JP7148360B2 - Method for producing grain-oriented electrical steel sheet and continuous film-forming apparatus - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a grain-oriented electrical steel sheet and a continuous film-forming apparatus.

A grain-oriented electrical steel sheet is a soft magnetic material used as a core material for transformers, generators, and the like. A grain-oriented electrical steel sheet is characterized by having a crystal structure in which the <001> orientation, which is the axis of easy magnetization of iron, is highly aligned in the rolling direction of the steel sheet. Such a texture is formed through finish annealing in the manufacturing process of the grain-oriented electrical steel sheet, in which crystal grains of {110}<001> orientation, so-called Goss orientation, are preferentially grown to a large size.
High magnetic flux density and low core loss are required for the magnetic properties of grain oriented electrical steel sheet products. Especially in recent years, from the viewpoint of energy saving, materials with low iron loss have been desired.

As a method to achieve low iron loss, "higher orientation" to increase the degree of accumulation of {110}<001> orientation in the rolling direction, "surface smoothing" to make the surface look like a mirror surface, local strain or steel plate surface "Magnetic domain refining" by processing, "High Si" to increase electrical resistance, "Thinning" to suppress eddy current, "High tension coating" to apply tensile stress in the rolling direction to the steel plate, etc. technology.
A lot of research has been done on these technologies individually, and each of them is already reaching a very high level.

Here, "increasing the tensile strength of the coating" is a technique that makes use of the difference in mechanical properties between the steel sheet and the coating to apply tensile stress to the steel sheet in the rolling direction due to the coating.
In many cases, a coating having a coefficient of thermal expansion different from that of a steel plate is formed at a high temperature and then cooled to room temperature. At that time, since the steel sheet shrinks as it cools, the shape of the coating does not change so much, so a tensile stress can be applied to the steel sheet.
Therefore, in general, a coating having a coefficient of thermal expansion significantly different from that of a steel plate can apply greater tension to the steel plate.

On the other hand, the difference in coefficient of thermal expansion also affects the peeling resistance (adhesion) between the steel sheet and the coating.
Ordinarily, in a grain-oriented electrical steel sheet, irregularities are formed at the interface between the steel sheet and the forsterite coating formed thereon, and the anchor effect ensures the peeling resistance (adhesion) of the upper high-strength coating. ing.
However, irregularities at the interface between the steel sheet and the forsterite coating may hinder movement of the domain wall, increasing iron loss. Therefore, if such a high-strength coating can be formed on a smoothed steel sheet having no forsterite coating without the problem of coating peeling, a further improvement in iron loss can be expected.

Therefore, conventionally, a method for forming a high-strength coating having high peel resistance has been studied. For example, a PVD (Physical Vapor Deposition) method for forming a ceramic film such as TiN, TiC, Ti (CN) by physical means; a CVD (Chemical Vapor Deposition) method for forming a film by chemical means; is mentioned.
These film-forming methods generally require a reduced pressure condition and a reaction gas must be uniformly supplied to the steel sheet. Therefore, when these film forming methods are used, they are often formed in a batch system. However, batch-type film formation results in higher film formation costs and lower productivity.
Therefore, conventionally, continuous film forming apparatuses for continuously forming films using these film forming methods have been proposed (for example, Patent Documents 1 to 3).

JP-A-62-040368 Japanese Patent Application Laid-Open No. 2005-089810 JP 2006-257533 A

The inventors of the present invention investigated the continuous film forming apparatuses described in Patent Documents 1 to 3, and found that the film adhesion of the obtained grain-oriented electrical steel sheet was sometimes insufficient.

The present invention has been made in view of the above points, and an object of the present invention is to provide a method for producing a grain-oriented electrical steel sheet that can obtain a grain-oriented electrical steel sheet with excellent film adhesion.
Another object of the present invention is to provide a continuous film forming apparatus used in the above manufacturing method.

As a result of intensive studies, the inventors of the present invention have found that the above object can be achieved by adopting the following configuration, and completed the present invention.

