JP2007285463A - Rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling bearing having improved responsiveness in microscopic rocking of a swing arm of a hard disk drive, by reducing frictional resistance by contact between a surface of a rolling body and a pocket surface of a cage. <P>SOLUTION: This rolling bearing has a relatively rotatably oppositely arranged bearing ring for rockingly and rotatably supporting the swing arm arranged in the hard disk drive, a plurality of rolling bodies 24 and 26 rollingly incorporated between the respective bearing rings, and the cages 28 and 30 for rotatably holding the plurality of rolling bodies in pockets 28a and 30a. The cages are set in the relationship of 1.05×Da≤Dp ≤1.15×Da in the size of its pockets, when assuming a rolling body diameter as Da, and a cage pocket diameter as Dp. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rolling bearing that supports an object so as to swing and rotate, and particularly supports a component that swings at a high speed such as a swing arm of a magnetic disk device (hard disk drive (hereinafter referred to as HDD)). It is related with the improvement of the rolling bearing used in order to do.

  Conventionally, a deep groove ball bearing using balls as rolling elements (hereinafter simply referred to as a ball bearing) is known as a rolling bearing that supports an object in a swingable and rotatable manner. For example, in an HDD bearing device mounted on a personal computer (desktop type and notebook type), swing arms that trace on a hard disk on which a large number of tracks are formed are arranged vertically along the axial direction. Two ball bearings are supported so as to be swingable and rotatable.

  As shown in FIG. 2 (a), for example, a bearing device used in such an HDD includes two rolling bearings (one-side ball bearings 10 (1) on the outer side in the vertical direction (the vertical direction in the figure) along the axis S. The lower side bearing in the figure), the other side ball bearing 12 (the upper side bearing in the figure)), and a sleeve 14 which is externally mounted on these two ball bearings 10 and 12. The sleeve 14 is configured such that a swing arm (not shown) is externally mounted, and includes a cylindrical sleeve main body 14a and an annular convex portion 14c provided on the inner peripheral surface 14b of the sleeve main body 14a. . The HDD includes a hard disk (not shown), a spindle motor that rotates the hard disk, and a magnetic head for writing data to the hard disk and reading data from the hard disk.

  In this case, for example, each of the ball bearings 10 and 12 has the inner rings 16 and 20 that are adhesively fixed to the outer peripheral surface S1 of the shaft S by applying an adhesive to the inner peripheral surfaces 16a and 20a. An adhesive 22 is applied to the outer peripheral surfaces 18a and 22a, and 22 is bonded and fixed to the inner peripheral surface 14b of the sleeve body 14a. As other fixing methods, for example, the inner peripheral surfaces 16a, 20a of the inner rings 16, 20 are brought into contact with the outer peripheral surface S1 of the shaft S to be press-fitted and fixed, and the outer peripheral surfaces 18a, 22a of the outer rings 18, 22 are fixed. May be pressed into and fixed to the inner peripheral surface 14b of the sleeve body 14a. In any case, the ball bearings 10 and 12 are positioned along the axial direction (vertical direction in FIG. 2A) at predetermined intervals by the annular convex portion 14c of the sleeve body 14a. A predetermined preload is applied to each of the bearings 10 and 12.

  Here, a method for applying a predetermined preload to the two ball bearings 10 and 12 will be described. For example, the annular protrusions 14c are interposed between the outer rings 18 and 22 of the two ball bearings 10 and 12, and the outer rings 18 and 22 are bonded and fixed to the inner peripheral surface 14b of the sleeve body 14a. Then, a preload in the direction of arrow F1 is applied to the inner ring 16 of the one-side ball bearing (lower bearing in FIG. 2A), and in this state, the inner ring 16 of the ball bearing 10 is moved to the axis S (outer peripheral surface S1). Adhesive fixing or press-fitting fixing to. Similarly, a preload in the direction of arrow F2 is applied to the inner ring 20 of the other ball bearing 12 (upper bearing in FIG. 2A), and in this state, the inner ring 20 of the ball bearing 12 is moved to the axis S (outer circumferential surface S1). Adhesive fixing or press-fitting fixing to. As a result, a predetermined preload can be applied to the two ball bearings 10 and 12.

