JP2008121770A - Rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling bearing having a chemical conversion coating film formed in an outer circumference surface of the bearing such as an inner ring inner surface and an inner ring width surfaces, wherein spaces between fine crystal particles of the chemical conversion coating film is filled with lubricant having excellent abrasion resistance, and abrasion due to friction with other members and the like in the outer surface of the bearing is prevented. <P>SOLUTION: The rolling bearing for a rolling mill roll neck has a plurality of conical rollers 5 between the outer ring 3 and the inner ring 1, and also has the chemical conversion coating film formed in the inner surface 1c of the inner ring 1 and width surfaces 1a, 1b, 1d, 1e of the inner ring. The spaces between the crystal particles of the chemical conversion coating film is filled with the lubricant holding alkali metal molybdate particles in a dispersed manner. and the lubricant is obtained by wet milling of the alkali metal molybdate in base oil with a surface active agent added. Maximum particle diameter of the alkali metal molybdate is equal to or shorter than 10 μm. The chemical conversion coating film is a phosphate coating film, especially a manganese phosphate coating film. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rolling bearing, and more particularly to a rolling bearing that is used by being loosely fitted to a housing or a rotating shaft, for example, a rolling bearing used for supporting a roll in a rolling mill facility in a steel mill.

  As roll neck bearings used for work rolls and intermediate rolls in hot rolling mills and cold rolling mills, four-row tapered roller bearings (see Patent Document 1) that can support a large load (see Patent Document 1) Patent Document 2), sealed rolling bearings with seals at both ends (see Patent Document 3), and the like are used. As a method for lubricating these bearings, a method using oil-air lubrication in addition to grease lubrication is known (see Patent Document 4).

  In the bearings of Patent Documents 1 to 3, wear of the inner ring inner diameter surface and the inner ring width surface of the bearing is a problem. For example, in a normal four-row tapered roller bearing, a pair of inner rings are combined, and three or four outer rings are arranged one by one between the pair of inner rings and outside the inner ring in the axial direction. If the width surfaces of the cylindrical inner ring are brought into contact with each other, an excessive force is transmitted from the roll neck during rolling, the inner ring creeps and the width surfaces are rubbed and worn. Further, since each bearing is used while being loosely fitted to the rotating shaft, the inner diameter surface of the bearing is worn due to sliding friction with the rotating shaft.

  In order to prevent such wear and the like, the bearing structures of Patent Document 2 and Patent Document 3 require lubrication to the inner ring inner diameter surface and the bearing width surface in addition to the inside of the bearing, and there is a problem that work is required. In Patent Document 1, by prohibiting the relative rotation of the inner rings, wear of the bearing inner rings can be prevented. However, the wear of the inner ring inner diameter surface that is in frictional contact with the rotating shaft and the inner ring width surface on the contact side with the collar is There is a problem that cannot be prevented.

In open type bearings, the inner ring end face and inner diameter face are supplied with lubricant inside the bearing. There are grease lubrication and oil (oil air) lubrication methods, and the supply method is also in the initial stage of operation. There are some that are still sealed, and some that are lubricated (oiled).
However, when the lubricant is lubricated (lubricated) halfway, a lubricant having excellent wear resistance is not always supplied. In addition, there is a problem that the effect of the lubricant is not maintained depending on the frequency of lubrication during the course. In addition, in order to operate the oil / air lubrication equipment that is ancillary equipment, it is necessary to create a high-speed air flow, intermittent injection of lubricating oil, adjustment of a small amount of lubricating oil supply, etc. There are problems such as high costs.
JP 2003-314565 A JP 2005-76746 A JP-A-9-267108 JP 2002-181283 A

  The present invention has been made to cope with such problems, and is formed by forming a chemical conversion coating on the outer peripheral surface of the bearing, such as an inner ring inner diameter surface and an inner ring width surface, and between the fine crystal grains of the chemical conversion coating film. It is an object of the present invention to provide a rolling bearing that can be filled with a lubricant having excellent wear resistance and that can prevent wear due to friction with other members on the outer peripheral surface of the bearing.

