JP2009293704A - Rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling bearing capable of effectively preventing seizure and damaging of a cage due to sliding contact between the cage and top foil. <P>SOLUTION: A fluid film is generated in an annular clearance G1 between an outer peripheral surface of the cage 14 and the top foil 16 of a cage support means 15 in response to rotation of the cage 14, and the rotation of the cage 14 is guided in a noncontact state to the top foil 16. When the axis of the cage 14 is inclined to the axis of an outer ring 11, an inclination of the axis of the top foil 16 is allowed in response to its inclination, and an inner peripheral surface of the top foil 16 is made to follow the outer peripheral surface of the inclined cage 14. Thus, breaking of the fluid film between the outer peripheral surface of the cage 14 and the top foil 16 is prevented. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rolling bearing used at high speed.

  For example, a rolling bearing that rotatably supports a main shaft of a machine tool is required to have a performance capable of withstanding high-speed rotation in order to improve machining performance. As a rolling bearing for high-speed rotation, there is provided a type that guides the rotation of the cage by bringing the guide surface of the cage into sliding contact with the inner peripheral surface of the raceway ring. With respect to this rolling bearing, in order to lubricate the sliding contact portion between the cage and the race, the oil supply device is used to directly inject oil air onto the guide surface of the cage or to drop the lubricating oil. (For example, refer to Patent Document 1).

In addition, as another rolling bearing for high-speed rotation, by generating dynamic pressure in the lubricating oil between the bearing ring and the cage, the holder is kept in a non-contact state with respect to the bearing ring. A rolling bearing that guides the rotation of the vessel has also been proposed (see, for example, Patent Document 2).
In this rolling bearing, a wedge-shaped space is formed between a plurality of dynamic pressure generating grooves formed on the race and the guide surface of the cage, and the cage rotates as the rolling bearing rotates at high speed. In addition, a dynamic pressure due to the so-called wedge effect is generated in the lubricating oil in each wedge-shaped space, and the cage is lifted from the raceway ring by this dynamic pressure, and the cage is maintained in a non-contact state with respect to the raceway ring. it can.

JP-A-10-292281 Japanese Utility Model Publication No. 03-11128

  Rolling bearings using the oil supply device cannot supply sufficient lubricating oil to the guide surface of the cage due to the shielding (air curtain) by the air generated by the high-speed rotation, and the cage is seized. There was a risk of damage.

In addition, the rolling bearing that lifts the cage from the raceway ring by the dynamic pressure does not cause the cage to be seized or damaged as long as the cage is maintained in a non-contact state with respect to the raceway ring. When the cage is vibrated during high-speed rotation and the axis of the cage is tilted with respect to the axis of the race, the shape of the wedge-shaped space is lost, so the wedge effect is reduced and dynamic pressure is reduced. In some cases, the raceway and the cage are in sliding contact. Therefore, there is still a risk that this type of rolling bearing will be seized or damaged.
The present invention has been made in view of such circumstances, and an object thereof is to provide a rolling bearing capable of effectively suppressing the seizure and damage of the cage.

A rolling bearing according to the present invention includes a first race ring having a first raceway surface and a first circumferential surface provided on a side of the first raceway surface, and a second raceway facing the first raceway surface. A second race ring having a surface and a second circumferential surface facing the first circumferential surface, a plurality of rolling elements interposed between the first race surface and the second race surface, A plurality of annular portions arranged between the first circumferential surface and the second circumferential surface, and a plurality of portions provided at predetermined intervals along the circumferential direction in a state of protruding in the axial direction from the side surface of the annular portion. In a rolling bearing comprising: a pillar portion; and a cage provided between the pillar portions and having a pocket for holding the rolling element,
A flexible annular top foil disposed with an annular gap along the circumferential surface of the cage; and interposed between the first circumferential surface and the top foil; A bump foil that supports the top foil in a state that allows elastic deformation in a radial direction and allows the inclination of the axis of the top foil in accordance with the inclination of the axis of the cage. It is characterized by comprising a cage guide means for generating a fluid film in the annular gap with rotation and guiding the rotation of the cage in a non-contact state with respect to the top foil.

  According to this configuration, as the cage rotates, a fluid film is generated in the annular gap between the circumferential surface of the cage and the top foil of the cage support means, and the rotation of the cage is controlled by the top foil. Can be guided in a non-contact state. For this reason, it is possible to prevent the retainer from being seized or damaged due to the strong sliding contact between the retainer and the top foil.

