JP6075106B2 - Slurry coating apparatus and slurry coating method - Google Patents

Description

  The present invention relates to a slurry coating apparatus and a slurry coating method for coating a slurry of an annealing separator for preventing seizure when performing high temperature annealing on a coil wound with a grain-oriented electrical steel sheet to the grain-oriented electrical steel sheet. .

  Conventionally, grain-oriented electrical steel sheets are mainly used as iron core materials for transformers, generators, and other electrical devices. Therefore, the grain-oriented electrical steel sheet is required to have a good surface coating in addition to good magnetic properties (iron loss).

The surface coating of the steel plate is made of a ceramic coating called a forsterite coating. When forming a forsterite film, first, a material that has been rolled to a predetermined thickness by cold rolling is used as a raw material, and an oxide film (subscale) containing silicon oxide (SiO ₂ ) as a base material for this material. ). Next, after applying magnesium oxide (MgO) on the oxide film, the steel sheet is wound into a coil shape. Thereafter, in the final annealing step, the coiled grain-oriented electrical steel sheet is heat-treated at a high temperature of 1000 ° C. or higher. Thereby, SiO ₂ and MgO react on the surface of the steel sheet to form a forsterite film (Mg ₂ SiO ₄ film). Note that MgO applied to the surface of the steel sheet also serves as an adhesion preventing agent for preventing adhesion between coil layers in the final annealing step, and is also referred to as an annealing separator. After the finish annealing, the steel sheet is flattened (flattened) to correct the shape of the steel sheet to obtain a product.

  Further, this annealing separator such as MgO is generally suspended in water to form a slurry. Then, on the exit side of the continuous annealing furnace in the decarburization annealing step, the supply nozzle and the squeeze roll apply this slurry so as to have a predetermined film thickness on both the upper surface and the lower surface of the strip. At this time, a liquid pool is often formed on the entrance side of the squeeze roll on the upper surface side of the belt-like body. Subsequently, after the annealing separator is dried in a drying furnace, the strip is wound to obtain a coil.

  Conventionally, these supply nozzles and squeeze rolls can adjust the film thickness of the slurry with squeeze rolls such as a rough application roll and an application roll after the slurry is supplied to the belt-like body with the supply nozzle as described in Patent Document 1. Placed in. Depending on the required accuracy of film thickness and installation space restrictions, when only one of the coarse application roll and the application roll is installed, a nozzle is further provided between the coarse application roll and the application roll. It may be configured to supply slurry.

  Moreover, as described in Patent Document 2, there is a case where the slurry is supplied to the band by the supply nozzle after the band has passed through all the application rolls. In this case, a plurality of nozzles for supplying the slurry are installed at intervals of several hundred mm in the width direction that is perpendicular to the traveling direction of the strip.

JP 2004-57971 A JP-A-62-67118

  By the way, after the flattening annealing in the manufacturing process of the steel sheet described above, a strip-like shape parallel to the longitudinal direction may occur in the belt-shaped body that is the steel sheet. Of the band-like body, the portion where such a shape defect has occurred does not become a product, so it must be discarded. For this reason, the occurrence of shape defects leads to a decrease in yield in the production of steel sheets. However, the details of the mechanism by which this saddle-shaped defect occurs are not clear, and the development of a technique for suppressing the occurrence of this saddle-shaped defect has been demanded.

  The present invention has been made in view of the above, and the object thereof is to suppress the occurrence of saddle-like shape defects along the longitudinal direction of a steel sheet, which are likely to occur after flattening annealing in the manufacture of a steel sheet. An object of the present invention is to provide a slurry coating apparatus and a slurry coating method capable of improving the yield in the production of steel sheets.

  In order to solve the above-described problems and achieve the above object, the slurry coating apparatus according to the present invention is configured to be able to supply slurry to a traveling belt-like body, and is parallel to the surface of the belt-like body. Slurry discharge means configured to be swingable in a direction perpendicular to the traveling direction, and a pair of application means configured to be able to apply the supplied slurry to the surface of the band-like body by holding and pressing the band-like body And.

  In the slurry application apparatus according to the present invention, in the above invention, the slurry discharge means is provided upstream of the pair of application means along the traveling direction of the belt-like body, and the pair of application means. A second slurry discharge means configured to be able to supply slurry to the traveling belt-like body is provided on the downstream side in the traveling direction of the belt-like body. In this configuration, the second slurry discharge means is configured to be swingable in a direction perpendicular to the traveling direction of the band-like body parallel to the surface of the band-like body.