In addition, the two ball bearings 10 and 12 are annularly rotated between the inner rings 16 and 20 and the outer rings 18 and 22 in a state where a plurality of rolling elements (balls) 24 and 26 are rotatably held one by one. Cages 28 and 30 are provided. The cages 28 and 30 are alternately provided with pockets 28a and 30a for holding the balls 24 and 26 and column portions 28b and 30b for connecting the adjacent pockets 28a and 30a along the circumferential direction. In this case, the cages 28 and 30 have a crown shape in which one of the balls 24 and 26 is inserted into the pockets 28a and 30a on one side and the other side is closed (a so-called crown shape). Cage). A pair of claw portions t protruding so as to partially cover the opening k are provided on the pillar portions 28b and 30b of the cages 28 and 30, and balls 24 and 26 inserted into the pockets 28a and 30a are provided. Is held in the pockets 28a, 30a in a state of being sandwiched by the claw portions t. In this state, the two ball bearings 10 and 12 have portions where the race rings (inner rings 16 and 20 and outer rings 18 and 22), rolling elements (balls) 24 and 26, and cages 28 and 30 contact each other. For the purpose of reducing wear due to friction, preventing seizure, and extending the fatigue life of the bearing, a predetermined lubricant (lubricating oil, grease, etc.) is enclosed therein.
In the configuration shown in FIG. 2A, the two ball bearings 10 and 12 are positioned so that the openings k of the cages 28 and 30 face each other as an example. The openings k may be positioned in the same direction (upward or downward direction in the figure), and the other side of the cages 28 and 30 (the closed side opposite to the opening k) is positioned facing each other. May be.

By the way, in recent years, downsizing (reduction in size and weight) of HDDs has progressed, and accordingly, allowable voltage and allowable current for driving HDDs have been lowered and reduced.
As a result, the rolling bearing used in the HDD causes the swing arm (particularly, the magnetic head attached to the tip of the swing arm) to be traced accurately and quickly within a very narrow range of the hard disk on which a large number of tracks are formed. There must be. For this reason, the rolling bearings for HDDs are particularly responsive (start of movement) when the swing arm is slightly swung during tracing. Specifically, the swing arm has a swing arm whose ball (ball) hardly rolls. There is a demand for lower torque during minute oscillation.

In response to such a demand for torque reduction, for example, in Patent Document 1, when the diameter (ball diameter) of the rolling elements (balls) 24 and 26 is Da and the pocket diameter of the cages 28 and 30 is Dp2, For HDD in which the ratio of the pocket diameter Dp2 to the ball diameter Da (ball diameter ratio) P2 (P2 = Dp2 / Da) is set within the range of 1.02 to 1.04 (1.02 ≦ P2 ≦ 1.04) A configuration of a rolling bearing (ball bearing) is disclosed as an example (see FIGS. 2B and 2C). According to such a configuration, the rolling elements (balls) 24 and 26 are not restrained positively, and the cages 28 and 30 are arranged in the radial direction (for example, the front and back directions in FIGS. 2B and 2C). The amount of movement can be kept small. As a result, a reduction in torque and a reduction in torque fluctuation of the ball bearings 10 and 12 (see FIG. 2A) incorporating the cages 28 and 30 are achieved.
JP 2003-194064 A

However, for example, when the swing arm starts to move during tracing, the surfaces (rolling surfaces) 24a, 26a of the rolling elements (balls) 24, 26 and the pocket surfaces 28p, 30p of the cages 28, 30 come into contact with each other. The frictional resistance between the moving surfaces 24a, 26a and the pocket surfaces 28p, 30p may increase, and the responsiveness during rotation of the rolling bearings (ball bearings 10, 12) may be reduced. In this case, as a result, the timing for starting the swing arm may be delayed, and the swing arm may not be traced at high speed and smoothly.
The present invention has been made to solve such a problem, and the object thereof is to reduce the frictional resistance caused by the contact between the surface of the rolling element and the pocket surface of the cage, and when the HDD swing arm is slightly swung. It is to provide a rolling bearing with improved responsiveness.

In order to achieve such an object, a rolling bearing according to the present invention supports a swing arm provided in a hard disk drive so as to swing and rotate, and a bearing ring disposed so as to be relatively rotatable. And a plurality of rolling elements that are rotatably incorporated between the races, and a holder that rotatably holds the plurality of rolling elements in the pocket. In such a configuration, the cage is set such that the pocket size is 1.05 × Da ≦ Dp ≦ 1.15 × Da when the rolling element diameter is Da and the cage pocket diameter is Dp. Has been.
Further, the number of recording tracks on the disk of the hard disk drive is set to 200,000 or more per inch.

