JP2017057956A - Cage for rolling bearing and rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cage for a rolling bearing in which seizure and breakage do not occur even in such a high-temperature/high-speed condition that a dm*n value becomes not smaller than 80×10, and the rolling bearing using the cage.SOLUTION: A rolling bearing 1 comprises an inner ring 2 and an outer ring 3, a plurality of rolling bodies 4 which are interposed between the inner ring and the outer ring, and a cage 5 for holding the rolling bodies 4. The cage 5 is an injection-molding body having a resin composition, the resin composition is obtained by blending a fiber-reinforced material and a fluorine resin to a polyamide resin which is composed of a dicarboxylic acid component and a diamine component, the dicarboxylic acid component uses a terephthalic acid as a main component, the diamine component uses 1, 10-decane diamine as a main component, and the fiber-reinforced material contains glass fibers at 15 to 40 mass%, or carbon fibers at 10 to 30 mass% with respect to the resin composition as a whole, and also contains the fluorine resin at 3 to 20 mass% with respect to the resin composition as a whole.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rolling bearing cage for rolling bearings used in automobiles, motors, machine tools and the like, and more particularly to a resin rolling bearing cage formed by molding a predetermined resin composition.

  Conventional ball bearings are generally press-molded as a cage that holds a plurality of rolling elements arranged in a circumferential direction between a raceway surface of an outer ring and a raceway surface of an inner ring so as to roll freely. Iron ones are used. However, when the rotational speed of the bearing is increased, the friction caused by the sliding contact between the rolling element and the cage is increased in the iron cage, and the temperature rise of the bearing is increased. . Therefore, it is considered effective to use a cage made by injection molding a synthetic resin that is superior to iron in terms of self-lubricating properties, low friction characteristics, light weight, etc. Polyamide 6 resin, polyamide 66 resin, polyamide 46 resin, and the like are used, and those containing glass fibers and strengthened as necessary are used (see Patent Document 1). A cage using polyamide 9T resin has also been proposed for the purpose of improving dimensional stability, heat resistance, and chemical resistance (see Patent Documents 2 and 3).

JP 2000-227120 A JP 2001-317554 A JP 2006-207684 A

  When a rolling bearing incorporating a resin cage is rotated at high speed, the cage may be deformed as a result of centrifugal force generated by the high speed rotation acting on the cage. When the cage is deformed, friction between the cage and the balls held by the cage increases, which causes heat generation of the bearing. Further, when the cage is deformed, contact with the outer ring of the bearing also occurs, and the frictional heat due to this contact may melt the resin and the rolling bearing may not rotate (seize). Therefore, the resin cage incorporated in the rolling bearing used at such high speed rotation is required not to be deformed due to mechanical and / or thermal stress.

However, the mechanical properties of the synthetic resin change greatly at the boundary of the glass transition temperature, 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 80 ° C., respectively. , Due to the occurrence of deformation due to centrifugal force, increased heat generation due to sliding friction between the cage and rolling elements, and further increase in bearing temperature, the cage and outer ring may come into contact with each other, resulting in seizure and cage damage . For this reason, for example, when used at a high speed rotation in which the dm · n value (product of the pitch circle diameter dm of the rolling element and the raceway rotation speed n) is 60 × 10 ⁴ or more (more than 80 × 10 ⁴ or more) It was difficult to prevent damage due to seizure and breakage of the cage. Further, since the polyamide 66 resin and the polyamide 46 resin have a high water absorption rate and the cage dimensions change accordingly, it is necessary to control the dimensions in a moisture-absorbed state. Furthermore, the strength and elastic modulus of the cage after moisture absorption are greatly reduced as compared to before moisture absorption.

  On the other hand, the polyamide 9T resin as described in Patent Documents 2 and 3 has a glass transition temperature of 125 ° C., which is higher than the glass transition temperatures of the above-mentioned polyamide 66 resin and polyamide 46 resin. However, even in the polyamide 9T resin, when the lubrication state is deteriorated for some reason with respect to the temperature rise under the high-speed rotation condition, the cage temperature may be higher than the glass transition temperature, and problems such as deformation may occur. There is.