  In the slurry application apparatus according to the present invention, in the above invention, the slurry discharge means is provided on the downstream side in the traveling direction of the belt-like body with respect to the pair of application means, and the pair of application means A third slurry discharge means configured to be able to supply slurry to the traveling belt-like body is provided on the upstream side in the traveling direction of the belt-like body.

  The slurry coating apparatus according to the present invention is characterized in that, in the above invention, the temporal change of the swing amount in the swing is a rectangular wave shape, a sine wave shape, or a triangular wave shape.

  The slurry coating apparatus according to the present invention is characterized in that, in the above-described invention, each slurry coating apparatus that holds the slurry discharge means is configured to be swingable with respect to the traveling belt-like body.

  The slurry application apparatus according to the present invention is characterized in that, in the above invention, the oscillation frequency of the slurry discharge means is set based on a turn pitch of a coil formed by winding a belt-like body.

  The slurry application apparatus according to the present invention is characterized in that, in the above invention, the oscillation frequency of the slurry discharge means is set based on an even multiple of the turn pitch.

  A slurry application method according to the present invention includes a slurry supply step for supplying a slurry while swinging in a direction perpendicular to the traveling direction of the strip and parallel to the surface of the strip with respect to the traveling strip. And a slurry applying step of applying the slurry to the surface of the band by pressing the supplied band and holding it.

  The slurry application method according to the present invention is characterized in that, in the above invention, the method further includes a second slurry supply step for supplying the slurry to the traveling strip after the slurry application step.

  In the slurry application method according to the present invention, in the above invention, in the second slurry supply step, the slurry is swung in the direction parallel to the surface of the band and perpendicular to the traveling direction of the band. It is characterized by supplying while letting go.

  In the slurry application method according to the present invention, in the above invention, the slurry is supplied in the third slurry supply step and the third slurry supply step for supplying the slurry to the traveling strip before the slurry supply step. And a second slurry application step of applying the slurry to the surface of the band by pressing the gripped band.

  The slurry application method according to the present invention is characterized in that, in the above invention, the temporal change of the swing amount in the swing is a rectangular wave shape, a sine wave shape, or a triangular wave shape.

  The slurry application method according to the present invention is characterized in that, in the above invention, the oscillation frequency in the oscillation is set based on a turn pitch of a coil formed by winding a strip.

  The slurry application method according to the present invention is characterized in that, in the above invention, the oscillation frequency in the oscillation is set based on an even multiple of the turn pitch.

  According to the slurry coating apparatus and the slurry coating method according to the present invention, it is possible to suppress the occurrence of saddle-like shape defects along the longitudinal direction of the steel sheet, which are likely to occur after flattening annealing in the production of the steel sheet, and manufacture of the steel sheet. It becomes possible to improve the yield in.

FIG. 1 is a schematic diagram showing a slurry coating apparatus according to an embodiment of the present invention. FIG. 2 is a conceptual diagram showing a conventional slurry coating apparatus and the film thickness distribution of the annealing separator slurry on the surface of the belt-like body. FIG. 3A is a cross-sectional perspective view of a coil of a belt-like body to which a conventional annealing separator slurry is applied. FIG. 3B is a partially enlarged cross-sectional view of a portion surrounded by a broken line in FIG. 3A. FIG. 4A is a graph showing an example of swing control of the slurry supply nozzle of the slurry application device according to the embodiment of the present invention. FIG. 4B is a graph showing an example of swing control of the slurry supply nozzle of the slurry application apparatus according to the embodiment of the present invention. FIG. 4C is a graph illustrating an example of swing control of the slurry supply nozzle of the slurry application apparatus according to the embodiment of the present invention. FIG. 5 is a conceptual diagram showing the film thickness distribution of the annealing separator slurry on the surface of the belt-like body when the slurry application device according to one embodiment of the present invention and the slurry supply nozzle are controlled in a sine wave shape. FIG. 6A is a conceptual diagram showing the film thickness distribution of the annealing separator slurry on the surface of the belt-like body when the slurry application device according to one embodiment of the present invention and the slurry supply nozzle are controlled in a rectangular wave shape. FIG. 6B is a partially enlarged cross-sectional view of a state in which a strip-like body coated with an annealing separator slurry according to an embodiment of the present invention is coiled. FIG. 7A is a configuration diagram illustrating a first modification of the slurry application device according to the embodiment of the present invention. FIG. 7B is a configuration diagram illustrating a second modification of the slurry application device according to the embodiment of the present invention. FIG. 7C is a configuration diagram illustrating a third modification of the slurry application device according to the embodiment of the present invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In all the drawings of the following embodiments, the same or corresponding parts are denoted by the same reference numerals. Further, the present invention is not limited to the embodiments described below.