That is, the present invention provides the following [1] to [13].
[1] A method for manufacturing a grain-oriented electrical steel sheet, wherein a steel sheet that is a grain-oriented electrical steel sheet without a forsterite coating is continuously subjected to film-forming treatment, wherein the steel sheet is subjected to the film-forming treatment. , heating to a film-forming temperature of 300 ° C. or higher, and after the film-forming process, the steel sheet subjected to the film-forming process is cooled by bringing it into contact with a roll, and the cooling rate at the time of contact with the roll is 200 ° C. /s or less.
[2] The method for producing a grain-oriented electrical steel sheet according to [1] above, wherein the cooling rate during contact with the rolls is 100° C./s or less.
[3] The method for producing a grain-oriented electrical steel sheet according to [1] or [2] above, wherein the film-forming treatment is performed by a CVD method or a PVD method.
[4] The method for producing a grain-oriented electrical steel sheet according to any one of [1] to [3], wherein the film-forming treatment is performed under reduced pressure conditions.
[5] The method for producing a grain-oriented electrical steel sheet according to any one of [1] to [4] above, wherein the diameter of the roll is 200 mm or more.
[6] Manufacture of the grain-oriented electrical steel sheet according to any one of [1] to [5] above, wherein the temperature of the rolls is changed during the cooling to adjust the cooling rate during contact with the rolls. Method.
[7] A film forming chamber in which a transported film forming material is heated to a film forming temperature of 300° C. or higher to continuously perform film forming processing on the film forming material, and a downstream side of the film forming chamber. and a roll for cooling the film-forming material, which has been subjected to the film-forming process, by contact, and the cooling rate at the time of contact with the roll is set to 200° C./s or less.
[8] The continuous film forming apparatus according to [7] above, wherein the cooling rate during contact with the roll is 100° C./s or less.
[9] The continuous film-forming apparatus according to [7] or [8] above, wherein the film-forming process is performed by CVD or PVD in the film-forming chamber.
[10] The continuous film forming apparatus according to any one of [7] to [9] above, comprising a roll temperature changing mechanism for changing the temperature of the roll.
[11] Provided with a temperature measuring device for measuring the temperature of the film-forming material subjected to the film-forming process, and driving the roll temperature changing mechanism based on the temperature measured by the temperature measuring device, The continuous film forming apparatus according to any one of [7] to [10] above, wherein the cooling rate during contact with the roll is adjusted by changing the temperature of the roll.
[12] The continuous film forming apparatus according to any one of [7] to [11] above, wherein the diameter of the roll is 200 mm or more.
[13] The continuous deposition apparatus according to any one of [7] to [12], wherein the material to be deposited is a grain-oriented electrical steel sheet having no forsterite coating.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the grain-oriented electrical steel sheet which can obtain the grain-oriented electrical steel sheet excellent in film adhesion can be provided.
Furthermore, according to the present invention, it is possible to provide a continuous film forming apparatus used in the above manufacturing method.

It is a schematic diagram which shows a continuous film-forming apparatus.

[Findings of the present inventors]
In a continuous film-forming apparatus, a grain-oriented electrical steel sheet (steel sheet) having no forsterite coating is continuously subjected to film-forming treatment at a high film-forming temperature under reduced pressure conditions.
After that, the steel sheet that has undergone the film forming process is cooled. At this time, gas and the like are thin around the steel plate under reduced pressure conditions. Therefore, cooling by radiation from the steel sheet itself, cooling by contact with rolls installed inside the continuous film forming apparatus, and the like play a major role.
Cooling by rolls plays a particularly large role because it is actually performed in contact with the steel sheet. Cooling by contact with the roll is affected by the temperature difference between the roll and the steel sheet, the contact time between the roll and the steel sheet, and the like.
The inventors of the present invention performed the film formation process a plurality of times, and sorted out the rate of occurrence of peeling failure of the film. As a result, it was found that the rate of occurrence of poor peeling of the coating was high, especially at the initial stage of threading.
If the cooling rate is excessively fast, the stress generated between the steel sheet and the coating is abruptly generated, which is thought to cause poor peeling of the coating. Probably, at the beginning of strip threading, the temperature of the rolls in contact with the steel sheet after the coating process is low, and the temperature difference between the rolls and the steel sheet is large. , and there is a possibility that peeling failure occurred.
On the other hand, as sheet threading progresses, the roll is given heat from the steel sheet, and the temperature gradually rises until it reaches equilibrium with the amount of heat released by the roll itself. As the temperature of the roll increases, the temperature difference between the steel sheet and the roll becomes smaller, so the temperature change when the steel sheet and the roll come into contact becomes smaller.