In the rolling bearing of the present invention, a plurality of rolling elements are interposed between the outer ring and the inner ring, and chemical conversion treatment is performed on at least one of the inner surface of the inner ring, the width surface of the inner ring, the outer diameter surface of the outer ring, and the width surface of the outer ring. A rolling bearing in which a coating is formed, wherein a lubricant in which particles of alkali metal molybdate are dispersed and held is filled between crystal grains of the chemical conversion coating.
In particular, the rolling bearing is a bearing that supports a roll of a rolling mill.

The lubricant is obtained by wet pulverizing an alkali metal molybdate in a base oil to which a surfactant is added.
Further, the maximum particle diameter of the alkali metal molybdate is 10 μm or less.

  The chemical conversion treatment film is a phosphate film. In particular, the phosphate coating is a manganese phosphate coating.

In rolling bearings used for roll support of rolling mills, an alkali metal molybdate having excellent wear resistance is provided between crystal particles such as phosphate coatings formed on the outer peripheral surface of the bearing such as the inner ring inner diameter surface and inner ring width surface. If the blended lubricant can be filled, the alkali metal molybdate can be supplied to the sliding surface with other members as the coating gradually wears, but the crystal grain size of the phosphate coating is 50 μm or less. In addition, the gap between the crystal grains was smaller than that, and the average particle diameter of the alkali metal molybdate was generally about 200 μm, so that it could not be filled. Further, even if the molybdate is pulverized in advance to reduce the particle size, it tends to agglomerate in the lubricant and is difficult to fill between crystal particles such as a phosphate coating.
On the other hand, wet pulverization of alkali metal molybdate in a base oil to which a surfactant has been added can prevent aggregation of alkali metal molybdate in the lubricant, such as phosphate coating It became possible to fill between the crystal grains. The present invention is based on such knowledge.

The rolling bearing of the present invention is formed by forming a chemical conversion coating on at least one of the inner ring inner surface, the inner ring width surface, the outer ring outer diameter surface, and the outer ring width surface, and an alkali metal molybdate between crystal grains of the chemical conversion coating. Lubricant containing alkali metal molybdate particles on each surface from between the crystal grains as well as improving the antirust property and initial conformability of each surface because it is filled with a lubricant in which salt particles are dispersed and held. Is gradually released as the coating wears, and is excellent in wear resistance over a long period of time.
For this reason, it is possible to prevent wear on the inner ring inner diameter surface and the rotating shaft, the outer ring outer diameter surface and the housing, or these surfaces due to sliding friction between the inner rings and the like, and the bearing replacement cycle becomes longer.

  In particular, since the lubricant obtained by wet pulverization of the alkali metal molybdate in a base oil to which a surfactant is added is used as the lubricant, the particle size of the alkali metal molybdate in the lubricant is reduced, for example, The maximum particle size can be 10 μm or less, and the lubricant can be easily filled between fine crystal particles of the chemical conversion coating.

  The rolling bearing of the present invention has a bearing outer peripheral surface such as an inner ring inner diameter surface, an inner ring width surface, an outer ring outer diameter surface, or an outer ring width surface of the bearing when used in a loose fit (gap fit) on a housing or a rotating shaft. The main object is a bearing that is worn by friction with other attached members.

  As an embodiment of the rolling bearing of the present invention, a rolling mill roll neck rolling bearing will be described with reference to FIG. FIG. 1 is a sectional view of a rolling mill roll neck rolling bearing. As shown in FIG. 1, a sealed four-row tapered roller bearing 12 mounted on a roll neck of a rolling mill includes a pair of inner rings having two rows of rolling surfaces 2a, 2b, 2c, and 2d, and a single row. A pair of outer rings 3a, 3b having rolling surfaces 4a, 4d and one outer ring 3c having two rows of rolling surfaces 4b, 4c; rolling surfaces 2a, 2d, 2b, 2c and outer rings 3a of each inner ring 1; 4 rows of tapered rollers 5 that are arranged so as to roll between the rolling surfaces 4a, 4d, 4b, and 4c of 3b and 3c, and a cage 6 that holds the tapered rollers 5 at predetermined intervals in the circumferential direction; And seal members 7 are attached to both ends of the outer rings 3a and 3b on both sides. A large collar 8 is provided at the center of each inner ring 1, and the tapered roller 5 rolls on each rolling surface 2 while being guided by the large collar 8 when the bearing is used.