  First, in order to facilitate the understanding of the contents of the present invention, a diligent study conducted by the present inventors for a slurry coating apparatus and a slurry coating method will be described. First, a slurry coating apparatus according to this embodiment will be described. FIG. 1 is a configuration diagram showing a slurry application device for applying an annealing separator slurry.

  As shown in FIG. 1, the slurry application device 20 according to this embodiment includes a squeeze roll 2 and a slurry supply nozzle 3. The slurry supply nozzle 3 is a slurry discharge means having a plurality of discharge ports for applying the annealing separator slurry 4 to the strip 1 that is a grain-oriented electrical steel sheet. The squeeze roll 2 is a pair of application means that squeeze the annealing separator slurry 4 applied on the strip 1 to a predetermined thickness. In addition, although mentioned later for details, the slurry supply nozzle 3 in this one embodiment is along the direction perpendicular to the feeding direction (traveling direction) parallel to the surface with respect to the strip 1, that is, along the width direction of the strip 1. And can be swung.

  In the application of the annealing separator slurry 4 using this slurry application apparatus, after the slurry supply nozzle 3 applies the annealing separator slurry 4 to the strip 1, the squeeze roll 2 is applied to the surface of the strip 1. The annealed separator slurry 4 is squeezed to a predetermined film thickness. After that, the strip 1 is subjected to various processes such as a finish annealing process (secondary recrystallization annealing process), a coating process, and a flattening annealing process, and finally becomes a product of an electromagnetic steel sheet.

  Here, when the conventional slurry application apparatus was used, the present inventors examined the saddle-like shape defect formed on the surface of the strip 1 after flattening annealing. As a result, it was found that a certain correlation was observed between the generation position along the width direction of the strip 1 and the installation position along the width direction of the slurry supply nozzle 3 with respect to the shape defect. Then, the inventors pay attention to the fact that the film thickness of the annealing separator slurry 4 has a non-uniform distribution along the width direction of the strip 1, and this film thickness distribution affects the shape defect. I came to remember.

  FIG. 2 shows the configuration of this conventional slurry coating apparatus and the width direction of the strip 1 of the annealing separator slurry 4 after the annealing separator slurry 4 on the strip 1 is narrowed to a predetermined film thickness. The film thickness distribution is shown.

  As shown in FIG. 2, when the slurry supply nozzle 3 supplies the annealing separator slurry 4 to the surface of the strip 1, the film thickness of the annealing separator slurry 4 is at a position close to each discharge port of the slurry supply nozzle 3. It is considered to be larger and smaller at a distant position. Therefore, in the conventional slurry coating apparatus 100, the film thickness distribution along the width direction and the film thickness distribution along the longitudinal direction of the strip 1 in the annealing separator slurry 4 are controlled. Thereby, the thickness difference of the film thickness of the annealing separator slurry 4 on the surface of the strip 1 falls within a predetermined range, and thus the thickness difference of the film thickness of the annealing separator slurry 4 falls within the predetermined range. However, the occurrence of the above-described defective shape could not be avoided.

  According to the knowledge of the present inventors, it is inevitable that a slight film thickness distribution of the annealing separator slurry 4 resulting from the installation position of the discharge port of the slurry supply nozzle 3 occurs on the surface of the strip 1. That is, uneven application of the annealing separator slurry 4 composed of a crest portion having a relatively large film thickness and a trough portion having a relatively small film thickness is caused by the position of the discharge port of the slurry supply nozzle 3, which is an inevitable phenomenon. It is believed that there is.

  Therefore, the present inventors conducted further earnest studies, and further examined the influence of uneven application of the annealing separator slurry 4 on the occurrence of shape defects.

  And when the present inventors wind up the strip | belt-shaped body 1 which apply | coated the annealing separator slurry 4 and make it a coil, the peak part and trough part of the annealing separator slurry 4 will always be the same position in the width direction of the strip | belt-shaped body 1. We focused on the points that exist in Here, FIG. 3A is a cross-sectional view along the width direction of the strip 1 in a state in which the strip 1 coated with the annealing separator slurry 4 is wound into a coil 10, and FIG. 3B is a cross-sectional view of FIG. It is a cross-sectional enlarged view of a dotted line enclosing part.

  That is, as shown in FIG. 3A, when the strip 1 is wound into a coil shape to form a hollow cylindrical coil 10, the peak of the annealing separator slurry 4 on the surface of the strip 1 is formed as shown in FIG. 3B. The coils 10 are sequentially laminated in the radial direction of the circle in the cross section along the longitudinal direction of the strip 1, so-called build-up occurs, and the annealing separator slurry 4 protrudes (inside the dotted line in FIG. 3B). And it is thought that the build-up of the peak part of the annealing separator slurry 4 on the surface of the strip 1 causes the shape defect of the strip 1 during the finish annealing. In addition, the position of the streak pattern due to the coating unevenness visually recognized after supplying the annealing separator slurry 4 to the surface of the strip 1 does not necessarily match the position of the shape defect formed on the surface of the strip 1.