The present inventors conducted tests based on the above considerations. The test results are shown in Table 1 below.
Specifically, a film-forming treatment was performed using a PVD method (ion plating method) on a test piece of a grain-oriented electrical steel sheet (steel sheet) having a surface roughness Ra of 0.2 μm or less and not having a forsterite coating. , a TiN coating was formed. The temperature of the steel sheet (film formation temperature) during the film formation process was set to 300° C. or higher.
After the film-forming process, the steel sheet heated to the film-forming temperature was pressed along the rolls and brought into contact with them, and cooled. Prior to cooling, the temperature of the roll itself (in degrees Celsius) was changed by cooling and/or heating the roll. Three types of rolls with different diameters (unit: mm) were used. The temperature of the steel sheet before and after contact with the roll and the contact time between the roll and the steel sheet were measured. All contact times were 1 second. Based on the measurement results, the cooling rate (unit: °C/s) during contact with the roll was determined.
After that, the steel sheet was allowed to cool to room temperature, and the presence or absence of peeling of the TiN coating was checked. 100 test pieces (30 mm×300 mm) were observed for each condition, and if peeling of the TiN coating was observed even partially on each test piece, it was determined that there was peeling. The number of test pieces with peeling among 100 sheets was taken as the peeling rate (unit: %). When the peeling rate was 2% or less, the film adhesion was evaluated as being excellent.

From the results of the above test, when the cooling rate at the time of roll contact (hereinafter also simply referred to as "cooling rate") is 200 ° C./s or less, the peeling rate is 2% or less, indicating that the film adhesion is excellent. Found it.
In particular, when the cooling rate during contact with the roll is 100° C./s or less, the peeling rate is 0% and the film adhesion is more excellent.

The diameter of the roll used for cooling was also found to affect coating adhesion.
See, for example, test results with a roll temperature of 50°C. The release rate for a roll diameter of 200 mm was 0%, which was better than the release rate for roll diameters of 100 mm or 250 mm.
The reason why the roll diameter affects the film adhesion is presumed as follows. That is, when the steel plate is bent so as to follow the roll, compressive stress is applied to the film and steel plate on the inner side where the steel plate and the roll are in contact, and tensile stress is applied on the outer side. Such a tendency becomes more pronounced as the roll diameter becomes smaller, and is moderated as the roll diameter becomes larger. For this reason, when the roll diameter is 200 mm or more, it is presumed that the film adhesion is more excellent.

Hereinafter, the present invention will be described again.

[Manufacturing method of grain-oriented electrical steel sheet]
The method for producing a grain-oriented electrical steel sheet of the present invention (hereinafter also simply referred to as the "manufacturing method of the present invention") is a steel sheet that is a grain-oriented electrical steel sheet that does not have a forsterite coating. In the method for manufacturing a grain-oriented electrical steel sheet, the steel sheet is heated to a film-forming temperature of 300° C. or higher when performing the film-forming treatment, and the film-forming treatment is performed after the film-forming treatment. A method for producing a grain-oriented electrical steel sheet, wherein the steel sheet is cooled by bringing it into contact with rolls, and the cooling rate during contact with the rolls is 200° C./s or less.

<Grain-oriented electrical steel sheet without forsterite coating>
A grain-oriented electrical steel sheet after secondary recrystallization annealing, which is usually called finish annealing, has a forsterite coating. As described above, when the forsterite coating is present, adhesion with the upper high-tensile coating is advantageous due to the anchor effect, but from the viewpoint of magnetic properties, the surface of the steel sheet is preferably smooth. . However, if the forsterite coating is not present, the adhesion to the overlying high-strength coating may be disadvantageous.
The production method of the present invention may be applied to a grain-oriented electrical steel sheet having a forsterite coating, but is particularly applied to a grain-oriented electrical steel sheet having no forsterite coating (hereinafter also simply referred to as "steel sheet"), It is effective in improving adhesion (coating adhesion) when a high-strength coating is formed on a grain-oriented electrical steel sheet that does not have a forsterite coating.
The method for producing a grain-oriented electrical steel sheet without a forsterite coating is not particularly limited, and for example, a method of physically removing the forsterite coating using mechanical polishing or the like and then chemically obtaining a smooth surface. (For example, see Japanese Patent Laid-Open No. 09-118923); A method in which a chloride auxiliary agent is added to an annealing separation agent mainly composed of MgO, and the forsterite coating is peeled off after final annealing (for example, Japanese Patent Laid-Open No. 2002-363763 Japanese Patent Laid-Open No. 08-269560): and the like.
A method that does not form a forsterite coating in the first place by using an annealing separator such as alumina (Al ₂ O ₃ ) may be employed. Multiplying multiple methods is also useful.
The obtained steel sheet preferably has a surface roughness Ra of 0.5 μm or less.

<Preprocessing>
It is preferable to remove impurities such as oxides remaining on the surface of the grain-oriented electrical steel sheet (steel sheet) that does not have the forsterite coating, that is, to perform pretreatment before the film-forming process described later. As a result, the adhesion of the film (for example, nitride film) formed by the film forming process to the steel plate (base iron) is significantly improved.
Ion sputtering is preferred as the pretreatment method. In the case of ion sputtering, it is preferable to use inert gas ions such as argon and nitrogen, or metal ions such as Ti and Cr as ion species.
In order to increase the mean free path of sputtering ions, the pretreatment is also preferably performed under reduced pressure conditions, preferably 0.0001 to 1.0 Pa.
It is preferable to apply a bias voltage of -50 to -1000 V using a steel plate as a cathode. As a pretreatment method, a method using an electron beam is also known.

