JPS5826412B2 - Method and device for improving properties of electrical steel sheets - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for improving the magnetic properties of electrical steel sheets.

In the past, many methods have been proposed to improve the magnetic properties of electrical steel sheets, but for example, applying mechanical processing to the surface of the steel sheet as described in Japanese Patent Publication No. 50-35679 has been proposed by laminating the steel sheets. This is not a preferable method for constructing iron cores, and it has been difficult to put it into practical use.

The present inventors focused on the fact that the magnetic properties of electrical steel sheets could be improved by irradiating the electrical steel sheets with laser light.
In No. 7662, we proposed a method of irradiating the surface of a grain-oriented electrical steel sheet with a finishing firing process with laser light.

The present invention is a further innovative improvement of the above-mentioned proposal, and the first invention is a lens array arranged in a direction perpendicular to the rolling direction on the surface of an electromagnetic steel sheet to be irradiated with pulsed laser light emitted from a laser oscillation device. The gist of the invention is to make the laser beam incident on the steel plate, focus the laser light from the lens array on the surface of the steel plate, and irradiate the steel plate at regular intervals in the rolling direction.

Furthermore, a second invention is directed to an apparatus for carrying out the method of the first invention.

As is well known, grain-oriented electrical steel sheets, for example, crystallographically (11
The (110) plane of each crystal grain on the plate surface, expressed as a 0)(001,1 structure, is parallel to the plate surface, and the easy axis of magnetization [00
1. It takes advantage of the fact that l is parallel to the rolling direction, and its production requires extremely strict process control. However, the present invention can be applied to steel sheets or coils that have undergone final annealing, or to those on which an insulating film has been formed. Applicable.

According to the findings of the present inventors, in the first invention, the energy density R is 0.01 J/crtt or more, 1000 J
It is desirable to irradiate the steel plate surface with point-like pulsed laser light of /c4 or less.

Further, at this time, it is preferable that the pulse oscillation time width is 100 m5ec or less.

If the pulse oscillation time width exceeds 100 m5ec, the effect of improving magnetic properties will decrease because thermal melting phenomenon that occurs on the surface of the steel sheet during irradiation causes changes in the crystal structure.

In the present invention, the laser beam is adjusted so that it is irradiated from the laser oscillation device onto the surface of the electromagnetic steel sheet through each lens of the lens array.

At this time, the lens array is arranged so that the arranged lens rows are lined up in a direction (C direction) that is almost perpendicular to the rolling direction (L direction or moving direction), and one surface of the lens array is arranged to face the laser beam path emitted from the laser beam oscillation device. The surface has a height determined above the surface of the electromagnetic steel sheet to be irradiated (that is, the height is determined by the size of the laser beam on the surface of the steel sheet and the focal length of the lens)
Set it up so that

Therefore, the laser beam exiting the lens array is focused on the steel plate so as to have a desired energy density.

Since the present invention is a non-contact operation, it is completely unaffected by the waveform shape that is inevitable during the manufacture of electrical steel sheets, and has a great feature that it can be easily put to practical use industrially.

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

FIG. 1 shows an implementation of the present invention in which a laser beam from a laser oscillation device is scanned and sequentially enters each lens of the lens array.

A laser oscillation device 1 oscillates a pulsed laser beam 2 having irradiation energy necessary for the present invention, and the laser beam is transmitted to a scanning unit 5 consisting of a rotating mirror 3 and a condensing lens 4.
As a result, the light sequentially reaches the end surface 7 of the lens array 6, passes through the lens array 6, is condensed, and is irradiated onto the steel plate surface 8 in a dotted manner.

FIG. 2 shows a plan view of the lens array and the steel plate.

At this time, the irradiation diameter a of the laser beam focused by one lens is 0.004~1, and the wind energy density P is 0.01~
1000 J/crA is preferred.

Also, the distance a between the centers of the light spots of the laser beam that passes through the adjacent lenses of the lens array 6 and irradiates the steel plate surface.
is set to 0.1 to 30 wrL.

