JPH0942296A - Corrosion resistant rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost corrosion resistant rolling bearing to prevent occurrence of initial wear due to defective lubrication even in corrosive atmosphere wherein no grease is usable, have high precision and high strength, and manufacture even a member in a complicated shape through injection molding. SOLUTION: A corrosion resistant rolling bearing comprises a track ring and a rolling body 3 consisting of inner and outer rings 1 and 2 made of ceramics; a holder 4 moldable through injection molding and formed of fluorine resin; and at least one solid lubricant feed member 5 arranged between the track rings and rolling on a track surface. The solid lubricant feed member 5 is started to roll simultaneously with starting of bearing operation, a solid lubrication film formed by transition of a solid lubricant to a contact surface between a rolling body 3 and track surfaces of the inner and outer rings 1 and 2 is formed to perform smooth lubrication operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corrosion resistant rolling bearing which can be suitably used in a corrosive atmosphere of water, acid, alkali or the like.

[0002]

2. Description of the Related Art As prior arts relating to this type of rolling bearing, for example, those disclosed in Japanese Patent Application Laid-Open No. 2-190614 and (first conventional example) and those disclosed in Japanese Patent Application Laid-Open No. 4-331819 ( Second conventional example), actual Kaihei 4-82
There is one disclosed in Japanese Patent No. 431 (third conventional example) and the like.

The rolling bearing of the first conventional example is a bearing ring made of stainless steel, a rolling element made of carbon, and a diameter of 2 μm.
The cage is made of a fluororesin containing the following short fibers and is formed only by molding to prevent fuzzing. At the initial stage of operation, carbon of the rolling elements performs a lubricating action, and as the rotation advances, the fluorine-based resin of the cage is displaced to the rolling elements and the races to perform the lubricating action. Further, the cage is reinforced by the short fibers to enhance the durability, and since there is no fluffing, early wear of the rolling elements is prevented.

The second conventional example relates to a cage for rolling bearings,
5-40% by weight of heat resistant fibers such as glass fiber, carbon fiber, graphite fiber, and perfluoroalkoxy (PF)
A) Molded from a composition in which 30 to 90% by weight of a resin is mixed with 5 to 30% by weight of one or more powder fillers selected from molybdenum powder, molybdenum disulfide powder and calcium compound powder. By combining a PFA resin and a heat resistant fiber, it is intended to obtain a rolling bearing cage that can withstand use in a harsh atmosphere such as high vacuum or extremely low temperature.

The corrosion-resistant rolling bearing of the third conventional example has an outer ring,
The inner ring and rolling elements are made of ceramics, and the cage is made of a polytetrafluoroethylene (PTFE) -based self-lubricating composite material. A rolling bearing that can withstand use in water and in corrosive gas atmospheres. It's about to get.

[0006]

However, the first conventional example is unsuitable as a rolling bearing used in a seawater atmosphere because the bearing ring is made of a stainless steel metal which is corroded by salt. . From the viewpoint of lubricity, even if the bearing operating time elapses to some extent, the self-lubricating function of the cage based fluorine resin begins to work,
In the initial stage of operation, the lubrication action between the rolling elements and the races is performed only by the carbon forming the rolling elements, so the initial wear of the rolling elements due to poor lubrication cannot be avoided.

On the other hand, in the case of the second conventional example, the PFA resin 3 which originally has insufficient mechanical strength in the composition of the cage.
Since it contains 0 to 90% by weight, there is a problem in that respect. That is, the cage has a function of holding the rolling elements at a predetermined interval, and it is required to have sufficient strength to withstand the stress received from various directions and should not be damaged. It was found that the breaking load was low in the destructive test.

In the third conventional example, the bearing ring and rolling elements are made of ceramics, and the cage is made of PTFE, which is a fluorine-containing resin excellent in sliding characteristics and chemical resistance, to ensure excellent corrosion resistance. I am doing it. However, the melting point of PTFE used as the material of the cage is as high as 327 ° C,
Since it has a high melt viscosity, there is a problem in moldability due to melt molding. For example, a crown type cage with a complicated shape and a cylindrical roller bearing cage with a relatively thin column part are manufactured by highly productive injection molding. Difficult to do. Therefore, when a cage having a complicated shape is required, it is very difficult to manufacture the PTFE material, for example, by a grinding process or the like, and the manufacturing itself is extremely difficult and extremely costly. .

