JP2021152394A - Rolling bearing - Google Patents

Abstract

To provide a rolling bearing capable of preventing seizure or failure even under high temperature and high speed condition in which a dm n value is 80×104 or more especially in grease lubrication.SOLUTION: A rolling bearing 1 includes an inner ring 2, an outer ring 3, a plurality of steel balls 4 interposed between the inner and outer rings, and a cage 5 for holding the balls 4, and is used under high-speed rotation in which a dm n value is equal to or more than 80×104. The cage 5 is prepared by injection-molding a resin composition. The resin composition contains a polyamide resin consisting of a dicarboxylic acid component mainly composed of terephthalic acid and a diamine component, or a polyether ether ketone resin as a base resin, and does not contain a fibrous reinforcing material, or contains 10 mass% or less of the fibrous reinforcing material based on the whole resin composition.SELECTED DRAWING: Figure 1

Description

The present invention relates to rolling bearings used in automobiles, motors, machine tools, etc., and more particularly to rolling bearings used under predetermined high-speed rotation conditions.

Conventional ball bearings are generally press-formed as a cage that rotatably holds a plurality of rolling elements arranged in the circumferential direction between the raceway surface of the outer ring and the raceway surface of the inner ring. The one made of iron is used. However, when the rotation speed of the bearing becomes high, in the iron cage, the friction due to the sliding contact between the rolling element and the cage becomes large, and the temperature rise of the bearing becomes large, and as a result, there is a risk of seizure. .. Therefore, it is considered effective to use a cage made of synthetic resin, which is superior to iron in terms of self-lubricating property, low friction characteristics, light weight, etc., as the material of the cage. Polyamide 6 resin, polyamide 66 resin, polyamide 46 resin and the like are used, and those reinforced by containing a predetermined amount (for example, 20% by mass or more) of a fibrous reinforcing material such as glass fiber or carbon fiber are used (patented). Reference 1). Further, a cage using a heat-resistant polyamide resin has also been proposed for the purpose of further improving dimensional stability, heat resistance, and chemical resistance (see Patent Documents 2, 3 and 4).

Japanese Unexamined Patent Publication No. 2000-227120 Japanese Unexamined Patent Publication No. 2001-317554 Japanese Unexamined Patent Publication No. 2006-207684 Japanese Unexamined Patent Publication No. 2016-121735

When a rolling bearing incorporating a resin cage is rotated at high speed, the peripheral speed of the cage and the rolling element also becomes very high due to the high speed rotation. In particular, in grease lubrication, the grease may be blown to the outer ring side by centrifugal force, and the supply of lubricating oil supplied from the grease may be delayed. When the lubricating oil is depleted, the bearings generate heat, and in some cases, the cage is deformed, melted, and worn, and the rolling elements and raceway rings are worn. In particular, when the rolling element is made of steel, the oil film may run out due to a temporary interruption in the supply of lubricating oil during high-speed rotation, and the rolling element may be damaged by the glass fibers contained in the cage. be. Further, as the rolling element is gradually damaged, the raceway ring may also be damaged, which may lead to seizure and wear.

In addition, the mechanical properties of synthetic resins change significantly with the glass transition temperature as a boundary, and the strength and elastic modulus decrease at high temperatures. Polyamide 66 resin and polyamide 46 resin, which are general cage materials described in Patent Document 1, have glass transition temperatures of about 50 ° C. and about 78 ° C., respectively, and at temperatures exceeding that, deformation due to centrifugal force is performed. The cage and the outer ring may come into contact with each other, resulting in seizure or damage to the cage. Thus, for example, when used in high speed rotation dm · n value (the product of the pitch circle diameter dm and the track wheel rotation speed n of the rolling elements) becomes 80 × 10 ⁴ or more, the damage or cage damage by seizing It was difficult to prevent. Further, since the polyamide 66 resin and the polyamide 46 resin have a high water absorption rate and the size of the cage changes accordingly, it is necessary to control the dimensions in a state of absorbing moisture before use. Furthermore, the strength and elastic modulus of the cage after moisture absorption are significantly reduced as compared with those before moisture absorption.

On the other hand, the polyamide 9T resin and the polyamide 10T resin as described in Patent Documents 2 to 4 have a glass transition temperature of 125 ° C., which is compared with the glass transition temperature of the above-mentioned polyamide 66 resin and polyamide 46 resin. high. Further, since the polyamide 9T resin and the polyamide 10T resin are aromatic polyamides, the water absorption is lower than that of aliphatic polyamides such as the polyamide 66 resin and the polyamide 46 resin, and the deterioration of physical properties due to water absorption is also small. ..

However, in the resin cage manufactured by injection molding, there is always a weld portion formed in the region where the resin composition joins during molding. The cage often has a large number of welds due to its shape. For example, when used in high speed rotation dm · n value is 80 × 10 ⁴ or more, the stress concentration on the strength reduction and the weld portion of the weld portion due to temperature increase during operation becomes more pronounced, the weld portion Cracks are likely to occur in the container, and the strength of the cage may decrease. Further, when a steel rolling element is used, the impact applied to the cage increases, and there is a further concern about cracking in the weld portion.

