JPH09162586A - Magnetic shielding case and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic shielding case and its manufacture wherein magnetic shielding of external magnetic field is excellent, stable residual magnetism characteristics can be obtained, magnetic hysteresis can be reduced, and manufacturing is enabled at a low cost. SOLUTION: Under a meter 10, a cup-shaped magnetic shielding case 5 is installed, which is constituted of two-layered material. Outer side material 5a is composed of stainless steel material (magnetic SUS) or the like wherein the residual magnetism Br is high, and the permeability μ is small. Inner side material 5b is composed of permalloy or the like wherein the residual magnetism Br is small and the permeability μ is high.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic shield case and a method for manufacturing the same, and more particularly to a magnetic shield case used as an outer case for automobile instruments and the like and a method for manufacturing the same.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional automobile meter.
FIG. As shown in FIG. 4, the meter 3
A cup-shaped case 35 is provided in the lower part of 0.
An outer housing 34 is provided in the case 35,
In the outer housing 34, crossing coils 37, 38 are wound around the inner housing 39 so as to cross each other.
Is arranged. Further, a movable magnet 36 made of a disk-shaped magnet is horizontally arranged in the inner housing 39. A through hole is provided in the center of the movable magnet 36 in the radial direction, and the pointer shaft 32 is inserted and fixed in the through hole. The lower end of the pointer shaft 32 is rotatably mounted on a support 39a provided in the lower portion of the inner housing 39, while the upper end of the dial 33 is mounted on the upper end surface of the outer housing 34. Through hole 3
The needle 31 extends upward from 3a and is fixed to the tip thereof.

In the meter 30 constructed as described above, a current flows from the detector (not shown) outside the meter 30 into the cross coils 37 and 38, and a magnetic field is generated in the meter 30. This magnetic field causes the movable magnet 36 to rotate by a certain angle, and the pointer 31 also rotates accordingly, causing the dial 33 to rotate.
It will point to the upper value.

In the case 35 of the meter 30 as described above,
The function of a magnetic shield is required to prevent the influence of external magnetism from affecting the movable magnet 36. Therefore, as the material of the case 35, conventionally, a 1% silicon steel plate having a relatively high residual magnetism Br, SPCC or SPCE is used.
Cold-rolled steel sheet (JIS G3141) and the like are used.

However, in a meter having a magnetic shield case made of these materials, the magnetic shield effect is excellent, but the residual magnetism is large, so that the current flowing in the crossing coils 37 and 38 is cut off. Even if it is the case, the movable magnet 3 should be stationary at a predetermined position.
There is a problem that 6 rotates a little and the so-called residual indicating characteristic is bad. If the residual magnetism is large, the rotation angle of the movable magnet 36 may be affected by the residual magnetism even when the meter is operating. Therefore, the pointer 31 indicates an inaccurate value on the dial 33, which causes so-called indication hysteresis.

Therefore, in order to improve the residual indicating characteristic and reduce the indicating hysteresis, as a material of the case 35, a permalloy PC material (70-80% N) having a low residual magnet Br is used.
i-Fe), PB material (40-50% Ni-Fe) and P
D (35-40% Ni-Fe) material or the like is used.
Although a material having a high magnetic permeability has an excellent magnetic shield effect, when an excessive magnetic flux is received, the magnetic flux is saturated and the magnetic shield effect is reduced.

In addition to the magnetic shield case as described above, as shown in FIG. 5, a cup-shaped case 35 is formed of the cold-rolled steel plate or synthetic resin described above, and the residual magnetism Br is retained on the inner peripheral surface. Thin plate 40 made of low amorphous alloy
There is also proposed a magnetic shield case in which a cylinder is rolled several times and arranged (Japanese Utility Model Publication No. 2-47500).

