JP2004239443A - Rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prolong the service life of a rolling bearing for a vacuum pump and so forth used under severe conditions such as reduced pressure atmosphere, high-speed rotation, high temperature, and lubrication with fluorocarbon lubricating oil. <P>SOLUTION: The size of the opening part of a pocket with weld line among the rolling element pockets of a retainer is set to 93% or more of a rolling element diameter, and the size of the opening parts of at least the other two or more pockets is set to 80 to 93% of the rolling element diameter. The retainer is formed of a PTFE resin material or a PPS resin material, or the pockets are chamfered on the inner and outer diameter sides and through holes are formed at the bottom parts of the pockets. As a result, cracking and brazing can be prevented from occurring at the bottom part of the pocket with weld line when rolling elements are assembled in the pockets while securely preventing the retainer from falling off so that wear powder is made hard to be produced in the retainer, lubricant is not deteriorated, dents are hard to be produced in a raceway surface, and lubricating performance can be increased. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention is used in a reduced-pressure atmosphere such as a semiconductor manufacturing apparatus or a vacuum pump apparatus, or used in a high-temperature environment such as for a heat roll of a fixing unit of office equipment, and contains a fluorine-containing polymer. The present invention relates to a rolling bearing used in an atmosphere containing a gas containing lubricating oil, grease, or fluoride.

  There are various types of vacuum pumps for creating or maintaining a vacuum degree, and among them, a dry screw pump is one having a relatively low ultimate vacuum degree. The pump body is provided with a suction port and a discharge port, a pair of rotors disposed in the pump body and having a left-handed screw and a right-handed screw respectively cut off, and rotatably held by the pump body by rolling bearings. And a pair of rotors are rotated synchronously in a non-contact state with each other, so that the gas in the container connected to the suction port is sucked into the pump body, and the gas is discharged from the discharge port. It discharges and makes the inside of the container a vacuum state.

  The two rotor shafts are rotatably supported by rolling bearings. For the rolling bearings, normal bearing steel (SUJ2) is often used. In a rolling bearing, since a high contact stress repeatedly acts on the inner and outer rings and the rolling elements, it is necessary to form the inner and outer rings and the rolling elements hardly and to prolong the rolling fatigue life. Therefore, after the inner and outer races and rolling elements of the rolling bearing are formed of the bearing steel (SUJ2), quenching and tempering are performed.

  As a lubricant for a bearing used in a reduced pressure (including vacuum) atmosphere such as a vacuum pump device, a solid lubricant may be used to prevent contamination of the reduced pressure atmosphere. Fluid lubricants such as lubricating oils have been increasingly used to improve reliability. As a typical example, a fluorine-based lubricating oil having high corrosion resistance and hardly evaporating is used. In particular, high-vacuum pumps used at high speeds and in some cases in high-temperature environments often use more reliable fluorine-based lubricants for lubrication. Conventionally, in a rolling bearing used in a reduced-pressure atmosphere including such a vacuum, only the lubricant is changed to a fluorine-based lubricating oil, and the accuracy of the bearing itself is kept to a normal specification (for example, JIS B 1514 in accuracy). It is.

  On the other hand, even under a high temperature environment exceeding 200 ° C., such as a heat roll in a fixing section of office equipment, a fluorine-based lubricating oil or a fluorine-based grease having excellent heat resistance, a small amount of evaporation, and being chemically stable is used. Such fluorine-based lubricating oils and fluorine-based greases include, for example, lubricating oils or greases containing a fluorine-containing polymer such as perfluoropolyether (PFPE) oil and fluorine-based grease based on this PFPE oil. No. Under a normal use environment, there was no problem in lubricating with a lubricating oil or grease containing such a fluorine-containing polymer.

  However, in recent years, office equipment represented by a copier (PPC), a laser beam printer (LBP), a facsimile (FAX), or a multifunction peripheral thereof has a tendency to be compact, energy-saving, recycle, and high-speed. Therefore, it has been required to have a smaller size and a longer torque life under more severe conditions (high speed, high load). Also, in the field of the vacuum pump, there is a demand for a rolling bearing that operates for a long time at a higher temperature and a higher speed in order to increase the capacity and reduce the size. Further, in the field of semiconductor and liquid crystal panel production, with the increase in the size of substrates and the speed of transportation, rolling bearings used are required to operate for a long period of time under high load and high speed.

In these and individual, between the outer ring raceway and inner ring raceway, as a common material of the retainer for retaining the equidistantly rolling elements, SPCC material and HB _S C1 material, is used and the like PA66 resin I have. BACKGROUND ART Rolling bearings that require corrosion resistance, such as the support bearings of the vacuum pump, use a rolling bearing retainer formed of a high-performance resin material having low ductility but corrosion resistance, but having poor corrosion resistance. The cage for rolling bearings is provided with a plurality of pockets for accommodating the rolling elements from the openings and holding the rolling elements in a rotatable manner at predetermined intervals in the circumferential direction.

  Referring to FIG. 23, conventionally, the opening size F of each pocket 30 is set to a value of 85 to 93% of the rolling element diameter G, respectively. Therefore, each rolling element 31 is incorporated into each pocket 30 from the opening 33 so as to push the claw 32 of each pocket 30 in the circumferential direction. This makes it easy to incorporate the rolling elements 31 into the respective pockets 30 and makes it difficult for the rolling elements 31 incorporated into the respective pockets 30 to fall off.

  By the way, in rolling bearings for vacuum pumps that are used at high speeds and in some cases in high-temperature environments, in order to prevent the lubricating oil film from decreasing due to an increase in lubricating oil temperature or to prevent lubricating oil from contaminating the pump section, Since lubrication in the oil bath cannot be performed and the lubrication system is of a splash type using gears or the like, lubrication conditions may be insufficient, such as insufficient supply of lubricating oil. Furthermore, fluorine-based lubricating oils have a higher specific gravity than ordinary mineral oil-based lubricating oils, and so-called wetting properties are extremely reduced, so that the formation of a lubricating oil film tends to be difficult, and the lubricating conditions are more severe. I have. In addition, when the air starts to be exhausted, a short but excessive axial load is applied to the bearing supporting the rotor of the dry screw pump, and the axial load fluctuates in the bearing. If such strict lubrication conditions are overlapped and lubrication is insufficient, peeling wear and peeling may occur on the bearing raceway surface.

  Also, when oil bath lubrication of fluorine-based lubricating oil is adopted, the oil level is not sufficient due to the structure of the device (the oil level of the pitch circle diameter of the bearing from the lower side of the housing inner diameter surface). There are things that are not good. That is, the combination angular contact ball bearings and double-row angular contact ball bearings shown in FIGS. 19 to 22 have a good lubrication state near the oil level, but the opposite side of the oil level is lubricated by rotation of the bearing. The lubrication state is not good, and the wear of the cage, the rolling wheels and the rolling elements is promoted, which may lead to breakage of the cage, discoloration of the rolling elements, and eventually damage to the bearings. In the drawings, reference numeral 100 denotes an outer ring, 200 denotes an inner ring, 300 denotes a rolling element, and 400 denotes a retainer.

Further, the fluorine-based lubricating oil reacts with iron to produce iron fluoride, which serves as a catalyst to decompose the fluorine-based lubricating oil. As described above, if the lubrication becomes insufficient and the rolling elements and the raceway surface of the bearing ring come into direct contact with each other, a very high temperature is locally generated at the contact point, whereby the fluorine-based lubricating oil (PFPE oil, etc.) is decomposed. In addition, the surfaces of the rolling elements, races and cages may be corroded, resulting in a short life. In order to cope with such a problem, in a high-speed application such as a machine tool or a vacuum pump device, silicon nitride (Si ₃₎ is used as a rolling element because of its advantages of excellent adhesion and seizure resistance to metal and light weight. N ₄ ) are used. However, when the temperature rises locally due to a break in the oil film, the PFPE oil reacts with Si, which is the main component of silicon nitride, and as a result, Si ₂ F ₆ gas is generated, resulting in brittleness and abnormal wear. Another problem arises.

These problems can occur in the same manner as in the case of rolling bearings used in an atmosphere containing a gas composed of fluoride, for example, in addition to the lubricating conditions using lubricating oil or grease containing a fluorine-containing polymerization couple. is there.
In addition, separately from the above, in the conventional rolling bearing cage, when a resin material having a lower deformability than, for example, a polyamide resin, for example, a high-functional resin such as a polyphenylene sulfide (PPS) resin is used as a material, When the rolling element 31 is incorporated into the pocket 30 from the portion 33 (see FIG. 23), a bending moment acts on the entire retainer by a force acting to push and open the claw portion 32 of the pocket 30, and the thickness of the bottom of the pocket 30 is increased. There is a problem that cracks, cracks, and the like may occur in a portion having a small (low strength), specifically, the bottom of the pocket 30 having the weld line 34. In particular, in the axial draw, if a weld line is formed at the bottom of an odd number of pockets, it tends to be a starting point of crack generation.

  The present invention has been developed to solve the above-mentioned problems, and provides a long-life rolling bearing even under severe lubricating conditions using a fluorine-based lubricating oil. In addition, when a rolling element is incorporated in a cage pocket, a weld line is formed. It is an object of the present invention to provide a rolling bearing in which cracks, cracks, and the like do not occur in pockets having a crack.

As a result of repeated investigations on the form of peeling abrasion and peeling peeling generated on a rolling bearing lubricated with a fluorine-based lubricating oil, the present inventors have found the following characteristics.
a. The rolling element of the rolling bearing in which peeling has occurred on the inner ring or the outer ring is always worn.
b. On the raceway surfaces of the inner and outer rings and the rolling elements where the peeling has occurred, traces of foreign matter such as abrasion powder and abrasive wear due to the foreign matter are observed.
c. Even if the inner ring and the outer ring do not have peeling, the rolling elements may be damaged or worn.
d. In the bearing whose rolling element is damaged or worn, abnormal wear occurs in the pocket portion of the steel cage.

