JP2000120666A - Rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the long lifetime even in the condition that peeling and breakdown is generated line the case of ATF oil lubrication by regulating a ratio of a long diameter of a contact ellipse of an inner ring to a diameter of a rolling body and a ratio of the long diameter of a contact ellipse of an outer ring to the long diameter of the contact ellipse of the inner ring at the time of applying a basic operating rated load. SOLUTION: A contact ellipse S1 is formed in a contact part of a raceway groove M1 of an inner ring 1 with a ball 3 having a diameter DW, and a contact ellipse S2 is formed in a contact part of a raceway groove M2 of an outer ring 2 with the ball 3. At the time of applying a basic operating rated load, a ratio of the long diameter Ba of the contact ellipse S1 to the diameter DW of the rolling body 3 is set so as to satisfy a relation that 0.25<=Ba/DW<=0.35, and a ratio of the long diameter Aa of the contact ellipse S2 to the long diameter Ba of the contact ellipse S1 is set so as to satisfy a relation that 0.6<=Aa/Ba<=0.9. At the time of ATF oil lubrication, the tangent force to be generated in a contact area even in the condition that the peeling and breakdown can be generated is restricted by regulating the ratio to the contact ellipse, and the lifetime can be prolonged by restricting the generation of heat.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing, and more particularly to an improvement in the rolling life of a radial ball bearing used for an application requiring a long life, such as an automatic transmission of an automobile.

[0002]

2. Description of the Related Art The most common radial ball bearing among rolling bearings has an outer ring groove radius re and a rolling element diameter Dw.
(Re / Dw = fe) and the inner ring groove radii ri and Dw
(Ri / Dw = fi) is, for example, JIS B15
As shown in FIG. 18, both fe and fi are 0.52
Is used. However, in the conventional radial ball bearing in which both the value of fe of the outer ring and the value of fi of the inner ring which are the standard specifications are 0.52, the difference between the outer diameter of the inner ring groove and the inner diameter of the outer ring groove from the shaft center is caused by the difference. Due to the difference in curvature, the maximum surface pressure Pmax generated in both grooves is higher in the inner ring than in the outer ring. Therefore, flaking due to fatigue is more likely to occur on the inner ring. On the other hand, the size of the contact ellipse is opposite to the surface pressure, and the contact ellipse of the outer ring having a relatively small Pmax is larger than that of the inner ring.

[0003] As described above, the basics of the conventional rolling bearing design technology focus on only Pmax, and have a design specification that reduces the value of Pmax.

[0004]

However, in recent years,
Depending on the conditions of use of the rolling bearing, the phenomenon of peculiar peeling failure of a different form from the conventional one becomes apparent. In that case, to extend the life of the bearing, it is not enough to simply reduce the value of Pmax only by design specification There is a problem that expected results cannot be obtained.

For example, a bearing used in an automatic transmission (AT) of an automobile may be used with a special lubricating oil (ATF oil) containing a special friction modifier or the like. Under such conditions, it has been found that a different form of peeling failure occurs. Referring to FIG. 6, (a) shows a form of peeling failure under use conditions determined by Pmax using a conventional mineral oil, and the starting point H of peeling is located at the center of the groove width of the track groove M. (Hereinafter referred to as A-type peeling). On the other hand, (b) shows the case of a bearing used for ATF oil lubrication for an automobile, in which the position of the starting point H of peeling is a peculiar peeling damage form starting from the end of the raceway groove M (hereinafter, referred to as the following). B-type peeling).
It is considered that the B-type delamination failure mode is caused by a tangential force and heat generated in the contact region because the lubricating oil contains a special friction modifier and the like.

Accordingly, the present invention has been made in view of the above-mentioned problems of the prior art, and has a long service life even under conditions in which a specific peeling failure form can occur, such as in the case of ATF oil lubrication. It is intended to provide a bearing.

[0007]

Means for Solving the Problems In order to achieve the above object, the inventors of the present invention have conducted repeated investigations on the form of peeling damage peculiar to ATF oil lubricated bearings. It has been found that the ratio between the major axis of the contact ellipse and the diameter of the rolling element greatly affects the bearing life caused by the pealing failure. And the major axis B of the contact ellipse of the inner ring
a / Ba and Dw of the rolling element diameter and the ratio Aa / Ba of the diameter Aa of the contact ellipse of the outer ring to the major axis Ba of the contact ellipse of the inner ring, that is, under a certain use condition. The inventors have found that the life of the bearing can be extended by defining the major axis of the contact ellipse, and have completed the present invention.

