JP2019044045A - Solid lubricant and solid lubricant encapsulated rolling bearing - Google Patents

Abstract

To provide a solid lubricant capable of suppressing the generation of cold abnormal noise in a low temperature condition while preventing the leakage from a bearing.SOLUTION: A solid lubricant 17 is a solid body of a mixture of a resin component and a lubricative component, and is used at a temperature of -20°C or less. The lubricative component is a grease containing a base oil whose main component is a poly-α-olefin oil and a thickner. The resin component is an ultra high molecular weight polyolefin, and is contained from 20 mass% to 50 mass% of the whole solid lubricant.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a solid lubricant sealed in a rolling bearing incorporated in various industrial machines and vehicles, and more particularly to a solid lubricant sealed in a rolling bearing used at low temperature.

  A lubricant (for example, grease) is enclosed in a rolling bearing incorporated in various industrial machines, vehicles and the like in order to impart lubricity. The rolling bearing is also incorporated in, for example, a pulley provided in a power transmission system of a car. When such a pulley is operated under a low temperature condition such as a cold area, abnormal noise may occur immediately after the operation. The abnormal noise generated at the time of cold is called cold abnormal noise.

  The cause of abnormal noise generation during cold weather has not been elucidated yet, but is considered to be caused by solidification of the grease sealed in the rolling bearing. Based on this idea, there has been proposed a technology for suppressing the generation of abnormal noise during cold by using a grease containing a base oil having good fluidity even at low temperatures or a grease having a high consistency (for example, patent documents 1, Patent Document 2).

Unexamined-Japanese-Patent No. 9-208982 Japanese Patent Application Laid-Open No. 11-270566

  However, since the above-mentioned grease is in a semisolid state (grease state) with good fluidity, there is a concern that it is likely to leak from the bearing. And if grease leaks from a bearing, there is a possibility that seizure etc. may occur.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a solid lubricant which can suppress the occurrence of cold abnormal noise under a low temperature condition while preventing the leakage from the bearing. . Another object of the present invention is to provide a solid lubricant encapsulated rolling bearing in which the solid lubricant is encapsulated.

  The solid lubricant according to the present invention is a solid of a mixture of a resin component and a lubricating component, and is a solid lubricant used at a temperature of -20 ° C. or lower, and the lubricating component is a poly-α-olefin oil. A grease containing a base oil containing as a main component a thickener and a thickener, and the resin component is an ultrahigh molecular weight polyolefin and is contained in an amount of 20% by mass to 50% by mass with respect to the entire solid lubricant. It features.

  The thickening agent is characterized in that it is an alicyclic diurea compound. Furthermore, the thickener is characterized in that it is contained in an amount of 20% by mass to 40% by mass with respect to the entire grease. In particular, it is characterized in that it is used at a temperature of −40 ° C. or less.

  The solid lubricant-sealed rolling bearing of the present invention is a solid lubricant-sealed rolling bearing in which a solid lubricant is sealed in a rolling bearing, and the above-mentioned solid lubricant is the solid lubricant of the present invention. .

  The solid lubricant according to the present invention is a solid of a mixture of a resin component and a lubricating component, which is used at a temperature of -20 ° C. or less, and the lubricating component is mainly composed of poly-α-olefin oil. It is a grease containing a base oil to be used and a thickener, and a resin component is an ultrahigh molecular weight polyolefin, which is contained in an amount of 20% by mass to 50% by mass with respect to the entire solid lubricant. At temperatures below -20 ° C, the poly-α-olefin oil exudes from the solid lubricant, and the poly-α-olefin oil imparts lubricity, so that it is possible to suppress the occurrence of cold noise. . Furthermore, since the solid lubricant itself is a solid body and the amount of the poly-α-olefin oil that exudes is small, the lubricant can be prevented from leaking from the bearing.

  Since the thickener is an alicyclic diurea compound, it can impart good thickening to the grease. Furthermore, since the thickening agent is contained in an amount of 20% by mass to 40% by mass with respect to the whole grease, the poly-α-olefin oil which exudes from the solid lubricant becomes a proper amount, and even at a temperature of −20 ° C. or less It is possible to preferably suppress the occurrence of cold abnormal noise. Moreover, since the solid lubricant of the present invention is used at a temperature of −40 ° C. or less, it is suitable for use in extremely cold regions where cold noise is particularly a concern.

  The solid lubricant-sealed rolling bearing of the present invention is formed by sealing the solid lubricant of the present invention. Therefore, while preventing leakage from the bearing, the occurrence of cold abnormal noise is suppressed even at a temperature of -20.degree. It is suitable for use in cold climates.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows an example of the solid lubricant enclosure rolling bearing of this invention. It is sectional drawing which shows the other example of the solid lubricant enclosure rolling bearing of this invention. It is a figure which shows the measurement result of the sound pressure under each temperature. It is a figure which shows the sound pressure difference between the temperature in FIG.

