JP2023168878A - tapered roller bearing - Google Patents

Abstract

To provide a tapered roller bearing capable of suppressing occurrence of seizure even under a severe use environment.SOLUTION: A tapered roller bearing 1 includes an inner ring 2, outer rings 4, 5, and a plurality of tapered rollers 7 arranged between the inner ring 2 and the outer rings 4, 5. An inside diameter of the inner ring 2 is 200 mm or less. The tapered roller bearing 1 is used under a load that is 0.2 or more times as high as a basic dynamic load rating. The inner ring 2 includes large flange surfaces 23a, 23b with which large diameter end surfaces 71a of the plurality of tapered rollers 7 are in contact. A coating film 31 is formed on the large flange surfaces 23a, 23b, and a coating film 32 is formed in a contact region with the large flange surfaces 23a, 23b of the large diameter end surface 71a. The coating films 31, 32 have Vickers hardness higher than Vickers hardness of the inner ring 2 and Vickers hardness of the tapered roller 7.SELECTED DRAWING: Figure 3

Description

The present invention relates to tapered roller bearings.

Patent Document 1 below describes a tapered roller bearing that includes an inner ring, an outer ring, and a plurality of tapered rollers arranged between the inner ring and the outer ring.

JP2021-127834A

Some tapered roller bearings are used to support the rolls of steel rolling mills. On the other hand, it is conceivable that a steel rolling mill may roll a rolled material (for example, high-strength steel, electromagnetic steel sheet, etc.) that is harder than conventionally used steel sheets. In this case, since the deformation resistance of the rolled material increases, it is necessary to increase the pressure acting on the rolled material. On the other hand, if the rolling load is simply increased, the contact pressure between the roll and the rolled material will increase, which may cause the roll to become flattened. There is a possibility that it will not be possible to manufacture the same plate material. Therefore, by reducing the diameter of the roll and reducing the contact area between the roll and the rolled material to generate a high surface pressure, it is possible to roll a hard rolled material with the same rolling load as before. Conceivable.

However, as the diameter of the rolls becomes smaller, the bearings also need to be made smaller, but as the bearings become smaller, the resistance (loading capacity) of the bearings to radial loads and axial loads decreases. Regarding radial load, as the diameter becomes smaller, the roll becomes more likely to be elastically deformed, and the radial load acting on the bearing from the roll decreases. Therefore, even if the bearing's resistance to radial load is reduced, the radial load acting on the bearing is also reduced, so that their effects cancel each other out, and as a result, the effect on the bearing is small.

On the other hand, the axial load does not change as the roll diameter becomes smaller. Therefore, when bearings are downsized, the impact of reduced resistance to axial loads can become a problem. For example, in a tapered roller bearing, an axial load may be received by the contact surface between the large diameter end surface of the tapered roller and the large flange surface of the inner ring. In this case, if a high load (contact pressure) is applied to the contact surface, the thickness of the oil film existing on the contact surface will decrease due to the increase in load, and as a result, the oil film may break easily and seize may occur. There is.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a tapered roller bearing that can suppress the occurrence of seizure even under severe usage environments.

The tapered roller bearing of the present invention is a tapered roller bearing comprising [1] an inner ring, an outer ring, and a plurality of tapered rollers disposed between the inner ring and the outer ring, wherein the inner diameter of the inner ring is , 200 mm or less, the tapered roller bearing is configured to be used under a load of 0.2 times or more of the basic dynamic load rating, and the inner ring has a diameter of 200 mm or less, and the inner ring is It has a large flange surface with which the diameter end surface contacts, and at least one of the large flange surface and the contact area with the large flange surface of the large diameter end surface has a Vickers hardness of the inner ring and a Vickers hardness of the tapered roller. A tapered roller bearing is formed with a coating that has a Vickers hardness greater than that of a tapered roller bearing.

