KR930009974B1 - Method for producing low iron loss grain oriented silicon steel sheets - Google Patents

Abstract

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Description

Manufacturing method of low iron loss grain oriented silicon steel sheet

1a and 1b are diagrams showing locally removed tracks of an oxide layer, respectively, measured with a three-dimensional roughness meter.

2A and 2B are graphs showing the effect of increasing magnetic properties, respectively.

3 is a graph showing the wear loss of the work team due to the local removal of the oxide layer.

4 is a graph showing the effect of increasing magnetic properties through electrolytic etching.

5 is a graph showing the effect of the filling of foreign substances.

6A and 6B are plan and side views, respectively, of a first embodiment implementing the method of the present invention.

7A and 7B are plan and side views, respectively, of a second embodiment implementing the method of the present invention.

8 is a partially enlarged cross-sectional view of the ultrasonic vibration member used in the present invention.

9 and 10 are schematic diagrams showing removal states of an oxide layer on the surface of a steel sheet, respectively.

* Explanation of symbols for main parts of the drawings

1: grain oriented silicon steel sheet 2: roller

4 head 5 ultrasonic vibration member

6: screw right shaft 8, 13: drive motor

14: work team 15: air cylinder

The present invention provides a method for producing a low iron loss grain-oriented silicon steel sheet that does not cause deterioration due to deformation correction annealing, in particular, an area having different tension or magnetic properties on the surface by imparting nonuniformity to an oxide layer formed on the surface of the steel sheet. The present invention relates to a method for improving iron loss in grain-oriented silicon steel sheet after secondary recrystallization annealing without deterioration due to stranin relief annealing that may occur.

Grain-oriented silicon steel is used as the core of transformers and other electrical machinery and devices and is required where good magnetic properties, especially low iron losses (called the W _17/50 value), are required.

For this purpose, the <1> direction of the secondary recrystallized grains in the silicon steel sheet should be aligned with the rolling direction precisely and the impurities and precipitates present in the steel of the final product should be reduced as much as possible.

Under the above circumstances, many studies have been conducted to increase the characteristics of grain-oriented silicon steel sheet. As a result, iron loss values have improved over the years. Recently 1.05W / kg in W _17/50 value was obtained at a thickness of 0.30mm products.

However, as the energy crisis is recognized many years ago, the development of electrical machinery and devices with low output loss is highly demanded. In this connection, a low iron loss grain-oriented silicon steel sheet is required as the core material.

Conventional means for reducing the iron loss of grain-oriented silicon steel sheet include increased Si content, reduced product thickness, refined secondary recrystallized particles, reduced impurity content, and precisely recrystallized secondary recrystallized particles in the {110} <1> direction. There are mainly metallurgical means, such as straightening. These metallurgical means have already reached their limits in terms of existing manufacturing methods and it is very difficult to improve the quality of existing ones. Whatever the improvement, the actual effect of the iron loss improvement is small.

Unlike the conventional means, Japanese Patent Application Laid-Open No. 54-23647 describes a method for producing fine secondary recrystallized particles by forming secondary recrystallization inhibiting regions on the steel sheet surface. However, it is unstable to control the secondary recrystallized particle size in this method, so this method is not practical.

In addition, Japanese Patent Application Publication No. 58-5968 discloses an iron loss reduction technique, in which a small ball of a ballpoint pen is pushed on the surface of the steel sheet to refine the magnetic domain to refine the magnetic domain to the surface portion of the steel sheet after secondary recrystallization. Micro deformations are formed. Japanese Patent Application Publication No. 57-2252 also describes an iron loss reduction technique, in which a laser beam is irradiated to the surface of the final product at intervals of several millimeters perpendicular to the rolling direction so that a high dislocation density region is applied to the surface portion of the steel sheet. It is formed and the identity of the domain is made. In addition, Japanese Patent Application Laid-Open No. 57-188810 describes an iron loss reduction technique in which micro deformation is formed in the surface portion of a steel sheet by electric discharge machining for refining magnetic domains.

All the above methods reduce iron loss by forming a micro strain in the surface portion of the base metal of the steel sheet after secondary recrystallization to carry out the refining of the magnetic domain, and has a practical and excellent iron loss reduction effect. However, in the above methods, the effect of the formation of plastic deformation is due to the heat treatment such as firing of the coating layer or by deformation correction annealing after work such as punching, shearing work, coiling, etc. By undesirable reduction.

