JP2008121761A - Spherical surface slide bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spherical surface slide bearing excellent in abrasion resistance even under a severe condition, and also to provide the spherical surface slide bearing with excellent lubricity and heat resistance by enhancing its abrasion resistance especially under a high surface pressure. <P>SOLUTION: A phosphate coating film 3b is coated on a recessed spherical surface 3a and, as a lubricant of the radial spherical surface slide bearing 1 for lubricating a sliding surface where an outer ring 3 and an inner ring 2 contacts with a predetermined lubricant, lubricating oil in which a surface active agent and alkali metal molybdate particles are dispersed or a lubricant including these are used and impregnated to the phosphate coating film 3b so that the alkali metal molybdate particles are held in clearances of crystal particles. Contacting a sliding counterpart with a chemical conversion coating film, the alkali metal molybdate particles are gradually supplied from the chemical conversion coating film to a sliding surface, and the alkali metal molybdate forms molybdenum oxide and the like by oxidation reaction and the like in an extreme pressure state and improves abrasion resistance of the spherical plain bearing and a sliding counterpart material is enhanced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a spherical plain bearing that lubricates a sliding surface with a lubricant.

  Generally, a spherical plain bearing is used when an attachment error to a shaft that performs a low-speed rocking motion, a shaft deflection due to a load, or a twist is not elastically acceptable.

  The schematic configuration of the radial spherical plain bearing 1 will be described with reference to FIG. 1. An inner ring 2 whose sliding surface is formed as a convex spherical surface, and an outer ring 3 where a concave spherical surface 3a along the convex spherical surface 2a is formed. These sliding surfaces are lubricated with a lubricant such as grease.

  The thrust spherical plain bearing is attached to a small-diameter shaft portion 5a formed at the end of the shaft 5, and an inner ring 7 having a sliding surface formed into a convex hemispherical surface 7a and a concave spherical surface 8a formed along the outer periphery thereof. The outer ring 8 and a lubricant such as grease for lubricating these sliding surfaces.

  Such spherical plain bearings are often used under lubrication under high surface pressure, and wear occurs on the surface where slippage occurs, often causing problems such as vibration and seizure due to the wear. Countermeasures are required.

  In addition, for spherical rolling bearings, if the inner ring holding the rotating shaft and the shaft are loosely fitted, the inner ring inner circumferential surface may slide against the shaft surface. The peripheral surface is recognized as a sliding surface.

  In order to improve the performance of such a spherical plain bearing, various additives are added to the lubricant such as grease for various purposes. In order to improve the seizure resistance, a sulfur-based additive is blended, and in order to improve the friction characteristics, organic molybdenum or the like is sometimes blended.

In particular, as a lubricating grease adjusted to have both lubricity and heat resistance under conditions of high load and high heat, there are those that contain molybdate or molybdenum oxide and further used in combination with an extreme pressure agent. It is known to use molybdenum oxide, calcium molybdate, molybdic acid in combination with a friction modifier or extreme pressure agent for the purpose of achieving both wear resistance and low friction under such severe conditions. (Patent Document 1).
In addition, chemical conversion treatment is performed to prevent rusting of the metal surface, to improve the adhesion between the steel plate or the like and the paint, and to enhance the effect of facilitating initial conformity to the metal sliding surface.

  As a general chemical conversion treatment, for example, a manganese phosphate salt coating treatment is applied to a metal surface such as iron to give a rust-preventing effect, or adhesion between a steel plate or the like and a paint as a coating base for a rolled steel plate or the like. Improvements have been made or initial familiarity between the raceway surfaces of the inner ring and outer ring of the bearing and the surface of the rolling element has been promoted (Patent Document 2).

JP 2000-53989 A JP-A-6-159371

  However, even if a lubricant such as grease is applied beforehand when lubricating the sliding surface of the spherical plain bearing from the above prior art, the characteristics of the lubricant will improve the wear resistance of the sliding surface. Even if the chemical conversion coating can be used effectively for the “familiarity” of the initial sliding of the bearing and a certain degree of wear resistance, it may not be sufficient for improvement. It was not possible to act stably and sufficiently.

