JP2000144162A - Rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling bearing keeping low dusting property, low torque property and long life, controlled so that the acoustic deterioration becomes small and used for spindle motors of disk memory devices by forming the lubricating oil film of an ester-based lubricating oil whose kinematic viscosity is a prescribed value or above onto a friction surface. SOLUTION: This rolling bearing forms a lubricating oil film of an ester- based lubricating oil such as dioctyl adipate having >=35 mm2/s kinematic viscosity at 40 deg.C onto a friction surface. Furthermore, it is preferable that a rolling bearing comprising a ball bearing forming the above lubricating oil film on the frictional surface and having <=8 mm internal circumference diameter of inner ring is prepared and a rolling bearing in which grease is enclosed is prepared by enclosing grease into the rolling bearing and further, any of these rolling bearings is used for the rotating shaft for information equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rolling bearing. For details, see the hard disk drive (HD
D), a rolling bearing for a rotating shaft of information equipment such as a video tape recorder (VTR), a digital audio tape recorder (DAT), and a laser beam printer (LBP). More particularly, the present invention relates to a rotating shaft support structure of a disk storage device, and more particularly to a spindle motor in a disk storage device such as a compact disk such as a CD-ROM and a DVD, a hard disk drive (HDD), and a high capacity floppy (registered trademark) disk drive. .

[0002]

2. Description of the Related Art Generally, lubricating oil or a combination of lubricating oil and a semi-solid lubricating oil such as grease, or only grease is used for lubricating rolling bearings used in information equipment. With the miniaturization and high performance of information equipment, the acoustic level required for bearings for rotating shafts is becoming stricter year by year.

For example, a bearing described in Japanese Patent Application Laid-Open No. 8-283767 has a kinematic viscosity at 40 ° C. of 10 mm ² / s.
It is described that the use of the lubricant composition containing the above ester oil as an essential component shows excellent acoustic characteristics under high temperature and high speed rotation.

FIG. 1 shows a structure for supporting a rotating shaft of a general hard disk drive (hereinafter abbreviated as HDD). This support structure has two rotation shafts: a rotation shaft 3 that rotatably supports the magnetic disk 2 via a hub 1 and a rotation shaft 5 of an arm 4 having a magnetic head (not shown) attached to the tip. The rotating shafts 3 and 5 are supported by a pair of ball bearings 6 and 7 arranged at an interval in the axial direction.

The inner ring 8 of a set of ball bearings 6 supporting the rotating shaft 3 of the magnetic disk 2 is mounted so as to rotate integrally with the rotating shaft 3, and the outer ring 9 is attached to the cylindrical stator 11 of the spindle motor 10. And fixed to the inner periphery of the
, The rotating shaft 3 is fixed to the center of the shaft and the rotating shaft 3 is rotated by the spindle motor 10.

[0006] The magnetic disk 2 rotatably supported by such a rotating shaft support structure is provided with a spindle motor 1.
The arm 4 rotates at a high speed in accordance with the rotation speed of 0. At this time, an arm 4 (commonly called a swing arm) to which a magnetic head for reading and writing magnetic recording data is attached also operates appropriately.

The distal end of the arm 4 is supported on an upper part of a rotating shaft 5. The rotating shaft 5 is rotated around the axis by an actuator composed of a coil or the like (not shown), and the tip of the arm 4 is turned by a required angle to magnetically rotate. Move the head to the required position. As described above, the rotation operation of the rotating shaft 5 makes it possible to read and write required magnetic recording data in the effective recording area of the magnetic disk 2.

A conventional rolling bearing for supporting a rotating shaft of an HDD is a high-precision small ball bearing (miniature ball bearing: JI).
SB 0104 “Ball bearing with an outer diameter of less than 9 mm”) is used, and at least the dimensional accuracy and rotational accuracy are determined by JI
S5 grade or higher is used.

