JP2002098152A - Retainer for rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a retainer in which running torque of a bearing is kept low stably, dust or noise generation is prevented, and which has a superior mechanical characteristic and is excellent in durability. SOLUTION: The retainer for a rolling bearing comprises a molded body of synthetic resin composition which retains rolling elements of rolling bearing, wherein the synthetic resin composition is made by admixing porous silica and lubricant to synthetic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cage for a rolling bearing.

[0002]

2. Description of the Related Art Conventional bearings for rolling bearings are made of metal, polyamide resin, polyacetal resin, polybutylene terephthalate resin and the like. In particular, when a synthetic resin is employed, a single injection-moldable synthetic resin, Alternatively, a synthetic resin composition reinforced by adding glass fiber, carbon fiber, organic fiber, or the like to a synthetic resin molding material has been used. A lubricating oil or a semi-solid lubricant such as grease has been used for lubricating a rolling bearing provided with such a retainer.

[0003] However, when a semi-solid lubricant such as grease is used, lubrication (stirring) depends on the consistency of the lubricant.
There is resistance, and a required torque is applied when the rotating shaft supported by the bearing rotates, and torque fluctuation occurs during the rotation. In particular, rolling bearings equipped with conventional grease lubricated cages have a shaft (the inner or outer ring of the rolling bearing) with a rotational speed of 10
At a high speed of about 000 rpm, the required torque for rotating the shaft supported by the bearing increases due to the agitation resistance of the grease, and the torque tends to fluctuate. In addition, the presence of grease tends to cause a relatively large amount of dust to float around the bearing. Such an increase and fluctuation of the torque, generation of dust, and noise caused by rotation of the bearing are caused by HD.
6mm inside diameter to be incorporated in office equipment such as D, VTR, DAT, LBP, audio equipment, PC peripheral equipment, etc.
In the following small-diameter bearings, there is a problem that the practical bearing performance is deteriorated.

[0004] In order to solve such a problem, rolling bearings having a lubricating function in the material of the cage have been conventionally proposed. For example, Japanese Patent Application Laid-Open No. 61-6429 discloses a bearing in which a fluorinated oil is impregnated in a porous polyamideimide resin formed by compression molding. Further, Japanese Patent Application Laid-Open No. 1-93623 discloses a retainer formed of an oil-impregnated plastic comprising a binder containing an oil and a base material, further impregnated with lubricating oil. JP-A-8-21450 discloses a mixture of a polyolefin resin and a lubricating oil, and molding the resin composition into a retainer shape. Japanese Patent Application Laid-Open No. 2000-97241 discloses a resin obtained by mixing an inorganic porous granular material with a synthetic resin and molding the resin composition into a retainer shape.

[0005]

However, Japanese Patent Application Laid-Open No.
The bearing retainer described in Japanese Patent No. 6429 in which a porous polyamide-imide resin is impregnated with fluorinated oil has a lower mechanical strength than a retainer in which a porous retainer is formed of a dense body. Therefore, the strength of the cage may be insufficient depending on the use conditions. Further, in order to form the communication hole, a powdery resin is compression-molded, then sintered, and further cut, so that the number of production steps increases.

In the case of the retainer described in JP-A-1-93623, lubricating oil is used at a high temperature (120 ° C. to 130 ° C.) for a long time (about 7 days) in order to increase the oil content. Since it is necessary to immerse, the lubricating oil and the resin forming the cage may be deteriorated and large dimensional changes may be observed, resulting in inferior product stability. There is a problem that it is difficult to maintain stable lubrication.

Further, in the case of the retainer described in Japanese Patent Application Laid-Open No. Hei 8-21450, since a lubricating oil is held by the polyolefin resin by using a polyolefin resin having a high oil absorbing property, the oil actually seeping out is used. Almost no. Further, even if the lubricating oil is uniformly dispersed in the resin, the lubricating oil near the surface exudes, but it is technically difficult to exude from the inside at a stable speed for a long period of time. Furthermore, when lubricating oil is compounded, a problem arises in terms of production if the compounding amount is large. For example, there are problems such as screw slippage during injection molding, unstable measurement, prolonged cycle time, poor dimensional accuracy, and poor adhesion of the lubricant to the mold surface resulting in poor finish of the molding surface. There is a problem that it is easy.

