JP2006089533A - Rolling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling device seldom developing white texture peeling and long in service life even if used under the conditions of high temperature, high speed and heavy load and also under such conditions that water tends to intrude thereinto. <P>SOLUTION: The rolling device is a deep-grooved ball bearing, comprising an inner ring 1 having a track face 1a on the outer circumferential surface, an outer ring 2 having a track face 2a against the track face 1a on the inner circumferential surface, a plurality of rollers 3 arranged rollably in between both the track faces 1a and 2a, a holder 4 holding the plurality of rollers 3 in between the inner ring 1 and the outer ring 2, and sealing elements 5 and 5 such as seals covering the opening of a gap in between the inner ring 1 and the outer ring 2. Further, in this rolling device, a grease G for lubricating the deep-grooved ball bearing is sealed in the inside of gaps among the rollers 3 formed in between the inner ring 1 and the outer ring 2. This grease G comprises a synthetic oil, an urea compound and an organosilicon compound. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rolling device such as a rolling bearing, a ball screw, a linear guide device, and a linear motion bearing.

  Rolling bearings used in automotive electrical components, automotive engine accessories (alternators, intermediate pulleys, car air conditioner electromagnetic clutches, etc.), gas heat pump electromagnetic clutches, compressors, etc. are subject to high temperature, high speed, and high load conditions. Often used in. In addition, due to recent demands for compactness and high performance, these conditions of use are becoming stricter.

  Under such severe use conditions, the grease sealed in the rolling bearing may be decomposed to generate hydrogen (see Patent Document 1). This hydrogen penetrates into the bearing steel that constitutes the inner ring, outer ring, and rolling elements and causes hydrogen embrittlement, leading to delamination accompanied by a change to white structure due to this hydrogen embrittlement (hereinafter also referred to as white structure delamination). Therefore, prevention is a new important issue.

  Further, since the rolling bearing as described above is used for an auxiliary machine of an automobile engine, it easily comes into contact with water splashed from the road surface. Although the seal prevents water from entering the inside of the bearing, it is difficult to completely prevent intrusion. In addition, when the engine is stopped, the temperature of the rolling bearing decreases and the dew point is reached, moisture in the air around the rolling bearing condenses into water droplets, which can be mixed into the grease sealed in the rolling bearing. is there. As described in Patent Document 2, there is a case where water is decomposed and hydrogen is generated, and this hydrogen causes white tissue peeling. Therefore, in a rolling bearing used for an auxiliary machine of an automobile engine, it is generated from grease. In combination with hydrogen, white tissue peeling was more likely to occur.

As countermeasures against white tissue peeling, grease is often used. For example, Patent Document 1 proposes a rolling bearing in which grease containing a passive oxidant such as sodium nitrite is enclosed, and Patent Document 3 encloses grease containing an organic antimony compound or an organic molybdenum compound. Rolling bearings have been proposed. In these rolling bearings, the coating derived from the above-mentioned compounding agent is formed at the rolling contact portion, so that hydrogen can be prevented from entering the bearing material.
Japanese Patent No. 2878749 JP-A-11-72120 Japanese Patent Publication No. 6-803565

However, since the rolling bearings described in Patent Documents 1 and 3 require some time until the coating film derived from the compounding agent is formed, the problem that hydrogen cannot be prevented from entering until the coating film is formed. Had a point. In addition, when the rolling element slips due to vibration or speed fluctuation, metal peeling may occur at the rolling contact portion and the coating derived from the compounding agent may be destroyed, so that hydrogen may enter from there. . Furthermore, since the above-mentioned compounding agent is an environmental load substance, its use is not desirable.
Therefore, the present invention solves the problems of the prior art as described above, and even when used under conditions of high temperature, high speed, high load, and in which water easily enters, white tissue peeling occurs. It is an object to provide a rolling device that is difficult and has a long life.