  Further, when the axis of the cage is inclined with respect to the axis of the raceway ring, the inclination of the axis of the top foil can be allowed according to the inclination, so the inclination of the circumferential surface of the cage On the other hand, the peripheral surface of the top foil can be imitated. For this reason, it is possible to prevent the fluid film between the circumferential surface of the cage and the top foil from being interrupted. As a result, it is possible to prevent the circumferential surface of the cage and the top foil from coming into strong sliding contact.

  According to the rolling bearing of the present invention, it is possible to effectively prevent the retainer from being seized or damaged by preventing the retainer and the top foil from slidingly contacting each other.

Next, a preferred embodiment of a rolling bearing according to the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view of a rolling bearing 1 according to an embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view taken along line AA in FIG. The rolling bearing 1 of the present embodiment is composed of an angular ball bearing and supports the rotary shaft S so as to be capable of high-speed rotation. The rolling bearing 1 is composed of an outer ring 11 as a first race ring that is a fixed ring, an inner ring 12 as a second race ring that is a rotary ring, and a ball disposed between the outer ring 11 and the inner ring 12. A plurality of rolling elements 13, a cylindrical cage 14 that holds the rolling elements 13 at predetermined intervals along the circumferential direction (in this embodiment, at regular intervals), and rotation that guides the rotation of the cage 14 Guide means 15 is provided.

A first raceway surface 11a on which the rolling element 13 rolls is formed at the axially central portion of the inner circumference of the outer ring 11, and the first raceway surface 11a is formed at both axial ends of the inner circumference. A first circumferential surface 11b having a diameter larger than the diameter is formed. The bus line of each first circumferential surface 11 b is parallel to the axis line of the outer ring 11.
The inner ring 12 is provided concentrically with the outer ring 11, and an inner peripheral surface thereof is fitted to the outer periphery of the rotation shaft S so as to be integrally rotatable. A second raceway surface 12a is formed on the outer periphery of the inner ring 12 so as to face the first raceway surface 11a, and two second circles are made to face each first circumferential surface 11b of the outer ring 11. A peripheral surface 12b is formed.

  The cage 14 has a pair of annular portions 14a that are opposed to each other while being spaced apart by a predetermined distance in the axial direction, and a predetermined interval along the circumferential direction in a state protruding from the side surface of the annular portion 14a (this In the embodiment, a plurality of pillar portions 14b provided at regular intervals) and pockets 14c that are provided between the pillar portions 14b and hold the rolling elements 13 are provided. The annular portion 14 a is disposed between the first circumferential surface 11 b of the outer ring 11 and the second circumferential surface 12 b of the inner ring 12. The pair of annular portions 14a are connected to each other by a column portion 14b.

  The rotation guide means 15 includes an annular top foil 16 and an annular bump foil 17 that elastically supports the top foil 16. These rotation guide means 15 include a first circumferential surface 11 b of the outer ring 11 and a cage. The fourteen annular portions 14a are respectively provided between the outer circumferential surface (circumferential surface) 14d.

When the rotation of the top foil 16 with respect to the outer peripheral surface 14d of the annular portion 14a of the retainer 14 is stopped, the top foil 16 is substantially free of the annular gap G1, and the outer peripheral surface 14d of the annular portion 14a and the top foil 16 As the relative rotational speed increases, the annular gap G1 of about several μm is formed (for example, when the relative rotational speed exceeds approximately 3000 min−1). Thus, the top foil 16 is provided concentrically with the annular portion 14a along the outer peripheral surface 14d. The top foil 16 has a flexibility that can be elastically deformed in the radial direction by the pressure (fluid pressure) of the air caught in the annular gap G <b> 1 as the cage 14 rotates at high speed. The top foil 16 is formed of a thin metal plate such as stainless steel, and the thickness thereof is set to, for example, about 50 to 400 μm according to the diameter and material of the top foil 16.
The top foil 16 is divided at one place on the circumference, and one end portion 16a thereof is refracted radially outward and brought into contact with the bump foil 17.

  The bump foil 17 has a first arc portion 17c fitted to the first circumferential surface 11b of the outer ring 11 and a second arc portion 17d protruding radially inward from the first arc portion 17c. It has a substantially wave shape formed alternately along the direction. The bump foil 17 is formed by press-molding a thin metal plate made of stainless steel or the like.

