JP5027526B2 - Universal joint and manufacturing method thereof - Google Patents

Description

  The present invention relates to a universal joint (joint) enclosing a foamed lubricant and a method for manufacturing the same.

In recent years, technical improvements for higher performance, compactness, and weight reduction of automobiles have progressed, and there is a demand for miniaturization, higher performance, and longer life of universal joints used for drive transmission of automobile parts and industrial machines. It is growing.
Along with the progress of downsizing and weight reduction, a high load is also applied to the universal joint, and it may be difficult to achieve a long life with conventional grease lubrication. As higher performance is required in the future, simply optimizing the amount of grease and additives will limit the prevention of lubricant scattering and dripping under high temperature, high speed, and high load usage environments. There is.
In order to solve such a problem, a foaming lubricant in which a solid component is foamed and filled with a lubricating oil has been reported (see Patent Document 1).
In this foamed lubricant, the solid lubricant is compressed following the boot that is deformed by the bending of the constant velocity joint. Here, the liquid lubricant that has exuded from the solid lubricant is supplied to a necessary portion, and good lubrication is possible.

  The lubricant disclosed in Patent Document 1 is a post-impregnation type in which a foamed resin is impregnated with a lubricating oil. In the case of the post-impregnation type, the lubricating oil is impregnated in the foaming space of the foamed resin, but hardly impregnated in the foamed resin itself. For this reason, there is a problem that the lubricating oil retention force is small, such as when the affinity between the foamed resin and the lubricating oil is weak, and the lubricating oil escapes at a time when used under high speed conditions. Such a foamed lubricant can be used in a short time of lubrication or in a sealed space, but is difficult to use in a long time or in an open space. Further, since the oil retention is not high, the lubricant constantly flows in the space while repeating the release of the lubricant and the absorption into the foam. In such a case, depending on the chemical nature of the lubricating oil and the additives contained in it, there is a possibility that the boot material may be attacked and deteriorated, and there is a problem that the material selection of either the lubricant or the boot material is limited. is there. In addition, there are problems in that the number of man-hours in the manufacturing process associated with post-impregnation, the increase in manufacturing time, and the cost increase associated therewith are unavoidable.

Therefore, a universal joint using a solid lubricant that has high lubricant retention and allows large deformation is required for the reasons described above. In particular, it is necessary to include lubricating oil or the like in the solid resin component to increase the lubricant retention.
In this way, the lubricant required for universal joints can supply the required amount to the required locations even compared to the grease lubrication that is widely used in the industry. This technology has the advantage of reducing costs by reducing the load, reducing the load on boot materials, and reducing the weight and size of universal joints. It can be said that this technology is highly socially important from multiple viewpoints.
Japanese Patent Laid-Open No. 9-42297

  The present invention has been made to cope with such problems, and is a universal joint in which a foamed lubricant is enclosed, which has a long service life, is low in cost, is excellent in productivity, and can simultaneously reduce the load on the environment. And it aims at provision of the manufacturing method.

  In the universal joint according to the present invention, the rotational torque is transmitted by the engagement between the track groove and the torque transmission member, and the torque transmission member rolls along the track groove to move in the axial direction. Is a universal joint in which a foaming lubricant is enclosed, and the foaming lubricant foams a mixture containing a lubricating component, a urethane prepolymer having an isocyanate group in the molecule, a curing agent, and a foaming agent. -It is cured, and the blending ratio of the lubricating component is 1 to 90% by weight with respect to the whole mixture.

The curing agent is an aromatic polyamine compound, and the foaming agent is water.
The mixture is filled around the torque transmission member before foaming / curing is completed.
The open-cell ratio of the foamed lubricant is 50% or more.
The universal joint is a constant velocity universal joint.

  The method for producing a universal joint of the present invention includes a mixing step of mixing a component containing a lubricating component, a urethane prepolymer having an isocyanate group in the molecule, a curing agent, and a foaming agent to obtain a mixture, Before the foaming / curing is completed, the method includes a filling step of filling the mixture around the torque transmission member and a foaming / curing step of foaming / curing the filled mixture.

  The foaming lubricant used in the universal joint of the present invention is formed by foaming and curing a mixture containing a lubricating component, a urethane prepolymer having an isocyanate group in the molecule, a curing agent, and a foaming agent. Occluded in the foamed and hardened solid component. For this reason, the lubricating oil is gradually released from the foamed lubricant due to the centrifugal force accompanying the rotational movement of the universal joint and external stresses such as compression, bending, and expansion that occur when the universal joint takes an angle. Therefore, it has excellent lubricant holding power, and the universal joint can be miniaturized, improved in performance and extended in life.

