JP3785198B2 - Rolling bearing - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a rolling bearing, and more particularly to a rolling bearing that is advantageous for use in a vacuum environment, a clean environment, a corrosive environment, or the like where normal grease or oil cannot be used.
[0002]
[Prior art]
As the aforementioned environment, for example, a conveyance system arranged inside a semiconductor manufacturing apparatus can be cited. In such an environment, if grease is used as a lubricant for a rolling bearing, the oil content of the grease evaporates. This causes problems such as deterioration of the lubrication function and contamination of the usage environment.
[0003]
In such a case, conventionally, the surface of the raceway and the surface of the rolling element are mainly coated with a soft metal such as gold, silver, lead, or copper, or a solid lubricant such as carbon or molybdenum disulfide in a film form. Things have been done.
[0004]
[Problems to be solved by the invention]
By the way, in the lubricating film made of the above-mentioned solid lubricant, although the lubricating film is peeled off little by little by contact with the rolling elements, the dust generation state is at a lower level than when using grease, but it is not suitable particularly in a clean environment. Is a level.
[0005]
Therefore, the applicant of the present application has considered that a lubricating film containing a fluorine-based resin is formed on a raceway ring or a cage so that dust generation can be reduced by an order of magnitude compared to the prior art (Japanese Patent Laid-Open No. 4-46219). Issue gazette). In this publication, it has been found that since the lubricating film is mainly provided on the raceway portions of the inner and outer rings, there is much dust generation due to peeling or missing of the lubricating film at the initial stage of rotation. Incidentally, since the thing of this gazette is equivalent to the comparative examples 3 and 4 shown in FIG. 3, please refer.
[0006]
In view of such circumstances, an object of the present invention is to suppress dust generation due to wear from a lubricating film.
[0007]
[Means for Solving the Problems]
The rolling bearing of the present invention is a rolling bearing used in a vacuum environment, a clean environment and a corrosive environment, and has a bearing ring made of a metal or a ceramic material, a rolling element, and a cage made of a metal or a synthetic resin material, Only at least the surface including the sliding surface of the cage, PTFE having an average molecular weight of 1 × 10 ^{4 to} 5 × 10 ⁴ is dispersed in a binder composed of a thermosetting synthetic resin selected from polyimide and polyamideimide. The mixed lubricating film is coated , and the ratio of the weight of the binder made of the thermosetting synthetic resin to the weight of the fluorine-based synthetic resin is 10 to 50: 1 to 20.
[0008]
The metal constituting the bearing ring and the rolling element is suitable for martensitic stainless steel such as JIS standard SUS440C, for example, precipitation hardening stainless steel such as JIS standard SUS630, particularly in an environment where corrosion resistance is required. Can be used after curing heat treatment. In light load applications, for example, austenitic stainless steel such as JIS standard SUS304 can be used. Further, Ni—Cr—Mo alloys such as those manufactured by Mitsubishi Materials Corporation, trade names HASTELLOY C-22, HASTELLOY C-276, HASTELLOY C-4 and the like can be used as the nickel-based alloy.
[0009]
Ceramic materials include yttria (Y ₂ O ₃ ) and alumina (Al ₂ O ₃ ) as sintering aids, as well as aluminum nitride (AlN), titanium oxide (TiO ₂ ), spinel (MgAl ₂ O ₄ ) as appropriate. ) Using silicon nitride (Si ₃ N ₄ ) as a main component, alumina (Al ₂ O ₃ ), silicon carbide (SiC), zirconia (ZrO ₂ ), aluminum nitride (AlN), etc. Can do.
[0010]
As the metal constituting the cage, for example, JIS standard SUS304, brass, titanium material or the like is preferably used. Synthetic resin materials include fluorine-based resins such as polytetrafluoroethylene (hereinafter abbreviated as PTFE) and ethylenetetrafluoroethylene (ETFE), polyether ether ketone (PEEK), polyphenylene sulfide (PPS), and polyether sulfone. It is also possible to use engineering plastics such as (PES) and nylon 46. Reinforcing fibers such as glass fibers may be added to these resins. As the type of the cage, a wave shape, a crown shape, a machined shape, or the like is preferably used.