From the above results, it is easily presumed that the peeling starts first from the rolling elements. And if you estimate the mechanism,
1. Lubrication conditions are very severe for vacuum pump bearings that are lubricated with fluorine-based lubricating oil and that are used at high speeds. In other words, since the fluorine-based lubricating oil has poor wettability, it is difficult for the lubricating oil to reach the gap, and when the temperature rise at high rotation is taken into consideration, the lubricating ability particularly around the retainer is reduced. Therefore, the rolling element and the retainer may come into strong contact with each other.
2. If the cage is not sufficiently lubricated, the pockets of the cage will be worn by contact with the rolling elements, and the rolling elements themselves will be damaged, resulting in poor surface roughness.
3. A rolling element whose roughness has deteriorated under severe lubrication conditions comes into metallic contact with the inner and outer rings, and peeling occurs on the inner and outer rings. Further, the peeling of the rolling elements and the inner and outer rings is promoted by the wear powder of the retainer.

In addition, the present inventors have investigated the effect of roughness under lubricating conditions with a fluorine-based lubricating oil. As a result, (a) when the roughness of the inner ring and the outer ring deteriorates, the rolling elements wear, and (a) the inner ring and the outer ring When the ratio of the roughness of the rolling elements to the roughness of the rolling elements increases, a phenomenon appears in which the rolling elements are worn.
This is because if the roughness deteriorates under severe lubricating conditions with a fluorine-based lubricating oil, metal contact occurs, new roughness deteriorates, contact wear occurs, and peeling wear easily occurs.

In addition, when the worn rolling elements were carefully observed, it was confirmed that there were countless scratches due to minute foreign substances (several μm level). This is thought to be due to abrasive wear caused by fine abrasion powder generated by metal contact or contact abrasion.However, when the roughness of the inner ring and outer ring deteriorates, the amount of abrasion powder increases and the abrasion of the rolling elements tends to increase. Indicated.
Here, the bearing for a vacuum pump used in a high-temperature and high-speed environment is subjected to a dimensional stabilization process so that the bearing does not undergo a dimensional change with time due to temperature. The dimensional stabilization process is to heat-treat the bearing at a temperature higher than the temperature at which the bearing is to be used in advance, and is generally a process performed in a tempering process. However, depending on the processing temperature, tempering of the bearing material proceeds, so that a softening phenomenon due to the tempering occurs. That is, when dimensional stabilization processing is performed for normal tempering, the hardness of the bearing tends to decrease.

Further, the reduction in hardness increases the elongation and toughness of the bearing material, and the material becomes sticky, so that it becomes difficult to finish the bearing in the grinding step and the roughness of the bearing raceway surface tends to deteriorate.
Therefore, it has been confirmed that such high-temperature bearings tend to be easily worn due to deterioration in roughness under severe lubricating conditions using fluorine-based lubricating oil.
As described above, it has been confirmed that when the roughness of the inner ring and the outer ring is deteriorated, the rolling elements are worn under the lubricating condition of the fluorine-based lubricating oil. FIG. 2 shows the relationship between the roughness of the inner ring and the outer ring and the life. When the roughness of the inner ring and the outer ring exceeds 0.05 μmRa, the life is remarkably reduced. If the thickness is 0.04 μmRa or less, a stable life can be obtained. Therefore, the thickness is desirably 0.04 μmRa or less. In addition, the improvement of the roughness is good from the viewpoint of the service life, but it is quite difficult to reduce the roughness to less than 0.01 μmRa in a normal bearing manufacturing process in consideration of the performance and the processing time of the working process. Since the processing cost increases extremely, the roughness of the inner ring and the outer ring is desirably 0.01 μmRa or more.

  If the inner and outer rings have poor roughness, metal contact and contact wear are likely to occur, but it is known that such contact wear also involves the roughness of the mating side (see Japanese Patent Application Laid-Open No. 6-50344). ). The same phenomenon appears even under lubricating conditions using a fluorine-based lubricating oil. If the roughness of the rolling elements is too good, the rolling elements will wear even if the inner and outer rings have a roughness of 0.05 μmRa or less.

  FIG. 3 shows the relationship between the ratio of the surface roughness of the inner ring or the outer ring to the surface roughness of the rolling elements (hereinafter, also simply referred to as roughness ratio) and the life. When the roughness ratio exceeds 6, the life is remarkably reduced. Similarly, if the roughness ratio is 5 or less, a stable life can be obtained. Therefore, the roughness ratio is desirably 5 or less. In addition, the reduction in the roughness ratio is good from the viewpoint of life, but when the rolling element is particularly a ball, the roughness is originally better than the inner ring and the outer ring, and in order to reduce the roughness ratio, However, it is necessary to make the roughness of the inner and outer rings extremely high. However, as described above, a significant improvement in roughness cannot be expected in the normal bearing manufacturing process. If the ratio is reduced, the acoustic level of the bearing is reduced. Therefore, the roughness ratio is desirably 3 or more in consideration of the processing cost and the acoustic level.

In addition, the alloy steel containing a large amount of Cr forms a dense and stable oxide film (passivity) on the surface, and is hard and slow in grain growth (small grain size) M ₇ C ₃ type or M ₂₃ C ₆ type. To produce carbides. Due to the presence of the oxide film and the carbide on at least the surface of the rolling element, even when the lubricating film becomes thin and direct contact between the rolling surface of the rolling element and the raceway surface of the bearing ring occurs, the occurrence of adhesion wear occurs. Can be prevented. Further, even when the contact point between the rolling element and the bearing ring becomes extremely hot locally, it is possible to suppress the corrosion of the surface of the rolling element and the bearing ring due to the fluorine-based lubricant and the fluoride gas.

In order to obtain such an effect, the Cr content of the alloy steel used must be 7% by weight or more. However, if the Cr content of the alloy steel used exceeds 27% by weight, a huge Cr carbide is formed at the stage of the material, and stress concentration occurs around the material, which is not preferable. In addition, since Cr is an expensive element, the cost increases if it is contained in a large amount.
A preferable range of the Cr content of at least the alloy steel forming the rolling elements is 7% by weight or more and 25% by weight or less, a more preferable range is 7% by weight or more and 22% by weight or less, and a further preferable range is 10% by weight or less. % By weight or more and 22% by weight or less. Further, at least the alloy steel forming the rolling element preferably has a Cr content of 7% by weight or more and 27% by weight or less, and a Si content of 0.10% by weight or more and 1.5% by weight or less.

It is necessary that Si is contained in an amount of 0.10% by weight or more as a deoxidizer during steelmaking. Si is an element effective for improving the rolling fatigue life, but reacts with a fluorine-containing polymer or fluoride in a high-temperature environment to generate silicon fluoride (Si ₂ F ₆ ) gas. But also. When the contact point between the rolling element and the bearing ring becomes extremely high locally, this gas is used to remove the fluorine-containing polymer contained in the lubricant or the fluoride in the atmosphere gas and the rolling element and the bearing ring. It is caused by the reaction with Si in the alloy steel to be formed. Therefore, with the generation of the gas, the rolling surface of the rolling element and the raceway surface of the bearing ring become brittle, and wear occurs between the rolling surface of the rolling body and the raceway surface of the bearing ring. In order to prevent the generation of silicon fluoride gas and prevent such abrasion, the silicon content in the alloy steel used is preferably set to 1.5% by weight or less. %, More preferably at most 0.8% by weight.

In addition, at least the alloy steel forming the rolling elements has a Cr content of 7% by weight or less and 27% by weight, a Si content of 0.10% by weight or more and 1.5% by weight or less, and an N content of 0% or less. It is desirable that the content be 0.05% by weight or more and less than 0.20% by weight.
When N is contained in the alloy steel, martensite generated by quenching is strengthened, and pitting corrosion resistance is improved. Therefore, when the contact point between the rolling element and the bearing ring becomes extremely hot locally by using the alloy steel containing N, a fluorine-based lubricant or a fluoride gas It can suppress that corrosion due to is caused. In addition, when N is contained in the alloy steel, formation of a huge Cr carbide is suppressed, so that early exfoliation due to stress concentration is prevented.

  In order to obtain such an effect, the N content of the alloy steel used must be 0.05% by weight or more. However, in order to contain 0.20% by weight or more of N in the alloy steel, it is necessary to perform the steelmaking in a high-pressure N atmosphere, and the cost is increased by the cost of the production equipment and maintenance. If an attempt is made to contain N of 0.20% by weight or more by steelmaking at atmospheric pressure, bubbles are generated during the solidification process, and a large amount of pores are contained in the ingot, and a large amount of retained austenite is generated during quenching, and the There is a possibility that the hardness may decrease. In order to avoid such a situation, the N content of the alloy steel used is preferably less than 0.20% by weight. A more preferable N content is 0.05% by weight or more and 0.19% by weight or less, and a still more preferable N content is 0.08% by weight or more and 0.19% by weight or less.

Preferably, at least the alloy steel forming the rolling elements contains Mn at a content of 1.5% by weight or less in addition to Cr, Si, and N described above. Mn acts as a deoxidizer during steelmaking. In addition to these, it is preferable to contain Mo for improving hardenability, V for improving abrasion resistance, and the like.
In addition, it is preferable that at least one of the inner ring, the outer ring, and the rolling element has a hardness of the raceway surface or the rolling surface of Hv450 or more. As a result, even when a certain amount of load is applied, it is possible to prevent the permanent deformation (dent) due to the composition deformation from occurring at the contact point between the raceway surface of the bearing ring and the rolling surface of the rolling element. As a result, even if a certain load is applied, the rolling fatigue life is not extremely reduced.

It is sufficient that at least the rolling element is made of an alloy steel having a Cr content of 7% by weight or more and 27% by weight or less. The inner ring and the outer ring are made of a material generally used conventionally. Can be formed. Examples of the material include bearing steels such as SUJ2 and NSJ2, silicon nitride (Si ₃ N ₄ ), silicon carbide (SiC), sialon (Sialon), partially stabilized zirconia (ZrO ₂ ), and alumina (Al ₂ O ₃ ). Ceramics.

