JP2007063423A - Grease composition, rolling bearing for wind power generator, rolling bearing for construction machine and rolling bearing for steel rolling machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grease composition suppressing occurrence of white structure release and corrosion and capable of keeping good lubrication for a long time when water is mixed therein and each rolling bearing for wind power generator, for construction machine and for steel rolling machine enclosing the grease composition and excellent in water resistance. <P>SOLUTION: The grease composition comprises: a base oil composed of at least one kind of lubricating oil selected from a mineral oil; a synthetic oil having 70-250 mm<SP>2</SP>/s kinematic viscosity at 40°C; and a thickener, and further comprises at least one kind of additive selected from a carboxylic acid-based rustproof additive, a carboxylic acid salt-based rustproof additive and an ester-based rustproof additive in a ratio of 0.1-20 mass% based on the grease total amount. Each rolling bearing for wind power generator, for construction machine and for steel rolling machine is obtained by each enclosing the grease composition. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a water-resistant grease composition that exhibits excellent lubricating performance even when water is mixed therein. The present invention also relates to a rolling bearing that is incorporated in a wind power generator, a construction machine, or a steel rolling mill that has many opportunities to come into contact with water and exhibits an excellent lubrication life even when water is mixed.

  Since wind power generators and construction machinery are installed outdoors or used outdoors, they are exposed to rainfall and snowfall, and steel rolling mills are injected with rolling water. In many cases, water is mixed in and poor lubrication is induced. Regarding the influence of moisture on such grease, for example, Furumura et al., When 6% moisture is mixed in lubricating oil (# 180 turbine oil), the rolling fatigue life is reduced to a fraction of 20 to 20% compared to the case where it is not mixed. It has been reported that it decreases to a factor of 1 (Saburo Furumura, Shinichi Shirota, Kiyoshi Hirakawa: NSK Bearing Journal, No.636, pp.1-10, 1977) . Schatzberg et al. Also reported that the rolling strength of steel decreased by 32 to 48% with only 100 ppm of water in the lubricating oil (P. Schtzberg, IMFelsen: Effects of water and oxygen during rolling contact lubrication, Wear 12, pp.331-342, 1968).

  Such a decrease in life is considered that hydrogen generated from mixed water acts on the bearing material and causes metal peeling called white tissue peeling. In order to prevent such peeling, grease added with a passive oxidizing agent such as sodium nitrite (for example, see Patent Document 1), grease added with an organic antimony compound or an organic molybdenum compound (for example, see Patent Document 2), Improvement of grease has been performed, such as grease added with an inorganic compound having a particle size of 2 μm or less (see, for example, Patent Document 3). These prevent the hydrogen from entering the bearing material by forming a film derived from the additive at the rolling contact portion, but rolling of the rolling element occurs due to vibration or speed change until the film is formed. Then, metal peeling may occur at the rolling contact portion.

  As measures other than the improvement of grease, use of stainless steel as a bearing material (for example, refer to Patent Document 4), making a rolling element made of ceramics (for example, refer to Patent Document 5), etc. have been proposed. Bearings made of these materials are generally expensive.

  In addition, iron such as bearing steel has a problem that corrosion (rust) is easily caused by water and abnormal noise is generated from the bearing. In bearings where water can be mixed, it is very important to have corrosion resistance, and corrosion resistance is simultaneously imparted by the same method as described above, but it has the effect of suppressing the occurrence of rust. Not enough.

Japanese Patent No. 2878749 Japanese Patent No. 3512183 Japanese Patent Laid-Open No. 9-169989 JP-A-3-183747 JP-A-4-244624

  The present invention has been made in view of such a situation, and even when moisture is mixed, a grease composition capable of suppressing the occurrence of white structure peeling and corrosion and maintaining good lubrication for a long time. The purpose is to provide. Another object of the present invention is to provide rolling bearings for wind power generators, construction machines or steel rolling mills which are filled with such a grease composition and have excellent water resistance.

