JP2000198993A - Rolling bearing and grease for rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a lubricating grease from flying about even under centrifugal force, prevent insufficient lubrication from occurring in a bearing, stabilize rotation under a low torque, and improve the durability of a bearing by using a lubricating grease which has a specified mixing consistency and is prepared by compounding a base oil containing an ester oil having a specified kinematic viscosity with a fatty acid lithium salt having a specified number of carbon atoms as a thickening agent. SOLUTION: A lubricating grease which has a mixing consistency adjusted to 175-250 and is prepared by compounding a base oil containing at least 30 wt.% ester oil having a kinematic viscosity at 40 deg.C of 10 mm2/s or higher with a 12-24C fatty acid lithium salt as a thickening agent is used. Diester oils (e.g. dioctyl adipate) and aromatic ester oils (e.g. trioctyl trimellitate) are examples of the ester oil. A 12-24C fatty acid lithium salt (e.g. lithium stearate) is used as the thickening agent. The mixing consistency is measured according to JIS K 2220.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rolling bearing, a grease for a rolling bearing, and a small-diameter high-speed rolling bearing.
Rolling bearings and greases for rolling bearings, or hard disk drives (HDDs) that can be applied particularly to home appliances such as air conditioners requiring low-noise, long-time rotation characteristics, and vacuum cleaners, washing machines, etc., which require durability. The present invention relates to a small-diameter, high-speed rolling bearing applicable to a recording / reproducing device for electronic information such as.

[0002]

2. Description of the Related Art Generally, rolling bearings used in household electric appliances such as vacuum cleaners, washing machines, and air conditioners (air conditioners) are required to suppress driving noise during rotation and have a quietness.
A bearing that does not generate noise even when used for a long time is required.

Further, recently developed magnetic recording / reproducing devices such as a hard disk drive (HDD) and a video tape recorder (VTR), and a laser beam printer (LB)
P) and other printing equipment, compact disc (CD), C
D-ROM, digital video disk (DVD), DV
Rolling bearings for D-ROMs and other recording / reproducing devices for electronic information and the like are required to have lower torque in order to reduce power consumption in response to demands for downsizing these devices.

Conventionally, rolling bearings having a small diameter and rotating at high speed, such as miniature bearings used in the above devices,
Alternatively, lubricating oil or lubricating grease has been used for lubrication of other rolling bearings.

[0005] Incidentally, as a cause of generating noise in a rolling bearing mounted on a recording / reproducing apparatus for home electric appliances and electronic information, poor lubrication due to lack of lubricant on a rolling surface is expected. The state can also be inferred from the presence or absence of fluctuations in the bearing rotation torque.

Further, the lubricating grease held in the rolling bearing has lubrication (stirring) resistance depending on the consistency and applies a required torque to the rotating shaft to fluctuate the torque. In addition, a lubricating composition for reducing dust generation and prolonging life even at high speed rotation is disclosed in
No. 83767 discloses that the kinematic viscosity at 40 ° C. is 10 mm ^2.
A lubricant composition containing an ester oil of at least / s as an essential component is disclosed.

[0007]

However, in order to reduce the rotational torque of the rolling bearing, a very small amount of the above-mentioned conventional lubricant composition is applied or filled in the rolling bearing and used. Therefore, there is a problem that insufficient lubrication is likely to occur even if a very small amount of lubricant is scattered by centrifugal force.

[0008] When lubricating grease flows out from the friction surface of the rotating rolling bearing and the lubrication becomes insufficient, the rotational torque of the bearing rapidly increases and noise is generated from the friction surface of the home electric appliance.

[0009] Incidentally, as a cause of noise generated in the rolling bearing, poor lubrication due to lack of lubricant on the rolling surface is expected, and the state can be inferred from the presence or absence of fluctuations in the bearing rotation torque.

Further, when lubricating oil is insufficient on the friction surface of a small-diameter high-speed rolling bearing of a recording / reproducing apparatus for electronic information or the like rotating at a high speed, noise is generated almost at the same time, and the rotational torque of the bearing rapidly increases, and the recording / reproducing of electronic information or the like occurs. This has an adverse effect on the precision mechanism of the playback device, and reduces the reliability of recording and playback of electronic information.