<Film formation>
In the production method of the present invention, the grain-oriented electrical steel sheet (steel sheet) having no forsterite coating is continuously subjected to film-forming treatment. When performing the film forming process, the steel sheet (more specifically, the surface of the steel sheet) is heated to a film forming temperature of 300° C. or higher.
The steel sheet to be subjected to the film forming process is, for example, a belt-like shape elongated in one direction (rolling direction), and is preferably pulled out from the coil and conveyed.
The film forming process is continuously performed, for example, on the surface of a steel sheet that is passed (conveyed) through a film forming chamber of a continuous film forming apparatus to be described later.
A CVD (Chemical Vapor Deposition) method or a PVD (Physical Vapor Deposition) method is preferably used for the film formation process.
The film forming process is preferably performed under reduced pressure conditions.

A thermal CVD method is preferable as the CVD method. The film formation temperature is preferably 900 to 1100.degree. The pressure during film formation may be atmospheric pressure, but it is preferable to form the film under reduced pressure conditions (including "vacuum conditions") because a more uniform film can be formed.
The pressure under the reduced pressure condition (internal pressure of the film formation chamber) is, for example, 10-1000 Pa. However, since the CVD method is a film forming method in which a reactive gas is supplied to form a film, and the optimum pressure varies depending on the composition of the film to be formed, it cannot be determined uniquely.

The PVD method is preferably an ion plating method. The film formation temperature is preferably 300 to 600° C. because the film formation efficiency can be improved. In the PVD method, since it is necessary to ionize a raw material called a target and reach the steel sheet, it is required to be performed under reduced pressure conditions lower than those in the CVD method. Specifically, for example, 0.1 to 100 Pa is suitable. be.
When the PVD method is used, it is preferable to apply a bias voltage of -10 to -300 V using a steel plate as a cathode because the adhesion of the coating is improved. The deposition rate can be increased by using plasma for ionizing the raw material.

It is preferable that the film formed by the film-forming treatment has a coefficient of thermal expansion different from that of the steel plate (lower coefficient of thermal expansion), and that the deformation that occurs when stress is applied is also smaller than that of the steel plate.
Specifically, the coating is preferably a nitride coating, more preferably a metal nitride coating, Zn, V, Cr, Mn, Fe, Co, Ni, Cu, Ti, Y, Nb, Mo, Hf, Zr. , W and Ta are more preferred. These tend to have a rock-salt structure and are easily matched with the body-centered cubic lattice of the steel plate (base steel), so that the adhesion of the coating can be improved.
The coating is not limited to a coating consisting of a single layer. For example, a coating consisting of a plurality of layers may be provided with functionality.
The film thickness of the coating is, for example, 0.05 to 5.0 μm, preferably 0.10 to 3.0 μm.

By such a film-forming treatment, a grain-oriented electrical steel sheet (a film-coated grain-oriented electrical steel sheet) having a grain-oriented electrical steel sheet without a forsterite coating and a coating formed on the surface thereof by the film-forming treatment is obtained. .

<cooling>
In the manufacturing method of the present invention, after the film-forming process, the steel sheet subjected to the film-forming process is brought into contact with the roll. More specifically, the surface of the steel sheet subjected to the film forming process is brought into contact with the surface of the roll. This cools (the surface of) the steel sheet that has undergone the film forming process.

In this cooling, the cooling rate during contact with the roll is set to 200° C./s or less. Cooling by the rolls may be performed until the temperature (for example, 200° C. or lower) at which there is no problem even if the film formed by the film forming process is exposed to the air. A desired temperature may be obtained by adjusting the contact time of the rolls while controlling the cooling rate at the time of contact with the rolls. After the film reaches a temperature at which there is no problem even if it is exposed to the atmosphere, it may be cooled by switching to normal gas cooling or the like. As a result, a grain-oriented electrical steel sheet having excellent film adhesion can be obtained.
The cooling rate during contact with the roll is preferably 150° C./s or less, more preferably 100° C./s or less, for the reason that the film adhesion is more excellent. When the cooling rate at the time of roll contact is slowed, the contact time between the roll and the steel sheet may be adjusted to lower the steel sheet temperature to the target temperature.
A slow cooling rate during roll contact does not pose a performance problem, and the lower limit of the cooling rate during roll contact is not particularly limited. is preferable, and 50° C./s or more is more preferable.