For these points, in Patent Documents 2 to 4, although the resin retainer has been proposed, high speed conditions dm · n value is 80 × 10 ⁴ or more in the rolling bearing using a steel rolling elements The seizure resistance underneath and the strength of the welded part of the cage have not been fully evaluated, and there is room for further improvement.

The present invention has been made in order to cope with such a problem, in particular in grease lubrication, such as dm · n value is 80 × 10 ⁴ or more, high temperature, seizure and breakage even at high conditions It is an object of the present invention to provide a rolling bearing which does not occur.

The rolling bearing of the present invention is a rolling bearing including an inner ring and an outer ring, a plurality of steel rolling elements interposed between the inner and outer rings, and a cage for holding the rolling elements. a bearing dm · n value is used in high-speed rotation of 80 × 10 ⁴ or more, the cage, the resin composition becomes by injection molding, the resin composition composed mainly of terephthalic acid A composition using a polyamide resin composed of a dicarboxylic acid component and a diamine component or a polyetheretherketone (PEEK) resin as a base resin, and the above resin composition does not contain a fibrous reinforcing material or is the resin composition. It is characterized by containing 10% by mass or less of the fibrous reinforcing material as a whole.

The resin composition is a composition using the above-mentioned polyamide resin as a base resin, and is characterized in that the glass transition temperature of the polyamide resin is 100 ° C. or higher.

The diamine component constituting the polyamide resin is characterized by containing 1,10-decanediamine, 1,9-nonanediamine, or 1,4-butanediamine as a main component.

The resin composition is characterized by not containing the fibrous reinforcing material. Further, the rolling bearing is characterized in that it is a bearing lubricated by grease lubrication.

The rolling bearing of the present invention has a cage obtained by injection molding a resin composition, and the resin composition is a polyamide resin or PEEK resin composed of a dicarboxylic acid component containing terephthalic acid as a main component and a diamine component. Since the base resin is used, the rigidity (elasticity) of the base resin itself is high, and deformation can be reduced even under conditions of high temperature and high speed rotation. Further, since the resin composition does not contain the fibrous reinforcing material or contains 10% by mass or less of the fibrous reinforcing material with respect to the entire resin composition, the retention rate of the strength of the weld portion can be maintained high, and the steel It can withstand high-speed rotation of the rolling element made of steel and can prevent cracking in the weld part. Further, by suppressing the content of the fibrous reinforcing material, damage to the rolling element such as when the oil film runs out can be prevented. Thus, a bearing which does not cause a problem due to seizure or cage damage even when dm · n value is used in high-speed rotation of 80 × 10 ⁴ or more.

Since the above resin composition uses a polyamide resin as a base resin and the glass transition temperature of the polyamide resin is 100 ° C. or higher, it has extremely high heat resistance as compared with the polyamide 66 resin and the polyamide 46 resin. Therefore, even if the blending ratio of the fibrous reinforcing material is 10% by mass or less (including 0% by mass), it is possible to suppress deformation during high-speed rotation.

The above-mentioned polyamide resin has a dicarboxylic acid component as a main component of terephthalic acid and a diamine component as a main component of 1,10-decanediamine, 1,9-nonanediamine, or 1,4-butanediamine, and thus has oil resistance and resistance. It has excellent chemical properties and can be used under stricter usage conditions than before, such as high temperature and in oil. Further, the water absorption rate is also very small as compared with the polyamide 66 resin and the polyamide 46 resin, and dimensional changes and deterioration of physical properties due to water absorption can be suppressed as much as possible.

Since the resin composition does not contain the fibrous reinforcing material, the strength of the weld portion can be reliably maintained without being affected by the orientation of the fibrous reinforcing material.

In the case of a rolling bearing lubricated by grease lubrication, there is a concern that the bearing may generate heat or the rolling element may be damaged due to the depletion of lubricating oil. Since the content of the reinforcing material is suppressed and the aggression to the rolling element is reduced, it can be effectively used for grease lubrication and even when the rolling element is a steel ball.

It is sectional drawing in the axial direction of an angular contact ball bearing. It is a perspective view of a resin cage of a punching type. It is a partially enlarged perspective view of the crown type resin cage.

Resin cage and provided with a steel rolling elements, the rolling bearing is grease lubricated, when used in high speed rotation dm · n value is 80 × 10 ⁴ or more, early seizure due to wear of the rolling elements Ya , There is a concern that the weld of the cage may crack. As a result of diligent studies to prevent damage to the rolling elements and improve the strength of the welded portion, the present inventors have made a predetermined polyamide resin or PEEK resin as a base resin, and have not filled or filled with a fibrous reinforcing material. By using a small filling amount, damage to the rolling elements can be prevented and the strength retention rate (ratio with the non-welded part) of the welded portion is higher than when the fibrous reinforcing material is blended with the normal filling amount. I found that it would be. The present invention is based on such findings.

