JP2002276652A - Cylindrical roller bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To have high loading capacity and aligning performance and hardly cause unbalance of the frictional moment balance of a roller by allowing the roller to make linear contact with a raceway. SOLUTION: This cylindrical roller bearing has the cylindrical roller 14 inserted between an inner ring 12 and an outer ring 10. The outside diameter surface 10B of the outer ring 10 is formed into a hemispherical shape having the radius larger than its distance from the bearing center, and an elastic material 30 hardly deformable compared with the outer ring is coated thereon so that the outer surface of the outer ring 10 becomes on approximately cylindrical shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical roller bearing, and more particularly, to a misalignment-permissible cylindrical roller bearing suitable for use in a part where roll deflection or misalignment during construction is a problem.

[0002]

2. Description of the Related Art As shown in FIG. 1, one of high-bearing bearings for supporting a high-load rotating body such as a rolling roll is disposed on a bearing box (not shown) below the drawing. Outer raceway 10A constituted by the inner surface of the outer race 10
A rolling element (referred to as a roller) 14 which is formed between the inner ring 12 and the rotating body (not shown) in the upper part of the figure protrudes from the track 10A. There is a so-called self-aligning roller bearing capable of performing an alignment of 0.5 ° or more within a range not to do so. In the figure, reference numeral 16 denotes a retainer for retaining the rollers 14.

As shown in FIG. 2, the center of the spherical surface of the outer raceway 10A does not coincide with the center of the shaft. However, the center of the outer raceway 10A is adjusted by the clearance between the end of the roller 14 and the raceway and the clearance of the entire bearing (automatic alignment depending on the design). Some toroidal bearings are possible. In this toroidal bearing, axial clearance is possible inside the bearing (generally, up to 10% of the bearing width).
Further, at low speeds, full-rolling without the retainer 16 is also possible.

[0004] Alternatively, as shown in FIG. 3, there is a cylindrical roller bearing with a spherical seat that can be aligned with the spherical seat 18 and the outer diameter surface 10B of the outer ring 10. The internal mechanism of the cylindrical roller bearing with a spherical seat is the same as that of a normal cylindrical roller bearing, and it is possible to escape in the axial direction inside the bearing, and it is also possible to perform full-rolling at a low speed.

As shown in FIG. 4, the spherical seat 18 and the outer ring 1 are provided.
There is also a tapered roller bearing with a spherical seat that can be aligned between the spherical surfaces of the outer diameter surface 10B. The internal mechanism of this tapered roller bearing with a spherical seat is the same as that of a normal tapered roller bearing.

[0006] Alternatively, as shown in FIG.
Bearing box (also referred to as chock) 20 having a spherical surface
There is also a bearing unit with a centering function for centering between the outer diameter surface 10B of the outer ring 10 formed into a spherical surface. The internal structure of the bearing unit with the centering function is the same as that of a normal cylindrical roller bearing or the like.

[0007]

However, in the self-aligning roller bearing shown in FIG. 1, since there is an inclined contact between the curved surfaces, a skew moment in the direction perpendicular to the paper surface always acts on the rollers 14, and Have a problem that the lubrication condition is poor and the absolute value of the frictional force is large, so that the roller skew is affected.

In the toroidal bearing shown in FIG. 2, it is necessary to incorporate the toroidal bearing offset by the amount of thermal expansion when assembling at a low temperature so that the upright position is maintained in a normal use state at a high temperature. If this is not the case, the degree of lightness is lower than that of the spherical roller bearing, but the same problem of unstable behavior is inherent.

Further, in the roller bearings with spherical seats shown in FIGS. 3 and 4, the size of the rollers 14 is reduced by the size of the spherical seats 18, so that the cage 1
In the case of 6, the load capacity is small, for example, about 20% smaller than in the case of the spherical roller bearing. Also, spherical seat 1
The problem of creep (sliding) and fretting (small moving wear) in the portion 8 is inherent.

Further, the tapered roller bearing with a spherical seat shown in FIG. 4 cannot be assembled unless it is divided, but it opens when a gap is left. Therefore, it is necessary to press the bearing with a bearing nut or bolt to fix it to the shaft. Also, there is a problem that the number of parts and the number of assembling steps are increased.

