JPH02190616A - Rolling bearing - Google Patents

Abstract

PURPOSE:To maintain smooth rotation by providing solid lubricant films at the rolling surfaces of the inner and outer wheels or the rolling element of a rolling bearing and forming a holder of copper-base metal containing lead of less than 80 in Vickers hardness, thus feeding the lead as lubricant. CONSTITUTION:A rolling element 4 held by a holder 5 is interposed between the inner wheel 2 and the outer wheel 3 of a rolling bearing. Lead-base lubricant films are provided on the rolling faces 2a, 3a of the inner and outer wheels, and the holder 5 is made of metal, of 70 in Vickers hardness, containing lead such as lead bronze. If the lubricant film is rolled by the repetition of friction and becomes less lubricative, the lead contained in the holder is fed to prevent the exhaustion of lubrication. In addition, if the holder is formed of a copper alloy base containing lead and copper base dendrite with a lower corrosive face than the copper alloy base, the feed quantity of the lubricant from the holder becomes constant, and the apparent lead quantity on the frictional surface is increased. As a result, stable lubricating performance can be maintained for many hours.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rolling bearing using a solid lubricant.

[Conventional technology]

When using rolling bearings in conditions such as high vacuum, lubricants with high vapor pressure such as grease evaporate into the atmosphere, so it is recommended to use solid lubricants with low vapor pressure such as graphite and molybdenum disulfide. It becomes necessary.

FIG. 2 shows a rolling bearing with a solid lubrication structure used in a conventional X-ray tube. This bearing 7 uses a solid lubricant to form a lubricating film 8.9 on the raceway surfaces of the inner ring 2 and outer ring 3, and on the surface of the rolling elements 4 interposed between the inner and outer rings 2.3.

In the above structure, the lubricating film formed on the sliding and rolling surfaces maintains a stable lubrication effect in the early stages of rotation, but once this lubricating film 8.9 wears out or peels off, Due to the lack of lubricant supply in these parts, metal-to-metal contact occurs in those parts, which significantly increases frictional torque and vibrations.

To address this instability in lubrication performance,
Conventionally, a bearing having the structure shown in FIG. 1 has been proposed. This bearing 1 has rolling elements 4 and a cage 5 made of a lead-containing copper alloy.
It is held between the inner and outer rings 2.3, and a solid lubricant film 6.6 is provided on the raceway surfaces 2a, 3a of the inner ring 2 and outer ring 3.

In the above structure, the lubricant film 6 provided on the raceway surfaces of the inner and outer rings 2.3 is transferred to the rolling elements 4 and acts as a lubricant, and when the lubricant of the skin 11516 is insufficient, the lead contained in the cage 5 The lubricant is maintained by being supplied to the raceway surface, which has the advantage of providing stable lubrication performance over a long period of time.

[Problems to be Solved by the Invention] By the way, in the above proposed structure, the cage 5 has a hardness of 80 Vickers hardness because of the idea that wear resistance is important.
-110. However, in this cage 5, when the solid lubricant on the raceway surfaces 2a, 3a and the surface of the cage 5 decreases, the shearing force on the friction surface that contacts the cage 5, the rolling elements 4, and the inner and outer rings 2.3 increases. As a result, the friction torque increases and wear particles with large shapes are generated. When such wear particles adhere to the surface of the friction surface, they cause an increase in vibration, and also obstruct the smooth supply of lubricant. This becomes a factor that deteriorates lubrication durability.

Furthermore, the conventional cage 5 is formed by melting a lead-containing copper alloy and then molding it using an as-cast method.
When the molten alloy is slowly cooled using a sand mold, etc.
The lead is thick (combined with each other, and as shown in FIG. 9, large precipitated lead layers 13 are scattered non-uniformly within the metal base 10 made of copper alloy).

If the lead in the cage 5 is uneven in this way, the lubricating performance will be greatly affected by the amount of lead present in the contact area with the rolling elements, and the friction torque and vibration will fluctuate suddenly. There are drawbacks.

In addition, if the structure is such that the cage 5 holds the rolling elements, it is necessary to guide the cage 5 in contact with the inner ring 2 or the outer ring 3 in order to suppress the swinging of the cage 5 during high-speed rotation.
When the amount of lubricant decreases, there is a drawback that the cage is likely to vibrate.

This invention was made to solve the drawbacks of conventional structures, and provides high durability and greatly reduces friction torque and vibration in rolling bearings that use solid lubricants and are used under high temperature and high vacuum conditions. The purpose of this invention is to provide bearings with improved performance.

[Means to solve the problem]

This invention provides two means to solve the above problems, and the first means is to provide a solid lubricant film on the raceway surfaces of the inner and outer rings or on one of the rolling elements, and to remove the retainer from the cage. The cage is made of lead-containing copper-based metal, and the hardness of the cage is set to less than 80 on the Vickers hardness scale.