  Moreover, since the manufacturing method of the universal joint of this invention consists of the said mixing process, a filling process, and a foaming and hardening process, it is not necessary to enclose a lubricant after an assembly. As a result, the production efficiency is improved and it can be manufactured at a low cost.

As a solid lubricant used in universal joints, as a result of intensive studies on a solid lubricant that has excellent lubricating oil retention and can suppress the amount of lubricating oil seepage to a minimum, a lubricating component and a urethane prepolymer having an isocyanate group in the molecule A foamed lubricant was obtained by foaming and curing a mixture containing a curing agent and a foaming agent. This foamed lubricant is a solid material in which a urethane prepolymer is made porous by foaming and curing, and is a foamed lubricant formed by occluding a lubricating component in the resin. It should be noted that the lubrication component is occluded in the foamed / cured solid component is a urethane prepolymer or a curing agent in the solid component obtained by foaming / curing a liquid / semi-solid lubricant component such as a lubricating oil or grease described later. It does not react with, and does not become a compound.
This foaming lubricant has excellent lubricating oil retention, can suppress the amount of lubricating oil spilled even if it is deformed by external force, can be manufactured at a low cost, and can be sealed only at the necessary parts of the universal joint. It turned out that it can manufacture efficiently. The present invention is based on such knowledge.

The foamed lubricant used in the universal joint of the present invention allows the lubricating component to be occluded in the resin, so that the flexibility of the resin causes the lubricant to exude by deformation due to external force such as compression, expansion, bending, and twisting. It can be released gradually from between the resin molecules. At this time, the amount of lubricating oil that oozes out can be minimized by changing the degree of elastic deformation according to the magnitude of the external force by selecting the resin.
Further, in the foamed lubricant used in the present invention, the resin component has a large surface area due to foaming, and the excess lubricating oil that has oozed out can be temporarily held in the foam bubbles again and ooze out. The amount of oil is stable, and by retaining the lubricant in the resin and impregnating the bubbles, the retained amount of the lubricating oil becomes larger than the non-foamed state.

In addition, the foamed lubricant used in the present invention requires very little energy when bent compared to non-foamed materials, and can be flexibly deformed while retaining the lubricating oil at a high density. Further, since the bulk density is reduced by foaming and there are many porous portions, it is advantageous in terms of weight reduction.
Also, since it is only necessary to foam and cure a mixture containing a lubricating component, a urethane prepolymer, a curing agent, and a foaming agent, no special equipment is required, and it can be filled and molded in any place. Is possible.
Further, the density of the foaming lubricant can be changed by controlling the blending amount of the mixture containing the lubricating component, the urethane prepolymer, the curing agent, and the foaming agent.

  The urethane prepolymer used in the present invention is a urethane prepolymer having an isocyanate group in the molecule, and this isocyanate group may be blocked by another substituent. The isocyanate group contained in the molecule may be at the end of the molecular chain or may be contained at the end of the side chain branched from the molecular chain. The urethane prepolymer may have a urethane bond in the molecular chain.

The urethane prepolymer can be obtained by reacting a compound having an active hydrogen group with a polyisocyanate.
Examples of the compound having an active hydrogen group include low molecular polyols, polyether polyols, polyester polyols, and castor oil polyols. These can be used alone or as a mixture of two or more. Examples of the low molecular polyol include divalent ones such as ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, hydrogenated bisphenol A, etc. (3- to 8-valent ones) For example, glycerin, trimethylolpropane, hexanetriol, pentaerythritol, sorbitol, shoelace and the like.

  Examples of polyether polyols include alkylene oxide (alkylene oxides having 2 to 4 carbon atoms such as ethylene oxide, propylene oxide, butylene oxide) adducts of the above low molecular polyols and ring-opening polymers of alkylene oxides. Includes polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycol.

  Examples of polyester polyols include polyester polyols, polycaprolactone polyols, and polyether ester polyols. Polyester polyols are carboxylic acids (aliphatic saturated or unsaturated carboxylic acids such as adipic acid, azelaic acid, dodecanoic acid, maleic acid, fumaric acid, itaconic acid, dimerized linoleic acid and / or aromatic carboxylic acids such as phthalic acid. , Isophthalic acid) and a polyol (the above low molecular polyol and / or polyether polyol).