An object of the present invention relating to the rolling bearing and the grease for a rolling bearing of the present invention is to solve the above-mentioned problem and to prevent the rolling bearing from generating noise at a stable low torque without causing insufficient lubrication during rotation. It is an object of the present invention to provide a rotating rolling bearing and to extend the service life of the rolling bearing of this type (extending the service life).

Another object of the present invention relating to a small-diameter high-speed rolling bearing according to the present invention is to solve the above-mentioned problems, and to provide a small-diameter high-speed rolling bearing used for an electronic information recording / reproducing device or the like by a centrifugal force during high-speed rotation. Make grease difficult to scatter,
It is an object of the present invention to prevent malfunction and noise when a small-diameter high-speed rolling bearing is used in electronic information equipment and to prolong the service life of this type of rolling bearing.

[0013]

Means for Solving the Problems In order to solve the above-mentioned problems, in the invention relating to the rolling bearing of the present invention, the rolling bearing is provided with a penetration consistency (JIS K2220) of 175.
A rolling bearing holding lubricating grease adjusted to 250 or a small-diameter high-speed rolling bearing having an inner diameter of less than 10 mm was provided.

Further, in order to solve the above-mentioned problem, in the invention relating to the lubricating grease of the present application, the mixing penetration (J
IS K2220) was adjusted to 175 to 250 to provide a grease for a rolling bearing made of lubricating grease.

[0015] The lubricating grease held by the above-mentioned rolling bearing is provided with a 4 g in order to more reliably achieve the object of the present invention.
The lubricating grease was obtained by mixing a thickening agent made of lithium soap or urea with a base oil containing an ester oil having a kinematic viscosity of 10 mm ² / s or more at 0 ° C.

Further, the lubricating grease held by the rolling bearing is a base oil containing 30% by weight or more of an ester oil having a kinematic viscosity at 40 ° C. of 10 mm ² / s or more. And a mixing consistency (JISK2220) of 175 to 25
Lubricant grease adjusted to zero is preferred.

The lubricating grease whose mixing consistency is adjusted to a predetermined range maintains a predetermined consistency even when it is agitated in a rotating rolling bearing and is subjected to shearing. Therefore, the lubricating grease hardly scatters or flows out of the bearing. The lubrication becomes difficult and there is no lack of lubrication in the bearing.

The kinematic viscosity at 40 ° C. is 10 mm ²
Lubricating grease employing a base oil containing preferably at least 30% by weight of an ester oil of at least 30 g / s, the lubricating oil (base oil) supplied from the grease to the friction surface has a predetermined kinematic viscosity,
Since the lubricating oil film is formed on the friction surface with a required thickness, the rotation state of the rolling bearing of home electric appliances and the like, especially the small-diameter high-speed rolling bearing of 10,000 rpm used for the recording / reproducing apparatus of electronic information, etc.
The lubricating property in a high-speed rotation state exceeding m is improved, and has an effect of stabilizing the bearing rotation torque low.

The lubricating grease containing a thickener containing at least 50% by weight of a fatty acid lithium salt having 12 to 24 carbon atoms has a sufficiently high consistency at high temperatures.

[0020] The small-diameter high-speed rolling bearing according to the invention of the present application comprises:
Since the lubricating grease hardly scatters or flows out, the lubricating grease rotates at a stable low torque without generating noise at the time of high-speed rotation without insufficient lubrication. In addition, due to the action of the lubricating grease, the noise of the rolling bearing is prevented, the durability of the rolling bearing is increased, and the use of this type of rolling bearing in an electronic information recording / reproducing device allows the recording / reproducing of electronic information. Errors are prevented.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION A rolling bearing used in each invention of the present application usually has a number of rolling elements formed of "rollers" or "balls" between an inner ring and an outer ring, and has a radial direction of a rotating shaft. Alternatively, it is a rolling bearing that is supported in the thrust direction or in both directions, and the spacing between the rolling elements is arranged by a retainer. Incidentally, a recording / reproducing apparatus for electronic information or the like usually has an inner diameter of a bearing of less than 10 mm and an outer diameter of 3 to 10 mm.
Rolling bearings of about 30 mm are often used, and such bearings include miniature bearings.

