JP3326882B2 - Magnetizing device for FDD spindle motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetizing device for a spindle motor for a floppy disk drive.

[0002]

2. Description of the Related Art Conventionally, a magnetizing device of this type has a yoke wire for magnetizing a main pole provided at a pole portion of a magnetizing yoke for magnetizing a main magnetic pole, and a PG magnetizing magnet provided in the same yoke. By using a magnetic yoke line and sequentially switching and magnetizing the two power supplies connected to each yoke line, a magnetizing pattern for PG is magnetized in a part of the magnetic poles. Was configured to.

[0003]

However, in the above-mentioned conventional magnetizing device, the routing of the yoke wire provided on the magnetizing yoke is complicated, and two magnets are required to magnetize one magnet. Since two magnetizations by a power source are required, when magnetization of a high coercivity material magnet or magnetization in a short cycle time is required, the magnetization stability of the magnetizing device and the magnetization yoke are required. There was a problem that its own durability was impaired.

The present invention solves such a conventional problem. In particular, the magnetizing stability and the magnetizing yoke itself against the magnetizing of the high coercive force material magnet and the magnetizing for a short cycle time are considered. It is an object of the present invention to provide an excellent magnetizing device capable of magnetizing without deteriorating the durability of the magnet.

[0005]

According to the present invention, in order to achieve the above object, a groove is provided in a tooth pole portion of a magnetized yoke main body, and a back yoke portion has the same phase position as the groove of the tooth pole portion. A non-uniform magnetic field in the gap with the back yoke formed by the tooth pole groove at the time of magnetization is provided, and the PG magnetization pattern is magnetized together with the main pole on the magnet in one operation. It is something to do.

[0006]

According to the present invention, the main pole and the magnetizing pattern for PG can be simultaneously and stably magnetized on the magnet without using complicated coil routing with a single power supply. It has the effect of. Further, since the cycle time can be shortened, the productivity can be improved, and since only one magnetizing power supply is required, the facility cost can be reduced.

[0007]

FIG. 1 is a view showing a main part of a magnetized yoke according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a main magnetic pole magnetizing pole for converging magnetic flux, and a yoke wire 2 is wound around the pole. Reference numeral 3 denotes a groove provided in a part of the tooth pole 1. Reference numeral 4 denotes a projection provided on the back yoke 5, the phase position of which is the same as that of the groove 3. Reference numeral 6 denotes a magnet to be magnetized, which is sandwiched between the tooth pole 1 and the back yoke 5. Reference numeral 7 denotes a resin mold such as an epoxy resin for fixing the yoke wire 2 to the tooth pole 1.

FIG. 2 is a diagram showing the magnetic properties of the neodymium-based sintered magnet 6 used in this embodiment. FIG. 3 is a diagram showing the magnetization characteristics of the magnet 6, in which the horizontal axis indicates the magnetization magnetic field and the vertical axis indicates the magnetization rate. Here, the magnetization rate is defined as 100% of the residual magnetic flux density of a so-called saturated magnetized magnet that is equal to or greater than the saturation magnetic field indicated by point A, and the residual magnetic flux density of the magnet magnetized by each magnetizing magnetic field is defined as a percentage. It is shown by.

Next, the operation of the above embodiment will be described.
In the above embodiment, an exciting current of 10.4 k as shown in FIG. 4 is applied to the yoke line 2 of FIG. 1 from a magnetizing power supply (not shown).
When A flows, a magnetomotive force is applied between the tooth pole 1 and the back yoke 5 to generate a magnetizing magnetic field of about 1500 kA / m as indicated by a point B in FIG. 3, and the magnet 6 has a magnetizing rate of about 97%. It is magnetized. However, the magnet 6 in contact with the groove 4 in FIG.
3, the magnetomotive force in the magnetizing direction 8 is lower than that in the portion without the groove, and the magnetic field generated in the magnetizing direction 8 in the periphery of the groove 3 by the protrusion 4 is reduced. A magnetizing magnetic field of 700 kA / m is applied to the magnet 6. Therefore, a magnetic pole having a portion that is locally magnetized at a weak magnetization rate of about 80% at the same phase position as the groove 4 can be formed in the magnet 6.

As described above, according to the above embodiment, by providing the projections 4 at the same phase position as the grooves 3 of the tooth poles 1 of the back yoke 5, the back yoke 5 formed by the grooves 3 when the magnet 6 is magnetized. Since the inhomogeneous magnetic field in the gap with the groove 3 is emphasized by the projection 4, the PG
There is an advantage that the magnetized pattern can be stably magnetized. Further, according to the above embodiment, since the yoke wire 2 is routed with a sufficient distance between the yoke wire 2 and the tooth pole 1, there is an effect that high durability can be obtained.

In the above embodiment, one groove 3 and one protrusion 4 are provided, but 2n grooves 3 and protrusions 4 may be provided. If the phase relationship between the groove 3 and the projection 4 is maintained, the shape and size can be appropriately selected depending on the PG used.

It is clear that the magnet 6 to be used is not limited to the neodymium magnet shown in the present embodiment, but may be a samarium-cobalt magnet, a ferrite magnet, or an alnico magnet. It can be applied to plastic magnets and rubber magnets.

[0013]

The present invention has the following effects as apparent from the above embodiment. 1. In order to magnetize the magnetized pattern for PG by one excitation,
The cycle time of magnetization can be shortened, and productivity can be improved and cost can be reduced. 2. Since there is no yoke wire for PG magnetization, magnetization can be performed with one power supply. 3. Since the conventional two magnetizing operations can be performed only once, the life of the magnetized yoke can be extended. 4. Since only one magnetizing power supply is required, facility costs can be reduced.

[Brief description of the drawings]

FIG. 1A is a front view showing a magnetized yoke portion of a magnetizing device according to an embodiment of the present invention. FIG. 1B is a side sectional view of FIG.

FIG. 2 is a list showing magnetic properties of a magnet according to one embodiment of the present invention.

FIG. 3 is a graph showing magnetization characteristics when a magnet is magnetized in one embodiment of the present invention.

FIG. 4 is a graph showing an exciting current waveform in one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tooth pole 2 Yoke line 3 Groove 4 Projection 5 Back yoke 6 Magnet 7 Resin mold 8 Magnetization direction A Saturation magnetization field B 1500 kA / m magnetization field C 700 kA / m magnetization field

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H02K 15/03 G11B 19/20 G11B 33/12 H01F 13/00 H02K 21/24

Claims (1)

(57) [Claims] 1. A phase between a magnetized yoke main body and a back yoke.
Magnetize with a magnet with a magnetized pattern for detection sandwiched
Device for FDD spindle motor for
Provided with one or 2n-number of grooves on the tooth pole portion of the serial magnetizing yoke body, by providing a projecting portion at the same phase position as the groove in the back yoke part, magnetizing phase position of the groove portion
A magnetizing device for an FDD spindle motor, wherein the ratio is locally reduced as compared with other portions .