  For this reason, the spherical plain bearing is particularly insufficient in terms of wear resistance under severe sliding conditions such as when the load is high and the speed is low.

  In particular, when a large load is applied to the sliding surface of the spherical plain bearing and the sliding speed becomes low, the lubricating oil film becomes thin and the life (durability) of the spherical plain bearing is shortened. Thus, when the viscosity of the lubricant is increased to increase the oil film thickness, there is a possibility that poor lubrication may occur.

  Accordingly, the object of the present invention is to solve the above-mentioned problems so as to provide a spherical plain bearing having a sliding surface with excellent wear resistance even under severe conditions, and particularly to improve wear resistance characteristics under high surface pressure. In addition, a spherical plain bearing having excellent properties in lubricity and heat resistance is to be obtained.

  In order to solve the above-mentioned problem, in the present invention, an inner ring having a convex spherical sliding surface and an outer ring having a concave spherical sliding surface in sliding contact with the convex spherical surface are provided, and the outer ring In a spherical plain bearing that lubricates the sliding surface that comes into contact with the inner ring with a lubricant, the chemical conversion film formed on the sliding surface is impregnated with a lubricant in which alkali metal molybdate particles are dispersed or a lubricant containing these. The spherical sliding bearing is formed by holding alkali metal molybdate particles in the gaps between the crystal grains of the chemical conversion coating.

  The spherical plain bearing of the present invention configured as described above is an alkali metal molybdate salt held in a dispersed state in the gaps between the crystal grains of the chemical conversion coating when the surface of the metal spherical plain bearing slides. When the particles come into contact with the sliding partner together with the chemical conversion coating, the particles are gradually supplied from the chemical conversion coating to the sliding surface. The alkali metal molybdate forms molybdenum oxide or the like by an oxidation reaction or the like in an extreme pressure state. Improve wear resistance of spherical plain bearings and sliding counterparts.

  From a microscopic view of the metal surface, it is considered that the alkali metal molybdate fine particles are dispersed and held in the gaps between the crystal grains of the chemical conversion coating film by capillary action during the impregnation of the lubricant containing the lubricating oil. It is done.

  In order to keep the alkali metal molybdate particles dispersed in the gaps between the crystal particles of the chemical conversion coating such as a phosphate coating and gradually supply them to the sliding surface, alkali molybdate is preferable. The metal salt particles are fine particles having a maximum particle size of 10 μm or less.

  Further, in order to ensure that the fine particles of the alkali metal molybdate as described above are dispersed in the state of primary particles in the lubricant, the lubricant is a lubricant containing a surfactant as a dispersion medium. The lubricant is preferably a lubricant in which an alkali metal molybdate is finely divided and dispersed by wet grinding.

  Further, in order to appropriately disperse the alkali metal molybdate in the lubricating oil by wet grinding as described above to obtain a preferable lubricant, the blending ratio of the alkali metal molybdate particles in the lubricant is 0.1. It is preferably ˜60% by weight.

  Further, in order to reliably retain the finely divided alkali metal molybdate particles in the gaps between the crystal grains of the chemical conversion coating, it is preferable that the chemical conversion coating is a phosphate coating such as a manganese phosphate coating. .

  Considering the heat resistance against frictional heat generated on the sliding surface, when the lubricant is a grease in which a thickener is blended with a base oil, the thickener is a urea compound, particularly an aromatic or A spherical plain bearing having the above-described configuration employing a grease which is an alicyclic diurea compound, for example, a diurea compound represented by the following formula 1 is preferable.

(In the formula, R ¹ and R ³ is a linear alkyl group or a cyclohexyl group having a carbon number of 4 to 24, R ¹ and R ³ may .R ² be different even identical, (It is an aromatic hydrocarbon having 6 to 15 carbon atoms.)

  In the present invention, the chemical conversion treatment film is formed on the sliding surface of the spherical sliding bearing that lubricates the sliding surface with a lubricant, and the alkali metal molybdate particles are held in the gaps between the crystal particles. The metal salt is gradually supplied from the phosphate film crystal to the sliding part, reducing the wear of the metal sliding surface, and extending the replacement time of the lubricating oil for the spherical plain bearing by maintaining the wear resistance effect. There are advantages.

