JPH08152025A - Solid lubrication rolling bearing - Google Patents

Abstract

PURPOSE: To provide a solid lubrication rolling bearing which is constituted to reduce the occurrence of dust, have excellent corrosion resistance, and be suitably used in a device, such as a semiconductor manufacturing device and a liquid crystal manufacturing device, needing clean atmosphere. CONSTITUTION: A solid lubrication rolling bearing is constituted in such a manner to rotatably hold a plurality of rolling bodies 4 through a holder 3 between outer and inner rings 1 and 2. A holder 3 has at least an inner peripheral surface covered with a fluorine resin film 22 through an electroless nickel film 21 or is formed by impregnating the electroless nickel film 21 with fluorine resin particles. Further, the outer and inner rings 1 and 2 and the rolling body 4 are formed of ceramics, such as silicone nitride, silicone carbide, partially stabilized zirconia, and aluminum. Or the outer and inner rings 1 and 2 have their whole surfaces covered with a film formed of titanium nitride, titanium carbon nitride, and chrome nitride.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-lubricated rolling bearing, which is particularly suitable for use in devices that require a clean atmosphere such as semiconductor manufacturing equipment and liquid crystal panel manufacturing equipment. Relates to a solid lubrication rolling bearing excellent in

[0002]

2. Description of the Related Art A rolling bearing having a structure that uses oil or grease as a lubricant can withstand high speed rotation and a large load because of its excellent lubricity, but on the other hand, oil and grease scatter as the bearing rotates, Alternatively, it cannot be used in a clean room, semiconductor manufacturing equipment, liquid crystal panel manufacturing equipment, or any other equipment that requires a clean environment, or when exposed to a vacuum because it pollutes the bearing's external environment due to vaporization due to temperature rise. I have a drawback.

Therefore, in a clean room, a semiconductor manufacturing apparatus, a liquid crystal panel manufacturing apparatus, or in a vacuum state, a bearing having a solid lubricating film formed on the raceway surface or the surface of the rolling element is used. As the solid lubricating film, soft metals such as gold, silver and lead, layered compounds such as molybdenum disulfide and tungsten disulfide, fluororesins and the like are generally used. Among these lubricating films, gold, silver, lead and fluororesin are gradually scraped off from the original film-forming surface by the frictional force generated by the rotation of the bearing, and the wear particles scraped off against each other. Lubrication is performed by transferring to a surface and forming a thin film on the surface.

On the other hand, molybdenum disulfide and tungsten disulfide are layered and have a cleavage plane by themselves, and the cleavage plane gradually wears to exhibit lubricity. In addition, the cage is made of a material containing a fluororesin, and the fluororesin particles generated by the sliding contact between the cage and the rolling element as the bearing rotates are used to remove the fluororesin particles of the inner and outer rings of the bearing and the rolling elements. A lubrication method is also adopted in which lubrication is performed by transferring to the rolling surface.

[0005]

By the way, in recent years, drive circuits for various electronic devices such as semiconductor devices and liquid crystal panels have been tending toward miniaturization and high integration, and accordingly, a small amount of particles (particles) are produced. The influence on the performance and reliability of is increasing. Therefore, there is a tendency that the demand for low dust generation is increasing more and more for bearings used in a clean environment such as semiconductor manufacturing equipment and liquid crystal panel manufacturing equipment.

However, all of the above solid lubricating films exhibit a self-sacrificing type lubricating action, and therefore the generation of wear particles is unavoidable, and the above requirements cannot be fully met. On the other hand, in the above-mentioned fluororesin cage, lubricant particles containing fluororesin are generated due to the sliding contact between the cage and the rolling elements, and the lubricant particles form a transition lubrication film, so that frictional wear of the cage material is caused. Properties affect the metastasis. That is, when a material that easily wears is used, the lubricant particles are excessively supplied, which not only causes dust generation but also the bearing particles may be locked due to the lubricant particles being caught. On the other hand, if a material that does not easily wear is used, the transfer lubrication film will not be formed and lubrication will be insufficient, and the raceways of the inner and outer rings of the bearing and the rolling surfaces of the rolling elements will wear and cause dust generation. . Further, the fluororesin has poor moldability, and in order to be used as a cage, it has to be machined into a cage shape, resulting in high cost. Further, a bearing used in a semiconductor manufacturing apparatus or a liquid crystal panel manufacturing apparatus may be used in a corrosive atmosphere such as acid or alkali, and the generated rust pollutes the external environment as dust.