  From the above, the present inventors have a non-uniform film thickness rather than completely suppressing the occurrence of a non-uniform film thickness distribution of the annealing separator slurry 4 along the width direction of the strip 1 that is unavoidable. Recalling that the occurrence of shape defects can be suppressed if the distribution of the film thickness is made as gentle as possible, or the build-up when the strip 1 is made into a coil can be suppressed on the premise of the occurrence of the distribution.

  Therefore, as shown in FIG. 1, the slurry application device 20 according to an embodiment of the present invention is configured so that the slurry supply nozzle 3 having a plurality of discharge ports is parallel to the surface of the strip 1 and perpendicular to the traveling direction. The structure which rocks along the direction, ie, the width direction of the strip | belt-shaped body 1, is employ | adopted.

  4A, 4B, and 4C are all graphs showing an example of a control method in which the amount of rocking when the slurry supply nozzle 3 is rocked is changed over time. FIG. 5 is a configuration diagram of the slurry application device and a graph showing the film thickness distribution of the annealing separator slurry 4 on the surface of the strip 1 when the slurry supply nozzle 3 is controlled based on the graph shown in FIG. 4A.

  The slurry supply nozzle 3 swings in a sine wave shape as shown in FIG. 4A or swings in a triangular wave shape as shown in FIG. 4B along the width direction of the strip 1. Thereby, as shown in the graph of the film thickness distribution of the annealing separator slurry 4 in FIG. 5, the film thickness distribution of the annealing separator slurry 4 along the width direction of the strip 1 is the slurry supply as shown in FIG. Compared with the case where the annealing separator slurry 4 is discharged in a state where the nozzle 3 is fixed without being swung, it becomes gentle. Here, the swinging width of the slurry supply nozzle 3 shown in FIG. 5 is desirably about ½ of the interval between the discharge ports adjacent to each other in the plurality of discharge ports in the slurry supply nozzle 3. Thereby, the supply of the annealing separator slurry 4 is averaged with respect to the width direction of the strip 1 between the plurality of discharge ports of the slurry supply nozzle 3.

  Also, the pitch T shown in FIGS. 4A and 4B is preferably 1 to 150 seconds, and preferably 2 to 120 seconds. Thereby, as shown in FIG. 5, the annealing separator slurry 4 is gently applied to the surface of the band-shaped body 1 as compared with the non-uniformity of the film thickness distribution of the annealing separator slurry 4 shown in FIG. Since the portion and the peak portion are gently formed, the film thickness distribution is relaxed and becomes gentle, and the occurrence of shape defects on the surface of the band 1 can be prevented. In the case where the slurry supply nozzle 3 is controlled to have a triangular wave shape, actually, the triangular wave-like folded end portion has a smooth substantially triangular wave shape waveform as shown in FIG. In some cases, a trapezoidal wave shape may be obtained by stopping at this end portion for a finite period of time. However, these oscillations are also included in the triangular wave oscillation.

  6A shows two layers of the annealing separator slurry 4 on the surface of the band 1 when the amount of oscillation of the slurry supply nozzle 3 is controlled based on the configuration diagram of the slurry application device and the graph shown in FIG. 4C. It is a graph which shows film thickness distribution. 6B corresponds to FIG. 3B in the case where the annealing separator slurry 4 is applied to the surface of the strip 1 as shown in FIG. 6A and then wound into a coil to form the coil 10 shown in FIG. 3A. 2 is a partial enlarged cross-sectional view showing a laminated structure of a coil 10. FIG.

  When the slurry supply nozzle 3 swings in a rectangular wave shape along the width direction of the strip 1 as shown in FIG. 4C, when the strip 1 is used as the coil 10 as shown in the graph of the film thickness distribution in FIG. In addition, the crests and troughs of the annealing separator slurry 4 overlap between the two layers of the laminated strip 1. Here, it is desirable that the swinging width of the slurry supply nozzle 3 be about ½ of the interval between adjacent discharge ports in the plurality of discharge ports.