In the case of the retainer described in Japanese Patent Application Laid-Open No. 2000-97241, the lubricating oil is not retained in the resin, and is supplied to the sliding interface by capillary action when the lubrication is stopped. Therefore, there is a problem that it is not possible to exude from the inside at a stable speed for a long period of time.

SUMMARY OF THE INVENTION The present invention has been made to address such a problem, and the present invention has been made to reduce the rotational torque of a bearing by providing a stable and stable supply of lubricating oil to a bearing for a rolling bearing. Stabilize, prevent dusting and noise generation,
Moreover, it is an object of the present invention to provide a rolling bearing retainer having good mechanical properties and excellent durability.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a cage for a rolling bearing comprising a molded product of a synthetic resin composition for holding a rolling element of a rolling bearing, wherein the synthetic resin composition is porous to the synthetic resin. It is characterized by comprising at least silica and a lubricant.

Further, the porous silica is porous silica impregnated with a lubricant, and is characterized in that it is a spherical porous silica having continuous pores. The spherical porous silica has an average particle size of 0.5 to 100 μm.

Further, the above synthetic resin composition comprises a synthetic resin 3
0-95% by weight, lubricant 1-40% by weight, porous silica 1
-40% by weight. Further, the synthetic resin composition is characterized by comprising a molded article of the synthetic resin composition further mixed with a fibrous oil conductor.

[0013] By mixing the porous silica and the lubricant, the roller bearing retainer of the present invention has a structure in which most of the lubricant is retained by the porous silica, which is an oil retaining body. It exists in a state of being uniformly dispersed up to. The lubricant held by the porous silica exudes at a stable speed for a long period of time at the contact portion of the surface of the cage with the rolling element, and exhibits good lubrication characteristics. If a fibrous filler is used in combination as a lubricating oil conductor, the lubricating oil contained in the particulate porous silica present inside will pass through the surface of the conductive fiber (the interface between the synthetic resin and the fiber). By extruding the surface of the cage at a stable speed for a long period of time, good lubrication characteristics can be exhibited. A rolling bearing incorporating a cage made of such a resin composition molded body requires a small torque required for rotation and a small fluctuation in torque. In addition, since good lubrication is performed for a long time, a rolling bearing having excellent durability can be obtained.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of the structure of a cage for a rolling bearing. FIG. 1 is a partially enlarged perspective view of a crown-shaped retainer obtained by integrally molding a resin composition. Cage for rolling bearing 1
A pair of opposed retainer claws 3 are formed on the upper surface of the annular retainer main body 2 at a constant pitch in the circumferential direction, and the opposed retainer claws 3 are bent in a direction approaching each other. A rolling element holding pocket 4 for holding a ball as a rolling element is formed between holding claws 3. Also,
Flat portions 5 are formed between adjacent back surfaces of the holding claws 3 in the adjacent pockets 4 and serve as rising reference surfaces of the holding claws 3. The cage 1 for a rolling bearing is obtained by molding a synthetic resin composition described below.

The synthetic resin that can be used in the present invention preferably has heat resistance and oil resistance. For example, polyamide resin, polyethylene resin, polyacetal resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polycarbonate resin, polyphenylene sulfide resin, polyether sulfone resin, polyetherimide resin, polyamideimide resin, polyetheretherketone resin, thermoplastic polyimide Preferred examples include resins. In particular, a polyamide resin is suitable because it is a material that is inexpensive and easily industrially used, in addition to excellent heat resistance and oil resistance. Examples of polyamide resins include polyhexamethylene adipamide (6,6-nylon), polyhexamethylene azeramid (6,9-nylon), polyhexamethylene sebacamide (6,10-nylon), and polyhexamethylene deca. Amide (6,12-nylon), polytetramethylene adipamide (4,6-nylon), polycaprolactam (6-nylon), polylaurinlactam (12-nylon), poly-11-aminoundecane (11-nylon) ) And aromatic polyamide resins such as polymetaphenylene isophthalamide, polyparaphenylene terephthalamide, and polymethaxylene adipamide (nylon MXD-6). Can be used as a mixture.

