JPH09144764A - Rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accomplish the long service life by reducing the degree of change of the clearance in a bearing when the bearing is used in the condition where the temperature rises on an inner ring side. SOLUTION: In a rolling bearing 1 in which inner and outer rings 2, 3 and a rolling element 4 made of heat resistant and corrosion resistant material are provided, and a lubricating film 6 made of metallic solid lubricant is formed on the surface of the rolling element 4, a film to promote the heat transfer effect to the inner and outer rings 2, 3 is formed as a base layer of the lubricating film 6 to be formed on the rolling element 4. Especially when the roller bearing is used in the condition where the temperature on the inner ring 2 side rises, the heat transfer is excellent from the inner ring 2 to the outer ring 3 to reduce the degree of the temperature rise on the inner ring 2 side, and the temperature difference between the inner and outer rings 2,3 is as small as possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention particularly relates to a rolling bearing suitable for use in a situation where the inner ring side has a high temperature such as a bearing for an anode X-ray tube.

[0002]

2. Description of the Related Art Rolling bearings used in the above-described situations cannot use general lubricating oil or grease as a lubricant.
Forming a film made of a so-called metallic solid lubricant such as a soft metal such as silver, copper or lead or a layered compound such as molybdenum disulfide on at least one of the rolling element transfer surface of the outer ring or the cage pocket surface. Is known.

[0003]

By the way, the above-mentioned anode X
In the case of a wire tube or the like, the internal atmosphere of the case becomes a vacuum, and the temperature rise of the rotary shaft arranged in this vacuum atmosphere is, for example, 400 to
It becomes remarkable at 500 ° C.

In the case of such an anode X-ray tube, although it is considered that the rolling bearing supporting the rotating shaft can serve as a heat transfer medium from the rotating shaft to the case, the rolling bearing is
During rotation, the inner / outer ring and the rolling element do not come into continuous contact at the same place, so it can be said that the heat conduction from the inner ring to the outer ring is unexpectedly bad, and the heat of the rotating shaft is efficiently transferred to the case side. It is not designed to escape. The anode X-ray tube is used in a vacuum atmosphere, and direct heat conduction and heat radiation are dominant as heat conduction.

For this reason, heat is easily accumulated in the rotary shaft, and therefore the temperature of the inner ring of the rolling bearing, which is in direct contact with the rotary shaft, rises almost the same as that of the rotary shaft. The temperature rise of the outer ring of the rolling bearing becomes relatively small, and the temperature difference between the inner and outer rings becomes large. Along with this,
Since the degree of thermal expansion of the inner and outer rings of the rolling bearing can be made different, the bearing internal clearance will change to a negative value far from the proper value, and the progress of wear of the lubricating film will be accelerated. However, the rolling bearing has a problem of seizure at an early stage.

Therefore, it is an object of the present invention to make it possible to reduce the degree of change in the bearing internal clearance so as to achieve a long service life, especially when the bearing is used in a situation where the inner ring side is heated. There is.

[0007]

SUMMARY OF THE INVENTION The present invention provides a rolling bearing having inner and outer rings made of a heat-resistant / corrosion-resistant material and rolling elements, and a lubricating film made of a metallic solid lubricant is formed on the surface of the rolling elements. , And configure as follows.

In the first rolling bearing of the present invention, a film that promotes heat conduction to the inner and outer rings is formed as an underlayer of the lubricating film formed on the rolling elements.

In the second rolling bearing of the present invention, a film is formed on at least the outer peripheral surface of the inner ring to promote heat conduction from the inner ring to the outer ring.

In the third rolling bearing of the present invention, a film for promoting heat conduction to the inner and outer rings is formed as a base layer of the lubricating film formed on the rolling elements, and at least the outer peripheral surface of the inner ring is formed. A film that promotes the heat conduction action from the inner ring to the outer ring is formed.

It is preferable to use a diamond-like carbon film as the film for promoting the above-mentioned heat conduction.

In short, according to the present invention, particularly when used in a situation where the inner ring side is heated, the heat conduction from the inner ring to the outer ring is made good and the degree of temperature rise of the inner ring can be reduced. This makes it possible to reduce the degree of change in the bearing internal clearance.

In particular, in the first rolling bearing, the heat conduction promoting film formed on the rolling elements allows good heat conduction from the inner race to the outer race while interposing the lubricating film. Further, in the second rolling bearing, the heat conduction accelerating film formed on at least the outer peripheral surface of the inner ring radiates the heat of the inner ring to the outer ring and conducts it well.
Further, the third rolling bearing also has the functions of the first and second rolling bearings.

If the heat conduction promoting film is a diamond-like carbon film, it is hard and has excellent lubricity, so that the inner / outer rings and the balls directly contact each other even after the wear of the lubricating film progresses. And prevent them from coming into contact with each other to maintain their lubricated state in good condition.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the embodiments shown in FIGS. 1 is a longitudinal sectional view of an upper half of a rolling bearing according to an embodiment of the present invention. In this embodiment, a deep groove type ball bearing is taken as an example of the rolling bearing.

