JP2021162026A - Rolling bearing - Google Patents

Abstract

To provide a rolling bearing that can reduce contact noise and an acoustic pressure value by reducing energy when a retainer comes into contact with a bearing ring.SOLUTION: A rolling bearing includes: a pair of bearing rings; rolling elements interposed between raceway surfaces of the pair of bearing rings; and a retainer for holding the rolling elements between the pair of bearing rings. A step surface for forming a large interval dimension between the step surface and the retainer is provided at a surface at which a raceway surface of at least one of the pair of bearing rings is provided.SELECTED DRAWING: Figure 1

Description

The present invention relates to rolling bearings.

A CT scanner (CT scanner device) of a medical device has an inspection unit (gantry unit), and an X-ray tube, a detector, and the like for taking an image are installed in a rotating portion. As the bearing for supporting the rotating portion, for example, a bearing having a large diameter of about 1 m (bearing for rotating support: bearing for gantry) is used.

Bearings for gantry are required to be fast and quiet. That is, by increasing the speed, the imaging time can be shortened and the burden on the patient can be reduced. In addition, by reducing the noise of the gantry bearing, it is possible to alleviate the patient's anxiety during imaging and at the same time prevent the atrophy of the organs.

Since the bearing for gantry rotates while supporting the base to which the imaging device such as the X-ray tube or the detector is attached, a moment load acts on the bearing. Therefore, 4-point contact ball bearings are used. That is, in the conventional four-point contact ball bearing, as shown in FIG. 11, the rolling elements 5 interposed between the pair of raceway rings 1 and 2 and the raceway surfaces 3 and 4 of the pair of raceway rings 1 and 2. And a cage 6 for holding the rolling element 5 between the pair of raceway wheels 1 and 2. Further, seal members 7 (7a, 7b) are arranged at the openings at both ends of the bearing.

That is, the raceway surface 3 is provided at the center of the inner diameter surface of the raceway ring 1 as the outer ring in the bearing axial direction, and the mounting grooves 8a and 8b are provided on the end side of the inner diameter surface of the raceway ring 1 in the bearing axial direction. The outer peripheral portions of the seal members 7a and 7b are mounted on the mounting grooves 8a and 8b, respectively. Further, a raceway surface 4 is provided at the center of the outer diameter surface of the raceway ring 2 as an inner ring in the bearing axial direction, and notches 9a and 9b are provided at the bearing axial end portion of the outer diameter surface of the raceway ring 2. There is. Then, the inner peripheral portions of the seal members 7a and 7b are loosely fitted to the cutout portions 9a and 9b.

By the way, bearings for CT scanner devices are required to be quiet, and there are demands such as a sound pressure value (for example, 70 dBA or less at a position 1 m from the center of rotation) and no jarring noise. However, the bearing for the CT scanner device is a thin-walled type and has a structure in which the rigidity of the cage is difficult to obtain, and the cage bends and comes into contact with the inner and outer rings, and abnormal noise is likely to occur.

Even if the cage is a rolling element guide, the advance / delay of the ball may occur depending on the usage conditions, and the thin-walled type cage is deformed due to the advance / delay. As a result, the cage and the raceway ring come into contact with each other to generate an abnormal noise. Bearings for CT scanner devices are required to reduce the acoustic level during rotation of the bearings in order to reduce the mental burden on the patient.

Therefore, conventionally, there are bearings for the purpose of lowering the acoustic level during rotation of the bearing (Patent Document 1 and Patent Document 2). That is, the bearings described in Patent Document 1 and Patent Document 2 have a cushioning member installed on at least one of the outer peripheral surface and the inner peripheral surface of the cage. As a result, even if the cage hits the outer ring or the inner ring, the contact noise is reduced by the buffering action of the buffer member, and the acoustic level at the time of bearing rotation is reduced.

Further, conventionally, it has been proposed that a grease storage member for preventing the outflow of grease to the outside is provided so that the internal grease can be stably supplied to the rolling groove for a long period of time to prevent the generation of abnormal noise. (Patent Document 3).

JP-A-2007-78057 JP-A-2007-78056 Japanese Unexamined Patent Publication No. 2005-155877

In Patent Document 1 and Patent Document 2, it is necessary to install a cushioning member on at least one of the outer peripheral surface and the inner peripheral surface of the cage, which increases the number of parts and requires mounting work of the cushioning member. Therefore, the assembly time of this bearing becomes long and the productivity is inferior. Further, although the O-ring is used as the cushioning member in the embodiment, when the O-ring is used, it is necessary to provide a groove for fitting the O-ring, which causes groove processing and deteriorates productivity.