The cage used for the rolling bearing of the present invention is a resin cage made by injection molding a resin composition. This resin composition uses a predetermined polyamide resin or PEEK resin as a base resin, and is unfilled or blended with a predetermined amount of a fibrous reinforcing material (glass fiber or carbon fiber).

The polyamide resin used in the present invention is composed of a dicarboxylic acid component and a diamine component, and is obtained by polycondensing the dicarboxylic acid and diamine constituting each component. The dicarboxylic acid component constituting the polyamide resin contains terephthalic acid as a main component. By using terephthalic acid as the main component, the polyamide resin has excellent high-temperature rigidity. Further, the diamine component constituting the polyamide resin preferably contains an aliphatic diamine as a main component, and more preferably contains a linear aliphatic diamine as a main component.

Examples of the linear aliphatic diamine include 1,11-undecanediamine, 1,10-decanediamine, 1,9-nonanediamine, 1,8-octanediamine, 1,6-hexanediamine, and 1,4-. Butane diamine and the like can be mentioned. Since both terephthalic acid and linear aliphatic diamine have high symmetry in chemical structure, a highly crystalline polyamide resin can be obtained by using these as main components. When the number of carbon atoms of the diamine component is 12 or more, the melting point of the polyamide resin becomes low, and the cage may be deformed when used under high temperature and high speed conditions.

Among the above-mentioned linear aliphatic diamines, 1,10-decanediamine, 1,9-nonanediamine, or 1,4-butanediamine having 10, 9, and 4 carbon atoms can be used as the main component. More preferred. In this case, the polyamide resin is composed of only one diamine, which is a dicarboxylic acid component, terephthalic acid, and a diamine component, 1,10-decanediamine, 1,9-nonanediamine, and 1,4-butanediamine. You may. For example, in the case of 1,10-decanediamine, the polyamide resin is composed of only decamethylene terephthalamide units (constituent units of PA10T), and in the case of 1,9-nonanediamine, the polyamide resin is composed of nonamethylene terephthalamide units (constituent of PA9T). Unit) only, and in the case of 1,4-butanediamine, the polyamide resin may be composed only of tetramethylene terephthalamide units (constituent units of PA4T).

Further, in the above-mentioned polyamide resin, a part of terephthalic acid, which is a dicarboxylic acid component, and 1,10-decanediamine, 1,9-nonanediamine, or 1,4-butanediamine, which are diamine components, is partially copolymerized with another copolymer. It may be a copolymerized polyamide replaced with a component. The copolymerized polyamide will be described below.

First, a case where 1,10-decanediamine or 1,9-nonanediamine is the main component will be described. Examples of dicarboxylic acid components other than terephthalic acid used as other copolymerization components include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimeric acid, suberic acid, azelaic acid, sebacic acid, undecanedic acid, and dodecane. Examples thereof include aliphatic dicarboxylic acids such as diacids, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acids, and aromatic dicarboxylic acids such as phthalic acids, isophthalic acids and naphthalenedicarboxylic acids. The diamine components other than 1,10-decanediamine or 1,9-nonanediamine used as other copolymerization components include 1,2-ethanediamine, 1,3-propanediamine, and 1,4-butanediamine. 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 2-methyl-1,8-octanediamine, 1,11-undecanediamine, 1,12- Examples thereof include aliphatic diamines such as dodecanediamine, alicyclic diamines such as cyclohexanediamine, and aromatic diamines such as xylylene diamine. Further, the above-mentioned polyamide resin may be copolymerized with lactams such as caprolactam.

However, when 1,10-decanediamine or 1,9-nonanediamine is the main component, if the amount of other copolymerization components increases, the melting point and crystallinity may decrease. , 1,10-decanediamine or 1,9-nonanediamine is preferably 95 mol% or more with respect to the total number of moles (100 mol%) of the raw material monomer. Further, it is particularly preferable that the composition is substantially composed of terephthalic acid and only 1,10-decanediamine or 1,9-nonanediamine, and substantially no other copolymerization component is contained.

Next, a case where 1,4-butanediamine is the main component will be described. The polyamide resin containing 1,4-butanediamine as a main component is referred to as polyamide a to distinguish it from other polyamide resins for convenience.

Examples of the dicarboxylic acid component other than the terephthalic acid used as the other copolymerization component include an aliphatic dicarboxylic acid, an alicyclic dicarboxylic acid, an aromatic dicarboxylic acid, and a dicarboxylic acid having an aromatic ring. Examples of diamine components other than 1,4-butanediamine used as other copolymerization components include aliphatic diamines, alicyclic diamines, aromatic diamines, and diamines having an aromatic ring. Specific examples of these dicarboxylic acids and diamines will be described later.

The polyamide a is preferably a copolymerized polyamide containing a tetramethylene terephthalamide unit and a hexamethylene terephthalamide unit (a constituent unit of PA6T) as constituent units. In the following, for convenience, the tetramethylene terephthalamide unit will be referred to as PA4T unit, and the hexamethylene terephthalamide unit will be referred to as PA6T unit.

