JP2002188641A - Sliding member, retainer and rolling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sliding member, a retainer and a rolling device which provides easy and low-cost working, therein showing an excellent high lubricat ing state in particular under a high temperature and a high vacuum environment, and suppressing production of particles or the like. SOLUTION: The sliding member and the retainer contain as an essential component a resistant resin capable of melt molding and a soft metal or a soft alloy having a lower melting point than the heat resistant resin has. The rolling device is provided with the retainer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a sliding member, a cage and a rolling bearing. More specifically, PVD and C
The present invention relates to a film forming apparatus such as a VD, a sliding member, a retainer, and a rolling device that can be suitably used under a high temperature or a vacuum environment such as an X-ray tube.

[0002]

2. Description of the Related Art Generally, a rolling bearing includes an inner race having an inner raceway on an outer peripheral surface, an outer race having an outer raceway on an inner peripheral surface,
A plurality of rolling elements rotatably provided between the inner raceway and the outer raceway, and rotatably provided between the inner raceway and the outer raceway while guiding and holding the plurality of rolling bodies. And a retainer. In addition, lubrication of rolling bearings is performed by enclosing lubricating oil or grease inside the bearing or circulating lubricating oil or grease.

[0003] However, especially at high temperatures and in a vacuum environment, the lubricating oil and grease scatter to the outside of the bearing when the bearing rotates, or emit gas by evaporation, thereby contaminating the outside environment of the bearing. Therefore, lubricating oil and grease cannot be used when a clean environment is required, such as a semiconductor, liquid crystal panel, or hard disk manufacturing apparatus, or at high temperatures, in vacuum, in a special atmosphere, or at extremely low temperatures.

Therefore, conventionally, Japanese Patent Application Laid-Open No.
No. 7, Japanese Patent Application Laid-Open No. 61-55410, etc., molybdenum disulfide by sputtering, ion plating, or the like on part or all of the inner ring, outer ring, cage, and rolling elements in advance. There is known a method of forming and lubricating a thin lubricating film of graphite, silver, lead or the like.

A similar technique is disclosed in Japanese Patent Application Laid-Open No. 62-1515.
No. 39 and JP-A-64-79418 each use a cage made of a sintered alloy in which a solid lubricant such as molybdenum disulfide, graphite, hexagonal boron nitride and metal powder are mixed,
There is disclosed a method of lubricating a cage material with a thin film formed by transferring the cage material to a rolling element, an inner race, and an outer race by frictional contact between the cage and the rolling element. In addition, Japanese Patent Application Laid-Open No. 2-2455
No. 14, JP-A-4-102718, etc., use a cage made of a resin composition obtained by adding a solid lubricant or the like to plastic, and transfer the cage material to the rolling element, inner ring, and outer ring by frictional contact. There is disclosed a method of lubricating with a thin lubricating film formed as described above. Also, Japanese Patent Application Laid-Open No. 6-28088
No. 2, JP-A-7-103247, and the like, lubricate with a metal lubricant that melts at a predetermined temperature to be in a liquid phase state, and the bearing material is hardly corroded by the metal lubricant such as molybdenum or ceramics. Is disclosed.

[0006]

The demand for higher performance and higher yield of products has led to higher temperatures and higher vacuum in the process. It is required to operate stably for a long time under severe environment such as vacuum and to have few particles scattered outside from the bearing (hereinafter sometimes referred to as low dust generation). Demands are increasing year by year.

However, in the lubrication method using a thin lubricating film formed in advance as described in JP-A-55-57717 and JP-A-61-55410, the contact surface is not affected by the operation of the bearing. If the lubricating film is worn away by the frictional force and disappears, the lubricating effect is lost and adhesion and seizure of the underlying metal (base material) occur, so that the life is generally short.

When a cage is made of a sintered metal as described in JP-A-62-151539 and JP-A-64-79418, a complicated shape may be used. Since it is impossible, it is necessary to form a desired retainer shape by machining from a rod material or a ring material, which is very expensive. In addition, sintered metal generally has excellent heat resistance, but the material has low mechanical strength and is brittle, so it is easy for cracks to occur on the surface during machining. It is necessary to slow down, and the machinability is poor, and furthermore, when the bearing is operated, cracks develop from the cracks and the like introduced at the time of the machining, abnormal wear of the cage, chipping or breakage occurs, A large amount of particles may scatter outside or the bearing may not be able to rotate.

