JPH0742743A - Roller bearing - Google Patents

Abstract

PURPOSE:To lessen the riskiness of seizure or banding in a roller bearing part by holding down a heating value at this roller bearing part to some extent. CONSTITUTION:Each surface roughness extending in both axial and circumferential directions of a rolling surface 2 of a roller 1 should be set to less than 0.06mumRa either side. The surface roughness of an inner ring raceway 4 that is a peripheral surface of a counterpart member is 0.08 to 0.15mumRa extending in the axial direction, but less than 0.04mumRa extending in the circumferential direction.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The roller bearing according to the present invention can be used as a full-roller needle roller bearing used in, for example, an automatic transmission for automobiles.

[0002]

2. Description of the Related Art For example, a roller bearing such as a full-roller type needle roller bearing (so-called needle bearing) is incorporated in a rotation supporting portion of a planetary gear mechanism of an automatic transmission for automobiles. In order to ensure the life of such roller bearings, the rolling surfaces of a plurality of rollers and the raceway surface formed on the peripheral surface of the mating member, such as the outer ring raceway and the inner ring raceway, which make line contact with these rolling surfaces. Line contact,
The rolling parts must be in good lubrication. Particularly in the case of the planetary gear mechanism for an automatic transmission, a sufficient supply amount of lubricating oil to the roller bearing mounting portion is not always ensured, and therefore consideration must be given to improving the lubricating state of the rolling portion.

Therefore, conventionally, the rolling contact surface and the raceway surface are finished to be as smooth as possible, and even with a small amount of lubricating oil, the metal contact between the roller and the mating member is prevented between the rolling contact surface and the raceway surface. I was trying to do it.

[0004]

However, it has been pointed out that, if the rolling surface and the raceway surface are simply finished to be smooth, the roller bearing may be seized in a remarkable case. That is,
During operation of the roller bearing, moments may be applied to the plurality of rollers in a direction that makes the central axis of each roller and the central axis of the mating member non-parallel (skew). When such a moment is applied, if the rolling surface and the raceway surface are simply smooth, each of the rollers hardly skews the moment and is skewed.

When the rollers are skewed, the resistance against the rotation of each roller becomes extremely large as compared with before the skewing, and the amount of heat generated in the roller bearing portion remarkably increases. Then, in a remarkable case, the roller bearing portion may be seized.

In order to prevent such a skew which causes such an inconvenience, for example, in Japanese Patent Publication No. 57-61933, the roughness of the outer ring raceway is made larger (rougher) than the roughness of the inner ring raceway.
However, there is described a technique in which the coefficient of friction between the rolling surface of each roller and the outer ring raceway is made larger than the friction coefficient between the rolling surface of each roller and the inner ring raceway. However, in such a conventional technique, the effect of preventing the skew of the roller is not always sufficient, and when the moment is large, the skew of the roller cannot be sufficiently prevented. The roller bearing of the present invention was invented in view of such circumstances.

[0007]

A roller bearing according to the present invention, like a conventional roller bearing, has a plurality of rollers each having an outer peripheral surface as a rolling contact surface and a raceway surface having a peripheral surface in line contact with the rolling contact surface. And a mating member. Particularly, in the roller bearing of the present invention, the surface roughness of the rolling surface in the axial direction and the circumferential direction is 0.06 μmRa or less, and the surface roughness of the peripheral surface of the mating member is , 0.08 to 0.1 in the axial direction
It is characterized by being 5 μmRa and being 0.04 μmRa or less in the circumferential direction.

[0008]

In the case of the roller bearing of the present invention configured as described above, even when a moment in the direction of skewing the roller acts, between the rolling surface of the roller and the raceway surface of the mating member,
The frictional force in the direction of preventing the roller skew acts to prevent the roller from skewing.