The polyamide a includes, for example, a binary copolymerized polyamide composed of only PA4T units and PA6T units, a ternary copolymerized polyamide composed of three types of monomer units including PA4T units and PA6T units, PA4T units and PA6T units. It is a quaternary copolymerized polyamide composed of four kinds of monomer units including.

When the polyamide a is a ternary copolymerized polyamide or a quaternary copolymerized polyamide, as an additional constituent unit, at least one of a monomer unit of an aromatic polyamide other than a PA4T unit and a PA6T unit and a monomer unit of an aliphatic polyamide is used. include.

The aromatic polyamide means a polyamide resin containing an aromatic ring in its molecule, and it is sufficient that the aromatic ring is contained in the molecule of the monomer unit of the aromatic polyamide. Specifically, the monomer unit may contain a portion derived from at least one of an aromatic diamine, a diamine having an aromatic ring, an aromatic dicarboxylic acid, and a dicarboxylic acid having an aromatic ring. Examples of the aromatic diamine include p-phenylenediamine and m-phenylenediamine, and examples of the diamine having an aromatic ring include m-xylylenediamine and p-xylylenediamine. Further, examples of the aromatic dicarboxylic acid include phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid and the like, and examples of the dicarboxylic acid having an aromatic ring include p-phenylene diacetic acid and the like.

In the monomer unit of the aromatic polyamide, at least one of the diamine component and the dicarboxylic acid component may have an aromatic ring, and the other polymerization component need not have an aromatic ring. For example, examples of raw materials for components having no aromatic ring include aliphatic diamines, alicyclic diamines, aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids.

Examples of diamines having no aromatic ring include linear aliphatic diamines such as tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, nonanediamine, decanediamine, undecanediamine, and dodecanediamine, 2-methylpentamethylenediamine, and 2 -Examples include branched aliphatic diamines such as ethylhexamethylenediamine and trimethylhexamethylenediamine, and alicyclic diamines such as cyclohexanediamine, cyclopentanediamine and cyclooctanediamine.

Examples of the dicarboxylic acid having no aromatic ring include aliphatic dicarboxylic acids such as adipic acid, pimelic acid, sebacic acid and dodecanedioic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid.

Based on the above, specific examples of the monomer unit of aromatic polyamide include tetramethylene isophthalamide unit (constituent unit of PA4I), hexamethylene isophthalamide unit (constituent unit of PA6I), and octamethylene terephthalamide unit (constituent unit of PA8T). , Nonamethylene terephthalamide unit (PA9T constituent unit), Decamethylene terephthalamide unit (PA10T constituent unit), Undecamethylene terephthalamide unit (PA11T constituent unit), Dodecamethylene terephthalamide unit (PA12T constituent unit), Metaxylylene adipamide unit (constituent unit of PAMXD6), metaxylylene sebacamide unit (constituent unit of PAMXD10), metaxylylene decamide unit (constituent unit of PAMXD12), paraxylylene adipamide unit (PAPXD6) (Constituent unit of PAPXD10), paraxylylene sebacamide unit (constituent unit of PAPXD10), paraxylylene dedecamide unit (constituent unit of PAPXD12), and the like.

The above-mentioned aliphatic polyamide means a polyamide having no aromatic ring in its molecule, and is a polyamide obtained by polymerizing an aliphatic diamine and an aliphatic dicarboxylic acid, a polyamide obtained by polymerizing an aliphatic diamine and an alicyclic dicarboxylic acid, and the like. Polyamide obtained by polymerizing alicyclic diamine and aliphatic dicarboxylic acid, polyamide obtained by polymerizing alicyclic diamine and alicyclic dicarboxylic acid, polyamide obtained by polymerizing aliphatic lactam and / or aliphatic aminocarboxylic acid, And their copolymers. As the aliphatic diamine, the alicyclic diamine, the aliphatic dicarboxylic acid, and the alicyclic dicarboxylic acid, the above-mentioned diamine or dicarboxylic acid can be used.

Examples of the aliphatic lactam include pyrrolidone, caprolactam, undecalactam, laurolactam and the like. Examples of the aliphatic aminocarboxylic acid include 1,11-aminoundecanoic acid.

Based on the above, specific examples of the monomer unit of aliphatic polyamide include butyric acid amide unit (PA4 constituent unit), caproamide unit (PA6 constituent unit), octaneamide unit (PA8 constituent unit), and decaneamide unit (PA10 constituent unit). Unit), undecaneamide unit (constituent unit of PA11), dodecaneamide unit (constituent unit of PA12), tetramethylene adipamide unit (constituent unit of PA46), tetramethylene sebacamide unit (constituent unit of PA410), tetra Methylene dodecamide unit (PA412 constituent unit), hexamethylene adipamide unit (PA66 constituent unit), hexamethylene sebacamide unit (PA610 constituent unit), hexamethylene dodecamide unit (PA612 constituent unit), deca Examples thereof include a methylene sebacamide unit (a constituent unit of PA1010) and a decamethylenedodecamide unit (a constituent unit of PA1012).

