JPH0650346A - Cylindrical roller bearing - Google Patents

Abstract

PURPOSE:To suppress the deterioration of grease by suppressing the heat generation of a beating by reducing the revolution slide of a roller. CONSTITUTION:A groove is formed on the guide surface for the inner race 2 of a retainer 4, and an O-ring 5 made of the lubricating rubber composition is installed in the groove, keeping a slight tightening gap for the inner race 2. The lubricating rubber composition consists of the thermoplastic fluoro resin as the first essential component, fluorinated rubber as the second essential component, and the low molecular weight polymer containing fluorine as the third essential component.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed cylindrical roller bearing, and more particularly to a sealed cylindrical roller bearing having a roller held by a cage between an outer ring and an inner ring.

[0002]

BACKGROUND OF THE INVENTION Rolling bearings are bearings in which rollers are interposed between the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring, and a grease is used to smoothly rotate the rollers. Is enclosed. However, when a rolling bearing is used due to grease lubrication, there is a problem that skid of the roller occurs due to agitation resistance of the grease, heat of the bearing is generated, and deterioration of the grease is promoted.

Therefore, a main object of the present invention is to provide a cylindrical roller bearing with a seal which can reduce the heat generation of the bearing and improve the grease retaining property.

[0004]

SUMMARY OF THE INVENTION The present invention is a roller bearing for guiding a retainer on the outer peripheral surface of an inner ring, in which a guide member of the retainer is fitted with a sealing material made of a lubricious rubber composition with a tightening margin. The lubricious rubber composition is composed of a thermoplastic fluororesin as a first essential component, a fluororubber as a second essential component, and a low molecular weight fluoropolymer as a third essential component.

In the present invention, the fluororubber is a polymer or copolymer of unit monomers containing an average of one or more fluorine atoms, has a glass transition point of room temperature or lower, and has a rubber-like elasticity at room temperature. It is not particularly limited as long as it has the following, and a wide range can be exemplified.

Examples of the polymerization method of fluororubber include bulk polymerization, suspension polymerization, emulsion polymerization, solution polymerization, catalyst polymerization, ionizing radiation polymerization, and redox polymerization. The molecular weight of fluororubber is usually 50,000.
A polymer having a molecular weight of 0 or more is preferable, and a polymer having a molecular weight as high as possible gives good results.
Above all, it is particularly preferable to use one having a size of about 100,000 to 250,000.

Typical examples corresponding to the above conditions are tetrafluoroethylene / propylene copolymer Afras manufactured by Asahi Glass Co., Ltd., vinylidene fluoride / hexafluoropropylene copolymer DuPont / Showa Denko Viton, and fluorine. Fluorovinylidene / hexafluoropropylene / tetrafluoroethylene copolymer Technofluon made by Montefluos, fluorosilicone elastomer Dow Corning silastic LS, perfluoroelastomer Daikin Industrial Co., Ltd. Can be mentioned.

In the present invention, the thermoplastic fluororesin which is the first essential component has a carbon chain in the main chain,
A polymer having a fluorine bond in its side chain, such as a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (hereinafter abbreviated as PFA) and a tetrafluoroethylene / hexafluoropropylene copolymer (hereinafter referred to as FEP). Abbreviated) and a tetrafluoroethylene / ethylene copolymer (hereinafter abbreviated as ETFE), preferably one or more polymers selected from the group consisting of: Any of the above resins can be produced by various polymerization methods such as catalyst emulsion polymerization, suspension polymerization, catalyst solution polymerization, gas phase polymerization and ionizing radiation irradiation polymerization. The molecular weight is preferably 50,000 or less, more preferably more than 5,000 and almost 20,000 or less.

As a typical example corresponding to the above conditions, the above-mentioned PFA manufactured by Mitsui DuPont Fluorochemical Co., Ltd. is used.
Examples include MP10 and FEP, Teflon FEP100 manufactured by Mitsui DuPont Fluorochemicals, and ETFE, Aflon COP manufactured by Asahi Glass Co., Ltd.