[0008]

However, the above-mentioned permalloy PC material, PB material, and PD material are all expensive, which increases the manufacturing cost of the magnetic shield case. Note that these materials are of excessive quality with respect to the required magnetic properties. Also, as a particularly serious problem, since these materials are magnetic substances, the meter 3
A magnetic circuit is formed in response to the magnetic field generated by the movable magnet 36 or the crossing coils 37, 38 arranged in the zero position, and the operation of the pointer 31 is affected. Therefore, the magnetic shield case 35 is required to have a magnetic shield for the outside and a material having a small magnetic reaction for the inside.

Regarding the magnetic shield case in which the amorphous alloy thin plate 40 is arranged on the inner peripheral surface of the case 35, the amorphous alloy is expensive and the processing cost for disposing the amorphous alloy thin plate 40 on the inner peripheral surface of the case is high. Manufacturing cost is high. Further, in the case of this magnetic shield case, since the amorphous alloy thin plate 39 is disposed only on the inner peripheral surface, that is, the side surface of the case 35, the bottom surface of the case 35 is not magnetically shielded.

The present invention has been made in view of the above problems, is excellent in magnetic shield by an external magnetic field, can obtain a stable residual indicating characteristic, and can reduce indicated hysterisis. An object of the present invention is to provide a magnetic shield case that can be manufactured at low cost and a manufacturing method thereof.

[0011]

A magnetic shield case according to the present invention comprises a two-layer material including an inner material and an outer material, and the inner material and the outer material have a residual magnetic Br of [inner material <
The outer material] and the magnetic permeability μ are [inner material> outer material].

In the method of manufacturing a magnetic shield case according to the present invention, the first material and the second material having a larger residual magnetism Br and a smaller magnetic permeability μ than the first material are stacked, A first drawing step of drawing a first processed product by drawing a cup-shaped material so that one material is on the inside, and a portion other than the wrinkles formed in the opening of the first processed product by the first drawing step. It is characterized by including a second drawing step of drawing again to form a second processed product, and a step of finally removing the wrinkles. Moreover, you may use the clad material which consists of said 1st material and said 2nd material.

Further, after the second drawing step, one or a plurality of drawing steps may be provided for drawing the portion other than the wrinkles generated in the immediately preceding drawing step again.

[0014]

In the present invention, a material having a high magnetic permeability μ and a small residual magnetism Br is used as the inner member of the magnetic shield case, and the residual magnetism Br is high as the outer member.
A material with a low magnetic permeability μ is used. Since an outer material having a low magnetic permeability μ and a high residual magnetism Br is arranged, a magnetic shield against an external magnetic field is excellent. Further, since the residual magnetic material Br has a small residual magnetism Br and a magnetic permeability μ is large, the inside of the magnetic shield case is improved. There is little magnetic reaction due to the magnetic field generated at.

When the inner material is, for example, a soft magnetic material such as Permalloy PB material or PC material, a magnetic shield case having an excellent magnetic shield can be obtained.
In addition, the magnetic shield case is made into two layers, the plate thickness of the expensive permalloy PB material or the like is made thinner than before, and other inexpensive materials are combined and reinforced to that extent to reduce the manufacturing cost. be able to. It is preferable to use, for example, an inexpensive stainless steel material (magnetic ferritic stainless steel) as the outer material. By using a non-magnetic austenitic stainless steel material as the outer material according to required characteristics, the magnetism of the entire magnetic shield case can be reduced.

Further, as the inner material and the outer material, various materials and plate thicknesses can be combined under the condition that the residual magnetism Br and the magnetic permeability μ satisfy the above conditions. Therefore, according to the present invention, the magnetic characteristics of the magnetic shield case can be arbitrarily and easily adjusted according to the required magnetic characteristics at the time of use. The magnetic shield case satisfying the required magnetic characteristics can also be manufactured by changing the magnetic annealing conditions in the heat treatment.