As the polyamide a, a ternary copolymerized polyamide is preferable, and PA4T / 6T / 66, PA4T / 6T / 6, PA4T / 6T / 410, PA4T / 6T / 46, and PA4T / 6T / 10T are more preferable. Here, "/" indicates a copolymer. In this case, the total amount of polyamides of components other than PA4T and PA6T is preferably 1 to 30 mol%, preferably 5 to 25 mol%, based on the total number of moles (100 mol%) of the raw material monomers of the entire polyamide a. Is more preferable. Since terephthalic acid is the main component of the dicarboxylic acid component constituting the polyamide a, it is excellent in high-temperature rigidity and the like.

As a method for producing the polyamide a, various polycondensation methods such as a melt polymerization method, a solid phase polymerization method, a massive polymerization method, a solution polymerization method, or a method in which these are combined can be used. Of these, the method is preferably a combination of melt polymerization and solid phase polymerization, or a combination of aqueous solution polymerization and solid phase polymerization.

In the present invention, the above-mentioned polyamide resin used as the base resin preferably has a melting point of 280 ° C. or higher. The upper limit is not particularly limited, but is preferably about 280 to 340 ° C. in consideration of molding processability and the like. The melting point range is preferably 300 to 340 ° C, more preferably 310 to 330 ° C, and particularly preferably 310 to 320 ° C. Since it has a higher melting point and excellent heat resistance than other polyamide resins generally used as cage materials (polyamide 66 resin (267 ° C), polyamide 46 resin (295 ° C)), the dm · n value is 80 ×. 10 ⁴ become as high temperature, it is used in high speed, deformation of the cage, seizure, damage and the like can be prevented. The melting point is determined by lowering the temperature of the above-mentioned polyamide resin from the molten state to 25 ° C. at a temperature lowering rate of 20 ° C./min in an inert gas atmosphere using a differential scanning calorimeter (DSC), and then 20 ° C./min. It can be measured as the temperature (Tm) of the endothermic peak that appears when the temperature is raised at the rate of temperature rise.

The polyamide resin preferably has a glass transition temperature of 100 ° C. or higher. More preferably, it is 120 ° C. or higher. Other polyamide resins commonly used as a retainer material (polyamide 66 resin (same 49 ° C.), polyamide 46 (same 78 ° C.)) Since the glass transition temperature is higher than, dm · n value 80 × 10 ⁴ or more Even when used at high temperature and high speed rotation, deformation of the cage can be suppressed, and heat generation due to sliding friction between the rolling element and the cage can be reduced. The glass transition temperature is a stepped shape that appears when the polyamide resin is rapidly cooled in an inert gas atmosphere using a differential scanning calorimeter (DSC) and then raised at a heating rate of 20 ° C./min. It can be measured as the temperature (Tg) at the midpoint of the heat absorption peak of (JIS K7121).

The resin composition constituting the cage does not contain the fibrous reinforcing material, or contains 10% by mass or less of the fibrous reinforcing material with respect to the entire resin composition. Even when the fibrous reinforcing material is blended in the resin composition, by reducing the blending amount to 10% by mass or less, the aggression to the rolling element due to sliding with the rolling element during high-speed rotation can be suppressed. Can be done. As a result, it is possible to prevent wear of rolling elements such as steel balls, seizure of bearings, and wear of raceway rings. Further, by blending a fibrous reinforcing material, it is possible to increase the rigidity (particularly tensile strength) of the cage, reduce the deformation of the cage even under the conditions of high temperature and high speed rotation, and reduce the amount of heat generated. The blending amount of the fibrous reinforcing material in the resin composition is preferably less than 10% by mass, more preferably less than 5% by mass, still more preferably less than 3% by mass, and 0% by mass (included) with respect to the entire resin composition. Not) is particularly preferred.

As the fibrous reinforcing material, glass fiber or carbon fiber is used. The glass fiber is obtained by spinning from inorganic glass containing _{SiO 2} , B ₂ O ₃ , Al ₂ O ₃ , CaO, MgO, Na ₂ O, K ₂ O, Fe ₂ O _{3 and the like as main components.} Generally, non-alkali glass (E glass), alkali-containing glass (C glass, A glass) and the like can be used. Non-alkali glass is preferable in consideration of the influence on the polyamide resin. The non-alkali glass is a borosilicate glass containing almost no alkaline component in the composition. Since it contains almost no alkaline component, it has almost no effect on the polyamide resin and the characteristics of the resin composition do not change. Examples of the glass fiber include Asahi Fiber Glass Co., Ltd .: 03JAFT692, MF03MB120, MF06MB120 and the like.

The carbon fiber can be used regardless of the type of raw material such as polyacrylonitrile-based (PAN-based), pitch-based, rayon-based, and lignin-poval-based mixture. Examples of pitch-based carbon fibers include Kureha M-101S, M-107S, M-101F, M-201S, M-207S, M-2007S, C-103S, and C. -106S, C-203S and the like can be mentioned. Examples of the PAN-based carbon fiber include Toho Tenax Co., Ltd .: Vesfight HTA-CMF0160-0H, HTA-CMF0040-0H, HTA-C6, HTA-C6-S, and Toray Industries, Inc .: Treca. Examples thereof include MLD-30, MLD-300, T008, and T010.