  Further, since the polyamide 9T resin is an aromatic polyamide, the water absorption is lower than that of an aliphatic polyamide such as polyamide 66 resin or polyamide 46 resin. However, a resin cage produced by injection molding always has a weld portion formed in a region where the resin composition merges at the time of molding. Polyamide 9T resin has a high elastic modulus and low toughness. As a result, stress concentration occurs in the weld portion during use, and cracks are likely to occur in the weld portion, which may reduce the strength of the cage.

With respect to these points, Patent Document 2 proposes a cage using a polyamide 9T resin, but does not suggest its seizure resistance performance. Patent Document 3 describes that the dm · n value is about 60 × 10 ⁴ for the temperature rise, but does not suggest the strength of the cage including the weld portion.

  When a large amount of a fibrous filler such as glass fiber is blended in the polyamide resin, the injection moldability and dimensional accuracy cannot be expected, and the mechanical properties may be deteriorated. In particular, a crack is generated in the weld portion during injection molding in a machined cage, and a crack or whitening of the tip of the holding claw occurs due to excessive removal during injection molding in a crown type cage. In addition, the fibrous filler may easily generate heat during use due to a decrease in slidability.

The present invention has been made to cope with such a problem, and is for a rolling bearing that does not cause seizure or breakage even under high temperature and high speed conditions such that the dm · n value is 80 × 10 ⁴ or more. It is an object to provide a cage and a rolling bearing using the cage.

The rolling bearing cage of the present invention is a rolling bearing cage formed by injection molding of a resin composition. The resin composition is a composition in which a polyamide resin composed of a dicarboxylic acid component and a diamine component is used as a base resin, and a fibrous reinforcing material and a fluororesin are blended therein. The dicarboxylic acid component is mainly composed of terephthalic acid, The diamine component is mainly composed of 1,10-decanediamine, and the fibrous reinforcing material is glass fiber or carbon fiber, and the blending ratio with respect to the whole resin composition is 15 to 40% by mass of the glass fiber, The carbon fiber is 10 to 30% by mass, and the fluororesin is 3 to 20% by mass.
Further, the polyamide resin contains carbon 14 which is a radioisotope.

The rolling bearing of the present invention is a rolling bearing comprising an inner ring and an outer ring, a plurality of rolling elements interposed between the inner and outer rings, and a cage that holds the rolling elements, and the cage is the present invention. It is characterized by being a rolling bearing retainer. In particular, the rolling bearing is a bearing used at high speed rotation with a dm · n value of 80 × 10 ⁴ or more.

The cage for a rolling bearing according to the present invention includes a predetermined polyamide resin mainly composed of terephthalic acid as a dicarboxylic acid component and 1,10-decanediamine as a diamine component, and 15 to 40% by mass of glass fiber or carbon. Since a resin composition containing 10 to 30% by mass of fiber and 3 to 20% by mass of fluororesin is injection-molded, the rigidity (elastic modulus) is high, and deformation is small even under conditions of high temperature and high speed rotation. In addition, the amount of heat generated can be reduced by the lubrication effect of the fluororesin, and seizure and breakage can be prevented even when used at high speed rotation where the dm · n value is 80 × 10 ⁴ or more. In addition, since the dicarboxylic acid component is a terephthalic acid and the diamine component is a polyamide resin whose main component is 1,10-decanediamine, the crystallization speed is very fast and the cycle time during molding is shortened. Can improve productivity.

  Since the above-mentioned polyamide resin used as the base resin has a melting point of 310 ° C. or higher, it is very different from the polyamide 66 resin (melting point 267 ° C.) and the polyamide 46 resin (melting point 295 ° C.) that are most frequently used as cage materials. High heat resistance. Moreover, even if it compares with polyamide 9T resin (melting | fusing point 306 degreeC), it equips with the heat resistance equivalent or more. For this reason, deformation can be reduced even under conditions of high temperature and high speed rotation.