The lubricant that can be used in the present invention can be any substance having a lubricating effect, such as a lubricating oil that is liquid at normal temperature, a wax that is solid at normal temperature, or a grease-like substance containing a thickener in lubricating oil. . Lubricating oils include mineral oils such as spindle oils, refrigerator oils, turbine oils, machine oils, dynamo oils, hydrocarbon synthetic oils such as polybutene, poly-α-olefins, alkylbenzenes, alkylnaphthalenes, and alicyclic compounds, and natural oils and fats. And non-hydrocarbon synthetic oils such as polyol ester oils, phosphate esters, diester oils, polyglycol oils, silicone oils, polyphenyl ether oils, alkyl diphenyl ether oils, fluorinated oils, etc.
Any generally used lubricating oil can be used without particular limitation.

The lubricating oil can be selected according to the conditions under which the cage for a rolling bearing of the present invention is used and the target performance. Further, a lubricating oil having heat resistance in accordance with the kneading and molding temperature of the resin can also be selected. Particularly when low friction is required, favorable results can be obtained by using an ester oil, a silicone oil or the like. Ester oil and silicone oil are particularly preferred because they have an affinity for silanol groups remaining on the surface of the spherical porous silica. As silicone oil,
Either a silicone oil having no functional group or a silicone oil having a functional group can be used.

Examples of the wax include a paraffinic wax having 24 or more carbon atoms, an olefinic wax having 26 or more carbon atoms, an alkylbenzene having 28 or more carbon atoms, and a hydrocarbon wax such as a crystalline microcrystalline wax, or And higher fatty acid derivative waxes such as myristic acid, palmitic acid, stearic acid, arachiic acid, montanic acid, and unsaturated fatty acids having 18 or more carbon atoms (eg, octadecenoic acid, parinaric acid, etc.). Examples of the higher fatty acid derivative wax include: 1) methyl and ethyl esters of higher fatty acids having 22 or more carbon atoms such as ethyl behenate and ethyl triconic acid; higher fatty acids having approximately 16 or more carbon atoms and higher monovalent having 15 or more carbon atoms. Esters with alcohol, octadecyl stearate, higher fatty acid esters such as higher fatty acid triglyceride having 14 or more carbon atoms, 2) higher fatty acid amides such as palmitic amide, stearic amide, oleic amide,
3) Salts of higher fatty acids such as lithium stearate and calcium stearate with alkali metals and alkaline earth metals.

The grease-like substance is obtained by adding a thickener to the above lubricating oil serving as a base oil. Examples of thickeners include: 1) calcium-based soap, sodium-based soap, lithium-based soap, barium-based soap, aluminum-based soap, zinc-based soap, etc. 2) Calcium-based complex soap as a complex-based soap, Sodium-based complex soap, lithium-based complex soap, barium-based complex soap, aluminum-based complex soap, zinc-based complex soap, etc. 3) Non-soap-based sodium terephthalate, diurea compound, triurea compound, tetraurea compound, polyurea compound, Urea
Examples include urethane compounds, diurethane compounds, silica aerogels, montmorillonite, bentone, polytetrafluoroethylene, fluorinate ethylene propylene copolymer, and boron nitride.

Among the above lubricants, when used in a cage for rolling bearings of small diameter bearings which are incorporated in office machines, audio equipment, personal computer peripherals, etc. and used at a high rotation speed of about 10,000 rpm, torque A lubricating oil is particularly preferable because it can suppress the increase and fluctuation of the noise and the generation of noise due to the rotation of the bearing.

