JP2006257527A - Method for producing grain-oriented magnetic steel sheet and device for reducing core loss in grain-oriented magnetic steel sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a grain-oriented magnetic steel sheet by which a low core loss grain-oriented magnetic steel sheet suitable for a stacked-core transformer or for a ribbon-core transformer can be produced with little variation in magnetic properties, and to provide an core reduction device. <P>SOLUTION: With the use of a core loss reduction device provided with: a thin cylindrical drum around which a transported grain-oriented magnetic steel sheet being the material to be projected can be wound, and which is freely rotatably arranged and has a plurality of slits elongating axially on a circumferential face; planet rolls for supporting the drum from the inside; and a solid grain projecting device for projecting solid grains from the inside of the drum through the slits onto the material to be projected, after a cold rolling step where the steel sheet is made into a cold rolled sheet with a final sheet thickness, the continuously transported cold rolled sheet is subjected to a strain introduction part or linear groove imparting step in which the continuously transported cold rolled sheet is wound around the thin cylindrical drum, solid grains are projected from the inside of the drum through the slits onto the surface of the cold rolled sheet, and the surface of the cold rolled sheet is given linear strain introduction parts or linear grooves. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a low iron loss grain-oriented electrical steel sheet, and more particularly, to a method for introducing strain or grooves in a linear shape and a device improvement for reducing iron loss.

  Oriented electrical steel sheets are mainly used as iron core materials for transformers and the like, and are required to have good magnetic characteristics, particularly excitation characteristics and iron loss characteristics. In particular, in recent years, from the viewpoint of energy saving, there has been an increasing demand for low iron loss materials with low energy loss for iron cores. In addition, it has been clarified that the noise generated by a transformer or the like becomes smaller as the magnetic flux density of the iron core material increases. Recently, iron core materials having a low iron loss and a high magnetic flux density are eagerly desired. ing.

  In addition to metallurgical methods such as increasing the magnetic flux density and refining secondary recrystallized grains as a method of reducing iron loss, there is a method of subdividing magnetic domains by irradiating laser light or plasma flame as a physical method. Proposed. In this method of irradiating a laser beam or a plasma flame, the magnetic domain fragmentation is caused by thermal strain introduced by the irradiation of the laser beam or the plasma flame. Since the introduced thermal strain disappears (recovers) by annealing at high temperature, this magnetic domain refinement technology can be used for a steel core transformer that does not require strain relief annealing, but requires strain relief annealing. It cannot be used for wound iron core transformers. For these reasons, it has been desired to develop a heat-resistant magnetic domain fragmentation technique that can withstand strain relief annealing.

  As a method for producing a grain-oriented electrical steel sheet that can withstand strain relief annealing and can be used for both a cored iron transformer and a wound iron core transformer, Patent Document 1, for example, uses a tooth-type roll on the surface of the electrical steel sheet. Patent Document 2 discloses a method of forming grooves, and Patent Document 2 discloses a method of forming linear grooves by etching on the surface of the final cold-rolled plate. Methods for forming rows or linear grooves have been proposed. In each of the methods described in Patent Document 1, Patent Document 2, and Patent Document 3, a point-sequence or linear groove is formed, and magnetic domain subdivision is performed using the demagnetizing field effect of the groove shape. Therefore, the domain refinement effect remains even after the strain relief annealing.

  However, in the method of forming a groove using the tooth roll disclosed in Patent Document 1, it is impossible to stably process a desired groove shape over a long period of time due to wear of the processing tool. Since the service life is relatively short, the replacement frequency of the processing tool increases, resulting in loss of processing tool recombination time and an increase in recombination cost, leaving problems from the viewpoint of productivity. In addition, in the method of forming a groove using etching or laser disclosed in Patent Document 2 and Patent Document 3, since the apparatus for forming the groove is very complicated and expensive, There was a problem that it was soaring and economically disadvantageous.