If necessary, additives other than the above-mentioned fibrous reinforcing material may be added to the resin composition in the present invention as long as the cage function and injection moldability are not impaired. As other additives, for example, solid lubricants, inorganic fillers, antioxidants, antistatic agents, mold release materials and the like can be blended.

If necessary, each material constituting the above resin composition is mixed by a Henschel mixer, a ball mixer, a ribbon blender, or the like, and then melt-kneaded by a melt extruder such as a twin-screw kneading extruder to pellet for molding. Can be obtained. The filler may be charged by using a side feed when melt-kneading with a twin-screw extruder or the like. A cage is molded by injection molding using these molding pellets. At the time of injection molding, the resin temperature is set to be equal to or higher than the melting point of the base resin, and the mold temperature is kept below the glass transition temperature of the base resin.

As described above, the resin composition of the cage used for the rolling bearing of the present invention is a fibrous reinforcing material (glass fiber or carbon fiber) of 10% by mass or less (including 0% by mass) in a predetermined polyamide resin or PEEK resin. Has a high melting point and glass transition temperature, exhibits excellent heat resistance, oil resistance, chemical resistance, dimensional stability, and toughness, and has high mechanical properties. Therefore, the cage according to the present invention can be used for a long time under harsh environmental conditions such as a high speed rotation range (high temperature atmosphere, contact with oil or chemicals, high speed rotation condition, high load condition, high humidity environment, etc.). It will be a durable cage.

Further, since the resin composition has low water absorption, it is possible to suppress swelling due to water absorption / moisture absorption, dimensional change due to expansion, and deterioration of physical properties. The cage according to the present invention has excellent dimensional stability and can be provided at low cost as a cage for applications requiring accuracy.

The rolling bearing and the cage thereof of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is an axial cross-sectional view of an angular contact ball bearing which is an example of a rolling bearing of the present invention, and FIG. 2 is a perspective view and a partially enlarged view of a cage (punch type) in the rolling bearing of FIG. .. As shown in FIG. 1, the angular contact ball bearing 1 holds the inner ring 2, the outer ring 3, a plurality of balls 4 interposed between the inner ring 2 and the outer ring 3, and the balls 4 held at regular intervals in the circumferential direction. It is equipped with a vessel 5. The inner ring 2 and the outer ring 3 and the ball 4 are in contact with each other with a predetermined angle θ (contact angle) with respect to the radial center line, and a radial load and an axial load in one direction can be applied. Grease is sealed around the ball 4, and lubrication is performed by grease lubrication.

In the angular contact ball bearing 1, the inner ring 2, the outer ring 3, and the ball 4 are all made of steel. Any material generally used as a bearing material can be used as the steel material. For example, high carbon chrome bearing steel (SUJ1, SUJ2, SUJ3, SUJ4, SUJ5, etc .; JIS G 4805), carburized steel (SCr420, SCM420, etc .; JIS G 4053), stainless steel (SUS440C, etc .; JIS G 4303) and the like are used. be able to.

The angular contact ball bearing 1 as shown in FIG. 1 is used for high-speed rotation and the like. In the present invention, as the cage 5, an injection molded product having a resin composition based on the above-mentioned polyamide resin or PEEK resin having a high glass transition temperature and excellent rigidity is used, and therefore, under high temperature and high speed rotation conditions. Also, the deformation of the cage can be suppressed. Further, since the above-mentioned polyamide resin and PEEK resin are also excellent in self-lubricating property and low friction property, the amount of heat generated by the friction between the ball 4 and the cage 5 can be reduced, the temperature rise is suppressed, and seizure occurs. Does not occur. Therefore, the bearing can be operated for a long time even under high temperature and high speed rotation conditions.

As shown in FIG. 2A, the cage 5 is provided with a plurality of pockets 6 for holding balls, which are rolling elements, in the annular cage body 5a at regular intervals in the circumferential direction. The planar shape of the pocket 6 is a flat circular shape, but it may be a perfect circle. Here, the flat circular shape means a pocket having a gap that matches the amount of pocket gap (difference between the inner diameter of the pocket and the diameter of the ball) required for the perfect circular shape, and pockets on both sides thereof that approximately approximate the radius of the ball. A flat circle formed by the radius of the surface. With such a shape, the amount of pocket gap in the circumferential direction of the rotation axis is increased to absorb the advance delay of the ball, so that the load applied to the cage can be reduced.

The cage 5 is a punching type cage, and is obtained by molding a base material by injection molding using the above-mentioned resin composition and then processing a pocket portion by cutting. Since the cage 5 is an injection-molded body, as shown in FIG. 2B, a weld portion 7 is formed in a region where the resin composition joins during molding. The weld portion 7 is a portion of the cage ring that is easily broken due to stress concentration. The position of the weld portion differs depending on the gate position, but for example, as shown in FIG. 2 (b), in the vicinity of the center of the pillar portion of the cage main body 5a between the pockets 6 adjacent in the circumferential direction, in the cage axial direction. Is formed along. The weld portion 7 may or may not be exposed in the pocket 6. In the cage of the present invention, a resin formed by using the above-mentioned polyamide resin or PEEK resin as a base resin and blending it with a fibrous reinforcing material (glass fiber or carbon fiber) of 10% by mass or less (including 0% by mass). Since it is a molded product obtained by injection molding the composition, it has excellent strength at the weld portion 7 and can prevent cracking at the weld portion. Specifically, as shown in Examples described later, the strength is higher than that in the case where only the base resin is changed to another polyamide resin. Even when used at high speed rotation, cracking at the weld portion can be prevented.