Polycaprolactone polyol is a polymerization initiator for glycols and triols such as ε-caprolactone, α-methyl-ε-caprolactone, ε-methyl-ε-caprolactone, etc. as organometallic compounds, metal chelate compounds, fatty acid metal acylates, etc. Obtained by addition polymerization in the presence of a catalyst. The polyether ester polyol is obtained by subjecting a polyester having a carboxyl group and / or an OH group to an addition reaction of an alkylene oxide such as ethylene oxide or propylene oxide. As the castor oil-based polyol, castor oil and castor oil or castor oil fatty acid and the above low molecular polyol, polyether polyol, and polyester polyol are transesterified or esterified polyol.
The urethane prepolymer used in the present invention preferably has an isocyanate group (—NCO) content of 2% by weight or more. If the isocyanate group (-NCO) content is less than this, it becomes difficult to achieve both foamability and elasticity.

Polyisocyanates include aromatic diisocyanates, aliphatic or alicyclic and polyisocyanate compounds.
Aromatic diisocyanates include, for example, diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate and mixtures thereof, 1,5-naphthylene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate Is mentioned.
Aliphatic or alicyclic diisocyanates include, for example, 1,6-hexamethylene diisocyanate, 1,12-dodecane diisocyanate, 1,3-cyclobutane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isopropane diisocyanate. 2,4-hexahydrotoluylene diisocyanate, 2,6-hexahydrotoluylene diisocyanate, 1,3-hexahydrophenyl diisocyanate, 1,4-hexahydrophenyl diisocyanate, 2,4′perhydrodiphenylmethane diisocyanate, 4, 4'-perhydrodiphenylmethane diisocyanate is mentioned.
Examples of the polyisocyanate compound include 4,4 ′, 4 ″ -triphenylmethane triisocyanate, 4,6,4′-diphenyl triisocyanate, 2,4,4′-diphenyl ether triisocyanate, and polymethylene polyphenyl polyisocyanate. It is done.
Moreover, what modified | denatured some of these isocyanate to biuret, allophanate, carbodiimide, oxazolidone, amide, imide, etc. is mentioned.

Examples of the urethane prepolymer suitable for the present invention include polypolymer ester polyol and prepolymer obtained by addition polymerization of polyisocyanate to polyether polyol, which are known as casting urethane prepolymers.
The polylactone ester polyol is preferably a urethane prepolymer obtained by addition polymerization of a polyisocyanate in the presence of a short-chain polyol to a polylactone ester polyol obtained by ring-opening reaction of caprolactone.
Examples of the polyether polyol include alkylene oxide addition products or ring-opening polymerization products, and urethane prepolymers obtained by addition polymerization of these with polyisocyanates are preferable.

  Examples of commercially available urethane prepolymers that can be suitably used in the present invention include trade name Plaxel EP manufactured by Daicel Chemical Industries, and trade names Coronate 4090 and 4047 manufactured by Nippon Polyurethane. Plaxel EP is a white solid urethane prepolymer having a melting point above room temperature.

  Curing agents for curing the urethane prepolymer include 3,3′-dichloro-4,4′-diaminodiphenylmethane (hereinafter referred to as MOCA) and 4,4′-diamino-3,3′-diethyl-5. 5'-dimethyldiphenylmethane, trimethylene-bis- (4-aminobenzoate), bis (methylthio) -2,4-toluenediamine, bis (methylthio) -2,6-toluenediamine, methylthiotoluenediamine, 3,5- Aromatic polyamines typified by diethyltoluene-2,4-diamine, 3,5-diethyltoluene-2,6-diamine, the above polyisocyanates, low molecular polyols typified by 1,4-butaneglycol and trimethylolpropane , Polyether polyol, castor oil-based polyol, polyester-based polyol, hydroxyl-terminated liquid polybutadiene Hydroxyl-terminated liquid polyisoprene, hydroxyl-terminated polyolefin-based polyols, and liquid rubbers having two or more hydroxyl groups represented by compounds in which the terminal hydroxyl groups of these compounds are modified with an isocyanate group or an epoxy group are used alone or in combination. be able to. Among these, an aromatic polyamine which can achieve both foamability and rubber-like elasticity and is easily available industrially is preferable for curing a urethane prepolymer obtained by addition polymerization of polylactone ester polyol and polyisocyanate.