In Patent Document 3, it is necessary to provide grease storage grooves on both sides of the rolling groove of the outer ring and to fix the grease storage members to both ends of the inner diameter surface of the outer ring. Therefore, the productivity is inferior and the production cost is high.

Therefore, in view of the above problems, the present invention provides a rolling bearing capable of reducing the energy when the cage and the raceway ring come into contact with each other to reduce the contact noise and the sound pressure value. be.

One rolling bearing of the present invention includes a pair of raceway wheels, a rolling element interposed between the raceway surfaces of the pair of raceway rings, and a cage for holding the rolling element between the pair of raceway wheels. It is a rolling bearing, and is provided with a stepped surface having a large dimension between it and a cage on the surface on which the raceway surface of at least one of the pair of raceway rings is provided.

According to one rolling bearing of the present invention, the contact area between the cage and the raceway ring can be reduced, and the generation of contact noise can be suppressed. Moreover, it is not necessary to use a cushioning member or the like which is a separate member.

In the one rolling bearing, when the wall thickness dimension of the cage is set to α1 and the contact width between the cage and the raceway ring is set to α2 when the stepped surface is not provided, the stepped surface is provided. It is preferable that the contact width α3 between the cage and the raceway ring is 0.3α2 or more and the step dimension α4 of the step surface is 0.25α1 or less. Further, when considering the stability when the cage contacts the raceway ring and the reduction of the contact noise due to the deflection and inclination of the cage, the contact width is 0.3α2 and the step size is close to 0.25α1. Is more preferable. If the contact width between the cage and the raceway ring is less than 0.3α2, the guidance may become unstable when the cage comes into contact with the raceway ring. When the step size is larger than 0.25α1, the processing man-hours increase. Further, it is not preferable because the required amount of grease to be sealed becomes larger.

Another rolling bearing of the present invention includes a pair of raceway wheels, a rolling element interposed between the raceway surfaces of the pair of raceway rings, and a cage for holding the rolling element between the pair of raceway wheels. It is a rolling bearing, and is provided with a stepped surface having a large dimension between the raceway wheels on at least one of the pair of raceway ring facing surfaces of the cage.

Even with the other rolling bearings of the present invention, the contact area between the cage and the raceway ring can be reduced, and the generation of contact noise can be suppressed. Moreover, it is not necessary to use a cushioning member or the like which is a separate member.

In the other rolling bearing of the present invention, when the wall thickness dimension of the cage is α1 and the contact width of the cage with the raceway ring is α2, the length of the stepped surface on the cage side in the bearing axial direction is 0. It is preferable that the step size is 7α2 or less and the step size of the stepped surface is 0.2α1 or less. If the bearing axial length of the stepped surface exceeds 0.7α2 or the stepped dimension of the stepped surface exceeds 0.2α1, the rigidity and strength of the cage may be significantly lowered.

The rolling bearing is preferably a 4-point contact ball bearing. Therefore, this rolling bearing is most suitable for a gantry that receives a moment load.

In the present invention, since the contact area between the cage and the raceway ring can be reduced, the energy when the cage and the raceway ring come into contact with each other is reduced to reduce the contact sound and the sound pressure value. be able to. As a result, the rolling bearing becomes a bearing having more required functions (high speed and quietness) of the gantry bearing. Moreover, the number of parts does not increase as compared with the conventional one, which does not cause a decrease in assembling property and a high cost.

