JP2007285498A - Rolling bearing for continuous casting machine, and continuous casting machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To extend the replacement period of a rolling bearing for a continuous casting machine by using an inexpensive means for suppressing the wear of rolling elements and inner and outer rings. <P>SOLUTION: Grease A to be filled into the bearing is formed by adding alkali metal salt of molybdenum acid to base grease formed by mixing thickener into base oil. A coating containing molybdenum oxide is formed on the sliding surfaces of rollers 4 and the inner and outer rings 3, 2 to suppress the wear of the sliding surfaces. The inexpensive means is used for elongating the replacement period of an automatic aligning roller bearing 1 as the rolling bearing for the continuous casting machine. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rolling bearing for a continuous casting machine and a continuous casting machine.

  In a continuous casting machine that continuously casts a slab with a mold, a slab that is continuously cast at a low speed is cooled while being guided along a predetermined line by a guide roll. Cut to length. A rolling bearing in which grease is sealed inside a bearing in which a plurality of rolling elements are arranged between inner and outer rings is used as a bearing that supports a guide roll that guides a slab of the continuous casting machine (for example, a patent) Reference 1). As this rolling bearing, a self-aligning roller bearing, a cylindrical roller bearing with an aligning ring, a split cylindrical roller bearing, or the like is used.

  Since the guide roll of the continuous casting machine rotates at a low speed while guiding a large and heavy slab, the rolling bearing for the continuous casting machine that supports the slab is between the rolling element and the raceway surface of the inner and outer rings. In addition, it is difficult to form an oil film of grease, and the raceways of the rolling elements and the inner and outer rings are very easily worn. For this reason, the exchange period of a bearing becomes short and there exists a problem that the operation rate of a continuous casting machine falls. In steelworks that employ a system that directly feeds continuously cast slabs to the lower rolling process without stocking them in the cooling yard, a reduction in the operating rate of the continuous casting machine also leads to a reduction in the operating rate of the rolling process.

  For rolling bearings for continuous casting machines used under severe conditions such as low speed and high load, the rolling elements and inner and outer rings are made of alloy steel containing Cr, V, Mo, etc. It has been proposed that carburizing treatment and carbonitriding treatment be performed on the steel to suppress wear of rolling elements and inner and outer rings (see, for example, Patent Documents 2 and 3). In what was described in patent document 2, what contained Cr: 8-20 mass% as an alloy steel was used, and what was described in patent document 3 WHEREIN: Cr: 0.5-3.0 mass as alloy steel %, V: 0.6 to 2.0% by mass, Mo: 3.0% by mass or less, Ni: 2.0% by mass or less, and a bearing containing a lubricant-containing polymer. ing.

JP 2002-206545 A JP-A-9-264328 JP 2001-323938 A

  Rolling bearings for continuous casting machines in which the rolling elements and inner and outer rings described in Patent Documents 2 and 3 are formed of alloy steel containing Cr, V, Mo, etc., and carburized or carbonitrided on the surface thereof, There is a problem that the material cost and the heat treatment cost increase, and the bearing becomes expensive. Moreover, since the thing described in patent document 3 is filled with the lubricant containing polymer inside a bearing, an extra effort is required for the assembly of a bearing, and a bearing becomes further expensive.

  Therefore, an object of the present invention is to suppress wear of rolling elements and inner and outer rings by an inexpensive means, and to extend the replacement cycle of a rolling bearing for a continuous casting machine.

  In order to solve the above problems, the present invention supports a guide roll that guides a slab of a continuous casting machine, and a grease is sealed inside a bearing in which a plurality of rolling elements are arranged between inner and outer rings. In a rolling bearing for a casting machine, a configuration was adopted in which the grease was a base grease in which a base oil was mixed with a thickener and an alkali metal salt of molybdic acid was added.

  The inventors of the present invention, when added to the base grease, react with the newly formed iron-based metal surface exposed by wear when the steel forming the rolling elements and the inner and outer rings is slid. From the surface analysis results of the sliding surfaces, it was found that these films produce films containing iron oxide and molybdenum oxide. It was confirmed to have Based on such knowledge and confirmation, wear of rolling elements and inner and outer rings is suppressed by inexpensive means, and the replacement cycle of the rolling bearing for continuous casting machine can be extended.