The diameter of the roll that comes into contact with the steel sheet after the film-forming treatment is, for example, 50 mm or more, preferably 100 mm or more, more preferably 150 mm or more, and still more preferably 200 mm or more for the reason that coating adhesion is superior.
The diameter of the roll is preferably large, and the upper limit is not particularly limited, but from the viewpoint of handling, it is, for example, 500 mm or less, preferably 400 mm or less.

It is preferable that the roll that comes into contact with the steel sheet after the film formation process is provided with a mechanism for changing the temperature of the roll itself (for example, a roll temperature changing mechanism described later). It is preferable to adjust the cooling rate at the time of contact with the roll by using this mechanism to change the temperature of the roll during cooling.

<Other treatments or processes>
An insulating coating may be further formed on the coating formed by the film forming process from the viewpoint of ensuring insulation. The type of insulating coating is not particularly limited, and conventionally known insulating coatings can be formed. As a method for forming an insulating coating, for example, a coating solution containing phosphate-chromic acid-colloidal silica, which is described in Japanese Patent Application Laid-Open No. 50-79442 and Japanese Patent Application Laid-Open No. 48-39338, is used. , a method of coating on a film formed by a film forming process and baking at about 800°C.
Flattening annealing can be used to shape the steel sheet, and flattening annealing can also be performed while baking the insulating coating.

[Continuous deposition equipment]
Next, an example of the continuous film forming apparatus of the present invention, which is preferably used in the manufacturing method of the present invention described above, will be described with reference to FIG.

<Basic configuration>
FIG. 1 is a schematic diagram showing a continuous film forming apparatus 1. As shown in FIG. First, the basic configuration of the continuous film forming apparatus 1 shown in FIG. 1 will be described. In FIG. 1, the film-forming material S is conveyed from left to right. The film-forming material S is, for example, a grain-oriented electrical steel sheet that does not have the above-described forsterite coating. The conveying direction is, for example, the direction along the rolling direction.

The continuous film forming apparatus 1 has a film forming chamber 31 . An exhaust port 33 is provided in the film forming chamber 31 . The internal gas of the film forming chamber 31 is exhausted from the exhaust port 33, and the reduced pressure condition is realized.
The conveyed film-forming material S is passed through the inside of the film-forming chamber 31 . The film-forming chamber 31 continuously performs film-forming processing on the film-forming material S passed through the inside of the film-forming chamber 31 . The film forming process is preferably the film forming process described in the manufacturing method of the present invention, and the CVD method or PVD method is preferably used. In this case, the film-forming chamber 31 is supplied with a source gas (atmosphere gas) for film-forming, such as nitrogen gas or TiCl ₄ gas.

The film-forming material S conveyed inside the film-forming chamber 31 is heated to a predetermined film-forming temperature, and a film such as a nitride film is formed on the surface of the film-forming material S.
As a means for heating the film-forming material S, since the inside of the film-forming chamber 31 is evacuated and the pressure is reduced, a burner or the like cannot necessarily be used. ), electron beam irradiation, laser, infrared rays, and the like, which do not require oxygen, are not particularly limited and may be used as appropriate.

A roll 20 is arranged in the decompression chamber 15 located upstream of the film forming chamber 31 . A roll 40 is arranged in the decompression chamber 35 located downstream of the film forming chamber 31 . Roll 20 and roll 40 are bridle rolls. The rolls 20 and 40 apply tension to the film-forming material S inside the film-forming chamber 31 . The film-forming material S passed through the inside of the film-forming chamber 31 is subjected to the film-forming process while tension is applied in the longitudinal direction.

The roll 20 is arranged in a decompression chamber 15 separated from the film forming chamber 31 by a boundary wall 17 . The roll 40 is arranged in a decompression chamber 35 separated from the film forming chamber 31 by a boundary wall 37 .
Thus, it is preferable that the roll 20 and the roll 40 are separated from the film forming chamber 31 by a boundary wall. As a result, the roll surfaces of the rolls 20 and 40 are not coated with a film by the film forming process, and the rolls are biased to make it difficult to control proper tension, and the film-forming material S may meander. Suppressed.