In the method of the present invention, the first material and the second material are superposed and drawn into a cup shape so that the first material is on the inside (first drawing step). At this time, a material having a high magnetic permeability μ and a small residual magnetism Br is used for the first material, and a material having a small magnetic permeability μ and a large residual magnetism Br is used for the second material. use. Then, the portion other than the wrinkles formed in the opening of the first processed product obtained by the first drawing step is drawn again (second drawing step). In the second drawing step, since the parts other than the wrinkles of the first processed product are drawn, it is possible to prevent the wrinkled parts from spreading to the second processed product formed by the second drawing process.
Further, in the first drawing step, since the first material and the second material may be superposed and drawn, it is possible to easily perform the drawing without performing a special processing such as a clad before the processing.

Further, after the second drawing step, the magnetic shield case having an even deeper shape can be manufactured by drawing the part other than the wrinkles once or a plurality of times.

[0019]

Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. FIG. 1 is a sectional view showing a meter using a magnetic shield case according to an embodiment of the present invention. As shown in FIG. 1, a cup-shaped magnetic shield case 5 is provided below the meter 10. This magnetic shield case 5, as shown in FIG.
The outer material 5a is made of a stainless steel material (magnetic SUS), and the inner material 5b is made of a permalloy PB material. The stainless steel material (magnetic SUS) used as the outer material 5a has a high residual magnetism Br and a low magnetic permeability μ. On the other hand, the permalloy PB material used as the inner material 5b has a small residual magnetism Br and a large magnetic permeability μ.

An outer housing 4 is provided in the magnetic shield case 5, and cross coils 7 and 8 wound around the inner housing 9 so as to intersect each other are arranged in the outer housing 4. Has been done. The cross coil 8 is wound around the cross coil 7 wound around the inner housing 9 in a direction orthogonal to the winding direction. A movable magnet 6 made of a disk-shaped magnet is arranged in the inner housing 9. At the center of the disk of the movable magnet 6, a pointer shaft 2 extending upward perpendicularly to the radial direction is fixedly provided, and the tip end of the pointer shaft 2 is provided at the upper end surface of the outer housing 4. It projects from the through hole 3a of the dial 3 thus formed. The pointer 1 is fixed to the tip of the protruding pointer shaft 2. In addition,
The thickness of this magnetic shield case is 0.2-1.0 mm
Any degree is acceptable.

The magnetic shield case 5 is made of the outer material 5
The c and the a and the inner member 5b are not limited to those obtained by rolling or pressing, but may be simply laminated.

In the meter 10 configured as described above, a current flows through the crossing coils 7 and 8 from a detector (not shown) arranged outside the meter 10, and a magnetic field is generated inside the meter 10. . Then, the magnetic field causes the movable magnet 6 to rotate by a certain angle, and accordingly the pointer 1 also rotates to indicate the value on the dial 3.

In the magnetic shield case 5 of the meter 10, since the outer material 5a is made of stainless steel material (magnetic SUS) having a high residual magnetism Br and a low magnetic permeability μ, the movable magnet 6 in the meter 10 is Not affected by external magnetic field. Further, since a permalloy PB material having a small residual magnet Br and a large magnetic permeability μ is used as the inner material 5b, the magnetic shield case 5 is affected by the movable magnet 6 and the crossing coils 7 and 8 in the meter 10. Nothing. Therefore, in the meter 10 in which such a magnetic shield case 5 is used, the residual indicating characteristic is stable and the indicating hysteresis characteristic can be reduced.

Further, the combination of the inner member and the outer member is not limited to the above-mentioned one, and it is possible to combine one having a small magnetic permeability μ as an outer member and one having a large magnetic permeability μ shown in the following Table 1 as an inner member. it can. For example, the Fe material can be used as the outer material, the PD material can be used as the inner material, the PB material can be used as the outer material, and the PC material can be used as the inner material.

[0025]

[Table 1]

Before explaining the method of manufacturing the magnetic shield case according to this embodiment, a method of manufacturing the magnetic shield case by the conventional drawing process will be described.

