JPH11236922A - Ball bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ball bearing capable of reducing the quantity of the lubricant without hindering the lifetime, reliability and stillness of the ball bearing and capable of sufficiently lowering the friction torque. SOLUTION: A side gap between an inner and an outer rings 1, 3 of a ball bearing provided with a ball 5 between the inner and the outer rings 1, 3 is sealed with a seal plate 7, and a space between the inner and the outer rings is lubricated by the lubricant, and a ball 5 made of ceramic is used. Each surface of the inner ring and the outer ring is formed with a metal film layer 8 of any one of titanium nitride, ohromium nitride, titanium carbide, and tungsten carbide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ball bearing, and more particularly to a ball bearing which has a small friction torque and is suitable for use at high speed rotation.

[0002]

2. Description of the Related Art Conventional ball bearings
Metals such as high carbon chromium bearing steel and martensitic stainless steel are generally used as the material of the inner and outer rings and balls, and the inner and outer rings are lubricated with an organic lubricant such as grease. In many cases, ball bearings used at high speed require a small friction torque, and the friction torque is reduced by reducing the amount of the lubricant to reduce the viscous resistance.

However, when the amount of the lubricant is reduced in the conventional ball bearing, the lubricity between the inner and outer rings and the ball is impaired, seizure occurs, and the inner and outer rings and the ball are made of material due to frictional heat during rotation. In some cases, the metal itself has deteriorated, or the rolling grooves and balls of the inner and outer rings have been worn or deformed, resulting in reduced rotational accuracy and rotational noise. Therefore, in the conventional ball bearing, when the amount of the lubricant is reduced, the friction torque is reduced, but sufficient life, reliability and quietness of the ball bearing cannot be obtained.

[0004] If the inner and outer rings and balls are all made of ceramics having high heat resistance, deterioration due to frictional heat, wear and deformation due to friction can be prevented.
Ceramics have high hardness and poor workability, and especially those that must be processed into complex shapes such as inner and outer rings require a lot of time and labor to process, and also have high carbon chromium bearing steel and martensitic stainless steel. However, it is not practical due to the problem that the price is higher than the materials used for conventional bearings and the production cost is high.

[0005]

The object of the present invention is to solve the above-mentioned problems of the conventional ball bearing, to reduce the amount of lubricant without impairing the life, reliability and quietness of the ball bearing, and to reduce the friction torque. An object is to provide a ball bearing that can be made sufficiently small.

[0006]

In order to achieve the above object, a ball bearing according to the present invention comprises a ball bearing having a ball between the inner and outer rings, and a side gap between the inner and outer rings of the ball bearing is closed by a seal plate to lubricate the inner and outer rings. The ball is made of a ceramic material, and a metal coating layer is formed on the surface of the inner ring and the outer ring.

Further, in the ball bearing according to the present invention, the side gap between the inner and outer rings of the ball bearing having a ball between the inner and outer rings is closed with a seal plate, and the inner and outer rings are lubricated with a lubricant. In addition to being made of ceramics, a metal coating layer is formed on the surface of each rolling groove of the inner ring and the outer ring. Further, the metal coating layer is made of any one of titanium nitride, chromium nitride, titanium carbide, and tungsten carbide.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a ball bearing according to an embodiment of the present invention. A plurality of balls 5 are arranged between an inner rolling groove 2 formed on the outer peripheral surface of the inner race 1 and an outer rolling groove 4 formed on the inner peripheral surface of the outer race 3. Are held by a retainer 6, and these inner and outer rings 1, 3, the ball 5, and the retainer 6
Are lubricated with an organic lubricant made of, for example, grease.

Further, a side gap between the inner and outer rings 1 and 3 is closed by a seal plate 7, and the outer periphery of the seal plate 7 is formed from the left and right edges of the inner peripheral surface of the outer ring 3. The inner periphery of the seal plate 7 faces the outer peripheral surface of the inner ring 1 with a very small gap such that the lubricant does not leak out.

[0010] In the ball bearing according to the present invention,
The inner and outer rings 1 and 3 are made of, for example, martensitic stainless steel such as SUS440C, and the balls 5 are made of, for example, ceramics such as silicon nitride, sialon, or alumina.

The rolling grooves 2, 4 in the inner and outer rings
On the surface of the metal film layer 8 of titanium nitride (TiN) by, for example, ion plating by physical vapor deposition (PVD).
Is formed, and the thickness of the metal coating layer is about 1 to 20 μm.

