JP2009133402A - Universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a universal joint having a longer service life and smaller energy loss for reducing sliding resistance between a cage and each race and developing the effects over a long period in use under severe conditions. <P>SOLUTION: The universal joint 1 includes the inner race 3 and the outer race 2 having ball rolling grooves 4, 5, respectively, a plurality of balls 6 fitted into the ball rolling grooves 4, 5, and the annular cage 7 having pocket portions for holding the balls 6. On the inner peripheral of the cage 7 having sliding contact with the inner race 3, the outer peripheral face of the cage 7 having sliding contact with the outer race 2, and the inner peripheral faces of the pocket portions of the cage 7 having sliding contact with the balls 6, coatings are formed each using such a resin composition that a synthetic resin contains fullerene, and at least one disulfide selected from molybdenum disulfide and tungsten disulfide. The whole composition contains the 0.1-10 volume% fullerene, and the 0.5-20 volume% disulfide. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a universal joint (joint) having sufficient durability.

  As a kind of universal joint (joint) used in vehicles, etc., it has the function of connecting the driving shaft and driven shaft intersecting with each other to transmit the rotational force, and at any joint angle between the driving shaft and the driven shaft. There is known a constant velocity joint that transmits rotation at a constant angular velocity without any difference in rotational angular velocity between the two. A typical structure of the constant velocity joint includes an inner race and an outer race each having a ball rolling groove, a plurality of balls fitted in the ball rolling groove, an outer peripheral surface of the inner race, and an outer race. It is configured to have an annular cage that is formed between the inner peripheral surface of the race and is formed with a pocket portion through which the ball is held to fit into the rolling groove of the inner race and outer race. Torque from the drive shaft side is transmitted to the driven shaft side through a plurality of balls inserted. Here, the cage constantly maintains the plurality of balls on a plane that bisects the complementary angle of the angle formed by the drive shaft and the driven shaft, so that power can be transmitted at a constant speed. Yes.

  In such a constant velocity joint, as described above, a plurality of balls roll in the ball rolling grooves of the inner race and the outer race, thereby enabling transmission of power at a constant velocity. The movement between the race and the ball at this time is a so-called rolling / sliding state under a low speed and high surface pressure condition. Therefore, an oil film is not easily formed on the rolling / sliding surface, and the ball does not roll, and if sliding is the main cause of heat generation due to friction, the inner race, the outer race and the ball are likely to be peeled off (flaking). . As described above, the cage is provided to always maintain the ball on a plane that bisects the complementary angle of the angle formed by the drive shaft and the driven shaft. Always slides with the outer peripheral surface of the inner race, and the outer peripheral surface of the cage slides with the inner peripheral surface of the outer race. If the sliding resistance of this portion is large, not only heat will be generated, but also the interference force with the ball will increase, preventing smooth rolling of the ball. That is, in the motion state of the ball and the race, the slip rate is increased, and as a result, the inner race, the outer race and the ball are promoted to be separated.

  Further, the temperature rise due to heat generation causes a decrease in the viscosity of the lubricating oil, which adversely affects oil film formation. Furthermore, since the temperature rise promotes the oxidative deterioration of the lubricating oil, it is not preferable from the viewpoint of the lubrication life. In addition to this, with the recent reduction in size and weight, higher output, and higher performance of vehicles, the use environment of constant velocity joints tends to become increasingly severe. Further, it is also required to reduce the frictional resistance inside the constant velocity joint and reduce the energy loss in order to improve fuel efficiency. The development of a constant velocity joint that can withstand use under such a severe environment is expected.

  In order to solve such a problem, a constant velocity joint in which a manganese phosphate treatment is performed and a specific grease is enclosed has been proposed (see Patent Document 1). In addition, a constant velocity joint has been proposed in which a solid lubricant film is formed on the surface of both the outer race and the inner race of the constant velocity joint, or one of the ball rolling groove surfaces after a predetermined surface roughness is obtained by shot blasting. (See Patent Document 2). Furthermore, a constant velocity joint has been proposed in which a coating containing a solid lubricant is provided on the surface of the cage (see Patent Document 3).

In Patent Literature 1 and Patent Literature 2, a coating treatment is performed after the surface of both the outer race and the inner race of the constant velocity joint or one of the ball rolling grooves is made a predetermined surface roughness by shot blasting. In this case, since the metal contact is unlikely to occur even when the oil film is difficult to form on the rolling surface of the ball, the rolling fatigue life is extended. However, since the ball rolling inhibition by the cage is not considered, it does not lead to a fundamental solution.
Patent Document 3 proposes a film in which a thermosetting resin is used as a binder and a solid lubricant is fixed as a solid lubricant film formed on the cage, or plating in which a solid lubricant is dispersed. However, the wear resistance is not sufficient under the high contact pressure condition of the constant velocity joint, and the coating peels off when subjected to repeated stress, and it has sufficient performance in terms of maintaining performance over a long period of time. That is not the case. In particular, the coating film has a problem of insufficient wear resistance under severe conditions such as sliding with a counterpart material having a relatively large surface roughness such as an outer race or inner race of a constant velocity joint.
JP 2000-46061 A JP 2000-145804 A JP 2002-372066 A

  The present invention has been made in order to cope with such problems, and reduces the sliding resistance between the cage and the race, etc., and even if used under harsh conditions, the effect is demonstrated over a long period of time, resulting in a long service life. Then, it aims at providing the universal joint with small energy loss.