  Moreover, it is superior to the above-mentioned other polyamide resins in oil resistance and chemical resistance, and can be used even under severer use conditions than conventional, for example, high temperature and in oil. Further, the water absorption rate is about the same as that of the polyamide 9T resin, which is very small as compared with the polyamide 66 resin and the polyamide 46 resin, and the dimensional change and physical property deterioration due to water absorption can be suppressed as much as possible.

  A part of the components constituting the polyamide resin (for example, 1,10-decanediamine) is synthesized from plants, and since the polyamide resin contains carbon 14 which is a radioisotope, it is compared with a petroleum-derived synthetic resin. Thus, the substantial carbon dioxide emission during combustion can be reduced.

The rolling bearing of the present invention comprises an inner ring and an outer ring, a plurality of rolling elements interposed between the inner and outer rings, and the retainer of the present invention that holds the rolling elements, and therefore has a dm · n value of 80. Even when used at a high-speed rotation of × 10 ⁴ or more, the bearing does not cause defects due to seizure or breakage of the cage.

It is an axial sectional view of an angular contact ball bearing. It is a perspective view etc. of a machined type resin cage. It is a partial expansion perspective view of a crown type resin cage. It is a figure which shows the outline | summary of a cage tension test.

  The rolling bearing cage of the present invention is a resin cage formed by injection molding of a resin composition. The resin composition used as the resin material includes a predetermined polyamide resin as a base resin, and a predetermined amount of fibrous reinforcing material (glass fiber or carbon fiber) and a fluororesin.

  The polyamide resin used in the present invention comprises a dicarboxylic acid component and a diamine component, and is obtained by polycondensation of dicarboxylic acid and diamine constituting each component. The dicarboxylic acid component constituting the polyamide resin has terephthalic acid as a main component. By using terephthalic acid as the main component, the polyamide resin has excellent high-temperature rigidity. Moreover, the diamine component which comprises the said polyamide resin has 1, 10-decane diamine as a main component. 1,10-decanediamine is a linear aliphatic diamine. Since both terephthalic acid and 1,10-decanediamine have high symmetry in chemical structure, a highly crystalline polyamide resin can be obtained by using them as the main components.

  In the present invention, as described above, a linear 1,10-decanediamine having 10 carbon atoms is used as a main component for the diamine component constituting the polyamide resin. Since the number of carbon atoms in the monomer unit of the diamine component as the main component is 10 and an even number, a more stable crystal structure is obtained and crystallinity is improved (even-odd effect) as compared with the case of an odd number. Further, when the diamine component as a main component has 8 or less carbon atoms, the melting point of the polyamide resin may exceed the decomposition temperature. When the diamine component has 12 or more carbon atoms, the polyamide resin has a low melting point, and the cage may be deformed when used under high temperature and high speed conditions. Note that the diamine having 9 or 11 carbon atoms may have insufficient crystallinity due to the even-odd effect of the polyamide resin.

  The polyamide resin may be obtained by replacing a part of terephthalic acid, which is a dicarboxylic acid component, and 1,10-decanediamine, which is a diamine component, with another copolymer component. However, since the melting point and crystallinity decrease when the amount of other copolymerization components increases, the total amount of terephthalic acid and 1,10-decanediamine as the main components is the total number of moles of raw material monomers (100 mol%). On the other hand, it is preferable to set it as 95 mol% or more. Further, it is particularly preferable that it is substantially composed only of terephthalic acid and 1,10-decanediamine, and does not substantially contain other copolymerization components.

  Dicarboxylic acid components other than terephthalic acid used as other copolymerization components include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecane Examples include aliphatic dicarboxylic acids such as diacids, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, and aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and naphthalenedicarboxylic acid. Moreover, as diamine components other than 1,10-decanediamine used as other copolymerization components, 1,2-ethanediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine are used. 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, and other aliphatic diamines, cyclohexanediamine, etc. Aromatic diamines such as alicyclic diamine and xylylenediamine. The polyamide resin may be copolymerized with lactams such as caprolactam.