  The cold abnormal noise targeted by the present invention is, for example, an abnormal noise generated when using a rolling bearing in which grease is sealed at a low temperature. As the abnormal noise, in particular, it is aimed at a javelin sound which is a sound that an object peels off. Although the cause of juzzing noise is not clear, it is considered that, for example, grease solidified by low temperature is involved. In addition, the cold abnormal noise is more likely to occur as the operating temperature of the rolling bearing becomes lower. The solid lubricant of the present invention is assumed to be used at a low temperature, for example, a temperature of -20 ° C or less, preferably -30 ° C or less, more preferably -40 ° C or less used.

  The solid lubricant of the present invention is a lubricant in which a mixture of a grease as a lubricating component and an ultrahigh molecular weight polyolefin as a resin component is solidified. The solid lubricant causes the base oil contained in the grease to exude to impart lubricity. The solid lubricant of the present invention is solidified even at a low temperature, and is sufficiently lubricated by a small amount of base oil exuded therefrom, so that it is possible to suppress cold abnormal noise.

  The grease used in the present invention is composed of a base oil containing poly-α-olefin oil (PAO oil) and a thickener. PAO oils are mixtures of oligomers or polymers of alpha-olefins or isomerized alpha-olefins. Specific examples of α-olefins include 1-octene, 1-nonene, 1-decene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1 -Nonadecene, 1-eicosene, 1-docosene, 1-tetradocosene etc. are mentioned, and usually these mixtures are used.

  The above-mentioned base oil consists only of PAO oil or is a mixture of PAO oil and other base oils. As the oil to be mixed with the PAO oil, for example, highly refined oil, mineral oil, ester synthetic oil, ether synthetic oil, silicone oil, fluorine oil, mixed oil of these, etc. can be used. Since the base oil of the present invention contains PAO oil as a main component, the content of PAO oil is 50% by mass or more, preferably 80% by mass or more, based on the whole base oil (mixed oil). In particular, it is preferable to use a base oil consisting only of PAO oil (100% PAO oil).

  As a thickener, a diurea compound selected from the group consisting of aliphatic diurea compounds, aromatic diurea compounds, and alicyclic diurea compounds is used. The diurea compound is obtained by reacting a diisocyanate component with a monoamine component. As the diisocyanate component, phenylene diisocyanate, tolylene diisocyanate, diphenyl diisocyanate, diphenylmethane diisocyanate, octadecane diisocyanate, decane diisocyanate, hexane diisocyanate, etc. may be mentioned. As the monoamine component, aliphatic monoamines, aromatic monoamines and alicyclic monoamines can be used. Examples of aliphatic monoamines include hexylamine, octylamine, dodecylamine, hexadecylamine, octadecylamine, stearylamine and oleylamine. The aromatic monoamines include aniline and p-toluidine. Examples of alicyclic monoamines include cyclohexylamine and the like.

  More specifically, as these urea compounds, aromatic diurea compounds using an aromatic diisocyanate as a diisocyanate component, aromatic monoamines as a monoamine component, aromatic diisocyanates as a diisocyanate component, and aliphatic monoamines as a monoamine component Aliphatic diurea compounds using the above, and alicyclic diurea compounds using the aromatic diisocyanate as the diisocyanate component and using the alicyclic monoamine as the monoamine component. Among these, it is preferable to use an alicyclic diurea compound because of its good thickening property, and it is particularly preferable to use a thickener consisting only of an alicyclic diurea compound.

  The grease in the present invention may consist of only the base oil and the thickener, or may additionally contain an additive. As an additive which can be blended, what is necessary is just a thing which does not impair the effect of the present invention, for example, an antioxidant, a rust inhibitor, an extreme pressure agent, an abrasion regulator, a pH adjuster, etc. can be mentioned.

  The content of the thickener in the above grease is 10 to 50% by mass, preferably 20 to 40% by mass with respect to the total amount of the grease. If the amount is less than 10% by mass, the amount of the base oil may be relatively increased to cause leakage, which may make it impossible to obtain a sufficient lubricating life. On the other hand, if it exceeds 50% by mass, the base oil amount may be relatively reduced, and the lubricating life may be shortened. When a diurea compound is used as a thickener, it is produced by reacting a diisocyanate component and a monoamine component in a base oil.