Further, in many cases, a lubricant such as grease cannot be used at all in a corrosive atmosphere.
Also in the case of the conventional rolling bearing, there is an unsolved problem that wear is inevitable in the early stage of operation due to poor lubrication, as pointed out in the first conventional example.
Therefore, the present invention has been made by paying attention to the above-mentioned unsolved problems of the related art, and the purpose thereof is to prevent poor lubrication even in a corrosive atmosphere such as water, acid or alkali where grease cannot be used. An object of the present invention is to provide a low-cost corrosion-resistant rolling bearing which can be used favorably while avoiding initial wear, and which can be manufactured with high precision and high strength even in a member having a complicated shape by injection molding.

[0010]

SUMMARY OF THE INVENTION The present invention, which solves the above-mentioned unsolved problems, relates to a corrosion-resistant rolling bearing, which comprises a raceway ring and a rolling element made of a ceramic inner ring and an outer ring, and a fluorine-containing moldable by injection molding. It is characterized by comprising a cage made of resin and at least one solid lubricant supply member which is arranged between the raceways and rolls on the raceway surface.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a cross section of an embodiment of a corrosion-resistant rolling bearing of the present invention. First, the structure will be described. A race ring composed of an inner race 1 and an outer race 2, a plurality of rolling elements 3 arranged between the races, a cage 4 for holding the rolling elements at a predetermined interval, and further Has at least one solid lubricant supply member 5 arranged between the races so as to be sandwiched between the rolling elements 3.

The inner ring 1, the outer ring 2, and the rolling elements 3 (the balls are shown in the figure, and may be rollers) are all made of ceramics. As ceramics, silicon nitride (Si
₃ N ₄ ), alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), silicon carbide (SiC), etc. are used, and it is suitable depending on the type of atmosphere such as chemical liquid or gas used for the corrosion resistant rolling bearing. Appropriately select what can be used.

The cage 4 is made of a fluorine-containing resin that can be molded by injection molding. The fluorine-containing resin is used because the material originally has excellent sliding characteristics and chemical resistance. Therefore, what is used for the cage of the present invention is preferably a fluorine-containing resin which has a low melt viscosity and can be injection-molded and which has excellent mechanical strength. As a result, high-precision, high-strength cages with complicated shapes can be mass-produced at low cost. In this respect, PTFE, which is widely used as a fluorine-containing resin, cannot be said to have sufficient moldability so that a crown-type cage can be molded, and is excluded from the cage molding material of the present invention.

Mechanical strength is one of the important factors for the performance required of the cage. Therefore, the present inventors
In order to identify a fluororesin that can guarantee practically sufficient strength, various types of fluororesins were used to manufacture the crown cage (used for the ball bearing 6206) shown in FIG. The test was conducted as follows. A crown-shaped cage obtained by molding using a mold having a gate provided at one place has a semicircular shape having a slight clearance α with respect to the inner diameter of the cage 4, as shown in FIG. Two jigs 10A, 1 above and below
Wear 0B. 10m for those jigs 10A and 10B
The load at the time of breakage was measured by moving in the vertical direction at a speed of m / min. The results are shown in Table 1.

[0015]

[Table 1]

From the results shown in Table 1, tetrafluoroethylene-hexafluoropropylene copolymer (FEP) and tetrafluoroethylene-ethylene are preferable as the fluororesin suitable for maintaining the strength required for the cage of the present invention. Copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), chlorotrifluoroethylene-ethylene copolymer (ECTFE), polyvinylidene chloride (PVdF) and the like can be used.

The cage made of fluorine-containing resin contains glass fiber, potassium titanate whiskers,
Aluminum borate whiskers, silicon carbide whiskers, carbon fibers, etc. with excellent corrosion resistance can be used. The combination of the fibrous reinforcing material and the fluorine-containing resin is appropriately determined depending on the type of chemical atmosphere used. The compounding ratio of the combination is 40 to 5% by weight of the fibrous reinforcing material with respect to 60 to 90% by weight of the fluorine containing resin, and preferably 70% of the fluorine containing resin.
Fluorine-containing resin is 30 to 10% by weight with respect to 90% by weight. If the amount of the fibrous reinforcing material is less than 5% by weight, the mechanical strength required for the cage cannot be obtained. On the other hand, if the fibrous reinforcing material exceeds 40% by weight, the fluidity becomes poor at the time of molding, the moldability is deteriorated, and a highly accurate cage cannot be obtained.

