KR20040087606A - construction method of magnetically shielded room - Google Patents

Abstract

PURPOSE: A method for fabricating a magnetic shielded room is provided to enhance reliability by shielding effectively terrestrial magnetic field and artificial magnetic field. CONSTITUTION: A magnetic shielded room is used for shielding magnetic field including terrestrial magnetic field and power frequency of 60Hz in order to measure magnetic field of a living body, operate an electron beam lithography apparatus and a precision measurement apparatus, and create the low magnetic field around a transformer and living environment. The magnetic shielded room includes an external multilayer wall. The external multilayer wall is formed with a Si steel plate or a nickel alloy including nickel 47 to 49 weigh percent.

Description

Construction method of magnetic shielded room

The present invention relates to a method for manufacturing a magnetic shielding room, and more particularly, to an external magnetic field including a geomagnetic field and a 60 Hz power magnetic field for biomagnetic field measurement, electron lithography equipment, precision measurement device operation, and low magnetic field working environment. A magnetic shield room used for shielding.

Magnetic shielding room is effective in shielding low frequency magnetic field as well as direct current magnetic field by using magnetic shielding effect using magnetic material with high permeability and eddy current shielding effect using metal with high electrical conductivity.

In order to manufacture a high shielding magnetic shielding room, it is usually made of double or triple wall, and the distance between the wall and the wall is about 20 to 30 cm, and aluminum is installed between them.

In the conventional double-walled magnetic shielding room, the magnetic permeability of both the inner wall and the outer wall is high, regardless of the strength of the magnetic field in the space in which the shielding room is to be installed, and magnetic materials such as mumetal and permalloy having 78 to 80% nickel. Is used.

Conventional magnetic materials such as Mumetal, Permalloy, Hypernom, and Magneifier 7904 have a high magnetic permeability for low external magnetic fields. For example, the coercivity of the material is as low as 0.01 Hersted (Oe), which is about one-fifth of the Earth's magnetic field, so it is easily magnetized by the earth's magnetic field, resulting in low permeability.

Therefore, the shielding effect is reduced when the magnetic field strength is much stronger than the coercive force of the magnetic material such as the earth magnetic field and the surroundings of a large electric power device.

In addition, materials with high nickel content have weaknesses in permeability and shielding performance due to mechanical stress generated during cutting, processing and assembly, and these materials are expensive.

The present invention has been made to solve the above-mentioned drawbacks of the prior art, a magnetic material having a coercive force similar to the strength of the earth's magnetic field to a shielded room outer wall material so that the shielding material is not easily magnetized by the earth's magnetic field and an artificial strong magnetic field. By using it, the magnetic shielding performance is enhanced in a strong magnetic field environment, the shielding performance is not deteriorated by stress, the material is easily handled and the shielding room price is lowered.

1 is a perspective view showing an example of a magnetic shield room according to the present invention,

2 is a cross-sectional view showing an example of the magnetic shield room wall surface according to the present invention,

3 is a plan view showing a manufacturing direction in the manufacturing process of the silicon steel sheet used in the magnetic shield room according to the present invention,

4 is a plan view showing an example of a laminated magnetic shield plate installed in a magnetic shield room according to the present invention;

5 is an enlarged partial cross-sectional view showing a corner portion of the magnetic shield room according to the present invention,

6 is an enlarged cross-sectional view of a part of a laminated magnetic shield plate installed in a magnetic shield room according to the present invention.

1: shielding wall 2: door 3: outer wall

4: aluminum layer 5: inner wall 6: longitudinal direction

7: Vertical direction 8, 9, 10: Bottom 11, 12, 13: Top

14, 15: vertically oriented silicon steel sheet 16, 17: magnetic plate 18, 19: bottom

20, 23: gap 21, 22: top 24 magnetic plate

1 is a view showing a schematic structure of a magnetic shield room.

The magnetic shield room is composed of a shield wall 1, a door 2 and the like.

FIG. 2 shows a double magnetic shielding wall structure. The outer wall 3 and the inner wall 5 are made of a magnetic material, and an aluminum layer 4 is provided in the middle thereof.

Since the outer wall 3 of the magnetic shielding wall is directly exposed to the external magnetic field, the magnetic field to be shielded is stronger than the inner wall 5.