In the bearing unit with the centering function shown in FIG. 5, it is necessary to handle the bearing box 20 as a dedicated and consumable product, and to form the inner diameter of the spherical seat formed on the bearing box 20. The problem of creep and fretting on the surface 20A is inherent.

On the other hand, as similar to the present invention, Japanese Utility Model Publication No. 3-1458 has a concave portion at least on both ends of an outer peripheral surface inside a housing, and a concave portion on an inner peripheral surface at both ends from a central portion. A sliding bearing provided with a cushion material having an inclined portion for increasing the thickness of the sliding bearing has been proposed, but has not been related to a roller bearing.

[0013] Also, in the actual unexamined Japanese Utility Model Publication No. 2-16025, in a semi-floating rear axle bearing device for supporting an axle at an outer end portion of an axle tube, an elastic body is interposed between an outer peripheral surface of the outer ring and an inner peripheral surface of the axle tube. However, it did not relate to roller bearings.

The present invention has been made to solve the above-mentioned conventional problems, and has a high load capacity, an aligning property, and
An object of the present invention is to provide a misalignment-permissible cylindrical roller bearing in which the rollers and the raceway are in line contact and the friction moment balance of the rollers is less likely to be unbalanced.

[0015]

As described above, when a functional component dedicated to alignment such as a spherical seat is provided, the load capacity cannot be increased due to physical restrictions. Further, when the rollers and the inner and outer raceways come into contact between the curved surfaces as in the case of a self-aligning roller bearing or a toroidal bearing, (1) the rollers contact each other at a contact angle.
In the case where (2) the absolute value of the frictional force is large in the boundary lubrication region, (3) the oil film breaks easily due to heat generation at high speed,
The friction moment balance around the rollers is easily out of order, and the problem of skew becomes apparent.

In view of the above, as a bearing satisfying the condition that a line contact state is maintained between the rollers inside the bearing and the raceway without providing a functional component dedicated to centering such as a spherical seat, an ordinary cylindrical bore is used. A bearing that directly aligns between the bearing housing and the outer surface of the outer ring has been devised.

That is, according to the present invention, in a cylindrical roller bearing in which a cylindrical roller is inserted between an inner ring and an outer ring, at least the outer diameter surface of the end of the outer ring has a radius larger than the distance from the center of the bearing. The object has been achieved by forming a spherical surface and coating the outer diameter surface with an elastic material that is more easily deformed than the outer ring so that the outer surface of the outer ring becomes substantially cylindrical.

In this way, by increasing the thickness of the elastic material near both ends in the bearing width direction, even when a moment acts on the bearing due to misalignment or shaft deflection, the amount of displacement on the end side can be increased. By tilting the entire bearing, the moment can be absorbed.

[0019]

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

In the first embodiment of the present invention, as shown in FIG. 6, in a cylindrical roller bearing having the same outer ring 10, inner ring 12, rollers 14 and retainer 16 as in FIG. The outer diameter surface 10B is coated with a polymer elastic material 30 of, for example, fluororesin or rubber (also referred to as an elastic coating), and finally formed into a spherical shape having a radius larger than the distance from the center of the bearing. It is molded so as to have a cylindrical outer surface 30A as in the case of the above bearing. In the figure, reference numeral 20 denotes a normal bearing box having a cylindrical inner surface 20A, A denotes a surface pressure distribution between the roller and the outer ring when a force F is applied from a rotating body, and B denotes a same between the outer ring and the bearing box. It is a surface pressure distribution.

As described above, by increasing the thickness of the elastic coating 30 near both ends in the bearing width direction, even when the moment M acts on the bearing due to misalignment or shaft deflection as shown in FIG. The amount of displacement on the end side can be increased by utilizing the spring property of the bearing 30, and the moment M can be absorbed by tilting the entire bearing.