  The universal joint of the present invention includes an inner race and an outer race each having a ball rolling groove, a plurality of balls fitted in the ball rolling groove, an outer circumferential surface of the inner race, and an inner circumference of the outer race. A universal joint having an annular cage interposed between the surfaces and formed with a pocket for holding the ball, wherein at least the inner race, the outer race, and the cage surface on the cage surface A film made of a resin composition containing fullerene and at least one disulfide selected from molybdenum disulfide and tungsten disulfide is formed on a portion that comes into contact with the ball, and is formed on the entire resin composition. On the other hand, the fullerene is contained in an amount of 0.1 to 10% by volume and the disulfide is contained in an amount of 0.5 to 20% by volume.

The coating is formed on an inner peripheral surface that is in sliding contact with the inner race of the cage and an outer peripheral surface that is in sliding contact with the outer race of the cage.
Further, the coating is formed on an inner peripheral surface of a pocket portion that is in sliding contact with the ball of the cage.

The synthetic resin is a polyimide resin. In particular, the polyimide resin is a polyamideimide resin having an elongation of 60% to 120%.
Further, the film thickness of the coating is 1 μm to 50 μm.

The surface of the cage has a surface roughness Ra of 0.3 μm to 2.0 μm before the coating is formed.
The outer race and the inner race in contact with the cage have a surface roughness Ra of 1.0 μm or less.

  The coating is formed on a portion of the outer race and the inner race that contacts at least the cage.

  The universal joint is a fixed type constant velocity universal joint used on a wheel side of a drive train of an automobile or a sliding type constant velocity universal joint used on a differential side of a drive train of an automobile.

  The universal joint of the present invention has a predetermined coating excellent in wear resistance and peeling resistance on the inner peripheral surface that is in sliding contact with the inner race of the cage, the outer peripheral surface that is in sliding contact with the outer race, the inner peripheral surface of the pocket portion that is in sliding contact with the ball, and the like. Therefore, the compatibility with the lubricating oil is excellent, the friction is reduced even with a small amount of adhering oil, and the sliding resistance between the cage and the race can be reduced. In addition, since there is no seizure, sliding heat generation during operation is small. Further, since the interference force with the ball is reduced, the occurrence of peeling of the inner race and outer race rolling grooves and the ball surface is also suppressed. Furthermore, the energy loss in the universal joint is reduced, and it is possible to contribute to the reduction in fuel consumption of the automobile.

  In the present invention, since a predetermined amount of synthetic resin, fullerene, and disulfide is blended in the resin composition, the film obtained from this resin composition is uniform in fine particle shape fullerene and disulfide powder. It is blended. The synergistic effect of these additives improves the wear resistance and peel resistance of the coating, and at the same time decreases the friction coefficient. Moreover, even if the said film contacts the lubricating oil and grease containing sulfur type additives, such as an extreme pressure agent, peeling of a film or elution of the film | membrane component to lubricating oil etc. can be suppressed. As a result, the above-described excellent sliding performance can be maintained over a long period even under high surface pressure conditions of the constant velocity joint.

The universal joint of the present invention will be described with reference to FIGS. FIG. 1 is a view showing a first embodiment of the present invention, and illustrates a ball fixed joint as a fixed type constant velocity joint. FIG. 2 shows a second embodiment of the present invention, and illustrates a double offset joint as a sliding type constant velocity joint.
As shown in FIG. 1, the ball fixed joint 1 is formed with six ball rolling grooves 4 and 5 in the axial direction at equal angles on the inner surface of the outer race 2 and the outer surface of the spherical inner race 3. A ball 6 incorporated between the grooves 4 and 5 is supported by a cage 7, the outer periphery of the cage 7 is a spherical surface 7 a, and the inner periphery is a spherical surface 7 b that fits the outer periphery of the inner race 3. A predetermined film is formed on the outer peripheral surface of the ball fixed joint 1 slidably contacting the outer race 2 of the cage 7, the inner peripheral surface of the cage 7 slidably contacting the inner race 3, and the inner peripheral surface of the pocket portion slidably contacting the ball 6 of the cage 7. It is what is done.
Further, the outer periphery of the outer race 2 and the outer periphery of the shaft 8 are covered with a boot 9, and the outer race 2, the spherical inner race 3, the ball rolling grooves 4 and 5, the ball 6, the cage 7, and the shaft 8. Grease 10 is enclosed in a space surrounded by.

  The film is a film obtained from a resin composition in which a synthetic resin contains fullerene and at least one disulfide selected from molybdenum disulfide and tungsten disulfide. This film is formed on the surface of the cage 7 at least at a portion in contact with the inner race 3, the outer race 2, and the ball 6 in order to reduce the sliding resistance between the cage and the race and between the cage and the ball. It only has to be done. Moreover, it is preferable to form this film also on the contact surfaces of the outer race 2 and the inner race 3 with the cage 7.