In order to achieve the above object, the present invention provides the following grease composition and rolling bearings for wind power generators, construction machines or steel rolling mills.
(1) It comprises at least one lubricating oil selected from mineral oils and synthetic oils, includes a base oil having a kinematic viscosity at 40 ° C. of 70 to 250 mm ² / s, a thickener, and a carboxylic acid-based antibacterial agent. A grease composition comprising at least one selected from a rust additive, a carboxylate-based rust preventive additive, and an ester-based rust preventive additive in a proportion of 0.1 to 20% by mass of the total amount of grease.
(2) A rolling bearing incorporated in a wind power generator, wherein a plurality of rolling elements are rotatably disposed between an inner ring and an outer ring, and the rolling element is formed between the inner ring and the outer ring. A rolling bearing for a wind power generator, wherein the grease composition according to claim 1 is enclosed in a space in which is disposed.
(3) A rolling bearing incorporated in a construction machine, wherein a plurality of rolling elements are rotatably disposed between an inner ring and an outer ring, and the rolling element is formed between the inner ring and the outer ring. A rolling bearing for construction machinery, wherein the grease composition according to claim 1 is sealed in the space provided.
(4) A rolling bearing incorporated in a steel rolling mill, wherein a plurality of rolling elements are movably disposed between an inner ring and an outer ring, and are formed between the inner ring and the outer ring. A rolling bearing for a steel rolling mill, wherein the grease composition according to claim 1 is enclosed in a space in which a moving body is disposed.

  The grease composition of the present invention maintains good lubricity by using a base oil having a specific kinematic viscosity, and also uses a carboxylate-based rust preventive additive and an ester-based rust preventive additive as a rust preventive additive. It exhibits excellent corrosion resistance and resistance to white tissue peeling.

  In addition, the rolling bearings for wind power generators, construction machines or steel rolling mills of the present invention show excellent lubrication life even when moisture is mixed by enclosing such a grease composition.

  Hereinafter, the present invention will be described in detail.

In the grease composition of the present invention, the base oil is selected from mineral oil and synthetic oil, and the kinematic viscosity at 40 ° C. is 70 to 250 mm ² / s. By setting the kinematic viscosity within the above range, it is possible to eliminate problems such as the generation of abnormal noise at low temperature startup and the loss of oil film at high temperatures. In order to ensure such an effect, the kinematic viscosity at 40 ° C. is preferably 120 to 185 mm ² / s.

  Mineral oil can be used that is purified by appropriately combining vacuum distillation, oil removal, solvent extraction, hydrocracking, solvent dewaxing, sulfuric acid washing, white clay purification, hydrorefining, and the like.

Synthetic oils include hydrocarbon oils, aromatic base oils, ester oils, ether oils, and the like. Examples of the hydrocarbon oil include normal paraffin, isoparaffin, polybutene, polyisobutylene, 1-decene oligomer, poly-α-olefin such as 1-decene and ethylene co-oligomer, and hydrides thereof. Examples of the aromatic oil include alkylbenzenes such as monoalkylbenzene and dialkylbenzene, and alkylnaphthalenes such as monoalkylnaphthalene, dialkylnaphthalene and polyalkylnaphthalene. Examples of ester oils include dibutyl sebacate, di-2-ethylhexyl sebacate, dioctyl adipate, diisodecyl adipate, ditridecyl adipate, ditridecyl glutarate, and methyl acetyl cinnolate, or trioctyl trimellitate. Aromatic ester oils such as tridecyl trimellitate and tetraoctyl pyromellitate, and further trimethylolpropane caprylate, trimethylolpropane verargonate, pentaerythritol-2-ethylhexanoate, pentaerythritol verargonate, etc. Polyol ester oils, and complex ester oils that are oligoesters of polyhydric alcohols and mixed fatty acids of dibasic acids and monobasic acids are also exemplified. Examples of ether oils include polyglycols such as polyethylene glycol, polypropylene glycol, polyethylene glycol monoether, and polypropylene glycol monoether, or monoalkyl triphenyl ether, alkyl diphenyl ether, dialkyl diphenyl ether, pentaphenyl ether, tetraphenyl ether, monoalkyl tetra And phenyl ether oils such as phenyl ether and dialkyl tetraphenyl ether. These lubricating oils can be used alone or as a mixture, and are adjusted to the above-mentioned preferable kinematic viscosity. Among them, a base oil using an ester oil having a kinematic viscosity at 40 ° C. of 120 to 185 mm ² / s alone is preferable. .

