

In addition, it is most preferable that all curved portions existing in the core have an inner radius of curvature r as defined herein. In the case where there is a curved portion having an inner radius of curvature r according to an embodiment of the present invention, and a curved portion not satisfying the requirement of an inner radius of curvature r according to an embodiment of the present invention, it is desirable that at least half of the curved portions satisfied the inner radius of curvature r defined in the present invention.

[0030]

Fig. 4 and 5 are diagrams schematically showing one example of a single-layer anisotropic electrical steel sheet in a strip core body. As shown in the examples in FIGS. 4 and 5, the anisotropic electrical steel sheet used in the present invention is curved, has a corner portion 3 composed of two or more curved portions 5, and a flat portion 4, and forms a substantially rectangular ring in a side view through the connecting portion 6, which is the end surface of one or more sheets of anisotropic electrical steel in the longitudinal direction.

In this description, it is sufficient that the main part of the strip core has a laminated structure 2 that is generally substantially rectangular in side view. One sheet of anisotropic electrical steel can form one layer of the strip core body through one connecting part 6, as shown in the example of FIG. 4. Alternatively, one sheet of anisotropic electrical steel may form about half the circumference of the strip core, and two sheets of anisotropic electrical steel may constitute one layer of the main body of the strip core through two connecting parts 6, as shown in the example of FIG. 5.

[0031]

The thickness of the anisotropic electrical steel sheet used herein is not particularly limited, and may be suitably selected depending on applications and the like, but is generally within the range of 0.15-0.35 mm, and preferably within the range of 0 .18-0.23 mm.

[0032]

2. Configuration of anisotropic electrical steel sheets

Next, the configuration of the anisotropic electrical steel sheets constituting the main part of the strip core will be described. In this description, the anisotropic electrical steel sheets have features such as the interlayer friction coefficient between adjacent anisotropic electrical steel sheets, the magnetostriction λpp of the laminated anisotropic electrical steel sheets, the location of the anisotropic electrical steel sheets with controlled interlayer friction coefficient in the strip core, and the utilization coefficient in the strip core. the core of a sheet of anisotropic electrical steel with a controlled interlayer friction coefficient.

[0033]

(1) Interlayer friction coefficient of adjacent anisotropic electrical steel sheets

In the anisotropic electrical steel sheet constituting the strip core according to one embodiment of the present invention, the interlayer friction coefficient of the laminated steel sheets in at least some of the flat portions is 0.20 or more. If the interlayer friction coefficient of the flat parts is less than 0.20, the noise reduction effect of the core shaped according to the present embodiment is not exhibited.

Although the mechanism by which this phenomenon occurs is unclear, the need for this definition is thought as follows.

The target metal core of the present invention has a structure in which there are alternately arranged curved portions that are limited to very narrow regions and flat portions that are extremely wide regions compared to the curved portions. It is well known that when a metal core forming a closed magnetic circuit is excited, the magnetic flux in the core is unevenly distributed along the inner peripheral side of the closed magnetic circuit, so that the magnetic circuit becomes short. It is believed that when the target strip core of the present invention having such a structure is excited, the uneven distribution of magnetic flux in the core is also changed. For this reason, in the flat parts, a large difference occurs between the magnetic flux density on the inner peripheral side and the magnetic flux density on the outer peripheral side, and the magnetostriction amount also differs between the inner peripheral side and the outer peripheral side. Thus, in steel sheets laminated from the inner peripheral side to the outer peripheral side, adjacent steel sheets facing each other are physically deflected to create friction. It is believed that such friction does not have a particularly noticeable effect in a conventional strip core, in which the area of the flat parts is relatively small and the adjacent steel sheets are limited in shape by a smooth curvature around the entire circumference.

[0034]

On the other hand, in the target metal core of the present invention, which has a relatively large area of flat parts, the shape limitation has almost no effect on the flat parts. Therefore, it is believed that the effects caused by friction between adjacent steel sheets (adjacent anisotropic electrical steel sheets in the fusion direction) due to differences in magnetostriction (differences in magnetic flux density) occur to a large extent. One effect is noise, and in the ribbon core of the present embodiment, friction contributes significantly to noise. In this specification, noise is reduced by increasing the interlayer coefficient of friction, but this action is not considered to simply minimize the dimensional change caused by differences in magnetostriction of the steel sheets (anisotropic electrical steel sheets) due to friction. The reason for this is that minimizing the dimensional change caused by the difference in magnetostriction requires a very large frictional resistance, and forcing the minimization of the dimensional change also prevents the change in the structure of the magnetic domains, which can reduce the magnetic efficiency of the core. In fact, in this specification, even if the interlayer friction coefficient is increased in a suitable range that does not minimize dimensional change too much, the magnetic efficiency of the core does not decrease and even tends to increase. Considering these factors, it is believed that the effect of the present invention is that the kinetic energy of the anisotropic electrical steel sheets due to magnetostriction is consumed as thermal energy due to friction by increasing the interlayer friction coefficient, thereby reducing vibration energy, that is, noise. This can be interpreted to mean that the trend of increasing core efficiency also has the effect of reducing losses due to eddy magnetic losses by increasing the temperature of the steel sheets due to the thermal energy consumed and increasing the electrical resistance. Thus, the mechanism of action in this description may be very different from the usual one.

[0035]

It should be noted that since this description specifies a metal core, the interlayer friction coefficient of the anisotropic electrical steel sheets is not measured on the raw material for forming the core, but on the anisotropic electrical steel sheets obtained by disassembling the core. For the interlayer friction coefficient of anisotropic electrical steel sheets, in this specification, 10 sets of 3 sheets are randomly removed from the laminated steel sheets in the order of lamination (all steel sheets if the number of laminated steel sheets is less than 30 sheets), and the interlayer friction coefficient is determined from the interlayer friction coefficient , measured in the flat parts of each steel sheet. When samples are taken randomly, it is preferable to measure a representative state, which is preferable for expressing the effect of the present invention.

