JPS6373861A - Manufacture of magnet circuit - Google Patents

Abstract

PURPOSE:To simplify an assembly operation and enable manufacturing readily a magnetic circuit with good magnetic characteristics by magnetizing magnet assemblies by the use of U-shaped magnetizing yokes and by causing said magnet assemblies to slide into an E-shaped yoke and then fixing said assemblies thereto. CONSTITUTION:An unmagnetized permanent magnet 10 is fatened to an auxiliary yoke plate 12 to form a magnet assembly 14. Said magnet assembly 14 is placed upon a spacer 16 and received within a U-shaped magnetizing yoke 18 to be subjected to magnetization. Then, as the magnet assembly 14 and spacer 16 are received in the U-shaped magnetizing yoke 18, an E-shaped yoke 24 having spaces between opposite faces being respectively almost equal to a space between opposite faces of said U-shaped magnetizing yoke 18 is arranged so as to adjoin said magnetizing yoke 18. After that, said magnet assemblies 14 are caused to slide one by one or at one time to be forwarded into the E-shaped yoke 24, respective auxiliary yoke plates 12 are fixed to the E- shaped yoke 24, and then the spacer 16 is removed from said yoke 24.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a magnetic circuit having an E-shaped yoke used in a head positioning system of a magnetic disk drive, and more specifically, to This relates to a method of manufacturing a magnetic circuit in which an auxiliary yoke is temporarily fixed to a U-shaped front τ(l) yoke, magnetized, and a permanent magnet is sent into an adjacent E-shaped yoke.

[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 arranged in a gap of a magnetic circuit including a permanent magnet is often used.

The magnetic circuit used in this type of application consists of permanent magnets fixed to the inside of both side yoke plates of an E-type yoke, and the sides of the magnets facing the center ball have the same polarity, so that the center ball is connected to the common part. There is a configuration that does this.

To manufacture such a magnetic circuit, there are two methods: one is to attach a permanent magnet that has been magnetized singly in advance to an E-type yoke, and the other is to magnetize each permanent magnet while temporarily fixing it to the side yoke.
There is a method of assembling it into a type yoke, or a method of fixing an unmagnetized permanent magnet to an E-type yoke, and then inserting an N coil and magnetizing it.

[Problems to be solved by the invention] However, in the method of assembling after magnetization, the magnet operating point (permeance) decreases due to the self-demagnetizing effect, making it impossible to fully demonstrate the inherent characteristics of a permanent magnet. Can not. In addition, since a strong attractive force acts between the magnet and the yoke, there is a risk that the magnet will collide with the yoke and cause cracks or chips, making work extremely difficult. Assembling it requires great care and considerable skill.

In a magnetic circuit with an E-type yoke, the problem is that the opposing surfaces of the permanent magnet have the same polarity as described above, and it is not possible to simply attach it to a magnetizer and magnetize it.
For this reason, a method was devised in which an E-shaped yoke was assembled using unmagnetized permanent magnets, a U-shaped and ■-shaped combined coil with a special structure was attached around the permanent magnet, and the coils were magnetized by energizing them. (Refer to Japanese Unexamined Patent Publication No. 189608/1989), this method does not lower the magnet operating point because it is magnetized after assembling the magnetic circuit. Workability is poor because magnetization must be prepared each time.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method that eliminates the drawbacks of the prior art as described above and allows easy fabrication of a magnetic circuit with good assembly workability and good magnetic properties.

[Means for Solving the Problems] The present invention, which can achieve the above objects, is a method for manufacturing a magnetic circuit that is assembled through the following four steps.

a. First step of temporarily fixing unmagnetized permanent magnets on the auxiliary yoke to form a magnet assembly; b. Second step of stacking the magnet assembly on a spacer and storing it in the U-shaped magnetizing yoke and magnetizing it. step c, [a step of arranging an E-shaped yoke adjacent to the U-shaped magnetizing yoke with a spacing approximately equal to the spacing between opposing surfaces of the U-shaped magnetizing yoke with the stone assembly and spacer housed; Step 3, d. Slide the single stone assembly one by one or simultaneously into the E-shaped yoke, fix each auxiliary yoke plate to the E-shaped yoke, and remove the mesh spacers; the fourth step.

[Function] Since the present invention involves magnetization of a simple U-shaped magnetic circuit, general magnetization methods such as electromagnet or pulse magnetization can be employed. Moreover, since the permanent magnet does not separate from the yoke because the only thing left to do is to slide the magnet assembly into the adjacent E-shaped yoke and carry it in. As a result, even though it is assembled after magnetization, the magnet/operating point is lowered due to the self-1ffl&f action. First, it is possible to exhibit good magnetic properties similar to those obtained by magnetization after assembly.

In addition, in the present invention, since the non-attached (n) permanent magnets are fixed to the yoke plate, the positioning and fixing work is quite easy.
Even unskilled workers can perform assembly work with high purity. Since the magnet assembly and the E-type yoke can be easily fixed by screwing or the like between the auxiliary yoke plate and the E-type yoke, positioning and assembly are easy. Even if the characteristics of one of the permanent magnets used are bad and the air gap magnetic flux density becomes defective, all you need to do is replace that magnet assembly.
The E-type yoke, the other permanent magnet, etc. are not wasted, and the yield is improved.

