JP2012092980A - Bearing unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bearing unit in which radial rigidity is improved, and cost and torque of a bearing is reduced.SOLUTION: Three, first to third single row bearings 6, 8, and 10 are arranged between a shaft body 2 and a housing 4. The second and third single row bearings are arranged on both sides of the first single row bearing. Each single row bearing includes an inner ring 12, an outer ring 14, and a plurality of rolling elements 16. Between the second single row bearing and the first single row bearing, a spacer 18 is interposed in such condition as abutted with the outer rings. Between the first single row bearing and the third single row bearing, a spacer 20 is interposed in such condition as abutting the inner rings. The inner ring of the second single row bearing abuts an outward flange 2f. The inner ring of the third single row bearing is bonded and fixed to the shaft body. The second single row bearing and the first single row bearing are arranged back to back. The first single row bearing and the third single row bearing are arranged face to face.

Description

  The present invention relates to a bearing unit that rotatably supports, for example, a swing arm of a hard disk drive (HDD) device.

  Conventionally, as an HDD apparatus using this type of bearing unit, for example, as shown in FIGS. 3A and 3B, a spindle motor 104 that rotates the magnetic disk 102 and information on the magnetic disk 102 are stored. One having a magnetic head 106 for performing recording or reading is known. The magnetic head 106 is attached to the tip of a swing arm 108 that is rotatably supported by a bearing unit J, and a voice coil 110 that rotates the swing arm 108 is provided at the base end. The swing arm 108 is rotatably supported on the base Bs of the HDD device via the bearing unit J. In this case, information is recorded on the magnetic disk 102 by rotating the swing arm 108 while the magnetic disk 102 is rotated, and the magnetic head 106 is translated relative to the magnetic disk 102, or the magnetic disk Information can be read from 102.

  In recent years, the HDD apparatus as described above has been required to increase the speed of recording and reading of information. Accordingly, the bearing unit J used in the HDD apparatus has a rigidity in the radial direction (radial direction). There is a demand for improving the rigidity. Therefore, in order to meet such a requirement, for example, Patent Document 1 proposes a technique for improving the radial rigidity by increasing the number of angular ball bearings. Further, for example, Patent Documents 2 and 3 propose a technique for improving radial rigidity by incorporating four (row) ball bearings.

JP 2006-329216 A JP-A-2005-207455 US 6,191,924 B1

However, in the technique for increasing the number of balls (Patent Document 1), the number of parts of the bearing may increase and the manufacturing cost may increase. Therefore, there is a certain limit to the cost reduction of the bearing. . In addition, in the technology (Patent Documents 2 and 3) in which four (row) ball bearings are incorporated, there is a case where the torque at the time of rotating the bearing is increased. there were.
Therefore, there is a demand for the development of a technique capable of improving the radial rigidity and reducing the cost and the torque of the bearing, but such a technique is not known at present.

  The present invention has been made to meet such demands, and an object of the present invention is to provide a bearing unit capable of improving radial rigidity and reducing the cost and torque of the bearing. .

In order to achieve such an object, the present invention is configured so that an outward flange protrudes from one end side and extends from the one end side toward the other end side so as to cover the outside of the shaft body. And three first to third single row bearings arranged between the shaft body and the housing, and second and third single row bearings on both sides of the first single row bearing. The row bearings are arranged, and each single row bearing is a bearing unit including an inner ring and an outer ring, and a plurality of rolling elements that are rotatably incorporated between the inner and outer rings, and a second single row A spacer is interposed between the bearing and the first single row bearing in contact with the outer rings, and between the first single row bearing and the third single row bearing. Has a spacer interposed between the inner rings, and the inner ring of the second single row bearing is in contact with the outward flange, and the third single row The inner ring of the support is bonded and fixed to the shaft body, the second single row bearing and the first single row bearing are arranged in a rear combination, and the first single row bearing and the third single row bearing are: Arranged in frontal combination.
In the present invention, the contact angle of the first single row bearing is set larger than the contact angles of the second and third single row bearings.

  ADVANTAGE OF THE INVENTION According to this invention, while improving radial rigidity, the bearing unit which can achieve the cost reduction and torque reduction of a bearing is realizable.