Also, by using a ceramic material mainly composed of zirconia, which is a chemically very stable oxide ceramic, or a ceramic material mainly composed of alumina, on the surface of the rolling element or the rolling element itself, Very little reaction with PFPE oil, even when locally hot. As a result, wear can be further reduced and the life can be prolonged.
In addition, especially when used in a vacuum environment, the rolling element surface is made of a dense nitride layer with a hardness of Hv900 or more and harder than the inner and outer rings, thereby preventing peeling and reducing wear, and operating at high speed for a long period of time. Can be. In addition, by having a nitrided layer on the surface, it is possible to suppress the decomposition of the fluorine-based lubricating oil and improve the lubricity. Further, since the nitrided layer has lower reactivity than the steel surface, it is possible to reduce corrosion wear on the surface.

Furthermore, since the combination of the inner ring, the outer ring and the rolling elements is a combination of steel and a nitride layer, wear is less likely to occur than the combination of steel and steel (combination effect of different materials). When the surface roughness of the rolling elements exceeds 0.005 μm Ra, the roughness of the rolling elements is so poor that rough wear is likely to occur. Therefore, the surface roughness of the rolling elements is 0.005 μm Ra or less.
Further, the configuration may be the same as that of a general rolling bearing, except that at least the rolling elements are different among the inner ring, the outer ring, and the rolling elements. Therefore, materials used other than the rolling elements include generally used bearing steels (SUJ2, carburized steel, etc.), martensitic stainless steels (SUS440C, 0.45C-13Cr-0.13N martensitic stainless steels, etc.), Precipitation hardening stainless steel (SUS630 etc.), titanium alloy, etc. can be mentioned, but it is not particularly limited to these.

  Further, when the above-described foreign matter biting mark and abrasion pattern were observed in more detail, it was found that the same scar was repeatedly left. From this result, it is considered that foreign matter is mixed in as a cause of the peeling damage as described above. That is, as the foreign matter is fixed on the raceway surfaces of the inner ring and the outer ring, and the rolling elements are repeatedly scratched, the roughness of the rolling surface of the rolling elements increases, and the surface of the raceways of the inner ring and the outer ring is eventually formed. The mechanism that peeling damage occurs is assumed.

  Then, the rolling bearing lubricated with the fluorine-based lubricating oil was rotated, and the raceway surface of the rolling bearing was observed in a relatively good state before the peeling failure occurred. As a result, even in such an initial fatigue state, it was confirmed that the same scar was repeatedly applied to the inner ring, the outer ring, and the rolling elements. When the state and components of the fixed foreign matter were investigated, it was found to be a ceramic component such as alumina which is a non-metal component.

  In addition, for unused rolling bearings lubricated with fluorine-based lubricating oil, observation of the raceway surface revealed that, although a little, the presence of ceramic components and metallic foreign matter was confirmed. It has been found that foreign matter may have already adhered to the raceway surface. Then, it was considered that such foreign matter was such that abrasive grains forming a working grindstone used when finishing the raceway surface of the rolling bearing by grinding were left on the raceway surface.

From these facts, the rolling bearing lubricated with the fluorine-based lubricating oil has a slight abrasive grain remaining on the raceway surface of the rolling bearing in the grinding process, causing the peeling damage, greatly reducing the life of the rolling bearing. I knew it was possible.
On the other hand, as compared with the foreign matter adhering to the raceway surface of the unused rolling bearing, foreign matter adhering to the raceway surface of the rolling bearing in a relatively good state before the peeling breakage was found. There was a great variation in the frequency of the treatment and the amount present. From this, it was easily presumed that the cause of the peeling breakage was not only foreign substances such as slight abrasive particles remaining on the raceway surface of the rolling bearing in the grinding process.

  Therefore, the present inventors have further investigated the route of entry of foreign matter, and as a result, have confirmed that a ceramic component or a metal-based foreign matter is present in the fluorine-based lubricant filled in the rolling bearing. This is because fluorine-based lubricating oils are relatively expensive compared to ordinary lubricating oils, and are often used after subdividing a small amount (about 0.5 to 2 liters) into containers made of resin or the like. It was presumed that the fluorine-based lubricating oil could be contaminated by foreign matter present in this container.

In order to remove the foreign matter adhering to the raceway surfaces of the inner ring and the outer ring as described above, it is effective that the raceway surfaces of the inner ring and the outer ring be subjected to surface processing such as barrel processing. Furthermore, it has been found that it is effective to filter the fluorine-based lubricating oil in order to remove foreign substances contained in the fluorine-based lubricating oil.
Further, as a method for preventing foreign matters having an average diameter exceeding 3 μm from being present on the raceway surface, a method of performing a surface processing treatment on the raceway surface may be mentioned. By this processing, the foreign matter existing on the track surface can be removed. Examples of the surface processing include barrel processing and cloth processing.

Further, there is a method of filtering a fluorine-based lubricating oil before filling the gap portion of the rolling bearing. Since foreign matter in the fluorine-based lubricant is removed by the filtration, no foreign matter is supplied from the fluorine-based lubricant onto the raceway surface.
The surface treatment and the filtration of the fluorine-based lubricating oil may be performed by either one of them. However, by performing both of them, a higher effect can be obtained, and a rolling bearing having a longer life can be obtained.

The rolling bearing used in the vacuum pump is usually made of bearing steel (SUJ2) and is hardened. The hardness of the bearing steel after quenching is Hv750 to 800.
Rolling bearings for vacuum pumps tend to be used under high temperature and high speed conditions. Further, in a vacuum pump used in a semiconductor manufacturing apparatus or the like, a corrosive gas may be exhausted, and a lubricating oil having low reactivity is used for lubricating the rolling bearing. As described above, fluorine-based lubricating oil has poor lubricity, and abrasion may occur on the bearing rolling surface due to poor lubrication. In order to prevent this abrasion, the abrasion can be reduced by further hardening the bearing rolling surface.

  Further, as described above, the fluorine-based lubricating oil reacts with iron to produce iron fluoride, which further acts as a catalyst to decompose the fluorine-based lubricating oil. On the other hand, by coating the iron surface of the rolling bearing with another material, the decomposition of the fluorine-based lubricating oil can be suppressed and prevented, and the lubricity can be improved accordingly. In particular, the ceramic coating is effective in suppressing the decomposition of the fluorine-based lubricating oil.

  Further, the present inventors conducted a life test under a lubricating condition using a fluorine-based lubricating oil using a plastic retainer to prove an estimation mechanism up to the occurrence of the peeling. The device did not damage the rolling element due to contact with the rolling element, and the wear powder had a low hardness, so that the inner and outer rings and the rolling element were not damaged, resulting in a long life. From these, the inventors of the present application have found that the combination of the material of the cage and the rolling elements greatly affects the bearing life caused by peeling damage under lubricating conditions using fluorine-based lubricating oil.

  Thus, the rolling bearing according to claim 1 of the present invention is an outer ring having an outer raceway, an inner race having an inner raceway, and a rolling element rotatably disposed between the outer raceway and the inner raceway. Comprising, between the outer raceway and the inner raceway, having a retainer that evenly distributes the rolling elements in the revolving direction of the rolling elements, under lubrication with lubricating oil or grease containing a fluorine-containing polymer, or In a rolling bearing used under an atmosphere containing a gas composed of a fluoride, the cage is formed of a high-performance resin material in an annular shape, and the pocket holds the rolling element from an opening and holds the rolling element so as to be able to roll. Are provided at predetermined intervals in the circumferential direction, and the dimension of the opening of a pocket having a weld line is 93% or more of the rolling element diameter, and the dimension of the opening of at least two or more other pockets Are respectively It is characterized in that at most 93% 80% or more element diameter.

  The rolling bearing according to claim 2 of the present invention includes an outer ring having an outer raceway, an inner race having an inner raceway, and a rolling element rotatably disposed between the outer raceway and the inner raceway. A retainer for equally arranging the rolling elements in the revolving direction of the rolling elements between the outer raceway and the inner raceway, and under lubrication with lubricating oil or grease containing a fluorine-containing polymer, or In a rolling bearing used in an atmosphere containing a gas composed of a nitride, the cage is made of a PTFE resin material or a PPS resin material, or a chamfer is formed on the inner and outer diameter sides of the pocket and the pocket is formed. It is characterized in that either one or both of them are provided by providing a through hole at the bottom.

The rolling bearing according to claim 3 of the present invention includes an outer ring having an outer raceway, an inner race having an inner raceway, and a rolling element rotatably disposed between the outer raceway and the inner raceway. A retainer for equally arranging the rolling elements in the revolving direction of the rolling elements between the outer raceway and the inner raceway, and under lubrication with lubricating oil or grease containing a fluorine-containing polymer, or In a rolling bearing used under an atmosphere containing a gas composed of a nitride, the cage is formed of a high-performance resin material in an annular shape, and has a pocket that accommodates the rolling element from an opening and holds the rolling element in a rolling manner. A plurality of pockets provided with a predetermined interval in the circumferential direction and having a weld line have an opening dimension of 93% or more of the rolling element diameter, and an opening dimension of at least two or more other pockets. Respectively, The retainer is made of a PTFE resin material or a PPS resin material, or has a chamfer formed on the inner and outer diameter sides of the pocket and has a through hole at the bottom of the pocket. And one or both of them.
The high-performance resin material is preferably a high-performance engineering plastic having excellent corrosion resistance, specifically, polyphenylene sulfide (PPS) resin, polyetheretherketone (PEEK) resin, polybutylene terephthalate (PBT) resin, or the like. Used.

  As described above, according to the rolling bearing according to claim 1 of the present invention, among the rolling element pockets of the cage formed of a high-performance resin material in an annular shape, the opening dimension of the pocket having the weld line is reduced. By setting the value of the rolling element diameter to 93% or more and the size of the opening of at least two other pockets to 80% or more and 93% or less of the rolling element diameter, respectively, When the rolling elements are incorporated into each pocket, cracks, cracks, and the like can be reliably prevented from being formed at the bottom of the pocket having the weld line, while reliably preventing falling off of the rolling elements.