This tapered roller bearing is used under a load of 0.2 times or more the basic dynamic load rating, for example, to support the rolls of a steel rolling mill. In addition, in this tapered roller bearing, the inner diameter of the inner ring is 200 mm or less, and as mentioned above, when used to support the rolls of a steel rolling mill, which have a smaller diameter than conventional bearings, the tapered roller bearing has a large diameter. A high load acts on the contact surface between the radial end surface and the large flange surface of the inner ring. In this way, this tapered roller bearing is used under harsh operating environments. In this respect, in this tapered roller bearing, at least one of the large flange surface of the inner ring and the contact area with the large flange surface on the large diameter end surface of the tapered roller has a Vickers hardness that is larger than the Vickers hardness of the inner ring and the Vickers hardness of the tapered roller. A hard coating is formed. Thereby, it is possible to suppress the occurrence of seizure between the large flange surface and the large diameter end surface. Therefore, with this conical rolling bearing, it is possible to suppress the occurrence of seizure even under severe usage environments.

The tapered roller bearing of the present invention may be [2] "the tapered roller bearing according to [1], wherein the coating is made of diamond-like carbon". In this case, the occurrence of image sticking can be further suppressed.

The tapered roller bearing of the present invention may be [3] "the tapered roller bearing according to [1] or [2], wherein the coating is formed over the entire surface of the large diameter end face". In this case, the occurrence of image sticking can be further suppressed.

The tapered roller bearing of the present invention comprises [4] "the tapered roller bearing according to any one of [1] to [3], wherein the coating is formed on both the large collar surface and the contact area". There may be. In this case, the occurrence of image sticking can be further suppressed.

The tapered roller bearing of the present invention comprises [5] "the tapered roller bearing according to any one of [1] to [4], which is configured to be used under an axial load greater than or equal to a radial load" It may be. In this case, seizure is likely to occur at the contact surface between the large flange surface of the inner ring and the large diameter end surface of the tapered roller, but this tapered roller bearing suppresses the occurrence of seizure even in such cases. be able to.

According to the present invention, it is possible to provide a tapered roller bearing that can suppress the occurrence of seizure even under severe usage environments.

It is a sectional view of the peripheral part of the tapered roller bearing concerning an embodiment. FIG. 2 is a cross-sectional view of a tapered roller bearing. FIG. 3 is a cross-sectional view of a portion of a tapered roller bearing.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. In the following description, the same reference numerals will be used for the same or equivalent elements, and overlapping description will be omitted.

A tapered roller bearing 1 shown in FIG. 1 is configured as a roll neck bearing that supports a neck portion N of a roll R (for example, a work roll) of a steel rolling mill. The tapered roller bearing 1 is arranged in an axle box (chock) C attached to a rolling mill main body. The tapered roller bearing 1 is a multi-row tapered roller bearing and can receive both radial load and axial load. The tapered roller bearing 1 has the function of supporting radial loads due to roll bending in the radial direction to correct the elastic deformation of the rolls and control the shape of the rolled material, and axial loads due to roll shifts and misalignment in the axial direction. This is because it is required.

As shown in FIGS. 1 and 2, the tapered roller bearing 1 includes a pair of inner rings 2, a first outer ring 4, a pair of second outer rings 5, a plurality of tapered rollers 7, and a plurality of cages 8. , and a pair of seal units 10. The tapered roller bearing 1 is configured to be plane symmetrical, for example, with respect to a plane passing through the center of the tapered roller bearing 1 in the axial direction A and perpendicular to the axial direction A (the boundary surface between the pair of inner rings 2).

The pair of inner rings 2 are arranged along the axial direction A and are in contact with each other. The inner ring 2 has a raceway surface 21 and an inner surface 22. The inner surface 22 is fitted with the neck portion N. A cylindrical intermediate seal 91 is arranged at the boundary between the inner surfaces 22 of the pair of inner rings 2, and the intermediate seal 91 seals between the inner surfaces 22. A groove 22a is formed in each inner surface 22, and the intermediate seal 91 is disposed within the groove 22a.

The inner ring 2 is provided with a large flange 23, a first small flange 24, and a second small flange 25. The large flange portion 23 has a first large flange surface 23a facing one side in the axial direction A, and a second large flange surface 23b facing the other side in the axial direction A. The first large flange surface 23a and the second large flange surface 23b are formed in an annular shape and are continuous with the raceway surface 21. A large-diameter end surface 71a of a tapered roller 7, which will be described later, comes into contact with the first large flange surface 23a and the second large flange surface 23b.