  Typical examples of the alkali metal salt of molybdic acid include potassium molybdate, sodium molybdate, lithium molybdate, and the like. Since the alkali metal salt of molybdic acid is a solid insoluble in oil, it exists in the grease in a dispersed state in the same manner as a solid lubricant such as molybdenum disulfide. As described above, the alkali metal salt of molybdic acid reacts with the iron-based metal nascent surface to form a film containing iron oxide and molybdenum oxide. Although the mechanism by which this film exerts an effect of suppressing wear is not clear, it is considered that molybdenum oxide in the film has an effect of suppressing wear.

  The addition amount of the alkali metal salt of molybdic acid is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass with respect to the entire grease. This is because when the amount added is less than 0.1% by mass, a film containing molybdenum oxide is not sufficiently formed, and when it exceeds 20% by mass, the effect of suppressing wear of this film reaches its peak. In addition, although the particle diameter of the alkali metal salt of molybdic acid generally obtained as an industrial product is about 200 μm, the smaller the particle diameter, the easier it is to react with the iron-based metal nascent surface, so the particle diameter should be 50 μm or less. Is preferred.

  Base oils of the grease include mineral oils such as naphthenic, paraffinic, liquid paraffin, hydrodewaxed oil, polyglycol oil such as polyalkylene glycol, ether-based synthetic oil such as alkyl diphenyl ether and polyphenyl ether, diester Oils, ester synthetic oils such as polyol ester oils, silicone oils such as polydimethylsiloxane and polyphenylmethylsiloxane, GTL base oils, hydrocarbon synthetic oils such as poly-a-olefin oils, fluorine oils, etc. Mixed oils can be used. Among these, naphthenic and paraffinic mineral oils are more preferable because they are inexpensive and easy to use industrially and do not deteriorate the rubber forming the seal member of the rolling bearing.

  The blending ratio of the base oil is preferably 50 to 98.9% by mass, and more preferably 70 to 96.9% by mass with respect to the entire grease. This is because if the blending ratio of the base oil is less than 50% by mass, the grease becomes hard and the lubricity at low temperatures deteriorates, and if it exceeds 98.9% by mass, the grease becomes soft and easily leaks from the inside of the bearing.

  Examples of the thickener include soaps such as lithium soap, lithium complex soap, calcium soap, calcium complex soap, aluminum soap, and aluminum complex soap, and urea compounds such as diurea compounds and polyurea compounds.

  The blending ratio of the thickener is preferably 1 to 40% by mass, more preferably 3 to 25% by mass, based on the entire grease. This is because if the blending ratio of the thickener is less than 1% by mass, the thickening effect is insufficient and it is difficult to form grease, and if it exceeds 40% by mass, the grease becomes too hard.

  In addition, a well-known additive can be added to the grease mentioned above as needed. This additive includes solid lubricants such as molybdenum disulfide and graphite, antioxidants such as amines and phenolic compounds, rust inhibitors such as petroleum sulfonates, dinoninaphthalene sulfonates, sorbitan esters, sulfurized fats and oils, sulfides Sulfur compounds represented by olefins, thiophosphates, sulfur-phosphorus compounds represented by thiophosphates, extreme pressure agents such as phosphorus compounds represented by tricresyl phosphate, metal sulfonates, metal phosphates, etc. Detergent dispersants, friction reducers such as organic molybdenum, wax compounds, fatty acid amides, fatty acids, amines, oils such as fats and oils, metal deactivators such as benzotriazole and sodium nitrite, polymethacrylate, polystyrene, etc. Viscosity index improvers, etc. are listed, and two or more of these are combined It can also be added Te.

ここに、Ｒ^１およびＲ^３は、炭素原子数４〜２４の直鎖アルキル基またはシクロヘキシル基であり、Ｒ^１およびＲ^３は同一のものであってもよい。また、Ｒ^２は炭素原子数６〜１５の芳香族系炭化水素基である。 By using the thickener as a diurea compound represented by the chemical formula (1), it is possible to further suppress wear of the rolling elements and the inner and outer rings.

Here, R ¹ and R ³ are a linear alkyl group having 4 to 24 carbon atoms or a cyclohexyl group, and R ¹ and R ³ may be the same. R ² is an aromatic hydrocarbon group having 6 to 15 carbon atoms.

  The diurea compound is obtained by a reaction of an isocyanate compound such as a diisocyanate and an amine compound such as a monoamine, and these can be reacted in a base oil to produce a base grease. In order not to leave a reactive free radical, the isocyanate group of the isocyanate compound and the amino group of the amine compound are preferably blended so as to be approximately equivalent.