[0009]

However, the bearing described in Japanese Patent Application Laid-Open No. 8-283767 has low dust emission, low torque, and good acoustic characteristics even under high temperature and high speed rotation. Although it is described that the service life can be extended, the selection of lubricating oil is not sufficient because acoustic degradation under high-speed rotation is not sufficiently considered. Normally, if the bearing is rotated for a certain period of time under high-speed rotation, it becomes difficult to form a good oil film, so that the sound level after a certain period of operation becomes worse than the initial sound level. Therefore, if the type and the kinematic viscosity of the lubricating oil are not limited, there is a possibility that the sound level is considerably deteriorated by operating for a certain period of time under high-speed rotation.

[0010] Accordingly, an object of the present invention is to provide a rolling bearing which solves the above-mentioned problems and exhibits low dust generation, low torque, and long life equivalent to or higher than conventional ones, while suppressing acoustic deterioration. It is to be.

[0011]

In order to solve the above-mentioned problems, the present invention forms a lubricating oil film of an ester-based lubricating oil having a kinematic viscosity at 40 ° C. of 35 mm ² / s or more on a friction surface of a rolling bearing. It was done. Further, a lubricating oil film of an ester lubricating oil having a kinematic viscosity at 40 ° C. of 35 mm ² / s or more at 40 ° C. can be formed from a ball bearing having an inner ring with an inner peripheral diameter of 8 mm or less. Further, grease can be sealed.

In a rolling bearing using such an ester oil as a lubricating oil, it is possible to minimize the acoustic deterioration under high-speed rotation.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The lubricating oil used in each invention of the present application is:
Consisting of ester lubricating oil, the main component ester oil is diester oil obtained from the reaction of dibasic acid and branched alcohol, aromatic ester oil obtained from the reaction of aromatic tribasic acid and branched alcohol, and polyhydric alcohol. The hindered ester oil obtained from the reaction of the monobasic acid is suitably used, and is not particularly limited.

As diester oils, dioctyl adipate (DOA), diisobutyl adipate (DIB),
Examples include dibutyl adipate (DBA), dioctyl azelate (DOZ), dibutyl sebacate (DBS), dioctyl sebacate (DOS), methyl acetyl ricinoleate (MAR-N), and the like.

The aromatic ester oil includes trioctyl trimellitate (TOTM), tridecyl trimellitate, tetraoctyl pyromellitate and the like.

Examples of the hindered ester oil include those obtained by reacting a polyhydric alcohol shown below with a monobasic acid.

The monobasic acid reacted with the polyhydric alcohol may be used alone or in combination. Further, a polyhydric alcohol and a dibasic acid / monobasic acid may be used as a complex ester which is a mixed fatty acid and an oligoester.

Examples of polyhydric alcohols include trimethylolpropane (TMP), pentaerythritol (PE),
Dipentaerythritol (DPE), neopentyl glycol (NPG), 2-methyl-2-propyl-1,3
-Propanediol (MPPD) and the like.

The monobasic acid is mainly a monovalent fatty acid having 4 to 22 carbon atoms, and examples thereof include the following. Specific examples include acetic acid, valeric acid, caproic acid,
Caprylic acid, enanthic acid, pelargonic acid, capric acid,
Undecanoic acid, lauric acid, myristic acid, palmitic acid, bovine fatty acid, stearic acid, caproleic acid, undecylenic acid, lindelic acid, tuzuic acid, fisthenic acid, myristoleic acid, palmitoleic acid, petroselinic acid, oleic acid, elaidic acid, Ascrepic acid, vaccenic acid, sorbic acid, linoleic acid, linolenic acid, sabinic acid, ricinoleic acid, nonadecanoic acid, arachinic acid, heneicosanoic acid, behenic acid, brassic acid, erucic acid and the like.

The ester-based lubricating oil used in the present invention comprises 4
The kinematic viscosity at 0 ° C. is 35 mm ² / s or more, more preferably 40 mm ² / s or more. Kinematic viscosity at 40 ° C is 35mm
^When the ester-based lubricating oil is less than ² / s, the lubricating oil film is not sufficiently formed at the initial stage of rotation of the bearing under high-temperature and high-speed rotation, and the lubricating oil film is interrupted to lower the bearing acoustic level.