  The weight average molecular weight of the polyamide resin is preferably 15000 to 50000, more preferably 26000 to 50000. When the weight average molecular weight of the polyamide resin is less than 15000, the rigidity of the resin is lowered, and the cage may be deformed during high-speed rotation. On the other hand, when the weight average molecular weight of the polyamide resin exceeds 50,000, crystallization is slowed down and fluidity during injection molding is lowered. The relative viscosity of the polyamide resin is not particularly limited, but in order to facilitate the molding of the cage, the relative viscosity measured at a concentration of 1 g / dL and 25 ° C. with 96 mass% sulfuric acid as the solvent is 2 0.0 or more is preferable.

The polyamide resin preferably has a melting point of 310 ° C. or higher. Moreover, although an upper limit is not specifically limited, It is preferable to set it as about 320-340 degreeC in consideration of moldability. The melting point range is preferably 310 to 340 ° C, more preferably 310 to 330 ° C, and particularly preferably 310 to 320 ° C. Higher melting point and superior heat resistance than other polyamide resins commonly used as cage materials (polyamide 66 resin (267 ° C), polyamide 46 resin (295 ° C), polyamide 9T resin (306 ° C)) Therefore, even if the dm · n value is 80 × 10 ⁴ or more and used at a high temperature and a high speed rotation, the cage can be prevented from being deformed, seized or damaged. The melting point was determined by using a differential scanning calorimeter (DSC) to lower the polyamide resin from a molten state to 25 ° C. at a temperature lowering rate of 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 130 ° C. or higher. More preferably, it is 150 degreeC or more. Since the glass transition temperature is higher than other polyamide resins (polyamide 66 resin (49 ° C.), polyamide 46 resin (78 ° C.), and polyamide 9T resin (125 ° C.)) that are generally used as cage materials, dm · Even when the n value is 80 × 10 ⁴ or more and used at a high temperature and high speed, deformation of the cage can be suppressed, and heat generation due to sliding friction between the rolling element and the cage can be reduced. Is a stepwise endothermic peak that appears when the polyamide resin is quenched in an inert gas atmosphere using a differential scanning calorimeter (DSC) and then heated at a rate of temperature increase of 20 ° C./min. It can be measured as the point temperature (Tg) (JIS K7121).

Glass fiber or carbon fiber is used as the fibrous reinforcing material to be blended with the polyamide resin as the base resin. 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 or the like as a main component. Generally, alkali-free glass (E glass), alkali-containing glass (C glass, A glass) or the like can be used. In view of the influence on the polyamide resin, alkali-free glass is preferable. The alkali-free glass is a borosilicate glass that contains almost no alkali component in the composition. Since the alkali component is hardly contained, there is almost no influence on the polyamide resin, and the properties 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 kind of raw material such as polyacrylonitrile (PAN), pitch, rayon, lignin-poval mixture. Examples of pitch-based carbon fibers include: Kureha Co., Ltd .: Kureka M-101S, M-107S, M-101F, M-201S, M-207S, M-2007S, C-103S, C -106S, C-203S and the like. Examples of the PAN-based carbon fiber include: Toho Tenax Co., Ltd .: Besfight HTA-CMF0160-0H, HTA-CMF0040-0H, HTA-C6, HTA-C6-S, or Toray Industries, Inc. MLD-30, MLD-300, T008, T010 and the like.

  As the fluororesin blended with the polyamide resin, polytetrafluoroethylene (hereinafter referred to as PTFE, thermal decomposition temperature of about 490 ° C. or higher), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (hereinafter referred to as PFA, heat Decomposition temperature of about 464 ° C. or higher), tetrafluoroethylene-hexafluoropropylene copolymer (hereinafter referred to as FEP, thermal decomposition temperature of about 419 ° C. or higher), tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer ( Hereinafter, referred to as EPE, thermal decomposition temperature of about 440 ° C.). In addition to these, polychlorotrifluoroethylene (hereinafter referred to as PCTFE; thermal decomposition temperature of about 347 to 418 ° C.), tetrafluoroethylene-ethylene copolymer (hereinafter referred to as ETFE; thermal decomposition temperature of about 347 ° C.). ), Chlorotrifluoroethylene-ethylene copolymer (hereinafter referred to as ECTFE, thermal decomposition temperature of about 330 ° C. or higher), polyvinylidene fluoride (hereinafter referred to as PVDF, thermal decomposition temperature of about 400 to 475 ° C.), polyvinyl Fluoride (hereinafter referred to as PVF, thermal decomposition temperature of about 372 to 480 ° C.) and the like. Further, the fluororesin may be a fluorinated polyolefin such as two or more types of copolymers or a terpolymer with a polymerization ratio of about 1:10 to 10: 1 of the monomer of the fluororesin. These show properties as solid lubricants.

