JPH10169661A - Cage for rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease as small as possible a dust generating amount during rotation of a cage for a rolling bearing used in a low pressure or vacuum, even under a condition of use at a high surface pressure, eliminate generation of gas in a lubricating oil source, form the rolling bearing cage of low dust generation or similarly of low dust generation, also rotate the cage by stable low torque, and form a vacuum use rolling bearing excellent in also durability. SOLUTION: A cage for a rolling bearing is formed of a porous unit of sintered material or the like consisting of a polyimide resin having a communication blow hole of 5 to 25% volumetric ratio, as a rolling bearing use holder impregnated with alkylated cyclopentane system oil as shown by a formula or as a vacuum use rolling bearing mounting this cage. In the formula, R represents alkyl group having a straight chain or branch of carbon number 4 to 130, m=3 to 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing retainer impregnated with lubricating oil and a vacuum rolling bearing to which the retainer is attached.

[0002]

2. Description of the Related Art Normally, a lubricant such as lubricating grease is held inside a rolling bearing.
The durability of the bearing is improved by reducing the coefficient of friction between the outer ring, the rolling elements and the cage.

As such a lubricant, not only a liquid lubricant but also a solid lubricant is used. For example, the lubricant is used in a closed clean atmosphere in a semiconductor manufacturing facility or the like, particularly in a low-pressure clean atmosphere such as a vacuum. In the rolling bearing for vacuum used, the vapor generated from the lubricating grease and the scattered fine particles may adversely affect the performance of precision parts, and lubricating oil or solid lubricant having a low vapor pressure is used.

Examples of the solid lubricant used include layered substances such as molybdenum disulfide, soft metals such as gold, silver, and lead, and polymer solids such as polytetrafluoroethylene (hereinafter abbreviated as PTFE). Lubricants are known.

[0005] However, even the above-mentioned conventional rolling bearing for vacuum using a solid lubricant cannot satisfy the demand for low dust generation due to the recent high performance of precision components.
For example, it has been difficult to sufficiently cope with a technology for manufacturing a semiconductor having a high-density pattern in which the line width of a conductive pattern is extremely fine.

[0006] As a rolling bearing for vacuum which relatively satisfies the above requirement of low dust generation, there is a type using a low vapor pressure fluorinated oil as a lubricating oil. A technique for impregnating a cage made of a porous body is disclosed in JP-A-61-6429, and a technique for impregnating a fluorinated oil into a porous polyimide cage having heat resistance superior to polyamideimide, JP-A-8-
It is disclosed in 177866.

[0007]

However, in the above-mentioned conventional low-dust-generating vacuum rolling bearing, the friction surface is 0.7 G.
Although there is no problem under the conditions of use at a low surface pressure of about Pa,
Rolling bearings that are required to withstand a high surface pressure of about GPa have a problem in that dust generation and gas generation amount increase during use.

Further, when a porous cage is impregnated with a fluorinated oil as a lubricating oil, the centrifugal force applied to the cage during rotation increases, the rotational efficiency of the bearing decreases, and the torque fluctuation also increases. is there.

[0009] Such a conventional rolling bearing,
Under the conditions of use at a high surface pressure as described above, the durability cannot be said to be sufficiently reliable.

Regarding the cause of the above-mentioned gas generation, when the material of the race and the rolling elements is steel such as stainless steel, FeF ₃ is formed by the reaction between Fe present on the surfaces thereof and F in fluorine oil. It is presumed that the fluorinated oil was generated and this further acted as a catalyst to further decompose the fluorinated oil.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to reduce the amount of dust generated during rotation of a roller bearing cage used at low pressure or vacuum as much as possible, and to reduce the amount of high surface pressure. Roller bearing cage that generates no dust from lubricating oil and has low dust generation even under operating conditions, or has low dust generation and also rotates with stable low torque and has excellent durability A rolling bearing for vacuum.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a bearing for a rolling bearing formed of a porous body having continuous ventilation holes and impregnated with an alkylated cyclopentane-based oil. Or a rolling bearing for vacuum mounting this retainer.

[0013] Further, the porous body may have a volume ratio of 5 to 25%.
The rolling bearing retainer is a porous body having a continuous vent hole, or a vacuum rolling bearing to which the retainer is attached.

[0014] Further, the above-mentioned porous body is configured to be a rolling bearing retainer which is a sintered body made of a polyimide resin, or a vacuum rolling bearing to which this retainer is attached.

The cage for a rolling bearing according to the present invention is characterized in that the alkylated cyclopentane-based oil impregnated in the cage is inactive, and a reaction such that Fe present on the raceway ring and the surface of the rolling element forms a catalyst. Don't wake up. Further, the alkylated cyclopentane-based oil is inactive against steel as compared with the fluorinated oil, so that the molecular chain is not cut and no gas is generated. Further, the alkylated cyclopentane-based oil has a lower viscosity than the fluorinated oil when the vapor pressure is substantially the same, and therefore can exhibit excellent low-torque rotation.