The central steel sheet is pulled by applying a load in the laminating direction to the contacting surfaces of three stacked steel sheets, and the interlayer friction coefficient is obtained from the relationship between the pulling force and the load in the laminating direction. In this specification, the load in the laminating direction is set to 1.96 N, the pulling speed is set to 100 mm/min, the change in the pulling force at the beginning of the relative deflection between the contact surfaces (which usually appears as the peak of the static friction force) is ignored, and the average value up to the first 60 mm after the start of the relative deflection is taken as the pulling force. Thus, the interlayer friction coefficient in this description is the dynamic friction coefficient.

The interlayer friction coefficient in this description is obtained by the formula (interlayer friction coefficient)=(pulling force)/1.96/2, where the pulling force is measured in N. Here “/2” takes into account the dynamic friction force of both surfaces acting on the drawn steel sheet . However, even if the friction coefficient for each surface is different, this is not taken into account, and the interlayer friction coefficient is estimated as the average interlaminar friction coefficient from both surfaces acting on the central steel sheet using the above equation.

It goes without saying that for the laminating order in the above dimension, the steel sheets are laid in the order of drawing from the iron core, and the drawing direction is the direction of magnetization in the iron core, that is, the direction from one curved part to another curved part across the flat part, and the rolling direction anisotropic electrical steel sheet, which is a material for a conventional metal core, in which a conventional anisotropic electrical steel sheet is used as a core material.

The size of each test piece is not particularly limited as long as it can be stretched under the conditions described above. However, since excessively high surface pressure on the contact surface also causes variations in the measured values, the contact surface area must be large enough considering the size of the steel sheets extracted from the iron core as the starting material, as well as the size of the test apparatus used for the above measurement. A sample generally useful using a tensile test has a width of approximately 20-150 mm and a length of approximately 50-400 mm. In addition, in order to stabilize the load distribution in the fusion direction on the contact surface during measurement, the size of the steel sheets surrounding the drawn-out center specimen should be significantly smaller than the size of the drawn-out center specimen, and the arrangement of the three steel sheets so that the contact surface area in The test time was constant with the size of the steel sheets surrounding the drawn central specimen being preferred to stabilize the test results. For example, in the case where the width of the three steel sheets is the same, and the length of the three steel sheets is 300mm, if the two outer steel sheets are cut into a length of 100mm, and the central steel sheet is clamped between the two steel sheets, the stable pulling force can be measured over a distance of more than 200 mm if the length of the gripping part for pulling the central sheet is neglected, while the contact area remains strictly constant at a width of 100 mm. However, it is believed that due to the size of the core from which the specimen is cut, device limitations, etc., it may be difficult to sustainably draw the specimen into the first 60 mm after the onset of relative deflection. In this case, it is acceptable to obtain the average pull-out force from measurement data at distances less than 60 mm. However, even in this case, the average pulling distance is preferably 10 mm or more. The above test conditions used in this description are in accordance with the JIS K7125: 1999 standard, and if there are conditions etc. necessary for more accurate measurement, the tests can be performed in accordance with the JIS K7125: 1999 standard.

The interlayer friction coefficient (interlayer friction coefficient of laminated anisotropic electrical steel sheets) is preferably 0.25 or more, and preferably 0.30 or more. The upper limit is set to 0.70 or less because it is necessary to control the range in which deflection of the steel sheets occurs. The upper limit is preferably 0.60 or less.

The interlayer friction coefficient according to an embodiment of the present invention is obtained as the average value of 10 sets of measurement values as described above. However, even if this average value is within the above-mentioned ranges, if individual measurement values are outside the above-mentioned ranges, situations may arise where the effect of the present invention cannot be obtained. For example, it is possible that 5 sets of measurement values are 0.10, 5 sets of measurement values are 0.90, and the average of all 10 sets is 0.50. In most cases, if steel sheets industrially produced to the same standard are laminated, the surface condition does not change much, and the fluctuation (variation) of the interlayer friction coefficient is in the range of a maximum of approximately 0.20, and therefore this situation can be ignored attention. However, the above situation may arise when multiple types of steel sheets with significantly different surface conditions are deliberately blended. Taking this point into account, in this specification, more than half of the measured interlaminar friction coefficient data should be within the numerical range suitable as average values. When obtaining the interlayer friction coefficient with 10 sets of measurement values, 5 or more sets of measurement values should be in the range of 0.20-0.70.

[0036]

(2) Arrangement of loaded elements (sheets of anisotropic electrical steel) with controlled interlayer friction coefficient

As described above, the effect of the present invention is caused by the difference in dimensional change due to the magnetostriction of the anisotropic electrical steel sheets laminated in their flat parts, the magnetostriction being caused by the uneven distribution of magnetic flux in the core. In principle, anisotropic electrical steel sheets laminated in all flat parts need not be in the friction state defined herein, and if even part of the phenomenon described herein occurs, a noise reduction can be expected. However, it is believed that in the case where its share is very small, the noise reduction also becomes small, that is, practically meaningless. Herein, considering such a situation, the interlayer friction coefficient of adjacently laminated anisotropic electrical steel sheets is determined as the average value of 10 sets randomly taken from the core as described above. Thus, in this specification, it is acceptable to have a region where the interlayer friction coefficient in the core is extremely low and the phenomenon used by the present invention hardly appears, and a region where the interlayer friction coefficient is sufficiently high and the phenomenon used by the present invention appears to a large extent.

In the case where such uneven distribution of interlayer friction coefficients is deliberately set, it is also possible to adopt a preferred shape regarding which region of the flat parts the structure of opposing anisotropic electrical steel sheets with a relatively high interlayer friction coefficient is placed. For example, as described above, the change rate of magnetic flux density due to the uneven distribution of magnetic flux, which also causes the effect of the present invention, increases towards the inner surface portion of the core. Thus, arranging the surfaces of anisotropic electrical steel sheets with a relatively high interlayer friction coefficient on the inner peripheral portion of the core is more effective in reducing noise than arranging them on the outer surface portion, and the effect of the present invention can be effectively obtained.