  In order to solve the above problems, the present invention has the following configuration. That is, the rolling device according to claim 1 of the present invention has an inner member having a raceway surface on the outer surface and a raceway surface opposite to the raceway surface of the inner member, and is disposed outward of the inner member. And a plurality of rolling elements arranged so as to be able to roll between the both raceway surfaces, and the rolling device is lubricated with grease containing a base oil, a thickener, and an additive. The base oil is a synthetic oil, the thickener is a urea compound, and the additive is an organosilicon compound.

A rolling device according to a second aspect of the present invention is the rolling device according to the first aspect, wherein the rolling device is a rolling bearing for an automobile electrical component or an automobile engine accessory.
A silicon-containing coating is formed on the raceway surface of the inner member, the raceway surface of the outer member, and the rolling surface of the rolling element by the organosilicon compound contained in the grease. Intrusion is prevented. Therefore, even if the rolling device of the present invention is used under conditions of high temperature, high speed, and high load, and in which water easily enters, the rolling device is less likely to cause white tissue peeling and has a long life.

Further, since this coating is formed very quickly, the period during which hydrogen cannot be prevented from entering because the coating is not formed is extremely short. Furthermore, since the organosilicon compound is a substance having a low impact on the environment, it can be suitably used for a wide range of applications.
The present invention can be applied to various rolling devices. For example, a rolling bearing, a ball screw, a linear guide device, a linear motion bearing, and the like.

  In the present invention, the inner member refers to an inner ring when the rolling device is a rolling bearing, a screw shaft when the ball screw is also used, a guide rail when the linear guide device is used, and a linear bearing. In the case, each means an axis. The outer member is an outer ring when the rolling device is a rolling bearing, a nut when it is a ball screw, a slider when it is a linear guide device, and an outer cylinder when it is also a linear bearing. Means each.

  Even if the rolling device of the present invention is used under conditions of high temperature, high speed, and high load, and water is likely to enter, it has a long life with little white tissue peeling.

An embodiment of a rolling device according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing a structure of a deep groove ball bearing which is an embodiment of a rolling device according to the present invention. This deep groove ball bearing has an inner ring 1 having a raceway surface 1a on the outer peripheral surface, an outer ring 2 having a raceway surface 2a facing the raceway surface 1a on the inner peripheral surface, and a raceway between the raceway surfaces 1a and 2a. A plurality of rolling elements (balls) 3, a cage 4 that holds the plurality of rolling elements 3 between the inner ring 1 and the outer ring 2, a seal that covers the opening of the gap between the inner ring 1 and the outer ring 2, and the like Sealing devices 5 and 5. Note that the cage 4 and the sealing device 5 may not be provided.

Grease G is disposed in a gap formed between the inner ring 1 and the outer ring 2 and provided with the rolling elements 3 therein. The base oil of grease G is a synthetic oil, the thickener is a urea compound, and an organosilicon compound is blended as an additive.
Although the kind of organosilicon compound mix | blended with the grease G is not specifically limited, Polysiloxane (silicone oil) is preferable. And the organosilicon compound provided with the functional group which has the adsorptivity with respect to a metal is especially preferable. For example, reactive silicone oil in which a reactive functional group is introduced into the side chain or terminal of polysiloxane (for example, reactive silicone such as amino modification, epoxy modification, carboxyl modification, alcohol modification, methacryl modification, mercapto modification, phenol modification, etc. Oil) and non-reactive silicone oils with non-reactive functional groups introduced into the side chain or terminal of polysiloxane (eg, polyether-modified, methylstyryl-modified, alkyl-modified, higher fatty acid ester-modified, higher alkoxy-modified, fluorine Non-reactive silicone oils such as modified).

In addition to an alkoxy group, a silane coupling agent having a functional group such as an epoxy group, a styryl group, a methacryloxy group, an acryloxy group, an amino group, or a sulfide group in one molecule can also be used. Furthermore, alkoxysilane (for example, tetraalkoxysilane, trialkoxysilane, dialkoxysilane), chlorosilane (for example, trichlorosilane, dichlorosilane), silazane having a silicon-nitrogen bond, and the like can also be used.
In addition, these organosilicon compounds may be used independently and may be used in combination of 2 or more type.