A temperature sensor 43a and a temperature sensor 43b are arranged upstream and downstream of the roll 40, respectively. The temperature sensor 43 a detects the temperature (surface temperature) of the film-forming material S conveyed on the upstream side of the roll 40 . The temperature sensor 43b detects the temperature (surface temperature) of the film-forming material S conveyed on the downstream side of the roll 40 . Temperature sensor 43 a and temperature sensor 43 b are connected to thermometer 42 . The temperatures detected by the temperature sensors 43 a and 43 b are sent to the thermometer 42 . Thus, the temperature (surface temperature) of the film-forming material S subjected to the film-forming process is measured.
That is, the thermometer 42, the temperature sensor 43a, and the temperature sensor 43b constitute a temperature measuring device that measures the temperature of the film-forming material S on which the film-forming process has been performed.
From the temperature detected by the temperature sensor 43a, the temperature detected by the temperature sensor 43b, the threading speed of the film-forming material S, and the like, the cooling rate of the film-forming material S at the time of contact with the roll 40, which will be described later, is grasped. be done.

The film-forming material S that has been heated in the film-forming chamber 31 and subjected to the film-forming process is cooled by coming into contact with the roll 40 .
The material of the roll 40 is, for example, metal and may be oxidized. The type of metal is not particularly limited, but since a metal with a high thermal conductivity has a high cooling capacity, for example, an alloy (iron-aluminum alloy) in which a high thermal conductivity metal such as aluminum is added to iron is suitable. mentioned.
The roll 40 is provided with a roll temperature changing mechanism 45 that changes the temperature of the roll 40 itself. The roll temperature changing mechanism 45 is, for example, a combination of a mechanism for circulating cooling water inside the roll 40; a heater incorporated in the roll 40;
The roll temperature changing mechanism 45 is connected to the roll temperature control device 44 . Roll temperature control 44 is also connected to thermometer 42 (this connection is not shown).
The roll temperature control device 44 drives the roll temperature changing mechanism 45 (specifically, cooling water The temperature of the roll 40 is changed by controlling the temperature, the temperature of the built-in heater, and the like.
In this way, when the film-forming material S subjected to the film-forming process is cooled using the roll 40, the cooling rate at the time of contact with the roll 40 is adjusted to 200° C./s or less. The preferred range of cooling rate and the like are as described above.

For example, when the roll 40 is at room temperature in the initial stage of sheet threading, the temperature of the roll 40 is increased by heating the built-in heater of the roll 40 . In this way, the cooling rate of the film-forming material S when it contacts the roll 40 is adjusted so as not to become excessively high.
On the other hand, in the latter stage of sheet threading, the temperature of the roll 40 may rise to a temperature where the heat input from the film-forming material S and the heat radiation from the roll 40 are balanced. In this case, by circulating cooling water inside the roll 40, the cooling rate of the film-forming material S when it contacts the roll 40 is controlled.

The preferred range of the diameter of the roll 40 that comes into contact with the film-forming material S after the film-forming process is as described above.

<Other configurations>
Other configurations provided in the continuous film forming apparatus 1 of FIG. 1 will be described.
As shown in FIG. 1, it is preferable to provide a pretreatment chamber 30 for performing the pretreatment described above on the upstream side of the film formation chamber 31 . The pretreatment chamber 30 is provided with an exhaust port 32 to achieve a reduced pressure condition. The pretreatment chamber 30 and the film formation chamber 31 are separated by a partition wall 34 .

When the pretreatment in the pretreatment chamber 30 and the film formation treatment in the film formation chamber 31 are performed under a reduced pressure condition, a differential pressure zone having one or more differential pressure chambers is further provided to reduce the internal pressure in stages. is preferred to be lowered.
At this time, when the continuous film forming apparatus 1 shown in FIG. .

Specifically, in FIG. 1, an entry-side differential pressure zone 10 including three entry-side differential pressure chambers 13 is arranged on the entry side of the decompression chamber 15 . The number of entry-side differential pressure chambers 13 is not limited to three.
Each entrance-side differential pressure chamber 13 has an exhaust port 12 . The exhaust amount from the exhaust port 12 increases stepwise as it approaches the pretreatment chamber 30 and the film forming chamber 31 . As a result, the internal pressure of the entry-side differential pressure chamber 13 forming the entry-side differential pressure zone 10 decreases stepwise as it approaches the pretreatment chamber 30 and the film formation chamber 31 . Thus, the internal pressure of the entry-side differential pressure zone 10 approaches the internal pressures of the pretreatment chamber 30 and the film forming chamber 31 from the atmospheric pressure.

The outlet side differential pressure zone 50 is also similar to the inlet side differential pressure zone 10 . That is, in FIG. 1 , an outlet side differential pressure zone 50 including three outlet side differential pressure chambers 53 is arranged on the outlet side of the decompression chamber 35 . The number of output-side differential pressure chambers 53 is not limited to three.
Each exit-side differential pressure chamber 53 has an exhaust port 52 . The exhaust amount from the exhaust port 52 decreases stepwise as the distance from the pretreatment chamber 30 and the film forming chamber 31 increases. As a result, the internal pressure of the output-side differential pressure chamber 53 forming the output-side differential pressure zone 50 increases stepwise as the distance from the pretreatment chamber 30 and film formation chamber 31 increases. Thus, the internal pressure of the exit-side differential pressure zone 50 approaches the atmospheric pressure from the internal pressures of the pretreatment chamber 30 and the film forming chamber 31 .

