JPH09210055A - Cylindrical roller bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylindrical roller bearing which suppresses revolution slide of a roller by giving the minimum required axial pre-load properly without relying on trial and error. SOLUTION: Axial load Fa having the following relationship is given to a roller 3 of a radial cylindrical roller bearing through a collar 5 to suppress slide between the roller 3 and races (outer ring 1, inner ring 2). Fc.Z/Fa<= 0.70 in the case of pre-load between an inner ring collar and an outer ring collar, and Fc.Z/Fa<=1.0 in the case of pre-load between the inner ring collar or the outer ring collar, wherein Fc is revolution centrifugal force of the roller, m is mass of the roller, dm is diameter of roller pitch circle, and Wt is roller revolution angle speed, and Fc has the relationship, Fc=m.1/2.dm.Wt<2> . Z is the number of rollers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a cylindrical roller bearing, and more particularly, to prevent damage to a raceway surface due to revolving sliding of rollers.

[0002]

2. Description of the Related Art Conventionally, cylindrical roller bearings have been widely used under various conditions from low load to high load. Recently, however, the speed of rolling bearings has been increasing, and the wear phenomenon and damage accompanying it have become new problems. In particular, in the case of a cylindrical roller bearing used under conditions of high speed rotation and low load, such as a main shaft of a jet engine or a gas turbine engine, a roller and an inner ring (in inner ring rotation) or an outer ring (outer ring rotation) The rotation driving force between the rollers is not sufficiently applied, and the rolling resistance of the rollers cannot be overcome. When such a large slip occurs, there is a possibility that the raceway surface of the bearing ring may be damaged with a white alteration layer, which is called skidding damage, or thermal damage, which is called smearing. In general, smearing is easy on large or very large bearings such as those used in steel.

Therefore, in order to suppress such orbital slip of the roller, it has been conventionally practiced to apply an axial preload to the cylindrical roller bearing via the flange of the cylindrical roller bearing.

[0004]

However, since the conditions and mechanism of occurrence of skidding damage or smearing damage have not been clarified yet, even if axial preload is applied through the collar,
I didn't know the proper value, so I had to repeat trial and error.

The present invention provides a cylindrical roller bearing which can appropriately apply a minimum required axial preload without repeating such trial and error.

[0006]

In the cylindrical roller bearing according to the present invention, an axial load Fa having the following relationship is applied to the roller of the radial cylindrical roller bearing through a collar to cause a slip between the roller and the bearing ring. It was suppressed. In case of preload between inner ring collar and outer ring collar, Fc · Z / Fa
≦ 0.70 Fc · Z / Fa for inner ring collar or outer ring collar preload
≦ 1.0 where Fc is the revolving centrifugal force of the roller, and Fc = between the roller mass m, the roller pitch circle diameter dm, and the roller revolution angular velocity ω _c.
It has a relationship of m · 1/2 · dm · ω _c ² .

Z is the number of rollers. According to the cylindrical roller bearing of the present invention, an appropriate axial load is determined in advance in accordance with the rotational speed of the cylindrical roller bearing, and the roller is preloaded via the collar. Therefore, a minimum required axial preload is applied to the cylindrical roller bearing. It is possible. Therefore, it is possible to suppress slipping even under use conditions of high speed rotation and low load, and eventually prevent damage such as skidding and smearing.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a cylindrical roller bearing, and FIG. 2 is a partial view thereof as viewed from the arrow II, in which 1 is an outer ring, 2 is a collared inner ring, 3 is a roller, and 4 is a cage. As described above, in most cases, damage caused by sliding such as skidding damage and smearing damage of the cylindrical roller bearing (hereinafter referred to as sliding damage) is accompanied by the revolution slip of the roller 3. Normal,
The roller 3 pushes the cage 4 while revolving, and the pushing force causes the cage 4 to rotate in synchronization with the revolution of the roller 3. However, when the rollers 3 revolve, the rotational speed of the cage 4 deviates from the geometrical rotational speed. When the roller 3 pushes the retainer 4 with a smaller force as in the case of inner ring rotation, the number of revolutions of the retainer is delayed.