[0008] That is, the rolling bearing according to the present invention, when a basic dynamic load rating is applied, the major diameter B of the contact ellipse of the inner ring
a / Ba / Dw ≦ 0.25 ≦ Ba / Dw ≦
0.35 and the ratio of the major axis Aa of the contact ellipse of the outer ring to the major axis Ba of the contact ellipse of the inner ring is 0.6 ≦ A.
a / Ba ≦ 0.9.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the present invention used under ATF oil.
FIG. 1 is a half sectional view of a radial ball bearing which is a bright rolling bearing;
Is the inner ring, 2 is the outer ring, 3 is the rolling element between the inner ring 1 and the outer ring 2.
There are a plurality of rolling elements (balls) interposed between the rolling elements. Of inner ring 1
Track groove M₁(Groove radius ri) and contact part of ball 3 of diameter Dw
The contact ellipse S shown in FIG.₁Is formed
You. Also, the raceway groove M of the outer ring 2_Two(Groove radius re) and ball 3
(Diameter Dw), the contact portion shown in FIG.
Ellipse S_TwoAre formed. Inner ring side contact ellipse S ₁Dimensions
The method is a major axis Ba and a minor axis Bb, and the contact ellipse S on the outer ring side.
_TwoIs a major axis Aa and a minor axis Ab.

[0011] As a design standard of a general radial ball bearing,
The ratio re / D of the outer ring groove radius re to the rolling element diameter Dw.
w = fe and ratio ri / Dw of inner ring groove radius ri to Dw =
It is JIS B to make fi both equal to 0.52.
Although shown in 1518, in the actual bearing design, Pmax is high to reduce the curvature of the flaking of easily generated life tough inner raceway groove M ₁ a (1 / ri),
By increasing the area of contact ellipse S ₁ between the inner ring 1 and the rolling elements 3, contrivance such as to reduce the Pmax of the inner ring side made longer life have been made.

[0012] However, as the inventors of the present invention proceed with the investigation on the case where the contact ellipse is used in ATF oil lubrication, the above-mentioned peculiar phenomenon of the B-type peeling has a close relation with the contact ellipse, and rather, the contact ellipse is reduced. It has been found that as the size increases, the life characteristics deteriorate. It was also found that the peel life was closely related to the value of the ratio between the major axis of the contact ellipse and the diameter of the rolling element. Further, it was also found that the value of the ratio that affects the peel life differs between the outer ring and the inner ring.

[0013] In the rolling bearing of the present invention,
Based on the fact, the outer ring groove radius re and the rolling element diameter Dw
Of the ratio (re / Dw) of the inner ring groove radius ri and Dw
And the value fi of the ratio (ri / Dw) to
By adjusting the clearance, the basic dynamic load rating Cr
Inner ring contact ellipse S when loaded₁Of the long diameter Ba of the rolling element 3
Ratio Ba / Dw with diameter Dw and outer ring contact ellipse S_TwoHead of
Diameter Aa and inner ring contact ellipse S ₁Ratio Aa / Ba with the long diameter Ba
Is defined to be within a predetermined value range. However,
The major axis (Aa, Ba) of the contact ellipse of the inner and outer rings is the bearing specification
It is not determined by the use of
Affected. Therefore, in the present invention, the bearing operating conditions
As described above, the basic dynamic load rating Cr
Of the contact ellipse when a load is applied.

Hereinafter, the present invention will be described based on a life comparison test performed on a radial ball bearing having a nominal number of 6206.

The ratio fe between the groove radius and the ball diameter of the bearing outer ring and the ratio fi between the groove radius and the ball diameter of the inner ring manufactured for this test.
Are shown in Table 1.

[0016]

[Table 1] As shown in Table 1, a plurality of types of outer races with fe ranging from 52 to 60% and inner races with fi ranging from 50.5 to 56.5% were manufactured. By appropriately combining the outer ring and the inner ring to assemble a ball bearing, test specimens having different contact ellipse areas when the basic dynamic load rating Cr was applied were obtained. That is, specifically, an embodiment in which the ratio Aa / Ba of the major axis Aa of the contact ellipse of the outer ring to the major axis Ba of the contact ellipse of the inner ring and the ratio Ba / Dw of the major diameter Ba of the contact ellipse of the inner ring and the ball diameter Dw are different. Radial ball bearings of test samples 1 to 10 and Comparative Examples 1 to 8 were assembled. The Cr here is JIS B
1518. In addition, SUJ2 was used as the material of the test specimen, and the same processing and heat treatment were applied to the outer ring and the inner ring. The surface hardness of each specimen is HRC5
8 to 64, and the amount of retained austenite is 0 to 20.
%, The surface roughness of the bearing ring is in the range of 0.01 to 0.04 μm Ra. <Conditions for Life Test> Using the radial ball bearings of Examples 1 to 10 and Comparative Examples 1 to 8 assembled with a combination of inner and outer rings as shown in Table 1 as test specimens, Nippon Seiko Co., Ltd. ball bearing life test It was measured basic rating life (10 ⁶ revolutions) L ₁₀ under clean lubrication under the following conditions using the machine.

