JP2003322155A - Rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling bearing capable of certainly preventing skidding damage even if slips frequently occur because of high-speed rotation and a service in a light-load environment and also reducing a manufacturing cost and simplifying a manufacturing process. <P>SOLUTION: A three-point contacting ball bearing 2 is used in which each ball 8 is held in such a way as contacting at one point with a raceway groove 4a of an outer ring 4 and at one point each of raceway grooves 6a and 7a of an inner rings 6 and 7. Phosphorus-based reforming films are formed on surfaces of the balls 8, the raceway surface 4a of the outer ring 4, and raceway surfaces 6a and 7a of the inner rings 6 and 7. The ball bearing 2 is used in high-speed rotation and in a light-load environment such that Pr/Cr≤0.05 and V>70 m/s, where Pr is a dynamic equation radial load, Cr is a fundamental dynamic rated load, and V is a relative slipping speed between a driving ring and the ball 8, with the driving ring being either of the inner rings 6, 7 and the outer ring 4. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing in which slip frequently occurs when used at a high speed and with a light load, and more particularly, to a main bearing of a jet engine or a gas turbine engine and an internal of those engines. -A rolling bearing suitable for an external gearbox bearing, a high-speed pinion bearing for a speed reducer, and the like.

[0002]

2. Description of the Related Art Generally, a rolling bearing having an outer ring, an inner ring and a rolling element has insufficient contact force between the rolling element and the raceways of the inner ring and the outer ring when used under a very small load (light load). Then, slippage occurs between the two. This phenomenon of slippage becomes significant during high-speed rotation, and wear called skidding damage occurs on the sliding surfaces between the rolling elements and the rolling surfaces of the inner and outer rings, significantly shortening the life of the rolling bearing. .

Particularly, a three-point contact ball bearing in which a ball is held so as to contact one raceway surface of an outer ring and an inner race at one point and to contact the other raceway surface at two points at high speed and under a light load environment When used in, the bearing has a small contact portion between the ball and the raceway surface, and the bearing immediately slips, causing skidding damage and reaching the bearing life in a short time.

As a conventional rolling bearing capable of achieving low friction against sliding, for example, at least one contact surface of an outer ring, an inner ring and a rolling element is chemically treated to form a compound reaction film layer. The formed rolling bearing is known (for example, Patent Document 1). Further, as another rolling bearing capable of achieving low friction against sliding, a metal component and a phosphorus compound, a sulfur compound, a halogen compound are provided on at least one contact surface of an outer ring, an inner ring and a rolling element made of metal. A compound or an organic metal compound alone or a combination reaction film layer with a combination of these compounds is formed, and at least one of an organic phosphorus compound, an organic sulfur compound, an organic halogen compound and an organic metal compound is used as an extreme pressure component. Rolling bearings in which an added lubricant is allowed to exist between the metal contact surfaces of the transmission member are also known (for example, Patent Document 2).

However, the rolling bearings of the above-mentioned Patent Documents 1 and 2 have not been subjected to any verification as to the state in which slipping is likely to occur frequently when they are used at high speed and with a light load, and there is no skiding damage. There is a problem in terms of bearing life due to the occurrence of. Here, as a rolling bearing capable of reliably preventing skidding damage, the rolling element is made of ceramic (for example, Patent Document 3), and in a bearing having a "roller" rolling element, the raceway surface of the outer ring is elliptical. There is known a rolling bearing (for example, Patent Document 4) in which a "roller" is preloaded to prevent slippage by forming a triangle or a triangle.

[0006]

[Patent Document 1] JP-A-9-133130

[Patent Document 2] Japanese Patent Laid-Open No. 10-96428

[Patent Document 3] Japanese Patent Laid-Open No. 3-199715

[Patent Document 4] JP-A-7-27134

[0007]

However, the rolling bearings of Patent Documents 3 and 4 have problems such as an increase in manufacturing cost and a complicated manufacturing process. The present invention has been made in view of the above circumstances, and it is possible to reliably prevent skidding damage even if slipping frequently occurs due to being used in a high-speed rotation and light load environment. At the same time, it is an object of the present invention to provide a rolling bearing capable of reducing the manufacturing cost and simplifying the manufacturing process.