The amount of the lubricant, especially the lubricating oil, is 1 to 40% by weight, preferably 5 to 3% by weight, based on the whole synthetic resin composition.
It is in the range of 5% by weight. If the amount of lubricating oil added is less than 1% by weight, the amount of lubricating oil will be absolutely insufficient, and the amount of oil supplied from the cage to the rolling elements will be insufficient, thus impairing the durability of the bearing. On the other hand, if it exceeds 40% by weight, the mechanical properties are undesirably reduced. Even when a grease-like substance containing a thickener is used, the amount of the lubricant is the same.

The porous silica usable in the present invention may be any porous silica having continuous pores and capable of impregnating and holding a lubricant. Preferred porous silicas are powders based on amorphous silicon dioxide. For example, precipitated silica, which is an aggregate of fine particles having a primary particle size of 15 nm or more, or an alkali silicate aqueous solution containing an alkali metal salt or an alkaline earth metal salt is emulsified in an organic solvent and gelled with carbon dioxide gas. Spherical porous silica (Japanese Unexamined Patent Publication No. 2000-143228), which is an aggregate of primary fine particles having a particle diameter of 3 to 8 nm. In the present invention, porous silica in which primary fine particles having a particle diameter of 3 to 8 nm are aggregated to form true spherical silica particles has continuous pores and has a property of being broken by shearing force at a sliding interface. Therefore, it is particularly preferable. The spherical silica particles have an average particle diameter of 0.5 to 100 μm. Such a spherical silica particle can hold a lubricant therein, and can supply a small amount of a lubricant impregnated therein at a sliding interface. If the average particle size is less than 0.5 μm, handling properties are poor. Also, the amount of the impregnated lubricant is not sufficient. If the average particle size exceeds 100 μm, dispersibility in the molten resin is poor. Further, the aggregate may be broken due to the shearing force applied at the time of kneading the molten resin, and the spherical shape may not be maintained. In consideration of ease of handling and imparting sliding characteristics, the average particle diameter is particularly preferably 1 to 20 μm. As such spherical porous silica,
Examples include Sunsphere manufactured by Asahi Glass Co., Ltd., and Gottball manufactured by Suzuki Yushi Kogyo Co., Ltd. Examples of non-spherical porous silica include Microid manufactured by Tokai Chemical Industry Co., Ltd.

The spherical silica particles in which primary fine particles having a particle diameter of 3 to 8 nm are collected have an oil absorption of 150 to 500 ml / 100 g, preferably 300 to 400 ml / 100 g. Oil absorption 150
If it is less than 100 ml / 100 g, the effect of retaining lubricating oil is not sufficient and it is not suitable for this application. If the oil absorption exceeds 500 ml / 100 g, the number of pores in the particulate porous silica increases, and the strength is reduced. Here, the oil absorption is based on JIS K5101.
It is a value measured according to. In addition, it is preferable that the inside and the outside surface of the spherical silica particles are covered with a silanol group (Si-OH) because the lubricant can be easily held inside. Further, the porous silica can be subjected to an organic or inorganic surface treatment suitable for the base material.

In the present invention, non-spherical porous silica can be used as long as the average particle diameter, the oil absorption, etc. are within the range of the true spherical silica particles. In addition, spherical and true spherical particles are preferable from the viewpoints of aggressiveness to the rolling elements and kneading properties. Here, spherical means that the ratio of the minor axis to the major axis is 0.8
A true sphere is a sphere closer to a true sphere than a sphere.

The amount of the porous silica is from 1 to 40% by weight, preferably from 5 to 35% by weight, based on the whole synthetic resin composition.
Range. If the amount of the porous silica is less than 1% by weight, the lubricating oil does not have a sufficient oil retaining effect, and if the amount of the lubricating oil is large, the screw slips particularly at the time of molding.
Not preferred. On the other hand, if the amount exceeds 40% by weight, the strength of the molded body is reduced, and the moldability is impaired.