When the metal coating layer 8 is formed by ion plating, when the metal coating layer is formed, metal ions collide with the base (in the present embodiment, the inner and outer rings), and the impact causes dust and other impurities on the surface of the base. Since the fine particles are repelled and the cleanliness is increased, the degree of adhesion of the metal coating layer is high, and a metal coating layer that is difficult to peel off can be formed. In addition, in ion plating, the temperature of the substrate does not need to rise so much (several hundred degrees or less), so that there is a merit that metal deformation and distortion of the substrate due to the influence of heat hardly occur.

The reason why the thickness of the metal coating layer is set to about 1 to 20 μm is that if the thickness of the metal coating layer 8 is less than 1 μm, the hardness of the metal coating layer becomes insufficient and the wear resistance is reduced. Also, when the thickness exceeds 20 μm, the metal coating layer is easily peeled off.

In the ball bearing configured as described above,
Since the metal coating layer 8 made of titanium nitride is formed on the surface of each of the rolling grooves 2 and 4 of the inner and outer rings 1 and 3, the hardness of the rolling groove surface is large and the wear resistance is improved. Since it is made of ceramics, it has high abrasion resistance and heat resistance.Therefore, even if the amount of lubricant is reduced and the friction torque is reduced, wear and deformation of the rolling grooves and balls are less likely to occur, and the life is longer. It is possible to provide a ball bearing that is long, has high reliability, and is excellent in quietness.

In the embodiment described above, the inner and outer rings 1, 3
The metal coating layer 8 is formed only in the rolling grooves 2 and 4 of
A metal coating layer made of, for example, chromium nitride (CrN) may be formed on the entire surface of the inner and outer rings.

The chromium nitride is particularly excellent in corrosion resistance. By forming a metal coating layer made of chromium nitride on the entire surface of the inner and outer rings, the corrosion resistance of the entire ball bearing is improved.
The ball bearing can be used even in a corrosive atmosphere and has a wide application range.

In the above embodiment, the metal coating layer 8 is formed by ion plating.
Physical vapor deposition (PVD) other than ion plating,
Alternatively, the metal coating layer may be formed by a chemical vapor deposition (CVD) method. Further, in the above-described embodiment, titanium nitride (TiN) and chromium nitride (CrN) are cited as the metal constituting the metal coating layer, but the metal coating layer is formed by using tungsten carbide (WC) or titanium carbide (TiC). Is also good.

The inner and outer rings are made of martensitic stainless steel SUS440C. This martensitic stainless steel has excellent corrosion resistance, high hardness and good wear resistance. High carbon chromium bearing steel can also be used.

[0019]

In the ball bearing according to the present invention, since the metal coating layer is formed on the surface of each rolling groove of the inner and outer races, the hardness of the rolling groove surface is large, and the wear resistance is improved. Moreover, since the balls are made of ceramics, they have high wear resistance and heat resistance.Thus, even if the amount of lubricant is reduced and the friction torque is reduced, the rolling grooves and balls are less likely to be worn or deformed. It is possible to provide a ball bearing having a long life, high reliability, and excellent quietness.

When both the inner and outer races and the ball are made of metal as in a conventional ball bearing, transfer may occur due to metal contact and deformation may occur. Is made of ceramics, the transfer is less likely to occur, which also reduces the risk of deformation of the inner and outer rings and balls.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal sectional view showing an embodiment of a ball bearing according to the present invention.

[Explanation of symbols]

 1: inner ring 2: inner ring rolling groove 3: outer ring 4: outer ring rolling groove 5: ball 6: retainer 7: seal plate 8: metal coating layer

Claims (3)

[Claims] 1. A ball bearing having a ball between inner and outer rings, wherein a side gap between the inner and outer rings is closed with a seal plate to lubricate the inner and outer rings with a lubricant, and the ball is made of ceramic. A ball bearing comprising a metal coating layer formed on the surface of the inner ring and the outer ring. 2. A ball bearing having a ball between inner and outer rings, a side gap between the inner and outer rings is closed with a seal plate to lubricate the inner and outer rings with a lubricant, and the ball is made of ceramic. A ball bearing comprising a metal coating layer formed on the surface of each rolling groove of the inner ring and the outer ring. 3. The ball bearing according to claim 1, wherein the metal coating layer is made of any one of titanium nitride, chromium nitride, titanium carbide, and tungsten carbide.