In the case of a cage composed of a resin composition as described in JP-A-2-245514, JP-A-4-102718, etc., the resin material itself serving as a base material is Insufficient lubricity, the lubrication effect is lost soon after the bearing is operated, the generation of abrasion particles increases rapidly and a large amount of particles scatter from the bearing to the outside, and the torque of the bearing increases to shorten the life. May be reached. Polytetrafluoroethylene resin (hereinafter referred to as P
By using TFE) or using a resin having excellent heat resistance such as polyimide or polybenzimidazole, the above-mentioned inconvenience is slightly improved, but since these resins cannot be melt-molded, As in the case of the above-described sintered metal, it is necessary to form a desired shape by machining a bar or the like, which is very expensive.

In the methods described in JP-A-6-280882 and JP-A-103247, a metal lubricant in a liquid phase is filled in a bearing internal space. In operation of the above, there is a problem that not only the metal lubricant leaks or scatters to the outside of the bearing and contaminates the outer space of the bearing, but also the mechanical structural parts around the bearing are corroded by the metal lubricant.

As described above, the conventional solid lubricated rolling bearing is difficult to lubricate for a long time, especially in a high temperature and high vacuum environment, a large amount of particles are scattered outside from the bearing, Depending on the material, there is a problem that machining is required and it becomes very expensive, and there is a case where the cage is broken when the bearing is operated.

Accordingly, an object of the present invention is to provide a sliding member, a cage, and a rolling bearing which are easy to process and inexpensive, have high lubricating performance especially in a high temperature and high vacuum environment, and generate few particles and the like. To provide.

[0013]

In order to achieve the above object, the present invention comprises a heat-resistant resin capable of being melt-molded and a soft metal or a soft alloy having a lower melting point than the heat-resistant resin. The present invention provides a sliding member characterized by containing

Further, the present invention provides a retainer comprising a heat-resistant resin capable of being melt-molded and a soft metal or a soft alloy having a lower melting point than the heat-resistant resin as essential components. A rolling device including a retainer is provided.

[0015]

In the sliding member and the retainer, a heat-resistant resin (hereinafter simply referred to as a heat-resistant resin) capable of being melt-molded and a soft metal or a soft alloy having a lower melting point than the heat-resistant resin are used as main components. Therefore, injection molding, which is a typical melt molding method, can be performed, and mass productivity is excellent. In addition, the heat-resistant resin, which is the main component, suppresses the generation of wear particles even when the bearing is operated in a high-temperature environment, because the material is less likely to deteriorate due to heat and retains wear resistance and lubricity. Also, the number of particles scattered outside is small. Therefore, the rolling bearing incorporating the cage of the present invention or the device incorporating the sliding member ensures stable lubrication for a long period of time even when used under high temperature and high vacuum, and reduces generation of particles and the like. .

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The sliding member and the cage contain a heat-resistant resin and a soft metal or a soft alloy having a lower melting point than the heat-resistant resin as essential components.

Examples of the heat-resistant resin include a fluorine-containing resin, thermoplastic polyimide (hereinafter abbreviated as TPI), polyether nitrile (hereinafter abbreviated as PEN), and a copolymer of polyether ketone and polybenzimidazole (hereinafter abbreviated as PEN). PEEK-PBI) or the like, and these may be used alone or in combination of two or more. Particularly preferred are fluorine-containing resins, for example, tetrafluoroethylene / perfluoroalkylvinyl ether copolymer (hereinafter abbreviated as PFA), tetrafluoroethylene / hexafluoropropylene copolymer (hereinafter F
EP), polychlorotrifluoroethylene (hereinafter abbreviated as PCTFE), tetrafluoroethylene / ethylene copolymer (hereinafter abbreviated as ETFE), chlorotrifluoroethylene / ethylene copolymer (hereinafter abbreviated as ECTFE)
Abbreviation), polyvinylidene fluoride (hereinafter, PVD)
F) and these may be used alone or in combination of two or more. Among them, PFA, FE
P, PVdF, and ETFE are preferable because of their excellent self-lubricating properties and heat resistance. PFA is preferable when used in a severe environment such as a higher temperature and a higher speed.

The soft metal is not particularly limited as long as it has a lower melting point than the heat-resistant resin.
Gallium (Ga: melting point 29.78 ° C.), indium (In: melting point 156.
2 ° C.), tin (Sn: melting point 231.9 ° C.), lead (Pb: melting point 327 ° C.), bismuth (Bi: melting point 271.3 ° C.) and the like are preferable. Further, these alloys may be used.

