JPS59197525A - Preparation of directional electromagnetic steel plate - Google Patents

Abstract

PURPOSE:To obtain a directional electromagnetic steel plate excellent in magnetic characteristics and good in coating characteristics, by irradiating a directional electromagnetic steel plate after finish annealing with laser beam in such a state that the interval between a laser condensing lens and the steel plate is made different from the focal distance of the condensing lens. CONSTITUTION:The plate surface of a direction electromagnetic steel plate after finish annealing is irradiated with laser beam 4 from a laser transmission apparatus 2 through a laser condensing lens 3. In this case, the interval of the laser condensing lens 3 and the directional electromagnetic steel plate 1 is made different from the focal distance (f) of the laser condensing lens 3. In this occasion, the steel plate may be brought nearer than the focal distance (f) or may by kept away therefrom. By this method, a directional electromagnetic steel plate good in insulating coating characteristics and reduced in iron loss is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a grain-oriented electrical steel sheet with excellent magnetic properties, and more specifically, a grain-oriented electrical steel sheet with excellent magnetic properties and good coating properties is produced by irradiating a laser beam. It relates to a manufacturing method.

Grain-oriented electrical steel sheets, which are mainly used as core materials for transformers and other electrical equipment, are usually crystallographically (1
10) It is displayed as [Oo1] structure, and what it means is that the (110
) plane is parallel to the plate surface, and the axis of easy magnetization [001] is parallel to the rolling direction.

Grain-oriented electrical steel sheets generally contain silicon with a ratio of 2.0 to 4.0, and contain A7N, MnS, BN, and S as inhibitors.
e.

A hot coil containing a predetermined amount of one or more of the elements forming CuS, Sb, etc. is pickled and cold-rolled once or twice or more with annealing in between to give the product a thickness. After that, it is decarburized and annealed, an annealing separator containing MgO as the main component is applied, and then it is finished at a high temperature in order to selectively grow crystals with (110) [001) orientation through secondary recrystallization. Manufactured by annealing. Grain-oriented electrical steel sheets on which a glass film is formed by secondary recrystallization through final annealing may be treated with an insulating film, for example, by Japanese Patent Publication No. 53-2
As shown in Japanese Patent No. 8375, a colloidal silica-phosphoric acid-aluminium-chromic acid-based treatment solution was applied, and 7
Baking treatment is performed at a temperature of 00 to 900°C. In this case, the film becomes glassy and applies tension to the steel plate during cooling due to the difference in thermal expansion coefficient between the film and the steel plate. As a result, iron loss can be reduced.

In order to save energy, there is a strong demand for the development of grain-oriented electrical steel sheets with low core loss. The surface is irradiated with a laser beam to subdivide the magnetic domains,
For example, a method for reducing iron loss is disclosed in JP-A-56-123325.
It is proposed in the Publication No. According to this method, iron loss is reduced and excellent magnetic properties are obtained, but the properties of the insulating coating on the surface of the steel sheet tend to be slightly deteriorated, and there is room for improvement.

For this reason, as a result of various studies and considerations, the inventors of the present invention have determined the direction and direction of irradiating a laser beam from a laser transmitter through a laser condensing lens onto the surface of a grain-oriented electromagnetic steel sheet with finished firing. It was discovered that by irradiating the laser beam with the distance between the electromagnetic steel sheet and the laser condensing lens different from the focal length of the condenser lens, iron loss could be significantly reduced without deteriorating the insulation coating.

The present invention has been constructed based on this knowledge, and its gist is to provide a grain-oriented electrical steel sheet with a finish-sintered purity.
In order to improve magnetic properties by irradiating a laser beam from a laser transmitter through a laser condensing lens, the distance between the laser condensing lens and the grain-oriented electromagnetic steel sheet is made different from the focal length of the laser condensing lens. A method of manufacturing a grain-oriented electrical steel sheet, which comprises irradiating the steel sheet.

The present invention will be explained in detail below with reference to the drawings.

In the drawing, reference numeral 1 denotes a grain-oriented electromagnetic steel sheet with a finish-hardened finish, and a laser beam 4 is irradiated onto the surface of the steel sheet 1 from a laser transmitter 2 through a laser condensing lens 3. In this irradiation, the distance between the laser condenser lens 3 and the grain-oriented electrical steel sheet 1 is made different from the focal length f of the laser condenser lens 3.

In this case, the focal length may be moved closer to the focal length f as shown in A in FIG. 1, or it may be moved farther away as shown in B in FIG. The distance to be varied is preferably 2 to 20 times the focal length f of the laser condensing lens 3.

Note that a method for making the distance between the laser condenser lens 3 and the grain-oriented electromagnetic steel sheet 1 different by the focal length f can be easily achieved by providing the laser condenser lens 3 with a moving device (not shown). Alternatively, a method may be used in which the running surface of the grain-oriented electrical steel sheet 1 is changed to allow the sheet to pass.

Next, an example will be described.

Example 1 A CO2 laser transmitter was used to irradiate a finish-sintered pure grain-oriented electrical steel sheet with a plate thickness of 0.3 mm and a Sl content of 2.93% with a laser beam through a laser condensing lens. The focal length f of the laser condensing lens used here is 63.
5+nm, and the irradiation conditions were as follows.

Irradiation ・・・・・・・・・ Linear irradiation line interval ・・・・・・・・・ 10-hour irradiation energy density・
・・・・・・・・・ 1 mυ et al. 2 In addition, the distance between the laser condensing lens and the grain-oriented electromagnetic steel sheet and the focal length of the laser condensing lens f and p ratio/f k are varied between 1 and 12%. irradiated with a laser beam.

Thereafter, the withstand voltage and interlayer current of the insulating coating were measured, and the appearance of the coating was also observed, and the iron loss W was 77.

The improvement equation was also measured and the results are shown in Table 1. The iron loss W before laser irradiation is 1.03 w/kg 71
It was 50.

First Example 2 The same finish-fired grain-oriented electrical steel sheet used in Example 1 was irradiated with a laser beam through a laser condensing lens using a CO2 laser transmitter.

The focal length f of the laser condensing lens used here is 63
．． The irradiation conditions are as follows.

Irradiation ・・・・・・・・・Linear irradiation interval
・・・・・・・・・lo+m++irradiation energy density・
・・・・・・・・・ 0.5 to 1.5 mJ/1an2 The ratio between the distance between the laser condensing lens and the grain-oriented electromagnetic steel plate and the focal length f of the laser condensing lens is 4 inches and 5 inches. did.

After performing this irradiation, the iron loss W1715o was measured and the improvement (lower range) thereof is shown in FIG.

In addition, the insulation coating properties were measured and the results are shown in Table 2.

2. As is clear from the results of Example 1.2, according to the present invention, a grain-oriented electrical steel sheet with good insulation coating properties and reduced iron loss can be produced.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing an improvement in iron loss in Example 2 of the present invention.

Claims (1)

[Claims] When irradiating a grain-oriented electrical steel sheet in the finish annealing process with a laser beam from a laser transmitter through a laser condensing lens to improve its magnetic properties, the distance between the laser condensing lens and the grain-oriented electrical steel sheet is determined by the focal length of the laser condensing lens. A method for producing a grain-oriented electrical steel sheet, which comprises irradiating a grain-oriented electrical steel sheet with a laser beam.