The grease base oil used in each invention of the present application is:
Heating may occur when used at a rotation speed of 3000 to 10000 rpm in home electric appliances, or when used in high-speed rotation conditions exceeding 10,000 rpm in a rolling bearing in a recording / reproducing device for electronic information or the like. As long as it has a heat resistance that satisfies the use limit temperature set above such a temperature. Normally, the base oil can be used without any limitation, but preferred examples that can withstand heating at about 100 ° C. include ester lubricating oils, synthetic hydrocarbon oils, and ether oils.

The types of the above-mentioned ester lubricating oils include, for example, diester oils obtained from the reaction of dibasic acids and branched alcohols, aromatic ester oils obtained from the reaction of aromatic tribasic acids and branched alcohols, and polyhydric alcohols. And a polyol ester oil obtained from the reaction of monobasic acid.

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

Examples of the aromatic ester oil include trioctyl trimellitate (TOTM), tridecyl trimellitate, tetraoctyl pyromellitate and the like.

Examples of the polyol ester oil include those obtained by reacting a polyhydric alcohol shown below with a monobasic acid. The monobasic acid to be 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 of a mixed fatty acid and an oligoester.

Examples of the polyhydric alcohol ester include trimethylolpropane (TMP), pentaerythritol (PE), dipentaerythritol (DPE), neopentyl glycol (NPG), 2-methyl-2-propyl-1,3-propane. Diol (MPPD) and the like.

The monobasic acid is mainly a monovalent fatty acid having 4 to 18 carbon atoms, and specific examples are acetic acid, valeric acid,
Caproic acid, caprylic acid, enanthic acid, pelargonic acid,
Capric acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, tallow acid, stearic acid, caproleic acid, undecylenic acid, lindelic acid, tuzic acid, fisthenic acid, myristoleic acid, palmitoleic acid, petroseric acid, oleic acid, Examples include elaidic acid, ascrepic acid, vaccenic acid, sorbic acid, linoleic acid, linolenic acid, sabininic acid, and ricinoleic acid.

Examples of the synthetic hydrocarbon oil include poly-α-olefin oils, and co-oligomer synthetic oils of α-olefin and ethylene.

As ether oils, diphenyl, trif
Phenyl, C of tetraphenyl₁₂~ C ₂₀The (di) alkyl
Phenyl ether oils into which groups have been introduced are preferred.

The conditions for the kinematic viscosity of the base oil used in the present invention are as follows:
At 40 ° C., it is 10 mm ² / s or more. With an ester-based lubricating oil having a kinematic viscosity at 40 ° C. of less than 10 mm ² / s, a sufficient lubricating oil film is not formed at the beginning of rotation of the bearing, and the lubricating oil film is interrupted. The upper limit of the kinematic viscosity of the base oil used in the present invention is 200 mm ² / s or less at 40 ° C., preferably 150 mm ² / s or less at 40 ° C., and more preferably 100 mm ² / s at 40 ° C. in consideration of the torque of the rotating shaft. ² / s or less.

Suitable thickeners for use in the present invention include lithium soap and urea.
This is blended so as to have a predetermined mixing consistency.

Examples of the lithium soap include lithium laurate (C ₁₂ ), lithium myristate (C ₁₄ ), lithium palmitate (C ₁₆ ), lithium margarate (C ₁₇ ), lithium stearate (C ₁₈ ), and arachidine. acid (C ₂₀₎ lithium, behenic acid (C ₂₂₎ lithium, lignoceric acid (C _24), lithium tallow fatty acid, 9-
Lithium hydroxystearate, 10-lithium hydroxystearate, lithium 12-hydroxystearate, lithium 9,10-hydroxystearate,
Examples thereof include lithium ricinoleate and lithium ricinoelaidate. Among these, particularly preferred lithium soaps are lithium stearate and lithium 12-hydroxystearate. When other thickeners are used in addition to lithium soap, the lithium soap is added to 50% by weight or more of the total amount of the thickener. It is preferable to mix them.

The urea as a thickener is represented by the following chemical formula 1.
A well-known diurea or polyurea represented by the formula can be used.