The fibrous oil conductor that can be used in the present invention is:
Glass fiber, pitch-based carbon fiber, PAN-based carbon fiber, aramid fiber, alumina fiber, boron fiber, silicon carbide fiber, boron nitride fiber, silicon nitride fiber, metal fiber, polyester hollow fiber (Toyobo: Looplo, Teijinsha) Manufactured by Aerocapsule Dry). Especially glass fiber,
When used as an industrial material, it is suitable as an oil conducting material because it is inexpensive and easily available.

The fibrous oil conducting material has a fiber diameter of φ3 to 25.
It is preferable to employ an oil conducting material having a fiber length of 100 to 6000 μm. This is because the use of thin fibers having a fiber diameter of less than φ3 μm tends to break the fibers during kneading and molding, and the length of the fibers present in the roller bearing retainer is considerably shortened. It does not fulfill. Further, when a thick fiber having a fiber diameter of more than φ25 μm is employed, the specific surface area of the fiber becomes smaller than in the case of a predetermined fiber system, so that the effect of the oil conductor is not obtained. From such a tendency, a more preferable fiber diameter is φ5 to 20 μm. If the fiber length is less than the predetermined range, the effect of the conductor is not obtained, which is not preferable. If a long fiber exceeding the predetermined range is employed, the moldability is deteriorated, which is not preferable. From such a tendency, a more preferable fiber length is 100 to 5000 μm.

The amount of the oil conducting material is in the range of 0 to 40% by weight, preferably 0 to 35% by weight, based on the whole synthetic resin composition. If the amount is more than 40% by weight,
It is not preferable because moldability is impaired. A more desirable compounding ratio is 0 to 30% by weight.

Further, an appropriate filler can be added in order to improve friction and wear characteristics and to improve various mechanical properties. For example, minerals such as calcium carbonate, talc, silica, clay, and mica; inorganic whiskers such as titanium oxide whiskers, potassium titanate whiskers, aluminum borate whiskers, and calcium sulfate whiskers; carbon black, graphite, polyester fibers, and polyimide resins And various thermosetting resins such as polybenzimidazole resin.

For the purpose of improving slidability, pulp of amino acid compound, polyoxybenzoyl polyester resin, polybenzimidazole resin, liquid crystal resin, aramid resin, polytetrafluoroethylene, boron nitride, molybdenum disulfide, Tungsten or the like can be blended.

In order to improve the thermal conductivity of the roller bearing cage, carbon fiber, metal fiber, graphite powder,
You may mix zinc oxide etc. Of course, it is also possible to use a plurality of the above fillers in combination. It should be noted that additives that can be widely applied to general synthetic resins may be used in combination in amounts that do not impair the effects of the present invention. For example, release agents, flame retardants, antistatic agents, weather resistance improvers, antioxidants,
An industrial lubricant such as a coloring agent or a conductivity-imparting agent may be appropriately added, and the method of adding these is not particularly limited.

As a method for kneading the synthetic resin composition, a conventionally well-known method can be used. For example, after mixing with a mixer such as a Henschel mixer, a ball mill, a tumbler mixer, etc., the mixture is supplied to an injection molding machine or a melt extruder (eg, a twin-screw extruder) having good melt mixing properties, or a hot roller, a kneader, a Banbury mixer is used in advance. ,
Melt mixing may be performed using a melt extruder or the like, or vacuum molding, blow molding, foam molding, multilayer molding, heat compression molding, or the like may be performed. The order of kneading the resin, the porous silica, and the lubricant is not particularly limited, but it is preferable that the porous silica and the lubricant are kneaded in advance, and the base is added after the porous silica contains oil. It is preferable to knead with a resin or an oil conducting material. Further, since porous silica easily absorbs and absorbs moisture, it is preferable to dry the porous silica before kneading. The drying means is not particularly limited, and drying in an electric furnace, vacuum drying, or the like can be employed.

