JPH07103247A - Rolling bearing - Google Patents

Abstract

PURPOSE:To provide good rotational torque and a good vibration characteristic and to reduce noise by using a metallic lubricant, to prevent a.bearing ring and a rolling element from corroding so as to prolong the life, and to prevent the metallic lubricant from flowing out so as to make a rolling bearing suitable to the use under a high cleanliness environment. CONSTITUTION:In a rolling bearing 1 using a metallic lubricant 6, which is melted to be in liquid phase at the predetermined temperature, an inner bearing ring 2, an outer bearing ring 3, and a rolling element 4 are formed of ceramics mainly consisting of steel or silicon nitride, and in the inner bearing ring 2 and the outer bearing ring 3, a film 7 made of a nonreactive material on the metallic lubricant 6 covers at least the inner bearing ring 2 outer circumferential face, the outer bearing ring 3 inner circumferential face, and the rolling element 4 surface, while sealing members 5, 5 are installed on axial directional both sides between the inner bearing ring 2 and the outer bearing ring 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing using a metal lubricant which is melted at a predetermined temperature to be in a liquid phase state, and more particularly, to prevent corrosion by the metal lubricant and prevent outflow of the metal lubricant. Regarding what was given.

[0002]

2. Description of the Related Art Conventionally, a fluid lubricant such as grease or a solid lubricant such as a soft metal has been known as a lubricant used for a rolling bearing.

Since the fluid lubricant is liable to flow out to the outside of the bearing minutely during operation and has a high vapor pressure, it cannot be used for rolling bearings used in a high cleanliness environment such as vacuum equipment. For this reason, a solid lubricant tends to be used as the rolling bearing used in the environment.

However, in general, a rolling bearing using a solid lubricant has poorer rotational torque and vibration characteristics as compared with a rolling bearing using a fluid lubricant, generates a large amount of noise, and separates the solid lubricant with rotation. Because it is easy to do
There is a problem that the life as a rolling bearing is short. In addition, since minute abrasion powder due to the peeling may come out of the bearing, it is not optimal for use in a high cleanliness environment.

Therefore, the inventors of the present application, as an alternative to the solid lubricant, have a predetermined temperature (temperature during operation).
We considered using a metal lubricant that melts in the liquid state in the rolling bearing for rolling bearings. With this, compared to a rolling bearing using a solid lubricant, it has excellent rotational torque and vibration characteristics, and can have low noise.

[0006]

However, when the above metal lubricant is used, the following problems occur. Metallic lubricants are Ga or Ga alloys, but these easily corrode the steel materials used for the inner and outer races and rolling elements, so that the raceways will be damaged in a short period of time. Becomes significantly shorter. Further, since it is premised on use in a high cleanliness environment, it is necessary to take measures to prevent the metal lubricant in the liquid phase from flowing out.

In view of the above circumstances, the present invention uses a metal lubricant to provide excellent rotational torque and vibration characteristics and low noise, but at the same time, to prevent corrosion of the races and rolling elements and to provide a long service life. The purpose of this is to prevent the metal lubricant from flowing out and to make it suitable for use in a high cleanliness environment.

[0008]

According to the present invention, in a rolling bearing using a metal lubricant which melts at a predetermined temperature to be in a liquid phase state, the inner and outer rings and rolling elements are mainly made of steel or silicon nitride. Of the inner and outer rings, at least the inner ring outer peripheral surface, the outer ring inner peripheral surface, and the surface of the rolling element are coated with a film made of a material that does not react with the metal lubricant. The seal members are attached to both sides in the axial direction.

The metal lubricant is preferably Ga or Ga alloy, and the coating film is preferably Mo, Ta or W.

[0010]

In summary, when a metal lubricant that melts at a predetermined temperature to be in a liquid phase is used, it is devised to prevent corrosion of the inner and outer races and rolling elements and to ensure the hermeticity. Therefore, compared with the case where a solid lubricant is used, the rotation torque and vibration characteristics are excellent, the noise is low, and the corrosion of inner and outer races and rolling elements is suppressed as much as possible to achieve a long life.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the embodiments shown in FIGS. FIG. 1 is a vertical cross-sectional side view of a rolling bearing, in which 1 denotes the entire rolling bearing including a deep groove type full ball bearing. This rolling bearing 1 is provided with an inner ring 2, an outer ring 3, a plurality of rolling elements 4 composed of balls, and two seal members 5 and 5. In an annular space surrounded by the inner / outer rings 2 and 3 and the seal member 5, for example, A metal lubricant 6 made of Ga or a Ga alloy (Ga-In, Ga-In-Sn, etc.) having a melting point of 25 [deg.] C. or less is filled and sealed.