As shown in FIG. 2, the double offset joint 11 is formed with six ball rolling grooves 14 and 15 in the axial direction at equal angles on the inner surface of the outer race 12 and the outer surface of the spherical inner race 13, and the ball rolling. A ball 16 incorporated between the grooves 14 and 15 is supported by a cage 17, the outer periphery of the cage 17 is a spherical surface 17a, and the inner periphery is a spherical surface 17b that fits the outer periphery of the inner race 13, and the center of each spherical surface 17a and 17b The positions of (a) and (b) are shifted in the axial direction on the axis of the outer race 12. In the case of FIG. 1 above, the outer peripheral surface of the double offset joint 11 slidably contacting the outer race 12 of the cage 17, the inner peripheral surface of the cage 17 slidably contacting the inner race 13, and the inner peripheral surface of the pocket portion slidably contacting the ball 16 of the cage 17. The same film is formed.
Further, the outer periphery of the outer race 12 and the outer periphery of the shaft 18 are covered with a boot 19, and the outer race 12, the spherical inner race 13, the ball rolling grooves 14 and 15, the ball 16, the cage 17, and the shaft 18. Grease 20 is enclosed in a space surrounded by.

Examples of using the universal joint of the present invention for a fixed type constant velocity joint include an undercut free joint in addition to the above-mentioned ball fixed joint. Such ball fixed joints and undercut free joints may have 6 or 8 balls. This fixed type constant velocity joint can be applied as, for example, a constant velocity joint used on the wheel side of a drive train of an automobile.
Examples of use for sliding constant velocity joints include double offset joints, tripod joints, cross groove joints, and the like. The number of balls of the double offset joint may be 6 or 8. This sliding constant velocity joint can be used as, for example, a constant velocity joint used on the differential side of an automobile drive train.
Moreover, a cross joint etc. are mentioned as an inconstant velocity joint.

  The synthetic resin that can be used in the present invention is not particularly limited as long as it is a material that has oil resistance, has high film strength when formed into a film, and is excellent in wear resistance. Examples of such resins include epoxy resins, phenol resins, polycarbodiimide resins, furan resins, bismaleimide triazine resins, unsaturated polyester resins, silicone resins, polyamino bismaleimide resins, aromatic polyimide resins and other thermosetting resins, polyolefins Resin, polyacetal resin, polyamide resin, polyphenylene ether resin, polyphenylene sulfide resin, polysulfone resin, polyether sulfone resin, polyetherimide resin, thermoplastic polyimide resin, aromatic polyamideimide resin, polybenzimidazole resin, polyether ketone resin And thermoplastic resins such as polyether nitrile resin, fluororesin, and aromatic polyester resin. Among these, preferred are aromatic polyamideimide resin, aromatic polyimide resin, epochine resin, phenol resin, polyphenylene sulfide resin and the like. These synthetic resins can be blended with various fillers in the form of fibers and particles as necessary.

  In the present invention, a particularly preferable synthetic resin is a polyimide resin excellent in film forming ability. Examples of the polyimide resin include a polyimide resin having an imide bond in the molecule and a polyamideimide resin having an imide bond and an amide bond in the molecule. By using the polyimide-based resin, the coating is excellent in adhesion to the cage surface and heat resistance.

Of the polyimide resins, aromatic polyimide resins are preferred. The aromatic polyimide resin is a resin having a repeating unit represented by Chemical Formula 1, and a polyamic acid that is a precursor of a resin having a repeating unit represented by Chemical Formula 1 can also be used. R ₁ is the residue of an aromatic tetracarboxylic acid or derivative thereof, and R ₂ is the residue of an aromatic diamine or derivative thereof. Examples of such R ₁ or R ₂ include a phenyl group, a naphthyl group, a diphenyl group, and an aromatic group in which these are connected by a connecting group such as a methylene group, an ether group, a carbonyl group, or a sulfone group.

  Examples of aromatic tetracarboxylic acids or derivatives thereof include pyromellitic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetra Carboxylic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, bis (2,3-dicarboxyphenyl) Examples thereof include methanoic dianhydride, and these are used alone or in combination.

  Examples of aromatic diamines or derivatives thereof include 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl sulfone, 4,4′-diaminodiphenylmethane, metaphenylene diamine, paraphenylene diamine, 4,4 Examples include diamines or diisocyanates such as' -bis (3-aminophenoxy) biphenyl ether.

Examples of the aromatic polyimide resin obtained by a combination of the aromatic tetracarboxylic acid or derivative thereof and the aromatic diamine or derivative thereof include those having a repeating unit shown in Table 1. These are resins having no heteroatoms in R ₁ and R ₂ .

In the aromatic polyimide resin in Table 1, polyimide C and polyimide D having a high ratio of aromatic rings in the molecule are preferable, and polyimide D is particularly suitable for the present invention. As a commercial item of an aromatic polyimide resin varnish, Ube Industries make: U varnish is mentioned, for example.