Japanese Patent Application Laid-Open No. 61-73886 discloses the reduction of iron loss in which non-uniform elastic deformation is formed on the surface of a steel sheet by locally removing the surface coating through a vibrating body forcibly reciprocating at a movement amount of 5 x 10 ^-6 kgm / s or more. The technique is described. However, also in this technique, the above-mentioned effect is greatly reduced by annealing of 600 degreeC or more.

In addition, when the formation of the micro plastic deformation is carried out after the coating treatment, by performing the insulating coating again to maintain the insulating properties, the number of process steps is greatly increased and the cost is increased.

In order to overcome the above drawbacks of the prior art, it is proposed in Japanese Patent Laid-Open No. 60-92481 to impart a non-forming portion of a forsterite film.

The publication describes two methods of imparting non-forming parts, one of which prevents forsterite protion from being locally formed and the other of locally forming non-forming parts after forming forsterite. How to grant. Local removal of double forsterite is practically useful in industry, because process control is difficult due to the use of chemical or means that impede the reaction in the method of preventing the formation of the forsterite part locally. .

On the other hand, as a means of locally removing forsteride after secondary recrystallization or forsterite formation, a mechanical method and output control using a rotating disk-type abrasive stone or iron needle under low pressure and chemical polishing, electropolishing, Optical methods using laser beams and the like have been described. Each of these methods has some effect. However, chemical polishing and electropolishing are expensive, and the rotating disk type abrasive stone is not suitable for industrial production because it is difficult to remove the position of the disk height according to the surface characteristics. In addition, an optical method using a laser beam or the like is expensive.

On the other hand, the use of iron needles under light pressure is inexpensive, but it is difficult to remove only forsterite, resulting in the removal of part of the surface portion of the base metal together with forsterite. Therefore, the base metal is raised on both sides of the removal or non-forming part, and the lamination factor is significantly reduced. In other words, the use of iron needles is not practical in industry.

The formation of grooves on the surface of the silicon steel sheet as a technique of self-refining tablets is described in Japanese Patent Publication Nos. 50-35679, 59-28525, 59-197520, 61-117218 and 61-117284 as known techniques. It is. However, the technique because by the phenomenon of magnetic domain refining with half the magnetic field (diamagnetic field) in the groove space (referred to as B ₁₀ value), the magnetic flux density is greatly reduced, and reduction in mechanical properties, the above-described deformation correction Although not sensitive to annealing, there is a drawback that the lamination rate is greatly reduced along the grooves.

Accordingly, one object of the present invention is to provide a plate having good surface properties in lamination without significantly reducing the B ₁₀ value and lamination rate, and to improve the efficiency without causing any deterioration of the magnetic properties, in particular iron loss characteristics such as bottle-type straightening annealing. It is to provide a method for producing a low iron loss grain oriented silicon steel sheet to easily perform the actual operation without reduction.

According to the present invention, a method for producing a low iron loss particle oriented silicon steel sheet which does not cause deterioration of properties due to strain correction annealing, wherein ultrasonic vibration is performed after secondary recrystallization in order to locally remove an oxide layer from the surface of the steel sheet. A method is provided which is applied to a surface. Therefore, the effect of the self-cleaning tablet is stable and can be obtained at low cost without significantly reducing the B ₁₀ value and the lamination rate, and without extinguishing the iron loss reduction effect due to the deformation correction annealing.

The working team of the ultrasonic vibration member in the method of the present invention is pushed to the surface of the steel sheet under a certain pressure. According to a preferred embodiment of the present invention, the ultrasonic vibration generating device and the head portion are disposed facing the surface of the steel sheet moving around the roller and move in the width direction of the steel sheet, and a plurality of ultrasonic vibration members are disposed in the head portion in a staggered form. Move towards and away from the surface of the steel sheet.

When the ultrasonic vibrating member moves to a strong surface, the work team of the member is pushed to the steel plate surface under controlled pressure. In this state, the head portion reciprocates in the width direction of the moving steel sheet so that ultrasonic vibration is applied to the grain-oriented silicon steel sheet to locally remove the oxide layer of forsterite formed by the secondary recrystallization from the steel sheet surface.

The shape of the work team applying ultrasonic vibration to the grain-oriented silicon steel surface after the second recrystallization annealing may be either plate-like or needle-like as long as the oxide layer can be removed locally. Can be. In addition, the material of the work tip is a rigid crystal of diamond, ruby, etc .; ceramic; Metals such as brass and copper; Abrasive stone, wood chips, etc.

The frequency of the ultrasonic vibrations needs to be 10 kHz or more.