  Further, according to the rolling bearing according to claim 2 of the present invention, the cage is formed of a PTFE resin material or a PPS resin material, or a chamfer is formed on the inner and outer diameter sides of the pocket and the bottom of the pocket is formed. Since the through holes are provided, it is difficult for the wear powder of the cage to be generated, the lubricant does not deteriorate, the indentation hardly occurs on the raceway surface, and the lubrication performance can be improved. It is possible to extend the life under the conditions.

  According to the rolling bearing according to claim 3 of the present invention, among the rolling element pockets of the cage formed of a high-performance resin material in an annular shape, the opening dimension of the pocket having a weld line is determined by the rolling element diameter. And the opening dimensions of the other two or more pockets are set to values of 80% to 93% of the rolling element diameter, respectively, and the retainer is made of a PTFE resin material or a PPS resin material. Because it is configured to have a chamfer on the inner and outer diameter sides of the pocket and to provide a through hole at the bottom of the pocket, it is possible to reliably prevent the cage from falling off the rolling bearing, When the rolling element is incorporated into the pocket, cracks and cracks can be reliably prevented from forming at the bottom of the pocket with the weld line. Agent does not degrade, the indentation is less likely to occur in the raceway surfaces, it is possible to improve the lubricating performance, it is possible to extend the life of a fluorine-based lubricating conditions.

Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a cross-sectional view of the rolling bearing of the present embodiment. This rolling bearing is a deep groove ball bearing, and is composed of a plurality of rolling elements (balls) 5, an inner ring 3 located inward therefrom, and an outer ring 1 located outward therefrom. While being held between the inner race 3 and the outer race 1, the rolling guide is provided. At this time, the inner ring 3 and the outer ring 1 are provided with rolling grooves for guiding the rolling elements 5, and the rolling elements 5 are equally held by the retainers 6 in the rolling grooves.

  The first embodiment of the present invention is premised on a rolling bearing, such as a vacuum pump device, which is depressurized including a vacuum and lubricated with a fluorine-based lubricant. As shown in Table 1 below, as an example and a comparative example of this embodiment, a plastic cage was prepared as an example, and a metal cage was prepared as a comparative example. Examples of the plastic cages include polyamide nylon 66 and polyphenylene sulfide (PPS), which are thermoplastic plastics. As the metal cages of the comparative examples, the low-carbon steel plates SPCC and A cage having the same shape was manufactured using S50CM, a tempered steel.

  On the other hand, the inner and outer rings and rolling elements are quenched at 830 ° C to 850 ° C using JIS bearing steel SUJ2, and then tempered at 230 ° C to 260 ° C as a dimensional stabilization process only for the inner and outer rings. Was subjected to tempering at a temperature of 160 ° C. to 200 ° C. in a normal specification, and was subjected to grinding and finishing, and the various retainers were combined therewith to finally produce a deep groove ball bearing 6206 having a value specified in JIS B 1518. Regarding the roughness of the raceway surface, test bearings having various roughnesses were prepared as described later by changing the grinding method or repeatedly performing finish grinding.

Next, test conditions will be described. Tester, using NSK Ltd. ball bearing life tester, to measure the basic rating life (10 ⁶ revolutions) L ₁₀ under clean lubrication. The lubricating oil used was a fluorine-based lubricating oil J100 (a perfluoropolyether oil manufactured by NOK Cryuba), which is the object of the invention, and a general spindle oil RO # 68 (a paraffinic mineral oil) as a comparative example. Although the present embodiment is intended for a rolling bearing used in a reduced-pressure atmosphere, in particular, fluorine-based lubricating oil does not change much under vacuum or atmospheric pressure. Do. In order to make the lubrication conditions strict, the test temperature was evaluated between 80 ° C. and 120 ° C., assuming that the lubricating oil temperature would rise and the oil film would decrease.
(Life test conditions)
Test machine name: Ball bearing life test machine Test load: P / C = 0.45
Bearing rotation speed: 3000 rpm
Test temperature: 80-120 ° C
Lubricating oil: Fluorine-based lubricating oil J100
Paraffin mineral oil RO # 68

  The test method is as follows. Ten test specimen bearings are prepared, and a life test is performed under the test conditions described above. To determine the life, the test was interrupted when the vibration value of the specimen bearing on the tester became twice the initial vibration value, the presence or absence of peeling on the raceway surface, the rolling elements and the pockets of the cage were determined. Wear was confirmed. Further, the longest test time was set to 500 hours, and thereafter, the test was terminated. Then, the total rotation time until peeling or abrasion occurred in 10% of the bearings from the short life side of the ten specimen bearings was determined from the Weibull distribution function, and this was defined as the life. Table 2 below shows the life time of Comparative Examples a to n lubricated with paraffinic mineral oil RO # 68, Comparative Examples A to H lubricated with fluorine-based lubricating oil J100, and Examples IP. In addition, the thing whose life time exceeded 500 hours is described as discontinuation.

As is clear from Table 2, in Comparative Examples a to n using paraffinic mineral oil lubrication, the paraffinic mineral oil has good wettability, so that peeling hardly occurs even in a metal cage. However, the test temperature is high, under conditions where the oil film is reduced, a material is the hardest S550CM cages (comparative example f), peeling by several points of peeling occurs, L ₁₀ life became about 350 hours Was. From this, it is understood that the difference in the material of the retainer does not greatly affect the bearing life under the paraffinic mineral oil lubrication.

  On the other hand, in Comparative Examples A to H using fluorine-based lubricating oil lubrication, the higher the test temperature, the shorter the life due to early peeling. In the bearings after these tests, the rolling elements were severely damaged, for example, similarly to defective products on the market, and the bearings with shorter life were worn. Peeling occurs on the inner and outer rings. This is because the wettability of the fluorine-based lubricating oil is not good as described above, so that insufficient lubrication occurs between the pocket portion of the cage and the rolling element, and the harder the cage, the more the lubricating oil film becomes. The lower the temperature (the higher the temperature), the earlier the wear and peeling occurred, proving that the bearing life was shortened. Also, in the SPCC cage having a low hardness, oxidized wear powder due to metal contact is observed, and since the oxidized wear powder is higher in hardness than the cage, it can cause indentation on the inner and outer rings, It is considered that abrasive wear occurred between the outer ring and the rolling elements.

  On the other hand, Examples I to P using the plastic cage exhibited a long life even under the lubrication of the fluorine-based lubricating oil. This is considered to be because wear between the steel rolling element and the plastic cage is hardly generated, and even if it is generated, the wear powder is soft, so that secondary defects such as indentations are hardly generated. Can be In Example L, peeling occurred in the nylon 66 cage. However, since the test temperature was as high as 120 ° C., the lubricating oil film was reduced and the cage was near the service limit of nylon 66. It is considered that the rotation of the rolling element occurred due to the deformation of the rolling element. Accordingly, a PPS-made cage is preferable especially when the use condition is a high temperature.

  Next, by the same test method as described above, the surface roughness of each of the inner ring and the outer ring and the roughness ratio with the rolling elements were variously changed, and a life test was performed by combining them. Table 3 shows the surface roughness and the roughness ratio with the rolling elements. As the roughness ratio of the inner ring or the outer ring to the rolling elements in the table, the one having the lower roughness, that is, the one having the larger value among the inner rings or the outer rings is adopted. In Examples 1 to 10 in which the fluorine-based lubricating oil J100 was used as the lubricant, the surface roughness of the inner ring and the outer ring and the roughness ratio with the rolling elements all satisfied the above-mentioned conditions. Similarly, among Comparative Examples 11 to 16 using fluorine-based lubricating oil J100 as a lubricant, Comparative Example 13 had a surface roughness of an inner ring, and Comparative Example 14 had a surface roughness of an outer ring satisfying the above conditions. However, Comparative Examples 11, 12, 15, and 16 did not satisfy the condition that the roughness ratio with the rolling element was 6 or less. The comparative examples 17 and 18 for reference use paraffinic mineral oil RO # 68 as a lubricant, of which the comparative example 17 has a surface roughness of an inner ring, and the comparative example 18 has a roughness ratio with a rolling element. The conditions are not satisfied. In Examples 9 and 10 and Comparative Examples 15 and 16, the test temperature was changed.

  As is clear from Table 3, Examples 1 to 10 in which the surface roughness of the inner ring and the outer ring and the roughness ratio of the inner ring and the outer ring to the rolling elements satisfy the above-described conditions, show that the strict lubrication conditions using a fluorine-based lubricating oil having poor wettability were used. However, each of them achieves a long life of more than 400 hours. This proves that the surface roughness of the inner ring and the outer ring and their ratio of roughness to the rolling elements influence the contact wear. On the other hand, the comparative examples 13 and 14 in which the surface roughness of the inner ring or the outer ring exceeds 0.05 μmRa, and the comparative examples 11 and 12 in which the roughness ratio with the rolling elements exceeds 6 clearly have a shorter service life, and further have a further test. Comparative Examples 15 and 16 in which the temperature was increased had a shorter life. However, even in Comparative Example 17 in which the surface roughness of the inner and outer rings exceeds 0.05 μmRa, and in Comparative Example 18 in which the roughness ratio with the rolling element exceeds 6, the lubrication condition with mineral oil has a long life. It was confirmed that various problems were peculiar to the fluorine-based lubricating oil.

  Next, a second embodiment of the rolling bearing of the present invention will be described. As in the first embodiment, this embodiment is based on the premise that a rolling bearing lubricated with a fluorine-based lubricating oil and a reduced pressure including a vacuum, such as a vacuum pump device. As an example and a comparative example of this embodiment, a coating treatment as shown in Table 4 below was applied to a deep groove ball bearing 6206 (see FIG. 1 of the first embodiment) having a value specified in JIS B 1518. Was given. Among them, in Examples 101 to 107 of the present invention, a coating film having a hardness (Hv 750 to 800) after quenching ordinary bearing steel SUJ2 is coated on at least the rolling elements, and preferably on all parts. On the other hand, in Comparative Examples 101 and 102, all parts are coated with a coating of nickel and Ni-P, but their hardness is soft. In Comparative Example 103, the hardness of the coating is sufficiently hard, but the coating covers only the inner and outer rings except the rolling elements.