  Further, the pitch T shown in FIG. 4C is 1 to 150 seconds, and preferably 2 to 120 seconds. This is because if the pitch T in the case of controlling the time variation of the oscillation amount to be a rectangular wave is too shorter than 1 second, the non-uniformity of the film thickness distribution of the annealing separator slurry 4 as shown in FIG. 2 remains. If the length is longer than 150 seconds, the amount of shift per turn when the strip 1 is used as the coil 10 becomes small, and the crest and trough of the annealing separator slurry 4 do not overlap between the two layers. This is because a buildup as shown in FIG. Even when the slurry supply nozzle 3 is controlled to have a rectangular wave shape, since the moving speed of the slurry supply nozzle 3 is finite, it is difficult to move the nozzle instantaneously along the plate width direction. Actual swing is substantially trapezoidal, but this swing is also included in the rectangular wave swing.

  As a result, as shown in FIG. 6B, the peaks and valleys in the film thickness distribution of the annealing separator slurry 4 are sequentially along the radial direction of the circle of the section along the longitudinal direction of the strip 1 in the coil 10. Since they are stacked, the build-up described above can be prevented. Therefore, it is possible to suppress the occurrence of a shape defect in the band 1.

  Regarding the swing of the slurry supply nozzle 3, it is simple to swing only the slurry supply nozzle 3, but the present invention is not necessarily limited to this. Specifically, even if the slurry supply nozzle 3 is swung with respect to the strip 1 by swinging the entire slurry application device 20 that holds the slurry supply nozzle 3 with respect to the traveling strip 1, Ancillary equipment such as a coating roll provided in the slurry coating apparatus 20 may be swung together.

(Modification)
Next, the configuration of the slurry coating apparatus in the separating agent coating process to which the apparatus configuration according to the above-described embodiment can be applied will be described. 7A, FIG. 7B, and FIG. 7C are configuration diagrams of a slurry application device showing a first modification, a second modification, and a third modification, respectively.

(First modification)
As shown in FIG. 7A, the slurry coating apparatus 21 according to the first modification includes a rough coating roll 2a, a pair of backup rolls 2b, a pair of coating rolls 2c, and a pair of nozzles 3a before the rough coating roll. The pair of pre-rough application roll nozzles 3 a is a pair of slurry discharge means for discharging the annealing separator slurry 4 to both surfaces of the strip 1. The pair of rough coating rolls 2a is a pair of coating means for roughly coating the both surfaces of the strip 1 with the annealing separator slurry 4 supplied by the nozzle 3a before the rough coating roll. The pair of coating rolls 2 c is a coating unit that squeezes the coarsely coated annealing separator slurry 4 supported by a pair of backup rolls 2 b provided on both sides of the strip 1. And in the slurry application apparatus 21 by this 1st modification, the nozzle 3a before rough application roll is comprised so that rocking | fluctuation is possible along the width direction (FIG. 7A, paper surface perpendicular | vertical direction) of the strip | belt-shaped body 1. FIG. .

(Second modification)
In the second modification, as shown in FIG. 7B, the slurry application device 22 is a rough application as the slurry discharge means or the second or third slurry discharge means in the slurry application apparatus 21 according to the first modification. The slurry discharge means or the third or second slurry discharge means is disposed downstream of the pre-roll nozzle 3a and upstream of the pair of application rolls 2c in the traveling direction of the band 1 on one surface side of the band 1 The nozzle 3b before the application roll is provided. And in this slurry application device 22, the nozzle 3a before rough application roll and the nozzle 3b before application roll are comprised so that rocking | fluctuation is possible along the width direction (paper surface perpendicular | vertical direction in FIG. 7B) of the strip | belt-shaped body 1. FIG.

(Third Modification)
In the third modification, as shown in FIG. 7C, the slurry application device 23 is further downstream in the traveling direction of the strip 1 of the pair of application rolls 2c in the slurry application device 21 according to the first modification. In addition, a post-application-roll nozzle 3c as a second slurry discharge means is provided. In the slurry application device 23 according to the third modification, the rough application roll pre-roller nozzle 3a and the post-apply roll nozzle 3c swing along the width direction of the strip 1 (the vertical direction in FIG. 7C). It is configured to be possible.

  Next, an example based on the second modification of the embodiment of the present invention described above and a comparative example based on the conventional technique will be described. The present invention is not limited to these examples.