Since the specific gravity of the alkylated cyclopentane oil is smaller than the specific gravity of the fluorinated oil (1.85 g / cc), the cage impregnated with such an oil is hardly affected by the centrifugal force. Improve the rotational efficiency of the bearing.

In the invention in which the porous body having the continuous pores having the predetermined porosity is impregnated with the predetermined lubricating oil, the lubricating oil can be efficiently retained in a large amount, the amount of the lubricating oil exuded and the exuding speed are stabilized, Exhibits extremely stable lubricity.

Further, when a polyimide resin sintered body is used as the porous body, excellent heat resistance, chemical resistance, mechanical properties and electrical insulation are provided as a resin bearing retainer.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION A porous body having continuous air holes forming a cage for a rolling bearing used in each invention of the present application is obtained by a well-known method of sintering or foaming ceramics, metal or heat-resistant resin. It is preferable to use a polyimide resin having excellent heat resistance as the resin. Examples of the metal include sintered iron-based or copper-based alloys, and examples of ceramics include silicon nitride, aluminum oxide, and silicon carbide.

The above-mentioned polyimide resin (hereinafter abbreviated as PI resin) is a resin obtained by condensation polymerization of an aromatic carboxylic acid and an aromatic amine, and has excellent heat resistance, chemical resistance, and cage. Having a well-known chemical structure having sufficient mechanical strength and electrical insulation (which may be a thermoplastic resin or a thermosetting resin). In the present invention, the PI resin does not include a resin called a polyamideimide resin having an imide bond and an amide bond in a main chain (hereinafter, abbreviated as a PAI resin).

Commercially available PI resins which can be used in the present invention include:
P84-HT, manufactured by Toray Industries: TI-3000, manufactured by Ube Industries, Ltd .: UIP-S. R, manufactured by DuPont: Vespel, manufactured by Mitsui Toatsu Chemicals: Aurum, manufactured by Furon, USA: Meldin, and the like.

Such a PI resin has high heat resistance and does not melt even in the absence of heat radiation such as in a vacuum, so that it exhibits good friction and wear characteristics over a wide temperature range, and also has a thermoplastic resin that can be used for molding. As described above, the porosity of the grain boundary can be controlled without melting to obtain a molded article having continuous pores. In this manner, the PI resin porous body can arbitrarily adjust the oil content and the seepage rate of the lubricating oil, and can extend the life of the bearing.

In order to improve the moldability and sliding characteristics of the PI resin, a solid lubricant such as PTFE, graphite, molybdenum disulfide and boron nitride may be added.

As a method for manufacturing a cage made of a porous PI resin, a method in which a powdery resin is press-molded at room temperature (or ordinary temperature) and then fired under an inert gas or a pressurized atmosphere, or heat compression A molding method such as molding, ram extrusion molding, or CIP can be employed.

The retainer used in each invention of the present application has a volume ratio of 5
It is preferable to form a porous body having continuous pores with a porosity of ２５25% by volume. If the porosity is less than 5% by volume, the retention rate of the impregnated oil is low, and it is difficult to exhibit lubrication for a long period of time. This is because a preferable material in terms of strength cannot be obtained. A molded body having a porosity of the above-mentioned volume ratio can be produced by appropriately adjusting the particle diameter (average particle diameter), molding pressure, sintering temperature and the like of the raw material resin powder.

The alkylated cyclopentane-based oil impregnated in the porous molded body having continuous pores having a predetermined porosity as described above is a lubricating oil having a structure represented by the following chemical formula 1.

[0027]

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(In the formula, R is a linear or branched alkyl group having 4 to 130 carbon atoms, and m is 3 to 4.) Specific examples of such a cyclopentane-based oil include: A tri (2-octyldodecyl) cyclopentane represented by the following chemical formula 2, which is NYE SYNT manufactured by NYE LUBICANTS, USA
HETIC OIL 2001A (product name) is available.

[0029]

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(Wherein R ₂ is a branched alkyl group having 19 carbon atoms. Molecular formula: C ₆₅ H ₁₃₀ ) This compound has a vapor pressure of 8.5 × 10 ⁻¹³ Torr at 25 ° C.
It is a lubricating oil that can sufficiently withstand use in a vacuum environment. This lubricating oil has a specific gravity of 0.85 g / cc, which is less than half that of the fluorinated oil. In addition, this lubricating oil is inert, has excellent heat resistance, chemical resistance, and solvent resistance. It also has a strong molecular chain bonding force, so it has excellent load resistance and the amount of generated decomposition gas (out gas). There are few.

