JP5060838B2 - Underwater rolling bearing - Google Patents

Description

  The present invention relates to a rolling bearing used in water.

Rolling used in food machinery, cleaning processes, etc. in water or water-based liquids or in an environment where the liquid is present on the raceway and oil is not allowed to enter the liquid As the bearing, a bearing lubricated with a solid lubricant is used. These bearings are required to have excellent load resistance and mechanical strength in addition to excellent wear resistance in order to reduce wear with other members in the liquid. It is also required to have excellent corrosion resistance against the liquid.
2. Description of the Related Art Conventionally, there has been known a bearing that provides a solid lubrication effect by using, for example, a resin whose main component is a fluororesin that can be melted and has solid lubricity in the resin itself (see Patent Document 1). In addition, a bearing is known in which the bearing ring and the rolling element are made of ceramics, the cage is made of graphite, and a solid lubrication effect is imparted by graphite (see Patent Document 2).

  However, since the solid lubricant has a circulation mechanism in which the solid lubricant is transferred to an object to which lubricity is imparted, discharged or consumed at the transfer destination, and further transferred in a form that supplements the solid lubricant, the bearing of Patent Document 1 is inevitably necessary. As a result, the bearing ring is worn out, and the rotational accuracy is inferior to that of the ordinary ring made of metal or ceramics. There is also a problem that load resistance is low.

In addition, graphite is very poor in strength and flexibility and inferior in impact resistance. In the embodiment of Patent Document 2, the cage is reinforced with metal, but the bearing is weak against shock load and vibration applied to the bearing. It has become.
JP 2000-240666 A JP 2001-271842 A

  The present invention has been made to cope with such problems, and in a rolling bearing used in a state where water or a liquid containing water as a main component exists on the raceway surface, the rolling made of ordinary metal or ceramics is used. The purpose is to provide a rolling bearing that has the same level of rotational accuracy as a bearing, is resistant to impact loads and vibrations, and has a long service life.

  An underwater rolling bearing according to the present invention includes an inner ring and an outer ring, a plurality of rolling elements interposed between the inner ring and the outer ring, and a holder that holds the plurality of rolling elements in sliding contact with each other. Is a submerged rolling bearing used in a state where the main component liquid is present on the raceway surface, and the cage is made of a resin composition in which at least a surface layer that is in sliding contact with the rolling element is blended with a carbon substance in a resin. It is characterized by being configured.

  The carbon material is at least one selected from carbon fiber, carbon powder, activated carbon, and graphite.

  The cage is characterized in that the entire cage is a molded body of the resin composition, and the blending ratio of the carbon substance is 10% by volume to 50% by volume with respect to the whole resin composition. .

  A surface layer of the cage is a film of the resin composition, and a blending ratio of the carbon substance is 10% by volume to 90% by volume with respect to the entire resin composition.

  At least one selected from an inner ring, an outer ring, and a rolling element of a rolling bearing incorporating the cage is made of ceramics.

  A ceramic coating is applied to at least one selected from the raceway surface of the inner ring, the raceway surface of the outer ring, and the rolling surface of the rolling element of the rolling bearing incorporating the cage.

  Since the underwater rolling bearing of the present invention uses a cage in which at least the surface layer that is in sliding contact with the rolling element is made of a resin composition in which a carbon material is blended with a resin, a carbon material having a solid lubricating effect is obtained from this cage. It is supplied to the raceway surface and the rolling element surface, and a transition film is formed on the raceway surface and the rolling element surface, resulting in a good lubrication state. For this reason, even if it is used under conditions where water or a liquid containing water as a main component is present on the raceway surface, the life is long.

  In addition, the bearing rings and rolling elements other than the cage have excellent wear resistance, and high-strength metals and ceramics can be used arbitrarily, so they are resistant to impact loads and vibrations, maintain dimensional stability, and have high rotational accuracy. It can be secured.

An example of the underwater rolling bearing according to the present invention is shown in FIG. FIG. 1 is a cross-sectional view of a deep groove ball bearing.
As shown in FIG. 1, in a rolling bearing 1, an inner ring 2 having an inner ring raceway surface 2a on an outer peripheral surface and an outer ring 3 having an outer ring raceway surface 3a on an inner peripheral surface are arranged concentrically, and the inner ring raceway surface 2a and the outer ring raceway are arranged. A plurality of rolling elements 4 are arranged between the surface 3a. The plurality of rolling elements 4 are held in sliding contact with the cage 5. Further, the opening portions in the axial direction are sealed by the seal member 6.