FIG. 3 shows the state of the force applied to the rollers 3 and the cage 4 in the load range when the outer ring rotates. In the symbols in FIG. 3, F _ca is the force with which the roller 3 pushes the cage 4, and F _so is the roller 3 receives from the raceway of the outer ring 1 (between the roller and the outer ring raceway).
The sliding frictional force, F _si represents the sliding frictional force that the roller 3 receives from the raceway surface of the inner ring 2 (between the roller and the inner ring raceway surface), and F _d represents the rotational resistance (drag force) by the lubricant.

The following equation (1) is established from the relationship of the balance of the forces in the circumferential direction of the rollers. F _ca = F _so −F _si + F _d (1) That is, the force F _ca that the roller 3 pushes the cage 4 is determined by the sliding friction between the inner and outer rings (race rings) and the resistance of the lubricant. Next, the same thing as above will be considered for the non-loaded zone.

Since the roller 3 and the inner ring 2 do not come into contact with each other in the non-loaded area, the sliding frictional force F _si between the roller and the inner ring raceway surface is zero, so the force F _ca that the roller 3 pushes the cage 4 is F _ca. = F _so + F _d (2) That is, all the non-loaded zones rollers push the cage 4 to increase the cage rotation speed. As the load applied to the bearing becomes smaller, the number of non-loaded bearing rollers increases, and as a result, the rotation speed of the cage 4 increases (however, in the case of outer ring rotation, the reverse is true of inner ring rotation).

Therefore, if the force F _ca for pushing the cage 4 by the non-loaded zone roller is reduced, it is possible to prevent the revolution number of the cage 4 from changing and to prevent slip damage. Therefore, as a means of reducing the F _ca, the axial load as preload the time through the flange of the bearing ring and the load, a direction opposite to the sliding friction force F _so between rollers - the outer ring raceway surface by contact between the roller and the collar _Shall produce a sliding friction force of F _sfi .

In order to simplify the problem, consider the case where the bearing load does not act at all. At this time, the force acting on the roller 3 can be modeled as shown in FIG. 4 according to the preload type (in the case of preload between inner ring flanges). FIG.
In the cylindrical roller bearing shown in FIG. 1, when the “inner ring collar load (axial load) Fa” is applied as a preload to both sides of the roller via the collar 5 to the unloaded spherical roller 3 (one row) in outer ring rotation. Is shown.

The symbol Z in FIG. 4 is the number of rollers (for one row). The symbol Fc is the revolution centrifugal force [kgf] of the roller 3 (and its reaction received from the outer ring raceway surface) and is represented as follows. Fc = mc × rc × ωc ² where mc is the roller mass [kgf · sec ² / mm].

Rc is the roller revolution radius [mm]. ωc is around
At revolution angular velocity [rad / sec], ωc = 1/2 (1-da / dm) ω_i＋1/2 (1 ＋ da / dm) ω_o Or ωc = π / Roller revolution speed / 30 where da: Roller diameter [mm] dm: Roller pitch circle diameter [mm] ω_i: Inner ring angular velocity [rad / sec] ω_o: Outer ring angular velocity [rad / sec] In this case, the roller 3 comes into contact with the inner ring collar 5 (Fig. 1).
So sliding friction force F_sfiHas occurred. This sliding friction force F
_sfiIs a sliding frictional force F between the roller and the outer ring raceway surface. _soWhat is
Opposite, and therefore axial in the unload zone
Force F that roller 3 pushes cage 4 under load_caIs F_ca= F_so+ F_d-2F_sfi ... (2 '). Sliding friction force F_sfiIs the inner ring on both sides
By contact with the brims 5 and 5. Where the rollers hold
Force F to push the vessel_caIf ≦ 0, the roller 3 is pushed by the cage 4.
On the contrary, F_caIf ≧ 0, the roller 3 should push the cage 4.
Means As described above, the revolution number variation of the cage 4
To prevent slipping and eliminate slip damage
Force F to push the container 4_caF should be reduced because F_ca≤0
Therefore, F_so+ F_d-2F_sfi≤ 0 (3) (However, with outer ring rotation and inner ring double collars) bearing slip
It is a condition for preventing damage.