Of these, the inner and outer rings 2, 3 and the rolling element 4
Is made of SUJ2, SUS, SKH, or ceramics mainly composed of silicon nitride, and the entire surface thereof is made of a material that does not react with the metal lubricant 6, such as Mo (molybdenum), Ta (tantalum), or W ( A film made of tungsten) is covered by, for example, a sputtering device. Reference numeral 7 is attached to this coating film. It is preferable to remove oxygen by performing hydrogen reduction treatment after forming the coating film 7 with a sputtering apparatus. In this coating film 7, once the metal lubricant 6 made of Ga or Ga alloy is bonded, it becomes difficult to separate it, so that the lubricity is further improved.

The seal member 5 is of a non-contact type such as a shield plate made of Mo (molybdenum) which is attached to the outer ring 3 so as to form a minute gap with respect to the outer peripheral surfaces of the inner ring 2 on both axial ends. Has been adopted. It is desirable to apply a wetting preventive agent (illustration, reference numeral omitted) mainly composed of, for example, titanium oxide to the surface of the seal member 5, and further, a minute gap is formed between the seal member 5 and the inner ring 2. It is desirable to apply the above-mentioned anti-wetting agent to the surface to be coated. The seal member 5 may be made of Ta (tantalum) or W (tungsten) in addition to Mo (molybdenum). When the usual carbon steel or SUS material is used, the coating film 7 is applied.

By the way, the rolling bearing 1 is used for an X-ray tube device 10 as shown in FIG. 2, for example. 1 in the figure
1 is an X-ray tube, 12 is a cathode member, 13 is an anode member, 14 is a cylindrical rotation shaft, 15 is a shaft-shaped support member, 16 is a rotor,
Reference numeral 17 is a stator, and 18 is a fluid metal. The rolling bearing 1 is interposed between the support member 15 and the rotary shaft 14 at two axially separated positions. The fluid metal 18 is the same as the metal lubricant 6 described above. The operation of the X-ray tube device 10 is that electrons generated by the cathode member 12 are accelerated at a high speed by an electrostatic field formed between the cathode member 12 and the anode member 13 to form an electron beam. By irradiating the anode member 13 with X-rays, X-rays are generated from the anode member 13 and emitted from the window 19 of the X-ray tube 11.

In such an X-ray tube device 10, the X-ray tube 1
When the rolling bearing 1 is used in such a high temperature environment, the clearance between the inner / outer rings 2 and 3 of the rolling bearing 1 and the rolling element 4 is taken into consideration when the rolling bearing 1 is used. It is desirable to set the (bearing gap) to a relatively large value such as C4 or more in accordance with the JIS standard. Also, in such a high temperature environment,
Since the rolling bearing 1 is filled with not only the rolling elements 4 but also the metal lubricant 6 between the inner and outer races 2 and 3, the thermal conductivity is good and the heat dissipation effect is excellent.

The present invention is not limited to the above-mentioned embodiments, and it goes without saying that it can be applied to various types of rolling bearings. Further, as the metal lubricant 6, in addition to Ga or Ga alloy described above, Bi-In-Pb-Sn alloy containing a relatively large amount of bismuth (Bi), or In-Bi alloy containing a relatively large amount of In. Or an In-Bi-Sn alloy. Furthermore, if the inner / outer rings 2, 3 and the rolling elements 4 are made of ceramics, even if a minute pinhole is present in the coating film 7, the inside will be corroded by the metal lubricant 6. Can be kept to a minimum.

In the above embodiment, the coating film 7 is applied to the entire surfaces of the inner and outer races 2 and 3, but it may be applied to at least the inner and outer circumferences of the outer race which are in contact with the metal lubricant 6.

[0018]

According to the present invention, by using a metal lubricant that melts at a predetermined temperature to be in a liquid state, the bearing ring and rolling elements are corroded while excellent in rotation torque and vibration characteristics and low noise. It is possible to prevent the metal lubricant from flowing out while making it suitable for use in a high cleanliness environment.

In addition, since not only the rolling elements but also the metal lubricant is present between the inner and outer rings of the rolling bearing, the thermal conductivity is good and the heat dissipation is excellent, so that it is suitable for use in a high temperature environment. Becomes

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of a rolling bearing according to an embodiment of the present invention.

FIG. 2 is a vertical sectional side view of an X-ray tube device using the rolling bearing of this embodiment.

[Explanation of symbols]

 1 rolling bearing 2 inner ring 3 outer ring 4 rolling element 5 sealing member 6 metal lubricant 7 coating film

Claims (2)

[Claims] 1. A rolling bearing using a metal lubricant which is melted at a predetermined temperature to be in a liquid phase state, wherein the inner and outer rings and rolling elements are formed of steel or ceramics mainly composed of silicon nitride. At least the outer peripheral surface of the outer ring, the inner peripheral surface of the outer ring, and the surface of the rolling element are covered with a film made of a material that does not react with the metal lubricant, and sealing members are provided on both axial sides between the inner and outer rings. The rolling bearing is characterized in that. 2. The rolling bearing according to claim 1, wherein the metal lubricant is Ga or Ga alloy, and the coating film is Mo, Ta or W.