JPH0262010A - Manufacture of magnetic circuit and jig therefor - Google Patents

Abstract

PURPOSE:To easily obtain a magnetic circuit whose assembly operation property and magnetic characteristic are good and which can be made small-sized by a method wherein a magnetizing coil is inserted into a gap of two sets of magnetic assemblies attached inside a magnetizing assembly jig and a pulse current is applied. CONSTITUTION:Two unmagnetized permanent magnets 22 are arranged on a yoke sheet 21 and bonded; a magnet assembly 23 is formed. Two sets of the magnet assembly 23 are attached inside a magnetizing assembly jig 24 of a closed magnetic circuit structure and are held in such a way that the magnets 22 are faced mutually via a gap. A magnetizing coil 31 having a wire material wound into 8-shaped so as to imitate a whole peripheral shape of a side face of the two juxtaposed magnets 22 is inserted into a gap of the faced magnets; the four magnets 22 are pulse-magnetized simultaneously; magnetic charge retention sheets 37 are inserted and attracted for the assembly 23 so as to bridge both magnets 22 of the assembly 23. A part between the yoke sheets 21 is coupled by using a coupling member. Thereby, it is possible to easily obtain a magnetic circuit whose assembly operation property and magnetic characteristic are good and which can be made small-sized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a yoke plate with two permanent magnets arranged in parallel,
The present invention relates to a method for manufacturing a magnetic circuit in which permanent magnets are arranged to face each other at intervals, and a magnetization assembly jig used therein. Although not particularly limited, the present invention relates to a technique suitable for manufacturing a magnetic circuit of a voice coil motor used, for example, in a head positioning system of a magnetic disk drive.

[Prior Art] As an actuator for a head positioning system in a magnetic disk device, a voice coil motor type in which a moving coil is disposed in a gap in a magnetic circuit including a permanent magnet is often used.

In the conventional technology, for example, as shown in FIG. 6A, unmagnetized permanent magnets 11 are positioned and adhered to the opposing surfaces of the U-shaped yoke 10, and then held between magnetizing electromagnets 12 to attach them. After magnetizing it or installing it in a solenoid-shaped magnetizing coil 13 as shown in Figure B and magnetizing it by passing a pulse current, two sets of U-shaped yokes lO are attached as shown in Figure C. They were assembled with butt-edges so that their tip surfaces were in contact.

Although this method of assembling by magnetizing after bonding can produce extremely good magnetic properties, it is necessary to use a U-shaped yoke, which usually requires finishing after hot forging. Because it is manufactured by performing the following steps, it has a fairly high tetravalent value.

Another method of configuring a similar magnetic circuit is to connect two permanent magnets 11 to a common auxiliary yoke plate 1 as shown in FIG. 7A.
4 is positioned and glued to form a magnet assembly 15. Next, as shown in FIG. Another method is to attach it and assemble a magnetic circuit.

[Problems to be Solved by the Invention] A structure using a flat main yoke plate 17 as shown in FIG. 7 has a simple yoke structure and can be made at low cost. However, in the magnet assembly 15 in which the two permanent magnets 11 are bonded to the auxiliary yoke plate 14, it is difficult to magnetize the two permanent magnets with different poles in that state. After magnetizing, it must be positioned and bonded to the auxiliary yoke plate 14 as shown in FIG.

However, with the method of assembling after adhesion, the magnet operating point (permeance) decreases due to the self-demagnetizing effect of the permanent magnet.
A drawback arises in that the inherent characteristics of permanent magnets cannot be fully exhibited.

In addition, since the permanent magnets are bonded together after magnetization, a strong attractive force acts between the permanent magnets, which not only makes it difficult to position the two permanent magnets, but also causes the permanent magnets to collide with each other, resulting in cracks, chips, etc. This makes workability extremely poor, and assembly requires great care and considerable skill.

In order to solve these technical problems, we have developed a magnet assembly in which - unmagnetized permanent magnets are glued to one auxiliary yoke plate, and two magnet assemblies are housed in a U-shaped magnetizing yoke. A method has been proposed in which two sets of magnets are magnetized, then a square-shaped main yoke assembly is placed adjacent to the two sets, and the four magnet assemblies are simultaneously slid and fed into the main yoke assembly. (Refer to Japanese Unexamined Patent Publication No. 185549/1983) Although this method can produce a magnetic circuit with good magnetic properties,
If the shape of the magnetizing yoke and the dimensions of the main yoke assembly do not exactly match, it will be difficult to slide the magnet assembly into the main yoke assembly. Furthermore, since an auxiliary yoke plate is required, the number of parts increases accordingly, and the height cannot be reduced.

The purpose of the present invention is to eliminate the drawbacks of the prior art as described above,
It is an object of the present invention to provide a method for easily manufacturing a magnetic circuit that has good assembly workability and magnetic properties and can be miniaturized, and a jig for use therein.