Therefore, a material whose coercivity is similar to the strength of the magnetic field is used as the material of the outer wall 3 so that it is not easily magnetized by a strong external magnetic field including the earth magnetic field.

High direction 49 steel and 49% 49% of nickel (Hiperm 49) and alloy 4750 (Alloy 4750) containing nickel have about coercive force of 0.1 Hersted (Oe). Suitable material.

High-oriented silicon steel sheet is cheaper than the 4750 alloy at a fifth the price, but the permeability is different depending on the direction. When the high-direction silicon steel sheet is manufactured in FIG. 3, the pulling direction of the steel sheet is lengthened in the longitudinal direction 6, which is referred to as a rolling direction.

Since the permeability in the direction (7) perpendicular to the rolling direction (length direction) is much smaller than that in the longitudinal direction (6), in order to increase the shielding ratio evenly according to the direction when the shielding room is manufactured, the high-oriented silicon steel sheets are overlapped. As shown in FIG. 4, it is preferable to arrange the bottom surfaces 8, 9, 10 and the top surfaces 11, 12, 13 so that the longitudinal directions thereof are perpendicular to each other.

Since the magnetic force lines leak from the edge of the shielded room, there are many differences in the shielding performance depending on the treatment method of the edge. In the case of using the high-oriented silicon steel sheets 14 and 15 whose longitudinal directions are perpendicular to each other as the material of the outer wall 3 in FIG. 5, the corner portion has a high coercive force and has a nickel content of 47 to 49% with no difference in permeability depending on the direction. Use (16, 17).

As shown in FIG. 6, when the materials are stacked and used, the gaps 20 between the bottom surfaces 18 and 19 and the gaps 23 between the top surfaces 21 and 22 should be shifted from each other so as not to be at the same point. Isotropic magnetic body plate 24 to reinforce the upper portion of the gap (20, 23) to prevent leakage of magnetic lines.

Since the magnetic field is considerably reduced by the outer wall 3 of the shielded room, the inner wall 5 can further shield the magnetic field by using mumetal, permalloy, etc., which have high permeability materials.

The permeability is about 40,000 when the high-oriented silicon steel sheet is used as the outer wall (3) material at 0.3 Hersted (Oe), which is the average strength in the north-south and vertical directions of the earth's magnetic field. At 20,000 geomagnetic fields, the highly oriented silicon steel sheet as the outer wall material had better shielding properties.

When the magnetic shielding room was manufactured to shield the electron beam lithography facility by overlapping high-direction silicon steel sheets perpendicular to each other, the global magnetic field could be reduced by about one-hundredth.

It is possible to improve the shielding performance against the earth magnetic field and the artificial strong magnetic field, to prevent the shielding performance from being deteriorated by stress, to easily handle the shielding material, and to lower the price of the shielding room.

The present invention is not limited to the above embodiments, and it is apparent that many modifications can be made by those skilled in the art within the technical spirit of the present invention.

Claims (4)

In constructing a magnetic shield room for shielding magnetic fields, including earth magnetic field and 60 Hz power frequency, for biomagnetic field measurement, electron lithography equipment, precision instrument operation, transformer, and low magnetic field living environment, A method of manufacturing a magnetic shield room, characterized in that the outer wall (3) of the multi-wall is made of a high-oriented silicon steel sheet or a nickel alloy containing 47 to 49% nickel. The method of claim 1, wherein when the high-direction silicon steel sheet is used, the longitudinal direction of the top surface (11, 12, 13) is perpendicular to the longitudinal direction of the bottom surface (8, 9, 10) when multiple layers of high-oriented silicon steel sheet Magnetic shielding room manufacturing method characterized in that. [3] The edge portion according to claim 1 or 2, wherein in the case of using the high-oriented silicon steel sheets 14 and 15 whose longitudinal directions are perpendicular to each other as the material of the outer wall 3, the edge portion has a nickel alloy having no permeability difference depending on the direction. A method for producing a magnetic shield room, characterized by using a magnetic body plate (16, 17) of 47 to 49%. The method according to claim 1, wherein when the high-oriented silicon steel sheet is stacked and used, the gaps 20 between the bottom surfaces 18 and 19 and the gaps 23 between the top surfaces 21 and 22 are arranged so as not to come to the same point. And additionally reinforcing the upper portion of the gap (20, 23) with an isotropic magnetic body plate (24).