  For such a problem, for example, Patent Document 4 discloses a direction in which granular materials such as metal grains and synthetic resin grains are projected onto the surface of a finish-annealed grain-oriented electrical steel sheet to give a point-like strain linearly. A method for reducing the iron loss of a magnetic steel sheet has been proposed. As a method for projecting a granular material, Patent Document 4 exemplifies a projection in which the granular material is combined with a gas, for example, air, and a projection in which a liquid is combined with water, for example, and a steel shot is illustrated as the granular material. According to the method described in Patent Document 4, the amount of strain introduced and the groove shape can be easily changed according to the application by adjusting the material, particle size, and projection speed of the granular material to be projected. There is an advantage that a grain-oriented electrical steel sheet can be made according to the situation. For example, in the case of an iron core, the energy applied to the projection granule is reduced, only strain is introduced without forming a large recess (groove), and the deterioration of the magnetic flux density is reduced. Reduction can be achieved. Further, in the case of a wound iron core, it is possible to obtain an effect of reducing iron loss that can withstand the stress relief annealing by increasing the energy imparted to the projection granule and forming a recess (groove).

In the method described in Patent Document 4, the equipment for projecting the granular material may be, for example, shot blasting, which is inexpensive equipment compared to the laser method or the etching method, the equipment cost is low, and the granular material to be used is also circulated. In addition, even if the shape or the like changes greatly, classification is performed, whereby deteriorated granular materials can be removed, and stable strain introduction processing is possible.
Further, in Patent Document 4, as an apparatus for realizing the iron loss reduction method of the above-described grain-oriented electrical steel sheet, a plurality of slits 2 are provided apart from the surface of the grain-oriented electrical steel sheet 1 as shown in FIG. A rotatable drum 3 and an iron loss reducing device for projecting the granular material 4 by providing the granular material projection device 6 at both ends of the drum 3 are described.

  Further, Patent Document 5 discloses that a grain or a high-pressure water such as metal grains, synthetic resin, or the like is projected or jetted onto the surface of a grain-oriented electrical steel sheet that has been finish-annealed or treated with an insulating film after finish annealing, and perpendicular to the rolling direction. Direction of heat treatment at a temperature of 750 ° C or higher after forming a recess with a spacing of 2 to 20mm in the rolling direction within a range of 45 ° to 45 °, a width of 30 to 100 µm, and a depth of the base iron portion of 5 µm to 30 µm. A method for manufacturing an electrical steel sheet has been proposed. According to the technique described in Patent Document 5, there is an optimum size for the shape of the recess (linear groove) introduced into the steel sheet surface in order to effectively obtain the iron loss reduction effect due to magnetic domain subdivision. Yes.

In addition, in Non-Patent Document 1, when a linear groove is introduced by performing an etching process, the relationship between the groove shape and the magnetic domain refinement effect is investigated, and the groove shape in which the magnetic domain refinement effect is most effectively obtained is Depth: about 20 μm, groove width: about 200 μm, groove pitch: 3 mm.
JP-A-61-117218 Japanese Patent Publication No. 3-69968 JP 61-75506 JP JP 58-16027 A JP 63-166932 A Junji Sato et al .: Kawasaki Steel Technical Report, vol.29 (1997), No.3, p.153-158

  From the description of Patent Document 5 and Non-Patent Document 1, it is important to stably form the strain introducing portion and the linear groove in a size within an appropriate range in order to exert more magnetic domain subdivision effects. I understand. However, when using the iron loss reducing apparatus shown in FIG. 3 described in Patent Document 4 and applying a linear strain or a linear groove to the surface of the grain-oriented electrical steel sheet, There is a variation in the dimensional shape of the linear groove, and it is impossible to stably provide fine linear strain introduction portions and linear grooves of the desired dimensional shape with high accuracy, and it is impossible to stably secure excellent magnetic properties. was there.

  In the iron loss reducing apparatus described in Patent Document 4, the drum 3 having a plurality of slits 2 provided at a position away from the directional electromagnetic steel sheet 1 by a certain distance is used as the conveying speed of the directional electromagnetic steel sheet 1. While rotating the drum 3 synchronously, the granular material 4 projected from the granular material projection device 6 causes the point distortion corresponding to the slit 2 provided in the drum 3 to be linear, or the linear distortion to the directional electrical steel sheet. It is intended to be applied to the surface of 1. According to this apparatus, although it is possible in principle to give the steel sheet surface the distortion introduction part and the linear groove according to the slit width and slit pitch processed in the drum 3, for example, the conveyance speed of the steel sheet and Even if a slight deviation occurs in the rotational speed of the drum, the pitch of the strain introducing portion and the linear groove varies with respect to the steel sheet conveyance direction, which may cause variations in magnetic characteristics. In an actual production line where steel plates are transported at high speed, plate vibration and acceleration / deceleration always occur, so it is difficult to completely synchronize the steel plate transport speed and drum rotation speed when the steel plate and drum are at a certain distance. As a result, variations in magnetic characteristics occur.