The polyamide-imide resin that can be used in the present invention is a resin having an amide bond and an imide bond in the polymer main chain, and can be obtained by reacting a polycarboxylic acid or a derivative thereof with a diamine or a derivative thereof.
Examples of polycarboxylic acids include dicarboxylic acids, tricarboxylic acids, and tetracarboxylic acids. Polyamideimide resins include (1) combinations of dicarboxylic acids and tricarboxylic acids and diamines, and (2) dicarboxylic acids and tetracarboxylic acids and diamines. (3) a combination of a tricarboxylic acid and a diamine, and (4) a combination of a tricarboxylic acid and a tetracarboxylic acid and a diamine. Each of the polycarboxylic acid and the diamine may be a derivative. Examples of polycarboxylic acid derivatives include acid anhydrides and acid chlorides, and examples of diamine derivatives include diisocyanates. Diisocyanate may be used that has been stabilized with a blocking agent necessary to prevent the isocyanate group from changing over time. Examples of the blocking agent include alcohol, phenol and oxime.
Moreover, an aromatic and an aliphatic compound can be used for polycarboxylic acid and diamine, respectively. The polyamideimide resin that can be used in the present invention is preferably excellent in elongation, and it is preferable to use an aliphatic compound in combination with an aromatic compound.
Further, it can be modified with an epoxy compound.

Examples of tricarboxylic acid or derivatives thereof include trimellitic anhydride, 2,2 ′, 3-biphenyltricarboxylic anhydride, 3,3 ′, 4-biphenyltricarboxylic anhydride, 3,3 ′, 4-benzophenone Examples include tricarboxylic acid anhydride, 1,2,5-naphthalene tricarboxylic acid anhydride, 2,3-dicarboxyphenylmethylbenzoic acid anhydride, and the like. These may be used alone or in combination.
Among these, trimellitic anhydride is preferable because it is mass-produced and is easy to use industrially.

  Examples of tetracarboxylic acid or derivatives thereof include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic acid Dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,3,5,6-pyridinetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride 3,4,9,10-perylenetetracarboxylic dianhydride, 4,4'-sulfonyldiphthalic dianhydride, m-terphenyl-3,3 ', 4,4'-tetracarboxylic acid Dianhydride, 4,4'-oxydiphthalic dianhydride, 1,1,1,3,3,3-hexafluoro-2,2-bis (2,3- or 3,4-dicarboxyphenyl) propane Dianhydride, 2,2-bis (2,3- or 3,4-dicarboxypheny ) Propane dianhydride, 2,2-bis [4- (2,3- or 3,4-dicarboxyphenoxy) phenyl] propane dianhydride, 1,1,1,3,3,3-hexafluoro- 2,2-bis [4- (2,3- or 3,4-dicarboxyphenoxy) phenyl] propane dianhydride, 1,3-bis (3,4-dicarboxyphenyl) -1,1,3 3-tetramethyldisiloxane dianhydride, butanetetracarboxylic dianhydride, bicyclo- [2,2,2] -oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, etc. Can be mentioned.

  Examples of dicarboxylic acids or derivatives thereof include succinic acid, glutaric acid, adipic acid, azelaic acid, suberic acid, sebacic acid, decanedioic acid, dodecanedioic acid, dimer acid, isophthalic acid, terephthalic acid, phthalic acid, naphthalenedicarboxylic acid , Oxydibenzoic acid, aliphatic dicarboxylic acid having carboxyl groups at both ends of the polybutadiene oligomer (Nihon Soda Co., Ltd .: Nisso-PB, C series, Ube Industries, Ltd .: Hycar-RLP, CT series, Thiokol Co., Ltd .: HC Polymer series, manufactured by General Tire: Telagen series, manufactured by Philips Petroleum: Butaretz series, etc., carbonate diols (produced by Daicel Chemical Industries: PLACEL, CD-205, 205PL, 205HL, 10,210PL, 210HL, 220,220PL, hydroxyl equivalent or more carboxyl equivalent become dicarboxylic acid ester dicarboxylic acid obtained by reaction of 220HL) can be mentioned.

  Examples of aromatic diamines or derivatives thereof include 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4 '-[2,2-bis ( 4-phenoxyphenyl) propane] diisocyanate, biphenyl-4,4′-diisocyanate, biphenyl-3,3′-diisocyanate, biphenyl-3,4′-diisocyanate, 3,3′-dimethylbiphenyl-4,4′-diisocyanate 2,2′-dimethylbiphenyl-4,4′-diisocyanate, 3,3′-diethylbiphenyl-4,4′-diisocyanate, 2,2′-diethylbiphenyl-4,4′-diisocyanate, 3,3 ′ -Dimethoxybiphenyl-4,4'-diisocyanate, 2,2'-dimethoxybi Enyl-4,4'-diisocyanate, naphthalene-1,5-diisocyanate, naphthalene-2,6-diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane Diisocyanate, transcyclohexane-1,4-diisocyanate, hydrogenated m-xylylene diisocyanate, lysine diisocyanate, carbonate diol (manufactured by Daicel Chemical Industries: PLACEL, CD-205, 205PL, 205HL, 210, 210PL, 210HL, 220, 220PL , 220HL), and diisocyanates such as urethane diisocyanate obtained by reacting with a diisocyanate having an isocyanate equivalent of a hydroxyl equivalent or higher.