According to the present invention, Japanese Patent Laid-Open No. 61-117218 relates to a technique for locally forming a groove as a conventional furniture tablet by effectively and locally removing an oxide layer from the surface of a grain-oriented silicon steel sheet by ultrasonic vibration impact. It is not required to apply a large load as described in. That is, when ultrasonic vibration is applied to the grain-oriented silicon steel sheet, the work tip of the ultrasonic vibration member is pushed to the steel sheet surface at a pressure of 40 kg / mm ² or less. When the pressure is 40 kg / mm ² or more, plastic deformation is imparted to the base metal surface portion, the lamination rate is reduced, and the work tip is greatly worn due to the elevation of the base metal around the removal portion of the oxide layer.

Further, according to the present invention, the large plastic deformation as described in the prior art of forming grooves using iron needles is not formed on the base metal surface, and it is not necessary to form deep grooves in the base metal, and thus a large B ₁₀ value. The problem of reduction and deterioration of mechanical properties is never caused.

The shape of the work track after applying the ultrasonic vibration according to the present invention, in which the work tip of the ultrasonic vibration member is ruby, to remove the oxide layer, and after removing the oxide layer using an iron needle under micro-pressure as in the comparative example. Explain.

1 shows a plot of the locally removed portion of the oxide layer measured with a three-dimensional roughness meter.

FIG. 1a illustrates a case where ultrasonic vibration is applied and FIG. 1b illustrates the use of the iron needle at low pressure.

As can be seen in FIGS. 1a and 1b, in both cases the depth of removal is several μm for 10 minutes, where it is evident that no deep grooves are formed in the base metal. However, when the oxide layer is mechanically removed by the iron needle, the base metal is raised around the groove, as can be seen from the left edge of the groove in FIG. 1B, even if the removal portion or groove is not very deep. These base metal ridges reduce the lamination rate in the electromagnetic steel sheet stacking, and the insulation is impaired, thereby losing their usefulness as industrial products. On the contrary, according to the present invention, the elevation of the base metal is not caused as can be seen in FIG. It is clear that the application of ultrasonic vibration has the effect of reducing the pressing force at the work tip.

The increase in magnetic properties according to the present invention is represented by ○ in FIG. 2, ◇ denotes a case of removing the surface coating with iron needles, and ◆ denotes a case of forming a groove as in the comparative example.

According to the method of the present invention, by applying the ultrasonic vibration of 30kHz in the direction perpendicular to the rolling direction of the steel sheet by the working diamond tip, grooves having a width of 30 μm and a depth of 0.2 μm are parallel to each other and 5 mm apart. The oxide layer was locally removed from the grain-oriented silicon steel sheet surface after the secondary recrystallization annealing by forming.

On the other hand, when a steel scriber such as iron needle was used under light pressure, grooves having a depth of 0.2 μm were formed at parallel intervals of 5 mm, and when used under medium pressure, a depth of 2 μm (120 μm in width) was used. The grooves were formed equilibrium with each other and 5 mm apart. In the latter method, the formation of grooves with a depth of 2 μm imposes high pressure on the base metal. Therefore, in using the iron needle under heavy pressure, the iron loss is greatly reduced before the deformation correction annealing, on the contrary, the property decreases after the calibration annealing. Deformation is introduced by forcibly forming a groove having a depth of 2 μm to perform self-refining, and thus the iron loss is reduced, but the effect of such iron loss reduction is lost by subsequent strain correction annealing (800 ° C. × 3 hours). In this case, the decrease in the value of B ₁₀ is large, and therefore this iron loss value is poor compared with the iron loss value immediately after the second recrystallization annealing.

In addition, since the forsterite layer near the grooves is unevenly destroyed under heavy pressure, the effect of the self-cleaning agent by removing the oxide layer such as forsterite (and also expected by the method of the present invention) is substantially eliminated and thus the iron loss characteristics are It is greatly reduced.

In the case of removing the oxide layer to a depth of 0.2 μm by the method of the present invention, the increase in the iron loss ratio before and after removing the oxide layer is small compared with the case where the grooves are formed under medium pressure, but the iron loss characteristics after the strain correction annealing It does not degrade but rather improves. The reason for such improvement is not clear, but it is presumed that the unnecessary deformation introduced slightly by the application of ultrasonic deformation is extinguished or formed by the deformation correction annealing, and the oxide layer preferably works to increase the iron loss characteristics.

When the oxide layer is removed to a depth of 0.2 탆 by iron needle under light pressure, iron loss and a decrease in magnetic flux density are caused after strain correction annealing. This is presumably due to the fact that the base metal is raised in the processed portion, thereby increasing the leakage of magnetic flux.

