JP2013060990A - Rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling bearing capable of reducing a friction coefficient on a fitted part, restraining a creep phenomenon, and preventing an increase in manufacturing cost due to complicated machining and increase in the number of workpieces.SOLUTION: When an outer circumferential face 11b of an outer race 11 is fitted and fixed on a fixed member H, an inner circumferential face 12b of an inner race 12 is fitted and fixed on a rotation member S. When the outer circumferential face 11b of the outer race 11 is fitted and fixed on the rotation member S, the inner circumferential face 12b of the inner race 12 is fitted and fixed on the fixed member H. At least one average surface roughness of the outer circumferential face 11b of the outer race 11 and the inner circumferential face 12b of the inner race 12 is set at 0.1 μmRa or less. A lubricant is applied between the circumferential faces 11b, 12b and fitting faces H1, S1 of the fixed member H or the rotation member S set on the average surface roughness.

Description

  The present invention relates to a rolling bearing, and more particularly to a rolling bearing used for an industrial motor, a household electric motor, and the like.

  A rolling bearing is, for example, an outer ring having an outer ring raceway surface on an inner peripheral surface, an inner ring having an inner ring raceway surface on an outer peripheral surface, and a plurality of balls arranged so as to be able to roll between the outer ring raceway surface and the inner ring raceway surface. (Rolling element) and a cage that holds a plurality of balls in a circumferential direction so as to roll freely.

  When the rolling bearing is of the inner ring rotating type, the outer peripheral surface of the outer ring is fitted and fixed to a predetermined housing and the inner peripheral surface of the inner ring is fitted and fixed to a predetermined shaft. On the other hand, it is supported rotatably.

  Here, in this type of rolling bearing, a phenomenon in which the outer ring rotates in a direction opposite to the rotation direction of the inner ring, that is, a so-called creep phenomenon, occurs at the fitting portion between the outer peripheral surface of the outer ring and the fitting surface of the housing. (In the case of the outer ring rotation type, the inner ring rotates in the direction opposite to the rotation direction of the outer ring). When this creep phenomenon occurs, wear occurs in the fitting portion, and wear powder due to the wear may enter the inside of the bearing, thereby reducing the bearing performance. The creep phenomenon is a phenomenon that occurs when there is a fitting gap in the fitting portion and an unbalanced load is generated, and is a problem that occurs in a free-side bearing that is assembled with a fitting gap.

  Therefore, in order to prevent this creep phenomenon, the conventional rolling bearing increases the contact friction with the receiving surface on the end surface of the outer ring or the inner ring that abuts the receiving surface in the axial direction of the housing or the shaft. The thing which provides the uneven structure which suppresses is known (for example, refer patent document 1).

  Further, as a conventional rolling bearing, there is known one in which a peripheral groove is provided on the outer peripheral surface of the outer ring and an O-ring having a small friction coefficient is attached to the peripheral groove (for example, see Patent Document 2).

JP 2009-041644 A International Publication No. 2008/084835 Pamphlet

  However, in the rolling bearing described in Patent Document 1, since the frictional force loses the creep force when the axial holding force is small or when an excessive unbalance load is applied, the creep phenomenon is suppressed depending on the use conditions. There is a possibility that the effect of this is not sufficiently obtained. Furthermore, since complicated processing is required, the manufacturing cost may increase.

  Further, in the rolling bearing described in Patent Document 2, the number of parts such as an O-ring is increased, which may increase the manufacturing cost. In addition, since it is necessary to strictly manage the crossing of the circumferential grooves provided in the outer ring, the manufacturing cost may increase. Furthermore, when the material used for the O-ring is rubber or resin, there is a problem that the use temperature is limited to about 120 °.

  Furthermore, as a general problem of this type of rolling bearing, when an unbalanced load is applied to the fitting portion, a creep phenomenon occurs remarkably in the outer ring, resulting in a decrease in bearing life and wear due to heat generation. There was a possibility that the bearing life could be reduced due to the powder intrusion.

  The present invention has been made in view of the above-described circumstances, and its purpose is to reduce the coefficient of friction at the fitting portion and suppress the creep phenomenon, and manufacture by complicated processing and an increase in the number of parts. An object of the present invention is to provide a rolling bearing capable of preventing an increase in cost.