  In particular, it has the advantage of being a spherical plain bearing with a sliding surface with excellent wear resistance even under harsh conditions, improving the wear resistance under high surface pressure, and having excellent lubricity and heat resistance. There is an advantage that it becomes a slide bearing.

  In the case of a lubricant in which an alkali metal molybdate salt is finely divided and dispersed by wet grinding in the presence of a surfactant, the fine particles are dispersed without any agglomeration and work efficiently. Particularly, the maximum particle size is 10 μm or less. In the case of fine particles, the spherical plain bearing is more preferable in the durability of the wear resistance effect.

  A spherical plain bearing in which the chemical conversion coating is a manganese phosphate coating, and if the blending ratio of the alkali metal molybdate particles in the lubricant is a predetermined amount, the lubricant and wear resistance are more efficiently exhibited. become.

  If the lubricant is a grease that employs an aromatic or alicyclic diurea compound as a thickener, there is an advantage that it becomes a heat-resistant spherical plain bearing that can withstand frictional heat generated on the sliding surface.

  The metal constituting the spherical plain bearing in the present invention can be employed without any particular limitation on the type of metal, and is mainly an iron-based metal such as steel, bearing steel, stainless steel, high carbon chromium steel (SUJ2). Spherical bearings made of iron-based metals containing metals for improving properties such as carbon, nickel, chromium, etc., or known metals other than iron-based metals or composite materials using metals. Good.

  The chemical conversion film formed on the surface of such a spherical plain bearing is subjected to a treatment such as coating, dipping, or spraying so as to impregnate a lubricating oil in which alkali metal molybdate particles are dispersed or a lubricant containing these. There is an effect that the alkali metal molybdate particles can be held in the gaps between the crystal particles of the chemical conversion coating. As such a chemical conversion treatment film, a well-known chemical conversion treatment film such as a chromate film by chromate treatment can be adopted in addition to a phosphate film.

For example, when forming a phosphate film, each film can be formed using, for example, a commercially available manganese phosphate film agent, zinc phosphate film agent, iron phosphate film agent, or the like. These coating agents are composed of phosphate compounds of manganese and zinc. These agents are heated to dissolve the metal, and crystal particles of manganese phosphate and zinc phosphate are deposited on the surface of the metal. This is deposited as a film.
The chromate treatment is a method in which a spherical plain bearing is immersed in a chromic acid solution containing hexavalent chromium, and a film is formed on the surface thereof.

  Incidentally, the manganese phosphate coating solution is composed of an aqueous solution of a manganese phosphate compound composed of divalent manganese ions, iron ions, nickel ions, trivalent phosphate ions, and the like. When the degreased and washed metal is brought into contact with the solution and heated, free phosphoric acid is generated by dissociation of the manganese phosphate aqueous solution, iron on the metal surface of the base metal is dissolved, and the hydrogen ion concentration on the metal surface is reduced. As the dissociation equilibrium of the aqueous manganese phosphate solution shifts on the metal surface, insoluble manganese phosphate crystals precipitate on the surface. This manganese phosphate salt is composed of manganese and iron, and the crystal grain size, film thickness, and coating roughness depend on the components of the compound.

  The lubricant may be a lubricating oil in which alkali metal molybdate particles are dispersed or a lubricant containing these, and may be a lubricating oil or a grease enriched with a thickener using a lubricating oil as a base oil. Good.

  Base oils that are components of lubricating oils or base greases are naphthenic, paraffinic, liquid paraffin, mineral oil such as hydrodewaxed oil, polyglycol oil such as polyalkylene glycol, ether type such as alkyldiphenyl ether, polyphenyl ether, etc. Synthetic oil, diester oil, ester synthetic oil such as polyol ester oil, silicone oil such as polydimethylsiloxane and polyphenylmethylsiloxane, hydrocarbon synthetic oil such as GTL base oil, poly-α-olefin oil, fluorine oil, etc. These mixed oils can be used.