[0037]

In addition to this, in the present embodiment, it is preferable that in the flat portions, the proportion of the area where the steel sheets are in contact with an interlayer friction coefficient of 0.20 to 0.70 is 50% or more of the total area where the steel sheets are laminated and in contact with each other. with a friend. If this proportion is 50% or higher, sufficient noise reduction effect can be obtained for any strip core shape. This proportion is preferably 70% or higher, and it goes without saying that the best condition is that the interlayer friction coefficients of all contacting surfaces of the flat parts satisfy the definition of the present invention.

In addition, the preferred shape is determined in which area of the flat parts the structure is placed to satisfy the friction conditions defined herein. As described above, the change rate of magnetic flux density due to the uneven distribution of magnetic flux, which also causes the effect of the present invention, increases towards the inner surface portion of the core. Thus, contact surfaces that satisfy friction conditions are more effective in reducing noise when they are located on the inner peripheral portion of the core than on the outer surface portion. In the present embodiment, this arrangement is determined such that, in the flat portions, the interlayer friction coefficient of the laminated steel sheets is 0.20 to 0.70 in the region within 50% of the thickness of the laminated steel sheets on the inner side of the strip core. It is possible to effectively obtain the effect of the present invention by arranging them mainly on the inner side. Said proportion is preferably 70% or higher, and it goes without saying that the best condition is that the interlayer friction coefficients of all contacting surfaces of the thickness of the laminated steel sheets of the flat parts satisfy the definition of the present embodiment.

[0038]

(3) Anisotropic electrical steel sheets

With regard to the anisotropic electrical steel sheets used in this specification, although the standard deviations of the interlayer friction coefficient and magnetostriction λpp are limited to specific ranges, the base steel sheet, base coating structure, etc. may be the same as those of known anisotropic electrical steel sheets. As described above, the base steel sheet is a steel sheet in which the crystal grain orientations in the base steel sheet are highly concentrated in the {110}<001> orientation, and which has excellent magnetic properties in the rolling direction.

A known anisotropic electrical steel sheet can be used as a base steel sheet in this specification. Next, one example of a preferred base steel sheet will be described.

[0039]

(3-1) Chemical composition of base steel sheet

The base steel sheet has the following chemical composition, in wt.%: Si: from 2.0% to 7.0%, with the balance being Fe. This chemistry allows the crystal orientation to be controlled to a Goss texture concentrated in the {110}<001> orientation and provides favorable magnetic properties. Other elements are not particularly limited, and known elements may be contained in a known range instead of Fe. The content ranges of representative elements are as follows.

C: 0% to 0.070%,

Mn: 0% to 1.0%,

S: 0% to 0.0250%,

Se: 0% to 0.0150%,

Al: 0% to 0.0650%,

N: 0% to 0.0080%,

Cu: 0% to 0.40%,

Bi: 0% to 0.010%,

B: 0% to 0.080%,

P: 0% to 0.50%,

Ti: 0% to 0.0150%,

Sn: 0% to 0.10%,

Sb: 0% to 0.10%,

Cr: 0% to 0.30%,

Ni: 0% to 1.0%,

Nb: 0% to 0.030%,

V: 0% to 0.030%,

Mo: 0% to 0.030%,

Ta: 0% to 0.030%,

W: 0% to 0.030%.

Since these optional elements may be contained depending on the specific purpose, there is no need to limit them to a lower limit, and therefore the optional elements may not be substantially contained. In addition to this, even if these optional elements are contained as impurities, the effect of the present invention is not impaired. Impurities refer to elements that are unintentionally contained and mean elements that enter the steel from ore, scrap metal, industrial environment, etc. in the industrial production of basic steel sheet.

[0040]

The chemical component of the base steel sheet can be measured using a conventional analytical method for steel. For example, the chemical component of a base steel sheet can be measured using inductively coupled plasma atomic emission spectrometry (ICP-AES). Specifically, the chemical composition can be determined, for example, by taking a 35 mm square test piece from the center position of the base steel sheet and performing a measurement with an ICPS-8100 measuring instrument manufactured by Shimadzu Corporation or the like. based on a calibration curve prepared in advance. The C and S contents can be measured by the infrared ray absorption method of a flame, and the N contents can be measured by the inert gas melting thermal conductivity method.

[0041]

The above chemical composition is the composition of the base steel sheet. In the case where the anisotropic electrical steel sheet used as a measurement sample has on its surface, for example, an insulating coating and a primary coating (such as a glass coating or an intermediate layer) made of an oxide or the like, a chemical composition measured after removing this coating, etc. by known methods.

[0042]

(3-2) Magnetostriction of anisotropic electrical steel sheets

The anisotropic electrical steel sheets used in the metal core according to an embodiment of the present invention have a feature such as an interlayer friction coefficient (interlayer friction coefficient of laminated anisotropic electrical steel sheets) as described above. Next, another important characteristic related to expressing the effect of the present invention will be described. As described above, the effect of the present invention is caused by the difference in the amount of magnetostriction between the anisotropic electrical steel sheets laminated with each other. The above explanation describes that one of the reasons for the difference in the magnetostriction amount is the non-uniform magnetic flux density, but the reason for this is also the variation in the magnetostrictive properties of the produced steel sheets, and this can also be used. In this specification, it is determined by the standard deviation of the magnetostriction λpp of the laminated anisotropic electrical steel sheets, and the standard deviation of the magnetostriction is 0.01×10 ^-6 - 0.10×10 ^-6 .

[0043]

In the case where the standard deviation of magnetostriction λpp is zero, the deviation of adjacent laminated steel sheets is caused only by the non-uniform magnetic flux density. However, if the standard deviation is significant, in addition to the non-uniform magnetic flux density, the difference in the magnitude of magnetostriction itself causes the adjacent laminated steel sheets to deflect, which reduces the noise. The lower limit that causes a significant difference is preferably 0.01×10 ^-6 or more. More preferably, the lower limit is 0.03×10 ^-6 or more.