The content of the organosilicon compound in the grease G is preferably 0.01% by mass or more and 20% by mass or less of the entire grease G. When the content is less than 0.01% by mass, it is difficult to sufficiently obtain the effect of suppressing white tissue peeling. On the other hand, when the content exceeds 20% by mass, the ratio of the base oil in the grease G is relatively reduced, and therefore the lubricity may be lowered. In order to make it difficult for such problems to occur, the content of the organosilicon compound is more preferably 0.1% by mass or more and 10% by mass or less.
It should be noted that the grease G may be blended with other types of additives generally used for grease together with an organosilicon compound. For example, antioxidants, rust preventives, extreme pressure agents and the like can be mentioned.

The type of base oil is not particularly limited as long as it is a synthetic oil generally used as a base oil for grease. Aliphatic hydrocarbon oil, aromatic hydrocarbon oil, ester oil, Ether oil, fluorine oil, etc. can be used without problems.
Examples of the aliphatic hydrocarbon oil include normal α-olefins such as normal paraffin, isoparaffin, polybutene, polyisobutylene, 1-decene oligomer, 1-decene and ethylene co-oligomer, and hydrides thereof. Examples of the aromatic hydrocarbon oil include alkylbenzenes such as monoalkylbenzene, dialkylbenzene and polyalkylbenzene, and alkylnaphthalenes such as monoalkylnaphthalene, dialkylnaphthalene and polyalkylnaphthalene.

  Further, as ester oils, dibutyl sebacate, di (2-ethylhexyl) sebacate, dioctyl adipate, diisodecyl adipate, ditridecyl adipate, ditridecyl glutarate, methyl acetyl ricinolate and the like, trioctyl trimellitate, Aromatic ester oils such as tridecyl trimellitate, tetraoctyl pyromellitate, polyol ester oils such as trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol-2-ethylhexanoate, pentaerythritol pelargonate, Examples thereof include complex ester oils which are oligoesters of monobasic and dibasic mixed fatty acids and polyhydric alcohols.

  Further, as ether oils, polyglycols such as polyethylene glycol, polypropylene glycol, polyethylene glycol monoether, polypropylene glycol monoether, monoalkyl triphenyl ether, alkyl diphenyl ether, dialkyl diphenyl ether, tetraphenyl ether, pentaphenyl ether, monoalkyl Examples thereof include phenyl ether oils such as tetraphenyl ether and dialkyl tetraphenyl ether.

Synthetic oils other than the above include tricresyl phosphate, silicone oil, perfluoroalkyl ether oil and the like.
These base oils may be used alone or in combination of two or more. In order to suppress the abnormal noise at the time of cold start by cold flow deficiency, kinematic viscosity base oil preferably 10~400mm ² / s at 40 ° C., the base oil is 20~250mm ² / s Is more preferable.
The type of thickener is not particularly limited as long as it is a urea compound generally used as a thickener for grease, and diurea, triurea, tetraurea, polyurea, and the like can be used without any problem.

〔Example〕
Hereinafter, the present invention will be described more specifically with reference to examples.
[About peel test]
A rolling bearing having substantially the same structure as that of the deep groove ball bearing in FIG. 1 is prepared by changing the content of the organosilicon compound in the grease in various ways. The grease is incorporated in an engine alternator and is subjected to a pulley load of 1560 N at room temperature. A rotation test was performed. Rotation test was a rapid acceleration or deceleration test that switch repeatedly rotational speed of the bearing at predetermined time intervals in a 2400 min ^-1 and 13300min ^-1. A rotation test was performed for each 10 deep groove ball bearings, and the ratio of deep groove ball bearings in which vibration occurred due to separation on the raceway surface of the outer ring within 500 hours (hereinafter referred to as separation probability) was investigated. .