  When the lubricant is grease, the blending ratio of the base oil is preferably 50 to 98.9% by weight, more preferably 70 to 96.9% by weight, based on the entire grease composition. When the blending ratio of the base oil is less than 50% by weight, the grease is hard and the lubricity at low temperatures is poor. On the other hand, if it exceeds 98.9% by weight, it is soft and easily leaks.

  Thickeners used for grease include lithium soap, lithium complex soap, calcium soap, calcium complex soap, aluminum soap, aluminum complex soap and other urea compounds such as diurea compounds and polyurea compounds. It is not particularly limited. However, in consideration of heat resistance and wear resistance, it is desirable to use an aromatic or alicyclic diurea compound represented by the formula 1 above.

Such a diurea compound is obtained by reaction of diisocyanate and monoamine, for example.
Examples of the diisocyanate include phenylene diisocyanate, diphenyl diisocyanate, phenyl diisocyanate, diphenylmethane diisocyanate, octadecane diisocyanate, decane diisocyanate, and hexane diisocyanate.

  Examples of the monoamine include octylamine, dodecylamine, hexadecylamine, octadecylamine, stearylamine, oleylamine, aniline, p-toluidine, cyclohexylamine and the like. Among these, particularly preferred monoamines are octylamine, octadecylamine or cyclohexylamine.

  The urea compound can be obtained by reacting an isocyanate compound with an amine compound. However, since no reactive free radical is left, the isocyanate group of the isocyanate compound and the amino group of the amine compound are blended so as to be approximately equivalent. It is preferable.

  Thus, the base grease for mix | blending various compounding agents is obtained by mix | blending a urea compound etc. with base oil. Such a base grease is produced by reacting an isocyanate compound and an amine compound in a base oil.

  The blending ratio of the thickener used in the present invention is preferably 1 to 40% by weight, more preferably 3 to 25% by weight, based on the entire grease composition. This is because if the blending amount of the thickener is less than the predetermined amount, the thickening effect is reduced and it is difficult to form grease, and if it is too much, the grease becomes too hard.

  In this invention, when producing a lubricating oil in which alkali metal molybdate particles are dispersed or a lubricant containing these, a lubricating oil composition that is difficult to agglomerate and precipitate in the oil and that the molybdate is maintained in a dispersed state with fine particles. In order to obtain a product, a molybdate is pulverized in a base oil in the presence of a surfactant as a dispersant to obtain a dispersed lubricating oil composition. In this way, it is difficult to agglomerate and precipitate even in oil, and the molybdate exhibits excellent dispersibility capable of maintaining a dispersed state with fine particles.

  The effect of using the surfactant in the present invention is that the fine particles of molybdate crushed in the base oil can be wrapped with the surfactant and dispersed in the base oil. As a result, fine particles of molybdate that originally have no affinity for the base oil are encapsulated with a surfactant to improve the affinity for the base oil, so that it becomes easier to maintain a dispersed state in the base oil and precipitate. This can prevent the effect of adding molybdate from decreasing.

  Surfactants have functional groups with different properties such as a hydrophilic group and a lipophilic group in one molecule. Surfactants can be classified according to their structure into ionic surfactants that ionize when hydrophilic groups are ionized and nonionic surfactants that do not ionize. Ionic surfactants are further anionic surfactants that ionize to negative ions due to the nature of the ionized ions, cationic surfactants that ionize to positive ions, and negatively and positively ionize depending on the pH of the system. Finely classified into amphoteric surfactants.

  The surfactant used in the present invention is preferably at least one surfactant selected from an anionic surfactant and a nonionic surfactant having a good affinity for molybdate.

  Examples of anionic surfactants include fatty acid salts, alkylbenzene sulfonates, higher alcohol sulfates, polyoxyethylene alkyl ether sulfates, α-sulfo fatty acid ester salts, α-olefin sulfonates, alkyl phosphate esters. Examples thereof include, but are not limited to, salts, alkane sulfonates, acyl glutamates, imidazoline compounds, polycarboxylic acid type polymers, and naphthalene sulfonic acid formalin condensates.