The upper limit of the kinematic viscosity at 40 ° C. of the ester lubricating oil can be changed so as to be suitable for workability in handling such as bearing filling or oil plating. Bearing oil grades can be used. In consideration of the viscosity grade of general bearing oils, the upper limit of the kinematic viscosity of the ester lubricating oil used in the present invention is 150 mm ² / s at 40 ° C.
It is.

In order to supply the above-mentioned ester-based lubricating oil to the friction surface of the rolling bearing to form a lubricating oil film, the lubricating oil may be dropped on the race surfaces of the inner and outer races and the rolling elements. Oil plating may be performed by immersing the oil in a solution diluted with a solvent at an appropriate concentration to form a uniform film on the bearing surface.

The ester-based lubricating oil may contain known additives such as a rust preventive, an antioxidant and an oiliness improver.

Incidentally, rust preventives which can be used by being added to the lubricating oil include barium sulfonate and calcium sulfonate which are organic sulfonic acid metal salts. And a phenolic antioxidant alone or as a mixture of both. Examples of the nitrogen compound-based antioxidant include phenyl α-naphthylamine, diphenylamine, phenylenediamine, oleylamideamine, and phenothiazine.

The phenolic antioxidants include:
p-tert-butylphenisallate, 2,6-di-
tert-butyl-p-phenylphenol, 2,2 ′
-Methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-methyl-6
-Tert-octylphenol), 4,4'-butylenebis (6-tert-butyl-m-cresol),
Tetrakis [methylene-3-3 (3 ', 5'-di-te)
rt-butyl-4'-hydroxyphenyl) propionate] methane, 1,3,5-trimethyl-2,4,6-
Tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, n-octadecyl-β- (4 ′
-Hydroxy-3 ', 5'-di-tert-butyl) phenoxy-1,3,5-triazine, 4,4'-thiobis- [6-tert-butyl-m-cresol], 2-
(2′-hydroxy-3′-tert-butyl-5′-
Hindered phenols such as methylphenyl) -5-chlorobenzotriazole.

As oiliness improvers, higher fatty acids such as oleic acid and stearic acid, and higher alcohols such as
Examples of amines include stearylamine and cetylamine, such as lauryl alcohol and oleyl alcohol, and examples of phosphate esters include tricresyl phosphate.

Further, extreme pressure agents, viscosity index improvers, abrasion inhibitors and the like may be added to the composition other than the above-mentioned compositions as long as the effects are not impaired. If the durability is insufficient with lubricating oil alone, it is also possible to enclose grease to such an extent that the rotational torque does not increase or falls within an allowable range.

The rolling bearing of the present invention may have a known structure, and holds a plurality of rolling elements via a retainer between the inner and outer rings. A specific example is a ball bearing. In particular, when a lubricating oil film of the above-mentioned ester-based lubricating oil is formed on the friction surface, the acoustic effect of the bearing is considerably suppressed. Therefore, in the related art, a ball bearing having an inner ring with an inner radius of 8 mm or less, which has been difficult to suppress the acoustic effect. Can be used. The ball bearing that can be used is not particularly limited as long as it can be manufactured, and the lower limit of the inner peripheral radius of the inner ring of the current ball bearing is 1 mm.

The material of the cage incorporated in such a bearing may be a known material such as an iron plate, a polyamide resin containing glass fibers or whiskers, or an oil-containing resin containing lubricating oil. In consideration of acoustic characteristics so as not to generate noise, it is preferable to use a resin cage.

Incidentally, such a bearing is provided with a seal.
A device may be attached. When this sealing device is attached,
Grease can be sealed in this bearing. Grease is filled in between the inner ring and outer ring, the inner ring,
There are gaps generated in the bearing between the outer ring and the rolling element, between the inner ring, the outer ring and the retainer, between the inner ring, the outer ring, the rolling element and the retainer, and the like.

The rolling bearing according to the present invention includes a hard disk drive (HDD), a video tape recorder (VTR), and a digital audio tape recorder (DA).
T), which can be used as a rotation axis of information equipment used as a rotation axis of information equipment such as a laser beam printer (LBP). Further, it can be used for supporting a compact disk such as a CD-ROM and a DVD, a disk rotating shaft of a disk storage device such as an HDD and a high-capacity floppy disk drive, and the like.