  ADVANTAGE OF THE INVENTION According to this invention, the rolling bearing which reduced the frictional resistance by contact with the surface of a rolling element and the pocket surface of a holder | retainer, and improved the responsiveness at the time of the micro swing of the swing arm of HDD can be provided. .

Hereinafter, a rolling bearing according to an embodiment of the present invention will be described with reference to the accompanying drawings.
The basic configuration of the HDD bearing device according to the present embodiment is the same as that of the conventional bearing device (FIG. 2A) described above, and hereinafter, the characteristics of the rolling bearing used in the bearing device will be described. The explanation of the typical configuration is stopped.

  1A and 1B show rolling bearing cages (hereinafter referred to as cages) 28 and 30 according to an embodiment of the present invention. The cages 28 and 30 are hard disk drives. It is incorporated in rolling bearings 10 and 12 (see FIG. 2 (a)) that swingably and rotatably support a swing arm (not shown) provided in the drive (HDD). The rolling bearings 10 and 12 have a pair of bearing rings (inner rings 16 and 20 and outer rings 18 and 22) arranged to face each other so as to be relatively rotatable, and opposed surfaces 16b and 20b and outer rings 18 of the inner rings 16 and 20. , 22 are provided with a plurality of rolling elements (balls) 24, 26 that are rotatably incorporated between the raceway surfaces 16c, 20c and between the raceway surfaces 18c, 22c formed on the opposing surfaces 18b, 22b, respectively. .

  In the present embodiment, the two rolling bearings 10 and 12 swing the swing arm (not shown) of the HDD in a state where a predetermined preload is applied, as in the conventional HDD bearing device described above. And it supports rotatably. In this case, it is assumed as an example that the hard disk is an HDD to which a high track density disk having 200,000 or more recording tracks per inch is applied. In the present embodiment, the rolling bearings 10 and 12 are assumed to be deep groove ball bearings (hereinafter referred to as ball bearings 10 and 20) as an example, and the ball bearings 10 and 12 include a lubricant (for example, Lubricating oil or grease) is enclosed.

  In the configuration shown in FIGS. 1A and 1B, the cages 28 and 30 have a plurality of pockets 28a and 30a for holding a plurality of balls 24 and 26, respectively, and adjacent pockets 28a and 28a. Column portions 28b, 30b connecting 30a are alternately provided along the circumferential direction. In this case, the cages 28 and 30 have a crown shape in which one of the balls 24 and 26 is inserted into the pockets 28a and 30a on one side and the other side is closed (a so-called crown shape). Cage). A pair of claw portions t protruding so as to partially cover the opening k are provided on the pillar portions 28b and 30b of the cages 28 and 30, and balls 24 and 26 inserted into the pockets 28a and 30a are provided. Is held in the pockets 28a and 30a in a state of being sandwiched between the claws t.

In this case, as an example, the two cages 28 and 30 are incorporated in the ball bearings 10 and 12 with their openings k facing each other (see FIG. 2A), and the inner rings 16 and 20 and the outer rings 18 and 22 are assembled. Rotating between.
FIG. 1A shows a ball bearing on one side of two ball bearings 10 and 12 externally mounted along the axis S of the HDD in the vertical direction (vertical direction in FIG. 2A). (a) Upper bearing) The structure of the cage 30 (see FIG. 2A) incorporated between the inner and outer rings 20, 22 of the 12 and the ball 26 held in the pocket 30a of the cage 30 is as follows. Is shown as an example. FIG. 1 (b) also shows a holding mechanism incorporated between the inner and outer rings 16, 18 of the ball bearing 10 (the lower bearing in FIG. 2 (a)) of the two ball bearings 10, 12. The configuration of the ball 28 (see FIG. 2A) and the ball 24 held in the pocket 28a of the cage 28 is shown as an example.

  The two cages 28 and 30 may be incorporated in the ball bearings 10 and 12 with their openings k directed in the same direction (upward or downward in FIG. 2A), or on the other side (opening k). It may be incorporated in the ball bearings 10 and 12 with the closed side on the opposite side facing each other.

