JP2963451B2 - Rolling bearing - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention supports a rotating member in a corrosive environment, for example, in a liquid of a molten metal treatment furnace, a molten metal plating bath and an electrolytic plating bath during alloy casting. The present invention relates to a rolling bearing used for a main shaft of a machine tool or the like. 2. Description of the Related Art For example, as a molten metal processing furnace for casting an alloy such as an aluminum alloy, as described in page 11 of the magazine "Metal" (Agne Co., Ltd., April 1980). The rotating cylinder is attached via a bearing to the outer periphery of the fixed shaft extending from the outside of the furnace into the molten alloy inside the furnace, and the molten alloy is agitated by the blades provided at the tip of the rotating cylinder, so that the molten metal is easily and uniformly formed. A structure having a structure to be formed is generally known. As the electrolytic plating tank, a vertical plating tank and the like are referred to as “'77 Ironmaking Machinery and Equipment Overview” (November 2, 1976
5th Heavy Industry Newspaper). That is,
The steel sheet is guided by a conductor roll and a hold down roll outside the electrolytic plating tank and a sink roll in the electrolytic solution of the plating tank, and an anode rod in the electrolytic solution,
The surface of the steel sheet is electroplated by energization with the steel sheet via a conductor roll serving as a cathode. Both end shafts of the sink roll are fitted into the roll end fitting holes of the support member fixed to the upper end of the plating tank. A bearing is interposed between the rolls to prevent wear between the support member and the rolls. In addition, the machine tool spindle is required to rotate at a high speed in order to shorten the processing time or improve the surface finish of the surface to be processed. However, in a molten metal processing furnace, the rotating blades are in the molten metal alloy. Therefore, if a bearing is arranged between a rotating cylinder at the same position as the blades and a fixed shaft, the rotating blades may be fixed. Bearings are corroded and damaged early in a corrosive environment caused by a molten alloy. For this reason, conventionally, the end of the rotary cylinder has to be unavoidably extended above the liquid level of the molten alloy, and the rotary cylinder is rotatably supported by a fixed shaft via a bearing at the extension. Therefore, since the rotating cylinder has a long distance from the bearing portion to the blade portion, the rotating tube is in a cantilever support state with the bearing portion as a fulcrum, and the blade swings during rotation, resulting in poor stirring efficiency and uniform molten metal. Hateful. In the electrolytic plating tank, since the sink roll is in the electrolytic solution, the sink roll and the bearing are always in an environment corroded by the electrolytic solution. By the way, various countermeasures for preventing the corrosion of the sink roll have been conventionally taken, for example, by improving the material surface, but even in those cases, the countermeasure for preventing the corrosion of the bearing was not particularly considered. As a result, there was a risk that the bearing would become unusable early due to corrosion. If the bearing becomes unusable due to corrosion, the operation of the electrolytic plating apparatus must be stopped and the bearing must be replaced each time, resulting in a remarkable reduction in operation. Also, in machine tool spindles, when bearings are rotated at ultra-high speeds (dmN value of 1,000,000 or more) or during heavy cutting, conventional oil-lubricated steel bearings may seize and become unusable at an early stage. there were. SUMMARY OF THE INVENTION An object of the present invention is to provide a rolling bearing that can smoothly rotate a machine tool main shaft and the like and extend the life thereof, and can also improve seizure resistance, corrosion resistance, and wear resistance. Accordingly, in the present invention, an inner ring, an outer ring, and a plurality of rolling elements disposed between the inner and outer rings are provided, and the inner ring is fitted to the outer peripheral surface of a shaft member. A rolling bearing in which the outer ring is fitted to an inner peripheral surface of a fitting hole formed in an outer member provided around the shaft member, wherein at least the inner ring and the outer ring are made of ceramic; And a gap between the shaft member and the shaft member,