More specifically, the HDD has a rotating shaft that supports the magnetic disk and a rolling bearing that rotatably supports the rotating shaft. The rolling bearing according to the present invention is used as the rolling bearing. be able to. At this time, the lubricating oil film is preferably formed on the friction surface of the rolling bearing.

The HDD has a rotating shaft for supporting an arm having a magnetic head and a rolling bearing for rotatably supporting the rotating shaft. The rolling bearing according to the present invention is employed as the rolling bearing. be able to. At this time, the lubricating oil film is preferably formed on the friction surface of the rolling bearing.

[0034]

[Example 1] As an ester-based lubricating oil, manufactured by NOF Corporation: Unistar H381R (kinematic viscosity at 40 ° C 4
² mg of 8.3 mm ² / s) was dropped on the raceway, and 8.5 mg of grease (Multemp SRL, manufactured by Kyodo Yushi Co., Ltd.) was encapsulated in the miniature ball bearing (bearing size: φ5 × φ13 ×).
3 (mm), eight inner rings, outer rings, and rolling elements of bearing steel, and eight cages of polyamide 66 resin reinforced with glass fiber) were prepared.

Each of the bearings is moved in the axial direction as follows.
A preload of 6 kgf was applied to the spindle. This spindle was placed in a constant temperature bath at 70 ° C.
Rotation was performed at 00 rpm, and a 135-hour durability test was performed. Remove the bearing after the test and add 0.8
Apply an axial load of kgf to 30 at 1800 rpm
After running for 2 seconds, the vibration value G was measured. Table 1 shows the ratio (vibration value after test / vibration value before test) between the bearing vibration value after the durability test and the vibration value of a single bearing measured before the durability test.
It was shown to. The values in Table 1 are average values of eight bearings.

Example 2 In Example 1, Unistar H481R (4
A rolling bearing was manufactured in exactly the same manner except that a kinematic viscosity at 0 ° C. of 64.2 mm ² / s) was used, a durability test was performed under the same conditions, vibration values before and after the test were measured, and the ratio was determined. The results are shown in Table 1.

Example 3 A rolling bearing was manufactured in exactly the same manner as in Example 1 except that the ester lubricating oil used was Rheolove OTM (kinematic viscosity at 40 ° C .: 80 mm ² / s) manufactured by FMC. An endurance test was performed under the same conditions, and vibration values before and after the test were measured.

[Comparative Example 1] In Example 1, an ester-based lubricating oil manufactured by FMC: Leo Lube LPE602 (4
A rolling bearing was manufactured in exactly the same manner except that a kinematic viscosity at 0 ° C. of 33.5 mm ² / s) was used, a durability test was performed under the same conditions, vibration values before and after the test were measured, and the ratio was measured. The results are shown in Table 1.

Comparative Example 2 In Example 1, Nippon Steel Chemical's Synfluid 601 (kinematic viscosity at 40 ° C. of 30.5 m
m ² / s), a rolling bearing was manufactured in exactly the same manner, a durability test was performed under the same conditions, vibration values before and after the test were measured, and the ratio was shown in Table 1.

Comparative Example 3 In Example 1, Nippon Steel Chemical's Synfluid 801 (a kinematic viscosity at 40 ° C. of 46.0 m) of a poly-α-olefin oil instead of an ester oil as a lubricating oil was used.
m ² / s), a rolling bearing was manufactured in exactly the same manner, a durability test was performed under the same conditions, vibration values before and after the test were measured, and the ratio was shown in Table 1.

Comparative Example 4 A rolling bearing was manufactured by filling 9.5 mg of grease (Multemp SRL, manufactured by Kyodo Yushi Co., Ltd.) in the miniature ball bearing in Example 1 instead of the ester-based lubricating oil. Perform a durability test under the conditions,
The vibration values before and after the test were measured, and the ratios are shown in Table 1.