[Means for Solving the Problems] The present invention, which can achieve the above object, manufactures a magnetic circuit in which two sets of yoke plates each having two permanent magnets arranged side by side are arranged so that the permanent magnets face each other. In the method, the following (
This is a method for manufacturing a magnetic circuit having five steps al to (el).

+a+yoke The first step of temporarily gluing two unmagnetized permanent magnets side by side to form a magnet assembly; (b) Attach the two magnet assemblies in a magnetization assembly jig with a closed magnetic path structure; The second step is to hold the permanent magnets so that they face each other with a gap in between; The third step involves inserting a magnetizing coil with a wire wound into a mold and simultaneously pulse-magnetizing four permanent magnets.
The fourth step is to insert a magnetic charge holding plate into each magnet assembly so as to bridge both permanent magnets of the fdl m stone assembly and attract it.
Step; te1 Fifth step of connecting both yoke plates with a connecting member.

Here, the timing of insertion of the magnetic charge retaining plate and removal of the magnetizing coil can be variously changed. For example, in the fourth step, the magnetic charge retaining plate may be inserted into the gap between the permanent magnet and the magnetized coil, and then the magnetizing coil may be removed, or the magnetic charge retaining plate may be left in that state after the magnetizing coil is removed. may be adsorbed.

The following jigs are used for magnetizing and assembling such magnetic circuits. For example, a lower magnetizing yoke plate, a guide column and a long screw erected on both sides of the lower magnetizing yoke plate, and an upper part facing the lower magnetizing yoke plate and fitting into the guide column and the long screw. It is equipped with a magnetizing yoke plate, a nut for fixing the upper magnetizing yoke plate to a long screw, and a magnetizing coil that can be installed between the upper and lower magnetizing yoke plates. The structure allows magnet assemblies to be attached to the bottom surface of each magnetic yoke plate.

Here, the magnetizing coil uses a non-magnetic substrate having a counterbore, and a 6n core is provided in the counterbore at a position corresponding to the two permanent magnets of the magnet assembly, and the entire circumference of the side surface is shaped. It is preferable to form an integrated structure by winding the wire material once or multiple times in a figure-eight shape and pouring resin into it.

[Operation] When a magnetizing coil is inserted into the gap between the 2m magnetic assemblies installed in the magnetization assembly jig and a pulse current is supplied, a magnetic field is generated on both sides of the wire forming the figure 8 shape. The two permanent magnets arranged in parallel on the yoke plate can be simultaneously magnetized with different polarities. The magnetization assembly jig has a closed magnetic circuit structure, and in order not to increase the magnetic resistance of the magnetic circuit, the air gap between the opposing permanent magnets is maintained as it was during magnetization, so that the self-M (magnetic operating point due to ft action) of the permanent magnet is prevent the decline of

Subsequently, the two magnet assemblies become separate magnetic circuits by attracting a magnetic charge holding plate so as to bridge the two permanent magnets on the yoke plate that have been magnetized. Therefore, in the assembly process of joining two sets of magnet assemblies and the connecting member,
Even if the gap between the opposed permanent magnets becomes larger, the magnet operating point does not decrease due to self-demagnetization.

In particular, if the magnetization assembly jig has a structure in which guide members are installed upright on both sides of the lower magnetization yoke, and a portion is provided in the upper magnetization yoke that is slidably fitted to the guide members, a closed magnetic path can be created by them. With this structure, both magnetized yoke plates are positioned, and the permanent magnets attached to the yoke plates are inevitably positioned in the horizontal direction.

[Example] FIG. 1 is an exploded perspective view showing the components of a magnetization assembly jig and a magnetic circuit according to the present invention, and FIG. 2C is an explanatory diagram showing the manufacturing process thereof. In the present invention, first, two unmagnetized permanent magnets 22 are positioned and bonded to the yoke plate 21 to form a magnet assembly 23. Two sets of these magnet assemblies 23 are installed in a magnetization assembly jig 24 having a closed magnetic path structure, and the permanent magnets 22
They are held so that they face each other with a gap in between.

The magnetization assembly jig 24 is provided on the base member 25, and includes a lower magnetization yoke plate 26a, and guide columns 27 and long screws 2 that are respectively erected on both sides of the lower magnetization yoke plate 26a.
8, an upper magnetizing yoke plate 26b facing the lower magnetizing yoke plate 26a and having a through hole that slidably fits into the guide column 27 and the long screw 28; It is provided with a nut 29 for fixing to 28. The 2 m magnet assemblies 23 are attached to the lower and upper magnetized yoke plates 26a and 26b, respectively, by screws 30 (see FIG. 2C).

Next, a magnetizing coil 31 is placed in the gap between the opposing permanent magnets 22.
is inserted, and the four permanent magnets 22 are simultaneously pulse magnetized.