  As the thickener, both organic and inorganic thickeners can be used, but those that do not contain heavy metals are preferable in consideration of the influence on the environment. Specifically, metal soaps such as lithium soap, calcium soap, aluminum soap, magnesium soap, sodium soap, or composite soaps thereof, urea compounds, bentonite, silica, carbon black, and the like can be suitably used. Of these, metal soaps and urea compounds are preferred. These may be used alone or in combination.

  The blending amount of the thickener is not limited as long as the grease can be formed and maintained with the above base oil, but is preferably 5 to 35 mass%, more preferably 5 to 25 mass% of the total amount of grease. In the case of mixed use, the total amount is within this range.

  In this invention, at least 1 sort (s) chosen from a carboxylic acid type rust preventive additive, a carboxylate type | system | group anticorrosive additive, and an ester type rust preventive additive is added. The addition amount is 0.1 to 20% by mass based on the total amount of grease in both cases of single use and mixed use. When the addition amount is less than 0.1% by mass, the effect of suppressing white structure peeling and corrosion cannot be sufficiently obtained. On the other hand, when the addition amount exceeds 20% by mass, the adhesion amount of the rust preventive agent on the surface of the bearing member is excessively increased, and the formation of an oxide film or the like derived from the grease composition of the present invention is hindered to cause white tissue peeling. It may occur. When the antirust performance is ensured and white structure peeling is taken into consideration, the addition amount is preferably 0.25 to 15% by mass with respect to the total amount of grease.

  Examples of the carboxylic acid-based antirust agent include monocarboxylic acids, linear fatty acids such as lauric acid and stearic acid, and saturated carboxylic acids having a naphthene nucleus. Dicarboxylic acids include succinic acid derivatives such as succinic acid, alkyl succinic acid, alkyl succinic acid half ester, alkenyl succinic acid, alkenyl succinic acid half ester, succinimide, hydroxy fatty acid, mercapto fatty acid, sarcosine derivative, and wax or Examples thereof include an oxidized wax such as an oxide of petrolatum.

  Examples of carboxylate-based anticorrosive additives include fatty acid, naphthenic acid, abietic acid, lanolin fatty acid, alkenyl succinic acid, and metal salts of amino acid derivatives. Metal elements include cobalt, manganese, zinc, and aluminum. , Calcium, barium, lithium, magnesium, copper and the like.

  Examples of ester-based rust preventive additives include partial esters of polyhydric alcohols such as sorbitol, pentaerythritol, sucrose, and glycerin with carboxylic acids such as oleic acid and lauric acid, and higher grades such as oleyl alcohol, stearyl alcohol, and lauryl alcohol. Fatty acid alcohol etc. are mentioned.

  In order to suppress the occurrence of white tissue peeling, it becomes more effective if it becomes easier to form an oxide film at the rolling contact portion in addition to the action of the rust preventive additive. Therefore, the grease composition includes dialkyldithiocarbamic acid compounds represented by the following general formula (1), dialkyldithiophosphate compounds represented by the general formula (2), and general formulas (3) to (5). It is preferable to add at least one organic metal salt selected from an organic zinc compound represented by the formula and a zinc alkylxanthate represented by the general formula (6).

In the general formulas (1) and (2), M represents a metal species, and specifically can be selected from Sb, Bi, Sn, Ni, Te, Se, Fe, Cu, Mo, and Zn. R ₁ and R ₂ may be the same group or different groups, and are selected from an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an alkylaryl group, and an arylalkyl group. Particularly preferred groups as R ₁ and R ₂ include 1,1,3,3-tetramethylbutyl group, 1,1,3,3-tetramethylhexyl group, 1,1,3-trimethylhexyl group, 1, 3-dimethylbutyl group, 1-methylundecane group, 1-methylhexyl group, 1-methylpentyl group, 2-ethylbutyl group, 2-ethylhexyl group, 2-methylcyclohexyl group, 3-heptyl group, 4-methylcyclohexyl group N-butyl group, isobutyl group, isopropyl group, isoheptyl group, isopentyl group, undecyl group, eicosyl group, ethyl group, octadecyl group, octyl group, cyclooctyl group, cyclododecyl group, cyclopentyl group, dimethylcyclohexyl group, decyl group Tetradecyl group, docosyl group, dodecyl group, tridecyl group, trimethylcyclohexane Sil group, nonyl group, propyl group, hexadecyl group, hexyl group, henicosyl group, heptadecyl group, heptyl group, pentadecyl group, pentyl group, methyl group, tert-butylcyclohexyl group, tert-butyl group, 2-hexenyl group, 2 -Methallyl group, allyl group, undecenyl group, oleyl group, decenyl group, vinyl group, butenyl group, hexenyl group, heptadecenyl group, tolyl group, ethylphenyl group, isopropylphenyl group, tert-butylphenyl group, second pentylphenyl group N-hexylphenyl group, tertiary octylphenyl group, isononylphenyl group, n-dodecylphenyl group, phenyl group, benzyl group, 1-phenylmethyl group, 2-phenylethyl group, 3-phenylpropyl group, 1, 1-dimethylbenzyl group, 2-phenylisopropyl group, 3-phenyl Niruhekishiru group, benzhydryl group, there is a biphenyl group and the like, and these groups may have an ether group.