An intermediate fit is provided between the outer race and the outer member. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail based on an embodiment shown in FIG. Reference numeral 1 denotes a rotating shaft as an inner member used in a corrosive environment, and its end is fitted in a shaft fitting hole 3 of an outer member 2 which is a non-rotating member. The end of the rotating shaft 1 is formed in a small-diameter stepped portion 4, and the inner peripheral surface of the shaft fitting hole 3 of the outer member 2 has a large-diameter stepped portion facing the stepped portion 4. A stepped portion 5 is formed. An inner ring 7 having heat resistance and corrosion resistance is fitted on the outer peripheral surface of the stepped portion 4 of the rotating shaft 1 so as to contact the stepped shoulder portion 4a, and the shaft fitting hole 3 of the outer member 2 is provided. An outer ring 8 having heat resistance and corrosion resistance is fitted to the inner peripheral surface of the stepped portion 5 so as to abut the stepped shoulder portion 5a and face the inner ring 7. The inner ring 7 includes a raceway portion 7a, and flanges 7b and 7c extending radially outwardly formed at the both ends of the raceway portion 7a. The outer race 8 includes a raceway portion 8a and a shoulder 5a of the outer member 2. A flange 8c is provided separately on the side and extends inward in the radial direction, and a flange 8b is formed on the opposite side to the shoulder 5a and is formed integrally with the track portion 8a and extends inward in the radial direction. Inner and outer rings 7,
The bearing cylindrical roller 9 made of ceramics, which is a heat-resistant and corrosion-resistant member, is provided on the outer circumference 10 of the inner raceway part 7a and the outer raceway part 8a on the inner circumference of the annular space between the raceways 7a, 8a. Are arranged so as to be able to roll with respect to the inner peripheral surface 11. Thus, a bearing 6 for rotatably supporting the rotating shaft 1 is formed. When rolling, the cylindrical roller 9 rolls the flange 7 b of the inner ring 7,
7c and the inner surfaces of the flanges 8b and 8c of the outer ring 8 guide the guide. Further, the inner ring raceway portion 7a and the flanges 7b, 7
c, and the respective boundary corners of the outer ring raceway portion 8a and the flange 8b are not provided with a slack like a conventional bearing, and have a radius R substantially equal to or slightly smaller than the chamfering radius of the cylindrical roller 9. Department. In the embodiment, there is no problem even if the structure is such that the cylindrical rollers 9 are held at equal intervals by a retainer. Of course, in this case, the cage is made of a heat and corrosion resistant material. 12 is a retaining ring for fixing the inner ring 7, and 13 is a sleeve for fixing the outer ring 8.
In the above-described embodiment, the case where the inner member is the rotating shaft 1 and the outer member 2 is the non-rotating member that rotatably supports the rotating shaft 1 has been described. On the contrary, the shaft 1 as the inner member is the non-rotating shaft. In some cases, the outer member 2 may be a rotating member that is rotatably supported by the non-rotating shaft 1. The ceramics used as the cylindrical rollers 9 include silicon nitride (Si ₃ N ₄ ) formed by pressure sintering such as hot pressing, hot isostatic pressing, or atmospheric pressure sintering. Alternatively, using sialon, further, in the case of a silicon nitride sintered body, since silicon nitride is a typical hard-to-sinter material, rare earth metal oxides, particularly preferably yttria (Y ₂ O ₃ ), If necessary, for example, aluminum oxide such as Al ₂ O ₃
The following addition and firing show good sinterability,
Desirable in terms of high strength and good rolling life. First
Table 3 and FIG. 3 show the crushing strength of the ceramic balls to which the yttria and the aluminum oxide of the present invention are added as a sintering aid for silicon nitride and the conventionally known ceramic balls to which magnesium oxide is added. 3 shows a comparison of the service life. As shown in FIG. 2, the test was performed with a load of 100 kgf, a rotation speed of 1200 rpm, a lubricating oil: spindle # 60, a ball diameter of 3/8 inch, and the number of balls: three. [Table 1] As is clear from Table 1 and FIG. 3, the product of the present invention is superior in both the crushing strength and the rolling life. Further, the sintering aid of the present invention described above, as the compounding ratio with respect to silicon nitride increases,
Although sintering is easy, the corrosion resistance to the electrolyte and the like is inferior. Therefore, it is preferable to add 10% or less as described above. In particular, the total amount of yttria and aluminum oxide is 10%. It is preferred that: Further, if necessary, aluminum nitride of 10% or less, or titanium oxide, zirconium oxide, magnesium oxide, molybdenum carbide, spinel, garnet or the like may be appropriately added, preferably at 5% or less, to improve sinterability. It is effective in terms of. FIG. 4 shows the corrosion resistance test values of the silicon nitride sintered body used in the present invention.