  Among fluororesins, PTFE, PFA, FEP and the like are preferable because of their excellent high temperature characteristics. For this reason, the composition containing the resin can withstand a relatively good heat history in the process of melt-molding the resin, and withstands relatively well even under high-speed conditions. In particular, PTFE is a state in which all of the skeleton carbon atoms are surrounded by fluorine atoms, and due to the strong bond between C and F, the heat resistant temperature is high among fluorine-based resins, and the low friction coefficient, non- Excellent properties such as adhesiveness and chemical resistance. PTFE is a resin that can be compression-molded with a tetrafluoroethylene homopolymer, and its thermal decomposition temperature is about 508 to 538 ° C.

  When PTFE is added in the form of a powder, if it is made into a powder, it can be used without any particular limitation on its shape and size, but it is granular and has a particle size of 75 μm or less, preferably an average particle size of 1 In order to make the resin composition uniform, those having ˜50 μm, more preferably those having an average particle diameter of 5 to 30 μm are preferable. The particle diameter can be evaluated by a particle size analyzer such as a Coulter counter or a microtrack, in addition to confirmation with a scanning electron microscope.

  Moreover, it can replace with the PTFE powder of a virgin material, and can use the reproduction | regeneration PTFE powder. Since the regenerated PTFE powder is a powder obtained by calcining a virgin material once and then pulverizing it, the melt viscosity of the resin composition may be remarkably increased as when PTFE of the virgin material is added to the resin composition. And does not hinder injection moldability. Further, since the regenerated PTFE powder is fired once, a stable molded product can be obtained without causing a dimensional change, a shape change, or a crack of the resin molded product mixed with the recycled PTFE powder. In addition, it is more preferable to use PTFE powder having a fine particle size instead of or using PTFE powder that has been subjected to γ-ray irradiation treatment to reduce the molecular weight. The average particle diameter of such regenerated PTFE-containing PTFE is also preferably the same average particle diameter as described above.

  Examples of commercially available PTFE powder containing regenerated PTFE include Kitamura Co., Ltd .: KT300M, KT300H, KT400M, KT400H, KT600M, KTL450, KTL610, KTL620, and the like.

  When glass fiber is used as the fibrous reinforcing material, the blending amount is 15 to 40% by mass with respect to the entire resin composition. When carbon fiber is used as the fibrous reinforcing material, the blending amount is 10 to 30% by mass with respect to the entire resin composition. A fluororesin shall be 3-20 mass%. By setting the glass fiber or carbon fiber in the above range, the rigidity of the cage can be increased, and deformation of the cage can be reduced even under conditions of high temperature and high speed rotation. Moreover, the heat generation of the cage can be suppressed by the fluororesin. Furthermore, if the shape of the cage is forced to be removed at the time of injection molding or if sufficient strength (tensile strength) of the weld portion is taken into consideration, the glass fiber content relative to the entire resin composition 20-30 mass% is preferable, and when using carbon fiber, the compounding quantity of the carbon fiber has preferable 15-25 mass%. The fluororesin is preferably 5 to 15% by mass based on the balance of strength and lubricity with respect to the entire resin composition.

  By blending 3 to 20% by mass, preferably 5 to 15% by mass of the fluororesin, in addition to the characteristics excellent in oil resistance and chemical resistance without impairing mechanical characteristics, in particular, low temperature rise Abrasion resistance and the like can also be improved. If the blending amount is less than 3% by mass, these effects cannot be expected, and improvement in slip characteristics such as self-lubricating property and wear resistance is not recognized remarkably. On the other hand, if it exceeds 20% by mass, the load applied to the cylinder of the melt molding machine or the like at the time of granulation or injection molding due to these melt viscosities becomes large, the moldability deteriorates, and stable granulation, injection moldability and Dimensional accuracy cannot be expected, and mechanical properties are degraded.