[0011]
The thermosetting synthetic resin desirably has a certain degree of slidability by itself, for example, a resin having an imide bond or an amidoimide bond is desirable. Examples of the resin binder having an imide bond or an amideimide bond include thermosetting condensation polymerization type polyimide and polyamideimide. These resins generally have features such as good heat resistance, excellent adhesiveness, extremely little decrease in adhesive strength even at high temperatures, excellent dimensional stability, and good frictional wear characteristics. In addition, these resins are not accompanied by the generation of moisture and other volatile components in the process of curing (addition polymerization), and the resin itself has extremely low hygroscopicity. All it nor would cause air bubbles and cracks. Polytetrafluoroethylene (PTFE) is used as the fluorine-based synthetic resin . This fluorine-based synthetic resin is a substantial lubrication main body. When only the above-mentioned thermosetting synthetic resin binders are used, they are very hard and have excellent heat resistance, but they are worn away and easily peeled off. Add as purpose. When using PTFE, a polymer having an average molecular weight of 1 × 10 ^{4 to} 5 × 10 ⁴ is selected. Among them, those having a polymer average molecular weight of 3 × 10 ^{4 to} 5 × 10 ⁴ are preferably used. When the average molecular weight is less than 1 × 10 ⁴ , the adhesion strength is lowered and the sliding resistance is also increased. When the average molecular weight exceeds 5 × 10 ⁴ , the shear resistance is large and the film becomes too hard.
[0012]
In addition, the particle diameter of PTFE is preferably 2 to 3 μm. If it exceeds 3 μm, the fluidity and dispersibility are lowered, the fluid film protrudes from the lubricating film, the smoothness of the lubricating film is impaired, smooth driving is hindered, and abnormal noise is also generated. If it is less than 2 μm, the lubricating effect is saturated, but it is economically negative.
[0013]
The thickness of the lubricating film 6 is required to be at least as smooth as the surface of the cage, and is preferably set to, for example, 5 to 20 μm, and the hardness is set to a pencil scratch value of 3H to 6H based on JIS standard K5400. . This hardness can be appropriately managed according to the mixing ratio of the resin binder of the lubricating film 6 and the fluorine-based synthetic resin and the firing conditions.
[0014]
The lubricating film of the present invention comprises 10 to 50% by weight of the resin binder having the imide bond or amideimide bond, and 1 to 20% by weight of a fluorine-based synthetic resin, for example, a solvent such as N-methyl-2-pyrrolidone. The solution dispersed and mixed using is applied to the coated surface by a bonded film method or the like.
[0015]
[Action]
According to the above configuration, the lubricant film is formed only on the surface including the sliding surface of the cage, and the lubricant film is worn by sliding contact with the rolling element. By being transferred to the raceway surface of the raceway, lubrication between the rolling elements and the raceway raceway surface is performed.
[0016]
In the case of the present invention, since no lubricating film is provided on the rolling elements or the raceway raceway surface, the amount of transfer associated with wear of the lubricating film at the initial stage of rotation or the like is the case where a lubricating film is formed on the rolling element or raceway raceway surface. Far less than
[0017]
In short, in the present invention, only a necessary amount is transferred from the lubricating film of the cage to the rolling elements and the raceway surface for use in lubrication.
[0018]
【Example】
Details of the present invention will be described below based on the embodiment shown in FIGS. FIG. 1 shows an embodiment of a rolling bearing according to the present invention. Here, a deep groove type ball bearing is taken as an example. In the figure, 1 is an inner ring, 2 is an outer ring, 3 is a ball as a rolling element, and 4 is a corrugated cage made of press. The entire surface of the cage 4 is covered with a lubricating film 5 in which a fluorine-based synthetic resin is dispersed and mixed in a resin binder having an imide bond or an amide-imide bond. Specifically, the inner and outer rings 1 and 2 and the ball 3 are made of JIS standard SUS440C, and the cage 4 is made of JIS standard SUS304. The lubricating film 5 is made of PTFE as a main lubricant and polyamideimide as a thermosetting organic resin binder.
[0019]
An example of the method for forming the lubricating film 5 will be described.