[0008]

In order to solve the above-mentioned problems, the invention of claim 1 is provided with an outer ring, an inner ring, rolling elements and the like formed of bearing steel, and is used at a high speed and under a light load. In the bearing, a phosphorus-based modified film is provided on at least one surface of the rolling element surface and the raceways of the outer ring and the inner ring on which the rolling element rolls.

According to a second aspect of the present invention, in the rolling bearing according to the first aspect, the rolling element is a ball, and the ball comes into contact with one raceway surface of the outer ring and the inner ring at one point, It is a three-point contact type ball bearing that is held in contact with the other raceway surface at two points. The invention of claim 3 is the rolling bearing according to claim 1 or 2, wherein the dynamic equivalent radial load is Pr and the basic dynamic load rating is Cr, and it is used at a light load of Pr / Cr ≤ 0.05. It is characterized by doing.

According to a fourth aspect of the present invention, in the rolling bearing according to the first or second aspect, one of the inner ring and the outer ring is a drive wheel, and a relative sliding speed between the drive wheel and the rolling element is V. , V> 70 m / s for high speed rotation. Further, the invention according to claim 5 is the rolling bearing according to claim 1 or 2, wherein the dynamic equivalent radial load is Pr, the basic dynamic load rating is Cr, and one of the inner ring and the outer ring is a drive wheel. And the relative sliding speed of the rolling element is V, Pr / Cr ≤
It is characterized by being used at a high speed and with a light load at 0.05 and V> 70 m / s.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a rolling ball bearing according to the present invention will be described below with reference to the drawings. Figure 1
It shows a main part of the three-point contact ball bearing 2 of the first embodiment. The three-point contact ball bearing 2 of the present embodiment is arranged coaxially with an outer ring 4 made of bearing steel and inside the outer ring 4.
Inner rings 6 and 7, a large number of balls 8 formed of bearing steel held between the outer ring 4 and the inner rings 6 and 7, and each ball 8
And a cage 10 made of bearing steel that holds the sheet at predetermined intervals. The outer race 4 is formed with a raceway groove 4a having an arc-shaped cross section with a radius R0. The two inner rings 6 and 7 are formed with raceway grooves 6a and 7a each having a Gothic arc sectional shape.

The ball 8 is a sphere having a diameter D, contacts the raceway groove 4a of the outer ring 4 at one point, and races 6 of the inner rings 6 and 7.
a and 7a are in contact with each other at one point and are held between the outer ring 4 and the inner rings 6 and 7. A phosphorus-based modified film is provided on the surfaces of the outer ring 4, the inner rings 6, 7 and the balls 8 of the three-point contact ball bearing 2. As shown in FIG. 2, the phosphorus-based modified film is thermally decomposed on the oxygen compound layer formed on the surface of the bearing material (outer ring 4, inner ring 6, 7, and ball 8) and on the oxygen compound layer. It is composed of the formed phosphorus compound layer,
The oxygen compound layer is a metal element (for example, iron) of the bearing material.
And a reaction layer containing oxygen as a main component and having baking resistance, and the phosphorus compound layer is a layer containing a metal element (for example, iron) of the bearing material, oxygen and phosphorus as main components.

Bearing material (outer ring 4, inner ring 6, 7 and ball 8)
The oxygen compound layer formed on the surface of the layer prevents the deterioration of the surface roughness of the bearing material due to the reaction when the phosphorus compound layer formed on the layer is thermally decomposed and reacts with the surface of the bearing material. Has a function of strengthening the adhesion between the formed phosphorus compound layer and the surface of the bearing material. That is, by providing the phosphorus-based modified film on the surfaces of the outer ring 4, the inner rings 6, 7 and the balls 8, the surface of the balls 8, the surface of the raceway groove 4a of the outer ring 4 and the raceway grooves 6a, 7a of the inner rings 6, 7 are formed. The surface roughness is not deteriorated, and the bond between these surfaces and the phosphorus compound layer formed through the oxygen compound layer becomes strong, and a surface effective for low friction is obtained.

