JPS61151876A - Spindle of magnetic disk device - Google Patents

Abstract

PURPOSE:To obtain a magnetic fluid seal with which a magnetic fluid is easily injected by drilling a pierced hole having the same diameter as a magnetic fluid enclosing part of a hub serving as the revolving part of a spindle and then injecting the magnetic fluid through the pierced hole by an injector. CONSTITUTION:A holder 9 sealed up by an 0 ring 8 is attached to a housing 7 forming a fixing part of a spindle 1 to which a magnetic disk 2 is mounted. The housing 7 includes a magnet 10 and a yoke 11 adhered respectively. At a revolving part a bearing 12 is put into a shaft 13 and a hub 14 is fixed with pressure. Then a magnetic fluid is filled into a gap 15 formed between the shaft 13 and the yoke 11 and a magnetic circuit is formed among the magnet 10, the yoke 11 and the shaft 13. A pierced hole 16 is formed at the measurement position of the hub 14 corresponding to the gap 15 serving as an injecting part of the magnetic fluid. Then the magnetic fluid is injected through the hole 16 by an injector, etc. Here the incoming/outgoing of air can be prevented at the part of the yoke 11.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a magnetic disk device, and in particular, it is possible to easily and reliably inject a magnetic fluid into a magnetic fluid seal to isolate it from the outside air, and to provide a stable sealing effect for a long period of time. The present invention relates to a magnetic fluid seal for a magnetic disk device that is suitable for ensuring.

[Background of the invention]

In magnetic disk drives, a spindle carrying a magnetic disk and an actuator equipped with a magnetic head are built into a base, and the rotating part of the spindle is installed in a sealed chamber isolated from outside air to prevent dust from entering into the spindle. A non-contact magnetic fluid seal is used between the fixed part and the fixed part 111.

Magnetic fluid seals have the advantage of being able to achieve complete sealing without contact, but in general, magnetic fluid seals are manufactured by injecting magnetic fluid into the area H between the yoke and magnet before assembly. The structure is such that the magnetic fluid is sealed in the gap between the shaft and the fixed part when the shaft is touched, so when the shaft is touched, it adheres to other parts and is scattered by the rotation of the spindle, especially with the magnetic spatula). If the particles are scattered onto the surface of a magnetic disk, which is a medium used for recording and reproduction, there is a risk of damage to the magnetic head and the magnetic disk.

In addition, if the magnetic fluid is used for a long time, it will lose weight due to evaporation, etc., and the expected sealing effect will no longer be maintained, making it necessary to replenish new magnetic fluid. A problem occurs in which injection cannot be made into the area.

Regarding magnetic fluid seals for conventional magnetic disk devices, see Utility Model Application No. 58-163048 and Utility Model Application No. 59-25.
No. 691 can be found, but although this is an effective means for preventing leakage of magnetic fluid from a magnetic fluid sealing portion, there is no mention of injection and replenishment of magnetic fluid.

[Purpose of the invention]

The object of the present invention is to provide a VC when replenishing the spindle during assembly and when it becomes necessary to replenish after long-term use.

It is an object of the present invention to provide a magnetic fluid seal that allows easy injection of magnetic fluid from the outside.

Another object of the present invention is to provide a magnetic fluid seal that can prevent magnetic fluid from adhering to unnecessary parts after assembly.

[Summary of the invention]

In order to achieve the above object, the present invention provides a yoke part of a magnetic fluid seal in a fixed part of a spindle, and a hub k which is a rotating part.
li! A magnetic fluid is sealed in the gap between the attached shaft and
The magnetic fluid can be easily injected by drilling one or more through holes in the same diameter as the magnetic fluid enclosing portion of the hub, and creating a structure in which the magnetic fluid can be injected through the through holes with a syringe with a needle attached. .

[Actual IM example of invention]

An embodiment of the present invention will be described below.

As shown in Fig. 2, the magnetic disk device has a spindle 1.
A 1C magnetic disk 2 is mounted with a specific gap, and a head 3 is installed in an actuator 4, each with a pace 5.
It is placed in a room that is sealed off from the outside air by a cover 6.

As a means of sealing, we use an elastic gasket C (not shown in this figure), but since the above method cannot be used for spindles with rotating parts, we use a magnetic seal as shown in Figure 1. Adopts a fluid seal.

A holder 9 sealed and incorporated with an O-ring 8 is attached to a housing 7 that forms a fixed part of the spindle 1, and a magnet 10. A yoke 11 is bonded to the inside with an inner wall 17.

Further, in the rotating part, a bearing 12 is mounted on a shaft 13 and fixed to a hub 14 by press fitting.

By filling the gap 15 between the shaft 13 and the yoke 11 with magnetic fluid, the magnet 10. Yoke 11° Shaft 1
5, a magnetic circuit is formed between them. A through hole 16 is drilled at the dimensional position of the hub 14 that is in the magnetic fluid injection part, that is, the gap 15, and the magnetic fluid is injected through the through hole 16 with a syringe or the like. can be prevented.

In other words, the base 5 and the cover 6 are shielded from the outside air.

〔Effect of the invention〕

According to the present invention, since the magnetic fluid can be injected after the spindle is assembled, initial injection of the magnetic fluid and replenishment by evaporation etc. can be easily performed, and it is possible to prevent the magnetic fluid from adhering to parts where it is not required. It has the effect of saying that it can be done.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of a spindle according to an embodiment of the present invention;
FIG. 2 is a schematic vertical sectional view of the magnetic disk device. 10...Magnet, 11...Yoke, 13
... shaft, 14 ... hub, 15 ... gap,
16...Through hole.

Claims (1)

[Claims] 1. A base with a sealed chamber isolated from outside air,
In a spindle of a magnetic disk device, a magnetic fluid seal is provided in a gap between a shaft mounted on the base, fixed to the hub, and rotating together, and a fixed part, and the sealed chamber can be isolated from the outside air by the magnetic fluid seal. 1. A spindle for a magnetic disk device, characterized in that a hub is provided with at least one through hole for injecting magnetic fluid at an annular dimensional position where .