JP2008285574A - Roller bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a roller bearing subject to operation under extreme pressures, enhanced in lubricating performance and further enhanced in abrasion resistance and torque reduction. <P>SOLUTION: The roller bearing is characterized by rollably holding multiple rollers via a holder in between an inner ring and an outer ring and being sealed with a lubricant composition where an ester oil is compounded with a specific urea compound and a benzylidene sorbitol derivative in the weight ratio (the benzylidene sorbitol derivative/the urea compound) of 0.1-1.0 so as to be 10-30 mass% in the total amount of the urea compound and the benzylidene sorbitol derivative. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to roller bearings incorporated in steel equipment, vehicles, various industrial machines, various motors and the like.

  Grease and lubricating oil are used for roller bearings incorporated in the above-mentioned facilities, machines, and devices in order to impart lubricity. Among them, grease has an advantage that it can be enclosed in a bearing and is widely used. On the other hand, the flow characteristics are poor compared to the lubricating oil, and the ability to supply the transfer surface required inside the bearing is poor. In particular, roller bearings used in railway equipment, vehicles, and industrial machinery are subject to extreme pressure conditions, so it is difficult for grease to enter the rolling surface and cause wear due to poor lubrication. is there.

  From such a background, an extreme pressure agent such as a sulfur compound is often added to grease sealed in roller bearings used in railway facilities, vehicles, and industrial machines to prevent wear (for example, patents). Reference 1). However, highly active extreme pressure agents can break the grease network and soften it, or conversely increase wear.

  Moreover, when an additive having high reactivity with a metal is added, there is a concern that a corrosive action may be exhibited in some cases such as a wet environment.

JP 2004-332768 A

  The equipment, machines, and equipment listed above are expected to have higher demands for higher performance in the future. However, in addition to the wear resistance of the roller bearings built in, lower torque is required for higher speeds. The demand is getting stricter year by year.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the lubrication performance of a roller bearing that is excellent in lubrication performance and is operated under the extreme pressure conditions as described above, and to further improve wear resistance and torque reduction.

  In order to solve the above-mentioned problems, the present invention comprises a plurality of rollers that are movably held between a inner ring and an outer ring via a cage, and the following general formula (1) or (2 ) And a benzylidene sorbitol derivative, the weight ratio of (benzylidene sorbitol derivative / urea compound) is 0.1 to 1.0, and the total amount of the urea compound and the benzylidene sorbitol derivative is 10 to 10. Provided is a roller bearing in which a lubricant composition blended so as to be 30% by mass is enclosed.

[(1) _where, C _{m H 2m + 1} and _C n _{H 2n + 1} is a straight-chain alkyl group, m + n is 16-36. Further, in _(2), C _{x H 2x + 1} and _C y _{H 2y + 1} is a linear alkyl group, x + y is 20 to 36. ]

  In the roller bearing of the present invention, the encapsulated lubricant composition becomes oily (having no yield value) when a shearing force is applied, and becomes solid and gelled (when the yielding value is large) when no shearing force is applied. . For this reason, even if the lubricant composition is discharged from the transfer surface, it becomes oily due to the extremely weak shear force generated by the contact between the gap between the cage and the seal and the grease existing near the transfer surface, and is supplied again to the transfer surface. Even under extreme pressure conditions, wear due to insufficient lubrication is suppressed, resulting in a longer life and lowering of torque.

  Hereinafter, the present invention will be described in detail.

  In the present invention, the structure of the roller bearing is not limited, and for example, the roller bearing shown in FIG. 1 can be exemplified. In the illustrated roller bearing, a roller 3 is disposed between an inner ring 1 and an outer ring 2 via a cage 4. The roller 3 receives rolling friction between the rolling surface 1 a of the inner ring 1 and the rolling surface 2 a of the outer ring 2, and receives sliding friction with the flange 1 b of the inner ring 1. In order to reduce these frictions, the grease composition shown below is enclosed.

  The grease composition is obtained by blending a urea compound represented by the following general formula (1) or (2) and a benzylidene sorbitol derivative in ester oil.