The composition obtained by mixing the above-mentioned fluororubber and thermoplastic fluororesin has characteristics as an elastic body. In the present invention, the low molecular weight fluoropolymer, which is the third essential component, is blended in order to impart further excellent sliding properties to such an elastic body.

[0011] In this invention, the low molecular weight fluoropolymer, tetrafluoroethylene (TFE), main structural unit -C _n F _2n -O- _(n is an integer from 1 to 4) fluoropolyether having major Structural unit

[0012]

[Chemical 1]

Among the polyfluoroalkyl group-containing compounds (having 2 to 20 carbon atoms) having, for example, those having a molecular weight of 50,000 or less. In order to give excellent sliding properties,
It is particularly desirable that the low molecular weight fluoropolymer has a molecular weight of 5,000 or less. Among such low molecular weight fluorine-containing polymers, those having an average particle size of tetrafluoroethylene polymer represented by the following formula of 5 μm or less are particularly preferable.

[0014]

[Chemical 2]

Examples of such materials include Bydax AR manufactured by DuPont and Furuon Lubricant L169 manufactured by Asahi Glass.

[0016] Next, as -C _n F _2n -O _(n is an integer from 1 to 4) average molecular weight of 50,000 or less fluoropolyethers having a main structural unit of,

[0017]

[Chemical 3]

The following can be exemplified. Such polymers are those having a structural unit containing a functional group such as an isocyanate group, a hydroxyl group, a carboxyl group, and an ester group in order to improve the affinity (adhesion) with other compounding materials and additives. desirable.

Specific examples of such a fluoropolyether include the following.

[0020]

[Chemical 4]

These fluoropolyethers may be used alone or in combination. Further, a fluoropolyether having activated hydrogen as a functional group and an isocyanate compound having no polyfluoropolyether group may be used in combination. Further, a fluoropolyether having an isocyanate group, diamines not containing various fluoropolyether groups, triamines, or diols not containing various fluoropolyether groups,
A method of using triols together may be adopted.

In particular, it is desirable to use a combination of fluoropolyethers in which functional groups react with each other to increase the molecular weight. As such, it is likewise desirable to combine, for example, those having units containing isocyanate groups with those having units containing hydroxyl groups.

Examples of the polyfluoroalkyl group-containing compound include compounds having a polyfluoroalkyl group as shown below.

[0024]

[Chemical 5]

The above-mentioned polyfluoroalkyl group (having 2 to 20 carbon atoms) having an average molecular weight of 50,000 or less is

[0026]

[Chemical 6]

And the like, a polymer of a reaction product of a compound having a reactive group and a polyfluoroalkyl group with an ethylenically unsaturated compound having a group which reacts with the reactive group (for example, fluoroalkyl acrylate), and Examples thereof include a reaction product of a compound having a reactive group and a polyfluoroalkyl group and various polymers having a group that reacts with the reactive group, or a polycondensation product of the above compound.

Like the above-mentioned fluoropolyether, the polyfluoroalkyl group-containing compound is a functional group having a high affinity for improving the affinity (adhesion) with other compounding materials and additives, such as an isocyanate group, A compound having a unit containing a hydroxyl group, a mercapto group, a carboxyl group, an epoxy group, an amino group, a sulfone group and the like is preferable.

These polyfluoroalkyl group-containing compounds may be used alone or in combination. Further, a polyfluoroalkyl group-containing compound having a reactive group having activated hydrogen and an isocyanate compound having no polyfluoroalkyl group may be used in combination. Also,
Adopting a method such as combining a polyfluoroalkyl group-containing compound having an isocyanate group with various polyfluoroalkyl group-free diamines, triamines or various polyfluoroalkyl group-free diol groups, triols, etc. May be.