(Examples 1 to 30 and Comparative Example 1)
In Examples 1 to 30 and Comparative Example 1, first, a cold-rolled sheet of grain-oriented electrical steel sheet containing 3.4% by weight of silicon (Si) having a final sheet thickness of 0.3 mm is used as the strip 1. . And after performing decarburization annealing with respect to this strip | belt body 1, the annealing separation agent slurry 4 was apply | coated to the strip | belt body 1 using the slurry application | coating apparatus 22 by a 2nd modification. Specifically, the coating amount of the annealing separator slurry 4 per one surface is oxidized on both surfaces of the strip 1 by setting the coating amount of the annealing separator slurry 4 per side to 7.0 g / m ² by the nozzle 3a before the rough coating roll and the nozzle 3b before the coating roll. Apply magnesium (MgO). Then, after winding the strip | belt-shaped body 1 into the coil 10, finish annealing is performed with respect to this coil 10 on 1200 degreeC temperature conditions. After the finish annealing, the shape of the belt-like body 1 is corrected in a flattening annealing furnace at a temperature of 850 ° C. And the presence or absence of the shape defect along a longitudinal direction was test | inspected visually with respect to the strip | belt-shaped body 1 by which shape correction was carried out.

  In these Examples 1-30, the rocking | fluctuation of at least one of the nozzle 3a before a rough application roll and the nozzle 3b before an application roll at the time of apply | coating the annealing separator slurry 4 to the surface of the strip | belt body 1 is as follows. Do.

  In Examples 1 to 5, only the nozzle 3a before the rough coating roll is set to have a pitch T shown in FIG. 4A of 1 second, 2 seconds, 60 seconds, 120 seconds, and 150 seconds, respectively, and the change over time in the swing amount is sine. It is controlled and swung in a wave shape. In Examples 6 to 10, only the nozzle 3b before the application roll is set to have a pitch T shown in FIG. 4A of 1 second, 2 seconds, 60 seconds, 120 seconds, and 150 seconds, respectively, and the change in the amount of fluctuation is sinusoidal. Control and swing. In Examples 11 to 15, only the nozzle 3a before the rough coating roll is used, and the pitch T shown in FIG. 4C is set to 1 second, 2 seconds, 60 seconds, 120 seconds, and 150 seconds, respectively. Control and swing. In Examples 16 to 20, only the nozzle 3b before the application roll is set to a rectangular wave shape with the pitch T shown in FIG. 4C set to 1 second, 2 seconds, 60 seconds, 120 seconds, and 150 seconds, respectively. Control and swing. In Examples 21 to 25, both the pre-coating roll pre-roller nozzle 3a and the pre-coating roll pre-nozzle 3b have a pitch T shown in FIG. 4A of 1 second, 2 seconds, 60 seconds, 120 seconds, and 150 seconds, respectively. The time change is controlled in a sine wave shape and oscillated. In Examples 26 to 30, both the rough coating roll pre-nozzle roller 3a and the pre-coating roll nozzle 3b have a pitch T shown in FIG. 4C of 1 second, 2 seconds, 60 seconds, 120 seconds, and 150 seconds, respectively. The time change is controlled to a rectangular wave shape and oscillated. Further, in Comparative Example 1, the annealing separator slurry 4 is applied to the surface of the strip 1 without swinging the nozzle 3a before the rough application roll and the nozzle 3b before the application roll, as in the prior art. Table 1 is a table showing the results of Examples 1 to 30 and Comparative Example 1 described above.

  From Table 1, in Examples 1-30, it turns out that the generation | occurrence | production of the shape defect of the grain-oriented electrical steel sheet which is the strip | belt-shaped body 1 does not occur at all, or is reduced compared with the past. In contrast, in Comparative Example 1, it can be seen that a shape defect has occurred. From comparison between Examples 1 to 30 and Comparative Example 1, as in Examples 1 to 30, at least one of the nozzle before rough coating roll 3a and the nozzle before coating roll 3b is arranged along the width direction of the band 1. It can be seen that the occurrence of shape defects in the grain-oriented electrical steel sheet can be suppressed by swinging.

  Moreover, in Table 1, when the example in which the shape defect is reduced and the example in which there is no shape defect are compared, at least one of the nozzle 3a before the rough application roll and the nozzle 3b before the application roll has a pitch T of 2 to 120. It can be seen that by applying the annealing separator slurry 4 while being swung as seconds, shape defects do not occur in the grain-oriented electrical steel sheet. Therefore, it can be seen that the pitch T in the oscillation of the slurry supply nozzle 3 is preferably 2 to 120 seconds.