In order to improve the corrosion resistance of the rolling bearing 1 used in the presence of water or a liquid containing water as a main component, it is desirable that the bearing rings (inner ring 2 and outer ring 3) and the rolling element 4 are made of ceramics. Moreover, since the ceramic member is expensive, it can be manufactured at a relatively low cost by using stainless steel or bearing steel with a ceramic coating. Ceramic coating includes diamond-like carbon (hereinafter referred to as DLC), metal-containing DLC, chromium nitride (CrN), chromium nitride silicon (CrSiN), titanium nitride (TiN), titanium aluminum nitride (TiAlN), titanium silicon nitride ( Examples thereof include a hard film such as TiSiN) or a laminated film thereof.
In order to improve the corrosion resistance of the surface other than the surface to which a high surface pressure such as a rolling surface is applied, plating such as nickel plating or zinc plating, resin coating, or the like may be employed.

The cage 5 is composed of a resin composition in which at least a surface layer that is in sliding contact with the rolling element 4 is a resin mixed with a carbon substance. Specific examples include a case where the entire cage is a molded body of a resin composition containing a carbon material, or a case where the cage surface layer is a film coated with the resin composition.
When the cage surface layer is a coating of the resin composition, the cage body material may be a metal material such as a copper alloy, stainless steel (SUS), aluminum alloy, or titanium alloy that does not contain a resin. it can. A heat resistant resin material can also be used.

  In the case where the entire cage is formed into a molded body of a resin composition containing a carbon material, the means for kneading the resin and the carbon material is not particularly limited. For example, dry-mixing can be performed with a Henschel mixer, a ball mixer, a ribbon blender, or the like, and melt-kneading can be performed with a melt extruder such as a twin-screw extruder to obtain molding pellets. The carbon material may be charged by using side feed when melt kneading with a twin screw extruder or the like. As the molding method, extrusion molding, injection molding, heat compression molding, and the like can be adopted. However, injection molding is preferable because of excellent manufacturing efficiency and low cost.

The resin used for the cage of the underwater rolling bearing of the present invention is not particularly limited. A thermoplastic resin that can be injection-molded is preferable because the entire cage can be formed into a molded body of a resin composition in which a carbon substance is blended by injection molding and can be manufactured at low cost.
Thermoplastic resins include thermoplastic polyimide (TPI) resin, polyether ether ketone (PEEK) resin, polyphenylene sulfide (PPS) resin, polyamide 66 (PA66) resin, polyamide 46 (PA46) resin, and polyamide 6 (PA6) resin. , Polyamide 9T (PA9T) resin, polyamide 6T (PA6T) resin, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) resin, tetrafluoroethylene-hexafluoropropylene copolymer (FEP) resin, ethylene-tetrafluoro Examples include ethylene copolymer (ETFE) resin, polyvinylidene fluoride (PVDF) resin, polyacetal (POM) resin, polyethylene (PE) resin, polypropylene (PP) resin, and polystyrene (PS) resin. It is.

  The resin used in the cage is preferably a resin that is excellent in water resistance even when sliding in the presence of water or a liquid containing water as a main component, that is, hardly hydrolyzed. In addition to this water resistance, it is also excellent in the balance of chemical resistance, moldability, etc., so in the case of injection molding, among the above resins, PEEK resin, PFA resin, FEP resin, ETFE resin, PVDF resin, PE Resins are preferred.

In the case of a large cage that is difficult to be injection-molded, a coating film can be formed by coating a resin composition containing a carbon substance on the cage pocket surface that is in sliding contact with the rolling element, thereby exhibiting a solid lubricating effect. Examples of the resin used for forming the film include polyimide (PI) resins, epoxy resins, phenol resins, furan resins, unsaturated polyester resins, vinyl ester resins, and acrylic resins.
Since the cage is used under the condition that the sliding heat generation is large, a thermosetting resin is preferable, and in particular, a PI-based resin is more preferable in terms of wear resistance and long-term heat resistance.

