JPS63286521A - Method for coating annealing and separating agent to grain oriented silicon steel sheet - Google Patents

Abstract

PURPOSE:To coat an annealing and separating agent uniformly on a grain oriented silicon steel sheet in the transverse direction with good operability and workability by coating the annealing and separating agent in the form of slurry on the steel sheet, then injecting gaseous fluid from slit nozzles to the steel sheet from a diagonal direction. CONSTITUTION:The grain oriented silicon steel sheet 2 which is subjected to cold rolling and decarburization annealing is run in an arrow direction. The annealing and separating agent essentially consisting of MgO is coated in the form of slurry by sprays 1 onto this steel sheet 2. Air, N2 or the like is then ejected from the slit nozzles 3 having headers to the steel sheet 2 at, for example, about >=45 deg. inclination in the progressing direction of the steel sheet on the down stream of the above-mentioned sprays. The distance between the discharge ports of the nozzles 3 and the steel sheet 2 is preferably within about 30mm and the gaseous pressure of the headers of the nozzles 3 about 0.05-0.50kg/cm<2>. The coating weight of the annealing and separating agent is thereby adjusted and is uniformized in the transverse direction of the sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for applying an annealing separator to grain-oriented silicon steel sheets.

[Conventional technology]

In addition to having excellent magnetic properties, it is important that grain-oriented silicon steel sheets have a good forsterite coating.

Generally, a grain-oriented silicon steel plate is produced by heating a grain-oriented silicon steel plate slab to, for example, 1,300 to 1,400°C, and then adding component molecules i1 to form an inhibitor. Annealing is performed to completely dissolve Mn, S, N, etc. into a solid solution and to finely precipitate the inhibitor on the hot-rolled sheet or intermediate sheet before final cold rolling. After two or more cold rollings, the removal of C, the formation of next crystals, and the oxide layer containing SiO2,
After applying an annealing separator mainly composed of MgO to the steel sheet, a so-called decarburization annealing is performed to form a finish for the purpose of developing secondary recrystallization, removing impurities, and forming a forsterite film. Annealing is performed.

By the way, the annealing separator is made into a slurry and is sprayed onto the steel plate with a spray nozzle, as shown in Japanese Patent Laid-Open Publication No. 61-96081, and then the application area weight is adjusted using a roll with an adjusted rolling blade. quantity was controlled. Furthermore, in order to adjust the coating weight, the roll grooves of the roll coater have also been changed.

[Problem that the invention seeks to solve]

In these conventional means, the roll surface deteriorates over time, and the degree of deterioration may vary in the roll axis direction, which tends to cause variations in the coating amount in the width direction of the steel sheet.

In addition, MgO, which is an annealing separator, sticks locally, for example, to the roll surface, and a so-called double track occurs in which the annealing separator is applied thinner only to the steel sheet surface that contacts that location than to other surfaces. When these coating variations in the width direction of the plate occur, they cause variations in the forsterite film formed in the final finish annealing, which is a post-process, not only impairing commercial value but also causing variations in magnetic properties.

The purpose of the present invention is to apply an annealing separator mainly composed of MgO in the form of a slurry to a grain-oriented silicon steel sheet, and to apply it at a uniform basis weight across the width of the steel sheet.
Another object of the present invention is to provide a method for applying an annealing separator that does not cause coating unevenness called double track and does not cause coating defects due to aging.

[Means for solving problems]

The gist of this method is to apply an annealing separator in the form of a slurry to a grain-oriented silicon steel sheet that has been cold rolled and decarburized annealed, and then inject a gas fluid from a slit nozzle onto the steel sheet from an oblique direction to adjust the coating weight. A method for applying an annealing separator to a grain-oriented silicon steel sheet is provided.