[0007] Therefore, the present invention is a solid lubricant which generates little dust, has excellent corrosion resistance, and can be suitably used for a device such as a semiconductor manufacturing apparatus or a liquid crystal panel manufacturing apparatus that requires a clean atmosphere, and can be used even in a vacuum state. The purpose is to provide a rolling bearing.

[0008]

In order to achieve the above object, the solid lubrication rolling bearing of the present invention has at least a pocket inner peripheral surface between the outer surface and the outer ring and the inner ring made of ceramics. The present invention is characterized in that rolling elements made of a plurality of ceramics are rotatably held by a cage on which a fluororesin coating is formed through an electrolytic nickel coating. Further, in order to achieve the same object, in the solid lubricated rolling bearing of the present invention, a film made of a fluororesin is formed at least between the outer ring and the inner ring via an electroless nickel film on the inner peripheral surface of the pocket. In addition, a plurality of rolling elements are rotatably held via a cage in which the particles made of the fluororesin are impregnated in the electroless nickel coating.

[0009]

[Operation] In the solid-lubricated rolling bearing of the present invention, at least the inner peripheral surface of the pocket of the cage is coated with the fluororesin film through the electroless nickel film. At the same time as the adhesion to the cage is improved, excessive transfer of the fluororesin is prevented, excellent lubricity is maintained for a long time, and dust generation can be suppressed. In addition, the electroless nickel coating usually has fine cracks and pores, and at the same time as the formation of the fluororesin coating in these portions, the fluororesin particles are introduced by impregnation to form the fluororesin coating. Adhesion with the electroless nickel coating is further improved. Further, even after the fluororesin coating has disappeared due to wear, the impregnated fluororesin particles serve as a new supply source of the lubricant, and the lubricating life is extended as compared with the case where the fluororesin coating alone is used. Moreover, since the cracks and holes in the electroless nickel coating are blocked by the fluororesin particles, even when the base material of the cage corrodes, corrosion will spread to the rolling elements and inner / outer rings through the cracks and holes. Can be suppressed. Further, by making the rolling elements, or the outer surfaces of the inner and outer rings or the entire ceramics, the corrosion resistance of the entire rolling bearing including these members is improved, and dust generation due to rust can be prevented.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The solid lubrication rolling bearing of the present invention will be described below. The solid lubrication rolling bearing according to the present invention has a plurality of rolling elements 4 arranged around a circumference of a plurality of rolling elements 4 via a cage 3 between an outer ring 1 and an inner ring 2, as shown in a sectional view of a main part as an example in FIG. It is configured to be rotatably held at intervals.
The outer ring 1 and the inner ring 2 can be configured by forming bearing steel or stainless steel into an annular shape and forming a ceramic coating 20 on the entire surface thereof. At that time, as the ceramic material, titanium nitride, titanium carbonitride, chromium nitride, or the like is excellent in adhesiveness and can be particularly preferably used. The thickness of the ceramic coating 20 is preferably 1 to 5 μm. As a film forming method, a known film forming technique such as a vacuum vapor deposition method, a sputtering method, an ion plating method or a CVD method can be adopted. Further, when used in a particularly corrosive environment, the entire outer ring 1 and inner ring 2 may be made of ceramics such as silicon nitride, silicon carbide, partially stabilized zirconia, or alumina. The rolling element 4 is formed by processing a ceramic such as silicon nitride, silicon carbide, partially stabilized zirconia, or alumina into a spherical shape.

Thus, the outer ring 1, the inner ring 2 and the rolling elements 4 are
Since all of them are made of ceramics or have a ceramic coating formed on the surface, they have excellent resistance to acids and alkalis and can prevent dusting due to rust. Further, the ceramic material forming the rolling element 4 and the ceramic material forming the outer ring 1 and the inner ring 2, or the rolling element 4
When the ceramic material for forming the outer ring 1 and the ceramic material for covering the outer surfaces of the outer ring 1 and the inner ring 2 are formed of different materials, adhesive wear is eliminated as compared with the case of forming the same material. It can prevent dust generation and is more effective.

The cage 3 is made of stainless steel,
Electroless nickel coating 21 at least on the inner surface of the pocket
The fluororesin coating film 22 is covered via. The electroless nickel coating 21 and the fluororesin coating 22 may be formed on both surfaces or the entire surface of the cage 3 as illustrated.

