JPH04362568A - Radial pre-load and sealing structure of bearing - Google Patents

Abstract

PURPOSE:To reduce radial pre-load and to prevent off-track owing to the inclination of a shaft by setting a groove into which a packing is inserted to be eccentric. CONSTITUTION:The center of a circular groove 12c for inserting the packing 17 which is peripherally provided for a hole part 12a is made to be eccentric in the same direction of the pre-load direction of a radial pre-load mechanism 14 energizing an outer race 9b as against the hole part 12a of a housing 12 holding the outer race 9b of a bearing with a clearance. Thus, radial pre-load as against the outer race 9b of the bearing 9 is increased in the same direction as the pre-load mechanism 14 by the pre-load of the packing 15 by electricity.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radial pressurization and sealing structure of a bearing that supports a shaft of a magnetic disk in a magnetic disk drive.

0002

2. Description of the Related Art As shown in the side view of FIG. 3, a magnetic disk device 1 to which the present invention is applied stores information in a donut-shaped area several tens of μm wide called a track on the surface of a magnetic disk 2, which is a recording medium. It is used to record and read the recorded information.

[0003] Tracks are arranged concentrically on the surface of the magnetic disk 2 like the annual rings of a tree, and one track is an area in which one magnetic head 3 can continuously write/read. A plurality of magnetic disks 2 are arranged at equal intervals as shown in the figure.
They are stacked on a shaft and rotated at high speed by a rotation mechanism (spindle) 4.

The magnetic head 3 includes a carriage 7 that rotates (seeks) on the surface of the magnetic disk 2 around a shaft 6.
The carriage 7 is held by, for example, a voice coil motor (VCM) 5.
It is rotated depending on the

The entire magnetic disk drive 1 is covered with a dust-proof top sealing cover 8. In a rotary drive system in which both ends of the shafts 6 and 10 are supported by a pair of bearings 9, such as the spindle 4 of the magnetic disk drive 1 or the carriage 7, thrust pressurization and radial pressurization are generally applied to the bearings 9. It is often used.

[0006] The thrust pressurization functions to absorb the internal gap of the bearing 9, prevent wobbling in the shaft direction, and maintain a stable relative height between the magnetic head 3 and the magnetic disk 2. In the case of the spindle 4, in which the bearing 9 fixes the outer ring and rotates the inner ring, the shaft 10 is press-fitted into the inner ring, and the outer ring is fit into a hole in a housing 12 that holds it.

On the other hand, like the carriage 7, the bearing 9
In the case of a method in which the inner ring is fixed and the outer ring is rotated, the outer ring is press-fitted into a hole in the carriage 7, and the shaft 6 is fit into the inner ring with a clearance.

This is because if both wheels are press-fitted, the bearing 9 will also be restricted in the shaft direction, and thrust pressurization will no longer work. In this way, either one of the two wheels of the bearing 9 is held with a gap in the radial direction, so that rattling occurs in the radial direction.

[0009] In the case of the spindle 4, this rattling appears as a vibration asynchronous to rotation, which interferes with positioning of the magnetic head 3 and reading/writing data. In addition, in the case of the carriage 7, a slight inclination of the shaft 6 occurs every time a seek is performed, making the position of the data head relative to the servo head unstable, resulting in off-track, which interferes with data reading/writing as described above. vinegar.

[0010] Therefore, the above-mentioned wobbling is prevented by applying radial pressurization to the bearing ring on the side that is loosely fitted and pressing it in a certain direction. Moreover, the magnetic disk device 1
In this case, if dust exists inside the device, it will enter between the magnetic head 3 and the magnetic disk 2, which is a recording medium, causing data read/write errors and, in severe cases, head crashes.

[0011] For this reason, the magnetic disk device 1 has a sealed structure in which the parts are joined to each other via rubber packing or the like, and a magnetic seal 16 is used at the rotating part to block air flow to the outside of the device. .

As shown in the enlarged view of FIG. 4, in the bearing 9, a shaft 10 is press-fitted into an inner ring 9a, an outer ring 9b is held in a hole 12a of a housing 12 with a gap,
A spring 13 applies thrust pressurization, and a spring 14 applies radial pressurization.

The housing 12 is attached to the sealing cover 8 via a packing 15, and a hole 12b is provided to prevent the magnetic seal 16 from bursting when the temperature changes. As mentioned above, the outer ring 9b of the bearing 9 is attached to the housing 1.
Since the housing 12 is held with a gap in the hole 12a of the housing 12, in order to seal this gap, a circular groove 12c is provided around the hole 12a of the housing 12, and a ring-shaped packing 17 is fitted into the hole 12c.