The conditions for the bearing wear test are as follows.
Rolling bearing: 6206 (bearing steel SUJ2 Hv760)
Surface pressure: 180kgf / mm ²
Temperature: 150 ° C
Rotation speed: 3600 rpm
Lubricating oil: Fluorine oil (Fomblin oil Y25 (Audimont))
Test time: 100 hours Coating thickness: 2-5 μm

FIG. 4 shows the relationship between the ratio of the rolling element wear rates of Examples 101 to 107 and the coating hardness when the rolling element wear rates of Comparative Examples 101 to 103 were set to 1. As is clear from the figure, as the hardness of the coating increases, the rolling element wear decreases. Further, in Examples 101 to 106, since the ceramic-based hard coating has low reactivity with the fluorine-based lubricating oil, wear is further reduced. Further, in Example 107 in which only the rolling elements were coated with the coating, the amount of wear of the rolling elements was larger than that in Examples 101 to 106 in which all parts were coated with the coating, but still far as compared with Comparative Examples 101 to 103. Less. In Comparative Examples 101 and 102, since the hardness of the coating is softer than that of the base material, the coating tends to be worn at an early stage. Further, in Comparative Example 103 in which the coating was coated only on the inner and outer rings, the wear of the rolling elements could not be prevented.
As described above, in the present embodiment in which at least the rolling elements, and preferably all parts, are coated with a coating harder than the hardness of the base material, the wear of the rolling elements can be reduced, and even under severe lubrication conditions using fluorine-based lubricating oil. Long life can be achieved.

  Next, a third embodiment of the rolling bearing of the present invention will be described. In this embodiment, similarly to the first embodiment, like a vacuum pump device, a reduced pressure including vacuum, and under lubrication with a lubricating oil or grease containing a fluorine-containing polymer, or a gas made of fluoride It is assumed that the rolling bearing is used in an atmosphere including. First, alloy steels having compositions shown in Table 5 below were prepared as alloy steels forming the inner ring, the outer ring, and the rolling elements. The units of the numerical values in Table 5 are all weight%.

  Using these alloy steels, an inner ring, an outer ring, and a rolling element of a single row deep groove ball bearing (nominal number 6206: outer diameter 62 mm, inner diameter 30 mm, width 16 mm, see FIG. 1 of the first embodiment) are formed. Rolling bearings were assembled using the combinations shown in Table 6 below. In addition, each sample was produced so that all points other than the used alloy steel were the same. That is, the inner ring, outer ring, and rolling elements of each sample are quenched and tempered under the condition of a predetermined surface hardness (450 or more in Vickers hardness).

For each of the assembled rolling bearings, a rotation test was performed using a bearing rotation tester manufactured by Nippon Seiko Co., Ltd. under the following conditions, and the bearing life was evaluated based on the vibration value. That is, the radial vibration generated in the bearing was constantly measured during the rotation test, and when the vibration value became three times or more of the initial value, the test was stopped, and the time taken until that time was taken as the life.
(Rotation test conditions)
Ambient temperature: 150 ° C
Atmospheric pressure: vacuum (1 × 10 ^-4 Torr)
Axial load: 1000N
Radial load: 500N
Rotation speed: 300 rpm
Lubricant: "Fomblin M15" manufactured by Ausimond
(Perfluoropolyether oil)
Further, in order to compare the lifespans of the test bearings, a relative value was calculated when the lifespan of Comparative Example 401 corresponding to the conventional example was set to “1”. These results are also shown in Table 6 below.

As can be seen from the results, the bearings of Examples 401 to 420 in which at least the alloy steel forming the rolling elements satisfies the above-mentioned recommended range have a lower performance than the bearings of Comparative Example 401 in which both the rolling elements and the inner and outer races are made of SUJ2. When a fluoropolyether oil is used as a lubricant and used under high temperature and high speed rotation, the bearing life is long.
In Examples 401 to 409 in which the inner and outer races are made of SUJ2 and the alloy steels forming the rolling elements are different within the recommended range, the N content is in the range of 0.05% by weight or more and less than 0.2% by weight. Certain Examples 404 to 407 have a longer bearing life than Examples 401 to 403 and Examples 408 and 409 in which the N content is out of this range.
In addition, when not only the rolling elements but also the inner ring and the outer ring are made of an alloy steel satisfying the scope of the present invention as in Examples 410 to 420, the bearing life can be further extended. .

  In this embodiment, the bearing life under high temperature and high speed rotation when perfluoropolyether oil is used as the lubricant is described, but lubrication containing a fluorine-containing polymer other than perfluoropolyether oil is described. Even under lubrication with oil or grease, even under an atmosphere containing a gas consisting of fluoride, it is possible to extend the bearing life by at least making the alloy steel forming the rolling elements satisfy the recommended range. it can.

  Next, a fourth embodiment of the rolling bearing of the present invention will be described. In this embodiment, as in the first embodiment, a vacuum pump device, a heat roll section of a fixing section of office equipment, a vacuum apparatus for manufacturing semiconductors, and the like, such as a vacuum apparatus for manufacturing semiconductors, are subjected to reduced pressure including vacuum and fluorine-based heavy load. It assumes a rolling bearing used under lubricating conditions with a lubricant containing coalescing.

First, a durability life test performed under the conditions of a fluorine-based lubricant, high temperature, high speed, and high vacuum will be described.
Specimen rolling bearing:
Model number 6206, inner diameter 30mm, outer diameter 62mm, width 16mm
(For the shape, see FIG. 1 of the first embodiment)
The thing which changed the combination of the material of each inner ring, the outer ring, and the rolling element was prepared. The rolling element material of the rolling bearing of the embodiment was alumina in the embodiment 502, and partially stabilized zirconia in the other embodiments. On the other hand, the rolling element of Comparative Example 501 was SUJ2, and the rolling element of Comparative Example 502 was silicon nitride.

Test method:
The test sample bearing was mounted on a bearing rotation tester manufactured by Nippon Seiko Co., Ltd., and a rotation test was performed under the following test conditions, and the life was evaluated based on the vibration value. Here, the time when the vibration value increased to three times the initial value was defined as the life of the test specimen bearing. In addition, the life of the rolling bearing in each of Examples and Comparative Examples is represented by a relative value when Comparative Example 501 is set to 1.

Test condition:
Temperature: 120 ° C
Atmosphere: vacuum (1.33 × 10 ^-2 Pa)
Rotation speed: 5000 rpm
Axial load: 1000N
Radial load: 500N
Lubricant: "Fomblin M15" (PFPE oil) manufactured by Ausimond
Table 7 shows the test results.

From the results in Table 7, it is clear that all the rolling bearings (Examples 501 to 507) of the present invention show much longer life under the conditions of PFPE oil lubrication, high temperature and high speed than the Comparative Example. It is.
Next, a description will be given of a wear test of a rolling bearing for a vacuum pump performed under fluorine-based lubrication.
Specimen rolling bearing:
Model No. 6206 (Material of inner ring and outer ring; bearing steel SUJ2, hardness Hv760)
13Cr martensitic stainless steel containing 0.45% by weight of C, 13.04% by weight of Cr, and 0.13% by weight of N was used as a rolling element material other than Comparative Example 503 (SUJ2).

  This was cold-worked (header) and deburred or cut to produce elementary balls. After quenching this elementary ball at 1060 ° C., it was subjected to sub-zero treatment at −80 ° C., and then tempered at 160 ° C., and finished to a predetermined accuracy. Next, nitriding treatment was performed by adopting an Nv nitriding process (trade name of Daido Hokusan Co., Ltd.), and finishing lapping was performed to adjust the surface roughness to the same as that of SUJ2 steel balls. (See Tables 8 and 9).

Here, the Nv nitridation process will be described. This process includes a process of performing a fluorination process at about 200 to 400 ° C. using a fluorine gas such as NF ₃ (nitrogen trifluoride) as a pretreatment of the nitriding process. And a process of performing a nitriding treatment with NH ₃ gas. By the fluoridation treatment, the Cr oxide layer that inhibits the nitridation reaction is removed, and the surface with the extremely thin fluorinated layer formed on the surface layer is extremely activated, and the subsequent nitridation treatment forms a stable and uniform nitrided layer. It can be suitably applied to martensitic stainless steel having high hardness and excellent wear resistance.

By this nitriding process, a compound layer having a steel ball diameter ratio of 1.4% Da as a nitrided layer is formed, and the surface hardness is determined by the amount of removal from the steel ball surface after nitriding (the more the hardness, the lower the hardness. ). In this way, the bearings with the surface hardness and roughness varied in various ways were prepared by forming a nitrided layer on the surface of the rolling element of each test specimen bearing.
The life of the bearing can be further improved by providing the inner ring and the outer ring with the same nitride layer as the rolling elements. However, since the inner ring and the outer ring are less likely to form a nitride layer than the rolling elements, in this test, the inner and outer rings were not subjected to the nitriding treatment, and only the surface roughness was changed to the nitride layer surface roughness (0 No. 6206 rolling bearing having the same surface roughness as that of the No. 0.003 μm) was used, and the amount of wear was taken as the life.

Test method:
Each of the sample bearings of the examples and the comparative examples was used as a test body, mounted on a bearing rotation tester manufactured by the company, and rotated under fluoro oil lubrication for 100 hours. Thereafter, the sample bearing was disassembled, and the wear amount of the rolling elements was measured. In addition, the wear amount ratio of the rolling elements in each example and the comparative example was represented by a relative amount where the wear amount of the comparative example 503 (untreated bearing) was set to 1.
Abrasion test conditions:
Rolling bearing: 6206 (bearing steel: all SUJ2, Hv760)
Surface pressure: 1764MPa
Temperature: 150 ° C
Rotation speed: 3600 rpm
Lubricating oil: “Fomblin oil Y25” (fluorine oil) manufactured by Audimont Corporation
Test time: 100 hours The test results are shown in Tables 8 and 9.

From the results shown in Tables 8 and 9, all the rolling bearings (Examples 501 to 504) of the present wear test showed significantly less wear than the comparative example under the conditions of fluoro oil lubrication, high temperature, and high speed. It is clear that there are few.
Among these, the relationship between the rolling element hardness and the wear amount ratio was organized for Example 501, Example 503, Example 504, Comparative Example 501, and Comparative Example 503 having a common rolling element roughness of 0.003 μmRa. As shown in FIG. From this figure, it can be seen that under the condition that the rolling element roughness is constant (0.003 μm), when the rolling element hardness is Hv900 or more, extremely excellent wear resistance is exhibited and the life is extended.