(Examples 31 to 36 and Comparative Example 2)
In Examples 31 to 36 and Comparative Example 2, first, a cold-rolled sheet of a grain-oriented electrical steel sheet having a final sheet thickness of 0.23 mm containing 3.4% by weight of silicon (Si) is used as the strip 1. And after performing decarburization annealing with respect to this strip | belt body 1, the annealing separation agent slurry 4 was apply | coated to the strip | belt body 1 using the slurry application | coating apparatus 22 by a 2nd modification. Specifically, the coating amount of the annealing separator slurry 4 per one surface is oxidized on both surfaces of the strip 1 by setting the coating amount of the annealing separator slurry 4 per side to 7.0 g / m ² by the nozzle 3a before the rough coating roll and the nozzle 3b before the coating roll. Apply magnesium (MgO). Then, after winding the strip | belt-shaped body 1 into the coil 10, finish annealing is performed with respect to this coil 10 on 1200 degreeC temperature conditions. After the finish annealing, the shape of the belt-like body 1 is corrected in a flattening annealing furnace at a temperature of 850 ° C. And the presence or absence of the shape defect along a longitudinal direction was test | inspected visually with respect to the strip | belt-shaped body 1 by which shape correction was carried out.

  In these Examples 31 to 36, when the annealing separator slurry 4 was applied to the surface of the strip 1, the coarse coating roll pre-nozzle 3 a was swung based on the following technical idea.

  The effect of swinging the coating nozzle of the annealing separator slurry 4 in the present invention in the steel plate width direction is to disperse minute fluctuations in the coating amount of the annealing separator slurry 4 due to the arrangement of the coating nozzles in the steel plate width direction. This is to promote the homogenization of the coating amount of the annealing separator slurry 4 on the steel plate. Furthermore, since this steel sheet is wound after application of the annealing separator slurry 4 to form a coil, the combination of the coating amount on the steel sheet of the annealing separator slurry 4 adjacent to or adjacent to the radial direction of this coil is made constant. It is considered more desirable to do so.

  Based on such an idea, it is recalled that it is desirable to change the oscillation period of the coating nozzle of the annealing separator slurry 4 in consideration of the turn pitch of the coil of the steel plate. In this embodiment, the coating nozzle is not swung for one cycle every one turn pitch, but is swung for one cycle every two turn pitches. As a result, the present inventors have found that there is a possibility that the total amount of the annealing separator slurry 4 applied between the layers of the coiled steel sheet may be further homogenized in the width direction of the steel sheet.

  Therefore, in Examples 31 to 36, the ratio (V / 2L) between the line speed V of the strip 1 and twice the turn pitch L of the coil 10 is defined as the turn pitch frequency (unit: [Hz]). The line speed V and the coil diameter of the coil 10 were set so that the turn pitch frequency was 0.665 Hz. At this time, the swinging frequency of the nozzle 3a before the coarse application roll was changed within a range of 0.010 Hz to 1.000 Hz, and the annealing separator slurry 4 was applied to the surface of the strip 1. Moreover, the time change of the rocking | fluctuation amount of the nozzle 3a before a rough application roll was controlled to the sine wave form. On the other hand, in Comparative Example 2, the annealing separator slurry 4 was applied to the surface of the strip 1 without swinging the nozzle 3a before the rough application roll, as in the prior art. Table 2 shows the inspection results of the defective shape of the band 1 in each of the above Examples 31 to 36 and Comparative Example 2.

  From Table 2, it can be seen that in Examples 31 to 36, the occurrence of the shape defect of the strip 1 (orientated electrical steel sheet) does not occur at all, or is reduced as compared with the prior art. Furthermore, in Examples 31 to 33, when the oscillation frequency of the nozzle 3a before the rough coating roll is close to the turn pitch frequency, that is, the same value as 0.665 Hz or in the vicinity thereof, the shape defect of the strip 1 occurs. You can see that it will not. On the other hand, in Comparative Example 2, it can be seen that the shape defect of the belt-like body 1 occurs.

  In Examples 31 to 36, the change over time of the swing amount of the nozzle 3a before the rough coating roll was controlled in a sine wave shape, but this was a case where the change over time in the swing amount was controlled in a rectangular wave shape or a triangular wave shape. However, no difference was found in the inspection result of the shape defect of the band 1.

  In Examples 31 to 36, the result in the case where the turn pitch frequency is 0.665 Hz is shown. However, even if the turn pitch frequency is a value other than 0.665 Hz, the rough coating roll pre-roller nozzle 3a is swung. By bringing the frequency closer to the turn pitch frequency, the same result as that obtained when the turn pitch frequency was 0.665 Hz was obtained.

  Further, in Examples 31 to 36, the turn pitch frequency was set based on twice the turn pitch as described above, and the oscillation of the nozzle 3a before the rough coating roll was controlled based on this turn pitch frequency. As a result, good results as shown in Table 2 were obtained, but the turn pitch frequency was set based on coating conditions based on such a concept, that is, an even multiple of the turn pitch. The same effect was obtained when the rough coating roll pre-nozzle 3a was swung according to the turn pitch frequency.

