JPS61241524A - Bearing device - Google Patents

Abstract

PURPOSE:To prevent deformation of an outer race of a bearing, and to improve an effect of vibration damping of a bearing portion by setting a position for pressing a sleeve engaged with an outer race of a bearing outside the thickness center radius of the outer race from the center line of a shaft. CONSTITUTION:A ball bearing 3 is fixed to a ring-shaped sleeve 8 by pressing. A little space is provided between the sleeve 8 and a base 7, and the sleeve 8 is pushed in the axial direction by pressing force of a spring 6. Thus, radial gap between the inner and outer races of the bearing 3 is removed. The center line along the pre-pressure produced by a pre-pressure spring 10 is disposed outside the outside diameter of the outer race of the bearing, and contact points 12, 13 are disposed in the center line. In this arrangement, disturbance vibration transmitted from a base 7 will not directly excite the bearing 3, and most of the disturbance vibration takes a roundabout from the contact points 12, 13 to the sleeve 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a bearing device that improves the rotation accuracy of a rotating body, and particularly to a bearing device that is most suitable for a high-precision rotating body such as a rotating body of a magnetic disk device.

[Background of the invention]

Generally, the shaft of a rotating body is rotatably supported at its upper and lower ends by a base via bearings. One of these bearings is tightly fitted and fixed to the base, and the other is fixed during assembly.
It is a loose fit. A spring or the like is interposed between the base and the bearing so as to pass through the center of the bearing from one direction to apply preload, thereby ensuring accurate positioning of the shaft in the radial and axial directions, suppressing shaft runout, and increasing bearing rigidity. I'm trying to raise it. However, in such a structure, since the bearing outer shaft is directly preloaded in the radial direction, the bearing outer shaft is likely to be deformed, resulting in a decrease in rotation accuracy. Moreover, between the base and the bearing on the side where the spring or the like applying preload is interposed, there is a gap in which the holding force is not effective in a direction perpendicular to the preload direction. For this reason, the radial runout in the right angle direction becomes large, and it is not possible to improve the accuracy of one rotation. Also,
Since force is directly transmitted between the bearing and the base on the center line in the preload direction, the dynamic stability of the shaft against disturbances may be reduced.

For example, as a structure that takes these points into consideration,
There is a structure described in Japanese Patent No. 8-184318.

In this structure, the bearing is fixed to the ring-shaped sleeve by press fitting or adhesive.

A groove is provided between the sleeve and the base, and a preload spring is inserted into the groove to indirectly press the bearing outer shaft. In addition, a slight gap is left between the sleeve and the base on the side with the preload spring.
The outer surface of the sleeve on the opposite side where the spring acts is eccentrically machined to have a cross section with a radius of curvature slightly larger than the outer diameter of the sleeve. As a result, when a preload is applied by the spring, a holding force is also generated in a direction perpendicular to the preload direction, thereby reducing whirling of the shaft in the perpendicular direction.

However, even in this structure, the position of the spring that presses the sleeve is at the center of the shaft, in other words, the acting force is at the center of the bearing, so disturbance vibrations that are transmitted to the base end up passing through the sleeve. - There is a possibility that the bearing and shaft may be vibrated in a straight line, resulting in increased whirling toward the main shaft. Furthermore, in terms of structure, since a single spring pushes the center of the arc of the sleeve where the deformation is greatest, it is necessary to increase the material strength of the sleeve to prevent the sleeve from deforming.

[Purpose of the invention]

An object of the present invention is to provide a bearing device that eliminates radial displacement of the bearing and can provide a highly accurate rotating body that rotates stably even in the face of external vibrations.