The mixing ratio of these soft metals (alloys) in the entire composition is preferably from 1% by weight to 45% by weight. 1
If it is less than% by weight, the amount of addition may not be sufficient, so that improvement in lubricity may not be observed. On the other hand, if the content exceeds 45% by weight, further improvement in lubricity cannot be expected, but also mechanical strength and formability are remarkably reduced, and sliding members and cages as molded products are abnormally worn. May be shortened or broken, resulting in a very short life.

By blending a fibrous filler in addition to the above-mentioned heat-resistant resin and soft metal (alloy), the mechanical strength of the sliding member and the cage can be increased. Usable fibrous fillers include, but are not particularly limited to, aluminum borate whiskers, potassium titanate whiskers, aramid fibers, aromatic polyimide fibers, liquid crystal polyester fibers, calcium carbonate whiskers, graphite whiskers, magnesium oxysulfate whiskers, and glass. Fiber, carbon fiber, metal fiber, silicon carbide fiber, alumina fiber, boron fiber, silicon carbide whisker, silicon nitride whisker, alumina whisker, aluminum nitride whisker, wollastonite, zinc oxide whisker, magnesium oxide whisker, mullite whisker, etc. it can.

The form of these fibrous fillers preferably has an aspect ratio of 3 to 200. If the aspect ratio is less than 3, the reinforcing effect is not sufficiently exhibited, and the sliding member and the retainer become fragile. On the other hand, if the aspect ratio exceeds 200, mixing with a heat-resistant resin or a soft metal (alloy) may occur. Uniform dispersion becomes extremely difficult, and in addition to a decrease in the moldability, there are cases where the mechanical strength is reduced due to uneven distribution in the sliding member or the retainer. Further, the fiber diameter is not particularly limited, but the average fiber diameter is preferably 0.2 μm to 30 μm, more preferably 0.3 μm to 5 μm. If the average fiber diameter is smaller than 0.2 μm, the fibers may aggregate when mixed with a heat-resistant resin or the like, and the dispersion of the fibers may be uneven. With a diameter, not only may the smoothness of the surface be impaired, but also the sliding surface may be damaged, or the lubricating film transferred to the mating material may be damaged. It enters between the contact surfaces and is crushed into a large number of fine wear particles, which are scattered to the outside. 0.3μ average fiber diameter
If m to 5 µm, such a tendency does not exist at all, and a favorable result can be obtained.

The proportion of the fibrous filler in the whole composition is not particularly limited, but is preferably 30% by weight or less. Even if the content exceeds 30% by weight, further improvement in mechanical strength cannot be expected, but also the melt fluidity is remarkably reduced, moldability is deteriorated, and the amount of lubricating components contained in the cage material is reduced. Due to the decrease, sufficient lubricity may not be obtained. Further, it is preferable that the total amount of the composition and the soft metal (alloy) is 10% by weight to 60% by weight of the total composition. If the total amount exceeds 65% by weight, the moldability is significantly reduced. Further, in order to impart an affinity between the heat-resistant resin and the fibrous filler, and to improve the adhesion between them and the dispersibility of the fibrous filler, a cup such as a silane coupling agent or a titanate coupling agent is used. It can be treated with a ring agent or other surface treatment agents suitable for the purpose, but is not limited thereto.

Further, various additives may be blended within a range that does not impair the object of the present invention. For example, foaming agents, antioxidants, heat stabilizers, ultraviolet absorbers, light protectants, flame retardants, antistatic agents, flow improvers, non-tackifiers, crystallization accelerators, nucleating agents, pigments, Dyes and the like can be exemplified. These may be any of known ones.

The above-mentioned heat-resistant resin, soft metal (alloy),
Furthermore, the method of mixing various additives such as a fibrous filler is not particularly limited. For example, each can be melt-kneaded separately, or these materials can be preliminarily mixed by a mixer such as a Henschel mixer, a tumbler, a ribbon mixer, a ball mill, etc., and then supplied to the melt mixer. As the melt mixer, a known melt kneader such as a single-screw or twin-screw extruder, a kneading roll, a pressure kneader, a Banbury mixer, and a Brabender plastograph can be used.
The temperature at the time of melt-kneading is not particularly limited, but may be appropriately selected within a temperature range in which the heat-resistant resin capable of being melt-molded sufficiently proceeds and does not decompose.

Then, the above-mentioned melt-kneaded material is formed into a predetermined shape by a usual method such as injection molding, compression molding, transfer molding or the like, whereby the sliding member and the retainer of the present invention can be obtained. Among them, the injection molding method is preferable because the productivity is excellent and the production cost can be reduced.