  In this embodiment, the diameters of the balls 24 and 26 (diameter (the distance in the left and right direction in FIGS. 1A and 1B)) are Da, and the diameters of the pockets 28a and 30a of the cages 28 and 30 (inner diameter (the same When the distance in the same direction in the figure)) is Dp1, the pocket diameter Dp1 is 105% or more of the ball diameter Da and 115% or less of the ball diameter Da (1.05 × Da ≦ Dp1 ≦ 1.15 × Da) It is set to be. In other words, when the ratio of the pocket diameter Dp1 to the ball diameter Da (ball diameter ratio) is P1 (P1 = Dp1 / Da), the value of the ball diameter ratio P1 is within the range of 1.05 to 1.15 ( 1.05 ≦ P1 ≦ 1.15).

  The diameters (ball diameter Da) of the balls 24 and 26 are not particularly limited here because they are set to a predetermined size according to the size of the HDD, for example. Further, the value of the ball diameter ratio P1 may be set to an arbitrary value within the range of 1.05 to 1.15 (1.05 ≦ P1 ≦ 1.15). Since it is arbitrarily set according to the ball diameter Da, the size of the HDD, the allowable torque of the ball bearings 10 and 12, etc., there is no particular limitation here. At this time, the ball diameter ratio P1 may be set to the same value by the two cages 28 and 30, or may be set to a different value by the cages 28 and 30.

Here, since the ball bearing 12 (the bearing on the upper side of FIG. 2A) is pre-loaded as described above and is externally mounted on the shaft S, the ball 26 incorporated between the inner and outer rings 20 and 22 is The track surfaces 20c and 22c are sandwiched between the track surfaces 20c and 22c with almost no play. For this reason, by setting the ball diameter ratio P1 within the range of 1.05 to 1.15 (1.05 ≦ P1 ≦ 1.15), the cage 30 holding the ball 26 in the pocket 30a is Due to its own weight, it moves very slightly in the direction of the ball 26 (downward direction in FIGS. 1 (a) and 2 (a)). In this state, the retainer 30 does not come into surface contact with the surface (rolling surface) 26a of the ball 26, as in the conventional configuration shown in FIG. In addition, the contact area between the pocket surface 30p and the ball 26 can be made extremely small (FIG. 1 (a)).
Thereby, when the ball bearing 12 rotates, the torque resistance can be reduced by extremely reducing the frictional resistance between the surface (rolling surface) 26a of the ball 26 and the pocket surface 30p of the cage 30, and the bearing can be reduced. 12 responsiveness can be improved.

Similarly, since the ball bearing 10 (the lower bearing in FIG. 2A) is pre-loaded as described above and is externally mounted on the shaft S, it is incorporated between the inner and outer rings 16,18. The ball 24 is sandwiched between the raceway surfaces 16c and 18c with almost no play. Therefore, by setting the ball diameter ratio P1 within the range of 1.05 to 1.15 (1.05 ≦ P1 ≦ 1.15), the cage 28 holding the ball 24 in the pocket 28a is Due to its own weight, it moves very slightly in the direction opposite to the ball 24 (downward direction in FIGS. 1B and 2A). In this state, the cage 28 does not come into surface contact with the surface (rolling surface) 24a of the ball 24 as in the conventional configuration shown in FIG. And the contact area of the said pocket surface 28p and the ball | bowl 24 can be made very small (FIG.1 (b)).
Thereby, when the ball bearing 10 rotates, the torque resistance can be reduced by extremely reducing the frictional resistance between the surface (rolling surface) 24a of the ball 24 and the pocket surface 28p of the cage 28. 10 responsiveness can be improved.

  As a result, for example, in an HDD, the swing arm (not shown) is supported by the ball bearings 10 and 12, so that when the swing arm slightly swings, the timing of its movement is not delayed, and a large number of Even within a very narrow range of a hard disk on which tracks are formed (for example, 200,000 tracks per inch (200,000 TPI)), the swing arm can be traced at high speed and smoothly.

  In the present embodiment, the two cages 28 and 30 are incorporated in the ball bearings 10 and 12 with the openings k facing each other as an example (see FIG. 2A). The opening k may be incorporated in the ball bearings 10 and 12 in the same direction (upward or downward in the figure), or the other side (the closed side opposite to the opening k) faces each other. The bearings 10 and 12 may be incorporated.