[0044]

On the other hand, in the case where one tries to increase the standard deviation of magnetostriction λpp, since the lower limit of magnetostriction λpp is zero, there is no other choice but to increase the magnetostriction λpp of steel sheets with larger magnetostriction λpp. An increase in magnetostriction λpp of steel sheets laminated in this way leads to an increase in noise. To avoid this, it is preferable to set the upper limit to 0.10×10 ^-6 or less. More preferably, the upper limit is 0.08×10 ^-6 or less.

[0045]

It should be noted that if steel sheets having different magnetostrictive properties are arranged according to non-uniform magnetic flux density, the effect of the present invention is unlikely to be achieved. For example, if a steel sheet with low magnetostriction λpp is placed on the inside where the magnetic flux density is high, and a steel sheet with high magnetostriction λpp is placed on the outside where the magnetic flux density is low, regardless of the fact that the standard deviation of the magnetostriction λpp is within the scope of the present invention, the effect of the present invention can be reduced compared to the case where the standard deviation of magnetostriction λpp is zero. However, arranging steel sheets having variations in magnetostriction λpp in accordance with variations in magnetic flux density in this manner requires a lot of time and effort, which is not realistic. The standard deviation of the magnetostriction λpp in this specification is determined from the characteristic magnetostriction values λpp measured in the flat portions of each steel sheet obtained by randomly removing a plurality of stacked steel sheets. As for the plurality of sheets, for example, 20 sheets are taken out (all steel sheets in the case where the number of laminated steel sheets is less than 20). By randomly extracting samples in this manner, random arrangement as described above can be eliminated, and representative conditions preferable for exhibiting the effect of the present invention can be determined.

[0046]

(4) Method for producing anisotropic electrical steel sheet

The method for producing anisotropic electrical steel sheet is not particularly limited, and the conventionally known method for producing anisotropic electrical steel sheet can be suitably selected. Preferable specific examples of the production method include a method in which a slab containing 0 to 0.070 mass% C and otherwise having the chemical composition of the above-mentioned anisotropic electrical steel sheet is heated to 1000°C or higher to perform hot rolling, and then hot annealing is carried out as necessary, the cold rolled steel sheet is then obtained by cold rolling one, two or more times, including intermediate annealing, heated at 700°C - 900°C, for example, in a humid atmosphere of hydrogen and inert gas, subjected to decarburization annealed, further subjected to nitriding annealing as required, and subjected to final annealing at approximately 1000°C after applying an annealing separator to the nitriding annealed cold rolled steel sheet to form an insulating coating at a temperature of approximately 900°C. In addition, a coating can then be applied to adjust the friction coefficient of the intermediate layer.

In addition to this, the effect of the present invention can be obtained even with a steel sheet that has been subjected to a treatment called "magnetic domain control" in the steel sheet manufacturing process in a known manner.

[0047]

The interlayer friction coefficient, which is a feature of the anisotropic electrical steel sheet used herein, is controlled by the type of coating and the surface condition such as surface roughness. The method is not particularly limited, and a known method may be used according to circumstances. For example, the roughness of the base steel sheet can be controlled by suitable control of the roll roughness when producing hot-rolled steel sheet and cold-rolled steel sheet, as well as by grinding the surface of the base steel sheet and chemical etching. In addition to this, other examples of this include a method of increasing the baking temperature of the coating or increasing the baking time in order to promote the surface smoothness of the glass coating, reduce roughness and increase the contact surface between steel sheets to increase the static coefficient of friction. As a result, the interlayer friction coefficient increases and slippage can be reduced.

In fact, it may be necessary to control the interlayer friction coefficient to a desired level while monitoring the surface condition of the steel sheets actually produced as samples, and it would not be difficult for one skilled in the art to control the surface condition of the products on a daily basis when performing rolling or surface treatment.

In addition to this, the timing of processing for controlling the interlayer friction coefficient is not particularly limited. It is believed that the above-mentioned rolling, chemical pickling and coating baking can be carried out according to circumstances in conventional processes for producing anisotropic electrical steel sheets. The method is not limited to this, and it is possible, for example, to apply any lubricant by spraying or by applying a roller or the like. when choosing the time immediately before or immediately after bending in the process of cutting steel sheets and producing elements of bent steel sheets loaded into the core. In addition to this, it is also possible to position the rolling roll just before bending and change the surface roughness by light rolling to control the interlayer friction coefficient.

[0048]

3. Method for producing strip core

The method for producing a strip core according to the present embodiment is not particularly limited as long as it can produce a strip core according to the present invention, and, for example, methods in accordance with known strip cores described in Patent Documents 8 to 10 in the prior art can be applied. technology. In particular, it can be mentioned that the method using the UNICORE production device (registered trademark: https://www.aemcores.com.au/technology/unicore/) of AEM UCORE is optimal.

[0049]

Moreover, heat treatment can be performed as necessary according to a known method. In addition, the resulting strip core body can be used as a strip core without modification, or can be used as a strip core obtained by integrally locking a plurality of stacked anisotropic electrical steel sheets using a known lock such as strapping tape.

[0050]

The embodiments of the present invention are not limited to those described above. The above-described embodiments are examples, and any shape which has substantially the same configuration as the technical idea described in the claims and showing the same operating effects is also included within the scope of this description.

[Examples]

[0051]

In the following, technical details will be further described with reference to examples of the present invention. The conditions in the examples shown below are examples of conditions used to confirm the feasibility and effect of the present invention, and the present invention is not limited to these example conditions. In addition, this specification may use various terms as long as the object of the present invention is achieved without deviating from the spirit of the present invention.

[0052]

(Anisotropic electrical steel sheets)

A slab having the chemical composition shown in Table 1 (in wt.%, with the rest being Fe) was used as a material to produce a final product having the chemical composition (in wt.%, with the rest being Fe) shown in Table 2.

In Tables 1 and 2, “-” means that the item was not used, the item was not controlled, and thus its content was not measured. In addition, “<0.002” and “<0.004” mean that the item was controlled with an understanding of the content, the content was measured, but sufficiently accurate measurement values (detection limit or less) were not obtained.