The tapered roller 5 receives rolling friction between the rolling surfaces 2a, 2d, 2b, and 2c of the inner ring 1 and the rolling surfaces 4a, 4d, 4b, and 4c of the outer ring, and the flange portions 8a, 8b, 8c, Sliding friction occurs between 8d, 8e, 8f, 8g and 8h. Grease is enclosed to reduce these frictions.
Further, the seal members 7 attached to the end portions of the outer rings 3a and 3b are in sliding contact with the outer diameter surface of the inner ring 1 to seal the inside of the bearing. The seal member 7 includes seal cases 9a and 9b attached to the ends of the outer rings 3a and 3b on both sides, and a contact-type oil seal 11 fitted in an annular groove 10 formed in the inner diameter portion of the seal cases 9a and 9b. Consists of.

  Lubricant in which a chemical conversion treatment film is formed on the inner diameter surface 1c of the inner ring 1 and the width surfaces 1a, 1b, 1d, and 1e of the inner ring 1, and particles of alkali metal molybdate are dispersed and held between the crystal grains of the chemical conversion treatment film Is filled. Further, if necessary, the same chemical conversion treatment film is formed on the rolling surfaces 2a, 2d, 2b, 2c of the inner ring 1, the rolling surfaces 4a, 4d, 4b, 4c of the outer ring, the surface of the tapered roller 5, etc. Also good. The chemical conversion coating film filled with the lubricant of the present invention is excellent in the effect of preventing wear against both sliding friction and rolling friction.

  The rolling bearing for a rolling mill roll neck, which is a rolling bearing of the present invention, is not limited to the four-row tapered roller bearing shown in FIG. 1, but may be a double-row tapered bearing or the like, and each may be a sealed type or an open type. May be.

The chemical conversion coating in the rolling bearing of the present invention is formed on the inner ring inner surface, inner ring width surface, outer ring outer diameter surface, and outer ring width surface by a chemical reaction by bringing a treatment solution into contact therewith by an appropriate means. The This coating is a compound coating composed of microcrystals.
Examples of chemical conversion treatment methods include phosphate treatment and chromate treatment. In the present invention, a phosphate treatment is preferable as a chemical conversion treatment method because it is excellent in wear resistance and oil retention. Among the phosphate treatments, manganese phosphate treatment is particularly preferable.

  Examples of the treatment liquid used for the manganese phosphate salt treatment include an aqueous solution of a manganese phosphate salt compound composed of divalent manganese ions, iron ions, nickel ions and trivalent phosphate ions. The reaction process of film formation when this treatment liquid is used and steel is used as a base material is shown below. Free phosphoric acid is generated by the first dissociation of the aqueous solution of manganese phosphate, and iron on the metal surface is dissolved by the free phosphoric acid. The hydrogen ion concentration on the metal surface decreases, the dissociation equilibrium of the manganese phosphate aqueous solution shifts in the direction of manganese phosphate formation, and insoluble manganese phosphate microcrystals precipitate on the metal surface to form a film. To do. The crystal particle diameter, film thickness, and film roughness in the coating can be adjusted by the treatment solution composition used.

  The average crystal particle diameter of the chemical conversion coating is preferably 10 μm to 50 μm. If the average crystal particle size is less than 10 μm, it is difficult to fill the gaps between the crystal particles even with the lubricant described later. Becomes easy to peel off.

Examples of the material of the inner ring, outer ring, and roller that constitute the rolling bearing of the present invention and serve as the base material of the chemical conversion coating film include, for example, bearing steel (high carbon chromium bearing steel JIS G 4805), case-hardened steel (JIS G 4103). 4104), high speed steel (AMS 6490), stainless steel (JIS G 4303), induction hardened steel (JIS G 4051, etc.).
In the phosphate treatment, since the surface state of the metal base material greatly affects the crystal particle diameter of the coating film to be formed, it is preferable to degrease the metal surface or clean it with ion-exchanged water before the treatment.

  In the rolling bearing of the present invention, a lubricant in which alkali metal molybdate particles are dispersed and held is filled between crystal grains of the chemical conversion coating. As the lubricant, lubricating oil or grease in which alkali metal molybdate particles are dispersed and held can be used.