As shown in FIG. 1, the magnetizing coil 31 consists of a wire 32 wound in a figure-eight shape shaped like the entire circumference of the sides of two permanent magnets arranged side by side, mounted on a non-magnetic substrate 33, and terminals attached at both ends. 34
was formed. This magnetizing coil 31 is attached to a spacer 35 provided before and after the base member 25 using a bridging screw 36.
Fix it with.

Once the magnetization is completed, the magnetic charge retaining plate 37 is inserted into the gap between the permanent magnet 22 and the magnetized coil 31 so as to bridge the gap between the adjacent permanent magnets (see Fig. 2C). Remove the inserted magnetizing coil 31.

After that, the side plate 38 is inserted as a coupling member between both yoke plates 21 and the magnetic charge retaining plate 37 is removed (second
(see Figure C), and re-magnetize the yoke plate 21 with the yoke plate 26a.
, 26b.

A magnetization assembly jig 24 incorporating two sets of magnet assemblies 23 includes lower and upper magnetization yoke plates 26a.

26'b and the guide column 28 are made of magnetic material and have a closed magnetic circuit structure, and in order not to increase the magnetic resistance of the magnetic circuit, the self-demagnetizing effect of the permanent magnets is maintained by keeping the air gap between the opposing permanent magnets as they were when magnetized. This prevents the magnet operating point from decreasing due to The through hole of the guide column provided in the upper magnetized yoke plate 26b has a minute gap (approximately 1O2) with respect to the guide column 27.
μm), and the re-magnetized yoke plate 26a,
This serves as a positioning hole for determining the relative position of the magnet 26b, which inevitably positions the permanent magnet 22, and also allows the upper magnetizing yoke plate 26b to smoothly slide up and down with respect to the guide column 27. .

Next, when a pulse current is supplied to the wire 32 forming the figure 8 shape, the direction in which the magnetic field is generated differs between the left and right loops, which face the permanent magnet, so the yoke plate 21
The two permanent magnets 22 arranged in parallel can be magnetized so that their polarities are opposite.

The magnetic charge retaining plate 37, which is attracted between the permanent magnets adjacent to each other so that [ljL], thereby makes the magnet assemblies 23 of 2 & [l separate magnetic circuits, and therefore the subsequent yoke plate 21 and side plate 38 In the assembling process for coupling the magnets, the magnet assembly functions to prevent the magnet operating point from decreasing due to the self-M1 action even if the distance between the magnet assemblies 23 is increased.

Next, FIGS. 3A-3D show another embodiment of the present invention.

In this embodiment, a plurality of wire rods 40 are used so as to be more strongly magnetized.

Here, the magnetizing coil 41 uses a non-magnetic substrate 43 having a counterbore 42, and two parts of the magnet assembly in the counterbore 42.
It has a structure in which a magnetic core 44 is provided at a position corresponding to each permanent magnet, a wire 40 is wound multiple times in a figure-eight shape that follows the entire circumference of the side surface, and resin is poured into the magnetic core 44 to form an integrated structure.

Note that reference numeral 34 indicates a terminal, and the magnetizing coil 41 described above is inserted into the gap between the magnet assemblies 32, and magnetization is performed by passing a pulse current (see A in the same figure).

Next, as shown in FIG. B, a magnetic charge holding plate 37 is inserted into the gap between the magnetized permanent magnet 22 and the magnetized coil 41,
2, the magnetizing coil 41 is removed as shown in FIG. 2C, the side plate 35 is inserted between the yoke plates 21, and the upper magnetizing yoke plate 26b is lowered. And like the same diagram 2
After configuring the magnetic circuit 50 by combining the two yoke plates 21 and the side plates 38, the magnetic charge holding plate 37 is removed, and the yoke plate 21
The magnetized yoke plate 26a.

Remove it from 26b.

FIG. 5 shows another embodiment of the invention.

This is the case where the gap between the permanent magnets 22 is small and the end shape of the coupling member 51 that couples the two yoke plates 21 is fitted into the yoke plate 21. In the figure A, magnetization is performed by supplying a pulse current to the magnetizing coil 31, and when the magnetization is completed, the magnetizing coil is removed and the magnetic charge holding plate 37 is removed as shown in the figure B.
Create a gap in which the magnetic charge retaining plate 37 is attracted to the permanent magnet 22. Next, as shown in FIG. After raising the fM1 yoke 26b and fitting the coupling member 51 to the yoke plate 21, the upper magnetized yoke plate 26b is lowered to form a magnetic circuit 50 as shown in the figure. Magnetic charge holding plate 37
Remove the yoke plate 2 from the re-magnetized yoke plates 26a and 26b.
Remove 1.