The blending ratio of the urethane prepolymer having an isocyanate group and the curing agent having a terminal hydroxyl group or a terminal amine group is an equivalent ratio of the hydroxyl group (—OH) or amine group (—NH ₂ ) to the isocyanate group (—NCO). preferably in the range of (OH or NH ₂ /NCO)=1/(0.9~1.7), especially considering the foaming and elasticity, (OH or NH ₂ /NCO)=1/(1.0 ~ 1.5) is preferred.

  Moreover, an additive can be used in the solid component as necessary. Additives include antioxidants typified by hindered phenols, reinforcing agents (carbon black, white carbon, colloidal silica, etc.), inorganic fillers (calcium carbonate, barium sulfate, talc, clay, meteorite powder, etc.) Examples include anti-aging agents, flame retardants, metal deactivators, antistatic agents, antifungal agents, fillers, and coloring agents.

The foaming agent that can be used in the present invention can be used as long as it can foam the urethane prepolymer. Examples of the foaming agent include (a) a chemical foaming agent such as water that reacts with an isocyanate compound to generate carbon dioxide gas, and (b) azobisiso that generates nitrogen gas by chemical decomposition by heat treatment or light irradiation. Decomposable foaming agents such as butyronitrile (AIBN) and azodicarbonamide (ADCA), (c) a physical foaming agent that heats and vaporizes a relatively low boiling organic solvent such as acetone and hexane, and (d) nitrogen. And a mechanical foaming agent that blows an inert gas or air from the outside.
In this invention, since the urethane prepolymer which has an isocyanate group in a molecule | numerator is used, the water which reacts with an isocyanate compound and generate | occur | produces a carbon dioxide gas is preferable.

Moreover, when using the chemical foaming method with such a reaction, it is preferable to use a catalyst as needed, for example, a tertiary amine catalyst or an organometallic catalyst is used. Examples of the tertiary amine catalyst include monoamines, diamines, triamines, cyclic amines, alcohol amines, ether amines, imidazole derivatives, and acid block amine catalysts.
Examples of organometallic catalysts include stanaoctate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin mercaptide, dibutyltin thiocarboxylate, dibutyltin maleate, dioctyltin dimercaptide, dioctyltin thiocarboxylate, octenoate, etc. Is mentioned. Moreover, you may mix and use these multiple types for the purpose of adjusting the balance of reaction.

The lubricating component that can be used in the present invention can be used regardless of the type as long as it does not dissolve the solid component forming the foam. As the lubricating component, for example, lubricating oil, grease, wax or the like can be used alone or in combination.
Examples of the lubricating oil include paraffinic and naphthenic mineral oils, ester synthetic oils, ether synthetic oils, hydrocarbon synthetic oils, GTL base oils, fluorine oils, and silicone oils. These can be used alone or as a mixed oil.

The grease is obtained by adding a thickener to a base oil, and examples of the base oil include the above-described lubricating oil.
Examples of the thickener include soaps such as lithium soap, lithium complex soap, calcium soap, calcium complex soap, aluminum soap, aluminum complex soap, and urea-based compounds such as diurea compounds and polyurea compounds, but are particularly limited. It is not a thing.
A diurea compound is obtained by reaction of diisocyanate and a monoamine, for example. Examples of diisocyanates include phenylene diisocyanate, diphenyl diisocyanate, phenyl diisocyanate, diphenylmethane diisocyanate, octadecane diisocyanate, decane diisocyanate, hexane diisocyanate, and monoamines include octylamine, dodecylamine, hexadecylamine, octadecylamine, oleylamine, aniline, Examples include p-toluidine, cyclohexylamine and the like. The polyurea compound can be obtained, for example, by reacting diisocyanate with a monoamine or diamine. Examples of the diisocyanate and monoamine include those similar to those used for the production of the diurea compound. Examples of the diamine include ethylenediamine, propanediamine, butanediamine, hexanediamine, octanediamine, phenylenediamine, tolylenediamine, and xylenediamine. Is mentioned.

  The blending ratio of the base oil in the grease is 1 to 98% by weight, preferably 5 to 95% by weight, based on the whole grease component. If the base oil is less than 1% by weight, it will be difficult to sufficiently supply the lubricating oil to the necessary locations. On the other hand, when it is more than 98% by weight, it remains liquid even at low temperatures.

  Examples of waxes include hydrocarbon synthetic waxes, polyethylene waxes, fatty acid ester waxes, fatty acid amide waxes, ketones / amines, hydrogenated oils, and the like. As oil components that may be used by mixing oil with these waxes, the same oil components as those described above can be used.