  If necessary, the resin composition in the present invention may contain additives other than the fibrous reinforcing material as long as the cage function and the injection moldability are not impaired. As other additives, for example, a solid lubricant, an inorganic filler, an antioxidant, an antistatic agent, a release material, and the like can be blended.

  Each material constituting the resin composition is mixed with a Henschel mixer, a ball mixer, a ribbon blender, or the like, if necessary, and then melt-kneaded with a melt extruder such as a twin-screw kneading extruder to form pellets for molding. Can be obtained. The filling material may be fed by side feed when melt-kneading with a twin screw extruder or the like. A cage is molded by injection molding using the 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 above polyamide resin, and the mold temperature is maintained below the glass transition temperature of the polyamide resin.

  As described above, the resin composition used as the resin material for the rolling bearing cage of the present invention is obtained by blending a predetermined amount of fibrous reinforcing material (glass fiber or carbon fiber) and fluororesin with a predetermined polyamide resin. High melting point and glass transition temperature, excellent heat resistance, oil resistance, chemical resistance, dimensional stability, toughness, slidability and high mechanical properties. For this reason, the rolling bearing cage of the present invention can be used for long periods of time in harsh environmental conditions such as high-speed rotation areas (high-temperature atmosphere, contact with oil or chemicals, high-speed rotation conditions, high-load conditions, humid environments, etc.). The cage can withstand use.

  Moreover, since the said resin composition has small water absorption, it can suppress the dimensional change and physical property fall accompanying swelling and expansion | swelling by water absorption and moisture absorption. The rolling bearing cage of the present invention is excellent in dimensional stability and can be provided at a low cost as a cage for applications requiring accuracy.

In the polyamide resin used in the present invention, plant-derived materials may be used as the dicarboxylic acid component or the diamine component. For example, 1,10-decanediamine using castor oil as a starting material can be used. By adopting a biomass-derived raw material such as a plant, the substantial discharge amount of carbon dioxide accompanying incineration disposal of a resin cage can be reduced as compared with a case where no biomass-derived raw material is used. Here, whether or not it is a plant plastic using a biomass-derived raw material can be determined by measuring the concentration of ¹⁴ C, which is a radioisotope, with respect to the carbon constituting the resin. ^Since the half-life of ¹⁴ C is 5730 years, carbon derived from fossil resources, which is supposed to be produced after more than 10 million years, does not contain ¹⁴ C at all. From this, if ¹⁴ C is contained in the resin, it can be determined that at least a raw material derived from biomass is used.

  A rolling bearing cage and a rolling bearing according to the present invention will be described with reference to FIGS. FIG. 1 is an axial sectional view of an angular 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 (a machined die) in the rolling bearing of FIG. . As shown in FIG. 1, the angular ball bearing 1 includes an inner ring 2, an outer ring 3, a plurality of rolling elements 4 interposed between the inner ring 2 and the outer ring 3, and the rolling elements 4 held at regular intervals in the circumferential direction. The cage 5 is provided. The cage 5 is the above-described rolling bearing cage of the present invention. The inner ring 2 and the outer ring 3 and the rolling element 4 are in contact with each other at a predetermined angle θ (contact angle) with respect to the radial center line, so that a radial load and an axial load in one direction can be applied. If necessary, a lubricant such as grease is sealed around the rolling elements 4 for lubrication.

  An angular ball bearing 1 as shown in FIG. 1 is used for high-speed rotation and the like. In the present invention, the cage 5 is an injection-molded body of a resin composition based on the above-described polyamide resin having a high glass transition temperature and excellent rigidity. Deformation of the cage can be suppressed. Moreover, since the above-mentioned polyamide resin is excellent in self-lubricating properties and low friction characteristics, the amount of heat generated by friction between the rolling element 4 or the outer ring 3 and the cage 5 can be reduced, temperature rise is suppressed, and seizure occurs. Does not occur. For this reason, the bearing can be operated for a long time even under high temperature and high speed rotation conditions.