The first small flange 24 has a first small flange surface 24a, and the second small flange 25 has a second small flange surface 25a. The first small flange surface 24a and the second small flange surface 25a are formed in an annular shape and are continuous with the raceway surface 21 on the opposite side from the large flange portion 23. A small diameter end surface 72a of a tapered roller 7, which will be described later, comes into contact with the first small collar surface 24a and the second small collar surface 25a.

The inner diameter of the inner ring 2 is 200 mm or less. The inner diameter of the inner ring 2 is the distance (diameter) between the inner surfaces 22 when viewed from the axial direction A. The inner diameter of the inner ring 2 may be 150 mm or less, or may be 100 mm or less.

The pair of second outer rings 5 are arranged to sandwich the first outer ring 4 in the axial direction A. The first outer ring 4 faces the central portion of the pair of inner rings 2 in the radial direction. The second outer ring 5 faces the end portions of the pair of inner rings 2 in the radial direction.

The first outer ring 4 has a raceway surface 41 and an outer surface 42. The second outer ring 5 has a raceway surface 51 and an outer surface 52. The outer surfaces 42 and 52 are fitted with the inner surface Ca (FIG. 1) of the axle box C. A cylindrical spacer 92 is interposed between the first outer ring 4 and the second outer ring 5. A groove 52a is formed in the outer surface 52, and an annular O-ring 94 is disposed in the groove 52a. The O-ring 94 seals between the outer surface 52 and the inner surface Ca of the axle box C.

The plural tapered rollers 7 include a plurality of first tapered rollers 7A and a plurality of second tapered rollers 7B. The first tapered roller 7A is arranged between the raceway surface 21 of the inner ring 2 and the raceway surface 51 of the second outer ring 5. The first tapered roller 7A comes into rolling contact with the raceway surfaces 21 and 51 on its outer circumferential surface (rolling surface) during rolling. The second tapered roller 7B is arranged between the raceway surface 21 of the inner ring 2 and the raceway surface 41 of the first outer ring 4. The second tapered roller 7B comes into rolling contact with the raceway surfaces 21 and 41 on its outer circumferential surface (rolling surface) during rolling. The plurality of tapered rollers 7 are arranged in a plurality of rows (four rows in this example).

Each tapered roller 7 is formed into a conical shape (truncated cone shape), and has a head portion 71 on the large diameter side and a tail portion 72 on the small diameter side. The end face of the tapered roller 7 on the head 71 side is a circular large diameter end face 71a, and the end face of the tapered roller 7 on the tail part 72 side is a circular small diameter end face 72a. The diameter of the large diameter end surface 71a is larger than the diameter of the small diameter end surface 72a.

The first tapered roller 7A is arranged so that the large diameter end face 71a faces the center side in the axial direction A, and the second tapered roller 7B is arranged so that the large diameter end face 71a faces the end side in the axial direction A. It is located. The plurality of first tapered rollers 7A and the plurality of second tapered rollers 7B are held by the retainer 8 so as to be rotatable at a constant interval between the raceway surface 21 and the raceway surface 41 or the raceway surface 51. There is.

During rolling, the large diameter end surface 71a of each first tapered roller 7A comes into sliding contact with the first large flange surface 23a of the inner ring 2, and the small diameter end surface 72a of each first tapered roller 7A contacts the first small flange surface 24a of the inner ring 2. sliding contact. Further, the large diameter end surface 71a of each second tapered roller 7B slides on the second large flange surface 23b of the inner ring 2, and the small diameter end surface 72a of each second tapered roller 7B slides on the second small flange surface 25a of the inner ring 2. Contact. The axial load acting on the tapered roller bearing 1 is mainly received by the contact surfaces between the large diameter end surface 71a and the first large flange surface 23a and the second large flange surface 23b.

A pair of seal units 10 are respectively attached to both ends of the second outer ring 5 in the axial direction A, and seal between the inner ring 2 and the second outer ring 5. As shown in FIGS. 2 and 3, the seal unit 10 includes a shield member 11 and a contact member 12 attached to the shield member 11. The shield member 11 is formed in an annular shape from a metal material such as steel, and includes a bottom wall portion 13, an inner wall portion 14, and an outer wall portion 15. The shield member 11 is fixed to the end of the second outer ring 5 by fitting the outer wall portion 15 to the inner surface 53 of the second outer ring 5 . The contact member 12 is formed in an annular shape from an elastic material such as rubber. The contact member 12 is fixed to the shield member 11 by fitting into the inner wall portion 14 of the shield member 11. The tip of the contact member 12 is in contact with the outer surface 27 of the inner ring 2 .