  The PI-based resin that can be used in the present invention is a resin having at least an imide bond in the molecule, and can be used as long as it is excellent in binding property to the cage substrate. An aromatic PI resin or an aromatic polyamideimide (PAI) resin in which an imide bond or an amide bond is bonded via an aromatic group is particularly preferable. When the aromatic resin is used, the binding property to the cage substrate is excellent, and the heat resistance and water resistance of the obtained coating layer are excellent.

As a method for obtaining a resin composition for coating in the present invention, (1) a method of mixing a carbon substance in a resin varnish obtained by dissolving a resin in a resin solvent and stirring uniformly, (2) a resin powder, Examples thereof include a method of mixing a carbon substance in an organic solvent and stirring uniformly.
Various methods such as a dipping method, a roller coating method, a brush coating method, a spray coating method, and a printing coating method can be adopted as a method for coating the resin composition on the surface of the cage.

  Although it does not specifically limit as a carbon substance used for this invention, Carbon fiber, carbon powder, graphite, activated carbon, etc. are employable. Since carbon fiber improves the strength of the resin composite material, it is particularly preferable when both lubricity and high strength are required.

The carbon fibers that can be used in the present invention may be either pitch-based or PAN-based classified from raw materials. Moreover, in order to improve kneadability, dispersibility, etc. with the above resin, carbon fibers surface-treated with a treating agent containing an epoxy group or the like may be employed. When the carbon fibers are uniformly dispersed, the carbon fibers are efficiently supplied to the sliding surface.
The length of the carbon fiber is 50 to 500 μm, more preferably 50 to 200 μm. When the length of the carbon fiber exceeds 500 μm, the carbon fiber is likely to aggregate and the dispersibility is deteriorated, and it becomes difficult to efficiently supply the carbon fiber on the sliding surface.

Commercially available pitch-based carbon fibers include Kureha Chemical Co., Ltd .: Kureka M-101S, M-107S, M-101F, M-201S, M-207S, M-2007S, C-103S, Examples thereof include C-106S and C-203S.
Moreover, as a commercial item of PAN type | system | group carbon fiber, Toho Tenax Co., Ltd. product: Besfight HTA-CMF0160-OH, the same HTA-CMF0040-OH, the same HTA-C6, the same HTA-C6-S etc. can be illustrated.

  Examples of the carbon powder that can be used in the present invention include glassy carbon powder obtained by carbonizing a phenol resin or a furan resin. As a commercial item, Kanebo Co., Ltd. product: Bell pearl C-2000, Nippon Carbon Co., Ltd. product: Nika beads etc. can be illustrated. These are spherical phenol resin particles carbonized by heat treatment.

  The graphite that can be used in the present invention may be either a natural product or an artificial product, and generally available graphite can be used. Examples of commercially available products include LONZA: KS-6 or KS-10, Nippon Graphite: ACP.

  Examples of the activated carbon that can be used in the present invention include carbonization of raw materials such as coal, coconut shells, and large sawdust at 700 to 800 ° C., and further gas activation with steam and carbon dioxide at 900 to 1100 ° C. Examples include activated carbon produced by chemical activation by firing at 600 ° C. In addition, regenerated activated carbon by decompression regeneration, thermal desorption regeneration, chemical regeneration, solvent regeneration, substitution regeneration, and oxidative decomposition regeneration can also be used.

  The carbon material used in the present invention preferably has an average particle size of 1 to 100 μm in order to maintain good dispersibility. The shape and the degree of adsorption of the carbon material are not particularly limited.

The compounding amount of the carbon substance is preferably 10 to 50% by volume with respect to the entire resin composition when injection molding is performed. If the amount is less than 10% by volume, a great effect cannot be obtained, and if it exceeds 50% by volume, the melt viscosity becomes too high, and injection molding becomes difficult.
When performing resin coating, 10 to 90 volume% is preferable with respect to the whole resin composition. Unlike the injection molding, the coating has no limitation on the melt viscosity at the time of molding, so the blending amount can be increased to the limit. However, if it exceeds 90% by volume, the coating film tends to peel off, which is not preferable.
In addition, as long as the solid lubrication effect of the carbon material is not hindered, a reinforcing material other than the carbon material, a solid lubricant, a filler such as a pigment may be blended.