The combination of functional groups is preferable from the viewpoint of increasing the strength. Specifically, it has a polyfluoroalkyl group having 2 to 20 carbon atoms and is selected from a hydroxyl group, a mercapto group, a carboxyl group and an amino group. A combination with a fluoropolymer containing at least one kind, or a fluoropolymer having a polyfluoroalkyl group having 2 to 20 carbon atoms and having a unit containing an isocyanate group, and polyfluoroalkyl having 2 to 20 carbon atoms Examples thereof include a combination with a fluoropolymer having a group and a unit containing a reactive group having an activated hydrogen.

Among these low molecular weight fluoropolymers,
It has been found that the use of fluoroolefin polymers or fluoropolyethers gives excellent results in lubricity, and the use of tetrafluoroethylene polymers having an average particle size of 5 μm or less gives the most desirable results.

In the present invention, the mixing ratio of the fluororubber, the thermoplastic fluororesin and the low molecular weight fluoropolymer is such that the weight ratio of the fluororubber to the thermoplastic fluororesin is 5.
It is desirable that the ratio be 0:50 to 95: 5. If the blending weight ratio of the thermoplastic fluororesin exceeds 50/100,
The desired composition does not have sufficient elastic properties, and the ratio is 5/100.
This is because if it is less than this, sufficient abrasion resistance cannot be obtained.

The low molecular weight fluoropolymer is preferably 5 to 50 parts by weight with respect to 100 parts by weight of the total of the fluororubber and the thermoplastic fluororesin. This is because if the compounding ratio of the low molecular weight fluoropolymer is less than 5 parts by weight, sufficient sliding properties cannot be obtained, and if it exceeds 50 parts by weight, the rubber-like elastic properties are impaired.

Further, with respect to the above-mentioned lubricating rubber composition, 3
The wear resistance can be improved by adding a cured powder of a thermosetting resin that is infusible at 00 ° C. or a heat-resistant resin powder having a glass transition point of 300 ° C. or higher.

The thermosetting resin powder is a fine powder of a phenol resin, an epoxy resin or the like after thermosetting, and the heat-resistant resin having a glass transition temperature of 300 ° C. or higher is a polyimide resin or an aromatic aramid resin. A powder is mentioned.

Among commercially available resin powders, a hardened and pulverized product of a phenol resin is manufactured by Kanebo Ltd .: Bell Pearl H30.
0, as a cured pulverized product of polyimide resin: PWA20 manufactured by Mikasa Sangyo Co., Ltd .; as a pulverized product of aromatic aramid resin: MP-P manufactured by Asahi Kasei Co., as a thermosetting resin powder having a glass transition point Tg of 300 ° C. or higher. Manufactured by Ube Industries, Ltd .: Upilex S (Tg> 500).

The particle size of such thermosetting resin powder is 1
Those having a particle size of up to 15 μm are preferable from the viewpoint of maintaining rubber-like elasticity and facilitating the kneading process. The thermosetting resin powder is preferably added in an amount of 5 to 20% by weight with respect to the first to third essential components. If it is less than 5% by weight, the effect of improving wear resistance is not obtained and 2
A large amount exceeding 0% by weight is not preferable because the rubber elasticity decreases.

In addition to the above components, various additives may be added within the range not impairing the object of the present invention. For example, as a vulcanizing agent for fluororubber, isocyanurate, organic peroxide, etc., antioxidants such as sodium stearate, magnesium oxide, and calcium hydroxide, or acid acceptors, antistatic agents such as carbon, silica and alumina, etc. It goes without saying that the above-mentioned fillers, other metal oxides, colorants, flame retardants and the like may be appropriately added.

The method of mixing the various raw materials described above is not particularly limited, and the generally-used methods can be used for mixing. For example, the elastomer as the main raw material and the other raw materials may be individually mixed sequentially or simultaneously by a roll mixer or other mixer. At this time, it is desirable to provide a temperature controller to prevent heat generation due to friction.

When a roll mixer is used,
For finishing mixing, it is more preferable to tighten the roll interval to about 3 mm or less and perform thin threading.