FIG. 8 shows an example of the relationship between the modulus of longitudinal elasticity and the tensile strength of various materials for selecting the elastic material 30 (source: "Plastic Data Handbook"). As the material becomes higher in strength, the modulus of longitudinal elasticity increases, and the distortion (deformation) of the material with respect to load decreases. For example, the modulus of longitudinal elasticity of common steel and fluororesin is 100 times larger, and that of rubber and fluororesin is 100 times larger. This shows that the polymer elastic material can easily release the moment acting on the entire bearing due to misalignment or bending.

When a radial load acting on a cylindrical roller bearing is considered as Fr, the maximum rolling element load Qmax under general use conditions is expressed by the following equation.

Qmax = 5 (Fr / Z) (1) where Z is the number of rollers.

If it is assumed that the roller length of this cylindrical roller bearing is equal to L, the average displacement δ between the roller and the outer ring raceway is assumed.
mean is represented by the following equation.

Δmean = 4.36 × 10 ⁻⁷ (Qmax ^0.9 / L ^0.8 ) (2)

Here, when the contacting surface pressure of the roller and the outer ring raceway becomes zero at one end due to the action of the moment, if the displacement at the other end becomes twice as large as δmean. Assuming that the increase in displacement on the side with the larger displacement can be centered on the bearing outer diameter surface, a flat contact state between the rollers and the outer ring raceway can be maintained.

Generally, the amount of displacement due to the contact between the rollers and the outer raceway is at a level of 50 μm or less, and the longitudinal elastic modulus is 100 kgf.
/ Mm ² , and a resin with an elastic limit of 1 kgf / mm ² , if this displacement is to be absorbed within the elastic range, 1% strain is 50 μm.
m, that is, 5 mm at the end where the displacement amount is large.
It is feasible if a resin having a thickness of 3 mm is coated.

As described above, by selecting the material of the resin or rubber to be coated on the outer diameter surface of the outer ring and the thickness thereof,
A bearing that absorbs misalignment and shaft deflection can be realized.

In the above-described embodiment, the elastic material 30 is coated over the entire outer diameter surface 10B of the outer race. However, as in the second embodiment shown in FIG. Coating is also possible.

The coating material is not limited to the fluororesin, and any material that is more easily deformed than metal, such as polyethylene or rubber, can be used.

[0032]

According to the present invention, even when a moment acts on the bearing due to misalignment or shaft deflection,
The displacement on the end side can be increased, and the entire bearing tilts,
It is possible to absorb the moment. Therefore, the centering can be performed directly between the bearing housing having a normal cylindrical hole and the outer diameter surface of the outer ring without providing a special functional component such as a spherical seat. Therefore, it has high load capacity and alignment,
In addition, it is possible to realize a bearing in which the rolling element and the raceway are in linear contact and the frictional moment balance of the rollers is less likely to be unbalanced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a configuration of a main part of a conventional spherical roller bearing.

FIG. 2 is a cross-sectional view showing a main configuration of the toroidal bearing.

FIG. 3 is a cross-sectional view showing a main part configuration of a cylindrical roller bearing with a spherical seat.

FIG. 4 is a sectional view showing a configuration of a main part of a tapered roller bearing with a spherical seat.

FIG. 5 is a sectional view showing a configuration of a main part of the bearing unit with the centering function.

FIG. 6 is a sectional view showing a configuration of a main part of the first embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a state in which a moment is applied.

FIG. 8 is a diagram showing an example of a relationship between elastic modulus and tensile strength of various materials for selecting an elastic material in the present invention.

FIG. 9 is a sectional view showing a configuration of a main part of a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Outer ring 10B ... Outer diameter surface 12 ... Inner ring 14 ... Rolling element (roller) 16 ... Cage 20 ... Bearing box 20A ... Inner surface 30 ... Elastic material (coating) 30A ... Outer surface

Claims (1)

[Claims] 1. A cylindrical roller bearing having a cylindrical roller inserted between an inner ring and an outer ring, wherein at least an end portion of an outer diameter surface of the outer ring is formed in a spherical shape having a radius larger than a distance from a center of the bearing. A cylindrical roller bearing, characterized in that the outer diameter surface is coated with an elastic material that is more easily deformed than the outer ring so that the outer surface of the outer ring has a substantially cylindrical shape.