The packing 17 is attached to the outer ring 9 of the bearing 9.
It is pressed and crushed by b. The above has described the case where radial pressurization is applied to the outer ring 9b of the bearing 9, but as shown in the enlarged view of FIG. 5, when applying radial pressurization to the inner ring 9a of the bearing 9, the bearing 9 is 9b is press-fitted into a carriage (not shown), the inner ring 9a is held on the shaft 6 with a gap, and the spring 13
Thrust pressurization is applied by the shaft 6, and radial pressurization is applied by the spring 18 embedded in the shaft 6.

16 is a magnetic seal, and a bearing 9
This prevents the grease from turning into oil mist and scattering into the equipment. However, with this configuration, since the inner ring 9a of the bearing 9 is held with a gap from the outer periphery of the shaft 6 as described above, grease will scatter into the device from this gap.

Therefore, conventionally, a groove 19 is formed on the outer circumference of the shaft 6.
A ring-shaped packing 20 is inserted into the ring-shaped packing 20, and the inner ring 9a is pressed to crush and seal it.

[0017]

[Problem to be solved by the invention] In the above configuration,
The center of the hole 12a of the housing 12, the center of the circular groove 12c, the center of the shaft 6, and the center of the groove 19 are made concentric for ease of machining.

However, in reality, there is some eccentricity due to variations in processing, and since the packing 17 or 20 is made of rubber, it does not have a completely uniform cross-sectional shape around the entire circumference. The amount of deformation of the packing 17 or 20 was undefined and not uniform.

For example, when applying radial pressurization to the outer ring 9b, the center of the circular groove 12c of the housing 12 is relative to the center of the hole 12a of the housing 12, as shown in FIG. If it is eccentric by arrow e in the opposite direction to the direction of radial pressurization, the width of the space in which the packing 17 is sandwiched is arrow b with eccentricity arrow e added on the radial pressurization side, whereas, On the opposite side is an arrow a which is a reduction of the eccentricity arrow e.

Therefore, on the arrow a side, the packing 17 is crushed more by the outer ring 9b of the bearing 9 than on the arrow b side, and the load of arrow c, which is twice the amount of arrow e, is applied in the opposite direction to the radial pressurization. is added to the outer ring 9b of the bearing 9.

[0021] As a result, the radial pressurization becomes weaker than the desired value. The eccentricity of the circular groove 12c is several tens of micrometers at most, but the cross-sectional deformation (for example, diameter) of the packing 17 can vary by several hundred micrometers, and the direction on the circumference is completely undefined.

If there is a temperature change in such a state, the deflection amount of the packing 17 changes depending on the thermal expansion of the housing 12, the bearing 9, and the packing 17, and the outer ring 9b of the bearing 9 is subjected to a load with an indeterminate direction. As a result, the shaft 10 of the spindle 4 tilts in an undefined direction.

[0023] This causes the carriage to fall down relative to the carriage 7, resulting in off-track and data read/write.
There was a problem that it interfered with the light. On the other hand, when applying radial pressurization to the inner ring 9a,
As shown in the E-F cross-sectional view, if the center of the groove 19 of the shaft 6 is eccentric from the center of the bearing 9 by an arrow e in the same direction as the direction of radial pressurization, then the width of the space in which the packing 20 is sandwiched is On the radial pressurization side, arrow b is the addition of eccentricity arrow e, whereas on the opposite side, it is arrow a, with eccentricity arrow e reduced.

Therefore, on the arrow a side, the packing 20 is crushed more by the inner ring 9a of the bearing 9 than on the arrow b side, and the load of arrow c, which is twice the amount of arrow e, is applied in the opposite direction to the radial pressurization. is added to the inner ring 9a of the bearing 9.

Then, as in the case of applying radial pressurization to the outer ring 9b, the radial pressurization may be lower than the desired value due to the eccentricity of the shaft 6 and the groove 19 and the variation in the cross-sectional shape of the packing 20. This means that it becomes weaker.

[0026] If the radial pressurization load weakens or the shaft 6 tilts in an undefined direction due to temperature changes, there is a problem in that off-track occurs, causing trouble in reading/writing data. Ta.

The present invention aims to provide a radial pressurization and sealing method that allows desired radial pressurization to be applied even if there are variations in parts, and that does not change the direction of shaft inclination even when the temperature changes. This is the purpose.

[0028]

[Means for solving the problem] In the present invention, FIG.
As shown in the main part sectional view, the center of the circular groove 12c for inserting the packing 17 provided around the hole 12a is set to the center of the hole 12a of the housing 12 that holds the outer ring 9b of the bearing 9 with a gap. , is eccentric in the same direction as the pressurizing direction of the radial pressurizing mechanism 14 that urges the outer ring 9b.