The present invention will be specifically described with reference to examples and comparative examples, but is not limited to these examples.
Examples 1 to 3, Reference Examples 1 to 2, and Comparative Examples 2 to 5
A bearing type test piece was obtained by incorporating a crown type resin cage, which was injection molded with the resin composition shown in Table 1, into a bearing (corresponding to 608, no seal) having a bearing ring and rolling elements made of SUS440C. The obtained bearing test piece was subjected to the underwater bearing test shown below, and the average bearing life was measured. The results are also shown in Table 1.

<Underwater bearing test>
In the underwater bearing test, after the bearing test piece 12 is attached to the shaft 8 of the underwater bearing tester 7 shown in FIG. 2, the bearing test piece 12 is submerged in the ion-exchanged water 14 so as to be below the water surface 10, and compressed. The maximum contact surface pressure of 1.7 GPa is applied to the bearing test piece 12 by the spring 13, and the torque applied to the bearing test piece 12 when the bearing test piece 12 is rotated at 500 rpm is transmitted through the leaf spring 11 to a strain gauge for torque measurement. 9 is a test method detected by No. 9, and the time required for the torque to rise abnormally in this test method was defined as the bearing life. Five bearing test specimens were prepared for each test condition, and the average value of the measured lifetime was used as the average bearing life.

Reference example 3
The same treatment and measurement as in Example 1 were performed except that a 30 μm thick coating having a resin composition with a volume ratio of PAI resin / graphite = 80/20 was formed on the entire surface of the PEEK resin cage. did. The results are also shown in Table 1.

Example 4
In Example 1, the same treatment and measurement as in Example 1 were carried out except that a silicon nitride rolling element was used instead of the SUS440C rolling element. The results are also shown in Table 1.

Example 5
The same treatment and measurement as in Example 1 except that a silicon nitride rolling element was used instead of the rolling element made of SUS440C in Example 1 and inner and outer rings having a DLC coating film formed on the raceway surface were used. Carried out. The results are also shown in Table 1.

Comparative Example 1
The same treatment and measurement as in Example 1 were carried out except that a SUS wave cage was used. The results are also shown in Table 1.

As shown in Table 1, the cage of Examples 1 to 5 showed excellent bearing life compared with Comparative Example 1 to Comparative Example 5.

  Since the underwater rolling bearing of the present invention uses a cage comprising a resin composition in which at least a carbon material is blended with a resin, a carbon material having a solid lubricating effect is supplied from this cage to the raceway surface and the rolling element. As a result, a transition film is formed on the raceway surface and the rolling elements, resulting in a good lubrication state and a long life. For this reason, it can utilize suitably for the rolling bearing used for food machinery etc. in the state where the liquid which has water or a main component of water exists in a raceway surface.

It is sectional drawing of a deep groove ball bearing. 1 is a schematic diagram showing an underwater bearing testing machine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rolling bearing 2 Inner ring 2a Inner ring raceway surface 3 Outer ring 4 Rolling body 3a Outer ring raceway surface 5 Cage 6 Seal member 7 Underwater bearing tester 8 Shaft 9 Strain gauge 10 Water surface 11 Leaf spring 12 Bearing test piece 13 Compression spring 14 Ion exchange water

Claims (3)

An inner ring and an outer ring; a plurality of rolling elements interposed between the inner ring and the outer ring; and a cage that holds the plurality of rolling elements in sliding contact with each other. An underwater rolling bearing used in an existing state,
The cage is composed of a resin composition in which at least a surface layer in sliding contact with the rolling element is blended with a carbon substance in a resin,
The carbon material is carbon fiber,
The resin is a polyether ether ketone resin, a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin, a tetrafluoroethylene-hexafluoropropylene copolymer resin, an ethylene-tetrafluoroethylene copolymer resin, a polyvinylidene fluoride resin, Or a polyacetal resin,
The retainer is an underwater product characterized in that the entire retainer is an injection-molded body of the resin composition, and the mixing ratio of the carbon substance is 10 to 50% by volume with respect to the entire resin composition. Rolling bearing for use.   The underwater rolling bearing according to claim 1, wherein at least one selected from an inner ring, an outer ring, and a rolling element of the rolling bearing incorporating the cage is made of ceramics. Inner ring raceway surface of a rolling bearing incorporating the cage, raceway surface of the outer ring, rolling, wherein at least one the ceramic coating selected from the rolling surface of the rolling elements are subjected claim 1, wherein Item 2. An underwater rolling bearing according to Item 2 .

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