JPH05239664A - Coating equipment for superfinely and uniformly coating separation agent for annealing - Google Patents

Abstract

PURPOSE:To finely and uniformly coat the surface of a steel sheet with slurry by providing charging-coating paths for a separation agent for annealing with superfinely pulverizing machines, cracking MgO and an additive in the slurry and executing activating treatment. CONSTITUTION:Superfinely pulverizing machines are set on one or >=two places among A: the space among MgO as a raw material, charging equipment and a stirring tank 1, B: the space between the stirring tank 1 and a circulating tank 2, C: the space between the circulating tank 2 and a coating roll 3, D: the space between a coating roll 3 and the circulating tank 2, E: the surface of the by-pass circuit of the stirring tank 1 and F: the surface of the by-pass circuit of the circulating tank 2. The flocculated bodies of MgO and an additive in slurry are cracked by the superfinely pulverizing machines, and, the surface of the grains is activated. In this way, the glass film of the slurry of the separation agent for annealing can be formed on the surface of a grain-oriented silicon steel sheet with tight adhesion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to coating equipment for applying a slurry, which is an annealing separator for grain-oriented electrical steel sheets, to the surface of the steel sheet in an ultrafine and uniform manner.

[0002]

2. Description of the Related Art Generally, grain-oriented electrical steel sheets are hot rolled from a material containing Si 4.5% or less and annealed once or cold rolled twice or more with intermediate annealing to obtain a final thickness. , Then N ₂ + H ₂ or PH ₂ O / PH in a wet atmosphere of H _2
2 to control decarburization annealing, decarburization and SiO ₂
An oxide film mainly composed of is formed.

Thereafter, an annealing separating agent containing MgO as a main component is suspended in water, and is applied as a slurry by a coating roll or the like. After drying, final annealing is performed to carry out secondary recrystallization, purification, and glass film formation. .. If necessary, an insulating coating agent is coated, baking and heat flattening are performed, and the final product is obtained.

The annealing separator in this manufacturing process is MgO.
TiO as a simple substance or as a glass film forming reaction accelerator
₂ , oxides such as MnO ₂ and V ₂ O ₅ , H ₃ BO ₃ and Na
₂ B ₄ O ₇ , CaB ₄ O ₇ , borate such as B ₂ O ₃ , boron compound, SrSO ₄ , Sb ₂ (SO ₄ ) ₃ , SrS
A certain amount of a sulfate or sulfide of MgO, etc. is added to MgO, and it is applied as a slurry suspended in water to a steel plate by a method such as a coating roll or spray.

The annealing separator applied in this manner reacts with the SiO ₂ -based oxide film formed by decarburization annealing to form a forsterite-based film usually called a glass film (2MgO + SiO ₂ → Mg _2). SiO ₄ ). In forming this glass film, in addition to the conditions for forming the oxide film formed by decarburization annealing and finish annealing conditions, the components of the annealing separator, the properties, and the coating state of the annealing separator on the steel sheet have an important influence. .. That is, the particle size, dispersion state, adhesiveness, etc. of MgO particles, additives, etc. on the steel plate surface have a great influence on the timing of forming the glass film with the underlying oxide film, the reaction rate, the amount of formation, etc. in the finish annealing. Of.

As a method for adjusting this annealing separator slurry, generally, a dispersion treatment is carried out by automatically stirring in a stirring device provided with a rotating body of propeller type, shear type or the like.
However, MgO, additives, etc. are usually manufactured by firing or drying a crystalline material as a raw material at a high temperature. For this reason,
Sintering of particles may occur during the manufacturing process, or agglomeration may occur during the process of manufacturing and use.

In particular, during the process of preparing the annealing separator slurry, MgO, additives and the like are remarkably aggregated, and when applied to a steel sheet, they are deposited as coarse particles of several μm to several tens of μm. As a result, the coating film becomes non-uniform and the adhesiveness deteriorates, resulting in a great adverse effect on the glass film forming reaction with the underlying SiO ₂ layer.

Further, in the process of forming the glass film, depending on the time and state of formation of the glass film,
There is a great adverse effect on the inhibitor due to additional oxidation to the steel sheet during the temperature rising process of finish annealing, penetration of [N] in the atmosphere gas, and conversely decrease of N and S, which are inhibitors in the steel. Will bring. For this reason, it is important to apply the annealing separator to the steel sheet finely, uniformly, and with good adhesiveness not only for obtaining the coating characteristics but also for the good magnetic characteristics, and various improving means have been conventionally proposed. ..

For example, Japanese Patent Laid-Open No. 62-156226 has been proposed by the present inventors as a method for activating MgO particles. In this method, a hydrated layer is formed only in the MgO re-surface layer obtained by high temperature firing in the MgO production stage, and the uniformity of the glass coating is improved, and the effect of improving magnetic properties is obtained.

In Japanese Patent Publication No. 2-267278, the calcined MgO is treated in a steam-containing layer at 100 ° C. or higher, and an OH chemisorption layer is formed on the MgO surface as H ₂ O conversion.
Form 0.8-2.5% based on weight. As a result, a grain-oriented electrical steel sheet having a uniform glass coating and excellent magnetic properties can be obtained.