The sliding member includes, for example, a mechanical seal, a slide bearing, a roller, a seal for a linear motion guide device, a nut for a slide screw, a slider for a slide linear motion guide, and the like. By forming them, these sliding members can be provided with excellent lubrication performance and low dust generation.

The present invention also provides a rolling bearing incorporating the above cage. The rolling bearing of the present invention, in order to provide the cage with high lubrication performance and low dust generation described above,
Even when used under high temperature and high vacuum, stable lubrication over a long period of time is ensured, and the generation of particles and the like is reduced.

In the rolling bearing of the present invention, it is preferable that a coating containing a solid lubricant is further applied to the surface of the raceway groove of the bearing and part or all of the rolling elements. This prevents direct contact between the cage, the rolling elements, the inner ring and the outer ring at the initial stage of operation before the solid lubricant film is transferred from the cage to the rolling elements, the raceway grooves of the inner and outer rings, and reduces the surface roughness. The increase can be suppressed, the bearing is in a good lubrication state from the beginning of operation, and a low bearing torque can be obtained, and the solid lubricating film can be transferred well from the cage to the raceway grooves of the rolling elements, inner ring and outer ring. Therefore, wear of the solid lubricant and the like, and falling off from the contact surface at the time of transfer are suppressed, the number of particles scattered outside from the bearing is reduced, and lubricity can be maintained for a longer period of time. Become like

The solid lubricating film is not particularly limited, but may be any of gold, silver, lead, indium, tin, graphite, fluorinated graphite, hexagonal boron nitride, fluoromica, PTFE, molybdenum disulfide, tungsten disulfide and the like. What is necessary is just to contain at least one kind chosen. The method for producing the solid lubricating film is not particularly limited, and for example, known film forming techniques such as firing, thermal spraying, sputtering, ion plating, vacuum evaporation, electrolytic plating, and electroless plating can be used. The thickness of the solid lubricating film is not particularly limited, but is preferably from 0.03 μm to 5 μm, more preferably from 0.05 μm to 3 μm. Thickness 0.03μm
If it is thinner, the solid lubricating film will wear and disappear before the cage material is transferred to the surfaces of the rolling elements, inner ring and outer ring to form a lubricating film, and the rolling elements, inner ring and outer ring will come into direct contact with each other. As a result, the torque of the bearing may rise sharply and seize. On the other hand, when the film thickness is more than 5 μm, the solid lubricating film is easily peeled off from the rolling elements, the inner ring and the outer ring due to residual stress generated inside the film at the time of film formation, and not only a lubricating effect is not obtained, but also the solid which has been separated The lubricating coating may enter the contact surface between the rolling element and the inner ring or the outer ring and be crushed into a number of fine particles, which may significantly increase the number of particles scattered outside the bearing. In addition, if the thickness of the solid lubricating coating is greater than 5 μm, the solid lubricating coating itself will support the load, causing permanent deformation on the coating surface, causing the bearing operation to become less smooth, When the rigidity of the surface decreases, the rigidity of the bearing itself may decrease.

The materials of the inner ring, outer ring and rolling elements of the rolling bearing of the present invention are not particularly limited. For example, metal materials such as bearing steel and stainless steel and silicon nitride (Si
₃ N _4), silicon carbide (SiC), sialon (SiAlON), zirconia (ZrO ₂₎ and alumina (Al ₂ O ₃₎ can be exemplified ceramic materials represented, using them alone or in combination be able to.

[0032]

The present invention will be further described below with reference to examples. However, the present invention is not limited to these.

(Examples 1 to 4, Comparative Examples 1 and 2) The raw materials of the cage used in the examples and the comparative examples are collectively shown as follows.
It is as follows. PFA (manufactured by Daikin Industries, Ltd .: NEOFLON PFA AP-201) TPI (manufactured by Mitsui Toatsu Chemicals, Inc .: Aurum) PEEK-PBI (manufactured by Hoechst-Celanese: Cerazole TU-60) Indium powder (manufactured by Wako Pure Chemical Industries) titanic acid Potassium whisker (Otsuka Chemical Co., Ltd .: Tismo D-101, diameter 0.3-0.6 μm, length 10-20 μm)

The retainer was dry-mixed with a Henschel mixer, except for potassium titanate whiskers, and then potassium titanate whiskers were added using a twin-screw extruder through a quantitative side feeder, extruded and granulated. did. The obtained pellets are supplied to an injection molding machine and molded,
The retainer was shaped (a retainer for model number 608). The cage was a crown type cage. In addition, as a test bearing,
Using 608 equivalent ball bearings (inner diameter 8mm, outer diameter 22mm, width 7mm)
The inner ring, outer ring and rolling elements were all made of SUS440C.
Note that Comparative Example 2 was made of SUS440C. Further, only in Example 4, a tin film was formed to a thickness of 0.1 μm on the surfaces of the inner and outer raceway grooves by vacuum evaporation. Table 1 also shows the mixing ratio (% by weight) of the cage material in each of the examples and comparative examples, and the presence or absence of a tin film in Table 1.