The solid lubricant supply member 5, which is a component of the corrosion-resistant rolling bearing of the present invention, has the same shape (ball or roller) as the rolling element 3, and its diameter is slightly smaller than the diameter of the rolling element 3. Good. This is because if the rolling elements have the same dimensions, they are likely to be damaged by the load. It is used by being incorporated in the cage 4 in place of any of the plurality of rolling elements between the bearing rings. The material of this solid lubricant supply member is graphite, fluorocarbon, PTFE, PFA, MoS ₂ ,
WS ₂ and mixtures thereof are preferred. Or
A core material coated with such a solid lubricant substance (for example, MoS ₂ is sputtered on the surface of a stainless ball) may be used.

Next, the operation will be described. The corrosion-resistant rolling bearing of the present invention comprises a ceramic inner ring 1, an outer ring 2, and a rolling element 3 having high corrosion resistance, a cage 4 made of a fluororesin which also has high corrosion resistance, and a solid having high corrosion resistance and self-lubricating property. Since it is composed of the lubricant supply member 5, it can be suitably used even in a corrosive atmosphere such as water, seawater, acid or alkali. Further, even when the lubricant such as grease flows out or deteriorates and cannot be used, the self-lubrication function of the solid lubricant supply member 5 ensures smooth lubrication from the initial operation of the bearing.
Wear damage to the raceways of the inner ring 1 and the outer ring 2 and the rolling elements 3 is prevented.

That is, when the rolling bearing starts to operate without grease and without lubrication, at the same time, the solid lubricant supply member 5 comes into contact with the raceway surfaces of the rolling element 3 and the inner ring 1 and the outer ring 2 to start rotating. The solid lubricant separated from the solid lubricant supply member 5 is supplied to the contact surface of the member to form a lubricating coating. Therefore, between the rolling elements and the races, the lubricating action of the formed film of the solid lubricant is carried out from the initial stage of operation, so that the solid lubricant operates smoothly and wear is prevented. Then, as the rotation continues, the fluororesin of the cage is scraped off little by little by contact with the rolling elements 3 to form a fluororesin coating on the surface of the rolling elements. It is transferred to the raceway surface of the outer ring 2, and the fluorine-containing resin coating is also formed there. Therefore, after a certain amount of operation time has elapsed, the lubricating action of the solid lubricant from the solid lubricant supply member 5 is further added to the lubricating action of the fluorine-containing resin lubricant supplied from the cage 4 to further smoothen the operation. The operation is performed.

Further, since the fluorine-containing resin constituting the cage 4 is selected from those having sufficiently high mechanical strength, it is possible to sufficiently withstand the stress applied to the cage from various directions and prevent damage. To be done. Moreover, it is possible to select from low melt viscosities, and even crown type cages with complex shapes and cages for cylindrical roller bearings with relatively thin column parts can be manufactured by injection molding, so at low cost. It can be mass-produced.

The corrosion-resistant rolling bearing of the present invention can be applied to roller bearings as well as ball bearings. Further, the present invention is not limited to radial bearings and can be applied to thrust bearings.

[0023]

EXAMPLES The effects of the present invention will be described below with reference to examples and comparative examples. A rolling bearing having the structure shown in FIG.
6) was trial-produced using various materials to obtain a test piece. The cage was the crown type shown in FIG. 2, and six rolling elements (balls) and two solid lubricant supply members were assembled. The diameter of the solid lubricant supply member was smaller than the ball diameter by 0.05 mm.

The rolling bearing of this test piece was operated under the following conditions, and the radial internal clearance after 500 hours was measured to evaluate the lubrication state from the wear amount. Rotation test conditions: rotation speed; 300 rpm radial load; 170 kgf atmosphere; water (ion-exchanged water) grease; none The material composition of each member of the specimen is as follows.

(Example 1) Inner ring, outer ring, rolling element: silicon nitride (Si ₃ N ₄ ) cage: potassium titanate whisker [Otsuka Chemical Co., Ltd.,
Trade name: TISMO-D] 20% by weight and ETFE [Daikin Industries, Ltd., trade name: NEOFLON ETFE] 80
Injection molding is performed by kneading wt% and pelletizing.

