JP2002195276A - Rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bearing capable of lowering nearing noise in use and also stably lubricating for a long time. SOLUTION: At least one of a raceway ring or a rolling body 14 is formed by steel material in the rolling bearing. A film laminated by a lubricating film 16B made of Ag and a lubricating film 16A made of Pb is formed on at least one of the raceway of the raceway ring or the rolling surface of the rolling body, which are made of steel material. The thickness of the lubricating film 16B made of Ag is 0.1 to 0.2 μm, and the thickness of the lubricating film 16A made of Pb is 0.1 to 0.5 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing, and more particularly, to a device used in a vacuum or high-temperature environment such as a rotary anode X-ray tube or a vacuum deposition device, or a bearing used in space. The present invention relates to a rolling bearing characterized by a formed lubricating film.

[0002]

2. Description of the Related Art Rolling bearings used in a vacuum or high-temperature environment cannot use a lubricant or grease. Therefore, a raceway surface and a rolling element formed on raceways such as an outer ring and an inner ring and slidingly contacting the rolling elements. It is known to coat a lubricating film made of a soft metal on at least one of a surface and a pocket surface for accommodating a rolling element of a cage. Silver (hereinafter Ag) and lead (hereinafter Pb) are known as soft metals for such a lubricating film. For example, in a rolling bearing such as a rotary anode X-ray tube employing a lubricating film composed of Ag and Pb, when used at an ambient temperature of 400 to 500 ° C., Ag is in a solid state and Pb is molten. The lubrication action is performed in the state. At such an ambient temperature, Pb, which performs a lubricating action in a molten state, is superior to Ag in terms of noise.

[0003] However, when the member constituting the bearing is made of steel, the wettability of the molten Pb to the steel is poor, and the molten Pb is melted on the coating portions such as the raceway surface of the bearing ring, the rolling element surface, and the pocket surface of the cage. Pb is not easily held in a film form. Then, as the use of the bearing progresses, the molten Pb is peeled off from the coated portion, and the lubricant is not supplied to the sliding contact portion of the bearing in sliding contact with the rolling element, so that the lubricating action between the bearing components is reduced. When the steel materials come into contact with each other, they tend to adhere to each other.

In order to solve the above-mentioned problems, Japanese Patent Application Laid-Open No. Hei 7-190067 discloses that the inner and outer races and rolling elements are formed of a steel material, and the surface of the rolling elements has tin (S
n) A rolling bearing in which an intermediate layer is coated with a three-layered lubricating film of Ag and an uppermost layer of Pb is proposed. In the rolling bearing having such a configuration, when the rolling bearing is used in a high-temperature atmosphere, Ag as the intermediate layer is mixed in a state where Pb as the uppermost layer and Sn as the lowermost layer are melted and mixed. Will be. In this melt-mixed state, Ag acts as a binder (binder) between the Pb-Sn alloy and the steel material, so that the molten lubricant has an appropriate wetting on the surfaces of the rolling elements and the raceway surfaces of the inner and outer rings. Ensure the nature. In other words, the lubricant melted and mixed from the rolling element itself or the rolling element is transferred to the raceway surfaces of the inner and outer rings, where it is easily held in a film form, so that the contact area between the rolling element and the raceway surface of the inner and outer rings is stable. Lubricated.

[0005]

However, in the rolling bearing having such a structure, although the wettability of the molten Pb to the steel material is improved by Ag acting as a binder between the molten Pb and the steel material, It is considered that the surface and the rolling element are in a boundary lubrication state. In the boundary lubrication state, contact between the base material of the raceway surface and the rolling element occurs, so that wear of the base material is unavoidable. In some cases, the bearing is removed from a covering portion such as the surface of the moving body, and there is a problem in terms of the life of the rolling bearing.

The present invention has been made in view of such a situation, and reduces noise during use of a bearing.
It is an object of the present invention to provide a bearing that can be stably lubricated for a long period of time.

[0007]

Means for Solving the Problems As a result of intensive studies, the present inventors have developed a rolling bearing in which a soft metal lubricating film is formed by laminating a rolling element and a contact surface where the rolling element contacts. By setting the thickness of the lubricating film made of soft metal within the specified range, it is possible to maintain good lubrication for a long time and reduce noise during use when used in a vacuum or high-temperature environment. I found it.

That is, an object of the present invention is to provide a rolling bearing in which a rolling element and a retainer for holding the rolling element are interposed between raceways formed of an outer race and an inner race. At least one of the rolling elements is made of steel,
A lubricating film made of Ag and a lubricating film made of Pb are laminated and formed on at least one of the raceway surface or the rolling element surface of a steel raceway, and the thickness of the Ag lubricating film is 0.1 to
0.2 μm, and the thickness of the Pb lubricating film is 0.1 to
It can be achieved by a rolling bearing characterized by being 0.5 μm.