  Moreover, when the solid granule is projected by using the apparatus of Patent Document 4 to give a linear groove, the shape of the applied strain introducing part or the linear groove is the depth of the slit part, that is, Influenced by drum thickness. For example, when the drum is thicker than the particle size of the projected granular material, the projected granular material has a high probability of colliding with the side wall in the slit when passing through the slit. The kinetic energy of the body is attenuated, and a strain-introducing portion or a linear groove having a desired dimensional shape cannot be applied to the steel plate surface.

  Therefore, in order to provide a fine strain introduction part and a linear groove using the apparatus of Patent Document 4, it is necessary to use a fine granular material to be projected and to use a thin drum. However, if the drum is thin, the rigidity is insufficient and the drum itself is more likely to be deformed and vibrated by centrifugal force.Therefore, the dimensional accuracy of strain-introducing parts and linear grooves applied to the steel sheet surface is reduced. As a result, variations in magnetic characteristics occur.

  The present invention advantageously solves such problems of the prior art, and provides a low iron loss directional electrical steel sheet suitable for a laminated iron core transformer or a wound iron core transformer that can withstand strain relief annealing. It aims at proposing the manufacturing method of a grain-oriented electrical steel sheet and the iron loss reduction apparatus of a grain-oriented electrical steel sheet which can be manufactured few.

  In order to achieve the above-mentioned problems, the present inventors diligently studied a method for imparting a fine linear strain introducing portion or a linear groove to a grain-oriented electrical steel sheet with high dimensional accuracy. As a result, in order to provide minute linear grooves with high dimensional accuracy, it has been conceived that a grain-oriented electrical steel sheet is wound around a thin drum having a plurality of slits and having a structure that can be driven and rotated freely. Thereby, even if slight fluctuations occur in the conveying speed of the steel sheet, the conveying speed of the steel sheet and the rotational speed of the drum can be completely synchronized, and variations in the dimensional shape of the linear grooves can be prevented. Further, as a result of further study, the present inventors have found that the reduction in rigidity of the thin drum can be solved by providing a planetary roll inside the drum and supporting the drum from the inside.

The present invention has been completed based on the above findings and further studies. That is, the gist of the present invention is as follows.
(1) In the manufacturing method of grain-oriented electrical steel sheet, the cold-rolled sheet that is continuously conveyed after the cold-rolling step to obtain a cold-rolled sheet with the final thickness is supported by a planetary roll from the inside and freely rotatable. A plurality of axially extending drums are wound around a circumferential surface disposed on a thin cylindrical drum having slits, and solid particles are projected from the inside of the drum to the surface of the cold-rolled plate through the slits. And the manufacturing method of the low iron loss directionality electrical steel sheet characterized by performing the distortion | strain introduction part or linear groove | channel provision process which provides a linear distortion | strain introduction part or a linear groove | channel on the said cold-rolled sheet surface.
(2) A thin cylindrical drum having a plurality of axially extending slits on a circumferential surface, which is capable of being wound around a directional electromagnetic steel sheet to be transported, which is a projection material, and which is rotatably disposed. A planetary roll that supports the drum from the inside, and a solid particle projection device that projects solid particles from the inside of the drum to the projection target through the slit, and has a linear shape on the surface of the grain-oriented electrical steel sheet. An iron loss reducing device for grain-oriented electrical steel sheet, characterized by providing a strain introducing portion or a linear groove.

  According to the present invention, the iron loss value of the grain-oriented electrical steel sheet can be stably reduced, and the variation in magnetic properties can be reduced, thereby producing a remarkable industrial effect. Further, the iron loss reducing device for grain-oriented electrical steel sheet of the present invention is a practically simple apparatus, and according to the present invention, it is possible to reduce the equipment cost and the operating cost in the production of low iron loss grain-oriented electrical steel sheet. There is also an effect that there is.