Solid lubricant supply member: PTFE [Moritex Co., Ltd., Teflon ball] (Example 2) Inner ring, outer ring, rolling element: Silicon nitride (Si ₃ N ₄ ) cage: Carbon fiber (PAN type) [Japan Carbon Co., Ltd., trade name; Carboron Z] 15% by weight and ETF
E [Daikin Industries, Ltd., trade name; NEOFLON ETF
E] 85 wt% was kneaded and pelletized, and injection molded.

Solid lubricant supply member: PTFE [Moritex Co., Ltd., Teflon sphere] (Example 3) Inner ring, outer ring, rolling element, cage: same as in Example 1 Solid lubricant supply member: graphite sphere (artificial graphite (Example 4) Inner ring, outer ring, rolling element: alumina (Al ₂ O ₃ ) Cage: aluminum borate whisker [Shikoku Kasei Co., Ltd., trade name; Arbolex G] 20% by weight and P
CTFE [Daikin Industries, Ltd., trade name; NEOFLON C
TFE] 80 wt% was kneaded and pelletized, and injection molded.

Solid lubricant supply member: PFA [Daikin Industry Co., Ltd., trade name; NEOFLON PFA] is injection molded. (Example 5) Inner ring, outer ring, rolling element: Giurconia (ZrO ₂ ) Cage: Silicon Carbide Whisker [Idemitsu Material Co., Ltd., trade name; SiC Whisker M Grade] 20 wt% and PVdF [Daikin Industry Co., Ltd.] Product name: NEOFLON VDF] 80 wt% is kneaded and pelletized, and injection molded.

Solid lubricant supply member: 25% by weight of fluorocarbon [Nippon Carbon Co., Ltd.] and 75% by weight of PFA [Daikin Industry Co., Ltd., trade name: NEOFLON PFA] are kneaded and pelletized. Molding (Comparative Example) Inner ring, outer ring, rolling element: Silicon nitride (Si ₃ N ₄ ) Cage: PTFE (crown type, manufactured by machining) Rolling of 6 types of specimens of Examples 1 to 5 and Comparative Example above Table 2 shows the results obtained by operating the bearing under the above conditions and measuring the radial internal clearance after 500 hours.

[0030]

[Table 2]

From the results shown in Table 2, in the case where the inner ring, the outer ring and the rolling elements were made of silicon nitride, the sample rolling bearings of Examples 1 to 3 of the present invention had a clearance amount of less than half that of the comparative example, and It is clear that the good condition of lubrication is maintained with a small amount.

[0032]

As described above, according to the present invention,
Since the inner ring, outer ring and rolling elements are made of ceramics, and the cage is made of fluorine-containing resin, it exhibits excellent corrosion resistance in various corrosive atmospheres such as water, seawater, acid, alkali, etc. However, there is an effect that smooth operation can be maintained for a long period of time.

Moreover, since the fluorine-containing resin of the cage has a high mechanical strength and can be injection-molded, it is possible to secure sufficient durability even for a cage that receives complicated stress. Even a complex shape such as a mold holder can be mass-produced and the cost can be reduced. Also,
At least one solid lubricant supply member arranged between the bearing rings supplies the solid lubricant to the raceway surface and the rolling element surface at the start of operation to form a lubricating film, so lubricants such as grease cannot be used at all. Even in a corrosive atmosphere, a good lubricating state can be maintained from the initial stage of operation, and wear can be significantly reduced compared to the conventional corrosion-resistant rolling bearing.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an embodiment of a corrosion resistant rolling bearing according to the present invention.

FIG. 2 is a perspective view of a crown-type cage used for the bearing shown in FIG.

FIG. 3 is a diagram illustrating a load application direction of a destructive test of the crown-type cage shown in FIG.

[Explanation of symbols]

 1 Inner ring 2 Outer ring 3 Rolling element 4 Cage 5 Solid lubricant supply member

Claims (1)

[Claims] 1. A bearing ring made of a ceramic inner ring and an outer ring and a rolling element, a cage made of a fluorine-containing resin that can be molded by injection molding, and at least a rolling member disposed between the bearing rings and rolling on the raceway surface. A corrosion-resistant rolling bearing comprising one solid lubricant supply member.