6A and 6B are views showing a conventional method of manufacturing a magnetic shield case. FIG. 6A is an apparatus used in the first drawing step, FIG. 6B is an apparatus used in the second drawing step, and FIG. It is sectional drawing which shows the to-be-processed member before a 1st drawing process, (d) the 1st processed product after a 1st drawing process, (e) the 2nd processed product after a 2nd drawing process. As shown in FIG. 6A, in the apparatus 20 for performing the first drawing process, a mold 16 is provided inside the mold installation table 17, and above the mold 16, the mold 16 is provided. 16 and a cylindrical stripper 12 that holds the edge of the disk-shaped workpiece 45 is provided. Further, when the member 45 to be processed is sandwiched by the stripper 12 and the die 16, the lower end edge of the stripper 12 is held by the jig 14.
Fixed by Further, a cylindrical punch 13 is provided inside the stripper 12.
3 is moved in the vertical direction via a rod 11 provided at the upper end portion thereof and connected to a driving device (not shown).

Conventionally, the magnetic shield case is manufactured as follows by using the drawing apparatus 20 having the above-described structure. First, as shown in FIG.
6 and the lower end surface of the stripper 12
The die 16 of the disk-shaped workpiece 45 shown in FIG.
The part larger than the diameter of the cavity is clamped with a constant pressure. By sandwiching the member 45 to be processed by the lower end surface of the stripper 12 and the upper end surface of the die 16 in this way, it is possible to perform processing while preventing wrinkles from being generated during drawing.

After the workpiece 45 is installed in the processing device 20, the punch 13 is lowered toward the workpiece 45. Then, as shown in FIG. 6D, the processed member 45 is formed into a shallow cup-shaped first processed product 45a.

However, when the peripheral edge of the member 45 to be processed enters the mold 16 due to the progress of drawing by the punch 13, wrinkles are generated on the peripheral edge of the member 45 to be processed. This wrinkle is generated by the following process. FIG. 7 is an enlarged view showing the vicinity 50 of the peripheral edge of the member 45 to be processed, which is processed by the drawing device 20 shown in FIG. When the workpiece 45 is drawn, the workpiece 45 is sandwiched between the stripper 12 and the mold 16 for a while after the start of processing, so that the drawing is performed while preventing wrinkles from occurring. However, as the drawing process progresses, at the final stage of the drawing process, as shown in FIG. 7, the peripheral edge of the member to be processed 45 is not clamped by the stripper 12 and the mold 16. Therefore, the stripper 12 cannot function as a wrinkle retainer, and the circumferential length of the peripheral edge portion 48a of the workpiece 45 is reduced by drawing.
It becomes the circumferential length of the opening of the first processed product 45a shown in FIG. 6 (d). As a result, the difference in the circumference lengths described above causes
Wrinkles occur at the opening edge portion of the upper end of the first processed product 45 shown in (d) (wrinkle portion 48a). Such wrinkles inevitably occur when the entire workpiece 45 is drawn.

After that, the first processed product 45a is drawn again using the drawing device 30 shown in FIG. 6 (b). The drawing device 30 has substantially the same configuration as the drawing device 20 that has performed the first drawing process. That is, the die 26 is provided inside the die installation table 27, and the stripper 22 in which the punch 23 is arranged is provided above the die 26. And this punch 2
3 is moved in the vertical direction via a rod 21 provided at the upper end portion thereof and connected to a driving device (not shown). However,
The diameter of the cavity in the mold 26 of the second drawing apparatus 30 and the diameter of the punch 23 are both smaller than those of the first drawing apparatus 20.

Using the second drawing device 30 as described above, the first processed product 45a is drawn as follows. First, the first processed product 45a is fitted to the lower end of the stripper 22, the lower end of the stripper 22 is brought close to the opening of the mold 26, and the peripheral edge of the lower surface of the first processed product 45a and the mold 26 are separated. Contact with the periphery of the opening. Then, while the first processed product 45a is pressed against the opening of the die 26 by the stripper 22 with a constant pressure, the punch 23 is lowered to perform the drawing process. As a result, the second processed product 45b having a shape deeper than the first processed product 45a can be obtained.