In Japanese Patent Laid-Open No. 56-130454, ultrasonic waves are applied to a geared roller, in which a roll is contacted under pressure linearly to the surface of a grain-oriented silicon steel sheet after secondary recrystallization annealing to form a fine recrystallized grain group on the surface of the steel sheet. The technique is described. In this technique, complex deformation is given to the surface of the steel sheet in order to obtain fine recrystallized particles. Therefore, it is natural to impart sufficient strain to enable recrystallization, whereby a gear roller is used.

In contrast, the present invention is to locally remove the oxide layer, which is different from forming fine recrystallized particles as a whole. Needle or plate type work tips are used for this purpose. Thus, the recrystallized particle group is not newly formed in the method of the present invention.

In a preferred embodiment of the present invention, the steel sheet is subjected to an electrolytic etching treatment after removing the oxide layer. Therefore, the effect of the self-cleaning agent can be further increased by applying a semi-magnetic field in the groove formed after the oxide layer is locally removed. In another embodiment of the present invention, a predetermined foreign material is filled into the grooves after the electrolytic etching is performed to further increase the magnetic properties as indicated by 에서 in FIGS. 2A and 2B. Of course, the importance of the lamination rate is sufficiently maintained in this case.

In addition, the results of the iron loss and the B ₁₀ value in the present preferred embodiment are indicated by ● in FIGS. 2A and 2B. From this it is clear that the iron loss is further reduced and the B ₁₀ value is reduced to some extent. These measurement data were subjected to local removal of the oxide layer on the steel sheet, charged with colloidal silica, and electrolytic etching and strain correction annealing (100 ° C. ×) in NaCl solution (100 g / l ) at a current density of 20 A / dm ² for 5 seconds. 3 hours) in the case of carrying out the treatment.

According to the present invention, the starting material is required to be a grain-oriented steel sheet after secondary recrystallization annealing. That is, it is meaningless to apply the method of the present invention to the steel sheet before the secondary recrystallization annealing, but when the method of the present invention is applied to the steel sheet after the secondary recrystallization annealing, the history of the steel sheet such as the kind of inhibitor, the number of cold rolling, etc. Iii) regardless of the effect.

Secondary recrystallization annealing is usually carried out at a temperature of 800 ~ 1200 ℃ the oxide layer is present on the grain-oriented silicon steel sheet surface.

According to the present invention, the oxide layer is locally removed by ultrasonic vibration. In this case, the work tip of the ultrasonic vibration member is in contact with the steel plate surface when ultrasonic vibration is applied at a pressure of 40 kg / mm ² or less, and the work tip follows the steel plate surface. When the pressure exceeds 40 kg / mm ² , plastic deformation occurs at the surface portion of the steel sheet, which is undesirable. The effect of removing the oxide layer locally is usually unchanged before or after forming an insulating coating on the oxide layer. In this case, the insulating coating layer may be a tension coating.

Local removal of the oxide layer is required to be performed in the form of a dashed line or a continuous or discontinuous straight line across the rolling direction to repeatedly form removal portions parallel to each other on the surface of the steel sheet. The removal direction is preferably perpendicular to the rolling direction. It is preferable that the space | interval between parallel removal parts exists in the range of 1-30 mm. When the distance between the parallel removal portions is 1 mm or less, the surface characteristics are degraded by the grooves, and a sufficient increase in iron loss value cannot be obtained, and when it exceeds 30 mm, the effect of magnetic domain purification is lost.

This effect is also substantially unchanged even when local removal is applied to one or both surfaces of the steel sheet.

Local removal of the oxide layer in the present invention needs to be performed using a work tip of ultrasonic vibration. The shape of the work tip is preferably needle-shaped. The width of the removal may vary depending on the size or thickness of the work tip. The width of the removal portion is 10-1000 μm, preferably about 100 μm. When the width of the removal portion is 10 μm or less, the steel sheet is easily broken by the notch action, and when it exceeds 1000 μm, the surface properties are deteriorated and the iron loss value is not improved. Ultrasonic vibration is applied to the work tip when the oxides such as popoprite are removed locally, so the processing deformation is small, the members (work tips) can be made small, and the flat metal can be obtained without the base metal being raised. There is an advantage.

When the local removal of the oxide layer is mechanically performed using an iron needle without applying ultrasonic vibration, the plastic deformation portion becomes large, and thus lamination and B ₁₀ values are greatly reduced.

Vibrations having a frequency of 10 kHz or more, an amplitude of 50 μm or less and mainly including one component in the vertical direction on the surface of the steel sheet are preferable as application conditions of the ultrasonic vibration. If the frequency is 10 kHz or less, the impact density due to vibration is small and its effect is less. On the other hand, when the amplitude is 50 μm or more, the impact force increases and the deformation is large, thereby decreasing the value of B ₁₀ .