[0041]

[Effect] The cylindrical roller bearing with seal according to the present invention is
A sealing material made of a lubricating rubber composition is fitted to the guide surface of the cage with an inner ring and an interference, and a thermoplastic fluororesin which is the first essential component as the lubricating rubber composition, and a fluororubber as the second essential component, Also, since the third essential component is formed with a distribution of a low molecular weight fluorine-containing polymer, the revolution slip can be reduced, the heat generation of the bearing can be reduced, and the deterioration of the grease can be suppressed.

[0042]

1 is a vertical sectional view of an embodiment of the present invention. In FIG. 1, rollers 3 are provided between the inner peripheral surface of the outer ring 1 and the outer peripheral surface of the inner ring 2, and the rollers 3 are rotatably held by a cage 4. A groove is formed on a guide surface of the retainer 4 with the inner ring 2, and an O-ring 5 as a sealing material, which is a feature of the present invention, is attached to the inner ring 2 with a slight interference. . O-ring 5 is a roller 3
The grease 6 sealed between the cage and the cage 4 is prevented from leaking, and is formed of a lubricating rubber composition. Since the lubricating rubber composition has a small coefficient of friction and can be used at high temperatures, it can reduce orbital slip, reduce heat generation of the bearing, and suppress deterioration of the grease 6. That is, in the embodiment of the present invention, the guide system of the cage 4 is the inner ring guide system in order to reduce the revolution slip. The outer ring guide causes friction between the outer diameter of the cage and the outer ring guide surface, but in the inner ring guide of this embodiment, the revolution driving force between the rollers 3 and the inner ring 2 causes the inner diameter surface of the cage and the inner ring guide surface to move. Since the driving force due to friction is added, the revolution slip can be reduced. Further, in the embodiment of the present invention, the frictional force is increased by the O-ring 5 using the lubricating rubber composition which is slightly larger than the friction coefficient between the cage and the inner ring. Further, a metallic seal 7 is provided between the outer ring 1 and the inner ring 2.

The raw materials used in Examples and Comparative Examples are collectively shown below. The mixing ratios of the respective components are all weight%, but for the raw materials shown in (3) to (9), the total weight of the raw materials shown in (1) and (2) is 10
% By weight with respect to 0.

(1) Vinylidene fluoride / fluoropropylene copolymer (Technoflon FOR4 manufactured by Asahi Monte Corporation)
20) (2) Tetrafluoroethylene / ethylene copolymer
(Aflon COP manufactured by Asahi Glass Co., Ltd.) (3) Low molecular weight fluoropolymer (low molecular weight TFE)
(Lubricant L169 manufactured by Asahi Glass Co., Ltd.) (4) Low molecular weight fluoropolymer (low molecular weight PFPE)
(Japan Anymont Fomblin Z-DISO
C) (5) Carbon (MT carbon manufactured by Faderbilt) (6) Sodium stearate (general industrial material) (7) Magnesium oxide (general reagent) (8) Calcium hydroxide (general reagent) (9) Phenolic resin (Kanebo) Belpearl H300) (10) Nitrile / butadiene copolymer (NBR)
(General industrial material hardness JIS-A70) (11) Dimethyl silicone polymer (silicone rubber) (General industrial material hardness JIS-A70) (12) Polyimide molding (DuPont Vespel SP21) First, roll interval 5-10 mm The fluororubber (1) was wound around a roll mixer whose degree was adjusted, and MT carbon, sodium stearate, and Mg were sequentially added at the ratios shown in Table 1.
O and Ca (OH) ₂ were added and kneaded. Then, the roll interval was adjusted to 1 mm, and mastication was performed about 10 times. For the purpose of preventing frictional heat at this time, cooling water was constantly passed through the roll to keep the roll temperature at 60 ° C or lower. Next, cooling water is stopped, steam is passed through the rolls, the rubber temperature is adjusted to 70 ° C or higher and 90 ° C or lower, and then the roll interval is returned to about 5 to 10 mm to obtain a low molecular weight fluoropolymer. Was added little by little and kneaded at the compounding ratio of each example shown in Table 1. After that, the roll interval is 1
It narrowed to mm and masticated 10 times.