A second method is to provide a film of a solid lubricant on the raceway surfaces of the inner and outer rings or on one of the rolling elements, and to form the cage from a lead-containing copper-based metal. The friction surface that comes into contact is formed of a copper alloy base containing lead, dendrites whose main component is copper, and lead uniformly scattered within the base, and the dendrites are A structure with a low corrosion surface was adopted.

(Operation) In the structure of the first means and second means, the lubricant layer provided on the raceway surfaces of the inner and outer rings or the surface of the rolling elements is transferred to the rolling elements or the raceway surfaces at the initial stage of rotation, and the lubricant layer is transferred to the rolling elements or the raceway surfaces in the early stage of rotation. Work as.

When the lubricant film is rolled due to repeated friction between the inner and outer rings and the rolling elements, and the lubrication of the raceway surface or the rolling element surface becomes insufficient, the lead contained in the cage is supplied to the raceway surface or the rolling element surface. Prevents depletion of lubrication in rolling and sliding parts.

In this case - in the first method, the hardness of the cage is adjusted to be low, so the shearing force generated on the friction surface of the cage is reduced, and the wear of the friction surface is gentler than in the conventional structure, resulting in a large Generation of wear particles is suppressed. Therefore, the friction torque is stabilized, and adhesion of abrasion powder to the surface of the rolling element is reduced, so that smooth supply of lubricant is maintained.

On the other hand, in the second method, lead is uniformly dispersed on the friction surface of the cage, so the amount of lubricant supplied from the cage is constant, the friction torque of the bearing is stabilized, and the copper Since the dendritic layer, which is the main component, is lowered from the contact surface to reduce the contact area between the rolling element and the copper alloy, the apparent amount of lead on the friction surface increases, improving lubricity. In addition, when worn lead enters the dendritic layer, which forms a recess in the substrate, this area acts similar to an oil reservoir during oil lubrication, maintaining stable lubricity over a long period of time.

be done.

〔Example〕

The rolling bearing according to the present invention is the same as that shown in FIG. Retained.

The raceway surfaces 2a and 3a of the inner ring 2 and outer ring 3 are provided with a lead lubricating film 6, and the cage 5 that holds the rolling elements 4 is made of a copper-based alloy containing lead such as lead bronze. It is formed.

The lubricating film 6.6 provided on the raceway surfaces of the inner and outer rings 2.3 acts as a lubricant for the rolling elements 4 at the initial stage of rotation, and the lubricant transferred to the rolling elements 4 draws out the lead contained in the cage 5. play a role.

In addition, lead-containing copper metals such as lead bronze emit less gas than other heat-resistant polymer materials even under high-temperature conditions in high vacuum (around 10-' Torr). It has the advantage that it does not adversely affect the degree of vacuum even when used in a vacuum tube such as a sphere.

The present inventors manufactured two types of bearing test products by changing the method of forming the retainer 5 for the rolling bearing 1 having the above structure, and attempted a vibration durability test of the test products.

The first test product had a hardness of the cage 5 of 7 on Vickers hardness.
It was formed by adjusting it to 0.

On the other hand, in the second test product, the cage 5 was formed by continuous casting,
The friction surfaces of the cage 5 that contact the rolling elements 4 and the inner and outer rings 2.3 were formed by corrosion treatment.

To explain this process, when a lead-containing copper alloy melted by continuous casting is rapidly cooled, dendrites 11 are precipitated inside the metal base 10 as shown in FIG. Lead 12 is uniformly dispersed and precipitated.

The metal base 10 described above is made of a copper alloy containing lead, but since the dendrites 11 are primary crystals, they are mostly made of copper and contain only a very small amount of lead.

Next, a corrosive solution containing a mixture of hydrogen peroxide (Hint) and aqueous ammonia (NH, OH) is applied to the friction surface of the cage 5 formed in this way, and when it is left for 6 to 8 seconds, copper becomes the main component. dendrites 11 are corroded, but the precipitated lead 12
As shown in FIG. become prominent.

By the way, in the durability test, a bearing vacuum tester was constructed to simulate an X-ray tube in order to see the effect in a vacuum state.

Figure 3 shows the vacuum testing machine. This testing machine has a cantilevered structure that receives radial loads. In Figure 0, 20 is a vacuum barrier, 21 is a drive shaft support, and 22
is a drive shaft supported by the drive shaft support 21 via the housing 26, and the tip of the drive shaft 220 is connected to the vacuum barrier 2.
It is fixed to a rotor 23 rotatably supported inside the 0.

The test bearing 1 is installed between a housing 26 and a drive shaft 22, and the drive shaft 22 is inserted inside the inner ring so that the inner ring and rotor 23 rotate together. A stator 24 is provided outside the barrier 20 along the outer peripheral surface of a rotor 23, and a weight 25 corresponding to a target of an X-ray tube is attached to the tip of the rotor 23.

In the above structure, when a magnetic field is generated in the stator 24 on the atmosphere side, the rotor 23 inside the barrier is magnetically raised and rotates.

In the durability test, the amount of electricity supplied to the stator 24 was kept constant, the rotational speed of the rotor 23 was controlled to be maintained in the range of 3100 to 3300 rotations, and the degree of vacuum inside the barrier 20 was maintained at 10-6 Torr. I did it.