Here, the retainer may be one having pockets for accommodating the rolling elements at intervals in the circumferential direction, but may be spacers interposed between the rolling elements adjacent to each other. Here, SKH4, SUS
440C, LNS125, ES1 (alloy component: 0.45
% C-13% Cr-0.14% N) stainless steel, but is not limited thereto. In addition, LNS125
In the case of stainless steel of ES1 or ES1, alloy components satisfying the following [Formula] are preferable because they do not generate a huge eutectic carbide. [Formula] C ≦ −0.05Cr% + 1.41 Here, the lubricating film is preferably formed by ion plating. Further, it is preferable that the thickness of the lubricating film made of Ag is smaller than the thickness of the lubricating film made of Pb.

According to such a rolling bearing, the soft metal Pb layer acts as a lubricating film at an ambient temperature lower than the melting point of Pb, and the Pb layer at an ambient temperature higher than the melting point of Pb. Is melted, and the layer of the soft metal Ag acts as a lubricating film. That is, the lubrication of the bearing can be improved over a wide temperature range, and the lubrication of the contact portion of the bearing can be maintained for a long period of time. Further, the thickness of the Pb film is 0.1 to 0.5 μm,
Since the thickness of the g film is set to 0.1 to 0.2 μm, by making the thickness of Ag smaller than the thickness of Pb,
It is possible to prevent a change in torque and an increase in sound due to an increase in the hardness of the film due to an increase in the Ag film thickness. That is, a low-noise bearing can be provided. Furthermore, even when the melting point of Pb is lower than the melting point of Pb, Pb alone is easily removed on the raceway because it is soft. However, by adding Ag, the coating is slightly hardened, so that it is difficult to be removed on the raceway and the life can be extended. . Therefore, Ag, which is excellent in terms of life,
The film thickness of Pb is set so that Pb, which is excellent in terms of torque stability and sound, is not increased so much while improving the life of Pb.

[0011]

FIG. 1 is a partial cross-sectional view of an angular type ball bearing (hereinafter referred to as a ball bearing) 10 according to a first embodiment of the present invention. As shown in FIG. 1, the ball bearing 10
It has a plurality of rolling elements 14 held by a retainer 13 between the outer ring 12 and the outer ring 12 and arranged at equal intervals along the circumferential direction of the ball bearing 10. In the present invention,
A bearing that does not use the retainer 13 may be used. The inner race 11 has a raceway surface 11A which is a concave groove for accommodating the rolling element 14 in a central portion of the outer peripheral surface of the inner race which is spaced apart from both ends in the axial direction. The outer ring 12 has a groove for accommodating the rolling element 14 at a central portion of the inner peripheral surface of the outer ring that is spaced apart from one end in the axial direction, and a slope inclined from the groove toward the other end. Track surface 12 consisting of a surface
A is formed. At this time, the rolling element 14 and the raceway surface 1
The contact angle with 2 A is a contact angle α with respect to the radial direction of the ball bearing 10. A lubricating film made of Pb and a lubricating film made of Ag are formed on the surface of the rolling element 14. At this time, the ball bearing 10 has an inner diameter of 8 mm and an outer diameter of 22 m.
m, width 7 mm, and contact angle α30 °.

FIG. 2 is a sectional view of a rolling element 14 used in the ball bearing 10 shown in FIG. Rolling element 14 shown in FIG.
Has a ball 15 and a lubricating film 16 formed on the surface 15A of the ball 15. The lubricating film 16 includes two layers, an upper layer 16A and a lower layer 16B, and an upper layer 16A made of Pb;
And a lower layer 16B made of Ag. Here, the thickness of the upper layer 16A is 0.3 μm, and the thickness of the lower layer 16B is 0.1 μm.

According to such a configuration of the present embodiment, when the ball bearing 10 is used at an ambient temperature equal to or lower than the melting point of Pb, Pb of the upper layer 16A of the rolling element 14 acts as a lubricating film, The lubrication of the ball bearing 10 is improved. When the ball bearing 10 is used at an ambient temperature higher than the melting point of Pb, Pb of the upper layer 16A is melted, and the lubrication by the molten metal and the soft metal Ag are performed.
The lower layer 16B made of serves as a lubricating film. That is, when the melting point of Pb is 327 ° C. or less, the upper layer 1 made of Pb
6A acts as a lubricating film, and at a temperature higher than the melting point of Pb, the lower layer 16B made of Ag acts as a lubricating film.
By doing so, the lubrication of the ball bearing 10 can be improved over a wide temperature range, and the lubrication of the contact portion of the ball bearing 10 can be maintained for a long period of time. Further, by making the film thickness of the Ag film smaller than the film thickness of Pb, it is possible to prevent the fluctuation of the torque and the rise of the sound due to the improvement of the hardness of the film accompanying the increase in the film thickness of Ag. , Ball bearing 10
Low noise can be achieved when using. In addition, even if the melting point of Pb is lower than the melting point of Pb, Pb alone is soft and easily removed on the raceway surface. However, the addition of Ag makes the coating slightly harder. Therefore, the lubricating film made of Pb is hardly removed from the rolling element surface, and the life of the ball bearing 10 can be extended.