When the diameter of the lens 6 is larger than the distance a, the two lens arrays 6-L 6-2 are
It is also possible to make the irradiation angles of the two rays symmetrical and linear in the C direction by arranging the irradiation angles differently from each other.

Further, the L direction irradiation interval t is set to o, oi to 30wrL.

FIG. 4 shows an example of the present invention in which laser light from a laser oscillation device is stretched out into a thin line and is made to simultaneously enter each lens of the lens array.

A laser oscillation device 1 oscillates a pulsed laser beam 2 having irradiation energy necessary for the present invention, and the laser beam 2 is transmitted to a cylindrical mechanism 10 and a cylindrical lens 1.
1 into a thin line-shaped beam in the C direction, and simultaneously enter the lens array 6.

Therefore, the steel plate surface 8 is also irradiated in a dotted manner at the same time.

Note that the lens array does not need to be installed strictly perpendicular to the rolling direction, and an arrangement of up to about 30 lenses does not pose any practical problem.

Of course, in this case, it is necessary to tilt the rotating mirror cylindrical lens and the like in the same manner as the lens array so that the laser beam is incident on the lens array.

Next, examples of the present invention will be shown.

Example 1 Lens arrays with a diameter of 0.5 rran were arranged at intervals of a = 0.5 mm in the C direction on a grain-oriented electrical steel sheet that was moving at a speed of V = 500 mm/S, and from each lens. The laser light energy density P is 3. OJ/
A YAG laser was repeatedly irradiated with a repetition frequency of 100 Hz so that crtl was obtained.

The iron loss value and magnetic flux density in the L direction before and after laser beam irradiation were measured for several samples, and are shown in Table 1.

Table 1 shows that even though the iron loss value before irradiation is quite large and varies, the iron loss value decreases significantly by laser light irradiation.
Also, the dispersion has become very small.

Moreover, the magnetic flux density before and after irradiation hardly changed.

Example 2 A lens array with a diameter of 1 wrL was arranged in the C direction at an interval of a = 5 rran on a finish annealed grain-oriented electrical steel sheet moving at a speed of V-500 rra/S, and the laser light energy from each lens was Density P is 3-OJ/cr
Repeat the YAG laser so that the frequency I K
Irradiation was performed at Hz.

The iron loss value and magnetic flux density in the C direction before and after laser beam irradiation were measured for several samples, and the results shown in Table 2 were obtained.

Table 2 shows that the iron loss value in the C direction was also significantly reduced by laser beam irradiation.

Example 3 A grain-oriented electrical steel sheet treated with an insulating film ☆ moving at a speed of V = 500 rran/S was irradiated with laser light under the same conditions as Example 1, and the magnetic properties in the L direction before and after irradiation were measured. Changes were measured.

The results are shown in Table 3.

Table 3 shows that the iron loss value after irradiation was significantly reduced compared to the iron loss value before irradiation.

[Brief explanation of the drawing]

Fig. 1 is a schematic side view showing an example of the present invention, Fig. 2 is a plan view showing a lens array and a steel plate, and Fig. 3a. 4b is a side view and a plan view showing the case where a plurality of lens arrays are used, and FIG. 4 is a schematic side view showing another embodiment of the present invention. 1: I nose oscillator, 3: Rotating mirror, 4: Condensing lens, 5: Scanning unit, 6: Lens array, 8: Steel plate, 10 Nijilintric mirror, 11 Nijilintrical lens.

Claims (1)

[Scope of Claims] 1. A method for improving the characteristics of an electrical steel sheet, comprising: installing a lens array above the surface of the steel sheet, and irradiating the surface of the steel sheet with a laser beam through the lens array. 2. The method for improving the characteristics of an electrical steel sheet according to claim 1, characterized in that the laser beam is made incident on the lens array by scanning the laser beam over the lens array. 2. The method for improving the characteristics of an electrical steel sheet according to claim 1, characterized in that the 3v-f light beam is formed into a linear shape and is made to simultaneously enter a lens array. 4. An apparatus for improving the characteristics of an electrical steel sheet, characterized in that a lens array is provided between a laser beam irradiation source and the steel sheet at a minute interval directly above the steel sheet.