  Examples of nonionic surfactants include polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, polyoxyethylene derivatives, polyoxyethylene alkylphenol ether, alkyl glucoside, polyoxyethylene fatty acid ester, sucrose fatty acid ester, sorbitan fatty acid Examples include esters, glycerin fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, fatty acid alkanolamides, polyoxyethylene alkylamines, polyoxyethylene glycerides, and the like, but are not limited thereto. .

  In combination with the surfactant, the finely divided molybdate is prevented from agglomerating in the base oil, thereby improving the dispersion state of the molybdate and increasing the molybdate as secondary particles. There is an effect to prevent.

  The blending ratio of the surfactant in the lubricant of the present invention is preferably 0.005 wt% to 5 wt%. If it is less than 0.005% by weight, the amount of the surfactant that disperses the finely divided molybdate in the base oil is insufficient, and the molybdate fine particles are aggregated and the secondary particle diameter is increased. If the amount exceeds 5% by weight, the effect of dispersing finely divided molybdate in the base oil will reach a peak, which is disadvantageous in cost.

  In the present invention, a wet pulverization method is employed for manufacturing a lubricant in which molybdate is dispersed. Common pulverization methods for pulverizing a solid include a dry method and a wet method. The dry pulverization method is a method of pulverizing dry powder or particles in a gas phase or in a vacuum. The wet pulverization method is a method of pulverizing powder (particles) in a liquid phase. The dry pulverization method has the advantage that the particle size distribution is sharp and has a classification function, but has the disadvantage that the particles are difficult to disperse in a liquid phase such as a base oil.

  In the wet pulverization method used in the present invention, powder (here molybdate) having no affinity for the liquid phase is pulverized in the presence of a surfactant in the liquid phase (here, base oil). The resulting powder is encapsulated in a surfactant to improve the affinity for the liquid phase. As a result, the dispersibility of molybdate is improved and aggregation and precipitation are less likely to occur.

  In the present invention, the means for pulverizing molybdate may be any means capable of wet pulverization. If wet pulverization is possible, a general pulverizer can be used. Examples thereof include a ball mill, a rod mill, a planetary mill, an atomizer mill, a bead mill, a mortar, a three-stage roll mill, a colloid mill, a corn mill, an auto-form mill, an optimizer, and a homogenizer. Moreover, the grinder which combined these may be used.

  The molybdate in the lubricant of the present invention is preferably pulverized by the above means so that the maximum particle size is 10 μm or less. This is because, when the maximum particle size of molybdate in the lubricant exceeds 10 μm, precipitation tends to occur even when wet pulverization is performed in the presence of a surfactant.

  The molybdate used in the present invention is preferably a metal salt, more preferably an alkali metal salt.

  Typical examples of the alkali metal salt of molybdic acid that can be used in the present invention include potassium molybdate, sodium molybdate, and lithium molybdate.

  The blending amount of molybdate in the lubricant of the present invention is preferably 0.1% by weight to 60% by weight, and more preferably 0.1% by weight to 50% by weight. If the amount is less than 0.1% by weight, the amount of pulverized product (molybdate) decreases, which not only makes it difficult to pulverize but also increases the pulverization time, which is not practical. On the other hand, when the amount exceeds 60% by weight, the lubricating oil composition in which molybdate is finely dispersed is changed from a paste to a solid and loses fluidity, making it difficult to grind and disperse.

Further, when producing a lubricating oil composition having a low molybdate concentration, a method is adopted in which a lubricating oil composition having a high molybdate concentration is first prepared and diluted to a desired concentration. be able to.

  A lubricant such as grease may contain a known additive as required. Examples of this additive include solid lubricants such as molybdenum disulfide and graphite, antioxidants such as amines and phenolic compounds, rust inhibitors such as petroleum sulfonates, dinonylnaphthalene sulfonates, sorbitan esters, sulfurized fats and oils, Sulfur compounds typified by sulfurized olefins, thiophosphates, sulfur-phosphorus compounds typified by thiophosphites, phosphorus compounds typified by tricresyl phosphate, etc., extreme pressure agents, metal sulfonates, metal phosphates Detergents such as organic molybdenum, friction reducers such as organic molybdenum, wax compounds, fatty acid amides, fatty acids, amines, oils such as fats, metal deactivators such as benzotriazole, sodium nitrite, polymethacrylate, polystyrene, etc. And a viscosity index improver. These can be added alone or in combination of two or more.