In the formula (1), C _m H _{2m + 1} and C _n H _{2n + 1} are linear alkyl groups, and m + n is 16 to 36. Further, in _(2), C _{x H 2x + 1} and _C y _{H 2y + 1} is a linear alkyl group, x + y is 20 to 36.

  The ester oil is not limited, but is obtained from the reaction of an aromatic tribasic acid or aromatic tetrabasic acid with a branched alcohol and a reaction of a monobasic acid with a polyhydric alcohol. Preferred examples include polyol ester oils.

  Specifically, as the aromatic ester oil, pyromellitic acid ester oil, trimesic acid ester oil, specifically trioctyl trimellitate as ester oil obtained from the reaction of aromatic tribasic acid and branched alcohol. And tridecyl trimellitate, pyromellitic ester oil obtained from a reaction of an aromatic tetrabasic acid and a branched alcohol, specifically tetraoctyl pyromellitate, and the like.

  Moreover, as a polyol ester oil, what is obtained by making the polyhydric alcohol and monobasic acid shown below react suitably is mentioned. In addition, a monobasic acid may be individual and multiple may be used. Furthermore, you may use as complex ester which is an oligoester of a polyhydric alcohol and the mixed fatty acid of a dibasic acid and a monobasic acid. Examples of the polyhydric alcohol include trimethylolpropane, pentaerythritol, dipentaerythritol, neopentyl glycol, 2-methyl-2-propyl-1,3-propanediol and the like. On the other hand, monobasic acids are mainly monohydric fatty acids having 4 to 16 carbon atoms, specifically, butyric acid, valeric acid, caproic acid, caprylic acid, enanthic acid, pelargonic acid, capric acid, undecanoic acid. , Lauric acid, mysteric acid, palmitic acid, beef tallow fatty acid, stearic acid, caproleic acid, palmitoleic acid, petrothelic acid, oleic acid, elaidic acid, asclepic acid, vaccenic acid, sorbic acid, linoleic acid, linoic acid, abinic acid, ricinol An acid etc. are mentioned.

The urea compound is obtained by reacting diisocyanate with a monoamine. As the diisocyanate, hexamethylene diisocyanate is used in the urea compound represented by the general formula (1), and 4,4′-diphenylmethane diisocyanate is used in the urea compound represented by the general formula (2). On the other hand, as the monoamine, the urea compound represented by the general formula (1) uses an aliphatic amine having linear C _m H _{2m + 1} and an aliphatic amine having linear C _n H _{2n + 1.} In the urea compound represented by), an aliphatic amine having linear C _x H _{2x + 1} and an aliphatic amine having linear C _y H _{2y + 1} are used. In addition, although m + n is 16-36 and x + y is 20-36, the affinity with ester oil is so high that carbon number is large, and preferable.

  Preferred examples of the benzylidene sorbitol derivative include dibenzylidene sorbitol, ditrilidene sorbitol, asymmetric dialkyl benzylidene sorbitol, and the like.

  The benzylidene sorbitol derivative is obtained by adding NLGI No. 2-No. It has the ability to increase to about 3 hardness. Further, it has fluidity-reversibility reversibility, in which crystal particles are dispersed to exhibit fluidity when subjected to shearing, and crystal particles aggregate and no longer exhibit fluidity when not subjected to shearing. However, as the presence or absence of shearing is repeated, the structural restoration in a short time becomes difficult and softens. Therefore, by using a urea compound that has a moderate flow-reversibility reversibility, the benzylidene sorbitol fluid crystal particles crosslink the urea compound crystal particles and easily re-aggregate, so that stable fluid-restoration reversibility is achieved. Can be obtained.

  In order to effectively obtain such an action, a urea compound and a benzylidene sorbitol derivative are mixed and used at a weight ratio of (benzylidene sorbitol derivative / urea compound) of 0.1 to 1.0. When the mixing ratio is less than 0.1, the benzylidene sorbitol derivative crystal particles are less likely to agglomerate, and the restoration of the thickener network structure is delayed when not subjected to shearing, and leakage from the application site is likely. On the other hand, when the mixing ratio exceeds 1, the reversibility of dispersion / aggregation is impaired and leakage tends to occur.