  Next, FIG. 6 summarizes the relationship between the rolling element surface roughness and the wear amount ratio for Example 502, Example 503, and Comparative Example 502 having a common rolling element hardness Hv1050. FIG. 6 shows that under the condition that the hardness of the rolling element is constant (Hv1050), when the surface roughness of the rolling element is 0.005 μmRa or less, it shows remarkably excellent wear resistance and a long life.

Therefore, the rolling bearing has a dense nitride layer at least on the surface of the rolling element, and the nitride layer is made of a compound layer having a hardness of Hv900 or more, and has a roughness of 0.005 μmRa or less. It can be said that an excellent life can be provided under high temperature, high speed conditions or a vacuum environment.
The oxide ceramic or the dense nitride layer in the present embodiment does not need to be limited to only the surface of the rolling element. For example, the rolling element itself may be made of an oxide ceramic.

  Next, a fifth embodiment of the rolling bearing of the present invention will be described. As in the first embodiment, this embodiment is based on the premise that a rolling bearing lubricated with a fluorine-based lubricating oil and a reduced pressure including a vacuum, such as a vacuum pump device. In this embodiment, a thrust ball bearing is used instead of the deep groove ball bearing and the angular ball bearing used in each of the above embodiments.

FIG. 7 is a cross-sectional view illustrating the structure of the thrust ball bearing 101 of the present embodiment.
A thrust ball bearing 101 (manufactured by Nippon Seiko Co., Ltd., designation number 51305) includes an outer ring 102, an inner ring 103, and a plurality of balls (rolling elements) 104 that are rotatably disposed between the two wheels 102, 103; A retainer 105 for holding the plurality of balls 104 between the two wheels 102 and 103, and a fluorine-based lubricating oil 106 formed between the two wheels 102 and 103 and filled in a space in which the balls 104 are provided. Have.

The two wheels 102 and 103 are provided with rolling grooves for guiding the balls 104, and the raceway surfaces 102a and 103a are subjected to surface processing. In addition, as this surface processing, barrel processing, cloth processing, etc. are preferably adopted.
The fluorine-based lubricating oil 106 used was filtered through a 10 μm filter before being filled into the gap of the thrust ball bearing 101. It is necessary to use a filter capable of removing foreign substances contained in the fluorine-based lubricating oil 106.

No foreign matter such as abrasive grains having an average diameter of 3 μm or more was found on the raceway surfaces 102a and 103a of such a thrust ball bearing 101.
In addition, JIS bearing steel SUJ2 material was used for the outer ring 102, the outer ring 103, and the ball 104, and quenching was performed at 830 to 850 ° C. Thereafter, the outer ring 102 and the inner ring 103 were tempered at 230 to 260 ° C. as a dimensional stabilization process, and the balls 104 were tempered at 160 to 200 ° C. in a normal specification. Thereafter, a thrust ball bearing having a value determined by JIS B 1518 was manufactured by a normal grinding process.

A bearing similar to the thrust ball bearing 101 having been subjected to surface processing under various conditions was prepared and subjected to a life test.
Barrel processing and cross processing were performed as the surface processing.
Abrasive grains used for barrel processing were limited to alumina-based abrasive grains used for processing the bearing. Then, treatment was performed using abrasive grains of various sizes to produce bearings for testing. The alumina-based abrasive grains (chips) used are all chips mainly composed of fused alumina, Alundum # 100 (in the case of a strong grinding stone), Alundum # 150 (in the case of a medium grinding stone), and alumina # 1500. 2,000 (in the case of glossy stone) and alumina # 4000 to 6000 (in the case of super glossy stone) (all manufactured by Nippon Diamond Industrial Co., Ltd.).

In the manufacture of the bearing, since the size of the abrasive used varies depending on the processing step, the above-described four types of chips were used in the barrel treatment for the purpose of determining which step was due to the abrasive. The processing time was set to 60 minutes, so that only the influence of the size of the abrasive grains on the life was confirmed.
The crossing process is a process of polishing a raceway surface of a completed bearing in a state in which a relatively durable rigid fiber cloth (hereinafter, referred to as a cloth) is wound around a wooden bar or the like. Regarding the cloth treatment, using a wiping cloth for a clean room (trade name: Xavina Minimax, manufactured by Kanebo Synthetic Fibers Co., Ltd.) as a cloth, the test was performed under five conditions of 0, 30, 60, 120, and 180 seconds. Bearings were manufactured. The pressing load of the cloth was constant.

The thrust ball bearing for a test thus produced was tested using a thrust type bearing life tester manufactured by Nippon Seiko Co., Ltd. under the conditions of a test load: P / C = 0.45 and a bearing rotation speed: 5000 rpm. the basic rating life (10 ⁶ revolutions) L ₁₀ under clean lubrication was measured. As the lubricating oil, a commercially available fluorine-based lubricating oil was used. The life test was performed at atmospheric pressure because the fluorine lubricating oil hardly changes under vacuum or atmospheric pressure. Further, assuming that the temperature of the lubricating oil rises and the formation of an oil film becomes insufficient, the evaluation was performed at a test temperature of 100 to 120 ° C. where the lubricating conditions are severe.

The test was performed using two types of fluorine-based lubricating oil, one not filtered and one filtered through a 10 μm filter. In addition, since the required amount of the fluorine-based lubricating oil may be taken out to another container (on the user side) and used, it is conceivable that foreign matter may be mixed in at the time of refilling. Therefore, by filtering through a 10 μm filter, large foreign matter can be removed without damaging the components of the fluorine-based lubricating oil. Note that a filter of 10 μm was used because it is considered that a foreign substance of 10 μm or less can be removed due to the nature of the filter (bridge effect).
Tables 10 and 11 show the test results. FIG. 8 shows the correlation between the maximum diameter of foreign matter and the life of the bearing when unfiltered fluorine-based lubricating oil is used. FIG. 9 shows the case where filtered fluorine-based lubricating oil is used. 4 shows the correlation between the maximum diameter of the foreign matter and the life of the bearing.

The number and size of foreign matters remaining on the raceway surface were measured by observing the raceway surface with an electron microscope (manufactured by JEOL Ltd.). In the column of the maximum diameter in the table, the value of the maximum average diameter (average value of the major axis and the minor axis) among the observed foreign substances is described.
Further, the life of the thrust ball bearing filled with the fluorine-based lubricating oil was evaluated based on the life time and the Weibull slope. In each of the examples and comparative examples, A shows the test result of a bearing filled with unfiltered fluorine-based lubricant, and B shows the test result of a bearing filled with filtered fluorine-based lubricant. In the bearing life shown in Tables 11 and 12, ">250" indicates that no peeling breakage or wear occurred even if the total number of tested bearings exceeded the calculated life (250 hours). Has been censored.

As described in Tables 11 and 12, as the time for performing the cross processing increases, the number of remaining foreign substances decreases. Therefore, it is estimated that the foreign substances have been removed by the cross processing. Further, the life of the bearing is extended by the cross treatment, and the value of the Weibull slope is also good.
In addition, when the barrel processing is performed, the number of residual foreign substances increases because the abrasive grains adhere to the raceway surface. However, when super-glossy stone is used (Examples 204A to 208A), the bearing has a long life because the abrasive grains are small and the maximum diameter is 3 μm or less even if adhered. When barrel processing is performed using another abrasive having a large diameter (Comparative Examples 203A to 213A), the maximum diameter of the foreign matter exceeds 3 μm, so that the life of the bearing is sufficient even when the cross processing is performed together. is not.

Therefore, the bearing has a long life because no foreign matter such as abrasive grains having an average diameter exceeding 3 μm remains on the raceway surfaces of the inner ring and the outer ring. In order to further stably obtain a long life, it is desirable that no foreign matter having an average diameter exceeding 2 μm remains.
On the other hand, if attention is paid to the presence or absence of filtration of the fluorine-based lubricating oil, the bearing on which filtration is performed clearly has a long life. Furthermore, it can be seen that the bearing having a stable life is manufactured (the quality is stable) because the value of the Weibull slope is large (Examples 201A, B to 208A, B). However, when large foreign matter remains, the life tends to be dominated by the large foreign matter. Accordingly, although some effects were observed in Comparative Examples 202A and 202B having a relatively small maximum diameter, the size of the foreign matter was dominant in other cases (Comparative Examples 201A and 203B and 203A and 213A and 213A and B). Therefore, there was no significant effect by the filtration. That is, even when the filtration is performed, the bearing has a long life because no foreign matters such as abrasive grains having an average diameter exceeding 3 μm remain on the raceway surfaces of the inner ring and the outer ring.

As described above, by removing foreign matters such as abrasive grains remaining on the raceway surfaces of the inner ring and the outer ring by barrel processing and cross processing, peeling wear and peeling are suppressed, and the bearing has a long life. Further, the use of the filtered fluorine-based lubricating oil has the effect of prolonging the service life.
Note that the present embodiment is an example of the present invention, and the present invention is not limited to the present embodiment. For example, in the present embodiment, the thrust ball bearing has been described as an example of the rolling bearing. However, the rolling bearing of the present invention can be applied to various other types of rolling bearings. For example, there are other types of thrust type rolling bearings such as thrust roller bearings, and radial type rolling bearings. Examples of radial rolling bearings include roller bearings such as cylindrical roller bearings, self-aligning roller bearings, and tapered roller bearings, and ball bearings such as deep groove ball bearings and angular ball bearings.

  Next, a sixth embodiment of the rolling bearing of the present invention will be described. As in the first embodiment, this embodiment is based on the premise that a rolling bearing lubricated with a fluorine-based lubricating oil and a reduced pressure including a vacuum, such as a vacuum pump device. In this embodiment, instead of the deep groove ball bearing or the angular ball bearing used in each of the above embodiments, a cage for holding the ball is formed in an annular shape from a high-performance resin material.