An embodiment of a spherical plain bearing of the present invention will be described below with reference to the accompanying drawings.
As shown in FIG. 1, the radial spherical plain bearing 1 according to the embodiment includes an inner ring 2 having a sliding surface formed on a convex spherical surface 2a and an outer ring formed with a concave spherical surface 3a along the convex spherical surface 2a. The concave spherical surface 3a of the outer ring 3 is covered with a phosphate film 3b, and the sliding surface where the outer ring 3 and the inner ring 2 are in contact is lubricated with a lubricant such as grease.

  Further, in the radial spherical plain bearing 1, the inner peripheral surface of the inner ring 2 may slide with respect to the surface of the shaft 5 if the inner ring 2 holding the rotating shaft 5 and the shaft 5 are loosely fitted. A phosphate film can also be formed on the inner peripheral surface of the inner ring 2 and lubricated with a lubricant such as grease.

  Further, as shown in the figure, a thrust spherical plain bearing 6 is provided at one end of a shaft 5 that the radial spherical plain bearing 1 rotatably supports.

  The thrust spherical plain bearing 6 is attached to a small-diameter shaft portion 5a formed at the end of the shaft 5, and an inner ring 7 having a sliding surface formed into a convex hemispherical surface 7a and a concave spherical surface 8a formed along the outer periphery thereof. In the same manner as in the case of the radial spherical plain bearing, the phosphate film 8b that covers the surface of the concave spherical surface 8a is coated, and the sliding surface where the outer ring 8 and the inner ring 7 are in contact is lubricated with grease or the like. Lubricated with chemicals.

  According to such a combination of the radial spherical plain bearing 1 and the thrust spherical plain bearing 6, a spherical plain bearing capable of supporting both a radial load and a thrust load is obtained.

  Of course, the radial spherical plain bearing 1 and the thrust spherical plain bearing 6 can be used independently according to the application.

  In the spherical plain bearing of the embodiment configured as described above, when the sliding surface where the outer ring and the inner ring are in contact is lubricated with grease having a predetermined composition, the alkali metal molybdate particles gradually slide from the chemical conversion coating. Supplied to the surface. Then, it is considered that the alkali metal molybdate forms molybdenum oxide or the like on the sliding surface between the outer ring and the inner ring in a spherical sliding bearing that slides at a low speed with a high load, thereby improving the wear resistance.

[Production Examples 1 to 4 and Comparative Production Examples 1 and 2]
In the base oil, the molybdate and the surfactant were adjusted at the blending ratio shown in Table 1. These were pulverized in a mortar for 72 hours to obtain a pasty molybdate dispersed lubricating oil.

[Production Example 5 and Production Example 6]
In the base oil, the molybdate and the surfactant were adjusted at the blending ratio shown in Table 1. These were pulverized with an atomizer mill for 72 hours to obtain a paste-like molybdate dispersed lubricating oil.

[Comparative Production Example 3]
The molybdate was previously pulverized by a jet mill and adjusted to a particle size of 4 μm. The adjusted molybdate and surfactant were adjusted and mixed in the base oil at the blending ratio shown in Table 1 to obtain a molybdate dispersed lubricating oil.

  These molybdate dispersed lubricating oils were evaluated as follows to compare dispersibility and particle diameter.

<Maximum particle size>
The obtained molybdate-dispersed lubricating oil was degreased and the long sides of the pulverized molybdate particles were observed with an electron microscope at a magnification of 1000 times in five fields, and the largest one was given as the maximum particle size. It was written together.

<Dispersity evaluation>
The prepared molybdate-dispersed lubricating oil was diluted with the same type of base oil so that the molybdate concentration was 1% by weight. The diluted base oil was sufficiently stirred and allowed to stand. After 24 hours, the dispersion state of the molybdate in the base oil was confirmed. If the whole base oil was observed to be clouded by molybdate, the dispersion was evaluated as being excellent in dispersibility. In addition, “x” was also shown in Table 1 in each case where the cloudiness state was not observed and the dispersibility was evaluated to be inferior.