FIG. 3 shows an example in which the thickness of the phosphorus compound layer and the oxygen compound layer formed on the bearing material was measured using tricresyl phosphite as the phosphorus compound. The depth profile of the sample was taken by AES (Auger electron spectroscopy analyzer) and the film thickness was obtained from the etching time by sputtering using a SiO2 substrate. The photoelectron intensities of phosphorus (P) and oxygen (O) in the compound layer The thickness of each layer is determined from the value of the sputtering time immediately before the change in the value of .DELTA.

Next, a skidding test of the three-point contact ball bearing 2 of the first embodiment shown in FIGS. 1 to 3 was conducted. The test bearing has an inner diameter Din = 60 mm and an outer diameter Dout = 110 m
Two types of bearings with m and width H = 25 mm were used. The bearing material of these test bearings is M for the inner rings 6, 7, outer ring 4, and balls 8.
50 materials were used.

Then, one of the test bearings was immersed in petroleum benzine for ultrasonic cleaning and then dried at room temperature while being careful not to leave oil. Next, the bearing was heated in the atmosphere to form an oxygen compound layer on the bearing surface. afterwards,
These test bearings were prepared by treating a synthetic hydrocarbon oil (polyα-olefin) containing 3% by weight of trioctyl phosphate with 4% by weight of PAN (phenyl-α-naphthylamine) as an antioxidant. By immersing, a phosphorus compound layer was formed on the oxygen compound layer to provide a phosphorus-based modified film. The other test bearing was a bearing not provided with a phosphorus-based modified film.

As described above, for the two types of test bearings, that is, the test bearing provided with the phosphorus-based modified film and the test bearing not provided with the phosphorus-based modified film, the inner rings 6 and 7 serve as driving wheels and rotate at high speed ( 40, 000 rpm), and the skid test was conducted over 200 hours with the axial load set to a very small value so that the revolution slip ratio of the ball 8 was the highest.

FIG. 4 is a diagram showing the characteristics of the orbital slip of the ball 8 with respect to the change of the axial load when the inner rings 6, 7 are rotated at a high speed of 40,000 rpm. The axial load of the ball 8 becomes 300 kgf or more. When the orbital slip is small and the axial load becomes a light load of 200 kgf or less, the orbital slip of the ball 8 gradually increases. Then, when the axial load is 20 kgf, the orbital slip ratio of the ball 8 is highest (77%).

Here, assuming that the dynamic equivalent radial load of the test bearing is Pr, the radial load coefficient is X, the axial load coefficient is Y, the radial load is Fr, and the axial load is Fa, Pr = X · Fr + Y · Fa ... The relational expression of (1) is obtained. By setting the axial load Fa of the test bearing to 20 kgf, the dynamic equivalent radial load Pr and the basic dynamic load rating of the test bearing are indicated by Cr, and the degree of load of the test bearing is Pr / Cr = 0.003 ... The light load is (2).

Since the orbital slip ratio of the ball 8 is 77%, the relative slip velocity V between the ball 8 and the inner ring 6 is a high speed rotation of V = 115 m / s (3) In this way, the relative slip velocity V between the ball 8 and the inner rings 6, 7 is set to V = 115 m / s for high-speed rotation, and Pr
Two types of test bearings, a test bearing provided with a phosphorus-based modified film and a test bearing not provided with a phosphorus-based modified film, were used under test conditions with a light load such that / Cr = 0.003.
The results of the skidding test performed during the time are shown in FIG. The test bearing provided with the phosphorus-based modified film is used for high-speed rotation and with a light load, and even if slip frequently occurs, as shown in FIG. Groove 6
No skidding damage has occurred on a and 7a over the entire circumference. This is because the inner ring is
The surface roughness of the orbital grooves 6a, 7a of No. 7 is not deteriorated, and the bond between these surfaces and the phosphorus compound layer formed through the oxygen compound layer becomes strong, and the surface effective for abrasion resistance is Obtained balls 8 and raceways 6a, 7a of inner rings 6, 7
Since the abrasion with and is reduced, skidding damage does not occur. On the other hand, the test bearing not provided with the phosphorus-based modified film has the ball 8 as shown in FIG.
Since the friction between the inner races 6 and 7 and the raceway grooves 6a and 7a is not reduced, a part of the inner races 6 and 7 in the circumferential direction suffers skidding damage.