In the general formulas (3) to (5), R ₃ and R ₄ may be the same group or different groups, and are selected from a hydrocarbon group having 1 to 18 carbon atoms and a hydrogen atom. In particular, R ₃ and R ₄ are both hydrogen atoms, mercaptobenzothiazole zinc (general formula (3)), benzoamidothiophenol zinc (general formula (4)), mercaptobenzimidazole zinc (general formula (5)). Can be preferably used.

In the general formula (6), _{R 5} is a hydrocarbon group having 1 to 18 carbon atoms.

  The amount of the above-mentioned organometallic salt added is 0.1 to 20% by mass based on the total amount of grease for both single use and mixed use. When the addition amount of the organic metal salt is less than 0.1% by mass, there is no effect in promoting the formation of an oxide film, and when it exceeds 20% by mass, an improvement in the effect corresponding to the increment cannot be obtained, and oxidation with the bearing material is not achieved. The reaction may be accelerated abnormally to cause corrosion and abnormal wear. The amount of the organic metal salt added is particularly preferably in the range of 0.5 to 10% by mass.

  Furthermore, you may add the other additive conventionally added to the grease composition to a grease composition as needed.

  The present invention also relates to rolling bearings for wind power generators, construction machines or steel rolling mills formed by sealing the above grease composition.

  FIG. 1 is a partial sectional view showing an example of a wind power generator. The illustrated wind power generator 1 is connected to a rotor blade 10 and a transmission 12 attached to a rotor shunt 11 of the rotor blade 10. A generator 17 to be driven and a tower 13 for holding the low tab plate 10, the transmission 12, the generator 17 and the like at a predetermined height are provided. Then, the rotor blade 10 receives wind and rotates to drive the generator 17 and take it out as electric energy. The rotor shaft 11 is often mounted with a unit bearing 14 such as a self-aligning roller bearing or a tapered roller bearing. In the present invention, the above grease composition is enclosed in these unit bearings 14.

  FIG. 2 is a side view showing an overall image of a hydraulic excavator which is a kind of self-propelled construction machine. The illustrated hydraulic excavator is configured such that an upper swing body 23 including a cab 24 is rotatably mounted on a lower traveling body 21 via a swing bearing 29. The slewing bearing 29 includes an inner ring that has an inner gear that meshes with a drive pinion on the upper slewing body side, is fixed to the lower traveling body 21 side, and an outer ring that is fixed to the upper slewing body side across the inner ring. A large number of spherical rolling elements are accommodated in an annular rolling element accommodation space formed between the outer ring and the outer ring so as to be rotatably supported by the inner ring. In the present invention, the grease composition is enclosed in the rolling element housing space. Reference numeral 22 denotes a revolving frame, 25 a building cover, 26 a counterweight, 27 an excavator working device, and 28 a revolving device.