  Lubricating components further include solid lubricants such as molybdenum disulfide and graphite, friction modifiers such as organic molybdenum, oily agents such as amines, fatty acids and fats, antioxidants such as amines and phenolic compounds, petroleum sulfonates. Rust inhibitors such as dinonyl naphthalene sulfonate and sorbitan esters, extreme pressure agents such as sulfur and sulfur-phosphorus compounds, antiwear agents such as organic zinc and phosphorus compounds, metals such as benzotriazole and sodium nitrite Various additives such as viscosity index improvers such as an inert agent, polymethacrylate, and polystyrene may be included.

The foaming lubricant used in the present invention is obtained by foaming and curing a mixture containing the above-described lubricating component, urethane prepolymer, curing agent, and foaming agent.
The blending ratio of the lubricating component is 1% by weight to 90% by weight, preferably 5% by weight to 80% by weight, based on the entire mixture. When the lubricating component is less than 1% by weight, the supply amount of the lubricating component is small and the function as a foaming lubricant cannot be exhibited, and when it exceeds 90% by weight, it does not solidify.
The blending ratio of the urethane prepolymer having an isocyanate group in the molecule is 8% by weight to 98% by weight, preferably 20% by weight to 80% by weight, based on the entire mixture. When it is less than 8% by weight, it does not solidify, so it does not function as a foaming lubricant. When it is more than 98% by weight, the supply amount of the lubricating component is small and the function as a foaming lubricant cannot be exhibited.

  The blending ratio of the curing agent is determined by the blending amount of the urethane prepolymer and the foaming ratio, and the blending ratio of the foaming agent is determined in relation to the foaming ratio described later. That is, the amount (ratio) of the curing agent is determined by the relationship between the hydroxyl equivalent of the urethane prepolymer having an isocyanate group in the molecule and the equivalent of water.

In the present invention, using a reactive impregnation method in which a foaming reaction and a curing reaction are simultaneously performed in the presence of a lubricating component such as a lubricating oil, in order to achieve both high filling of the lubricating component and high strength of material properties at the same time. desirable. This is because the lubricant is uniformly impregnated into the foam formed in the foam during the foam formation stage, and the lubricant is occluded in the foamed / cured solid component, so that the lubricant is highly filled and the material properties It is considered that the increase in strength is compatible.
On the other hand, after the foam is manufactured in advance, the post-impregnation method in which the lubricant is impregnated does not have sufficient lubricant holding power, and the lubricant is released in a short period of time and supplied when used for a long time. It becomes insufficient.

  In the present invention, it is preferable that the bubbles generated when the urethane prepolymer is made porous by foaming are open cells that communicate with each other. This is because the lubricating component is directly supplied from the surface of the resin to the outside through open cells by external stress. In the case of closed cells where the bubbles do not communicate with each other, the entire amount of lubricating oil in the solid component is temporarily isolated in the closed cells, making it difficult to move between the bubbles, and may not be sufficiently supplied to the outside when necessary. is there.

  The open cell ratio of the foamed lubricant used in the present invention is preferably 50% or more, more preferably 70% or more. When the open cell ratio is less than 50%, the ratio of the resin component (solid component) lubricating oil temporarily taken up into the closed cells increases and may not be supplied to the outside when necessary.

The open cell ratio of the foamed lubricant used in the present invention can be calculated by the following procedure.
(1) The foamed and hardened foamed lubricant is cut into an appropriate size to obtain Sample A. The weight of sample A is measured.
(2) Soxhlet A is washed for 3 hours (solvent: petroleum benzine). Thereafter, the sample is left in a thermostatic bath at 80 ° C. for 2 hours to completely dry the organic solvent, and sample B is obtained. The weight of sample B is measured.
(3) The open cell ratio is calculated by the following procedure.
Open cell ratio = (1− (weight of resin component of sample B−weight of resin component of sample A) / weight of lubricating component of sample A) × 100
The resin component weight and the lubrication component weight of Samples A and B are calculated by multiplying the weights of Samples A and B by the composition charge ratio.
Lubricating components taken into discontinuous closed cells are not released to the outside by Soxhlet cleaning for 3 hours, so the weight of sample B is not reduced. The open cell ratio can be calculated as the release of the lubricating component.

  In the present invention, the foaming ratio of the foamed lubricant is preferably 1.1 times to 100 times, more preferably 1.1 times to 10 times. When the expansion ratio is less than 1.1 times, the bubble volume is small and deformation cannot be allowed when external stress is applied. Also, if it exceeds 100 times, it will be difficult to obtain the strength to withstand external stress.