In this case, pulse or continuous mode is used as the generation mode of the ultrasonic vibration.

As a work tip for applying ultrasonic waves to the surface of the steel sheet, a material made of a material capable of locally removing an oxide layer may be used, but a columnar or semi-ball shape diamond having a diameter of 2 mm or less, Preference is given to using ceramics or cemented carbides. If the material is not rigid, it is busy to replace the oxide layer removing means, and the self-cleaning tablet is adversely affected. In addition, hemispherical or other shapes of 2 mm or more in diameter have an undesirable effect on magnetic domain refining due to wear.

3 shows the degree of wear of the work tip with the result of using iron needles as a comparative example.

In the method of the present invention, an ultrasonic vibration of 30 kHz is applied to a work tip of an electrodeposited diamond and the work tips are moved under a load of 10 kg / mm ^{2 in} a direction perpendicular to the rolling direction so that grooves having a parallel and spacing of 5 mm are formed. By forming, the oxide layer was locally removed from the surface of the steel sheet after the secondary recrystallization annealing.

On the other hand, as a comparative example, iron needles under a load of 100 kg / mm ² or a scrubber of electrodeposited diamond under a load of 20 kg / mm ² were used to form grooves parallel to each other and having a spacing of 5 mm.

As can be seen in FIG. 3, the wear rate of the working team is the largest in the iron needle, while the electrodeposited diamond subjected to the ultrasonic vibration according to the present invention has no weight loss, but the electrodeposited diamond used under a load of 20 kg / mm ² . The tip of is broken and loses weight, which adversely affects the removal of oxides.

According to the present invention, if electrolytic etching is performed after locally removing the oxide layer by application of ultrasonic vibration, iron loss can be further reduced. In this case, the etching depth of the grooves is preferably 20 μm or less.

4 shows the relationship between the etching depth and the magnetic properties after the oxide layer is locally removed.

의 초경 작업팁에 인가하고 상기 작업팁에 의해 압연방향에 수직인 방향으로 서로 평행이고 간격이 8mm인 홈을 형성시킴으로써 산화물층을 국부적으로 제거했다. 다음에 NH₄Cl-NaCl(100g/l-100g/l)의 수용액에서 5A/dm²의 전류밀도로 전해에칭을 수행했다. 에칭깊이는 에칭시간을 변화시킴으로써 결정했다. 자기적 특성에 대한 에칭 효과는 제 4 도에 나타낸다.In this case, ultrasonic vibration with a frequency of 20 kHz and an amplitude of 15 μm is 1.5

The oxide layer was locally removed by applying to the cemented carbide tip and forming grooves parallel to each other with a spacing of 8 mm in the direction perpendicular to the rolling direction by the tip. Next, electrolytic etching was performed at a current density of 5 A / dm ² in an aqueous solution of NH ₄ Cl-NaCl (100 g / l-100 g / l). The etching depth was determined by changing the etching time. The etching effect on the magnetic properties is shown in FIG.

Grooves formed by electrolytic etching with materials that locally produce different tensile forces due to different coefficients of thermal expansion or magnetically different materials (e.g., metals, silicates, phosphorus compounds, oxides, nitrides, etc.) that form a semi-magnetic field In the case of filling with a predetermined external substance, the iron loss value is further improved. In this case, it is desired that the coefficient of thermal expansion of the external material is smaller than that of the silicon steel sheet to obtain another tensile effect.

5 shows the effect of improving the iron loss value by the filling of the foreign material. In this case, a groove having a depth of 10 mu m was formed by local removal of the oxide and electroetching in the same manner as in the fourth degree. The grooves were then Sb plated and strain corrected annealing at 800 ° C. for 3 hours.

Next, the application of ultrasonic vibration to the surface of the steel sheet according to the present invention will be described in detail with reference to FIGS.

6a and 6b show a first embodiment of the method according to the invention. After the second recrystallization annealing, the grain-oriented silicon steel sheet 1 is moved around the roller 2 supported by the bearing 3. On the other hand, the head portion 4 of the ultrasonic wave generating device is arranged facing the surface of the moving steel sheet around the roller 3. And the head part 4 is equipped with the several ultrasonic vibration member 5 arrange | positioned staggered upwards or downwards of the head part 4. In addition, the head part 4 is reciprocally movable in the width direction of the moving steel plate 1 through the screws 6 supported at both ends by the bearing 7 and the motor 8.