Assuming that the friction coefficient between the roller rolling surface and the outer ring raceway surface is μ ₀ and the friction coefficient between the roller end surface and the inner ring collar surface is μ _fi , F _so = μ ₀ F _c (4 ) F _sfi = μ _fi F _a / Z (5). By substituting these (4) and (5) into the above equation (3) and rearranging, the following can be expressed.

Μ ₀ F _c + F _d −2 μ _fi F _a / Z ≦ 0 (6) Therefore, F _c (μ ₀ + F _d / F _c ) ≦ 2 μ _fi F _a / Z, that is, F _c · Z / F _a ≦ 2 μ _fi / (μ ₀ + F _d / F _c ) ≡K _ii (7) When the right side of the equation (7) is considered to be a substantially constant value, the following equation (8) is obtained.

F _a ≧ F _c · Z / K _ii (8) Although the above is the case of [preload between inner ring collars], the case of preload between outer ring collars can be treated in substantially the same way. On the other hand, when the preload type is [preload between inner ring collar and outer ring collar], it is modeled as shown in FIG. in this case,
Since the sliding frictional force F _sfo due to the contact between the roller 3 and the outer ring brim is added to the factor, the conditional expression for preventing the sliding damage of the bearing is as follows.

F _so + F _sfo + F _d −F _sfi ≦ 0 (9) Now, if the friction coefficient between the roller end face and the outer ring flange face is μ _fo , then F _sfo = μ _fo F _a / Z (10) It becomes a relationship. By substituting the equations (4), (5) and (10) into (9) and rearranging, the following can be expressed.

F _c · Z / F _a ≦ (μ _fi −μ _fo ) / (μ ₀ + F _d / F _c ) ≡K _io (11) When the right side of the equation (11) is considered to be a substantially constant value, The following formula (12) is obtained. F _a ≧ F _c · Z / K _io (12) It should be noted that although all of the above are for the outer ring rotation, the same K _ii , K _io are also for the inner ring rotation.

Appropriate values of K _ii and K _io (roller centrifugal force /
The value of the preload ratio) can be experimentally obtained as follows. That is, a preload test is performed on the cylindrical roller bearing in the roller axis direction, and "the appropriate K _ii and K _io values that do not cause slippage are roughly estimated from the test data. Thereafter, based on the K _ii and K _io values, (8) or (12), to easily calculate the axial preload force F _a time of the minimum required to be loaded by the flange may be set to a cylindrical roller bearing.

Below, the roller centrifugal force / preload ratio K _ii , K _io
Describe the contents of the test to determine. The test bearing specifications are as follows. Bearing type: Double-row cylindrical roller bearing Bearing inner diameter: 400mm Bearing outer diameter: 573mm Bearing pitch diameter: 457mm Number of rollers: 36 / row Roller diameter: 30mm Roller weight: 0.364kg Roller pitch circle diameter: 457mm Test condition Outer ring Rotation speed: 140-830 rpm Inner ring is stationary Roller axial preload: 2-25 KN Roller preload method: Inner ring collar preload and inner ring collar-outer ring collar preload test method When the outer ring rotation speed of the bearing under test is 140 rpm The axial preload (axial load) was gradually increased from 0 to 25 KN, and the roller revolution speed was measured. Next, the same test was performed by setting the outer ring rotation speed to 370 rpm. A series of tests are 140 rpm of outer ring, 370r
It carried out in order of pm, 600 rpm, and 830 rpm.

Next, the roller revolving centrifugal force F _c where axial preload force Fa and the relation _{F c · Z / F a ≡K} ii ...... (7) F c · Z / F a ≡K io ...... ( 11), the roller revolution centrifugal force F _c / roller axial preload ratio K _ii ,
The K _io was calculated and the relationship with the roller revolution slip ratio S _C was plotted. The roller revolution slip ratio S _C (%) is The case where the measured roller revolution speed approaches the outer ring rotation speed is defined as positive, and the case where it approaches the inner ring rotation speed is defined as negative.

