JPH05239694A - Grain-oriented silicon steel sheet for magnetic shield excellent in coating adhesion - Google Patents

Abstract

PURPOSE:To obtain a grain-oriented silicon steel sheet for a magnetic shield good in magnetic shield properties and excellent in coating adhesion by using only forsterite coating having specified thickness on ferrite as the substrate of the surface coating of a grain-oriented silicon steel sheet. CONSTITUTION:In a grain-oriented silicon steel sheet applied with the surface coating of coating material, as the substrate of the coating, only forsterite on ferrite is used with glassy coating obviated, and its thickness is prescribed to 2mum. The forsterite film is formed as a result of finish annealing. In this way, the objective grain-oriented silicon steel sheet for a magnetic shield excellent in coating adhesion without deteriorating its magnetic shielding properties can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grain-oriented silicon steel sheet coated with a paint used for a magnetic shield of a small motor.

[0002]

2. Description of the Related Art Advances in the manufacturing technology of grain-oriented silicon steel sheets have been remarkable, and the magnetic properties of the steel sheets have been remarkably improved. That is,
There has been a great deal of progress in technologies for improving the orientation and grain size of the crystal grains that make up a steel sheet, including the removal of impurities that impair the magnetic properties of the steel sheet. Further, regarding the surface of the steel sheet, iron loss can be improved by applying a vitreous coating that imparts tensile stress in the rolling direction on the forsterite film resulting from finish annealing. It has been disclosed in Japanese Laid-Open Patent Publication No. 54-156199, and it is considered that the grain-oriented silicon steel sheets of recent years are mostly manufactured by using this technique. OA equipment, audio equipment and VT
In a small motor used for R etc., a magnetic shield material is wrapped around the motor to shield the leakage flux.
Conventionally, a normal silicon steel plate has been used for this magnetic shield material. As motors have become smaller and lighter in recent years, performance required for magnetic shield materials includes improved magnetic shield performance and thinner plates, as well as beautiful appearance and corrosion resistance. In order to improve the magnetic shielding performance, it is effective to use grain-oriented silicon steel sheet with excellent magnetic permeability, but to improve the appearance and corrosion resistance, use grain-oriented silicon steel sheet coated with paint. Things have become commonplace.

[0003]

For a small motor having a diameter of about 20 mm, a conventional grain-oriented silicon steel sheet, which has been used conventionally, is coated with a coating material, and there is no problem in coating adhesion. Further miniaturization has progressed 10
For a small motor having a diameter of -15 mm or less, there is a problem that the paint peels off when the magnetic shield material is wound around the motor. It is an object of the present invention to provide a grain-oriented silicon steel sheet for magnetic shield, which solves the above problems without impairing the magnetic shield property.

[0004]

DISCLOSURE OF THE INVENTION The present invention is characterized in that a grain-oriented silicon steel sheet coated with a paint is characterized in that the base of the paint is only a forsterite coating having a thickness of 2 μm or less on the base metal. It is a grain-oriented silicon steel sheet for magnetic shield with excellent adhesion.

[0005]

FIG. 1 is a sectional view of a conventional grain-oriented silicon steel sheet for magnetic shield coated with a paint. Even in the conventional magnetic shield material shown in FIG. 1, the coating adhesion may be improved by coating with paint, and the reason was investigated. As a result, it was found that the forsterite film under the paint had partly exfoliated from the base metal into powder in the case of good paint adhesion, but the paint film prevented the falling from the steel plate. It was On the other hand, if the peeling area of the forsterite coating increases or if it peels widely in the form of a foil, the effect of fixing the peeled forsterite coating to the steel plate surface will decrease, and the paint will peel from the steel plate. Also became clear. In particular, when the forsterite coating is integrally peeled off, peeling of the coating film is more likely to occur even with a slight bending process as compared with the case where the forsterite coating is peeled off. Based on this finding, the influence of the thickness of the forsterite coating and the presence or absence of the vitreous coating on the coating adhesion of Tsuzuki paint was investigated. FIG. 2 shows a method for determining the paint adhesion of paint. That is, as shown in FIG. 2, a target oriented paint is coated with a grain-oriented silicon steel plate, which is wound around a round bar of 10 mmΦ, and then the presence or absence of floating of the paint on the inside is determined when the paint is spread again. The samples used for the investigation were grain-oriented silicon steel sheet (forsterite film formed on the surface) after final finishing annealing with a thickness of 0.23 mm obtained by the ordinary manufacturing method, and a glassy coating with a thickness of 2 μm on the steel sheet. It is a steel sheet that has been applied, and these are coated with a polyester paint to a thickness of 4 μm. The coating adhesion of this test material was judged by the method of FIG. 2, and it was arranged in FIG. 3 regardless of the forsterite coating thickness formed on the surface of the test material and the condition of the presence or absence of glassy coating. is there.