  As shown in FIG. 2 (a), the cage 5 is provided with a plurality of pockets 6 for holding balls as rolling elements at regular intervals in the circumferential direction in an annular cage body 5a. The planar shape of the pocket 6 is a flat circular shape, but may be a perfect circle. Here, the flat circular shape means a pocket that approximates the radius of the ball on both sides with a gap that matches the amount of pocket gap (difference between pocket inner diameter and ball diameter) required for a perfect circle shape. A shape that is a flat circle composed of the radius of the surface. With such a shape, the load on the cage can be reduced by increasing the pocket clearance in the circumferential direction of the rotating shaft and absorbing the advance and delay of the ball.

  The cage 5 is a machined die cage, and is obtained by molding a shaped material by injection molding using the resin composition described above and then machining 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 is merged during molding. The weld portion 7 is a portion that easily breaks due to stress concentration in the cage ring. In the cage of the present invention, a molded body obtained by injection molding a resin composition comprising the above-described polyamide resin as a base resin and a predetermined amount of fibrous reinforcing material (glass fiber or carbon fiber) blended therein. Therefore, the weld portion 7 is excellent in tensile strength and can be prevented from cracking at the time of use at high speed rotation. Specifically, as shown in the examples described later, the tensile strength is higher than when only the base resin is changed to another polyamide resin.

  In FIG. 1 and FIG. 2, an angular ball bearing has been described as an example of the rolling bearing of the present invention. However, 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. It can also be applied to bearings and needle roller bearings.

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

  When the crown type cage shown in FIG. 3 is injection-molded, the bent tip 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, so that the inner diameter mold for forming the pocket is released by elastically expanding the diameter of the pocket opening to the inner diameter of the pocket. . In the cage of the present invention, since the above-mentioned resin composition is used as a cage material, it prevents cracking and whitening of the tip of the holding claw when forcibly removing the above while maintaining high rigidity during use. obtain. In particular, for the fibrous reinforcing material contained in the resin composition, the blending amount is 20 to 35% by mass with respect to the entire resin composition when glass fiber is used, and the entire resin composition when carbon fiber is used. On the other hand, it becomes easy to prevent this by setting it as 15-30 mass%. Moreover, the heat_generation | fever at the time of use can be suppressed by mix | blending 3-20 mass% of fluororesins by the improvement of slidability further.

  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 the examples and comparative examples are collectively shown below.
(1) Resin material Polyamide resin A: Resin using terephthalic acid and 1,10-decanediamine as main materials (XecoT XN500 manufactured by Unitika)
Polyamide 66 resin: Amilan CM3001 manufactured by Toray Industries, Inc.
Polyamide 46 resin: Stanyl TW300 manufactured by DSM
Polyamide 9T resin: Genesta N1000 manufactured by Kuraray
(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: Toho Tenax HTA-C6 (average fiber diameter 7 μm, average fiber length 6 mm)
(3) Fluororesin PTFE: Kitamura Co., Ltd .: KTL610 (average particle size 12 μm)

Examples 1-5, Comparative Examples 1-7
Using the resin compositions in which these raw materials were blended in the proportions shown in Table 1, angular ball bearing cages of Examples and Comparative Examples were produced, and various tests were performed. A twin screw extruder was used for the production of the composition. Use a mixer in advance to mix the polyamide resin and fluororesin, put them into a twin screw extruder, and supply glass fiber and carbon fiber using a fixed side feeder to prevent breakage and extrude. Grained. The obtained pellets for molding were molded by an in-line screw injection molding machine to obtain a desired cage shape (outer diameter 93 mm, inner diameter 88 mm, width 13 mm). In addition, the shape of the cage was the machined type cage shown in FIG. After molding, humidity control was carried out in an atmosphere of 80 ° C. and 95% relative humidity, and each test was carried out on the water absorbed. The water absorption rate was measured from the mass of the obtained cage before and after humidity control according to the calculation formula shown below. The results are shown in Table 1.