Tester name: Ball bearing life tester Test load: P / C = 0.46 Bearing rotation speed: 1200 rPm Test temperature: 110 ° C. Lubricating oil: ATF oil <Method of life test> Ten test bearings A life test was performed under the above conditions. The life was determined by interrupting the test when the vibration value of the test specimen bearing on the test machine became twice the initial vibration value, and checking whether or not the raceway groove surface had peeled off. The longest test time was 500 hours, and the subsequent tests were terminated. And by the Weibull distribution function,
The total rotation time until peeling occurred in 10% of the bearings from the short life side among the ten specimen bearings was determined, and this was defined as the life.

Table 2 shows the test results.

[0019]

[Table 2] As shown in Table 2, the life of each bearing of Examples 1 to 10 is as follows:
It has a long life of at least 1.2 times or more and at most 2.45 times the calculated life of about 143 hours (JIS B 1518). Further, the site of the peeling failure was the outer ring or the inner ring, and the peeling form was all the A type as in the case of the mineral oil lubrication.

In the first to sixth embodiments, the major axis of the contact ellipse of the outer ring is hardly changed (with a value of approximately 0.3) of the ratio Ba / Dw of the major axis Ba of the contact ellipse of the inner ring to the ball diameter Dw. The combination was performed by changing the value of the ratio Aa / Ba between Aa and the major axis Ba of the contact ellipse of the inner ring (in the range of 0.885 to 0.607), and the result was that the life was greatly extended. Obtained. On the other hand, in Examples 7 to 10, a combination was selected such that the ratio of the groove curvatures of the outer ring and the inner ring was kept constant, and the ratio (Aa / Ba) between the long diameter of the contact ellipse of the outer ring and that of the inner ring was substantially the same. Thus, a remarkable life extension effect is obtained.

From the first to tenth embodiments, a raceway ring considering the ratio Ba / Dw of the major diameter Ba of the contact ellipse of the inner ring and the ball diameter Dw and the ratio Aa / Ba of the major diameter of the contact ellipse of the outer ring and that of the inner ring is taken into consideration. It is clear that the combination can achieve a longer bearing life with ATF oil lubrication.

On the other hand, in Comparative Examples 1 to 8, unlike the results of the examples, all of the peeling lives did not reach the calculated lifetimes (about 143 hours). The peeled portion was either the inner ring or the outer ring, and the type of damage was B type, which is unique to ATF oil lubrication.

In Comparative Example 1, the ratio Ba / Dw between the major axis Ba of the inner ring and the ball diameter Dw of the contact ellipse Ba / Dw was 0.54, which is the largest among the test pieces. The value of the ratio Aa / Ba with respect to the long diameter Ba was the smallest, that is, 0.516. The peeling life was much shorter than the calculated life, the peeling portion was the inner ring, and the peeling form was B type.

In Comparative Example 2, the ratio (re / Dw) fe between the outer ring groove radius re and the rolling element diameter Dw and the inner ring groove radius ri were determined.
The ratio (ri / Dw) fi between Dw and Dw is calculated according to JIS B151.
The value is set to 52% similarly to the value shown in FIG.
The value of Ba / Dw is 0.314, which is almost the same as in Examples 1 to 10, whereas the value of Aa / Ba is 0.968, which is the largest value in the specimen, and the peel life is 75 hours. It was much shorter than the calculated life. The area of the peeling was the outer ring, and the peeling form was the B type peculiar to the ATF oil as in Comparative Example 1.

In Comparative Example 3, based on the result of Comparative Example 2 that the outer ring was peeled, the value of Aa / Ba was changed by changing only the groove radius re of the outer ring while keeping the value of Ba / Dw the same. Is 0.59, which is the smallest, but the peeling life is 140 hours, which is almost the same as the calculated life. And although the part of peeling was outer ring peeling like Comparative Example 2, the damage form changed to A type same as mineral oil.

In Comparative Examples 4 and 5, the value of Ba / Dw was set to be larger than that of
The bearings of the combination in which the value of a was relatively small had peeling lives of 80 hours and 130 hours, respectively, and the peeled portions were all inner rings, and the type of damage was B type specific to ATF oil lubrication.

With respect to Comparative Examples 6 and 7, the value of Ba / Dw was set to be the smallest, and
/ Ba value is relatively large,
The peel life is 120 hours and 60 hours, respectively.
In each case, the exfoliation site was the inner ring. The peeling form was the same type A as the mineral oil.