This state will be described with reference to FIGS. 1 to 3 show that the roller 1 is prevented from skewing by devising the contact state between the rolling surface 2 of the roller 1 and the inner ring raceway 4 which is the raceway surface provided on the outer peripheral surface of the inner ring 3. To do. In the case of the roller bearing of the present invention, as is clear from FIGS. 1 to 3, the surface roughness of the inner ring raceway 4 is not limited to the axial direction (the horizontal direction of FIGS. 1 and 2 and the horizontal direction of FIG. 3). It is relatively rough (0.08 to 0.15 μmRa) and relatively smooth (0.04 μmRa or less) in the circumferential direction. That is,
The ratio of the surface roughness in the axial direction to the surface roughness in the circumferential direction (surface roughness in the axial direction / surface roughness in the circumferential direction) is 2 or more.

As described above, the roller 1 rolls while the rolling surface 2 of the roller 1 is brought into contact with the inner ring raceway 4 having a difference between the surface roughness in the axial direction and the surface roughness in the circumferential direction. In this state, when a moment M in a direction that skews the roller 1 acts on the roller 1, a force acting on the roller 1 in a direction that opposes the moment M and prevents the roller 1 from skewing. Works.

That is, when the roller 1 tends to be skewed, the frictional state between the rolling surface 2 and the inner ring raceway 4 becomes not only rolling friction but also sliding friction. Due to this sliding friction, there is a tendency for the two surfaces 2 and 4 (referring to the rolling surface 2 and the inner ring raceway 4. The same applies hereinafter) to rub against each other in the axial direction and the circumferential direction. In the case of a roller bearing, since the surface roughness of the inner ring raceway 4 in the axial direction is larger than the surface roughness in the circumferential direction, the frictional force in the axial direction of the both surfaces 2 and 4 is It is greater than the frictional force over. Then, due to the relatively large sliding frictional force in the axial direction, a force is generated in the roller 1 against the moment M to prevent the roller 1 from skewing.

In this way, the effect of preventing the skew of the roller 1 is that the surface roughness of the outer ring raceway formed on the inner peripheral surface of the outer ring instead of the inner ring raceway 4 (or together with the inner ring raceway 4) is Direction (horizontal direction in FIGS. 1-2, left-right direction in FIG. 3) is relatively rough (0.08 to 0.15 μmRa) and relatively smooth in the circumferential direction (0.04 μmRa). The following is also obtained.

On the other hand, as shown in FIGS. 4 to 6, when the surface roughness of the inner ring raceway 4 (or the outer ring raceway) is made substantially equal in the axial direction and the circumferential direction, the inner ring raceway 4 The force in the direction for preventing the skew of the roller 1 is not sufficiently generated regardless of the surface roughness of the roller. That is, when the surface roughness is small (smooth) in both the axial direction and the circumferential direction, a frictional force enough to generate a force to counter the skew is applied to the both surfaces 2, 4 It does not work in the interval and cannot prevent the skew of the roller 1. Further, when the surface roughness is large (rough) in both the axial direction and the circumferential direction, not only the sliding frictional force in the axial direction but also the sliding frictional force in the circumferential direction becomes large. Due to the frictional force in the circumferential direction,
The force to return the skewed roller to its original state is eliminated, and the effect of preventing the skew of the roller 1 is lost. Further, if the surface roughness is increased in both directions, the lubricity between the two surfaces 2 and 4 deteriorates, which adversely affects the rolling fatigue and shortens the life of the roller bearing.

[0014]

EXAMPLES In order to confirm the effects of the present invention, the results of experiments conducted by the present inventor will be described with reference to FIGS. 7 to 9 and the description in Table 1.

FIG. 7 shows the apparatus used in the experiment. A hollow fixed shaft 6 is supported between a pair of holders 5a and 5b arranged concentrically and at a distance so as to be stretched over both holders 5a and 5b. This fixed shaft 6
Lubricating oil is fed into the inside from one holder 5b, and this lubricating oil is discharged around the fixed shaft 6 through a discharge hole 7. The outer peripheral surface of the fixed shaft 6 is the inner ring raceway 4 which is a raceway surface.

On the other hand, an outer ring 8 is provided around the fixed shaft 6.
The fixed shaft 6 is supported concentrically and rotatably.
That is, a plurality of rollers 1 and 1 are rotatably provided between the outer ring raceway 9 formed on the inner peripheral surface of the outer ring 8 and the inner ring raceway 4,
An outer ring 8 is rotatably supported around the fixed shaft 6. No cage is provided for holding the rollers 1, 1.