Further, since it is possible to surely prevent the skidding damage only by providing the phosphorus-based modified film on the surfaces of the outer ring 4, the inner rings 6, 7 and the balls 8, it is possible to prevent the skidding damage from the conventional measures. Compared with the method in which the rolling elements (balls) are made of ceramic, or the bearing surface of the rolling elements is "rollers", the raceway of the outer ring is elliptical or triangular and preload is applied to the "rollers" to prevent slippage. It is possible to reduce the manufacturing cost and simplify the manufacturing process.

Next, FIG. 6 shows a main part of the three-point contact ball bearing 20 of the second embodiment, which is mainly used as a main bearing of an aircraft engine. Similarly to the first embodiment, the three-point contact ball bearing 20 of the present embodiment also has an outer ring 24 formed of bearing steel, two inner rings 26 and 27 coaxially arranged inside the outer ring 24, and an outer ring. 24 and inner rings 26, 27
A large number of balls 28 made of bearing steel held between
And a cage 30 made of bearing steel that holds each ball 28 at a predetermined interval. The outer race 24 is formed with a raceway groove 24a having an arc-shaped cross section with a predetermined radius. The two inner rings 26, 27 are formed with raceway grooves 26a, 27a having a Gothic arc sectional shape. The ball 28 is a sphere and is in contact with the raceway groove 24a of the outer ring 24 at one point, and the raceway grooves 26a, 2 of the inner rings 26, 27 are contacted with each other.
The outer ring 24 and the inner rings 26, 27 are in contact with each other at one point with respect to 7a.
Is held between.

The phosphorus-based modified film is also provided on the surfaces of the outer ring 24, the inner rings 26, 27, and the balls 28 of the three-point contact ball bearing 20 as in the first embodiment. 3 shown in FIG.
A skidding test of the point contact ball bearing 20 was conducted. The test bearing has an inner diameter Din = 220mm and an outer diameter Dout = 330m.
Two types of bearings with m and width H = 55 mm were used. The bearing materials of these test bearings are M5 for the inner rings 26 and 27 and the outer ring 24.
It is a 0NiL material, and the ball 28 is an M50 material.

Then, the skid test is conducted without providing the phosphorus-based modified film on one of the test bearings and the phosphorus-based modified film on the other test bearing. Here, ball 28 and inner ring 26,
By setting the relative slip velocity V of 27 to V = 87 m / s high-speed rotation, the rotation to 10,000 rpm high-speed rotation, and the axial load to 260 kgf, Pr / Cr =
Under a test condition of a light load of 0.01, a skidding test was performed for 200 hours on two types of test bearings, a test bearing provided with a phosphorus-based modified film and a test bearing not provided with a phosphorus-based modified film. .

After the test, the inner rings 26 of the two types of test bearings,
Visual inspection of the raceway grooves 26a, 27a of No. 27 shows that the test bearing provided with the phosphorus-based modified film has no skidding damage in the raceway grooves 26a, 27a over the entire circumference. Also, the test bearing without the phosphorus-based modified film is
It was found that the orbital grooves 26a and 27a of Nos. 6 and 27 were partially damaged in the circumferential direction by skidding.