First, the iron loss reducing apparatus for grain-oriented electrical steel sheet according to the present invention will be described.
The iron loss reducing device for grain-oriented electrical steel sheet according to the present invention includes a drum 3, a planetary roll 5, and a solid particle projection device 6. An example of the iron loss reduction apparatus for grain-oriented electrical steel sheets according to the present invention is schematically shown in FIG.
The drum 3 has a thin cylindrical shape and has a plurality of through-thick slits 2 extending in the axial direction on the circumferential surface. The drum 3 is non-driven, and can be wound around the directional electromagnetic steel sheet 1 that is continuously conveyed, and is rotatably arranged. By adopting such a structure, the drum 3 can be freely rotated integrally with the directional electromagnetic steel sheet 1 by friction with the surface of the wound directional electromagnetic steel sheet 1. For this reason, even when fluctuations occur in the steel plate conveyance speed, the drum rotation speed and the steel plate conveyance speed are always the same, and the drum rotation speed and the steel plate conveyance speed are controlled by a control device for synchronization. I don't need it.

  Here, the “thin wall” cylindrical shape means a case where the thickness t is 10 mm or less, the ratio of the drum outer diameter D to the thickness t, and t / D is 0.02 or less. In the present invention, the drum 3 needs to be a large diameter drum that does not cause plastic deformation when the directional electromagnetic steel sheet is wound around the drum in order to prevent deterioration of the magnetic properties of the directional electromagnetic steel sheet. It is preferable that the outer diameter D is 500 mm or more. By using such a thin cylindrical drum as the drum in which the slit is provided, it is possible to efficiently form a linear strain introducing portion or a linear groove without attenuating the kinetic energy of the projected solid particles.

  The drum 3 has a plurality of thick through slits 2 extending in the axial direction on the circumferential surface. The width and pitch of the slits 2 provided on the circumferential surface of the drum 3 are appropriately determined according to the linear strain introduction portion and the dimensional shape (width and pitch) of the linear grooves applied to the grain-oriented electrical steel sheet 1. However, in order to effectively increase the iron loss reduction effect, it is preferable to set the slit width to 100 to 500 μm and the slit pitch to 2 to 10 mm. Note that the length of the slit is preferably substantially equal to the steel plate width.

In the present invention, the drum 3 is rotatably supported by the plurality of planetary rolls 5 from the inside. The planetary roll 5 is also not driven. Thereby, sufficient rigidity can be secured even with a thin cylindrical drum, and a fine linear strain introduction portion or linear groove corresponding to the dimension of the slit can be provided with high accuracy.
Further, it is preferable that the planetary rolls 5 are evenly disposed along the inner circumferential surface of the drum so as to support the drum 3 evenly from the inner side. In the present invention, the arranged planetary rolls 5 may be any number as long as the number of the planetary rolls 5 can support the inner peripheral surface evenly according to the diameter of the drum and can secure a space in which solid particles can be projected from the inside. Not.

  In the present invention, a plurality of solid particle projection devices 6 are disposed in the space between the planetary rolls 5 inside the drum 3. The solid particle projection device 6 projects the solid particles 4 on the surface of the grain-oriented electrical steel sheet 1 through the slits 2 provided in the drum 3. The solid particle projection device 6 is preferably provided at a position where the solid particles can be projected onto the surface of the grain-oriented electrical steel sheet 1 in the space between the planetary roll 5 and the planetary roll 5. In addition, although the projection direction of a solid particle is not specifically limited, It is preferable to project from the downward direction of a slit. This eliminates the problem that the projected solid particles fall by their own weight, accumulate in the slit, and block the slit. The solid particle projection device 6 is preferably a pneumatic shot blasting device or the like, but is not limited thereto. Moreover, in the solid particle projector 6, it is preferable that the projection energy such as the projection speed of the solid particles can be made variable according to the application.

Further, the solid particles projected by the iron loss reducing apparatus of the present invention are not particularly limited and may be appropriately selected depending on the application, and examples thereof include steel shots and alumina particles.
A solid particle supply device 8 is connected to the solid particle projection device 6 outside the drum 3, for example, at an axial end of the drum 3, and supplies the solid particles 4 to the solid particle projection device 6. Further, the dust collector 7 is preferably connected to the drum 3, whereby the projected solid particles 4 are sucked and the solid particles 4 do not accumulate at the lower part of the drum 3. The dust collector 7 is preferably connected to a classifier (not shown). As a result, the sucked solid particles are classified, and the worn and crushed particles and foreign matters are removed, and only those having a certain particle diameter can be circulated and used. A groove can be stably and accurately provided.