A driven gear 10 is externally fitted and fixed on the outer peripheral surface of the end portion (the right end portion in FIG. 7) of the outer ring 8, and the driven gear 10 and
The outer ring 8 is rotated at 16000 rpm by meshing with the drive gear 12 which is rotationally driven by the motor 11. Further, a retaining ring 14 is provided around the outer ring 8 via a pair of angular type ball bearings 13 and 13 combined in a back-to-back manner. And this retaining ring 14
To the above, a radial weight of 2500 N and a moment weight of 14 N · m are added.

Using such a test apparatus, the inner ring raceway 4 on the outer peripheral surface of the fixed shaft 6 and the rolling surfaces 2, 2 of the rollers 1, 1 are used.
When the temperature of the inner ring raceway 4 was measured while changing the surface roughness of No. 1, the results shown in Table 1 below were obtained. still,
The surface roughness value in Table 1 is the center line average roughness specified in JIS B 0601, and the unit is μmRa. The unit of the temperature of the inner ring raceway 4 is ° C.

Table 1

[Table 1]

As is clear from the description of Table 1, the roller bearing of the present invention can suppress the temperature rise in the inner ring raceway 4 portion to a low level as compared with the conventional roller bearing. Further, in the case of the roller bearing of the present invention, the temperature change in the inner ring raceway 4 portion was extremely small as shown in FIG. On the other hand, in the case of the conventional roller bearing, as shown in FIG. 9, the temperature of the inner ring raceway 4 portion largely changed.

The surface of each of the constituent members can be processed into desired properties by using appropriate abrasive grains or a binder as a grindstone and devising a processing method such as centerless processing. For example, by using a grindstone formed of fused alumina-based abrasive grains and a resinous binder, the feed rate of the workpiece is appropriately set and the grinding is performed to obtain a member having a desired surface texture. can get.

[0022]

Since the roller bearing of the present invention is constructed and operates as described above, it is possible to suppress the amount of heat generated in the roller bearing portion to be small and to reduce the risk of seizure of the roller bearing portion.

[Brief description of drawings]

FIG. 1 is a perspective view schematically showing a roller bearing of the present invention.

FIG. 2 is a view similarly seen from the circumferential direction.

FIG. 3 is a view similarly seen from the axial direction.

FIG. 4 is a perspective view schematically showing a conventional roller bearing.

FIG. 5 is a view similarly seen from the circumferential direction.

FIG. 6 is a view similarly seen from the axial direction.

FIG. 7 is a cross-sectional view of a test device performed to confirm the effects of the present invention.

FIG. 8 is a diagram showing a temperature change on a raceway surface of the roller bearing of the present invention.

FIG. 9 is a diagram showing a temperature change on a raceway surface of a conventional roller bearing.

[Explanation of symbols]

 1 roller 2 rolling surface 3 inner ring 4 inner ring raceway 5a, 5b holder 6 fixed shaft 7 discharge hole 8 outer ring 9 outer ring raceway 10 driven gear 11 motor 12 drive gear 13 ball bearing 14 retaining ring

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuo Murakami 1-3-2 Minamigaoka, Hadano City, Kanagawa Prefecture 1-306 (72) Inventor Toshiyuki Yamamoto 11-1 Shoji Town, Takasaki City Gunma Prefecture (72) Inventor Shimazaki Tamotsu Line 646-1 Nakajuku, Annaka City, Gunma Prefecture

Claims (1)

[Claims] 1. A roller bearing comprising a plurality of rollers having an outer peripheral surface as a rolling surface and a mating member having a peripheral surface as a raceway surface which makes line contact with the rolling surface. The surface roughness in both the axial direction and the circumferential direction is 0.06 μmRa or less, and the surface roughness of the peripheral surface of the mating member is 0.08 to 0.15 μmRa in the axial direction. The roller bearing is characterized by having 0.04 μmRa or less in the circumferential direction.