In each of the above-described embodiments, the case where the phosphorus-based modified film of the present invention is formed on all of the constituent parts of the rolling bearing has been described. However, the present invention is not limited to this, and the rolling bearing It also includes the case where the phosphorus compound layer and the oxygen compound layer of the present invention are formed in at least one of the raceway grooves and balls of the outer ring and the inner ring. Further, in each of the embodiments, the rolling bearing having one outer ring and two inner rings has been described. However, even if the rolling bearing has two outer rings and one inner ring, the same effect can be obtained. Can play.

[0027]

As described above, according to the rolling bearing of the present invention, the phosphorus-based modified film is formed on at least one surface of the rolling elements and the raceways of the outer ring and the inner ring on which the rolling elements roll. By providing them, those surfaces become effective surfaces for abrasion resistance, so even if slipping occurs frequently due to use of the environment at high speed and light load, the surface of the rolling element and this rolling element are It is possible to reliably prevent skidding damage to the raceways of the rolling outer ring and inner ring, and at the same time, reduce manufacturing cost and simplify the manufacturing process.

[Brief description of drawings]

FIG. 1 is a diagram showing a main part of a three-point contact ball bearing according to a first embodiment of the present invention.

FIG. 2 is a model diagram for explaining a phosphorus-based modified film according to the present invention.

FIG. 3 is a diagram showing a depth profile of the phosphorus-based modified film formed on the rolling bearing of the present invention measured by an Auger electron spectroscopy analyzer.

FIG. 4 is a diagram showing the characteristics of the revolution slip of the rolling elements with respect to the change of the axial load when the rolling bearing of the first embodiment according to the present invention is rotating at a high speed.

FIG. 5 is a diagram showing the results of performing a skidding test for 200 hours on a test bearing provided with a phosphorus-based modified film and a test bearing not provided with a phosphorus-based modified film.

FIG. 6 is a diagram showing a main part of a three-point contact ball bearing according to a second embodiment of the present invention.

[Explanation of symbols]

23-point contact ball bearing 4 outer ring 4a Raceway groove (raceway surface) 6,7 inner ring 6a, 7a Raceway groove (raceway surface) 8 balls 20 3-point contact ball bearing 24 outer ring 24a Raceway groove (raceway surface) 26,27 inner ring 26a, 27a Raceway groove (raceway surface) 28 balls

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hisashi Kawamura             1-5-50 Kumei, Kugenuma, Fujisawa-shi, Kanagawa             Within NSK Ltd. F term (reference) 3J101 AA03 AA04 AA32 AA42 AA54                       AA62 BA10 BA70 DA05 EA78                       EA80 FA35 FA44 GA11 GA26                 4K044 AA02 AB10 BA12 BA19 BB01                       BB03 BC01 CA53 CA62

Claims (5)

[Claims] 1. A rolling bearing comprising an outer ring, an inner ring, rolling elements, etc. formed of bearing steel, which is used at high speed and with a light load, the surface of the rolling element, the outer ring on which the rolling element rolls, and At least one surface of the raceway of the inner ring,
A rolling bearing having a phosphorus-based modified film. 2. The rolling element is a ball, and the ball is held in contact with one raceway surface of the outer ring and the inner race at one point and is held in contact with the other raceway surface at two points. The rolling bearing according to claim 1, wherein the rolling bearing is a contact type ball bearing. 3. The rolling bearing according to claim 1, wherein the rolling bearing is used at a light load of Pr / Cr ≦ 0.05, where Pr is a dynamic equivalent radial load and Cr is a basic dynamic load rating. 4. One of the inner wheel and the outer wheel is a driving wheel,
When the relative slip speed between the drive wheel and the rolling element is V,
The rolling bearing according to claim 1 or 2, which is used at a high speed of V> 70 m / s. 5. When Pr is a dynamic equivalent radial load, Cr is a basic dynamic load rating, and one of the inner wheel and the outer wheel is a driving wheel and a relative sliding speed between the driving wheel and the rolling element is V, Pr / Cr The rolling bearing according to claim 1 or 2, wherein the rolling bearing is used at a high speed and a light load, with ≦ 0.05 and V> 70 m / s.