Needless to say, the iron loss reducing apparatus of the present invention is provided with ancillary equipment for operation such as attaching and detaching electromagnetic steel sheets.
Next, a method for producing a grain-oriented electrical steel sheet having fine iron loss characteristics introduced with a fine linear strain introduction portion or linear groove will be described.
In a normal method of manufacturing a grain-oriented electrical steel sheet, a hot rolling process in which hot rolling is performed on a slab for grain-oriented electrical steel sheet containing Si: 4 mass% or less, and the hot-rolled sheet is necessary. A cold rolling step of subjecting the hot-rolled sheet to cold-rolled sheet having a final sheet thickness by subjecting the hot-rolled sheet to two cold rollings including intermediate annealing or one cold rolling. The steel sheet is subjected to a decarburization annealing, an annealing separator and a secondary recrystallization annealing, followed by a flattening annealing and an insulating coating application / baking process in order to obtain a grain-oriented electrical steel sheet.

  In the present invention, after the cold rolling step of making the cold-rolled sheet having the final thickness described above, the cold-rolled sheet that is continuously conveyed is supported from the inside by a planetary roll and is arranged rotatably. It is wound around a thin cylindrical drum having a plurality of axially extending slits on the peripheral surface, and solid particles are projected from the inside of the drum through the slit onto the surface of the cold rolled plate, and linear on the surface of the cold rolled plate The strain introducing portion or the linear groove applying step for applying the strain introducing portion or the linear groove is applied.

The strain introduction part or the linear groove applying step described above may be any time as long as it is a step after the cold rolling step to obtain a cold-rolled sheet having a final thickness, for example, secondary recrystallization annealing even before decarburization annealing. The order of performing the steps is not particularly limited.
In the case of a wound iron core, it is necessary to form a linear groove, but if left as it is, a large strain remains in the vicinity of the formed linear groove, which adversely affects the magnetic properties. For this reason, since it is necessary to recover the strain by heat treatment or the like, it is preferable to form linear grooves before high-temperature annealing at 700 ° C. or higher, such as secondary recrystallization annealing or planarization annealing. On the other hand, in the case of a product core, a linear groove may be formed, but the magnetic flux density is slightly reduced by forming the linear groove, so that a directional electrical steel sheet having a high magnetic flux density and a low iron loss is obtained. It is more preferable to introduce only strain. In this case, the strain introduction is preferably performed after the planarization annealing.

The strain introducing portion or the linear groove applying step is preferably performed using the iron loss reducing apparatus of the present invention described above.
In the present invention, a directional electromagnetic steel sheet (cold rolled sheet) continuously conveyed is supported from the inside by a planetary roll, has sufficient rigidity and is rotatable, and has a thin cylindrical shape having a plurality of thick through slits. Wrap around the drum. Thereby, the conveyance speed of a cold-rolled board and the rotational speed of a drum synchronize completely, and the fine distortion introduction part or linear groove | channel according to the dimension of a slit can be provided accurately.

Next, solid particles are projected from the inside of the drum onto the surface of the cold-rolled plate wound around the thin cylindrical drum through a slit provided in the drum by a solid particle projection device. Thereby, the fine strain introduction part or linear groove | channel according to the dimension of a slit is provided on the cold rolled sheet surface.
The preferable shape of the strain introducing portion or the linear groove to be applied is preferably a width: 100 to 500 μm and a pitch: 2 to 10 mm in the strain introducing portion, and a depth: 5 to 100 μm and a width in the linear groove. Preferably, the thickness is 100 to 500 μm and the pitch is 2 to 10 mm. In addition, what is necessary is just to select suitably the kind of solid particle, particle size, etc. which are projected according to the objective, and it is preferable that the particle size (size) shall be 50-300 micrometers.

  Hereinafter, the present invention will be further described based on examples.