[Summary of the invention]

Applying preload to a bearing is used for many rotating bodies in order to eliminate play in the bearing, but depending on the method used, the preload method that eliminates play in the radial direction may cause deformation of the outer shaft of the bearing, which may actually cause damage to the bearing. It can also increase vibration. In addition, if the direction of preload and the contact position between the bearing and the base are not appropriate, external vibration from the base will directly cause
It is transmitted to the rotating shaft via the contact point, and can also cause an increase in the rotation of the shaft. From this point of view, the present invention presses the sleeve that houses the bearing without directly preloading the outer shaft of the bearing, and furthermore, the contact position between the sleeve and the base hole is set at an optimal position where external vibrations are least likely to be transmitted. It is characterized by:

[Embodiments of the invention]

An example of a bearing device according to the present invention applied to a magnetic disk device will be described below with reference to FIGS. 1 and 2.

The main shaft 1 is rotatably supported on a base 7 by ball bearings 2 and 3. A hub 4 is fixed to the main shaft 1, and a large number of magnetic disks 5 are stacked on the hub 4 at regular intervals. Also, between the above ball bearings 2 and 3,
A coil spring 6 is inserted to apply preload in the axial direction.

Of the ball bearings 2.3 described above, the ball bearing 2 is held or bonded to the base 7 so that its outer ring is sufficiently fitted into the ball bearing insertion hole diameter of the base 7.

Further, the other ball bearing 3 is fixed to a ring-shaped sleeve 8 by press fitting or adhesive. Further, a slight gap is provided between the sleeve 8 and the base 7, and the pressing force of the spring 6 pushes the sleeve 8 in the axial direction. In other words, the bearing outer shaft is not directly preloaded, but is indirectly pushed in the axial direction, thereby creating a structure in which axial preload is applied. Therefore, the radial clearance existing between the inner ring and outer ring of the bearing 3 is removed. In this example, grooves 9 are provided at two locations between the sleeve 8 and the base 7, as shown in FIG. 2, and springs 10 are inserted into the grooves to preload the sleeve 8 in the radial direction. Further, the surface of the base 7 on the opposite side on which the spring 10 acts has a radius of curvature slightly larger than the outer diameter of the opposing sleeve 8. As a result, a gap 11 is formed between the base 7 and the sleeve 8, and the sleeve 8 and the base 7 are connected to the two points 12 and 1.3 on the line of action of the two springs 9 and 9. I will be in contact with you. With such a configuration, a holding force in a direction perpendicular to the preload direction is also generated, so that the wobbling of the shaft in the perpendicular direction is reduced. Furthermore, the center line in the direction of preload by the preload spring 10 is set to
It is arranged outside the outer diameter of the outer ring, and a contact point 12° 13 is arranged on the center line. In this way, external vibrations transmitted through the base 7 will not directly excite the bearing 3, and most of them will detour from the contact points 12 and 13 to the sleeve 8, thereby reducing the swing of the main shaft 1. It will not increase,
High precision bearings can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, there is no deformation of the outer ring of the bearing, and the vibration and force transmission between the base and the bearing is not linear but in a roundabout direction, and the vibration damping effect of the bearing is also improved. Therefore, it is possible to obtain an optimal bearing for obtaining a highly accurate rotating body.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of the structure of an example of a bearing device of the present invention applied to a magnetic disk device, and FIG.
It is a sectional view taken along the line ■-■ in the figure. 1... Main shaft, 2, 3... Bearing, 4... Hub, 5...
...Magnetic disk, 6...Coil spring, 7...Base, 8...Sleeve, 9...Groove, 10...Spring,
12.13...Contact point.

Claims (1)

[Scope of Claims] 1. In a bearing device that applies preload in the radial direction to an outer ring of a bearing that is rotatably supported on a shaft or a part that contacts the outer ring, a sleeve fitted to the outer ring of the bearing is provided. A bearing device characterized in that the pushing position is outside the center radius of the plate thickness of the outer ring from the shaft center line. 2. The outer periphery of the sleeve or the inner wall of the base is eccentrically processed so that the outer periphery of the sleeve contacts the inner wall of the insertion hole of the base that accommodates the bearing fitted with the sleeve on the line of action of the preload force. A bearing device according to claim 1, characterized in that: