JP2008169970A - Tapered roller bearing for automobile drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tapered roller bearing for automobile drive provided with a retainer excellent in mechanical strength, dimension stability, slide property and fatigue-resistance while attaining light weight replacing a retainer formed of iron. <P>SOLUTION: In the tapered roller bearing for automobile drive provided with at least an inner ring, an outer ring, the retainer and the roller, the retainer comprises a synthetic resin composition containing a glass fiber having an irregular shape cross section in a ratio of 10-40 mass%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a tapered roller bearing used in an automobile drive system such as an automatic transmission.

  Tapered roller bearings are used in automatic transmissions, specifically differentials, counter drive gears, and the like. Since these tapered roller bearings are exposed to chemicals such as ATF (automatic fluid) and become high temperature and at the same time require high reliability, iron press cages have been used so far (for example, patents) References 1-4).

  However, in recent years, there is a high demand for weight reduction and torque reduction, and even with a review of the structure and the like, the iron cage can no longer handle it.

Japanese Patent No. 3359501 JP 2001-12461 A JP 2005-76674 A JP 2005-76675 A

  The present invention has been made in view of such a situation, and instead of the conventional iron cage, while reducing the weight, the mechanical strength, dimensional stability, slidability, fatigue resistance, etc. An object of the present invention is to provide a tapered roller bearing for driving an automobile having an excellent cage.

  In order to achieve the above object, the present invention provides a tapered roller bearing for driving an automobile comprising at least an inner ring, an outer ring, a cage, and a roller, wherein the cage has a ratio of 10 to 40% by mass of glass fiber having an irregular cross section. A tapered roller bearing for driving an automobile is provided.

  In the tapered roller bearing for driving an automobile of the present invention, since the cage is made of resin, the weight can be significantly reduced as compared with an iron cage. Furthermore, since the cage contains glass fibers having a deformed cross section as a reinforcing material, it has excellent mechanical strength, fatigue resistance, etc., and there is no occurrence of sink marks during molding due to a decrease in the anisotropy of the glass fibers. Since the dimensional accuracy is also high, the conical bearing for automobiles of the present invention has excellent durability and high reliability.

  Hereinafter, embodiments of the present invention will be described in detail.

  In the present invention, the structure of the tapered roller bearing for driving an automobile is not limited, and for example, the tapered roller bearing shown in FIG. 1 can be exemplified. The illustrated tapered roller bearing includes an inner ring 2 having an inner ring raceway 1 on an outer peripheral surface, an outer ring 4 having an outer ring raceway 3 on an inner peripheral surface, a plurality of tapered rollers 5, and the tapered rollers 5 divided equally. And a cage 6 for disposing. FIG. 2 shows a perspective view of the cage 6.

  In this invention, what shape | molded the synthetic resin composition which mix | blended the synthetic fiber with the glass fiber which has a deformed cross section as the said holder | retainer 6 is used. Although there is no restriction | limiting in a synthetic resin, when heat resistance, fatigue resistance, etc. are considered, polyphenylene sulfide, aromatic polyamide, polyamide 46, polyamide 66, etc. are preferable. Among these, polyphenylene sulfide is most preferable because it can be used at a high temperature of 150 to 180 ° C. and has excellent chemical resistance such as ATF. However, since polyphenylene sulfide is brittle and may be damaged by impact or the like, a toughening agent composed of an ethylene-based copolymer having a reactive functional group such as glycidyl methacrylate is blended at a ratio of 5 to 20% by mass. It is preferable.

  Aromatic polyamide is preferred next to polyphenylene sulfide because it has a high melting point and high strength, can be used at a high temperature of 130 to 150 ° C., and has excellent chemical resistance. However, since it is brittle like polyphenylene sulfide, it is preferable to add a toughening agent in the same manner.

  Polyamide 46 is also preferable because it has a heat resistance of 120 to 140 ° C., the impact strength and fatigue resistance of the resin itself is high, and the reliability is improved against breakage of the synthetic resin cage.

  Polyamide 66 has a heat resistance of 100 to 120 ° C., but has a good balance of impact strength, fatigue resistance and the like, and has a low material cost. Therefore, it is most suitable when used in a low temperature environment.

  The molecular weight of these synthetic resins is preferably set to a molecular weight that allows injection molding in a state of containing glass fibers having an irregular cross section in consideration of productivity. Specifically, the number average molecular weight is preferably 13,000 to 30000, and further considering the mechanical strength such as impact strength, the number average molecular weight is more preferably 18000 to 26000. When the number average molecular weight is less than 13,000, the molecular weight is too low, the mechanical strength is low, and the practicality is low. On the other hand, when the number average molecular weight exceeds 30000, the melt viscosity in a state where a prescribed amount of glass fiber having a modified cross section is contained is too high, and it becomes difficult to manufacture by injection molding with high accuracy.

  A glass fiber having an irregular cross section is a glass fiber having a non-circular cross section. Examples of the cross-sectional shape include eyebrows, ellipses, and ellipses. Preferably, it is a glass fiber having a deformed ratio (ratio of the major axis part to the minor axis part) of 1.5 to 5, and more preferably a glass fiber of 2 to 4. If the profile ratio is less than 1.5, the effect of improving the mechanical strength is small, and if the profile ratio exceeds 5, it is too flat and it is difficult to produce stably. Moreover, it is preferable that a short diameter part is 5-12 micrometers. If the short diameter part is less than 5 μm, it is too thin and breaks or breaks during production. Therefore, it is difficult to maintain a stable quality at low cost, and the practicality is low. On the other hand, when the minor axis exceeds 12 μm, the fiber is too thick in consideration of the deformed ratio, resulting in poor dispersibility in the resin, and unevenness in strength may occur in the resin part.