In the figure, 1 is the whole rolling bearing, 2 is an inner ring, 3 is an outer ring, and 4 is a ball as a rolling element. Inner and outer rings 2, 3 and balls 4 are made of heat-resistant and food-resistant materials such as JIS standard SKH4, JIS standard SUS440C, SUS630,
It is a steel material such as SUS304 or AISI standard M50. The thermal conductivity of these steel materials is 0.835 × 10
^-4 [W / (cm · deg)].

On the surface of the ball 4, a film 5 is formed as a base layer for promoting heat conduction to the inner and outer rings 2, 3, and a lubricating film 6 is formed on the surface of the heat conduction promotion film 5. ing. A film 5 is formed on the entire surface of the inner ring 2 and the outer ring 3 to promote the heat conduction action from the inner ring 2 to the outer ring 3. The film 5 of the outer ring 3 is not particularly required, but if it exists, the radiation efficiency is further increased.

The heat conduction promoting film 5 is specifically a diamond-like carbon film (DL).
C) and is formed by, for example, a CVD method, a plasma CVD method, an ion beam method, an ion chemical vapor deposition method, or the like.
The lubricating film 6 is a so-called metallic solid lubricant such as a soft metal such as silver, copper or lead or a compound such as molybdenum disulfide or tungsten disulfide, and is formed by, for example, sputtering or ion plating. The thermal conductivity of diamond-like carbon film is about the same level as that of diamond, and is about 6.60.
^{X10 −4} [W / (cm · deg)], which is extremely high.
Moreover, this diamond-like carbon film has high hardness and excellent lubricity against rolling contact and sliding contact. The thermal conductivity of each of silver, copper, and lead used as the lubricating film 6 is 4,28 × 10 ⁻⁴ [W / (cm · d
eg)], 4.01 × 10 ^-4 [W / (cm · de
g)], 0.024 × 10 ⁻⁴ [W / (cm · deg)]
It is.

An example of a film forming method in the case where the heat conduction promoting film 5 is a diamond-like carbon film will be described.
For example, a suitable amount of an inert gas as a carrier gas is added to a carbon source such as CH ₄ or a mixed gas obtained by mixing hydrogen with the carbon source, and this is added at about 10 ⁻² to 10 ⁻⁴ Torr at 300 to 1100. It circulates on the surface of the inner ring 2 and the balls 4 heated to about ℃. Then, carbon is attached to the surfaces of the inner ring 2 and the balls 4 in a required compositional arrangement to form a film called diamond-like carbon. This film thickness is set according to the load of the bearing, the number of revolutions, etc., but is usually set in the submicron unit. Since the diamond-like carbon film is slightly blackened, it is needless to say that the diamond-like carbon film is superior in radiation efficiency to the metal material used for the inner / outer rings, balls, etc. which exhibit metallic luster.

Such a rolling bearing 1 is provided with, for example, an anode X.
When used in a rotating shaft supporting portion such as a wire tube, the inner ring 2 is heated to almost the same temperature as the rotating shaft due to the direct heat conduction from the rotating shaft which is heated to a considerably high temperature. However, in the case of the rolling bearing 1 of the present embodiment, the heat of the inner ring 2 is efficiently transmitted to the outer ring 3 by radiating the heat from the heat conduction promoting film 5 formed especially on the outer peripheral surface of the inner ring 2 toward the outer ring 3 side. It becomes well conducted. Moreover, the heat conduction promoting film 5 formed on the balls 4 allows good heat conduction from the inner ring 2 to the outer ring 3 while interposing the lubricating film 6. As a result, the heat of the rotating shaft can be efficiently dissipated to the case surrounding the rotating shaft, so that the cooling action of the entire anode X-ray tube can be enhanced. Moreover, since the degree of temperature rise of the inner ring 2 can be reduced, the temperature difference between the inner ring 2 and the outer ring 3 can be narrowed as much as possible compared with the conventional case. By approximating the degree of thermal expansion of the inner and outer rings 2 and 3 in this way, it becomes possible to maintain the bearing internal clearance in the vicinity of an appropriate value, so that it is possible to suppress an increase in the rotational torque of the rolling bearing 1 and to increase the lubricating film. As a result, the early wear of No. 6 can be reduced, and the bearing function can be exhibited satisfactorily and stably over a long period of time. When assembling the rolling bearing 1, considering the thermal expansion of each element in the usage environment,
Set the inner clearance of the bearing to be wide enough.

If the heat conduction promoting film 5 is a diamond-like carbon film having not only high thermal conductivity but also high hardness and excellent lubricity, even if wear of the lubricating film 6 progresses, The direct contact between the outer rings 2 and 3 and the balls 4 is prevented, and the lubrication state of the contact portions can be maintained well for a long period of time.

It should be noted that the present invention is not limited to only the above embodiment, and various applications and modifications are conceivable.

(1) Although the deep groove type ball bearing is taken as an example in the above embodiment, the present invention can be applied to various rolling bearings such as an angular type ball bearing and a three-point contact type ball bearing.