Examples of using the universal joint of the present invention for a constant velocity joint include a ball fixed joint (hereinafter referred to as BJ), an undercut free joint (hereinafter referred to as UJ), and the like. The number of torque transmitting members (balls) of such BJ and UJ may be 6 or 8.
When foamed lubricant is enclosed in BJ or UJ, only the necessary parts are filled with the lubricant, which contributes to cost reduction and weight reduction, and because the operating angle used is large, compression and It is easy to bend and the lubricant is easily supplied to the sliding part.
Examples of use for the sliding constant velocity joint include a double offset joint (hereinafter referred to as DOJ), a tripod joint (hereinafter referred to as TJ), and a cross groove joint. The number of DOJ torque transmission members (balls) may be six or eight.
Moreover, a cross joint etc. are mentioned as an inconstant velocity joint.

The universal joint of this invention is demonstrated based on FIGS. 1-3. 1 is a partially cutaway sectional view of BJ, FIG. 2 is a partially cutaway sectional view of DOJ, and FIG. 3 is a partially cutaway sectional view of TJ.
As shown in FIG. 1, the BJ 1 has six track grooves 4, 5 in the axial direction formed at equal angles on the inner surface of the outer member 2 and the outer surface of the spherical inner member 3, and between the track grooves 4, 5. The torque transmission member 6 incorporated in the housing 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 member 3.
Further, the outer periphery of the outer member 2 and the outer periphery of the shaft 8 are covered with a boot 9, and the outer member 2, the spherical inner member 3, the track grooves 4 and 5, the torque transmission member 6, and the cage 7 The foamed lubricant 10 is enclosed in a space surrounded by the shaft 8.

As shown in FIG. 2, the DOJ 11 has six track grooves 14 and 15 in the axial direction formed at equal angles on the inner surface of the outer member 12 and the outer surface of the spherical inner member 13, and between the track grooves 14 and 15. The torque transmission member 16 incorporated in the cage 17 is supported by a cage 17, the outer periphery of the cage 17 is a spherical surface 17 a, and the inner periphery is a spherical surface 17 b that fits the outer periphery of the inner member 13. ), (B) are shifted in the axial direction on the axial center of the outer member 12.
The outer periphery of the outer member 12 and the outer periphery of the shaft 18 are covered with a boot 19, and the outer member 12, the spherical inner member 13, the track grooves 14 and 15, the torque transmission member 16, and the cage 17 The foamed lubricant 20 is enclosed in a space surrounded by the shaft 18.

As shown in FIG. 3, the TJ 21 has three cylindrical track grooves 23 in the axial direction formed at equal angles on the inner surface of the outer member 22, and the tripod member 24 incorporated inside the outer member 22 has three Leg shafts 25, spherical rollers 26 serving as torque transmission members are fitted on the outer sides of the respective leg shafts 25, and needles 27 are assembled between the spherical rollers 26 serving as torque transmission members and the leg shafts 25 to generate torque. A spherical roller 26 as a transmission member is supported so as to be rotatable and slidable in the axial direction, and the spherical roller 26 as a torque transmission member is fitted into the track groove 23.
The outer periphery of the outer member 22 and the outer periphery of the shaft 28 are covered with a boot 29, and the foamed lubricant 30 is placed in a space surrounded by the outer member 22, the track groove 23, the tripod member 24, and the shaft 28. It is enclosed.

For such TJ and DOJ, it is necessary to slide in the axial direction. Therefore, when an existing lubricant such as grease is used, the enclosed space volume is larger than that of the above-described fixed joint such as BJ.
However, since the foaming lubricant (10 in FIG. 1, 20 in FIG. 2, 30 in FIG. 3) can be filled only in the necessary parts, the cost is reduced when the foaming lubricant is enclosed in DOJ or TJ. The contribution to weight reduction is greater.

The method for manufacturing a universal joint according to the present invention is a method for manufacturing the above-described universal joint, in which the components of the raw materials are mixed to obtain a mixture, and before the foaming / curing of the mixture is completed, A filling step for filling the periphery of the torque transmitting member; and a foaming / curing step for foaming and curing the filled mixture to obtain a solid.
In the universal joint of the present invention, a predetermined space of the subassembly assembled only around the torque transmission member of the above-mentioned various universal joints is filled with a mixture of at least a urethane prepolymer, a curing agent, a lubricating component, and a foaming agent. After curing, it is obtained by assembling a member such as a boot. Since the mixture is simply filled into the universal joint sub-assembly and foamed / cured, it can be easily filled into any part of the universal joint with a complicated shape. The resulting universal joint already contains a lubricant. Is impregnated. For this reason, a molding die for obtaining a foamed molded article, a post-impregnation step of a lubricant, and the like are unnecessary.

