JP2003074565A - Rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent early separation of an oil film and prevent generation of hydrogen to elongate the life in a rolling bearing subjected to grease lubrication by using engine auxiliary devices such as alternator, electromagnetic clutch, intermediate pulley, compressor for car air conditioner, and bearing for water pump. SOLUTION: In a rolling bearing in which a plurality of rolling bodies are disposed between a fixed shaft and a rotary ring subjected to grease lubrication, the average roughness R1 of the center line of the raceway face of the fixed ring is regarded as 0.03-0.09 μmRa, and R1 and PCD are set to have a relationship as follows 1.0×10<-3> <=R1 /PCD<=3.0×10<-3> , thereby, slide is depressed and several kV static electricity is easily discharged or conducted to prevent generation of hydrogen and elongate the life.

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention
Rolling bearings, especially alternators and electromagnetic
Switch, intermediate pulley, compressor for car air conditioner, water port
Used for engine accessories such as pump bearings
Prolonging the life of bearings by setting the roughness appropriately
The present invention relates to a rolling bearing. [0002] 2. Description of the Related Art As an index relating to the life of a rolling bearing,
Oil film indicating the degree of oil film formation that greatly affects lubrication quality
The concept of parameter Λ is used ("rolling axis
Receiving Engineering ”Rolling Bearing Engineering Editorial Board: Yokendo Showa 5
The first edition was issued on July 10, 2000, p. 178).   Λ = hmin / (hr₁ ²+ Hr₂ ²)^1/2≒ hmin / 1.15 (σ₁₂ ²+ Σ _c ² )^1/2                                                                 ... (1) Where hmin = minimum oil film thickness hr₁, Hr₂= 2 contact surfaces (rolling between raceway and rolling element)
Root mean square roughness of the contact surface) σ₁₂= Center line average roughness of raceway (h ≒ 1.12R) σ_c= Center line average roughness of steel ball (h ≒ 1.12R) From the above equation (1), the value of the oil film parameter Λ is
The larger the oil film, the thicker the oil film is formed and the longer the life is.
It is understood that when Λ ≦ 3, it becomes a so-called boundary lubrication state.
It is said to shorten the life. So traditionally
Smooth the rolling contact surface between the race and the rolling element
Long service life by machining into a kana surface and forming a sufficient oil film
Was considered to be a necessary condition to achieve. [0004] Grease lubricated rolling bearings
A similar idea can be applied, thus creating a track surface
Processing to a smooth surface only
By increasing the 大 き く and improving the track surface roughness
To prevent oil film breakage and high vibration.
Was. [0005] In grease lubricated bearings, patents
In report No. 2508178, each track of outer ring and inner ring
Of the surface and the surface of the rolling element, at least the outer raceway surface,
Many with a depth of 0.0005 mm or more and 0.0008 mm or less
A groove-shaped recess, and a groove-shaped recess partitioned by the groove-shaped recess
With a smooth part with a roughness of 0.08 μm Ra or less
By forming, the sliding motion is suppressed and
The function of the oil sump in the part also acts secondary to the metal in the flat part
Prevents sticking and prevents bearing seizure, sufficient bearing performance
Are disclosed. In a grease lubricated bearing,
In Japanese Patent Publication No. 5-32602, "0.05 µm Ra <steel
"Surface roughness of ball <surface roughness of rolling surface"
The lubrication between the raceways is improved by approaching the raceway roughness.
Forming an oil film to improve the temperature of steel balls
Technology to prevent the early peeling of the steel ball surface and extend the service life
The art is disclosed. In Japanese Patent Application Laid-Open No. 4-160225,
Forms an electrical insulation film on the bearing raceway surface and
Suppression of hydrogen atom generation by electrolysis by medium reaction
Technology to prevent exfoliation accompanying structural change and extend the life
The art is disclosed. On the other hand, high speed used under grease lubrication
High temperature due to rotation, high vibration, high load (4G ~
20G) works simultaneously through the belt
In bearings for bearings, Λ becomes small, making it difficult to form an oil film
For example, a draft of the Japanese Tribology Conference
Shu (Tokyo 1995-5) p551, average rotation
It is introduced that the slip rate increases to about 25-30%
As in the fixed wheel load range where slippage is likely to occur.