  FIG. 10 is a perspective view showing an embodiment of a cage employed in the rolling bearing of the present invention, and FIG. 11 is a side view of a main part showing a pocket having a weld line of the cage for the rolling bearing of FIG. FIG. 12 is a side view of a main part showing another pocket of the roller bearing retainer of FIG. FIG. 13 is a plan view for explaining a method of testing the tensile strength of the rolling bearing cage.

Referring to FIGS. 10 to 12, the rolling bearing cage 20 includes a high-performance resin material such as polyphenylene sulfide (PPS) resin and a reinforcing material such as glass fiber in a weight ratio of about 5 to 15%. The ring is formed without annealing treatment.
A plurality of (seven in FIG. 10) pockets 21 and 22 are provided in the rolling bearing retainer 20 at predetermined intervals in the circumferential direction, and are opened upward in FIG. 10. Each of the pockets 21 and 22 holds a rolling element 19 of a rolling bearing (not shown) from the opening 23 so as to be rollable.

Each pocket 21, 22 is provided with a pair of claws 24, and each rolling element 19 pushes the pawls 24 of each pocket 21, 22 in the circumferential direction so as to extend from the opening 23. It is incorporated in each of the pockets 21 and 22.
By the injection molding of the high-performance resin material, a weld line 26 is formed at a position where the molten resin injected from the gate 25 joins, and the opening dimension (dimension between claw portions) A of the pocket 21 having the weld line 26 (FIG. 11) ) Is set to a value larger than 93% of the rolling element diameter C (for example, 93 to 110%). The opening size B (FIG. 12) of each of the other pockets 22 is set to a value of 80 to 93% of the rolling element diameter C. Accordingly, the interference D (FIG. 11) of the claw portion 24 of the pocket 21 having the weld line 26 is smaller than the interference E (FIG. 12) of the claw portions 24 of the other pockets 22.

  Hereinafter, the operation of the present embodiment will be described. In the cage 20 for rolling bearings, the interference D by the claw portion 24 of the pocket 21 having the weld line 26 is smaller than the interference E by the claw portion 24 of each of the other pockets 22. When the rolling element 19 is incorporated, the force received when the claw portion 24 of the pocket 21 having the weld line 26 is expanded in the circumferential direction by the rolling element 19 is smaller than that of the claw portions 24 of the other pockets 22. Do it.

Therefore, in the pocket 21 having the weld line 26, the rolling element 19 is smoothly incorporated without exerting an excessive force on the claw portion 24, and a crack, a crack, or the like is generated in the weld line 26 portion (the bottom of the pocket 21). There is no. Further, in each of the other pockets 22, the ease of incorporating the rolling elements 19 into the respective pockets 22 and the difficulty of the rolling elements 19 incorporated into the respective pockets 22 falling off are both compatible.
If the opening size (dimension between claws) A of the pocket 21 having the weld line 26 is set to 100% or more, the interference D by the claws 24 is eliminated, so that the rolling element 10 can be incorporated more smoothly. It is.

Next, the tensile test was performed on the rolling bearing cage 20 of the present embodiment by changing the various conditions by the following method.
That is, referring to FIG. 13, a state in which the rolling bearing cage is positioned such that the gate 25 of the rolling bearing cage is on the right side in FIG. 13 and the weld line 26 is on the left side in FIG. Then, a pair of top members 27 are arranged in the inner diameter portion of the retainer. Each top member 27 is formed in a semicircular shape, and has a diameter slightly smaller than the inner diameter of the retainer. Then, each of the top members 27 was pulled in the opposite direction (vertical direction in FIG. 13) until the cage for rolling bearings was broken, and the load at the time of breaking was measured.
Table 12 shows the conditions and results. Here, the number refers to the number of retainers. In addition, all the fractures occurred from the weld line 26 portion. In Table 13, all values of the breaking load are average values.

As understood from Table 12, when the weight ratio of the reinforcing material such as glass fiber is set to 20%, the breaking load is smaller than that of 10%. Further, those subjected to the annealing treatment have a smaller breaking load than those not subjected to the annealing treatment.
Further, the rolling bearing retainer 20 of the present embodiment, in which various conditions were changed, was actually incorporated into a rolling bearing, and it was examined whether or not cracks occurred in the incorporated retainer.
Table 13 shows the conditions and results. Note that all cracks occurred from the weld line 26.

As can be understood from Table 13, when the content weight ratio of the reinforcing material such as glass fiber is set to 20%, a crack is generated in the pocket having the weld line 26 regardless of the presence or absence of the annealing treatment.
As described above, according to the present embodiment, the opening size A of the pocket 21 having the weld line 26 is set to a value larger than 93% of the rolling element diameter C (for example, 93 to 110%), and other values are set. The opening size B of each pocket 22 is set to a value of 80 to 93% of the rolling element diameter C. Accordingly, when the rolling element 19 is incorporated into each of the pockets 21 and 22, cracks, cracks, and the like are formed at the bottom of the pocket 21 having the weld line 26 while reliably preventing the rolling bearing retainer 20 from dropping from the rolling bearing. This can be reliably prevented from occurring.

  In addition, a high-functional resin material such as polyphenylene sulfide (PPS) resin contains a reinforcing material such as a darkening fiber at a weight ratio of about 5 to 15% and is not subjected to an annealing treatment. Therefore, it is possible to secure sufficient strength of the weld line 26 together with excellent corrosion resistance, and it is possible to more reliably prevent cracks, cracks, and the like from occurring at the bottom of the pocket 21 where the weld line 26 is located.

The cage 20 for a rolling bearing of the present embodiment can be applied to a rolling bearing having a rolling element, and is applied to, for example, a cylindrical roller bearing, a tapered roller bearing, a self-aligning roller bearing, and the like.
Next, a seventh embodiment of the rolling bearing of the present invention will be described. As in the first embodiment, this embodiment is based on the premise that a rolling bearing lubricated with a fluorine-based lubricating oil and a reduced pressure including a vacuum, such as a vacuum pump device. In this embodiment, a double-row angular contact ball bearing is used instead of the single-row deep groove ball bearing used in each of the above embodiments.

14 to 18, 1 is an outer ring, 3 is an inner ring, 5 is a rolling element (ball), 6 is a cage, 12 is a bearing case, 13 is a bearing cover, 14 is oil (fluorinated oil), and 15 is timing. Show gears. That is, although there is no limitation in the present invention, oil bath lubrication of a fluorine-based oil is employed in the present embodiment in order to maintain the degree of vacuum.
Further, in the present invention, the outer ring 1, the inner ring 3, and the rolling elements 5 are not particularly limited to the illustrated form, but can be arbitrarily changed to a well-known form. Either or both of the shapes are limited.

[Improvement of cage material]
The rolling bearing according to the present embodiment has a rolling element 5 between an outer ring 1 and an inner ring 3, and a retainer 6 for rotatably holding the rolling element 5 is made of a PTFE (polytetrafluoroethylene) resin material. Alternatively, a PPS (polyphenylene sulfide) resin material is used.
The retainer 6 is a well-known crown-type retainer in which pockets 8 that rotatably hold the rolling elements 5 are provided at a plurality of circumferential positions of an annular main portion 7 formed of a synthetic resin material. A well-known structure can be applied except that the material is limited as described above. In the present embodiment, the crown-shaped cage is shaped as described above, but a resin cage having another shape can also be used.
By limiting the material of the retainer 6 as in the present embodiment, the retainer 6 has self-lubricating properties and a small coefficient of friction as compared with a steel retainer, so that the retainer wear powder is less likely to be generated. Even if abrasion powder is generated, the lubricant is not degraded and no indentation is generated on the raceway surface, so that the bearing life can be extended.

[Improvement of cage shape]
The life of the bearing can be extended by forming the retainer 6 as follows. A hole 10 (through hole) having a desired size is formed in the bottom portion 9 of the pocket 8, and a lubricant is infiltrated through the hole 10 to improve the lubricating performance between the retainer 6 and the rolling element 5, thereby extending the life of the bearing. can do. The size (hole diameter) and shape of the hole 10 or the number of holes (one or more for one pocket) are not particularly limited, and the design can be arbitrarily changed within the scope of the present invention.

Further, chamfers 11 are provided on the inner and outer diameter sides of the cage pocket 8 to facilitate the infiltration of the lubricant, thereby improving the lubricating performance between the cage 6 and the rolling elements 5. Further, the inclination angle of the chamfer 11 is not particularly limited, and is arbitrarily selected within the scope of the present invention.
As described above, the shape of the retainer 6 is not limited to a known structure except that the through hole 10 and the chamfer 11 are provided.

[Improvement of cage material and shape]
Further, the material of the retainer 6 is a PTFE (polytetrafluoroethylene) resin material or a PPS (polyphenylene sulfide) resin material as described above, and the shape of the retainer 6 is formed in the pocket bottom portion 9 as described above. It is within the scope of the present invention to provide the chamfers 11 on the inner and outer diameter sides of the pocket 8 surface in addition to providing the chamfers 10.

Although not particularly limited in the present invention, when a ball is used for the rolling element 5, the following specifications can be included to further extend the bearing life.
Generally, the groove radius dimension of the inner and outer raceway surfaces 2 and 4 is 50.5 to 60% of the ball diameter, but in terms of PV value (P: contact surface pressure, V: sliding speed). It is desirable to employ 52 to 54% of the inner ring and 53 to 56% of the outer ring.

It is known that the smaller the groove radius is, the longer the bearing life is due to the contact surface pressure.However, if it is too small, the contact ellipse with the raceway surface becomes large and it is easy to slip, and the bearing life is shortened due to sliding wear. Sometimes. Therefore, even if the bearing life is shortened due to the large contact surface pressure, the bearing life is relatively extended by reducing the sliding speed.
Further, the use of a carbonitrided bearing material or a nitrided bearing material having a long life even under lubrication conditions with dust can extend the life of the bearing.