From FIG. 3, in the case of the test material coated only with the forsterite coating without the glassy coating, when the forsterite coating thickness is 2 μm or less, the paint adhesion is 100% even when bent with a diameter of 10 mm. Pass. On the other hand, in the case of the test material coated with vitreous coating, the pass rate reaches 100% when the thickness of the forsterite coating is 1.0 μm, but when the thickness of the forsterite coating is 1.5 μm, failure occurs and the vitreous coating becomes vitreous. It is clear that the coating has a detrimental effect on paint adhesion. Although the iron loss is slightly deteriorated by the method of the present invention, there is no problem in the magnetic permeability, but rather it is improved in the low magnetic field where magnetic shielding properties are required. From the above, when a paint is applied to a grain-oriented silicon steel sheet and used as a magnetic shield material for a small motor, according to the present invention, the vitreous coating is omitted and the forsterite coating thickness is limited to 2 μm or less. A grain-oriented silicon steel sheet for magnetic shielding having excellent coating adhesion can be obtained.

[0007]

Example 1 The coating of a glassy coating on a grain-oriented silicon steel sheet having a thickness of 0.23 mm was omitted, and the film thickness of the forsterite film was 1.5 μm and the film thickness of the forsterite film was 1.5 μm. When a polyester-based paint was applied to the above material in a film thickness of 4 μm and the paint adhesion (bending diameter 10 mm) was tested, it passed 100%. A magnetic shield confirmation test was performed using this test material. The test method is shown in FIG. The sample material 5 was placed between the magnet 6 and the Gauss measuring machine 9, and the Gauss adjustment distance 7 was adjusted to measure the magnetic strength after shielding while changing the measurement distance 8. Gauss adjustment distance 25m
When m, 18 mm, and 15 mm, the magnetic strength before shielding is 100, 150, and 200 gauss, respectively. The test results are shown in FIG. From this graph, it can be seen that the magnetic shield property is equivalent to that of the conventional product.

Example 2 A vitreous coating was prepared by removing the vitreous coating from a portion of a grain-oriented silicon steel sheet having a forsterite coating film thickness of 2 μm and a vitreous coating layer on the forsterite coating film having a thickness of 0.23 mm. Create materials with and without and use 5μ of epoxy paint on both materials.
After painting, the paint adhesion (bending diameter 10 mm) was tested, and the material without glass coating was 100
% Passed, but the material with the glassy coating only passed 35%.

[0009]

Industrial Applicability According to the present invention, the coating adhesion can be remarkably improved by stopping the vitreous coating of the grain-oriented silicon steel sheet and reducing the thickness of the undercoating film on the surface to below the specified value, thereby reducing the size. It can now be used as a magnetic shield material for advanced motors.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a conventional grain-oriented magnetic steel sheet for magnetic shield coated with paint.

FIG. 2 is a view showing a procedure of a 10Φ round bar 180 ° bending adhesion test.

FIG. 3 is a graph showing the relationship between the coating adhesion and the forsterite coating thickness and the presence / absence of glass coating.

FIG. 4 is a diagram showing a method of testing magnetic shielding properties.

FIG. 5 is a graph showing the results of comparing the magnetic shielding properties of the example and the conventional example.

[Explanation of symbols]

 1 Base metal 2 Forsterite coating 3 Vitreous coating 4 Paint coating 5 Sample material 6 Magnet 7 Gauss adjustment distance 8 Measuring distance 9 Gauss measuring machine

Claims (1)

[Claims] 1. A magnetic shield excellent in coating adhesion, characterized in that in a grain-oriented silicon steel sheet coated with a paint, the base of the coating is only a forsterite coating with a thickness of 2 μm or less on the base metal. Grain-oriented silicon steel sheet.