[0035]

Embedded image

Wherein R ₂ is an aromatic hydrocarbon group, an aliphatic hydrocarbon group or an alicyclic hydrocarbon group having 6 to 15 carbon atoms, and R ₁ and R ₃ are each a group having 6 to 15 carbon atoms. 12 represents any of an aromatic hydrocarbon group, a cyclohexyl group, a cyclohexyl derivative having 7 to 12 carbon atoms, and an alkyl group having 6 to 20 carbon atoms.) The penetration of the lubricating grease used in the present invention (JIS)
K2220) is 175 to 250. When the mixing penetration is less than 175, the bearing torque of the rolling bearing holding the mixing penetration becomes large, and it becomes difficult to seal the lubricating grease in a rolling bearing, particularly a small-diameter rolling bearing. On the other hand, if the mixing penetration exceeds 255, lubrication is insufficient in the rolling bearing during rotation, particularly at high speed rotation, and noise is generated in the rolling bearing rotating at high speed.

The grease of the present invention may contain known additives such as a rust preventive, an antioxidant, an extreme pressure additive and a wear inhibitor so as not to impair the intended purpose.

Incidentally, rust preventives include organic sulfonic acid metal salts and esters. Among these, organic sulfonic acid salts include metal salts such as dinonylnaphthalene sulfonic acid and heavy alkylbenzene sulfonic acid. Specific examples include calcium sulfonate, barium sulfonate, sodium sulfonate and the like.

Examples of the esters include sorbitan monolaurate, sorbitan trilaurate, sorbitan monostearate, and sorbitan monooleate, which are partial esters of polybasic carboxylic acids and polyhydric alcohols of sorbitan derivatives.

Examples of the antioxidant include a nitrogen-containing compound-based antioxidant and a phenol-based antioxidant, each of which is used alone or in combination. Examples of nitrogen compound antioxidants include phenyl α-naphthylamine, diphenylamine, phenylenediamine, oleylamideamine,
Phenothiazine and the like. Examples of the phenolic antioxidant include p-tert-butylphenisalicylate, 2,6-di-tert-butyl-p-phenylphenol, and the like.

[0041]

EXAMPLES Examples 1-4, Comparative Examples 1-3 Lubricating greases were prepared by mixing base oils, thickeners and additives in the proportions shown in Table 1. In addition, each compounding component in a table | surface is a content (weight%) when the whole composition is made into 100 weight%.
It is.

With respect to the obtained lubricating grease (Examples 1 to 4, Comparative Examples 1 to 3), the following bearing acoustic measurement test (1)
A bearing acoustic measurement test (2) was performed, and the results are shown in Table 1.

<Bearing Acoustic Measurement Test (1)> 608 bearing filled with lubricating grease (deep groove ball bearing, dimensions: inner diameter 8 mm,
Two spindles (outer diameter: 22 mm) were assembled into one spindle, and the spindle was driven to rotate at a bearing rotation speed of 8000 rpm, an ambient temperature of 100 ° C., and an axial load of 3 kgf. Under these rotation conditions, a noise value (dBA) was measured every 200 hours in accordance with JIS B1548-1960. When the noise value was less than 42 dBA at each measurement, the bearing was rotated again under the same conditions, and the noise value after 200 hours was measured. The same measurement was repeated until the noise value reached 42 dBA, and the time when the noise value finally reached 42 dBA was examined. The results were evaluated on a four-point scale as described below, and the notation is also shown in Table 1. ◎: The time to reach 42 dBA is 2,000 hours or more. 印: The time to reach 42 dBA is 1200 to less than 2000 hours. 印: The time to reach 42 dBA is 400 to 1200 hours. X: The time to reach 42 dBA. But less than 400 hours