Although this embodiment describes only a double-row angular contact ball bearing used for a vacuum pump, the present invention is not limited to this, and is applicable to well-known rolling bearings in general such as a combination angular contact ball bearing. It is. Further, a rolling bearing used other than the vacuum pump may be used.
In this embodiment, the sixth embodiment, that is, the opening size of the pocket having the weld line is set to a value of 93% or more of the rolling element diameter, and the opening size of each of the other pockets is set as follows. When the rolling element is set to a value of 80 to 93% of the diameter of the rolling element, the fall of the cage for the rolling bearing from the rolling bearing can be reliably prevented, and the bottom of the pocket having a weld line can be formed when the rolling element is incorporated into each pocket. The effect of reliably preventing cracks, cracks, and the like from occurring is synergistic.

In addition, although each said embodiment demonstrated what respond | corresponds to each of this invention which does not depend on each other, it is possible to improve a bearing characteristic further by combining each invention, ie, each embodiment. It is quite obvious from the above description.
That is, the present invention
(1). Rolling bearings used under reduced pressure such as vacuum pumps.
(2). Rolling bearings that support heat rolls, etc. in the fixing section of office equipment. Is assumed. In (1), both are resistant to corrosion and evaporation, and in (2), because they are used in a high-temperature environment, they have low heat resistance, low evaporation, and are chemically stable. A system lubricant is used.

  However, fluorine-based lubricants have the advantage that they are less likely to evaporate and are more chemically stable than mineral oil-based lubricants, but they have high specific gravity and poor wettability, so they are insufficiently lubricated (oil film formation is not sufficient). Lubricating oil is difficult to reach in places where the clearance is narrow (for example, between the cage pocket and the rolling element). There was a problem that peeling damage such as peeling was apt to occur and the life was shortened. Moreover, it has been found that this peeling damage is apt to occur selectively on the rolling surface of the rolling element and the pocket portion of the cage (made of steel). For this reason, the present invention has the following embodiments in order to solve these problems, and has particularly come to provide a rolling bearing having a long life under the use environments (1) and (2).

1. Focusing on the condition that the surface roughness of the raceway surfaces of the inner ring and the outer ring is 0.05 μm Ra or less, and focusing on the fact that the rolling element wears a lot even if the surface roughness of the rolling element is too good, the roughness ratio between the two is set to 6 or less. , A long-life rolling bearing.
2. The rolling surface of the rolling element that is subject to selective peeling damage is covered with a dense oxide film, and hard and fine carbides are dispersed to prevent cohesive wear, and the high temperature in the local high temperature area (local contact) In order to prevent corrosion of fluorine gas due to decomposition of fluorine-based lubricant, a material having at least a passive film and 7 to 27% by weight of Cr, which is a carbide-forming element, is added to the rolling elements. That you did.

3. Similarly, by making the surface hardness of the rolling surface of the rolling element harder than the surface hardness of the raceway surface of the inner and outer races (including the one formed by the coating of Ni-P, Cr, TiN, etc.), the wear of the rolling element is reduced. As a long-life rolling bearing.
4. Similarly, the rolling element is provided with a nitride layer on the rolling surface, has a surface roughness of not more than 0.005 μm Ra, a hardness of not less than Hv900, or is composed of chemically stable oxide-based ceramics. Rolling bearings with long life.
5. Fluorine-based lubricants have higher specific gravity and poor wettability than mineral oil-based lubricants, so they are more susceptible to the presence of foreign matter such as abrasive grains, and remain due to barrel treatment, cloth treatment, or lubricant filtration. By suppressing the average diameter of foreign matter to 3 μm or less, the cause of peeling damage was eliminated, resulting in a long-life rolling bearing.

  6. In order to improve the corrosion resistance (due to the influence of fluorine-based lubricant) in the use of the support bearing of the vacuum pump, a cage that is easily damaged by peeling is made of a resin such as PPS, PEEK, or PBT. Injection molding is used as a manufacturing method of these, but since cracks are easily generated by a weld line, the opening of this portion is made wider than the opening of another pocket, and the opening of another pocket is made of a rolling element. Make it narrow to prevent falling off. By preventing cracks during forcible removal after injection molding of the cage and during assembly of the rolling bearings, the cost of rolling bearings for vacuum pumps is reduced, and the welds of the cages are prevented from being damaged. Long life, resulting in a long life rolling bearing.

  7. In a retainer using a fluorine-based lubricant, a material such as PTFE and PPS that can be used at high temperatures and is resistant to corrosion is used. Fluorine-based lubricants have poor wettability, and through holes should be provided at the bottom of the pockets or chamfers should be made on the inner and outer diameter surfaces of the pocket surface to improve the lubrication of the lubricant between the cage and the rolling elements. To prevent the peeling of the cage, resulting in a long-life rolling bearing.

  As described above, the non-dependent embodiments 1 to 7 of the present invention overlap with the column of the means for solving the above problems, but each of them is unique to the application in which a fluorine-based lubricant must be used. The present invention has been disclosed as a means for solving the above problem, and by combining these alone or in combination, the objects and effects of the present invention can be synergistically achieved, and in particular, to prevent peeling damage and provide a long-life rolling bearing. Becomes possible.

It is a longitudinal section showing one embodiment of the rolling bearing of the present invention. It is explanatory drawing which shows the relationship between the surface roughness of an inner / outer ring, and life. It is explanatory drawing which shows the relationship between the roughness ratio with respect to the rolling element of an inner / outer ring, and life. It is explanatory drawing which shows the relationship between the hardness of a coating film and the rolling element wear rate. It is explanatory drawing which shows the relationship between the hardness of a rolling element, and a wear amount ratio. It is explanatory drawing which shows the relationship between the surface roughness of a rolling element, and a wear amount ratio. It is a sectional view of a thrust ball bearing showing one embodiment of the rolling bearing of the present invention. FIG. 4 is an explanatory diagram showing the relationship between the maximum diameter of foreign matter and the life of a bearing when unfiltered fluorine-based lubricating oil is used. FIG. 4 is an explanatory diagram showing a relationship between the maximum diameter of foreign matter and the life of a bearing when filtered fluorine-based lubricating oil is used. It is a perspective view showing one embodiment of a cage adopted as a rolling bearing of the present invention. It is a principal part side view which shows the pocket with a weld line of the cage for rolling bearings of FIG. It is a principal part side view which shows the other pocket of the cage for rolling bearings of FIG. It is explanatory drawing of the test method of the tensile strength of the cage for rolling bearings. It is a longitudinal section showing one embodiment of the rolling bearing of the present invention. It is sectional drawing of the cage of the rolling bearing of FIG. FIG. 15 is a plan view showing a part of a cage of the rolling bearing of FIG. 14. It is sectional drawing which shows a part of cage. It is a schematic structure figure of a vacuum pump. It is a longitudinal section of the conventional combination angular contact ball bearing. FIG. 21 is a sectional view of a retainer of the angular contact ball bearing of FIG. 20. It is a longitudinal section of the conventional double row angular contact ball bearing. FIG. 22 is a sectional view of a retainer of the angular contact ball bearing of FIG. 21. It is a principal part side view which shows the pocket with a weld line of the conventional cage for rolling bearings.

Explanation of reference numerals

1 is an outer race 2 is a raceway 3 is an inner race 4 is a raceway 5 is a rolling element 6 is a cage 8 is a pocket 9 is a bottom part 10 is a through hole 11 is a chamfer 20 is a rolling bearing cage 21 has a weld line The pocket 22 is another pocket 23, the opening 24, the claw 25, the gate 26 is the weld line A is the opening dimension of the pocket with the weld line B is the opening dimension of the other pocket C is the rolling element diameter D is the welding line E is the interference by the claw of the other pocket. E is the interference by the claw of the other pocket. 101 is the thrust ball bearing 102. The outer ring 103 is the inner ring 104. The ball 106 is the fluorine-based lubricating oil 102a. The raceway surface 103a is the raceway surface.

Claims (3)

  An outer race having an outer raceway, an inner race having an inner raceway, and a rolling element rotatably disposed between the outer raceway and the inner raceway, wherein the rolling element is disposed between the outer raceway and the inner raceway. In a rolling bearing having a retainer for equally arranging the rolling elements in the revolving direction of the moving body and being used under lubrication by a lubricating oil or grease containing a fluorine-containing polymer or under an atmosphere containing a gas made of fluoride. The retainer is formed in a ring shape with a high-performance resin material, and a plurality of pockets for accommodating the rolling element from an opening and rotatably holding the rolling element are provided at predetermined intervals in a circumferential direction; The size of the opening of the pocket with the line is 93% or more of the diameter of the rolling element, and the size of the opening of at least two other pockets is 80% or more and 93% or less of the diameter of the rolling element. Features Rolling bearing.   An outer race having an outer raceway, an inner race having an inner raceway, and a rolling element rotatably disposed between the outer raceway and the inner raceway, wherein the rolling element is disposed between the outer raceway and the inner raceway. In a rolling bearing having a retainer for equally arranging the rolling elements in the revolving direction of the moving body and being used under lubrication by a lubricating oil or grease containing a fluorine-containing polymer or under an atmosphere containing a gas made of fluoride. The retainer is made of a PTFE resin material or a PPS resin material, or is formed by forming a chamfer on the inner and outer diameter sides of the pocket and providing a through hole at the bottom of the pocket. Or a rolling bearing characterized by both.   An outer ring having an outer raceway, an inner race having an inner raceway, and a rolling element rotatably disposed between the outer raceway and the inner raceway; In a rolling bearing having a retainer for equally arranging the rolling elements in the revolving direction of the moving body and being used under lubrication by a lubricating oil or grease containing a fluorine-containing polymer or under an atmosphere containing a gas made of fluoride. The retainer is formed in a ring shape with a high-performance resin material, and a plurality of pockets for accommodating the rolling element from an opening and rotatably holding the rolling element are provided at predetermined intervals in a circumferential direction; The opening size of the pocket with the line is 93% or more of the rolling element diameter, and the opening size of the other at least two or more pockets is 80% or more and 93% or less of the rolling element diameter, respectively. The retention Is made of a PTFE resin material or a PPS resin material, or is formed by forming a chamfer on the inner and outer diameter sides of the pocket and providing a through hole in the bottom of the pocket. A rolling bearing, characterized in that:

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