In FIGS. 1 and 2, an angular contact ball bearing has been described as an example of the rolling bearing of the present invention, but the bearing type to which the present invention can be applied is not limited to this, and other ball bearings, tapered roller bearings, and self-aligning rollers are used. It can also be applied to bearings, needle roller bearings, etc.

As another example of the cage according to the present invention, a crown-shaped cage will be described with reference to FIG. FIG. 3 is a partially enlarged perspective view of a crown-shaped cage obtained by injection molding the above-mentioned resin composition. As shown in FIG. 3, the cage 8 forms a pair of opposing holding claws 10 on the upper surface of the annular cage main body 9 at a constant pitch in the circumferential direction, and the opposing holding claws 10 approach each other. A pocket 11 for holding a ball as a rolling element is formed between the holding claws 10 while bending in the direction of bending. Further, a flat portion 12 serving as a rising reference surface of the holding claws 10 is formed between the back surfaces of the holding claws 10 adjacent to each other in the adjacent pockets 11. The holding claw 10 has a curved tip portion 10a.

When the crown mold cage shown in FIG. 3 is injection-molded, the curved tip portion 10a of the holding claw 10 is forcibly removed when it is taken out from the mold. This is because the diameter of the pocket opening is smaller than the inner diameter of the pocket 11, and the inner diameter mold for forming the pocket elastically expands the diameter of the pocket opening to the inner diameter of the pocket to release the mold. .. In the cage according to the present invention, since the above-mentioned resin composition is used as the cage material, it is possible to prevent cracks and whitening of the tip of the retaining claw during the above-mentioned forcible removal during molding while maintaining the rigidity at the time of use. obtain. In particular, as described above, by setting the blending amount of the fibrous reinforcing material contained in the resin composition to 10% by mass or less (including 0% by mass) with respect to the entire resin composition, it becomes easy to prevent this. ..

Rolling bearing of the present invention, because with the above-described retainer is sufficient available in steel rolling elements in dm · n value 80 × 10 ⁴ or more high-speed rotation condition in grease lubrication.

The present invention will be further described below with reference to examples, but the present invention is not limited thereto.

The raw materials used in Examples and Comparative Examples are shown below.
(1) Resin material Polyamide resin A: Genesta N1000 manufactured by Kuraray Co., Ltd. (resin using terephthalic acid and 1,9-nonanediamine as main components)
Polyamide resin B: XecoT XN500 manufactured by Unitika Ltd. (resin using terephthalic acid and 1,10-decanediamine as main components)
Polyamide resin C: ForTii Ace 1131 manufactured by DSM (resin using terephthalic acid and 1,4-butanediamine as main components)
Polyamide 66 resin: Amylan CM3001 manufactured by Toray Industries, Inc.
Polyamide 46 resin: DSM stanil TW300
PEEK resin: PEEK450G manufactured by Victrex
(2) Fibrous reinforcing material Glass fiber: 03JAFT692 manufactured by Asahi Fiber Glass Co., Ltd. (average fiber diameter 10 μm, average fiber length 3 mm)
Carbon fiber: HTA-C6 manufactured by Toho Tenax Co., Ltd. (average fiber diameter 7 μm, average fiber length 6 mm)

Examples 1 to 4, Comparative Examples 1 to 7, Reference Examples 1 to 3.
Using the resin composition in which these raw materials were blended in the ratio shown in Table 1, cages for angular contact ball bearings of Examples, Comparative Examples, and Reference Examples were prepared, and various tests were carried out. A twin-screw extruder was used to produce the composition. Glass fibers and carbon fibers were supplied using a fixed-quantity side feeder to prevent breakage, and extruded to granulate. The obtained molding pellets were molded by an in-line screw type injection molding machine to obtain a desired cage shape (outer diameter 93 mm, inner diameter 88 mm, width 13 mm). The shape of the cage was the punching type cage shown in FIG. After molding, humidity control treatment was carried out in an atmosphere of 80 ° C. and 95% relative humidity, and each test was carried out on the water-absorbed material.

[Bearing temperature test]
The by going bearing test increased sequentially rpm until dm · n value 80 × 10 ⁴ by using angular contact ball bearings were performed. The cages of Examples, Comparative Examples, and Reference Examples were incorporated, steel balls (material: SUJ2) were used for the rolling elements, grease as a lubricant was sealed, and comparative tests were conducted using angular contact ball bearings. In the test, the outer ring temperature was measured, and in consideration of accuracy and durability, up to 50 ° C. was used as a reference, less than 50 ° C. was accepted, and those having an temperature rise of 50 ° C. or higher were rejected. The results are shown in Table 1.

