JPH02121154A - Spindle hub for magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent the generation of the wear dust and the burrs when a magnetic disk is loaded by forming plural slits symmetrically to each other along the extending direction of a positioning part and around a rotary shaft and a screw groove into the positioning part and using a screw which is put into the screw groove. CONSTITUTION:A spindle hub 10 consists primarily of a disk-shaped bottom part 11 and a cylinder part 12 which is extended upward from the part 11. A rotary shaft 20 is put with press into a cylindrical opening formed at the center part of the hub 10. Thus the hub 10 is unified coaxially with the shaft 20. Then four slits 13-16 are formed symmetrically to each other along the axial line and around this axial line of the part 12 of the hub 10. In addition, a screw groove 17 is formed inside the part 12 and a screw 18 is put into the groove 17. When a magnetic disk is loaded, the outer diameter of the part 12 is contracted by removing the screw 18 out of the part 12. Thus it is possible to prevent the generation of the wear dust and the burrs when the magnetic disk is loaded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a spindle hub for a magnetic disk device, which is applied to a sealed magnetic disk device or the like.

(Prior Art) In a sealed magnetic disk device, a spindle hub is formed at the tip of a rotating shaft, and the rotating shaft is connected to multiple magnetic disks stacked around the spindle hub with a spacer interposed between them. Circular positioning is performed.

FIG. 5 is a plan view showing the mutual relationship between the rotating shaft, the spindle hub, and the magnetic disk, where 1 is the rotating shaft, 2 is the spindle hub, and 3 is the magnetic disk. A cylindrical spindle hub 2 is coaxially formed at the tip of a rotating shaft 1 that stands upright and is supported by horizontally arranged bearings. This spindle hub 2 has an outer diameter that is equal to the magnetic disk 3.
By setting it to a value slightly smaller than the inner diameter of
A magnetic disk 3 is positioned around a rotating shaft 1 with high precision. The operation of a magnetic disk requires extremely high rotational balance, and this rotational balance is governed by the positioning accuracy of the magnetic disk around the rotation axis. The positioning accuracy expressed by the difference between the outer diameter of the spindle hub and the inner diameter of the magnetic disk, that is, the gap between the spindle hub and the magnetic disk, is normally required to be as small as several tens of micrometers.

(Problems to be Solved by the Invention) As mentioned above, it is quite difficult to achieve a minute dimensional difference between the outer diameter of the spindle hub and the inner diameter of the magnetic disk with high precision due to manufacturing tolerances. If this dimensional difference is too large, positioning accuracy will decrease. Conversely, if the above-mentioned dimensional difference is insufficient, wear powder will be generated on the inner circumferential surface of the magnetic disk due to excessive friction with the outer circumferential surface of the spindle hub when the magnetic disk is mounted. It is difficult to completely remove this abrasion powder, especially in a sealed magnetic disk device.

Such residual wear particles may become caught between the surface of the magnetic disk and the core of the magnetic head during access, causing scratches on both sides, or the core may crash against the surface of the magnetic disk, making reading and writing impossible. A failure occurs.

Furthermore, if cracks occur on the inner circumferential surface of the magnetic disk or the outer circumferential surface of the spindle hub when they come into contact with each other, the magnetic disk and spindle hub may crash, making it difficult to attach and detach the magnetic disk thereafter.

In order to avoid the occurrence of abrasion powder and debris when the dimensional difference between the inner and outer diameters is insufficient, a notch is made in the axial direction on the outer circumferential surface of the spindle hub, as illustrated in the plan view of Fig. 6. Efforts have also been made to reduce the contact area with the inner peripheral surface of the magnetic disk by making it gear-shaped. However, even with such efforts, it is difficult to sufficiently prevent the occurrence of wear particles and debris.

(Means for Solving the Problems) A spindle hub of a magnetic disk device according to the present invention includes:
a disc-shaped bottom, a cylindrical cylindrical part extending upward from the bottom, and a plurality of slots formed along the axial direction of the cylindrical part and symmetrically around the axis;
The cylindrical part has a screw groove formed inside the cylindrical part and a screw that is screwed into the screw groove. The structure is designed to effectively prevent the generation of wear particles.

Hereinafter, the operation of the present invention will be explained in detail together with examples.

(Embodiment) FIGS. 1 and 2 are a plan view and a front view showing the structure of a spindle hub of a magnetic disk device according to an embodiment of the present invention in relation to a rotating shaft, and FIG. FIG. 1 is a sectional view taken along line A-A in FIG.