[Effects of the Invention] In the present invention, since the permanent magnet is bonded to the yoke plate in an unmagnetized state, the permanent magnet can be easily positioned and the workability is extremely good. In addition, the magnet assembly becomes part of the magnetic circuit in the magnetization assembly jig when it is stored in the magnetization assembly jig, and there is no self-demagnetizing effect of the permanent magnet after magnetization, and the magnet assembly faces each other during assembly after magnetization. Even in the process where the gap between magnet assemblies must be increased, the magnetic circuit is closed for each magnet assembly by the magnetic charge retaining plate, so the permanent magnet's self-$1uf
There is no f effect, so it is possible to fully bring out the inherent characteristics of permanent magnets and easily manufacture a good magnetic circuit.

In addition, in the present invention, since the shape of the magnetizing coil is made into a figure 8 shape, four permanent magnets can be simultaneously magnetized so that the polarities of the two permanent magnets temporarily arranged in parallel with the yoke are different. The time required for the magnetization process can be shortened. In particular, when a magnetizing coil in which a wire is wound multiple times is used, good magnetization can be achieved with a small pulse current proportional to the increase in the number of windings.

Furthermore, in the present invention, the yoke plate is not U-shaped like the conventional one (it is a flat plate), so the cost of the yoke can be reduced.Also, since no auxiliary yoke is required, the number of parts can be kept to a minimum. The height dimension can be reduced. Due to these various effects, the present invention makes it possible to manufacture a high-performance magnetic circuit with good workability and economy.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing a magnetization assembly jig for a magnetic circuit and the components of the magnetic circuit according to the present invention, FIGS. 2A-C are explanatory diagrams showing the manufacturing process using the same, and FIG. 3A -D is a manufacturing process explanatory diagram showing another embodiment of the present invention, FIG. 4 is an exploded perspective view showing an example of a magnetizing coil used therein, and FIGS. 5A-D
FIG. 3 is a process explanatory diagram showing another embodiment of the present invention. In addition, FIGS. 6A to 6C are explanatory diagrams showing an example of the prior art, and FIGS.
Figures A and B are explanatory diagrams showing other examples of the prior art. 2I...Yoke plate, 22...Permanent magnet, 23...
Magnet assembly, 24... Magnetizing assembly jig, 26a... Lower magnetizing yoke plate, 26b... Upper magnetizing yoke plate, 27
...Guide column, 28...Long screw, 29...Nut, 31...Magnetizing coil, 32...Wire, 37...
Magnetic charge holding plate, 38...side plate. Patent Applicant: Fuji Electrochemical Co., Ltd. Representative: Shigeru Minoru Figure 6b Figure 6b

Claims (5)

[Claims] 1. In a method for manufacturing a magnetic circuit in which two sets of yoke plates each having two permanent magnets arranged side by side are arranged so that the permanent magnets face each other, (a) two sets of unmagnetized permanent magnets are placed on the yoke plate; First step of arranging and gluing magnets to form a magnet assembly; (b) Two sets of magnet assemblies are installed in a magnetization assembly jig with a closed magnetic circuit structure, and the permanent magnets face each other with an air gap between them. (c) Magnetization in which a wire is wound in a figure-eight shape in the shape of the entire circumference of the side surfaces of two permanent magnets arranged in parallel in the gap between opposing permanent magnets; The third step involves inserting a coil and simultaneously pulse-magnetizing four permanent magnets.
(d) A fourth step in which a magnetic charge retaining plate is inserted and attracted to each magnet assembly so as to bridge both permanent magnets of the magnet assembly; (e) A connecting member is used to connect both yoke plates. A method for manufacturing a magnetic circuit, comprising the following five steps: a fifth step of bonding; 2. 2. The manufacturing method according to claim 1, wherein in the fourth step, after inserting a magnetic charge retaining plate into the gap between the permanent magnet and the magnetizing coil, the magnetizing coil is removed. 3. 2. The manufacturing method according to claim 1, wherein in the fourth step, after the magnetizing coil is removed, a magnetic charge holding plate is attracted to each of the permanent magnets of both magnet assemblies. 4. a lower magnetized yoke plate, a guide post and a long screw erected on both sides of the lower magnetized yoke plate, and an upper magnetized part that faces the lower magnetized yoke plate and fits into the guide post and the long screw. It is equipped with a yoke plate, a nut for fixing the upper magnetized yoke plate to a long screw, and a magnetizing coil that can be installed between the upper and lower magnetized yoke plates. A magnetization assembly jig that allows magnet assemblies to be attached to the bottom surface of the yoke plate. 5. The magnetizing coil uses a non-magnetic substrate with a counterbore, and a magnetic core is provided in the counterbore at a position corresponding to the two permanent magnets of the magnet assembly. 5. The jig according to claim 4, wherein the jig has a structure in which the wire material is wound one or more times in a letter shape, and resin is poured into the jig.