The thickness of the electroless nickel coating 21 is not particularly limited, but is preferably about 10 μm for practical use. Further, since the electroless nickel coating 21 is for improving the adhesion between the fluororesin coating 22 and the cage 3 described later, it is preferable that the coating surface has irregularities. This electroless nickel coating 21 is, for example,
After carrying out organic solvent cleaning, acid treatment, and electrolytic cleaning of the cage 3, a nickel film of about submicron is formed by electrolytic nickel plating, and then immersed in a nickel plating bath for electroless plating to form a film. . The plating conditions are
It may be performed under the same conditions as in ordinary electroless nickel plating, for example, pH 4.5 to 5.5, and sodium hypophosphite is used as a reducing agent in an acidic nickel sulfate bath at a liquid temperature of about 90 ° C. .

The fluororesin is also not particularly limited, and polytetrafluoroethylene (hereinafter abbreviated as PTFE),
Polytrifluoroethylene, polytrifluorochloroethylene, hexafluoropropylene, polyvinyl fluoride,
Well-known fluororesins such as polyvinylidene fluoride homopolymers or copolymers can be used.
The homopolymer of E is preferable, for example, "Teflon (Dupont, USA)" or "Polyflon (Daikin Industries, Ltd.)".
Fluorine resin commercially available under the registered trademark name of can be preferably used. The fluororesin coating film 22 is a solution (aqueous solution, alcohol, etc.) in which particles of the fluororesin and a suitable binder and a surfactant are dispersed in a suitable solvent.
A film is formed by immersing in. The film thickness of the fluororesin coating film 22 is not particularly limited, but is preferably 1 μm or more for practical use. The fluororesin coating film 22 thus formed is the electroless nickel coating film 21.
The intervening contact causes the film to adhere to the cage 3 more firmly than the case where the film is directly formed on the surface of the stainless steel forming the cage 3.

By the way, the electroless nickel coating 21 has:
Usually, as shown in the enlarged sectional view of the main part of the cage 3 in FIG. 2, there are fine cracks 23 and holes (not shown). Such cracks 23 and holes are formed by the electroless nickel coating 21 and the fluororesin coating 2 formed thereon.
When the base material (stainless steel or the like) of the cage 3 is corroded by reducing the adhesiveness with the cracks 2, the corrosion causes the cracks 23
This may cause the outer ring 1, the inner ring 2, and the rolling elements 4 to spread through the holes. Therefore, in addition to the fluororesin coating film 22, it is more preferable to impregnate the cracks 23 and pores of the electroless nickel coating film 21 with particles of fluororesin that form the fluororesin coating film 22 to close the cracks 23 and pores. .

This impregnation is realized by immersing the cage 3 in a solution in which the fluororesin particles, the surfactant and the binder are dispersed in a solvent (aqueous solution, alcohol, etc.).
Immersion time is in the range of about 10-20 minutes. Here, the binder and the solvent are the same as those used when forming the fluororesin coating film 22 described above. The particle size of the fluororesin particles is selected in consideration of the sizes of the cracks 23 and holes in the electroless nickel coating 21. For example, in the case of the electroless nickel coating 21 which is preferable in the present invention described above, the size of the crack 23 is 2-3 μm in width and 2-3 in depth.
Based on these data, the preferable particle size of the fluororesin particles is in the range of 0.1 to 1 μm. Also,
The liquid temperature during immersion of the fluororesin particle dispersion solution is 30 to 80 ° C.
Is preferable, and the immersion time of the cage 3 is preferably 10 to 20 minutes. Under the above conditions, the fluororesin coating film 22 is formed at the same time when the fluororesin particles are impregnated. The presence or absence of impregnation is determined by depth direction analysis by XPS, specifically, XPS analysis while physically scraping the surface by argon ion etching.