<Bearing Sound Measurement Test (2)> A 684 bearing filled with lubricating grease (deep groove ball bearing, dimensions: inner diameter 4 mm,
Two pieces (outer diameter 9 mm) were assembled into one spindle, and this spindle was driven to rotate at a bearing rotation number of 20,000 rpm, an ambient temperature of 100 ° C., and an axial load of 0.8 kgf. Under these rotation conditions, JIS B1548-1960
The noise value (dBA) was measured every 100 hours in accordance with. If the noise value is less than 42 dBA at each measurement,
The bearing was rotated again under the same conditions, and the noise value after 100 hours was measured. The same measurement is repeated until the noise value reaches 42 dBA.
Was reached. The result is 4
The results were evaluated on a scale and the notation is also shown in Table 1.印: Time to reach 42 dBA is 500 hours or more ○: Time to reach 42 dBA is 300 hours or more 5
Less than 00 hours △: Time to reach 42 dBA is 100 hours or more 3
Less than 00 hours x mark: Time to reach 42 dBA is less than 100 hours

[0045]

[Table 1]

As is clear from the results of the bearing acoustic measurement test (1) in Table 1, the mixing penetration was 265 or more (consistency).
The lubricating greases of Comparative Examples 1 to 3 of No. 2) had a test time of 4
In less than 00 hours or less than 1200 hours, a noise reaching 42 dBA was generated from the bearing, and it was recognized that excess lubricating oil was separated and the lubricating grease was consumed in a short time, and the lubricating grease was depleted.

On the other hand, in the same test, in the lubricating greases of Examples 1 to 4 having the admixing penetration of 175 to 250 (consistency No. 3 to 4), the time when the noise value of the bearing reached 42 dBA was obtained. It is 2,000 hours or more, which is recognized as prolonging the life of the rolling bearing without generating noise, suppressing the noise of home electric appliances and the like and prolonging the service life.

Further, as is clear from the results of the bearing acoustic measurement test (2) in Table 1, the lubricating greases of Comparative Examples 1 to 3 having a mixing consistency of 265 or more (consistency No. 2) had a test time of It was recognized that noise reaching 42 dBA was generated from the bearing rotating at high speed in less than 100 hours, less than 300 hours or less than 500 hours, and the lubricating grease was scattered by the centrifugal force during high-speed rotation and a sufficient lubricating oil film was not formed on the friction surface. Can be

On the other hand, the mixing consistency was 175 to 2
The lubricating grease of Examples 1 to 4 having a consistency number of 50 (consistency No. 3 to 4) had a time when the noise value of the bearing reached 42 dBA for 5 days.
It is more than 00 hours, and it is recognized that the service life of the rolling bearing has been prolonged and the malfunction and noise of the recording / reproducing apparatus for electronic information and the like have been suppressed.

[0050]

As described above, according to the present invention, lubricating grease having a predetermined mixing consistency is unlikely to be scattered even when a centrifugal force acts during rotation of a rolling bearing, and insufficient lubrication does not occur in the bearing. Rolling bearings of this type used in home appliances and recording / reproducing devices for electronic information, etc., rotate at high speed without causing insufficient lubrication, rotating at a stable low torque and without generating noise. There is an advantage that it becomes a good rolling bearing.

A rolling bearing holding the lubricating grease employing a base oil having a predetermined kinematic viscosity stably forms a lubricating oil film, improves lubricity, and more reliably achieves the above effects.

In each of the above-mentioned inventions using a lubricating grease containing lithium soap or urea as a thickener, particularly a lubricating grease containing a thickener containing a predetermined amount of a lithium fatty acid salt, the heat-resistant and high-speed rotating The lubricating grease is less likely to scatter even when the temperature of the bearing increases, and the rolling bearing is less likely to generate noise even at high temperatures.

Also, in the invention relating to the bearing grease, the mixing consistency is adjusted to a predetermined range, so that the lubricating grease separates the lubricating oil at an appropriate speed when the bearing rotates. It is possible to provide a lubricating grease that can prevent noise caused by the rolling bearing of the regenerating device and improve the acoustic characteristics and durability (life) of this type of rolling bearing.

The lubricating grease employing a base oil having a predetermined kinematic viscosity stably forms a lubricating oil film, and the above effects are more reliably achieved. In each of the above inventions using a lubricating grease containing lithium soap or urea as a thickener, particularly a lubricating grease containing a thickener containing a predetermined amount of a fatty acid lithium salt, a bearing having excellent heat resistance and high-speed rotation is used. Lubricating grease becomes difficult to scatter even when the temperature rises,
A grease for rolling bearings that does not easily generate noise even at high temperatures.