If the outer ring raceway is prematurely peeled and the life of the bearing is shortened,
Such problems are conceivable. Preventing the fixed ring (bearing outer ring) from being separated at an early stage.
As a countermeasure, "SAE Technical Paper: SAE
950944 (Date February 27-March 2, 1995
1) to 14), the fatigue of the alternator bearings
Elucidating the labor mechanism and changing the enclosed grease from E grease
By changing to M grease with high damper effect,
Suppresses slip and absorbs high vibration and high load with M grease.
Technology to prevent metal contact and prevent premature separation of bearings
Is disclosed. [0010] The conventional technique as described above
In the art, as shown in Japanese Patent Publication No. 5-32602
For grease lubricated bearings, "0.05 μm Ra
<Surface roughness of steel ball <Surface roughness of rolling surface>
The distance between the steel ball and the rolling surface can be
Oil film is formed on the surface to improve lubricity and reduce the temperature rise of steel balls.
Suppress surface delamination to extend steel ball life
Can be realized, but steel
Since the ball roughness is as large as 0.05 μmRa, the vibration increases
Predictable, bearing acoustics become a problem. [0011] Further, as disclosed in Japanese Patent Publication No. 2508178,
Outer ring raceway surface is at least 0.0005 mm deep
A large number of groove-shaped recesses of 0.0008 mm or less;
0.08
By forming with a smooth part of μmRa or less, slip
Expect the effect of extending the life of fixed wheels to suppress movement
It does not take into account acoustic issues,
In addition, it does not show the optimum rotating wheel surface roughness. On the other hand, a general iron pulley is used as an auxiliary engine.
When used with a crankshaft that rotates at high speed,
Due to the friction between the driven belt and the pulley, several kV
Gas is generated and a part is discharged to the atmosphere.
Bearing track, as described in US Pat.
Form a film on the surface and use the catalytic reaction of the film,
Water in grease was decomposed into hydrogen ions by electric discharge
Reacts with hydrogen molecules to form hydrogen ions
A technology has been disclosed to prevent entry into the reception area and extend the service life.
I have. However, in the above technology, when the surface pressure is high or
When used under vibration, the surface oxide film may peel off.
Long life cannot be obtained. Accordingly, the present invention provides a grease lubricated
The rolling fatigue life of rolling bearings
In order to make it more effective, the fixed ring
Track surface center line average roughness, ie, R₁To increase
Reduces slip and reduces friction between belt and pulley.
Easily discharge or energize several kV of static electricity generated
To reduce the potential difference between the fixed and rotating wheels,
The purpose is to prevent it. [0014] Means for Solving the Problems The inventors have solved the above problems.
As a result of conducting various experiments as described below,
Multiple rolling between grease lubricated fixed shaft and rotating wheel
In rolling bearings that are used with the body
Track surface center line average roughness R₁To R₁= 0.03-0.09
μmRa, and R₁And PCD (Pitch circle straight
Engine auxiliary equipment characterized by the following relationship:
It is a rolling bearing for use. 1.0 × 10^-3≤R₁/PCD≦3.0×10^-3 [0015] BRIEF DESCRIPTION OF THE DRAWINGS FIG.
This will be described with reference to FIG. FIG. 1 shows the rolling to which the present invention is applied.
FIG. 2 is a cross-sectional view schematically showing a bearing, in which the rolling shaft
The receiver 1 is press-fitted into a housing 8 in which the outer ring 2 is fixed to the outside.
Then, the rotating shaft 7 is press-fitted into the inner ring 3, and the rolling element 4 is
Of the raceway surface 10 of the outer race 2 and the race of the inner race 3 as a rotating wheel
It is held by the retainer 5 so as to be able to roll between the road surfaces 11. Outside
Between the wheel 2 and the inner ring 3, on both sides of the rolling element 4 and the retainer 5
The seal 6 is arranged, the internal grease 9 is enclosed, and
Prevents foreign matter from entering from outside. [0016] The inventors have developed such a rolling bearing.