For example, when the two cages 28 and 30 are incorporated in the ball bearings 10 and 12 so that the openings k are directed in the same direction (upward or downward in FIG. 2A), the pocket surfaces 28p and 30p The contact state with the balls 24 and 26 is either the state in which the two cages 28 and 30 are as shown in FIG. 1B (when the opening k is facing upward), or the state shown in FIG. (when k are mutually downward).
Further, for example, when the two cages 28 and 30 are incorporated in the ball bearings 10 and 12 so that the other side (the closed side opposite to the opening k) faces each other, the contact between the pocket surface 28p and the ball 24 is achieved. The state is the state shown in FIG. 1A, and the contact state between the pocket surface 30p and the ball 26 is the state shown in FIG.

Also in these cases, when the ball bearings 10 and 12 are rotated, the frictional resistance between the surfaces (rolling surfaces) 24a and 26a of the balls 24 and 26 and the pocket surfaces 28p and 30p of the cages 28 and 30 is extremely reduced. Thus, torque fluctuations can be reduced, and the responsiveness of the bearings 10 and 12 can be improved.
As a result, as in the case described above, for example, even in a very narrow range of a hard disk (for example, 200,000 tracks per inch (200,000 TPI)) on which a large number of tracks are formed, the HDD swing arm Can be traced quickly and smoothly.

In the present embodiment described above, a crown type cage is applied as the cages 28 and 30, but various types such as a wave type cage, a cage type cage and a matching cage are also available. Can be applied.
Further, in the above-described embodiment, the ball bearings 10 and 12 (the inner rings 16 and 20, the outer rings 18 and 22, the balls 24 and 26, the cages 28 and 30) are not particularly mentioned, but the purpose of use Any material may be applied depending on the usage situation. For example, stainless steel, bearing steel (high carbon chrome bearing steel, carburized bearing steel, etc.), ceramic, and the like can be applied as materials for the inner rings 16, 20, outer rings 18, 22 and balls 24, 26, respectively. In addition, metal (iron, stainless steel, etc.) or plastic can be applied as the material of the cages 28 and 30, but in order to improve the size and weight reduction of the bearing device, the cages 28 and 30 are made of plastic. It is preferable that it is manufactured.
Furthermore, although not particularly mentioned in the above-described embodiment, a sealing plate may be interposed between the inner rings 16 and 20 and the outer rings 18 and 22 in order to seal the ball bearings 10 and 12. In this case, for example, a contact-type seal, a non-contact-type seal, a shield, or the like may be arbitrarily selected and provided.

(a), (b) is principal part sectional drawing which shows the structural example of the cage for rolling bearings concerning one Embodiment of this invention. It is a figure which shows the structural example of the conventional HDD bearing apparatus, Comprising: (a) is principal part sectional drawing which shows the whole structural example, (b), (c) is a structural example of the cage for rolling bearings FIG.

Explanation of symbols

10, 12 Ball bearing 14 Sleeve 14a Sleeve body 14b Sleeve inner peripheral surface 14c Annular convex portions 16, 20 Inner ring 16a, 20a Inner ring inner peripheral surface 16b, 18b, 20b, 22b Opposing surfaces 16c, 18c, 20c, 22c Raceway surface 18, 22 outer ring 18a, 22a outer ring outer peripheral surface 24, 26 ball 24a, 26a ball surface 28, 30 cage 28a, 30a pocket 28b, 30b pillar 28p, 30p pocket surface 28x, 30x pocket surface-ball contact point k opening t claw Da Ball diameter Dp1 Pocket diameter S Axis S1 Axis outer peripheral surface F1, F2 Preload direction

Claims (2)

A swing arm provided in the hard disk drive is supported so as to be swingable and rotatable, and a raceway arranged to be relatively rotatable and opposed to each other, a plurality of rolling elements rotatably incorporated between the raceways, A rolling bearing comprising a cage for rotatably holding a rolling element in a pocket,
The cage is characterized in that the pocket size is set to 1.05 × Da ≦ Dp ≦ 1.15 × Da when the rolling element diameter is Da and the cage pocket diameter is Dp. Rolling bearing. 2. The rolling bearing according to claim 1, wherein the number of recording tracks of the disk of the hard disk drive is 200,000 or more per inch.

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