  Both urea compounds and benzylidene sorbitol derivatives function as thickeners. Therefore, it mix | blends so that 10-30 mass% of the lubricant composition whole quantity may occupy in total of both. When the total blending amount is less than 10% by mass, the lubricant composition is too soft from the beginning and easily leaks from the application site, the fluidity exceeding 30% by mass is low, and sufficient lubricity cannot be imparted to the application site.

  Both urea compounds and benzylidene sorbitol derivatives have high affinity with ester oils, and when heated to a predetermined temperature, they can be completely dissolved in ester oils, and each crystal particle can be uniformly formed in ester oils. As a result, the nucleation state can be controlled by the cooling method. In addition, crystal grains having a small particle size can be generated, and when the rolling bearing for rocking motion is filled, the bearing acoustic characteristics are excellent.

  Various performances can be improved by adding an additive to the grease composition according to its use, but it is preferable to add an extreme pressure additive. As the extreme pressure additive, phosphorus-based, sulfur-based, phosphorus-sulfur-based, zinc dithiophosphate, molybdenum dithiophosphate, and the like are preferable, and each is added alone or in appropriate combination.

  Furthermore, antioxidants such as amine-based, phenol-based, sulfur-based, zinc dithiophosphate and zinc dithiocarbamate; rust preventives such as sulfonic acid metal salts, ester-based, amine-based, naphthenic acid metal salts and succinic acid derivatives; Oiliness improvers such as fatty acids and animal and vegetable oils; metal deactivators such as benzotriazole and the like can be added alone or in appropriate combination.

  In addition, the addition amount of these additives will not be restrict | limited especially if it is a range which does not impair the objective of this invention.

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

Example 1
In a first container, 4 parts of hexamethylene diisocyanate (HDI) was added and dissolved in 42 parts of pentaerythritol ester (PET) and heated to 70 ° C. In a second container, 6 parts of octylamine (C ₈ NH ₂ ) was dissolved in 45 parts of PET. And the content of the 2nd container was put into the 1st container, and it heated up gradually, stirring, and hold | maintained at 140 degreeC for 30 minutes, and synthesize | combined the urea compound. Next, 3 parts of dibenzylidene sorbitol (DBS) was added to the first container, and after sufficiently stirring and mixing, the temperature was raised to 195 ° C. to completely dissolve the urea compound and DBS. Next, the contents of the first container were poured into an aluminum bat that had been previously water-cooled, and the bat was cooled with running water to obtain a gel-like material. Then, a gel lubricant was put on a three-roll mill to obtain a test lubricant composition.

(Example 2)
Using octadecylamine (C ₁₈ HN ₂ ) instead of octylamine, a urea compound was synthesized according to Example 1, and DBS and molybdenum dithiophosphate (MoDTP) were added to obtain a test lubricant composition.

(Examples 3 to 6)
Using the base oil, diisocyanate, monoamine, benzylidene sorbitol derivative and extreme pressure additive shown in Table 1, a test lubricant composition was obtained according to Example 1 or Example 2.

(Comparative Example 1)
In PET, 4,4′-diphenylmethane diisocyanate (MDI) and cyclohexylamine (CHA) were reacted to synthesize a urea compound, and MoDPT was further added to obtain a test lubricant composition.

(Comparative Example 2)
DBS was added to PET to obtain a test lubricant composition.

(Comparative Example 3)
A test lubricant composition was obtained by blending lithium hydroxystearate with mineral oil (MO) and further adding a sulfur-based extreme pressure additive.

(1) Relationship between presence / absence of shear and apparent viscosity Using the test lubricant composition of Example 1 and the test lubricant composition of Comparative Example 1, the initial apparent viscosity (● in the figure) and shear of 1 Measure the apparent viscosity (▲ in the figure) after receiving, the apparent viscosity after receiving a shear once (■ in the figure), and the apparent viscosity after further shearing (♦ in the figure) did. FIG. 2 shows the measurement results of the test lubricant composition of Example 1. The lubricant composition of the present invention becomes oily when subjected to shear and exhibits fluidity. It turns out that it has the characteristic which returns to gel form. On the other hand, FIG. 3 shows the measurement result of the test lubricant composition of Comparative Example 1. Since only the urea compound is contained, the change in the apparent viscosity is small when subjected to shearing and when left standing.