  The bump foil 17 supports the top foil 16 at regular intervals along the circumferential direction by inscribing the top foil 16 at the top of each second arc portion 17d. Therefore, when the fluid pressure in the annular gap G1 is not more than the steady value, the top foil 16 is allowed to be elastically deformed radially outward only between the tops of the adjacent second arc portions 17d. . The bus of the top foil 16 is parallel to the axis of the outer ring 11 when no load is applied to the top foil 16.

Each second arc portion 17d elastically supports the top foil 16, thereby allowing the axis of the top foil 16 to be inclined. That is, in each second arc portion 17d, the generatrix M passing through the top is usually parallel to the axis L1 of the outer ring 11 (see the two-dot chain line in FIG. 3), but the axis L2 of the top foil 16 is the outer ring. 11 is inclined with respect to the axis L1 of the outer ring 11 by elastically deforming following the inclination (see the solid line in FIG. 3). . The inclination of the axis L2 of the top foil 16 is such that the radial width of the annular gap G1 is narrowed when the axis L3 of the retainer 14 is inclined with respect to the axis L1 of the outer ring 11, and the fluid pressure of the annular gap G1 is reduced. It is brought about when the steady value is exceeded. In FIG. 3, the inclination of the axis L2 of the top foil 16 is exaggerated and the actual inclination is very small.
The bump foil 17 is divided at one place on the circumference, and its one end 17 a is welded to the first circumferential surface 11 b of the outer ring 11 together with the one end 16 a of the top foil 16.

  According to the rolling bearing 1 having the above configuration, when the cage 14 rotates as the inner ring 12 rotates at high speed, air is caught in the annular gap G1 between the outer peripheral surface 14d of the annular portion 14a and the top foil 16. Due to the fluid pressure, the top foil 16b tends to elastically deform radially outward. Here, the elastic deformation of the top foil 16 that is in contact with the top of the second arc portion 17d of the bump foil 17 is restricted by the second arc portion 17d. The part which is not in contact with the said top part will elastically deform radially outward. As a result, a wedge-shaped space is formed in the annular gap G1, so that a fluid film can be generated by generating a dynamic pressure in the annular gap G1. Therefore, the rotation of the retainer 14 can be guided to the top foil 16 in a non-contact state by the generated fluid film. Therefore, it is possible to prevent the retainer 14 from being seized or damaged due to the strong sliding contact between the retainer 14 and the top foil 16.

  Further, when the cage 14 vibrates, as shown in FIG. 3, when the axis L3 of the cage 14 is inclined by an angle θ with respect to the axis L1 of the outer ring 11, an annular gap G1 on the right end side in FIG. Becomes narrow and the fluid pressure in the annular gap G1 exceeds the steady value. Accordingly, the right end portion side of the second arc portion 17d of the top foil 16 and the bump foil 17 is pressed by the fluid pressure and elastically deformed radially outward. As a result, the axis of the top foil 16 can be tilted so as to follow the tilt of the cage 14. For this reason, it is possible to prevent the fluid film from being interrupted by maintaining the annular gap G1 at an appropriate gap. Therefore, even when the axis L3 of the retainer 14 is inclined with respect to the axis L1 of the outer ring 11, it is possible to prevent the outer peripheral surface 14d of the annular portion 14a of the retainer 14 and the top foil 16 from being in strong sliding contact. . Therefore, it is possible to effectively prevent the retainer 14 from being seized or damaged due to the strong sliding contact between the retainer 14 and the top foil 16.

  Further, when vibration of the cage 14 occurs during low-speed rotation at which the fluid film cannot be generated, the cage 14 may be eccentric and the outer peripheral surface 14d of the annular portion 14a may press the top foil 16. There is. In this case, however, the impact of the second arcuate portion 17d of the bump foil 17 can be reduced by the elasticity, so that the vibration of the cage 14 can be attenuated in a short time. For this reason, it is possible to prevent the cage 14 from being damaged due to repeated contact with the top foil 16.