  According to the embodiment of the present invention described above, when the annealing separator slurry 4 is applied to the surface of the strip 1 using the slurry supply nozzle 3, the slurry supply nozzle 3 is aligned along the width direction of the strip 1. Even if the film thickness distribution of the annealing separator slurry 4 along the width direction is smoothed or the strip 1 is wound up to form the coil 10, it is built up. Therefore, it is possible to suppress the occurrence of shape defects in the band 1.

  Although one embodiment of the present invention has been specifically described above, the present invention is not limited to the above-described embodiment, and various modifications based on the technical idea of the present invention are possible. For example, the numerical values given in the above-described embodiment are merely examples, and different numerical values may be used as necessary.

  In the above-described embodiment, the pitch T when the slurry supply nozzle 3 is controlled to be sinusoidal or rectangular wave is set to 2 to 120 seconds, or the oscillation frequency of the coating nozzle is set to a predetermined pitch according to the turn pitch of the coil 10. Although the value (for example, 0.665 Hz) is used, the period and frequency may be variable corresponding to the line speed of the strip 1 and the position after winding of the coil 10.

DESCRIPTION OF SYMBOLS 1 Strip body 2 Squeeze roll 2a Coarse application roll 2b Backup roll 2c Application roll 3 Slurry supply nozzle 3a Nozzle before application roll 3b Nozzle before application roll 3c Nozzle after application roll 4 Annealing separator slurry 10 Coil 20, 21, 22, 23 , 100 Slurry coating device

Claims (13)

Slurry with and is configured to be supplied to the steel sheet running, the slurry discharge means which can swing at a pitch of 2 to 120 seconds in a direction perpendicular to the running direction of the steel sheet in parallel to the plane of the steel plate When,
A pair of application means configured to be able to apply the supplied slurry onto the surface of the steel plate , while pressing the steel plate while pressing the steel plate ,
The slurry application device is characterized in that the oscillation frequency of the slurry discharge means is set based on a turn pitch of a coil formed by winding the steel plate . The slurry discharging means is provided on the upstream side along the traveling direction of the steel sheet with respect to the pair of application means, and on the downstream side along the traveling direction of the steel sheet with respect to the pair of application means. The slurry coating apparatus according to claim 1, further comprising a second slurry discharge unit configured to be able to supply slurry to the traveling steel plate . The second slurry discharge means, a slurry coating apparatus according to claim 2, characterized in that it can swing in a direction perpendicular to the running direction of the steel sheet in parallel to the plane of the steel sheet. The slurry discharge means is provided on the downstream side along the traveling direction of the steel sheet with respect to the pair of application means, and on the upstream side along the traveling direction of the steel sheet with respect to the pair of application means. The slurry coating apparatus according to claim 1, further comprising a third slurry discharge unit configured to be able to supply slurry to the traveling steel plate .   The slurry application apparatus according to any one of claims 1 to 4, wherein a temporal change in a swing amount in the swing is a rectangular wave shape, a sine wave shape, or a triangular wave shape. 6. The slurry coating apparatus according to claim 1, wherein each of the slurry coating apparatuses that hold the slurry discharging means is configured to be swingable with respect to the traveling steel plate .   The slurry coating apparatus according to claim 1, wherein the oscillation frequency of the slurry discharge means is set based on an even multiple of the turn pitch. Against traveling steel sheet, a slurry supplying step of supplying a slurry while swinging at a pitch of 2 to 120 seconds in a direction perpendicular to the running direction of the steel sheet in parallel to the plane of the steel sheet,
A slurry application step of applying the slurry to the surface of the steel sheet by pressing while holding the steel sheet supplied with the slurry;
And a swing frequency in the swing is set based on a turn pitch of a coil formed by winding the steel plate . The slurry applying method according to claim 8, further comprising a second slurry supplying step for supplying slurry to the traveling steel plate after the slurry applying step. Claim 9, in the second slurry supplying step, the slurry relative to the steel plate, and supplying while swinging in a direction perpendicular to the running direction of the steel sheet in parallel to the plane of the steel plate The slurry application | coating method of description. Before the slurry supplying step, a third slurry supplying step for supplying slurry to the traveling steel plate , and pressing the slurry while gripping the steel plate supplied with the slurry in the third slurry supplying step. The slurry application method according to claim 8, further comprising a second slurry application step of applying to the surface of the steel plate .   The slurry application method according to any one of claims 8 to 11, wherein the temporal change of the swing amount in the swing is a rectangular wave shape, a sine wave shape, or a triangular wave shape.   The slurry application method according to any one of claims 8 to 12, wherein an oscillation frequency in the oscillation is set based on an even multiple of the turn pitch.

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