(a) is sectional drawing which shows the structure of the bearing unit which concerns on one embodiment of this invention, (b) is a figure which shows the 1st preload provision process in the case of the assembly of the bearing unit of the figure (a), (c) is a figure which shows the 2nd preload provision process in the case of the assembly of the bearing unit of the figure (a). (a) is sectional drawing which shows the structure of the bearing unit which concerns on the modification of this invention, (b) is a figure which shows the preload provision process in the case of the assembly of the bearing unit of the figure (a). (a) is sectional drawing which shows the structure of HDD apparatus, (b) is a top view of the HDD apparatus of the figure (a).

Hereinafter, a bearing unit according to an embodiment of the present invention will be described with reference to the accompanying drawings.
As shown in FIG. 1A, the bearing unit J of the present embodiment includes a shaft body 2 having an outward flange 2f projecting from one end side and extending from the one end side toward the other end side, The housing 4 is disposed so as to cover the outside of the body 2, and the three single row bearings 6, 8, 10 are arranged between the shaft body 2 and the housing 4. Each single-row bearing 6, 8, 10 includes an inner ring 12 bonded and fixed to the shaft body 2, an outer ring 14 bonded and fixed to the housing 4 facing the inner ring 12, and the inner and outer rings 12 and 14. It comprises a plurality of rolling elements 16 incorporated so as to be capable of rolling.

  In the drawing, “balls” are illustrated as the rolling elements 16, but “rollers” may be applied. Further, although not particularly given a reference symbol in the drawings, each of the three single row bearings (first single row bearing 6, second single row bearing 8, and third single row bearing 10) includes: A cage for rotatably holding the plurality of rolling elements 16 and a sealing plate (for example, a seal or a shield) for sealing the inside of the bearing from the outside of the bearing are provided, but these are not necessarily required.

  In such a bearing configuration, the three single row bearings (the first single row bearing 6, the second single row bearing 8, and the third single row bearing 10) are shaft bodies in a state where a predetermined preload is applied. 2 and the housing 4 are bonded and fixed. In this case, of the three single row bearings 6, 8, and 10, the preload of the first single row bearing 6 is the other two single row bearings (the second single row bearing 8, the third single row bearing The contact pressure L1 of the first single row bearing 6 and the contact angle L2 of the second single row bearing 8 and the third single row bearing 10 are set to a preload load larger than that of the row bearing 10). It is set larger than the contact angle L3.

  Note that the contact angles L1, L2, and L3 are defined by the lines connecting the points where the rolling elements 16 are in contact with the inner and outer rings 12 and 14 when a preload is applied to the single-row bearings 6, 8, and 10, respectively. It is defined as the angle formed with a plane (radial plane) perpendicular to the central axis. In this case, as the contact angle increases, the bearing's ability to apply an axial load increases. Conversely, as the contact angle decreases, the bearing's ability to apply a radial load increases.

  Here, the arrangement configuration of the three single row bearings 6, 8, and 10 in the bearing unit J of the present embodiment will be described. The first single row bearing 6 having a large contact angle L1 is connected to the outward flange 2f on one end side. The third single row bearing 10 having a small contact angle L3 is arranged on the other end side, and the second single row bearing 8 having a small contact angle L2 is arranged in the middle between both bearings 6 and 10. ing.

  In such an arrangement, the first single-row bearing 6 and the second single-row bearing 8 which are adjacent to each other on one end side are arranged in a back face combination (DB) and the preload direction of both the bearings 6 and 8 is set. Are set in opposite directions. In this case, the preload load of the first single row bearing 6 with the large contact angle L1 is the sum of the preload loads of the second and third single row bearings 8 and 10 with the other two small contact angles L2 and L3. It is set almost the same. In other words, the preload of the first single row bearing 6 is set to approximately twice the preload applied to each of the second and third single row bearings 8 and 10. At this time, the preloads of the second and third single row bearings 8 and 10 may be set to substantially the same level.