These techniques are used as a solution to the problem of agglomeration of MgO particles in the annealing separator slurry after firing MgO.
By subjecting the re-surface of the particles to a special surface treatment, the particles are modified to lower the surface energy and improve the compatibility with water. However, in these conventional techniques, although the cohesiveness is improved, it is still insufficient, and since it is not possible to control the uniform dispersion condition of the additive,
Furthermore, the development of new technology was desired.

[0012]

In the present invention, when the annealing separator is applied to the grain-oriented electrical steel sheet, MgO and a sintered body, an aggregate, or an aggregate formed during the production of the additive and an aggregate formed during the slurry preparation are used. It is an object of the present invention to provide a new adjusting equipment for an annealing separator as a solution for unevenness of an annealing separator coating and poor adhesion. This equipment also suppresses the hydration reaction that progresses during the crushing treatment of the sintered body and the agglomerate, and enables fine dispersion.

[0013]

[Means for Solving the Problems] As a method for preparing an annealing separator slurry, conventionally, a stirring tank provided with a propeller-shaped or shear-shaped rotating body as described above is used. However, in order to disperse the particles in the slurry by these, high speed and long time stirring is required. In such a case, not only sufficient dispersion of particles cannot be obtained, but also particles or a stirring device The temperature of the slurry rises due to the contact friction between the particles and the particles, and the hydrated water content becomes excessive, resulting in film defects and magnetic deterioration.

As a method for solving these problems, a huge amount of experiments and a method for surely smashing the sintered body and the agglomerate of the annealing separator without a problem such as an increase in hydrated water content by a slurry treatment for a short time Considered by research. As a result, as a method for applying an annealing separator that can solve the above problems, a coating facility equipped with an ultrafine pulverizer can be used for ultrafine,
We devised an equipment that can obtain a coating state that is uniform and has good adhesion.

That is, the gist of the present invention is that a raw material charging tank for cold rolling an grain-oriented electrical steel sheet to a final thickness and applying an annealing separator after decarburization annealing before performing finish annealing. In a coating facility including a stirring tank, a circulation tank, and a coating roll, when applying the annealing separator, a slurry in which an annealing separator having MgO as a main component is suspended in water is used as a raw material MgO and water charging facility. ~ Coating roll 3 paths (A), (B), (C),
(D) or an agitation tank (E) or a circulation tank bypass circuit (F) at one place or at two or more places provided with an ultrafine pulverizer, for crushing aggregates of MgO and additives in the slurry This is a coating facility for applying ultrafine and uniform annealing separating agent, which is characterized in that it is applied to a steel strip after activation treatment.

The present invention will be described below in detail based on embodiments with reference to the drawings. FIG. 1 is a diagram showing the entire coating equipment. The annealing separator and water are mixed in the stirring tank 1 and mixed. After that, while circulating the liquid between the circulation tank 2 and the coating roll 3, the steel plate is continuously applied. At this time, in FIG. 1, between the equipment for feeding the raw material MgO and water and the stirring tank 1 (A), between the stirring tank 1 and the circulation tank 2 (B), between the circulation tank 2 and the coating roll 3. (C), coating roll 3
The ultrafine pulverizer is provided at any one location or two or more locations (D) between the circulation tank 2 and the circulation tank 2, (E) on the bypass circuit of the stirring tank 1, and (F) on the bypass circuit of the circulation tank 2. It is installed. In this equipment, the circulation tank 2 is not essential and may be directly supplied from the stirring tank 1 to the coating roll 3.

As shown in FIG. 2, the ultrafine grain pulverizer is provided with an upper grindstone 5 and a lower grindstone 6 for a rotating body. The slurry is supplied from a hopper 4 and the slurry is discharged from the ultrafine grain crusher through an outlet 7. .. At this time, the rotating body grindstone is not limited to two, and three or more grindstones may be combined. Also, such a grindstone may be circulated in such a device or used by connecting a plurality of devices. Is also good.

The rotary grindstone is shown in FIG.
As shown in (c), the grindstone surface is provided with dot-shaped, linear-shaped, mesh-shaped projections, or a combination of these shapes. The grinding conditions are determined by the clearance of the grindstone, the slurry concentration, the processing speed, etc. in addition to the manufacturing conditions of the annealing separator. That is, when there are many sintered bodies during the production of MgO or the like, or when the cohesiveness during slurry preparation is strong, measures are taken such as making the surface projections of the grinding wheel fine projections or reducing the distance between the grinding wheels. In addition, the processing speed and the number of times of processing of the slurry processed by the ultrafine pulverizer are controlled.

When the annealing separator is applied in this equipment, Mg
The physical property values of MgO itself, which are brought about by the manufacturing conditions of O,
Depending on the amount, type, etc. of the additive, the hydration reaction may proceed in the same manner as in the case of performing ordinary stirring. For this reason, it is desirable that the number of crushing processes by the ultrafine particle crushing process is desirably suppressed to about 10 times or less in any of (A) to (F) shown in FIG.