In figure 8 the ultrasonic vibration member 5 is shown in detail. Each of the ultrasonic vibration members 5 staggered in the head portion 4 is provided with the ultrasonic vibration members 5 acting toward the surface of the moving steel sheet 1 at both ends in the width direction of the steel sheet by the action of the air cylinder 15, And connected to the air cylinder 16 supported by the head 4 in such a way that it does not damage the surface of the roller 2 by moving away from the surface. In addition, the pressing force of the work tip 14 against the steel sheet 1 can be controlled by adjusting the air pressure applied from the air cylinder 15 to the ultrasonic vibration member 5.

When the oxide layer is removed continuously and locally from the surface of the silicon steel sheet by applying ultrasonic vibration in the apparatus shown in FIG. 6, first, the number of the ultrasonic vibration members 5 used and the moving speed of the head portion 4 are changed. To determine the balance with the feed rate of the steel sheet (1). In this case, the oxide removal is carried out in the advancing step of the head part, and the ultrasonic vibration member is moved away from the steel plate surface in the advancing step of the head part. The advancing and reversing steps of the head portion are repeated continuously to locally remove the oxide layer from the surface of the moving steel sheet. 9 shows the removal track of the oxide layer.

In addition, the removal track shown in FIG. 10 can be obtained by supplying the steel plate 1 intermittently.

7a and 7b show a second embodiment of an apparatus for locally removing an oxide layer from the surface of a grain-oriented silicon steel sheet after secondary recrystallization annealing by applying ultrasonic vibrations according to the present invention. By continuously supplying the steel sheet, a removal track as shown in FIG. 10 is obtained.

As shown in FIGS. 7A and 7B, the end of the arm 9 is connected to each of the bearings 3 located at both ends of the roller 2, and the segment gear is connected to the arm 9. It is formed on the other end. The segment gear of this arm 9 is supported by the support 10 and is engaged with the pinion gear 12 of the pinion side 11 connected to the drive motor 13. On the other hand, the screw shaft 6 for supporting and moving the head portion 4 of the device for generating ultrasonic vibration is supported by the arm 9.

According to the above structure, the head part 4 synchronizes the engagement movement between the segment gear and the pinion gear, and moves in the direction of movement of the plate or the peripheral direction of the roller 2 with the feeding speed of the plate by the driving motor. At the same time, the head part 4 is moved in the width direction of the plate by the drive motor 8, whereby the removal track is formed in a direction perpendicular to the moving direction of the plate as shown in FIG. Can be.

In any case, when the number of ultrasonic vibration members used is increased, the formation efficiency (productivity) of the removal track is, of course, excellent. Moreover, in the case of using the apparatus of FIG. 6, if the removal track can be formed in the backward step, the inclination of the removal track is opposite to the track formed in the forward step, and the parallel track cannot be formed on the surface of the plate. Therefore, the removal track can be formed only in the forward step for the movement of the head 4. However, if the feed rate of the plate stops intermittently, a removal track can be formed even in the reverse stage.

On the other hand, in the case of using the apparatus of FIG. 7, it is possible to form a removal track in the forward and backward steps as shown in FIG. 10 while continuously feeding the plate. Therefore, in the latter apparatus, when the number of ultrasonic vibrating members and the feeding speed of the plate are the same, the production efficiency is doubled as compared with the former apparatus. In other words, the number of ultrasonic vibration members of the latter device can be reduced to half of the former device.

The work tip 14 of the ultrasonic vibration member 5 is made of diamond, ruby, brass, steel polished stone or the like as mentioned above. The applied vibration frequency is at least 20 kHz, preferably 25 to 50 kHz, and the pressing force of the work tip is up to 40 kg / mm ² . The work team 14 of the ultrasonic vibration member 5 can be easily inclined forward in the moving direction of the plate.

The spacing between adjacent ultrasonic vibrating members is preferably about 5 mm. Since the diameter of the roller 2 is at least 300 mm, it can be appropriately determined with the number of ultrasonic vibration members and the feeding speed of the plate without causing bending deformation of the plate. Steel, rigid rubber, etc. are suitable as the material of the roller. In the case of rigid rubber, the hardness is preferably at least 60 (Hs).

The following examples are given by way of illustration of the invention and are not intended as a limitation thereof.

Example 1

The hot rolled silicon steel sheet containing 3.27 wt% of Si (hereinafter simply referred to as%), Mn: 0.070%, Se: 0.019%, and Sb: 0.020% was subjected to two cold rolling processes, and the cold rolled layer was intermediate at 950 ° C. Annealing treatment gave a cold rolled steel sheet having a final thickness of 0.23 mm.