(2) Flow-recovery reversibility test For the test lubricant compositions of Example 1, Comparative Example 1 and Comparative Example 2, rotation-revolution stirrer (shear conditions: rotation 1370 r / min, revolution 1370 r / min, 3 min) The mixture was stirred and measured for the immiscible penetration, and then it was allowed to stand at 40 ° C. for 3 hours to measure the immiscible penetration 4 times. The results are shown in Table 1 and FIG. 4, and the difference between the immiscible penetration after the first shearing and the respective immiscibility penetrations after the second to fourth shearing, and the immiscibility after the first standing. If the difference between the degree of miscibility and the respective immiscible penetrations after the second to fourth times is within ± 15, it can be regarded as having good flow-restoration reversibility. The test lubricant composition satisfies this criterion. On the other hand, the comparative lubricant compositions of Comparative Example 1 and Comparative Example 2 have a large increase in the immiscible consistency after standing and repeated flow-restoration reversibility during repeated stirring and leaving. .

(3) Bearing leak test Single-row deep groove ball bearings with a non-contact seal (inner diameter 25 mm, outer diameter 62 mm, width 17 mm) were filled with each test lubricant composition to prepare test bearings. The test bearing was continuously rotated for 20 hours at a rotational speed of 10000 r / min, an axial load of 98 N, and a radial load of 98 N, and the grease leakage rate was determined from the difference from the initial weight. The results are shown in Table 1. A grease leakage rate of 6% by mass or less is acceptable. The test bearings of the examples all satisfy the above criteria.

  In addition, according to Example 1, test lubricant compositions were prepared by changing the weight ratio of (benzylidene sorbitol derivative / urea compound), and the grease leakage rate was determined in the same manner. The results are shown in FIG. 5, and are shown as relative values with respect to the test lubricant composition having a (benzylidene sorbitol derivative / urea compound) weight ratio of 1. From the figure, it can be seen that when the weight ratio of (benzylidene sorbitol derivative / urea compound) is in the range of 0.1 to 1.0, grease leakage can be suppressed as much as possible.

(4) Abrasion resistance test Using a reciprocating wear test apparatus, the test lubricant composition was applied on a test stand to a film thickness of 1 mm, amplitude 10 mm, frequency 15 Hz, vertical load 2 GPa, test temperature 80 ° C. The test was conducted under the condition of a test time of 10 minutes, and the wear resistance was evaluated by the size of wear marks (wear mark diameter) formed in the direction perpendicular to the rocking direction. The results are shown in Table 1, and are shown as relative values with respect to the wear scar diameter of Comparative Example 3, but the test lubricant compositions of the examples are all 1 or less.

(5) Copper plate corrosion test Although the test was conducted in accordance with JIS K2220B method, all of the tested lubricant compositions in the examples are acceptable.

It is sectional drawing which shows an example of the roller bearing of this invention. 2 is a graph showing the relationship between shear stress and apparent viscosity in the test lubricant composition of Example 1. FIG. 6 is a graph showing the relationship between shear stress and apparent viscosity in the test lubricant composition of Comparative Example 1. It is a graph which shows the result of the (2) flow-restoration reversibility test in an Example. It is a graph which shows the relationship between the weight ratio obtained in the Example (benzylidene sorbitol derivative / urea compound) and the grease leakage rate.

Explanation of symbols

1 Inner ring 2 Outer ring 3 Roller

Claims (1)

A plurality of rollers are movably held through a cage between an inner ring and an outer ring, and a urea compound represented by the following general formula (1) or (2) and a benzylidene sorbitol derivative are added to the ester oil. And (benzylidene sorbitol derivative / urea compound) in a weight ratio of 0.1 to 1.0, and a lubricant composition in which the total amount of the urea compound and the benzylidene sorbitol derivative is 10 to 30% by mass. A roller bearing characterized by enclosing an object.

[(1) _where, C _{m H 2m + 1} and _C n _{H 2n + 1} is a straight-chain alkyl group, m + n is 16-36. Further, in _(2), C _{x H 2x + 1} and _C y _{H 2y + 1} is a linear alkyl group, x + y is 20 to 36. ]

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