Further, in a small-diameter high-speed rolling bearing holding lubricating grease having a predetermined mixing consistency, the lubricating grease hardly scatters even when a centrifugal force is applied during high-speed rotation of the bearing, so that insufficient lubrication does not occur in the bearing. Rolling bearings of this type used in home appliances and recording / reproducing devices for electronic information and the like can be rotated at a stable low torque without generating noise and have good durability (life).

In the small-diameter high-speed rolling bearing holding the lubricating grease employing a base oil having a predetermined kinematic viscosity, the lubricity of the lubricating grease is improved because the lubricating oil film is formed stably.
It rotates without generating noise with more stable low torque,
Durability (lifetime) is surely improved.

Further, in the invention relating to the above-mentioned small-diameter high-speed rolling bearing using a lubricating grease containing lithium soap or urea as a thickener, particularly a lubricating grease containing a thickener containing a predetermined amount of a fatty acid lithium salt, Lubricating grease is excellent in heat resistance and hardly scatters even when the temperature of a bearing that rotates at high speed rises. Accordingly, such a small-diameter high-speed rolling bearing can be applied to a recording / reproducing device for electronic information and the like, and is a small-diameter high-speed rolling bearing capable of preventing malfunction of the device and noise in the device due to the rolling bearing.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C10N 40:02 50:10

Claims (9)

[Claims] Claims 1. A rolling penetration (JIS)
K2220) is a rolling bearing holding lubricating grease adjusted to 175 to 250. 2. The lubricating grease according to claim 1, wherein the lubricating grease is a base oil containing an ester oil having a kinematic viscosity of 10 mm ² / s or more at 40 ° C., and a thickener made of lithium soap or urea. Rolling bearing. 3. A rolling bearing in which lubricating grease is held in a rolling bearing, wherein the lubricating grease is obtained by adding a thickener to a base oil containing 30% by weight or more of an ester oil having a kinematic viscosity of 10 mm ² / s or more at 40 ° C. Has 12 or more carbon atoms
24 fatty acid lithium salts are blended and mixed with each other (JI
SK2220) is a lubricating grease adjusted to 175 to 250. 4. A grease for lubricating the inside of a rolling bearing, wherein the lubricating grease is mixed with a grease (JIS K22).
20) A grease for a rolling bearing, wherein grease is adjusted to 175 to 250. 5. The lubricating grease according to claim 4, wherein the lubricating grease is a base oil containing an ester oil having a kinematic viscosity at 40 ° C. of 10 mm ² / s or more, and a thickener made of lithium soap or urea. Grease for rolling bearings. 6. A grease for lubricating the inside of a rolling bearing, wherein the lubricating grease has a kinematic viscosity at 40 ° C. of 10 mm.
^In a base oil containing 30% by weight or more of an ester oil of ² / s or more, a fatty acid lithium salt having 12 to 24 carbon atoms was 50% by weight.
The thickener contained above is blended and mixed into a mixture (JI
(SK2220) adjusted to 175 to 250. A grease for rolling bearings. 7. A small-diameter, high-speed rolling bearing in which a lubricating grease having an adjusted penetration (JISK2220) adjusted to 175 to 250 is held in a rolling bearing having an inner diameter of less than 10 mm. 8. The lubricating grease according to claim 7, wherein the lubricating grease is obtained by mixing a thickening agent made of lithium soap or urea with a base oil containing an ester oil having a kinematic viscosity of 10 mm ² / s or more at 40 ° C. Small diameter high speed rolling bearing. 9. A small-diameter high-speed rolling bearing having lubricating grease held in a rolling bearing having an inner diameter of less than 10 mm, wherein the lubricating grease has a kinematic viscosity at 40 ° C. of 10 mm ² /
A thickener containing 50% by weight or more of a lithium salt of a fatty acid having 12 to 24 carbon atoms is blended with a base oil containing 30% by weight or more of an ester oil of at least 50% by weight, and a mixing consistency (JIS K).
2220) is a lubricating grease adjusted to 175 to 250, a small-diameter high-speed rolling bearing.