[0020]
(A) Degrease each cage 4. The retainer 4 is subjected to a deburring barrel polishing process after pressing, and has a surface roughness Rz of 0.3 μm to 1.0 μm. Note that the adhesion of the lubricating film 5 to the surface of the cage 4 may be further increased by sandblasting the cage 4 to have a surface roughness of Rz 6 to 10 μm.
[0021]
(B) A solution obtained by dissolving PTFE powder and polyamideimide powder with N-methyl-2-pyrrolidone is sprayed over the entire surface of the cage 4 a plurality of times. This is an application method called a so-called bonded film method, in which each of the powders is almost uniformly diffused on the spray surface. In addition, the component ratio of the above-mentioned solution is, for example, PTFE powder 5%, polyamideimide powder 25%, and N-methyl-2-pyrrolidone 70%.
[0022]
(C) The sprayed coating is fixed to the cage 4 by baking at a temperature of 180 ° C. ± 10 ° C. for a predetermined time (about 30 minutes to 120 minutes).
[0023]
Then, if necessary, (b) and (c) are repeated several times, and the film thickness of the lubricating film 5 is finally set to 5 to 20 μm, for example. Finally, the surface roughness of the lubricating film 5 is Rz 1 to 2 μm, which is rougher than the roughness of the ball 3 (Rz 0.1 μm or less), and the lubricating film is efficiently formed by the sliding contact with the ball 3. It will be transferred to the surface.
[0024]
Next, since the test is performed on the dust generation amount and the dust generation life at the initial rotation of the rolling bearing, explanation will be given. In this test, the apparatus shown in FIG. 2 is used. In the figure, 50 is a rolling bearing, 51 is a rotating shaft, 52 is a casing, 53 is a magnetic fluid seal, 54 is a dust generation number measuring device (particle counter), 55 is a measurement result recorder (recorder), and 56 is a bearing housing. is there.
[0025]
Bearing used: SEML 6012 (φ6 × φ12 × 3), nominal number ML6012
・ Rotation speed: 200rpm
・ Load: Radial load (2.9N)
・ Atmosphere: Class 10 clean bench in the air, room temperature ・ Measurement conditions: Dust generation tests with particle diameters of 0.3 μm or more are conducted for the following six types (1) to (6). (1) As Example 1, the inner and outer rings and balls are JIS standard SUS440C, the cage is JIS standard SUS304, and the entire surface of the cage is covered with a lubricating film. (2) As Example 2, the inner and outer rings are JIS standard SUS440C, the balls are ceramic materials mainly composed of silicon nitride (Si ₃ N ₄ ), the cage is JIS standard SUS304, and the entire surface of the cage is covered with a lubricating film. To do. (3) As Comparative Example 1, the inner and outer rings and balls are JIS standard SUS440C, the cage is JIS standard SUS304, and no lubrication film is provided. ( ₄ ) In Comparative Example 2, the inner and outer rings are JIS standard SUS440C, the balls are ceramic materials mainly composed of silicon nitride (Si ₃ N ₄ ), the cage is JIS standard SUS304, and no lubrication film is used. . (5) As Comparative Example 3, the inner and outer rings and balls are JIS standard SUS440C and the cage is JIS standard SUS304, and the inner and outer ring raceways and the entire surface of the cage are covered with a lubricating film. (6) As Comparative Example 4, the inner and outer rings are JIS standard SUS440C, the balls are ceramic materials mainly composed of silicon nitride (Si ₃ N ₄ ), and the cage is JIS standard SUS304. Cover the entire surface with a lubricating film.
[0026]
First, in the test of the dust generation amount at the initial stage of rotation, the dust generation amount from the start of the test to 20 hours is measured. As a result, as shown in FIG. 3, Example 1, Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 2, and Comparative Example 1 were obtained in ascending order of dust generation. This result proves the superiority of covering the cage with the above-described lubricating film rather than covering the track of the inner and outer rings.
[0027]
In the dust generation life test, the time until dust having a particle diameter of 0.3 μm or more reaches 1000 / 0.1 cf or more is measured. Measurements are made every 6 minutes. As a result, Comparative Example 1 was about 25 hours, Comparative Example 2 was about 50 hours, and Examples 1, 2 and Comparative Examples 3 and 4 were 1000 hours or more. This result proves the superiority of using the above-described lubricating film 5 rather than no lubrication.