  In addition, the preload direction of the first single row bearing 6 having a large contact angle L1 is set to be opposite to the preload directions of the second and third single row bearings 8 and 10. As a result, the first single row bearing 6 and the second single row bearing 8 are arranged in the rear combination (DB), and the second single row bearing 8 and the third single row bearing 10 are combined in parallel. It will be arranged with (DT). The rear combination (DB) bearing has the ability to load a radial load and an axial load in both directions, and the parallel combination (DT) bearing has the ability to load a radial load and an axial load in one direction.

Next, an example of a method for assembling the bearing unit J of the present embodiment will be described.
First, as shown in FIG. 1B, the first single-row bearing 6 having a large contact angle L1 is inserted between the shaft body 2 and the housing 4, and the inner ring 12 is brought into contact with the outward flange 2f. In this state, the shaft body 2 is adhered and fixed. At this time, the outer ring 14 of the first single-row bearing 6 is not moved and fixed to the housing 4 without being adhesively fixed. The radial internal clearance of the first single-row bearing 6 is set in advance larger than the other two single-row bearings (second and third single-row bearings 8 and 10).

  Subsequently, after the outer ring spacer 18 is inserted between the shaft body 2 and the housing 4 and brought into contact with the outer ring 14 of the first single row bearing 6, the second single row bearing 8 having a small contact angle L2. Is inserted between the shaft body 2 and the housing 4, and the outer ring 14 is brought into contact with the outer ring spacer 18. In this state, a first preload F + α is applied from the second single row bearing 8 side toward the outward flange 2f. At this time, the first preload F + α is applied to the inner ring 12 of the second single row bearing 8, and the inner ring 12 is bonded and fixed to the shaft body 2 while maintaining the state. Thereby, the second single row bearing 8 is fixed (temporarily fixed) between the shaft body 2 and the housing 4.

  Next, as shown in FIG. 1 (c), the outer ring spacer 20 is inserted between the shaft body 2 and the housing 4 and brought into contact with the outer ring 14 of the second single row bearing 8. The third single-row bearing 10 having the corner L3 is inserted between the shaft body 2 and the housing 4, and the outer ring 14 is brought into contact with the outer ring spacer 20. In this state, a second preload F is applied from the third single row bearing 10 side toward the outward flange 2f. At this time, the second preload F is applied to the inner ring 12 of the third single row bearing 10, and the inner ring 12 is bonded and fixed to the shaft body 2 while maintaining the state, and the outer ring 14 is attached to the housing 4. Adhere and fix.

  In this case, the first preload load F + α is set larger than the second preload load F in consideration of the decrease in the preload load of the second single row bearing 8 when the second preload load F is applied. Has been. More specifically, the second single-row bearing 8 temporarily fixed between the shaft body 2 and the housing 4 has an inner ring 12 bonded and fixed to the shaft body 2, and an outer ring 14 extending along the housing 4. It is free to move. Further, as described above, the outer ring 14 of the first single-row bearing 6 is also free to move along the housing 4.

  In this state, when the second preload load F is applied to the inner ring 12 of the third single row bearing 10, the preload is transmitted from the outer ring 14 of the third single row bearing 10 via the outer ring spacer 20. And is transmitted to the outer ring 14 of the first single row bearing 6 through the outer ring spacer 18. At this time, the outer rings 14 of the first and second single row bearings 6 and 8 both move along the housing 4 by a predetermined amount.

  Here, in the first single row bearing 6, the preload load (first preload load F + α) already applied is further increased. On the contrary, the second single row bearing 8 is The preload load that has already been applied (first preload load F + α) decreases. Therefore, the first preload load F + α is larger than the second preload load F in consideration of the decrease (α) of the preload load of the second single row bearing 8 when the second preload load F is applied. It is set large. In other words, even if the first preload F + α already applied to the second single row bearing 8 decreases when the second preload F is applied, the second single row bearing 8 The first preload load F + α is set so that the second preload load F remains at the same time.

  As a result, the first single row bearing 6 on one end side is in a state where a preload load approximately twice the second preload load F is applied to the first single row bearing 6 on the other end side. The third single row bearing 10 is in a state where a second preload F is applied to the third single row bearing 10 (FIG. 1A). The first preload F + α is arbitrarily set according to the internal specifications of the bearing unit J, the purpose of use, etc., and is not particularly limited in numerical value, but is generally F × 1.3 to F × 1.5. What is necessary is just to set to about.