Example 1
Planar annealed Si: 4 mass% grain-oriented electrical steel sheet (thickness: 0.23 mm, width: 300 mm)
1 is used to wind a directional electrical steel sheet continuously conveyed on the drum 3 of the iron loss reduction apparatus using the iron loss reduction apparatus of the present invention shown in FIG. A linear strain-introducing portion was imparted to the surface to make an example of the present invention. In the iron loss reduction apparatus used, the drum 3 is a thin cylinder with an outer diameter of 1000 mmφ and a wall thickness of 3 mm, and 16 planetary rolls (outer diameter: 100 mmφ) 5 are arranged inside the drum. The structure is supported from the inside. The drum 3 is provided with a plurality of thick through slits 2 extending in the axial direction and having a width of 350 μm in the circumferential direction on the circumferential surface with a pitch of 7.5 mm. Further, six pneumatic shot blasting apparatuses are disposed as solid particle ejecting apparatuses 6 between the planetary rolls at the upper part of the drum 3 and between the planetary rolls inside the drum 3. Using this pneumatic shot blasting device, solid particles to be projected onto high-pressure air compressed by a compressor were mixed and projected onto the steel plate surface at high speed to give a linear strain introduction part. As solid particles, alumina particles having an average particle diameter of 55 μm were used, and the injection pressure was 0.1 MPa.

In addition, the conveyance speed of the grain-oriented electrical steel sheet was changed as shown in FIG. At this time, the projection amount of the solid particles was changed in proportion to the conveyance speed so that the projection amount of the solid particles per unit time was constant at 5 kg / min · m ² .
In addition, as a conventional example, using the same type of apparatus as shown in FIG. 3, wire is applied to a grain-oriented electrical steel sheet (sheet thickness: 0.23 mm, sheet width: 300 mm) containing Si: 4 mass% after flattening annealing. A strain-introducing portion was added. In the same type of apparatus as shown in FIG. 3, with the directional electromagnetic steel sheet being separated by a certain distance (100 mm), the drum rotation speed and the steel sheet conveyance speed are synchronized with each other through a slit from the inside of the drum. , Solid particles were projected. The dimensions of the drum, the size of the slit provided in the drum, the pitch, the projected solid particles, the projection pressure, and the projection amount were the same as those of the example of the present invention using the apparatus of FIG.

The grain-oriented electrical steel sheet provided with the linear strain-introducing portion by the above-described method is further coated with an insulating coating, and then a test piece is taken from each position corresponding to each region shown in FIG. 2 of the grain-oriented electrical steel sheet. Five pieces of each were collected and measured for iron loss W17 / 50 and magnetic flux density B8. From the obtained iron loss value and magnetic flux density value, the variation of the measured value in each region where the conveyance speed was changed was calculated.
The obtained measurement results are shown in Table 1. W17 / 50 represents iron loss W / kg at a magnetic flux density of 1.7 T and a frequency of 50 Hz.

本発明例、従来例ともに、歪付与前に比べて、鉄損が0.09Ｗ／kg程度低減しており、歪導入により大きな鉄損低減効果が得られている。本発明例では、歪導入後の鉄損値のばらつきが少なくなっているのに対し、従来例では、歪導入により鉄損値のばらつきが大きくなっている。なお、磁束密度B8は、歪導入により若干低下しているが、実用上は問題ない程度である。
（実施例２）
平坦化焼鈍済みのSi：4mass％を含有する方向性電磁鋼板（板厚：0.23mm、板幅：500mm）
を用い、実施例１と同様に、図１に示した本発明の鉄損低減装置を利用して、該鉄損低減装置のドラム３に連続して搬送される方向性電磁鋼板を巻き掛けし、該方向性電磁鋼板表面に固体粒子噴射装置６から固体粒子を高速で投射し、線状溝を付与し、本発明例とした。なお、使用した鉄損低減装置のドラム３には、幅：400μｍの肉厚貫通スリット２を、ピッチ：7.5mmで円周面上に複数個設けた。また、投射する固体粒子は、平均粒径：200μｍのＳＵＳ３０４粒子を用い、噴射圧力を1.0MPaとした。

In both the example of the present invention and the conventional example, the iron loss is reduced by about 0.09 W / kg as compared with that before the application of strain, and a large iron loss reduction effect is obtained by introducing the strain. In the example of the present invention, the variation of the iron loss value after the introduction of strain is reduced, whereas in the conventional example, the variation of the iron loss value is increased by introducing the strain. The magnetic flux density B8 is slightly reduced due to the introduction of strain, but is practically satisfactory.
(Example 2)
Planar annealed Si: 4 mass% grain-oriented electrical steel sheet (thickness: 0.23 mm, width: 500 mm)
In the same manner as in Example 1, using the iron loss reducing device of the present invention shown in FIG. 1, a directional electrical steel sheet continuously wound around the drum 3 of the iron loss reducing device is wound. The solid particle was projected at high speed from the solid particle injection device 6 on the surface of the grain-oriented electrical steel sheet to give a linear groove, thereby obtaining an example of the present invention. The drum 3 of the iron loss reducing apparatus used was provided with a plurality of thick through slits 2 having a width of 400 μm on the circumferential surface with a pitch of 7.5 mm. The solid particles to be projected were SUS304 particles having an average particle size of 200 μm and the injection pressure was 1.0 MPa.