Alternatively, as shown in the main part sectional view of FIG. 2, a shaft 6 that holds the inner ring 9a of the bearing 9 with a gap
With respect to the center of the shaft 6, the center of the groove 19 for inserting the packing 20 provided around the outer circumference of the shaft 6 is eccentric in the direction opposite to the pressurizing direction of the radial pressurizing mechanism 18 that urges the inner ring 9a. It is.

[0030]

In the case of FIG. 1, the radial pressurization of the outer ring 9b of the bearing 9 is increased in the same direction as the pressurization mechanism 14 due to the pressurization of the packing 15 due to eccentricity.

In the case of FIG. 2, the radial pressurization of the inner ring 9a of the bearing 9 is increased in the same direction as the pressurization mechanism 18 due to the pressurization of the packing 20 due to eccentricity.

[0032]

[Embodiment] In the present invention, as shown in the cross-sectional view of the main part of FIG.
In the case of the biasing method, a circular groove 12 for inserting the packing 15 provided around the hole 12a is inserted into the center of the hole 12a of the housing 12 that holds the outer ring 9b with a gap.
The center of c is offset by an arrow f in the same direction as the pressurizing direction of the radial pressurizing mechanism 14.

In other words, arrow f indicates that within the range of variations in cross-sectional diameter and eccentricity of packing 17, the width of the space between packing 17 and outer ring 9b of bearing 9 is greater than arrow b' on the radial pressurized side. is also set so that the arrow a' on the opposite side is larger.

Therefore, since the packing 17 is crushed more on the arrow b' side than on the arrow a' side, the packing 17 is crushed more than on the arrow a' side.
The direction of the load that the outer ring 9b of the bearing 9 receives from the bearing 9 is constant and in the same direction as the pressurization by the radial pressurization mechanism 14.

Therefore, the radial pressurization does not become smaller than a desired value, and even if the temperature changes, the outer ring 9b always contacts the hole 12a of the housing 12 on the opposite side of the circumference from the radial pressurization. Therefore, off-track due to the inclination of the shaft 10 can be prevented.

In addition, in the case of a method in which the inner ring 9a of the bearing 9 is biased by the radial pressurizing mechanism 18, as shown in the cross-sectional view of the main part in FIG. In contrast, the center of the groove 19 for inserting the packing 20 provided around the outer periphery of the shaft 6,
It is eccentric by arrow f in the direction opposite to the pressurizing direction of the radial pressurizing mechanism 18 that urges the inner ring 9a.

The amount of eccentricity of the arrow f and the actions and effects resulting from the eccentricity are the same as in FIG. 1 described above.

[0038]

[Effects of the Invention] According to the present invention, when sealing is achieved by directly crushing the packing with the outer ring or inner ring of a bearing to which radial pressurization is applied, the radial pressurization can be reduced by simply making the groove into which the packing is inserted eccentrically. This has great economic and industrial effects, such as being able to prevent off-tracking due to the inclination of the shaft.

[Brief explanation of the drawing]

[Fig. 1] A sectional view of the first essential part of the radial pressurization and sealing structure of the bearing of the present invention,

[Fig. 2] A sectional view of the second main part of the radial pressurization and sealing structure of the bearing of the present invention,

FIG. 3 is a side view of a magnetic disk device to which the present invention is applied;

[Figure 4] Enlarged view of the radial pressurization and sealing structure of a conventional outer ring pressurized bearing.

[Figure 5] Enlarged view of the radial pressurization and sealing structure of a conventional pressurized inner ring type bearing.

[Fig. 6] Cross-sectional view along CD in Fig. 4,

[Figure 7] EF cross-sectional view of Figure 5,

[Explanation of symbols]

1 magnetic disk device, 6, 10 shaft, 9 bearing, 9a inner ring, 9b outer ring, 12 housing, 12a hole, 12c circular groove, 14, 18 radial pressurization mechanism (spring), 15, 17
, 20 packing, 19 groove,

Claims (2)

[Claims] Claim 1: A hole (12) in a housing (12) that holds an outer ring (9b) of a bearing (9) with a gap.
a) The center of the circular groove (12c) for inserting the packing (17) provided around the hole (12a) is connected to the radial pressurizing mechanism (14) that biases the outer ring (9b). ) The radial pressurization and sealed structure of the bearing is characterized by eccentricity in the same direction as the pressurization direction of the bearing. 2. A groove for inserting a packing (20) provided around the outer periphery of the shaft (6) relative to the center of the shaft (6) that holds the inner ring (9a) of the bearing (9) with a gap. (19), the center of the inner ring (9)
(a) A radial pressurization and sealing structure for a bearing, characterized in that the radial pressurization mechanism (18) that biases the bearing is eccentric in a direction opposite to the pressurization direction.