The said mixing process is a process of mixing each component of a raw material and obtaining a mixture. A method of mixing a mixture containing a lubricating component, a urethane prepolymer having an isocyanate group in the molecule, a curing agent, and a foaming agent is not particularly limited. For example, a Henschel mixer, ribbon mixer, juicer mixer, mixing Mixing can be performed using a generally used stirrer such as a head.
For the mixture, it is desirable to use a surfactant such as a commercially available silicone foam stabilizer, and to uniformly disperse each raw material molecule. Further, the surface tension can be controlled by the type of the foam stabilizer, and the type of the generated bubbles can be controlled to open cells or closed cells. Examples of such surfactants include anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, silicone surfactants, and fluorine surfactants.

  The filling step is a step of filling an arbitrary part of the universal joint subassembly before the mixture is foamed and cured. Since the mixture before foaming / curing is fluid, it can be easily filled into any part of a universal joint having a complicated shape. In addition, when filling the mixture, it can be formed into a predetermined shape by covering the side surface of the predetermined space in the universal joint sub-assembly with a jig such as a metal fitting as necessary.

The foaming / curing step is a step of foaming / curing the filled mixture in the universal joint sub-assembly.
As the means for foaming the resin component, the above-described foaming means can be employed. In the present invention, a compound having a highly reactive isocyanate group is used as a raw material, and chemical foaming by carbon dioxide generated by a chemical reaction between an isocyanate compound and water molecules is used. Moreover, when using foaming with such a reaction, it is preferable to use the above-mentioned catalyst as needed.
Further, the bubbles obtained by foaming are preferably the above-mentioned open cells, and the foaming ratio of the resin component is preferably 1.1 times to 100 times.

Further, in the above manufacturing method, as a method other than filling the mixture into the universal joint sub-assembly, there is a method in which the foamed lubricant formed by foaming and curing after filling into the molding die is incorporated into the universal joint.
There is also a method of foaming and curing the mixture at normal pressure without using a molding die. In this case, the foamed and cured product must be post-processed into the desired shape by cutting or grinding, and then incorporated into the universal joint. There is. In the case of post-processing, the lubricant may leak during processing. In this case, it is necessary to ensure a predetermined amount of lubricant by post-impregnation.
These methods require a jig such as a molding die, and require post-processing such as grinding, post-impregnation, and incorporation. In addition, even if the cured foam is added by post-impregnation with a lubricant, problems such as low lubricant retention and easy leakage of the lubricant from the foam during handling for incorporation into a universal joint occur. Cheap.
From the above, in the present invention, it is preferable to adopt a method in which the mixture is filled into the universal joint sub-assembly and foamed and cured in terms of quality, work and cost.

  Even if the conventional universal joint causes grease to flow out due to breakage of the boot, resulting in poor lubrication, the lubricant is gradually released in the universal joint of the present invention. It also serves as a seal against intrusion of dust and moisture from the outside.

  In the universal joint of the present invention, the lubricating component contained in the foamed lubricant is not exuded suddenly even when the foam is deformed by an external force, and the lubricating component is efficiently exuded on the sliding surface. Can be used. As a result, it is possible to obtain a universal joint that requires a minimum amount of lubricating components, has a long life, and has little deterioration in rubber boots. For this reason, the universal joint of the present invention can be used for various industrial universal joints, preferably for automobile universal joints, and particularly preferably for automobile constant velocity joints.

Examples 1 to 4 and Comparative Example 2
At a blending ratio shown in Table 1, urethane prepolymer, foam stabilizer, lubricating oil and grease were mixed well at 80 ° C, and then a hardener dissolved at 120 ° C was added and mixed quickly. Finally, after adding a foaming agent and an amine catalyst and stirring, the fixed eight ball joint subassembly (NTN Corporation) shown in FIG. 1 in which the outer member 2, the inner member 3, the cage 7 and the torque transmission member 6 are assembled. 17.0 g was sealed in an EBJ82 outer diameter size of 72.6 mm). After a few seconds, the foaming reaction started. After standing for 30 minutes at 100 ° C. and foaming and curing, other members such as boots and shafts were assembled to obtain a constant velocity joint for testing in which a foaming lubricant was enclosed. Using this constant velocity joint for testing, the actual machine durability test shown below was performed, and the durability in the actual machine was evaluated. The results are also shown in Table 1. Further, the open cell ratio of the foamed lubricant was measured based on the above-described method for calculating the open cell ratio. The results are also shown in Table 1.