The above object of the present invention can be achieved by the following constitution.
(1) An outer ring in which an outer ring raceway surface is provided on an inner peripheral surface, an inner ring in which an outer ring raceway surface is provided with an inner ring raceway surface, and a plurality of rolling elements that are rotatably arranged between the outer ring raceway surface and the inner ring raceway surface. When the outer peripheral surface of the outer ring is fitted and fixed to the fixing member, the inner peripheral surface of the inner ring is fitted and fixed to the rotating member, and when the outer peripheral surface of the outer ring is fitted and fixed to the rotating member, the inner ring A rolling bearing in which the inner peripheral surface of the inner ring is fitted and fixed to a fixing member, and the average surface roughness of at least one of the outer peripheral surface of the outer ring and the inner peripheral surface of the inner ring is set to 0.1 μmRa or less, and the average surface roughness A rolling bearing, characterized in that a lubricant is applied between a peripheral surface set to 1 and a fitting surface of a fixed member or a rotating member.
(2) The rolling bearing according to (1), wherein a circumferential groove is provided on a circumferential surface to which a lubricant is applied, of the outer circumferential surface of the outer ring and the inner circumferential surface of the inner ring.

  According to the present invention, the average surface roughness of at least one of the outer peripheral surface of the outer ring and the inner peripheral surface of the inner ring is set to 0.1 μmRa or less, and the peripheral surface set to the average surface roughness and the fixed member or the rotating member Since the lubricant is applied between the fitting surface and the fitting surface, the coefficient of friction at the fitting portion can be reduced and the creep phenomenon can be suppressed. Moreover, since it is only necessary to process the outer peripheral surface of the outer ring or the inner peripheral surface of the inner ring to a predetermined average surface roughness, it is possible to prevent an increase in manufacturing cost due to complicated processing and an increase in the number of parts.

It is sectional drawing explaining 1st Embodiment of the rolling bearing which concerns on this invention. It is sectional drawing explaining 2nd Embodiment of the rolling bearing which concerns on this invention. It is a graph which shows the relationship between a fitting clearance gap and limit creep force. It is a graph which shows the relationship between the rotation continuation time of a bearing, and creep resistance.

  Hereinafter, each embodiment of the rolling bearing which concerns on this invention is described in detail based on drawing.

(First embodiment)
First, a first embodiment of a rolling bearing according to the present invention will be described with reference to FIG.

  As shown in FIG. 1, the rolling bearing 10 of the present embodiment includes an outer ring 11 having an outer ring raceway surface 11a on an inner peripheral surface, an inner ring 12 having an inner ring raceway surface 12a on an outer peripheral surface, an outer ring raceway surface 11a and an inner ring raceway. There are provided a plurality of balls (rolling elements) 13 that are arranged to be freely rollable between the surface 12a and a holder 14 that holds the balls 13 at a predetermined interval in the circumferential direction. The rolling bearing 10 is an inner ring rotation type bearing. The outer peripheral surface 11b of the outer ring 11 is fitted and fixed to the housing (fixing member) H, and the inner peripheral surface 12b of the inner ring 12 is fitted to the shaft (rotating member) S. It is fixed.

  Seal members 15 for sealing the bearing space between the outer ring 11 and the inner ring 12 are attached to both ends of the outer ring 11 in the axial direction. The seal member 15 includes an annular cored bar 16 and a resin-made elastic body 17 that is injection-molded on the cored bar 16.

  In the present embodiment, the outer peripheral surface 11b of the outer ring 11 is polished, and the average surface roughness of the outer peripheral surface 11b of the outer ring 11 is set to 0.1 μmRa or less. Further, a lubricant G such as urea grease is applied to the fitting portion between the outer peripheral surface 11 b of the outer ring 11 and the fitting surface H 1 of the housing H. In addition, the grease which is the lubricant G can be appropriately selected according to the use environment.