The inlet-side differential pressure zone 10 and the outlet-side differential pressure zone 50 have seal rolls 11 and seal rolls 51, respectively, between the respective differential pressure chambers. is not limited to

When the film-forming material is a grain-oriented electrical steel sheet, the grain-oriented electrical steel sheet is held in a coil shape for a long time during the finish annealing. Therefore, the ends of the coil lower portion may be bent or deformed. The deformed end of the film-forming material S may damage the roll 20 or the like during passage. In order to avoid this, it is preferable to provide a shear 5 for cutting off the end of the film-forming material S on the upstream side of the entrance-side differential pressure zone 10 .

EXAMPLES The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the following examples.

<Production of test material>
Using the continuous film-forming apparatus 1 described with reference to FIG. 1, the film-forming material S, which is a grain-oriented electrical steel sheet having no forsterite film, is continuously subjected to the film-forming process in the film-forming chamber 31. , and cooled by contact with rolls 40 .
More specifically, as the film-forming material S, after removing the forsterite coating by buffing, the surface roughness Ra is reduced to less than 0.1 μm by electropolishing using sodium chloride as an electrolyte, and the thickness is 0. A 0.21 mm grain oriented electrical steel sheet was used.
A film forming process was performed by PVD to form a nitride film. More specifically, first, in the pretreatment chamber 30, pretreatment was performed to remove oxides on the surface of the steel sheet with Ar ions accelerated at a bias voltage of -600V. After that, in the film forming chamber 31, a steel plate was used as a cathode, and a film forming process was performed under the conditions of a bias voltage of −100 V and a film forming rate of 1.0 nm/s. The steel sheet temperature (film formation temperature) during film formation was set to 500°C. The film quality and film thickness of the formed nitride film are shown in Table 2 below.
The diameter of the roll 40 used for cooling after film formation was 200 mm or 180 mm. The roll temperature control device 44 is operated to drive the roll temperature changing mechanism 45 based on the temperature of the film-forming material S measured by the thermometer 42 (specifically, the temperature of the cooling water, the temperature of the built-in heater, etc. is controlled) to change the temperature of the roll 40 . As a result, the cooling rate of the film-forming material S at the time of contact with the roll 40, which will be described later, was adjusted.
After finishing film formation in the continuous film forming apparatus 1, the nitride film was coated with a phosphate-based coating liquid, and then baked at 850° C. for 60 seconds to form an insulating film.
Thus, a grain-oriented electrical steel sheet test material consisting of the steel sheet, the nitride coating, and the insulating coating was obtained.

For the obtained test material, the cooling rate (unit: °C/s) at the time of contact with the roll 40 was calculated. The cooling rate at the time of contact with the roll 40 was calculated based on the temperatures detected by the temperature sensors 43a and 43b arranged on the upstream and downstream sides of the roll 40 and the sheet threading speed.
In each test material, a test piece (length in the rolling direction: 280 mm × length in the direction perpendicular to the rolling 30 mm) was cut out.

<evaluation>
For each test material, the coating adhesion was evaluated using the round bar winding method. Specifically, a test piece of each test material (length in the rolling direction: 280 mm × length in the direction perpendicular to rolling: 30 mm) is wound around a round bar with a diameter of 80 mm to generate internal stress in the steel plate and coating. rice field. After that, when it was bent back by 180°, the presence or absence of cracks in the coating and peeling of the coating was visually inspected. The same evaluation was performed while decreasing the diameter of the round bar at intervals of 5 mm, and the minimum diameter (bending peeling diameter) at which cracks and peeling did not occur in the film was visually determined. The smaller the value of the bending peeling diameter, the better the film adhesion. If the bending peeling diameter is 30 mm or less, it can be evaluated that the film adhesion is particularly excellent. The results are shown in Table 2 below. Table 2 below shows the largest value (worst value) among the bending peeling diameters of the 30 test pieces.
Furthermore, iron loss W _17/50 (unit: W/kg) was measured for each test material. The results are shown in Table 2 below.

As shown in Table 2 above, test material No. 1 having a cooling rate of 200° C./s or less during contact with the rolls. 2, 4 to 5, 7 to 8 and 10 to 11 are test material Nos. whose cooling rate exceeds 200°C/s. Compared to Nos. 1, 3, 6 and 9, the value of the bending peeling diameter was smaller and the film adhesion was better.