[0028]
Furthermore, the graph of FIG. 4 shows the relationship between the static load rating and the dusting life. That is, it can be seen that if the static load rating is small, the dust generation life is extended. Under light load conditions of 2.9 [%] or less of the static load rating Co of the bearing, the dusting life is significantly extended to 1000 hours or more. This result shows that the bearing of this example structure is particularly effective when used under light load conditions.
[0029]
Next, the lubricating film 5 of the present invention is compared with a conventional lubricating film made of only PTFE (polytetrafluoroethylene). Here, the same Example 1 and Comparative Examples 5 and 6 as described above are used. Comparative Example 5 has the same specifications as in Example 1, that is, the inner and outer rings and balls are JIS standard SUS440C, the cage is JIS standard SUS304, and the cage is covered with a lubricating film made only of PTFE having an average molecular weight of less than 10,000. Yes. In Comparative Example 6, only the lubricating film in Comparative Example 5 is PTFE having an average molecular weight of 10,000 or more. In the lubricating films of Comparative Examples 5 and 6, the hardness is “B” of the pencil scratch value based on JIS standard K5400, whereas in the lubricating film of Example 1, the hardness is “3H” of the pencil scratch value. ~ 6H ". And in the test of the amount of dust generation at the initial stage of rotation similar to that described above, as shown in FIG. As shown in this result, it can be said that the conventional lubricating film made of only PTFE is soft and excessive wear easily occurs in sliding contact, whereas the lubricating film of the present invention is hard. It can be said that wear during sliding contact is suppressed to the minimum necessary. That is, the lubricating film 5 of the present invention is superior in reducing the amount of dust generation than a conventional lubricating film made of only PTFE (polytetrafluoroethylene).
[0030]
In addition, this invention is not limited only to the said Example. For example, in the embodiment, the entire cage may be formed of the resin having the above configuration. Moreover, although the deep groove type ball bearing is cited as the bearing type, the present invention can be applied to other types of rolling bearings. Moreover, you may attach a sealing board to a bearing edge part. In addition, the lubricating film 5 may be formed only on the inner surface of the pocket of the cage 4, and in that case, the lubricating film 5 is almost the same as or approximate to the test data. In this case, before forming the lubricating film 5, it is necessary to cover a portion (not shown) of the cage 4 except for the pocket inner surface.
[0031]
【The invention's effect】
As described above, according to the present invention, at least the cage slides between the rolling element and the raceway with rotation without coating the lubricating film between the rolling element and the raceway as in the prior art. Since only the required amount is transferred from the lubricating film coated only on the surface including the surface, it is possible to prevent excessive wear of the lubricating film as in the conventional case, and the entire bearing. Dust generation can be reduced.
[0032]
Therefore, for example, when the rolling bearing of the present invention is used where high-precision processing is required as in the semiconductor manufacturing process, it is difficult to inhibit the clean atmosphere, which can contribute to the improvement of the yield of semiconductor manufactured products.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an upper half of a deep groove type ball bearing according to an embodiment of the present invention.
FIG. 2 is a schematic view of a test apparatus used for measuring the dust generation amount of the bearing.
FIG. 3 is a graph showing measurement results of the amount of dust generation.
FIG. 4 is a graph showing a relationship between a static load rating and a dusting life in an example.
FIG. 5 is a graph showing measurement results of the amount of dust generation.
[Explanation of symbols]
1 Inner ring 2 Outer ring 3 Ball 4 Cage 5 Lubrication film

Claims (1)

Rolling bearings used in vacuum, clean and corrosive environments,
From a thermosetting synthetic resin selected from polyimide and polyamideimide , having a raceway made of metal or a ceramic material, a rolling element, and a cage made of metal or a synthetic resin material, at least the surface including the sliding surface of the cage comprising average molecular weight 1 ^× 10 ⁴ ~5 × 10 4 of the lubricating film of the PTFE dispersed mixture is fluorine-based synthetic resin in the binder is coated, and the weight of the binder consisting of the thermosetting synthetic resin, the fluorine-based synthetic A rolling bearing characterized in that the ratio to the weight of the resin is 10 to 50: 1 to 20 .

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