The tapered roller bearing 1 is installed in an axle box so that it is used under a load of 0.2 times or more the basic dynamic load rating (Cr). That is, the tapered roller bearing 1 is configured to be used under such a load. When used to support the roll R in a steel rolling mill, an extremely large load of 0.2 times or more of the basic dynamic load rating acts on the tapered roller bearing 1 (bender load of the steel rolling mill). The basic dynamic load rating is a fixed load that is set so that the bearing can withstand a basic rating life (90% life) of one million revolutions. Further, the tapered roller bearing 1 is configured to be used while receiving an axial load greater than a radial load. That is, the axial load that acts on the tapered roller bearing 1 during use is greater than the radial load that acts on the tapered roller bearing 1 during use. The tapered roller bearing 1 may be configured to be used under a load of 0.3 times or more, 0.4 times or more, or 0.5 times or more of the basic dynamic load rating.

In the tapered roller bearing 1, a coating 31 is formed on the first large flange surface 23a and the second large flange surface 23b of each inner ring 2. Further, a coating 32 is formed on the large diameter end surface 71a of each tapered roller 7. In this example, the coating 31 is formed over the entire first large flange surface 23a and the entire second large flange surface 23b, and the coating 32 is formed over the entire large diameter end surface 71a. No coating is formed on the small-diameter end surface 72a of the tapered roller 7, and on the first small flange surface 24a and the second small flange surface 25a of the inner ring 2. In the tapered roller bearing 1, the large diameter end surface 71a comes into sliding contact with the first large flange surface 23a or the second large flange surface 23b via the coating 31 and the coating 32.

The coatings 31 and 32 are hard coatings having a Vickers hardness greater than that of the inner ring 2 and the tapered roller 7. Vickers hardness can be measured, for example, by a Vickers hardness test defined by JIS standards (JIS Z 2244-1:2020, JIS Z 2244-2:2020). The coatings 31 and 32 are made of, for example, a non-metallic material. In this example, the coatings 31 and 32 are hard carbon films made of diamond-like carbon, and have a Vickers hardness of about 3000 HV. As an example, when the material of the inner ring 2 is carburized carbon steel, the Vickers hardness of the inner ring 2 is, for example, about 650HV to 750HV, and when the material of the tapered rollers 7 is carburized carbon steel, the Vickers hardness of the tapered rollers 7 is about 650HV to 750HV. is, for example, about 670HV to 770HV. The coatings 31 and 32 are interposed between the first large flange surface 23a or the second large flange surface 23b and the large diameter end surface 71a, and are interposed between the first large flange surface 23a or the second large flange surface 23b and the large diameter end surface 71a. suppress metal contact between The coatings 31 and 32 have a function of suppressing friction (wear) at the contact surface between the first large flange surface 23a or the second large flange surface 23b and the large diameter end surface 71a. The coatings 31 and 32 are not limited to diamond-like carbon, and may be made of, for example, chromium plating. In this case, the Vickers hardness of the coatings 31 and 32 is, for example, about 700 HV to 1000 HV. The coatings 31 and 32 may be composed of different types of coatings.
[Action and effect]

The tapered roller bearing 1 is used under a load of 0.2 times or more the basic dynamic load rating, for example, in order to support the rolls of a steel rolling mill. In addition, in the tapered roller bearing 1, the inner diameter of the inner ring 2 is 200 mm or less, and as described above, when used to support the rolls of a steel rolling mill, which have a smaller diameter than conventional bearings, the tapered roller 7 A high load acts on the contact surface between the large diameter end surface 71a of the inner ring 2 and the large collar surfaces 23a and 23b of the inner ring 2. In this way, the tapered roller bearing 1 is used under harsh operating environments. In this regard, in the tapered roller bearing 1, the coating 31 is formed on the first large flange surface 23a and the second large flange surface 23b of the inner ring 2, and the coating 32 is formed on the large diameter end surface 71a of the tapered roller 7. There is. The coatings 31 and 32 have a Vickers hardness greater than that of the inner ring 2 and the tapered roller 7. Thereby, it is possible to suppress the occurrence of seizure between the large flange surfaces 23a, 23b and the large diameter end surface 71a. Therefore, according to the tapered roller bearing 1, the axial resistance performance can be improved, and the occurrence of seizure can be suppressed even under severe usage environments.