FIG. 6 is a diagram plotting the relationship between the roller revolution slip ratio S _{C and the} revolution centrifugal force / roller preload ratio K _ii when preloading between the inner ring collars. FIG. 7 is a graph plotting the relationship between the roller revolution slip ratio S _{C and the} revolution centrifugal force / roller preload ratio K _io during preload between the inner ring collar and the outer ring collar. 6 and 7, in order to suppress the roller revolution slip ratio S _C to approximately 0%, in the case of inner ring collar preload, K _ii ≡F _c ·
Z / F _a ≒ 0.4, in the case of pre-load between the inner flange-outer flange, may be be set _{K io ≡F c · Z / F} a ≒ 0.2 and comprising as roller axial preload force Fa I understand.

However, it is generally said that slip damage occurs when the roller revolution slip ratio S _C is 50% or more (for example,
"Lubrication" Vol. 24, No. 11 (1979) 725-72
(See Fig. 7 "Skidding damage occurrence limit" in "Rolling bearing wear"). In the present invention, the roller revolution slip ratio S _C 25% is defined as the upper limit at which slip damage occurs, and the roller revolution centrifugal force / roller preload ratios K _ii and K _io are set as follows in view of a margin. It was

Inner ring brim preload (or outer ring brim preload)
6 in the case of K _ii ≡F _c · Z / F _a ≦ 1.0 In the case of preload between the inner ring collar and the outer ring collar, in the case of FIG. 7, K _io ≡F _c · Z / F _a ≦ 0.7 From (8) or (12) based on the K _ii and K _io values of, the required minimum roller axial preload F _a to be loaded can be calculated in accordance with the number of revolutions of the roller revolution. Thus, an appropriate roller axial preload (axial load) Fa that does not cause slippage can be easily set in the cylindrical roller bearing without trial and error.

[0027]

As described above, in the cylindrical roller bearing according to the present invention, when the axial preload is applied through the collar in order to suppress the revolution slip of the roller, the magnitude of the preload value Fa is In case of preload between inner ring collar and outer ring collar, Fa ≧ (rotational centrifugal force of roller × number of rollers) /0.7, and in case of inner ring flange or outer ring collar preload Fa ≧ (revolutionary centrifugal force of roller × number of rollers) It may be set as /1.0. Therefore, it is no longer necessary to repeat trial and error to find an appropriate axial preload value as in the past, and it is possible to easily apply the minimum required axial preload and efficiently under high-speed rotation and low load use conditions. This has the effect of suppressing slippage and preventing damage such as skidding and smearing.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a cylindrical roller bearing according to the present invention.

FIG. 2 is a partial external view showing an arrow II in FIG.

FIG. 3 is a schematic diagram showing a state of a force applied to a roller and a cage within a load zone when an outer ring rotates.

FIG. 4 (a) is a perspective view showing a state of a force acting on a roller in the case of preload between inner ring flanges of a cylindrical roller bearing, and FIG. 4 (b) is a roller and a cage in a non-loaded range in the case of outer ring rotation. It is a schematic diagram which shows a mode of the force applied to.

FIG. 5 is a perspective view showing a state of a force acting on the roller in the case of preload between the inner ring flange and the outer ring flange of the cylindrical roller bearing.

[Fig. 6] Roller revolution slip ratio S _{c in} the case of inner ring collar preload
And a roller centrifugal force / preload ratio K _ii are plotted.

FIG. 7 is a graph plotting the relationship between the roller revolution slip ratio S _c and the roller centrifugal force / preload ratio K _{io in} the case of preload between the inner ring collar and the outer ring collar.

[Explanation of symbols]

 1 Outer ring 2 Inner ring 3 Roller 4 Cage 5 Inner ring brim

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideo Fujiwara 1-5-50 Shinmei Kugenuma, Fujisawa-shi, Kanagawa NSK Ltd.

Claims (1)

[Claims] 1. A cylindrical roller bearing in which a radial cylindrical roller bearing is provided with an axial load Fa having the following relationship via a collar to suppress slippage between the roller and the bearing ring. In case of preload between inner ring collar and outer ring collar, Fc · Z / Fa
≦ 0.70 Fc · Z / Fa for inner ring collar or outer ring collar preload
≦ 1.0 where Fc is the revolving centrifugal force of the roller, and Fc = between the roller mass m, the roller pitch circle diameter dm, and the roller revolution angular velocity ω _c.
It has a relationship of m · 1/2 · dm · ω _c ² . Z is the number of rollers.