[0053]

[Table 1]

Steel type Slab C Si Mn S Al N Cu Bi Nb A 0.070 3.26 0.07 0.025 0.026 0.008 0.07 - - B 0.070 3.26 0.07 0.025 0.026 0.008 0.07 - 0.007 C 0.070 3.26 0.07 0.025 0.025 0.008 0.07 0.002 - D 0.060 3.45 0.10 0.006 0.027 0.008 0.20 - 0.005

[0054]

[Table 2]

Steel type Final product C Si Mn S Al N Cu Bi Nb A 0.001 3.15 0.07 <0.002 <0.004 <0.002 0.07 - - B 0.001 3.15 0.07 <0.002 <0.004 <0.002 0.07 - 0.005 C 0.001 3.15 0.07 <0.002 <0.004 <0.002 0.07 0.002 - D 0.001 3.34 0.10 <0.002 <0.004 <0.002 0.20 - -

[0055]

The production process corresponds to the production conditions for well-known anisotropic electrical steel sheets.

Specifically, hot rolling, hot annealing, and cold rolling were performed. Some of the cold rolled steel sheets after decarburization annealing have been subjected to nitriding treatment (nitriding annealing) in a mixed atmosphere of hydrogen, nitrogen and ammonia. In addition, to control the magnetic domain, periodic linear grooves were formed on the surfaces of steel sheets by laser irradiation.

In addition, an annealing separator consisting mainly of MgO was applied and final annealing was performed. An insulating coating solution containing chromium and consisting primarily of phosphate and colloidal silica was applied to primary coatings formed on the surfaces of final annealed steel sheets and heat treated to form the insulating coating.

[0056]

Regarding the interlayer friction coefficient, the degree of surface smoothness (roughness) of the glass insulating coating that will be the final outer surface was controlled using a known technique, for example, by changing the diameter of the oxide particles added to the annealing separator, or by changing the baking temperature and time when forming the insulating coating in order to adjust the interlayer friction coefficient.

In addition, for some materials, epoxy resins with different viscosities were applied at 2 g/m ² and baked at 200°C in order to form surface films with different interlayer friction coefficients.

In addition, the variation of magnetostriction λpp was controlled by adjusting the sampling position of the anisotropic electrical steel coil used to create the core. There are variations in the magnetostriction λpp in commercially produced anisotropic electrical steel coils, for example due to variations in crystal orientation, especially the rotation angle β about a direction orthogonal to the rolling direction of the steel sheets, which is specifically called the "split angle" due to the properties of the coil ( curvature in rolls: curvature increases towards the inner circumference) during secondary recrystallization; variations in tension during heat treatment to form an insulating coating; or permanent deformation due to handling of the rolls. Such variations are small in small areas of the roll, but are large when considering the entire length of the roll, for example from the top to the bottom. In this example, not only was a core with a small variation in magnetostriction λpp produced using only sheets taken from a small area, but also a core with a large variation in magnetostriction λpp was produced using sheets taken from the entire roll, from the top to the bottom.

Various properties of anisotropic electrical steel sheets used as core materials and anisotropic electrical steel sheets taken from the cores were measured using the following technique. The properties of the anisotropic electrical steel sheets are shown in Table 3 for an experiment in which the interlayer friction coefficient was controlled, and in Table 4 for an experiment in which variations in magnetostriction λpp were controlled. In Tables 3, 4, 6 and 7, the “interlayer friction coefficient” is referred to as “friction coefficient” for brevity.

[0057]

[Table 3]

Steel Sheet No. Steel type Hot rolling Hot annealing Cold rolling Decarburizing annealing Nitriding Final annealing Magnetic domain management Friction coefficient control Properties Heating temperature Finish temperature Rewinding temperature Sheet thickness Temperature Time Sheet thickness Cold rolling coefficient Heating temperature Time Temperature Time B8 Magnetostriction λpp Friction coefficient °C °C °C mm °C With mm % °C With °C hour Tl ×10 ^-6 - A1 A 1150 900 540 2.9 1100 180 0.35 87.9 800 180 Made 1100 50 No Controlled by the particle diameter of the raw material for the annealing separator 1.91 0.63 0.09 A2 A 1150 900 540 2.9 1100 180 0.35 87.9 800 180 1100 50 1.90 0.66 0.16 A3 A 1150 900 540 2.9 1100 180 0.35 87.9 800 180 1100 50 1.92 0.60 0.27 A4 A 1150 900 540 2.9 1100 180 0.35 87.9 800 180 1100 50 1.91 0.66 0.66 B1 B 1150 880 650 2.5 1150 180 0.23 90.8 750 180 Made 1100 50 Made Controlled by the heat treatment time and temperature of forming the insulation coating 1.93 0.33 0.05 B2 B 1150 880 650 2.5 1150 180 0.23 90.8 750 180 1100 50 1.94 0.28 0.12 B3 B 1150 880 650 2.5 1150 180 0.23 90.8 750 180 1100 50 1.92 0.32 0.20 B4 B 1150 880 650 2.5 1150 180 0.23 90.8 750 180 1100 50 1.95 0.31 0.35 C1 C 1150 900 750 2.8 1100 120 0.26 90.7 850 180 Made 1150 60 No Controlled by the viscosity of the epoxy coating material 1.92 0.51 0.02 C2 C 1150 900 750 2.8 1100 120 0.26 90.7 850 180 1150 60 1.93 0.56 0.18 C3 C 1150 900 750 2.8 1100 120 0.26 90.7 850 180 1150 60 1.93 0.55 0.31 C4 C 1150 900 750 2.8 1100 120 0.26 90.7 850 180 1150 60 1.94 0.48 0.64 D1 D 1350 930 540 2.7 1050 180 0.26 90.4 850 180 No 1100 70 No Controlled by the heat treatment time and temperature of forming the insulation coating 1.93 0.54 0.12 D2 D 1350 930 540 2.7 1050 180 0.26 90.4 850 180 1100 70 1.92 0.48 0.18 D3 D 1350 930 540 2.7 1050 180 0.26 90.4 850 180 1100 70 1.91 0.56 0.26 D4 D 1350 930 540 2.7 1050 180 0.26 90.4 850 180 1100 70 1.94 0.51 0.33

[0058]

[Table 4]