  Examples of diamines include siloxane diamines having an amino group bonded to both ends of dimethylsiloxane (silicone oil X-22-161AS (amine equivalent 450), X-22-161A (amine equivalent 840), X-22-161B (amine). Equivalent 1500), X-22-9409 (amine equivalent 700), X-22-1660B-3 (amine equivalent 2200) (above, manufactured by Shin-Etsu Chemical Co., Ltd.), BY16-853 (amine equivalent 650), BY16-853B ( Amine equivalent 2200) (above, manufactured by Toray Dow Corning Silicone)), both-terminal aminated oligomers such as both-terminal aminated polyethylene and both-terminal aminated polypropylene, and both-terminal aminated polymers, diamines having oxyalkylene groups (Jeffer) Min D series, Jeffermin ED series, Jeffermin XT J-511, Jeffamine XTJ-512, both manufactured by Sun Techno Chemical Co., Ltd.) and the like.

  Unlike an aromatic polyimide resin, a polyamide-imide resin having a repeating unit of an amide bond and an imide bond in a resin solution state without passing through a precursor is particularly preferred in the present invention. Further, diisocyanate-modified, BPDA-modified, sulfone-modified and rubber-modified resins of polyamideimide resin can be used. As a commercial item of a polyamideimide resin varnish, Hitachi Chemical Co., Ltd. product: HPC5020, HPC7200, etc. are mentioned, for example.

  In the present invention, the polyamideimide resin is preferably a polyamideimide resin having a resin film elongation of 60 to 120%. If the elongation is less than 60%, the adhesion to the base cage or the like is poor and the film is easily peeled off, and the film is likely to peel off in an environment where it comes into contact with lubricating oil or grease containing sulfur additives. . If the elongation exceeds 120%, the heat resistance will decrease and the lubricant will easily swell. As a commercial item of the polyamide-imide resin whose elongation rate of a resin film is 60 to 120%, Hitachi Chemical Co., Ltd. product: HPC5020 and HPC7200-30 are mentioned, for example.

In the present invention, the elongation percentage of the polyamideimide resin film is measured by the following method.
The polyamide-imide resin solution is applied onto a glass substrate that has been degreased with acetone and then cleaned with nitrogen gas blow, pre-dried at 80 ° C for 30 minutes and then at 150 ° C for 10 minutes, and finally the molecular structure of the polyamide-imide resin Dry for 30 minutes at a suitable curing temperature. The cured coating film is peeled off from the glass substrate to obtain a resin film with a thickness of 80 ± 8 μm. This film is formed into a strip-shaped test piece of 10 mm x 60 mm, the distance between chucks is 20 mm, and the tensile speed is 5 mm / min Measure the elongation (%) with a tensile tester at room temperature.

Fullerene blended in the polyimide resin is a carbon molecule composed of a carbon 5-membered ring and a 6-membered ring and having various polyhedral structures closed in a spherical shape. As a third carbon allotrope following graphite and diamond, H. W. Kroto and R.K. E. It is a new carbon material discovered by Smalley et al. As a typical molecular structure, a C _{60 having} a so-called soccer ball-like structure in which ₆₀ carbon atoms constitute a spherical truncated icosahedron composed of 12 five-membered rings and 20 six-membered rings. Similarly, there are C ₇₀ composed of ₇₀ carbon atoms, and higher fullerenes having a larger number of carbon atoms such as C ₇₆ , C ₇₈ , C ₈₂ , C ₈₄ , C ₉₀ , C ₉₄ , C _96, etc. . Of these, C ₆₀ and C ₇₀ are typical fullerenes. Moreover, a multimer is obtained by making these react. In the present invention, any fullerene can be used, either spherical or multimeric.

  The fullerene production method includes a laser evaporation method, a resistance heating method, an arc discharge method, a thermal decomposition method, etc., and specifically disclosed in, for example, Japanese Patent No. 2802324, which is under reduced pressure or inactive. Fullerenes are obtained by generating carbon vapor in the presence of gas, cooling and cluster growth.

On the other hand, in recent years, a combustion method has been put to practical use as an economical and efficient mass production method. As an example of the combustion method, an apparatus in which a burner is installed in a decompression chamber is used, and a hydrocarbon raw material and oxygen are mixed and supplied to the burner while ventilating the inside of the system with a vacuum pump to generate a flame. Then, the soot-like substance produced | generated by the said flame is collect | recovered with the collection | recovery apparatus provided downstream. In this production method, fullerene is obtained as a solvent-soluble component in soot and is isolated by solvent extraction, sublimation or the like. The obtained fullerene is usually a mixture of C ₆₀ , C ₇₀ and higher order fullerene, and can be further purified to isolate C ₆₀ , C _{70 and the} like.
The fullerene used in the present invention is not particularly limited in its structure and production method, but those having a carbon number of C ₆₀ or C ₇₀ or a mixture thereof are particularly preferred.