When manufacturing a processed product having a shape deeper than the second processed product 45b, the cavity of the die 26 and the punch 23 of the die 26 in the second drawing device 30 are manufactured in the same manner as in the second drawing process. The second processed product 45b is drawn by using a processing device having a die and a punch each having a smaller diameter. In this way, the magnetic shield case having a desired shape is manufactured.

However, when the magnetic shield case is manufactured as described above, the second drawing step
The area of the wrinkles 48a of the first processed product 45a is enlarged (wrinkles 48b).

Therefore, in the method of the present invention, the magnetic shield case is manufactured as follows in order to suppress the expansion of the wrinkles generated in the processed product and obtain a high quality magnetic shield case.

3A and 3B are views showing a method of manufacturing the magnetic shield case according to this embodiment. FIG. 3A is an apparatus used in the first drawing step, FIG. 3B is an apparatus used in the second drawing step,
(C) is a processed member before the first drawing process, (d) is a first processed product after the first drawing process, and (e) is a second processed product after the second drawing process.
It is sectional drawing which shows a processed product. The first and second drawing devices 20 and 30 shown in FIGS. 3A and 3B used in this embodiment are the same as the processing devices used in the conventional manufacturing method.

In the method of manufacturing the magnetic shield case according to this embodiment, first, as shown in FIG.
A disk-shaped member to be processed 15 in which the first material 15a and the second material 15b shown in FIG. The first material 15a has a small residual magnetism Br and a magnetic permeability μ
, A material having a high residual magnetism Br and a low magnetic permeability μ is used as the second material 15b. Such a processed member 15 includes, for example, a permalloy PB material as the first material 15a and a stainless steel material as the second material 15b. After such a member 15 to be processed is installed in the drawing device 20, drawing is performed as follows with the first material 15a facing inside.

First, similar to the above-described conventional first drawing process, the work piece 15 is subjected to drawing process to manufacture the first processed product 18. Then, as described above, wrinkles are also generated in the opening of the first processed product 18 (wrinkles 18a). By installing this first processed product 18 in the second drawing device 30,
A second drawing process is performed. At this time, unlike the conventional second drawing process described above, not all the first processed product 18 is drawn, but the part 18b other than the wrinkles of the first processed product 18 is drawn. That is, the punch 23 is lowered, and the lowering of the punch 23 is stopped when the drawing work of the portion 18b other than the wrinkles of the first processed product 18 is completed. As a result, only the portion in which no wrinkles are generated is drawn, so that it is possible to manufacture a good quality second processed product 19 without enlarging the wrinkles 18a.

In this embodiment, since two kinds of materials having different characteristics are superposed and drawn, wrinkles are likely to occur in the processed product due to the difference in the shrinkage ratio of the materials, but the wrinkles in the processed product are obtained by the method of the present invention. The expansion of the part can be effectively suppressed. Further, the magnetic shield case can be manufactured at a lower cost than the case where two kinds of materials are processed separately to manufacture a double case or an expensive material is manufactured by increasing the plate thickness. it can.

When manufacturing a deeper product, the third processing apparatus having a die and a punch smaller than the diameter of the cavity and the diameter of the punch 23 in the die 26 of the second processing apparatus 30 (see FIG. (Not shown)
Similar to the drawing process, the part 19b other than the wrinkles 19a of the second processed product 19 is drawn. After the final drawing process, the wrinkles are cut off to complete the magnetic shield case.

As described above, since the parts other than the wrinkles formed in the processed product by the drawing process are drawn again, the expansion of the wrinkles can be suppressed and a high-quality magnetic shield case can be manufactured.