(2) In the above embodiment, the inner ring 2 and the outer ring 3 are
An example in which the heat conduction promoting film 5 is formed on the ball 4 and the ball 4 is given, but the heat conduction promoting film 5 is formed only on the entire surface of the inner ring 2 as shown in FIG. 2, or as shown in FIG. What is formed only on the surface of the ball 4 is also included in the present invention. Further, the heat conduction promoting film 5 may be formed only on the outer peripheral surface of the inner ring 2. However,
In the case of the embodiment shown in FIG. 2, the lubricating film 6 may be formed on the grooved ball rolling surface of the inner ring 2 in addition to being formed on the balls 4.

(3) The lubricating film 6 can have a structure in which various types of films are laminated. For example, steel balls 4
On the other hand, a bottom layer such as Sn is coated, the surface of this bottom layer is coated with an intermediate layer such as Ag (or Bi or an alloy of Ag and Bi), and the surface of this intermediate layer is further covered with a top layer such as Pb. Can have a three-layer structure. By doing so, the lubricating film becomes molten in a high temperature environment, and the wettability of the balls 4 and the inner / outer rings 2, 3 is improved, so that the lubricating action of the inner / outer rings 2, 3 and the balls 4 is maintained for a long time. It can be performed stably, and vibration and noise can be reduced.

(4) In the above embodiment, a full ball bearing without a cage is used, but a cage of corrugated type, corrugated type or the like may be used. As these cages,
It is made of steel such as JIS standard SUS304 or copper or copper alloy.

FIG. 4 shows an embodiment in which the present invention is applied to a bearing device for an anode X-ray tube. In this device, a pair of full ball bearings 11, 11 are rotatably supported on a rotary shaft 20. The outer rings 30, 30 are fitted into the housing 7 by a clearance fit, and are arranged so as to be movable in the axial direction with respect to the housing 7. Both ball bearings 11, 11
Is similar to the conventional example, the outer ring raceway grooves 31, 31 and the rotary shaft 20.
This is an integral type deep groove type ball bearing in which a large number of balls 40, 40 are interposed between the inner ring raceway grooves 21, 21 formed directly on the. The balls 40, 40 are made of a ceramic material mainly composed of high speed steel (for example, JIS standard SKH4) or silicon nitride, in addition to those of the above-mentioned embodiment. Although not shown, the lubricating film 6 is applied to the surfaces of the balls 40, 40.
The rotating shaft 20 is JIS standard SKH4, and the collars 32 and 33 between the outer rings are JIS standard SUS440C and SUS4.
It is made of stainless steel such as 03 or SUS410. 8 is a target plate.

Although not shown, a heat conduction promoting film 5 of the present invention is formed as an underlayer of the lubricating film of the balls 40, 40, and the outer peripheral surface of the rotary shaft 20 including the inner ring raceway grooves 21, 21 is also formed. , And the outer peripheral surfaces of the outer races 30, 30 including the raceway grooves 31, 31 are provided with the heat conduction promoting film 5. If the heat conduction promoting film 5 is also formed on the inner peripheral surfaces of the collars 32 and 33, the heat conduction efficiency is further improved.

[0029]

In the rolling bearing of the present invention, particularly when used in a situation where the inner ring side is heated, the heat conduction from the inner ring to the outer ring is improved to reduce the temperature rise on the inner ring side.・ By reducing the temperature difference of the outer ring as much as possible, the degree of change in the bearing internal clearance can be reduced. As a result, the lubrication action between the bearing components can be stably performed, and the life can be extended.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an upper half of a rolling bearing according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view showing an upper half of a rolling bearing according to another embodiment of the present invention.

FIG. 3 is a longitudinal sectional view showing an upper half of a rolling bearing according to still another embodiment of the present invention.

FIG. 4 is a longitudinal sectional view showing a bearing device for an anode X-ray tube according to still another embodiment of the present invention.

[Explanation of symbols]

 1 Rolling bearing 2 Inner ring 3 Outer ring 4 Ball 5 Heat conduction promoting film 6 Lubricating film

Claims (4)

[Claims] 1. A rolling bearing having inner and outer rings made of a heat-resistant / corrosion-resistant material and a rolling element, wherein a lubricating film made of a metallic solid lubricant is formed on the surface of the rolling element, the rolling bearing being formed on the rolling element. A rolling bearing, wherein a film that promotes heat conduction to the inner and outer rings is formed as a base layer of the lubricating film. 2. A rolling bearing having inner and outer rings made of a heat-resistant and corrosion-resistant material and rolling elements, wherein a lubricating film made of a metallic solid lubricant is formed on the surface of the rolling elements, at least the outer peripheral surface of the inner ring. The rolling bearing is characterized in that a film for promoting heat conduction from the inner ring to the outer ring is formed on. 3. A rolling bearing having inner and outer rings made of a heat-resistant / corrosion-resistant material and a rolling element, wherein a lubricating film made of a metallic solid lubricant is formed on the surface of the rolling element, the rolling bearing being formed on the rolling element. A film that promotes heat conduction to the inner and outer rings is formed as a base layer of the lubricating film, and a film that promotes heat conduction from the inner ring to the outer ring is formed on at least the outer peripheral surface of the inner ring. Rolling bearings characterized by 4. The rolling bearing according to claim 1, wherein the film that promotes the heat conduction effect is a diamond-like carbon film.