  Content of the glass fiber which has an irregular cross section is 10-40 mass% of the resin composition whole quantity, Preferably it is 25-30 mass%. When the content is less than 10% by mass, the reinforcing effect is small. When the content exceeds 40% by mass, fluidity suitable for injection molding cannot be obtained, and toughness is reduced and forced removal from the mold at the time of molding or There is a risk of damage when the roller is inserted, which is not preferable.

  The glass fiber having a modified cross section used in the present invention is less likely to break than a conventional glass fiber having a circular cross section, and is dispersed in the resin in a longer state than the glass fiber having a circular cross section when kneaded with a resin and injection molded. . Therefore, when compared with the same content, the effect of increasing the mechanical strength is superior to that of glass fibers having a circular cross section. Further, since the glass fiber having an irregular cross section is oriented so as to form a plane parallel to the cage surface at the time of molding, it can receive a load on the plane and has excellent load resistance. Furthermore, a slight reinforcing effect appears in the radial direction, the mechanical strength is further increased, and the difference in dimensional change is reduced, so that sink marks are less likely to occur.

  In addition, the glass fiber having an irregular cross section is a silane coupling agent having an epoxy group, an amino group or the like at one end, or an epoxy type, urethane type, acrylic type or the like in consideration of adhesiveness with the above-described resin. It is preferable to use a surface-treated product. Silane coupling agents and sizing agents are selected according to the type of resin. For example, silane coupling agents having an epoxy group, amino group, or the like have a reinforcing effect because the epoxy group or amino group acts on the amide bond of the resin. To improve.

  The glass fiber having an irregular cross section preferably has a fiber length of 300 to 900 μm, more preferably 350 to 600 μm, in the obtained resin cage. If the fiber length is less than 300 μm, the reinforcing effect and the dimensional stability effect are small, which is not preferable. On the other hand, it is difficult to maintain a long fiber state exceeding 900 μm in the process of kneading with resin and injection molding, and the upper limit of the fiber length is a value set from the manufacturing process. In order to obtain such a fiber length, kneading conditions and molding conditions may be adjusted.

  A part of the glass fiber having an irregular cross section may be replaced with another fibrous reinforcing material such as carbon fiber or a whisker-like reinforcing material such as potassium titanate whisker.

  Furthermore, a colorant or the like may be added to the resin composition. When a resin having insufficient heat resistance is used, iodide-based heat stabilization is performed to prevent deterioration due to heat during molding and use. It is preferable to add an agent or an amine-based antioxidant alone or in combination. In order to improve the impact resistance, a rubber-like substance such as ethylene propylene non-conjugated diene rubber (EPDM) may be blended.

  In addition, from the viewpoint of productivity, injection molding is preferred as a method for producing a resin cage using the above-mentioned resin, glass fiber having a modified cross section and other blends.

  Examples The present invention will be further described below with reference to examples and comparative examples, but the present invention is not limited thereby.

(Examples 1 to 3, Comparative Example 1)
As shown in Table 1, a resin composition was prepared using a synthetic resin and glass fiber. In addition, PA66 used for the resin is “UBE nylon 2020U (containing copper heat stabilizer)” manufactured by Ube Industries, Ltd., and PA46 is “Stanyl TW341 (containing copper heat stabilizer)” manufactured by DJEP, L-PPS is “Fortron 0220A9” manufactured by Polyplastics Co., Ltd. The toughening agent is “Bond First E (ethylene-glycidyl methacrylate (GMA) copolymer, GMA content 12%)” manufactured by Sumitomo Chemical Co., Ltd. On the other hand, the glass fibers are all treated with an amino-based silane coupling agent. In the examples, glass fibers with an oblong cross section (“CSG3PA-820” manufactured by Nitto Boseki Co., Ltd., deformed ratio 4, short diameter 7 μm, urethane) System sizing agent treatment) In Comparative Example 1, circular cross-section glass fibers having an average diameter of about 13 μm were used.

  And each test piece for tensile tests and warpage amount measurement (ISO D-1 standard) was produced from the resin composition, and the tensile strength and warpage amount were measured. In addition, a resin composition is injection molded to produce a cage of HR30305C (d25, D62, T18.25, B17, C14) that is approximately the same size as a tapered roller bearing for driving an automobile used in AT, MT, etc. The appearance was observed. The results are shown in Table 1.

  As shown in Table 1, the mechanical strength is improved by blending glass fibers having an irregular cross section as compared with the case of blending glass fibers having a circular cross section. In addition, the amount of warpage is small, and even a narrow, small-diameter cage is free from sink marks on the surface, can be molded with high accuracy, can be injection molded, and is excellent in productivity.

It is a half sectional view of a tapered roller bearing. It is a perspective view which shows an example of the retainer for tapered roller bearings.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner ring track 2 Inner ring 3 Outer ring track 4 Outer ring 5 Tapered roller 6 Cage

Claims (1)

In a tapered roller bearing for driving an automobile comprising at least an inner ring, an outer ring, a cage and a roller,
A tapered roller bearing for driving an automobile, wherein the cage is made of a synthetic resin composition containing glass fibers having an irregular cross section at a ratio of 10 to 40% by mass.

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