  Examples of the diisocyanate include phenylene diisocyanate, diphenyl diisocyanate, phenyl diisocyanate, diphenyl metadiisocyanate, octadecane diisocyanate, decane diisocyanate, and hexane diisocyanate. Examples of monoamines include octylamine, dodecylamine, hexadecylamine, octadecylamine, stearylamine, oleylamine, aniline, p-toluidine, cyclohexylamine, etc. Among them, octylamine, octadecylamine and cyclohexylamine Is particularly preferred.

  The inside of the bearing in which the grease is sealed is preferably sealed with a contact seal.

  Further, the continuous casting machine of the present invention supports a guide roll for guiding a continuously cast slab with any of the above-described rolling bearings, thereby enabling the replacement period of the rolling bearings to be extended, and the operating rate thereof. It was made possible to improve.

  The rolling bearing for a continuous casting machine according to the present invention is an inexpensive means because the grease enclosed in the bearing is made by adding an alkali metal salt of molybdic acid to a base grease containing a base oil and a thickener. Thus, the wear of the rolling elements and the inner and outer rings can be suppressed, and the replacement cycle of the rolling bearing for the continuous casting machine can be extended.

ここに、Ｒ^１およびＲ^３は、炭素原子数４〜２４の直鎖アルキル基またはシクロヘキシル基であり、Ｒ^１およびＲ^３は同一のものであってもよい。また、Ｒ^２は炭素原子数６〜１５の芳香族系炭化水素基である。 By using the thickener as a diurea compound represented by the chemical formula (1), it is possible to further suppress wear of the rolling elements and the inner and outer rings.

Here, R ¹ and R ³ are a linear alkyl group having 4 to 24 carbon atoms or a cyclohexyl group, and R ¹ and R ³ may be the same. R ² is an aromatic hydrocarbon group having 6 to 15 carbon atoms.

  In the continuous casting machine of the present invention, since the guide roll for guiding the continuously cast slab is supported by any of the above-described rolling bearings, the operating period is improved by extending the replacement period of the rolling bearings. In an ironworks that employs a system that directly sends a continuously cast slab to a lower rolling process, the operating rate of the rolling process can also be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a continuous casting machine using a rolling bearing for a continuous casting machine according to the present invention. In this continuous casting machine, molten steel placed in a ladle 21 is cast into a mold 23 via a tundish 22, and a cast piece 24 continuously cast in the mold 23 is pulled down by a pinch roll 25 and pulled out. The cast slab 24 is cooled while being guided in a curved shape by a number of guide rolls 26, and the slab 24 cooled and solidified as a whole is cut into a predetermined length by a torch 27.

  FIG. 2 shows a shaft end portion of a guide roll 26 supported by a self-aligning roller bearing 1 as a rolling bearing for a continuous casting machine according to the present invention. The self-aligning roller bearing 1 is configured by holding a barrel-shaped roller 4 by a cage 5 between a spherical raceway surface 2a of an outer ring 2 and two rows of raceway surfaces 3a of an inner ring 3 and arranging them in two rows. The inside of the bearing in which the grease A is sealed is sealed with a contact seal 6. The outer ring 2 is fitted into the bearing box 11, the inner ring 3 is fitted to the shaft end portion of the guide roll 26, and the inside of the bearing box 11 is connected to the ring members 12 a and 12 b that fix both ends of the inner ring 3. It is sealed with an oil seal 13 disposed therebetween. Although illustration is omitted, grease A is also sealed inside the bearing housing 11.

  The grease A is obtained by adding an alkali metal salt of molybdic acid to a base grease in which a diurea compound represented by the chemical formula (1) is added as a thickener to a base oil of naphthenic mineral oil.

  As shown in Table 1, as examples, nine types of greases in which an alkali metal salt of molybdic acid is added to a base grease in which the diurea compound represented by the chemical formula (1) is blended as a thickener in mineral oil of the base oil. (Examples 1 to 9) were prepared. In addition, as comparative examples, the same base grease with nothing added (Comparative Example 1) and those with the addition of molybdenum compounds of calcium molybdate, zinc molybdate and molybdenum trisulfide, respectively (Comparative Examples 2 to 4) Also prepared.