Test material no. 4 and test material No. 5, which has a cooling rate of 80° C./s when in contact with the roll. 5 is a test material No. 5 having a cooling rate of 160° C./s. 4, the value of the bending peeling diameter was smaller, and the film adhesion was better.
Similarly, test material No. 1, which has the same conditions other than the cooling rate at the time of roll contact. 7 and test material No. 8, the cooling rate at the time of roll contact is 80° C./s. 8 is a test material No. 8 having a cooling rate of 180° C./s. Compared to No. 7, the bending peel diameter value was smaller and the film adhesion was better.
Similarly, test material No. 1, which has the same conditions other than the cooling rate at the time of roll contact. 10 and test material No. 11, the cooling rate at the time of roll contact is 80° C./s. Test material No. 11 has a cooling rate of 180°C/s. Compared to No. 10, the bending peel diameter value was smaller and the film adhesion was better.

Test material No. with the same conditions other than the roll diameter. 2 and test material No. 11, the test material No. 1 with a roll diameter of 200 mm. 11 is a test material No. with a roll diameter of 180 mm. 2, the bending peeling diameter value was smaller and the film adhesion was better.

1: Continuous Film Forming Apparatus 5: Shear 10: Entrance Side Differential Pressure Zone 11: Seal Roll 12: Exhaust Port 13: Entrance Side Differential Pressure Chamber 15: Decompression Chamber 17: Parting Wall 20: Roll 22: Exhaust Port 30: Pretreatment Chamber 31: Film formation chamber 32: Exhaust port 34: Boundary wall 35: Decompression chamber 37: Boundary wall 40: Roll 41: Exhaust port 42: Thermometer (temperature measurement mechanism)
43a: Temperature sensor 44b: Temperature sensor 44: Roll temperature control device 45: Roll temperature change mechanism 50: Delivery side differential pressure zone 51: Seal roll 52: Exhaust port 53: Delivery side differential pressure chamber S: Film deposition material

Claims (12)

A method for manufacturing a grain-oriented electrical steel sheet, comprising continuously subjecting a steel sheet, which is a grain-oriented electrical steel sheet having no forsterite coating, to a film-forming process,
When performing the film-forming treatment, the steel plate is heated to a film-forming temperature of 300 ° C. or higher,
After the film-forming treatment, the steel sheet subjected to the film-forming treatment is cooled by being brought into contact with a roll, and the cooling rate at the time of contact with the roll is set to 180 ° C./s or less ,
A method for producing a grain-oriented electrical steel sheet , wherein the cooling rate during contact with the rolls is adjusted by changing the temperature of the rolls during the cooling . 2. The method for producing a grain-oriented electrical steel sheet according to claim 1, wherein the cooling rate during contact with the rolls is 100[deg.] C./s or less. The method for producing a grain-oriented electrical steel sheet according to claim 1 or 2, wherein the film forming process is performed by a CVD method or a PVD method. The method for producing a grain-oriented electrical steel sheet according to any one of claims 1 to 3, wherein the film forming process is performed under reduced pressure conditions. The method for producing a grain-oriented electrical steel sheet according to any one of claims 1 to 4, wherein the roll has a diameter of 200 mm or more. a film formation chamber for heating a conveyed film formation material to a film formation temperature of 300° C. or higher and continuously performing film formation processing on the film formation material;
a roll that is arranged downstream of the film formation chamber and that cools the film-forming material that has been subjected to the film-forming process by contact;
A continuous film forming apparatus, wherein the cooling rate during contact with the roll is 180° C./s or less. 7. The continuous film forming apparatus according to claim 6 , wherein the cooling rate during contact with the roll is 100[deg.] C./s or less. 8. The continuous film forming apparatus according to claim 6 , wherein said film forming process is performed by CVD or PVD in said film forming chamber. 9. The continuous film forming apparatus according to any one of claims 6 to 8 , comprising a roll temperature changing mechanism for changing the temperature of said roll. A temperature measuring device for measuring the temperature of the film-forming material subjected to the film-forming process,
The continuation according to claim 9 , wherein the cooling rate at the time of contact with the roll is adjusted by driving the roll temperature changing mechanism to change the temperature of the roll based on the temperature measured by the temperature measuring device. Deposition equipment. The continuous film forming apparatus according to any one of claims 6 to 10 , wherein the roll has a diameter of 200 mm or more. The continuous deposition apparatus according to any one of claims 6 to 11 , wherein the material to be deposited is a grain-oriented electrical steel sheet having no forsterite coating.

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