By carrying out the impregnation treatment, the fluororesin particles enter the cracks 23 and the pores of the electroless nickel coating 21, and the adhesion between the fluororesin coating 22 and the electroless nickel coating 21 is further improved. Further, even after the fluororesin coating 22 is lost due to wear, the impregnated fluororesin particles serve as a new supply source of the lubricant, and the lubricating life is extended as compared with the case where the fluororesin coating 22 alone is used. Moreover, since the cracks 23 and pores of the electroless nickel coating 21 are blocked by the fluororesin particles, when the base material of the cage 3 is corroded, the outer ring 1 and the inner ring 2, rolling through the cracks 23 and pores. It is possible to suppress the spread to the moving body 4. As described above, since the impregnation treatment improves the corrosion resistance as well as the lubricity, the outer ring 1, the inner ring 2, and the rolling elements 4 that form the bearing are
Unlike the above-described rolling bearing having the fluororesin coating 22 alone, not all of the above-mentioned bearing constituent members are necessarily made of ceramics (the surface or the whole thereof), and if at least one is made of ceramics, excellent bearing durability is obtained. can get. This is advantageous in terms of material cost.

Further, after immersion, if necessary, 200 to 30
Heat treatment at a temperature of 0 ° C. for 2 to 5 hours increases the hardness of the nickel-plated coating to improve wear resistance, and improves the adhesion of PTFE particles adsorbed or bonded to the surface by impregnation. You can

[0019]

EXAMPLES The present invention will be described in detail based on examples. However, the present invention is not limited to the following examples. (Examples 1 to 6 and Comparative Examples 1 and 2) The outer ring 1, the inner ring 2, the cage 3 and the rolling elements 4 were made of the materials shown in Table 1, respectively, and FIG.
A solid-lubricated rolling bearing having the structure shown in was produced. still,
The electroless nickel coating 21 was coated with a film thickness of 10 μm. Further, the PTFE coating 22 was coated with a film thickness of 1 μm by immersing it in a solution in which PTFE particles were dispersed.

[0020]

[Table 1]

Then, the dust generation amount of each of the above test bearings was measured by the dust test apparatus shown in FIG. In this dust testing apparatus, the test bearings 6 are mounted in pairs in the housing 8 via the spring 7, and are rotated by the rotation introducing machine 9 with a magnetic fluid seal. The dust generated from the test bearing 6 due to the rotation is collected in a funnel 10 provided at the lower part of the device, and then sent to a light scattering type particle counter 11 to count the number of dust particles. The above test conditions are as follows.・ Test bearing 608 ・ Axial load 9.8N ・ Rotation speed 300rpm ・ Atmosphere In air

The test results are also shown in Table 1. The amount of dust generated is the number of dust generated after 600 hours of rotation, and the unit is "pieces / ft ³ ".
Is. Solid lubricated rolling bearing according to the present invention (Examples 1 to 1)
It can be seen that 6) has an extremely small amount of dust generation as compared with the solid lubricating rolling bearing (Comparative Example 1) in which the electroless nickel coating is not interposed.

The corrosion resistance test of each test bearing 6 is shown in FIG.
It carried out using the corrosion resistance evaluation apparatus shown in. The corrosion resistance test is
A beaker 3 in which a test bearing 6 is housed in an airtight container 31 in which a 0.5N hydrochloric acid aqueous solution 30 is injected and whose upper portion is opened.
2 was stored and kept at a temperature of 50 ° C. for 100 hours in a thermostat 33, and then the appearance was visually observed. The evaluation results are also shown in Table 1. In Example 4, since the inner and outer rings were made of stainless steel (SUS440C) not coated with ceramics, it was confirmed that rust was generated on the surfaces of the inner and outer rings.
It was found that the bearing as a whole was slightly inferior in corrosion resistance. In Example 5, the rolling element is made of stainless steel (SUS440
C), the same rust was observed, and it was found that the corrosion resistance was slightly inferior. In Comparative Example 2, the amount of dust generated was small because the cage was coated with the fluororesin film with the electroless nickel film interposed therebetween, but the inner and outer rings were made of high carbon chrome steel (SUJ2), and therefore rusted. Was observed.

(Examples 7 to 10 and Comparative Examples 3 to 5) The outer ring 1, the inner ring 2, the cage 3 and the rolling elements 4 are made of the materials shown in Table 2, and the solid lubricated rolling bearing having the structure shown in FIG. 1 is used. It was made. The cage 4 is coated with an electroless nickel coating 21 with a film thickness of 10 μm, and a P particle having an average particle size of 0.4 μm.
Dip the TFE particles together with a binder in a solution at a liquid temperature of 40 ° C. for 20 minutes, and then heat at 300 ° C. for 3 hours to form a PTFE film having a thickness of 1 μm.
Those impregnated with FE particles (Examples 7 to 10), PTF
Those obtained by only forming the E coating (Comparative Examples 3 and 4) and those obtained without the electroless nickel coating and using the PTFE sintered film (Comparative Example 5) were used.