  As described above, according to the present embodiment, the preload load of the first single row bearing 6 arranged between the shaft body 2 and the housing 4 is applied to the other two single row bearings (second single row bearings). The bearing 8 is set to a preload larger than that of the third single-row bearing 10), and the contact angle L1 of the first single-row bearing 6 is set to the contact angle L2, of the other two single-row bearings 8,10. By setting it larger than L3, the contact surface pressure between the rolling element 16 and the inner and outer rings 12, 14 can be kept low even if a larger preload is applied. Thereby, the preload of the whole bearing unit J can be increased. That is, the preload can be set larger than that of a bearing unit using three similar bearings.

  As a result, the bearing unit J of the present embodiment can drastically improve the radial rigidity as compared with the existing bearing unit using two similar bearings. In other words, the bearing unit J of the present embodiment has an existing bearing unit that uses four similar bearings while improving radial rigidity over an existing bearing unit that uses two similar bearings. Compared to the above, it is possible to suppress an increase in torque when the bearing rotates.

  Therefore, when the bearing unit J of the present embodiment is incorporated in an HDD device as shown in FIG. 3 and the swing arm 108 is rotatably supported, the swing arm 108 can be operated smoothly at high speed. it can. As a result, for example, the magnetic head 106 of the swing arm 108 can be scanned at high speed and smoothly with respect to the magnetic disk 102 having a recording track density of 300,000 TPI or more. As a result, the information recording or reading accuracy can be improved. It can be improved dramatically.

  Further, according to the bearing unit J of the present embodiment, since it is not necessary to increase the number of balls as in the conventional case, the number of parts of the bearing does not increase. Thereby, the low-cost bearing unit J is realizable.

  In addition, this invention is not limited to embodiment mentioned above, The following modifications can also be included in the scope of the present invention, and the same effect can be acquired. For this reason, in the following description, only the structure of this modification is demonstrated and description of the effect is abbreviate | omitted.

  FIG. 2 (a) shows a configuration of a bearing unit J according to a modification of the present invention. In the bearing unit J, the second single-row bearing 8 having a small contact angle L2 is connected to an outward flange on one end side. The third single-row bearings 10 having a small contact angle L3 are arranged on the other end side, and the first single-row bearing 6 having a large contact angle L1 is placed between the two bearings 8 and 10. Arranged.

  In such an arrangement, the second single row bearing 8 and the first single row bearing 6 adjacent to each other at one end side are arranged in a back face combination (DB) and the preload direction of both bearings 8 and 6 Are set in opposite directions. In this case, the preload load of the first single row bearing 6 with the large contact angle L1 is the sum of the preload loads of the second and third single row bearings 8 and 10 with the other two small contact angles L2 and L3. It is set almost the same. In other words, the preload of the first single row bearing 6 is set to approximately twice the preload applied to each of the second and third single row bearings 8 and 10. At this time, the preloads of the second and third single row bearings 8 and 10 may be set to substantially the same level.

  In addition, the preload direction of the first single row bearing 6 having a large contact angle L1 is set to be opposite to the preload directions of the second and third single row bearings 8 and 10. As a result, the second single row bearing 8 and the first single row bearing 6 are arranged in the rear combination (DB), and the first single row bearing 6 and the third single row bearing 10 are front combined. It will be arranged with (DF). The rear combination (DB) bearing and the front combination (DF) bearing have the ability to load radial loads and axial loads in both directions.

Next, an example of a method for assembling the bearing unit J of this modification will be described.
As shown in FIG. 2B, the second single-row bearing 8 having a small contact angle L2 is inserted between the shaft body 2 and the housing 4, and the inner ring 12 is in contact with the outward flange 2f. The shaft body 2 is bonded and fixed. At this time, the outer ring 14 of the second single-row bearing 8 is not moved and fixed to the housing 4 without being adhesively fixed.