When the porous silica and the lubricant are mixed in advance, if the viscosity of the lubricant is high, it is difficult for oil to penetrate into the spherical porous silica. In that case, a method of diluting with a suitable solvent in which the oil dissolves, penetrating the diluted solution into the porous silica, gradually drying and evaporating the solvent to impregnate the lubricant inside the porous silica with a lubricant. is there. Alternatively, a method in which porous silica is immersed in a lubricant and a vacuum is drawn to force the lubricant into the interior of the porous silica. The method of melting and impregnating the lubricant, or the method of heating to an appropriate temperature to lower the viscosity of the lubricant and impregnating the lubricant when the viscosity is high even with a liquid lubricant at room temperature is an effective technique.

In addition, the above resin composition is used as a solid lubricant for supplying lubricating oil to rolling elements and rolling surfaces of a bearing by partially adhering to a cage formed of an iron plate or a copper alloy, and rolling. It is also possible to form a bearing cage. Further, as long as the lubricity of the resin composition is not impaired, the properties of the intermediate product or the final product may be separately improved by a chemical or physical treatment such as an annealing treatment. Annealing treatment can be performed in lubricating oil to suppress resin moisture absorption.

A rolling bearing incorporating a cage obtained by molding the above resin composition is immersed in a solution obtained by diluting a lubricating oil or grease to an appropriate concentration with an appropriate volatile organic solvent, and then immersing the bearing in the bearing surface. Oil plating for forming a uniform film may be performed. The lubricating oil for oil plating may be the same as or different from the above lubricating oil that can be contained in the resin composition. Specifically, an ester oil such as 2-ethylhexyl sebacate, a polyol ester oil obtained by esterifying pentaerythritol or trimethylolpropane, a mineral oil, a poly-α-olefin oil, an alkyl diphenyl ether oil and the like are suitable.
Further, an appropriate amount of a rust inhibitor, an antioxidant, an oiliness improver, or the like may be added to the lubricating oil for oil plating. Examples of the rust preventive include barium sulfonate and calcium sulfonate, examples of the antioxidant include 2,6-di-tert-butyl-p-cresol, and examples of the oiliness improver include oleic acid and tricresyl phosphate. Further, when the cage for a rolling bearing of the present invention is used by being incorporated in a grease-enclosed bearing, a grease-enclosed bearing having a longer life can be obtained.

[0036]

Examples 1 to 6 and Comparative Examples 1 to 4 A polyamide resin (Amilan CM1001 (6-nylon) manufactured by Toray Industries, Inc.) was used as a heat and oil resistant resin, and an ester oil (Japan) was used as a lubricating oil. Made by Yushi, Unistar H481
R), spherical silica particles (Sunsphere H, manufactured by Asahi Glass Co., Ltd.)
52, average particle diameter 5μm, oil absorption 300ml / 100g), fibrous oil conducting material (Asahi Fiberglass: glass fiber C)
S03MA497, fiber diameter: 13 μm, fiber length: 3 mm). After the lubricating oil was impregnated into the spherical silica particles, the mixture containing the lubricating oil and the polyamide resin were charged into a Henschel mixer and mixed. Thereafter, melt kneading was performed at 235 ° C. using a twin screw extruder (BT30 manufactured by Plastics Engineering Laboratory).
Pellets were made. Injection molding is performed at 240 ° C using the pellets, and a cage for a rolling bearing having a predetermined shape (equivalent to 684 model number: dimensions φ6.87mm × φ5.30mm × 1.90mm)
I got In addition, as one of the tests of comparative materials, grease-filled products (manufactured by Kyodo Yushi Co., Ltd .: 2 mg of grease and Multemp SRL)
Was also prepared. Use these cages with an inner diameter of 4 mm
Built into a test bearing consisting of a 9mm, 4mm width miniature ball bearing (inner, outer rings and rolling elements are bearing steel). The performance of the bearing is shown below as the rotational speed fluctuation rate (jitter), torque, operating noise, and endurance time. The measurement was carried out by the method, and the results are shown in Table 1. Furthermore, according to the compounding ratio shown in Table 1, the diameter is φ100mm and the thickness is 2mm
The test piece was subjected to heat compression molding at a mold temperature of 240 ° C., and the amount of lubricating oil exudation (weight reduction rate) was measured using the molded body.