The cold rolled steel sheet was then subjected to primary recrystallization annealing at a temperature of 800 ° C. in a decarbonized and wet hydrogen atmosphere, and the surface was coated and wound with a slurry of an annealing separator composed mainly of MgO, and then in a box furnace. The secondary recrystallization annealing treatment was carried out at a temperature of 850 ° C. for 50 hours at, and purified annealing was performed at a temperature of 1200 ° C. in a dry hydrogen atmosphere for 10 hours.

After the excess annealing separator was removed only from the steel sheet surface, the steel sheet was treated under the conditions shown in Table 1 below.

_Iron loss W _17/50 (W / kg) of the steel sheet thus obtained was measured and the results are shown in Table 1.

TABLE 1

Frequency: 28.5kHz

Example 2

The hot rolled silicon steel sheet containing Si: 3.05%, Mn: 0.073%, Se: 0.020%, and Sb: 0.025% was subjected to two cold rolling treatments and subjected to intermediate annealing at 950 ° C during cold rolling to give a final thickness of 0.23 mm. A cold rolled steel sheet was obtained.

Next, the cold rolled steel sheet was subjected to primary recrystallization annealing at a temperature of 810 ° C. in a decarbonized and wet hydrogen atmosphere, and the surface was coated and wound with a slurry of an annealing separator mainly composed of Al ₂ O ₃ , and then into a box. The secondary recrystallization annealing treatment was performed at a temperature of 850 ° C. for 50 hours at and a purge annealing treatment at a temperature of 1200 ° C. in a dry hydrogen atmosphere for 10 hours.

After the annealing separator was removed, an insulating coating was formed on the surface of the steel sheet, followed by a flat sawn treatment. Next, a treatment was performed to locally remove the oxide layer under the conditions shown in Table 2 of the steel sheet thus treated. Next, the steel sheet was subjected to electrolytic etching treatment in an aqueous NaCl (100 g / L) solution at a current density of 30 A / dm ² for 10 seconds, followed by insulation coating with phosphate.

The iron loss W _17/50 (W / kg) of the steel sheet thus obtained was measured and results are obtained as shown in Table 2. Further, the standard steel sheet after the annealing treatment platform is B ₁₀ = 1.9T, and W _17/50 = 0.95W / kg.

TABLE 2

Frequency: 28.5kHz

Example 3

The hot rolled silicon steel sheet containing Si: 3.25%, Mn: 0.072%, Se: 0.018%, and Sb: 0.025% was subjected to two cold rolling treatments and subjected to intermediate annealing at 950 ° C during cold rolling to give a final thickness of 0.23 mm. A cold rolled steel sheet was obtained.

Next, the cold rolled steel sheet was subjected to primary recrystallization annealing at a temperature of 820 ° C. in a decarbonized and wet hydrogen atmosphere, and the surface was coated and wound with a slurry of an annealing separator mainly composed of MgO, and 50 hours in a box furnace. Secondary recrystallization annealing treatment at a temperature of 850 ° C., and purifying annealing at a temperature of 1200 ° C. in a dry hydrogen atmosphere for 10 hours.

After the excess annealing separator was removed and the plate annealing treatment was performed, the steel sheet was subjected to an oxide layer local removal treatment under the conditions shown in the following Table 3. As in the previous treatment, electrolytic etching was performed in an aqueous NaCl (250 g / l ) solution at a current density of 30 A / dm ² for 10 seconds. Next, the formed grooves were filled with a bolosiloxane solution and gradually heated to 200 to 400 ° C to carry out firing. A portion of the steel plate was coated with antimonysol and dried at 100 ° C.

The iron loss W _17/50 (W / kg) of the steel sheet thus obtained was measured and the results are shown in Table 3. In addition, standard steel sheet after annealing is platform W = _17/50 has a 0.92W / kg and ₁₀ B = 1.91T in magnetic properties.

Table 3 (a)

Frequency: 28.5kHz

Table 3 (b)

Frequency: 28.5kHz

Example 4

A hot rolled silicon steel sheet containing Si: 3.28%, Mn: 0.074%, Se: 0.026, sol Al: 0.027%, and N: 0.0083% was annealed at a temperature of 1130 ° C. for 4 minutes and quenched. ), Pickled.

The steel sheet was then subjected to heavy cold rolling to obtain a cold rolled steel sheet having a final thickness of 0.23 mm. The cold rolled steel sheet was then subjected to primary recrystallization annealing at a temperature of 820 ° C. in a decarbonized and wet hydrogen atmosphere, and the surface was coated with a slurry of an annealing separator consisting mainly of MgO, and a temperature of 850 ° C. for 50 hours in a box furnace. The secondary recrystallization annealing treatment was performed, and the purification annealing treatment was carried out at a temperature of 1200 ° C. in a dry hydrogen atmosphere for 10 hours.