Comparative Example 8 is a bearing having a combination of values as shown in Table 2. The peeling life is about 135 hours, which is almost the same as the calculated life, and the peeling occurs. Was of type B.

The results shown in Table 2 are plotted on a graph.

FIG. 3 shows the life L ₁₀ (Hr) of each specimen,
Ratio Ba / D of major diameter Ba of contact ellipse of inner ring and ball diameter Dw
This shows the relationship with w. Taking the L ₁₀ life on the vertical axis, Ba horizontal axis
/ Dw values are plotted. The following can be said from FIG. Examples in which the ratio of Ba / Dw is in the range of 0.3 ± 0.05 have a longer life than 1.2 times the calculated life, and the comparative example has a shorter life.

FIG. 4 shows the life L ₁₀ (Hr) of each specimen,
The major axis Aa of the contact ellipse of the outer ring and the major axis Ba of the contact ellipse of the inner ring
The relationship is shown below. Taking the L ₁₀ life on the vertical axis, the horizontal axis Aa /
The ratio of Ba is plotted. The following can be said from FIG. The ratio of Aa / Ba is 0.6 ≦ Aa / B
The examples within the range of a ≦ 0.9 have a long life of about 1.2 times or more of the calculated life, and the life of the comparative example is reduced. That is, it can be seen from FIGS. 3 and 4 that the service life is not extended even if only one of them is in the claims as in Comparative Examples 1 to 8. That is, the value of Ba / Dw and Aa
Only when the bearing specifications satisfy both of the values of / Ba are satisfied, the life is long. Therefore, in the rolling bearing of the present invention, when the basic dynamic load rating is applied, as shown in FIG. The ratio of the major axis Ba of the inner ring contact ellipse to the diameter Dw of the rolling element satisfies the relationship of 0.25 ≦ Ba / Dw ≦ 0.35, and the major axis Aa of the contact ellipse of the outer ring and the major axis Ba of the contact ellipse of the inner ring. Is 0.6 ≦ Aa / Ba ≦ 0.9.
Is defined as a long-life bearing specification in ATF oil lubrication. More preferably, the ratio of the major axis Ba of the contact ellipse of the inner ring to the diameter Dw of the rolling element is 0.30 when a basic dynamic rated load is applied, as a long life range of at least twice the calculated life shown in the embodiment. ≦ Ba / Dw ≦ 0.32, and the ratio of the major axis Aa of the contact ellipse of the outer ring to the major axis Ba of the contact ellipse of the inner ring is 0.6 ≦ Aa / Ba ≦
The range of 0.75 is defined as a long life bearing specification in ATF oil lubrication. This is presumably because the tangential force generated in the contact area was suppressed by defining the ratio to the contact ellipse, and the life was extended by suppressing heat generation.

[0032]

As described above, according to the present invention, the specification of the radial ball bearing is set to be 0.25 ≦ Ba / Dw ≦
0.35 Aa / Ba
≤ 0.9 range, so that the rolling life of radial ball bearings and the like used in applications that require a long life, such as automatic transmission of automobiles,
This has the effect of being able to be significantly extended compared to the prior art.

[Brief description of the drawings]

FIG. 1 is a half sectional view of a main part of a rolling bearing of the present invention.

2A and 2B are cross-sectional views of groove portions of an outer ring and an inner ring, wherein FIG. 2A shows a contact ellipse of an inner ring raceway groove, and FIG.

3 is a graph showing the relationship between the Ba / Dw and L ₁₀ life.

4 is a graph showing the relationship between Aa / Ba and L ₁₀ life.

FIG. 5 is a graph showing a relationship between Ba / Dw and Aa / Ba.

FIG. 6 is a schematic cross-sectional view illustrating a difference between types (A and B) of peel damage.

[Explanation of symbols]

1 the inner ring 2 an outer ring 3 rolling element r _i the inner raceway ring groove curvature radius Dw transfer body diameter r _e outer raceway ring groove curvature radius Aa major axis diameter Ba inner ring of the contact ellipse of the contact ellipse of the outer ring of the

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Nobuaki Mitamura 1-5-150 Kugenuma Shinmei, Fujisawa-shi, Kanagawa F-term in NSK Ltd. (reference) 3J101 AA02 AA42 AA52 AA62 BA53 BA54 BA55 FA31 GA11

Claims (1)

[Claims] When the basic dynamic load rating is applied, the ratio of the major diameter Ba of the contact ellipse of the inner race to the diameter Dw of the rolling element is 0.2.
The relationship of 5 ≦ Ba / Dw ≦ 0.35 is satisfied, and the ratio of the major axis Aa of the contact ellipse of the outer ring to the major axis Ba of the contact ellipse of the inner ring satisfies 0.6 ≦ Aa / Ba ≦ 0.9. And rolling bearing.