  As described above, according to the rolling bearing 10 of the present embodiment, the average surface roughness of the outer peripheral surface 11b of the outer ring 11 is set to 0.1 μmRa or less, and the outer peripheral surface 11b of the outer ring 11 and the fitting surface of the housing H Since the lubricant G is applied to the fitting portion with H1, the coefficient of friction at the fitting portion between the outer ring 11 and the housing H can be reduced and the creep phenomenon can be suppressed. Moreover, since it is only necessary to process the outer peripheral surface 11b of the outer ring 11 to a predetermined average surface roughness, it is possible to prevent an increase in manufacturing cost due to complicated processing and an increase in the number of parts.

  Here, when there is a fitting gap in the fitting portion and an unbalanced load is generated, if the friction coefficient of the fitting portion is small and a sufficient lubrication state is maintained in the fitting portion, the outer ring 11 Is accompanied by the rotation of the inner ring 12 and further forms an oil film at the fitting portion, so that the creep phenomenon does not occur. And this invention utilizes the delay effect of the creep phenomenon by oil film formation in the said fitting part.

  In this embodiment, since it is an inner ring rotation type bearing, the average surface roughness of the outer peripheral surface 11b of the outer ring 11 is set to 0.1 μmRa or less, and the outer peripheral surface 11b of the outer ring 11 and the fitting surface H1 of the housing H are set. In the case of a bearing of the outer ring rotating type, the average surface roughness of the inner peripheral surface 12b of the inner ring 12 is set to 0.1 μmRa or less, and the inner peripheral surface of the inner ring 12 is applied. A lubricant G is applied between 12b and the fitting surface S1 of the shaft S.

(Second Embodiment)
Next, a second embodiment of the rolling bearing according to the present invention will be described with reference to FIG. Note that the same or equivalent parts as those in the first embodiment are given the same or equivalent reference numerals in the drawings, and the description thereof is omitted or simplified.

  In the present embodiment, as shown in FIG. 2, two annular circumferential grooves 20 are formed on the outer circumferential surface 11 b of the outer ring 11 to which the lubricant G is applied, spaced apart in the axial direction. It functions as a lubricant reservoir.

  As described above, according to the rolling bearing 10 of the present embodiment, since the two circumferential grooves 20 are formed on the outer peripheral surface 11b of the outer ring 11, the outer periphery of the outer ring 11 can be used even if the bearing 10 is used for a long period of time. Lubricity can be maintained at the fitting portion between the surface 11b and the fitting surface H1 of the housing H. Thereby, a creep phenomenon can be suppressed over a long period of time.

In this embodiment, since the inner ring rotation type bearing is used, the peripheral groove 20 is formed on the outer peripheral surface 11b of the outer ring 11. However, in the case of the outer ring rotation type bearing, the peripheral groove is formed on the inner peripheral surface 12b of the inner ring 12. 20 is formed. Moreover, the shape (depth, width), number, etc. of the circumferential groove 20 are not limited to the above, and can be appropriately adjusted according to the amount of the lubricant G required.
About another structure and an effect, it is the same as that of the said 1st Embodiment.

  Next, in order to confirm the effects of the present invention, the rolling bearing of the present invention and the rolling bearing of the comparative example were compared by performing a creep test and a rotational durability test.

(Creep test)
In this test, the surface roughness of the outer peripheral surface (11b) of the outer ring (11) was set to 0.1 μmRa, 0.05 μmRa, and 0.02 μmRa as the rolling bearing of the present invention, respectively, and the outer peripheral surface of the outer ring (11) ( Three types of rolling bearings (invention examples 1 to 3, corresponding to the first embodiment) are prepared by applying a lubricant (urea grease) to 11b). Moreover, as a rolling bearing of a comparative example, a rolling bearing having a standard product (Comparative Example 1) and an O-ring mounted on a pair of circumferential grooves formed on the outer peripheral surface (11b) of the outer ring (11) (Comparative Example 2). Prepare. In addition, all the test bearings use the bearing identification number 6202ZZ as a base.