Examples of the ultrahigh molecular weight polyolefin used in the present invention include powders made of polyethylene, polypropylene, polybutene or copolymers thereof, or mixed powders in which each single powder is blended. Here, the average molecular weight of each powder measured by the viscosity method is preferably 1 × 10 ^{6 to} 5 × 10 ⁶ . It is because the polyolefin in such a molecular weight range is superior to the low molecular weight polyolefin in rigidity and oil retention. Among ultra high molecular weight polyolefins, it is preferable to use ultra high molecular weight polyethylene.

  The content of the ultrahigh molecular weight polyolefin in the solid lubricant is 20 to 50% by mass, preferably 30 to 50% by mass, and most preferably 40 to 50% by mass with respect to the total solid lubricant. . When the amount of the ultrahigh molecular weight polyolefin is less than 20% by mass, the amount of the high molecular weight polyolefin as the resin component is insufficient, the solidification of the lubricant is difficult, and the solid lubricant may leak when the bearing is used. When the amount of the ultrahigh molecular weight polyolefin exceeds 50% by mass, the amount of grease as a lubricating component is insufficient, and the supply of the base oil which exudes from the solid lubricant is inferior.

  In the solid lubricant of the present invention, a predetermined amount of the above-mentioned grease and a predetermined amount of the ultrahigh molecular weight polyolefin are uniformly mixed and directly sealed in a mold or bearing of the predetermined shape. It is obtained by heating to a temperature (melting temperature) and then cooling to solidify. The method of mixing the grease and the ultrahigh molecular weight olefin is not particularly limited, and, for example, a commonly used stirrer such as a Henschel mixer or a ribbon mixer can be used. The heating (baking) conditions are preferably heating at a temperature above the gelation point and below the dropping point of the grease (for example, about 150 to 200 ° C.).

  An example of the rolling bearing in which the solid lubricant according to the present invention is sealed will be described based on FIG. FIG. 1 is a cross-sectional view of a rolling bearing which encapsulates a solidified solid lubricant in a spot pack shape. In the rolling bearing 11, an inner ring 12 having an inner ring rolling surface on the outer peripheral surface and an outer ring 13 having an outer ring rolling surface on the inner peripheral surface are concentrically disposed. A plurality of rolling bearings are provided between the inner ring rolling surface and the outer ring rolling surface Each rolling element 14 is disposed. A cage 15 holds the plurality of rolling elements 14. In the rolling bearing 11, a solid lubricant 17 is enclosed around the rolling element 14.

  Another example of the rolling bearing in which the solid lubricant of the present invention is enclosed is shown in FIG. FIG. 2 is a cross-sectional view of a rolling bearing which encapsulates the solidified solid lubricant in a full pack shape. As in the case of FIG. 1, the rolling bearing 11 in the form of FIG. 2 includes the inner ring 12, the outer ring 13, the rolling elements 14, and the cage 15, and the above solid lubricant 17 around the rolling elements 14. It is obtained by enclosing.

  As an example of the method of encapsulating the solid lubricant 17, the following method may be mentioned. After a predetermined amount of the grease and a predetermined amount of the ultrahigh molecular weight polyolefin are uniformly mixed, the mixture is heated to 90 to 120 ° C. to obtain a semisolid state. Next, the roller bearing 11 is sealed while maintaining the state. As shown in FIG. 1 (a) and FIG. 1 (b), the method of the enclosure is such that a cage 15 consisting of two strips is overlapped and fixed by a rivet 16 between the inner ring 12 and the outer ring 13 In a portion where the inner ring 12 and the outer ring 13 are filled in a so-called full pack shape, as shown in FIG. 2 (a) and FIG. 2 (b). It can be mentioned. The above semisolid is obtained by heating the entire bearing to a temperature not lower than the gelling point of the ultrahigh molecular weight polyolefin and not higher than the dropping point of the grease in the state of being enclosed in this manner, and then cooling to solidify. Is solidified to become a solid lubricant, and the solid lubricant encapsulated rolling bearing of the present invention is obtained. That is, the process of obtaining the rolling bearing in which the solid lubricant of the present invention is enclosed in this manner is a method of suppressing the abnormal noise during rolling of the rolling bearing. Moreover, it can be said that the solid lubricant of the present invention is a lubricant for suppressing cold noise.

  The type of the rolling bearing of the present invention is not limited, and may be an angular ball bearing, a cylindrical roller bearing, a needle roller bearing, a tapered roller bearing or the like in addition to the deep groove ball bearing shown in each drawing. Moreover, any of the form which has a sealing member, and the form which does not have a sealing member may be sufficient.