[0045]

[Table 1]

In the compound obtained in the above steps, 150 × 150 × 1t sheet was subjected to primary vulcanization (170
It was manufactured by carrying out secondary vulcanization (230 ° C., 16 hours, free) at 10 ° C. for 10 minutes at a pressing pressure of 7 kgf / cm ² .
The friction test, abrasion test, non-adhesiveness and elastic property of each test piece were determined. The method of each test is as follows.

(1) Test Method-Friction and Wear Test The obtained test piece was processed into an inner diameter of φ17 and an outer diameter of φ21.
A ring test piece was obtained by adhering it to a 17 × φ21 × 10 SPCC ring piece. Mating material is SUJ2 (bearing steel) φ6 × φ
A 33 × 6 disc-shaped test piece was prepared and evaluated using a thrust type friction and wear tester. The condition is a sliding speed of 128 m / min,
The surface pressure was 3.5 kgf / cm ² . Table 2 shows the friction coefficient and the wear coefficient after 500 hours.

(2) Non-adhesion In the obtained test piece, the contact angle to water was measured by a goniometer-type contact angle measuring device, and it was judged that the larger the contact angle, the better the non-adhesiveness. The results are shown in Table 2.

(3) Elastic body property The obtained test piece is compliant with JIS-K6301,
The tensile strength, elongation, and hardness (JIS-A) were investigated. The results are shown in Table 2.

(4) Impact resistance properties The test pieces obtained were tested according to ASTM D256,
The Izod impact strength was investigated. The results are shown in Table 2.

[0051]

[Table 2]

Comparative Example In the comparative example, the raw materials were blended in the proportions shown in Table 1, and kneading, molding and vulcanization were performed in the same manner as in the examples. The test pieces were adjusted and tested in the same manner as in the examples. The results are shown in Table 2.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of the present invention.

[Explanation of symbols] 1 outer ring 2 inner ring 3 rollers 4 cage 5 O-ring 6 grease 7 metal seal

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C10N 40:02

Claims (7)

[Claims] 1. A rolling bearing for guiding a retainer on the outer peripheral surface of an inner ring, wherein a seal member made of a lubricious rubber composition is fitted to the guide surface of the retainer with the inner ring and a tightening margin. The rubber composition comprises a first essential component, a thermoplastic fluororesin, a second essential component, fluororubber, and a third essential component, a low molecular weight fluoropolymer.
Cylindrical roller bearing with seal. 2. The cylindrical roller bearing with a seal according to claim 1, wherein a cured powder of a thermosetting resin or a heat resistant resin powder having a glass transition point of 300 ° C. or higher is added to the lubricating rubber composition. 3. The thermoplastic fluororesin as the first essential component is tetrafluoroethylene / ethylene copolymer,
The sealed cylindrical roller bearing according to claim 1, which is one or more selected from the group consisting of a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer and a tetrafluoroethylene / hexafluoropropylene copolymer. 4. The second essential component has a molecular weight of 100,0.
A fluororubber of from 00 to 250,000.
Cylindrical roller bearing with seal. 5. The fluororubber which is the second essential component,
Group consisting of tetrafluoroethylene / propylene copolymer, vinylidene fluoride / hexafluoropropylene copolymer, vinylidene fluoride / hexafluoropropylene / tetrafluoroethylene copolymer, fluorosilicone copolymer and perfluoro-based copolymer 1 selected from
The sealed cylindrical roller bearing according to claim 1, which is a polymer of at least one kind. 6. The low molecular weight fluoropolymer as the third essential component is selected from the group consisting of tetrafluoroethylene polymers having an average molecular weight of 50,000 or less, fluoropolyethers and polyfluoroalkyl group-containing compounds.
The sealed cylindrical roller bearing according to claim 1, which is a polymer of at least one kind. 7. The sealed cylindrical roller bearing according to claim 1, wherein the low molecular weight fluoropolymer which is the third essential component is a tetrafluoroethylene polymer having an average particle size of 5 μm or less.