Fullerene can be used as a solid compounding agent or as a compounding agent obtained by dissolving and dispersing fullerene in an organic solvent. In any case, C ₆₀ , C ₇₀ and higher order fullerenes can be used alone or in a mixed state, but these can be used in a mixed state from the viewpoint of dispersibility in the resin and the like. preferable.
In order to further improve the dispersibility, the average particle size at the time of mixing is 100 μm or less, preferably 50 μm or less, more preferably 10 μm or less.

  In the present invention, the blending ratio of fullerene is 0.1 to 10% by volume, preferably 0.1 to 5% by volume of solid fullerene with respect to the entire resin composition. More preferably, 0.1 to 1% by volume is blended. If it is less than 0.1% by volume, sufficient wear resistance cannot be obtained, and if it exceeds 10% by volume, the dispersion becomes poor and the wear resistance deteriorates.

  Powdered molybdenum disulfide and tungsten disulfide can be used. In view of dispersibility and surface smoothness of the coating, the particle diameter is 10 μm or less, preferably 5 μm or less. The mixing ratio of molybdenum disulfide and tungsten disulfide is 0.5 to 20% by volume, preferably 0.5 to 15% by volume, based on the entire resin composition. More preferably, 1 to 15% by volume is blended. If it is less than 0.5% by volume, sufficient frictional wear characteristics cannot be obtained, and if it exceeds 20% by volume, the wear resistance is deteriorated.

In the present invention, for the purpose of improving the coefficient of friction and improving the initial conformability without lowering the wear resistance of the coating, the resin composition constituting the coating is a solid such as polytetrafluoroethylene or graphite. A lubricant can be used in combination with fullerene and molybdenum disulfide or tungsten disulfide.
In the present invention, a preferred embodiment of the coating is a coating made of a resin composition in which fullerene and at least one disulfide selected from molybdenum disulfide and tungsten disulfide are dispersed and blended in a polyimide resin.

  The material of the cage used in the universal joint of the present invention is not particularly limited, and iron-based metal materials, copper-based metal materials, aluminum-based metal materials, and resin materials can be used. Structural alloy steel is preferably used. In order to impart an appropriate material strength to these, heat treatment such as quenching and tempering is appropriately performed, and the hardness of the material surface is adjusted to about Vickers hardness HV 750.

  As the material for the constant velocity joint race, structural carbon steel such as S50C or S60C is used for the outer race, and structural alloy steel such as SCr420 is used for the inner race.

In the present invention, as a method for forming a film on a universal joint cage or the like, any film forming method can be employed. For example, the following methods can be exemplified.
First, a cage or the like that is a base made of an iron-based metal material is sufficiently washed to remove surface contamination. Examples of the cleaning method include immersion cleaning with an organic solvent, ultrasonic cleaning, steam cleaning, acid / alkali cleaning, and the like.
For the purpose of improving the adhesion of the coating, it is possible to perform shot blasting (including shot peening, WPC, etc.), chemical etching, and phosphate coating treatment as pretreatment. The surface roughness of the substrate can be set in a range of Ra = 0.3 μm or more, and preferably Ra = 0.3 to 2.0 μm. When Ra is less than 0.3 μm, a sufficient anchor effect cannot be obtained, and adhesion cannot be improved. On the other hand, when the surface roughness of the substrate is large, the finished surface becomes rough. However, if the surface roughness is adjusted to be small by machining such as polishing, it can be used as a cage. Further, if Ra = 0.3 to 2.0 μm, it is possible to obtain a small surface roughness without performing sufficient adhesion and machining.

Next, a coating film is formed on the sliding surface of the cage surface, outer race, and inner race cage with a spray coating method, a dip coating method, an electrostatic coating method, a tumbler coating method, an electrodeposition coating method, or the like. A preferred coating thickness is 1-50 μm, more preferably 6-35 μm. If it is less than 1 μm, it will be worn away or peeled off during operation and sufficient durability will not be obtained, and if it exceeds 50 μm, the dimensional accuracy of the cage will deteriorate and the cost will be further increased, which is not preferable.
Further, in the process of forming the film, the excessively adhered varnish can be removed by physical and chemical methods such as wiping, centrifuging and air blowing, and adjusted to a desired thickness.
After the coating is formed, the cage with the coating formed on the surface is completed by removing the solvent, drying, melting, crosslinking, etc. by heat treatment. When the film thickness is increased, it may be overcoated. It is also possible to perform machining or tumbling after the coating is completed.

  Furthermore, it is preferable that the surface roughness of the outer race and the inner race that come into contact with the cage having a film formed on these surfaces is small. The preferable range is Ra 1.0 μm or less, more preferably Ra 0.8 μm or less. By setting this range, the durability of the coating can be improved. Examples of the method for reducing the surface roughness include lapping, tumbler, and aero lapping.