In addition, the conveyance speed of the grain-oriented electrical steel sheet was changed as shown in FIG. At this time, the projection amount of the solid particles was changed in proportion to the conveyance speed so that the projection amount of the solid particles per unit time was constant at 10 kg / min · m ² .
Further, as a conventional example, similar to Example 1, an apparatus of the same type as the apparatus shown in FIG. In the same type of apparatus as shown in FIG. 3, the rotating speed of the drum and the conveying speed of the steel sheet were synchronized while the directional electromagnetic steel sheets were separated by a certain distance (100 mm). The dimensions of the drum, the size and pitch of the slits provided in the drum, the projection solid particles, the projection pressure, and the projection amount were the same as in the case of the present invention example using the apparatus of FIG.

  The grain-oriented electrical steel sheet provided with linear linear grooves by the above-described method is further coated with an insulating coating, and then a test piece is taken from each position corresponding to each region shown in FIG. After collecting 5 pieces each and annealing at 750 ° C., the iron loss W17 / 50 and the magnetic flux density B8 were measured. From the obtained iron loss value and magnetic flux density value, the variation of the measured value in each region where the conveyance speed was changed was calculated.

  The obtained measurement results are shown in Table 2. W17 / 50 represents iron loss W / kg at a magnetic flux density of 1.7 T and a frequency of 50 Hz.

本発明例、従来例ともに、線状溝付与前に比べて、鉄損が0.1Ｗ／kg程度低減しており、溝付与により大きな鉄損低減効果が得られている。本発明例では、溝付与後の鉄損値のばらつきが、少なくなっているのに対し、従来例では、溝付与後に鉄損値のばらつきが大きくなっている。なお、磁束密度B8は、歪導入により若干低下しているが、実用上は問題ない程度である。

In both the example of the present invention and the conventional example, the iron loss is reduced by about 0.1 W / kg as compared with that before the linear groove is provided, and a large effect of reducing the iron loss is obtained by providing the groove. In the example of the present invention, the variation in the iron loss value after providing the groove is reduced, whereas in the conventional example, the variation in the iron loss value after applying the groove is large. The magnetic flux density B8 is slightly reduced due to the introduction of strain, but is practically satisfactory.

It is the schematic which shows typically an example of the iron loss reduction apparatus of this invention. In addition, (a) is a side view and (b) is a plan view. It is a graph which shows the change condition of the conveyance speed used for the Example. It is the schematic which shows an example of the conventional iron loss reducing apparatus typically. In addition, (a) is a side view and (b) is a plan view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Directional electrical steel sheet 2 Slit 3 Drum 4 Solid particle 5 Planetary roll 6 Solid particle projection apparatus 7 Dust collector 8 Solid particle supply apparatus

Claims (2)

  In the method for producing grain-oriented electrical steel sheets, the cold-rolled sheet that is continuously conveyed after the cold-rolling step to obtain a cold-rolled sheet with the final thickness is supported from the inside by a planetary roll and rotatably disposed. Wrapped around a thin cylindrical drum having a plurality of axially extending slits on the circumferential surface, and solid particles are projected from the inside of the drum through the slit onto the surface of the cold-rolled plate. A method for producing a low iron loss grain-oriented electrical steel sheet, comprising performing a strain introducing portion or a linear groove applying step for providing a linear strain introducing portion or a linear groove on a surface of a drawn plate. A thin cylindrical drum having a plurality of axially extending slits on a circumferential surface, on which a directional electromagnetic steel sheet to be transported as a projection material can be wound and rotatably disposed, and the drum An iron loss reducing device for grain-oriented electrical steel sheets, comprising: a planetary roll that supports the inner surface of the drum; and a solid particle projection device that projects solid particles from the inside of the drum onto the projection material through the slit.

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