  In this test, first, the outer peripheral surface (11b) of the outer ring (11) of the test bearing is fitted and fixed to the fitting surface (H1) of the housing (H), and the inner peripheral surface (12b) of the inner ring (12). The shaft (S) was inserted, and the inner peripheral surface (12b) of the inner ring (12) was fitted and fixed to the fitting surface (S1) of the shaft (S). Next, an unbalanced load was placed on the disk attached to the shaft (S), the shaft (S) was rotated, and the unbalanced load was loaded on the test bearing. Then, the number of revolutions of the shaft (S) was gradually increased, and the limit creep force at which the creep phenomenon started to occur in the outer ring (11) was measured a plurality of times, and the average value was calculated. Further, the above measurement was performed by changing the fitting gap between the outer peripheral surface (11b) of the outer ring (11) and the fitting surface (H1) of the housing (H). The results are shown in FIG.

  As is clear from FIG. 3, it was found that all of Examples 1 to 3 of the present invention have a higher limit creep force and exhibit creep resistance performance regardless of the fitting gap as compared with Comparative Example 1. Moreover, it turned out that all of the inventive examples 1 to 3 exhibit higher creep resistance than Comparative Example 2 in a loose region where the fitting gap is 15 μm or more. In addition, G7, G6, F7, and F6 are effective for the mating intersection. However, when aluminum or the like is used for the housing for weight reduction, even when it is made tighter, for example, H7 or H6, due to the thermal expansion of the housing. It has been found that a fitting gap similar to the above is obtained, which is more advantageous.

(Rotational durability test)
In this test, as the rolling bearing of the present invention, the surface roughness of the outer peripheral surface (11b) of the outer ring (11) is set to 0.1 μmRa, and two peripheral grooves ( 20) to form a rolling bearing (invention example 4, corresponding to the second embodiment) in which two circumferential grooves (20) are filled with a lubricant (urea grease). In addition, as a comparison with Invention Example 4, the Invention Example 1 is prepared. Note that the test bearing of Example 4 of the present invention also uses the bearing identification number 6202ZZ as a base.

  In this test, similar to the above test, the test bearing is set on the housing (H) and the shaft (S), and the shaft (S) is continuously rotated for 5000 hours. The results of measuring the change are shown in FIG.

  As is apparent from FIG. 4, in Example 4 of the present invention, even when the sample was rotated for 5000 hours, the creep resistance was maintained without decreasing, and the long-term creep resistance was confirmed. Further, in both Invention Example 1 and Invention Example 4, there is no noticeable fretting mark on the outer peripheral surface (11b) of the outer ring (11), and there is a fretting mark on a general bearing (no data in the figure) tested in the same manner. The anti-fretting effect was also confirmed.

  In addition, this invention is not limited to what was illustrated to the said embodiment, In the range which does not deviate from the summary of this invention, it can change suitably.

DESCRIPTION OF SYMBOLS 10 Rolling bearing 11 Outer ring 11a Outer ring raceway surface 11b Outer peripheral surface 12 Inner ring 12a Outer ring raceway surface 12b Inner peripheral surface 13 Ball (rolling element)
14 Cage 20 Circumferential groove G Lubricant H Housing (fixing member)
H1 Mating surface S Shaft (Rotating member)
S1 mating surface

Claims (2)

An outer ring in which an outer ring raceway surface is provided on an inner peripheral surface, an inner ring in which an outer ring raceway surface is provided with an inner ring raceway surface, and a plurality of rolling elements that are rotatably arranged between the outer ring raceway surface and the inner ring raceway surface; With
When the outer peripheral surface of the outer ring is fitted and fixed to the fixing member, the inner peripheral surface of the inner ring is fitted and fixed to the rotating member, and when the outer peripheral surface of the outer ring is fitted and fixed to the rotating member, the inner ring Is a rolling bearing in which the inner peripheral surface is fitted and fixed to the fixing member,
The average surface roughness of at least one of the outer peripheral surface of the outer ring and the inner peripheral surface of the inner ring is set to 0.1 μmRa or less,
A rolling bearing, wherein a lubricant is applied between a peripheral surface set to the average surface roughness and a fitting surface of the fixed member or the rotating member.   The rolling bearing according to claim 1, wherein a circumferential groove is provided on a circumferential surface to which the lubricant is applied, of the outer circumferential surface of the outer ring and the inner circumferential surface of the inner ring.

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