  A method for dispersing and retaining the particles of the alkali metal molybdate in the lubricant will be described below. A lubricating oil composition is obtained by wet-grinding an alkali metal molybdate in a base oil to which a surfactant is added as a dispersant. By using this method, the pulverized alkali metal molybdate is obtained in a state of being dispersed in fine particles without agglomerating in the base oil.

  The lubricant used in the present invention is the lubricant composition itself, a lubricant obtained by diluting the lubricant composition, and the lubricant composition blended with other lubricants and base greases as additives. Can be used. Even when the lubricating oil composition is blended with lubricating oil, grease, or the like, the alkali metal molybdate salt hardly aggregates and precipitates therein, and the state in which the alkali metal molybdate salt is dispersed and held in fine particles can be maintained.

  As a method of filling the lubricant between the crystal grains of the chemical conversion coating film, the inner ring, the outer ring, etc. on which the chemical conversion coating film is formed are immersed in an impregnation tank filled with the lubricant, and the capillary action between the crystal grains of the coating film For example, a method of impregnating and filling using the above. As described above, in these lubricants, the alkali metal molybdate is dispersed and held in fine particles (maximum particle size of 10 μm or less), so that it can be easily filled between crystal grains. Moreover, you may perform the said impregnation as pressure reduction or pressurization as needed.

  The effect of using the surfactant during the production of the lubricating oil composition is that the fine particles of the alkali metal molybdate crushed in the base oil can be wrapped with the surfactant and dispersed in the base oil. . As a result, fine particles of alkali metal molybdate that originally have no affinity for the base oil are encapsulated with a surfactant to improve the affinity for the base oil, making it easier to maintain a dispersed state in the base oil. Further, it is possible to prevent the effect of addition of the alkali metal molybdate from being reduced by precipitation.

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 anionic surfactants that ionize into negative ions due to the nature of the ionized ions, cationic surfactants that ionize into positive ions, and amphoteric that ionize negatively and positively depending on the pH of the system. Finely classified into surfactants.
The surfactant used in the present invention is at least one surfactant selected from an anionic surfactant and a nonionic surfactant having a good affinity for alkali metal molybdate. preferable.

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

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 alkali metal molybdate is prevented from agglomerating in the base oil, so that the dispersion state of the alkali metal molybdate is improved and the alkali metal molybdate is secondary. It has the effect of preventing the particles from becoming large.

  The blending ratio of the surfactant in the lubricating oil composition is preferably 0.05% by weight to 5% by weight. If it is less than 0.05% by weight, the amount of the surfactant that disperses the finely divided alkali metal molybdate in the base oil is insufficient, resulting in aggregation of the alkali metal molybdate fine particles and an increase in the secondary particle size. If the amount exceeds 5% by weight, the effect of dispersing the finely divided alkali metal molybdate in the base oil reaches its peak, which is disadvantageous in terms of cost.

  Representative examples of the alkali metal molybdate that can be used in the present invention include potassium molybdate, sodium molybdate, and lithium molybdate. Molybdates, especially alkali metal molybdates, have very good wear resistance. This is because, when an alkali metal molybdate salt is blended with a lubricant, the alkali metal molybdate reacts on the frictional wear surface in the presence of the lubricant or the new ferrous metal surface exposed by wear, and a coating is formed on the sliding surface. It is thought that it is for generating.

As described above, the wet pulverization method is employed for producing the lubricating oil composition in which the alkali metal molybdate is dispersed. Common pulverization methods for solid / powder include dry and wet. The dry pulverization method is a method of pulverizing dry powder / particles in a gas phase or in a vacuum. The wet pulverization method is a method of pulverizing powder in a liquid phase. The dry pulverization method has an advantage that the particle size distribution is sharp and has a classification function, but has a disadvantage that 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, alkali metal molybdate) having no affinity for the liquid phase is pulverized in the presence of a surfactant in the liquid phase (here, base oil). The pulverized powder is encapsulated in a surfactant to improve the affinity for the liquid phase. As a result, the dispersibility of the alkali metal molybdate is improved and aggregation and precipitation are less likely to occur.