The materials used in the examples and comparative examples of the present invention are collectively shown as follows. [] Is an abbreviation shown in Table 2.
(1) Polyamideimide resin varnish [PAI]
Hitachi Chemical Co., Ltd .: HPC-5020, Elongation: 70%
(2) Aromatic polyimide resin varnish [PI]
Ube Industries, Ltd .: U Varnish-A
(3) Mixed fullerene [mixed fullerene]
Frontier Carbon Co .: mixed fullerene, C ₆₀ (diameter: 0.71 nm) is about 60% by mass, C ₇₀ (long axis diameter: 0.796 nm, short axis diameter: 0.712 nm) is about 25% by mass, and the remainder is higher order fullerene It is a mixture of
(4) Silicon carbide [SiC]
Soekawa Riken Co., Ltd .: Reagent, average particle size 1μm
(5) molybdenum disulfide powder [MoS ₂ -0.5]
Nippon Molybdenum Co., Ltd .: M5, average particle size 0.5 μm
(6) Tungsten disulfide powder [WS ₂ −1 μm]
Nippon Lubricant Co., Ltd .: WS2A, average particle size 1 μm
(7) Polytetrafluoroethylene powder [PTFE-0.3 μm]
Kitamura Co., Ltd .: KD-1000AS dispersion (solvent: NMP), average particle size 0.3 μm
(8) Graphite powder [Graphite-6μm]
Lonza KS-6, average particle size 6μm

Examples 1-6, Comparative Examples 4-12
Various fillers were mixed with the solid content of the polyamide-imide resin varnish (solvent: N-methyl-2-pyrrolidone) at a ratio shown in Table 2 until sufficiently uniformly dispersed by a ball mill, and the mixture was mixed with SCr420 for friction test. The outer diameter surface of a ring [outer diameter 40 mm × inner diameter 20 mm × thickness 10 mm (subcurvature R 60), surface roughness Ra 1.0 μm: 21 in FIG. After coating, the film was dried at 100 ° C for 1 hour, further at 150 ° C for 1 hour, and baked at 250 ° C for 1 hour. The coating thickness was adjusted by changing the number of sprays. The coating solution containing fullerene is prepared in advance as a concentrated solution in which fullerene is dissolved at a concentration of 5% by weight in a mixed solvent of toluene and N-methyl-2-pyrrolidone (mixing weight ratio 50:50). It was added to a polyamide-imide resin varnish to prepare a predetermined concentration. In addition, the mixture ratio of each component of Table 2 is a ratio in solid content, and all are volume%.
The obtained test piece is subjected to the friction test shown below, and the friction coefficient, the specific wear amount, and the state of the coating after the test are also shown in Table 2.

Example 7
Example 1 except that aromatic polyimide resin varnish (solvent: N-methyl-2-pyrrolidone) was used and blended fullerene and molybdenum disulfide in the proportions shown in Table 2 and the firing temperature after coating was 350 ° C. Test pieces were prepared in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The results are also shown in Table 2.

Comparative Example 1
The same test piece as in Example 1 was used without treatment, and evaluated in the same manner as in Example 1. The results are also shown in Table 2.

Comparative Example 2
The same test piece as in Example 1 was subjected to electroless plating containing ethylene tetrafluoride resin powder (30% by mass) nickel plating (plating thickness: 20 μm): Nippon Kanisen-Kaniflon. The obtained test piece was evaluated in the same manner as in Example 1. The results are also shown in Table 2.

Comparative Example 3
A test piece similar to that in Example 1 was subjected to a manganese phosphate coating treatment. The obtained test piece was evaluated in the same manner as in Example 1. The results are also shown in Table 2.

Comparative Example 13
SUJ2 ring for friction test [Outer diameter 40 mm × Inner diameter 20 mm × Thickness 10 mm (Sub curvature R 60) surface roughness adjusted to Ra 0.08 μm to form the same coating as in Example 4 The test specimens were evaluated in the same manner as in Example 1. The results are also shown in Table 2.

Comparative Example 14
For the same ring as in Example 4, the surface roughness of the steel plate 20 [SCr420 quenching and tempering product (Hv 700)] was Ra 3.0 μm, and the obtained test piece was evaluated in the same manner as in Example 1. The results are also shown in Table 2.

<Friction test>
A friction test was performed using the obtained ring-shaped test piece. FIG. 3 is a diagram showing a friction tester. 3A shows a front view, and FIG. 3B shows a side view.
A ring-shaped test piece 21 is attached to the rotating shaft 22, and a steel plate 24 is fixed to the air slider 25 of the arm portion 23. The ring-shaped test piece 21 is in rotational contact with a steel plate 24 [SCr420 carburized and tempered product (Hv 700, surface roughness Ra 1.0 μm)] while a predetermined load 26 is applied from above. The frictional force generated when the ring-shaped test piece 21 is rotated is detected by the load cell 27.
The lubricating oil was supplied to the sliding surface by impregnating the felt pad 28 with the lubricating oil mobile velocity oil No. 3 (manufactured by Exxon Mobil: VG2) and bringing the felt pad 28 into contact with the ring-shaped test piece 21. In this state, a friction test was performed under the conditions of a load of 50 N and a sliding speed of 0.05 m / sec between the ring-shaped test piece 21 and the steel plate 24. The test time was 60 minutes.
The average friction coefficient for 10 minutes before the end of the test was compared. The wear volume was determined from the wear marks on the steel plate, and the specific wear amount (× 10 ⁻¹⁰ mm ³ / (N · m)) was calculated. In addition, after the test, the state of the coating formed on the outer diameter surface of the ring-shaped test piece 21 was visually observed. A case where there is no peeling is evaluated as “Fail”, and a case with a large amount of wear is evaluated as “Fail”.