After the excess annealing separator was removed and the plate annealing was carried out, the steel sheet was subjected to an oxide layer local removal treatment under the conditions shown in Table 3 below.

_Iron loss value W _17/50 (W / kg) of the steel sheet thus obtained was measured, the results are shown in Table 4. In addition, standard steel sheet after annealing is platform W = _17/50 has a 0.89W / kg and ₁₀ B = 1.92T in magnetic properties.

TABLE 4

Frequency: 28.5kHz

Example 5

After the second recrystallization annealing, the oxide layer is localized at intervals of 8 mm from the surface of the grain-oriented silicon steel sheet having a diameter of 1 mm and a sintered diamond in a direction perpendicular to the rolling direction by linearly pushing a work tip made of sintered diamond. Removed. In this case, ultrasonic vibrations with a frequency of 25 KHz and an amplitude of 20 μm were applied to the work tip and the pressing force was 10 kg / mm ² .

Similarly, oxide was removed using cemented carbide at a sharp point without applying ultrasonic vibrations. In this case a load of 10 kg / mm ² was applied to the work tip.

After removing the oxide layer, electrolytic etching was performed in aqueous NaCl solution (200 g / l ) for 10 seconds at a current density of 10 A / dm ² , and then the plated Ni was plated and strain-corrected annealing treatment (800 ° C. × 2 hours). ) The magnetic properties of the steel sheet thus obtained are shown in Table 5.

TABLE 5

As described above, according to the present invention, grain-oriented steel sheets which have very low iron loss and which do not lose the effect of self-crystallization even after strain correction annealing can be produced without causing the reduction of lamination rate and B ₁₀ value unavoidable in the prior art. have.

Claims (8)

In the method for producing a low iron loss grain oriented silicon steel sheet from a silicon steel sheet having an oxide layer after the second recrystallization annealing without causing the deterioration of characteristics through the strain calibration annealing, (a) conditions of limited pressure of 40kg / mm ² or less Applying ultrasonic vibration to the surface of the grain-oriented silicon steel sheet after the secondary recrystallization annealing under the following step, and (b) applying the ultrasonic vibration without substantially forming a newly recrystallized particle group on the surface. Locally removing the oxide layer portion, controlling the oxide layer removing portion to have a width of 10 to 1000 µm, a dotted line or a straight line, parallel to each other, and formed at intervals of 1 to 30 mm, and (c) the ultrasonic vibration. Providing an effective vibration component in a direction perpendicular to the surface of the steel sheet, wherein the ultrasonic vibration has a frequency of 20 KHz or more and A method for producing a low iron loss grain-oriented silicon steel sheet having a width of 50 μm or less. The method for producing a low iron loss grain-oriented silicon steel sheet according to claim 1, wherein after the oxide layer is locally removed, the steel sheet is electroetched. The method for producing a low iron loss grain-oriented silicon steel sheet according to claim 1, wherein after the oxide layer is locally removed, the steel sheet is subjected to electroetching, and the external material is filled in the etched portion. The method of claim 1, wherein ultrasonic vibration is applied to face the surface of the steel sheet to reciprocate in the width direction of the steel sheet, and can move toward and away from the surface of the moving steel sheet and move up and down. Arranging a plurality of ultrasonic vibrations that can move to each other, applying ultrasonic vibration to the surface while applying each ultrasonic vibration at a predetermined pressure to the surface of the steel sheet, and reciprocating the vibration in the width direction of the steel sheet. A method for producing a low iron loss grain oriented silicon steel sheet, wherein local removal of an oxide layer is performed by repeating the movement to form removal portions at predetermined intervals on the surface of the steel sheet in the direction of resin in the rolling direction. The method of manufacturing a low iron loss grain-oriented silicon steel sheet according to claim 4, wherein the vibration is moved up and down in the moving direction of the steel sheet in synchronism with the moving speed of the steel sheet and moved in the width direction of the steel sheet. The method of claim 1, wherein the vibration is made of a material selected from the group consisting of diamond, ceramics, ruby, and cemented carbide, and the shape thereof is needle-shaped or plate-shaped. The method for producing a low iron loss grain oriented silicon steel sheet according to claim 2, wherein the etching depth by said electrolytic etching is 20 m or less. The method of claim 3, wherein the foreign material is selected from the group consisting of metals, silicates, phosphorus compounds, oxides, and nitrides.

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