Example 7 A polyamide resin was added to a polyacetal resin (manufactured by Polyplastics Co., Ltd .: Duracon M90).
A cage for a rolling bearing was obtained in the same manner as in Example 6, except that the shaft extrusion temperature was changed to 190 ° C and the injection molding temperature was changed to 195 ° C. The same evaluation as in Example 1 was performed, and the results are shown in Table 1.

(1) Measurement of Rotational Speed Fluctuation Rate (Jitter) The rotational speed was measured using an FG jitter measuring instrument. The measurement conditions were as follows: After aging for 10 minutes at a rotation speed of 15000 rpm, jitter measurement for 30 seconds was performed 5 times, and the average value (rotation speed fluctuation rate,%) was obtained. (2) Measurement of torque Torque (gf-cm) was measured under the conditions of a rotation speed of 15000 rpm and an axial load of 1 kgf. (3) Operating sound The acoustic value (dBA) after 100 hours of rotation was measured under the conditions of a rotation speed of 10,000 rpm and an axial load of 0.5 kgf. (4) Endurance test At room temperature, an axial load of 1 kgf and a rotation speed of 10,000 rpm, the time required for the bearing to rotate within three times the initial vibration acceleration was examined. In that case, the test was stopped when the vibration value of the bearing exceeded the specified condition with the target of 3000 hours. (5) Exudation amount of lubricating oil (weight loss rate of molded article) Measure the molded article weight after molding, sandwich the molded article with paraffin paper so that the lubricating oil easily exudes, and put a 500g weight on it At 80 ° C. for 6 hours, and the weight of the molded body was measured. The weight loss was determined by subtracting the weight after 6 hours from the initial weight, and the weight loss was calculated by dividing the weight loss by the initial weight (subtraction). Weight loss rate (%) = (reduced weight / initial weight) × 100. Since the weight loss is considered to be the amount of seepage of the lubricating oil, it can be said that the greater the weight reduction rate, the more the seepage of the lubricating oil. (6) Moldability Moldability at the time of injection molding was compared. If there was a problem such as screw slippage, adhesion of oil to the mold, and time required for weighing, etc., it was evaluated as れ ば if molding was possible without any problems, and × if it was not molded.

[0039]

[Table 1]

As is clear from the results shown in Table 1, Examples 1 and 2 in which the polyamide resin, porous silica and lubricating oil were blended in predetermined amounts, and Example 3 in which a fibrous oil conductor was blended. -The rolling bearing incorporating the cage having the composition of Example 7 using the polyacetal resin and having the composition of Example 7 has a low rotation speed fluctuation rate of 0.010 to 0.013%, is stable, and has a torque of 0.4 to 0.6. The value was as small as g · cm. In addition, the acoustic value was as small as 30 to 32 dBA. Furthermore, since the operation can be performed for 3000 hours or more, the durability is good, and it can be seen that the lubricating oil is stably supplied to the surface of the cage through the porous silica or glass fiber. In each example, the weight loss rate was
Since it is 1.1 to 1.6%, it can be said that the amount of exuding oil is sufficiently large. Furthermore, the moldability was all ○, indicating that molding was easy even when the amount of lubricating oil was large.

On the other hand, since Comparative Example 1 does not contain porous silica, the lubricating oil present inside the resin molded product does not seep to the contact portion with the rolling element. As a result, the rotational speed fluctuation rate, the torque, and the level of the acoustic value showed larger values than those containing the porous silica of the example. Further, since there was no seepage of lubricating oil from the inside of the cage, when the amount of lubricating oil in the surface layer decreased, the vibration gradually increased, and the durability was poor. The weight loss rate was as low as 0.1%, and the amount of exuding oil was insufficient. Furthermore, the formability was poor due to the large amount of lubrication.