The coatings 31 and 32 are made of diamond-like carbon. Thereby, the occurrence of image sticking can be further suppressed.

A coating 32 is formed over the entire large diameter end surface 71a. Thereby, the occurrence of image sticking can be further suppressed.

Coatings 31 and 32 are formed on the large collar surfaces 23a and 23b and the large diameter end surface 71a, respectively. Thereby, the occurrence of image sticking can be further suppressed.

The tapered roller bearing 1 is configured to be used under an axial load greater than a radial load. In this case, seizure is likely to occur at the contact surface between the first large flange surface 23a and the second large flange surface 23b of the inner ring 2 and the large diameter end surface 71a of the tapered roller 7. For example, even in such a case, the occurrence of image sticking can be suppressed.

The present invention is not limited to the above embodiments and modifications. For example, the materials and shapes of each structure are not limited to the materials and shapes described above, and various materials and shapes can be employed. Although the tapered roller bearing 1 was sealed in the above embodiment, the tapered roller bearing 1 does not have to be sealed. A lubricant (lubricating oil) may be present in the tapered roller bearing 1. If a lubricant is present, even if the coatings 31 and 32 are lost due to wear or the like, an oil film is formed in place of the coatings 31 and 32, and the large flange surfaces 23a and 23b can be protected.

In the above embodiment, the coating 32 is formed over the entire surface of the large diameter end surface 71a, but the coating 32 is formed in the contact area with the large collar surfaces 23a, 23b on the large diameter end surface 71a (the edges along the outer periphery of the large diameter end surface 71a). It may be formed only in part). In this case as well, the occurrence of burn-in can be suppressed similarly to the above embodiment. Furthermore, by reducing the area in which the coating 32 is formed, productivity can be increased and costs can be reduced. When a relief portion (recess) is formed in the center of the large-diameter end face 71a, the coating 32 may be formed only in a region of the large-diameter end face 71a where the relief portion is not formed.

In the above embodiment, the coating 31 is formed on the first large flange surface 23a and the second large flange surface 23b, and the coating 32 is formed on the large diameter end surface 71a. It is sufficient that it is formed on at least one of 23a, 23b and the large diameter end surface 71a, and may be formed only on the large collar surfaces 23a, 23b, or only on the large diameter end surface 71a. That is, one of the coatings 31 and 32 may be omitted. In this case as well, the occurrence of burn-in can be suppressed similarly to the above embodiment.

DESCRIPTION OF SYMBOLS 1... Conical roller bearing, 2... Inner ring, 4... First outer ring, 5... Second outer ring, 23a... First large flange surface, 23b... Second large flange surface, 71a... Large diameter end surface, 31... Coating, 32... Coating.

Claims (5)

Inner circle and
outer ring and
A tapered roller bearing comprising a plurality of tapered rollers arranged between the inner ring and the outer ring,
The inner diameter of the inner ring is 200 mm or less,
The tapered roller bearing is configured to be used under a load of 0.2 times or more the basic dynamic load rating,
The inner ring has a large flange surface that the large diameter end surfaces of the plurality of tapered rollers contact,
A coating having a Vickers hardness greater than the Vickers hardness of the inner ring and the tapered roller is formed on at least one of the large flange surface and a contact area with the large flange surface on the large diameter end surface. A tapered roller bearing. The tapered roller bearing according to claim 1, wherein the coating is made of diamond-like carbon. The tapered roller bearing according to claim 1 or 2, wherein the coating is formed over the entire surface of the large diameter end face. The tapered roller bearing according to claim 1 or 2, wherein the coating is formed on both the large collar surface and the contact area. The tapered roller bearing according to claim 1 or 2, which is configured to be used under an axial load greater than a radial load.

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