In order to impregnate the above-described predetermined lubricating oil into the porous molded body, it is preferable to impregnate under a reduced pressure atmosphere in order to eliminate air and moisture in the pores. If it is wiped off, a bearing retainer can be obtained. For efficient impregnation, it is preferable to heat the lubricating oil and the retainer.

The rolling bearing according to the invention of the present application is:
The rolling friction surface, sliding friction surface, and rolling element of the bearing ring are made of a well-known component material of a rolling bearing, and are made of metal such as stainless steel (for example, SUS440C) and tungsten-based high-speed tool steel (for example, SKH4). Materials, ceramics (for example, silicon nitride, silicon carbide, and the like) are examples of the constituent materials.

On the rolling friction surface, sliding friction surface and rolling element surface of the bearing ring, a titanium (Ti) layer is used as a base layer, and a titanium nitride (TiN) layer and titanium carbonitride (TiC ₁₋ ) are formed thereon. the composite coating of _x N _x) layer may be formed by a known method such as ion plating. By doing so, the hardness of the surface is increased and the durability is further increased, and the steel surface becomes inactive and the decomposition of the lubricating oil can be suppressed.

[0034]

【Example】

[Example 1] A PI resin powder having a repeating unit structure represented by the following chemical formula 3 (UIP-R: UIP-R, average particle diameter 9 µm) was molded at a molding pressure of 4000 kgf / cm ² , and further nitrogen atmosphere Sintering at 400 ° C for 2 hours,
The obtained sintered body is cut to obtain a rolling bearing cage (6) made of a porous sintered body having continuous pores with a porosity of 15%.
08 model number: outside diameter 16mm, inside diameter 131mm, length 6.2
2 mm).

[0035]

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The cage made of the obtained porous sintered body was
Cyclopentane oil (NYELUBICANTS, USA: NYE
SYNTHETIC OIL 2001A) and reduced pressure to 1 Torr to impregnate the lubricating oil. After impregnation, wipe off excess oil on the surface of the cage with a clean cloth.
It was assembled in a 440C test bearing (equivalent to 608 model number).

The following tests were conducted to examine the amount of dust, torque fluctuation, and durability of the bearing under a predetermined environment.
The results are shown in Table 1.

(1) Dust generation test Room temperature, degree of vacuum 1.0 × 10 ⁻⁶ Torr or less, thrust load 9.8 N (contact pressure 0.7 GPa) or thrust load 9
The above test bearing is rotated under the conditions of 8N (surface pressure: 1.5 GPa) and the number of rotations is 50 rpm, and a dust detector (direct detection of a method of measuring the number of dust by a sensor using a laser beam) is disposed immediately below the bearing. Device), dust of 0.3 μm or more was detected for 150 hours, and the total number of dust was determined.

(2) Torque fluctuation test Room temperature, degree of vacuum 1.0 × 10 ⁻⁶ Torr or less, rotation speed 20
0rpm, thrust load 9.8N or thrust load 9
The torque fluctuation width was measured under the condition of 8N. The evaluation is
Those with a torque fluctuation range exceeding 2 × 10 ⁻³ N · m were evaluated as “large torque fluctuation”, and those with a torque fluctuation range of 1 × 10 ⁻³ N · m or less were evaluated as “small torque fluctuation” in two stages. .

(3) Endurance test Room temperature, degree of vacuum 1.0 × 10 ⁻⁶ Torr or less, rotation speed 25
Under a condition of 00 rpm, a thrust load of 9.8 N or a thrust load of 98 N, an endurance test for measuring a time until the vibration width of the bearing becomes three times as large as the initial test was measured. The measurement limit was 700 hours.

[0041]

[Table 1]

Example 2 In Example 1, instead of the PI resin shown in Chemical formula 3, a PI resin having a repeating unit structure of Chemical formula 4 below (TI-3000, manufactured by Toray Industries, a free sinter product, a porosity of 7) %), Except that a cage for a rolling bearing impregnated with cyclopentane-based oil was manufactured, and this cage was used as a test bearing (6) made of SUS440C.
08 model number).

[0043]

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In order to examine the amount of dust generation, torque fluctuation and durability of the bearing under a predetermined environment, the above-mentioned tests (1) to (5) were carried out.
(3) was performed, and the results are shown in Table 1.

[Comparative Example 1] Stainless steel (SUS44)
0C) and a test bearing (equivalent to 608 model number) using a rolling element made of the same material as the stainless steel material (SUS3).
No. 04) was incorporated without contacting any lubricating oil.

The above tests (1) to (5) are also applied to this bearing.
(3) was performed, and the results are shown in Table 1.