The test value is expressed as a weight loss rate when the test material is immersed in a 1 mol HCl aqueous solution at 80 ° C. Table 2 shows the components of each test material. [Table 2] As is apparent from FIG. 4, the silicon nitride sintered body used in the present invention has a lower weight reduction rate than the comparative example, which means that the silicon nitride sintered body has good corrosion resistance. It is nothing but being. Next, in the case of a corrosive environment at a relatively low temperature, for example, in the case of casting of an alloy of lead or zinc or electrolytic plating, since the corrosiveness is not so severe, only the cylindrical roller 9 is formed of ceramics, and the inner ring 7 and the outer ring 8 are formed. It is sufficient to be formed of a metal having corrosion resistance such as stainless steel. However, in a very corrosive environment irrespective of high or low temperature, for example, in the case of a molten metal treatment furnace for aluminum alloy or aluminum electrolytic plating, it is not sufficient to form only the cylindrical rollers 9 of ceramics. Is best formed of ceramics or, for example, in the case of molten zinc, after forming the inner ring 7 and the outer ring 8 from ordinary bearing steel, a corrosion-resistant coating of vanadium carbide, a chromium compound, etc. May be used. When the inner ring 7 and the outer ring 8 are formed of ceramics, the same material as that of the cylindrical roller 9 described above is used. Outer rings 7, 8
When the inner and outer rings 7 and 8 are assembled, the inner ring 7 and the rotating shaft 1 are set to a clearance fit of required dimensions, and the outer ring 8 and the outer member 2 are set to an intermediate fit. I have to put it. The reason is that ceramics have a smaller coefficient of thermal expansion than metal, so if the fitting dimension between the inner ring 7 and the rotating shaft 1 is tight, the rotating shaft
Since the inner ring 7 may be damaged due to thermal expansion, the inner ring 7 may be damaged in a radial direction. On the other hand, the outer ring 8 can maintain a good fit against thermal expansion of the outer member 2 at the time of use as the outer ring 8 is more closely fitted to the outer member 2, but in fact, ceramics are weaker in strength. Since the outer ring 8 may be broken at the time of press-fitting, the outer ring 8 is preferably set to an intermediate fit state in which the influence of press-fitting and the influence of thermal expansion of the outer member 2 can be minimized. Of course, when only the cylindrical rollers are made of ceramics, the above-described influence of thermal expansion can be avoided. In particular, when used for machine tool spindles and the like, the ceramic cylindrical roller of the present invention exhibits the excellent seizure resistance of ceramics against the metal of the inner and outer rings or the cage, and the corrosion resistance of rolling bearings,
The wear resistance can be improved, and the smooth rotation of the spindle and the extension of the life can be measured. Of course, the assembled state of the inner and outer rings 7 and 8 can be naturally applied to the case where the outer member 2 is a rotating member and the shaft 1 is a non-rotating member. As described above, according to the present invention, a rolling bearing excellent in heat resistance and corrosion resistance for use in a corrosive environment, or a smooth rotation and a prolonged life of a machine tool main shaft or the like can be provided. A rolling bearing capable of measuring and improving seizure resistance, corrosion resistance and wear resistance can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention. FIG. 2 is a diagram showing a test method of crushing strength and rolling life. FIG. 3 is a graph showing a test result of a rolling life. FIG. 4 is a graph showing the results of a corrosion resistance test. [Description of Signs] 1 ... Rotating shaft (shaft member) 2 ... Outer member 7 ... Inner ring 8 ... Outer ring 9 ... Rolling element

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kiyoshi Nakamura 8 Shinsugitacho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Inside the Yokohama Metal Works, Tokyo Shibaura Electric Co., Ltd. (72) Koichi Inoue 8 Shinsugitacho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Tokyo Shibaura Electric Co., Ltd. Yokohama Metal Factory (58) Field surveyed (Int.Cl. ⁶ , DB name) F16C 33/62 F16C 35/06

Claims (1)

(57) [Claims] An inner ring, an outer ring, and a plurality of rolling elements disposed between the inner and outer rings, wherein the inner ring is fitted to an outer peripheral surface of a shaft member,
In a rolling bearing in which the outer ring is fitted to an inner peripheral surface of a fitting hole formed in an outer member provided around the shaft member, at least the inner ring and the outer ring are formed of ceramics,
A rolling bearing, wherein a clearance fit is provided between the inner ring and the shaft member, and an intermediate fit is provided between the outer ring and the outer member.