The test was conducted using the first test product and second test product above, and the structure shown in Figure 1, and the hardness of the cage was 80 to 11G in terms of Vickers hardness.
A continuous rotation test was conducted on a bearing with a conventional structure set to 1, and the amount of vibration of the bearing 1 that changed over time was detected. The test results are shown in FIGS. 4 to 6.

Figure 4 shows the change in the amount of vibration of the conventional structure. As shown in Figure 0, the amount of vibration was at a relatively low and stable level at the beginning of rotation, but after about 3 hours, it suddenly started to change. An increase in vibration occurred, and thereafter sudden increases in vibration occurred frequently.

This increase in vibration may be due to the fact that the rolling elements 4 have passed through a portion of the friction surface of the cage 5 where almost no lead exists, or the lubricant has temporarily depleted on the surface of the rolling elements 4 or in the guide section of the cage. Conceivable.

FIG. 5 shows the test results for the first test article. In this case, the vibration level was in a very low range of 0.10-0.15 G, and stable rotation was obtained.

It is clear that adjusting the hardness of the cage to be low in this way has a large vibration suppression effect. The reason for this is that as the material becomes softer, the friction surface of the retainer 5 wears out more gently, which reduces the amount of abrasion powder that clogs the FR friction surface. This is thought to be because the lubricant is smoothly supplied to the surfaces and the cage guide.

FIG. 6 shows the test results for the second test article, and as in the case of the first test article in FIG. 5, the vibration was at a low and stable level. The reasons for this may be as follows. That is, in the second test product, the lead-containing metal base 10 was replaced with dendrites 11 containing almost no lead.
It protrudes further, and contacts the rolling elements 4 and the inner and outer rings 2.3 only through the protruding metal base 10 and lead 12. For this reason, the contact surface is smaller compared to the conventional case where the entire friction surface is in contact (although the lead content is not reduced, the apparent amount of lead on the friction surface increases. A good lubrication condition can be obtained.

Further, since the lead 12 is evenly distributed within the metal base 10, the supply of lubricant becomes constant and the friction torque of the bearing becomes stable.

Furthermore, as wear progresses on the friction surface, the metal base 10
When the lead 12 that falls off from the dendrites 11 enters the dendrites 11 at low places, it is retained for a long time and the dendrites 11 act as a reservoir for lead, further improving lubricity and durability. .

The above results show the results when a lead lubricating film is formed on the raceway surfaces of the inner and outer rings 2.3, but the same characteristics can be obtained even if the film is formed only on the surface of the rolling elements 4. was gotten.

Furthermore, similar results can be obtained by forming the film with another solid lubricant such as molybdenum disulfide instead of lead.

〔Effect of the invention〕

As described above, since the present invention has the above-described configuration, it has the following effects.

In the first method, since the cage hardness is adjusted to be low, cage wear becomes gentle and the amount of wear powder generated is suppressed, while sufficient lubricant can be supplied and smooth rotation with low vibration is achieved. be able to.

In addition, in the second method, since the distribution of lead contained in the cage is dispersed, the amount of lubricant supplied from the cage is constant, the friction torque of the bearing is stabilized, and the lead contained in the cage is Since the base structure containing lead is made to protrude from the dendrites that contain almost no lead, the apparent amount of lead on the friction surface increases, resulting in a better lubrication state. Furthermore, if soft lead is embedded in the dendrites concave due to rotation, durability is further improved, making it possible to achieve stable low vibration over a long period of time.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing the structure of a rolling bearing according to the present invention, Fig. 2 is a cross-sectional view of a conventional structure, Fig. 3 is a partially vertical side view of a bearing vacuum testing machine, and Figs. 4 to 6 are Figure 7 shows the internal structure of the cage of the present invention, Figure 8 is a sectional view of Figure 7, and Figure 9 shows the internal structure of the cage of the conventional structure. FIG. 1... Rolling bearing, 3... Outer ring, 5... Cage, 10... Metal base, 12... Lead. 2... Inner ring, 4... Rolling element, 6... Lubricating film, 11... Dendrites,

Claims (2)

[Claims] (1) In a rolling bearing in which the rolling elements interposed between the inner and outer rings are held by a cage, a film of solid lubricant is provided on the raceway surfaces of the inner and outer rings or one of the rolling elements, and the cage is made of lead-containing copper. A rolling bearing characterized in that it is made of metal and the hardness of the cage is set to less than 80 on the Vickers hardness scale. (2) In a rolling bearing in which the rolling elements interposed between the inner and outer rings are held by a cage, a film of solid lubricant is provided on the raceway surfaces of the inner and outer rings or one of the rolling elements, and the cage is made of lead-containing copper. The friction surface, which is made of metal and comes into contact with the rolling elements and inner and outer rings of the cage, is made of a copper alloy base containing lead, dendrites mainly composed of copper, and lead uniformly scattered within the base. A rolling bearing characterized in that the dendrites form a low corrosion surface with respect to the copper alloy base material.