  The rolling bearing of the present invention can suppress the generation of abnormal noise even at a temperature of −20 ° C. or less, and thus is suitable for a rolling bearing used in a cold region or the like. For example, it is used as a rolling bearing for a pulley incorporated in a pulley provided in a power transmission system of an automobile (fitted to the inner diameter of the pulley).

(1) Preparation of Test Bearing The grease and the ultrahigh molecular weight polyethylene were mixed with the composition (mass%) shown in Table 1 for Example 1 and Comparative Example 3. 0.8 to 1.0 g of the obtained mixture is sealed in a bearing (NTN 6203), heated at 160 ° C. for 30 minutes, and then cooled to solidify a test in which a solid lubricant is enclosed I got a bearing for. The base oil and the thickener were mixed with the composition (mass%) shown in Table 1 for Comparative Examples 1 and 2 to obtain a grease. 0.7 g of the obtained grease was sealed in a bearing (manufactured by NTN, 6203) to obtain a test bearing in which a semi-solid (grease state) grease was sealed.

(2) Cold abnormal noise test The test bearings of Example 1 and Comparative Examples 1 to 3 were operated at each test temperature (−40 ° C., 20 ° C.) to measure the sound pressure. In the case of a test temperature of -40 ° C, the test bearing was cooled at -50 ° C for 1 hour, then assembled into a tester, and the operation started after reaching -40 ° C. In the test, the bearing was rotated to 7000 min- ¹ at 30 seconds after start, and the sound pressure in the meantime was measured.

For example, FIG. 3 shows the time change of the sound pressure at each temperature when the test bearing of Comparative Example 1 is used, and FIG. 4 shows the sound pressure difference between the temperatures. As shown in FIG. 3, at −40 ° C., the sound pressure temporarily rises after the start of operation of the bearing (about 10 seconds later), and the raised sound pressure becomes abnormal noise during cold. On the other hand, this sound pressure rise is not seen at 20 ° C. Therefore, it can be said that the cold abnormal noise is larger as the sound pressure difference is larger. In Example 1 and Comparative Examples 1 to 3, the maximum value of the sound pressure difference as shown in FIG. 4 was calculated to evaluate cold abnormal noise. The results are shown in Table 1.
Rolling bearing: 6203 (with pulley)
Test temperature: -40 ° C, 20 ° C
Bearing rotation conditions: Acceleration to 7000 min- ^{1 in} 30 seconds from start Test load: Load 280 N

  In Table 1, in Example 1, cold abnormal noise could be suppressed more than Comparative Example 1 containing the same grease. Since Comparative Example 1 is semi-solid, it is considered that the stirring accompanying the rotation of the bearing is received even at low temperature, and abnormal noise is generated. On the other hand, in Example 1, the solid lubricant itself is solidified, and a small amount of base oil (PAO oil) exuded from the solid lubricant imparts lubricity, thereby suppressing the generation of abnormal noise. it can. Moreover, since the solid lubricant of Example 1 is solidified, the lubricant can be prevented from leaking from the bearing. On the other hand, although comparative example 3 is solidified, cold abnormal noise similar to comparative example 2 containing the same grease is generated. That is, cold noise can not be suppressed only by using a solid lubricant that has been solidified. From the above, it is possible to suppress cold abnormal noise by using a solid lubricant in which a mixture of a grease containing a base oil mainly composed of PAO oil and an ultrahigh molecular weight polyolefin as a resin component is solidified. it can.

  The solid lubricant of the present invention can suppress the generation of cold abnormal noise under low temperature conditions while preventing the leakage from the bearing, so it is suitable for a solid lubricant encapsulated rolling bearing used in a cold district etc. ing.

11 Rolling bearing 12 Inner ring 13 Outer ring 14 Rolling element 15 Cage 16 Rivet 17 Solid lubricant

Claims (5)

A solid lubricant which is a solid of a mixture of a resin component and a lubricating component and used at a temperature of -20 ° C. or less,
The lubricating component is a grease comprising a base oil mainly composed of poly-α-olefin oil, and a thickener,
The solid lubricant characterized in that the resin component is an ultrahigh molecular weight polyolefin and is contained in an amount of 20% by mass to 50% by mass with respect to the entire solid lubricant.   The solid lubricant according to claim 1, wherein the thickening agent is an alicyclic diurea compound.   The solid lubricant according to claim 2, wherein the thickener is contained in an amount of 20% by mass to 40% by mass with respect to the entire grease.   The solid lubricant according to any one of claims 1 to 3, which is used at a temperature of -40 ° C or less. A solid lubricant sealed rolling bearing in which a solid lubricant is sealed in a rolling bearing,
A solid lubricant encapsulated rolling bearing characterized in that the solid lubricant is the solid lubricant according to any one of claims 1 to 4.

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