[0035]

[Table 1]

Each of the test bearings of the above Examples and Comparative Examples was subjected to a rotation test using a bearing rotation tester manufactured by Nippon Seiko under the following conditions to evaluate torque stability and torque life.・ Ambient pressure: 1 × 10 ^-4 Pa ・ Ambient temperature: 200 ℃ ・ Axial load: 19.6N ・ Radical load: 1.96N ・ Rotational speed: 5000rpm

The torque is measured using a strain gauge, and a value at the beginning of rotation (initial value) and a value at a time when the torque after 10 minutes of rotation is almost stable (steady value) are obtained. The torque stability was evaluated from the ratio divided by the value. Regarding the torque life, the test was stopped when the torque value became three times or more of the steady value, and the total number of revolutions up to that time was defined as the torque life.

Further, in order to evaluate the amount of dust generated from the bearing, the number of particles scattered outside from the test bearing was measured by laser light scattering using a vacuum bearing dust tester manufactured by Nippon Seiko under the following conditions. It was measured by a formula particle counter. The test conditions are as follows.・ Ambient pressure: 1 × 10 ^-4 Pa ・ Ambient temperature: 200 ℃ ・ Axial load: 19.6N ・ Rotational speed: 1000rpm

The above test results are also shown in Table 1. still,
In Table 1, the torque life is represented by a relative value with the value of Comparative Example 1 being 1, and the amount of dust generation is represented by a relative value with the value of Comparative Example 1 being 100. As shown in Table 1, in the test bearing of each example, even in a high-temperature environment of an atmospheric temperature of 200 ° C., the torque increase was small and stable compared to the comparative example,
It can be seen that a very long torque life is exhibited and the number of dust particles scattered outside from the bearing is very small.

(Verification of Mixing Ratio of Soft Metal) A heat-resistant resin (PFA, TPI, PEEK-PBI), indium powder, and potassium titanate whisker were used by using a melt-kneaded product in which the mixing ratio of indium powder was changed. To form a crown cage, and the torque life and dust generation were measured under the same conditions as above. still,
The mixing ratio of potassium titanate whiskers was constant at 20% by weight.

FIG. 1 shows the results. In the figure, “○” indicates the torque life when the heat-resistant resin is TPI, “□” indicates the torque life when the heat-resistant resin is PFA, and “△” indicates the heat-resistant resin is PEEK-PBI. And the respective values are shown as relative values with the value of Comparative Example 1 set to 1.
In the figure, “●” indicates the amount of dust when the heat-resistant resin is TPI, and “■” indicates the amount of dust when the heat-resistant resin is PFA.
"◆" indicates the amount of dust generated when the heat-resistant resin was PEEK-PBI, and each value is shown as a relative value with the value of Comparative Example 1 being 100. As is clear from the figure, the addition of indium powder tends to prolong the torque life and reduce the amount of dust generation. In particular, excellent results have been obtained by adding 5 to 45% by weight of indium powder.

[0042]

As described above, a cage or a sliding member containing a heat-resistant resin and a soft metal or a soft alloy having a melting point lower than that of the heat-resistant resin as essential components is inexpensive and can be used in a high-temperature environment. , A good lubricating state can be maintained over a long period of time, and the number of particles scattered outside is small. For this reason, it is very unlikely that the external environment is polluted even under a high temperature environment. Therefore, a rolling device incorporating the retainer or various devices incorporating a sliding member can operate stably for a long period of time even under high temperature and high vacuum, and does not pollute the external environment. Used in harsh environments where lubricating oil or grease cannot be used, such as high temperature, vacuum, special atmosphere, cryogenic temperature, etc. be able to.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the torque life and the amount of dust generated when the mixing ratio of indium metal powder is changed.

Claims (3)

[Claims] 1. A sliding member comprising, as essential components, a heat-resistant resin capable of being melt-molded and a soft metal or a soft alloy having a lower melting point than the heat-resistant resin. 2. A cage comprising, as essential components, a heat-resistant resin capable of being melt-molded and a soft metal or a soft alloy having a lower melting point than the heat-resistant resin. 3. A rolling device comprising the retainer according to claim 2.