[High-speed rotation test]
Use angular ball bearing, as an accelerated test was carried out high-speed rotation test in dm · n value 144 × 10 ^4. Angular that incorporates the cages of Examples, Comparative Examples, and Reference Examples, uses steel balls (material: SUJ2) for the rolling elements, encloses grease as a lubricant, and provides non-contact seals on both sides to seal. A comparative test was conducted using ball bearings. The test was performed for 30 hours, and those that could be tested for 30 hours were rejected, and those that were burned were rejected. The results are shown in Table 1.

[Weld strength]
From dm · n value 80 × 10 ⁴ or more use conditions (tensile strength of the weld portion) breaking strength of the cage is a high strength is required. As a substitute characteristic of this, a welded test piece in the shape of a No. 1 dumbbell test piece in ISO was molded, and the test piece was humidity-controlled at 80 ° C. × 95% RH for 5 hours, and a tensile tester manufactured by Shimadzu Corporation (Autograph). Weld strength was measured using AG50KNX) at a tensile speed of 10 mm / min. The results are shown in Table 1.

As shown in Table 1, in the bearing temperature test, the outer ring temperature from around the dm · n value exceeds the 80 × 10 ⁴ in the comparative example became 50 ° C. or higher. On the other hand, in the examples and reference examples, spikes outer ring temperature even dm · n value is a 80 × 10 ⁴ is not observed, was maintained less than 50 ° C.. Further, in the high-speed rotation test, in the examples and the reference examples, the test for 30 hours was completed without causing seizure. On the other hand, in Comparative Examples 1 to 5 in which glass fibers and carbon fibers were blended in a predetermined amount or more, seizure occurred in all of them within 30 hours, and the surface of the rolling elements was roughened. Further, in Comparative Examples 6 to 7, deformation was observed in the pocket of the cage due to the temperature rise.

Regarding the weld strength, the cages of Examples and Reference Examples showed good strength of 80 MPa or more. On the other hand, the cages of Comparative Examples except Comparative Example 5 were less than 80 MPa.

Generally, by blending a fibrous reinforcing material such as glass fiber, the tensile strength of the resin molded product is improved. On the other hand, from the results in Table 1, in the resin composition in which a polyamide resin such as a polyamide 9T resin, a polyamide 10T resin, or a polyamide 4T resin or a PEEK resin is filled with a fibrous reinforcing material, the weld strength depends on the orientation of the fibrous reinforcing material. Is considered to have decreased. In particular, the polyamide resin or PEEK resin used as the base resin in the present invention has a high elastic modulus of its own, and when a fibrous reinforcing material is added, the elastic modulus is further increased, and the cage is less likely to be deformed. However, when stress is applied, the stress is concentrated on the weld portion of the cage, so that the breaking strength of the cage may decrease. Therefore, by setting the blending amount of the fibrous reinforcing material to a predetermined value or less, the weld strength can be increased while ensuring the tensile strength to some extent. Further, since the damage to the mating material is reduced, seizure of the rolling bearing can be suitably prevented even under the condition that the rolling element is a steel ball and grease lubricated and the rolling element rotates at high speed.

Rolling bearing of the present invention does not cause seizure or breakage even at high conditions such as dm · n value is 80 × 10 ⁴ or more, an automobile, a motor, a variety of rolling bearings used in machine tools Available. In particular, it is useful for versatile rolling bearings in which the rolling element is a steel ball and the lubrication is grease lubrication.

1 Angular contact ball bearing (rolling bearing)
2 Inner ring 3 Outer ring 4 Ball (rolling element)
5 Cage 6 Pocket 7 Weld part 8 Cage 9 Cage body 10 Claw 11 Pocket 12 Flat part

Claims (5)

A rolling bearing including an inner ring and an outer ring, a plurality of steel rolling elements interposed between the inner and outer rings, and a cage for holding the rolling elements.
The rolling bearing is a bearing dm · n value is used in high-speed rotation of 80 × 10 ⁴ or more,
The cage is formed by injection molding a resin composition, and the resin composition uses a polyamide resin containing a dicarboxylic acid component containing terephthalic acid as a main component and a diamine component, or a polyetheretherketone resin as a base resin. Composition
A rolling bearing characterized in that the resin composition does not contain a fibrous reinforcing material or contains 10% by mass or less of the fibrous reinforcing material with respect to the entire resin composition. The rolling bearing according to claim 1, wherein the resin composition is a composition using the polyamide resin as a base resin, and the glass transition temperature of the polyamide resin is 100 ° C. or higher. The rolling bearing according to claim 2, wherein the diamine component constituting the polyamide resin contains 1,10-decanediamine, 1,9-nonanediamine, or 1,4-butanediamine as a main component. The rolling bearing according to any one of claims 1 to 3, wherein the resin composition does not contain the fibrous reinforcing material. The rolling bearing according to any one of claims 1 to 4, wherein the rolling bearing is a bearing lubricated by grease lubrication.

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