  Moreover, FIG. 3 is sectional drawing which shows an example of the roll neck bearing for rolling mills used for a steel rolling mill. The illustrated roll neck bearing for a rolling mill is configured by arranging a pair of bearings including a double row inner ring 30 and two single row outer rings 31 arranged via a spacer 32 via a spacer 33. A total of four rows of rolling elements 34 are arranged between the double row inner ring 30 and the single row outer ring 31 so as to be rollable in the circumferential direction by a cage 35. A seal member 36 is mounted on the outer end of each bearing in a state where the seal lip portion is in contact with the outer peripheral surface of the double-row inner ring 30 and the inner periphery of the butt end of the two double-row inner rings 30. An intermediate seal is mounted on the side. Also, by forming a slit for venting machine in the intermediate seal member, even if the air inside the bearing expands and contracts due to temperature change, water balances using the pressure difference inside and outside the bearing and water enters the inside of the bearing. It is devised not to. In the present invention, the above grease composition is enclosed in a bearing space formed by the double row inner ring 30, the single row outer ring 31, the rolling elements 34 and the seal member 36.

  Since wind power generators, construction machines, and steel rolling mills have many opportunities to come into contact with water, water easily enters the rolling bearings incorporated therein. However, since the above grease composition contains a specific anti-rust additive, the rolling bearings for wind power generators, construction machines or steel rolling mills of the present invention are effective in corrosion even if moisture is mixed. Therefore, the white tissue peeling can be effectively suppressed and the life is prolonged.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is further demonstrated, this invention is not restrict | limited at all by this.

(Examples 1-4, Comparative Examples 1-2)
The test grease prepared with the formulation shown in Table 1 was enclosed in a tapered roller bearing “HR30205 (inner diameter 25 mm, outer diameter 52 mm, width 16.25 mm)” manufactured by NSK Ltd. to produce a test bearing. And after inject | pouring water into this test bearing so that it might become 1 mass% with respect to the sealing grease whole quantity, it was continuously rotated for 100 hours at 120 degreeC, radial load 98N, axial load 1470N, and rotational speed 3500rpm. After rotation, the test bearing was disassembled, and the presence or absence of rust and peeling was visually observed. The results are shown in Table 1.

  As shown in Table 1, according to the present invention, at least one selected from a carboxylic acid-based rust preventive additive, a carboxylate-based rust preventive additive and an ester-based rust preventive additive is 0.1 to 20% by mass of the total amount of grease. It can be seen that by encapsulating the grease composition of each example contained in the ratio, the anti-rust performance and anti-peeling effect are extremely good and a long-life rolling bearing is obtained.

It is a partial sectional view showing an example of a wind power generator. It is a side view which shows the whole image of the hydraulic shovel which is an example of a construction machine. It is sectional drawing which shows an example of the roll neck bearing for rolling mills used for a steel rolling mill.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wind generator 10 Rotor blade 11 Rotor shout 12 Transmission 13 Tower 14 Unit bearing 17 Generator 21 Lower traveling body 22 Turning frame 23 Upper turning body 24 Driver's cab 25 Building cover 26 Counterweight 27 Working device 28 of excavator Device 29 Slewing bearing 30 Double row inner ring 31 Single row outer ring 32 Spacer 33 Spacer 34 Rolling element 35 Cage 36 Seal member

Claims (4)

A carboxylic acid anticorrosive additive comprising a base oil having a kinematic viscosity at 40 ° C. of 70 to 250 mm ² / s and a thickener, comprising at least one lubricating oil selected from mineral oil and synthetic oil A grease composition comprising at least one selected from carboxylate-based rust preventive additives and ester-based rust preventive additives in a proportion of 0.1 to 20% by mass of the total amount of grease.   A rolling bearing incorporated in a wind power generator, wherein a plurality of rolling elements are rotatably disposed between an inner ring and an outer ring, and the rolling elements are formed between the inner ring and the outer ring. A rolling bearing for a wind power generator, wherein the grease composition according to claim 1 is enclosed in the formed space.   A rolling bearing incorporated in a construction machine, wherein a plurality of rolling elements are rotatably disposed between an inner ring and an outer ring, and the rolling elements are formed between the inner ring and the outer ring. A rolling bearing for construction machinery, wherein the grease composition according to claim 1 is enclosed in the space.   A rolling bearing incorporated in a steel rolling mill, wherein a plurality of rolling elements are rotatably arranged between an inner ring and an outer ring, and the rolling elements are formed between the inner ring and the outer ring. A rolling bearing for a steel rolling mill, wherein the grease composition according to claim 1 is enclosed in a space provided.

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