  The means for pulverizing the alkali metal 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 alkali metal molybdate in the lubricating oil composition is preferably pulverized by the above means so that the maximum particle size is 10 μm or less. When the maximum particle diameter of the alkali metal molybdate in the lubricating oil composition exceeds 10 μm, it becomes difficult to fill a lubricant containing particles of the alkali metal molybdate between the crystal grains of the chemical conversion coating.
Even when this lubricant composition blended with lubricating oil or grease is used as the lubricant to be filled in the chemical conversion coating film, the alkali metal molybdate salt hardly aggregates and precipitates in the lubricant. It is possible to maintain a state in which the salt is dispersed and held at the same maximum particle size as in the lubricating oil composition.

  The blending amount of the alkali metal molybdate in the lubricating oil composition during the production of the lubricating oil composition is preferably 0.1% by weight to 60% by weight, and preferably 0.1% by weight to 50% by weight. Further preferred. If the amount is less than 0.1% by weight, the amount of the pulverized product (alkali metal molybdate) is reduced, 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 the alkali metal 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 having a low concentration of alkali metal molybdate, a method of preparing a lubricating oil composition having a high concentration of alkali metal molybdate first and diluting it to a desired concentration is prepared. Can be adopted.

  The concentration of the alkali metal molybdate in the lubricant filled in the chemical conversion coating film is preferably 0.1% by weight to 20% by weight, preferably 0.5% by weight to 10% by weight, based on the entire lubricant. If it is less than 0.1% by weight, the effect of improving wear resistance cannot be expected. On the other hand, if the amount exceeds 20% by weight, the effect will reach its peak and the cost will be disadvantageous.

  The base oil used in the lubricating oil composition constituting the lubricant of the present invention or used for blending and diluting the lubricating oil composition is not particularly limited as long as it is a commonly used base oil. it can. For example, mineral oil such as naphthenic, paraffinic, liquid paraffin, hydrodewaxed oil, polyglycol oil such as polyalkylene glycol, ether synthetic oil such as alkyl diphenyl ether and polyphenyl ether, diester oil, polyol ester oil, etc. Examples include ester-based synthetic oils, silicone oils such as polydimethylsiloxane and polyphenylmethylsiloxane, hydrocarbon-based synthetic oils such as GTL base oil and poly-α-olefin oil, fluorine oils, and mixed oils thereof.

  The grease constituting the lubricant of the present invention is obtained by adding a thickener to a base oil. Examples of the base oil include those described above. Examples of the thickener include lithium soap, lithium complex soap, calcium soap, calcium complex soap, aluminum soap, aluminum complex soap, and other soaps, diurea compounds, polyurea compounds, and the like. However, it is not particularly limited.

  The diurea compound is obtained, for example, by reaction of diisocyanate and monoamine. Diisocyanates include phenylene diisocyanate, diphenyl diisocyanate, phenyl diisocyanate, diphenylmethane diisocyanate, octadecane diisocyanate, decane diisocyanate, hexane diisocyanate, and monoamines include octylamine, dodecylamine, hexadecylamine, octadecylamine, oleylamine, aniline, Examples include p-toluidine, cyclohexylamine and the like. The polyurea compound can be obtained, for example, by reacting diisocyanate with a monoamine or diamine. Examples of the diisocyanate and monoamine include those similar to those used for the production of the diurea compound. Examples of the diamine include ethylenediamine, propanediamine, butanediamine, hexanediamine, octanediamine, phenylenediamine, tolylenediamine, and xylenediamine. Is mentioned.

  The lubricant of the present invention can contain known additives 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 reducing agents such as organic molybdenum, wax compounds, fatty acid amides, fatty acids, amines, oils such as fats and oils, metal deactivators such as benzotriazole, polymethacrylate, polystyrene, etc. Agents and the like. These can be added alone or in combination of two or more.

Lubricating oil preparation example 1-lubricating oil manufacturing example 4 and comparative manufacturing example 1, comparative manufacturing example 2
In the base oil, the alkali metal 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.

Lubricating oil preparation example 5 and lubricating oil preparation example 6
In the base oil, the alkali metal 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 pasty molybdate dispersed lubricating oil.

Comparative production example 3
The alkali metal molybdate was pulverized in advance with a jet mill and adjusted to a particle size of 4 μm. The adjusted alkali metal 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 side of the pulverized molybdate particles was observed with an electron microscope at a magnification of 1000 times in five fields of view. 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, and if the entire base oil was observed to be clouded by molybdate, it was evaluated that the dispersibility was excellent, 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 with a maximum particle size of 10 μm or less and a degree of dispersion evaluation of “◯” are comprehensively evaluated as being excellent in dispersibility, “◎”, and those other than that are inferior in dispersibility. Then, “x” is also shown in Table 1.