In order to solve the above problems, ordinary bearings and outer rings
Varying the roughness of each raceway surface of the inner ring and the surface of the rolling elements
Manufactured bearings and disclosed in JP-A-09-89724.
The number of revolutions is set to 9000 rpm every predetermined time (for example, every 9 seconds).
Switch to 18000 rpm using a rapid acceleration and reduction gear
The test was performed. Also, this test bearing has a JIS reference number.
6303, 10-15 μm in bearing clearance, load
The condition is P (load load) / C (dynamic rating load) = 0.10,
The test temperature is constant at 80 ° C.
Used. Further, the test life of the bearing at this time is 135.
0 hours, so a test censoring time of 150 hours
0 hours. The test is medium when the initial vibration rises 5 times.
And the presence or absence of peeling was calculated. The number of tests is n = 10 each
I went there. As a result, as shown in Table 1, the fixed wheel
In addition, the average roughness of the raceway surface center line of the outer ring is 0.03-0.09.
Even if it reaches 1500 hours,
No outbreak was observed. For rolling elements,
The test was performed with various changes._c= 0.002-0.0
It was confirmed that 10 μmRa was optimal. [Table 1]In order to investigate the cause, during the test and during the test
After examining the bearings after the test, long-life bearings and short-life bearings were
As shown in FIG. 2, the electric resistance of the inner and outer rings during rotation is shown in FIG.
Was measured using a slip ring, etc.
Exists, and its value is closely related to long life and short life
I found something related. As a result, the rolling bearing used under grease lubrication is used.
In rolling bearings, the rolling contact between the rolling element and its mating member
Surface roughness R of the contact surface₁, R₂Defined in JISB0601
Grease lubrication when displayed with center line average roughness
It is used by arranging multiple rolling elements between a fixed wheel and a rotating wheel.
The average roughness of the center line
Sa R₁To R₁= 0.03-0.09 μm Ra, and
One, said R₁And PCD (pitch circle diameter) have the following relationship
Rolling bearings are suitable as rolling bearings for engine accessories
It turned out to be. 1.0 × 10^-3≤R₁/PCD≦3.0×10^-3 In this rolling bearing, the mating member
In terms of the surface roughness of the rolling elements,
Therefore, it is processed with higher precision than_c
= 0.002 to 0.010 µm Ra is optimal.
is there. Next, the bearing of the embodiment and the bearing of the comparative example will be described.
The life test will be described. As a testing machine,
No. 9-89724, the number of rotations is changed at predetermined time intervals (for example,
(For example, every 9 seconds) Switch between 9000rpm and 18000rpm
A rapid acceleration / deceleration test was used. In addition, the present embodiment example and the ratio
In both cases, JIS call number 6303 was used for the test bearing.
The bearing clearance is 10 to 15 μm, and the load condition is P (negative
(Load) / C (dynamic load rating) = 0.10, test temperature 8
The temperature was kept constant at 0 ° C., and E grease was used as the sealed grease. Further, the calculated life of the bearing at this time is 1350.
Time, so the test censoring time is 1500 hours
Between. The test is performed when the initial vibration increases by 5 times.
Was interrupted and the presence or absence of peeling was confirmed. Tests are each n = 10
I went there. The bearings used in this test were two types of bearing steel.
The surface hardness of the outer and inner rings is HRC 58-63,
Stenite content is 0.05 to 15%, and the surface hardness of rolling elements
The thickness was HRC62 to 64. Table 1 shows the surface roughness of the bearing ring.
Shown in The steel ball surface roughness was 0.005 μmRa. In the calculation of the oil film parameter Λ,
The calculation of the minimum oil film thickness hmin is based on “Rolling bearing engineering”
Journal of the Bearing Engineering Editorial Committee: Yokendo July 10, 1975
First edition issued Cheng's formula shown in p178
Was used. In addition, the surface roughness of the bearing
Since uniform roughness is used, Λ = hmin / 1.15 (σ
12²+ Σ_c ²)^1/2Λ was calculated using the equation. Table 2 shows the experimental results. Examples 1 to 10
In all, 10 out of 10 reached 1500 hr
No peeling was observed. This is shown in FIG.