[Comparative Example 2] A PI resin powder having a repeating unit structure represented by the following chemical formula 5 (manufactured by LENZING:
P84-HT, average particle size 25 μm) at a molding pressure of 2000
kgf / cm ² and then 350 N under nitrogen atmosphere.
After sintering at 2 ° C. for 2 hours, the obtained sintered body was cut to obtain a rolling bearing retainer (608 model number) made of a porous sintered body having continuous pores with a porosity of 25%.

[0048]

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A fluorinated oil (Faubulin Z, manufactured by Ausimont Co.) was placed in the cage made of the obtained porous sintered body.
25) was impregnated under reduced pressure to 1 Torr. After the impregnation, excess oil on the surface of the cage was wiped off with a clean cloth to obtain a cage for testing.

Further, the SUS incorporating the test cage is
On the rolling surfaces of the inner and outer races of the 440C bearing (equivalent to the 608 model number) and on the entire surfaces of the rolling elements, a composite layer was formed by sequentially stacking a Ti layer, a TiN layer, and a TiCN layer by an ion plating method. The thickness of the composite coating was 0.5 μm on the rolling surfaces of the inner and outer rings, and 0.2 μm on the entire surface of the rolling elements.

The above-mentioned tests (1) to (3) were carried out by incorporating the above-mentioned rolling elements into the bearings, and the results are shown in Table 1.

Comparative Example 3 In Example 1, instead of the PI resin shown in Chemical formula 3, a PI resin powder having a repeating unit structure shown in Chemical formula 6 below (Ube Industries, Ltd .: UIP-S, average particle size 8)
μm) at a molding pressure of 4000 kgf / cm ² , and further sintered under a nitrogen atmosphere at 400 ° C. for 2 hours. The obtained sintered body is cut to form a porous body having continuous pores with a porosity of 20%. A cage (608 model number) for a rolling bearing made of a sintered body was obtained.

[0053]

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The cage made of the obtained porous sintered body was placed in a fluorinated oil (Fomblin Z, manufactured by Ausimont).
25) was impregnated by reducing the pressure to 1 Torr, and then excess oil on the surface of the cage was wiped off with a clean cloth to obtain a test cage.

The cage was assembled in a test bearing made of SUS440C (corresponding to a 608 model number and not subjected to the above-described composite coating treatment), and subjected to the tests (1) to (4) described above.
(3) was performed, and the results are shown in Table 1.

As is clear from the results in Table 1, the bearing ring and the rolling element are SUS440C, and the cage is SUS304.
The rolling bearing of Comparative Example 1, which was formed with no lubricant and used no lubricating oil, had a large amount of dust generation and a large fluctuation in torque, and had a short durability time.

In Comparative Example 2 in which a titanium-based composite coating was formed on the surfaces of the race and the rolling elements and the retainer was impregnated with fluorinated oil, the light load (thrust load: 9.8 N) was used. Although the amount of dust was as small as 50 pieces and the durability time was 700 hours or more, in the case of heavy load (thrust load 98N),
The amount of dust generated increased sharply to 1,000 pieces, and the durability time was shortened to 100 hours. Also, in Comparative Example 3 in which the cage was impregnated with fluorinated oil without forming a titanium-based composite coating on the surfaces of the bearing ring and the rolling elements, as in Comparative Example 2 described above,
In the case of light load (thrust load 9.8N), the amount of dust generation is 45
The number of particles was small, and the durability time was 700 hours or more. However, in the case of a heavy load (a thrust load of 98 N), the amount of generated dust rapidly increased to 2500 pieces, and the durability time was reduced to 150 hours.

On the other hand, in Examples 1 and 2 in which the alkylated cyclopentane-based oil was impregnated in a cage made of a porous body made of PI and having a predetermined open porosity, the amount of dust generation and torque fluctuation were compared. Notably smaller than the example, with a durability time of 7
Excellent durability exceeding 00 hours was shown.

[0059]

As described above, the present invention relates to a rolling bearing retainer in which a porous material having continuous ventilation holes is impregnated with an alkylated cyclopentane-based oil or a vacuum rolling bearing to which the retainer is attached. As a result, the amount of dust generated during rotation of the roller bearing cage used at low pressure or vacuum is minimized as much as possible. A rolling bearing retainer that is dusty or a vacuum rolling bearing that has similar advantages.

Claims (4)

[Claims] 1. A porous body having continuous air holes,
Roller bearing cage made of impregnated alkylated cyclopentane oil. 2. The cage for a rolling bearing according to claim 1, wherein the porous body is a porous body having continuous air holes having a volume ratio of 5 to 25%. 3. The cage for a rolling bearing according to claim 1, wherein the porous body is a sintered body made of a polyimide resin. 4. A vacuum rolling bearing to which the rolling bearing retainer according to claim 1 is attached.