FIG. 3 is a sectional view of a rolling element 24 used in an angular type ball bearing (hereinafter, ball bearing) 20 (not shown) according to a second embodiment of the present invention. Rolling element 2 shown in FIG.
4 has a ball 15 and a lubricating film 26 formed on the surface 15A of the ball 15. The lubricating film 26 is composed of two layers, an upper layer 26A and a lower layer 26B, and the upper layer 26A made of Ag.
And a lower layer 26B made of Pb. Here, the thickness of the upper layer 26A is 0.1 μm, and the thickness of the lower layer 26B is 0.3 μm.

According to such a configuration of the present embodiment, when the ball bearing 20 is used at an ambient temperature equal to or lower than the melting point of Pb, the Ag of the upper layer 26A acts as a lubricating film, and lubrication of the ball bearing is performed. Is good. In addition, ball bearing 2
When 0 is used at an ambient temperature higher than the melting point of Pb, Pb of the lower layer 26B is in a molten state, and the ball bearing 2
During operation of Ag, the Ag of the upper layer 26A
And is transferred to the sliding contact portion of the ball bearing that comes into sliding contact with the rolling element 24. In this way, Pb of the lower layer 26B is lubricated by the molten metal and the soft metal A transferred to the sliding contact portion of the ball bearing 20 slidingly contacting the rolling element 24.
The upper layer 26A made of g functions as a lubricating film. That is, when the melting point of Pb is 327 ° C. or lower, the upper layer made of Pb acts as a lubricating film.
The lower layer made of g functions as a lubricating film. By doing so, the lubrication of the bearing can be improved over a wide temperature range, and the lubrication of the contact portion of the bearing can be maintained for a long period of time.

Further, according to such a configuration of the present embodiment, it is advantageous in a method of forming a lubricating film on the surface of a rolling element by ion plating, which will be described later. In other words, Pb having a lower melting point is first evaporated to form the lower layer 26B of the rolling element 24, and Ag having a higher melting point than Pb is coated on the lower Pb as the upper layer 26A so that the lubricating film forming operation can be performed in one step. Can be processed in batch. That is, P of the deposition material
In ion plating in which b and Ag are put into the same crucible and evaporated by an electron beam, Pb having a low melting point evaporates first, so that Pb is first coated on the rolling element surface serving as a base material, and Ag having a melting point higher than Pb is used. Is coated on the upper layer of Pb. From the viewpoint of cost, it is preferable that Pb be a lower layer and Ag be an upper layer. The configuration, operation, and effects of the ball bearing 20 of the present embodiment other than those not shown above are the same as those of the above-described ball bearing 10 of the first embodiment of the present invention.

FIG. 4 is a schematic view of a film forming apparatus 50 using ion plating, which is a method for forming a lubricating film on the surfaces of the rolling elements 14 and 24 described above. The film forming apparatus 50 shown in FIG. 4 is connected to a vacuum chamber 51 and an anode power supply 52,
A hollow cathode ion gun and reaction gas supply means 54 for vaporizing the vapor deposition material 53 and ionizing vapor deposition particles, a work 55 of a rolling element in a mesh basket, and a cathode power supply 56 for applying a bias to the work 55 are shown.

In order to manufacture the above-mentioned rolling elements 14 and 24, first, after evacuating the vacuum chamber 51 of the film forming apparatus 50 to 1 × 10 ⁻⁴ Pa or less, Ar gas is introduced, and the cathode power supply 56 is operated. Let it. Then, glow discharge occurs on the surface of the rolling element that becomes the work 55, and the oxide film on the rolling element surface is removed (cleaning). Next, after cleaning for a predetermined time, supply of Ar gas is stopped, and high vacuum is maintained again. Next, Pb and A serving as the deposition raw material 53 are deposited on the deposition boat 53A.
g is weighed and a predetermined amount is charged, and the deposition material 53 is melted by an electron beam from a holocathode ion gun 54. At this time, when the anode power supply 52 is operated, plasma is generated. Then, Ar gas serving as a reaction gas is introduced by the gas supply means 53. Next, when the cathode power supply 56 is operated, a bias is applied to the work 55 to coat the workpiece. During coating, the basket in which the object is placed is rotated in the direction A in the figure. By doing so, the rolling elements 1 described in the above-described first and second embodiments can be used.
4, 24 are formed.