<Comprehensive evaluation>
Those having a maximum particle size of 10 μm or less and having a dispersity evaluation of “◯” are comprehensively evaluated as being excellent in dispersibility, and “◎”, and the other particles are inferior in dispersibility. Then, “x” is also shown in Table 1.

As shown in Table 1, each production example has a maximum particle size of 10 μm or less and excellent dispersibility.
The comparative production example was inferior in dispersibility. Further, in Comparative Production Example 3 in which the wet pulverization was not performed in the presence of the surfactant, the dispersibility of the molybdate was inferior.

Next, the greases of Production Examples 1 to 6 were sealed on the sliding surfaces of the following spherical plain bearings.
The spherical plain bearings used were made of high carbon chrome steel (SUJ2), and each of the sliding surfaces where the outer ring and inner ring were in contact with the manganese phosphate salt coating solution (divalent manganese ions, iron ions, nickel) A degreased and washed base material is immersed in a heated condition in an ion and a trivalent phosphate ion), and an aqueous manganese phosphate salt coating treatment of the manganese phosphate compound is performed. A manganese acid salt film (average crystal grain size: 40 μm) was formed on the convex spherical surface of the inner ring and the concave spherical surface of the outer ring. Next, it was immersed in the greases of Production Examples 1 to 6 in which an alkali metal molybdate having an average particle size of 3 μm and a maximum of 10 μm was dispersed on the surface after the phosphate coating was formed. By this, the capillary phenomenon was utilized between the phosphate film crystals, and the alkali metal molybdate was dispersed and held between the crystals.

The obtained spherical plain bearing can maintain sufficient lubricity and wear resistance even under high load and low speed swinging conditions, even under high load and low speed swinging conditions where the oil film forming ability is inferior, The lubrication life of the spherical plain bearing could be extended.
Judging from the above results, it is estimated that the oil film forming ability is not reduced even when the molten iron is rolled with high load and low speed rocking, like the rolling roll shaft of steel equipment. The

The longitudinal cross-sectional view which shows the spherical plain bearing which is embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Radial spherical plain bearing 2, 7 Inner ring 2a Protruding spherical surface 3, 8 Outer ring 3a, 8a Concave spherical surface 3b, 8b Phosphate coating 5 Shaft 5a Small diameter shaft part 6 Thrust spherical plain bearing 7a Convex hemisphere

Claims (8)

An inner ring having a convex spherical sliding surface and an outer ring having a concave spherical sliding surface in sliding contact with the convex spherical surface are provided, and the sliding surface in contact between the outer ring and the inner ring is lubricated with a lubricant. In spherical plain bearings,
The chemical conversion treatment film formed on the sliding surface is impregnated with a lubricating oil in which alkali metal molybdate particles are dispersed or a lubricant containing these, and the alkali metal molybdate particles in the gaps between the crystal particles of the chemical conversion treatment film. A spherical plain bearing made of   The spherical plain bearing according to claim 1, wherein the lubricant is a lubricant containing a surfactant.   The spherical plain bearing according to claim 1 or 2, wherein the alkali metal molybdate particles are fine particles having a maximum particle size of 10 µm or less.   The spherical plain bearing according to any one of claims 1 to 3, wherein the lubricant is a lubricant in which an alkali metal molybdate is finely divided and dispersed by wet grinding using a lubricant containing a surfactant as a dispersion medium. .   The spherical plain bearing according to any one of claims 1 to 4, wherein a blending ratio of the alkali metal molybdate particles in the lubricant is 0.1 to 60% by weight.   The spherical plain bearing according to any one of claims 1 to 5, wherein the chemical conversion coating is a phosphate coating.   The spherical plain bearing according to claim 6, wherein the chemical conversion coating is a manganese phosphate coating.   The spherical plain bearing according to any one of claims 1 to 7, wherein the lubricant is a grease obtained by blending a thickener with a base oil, and the thickener is a urea compound.

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