Further, in the pulverization process, the agitation tanks provided with the ordinary propeller-shaped and shear-shaped rotating bodies used in the agitation tank 1 and the circulation tank 2 are used together. preferable. In fact, what has been crushed by the present ultrafine pulverizer can be applied finely and uniformly without re-aggregation even after a normal stirring for a long time.

[0021]

【Example】

(Example 1) C: 0.070 and Si: 3.2 by weight ratio
0, Mn: 0.060, S: 0.025, Al: 0.0
30, N: 0.0078, the balance being a high magnetic flux density grain-oriented electrical steel sheet material consisting of Fe and inevitable impurities was hot-rolled by a known method and cold-rolled to a final sheet thickness of 0.29 mm. On this steel sheet, 100 parts by weight of MgO: 5 parts by weight of TiO ₂ ,
An annealing separator composed of 0.5 part by weight of Na ₂ B ₄ O ₇ was added under the conditions shown in Table 1.

[0022]

[Table 1]

(1): The slurry was applied while being circulated between the stirring tank 1 and the coating roll 3 shown in FIG. 1 and dried, and (2): after stirring in the stirring tank 1 shown in FIG. The slurry finely crushed with the ultrafine crushing device (grinding stone shape: (b) in FIG. 3) installed in B) was circulated between the circulation tank 2 and the coating roll 3 under the condition that the distance between the grinding stones was 30 μm, and the slurry was dried. Make two kinds of coils with things, 1200
Final finishing annealing was performed at ℃ × 20hr. The particle size of the slurry in this experiment, the coating state on the steel plate,
Table 2 shows the formation status and magnetic properties of the glass coating of the finished product after the final finish annealing.

[0024]

[Table 2]

As a result, according to the present invention, the particle size in the slurry was fine, and the slurry was applied finely, uniformly and with good adhesion. Further, the glass film after finish annealing was uniformly formed as a good glass film and had good magnetic properties.
On the other hand, in the comparative example, the particle size in the slurry was extremely coarse due to the sintered body or the agglomerate, the appearance after coating the steel sheet was non-uniform, the surface was rough, and the adhesion was very poor. Further, the glass film after finish annealing was nonuniform and thin, and gas mark-like unevenness was generated. Further, the magnetic properties were also considerably worse than those of the present invention.

[0026]

As described above, when the annealing separating agent slurry is adjusted by the coating equipment of the present invention provided with the ultrafine particle pulverizing apparatus, the sintered compacts and agglomerates produced during the manufacturing of the annealing separating agent become ultrafine and uniform. It is disintegrated and the particle surface is activated. Further, the additives to be added are also uniformly and ultra finely dispersed on the MgO surface or the steel plate surface. For this reason, a coating film can be formed on the surface of the grain-oriented electrical steel sheet with good adhesion, and as a result, a good quality glass film is formed during finish annealing, and good magnetic properties are obtained.

[Brief description of drawings]

FIG. 1 is a schematic view of equipment for preparing and coating an annealing separator slurry of the present invention.

FIG. 2 is a schematic view showing an example of an ultrafine particle crushing device of the present invention.

FIG. 3 is a diagram showing an example of a surface shape of a rotary grindstone used as a crusher.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Osamu Tanaka, No. 1 Tobata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka Prefecture (72) Inside the Yawata Works (72) Inventor, Yukio Mizoda Tobata-cho, Tobata-ku, Kitakyushu, Fukuoka No. 1 No. 1 New Steel Works, Yawata Works

Claims (4)

[Claims] 1. A grain-oriented electrical steel sheet is cold-rolled to a final thickness, and a decarburizing-annealing annealing separator is applied by using a coating facility including a raw material charging tank, a stirring tank 1, a circulation tank 2 and a coating roll 3. In a process for producing a grain-oriented electrical steel sheet, which comprises performing a finish annealing by means of a final annealing, a slurry obtained by suspending an annealing separator having MgO as a main component in water is used as a raw material MgO and water when applying the annealing separator. Input equipment ~
Coating roll 3 paths (A), (B), (C),
(D) or a bypass circuit (E) of a stirring tank or a bypass circuit (F) of a circulation tank, using an ultrafine pulverizer provided at one or more places, for crushing aggregates of MgO and additives in the slurry Coating equipment for ultra-fine and uniform application of an annealing separator, which is characterized by applying it to a steel strip after activation. 2. The coating facility according to claim 1, wherein the ultrafine pulverizer has a structure in which two or more grinder-shaped rotating body grindstones are provided. 3. The coating equipment according to claim 2, wherein the rotary grindstone is provided with ridges of a dot shape, a line shape, a mesh shape, or a combination thereof. 4. The stirring of the slurry before or after the crushing and activation treatment with an ultrafine pulverizer is carried out together with a stirring device provided with a propeller-shaped, shear-shaped rotator or the like. The coating facility according to claim 1.