The base oil of the grease used is a hydrocarbon oil having a kinematic viscosity at 40 ° C. of 47 mm ² / s, the thickener is a diurea compound, and the organosilicon compound is a reactive silicone oil with one end modified with alcohol ( Shin-Etsu Silicone X-22-170B) manufactured by Shin-Etsu Chemical Co., Ltd.
The results are shown in the graph of FIG. As can be seen from the graph of FIG. 2, the occurrence probability of peeling was low when the content of the organosilicon compound was 0.01% by mass or more, and the occurrence probability of peeling was 0% when the content was 0.1% by mass or more. In addition, peeling probability when the content of the organosilicon compound was 0% by mass was 70%.

[High-speed four-ball friction and wear test]
Using a high-speed four-ball friction and wear tester as shown in FIG. 3, the test was conducted by the method prescribed in ASTM D 2266. Three steel balls 22 are arranged in an equilateral triangle shape so as to be in contact with each other in a concave portion 21 provided at the center of a ball pot 20 of a high-speed four-ball frictional wear tester, and fixed by a fixture 23, One steel ball 24 was placed in a recess formed in the center. After the grease was applied to all the steel balls 22 and 24, the steel balls 24 were rotated at a rotational speed of 1200 min ⁻¹ by the chuck 25 under an ambient temperature of 75 ° C. At that time, a vertical load of 196 N was applied to the steel ball 24 by a lock nut 26 screwed into the ball pot 20. And the friction coefficient 5 minutes after rotation was measured. Note that the steel balls 22 and 24 are steel balls having a diameter of 1/2 inch (material is SUJ2). The grease used was the same as that used in the peel test.

  The results are shown in the graph of FIG. The friction coefficient shown in the graph of FIG. 2 is a relative value when the friction coefficient of a grease having an organosilicon compound content of 0% by mass is taken as 1. As can be seen from the graph of FIG. 2, the friction coefficient is low when the content of the organosilicon compound is 0.01% by mass or more and 20% by mass or less, and the friction coefficient is 0.1% by mass or more and 10% by mass or less. It was even lower.

  In addition, this embodiment shows an example of this invention, Comprising: This invention is not limited to this embodiment. For example, in the present embodiment, a deep groove ball bearing has been described as an example of a rolling device, but the present invention can be applied to various types of rolling bearings. For example, radial rolling bearings such as angular contact ball bearings, self-aligning ball bearings, cylindrical roller bearings, tapered roller bearings, needle roller bearings, and self-aligning roller bearings, and thrust types such as thrust ball bearings and thrust roller bearings This is a rolling bearing. Furthermore, the present invention can be applied not only to rolling bearings but also to various types of various rolling devices. For example, a ball screw, a linear guide device, a linear motion bearing, or the like.

  The rolling device of the present invention is suitable for use under high temperature, high speed, high load conditions, and conditions where water easily enters. For example, the rolling device of the present invention is a rolling device used for automobile electrical components, automobile engine accessories (alternators, intermediate pulleys, car air conditioner electromagnetic clutches, etc.), gas heat pump electromagnetic clutches, compressors, etc. It is suitable as a device.

It is a longitudinal cross-sectional view which shows the structure of the deep groove ball bearing which is one Embodiment of the rolling device which concerns on this invention. It is a graph which shows the correlation with content of an organosilicon compound, peeling occurrence probability, and a friction coefficient. It is sectional drawing of a high-speed four-ball type friction and abrasion tester.

Explanation of symbols

1 inner ring 1a raceway surface 2 outer ring 2a raceway surface 3 rolling element G grease

Claims (2)

An inner member having a raceway surface on the outer surface, an outer member having a raceway surface opposite to the raceway surface of the inner member, and arranged on the outer side of the inner member, and rolling between the both raceway surfaces A rolling device comprising a plurality of freely arranged rolling elements and lubricated with grease containing a base oil, a thickener and an additive,
A rolling device characterized in that the base oil is a synthetic oil, the thickener is a urea compound, and the additive is an organosilicon compound.   The rolling device according to claim 1, wherein the rolling device is a rolling bearing for an automobile electrical component or an automobile engine accessory.

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