[Example] FIG. 1 is a process explanatory diagram showing an example of a method for manufacturing a magnetic circuit according to the present invention.

First, as shown in FIG. 1A, an unmagnetized permanent magnet IO having a desired shape is positioned and bonded to the temporary auxiliary yoke 12, thereby manufacturing the magnet assembly 14.

Next, as shown in FIG. B, the magnet assembly 14 is stacked on the magnetic or non-magnetic spacer 16. Here, the height of the spacer 16 is selected so that when the spacer 16 and the magnet assembly 14 are stacked on top of each other, the height is approximately equal to the distance between the facing surfaces of the U-shaped magnetizing yoke 18. The magnet assembly 14 and spacer 16 stacked in this manner are housed in the U-shaped foundation yoke 18, and magnetized by magnetizing electromagnets 20 located on both the upper and lower sides.

As shown in Figure C, two sets of U-shaped magnetizing yokes 18 containing the magnet assembly 14 and the spacer 16 are arranged symmetrically (that is, so that the spacer 16 is located on the inside).
&I] together constitute a pseudo circuit 22. On the other hand, the E-shaped yoke 24 having a distance approximately equal to the distance between the facing surfaces of the N-yoke 18 (the distance between the side yoke portion and the center ball) is arranged adjacent to the pseudo circuit 22 described above. .

Thereafter, the two magnet assemblies 14 and the two spacers 16 in the pseudo circuit 22 are slid 1 Mi at a time or 2 Mi at the same time and sent into the E-type yoke 24.

Then, each auxiliary yoke plate 14 is positioned and screwed onto the side yoke portion of the E-type yoke 24, and then the spacer 16
remove. Therefore, although not shown in the drawings, screw insertion holes are drilled in advance at predetermined positions in the side yoke portions of the auxiliary yoke plate 12 and the E-type yoke. A magnetic circuit with a mold yoke is manufactured.

Although one embodiment of the present invention has been described in detail above, it goes without saying that the present invention is not limited to only such a configuration. For example, the shape of the permanent magnet used was a rectangular parallelepiped in the embodiment shown in FIG. The plate 12 may have a trapezoidal shape.

Further, in the above embodiment, magnetization is performed using an electromagnet, but in industry, pulse magnetization as shown in FIG. 3 is more common. In this case, the U-shaped magnetizing yoke 18 containing the magnet assembly 14 and the spacer 16 is installed in the solenoid coil 30, and the high-voltage charge charged to the capacitor by the magnetizing device 32 is instantly discharged. In this method, a strong magnetic field is created within the solenoid coil 30 using a large current to perform magnetization. This pulse magnetization has advantages such as generating a thick magnetic field in a very short time and being easy to handle compared to magnetization using an electromagnet.

In the above embodiment, the E-type yoke 24 is an integral structure,
Although this structure is more desirable from the point of view of the magnetic circuit, the E-type yoke may be constructed by a combination of side yoke portions, center pole portions, and yoke plates connecting them.

[Effects of the Invention] As described above, the present invention is a method of magnetizing a magnet assembly using a U-shaped magnetizing yoke and sliding and fixing it on an E-shaped yoke. The magnet assembly can slide smoothly using the smooth surface of the auxiliary yoke plate, and the permanent magnet does not separate from the yoke, making it easy to attach (even though it is 11e9). There is no lowering of the magnet operating point due to the self-17Hff effect, and after assembly, it is possible to exhibit excellent magnetic properties similar to those of t'f F.

In addition, in the present invention, since the magnet assembly is assembled using unmagnetized permanent magnets, even an unskilled person can easily and accurately fix the magnet assembly, and the auxiliary yoke plate and the
Since it can be fixed to the mold yoke with screws, it can also be fixed precisely and firmly. Even if it is found that a single-stone assembly with poor characteristics is included after assembly, only that assembly can be replaced, which has the advantage of improving yield.

[Brief explanation of the drawing]

FIG. 1 is a process explanatory diagram of a method for manufacturing a magnetic circuit according to the present invention, FIG. 2 is an explanatory diagram of another magnet assembly used in the present invention, and FIG. 3 is an explanatory diagram of pulse magnetization. 10... Permanent magnet, 12... Auxiliary yoke plate, 14.
・Magnet assembly, 16... Spacer, 18... U-shaped magnetizing yoke, 20... Attachment capacitor (d stone, 22...
・1 pseudo circuit, 24...E type yoke. Patent applicant: Fuji Electrochemical Co., Ltd. Agent: Shigeru Miyoshi Figure 1B Figure 2Figure 3

Claims (1)

[Claims] 1. Fix an unmagnetized permanent magnet to an auxiliary yoke plate to form a magnet assembly, stack the magnet assembly on a spacer, house it in a U-shaped magnetizing yoke, and magnetize it to create a U-shaped magnetization. An E-shaped yoke is placed adjacent to the yoke with a spacing approximately equal to the spacing between opposing surfaces of the U-shaped magnetizing yoke, and the magnet assembly is slid and fed into the E-shaped yoke to form each auxiliary yoke plate into an E-shaped yoke. A method for manufacturing a magnetic circuit, characterized by removing a spacer after fixing it to a yoke.