The present invention will be explained in detail below. Grain-oriented silicon steel sheets are prepared by hot rolling a slab, winding it up as a coil, pickling and annealing, and then cold rolling once or twice or more with an intermediate annealing in between, followed by decarburization, subsequent crystal formation, and 5iOz. So-called decarburization annealing is performed to form an oxidized layer. Then MgO
A slurry of an annealing separator mainly composed of
The coating weight of the annealing separator is controlled by making the annealing separator inclined with respect to the traveling direction of the steel plate 2, for example, and ejecting the annealing separator while ensuring an angle of 45 degrees or more with respect to the steel plate 2. Further, as shown in Fig. 2, a slurry of annealing separator is applied to the steel plate 2 using a spray 1, and then passed between rolls 4, and then a gas fluid is injected from a slit nozzle 3 onto the steel plate 2 from an oblique direction to apply the slurry. The distance between the steel plate and the slit nozzle discharge port when ejecting gas fluid from the slit nozzle 3 is 30 m.
The pressure of the header of the slit nozzle 3 is preferably 0.05 to 0.50 kg/c depending on the sheet passing speed.
m2 is preferred.

In this way, by ejecting the gas fluid obliquely onto the steel plate from the slit nozzle, the coating weight of the annealing separator is controlled, and the coating weight is uniformly applied over the entire width of the steel plate without variation. As a result, the forsterite film formed by final annealing is good and has excellent magnetic properties. In addition, annealing separators such as MgO are
Since the hydration reaction M[O+H20→Mg(OH)z of gO progresses more easily as the temperature is higher, it is preferable to use a low-temperature gas that has been passed through a cooling device.

After adjusting the coating amount, the grain-oriented silicon steel plate is heated to, for example, about 200° C. in a drying oven to remove adhering moisture from the slurry-like annealing separator on the steel plate.

Next, the steel plate is made into a coil shape and subjected to long-term high-temperature annealing in a finish annealing furnace by a known method. Secondary recrystallization occurs during the annealing process, and oxidation containing SiO□ generated during the decarburization process occurs. The layer and the annealing separator mainly composed of MgO react to form a forsterite film and remove impurities.

[For production]

The thickness distribution of the forsterite coating in the width direction of the product plate after annealing is shown in FIGS. 3 and 4 for the conventional method and the present invention. As is clear from the comparison between Figures 3 and 4, controlling the coating amount by gas spraying according to the present invention not only reduces the variation in the forsterite film, but also reduces the variation in the coating amount. Since all that is needed is to adjust the , the operability and workability have also been significantly improved compared to the conventional method.

Next, examples will be described.

〔Example〕

Si3.2%, S 0.02%, Mn 0.07%
A slab containing IO, 028%, NO, 009% was hot rolled to a thickness of 31IIm, hot rolled plate annealed at 1120°C for 3 minutes, and then cold rolled to a final thickness of 0.3m+.
It was set as n. Next, at 850℃ for 3 minutes, dew point 40℃, H250
After continuous decarburization annealing in an atmosphere consisting of . For a coating weight of 17 m, the distance between the gas discharge port and the steel plate was 20 mm, and the angle of gas spraying was 60° with respect to the direction of movement of the steel plate. The slit width of the discharge port was 2 mm, and the header pressure was 0.1 kg/am''.

Next, the steel plate coated with the annealing separator was heated in a drying oven until the temperature of the steel plate reached 200°C to remove the attached moisture, and the weight of the solid material after moisture removal was wound into a coil.
2 (one side). Next, it is charged into a finishing annealing furnace, and 11
It was annealed at 00°C for 40 hours. The properties of the grain-oriented silicon steel sheet after annealing were investigated, and the results shown in Table 1 were obtained.

〔Effect of the invention〕

As described above, according to the present invention, the annealing separator can be uniformly applied to the grain-oriented silicon steel sheet without any variation. For this reason, the forsterite film formed by subsequent finishing annealing also becomes good, and the magnetic properties also become good.

[Brief explanation of drawings]

FIG. 1 is a diagram showing one embodiment of the present invention, FIG. 2 is a diagram showing another embodiment of the present invention, and FIG. 3 is a diagram showing the forsterite film thickness distribution in the board width direction depending on the affected area. FIG. 4 is a diagram showing the forsterite film thickness distribution in the board width direction according to this test. 1...Spray, 2...Steel plate, 3...Slit nozzle, 4...Roll.

Claims (1)

[Claims] 1. After applying an annealing separator in the form of a slurry to a grain-oriented silicon steel sheet that has been cold rolled and decarburized and annealed, a gas fluid is injected from a slit nozzle onto the steel sheet from an oblique direction to adjust the applied area weight. A method for applying an annealing separator to a grain-oriented silicon steel sheet.