[0042]

[Table 1]

From the results shown in Table 1, when the ester-based lubricating oil of Comparative Example 1 having a kinematic viscosity at 40 ° C. of 33.5 mm ² / s is used, if the initial vibration value is 1, a predetermined condition is obtained. By performing the endurance test, the vibration value becomes about 2.3 times the initial value. Further, as shown in Comparative Examples 2 and 3, when the poly-α-olefin oil was used as the lubricating oil instead of the ester oil, the vibration value was about twice the initial value. In the case of Comparative Example 4 using grease instead of lubricating oil, the vibration value is about 2.3 times the initial value.

On the other hand, when the ester-based lubricating oil having a kinematic viscosity at 40 ° C. of 35 mm ² / s or more at 40 ° C. in Examples 1 to 3 is used, if the initial vibration value is 1, a predetermined condition is obtained. By performing the endurance test, the vibration value becomes about 1.6 times or less of the initial value.

Therefore, by using ester oil having a predetermined viscosity as a lubricating oil for a rolling bearing, acoustic deterioration of the bearing can be suppressed.

[0046]

As described above, each invention of the present application has the following features.
CD-R using ester-based lubricating oil in a predetermined viscosity range
An object of the present invention is to provide a rolling bearing used for a spindle motor in a disk storage device such as a compact disk such as OM and DVD, a hard disk drive (HDD), and a high-capacity floppy disk drive.

[0047] By using an ester-based lubricating oil having a predetermined viscosity range as a lubricating oil for a bearing, acoustic deterioration of the bearing can be considerably suppressed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a rotating shaft support structure of a hard disk drive.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hub 2 Magnetic disk 3, 5, 17 Rotation axis 4 Arm 6, 7 Ball bearing 8 Inner ring 9 Outer ring 10 Spindle motor 11 Cylindrical stator 12 Deep dish rotor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 19/20 G11B 19/20 E // C10N 20:02 30:00 40:02 40:18 (72) Inventor Hidenobu Mikami 3066 Oumida, Kuju-shi, Mie Prefecture, N.O., Ltd. (72) Inventor Masaki Egami 3066 Oumida, Oaza, Oogata, Kuwana-shi, Mie N.T.N.U. (72) Inventor, Takashi Anzai 3066 Oumita, Kuwana-shi, Fukushima Prefecture F-term (reference) in NTN Corporation 3J101 AA02 AA42 AA52 AA62 AA81 EA63 EA67 FA01 GA53 4H104 BB22B BB33A BB34A EA02A LA20 PA01 PA16 QA18 5D109 BB02 BB05 BB05

Claims (7)

[Claims] The friction surface has a kinematic viscosity at 40 ° C. of 35 mm.
^A rolling bearing formed by forming a lubricating oil film of ester lubricating oil of ² / s or more. 2. The friction surface has a kinematic viscosity at 40 ° C. of 35 mm.
A rolling bearing which is a ball bearing having a lubricating oil film of an ester lubricating oil of ² / s or more and an inner ring having an inner peripheral diameter of 8 mm or less. 3. A grease-filled rolling bearing in which grease is sealed in the rolling bearing according to claim 1. 4. A rolling bearing for an information equipment rotating shaft, wherein the rolling bearing according to claim 1 or 2 or the grease-enclosed rolling bearing according to claim 3 is used for an information equipment rotating shaft. 5. An information device using one of the rolling bearing according to claim 1 and 2 and the grease-enclosed rolling bearing according to claim 3 for supporting a disk rotating shaft of a disk storage device of the information device. Rolling bearing for supporting the disk rotating shaft of the disk storage device. 6. A lubricating oil film comprising: a rotating shaft for supporting a magnetic disk; and the rolling bearing according to claim 2, which rotatably supports the rotating shaft; or the grease-enclosed rolling bearing according to claim 3, Is a hard disk drive device formed on the friction surface of the rolling bearing. 7. A rolling shaft for supporting an arm having a magnetic head, and the rolling bearing according to claim 2 for rotatably supporting the rotating shaft, or a grease-sealed rolling bearing according to claim 3, A hard disk drive device wherein the lubricating oil film is formed on a friction surface of the rolling bearing.