[0019]

EXAMPLES Table 1 shows the results of a comparison test between the ball bearing of the present invention and a conventional ball bearing. The test conditions shown below include:
The test bearing was a single row angular contact ball bearing (see FIG. 1) having an outer diameter of 22 mm, an inner diameter of 8 mm, a width of 7 mm, and a contact angle α of 30 °, without using a cage. An axial load of 30 N is applied, the rotational speed is set to 10,000 rpm, the test temperature is set to 300 ° C., and the degree of vacuum is set to 1 × 10 ⁻⁴ Pa or less. In the test results shown below, the materials of the inner and outer rings and balls were changed in each of the examples and comparative examples. In the comparative example, the materials of the upper layer and the lower layer of the film formed on the surface of the ball are changed. In the first embodiment, the inner ring
The material of the outer ring and the material of the ball are SKH4, the upper layer of the film formed on the surface of the ball is Ag (0.1 μm), and the lower layer is P
b (0.3 μm). In the second embodiment, the first embodiment
, The material of the inner and outer rings and the material of the balls are changed to ES1. In Example 3, the upper layer of the film formed on the ball in Example 1 was Pb (0.3 μm), and the lower layer was Ag.
(0.1 μm). In Comparative Example 1, the inner ring
The material of the outer ring and the material of the ball are SKH4, and the film formed on the surface of the ball is a single layer of Pb (0.3 μm).
In addition, the life of the bearing of Comparative Example 1 in which a single layer of Pb is coated on a ball is indicated as 1.

[0020]

[Table 1]

From the above test results, assuming that the life of the ball bearing shown in Comparative Example 1 is 1, the life of the ball bearing of Example 1 is 3.5, the life of the ball bearing of Example 2 is 3.7,
In Example 3, the life was 3.1. From this, it can be seen that the life of the ball bearing of the present invention is increased from about 3 times to 3.7 times as compared with the conventional ball bearing. Therefore, it can be seen that the ball bearing of the present invention has a longer life than the conventional ball bearing.

It should be noted that the present invention is not limited to the above-described embodiment, and appropriate modifications and improvements can be made.
In the present invention, in the above-described embodiment, the case of the angular type ball bearing has been described. However, another type of rolling bearing, for example, a deep groove ball bearing, a cylindrical roller bearing, a tapered roller bearing, or a spherical roller bearing may be used. . Further, the rolling bearing in the present invention may not have a cage as in the bearing used in the above-described embodiment.
Further, the location where the lubricating film made of Ag and Pb having a predetermined film thickness is formed is not limited to the rolling element surface as shown in the above-described embodiment, and is not limited to the surface of the rolling element. The raceway surface and the pocket surface of the cage may be used.

[0023]

As described above, according to the rolling bearing of the present invention, the lubricating film formed on the rolling element includes Pb
The noise during use of the bearing can be reduced by improving the life of the layer composed of, and after the Pb is melted, the layer composed of Ag acts as a lubricating film, so that it can be used for a long time at a wide range of ambient temperatures. A rolling bearing capable of stably lubricating over a long distance can be provided.

[Brief description of the drawings]

FIG. 1 shows a part of a sectional view of a ball bearing 10 according to a first embodiment of the present invention.

FIG. 2 shows a rolling element 14 used in the ball bearing 10 shown in FIG.
FIG.

FIG. 3 is a sectional view of a rolling element 24 used in a ball bearing 20 according to a second embodiment of the present invention.

FIG. 4 is a schematic view of a film forming apparatus 50 for forming lubricating films 16 and 26 formed on the surfaces of rolling elements 14 and 24 used in the ball bearings 10 and 20 of the present invention.

[Explanation of symbols]

 10, 20 angular contact type ball bearing (rolling bearing) 11 inner ring 12 outer ring 13 retainer 14, 24 rolling element 15 ball 16, 26 lubricating film 16A, 26A upper layer 16B, 26B lower layer α contact angle

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J101 AA32 AA42 AA54 AA62 BA20 BA53 BA54 BA70 CA11 DA05 EA03 EA04 EA05 EA06 EA23 EA25 FA01 FA32 GA57 GA60

Claims (1)

[Claims] 1. A rolling bearing in which a rolling element and a retainer for holding the rolling element are interposed between a raceway composed of an outer ring and an inner race, wherein at least one of the raceway ring and the rolling element is made of a steel material. A lubricating film made of Ag and a lubricating film made of Pb are laminated on at least one of the raceway surface of the bearing ring or the rolling element surface, which is a steel material, and the Ag lubricating film has a thickness of 0. A rolling bearing, wherein the thickness of the lubricating film of Pb is 0.1 to 0.5 μm.