[Calculation formula of water absorption rate]

Water absorption rate (mass%) = (mass after humidity control−mass before humidity control) × 100 / mass before humidity control

[Cage tensile test]
In order to confirm the breaking strength (tensile strength of the weld portion) in the cage of the present invention, a cage tensile test was performed using the produced cage. In the cage tensile test, a test cage 14 is set on an annular tension jig 13 shown in FIG. 4 so that the weld portion is in a horizontal position, and a tensile tester manufactured by Shimadzu Corporation (autograph) AG50KNX) at a tensile speed of 10 mm / min. The results are shown in Table 1 as cage breaking strength (N).

[Bearing temperature test]
A bearing test was performed in which angular ball bearings were used and the rotational speed was sequentially increased to a dm · n value of 80 × 10 ⁴ . A comparative test was carried out using angular ball bearings in which the cages of Examples and Comparative Examples were incorporated, grease as a lubricant was sealed, and non-contact type seals were provided on both sides and sealed. In the test, the outer ring temperature was measured, and in view of accuracy and durability, the temperature of the outer ring was determined to be 30 ° C. as a reference, and less than 30 ° C. was accepted, and the temperature increased by 30 ° C. or more was rejected. The results are shown in Table 1.

With respect to the cage tensile test, a high strength is required for the breaking strength of the cage (the tensile strength of the weld portion) from the use conditions where the dm · n value is 80 × 10 ⁴ or more. As shown in Table 1, the cage made of the example of the present invention showed a good strength of 2000 N or more. On the other hand, Comparative Examples 1-7 were all 2000 N or less.

Regarding the bearing temperature test, as shown in Table 1, in Comparative Examples 1 to 4, the outer ring temperature suddenly increased from around dm · n value exceeding 70 × 10 ⁴ to 30 ° C. or more. In contrast, in the embodiment according to the present invention, surge of the outer ring temperature even dm · n value is a 80 × 10 ⁴ was not observed, had kept 30 ° C. or less. In Comparative Examples 5 to 7, the outer ring temperature did not increase rapidly, but the range of the resin composition was not appropriate, so that the breaking strength of the cage was inferior as described above.

The rolling bearing cage of the present invention does not cause seizure or breakage even under high temperature and high speed conditions, and can be used as a cage for various rolling bearings used in automobiles, motors, machine tools, and the like. In particular, it is suitable as a bearing retainer used at high speed rotation such that the dm · n value is 80 × 10 ⁴ or more.

1 Angular contact ball bearings (rolling bearings)
DESCRIPTION OF SYMBOLS 2 Inner ring 3 Outer ring 4 Rolling element 5 Cage 6 Pocket 7 Weld part 8 Cage 9 Cage body 10 Holding claw 11 Pocket 12 Flat part 13 Tension jig 14 Test cage

Claims (4)

A rolling bearing retainer that is an injection-molded body of a resin composition,
The resin composition is a composition in which a polyamide resin composed of a dicarboxylic acid component and a diamine component is used as a base resin, and a fibrous reinforcing material and a fluororesin are blended therein.
The dicarboxylic acid component is based on terephthalic acid, the diamine component is based on 1,10-decanediamine,
The fibrous reinforcing material is glass fiber or carbon fiber,
The blending ratio with respect to the whole resin composition is 15 to 40% by mass for the glass fiber, 10 to 30% by mass for the carbon fiber, and 3 to 20% by mass for the fluororesin. Cage.   The rolling bearing retainer according to claim 1, wherein the polyamide resin contains carbon 14 which is a radioisotope. A rolling bearing comprising an inner ring and an outer ring, a plurality of rolling elements interposed between the inner and outer rings, and a cage for holding the rolling elements,
The rolling bearing according to claim 1, wherein the cage is a rolling bearing cage according to claim 1. The rolling bearing according to claim 3, wherein the rolling bearing is a bearing used at high speed rotation with a dm · n value of 80 × 10 ⁴ or more.

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