Comparative Example 1
A test constant velocity joint was obtained in the same manner as in Example 1 except that foaming / curing was performed without using the lubricating oil, followed by post-impregnation with the lubricating oil. Using this constant velocity joint for testing, the actual machine durability test shown below was performed, and the durability in the actual machine was evaluated. The results are also shown in Table 1.

<Real machine durability test>
The test constant velocity joint was subjected to an actual machine durability test under the conditions of a torque load of 186 N · m, a rotational speed of 1700 rpm, an angle of 6 deg and an operating time of 300 hours. After the test, the inside of the constant velocity joint for inspection was inspected, and “○” was marked as “Yes” for those that could continue operation, and “X” was marked as “No” for those that were severely damaged and could not be continued. In addition, when the surface temperature of the outer member exceeded 100 ° C. during the test, abnormal temperature rise was not allowed, and the time exceeding 100 ° C. is also shown in Table 1.

  Examples 1 to 4 showed good results in an endurance test using an actual machine. In Comparative Example 1, since the lubricant was impregnated after the foam was formed (post-impregnation), the lubricant retention force was small, and the lubricant was not on the joint (the boot side) during the constant velocity joint operation (during rotation). I moved. As a result, it is considered that the lubrication was insufficient because the amount of lubricant was insufficient in the portion requiring lubrication, and the temperature was increased. In Comparative Example 2, since the open cell ratio was small, it was considered that the release of the lubricating component gradually became smaller, resulting in poor lubrication and causing a temperature rise.

  The universal joint of the present invention can efficiently exude a lubricating component, and the amount of the lubricating component may be the minimum necessary, and can maintain the lubricity for a long period of time. Therefore, the stranded wire machine, the electric device, the printing machine, and the automobile It can be suitably used as a universal joint for various industrial machines such as parts, electrical equipment, and construction machines, particularly as a constant velocity joint for automobiles.

It is sectional drawing of the constant velocity joint which concerns on one Example of this invention. It is sectional drawing of the constant velocity joint which concerns on the other Example of this invention. It is sectional drawing of the constant velocity joint which concerns on the other Example of this invention.

Explanation of symbols

1, 11, 21 Constant velocity joint 2, 12, 22 Outer member 3, 13 Inner member 4, 5, 14, 15, 23 Track groove 6, 16 Torque transmission member (ball)
7, 17 Cage 7a, 17a Spherical surface 7b, 17b Spherical surface 8, 18, 28 Shaft 9, 19, 29 Boots 10, 20, 30 Foamed lubricant 24 Tripod member 25 Leg shaft 26 Torque transmission member (spherical roller)
27 Needle

Claims (6)

Rotational torque is transmitted by the engagement between the track groove and the torque transmission member, and the torque transmission member rolls along the track groove to move in the axial direction. Foaming lubricant is formed around the torque transmission member. An enclosed universal joint,
The foamed lubricant is formed by foaming and curing a mixture containing a lubricating component, a urethane prepolymer having an isocyanate group in the molecule, a curing agent, and a foaming agent.
The foaming agent is a foaming agent that generates gas to foam,
The universal joint, wherein a blending ratio of the lubricating component is 1% by weight to 90% by weight with respect to the entire mixture.   The universal joint according to claim 1, wherein the curing agent is an aromatic polyamine compound, and the foaming agent is water.   The universal joint according to claim 1, wherein the mixture is filled around a torque transmission member before foaming and curing is completed.   The universal joint according to claim 1, 2 or 3, wherein the foamed lubricant has an open cell ratio of 50% or more.   The universal joint according to any one of claims 1 to 4, wherein the universal joint is a constant velocity universal joint. A method for manufacturing a universal joint according to any one of claims 1 to 5,
A mixing step of obtaining a mixture by mixing a lubricating component, a urethane prepolymer having an isocyanate group in the molecule, a curing agent, and a foaming agent that generates gas and foams ;
A filling step of filling the mixture around the torque transmission member before foaming / curing of the mixture is completed;
A method for producing a universal joint, comprising: a foaming / curing step of foaming / curing the filled mixture.

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