The base grease 1 used in Examples 1, 3, 5 and Comparative Examples 1 to 4 was diphenylmethane-4, 4′-diisocyanate in 2000 g of mineral oil (kinematic viscosity at 100 ° C. of 13.5 mm ² / sec). 60.6 g is reacted with 31.3 g of octylamine and 66.2 g of stearylamine, and the resulting diurea compound is uniformly dispersed. The base grease 2 used in Examples 2, 4, and 6 was composed of 2000 g of the same mineral oil as that of the base grease 1 and 158.2 g of diphenylmethane-4,4′-diisocyanate, 81.3 g of octylamine, and 58.aniline. The base grease 3 used in Examples 7 to 9 was obtained by reacting 9 g with the resulting diurea compound, and in the same mineral oil 2000 g, diphenylmethane-4, 4′-diisocyanate 60.3 g And 65.5 g of stearylamine and 24.1 g of cyclohexylamine are reacted to uniformly disperse the produced diurea compound.

  In addition, the alkali metal salts of molybdic acid added to the base grease of each example are sodium molybdate in Examples 1, 2, and 7, potassium molybdate in Examples 3, 4, and 8, and Examples 5, 6, and 9. Is lithium molybdate. The addition amount of the molybdic acid alkali metal salt of each of these Examples and the molybdenum compound of each of Comparative Examples 2 to 4 was 2% by mass of the entire grease, and each base grease added with these was added to a three-stage roll mill. JIS consistency No. The grease of each example and comparative example was obtained by adjusting to one grade (consistency: 310 to 340).

The SRV reciprocating friction and wear test in which the balls are reciprocated and slid on the disks using the greases of the above-described examples and comparative examples was measured, and the wear width of each disk after the test was measured. The wear suppression performance was compared. The test conditions are as follows. The material of the ball and the disk was high carbon chrome bearing steel SUJ2.
・ Load: 800N
・ Amplitude: 1 mm
・ Frequency: 20Hz
・ Test time: 5 hours

  The results of the SRV reciprocating friction and wear test are also shown in Table 1. In the case of using the grease of each comparative example, the wear width of the disk is 1.19 to 1.30 mm, which is significantly larger than 1 mm, whereas in the case of using the grease of each example, the wear of the disk is It can be seen that the width is reduced to 0.55 to 0.75 mm, almost half of each comparative example, and has excellent wear suppression performance. The mechanism of this wear suppression is not clear, but as a result of surface analysis of the sliding surface of the disk after the test, it was observed that a film containing iron oxide and molybdenum oxide was formed in each example. Therefore, it is considered that the molybdenum oxide in this film exerted the effect of suppressing wear.

  In the embodiment described above, the rolling bearing for the continuous casting machine that supports the guide roll is a self-aligning roller bearing. However, the rolling bearing for the continuous casting machine according to the present invention is a cylindrical roller bearing with a centering ring, divided into two. Other rolling bearings such as a cylindrical roller bearing may be used.

1 is an external perspective view showing a continuous casting machine using a rolling bearing for a continuous casting machine according to the present invention. The longitudinal cross-sectional view which shows embodiment of the rolling bearing for continuous casting machines which supports the axial end part of the guide roll of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Self-aligning roller bearing 2 Outer ring 3 Inner ring 2a, 3a Raceway surface 4 Roller 5 Cage 6 Contact seal 11 Bearing box 12a, 12b Ring member 13 Oil seal 21 Ladle 22 Tundish 23 Mold 24 Cast slab 25 Pinch roll 26 Guide roll 27 Torch

Claims (4)

  In a rolling bearing for a continuous casting machine that supports a guide roll for guiding a slab of a continuous casting machine and in which grease is sealed inside a bearing in which a plurality of rolling elements are arranged between inner and outer rings, the grease is used as a base oil. A rolling bearing for a continuous casting machine, characterized in that an alkali metal salt of molybdic acid is added to a base grease formulated with a thickener. The rolling bearing for a continuous casting machine according to claim 1, wherein the thickener is a diurea compound represented by chemical formula (1).

Here, R ¹ and R ³ are a linear alkyl group having 4 to 24 carbon atoms or a cyclohexyl group, and R ¹ and R ³ may be the same. R ² is an aromatic hydrocarbon group having 6 to 15 carbon atoms.   The rolling bearing for a continuous casting machine according to claim 1 or 2, wherein the inside of the bearing in which the grease is sealed is sealed with a contact seal.   A continuous casting machine characterized in that a guide roll for guiding a continuously cast slab is supported by the rolling bearing according to any one of claims 1 to 3.

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