[0025]

[Table 2]

Then, the torque of each of the above test bearings was measured by the vacuum durability test apparatus shown in FIG. In this vacuum endurance test apparatus, the test bearing 60 is the spring 70.
Two of them are mounted in the housing 80 through a pair and are arranged in the vacuum chamber 100, and are rotated by a rotation introducing machine 90 with a magnetic fluid seal under vacuum. The torque of the test bearing 60 due to the rotation is measured by the load cell 110 as a torque for two bearings. The time until the torque for two bearings exceeded 80 g · cm was measured and used as the criterion for determining the durability of the bearing. The above test conditions are as follows.・ Test bearing 608-H (stainless steel product) ・ Axial load 25N ・ Rotational speed 500 rpm ・ Atmosphere 1 × 10 ^-5 Torr or less

The test results are also shown in Table 2. It can be seen that the solid lubrication rolling bearings (Examples 7 to 10) according to the present invention have improved durability as compared with the solid lubrication rolling bearings shown in the comparative examples. In particular, the durability was improved compared to the solid lubrication rolling bearing (Comparative Example 4) in which the cage was provided with the electroless nickel coating and the PTFE resin coating, and the effect of the impregnation was confirmed. Was given.

[0028]

As described above, in the solid lubrication rolling bearing of the present invention, since at least the pocket inner peripheral surface of the cage is coated with the fluororesin film through the electroless nickel film, the electroless nickel film By the anchoring effect, the adhesion of the fluororesin film to the cage is improved, and at the same time, excessive transfer of the fluororesin is prevented, excellent lubricity is maintained for a long time, and dust generation can be suppressed. In addition, the electroless nickel coating usually has fine cracks and pores, and at the same time as the formation of the fluororesin coating in these portions, the fluororesin particles are introduced by impregnation to form the fluororesin coating. Adhesion with the electroless nickel coating is further improved. Further, even after the fluororesin coating has disappeared due to wear, the impregnated fluororesin particles serve as a new supply source of the lubricant, and the lubricating life is extended as compared with the case where the fluororesin coating alone is used. Moreover, since the cracks and holes in the electroless nickel coating are blocked by the fluororesin particles, even when the base material of the cage corrodes, corrosion will spread to the rolling elements and inner / outer rings through the cracks and holes. Can be suppressed. Furthermore, rolling elements, or
By making the outer surface or the whole of the outer ring of ceramics, the corrosion resistance of the entire rolling bearing including these members is improved, and dust generation due to rust can be prevented.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts showing a solid lubrication rolling bearing according to the present invention.

FIG. 2 is an enlarged sectional view of a main part of the cage shown in FIG.

FIG. 3 is a schematic view showing a dust test apparatus used in the present invention.

FIG. 4 is a schematic view showing a corrosion resistance evaluation apparatus used in the present invention.

FIG. 5 is a schematic view showing a vacuum durability test apparatus used in the present invention.

[Explanation of symbols]

 1 Outer ring 2 Inner ring 3 Cage 4 Rolling element 6 Test bearing 7 Spring 8 Housing 9 Rotation introduction machine with magnetic fluid seal 10 Rot 11 Particle counter 20 Ceramics coating 21 Electroless nickel coating 22 Fluororesin coating 23 Crack 31 Sealed container 32 Beaker 33 Constant temperature bath 60 Test bearing 70 Spring 80 Housing 90 Rotation induction machine with magnetic fluid seal 100 Vacuum chamber 110 Load cell

Claims (3)

[Claims] 1. A plurality of cages having a fluororesin coating formed on at least the inner peripheral surface of the pocket with an electroless nickel coating between an outer ring and an inner ring whose outer surface or the whole is made of ceramics. A solid-lubricated rolling bearing characterized in that a rolling element made of ceramics is rotatably held. 2. A film made of a fluororesin is formed between at least an inner peripheral surface of the pocket between the outer ring and the inner ring through an electroless nickel film, and particles made of the fluororesin are contained in the electroless nickel film. A solid lubrication rolling bearing, wherein a plurality of rolling elements are rotatably held by a cage impregnated in the. 3. The solid lubricated rolling bearing according to claim 2, wherein at least one of the outer ring, the inner ring and the rolling element has an outer surface or the whole made of ceramics.