As described above, peeling frequently occurs even in a region where Δ is 3 or less.
The surface of the fixed wheel that is
Generated electromotive force is easily discharged or comes into contact with metal
Energized in the inner and outer rings to suppress the generation of hydrogen
It is considered that the life was extended. Another slip occurred
If the surface roughness is set as in the present invention,
Control becomes easier, and the slip rate decreases.
You. [Table 2]In Examples 11 and 12, Λ was small.
It becomes easier to come into contact with metal because of
2/10 pieces, peel off on outer ring surface in about 1400 hours
I was terrified. Observation of the outer ring raceway surface where peeling occurred
As a result, the polished eyes have disappeared slightly, and traces of metal contact can be confirmed.
Came. However, the peeling life of Comparative Examples 1 to 10 described later.
Life is longer, about 2 to 10 times compared to life
You. On the other hand, Comparative Examples 1 to 3 have a normal ball axis.
Normal or super-finished surface roughness level of the receiving raceway surface
However, the oil film parameter Λ is improved and metal contact is suppressed.
It is considered to control. However, engine replacement
High temperature and high vibration act as typified by machine bearings
Under the environment, slip and metal contact are likely to occur,
By simply improving the surface roughness, as shown in FIG.
In addition, several kV of friction generated between belt and pulley
You can hardly expect to easily discharge static electricity,
Therefore, early peeling cannot be prevented. That
As a result, Comparative Examples 1 to 3 were 228, 234, and 37, respectively.
At 8 hours, peeling occurs at 1/4 or less of the calculated life. In Comparative Example 4, only the fixed wheel was used.
"Condition 1" is satisfied, but PCD is low.
In addition, since Λ is smaller than 1, metal contact
In the whole area, surface origin peeling occurred on the outer ring in 439 hours
I was born. For Comparative Examples 5 and 6, the fixed wheel
Test 10 because the surface roughness is 0.10 μm Ra or more
Of the individual vibrations, 8,10 each, more than 5 times the initial vibration
The test has stopped. Investigation of bearings stopped due to large vibration
As a result, the surface roughness was extremely deteriorated. [0030] As is clear from the above description, the present invention
According to the grease lubrication between the fixed wheel and the rotating wheel
Rolling bearing smell used by arranging multiple rolling elements
And the center line average roughness R of the raceway surface of the fixed wheel₁To R₁= 0.0
3 to 0.09 μm Ra;₁And PCD
Has the following relationship to suppress slip and
Of several kV generated by friction between belt and pulley
Easily discharges or conducts static electricity.
Rolling in width can extend the life. 1.0 × 10
^-3≤R₁/PCD≦3.0×10^-3 The most suitable specification is a fixed wheel raceway surface.
Centerline roughness σ₁= 0.03-0.08 μmRa, rotation
The center line roughness of the raceway₂= 0.03-0.04 μm
Ra and 1.0 × 10^-3≤R₁/ PCD ≦
3.0 × 10^-3By further setting the range,
Life can be extended.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view schematically showing a part of a rolling bearing to which the present invention is applied. FIG. 2 is a graph showing experimental data of a relationship between roughness of a fixed wheel and electric resistance in a rolling bearing. FIG. 3 is an operation view of a grease additive reservoir in a fixed ring raceway surface groove according to the embodiment of the present invention. FIG. 4 is an operation diagram of a grease additive reservoir in a conventional fixed wheel raceway surface groove shown for comparison with the present invention. [Description of Signs] 1 Rolling bearing 2 Outer ring 3 Inner ring 4 Rolling element 5 Cage 6 Seal 7 Rotating shaft 8 Housing 9 Grease 10 Fixed ring raceway surface 11 Rotating wheel raceway surface

Claims (1)

Claims: 1. A rolling bearing having a plurality of rolling elements disposed between a fixed shaft to be grease-lubricated and a rotating wheel, the track surface center line average roughness R ₁ of the fixed wheel being used. For R ₁ = 0.
And 03～0.09MyumRa, and said _{R 1} and PCD
Has the following relationship: 1.0 × 10 ⁻³ ≦ R ₁ /PCD≦3.0×10 ⁻³