  As shown in Table 2, since Examples 1 to 7 are polyimide resin coatings containing a predetermined amount of fullerene and molybdenum disulfide or tungsten disulfide, the friction coefficient is low. There was no noticeable wear.

  Further, as is apparent from Table 2, the untreated comparative example 1 showed a large value for both the friction coefficient and the specific wear amount of the steel plate. The comparative example 2 which gave the nickel tetrafluoride resin powder containing nickel plating also peeled during the test, and did not contribute to a characteristic improvement. Even in Comparative Example 3 in which the phosphate coating was formed, the durability was not sufficient. In Comparative Example 4 to Comparative Example 11 in which a film using a synthetic resin as a base material was formed, the film was not blended with a predetermined amount of fullerene and disulfide, and thus the film was inferior due to peeling or abrasion. It was. In Comparative Example 12, the film was thin because the film was thin although a predetermined amount of fullerene and molybdenum disulfide were blended in the film. Further, even when a resin film having the same composition as in Example 4 is formed, the properties of the comparative example 13 with a small surface roughness of the substrate and the comparative example 14 with a rough surface of the counter steel plate are inferior due to peeling or abrasion. It was.

  In the universal joint of the present invention, a polyimide resin film in which fullerene and molybdenum disulfide or tungsten disulfide are blended is formed on a cage surface or a sliding surface with an outer race or inner race cage. These coatings have excellent adhesion to cages, outer races, and inner races, and since friction due to contact between the cages, outer races, and inner races is small and there is no wear or delamination, seizure hardly occurs and long life is achieved. Therefore, high reliability can be obtained. Therefore, it can be suitably used as a constant velocity joint that is small and light, has low energy loss, and is used in harsh usage environments.

It is a figure which shows the 1st Embodiment of this invention. It is a figure which shows the 2nd Embodiment of this invention. It is a figure which shows a friction tester.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ball fixed joint 2,12 Outer race 3,13 Inner race 4,5,14,15 Ball rolling groove 6,16 Ball 7,17 Cage 8,18 Shaft 9,19 Boot 10,20 Grease 11 Double offset joint 21 Ring-shaped test piece 22 Rotating shaft 23 Arm part 24 Steel plate 25 Air slider 26 Load 27 Load cell 28 Felt pad impregnated with lubricating oil

Claims (11)

An inner race and an outer race each having a ball rolling groove, a plurality of balls fitted in the ball rolling groove, and an outer peripheral surface of the inner race and an inner peripheral surface of the outer race. A universal joint having an annular cage formed by penetrating a pocket portion for holding the ball,
Fullerene and at least one disulfide selected from molybdenum disulfide and tungsten disulfide are included in the synthetic resin in at least a portion of the cage surface that comes into contact with the inner race, the outer race, and the ball. A universal joint characterized in that a film made of a resin composition is formed, and the fullerene is contained in an amount of 0.1 to 10% by volume and the disulfide is contained in an amount of 0.5 to 20% by volume with respect to the entire resin composition.   2. The universal joint according to claim 1, wherein the coating is formed on an inner peripheral surface that is in sliding contact with the inner race of the cage and an outer peripheral surface that is in sliding contact with the outer race of the cage.   The universal joint according to claim 1, wherein the coating is formed on an inner peripheral surface of a pocket portion that is in sliding contact with the ball of the cage.   The universal joint according to claim 1, wherein the synthetic resin is a polyimide resin.   The universal joint according to claim 4, wherein the polyimide resin is a polyamide-imide resin having an elongation of 60 to 120%.   The universal joint according to any one of claims 1 to 5, wherein the film thickness is 1 to 50 µm.   The universal joint according to any one of claims 1 to 6, wherein the surface of the cage has a surface roughness Ra of 0.3 to 2.0 µm before the coating is formed.   The universal joint according to any one of claims 1 to 7, wherein a surface roughness Ra of the outer race and the inner race in contact with the cage is 1.0 µm or less.   The universal joint according to any one of claims 1 to 8, wherein the coating is formed on a portion of the outer race and the inner race that comes into contact with at least the cage.   The universal joint according to any one of claims 1 to 9, wherein the universal joint is a fixed type constant velocity universal joint used on a wheel side of a drive train of an automobile.   The universal joint according to any one of claims 1 to 9, wherein the universal joint is a sliding type constant velocity universal joint used on a differential side of a drive train of an automobile.

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