Steel Sheet No. Steel type Hot rolling Hot annealing Cold rolling Decarburization annealing Nitriding Final annealing Magnetic domain management Properties Heating temperature Finish temperature Rewinding temperature Sheet thickness Temperature Time Sheet thickness Cold rolling coefficient Heating temperature Time Temperature Time B8 Magnetostriction λpp Magnetostriction standard deviation Friction coefficient °C °C °C mm °C With mm % °C With °C hour Tl ×10 ^-6 ×10 ^-6 - A11 A 1150 900 540 2.9 1100 180 0.35 87.9 800 180 Made 1100 50 No 1.92 0.63 0.06 0.22 A12 A 1150 900 540 2.9 1100 180 0.35 87.9 800 180 1100 50 1.90 0.60 0.08 0.22 A13 A 1150 900 540 2.9 1100 180 0.35 87.9 800 180 1100 50 1.91 0.63 0.12 0.22 A14 A 1150 900 540 2.9 1100 180 0.35 87.9 800 180 1100 50 1.90 0.59 0.19 0.22 B11 B 1150 880 650 2.5 1150 180 0.23 90.8 750 180 Made 1100 50 Made 1.93 0.31 0.05 0.32 B12 B 1150 880 650 2.5 1150 180 0.23 90.8 750 180 1100 50 1.94 0.32 0.09 0.32 B13 B 1150 880 650 2.5 1150 180 0.23 90.8 750 180 1100 50 1.95 0.28 0.14 0.32 B14 B 1150 880 650 2.5 1150 180 0.23 90.8 750 180 1100 50 1.93 0.31 0.16 0.32 D11 D 1350 930 540 2.7 1050 180 0.26 90.4 850 180 No 1100 70 No 1.93 0.53 0.02 0.26 D12 D 1350 930 540 2.7 1050 180 0.26 90.4 850 180 1100 70 1.91 0.51 0.06 0.26 D13 D 1350 930 540 2.7 1050 180 0.26 90.4 850 180 1100 70 1.93 0.51 0.11 0.26 D14 D 1350 930 540 2.7 1050 180 0.26 90.4 850 180 1100 70 1.94 0.51 0.14 0.26

[0059]

(Metal core)

Tape cores a - e having the shapes shown in Table 5 and FIG. 7, were produced using each steel sheet as the material.

L1 is parallel to the X-axis direction and is the distance between the parallel anisotropic electrical steel sheets 1 at the innermost periphery of the strip core in the flat cross section including the center CL (distance between the inner flat parts). Flat parts refer to linear parts, different from curved parts. L2 is parallel to the Z-axis direction and is the distance between the parallel anisotropic electrical steel sheets 1 at the innermost periphery of the strip core in the vertical cross section including the center CL (the distance between the inner flat parts). L3 is parallel to the X-axis direction and is the lamination thickness (thickness in the lamination direction) of the strip core in a flat cross section including the center CL. L4 is parallel to the X-axis direction and is the width of the laminated steel sheets of the strip core in a flat cross section including the center CL. L5 is the distance between flat parts (distance between curved parts) that are adjacent to each other in the innermost part of the strip core and together form a right angle. In other words, L5 represents the shortest length of the flat portions 4a in the longitudinal direction between the flat portions 4, 4a of the anisotropic electrical steel sheet at the innermost periphery. r represents the radius of curvature of the curved portion on the inner side of the strip core, and ɸ represents the bending angle of the curved portion of the strip core. The substantially rectangular cores a - e, in which the flat parts having a distance L1 between the inner flat parts are separated approximately at the center of the distance L1, have a structure in which two cores having a substantially U-shape are connected. Here, the core e is a core that is traditionally used as an ordinary strip core, and is produced by a method in which steel sheets are cut and then wound into a cylindrical shape, the corner parts of the cylindrical laminated body are then compressed so that they have a constant curvature, and the cylindrical the laminate body is formed into a substantially rectangular shape and then annealed to maintain that shape. For this reason, the radius of curvature of the curved part varies significantly depending on the position of the steel sheets being laminated. r in Table 5 means r on the innermost surface. r increases in the outward direction and is approximately 70 mm at the outermost peripheral part.

[0060]

[Table 5]

Core No. Core shape L1 L2 L3 L4 L5 r ɸ mm mm mm mm mm mm ° a 197 66 45 150 16 1 45 b 197 66 45 150 18 2 45 c 197 66 45 150 20 3 45 d 197 66 55 150 20 2 thirty e 197 66 45 150 - 15 90

[0061]

(Evaluation method)

(1) Magnetic properties of anisotropic electrical steel sheet

The magnetic properties of anisotropic electrical steel sheet were measured by the Single Sheet Tester (SST) method defined in JIS C 2556:2015. Each property was measured at a total of 20 points, including 5 positions on the longitudinal side (1/10, 3/10, 5/10, 7/10 and 9/10 of the full length) of the long electrical steel sheet unwound from the produced coil, and 4 positions in the width direction (1/5, 2/5, 3/5 and 4/5 of the width) at each of the positions on the longitudinal side, and their average value was taken as the property of the steel sheet. In addition to this, the standard deviation of magnetostriction λpp was obtained from these measured values at 20 points.

The electrical steel sheet to be measured has a width equal to or greater than the width of a single sheet (electrical steel sheet) used in the single sheet magnetic testing (SST) method.

[0062]

(2) Interlayer friction coefficient of anisotropic electrical steel sheets (materials)

The interlayer friction coefficient of the anisotropic electrical steel sheets was obtained in essentially the same manner as the interlayer friction coefficient of the anisotropic electrical steel sheets laminated into a core as described above. However, sample collection was performed as follows. First, 20 steel sheets with a length in the width direction of 50 mm and a length in the rolling direction of 350 mm were cut at the above 20 positions (20 points), from which 18 sheets were randomly selected, and they were further divided into 6 sets of 3 sheets. For each set, one sheet was considered as a drawing sample, and the other two sheets were considered as enclosing samples, adjusting the size of the sheets in the rolling direction to be 100 mm. The 50 mm end portion of the drawn specimen in the rolling direction was considered as a gripping part, the adjacent part was clamped between the female specimens, and a load of 1.96 N was uniformly applied to the female specimens. When the drawn sample was pulled in this state, the change in the pulling force changed after approximately 200 mm. Then, the change in pullout force at the start of the relative deflection between the contact surfaces was not taken into account, and the average pullout force at a pullout distance of 60 mm from 30 to 90 mm after the start of the relative deflection was used as the pullout force in the one set test to obtain the interlayer friction coefficient for each set. In addition, the average value of the interlayer friction coefficients for 6 sets was considered as the interlayer friction coefficient of the anisotropic electrical steel sheets.