In Comparative Example 2, the lubricating oil was not included, and grease was sealed in the sliding portion and lubricated. Therefore, the grease was scattered by the operation and adhered to the ball transfer surface, so that the rotational speed fluctuation rate was large, The resistance to agitation was large, and as a result, the torque was about 10 times greater than in each of the examples.
In Comparative Example 3, since the amount of the lubricating oil added was increased to 20% by weight without containing porous silica, slippage of the screw occurred during injection molding, and the supply of pellets to the molding machine could not be performed stably. It could not be formed into a container shape. In Comparative Example 4, the addition amount of the porous silica was 60% by weight.
Therefore, the molded body became brittle and could not be molded into a cage shape.

As described above, since the rolling bearings incorporating the cages of the respective embodiments are provided with the rolling bearing cages having excellent lubricating oil supply capability, good lubrication can be achieved for a long time without using grease. It is used under, and it is hard to cause seizure. Further, since no grease is sealed, an increase in torque due to stirring of the grease is suppressed. In conventional grease-sealed bearings, when operating conditions are severe (high speed, high temperature, high load, etc.), lubricating oil is not supplied sufficiently from grease, and seizure may occur due to poor lubrication.
A rolling bearing incorporating a cage made of a resin composition in which lubricating oil is impregnated into porous silica has an advantage that lubricating oil is supplied from the inside, so that poor lubrication is less likely to occur. Of course, it is also possible to use the grease and the rolling bearing retainer of the present invention together for the purpose of extending the life.

[0044]

As described above, the cage for a rolling bearing of the present invention is made of a molded article of a synthetic resin composition obtained by blending at least porous silica and a lubricant in a synthetic resin, so that the porous silica can hold the lubricant. it can. As a result, the lubricant oozes out on the cage surface, so that the rolling torque of the rolling bearing is low, the fluctuation is small and stable for a long time, and the generation of dust and noise is prevented. Rolling bearings with excellent performance can be obtained.

In particular, porous silica is porous silica impregnated with a lubricant, and spherical porous silica having continuous pores. It is easy to seep. In addition, the spherical porous silica has an average particle size of 0.5 to 100 μm, so it has good mechanical properties, and the rolling torque of the above-mentioned rolling bearing is low, fluctuation is small and stable for a long time, and dust generation and noise generation are prevented. In addition, a rolling bearing having good mechanical properties and excellent durability can be obtained.

The synthetic resin composition constituting the cage for a rolling bearing is composed of 30 to 95% by weight of a synthetic resin, 1 to 40% by weight of a lubricant, and 1 to 40% by weight of porous silica.
Furthermore, since it is made of a molded article of the synthetic resin composition to which the fibrous oil conductor is added and mixed, it is possible to increase the amount of the lubricant compounded. As a result, in addition to the above effects, the moldability of the oil-containing material, which has conventionally been difficult to mold, can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of the structure of a cage for a rolling bearing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cage for rolling bearings 2 Cage main body 3 Cage claw 4 Pocket 5 Flat part

Claims (6)

[Claims] 1. A rolling bearing cage comprising a molded body of a synthetic resin composition for holding a rolling element of a rolling bearing, wherein the synthetic resin composition contains at least porous silica and a lubricant in a synthetic resin. A retainer for rolling bearings, characterized in that: 2. The cage for a rolling bearing according to claim 1, wherein the porous silica is a porous silica impregnated with a lubricant. 3. The rolling bearing retainer according to claim 1, wherein the porous silica is a spherical porous silica having continuous pores. 4. An average particle diameter of the spherical porous silica is
4. The cage for a rolling bearing according to claim 3, wherein the thickness is 0.5 to 100 [mu] m. 5. The synthetic resin composition according to claim 1, wherein the synthetic resin comprises 30 to 9 synthetic resins.
5% by weight, lubricant 1-40% by weight, porous silica 1-40
2. The rolling bearing retainer according to claim 1, wherein the retainer is composed of% by weight. 6. The synthetic resin composition according to any one of claims 1 to 5, wherein the synthetic resin composition further comprises a molded article of the synthetic resin composition to which a fibrous oil conductor is added. Roller bearing cage.