  FIG. 4 is a cross-sectional view showing another embodiment, and FIG. 5 is an enlarged cross-sectional view taken along line BB. This embodiment is mainly different from the embodiment shown in FIG. 1 in that the first race ring which is a fixed ring is constituted by the inner ring 21 and the first raceway surface 21a is sandwiched between the outer circumference on the inner ring 21 side. A point where two first circumferential surfaces 21b are formed, a second race ring which is a rotating wheel is constituted by an outer ring 22, and the inner circumference on the outer ring 22 side is opposed to the two first circumferential surfaces 21b. In this state, the shoulder portion of the second raceway surface 22a and the point where two second circumferential surfaces 22b equal to the inner diameter of the counter bore are formed, and the rotation guide means 15 are held with each first circumferential surface 21b of the inner ring 21. It is a point arranged between the inner peripheral surface 14 e of the container 14.

  In this embodiment, the top foil 16 of the rotation guide means 15 is substantially free of the annular gap G2 when the rotation is stopped with respect to the inner peripheral surface 14e of the annular portion 14a of the cage 14, and the annular ring As the relative rotational speed between the inner peripheral surface 14e of the portion 14a and the top foil 16 increases (for example, when the relative rotational speed exceeds approximately 3000 min−1), the annular gap G2 is formed. Thus, the top foil 16 is provided along the inner peripheral surface 14e. In addition, the bump foil 17 of the rotation guide means 15 is disposed along the first circumferential surface 21b of the inner ring 21 with the top of the second arc portion 17d facing outward in the axial direction.

Also in this embodiment, a fluid film can be generated by generating a dynamic pressure in the annular gap G2 with the rotation of the cage 14, and the rotation of the cage 14 is topped by the generated fluid film. The foil 16 can be guided in a non-contact state.
When the axis of the cage 14 is tilted with respect to the axis of the inner ring 21, the fluid film in the annular gap G2 is interrupted by tilting the axis of the top foil 16 so as to follow the tilt of the cage 14. Can be prevented. Therefore, it is possible to effectively prevent the retainer 14 from being seized or damaged due to the strong contact between the retainer 14 and the top foil 16.

  The present invention is not limited to the above embodiment. For example, for the bump foil 17, an annular body obtained by cutting and raising a blade-like leaf spring elastically contacting the top foil 16 at predetermined intervals along the circumferential direction is used instead of the substantially wave-shaped one. You can also Further, for a rolling bearing using a cage in which the annular portion 14a is formed only on one side in the axial direction, such as a crown-shaped cage, the rotation guide means 15 is formed only on one side.

It is sectional drawing of the rolling bearing which concerns on one Embodiment of this invention. It is an AA arrow expanded sectional view of FIG. It is a principal part expanded sectional view for demonstrating the deformation | transformation state of bump foil. It is sectional drawing of the rolling bearing which concerns on other embodiment. It is a BB arrow expanded sectional view of FIG.

Explanation of symbols

1 Rolling bearing 11 Outer ring (first race)
11a First raceway surface 11b First circumferential surface 12 Inner ring (second raceway)
12a Second raceway surface 12b Second circumferential surface 13 Rolling element 14 Cage 14a Ring portion 14b Column portion 14c Pocket 14d Outer peripheral surface (circumferential surface) of cage
15 Rotation guide means 16 Top foil 17 Bump foil 21 Inner ring (first track ring)
21a First raceway surface 21b First circumferential surface 22 Outer ring (second raceway)
22a Second raceway surface 22b Second circumferential surface G1, G2 Annular gap

Claims (1)

A first raceway having a first raceway surface and a first circumferential surface provided on a side of the first raceway surface;
A second raceway ring having a second raceway surface facing the first raceway surface and a second circumferential surface facing the first circumferential surface;
A plurality of rolling elements interposed between the first raceway surface and the second raceway surface;
An annular portion disposed between the first circumferential surface and the second circumferential surface, and provided at predetermined intervals along the circumferential direction in a state of protruding in the axial direction from the side surface of the annular portion. A cage having a plurality of pillar portions and a pocket provided between the pillar portions and holding the rolling elements;
In a rolling bearing with
A flexible annular top foil disposed with an annular gap along the circumferential surface of the cage; and interposed between the first circumferential surface and the top foil; A bump foil that supports the top foil in a state that allows elastic deformation in the radial direction and that allows the inclination of the axis of the top foil in accordance with the inclination of the axis of the cage. A rolling bearing comprising a cage guide means for generating a fluid film in the annular gap with rotation and guiding the rotation of the cage in a non-contact state with respect to a top foil.

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