[0063]

As magnetic properties, the magnetic flux density B8 (T) of the steel sheet in the rolling direction when excited by a current with a density of 800 A/m and the magnetostriction range at an alternating current frequency of 50 Hz and an excitation magnetic flux density of 1.7 T were measured.

(3) Noise characteristics of the metal core

The noise of each metal core was measured based on the IEC60076-10 method, which determines the number of microphones, their location, the distance between the microphones and the core, etc. during noise measurement.

[0064]

(4) Interlayer friction coefficient of anisotropic electrical steel sheets laminated into a core

The interlayer friction coefficient of sheets of anisotropic electrical steel laminated into a core was obtained as follows. The core was disassembled, 10 sets of 3 sheets each were randomly selected in order of fusion from the laminated steel sheets, and a total of 60 steel sheets having a rolling direction length of 90 mm and a width of 80 mm from the center portion in the width direction were cut from flat parts for which the above-mentioned distance between the inner flat parts was L1. In addition, for each set, one sheet at the center of the batch was considered as a drawing sample, and the other two sheets were considered as surrounding samples, adjusting the length of the sheets in the rolling direction to 10 mm. The 20 mm end portion of the drawn specimen in the rolling direction was considered as a gripping part, the adjacent part was clamped between the female specimens, and a load of 1.96 N was uniformly applied to the female specimens. When the drawn sample was pulled in this state, the change in the pulling force after approximately 60 mm changed. Then, the change in the pulling force at the beginning of the relative deflection between the contact surfaces was not taken into account, and the average value of the pulling force at a pulling distance of 40 mm from 10 to 50 mm after the start of the relative deflection was used as the pulling force in the one set test to obtain the interlayer friction coefficient for each set. In addition, the average value of the interlayer friction coefficients for 10 sets was considered as the interlayer friction coefficient of the anisotropic electrical steel sheets laminated in the core. In addition, the number of measurement values in the range of 0.20-0.70 out of 10 measurement values for each core was obtained.

(5) Magnetostriction λpp of anisotropic electrical steel sheets laminated into a core and its standard deviation

The standard deviation of magnetostriction λpp of sheets of anisotropic electrical steel laminated into a core was obtained as follows. The core was disassembled, 20 steel sheets were randomly selected from the laminated steel sheets, and their flat parts were cut out and used as samples. For these samples, the magnetostriction peak-to-peak was measured at an alternating current frequency of 50 Hz and an excitation magnetic flux density of 1.7 Tesla. The average value for these 20 sheets was considered as the magnetostriction λpp of the anisotropic electrical steel sheets laminated into the core, and its standard deviation was obtained.

[0065]

(Example 1)

The noise was evaluated in different cores manufactured using different steel sheets having different interlaminar friction coefficients. In addition, each core was disassembled, and the interlayer friction coefficient of laminated anisotropic electrical steel sheets was obtained. The results are shown in Table 6. It can be observed that even when materials of the same steel type are used, having substantially the same magnetostriction λpp, the noise of the cores can be reduced by suitable control of the interlayer friction coefficient.

In addition to this, Table 6 shows examples (Test Nos. 1-25 to 1-28) in which steel sheets that have significantly different interlayer friction coefficients and showed significant differences in noise when the core shape conforms to the present invention , are used as materials to produce a core (core e) having a larger radius of curvature of the curved part. Core e is a core that is traditionally used as a conventional strip core and is produced by a method in which steel sheets are wound into a cylindrical shape, then the corner portions of the cylindrical laminate body are compressed so that they have a constant curvature, and the cylindrical laminate body is formed substantially in rectangular shape and then annealed to relieve stress and maintain shape. In these cases, stress relief annealing is performed at 700°C for 2 hours. In the table, the property values of the steel sheets obtained by disassembling the core are indicated by "-", which means that the shapes of the steel sheets obtained by disassembling the core e were obtained by heat treatment and the application of deformation in the above production process, and therefore the suitable property values could not be received. In these cases, although the noise itself is reduced by final stress-relieving annealing, it can be noted that the effect of the present invention cannot be expected even if at least the interlayer friction coefficient of the original steel sheet changes significantly.

[0066]

[Table 6]

Test No. Steel Sheet No. Core No. Properties of the metal core Notes Magnetostriction Friction coefficient Number of sets between 0.20 and 0.70 Noise ×10 ^-6 Of 10 sets dB 1-1 A1 a 0.66 0.13 0 32.6 Comparative example 1-2 A2 a 0.66 0.18 3 33.2 Comparative example 1-3 A3 a 0.65 0.30 10 27.6 Example according to the invention 1-4 A4 a 0.67 0.67 7 25.3 Example according to the invention 1-5 B1 a 0.33 0.08 0 33.1 Comparative example 1-6 B2 a 0.36 0.15 0 31.6 Comparative example 1-7 B3 a 0.35 0.24 9 26.1 Example according to the invention 1-8 B4 a 0.35 0.37 10 26.3 Example according to the invention 1-9 C1 a 0.55 0.02 0 32.6 Comparative example 1-10 C2 a 0.56 0.21 7 26.8 Example according to the invention 1-11 C3 a 0.60 0.33 10 27.1 Example according to the invention 1-12 C4 a 0.52 0.68 6 24.6 Example according to the invention 1-13 D1 a 0.57 0.12 2 33.3 Comparative example 1-14 D2 a 0.54 0.22 8 27.3 Example according to the invention 1-15 D3 a 0.56 0.27 10 26.9 Example according to the invention 1-16 D4 a 0.55 0.36 10 27.6 Example according to the invention 1-17 A1 b 0.66 0.09 1 32.5 Comparative example 1-18 A3 b 0.66 0.27 9 27.6 Example according to the invention 1-19 B1 b 0.34 0.05 0 33.1 Comparative example 1-20 B3 b 0.34 0.20 5 28.5 Example according to the invention 1-21 C1 c 0.57 0.02 0 33.3 Comparative example 1-22 C3 c 0.58 0.58 10 24.6 Example according to the invention 1-23 D1 d 0.55 0.08 1 31.6 Comparative example 1-24 D3 d 0.59 0.29 10 25.3 Example according to the invention 1-25 A1 e - - - 31.2 Comparative example 1-26 A3 e - - - 31.9 Comparative example 1-27 B1 e - - - 29.8 Comparative example 1-28 B3 e - - - 29.4 Comparative example