  Subsequently, after the outer ring spacer 18 is inserted between the shaft body 2 and the housing 4 and brought into contact with the outer ring 14 of the second single row bearing 8, the first single row bearing 6 having a large contact angle L1. Is inserted between the shaft body 2 and the housing 4, and the outer ring 14 is brought into contact with the outer ring spacer 18. At this time, the radial internal clearance of the first single row bearing 6 is set to be larger than the other two single row bearings (second and third single row bearings 8 and 10) in advance.

  Subsequently, after the inner ring spacer 22 is inserted between the shaft body 2 and the housing 4 and brought into contact with the inner ring 12 of the first single row bearing 6, the third single row bearing 10 having a small contact angle L3 is used. Is inserted between the shaft body 2 and the housing 4, and the inner ring 12 is brought into contact with the inner ring spacer 22. In this state, a preload F + β is applied from the third single row bearing 10 side toward the outward flange 2f. At this time, the preload F + β is applied to the outer ring 14 of the third single row bearing 10, whereby the preload F + β is simultaneously applied to the three single row bearings 8, 6, 10.

  In this case, the preload load F + β is applied to the two single row bearings 8 and 10 having a small contact angle when the preload load is released and the preset residual preload load F is applied to the single row bearing 6 having a large contact angle. The residual preload is set to be larger than the residual preload F so that a residual preload twice as large as the residual preload is applied. More specifically, the outer ring 14 of the second single row bearing 8 is free to move along the housing 4, and the inner and outer rings 12, 14 of the first single row bearing 6 are connected to the shaft body 2. And it is in a state of movement free along the housing 4.

  In such a state, when a preload F + β is applied to the outer ring 14 of the third single-row bearing 10, the preload is transmitted from the rolling elements 16 to the inner ring 12, and then from the inner ring 12 to the inner ring spacer. It is transmitted to the inner ring 12 of the first single row bearing 6 through 22. Then, the preload transmitted to the inner ring 12 is transmitted from the rolling elements 16 to the outer ring 14 and then transmitted to the outer ring 14 of the second single row bearing 8 via the outer ring spacer 18. At this time, the inner and outer rings 12 and 14 of the third single-row bearing 10, the outer ring 14 of the second single-row bearing 8, and the inner and outer rings 12 and 14 of the first single-row bearing 6 are both the shaft body 2 and the housing 4. Will move by a predetermined amount.

  Then, while maintaining this state, the outer ring 14 of the third single row bearing 10 is bonded and fixed to the housing 4, and the inner ring 12 is bonded and fixed to the shaft body 2, and then the preload F + β is released. As a result, the first single row bearing 6 arranged in the center is given a preload that is approximately twice the preload F of the second and third single row bearings 8 and 10 (see FIG. 2 (a)). Note that the preload F + β is arbitrarily set according to the internal specifications of the bearing unit J, the purpose of use, and the like, and is not particularly limited in numerical values, but is generally set to about F × 1.3 to F × 1.5. Just do it.

2 shaft body 2 f outward flange 4 housing 6, 8, 10 single row bearing 12 inner ring 14 outer ring 16 rolling elements 18, 20 spacer

Claims (2)

A shaft body having an outward flange projecting on one end side and extending from the one end side toward the other end side;
A housing arranged to face the outside of the shaft body;
Comprising three first to third single row bearings arranged between the shaft body and the housing,
Second and third single row bearings are arranged on both sides of the first single row bearing,
Each single row bearing is a bearing unit including an inner ring and an outer ring, and a plurality of rolling elements that are rotatably incorporated between the inner and outer rings,
Between the second single row bearing and the first single row bearing, a spacer is interposed in a state where the outer rings are in contact with each other,
A spacer is interposed between the first single-row bearing and the third single-row bearing in a state of being in contact with the inner rings,
The inner ring of the second single row bearing is in contact with the outward flange,
The inner ring of the third single row bearing is adhesively fixed to the shaft body,
The second single row bearing and the first single row bearing are arranged in a rear combination,
The first single row bearing and the third single row bearing are arranged in a front combination.   2. The bearing unit according to claim 1, wherein a contact angle of the first single row bearing is set larger than contact angles of the second and third single row bearings.

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