  As shown in Table 1, each of the lubricant preparation examples had a maximum particle size of 10 μm or less and excellent dispersibility, and the comparative preparation example was inferior in dispersibility. In Comparative Production Example 3 in which wet pulverization was not performed in the presence of a surfactant, the dispersibility of the alkali metal molybdate was inferior.

Examples 1 to 6
Bearing test pieces (material: SNCM420, dimensions: φ110 × φ130 × 50 (mm)) on the inner ring inner diameter surface and inner ring width surface of the rolling bearing roll neck for rolling mill shown in FIG. Formed. As a treatment process, the test piece was ultrasonically washed with acetone at 30 ° C. for 10 minutes, subjected to alkali degreasing treatment at 70 ° C. for 2 minutes, washed with ion-exchanged water, and then prepared by Nihon Parker Rising Co. The sample was pretreated at 40 ° C. for 40 seconds using 30 g each of VMB. Next, this test piece was coated with a manganese phosphate treatment solution at 95 ° C. for 10 minutes.

  The average crystal particle size after chemical conversion was measured and found to be 30 μm. The average gap width of the crystal particles was 6 μm. The average crystal particle diameter is a two-dimensional size when observed with a 200-fold electron microscope (SEM), and is an average diameter of about 20 crystals having a circular shape, a polygonal shape, an elliptical shape, or the like. In addition, in the ellipse shape, it represented by the major axis.

For the test piece on which the manganese phosphate coating was formed, the molybdate-dispersed lubricating oil prepared in Lubricating Oil Preparation Example 1 to Lubricating Oil Preparation Example 6 was used with the same base oil so that the molybdate concentration was 1% by weight. Soaked in each lubricating oil diluted with for 10 minutes.
When the obtained test pieces (Example 1 to Example 6) were observed, it was confirmed that the lubricating oil was filled between the crystal particles of any of the test pieces. In each of the lubricating oils of Lubricating Oil Preparation Example 1 to Lubricating Oil Preparation Example 6, the alkali metal molybdate has a maximum particle size of 10 μm or less and excellent dispersibility, so that the lubricating oil is between the crystal grains of the manganese phosphate salt coating. It is thought that it could be filled easily by capillary action.

  The rolling bearing of the present invention is formed by forming a chemical conversion coating on a sliding surface with other members such as an inner ring inner diameter surface and an inner ring width surface, and particles of alkali metal molybdate between crystal grains of the chemical conversion coating. Since it is filled with a lubricant that is dispersed and held and is excellent in wear resistance on the sliding surface, it can be suitably used as a rolling bearing for a rolling mill roll neck used for supporting a roll of a rolling mill facility in an iron mill.

It is sectional drawing of the bearing for rolling mill roll necks.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner ring 2 Rolling surface of inner ring 3 Outer ring 4 Rolling surface of outer ring 5 Tapered roller 6 Cage 7 Seal member 8 Large collar 9 Seal case 10 Annular groove 11 Contact type oil seal 12 Tapered roller bearing

Claims (6)

A rolling element in which a plurality of rolling elements are interposed between the outer ring and the inner ring, and a chemical conversion coating is formed on at least one of the inner diameter surface of the inner ring, the width surface of the inner ring, the outer diameter surface of the outer ring, and the width surface of the outer ring. A bearing,
A rolling bearing comprising a lubricant in which particles of alkali metal molybdate are dispersed and held between crystal grains of the chemical conversion coating.   2. The rolling bearing according to claim 1, wherein the lubricant is obtained by wet-grinding an alkali metal molybdate in a base oil to which a surfactant is added.   The rolling bearing according to claim 1 or 2, wherein the alkali metal molybdate has a maximum particle size of 10 µm or less.   The rolling bearing according to claim 1, wherein the chemical conversion coating is a phosphate coating.   The rolling bearing according to claim 4, wherein the phosphate coating is a manganese phosphate coating.   The rolling bearing according to any one of claims 1 to 5, wherein the rolling bearing is a bearing that supports a roll of a rolling mill.

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