[0067]

(Example 2)

The noise was evaluated in different cores manufactured using different steel sheets having different interlaminar friction coefficients, magnetostriction λpp and magnetostriction standard deviations λpp. In addition, each core was disassembled, and the interlayer friction coefficient, magnetostriction λpp, and standard deviation of magnetostriction λpp of laminated anisotropic electrical steel sheets were obtained. The results are shown in Table 7. It can be observed that the noise of the cores can be reduced by optimizing the standard deviation of magnetostriction λpp in addition to the interlayer friction coefficient.

[0068]

[Table 7]

Test No. Steel Sheet No. Core No. Properties of the metal core Notes Magnetostriction Magnetostriction standard deviation Friction coefficient Number of sets between 0.20 and 0.70 Noise ×10 ^-6 ×10 ^-6 Of 10 sets dB 2-1 A11 c 0.65 0.07 0.22 8 23.9 Example according to the invention 2-2 A12 c 0.65 0.08 0.24 9 23.1 Example according to the invention 2-3 A13 c 0.65 0.13 0.23 8 26.4 Example according to the invention 2-4 A14 c 0.63 0.19 0.22 9 26.8 Example according to the invention 2-5 B11 c 0.33 0.05 0.33 10 23.7 Example according to the invention 2-6 B12 c 0.37 0.09 0.33 10 23.6 Example according to the invention 2-7 B13 c 0.28 0.14 0.34 10 26.0 Example according to the invention 2-8 B14 c 0.36 0.17 0.34 10 26.1 Example according to the invention 2-9 D11 c 0.56 0.03 0.26 10 23.1 Example according to the invention 2-10 D12 c 0.60 0.06 0.28 10 23.5 Example according to the invention 2-11 D13 c 0.60 0.12 0.26 10 26.2 Example according to the invention 2-12 D14 c 0.61 0.15 0.27 10 26.7 Example according to the invention 2-13 B11 a 0.34 0.05 0.34 10 23.4 Example according to the invention 2-14 B13 a 0.31 0.15 0.33 10 26.7 Example according to the invention 2-15 D11 d 0.65 0.04 0.27 10 22.2 Example according to the invention 2-16 D13 d 0.68 0.13 0.28 10 24.6 Example according to the invention

[0069]

From the above results, it can be seen that in the strip core of the present invention, more than half of the measurement values obtained at a variety of different laminated thickness positions are in the range of 0.20-0.70 for the interlayer friction coefficients of at least some anisotropic electrical steel sheets laminated at least least in some flat parts, their average value is 0.20-0.70, and the standard deviation of magnetostriction λpp of anisotropic electrical steel sheets is
0.01×10 ^-6 - 0.10×10 ^-6 , and therefore the generation of noise caused by the combination of the steel sheets used and the shape of the metal cores can be effectively minimized.

INDUSTRIAL APPLICABILITY

[0070]

According to each of the aspects of the present invention, in a strip core formed by laminating curved anisotropic electrical steel sheets, the generation of noise caused by the combination of the shape of the metal core and the steel sheets used can be effectively minimized. Accordingly, industrial applicability is significant.

BRIEF DESCRIPTION OF REFERENCE SYMBOLS

[0071]

1 - sheet of anisotropic electrical steel

2 - laminated structure

3 - corner part

4 - first flat part (flat part)

5 - curved part

6 - connecting part

10 - main part of the strip core

Claims (12)

1. A strip core comprising a substantially rectangular strip core body in side view, wherein the main body of the strip core includes a portion of anisotropic electrical steel sheets in which flat portions and corner portions alternate continuously in the longitudinal direction, and an angle formed by two adjacent flat portions with each of the corner portions therebetween , is 90°, is laid in the direction of the sheet thickness, and has a substantially rectangular laminated structure in side view, wherein each of the corner portions has two or more curved portions having a curved shape in a side view of the anisotropic electrical steel sheets, and the sum of the bending angles of the curved portions in one corner portion is 90°, in which each curved part in side view has an internal radius of curvature r equal to 1-5 mm, in which sheets of anisotropic electrical steel have chemical composition containing, in wt.%, Si: 2.0-7.0%, with the remainder of Fe and impurities, and texture oriented in Goss orientation, and wherein more than half of the measured values obtained at a variety of different positions along the thickness of the laminate are 0.20-0.70 for interlayer friction coefficients, which are the dynamic coefficients of friction of the laminate anisotropic electrical steel sheets in at least some of the flat portions, and their average value is 0.20-0.70. 2. Tape core according to claim 1, in which the standard deviation of magnetostriction λpp of sheets of anisotropic electrical steel, determined by the range of the magnetostriction value measured on flat areas of each of a plurality of randomly selected sheets of anisotropic electrical steel, taken from laminated sheets of anisotropic electrical steel, is 0.01 × 10 ^-6 - 0.10 ×10 ^-6 . 3. Tape core according to claim 1 or 2, in which the interlayer friction coefficient of the laminated sheets of anisotropic electrical steel in the region within 50% of the thickness of the laminated sheets of anisotropic electrical steel from the inner side of the strip core in the flat parts is 0.20-0.70.