The spindle hub 10 is made of aluminum alloy or the like, and mainly includes a disc-shaped bottom 11 and a cylindrical cylindrical part 12 extending upward from the bottom 11. A rotary shaft 20 made of aluminum alloy or the like, like the spindle hub, is press-fitted into a circular opening formed in the center of the spindle hub lO by shrink fitting or the like. Due to this press-fitting, the spindle hub 10 and the rotating shaft 20 are negatively magnetized with their axes aligned, that is, coaxially.

Along the axial direction of the cylindrical portion 12 of the spindle hub 10 and symmetrically around this axis, four slots 13, 14,
15.16 are formed. Further, a threaded groove 17 is formed inside the cylindrical portion 12, and this threaded groove 17
A screw 18 is provided to be screwed into.

FIG. 4 is a cross-sectional view showing the main parts of a sealed magnetic disk device equipped with the spindle hub according to the embodiment of the present invention shown in FIGS. 1 to 3. FIG.

A rotating shaft 20 having a spindle hub 10 formed at its tip is held upright by a hair ring 31 horizontally fixed to a base plate 33 at the bottom. This sealed magnetic disk device is assembled with the cover 34 removed.

First, the screw 18 is removed from the screw groove 17 formed inside the cylindrical portion 12 of the spindle hub 10. In this state, spacers 41, 42, 43.
Magnetic disk 51.52.53.5 with 44 interposed
4 are sequentially stacked. During this stacking, since the screw 18 is removed, the slits 13 to 16 cause the cylindrical portion 12 to incline inward and contract slightly inward. Since the slots in the cylindrical portion 12 are formed symmetrically around its axis, substantially uniform contraction occurs around this axis. As mentioned above, a small amount of shrinkage equivalent to the minute difference between the inner diameter and outer diameter of several tens of micrometers is sufficient, and this reduces the amount of wear particles and particles from the inner peripheral surface of the magnetic disks being stacked. occurrence is almost completely prevented.

When the stacking of the magnetic disks is completed, the positioning section 12
A screw 18 is screwed into a screw groove 17 formed inside. By this screw engagement of the screws 18, the positioning portion 12, which had contracted slightly due to the formation of the slot, uniformly expands and returns to its original shape, achieving a predetermined positioning accuracy. When this stacking of magnetic disks is completed, the cover 34
is attached, and a sealed magnetic disk device is completed.

Although the example in which four slots are formed in the cylindrical positioning part has been described above, any number of slots can be formed symmetrically around the rotation axis.

(Effects of the Invention) As described above in detail, the spindle hub of the magnetic disk device according to the present invention has a plurality of slots formed symmetrically around the rotation axis along the extending direction of the positioning part. and a threaded groove formed inside this positioning part,
The spindle hub is equipped with a screw that is screwed into this screw groove, and the outer diameter of the spindle hub is contracted only when a magnetic disk is installed, so it is possible to effectively prevent the generation of abrasion particles and particles when installing a magnetic disk. This has the effect of significantly improving the reliability of the system.

[Brief explanation of drawings]

1 and 2 are a plan view and a front view showing the configuration of a spindle hub of a magnetic disk device according to an embodiment of the present invention together with a rotating shaft, and FIG. 3 is a sectional view taken along line AA' in FIG. FIG. 4 is a sectional view showing the main parts of a sealed magnetic disk device equipped with the spindle hub of the embodiment shown in FIGS. 1 to 3, and FIGS. FIG. lO... Spindle hub, 11... Disc-shaped bottom, 12... Cylindrical positioning part, 13-16...
Slot, 17... Screw groove, 18... Screw, 20.
... Rotating shaft, 31... Bearing, 32... Motor, 33... Base plate, 34... Cover, 41
~44...Spacer, 51-54...Magnetic disk. Figure 1

Claims (1)

[Scope of Claims] A spindle hub for positioning a plurality of magnetic disks stacked at the tip of a rotating shaft of a magnetic disk device with a spacer interposed therebetween, the spindle hub having a disk shape. a bottom portion, a cylindrical cylindrical portion extending upward from the bottom portion, and a plurality of slots formed along the axial direction of the cylindrical portion and symmetrically around the axis;
A spindle hub for a magnetic disk device, comprising a screw groove formed inside the cylindrical portion and a screw screwed into the screw groove.