[0042]

As described above, according to the present invention,
Since the magnetic shield case is formed of a two-layer material including an inner material and an outer material, and an outer material having a high residual magnetism Br and a low magnetic permeability μ is used, the magnetic shield against an external magnetic field is excellent. Residual magnetism Br as inner material
Since a material having a small magnetic field and a large magnetic permeability μ is used, it is possible to obtain a magnetic shield case with less magnetic reaction due to the magnetic field generated in the case. By manufacturing a meter or the like using such a magnetic shield case, the residual indicating characteristic can be stabilized and the indicating hysteresis can be reduced.

Also, since the magnetic shield case has a two-layer structure, the plate thickness of the expensive low coercive force material as the inner material can be made thinner than before, and other inexpensive materials are combined as the outer material by that amount. The manufacturing cost can be reduced by reinforced with.

On the other hand, according to the method of the present invention, the first and second
Since a portion other than the wrinkles in the processed product is drawn, it is possible to prevent the wrinkles from expanding due to the subsequent drawing, and it is possible to manufacture a high-quality magnetic shield case.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a meter using a magnetic shield case according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a magnetic shield case according to an embodiment of the present invention.

3A and 3B are diagrams showing a method of manufacturing a magnetic shield case according to an embodiment of the present invention, in which FIG. 3A is a device used in a first drawing process, FIG. 3B is a device used in a second drawing process, and FIG. c)
Is a member to be processed before the first drawing process, (d) is a first processed product,
(E) is sectional drawing which shows a 2nd processed product.

FIG. 4 is a sectional view showing a meter using a conventional magnetic shield case.

FIG. 5 is a perspective view showing a conventional magnetic shield case.

6A and 6B are views showing a conventional method for manufacturing a magnetic shield case, FIG. 6A is a device used in a first drawing step, and FIG.
Is a device used for the second drawing step, (c) is a workpiece to be processed before the first drawing, (d) is a first processed product, and (e) is a second processed product.

FIG. 7 is an enlarged view showing a cross section of a peripheral edge portion of a member to be processed which is processed by the apparatus shown in FIG.

[Explanation of symbols]

 1, 31; pointer 2, 32; pointer shaft 3, 33; dial 4, 34; outer housing 5; magnetic shield case 5a; outer member 5b; inner member 6, 36; movable magnet 7, 8, 37, 38; Cross coil 9,39; Inner housing 11,21; Cylinder 12,22; Stripper 13,23; Punch 14; Jig 15,45; Work piece 15a; First material 15b; Second material 16,26; Mold 17, 27; Mold setting table 18, 45a; First processed product 18a, 19a, 48a, 48b; Wrinkled part 18b, 19b; Portion other than wrinkled part 19, 45b; Second processed product; 20, 30; Drawing process Device 35; Case 40; Amorphous thin plate 50; Vicinity of peripheral edge of workpiece

Claims (4)

[Claims] 1. A two-layer material including an inner material and an outer material, wherein the inner material and the outer material have a residual magnetism Br of [inner material <outer material] and a magnetic permeability μ of [inner material> outer material]. A magnetic shield case characterized in that 2. A first material and a residual magnetism B more than that of the first material.
a first drawing step for obtaining a first processed product by stacking a second material having a large r and a small magnetic permeability μ and drawing the cup-shaped product so that the first material is on the inside; A second drawing step of forming a second processed product by drawing a portion of the first processed product other than the wrinkled part formed in the opening of the first processed product again, and a step of finally cutting off the wrinkled part. A method of manufacturing a magnetic shield case, comprising: 3. A first material and a residual magnetism B more than the first material.
a first drawing step for obtaining a first processed product by drawing a clad material with a second material having a large r and a small magnetic permeability μ into a cup shape so that the first material is on the inside. A second drawing step of forming a second processed product by drawing again a portion other than the wrinkles generated in the opening of the first processed product by the first drawing process, and finally cutting out the wrinkles. A method of manufacturing a magnetic shield case, comprising: 4. After the second drawing step, the part other than the wrinkles generated in the drawing step immediately before the second drawing step is drawn again.
Alternatively, the method for manufacturing a magnetic shield case according to claim 2 or 3, comprising a plurality of drawing steps.