It is sectional drawing of the main part of the 1st rolling bearing which concerns on this invention. It is an enlarged sectional view of the main part of the rolling bearing of FIG. It is a development plan view of a cage. It is sectional drawing of the main part of the 2nd rolling bearing which concerns on this invention. FIG. 6 is an enlarged cross-sectional view of a main part of the rolling bearing of FIG. It is sectional drawing of the main part of the 3rd rolling bearing which concerns on this invention. FIG. 6 is an enlarged cross-sectional view of a main part of the rolling bearing of FIG. It is sectional drawing of the main part of the 4th rolling bearing which concerns on this invention. FIG. 8 is an enlarged cross-sectional view of a main part of the rolling bearing of FIG. It is a simplified sectional view of the CT scanner device. It is an enlarged sectional view of the main part of the conventional rolling bearing.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 10. FIG. 1 is a rolling bearing (gantry bearing) used in a CT scanner device (see FIG. 10). In the CT scanner device, the X-rays generated by the X-ray tube device 70 are applied to the subject 76 through the wedge filter 72 that makes the intensity distribution uniform and the slit 74 that limits the intensity distribution. The X-rays that have passed through the subject 76 are received by the detector 78, converted into an electric signal, and sent to a computer (not shown). Each component such as the X-ray tube device 70, the wedge filter 72, the slit 74, and the detector 78 is rotated in a substantially cylindrical shape rotatably supported by the fixed pedestal 82 via a bearing 80 (rolling bearing according to the present invention). It is attached to the gantry 84 and rotates around the subject 76 as the rotating gantry 84 rotates. Then, the X-ray tube device 70 and the detector 78 facing each other rotate around the subject 76 to obtain projection data covering all angles at every point in the inspection cross section of the subject 76, and from these data, the projection data is obtained. A tomographic image is obtained by a pre-programmed reconstruction program.

In the CT scanner device, in order to make the inner peripheral surface of the fixed pedestal 82 a large diameter of about 1 m in diameter so that the subject 76 can enter, the rolling bearing 80 between the fixed pedestal 82 and the rotating pedestal 84 has a diameter. On the other hand, so-called ultra-thin large rolling bearings with a remarkably small cross section are used.

The rolling bearing (gantry bearing) 80 includes a pair of raceway rings 11 and 12, a rolling element 15 interposed between the raceway surfaces 13 and 14 of the pair of raceway wheels 11 and 12, and a pair of raceway wheels 11, A cage 16 for holding the rolling element 15 between the 12 is provided. Further, seal members 17 (17a, 17b) are arranged at the openings at both ends of the bearing.

That is, the raceway surface 13 is provided at the center of the inner diameter surface of the raceway ring 11 as the outer ring in the bearing axial direction, and the mounting grooves 18a and 18b are provided on the end side of the inner diameter surface of the raceway ring 11 in the bearing axial direction. The outer peripheral portions of the seal members 17a and 17b are mounted on the mounting grooves 18a and 18b, respectively. Further, a raceway surface 14 is provided at the center of the outer diameter surface of the raceway ring 12 as an inner ring in the bearing axial direction, and notches 19a and 19b are provided at the bearing axial end portion of the outer diameter surface of the raceway ring 12. There is. Then, the inner peripheral portions of the seal members 17a and 17b are loosely fitted to the cutout portions 19a and 19b.

In order to cope with a moment load or the like, a four-point contact ball bearing having a contact angle α between the rolling element 15, the inner ring (race wheel) 12 and the outer ring (race wheel) 11 is used.

The cage 16 is made of a resin material. The resin cage 16 is a split type in which a plurality of resin segments 20 (injection molded products) having an arc-shaped cross section are connected in the circumferential direction to form an annular shape. As shown in FIG. 3, the concave or convex fitting portions 22a and 22b formed at both ends of each segment 20 are fitted to the convex or concave fitting portions 22b and 22a at the end of the segment to be coupled. By engaging with each other in the circumferential direction, the segments 20 are joined to form an annular cage 16. The segment 20 of the illustrated example is provided between the base portion 21 having an arc shape in which the annular body is divided at a plurality of points in the circumferential direction, the pillar portion 22 extending in one axial direction from the base portion 21, and the adjacent pillar portions 22. It is provided with a plurality of pockets 23a and 23b.

The pockets 23a and 23b in the illustrated example have two types of shapes. One of them is a first pocket 23a having a holding function and an equal distribution function of the rolling element 15, and since the pocket opening width of this pocket 23a is smaller than the diameter of the rolling element 15, the pocket of the rolling element 15 The protrusion to the opening side is restricted, and the rolling element 15 is held in the pocket 23a. The other is a second pocket 23b having only the equal distribution function of the rolling element 15, and in this pocket 23b, since the pocket opening width is larger than the diameter of the rolling element 15, the rolling element 15 can freely move in the axial direction. .. Therefore, the second pocket 23b does not have a holding function like the first pocket 23a, but only has a function of equally arranging the rolling elements 15. In each segment 20, these two types of pockets 23a and 23b are alternately formed in the circumferential direction.

The rolling element 15 is accommodated in the pockets 23a and 23b by pushing the rolling element 15 from the opening of the pockets 23a and 23b toward the back of the pocket. At this time, in the first pocket 23a, it is necessary to push in the rolling element 15 while expanding the pillar portion 22 on the entrance side, but in the second pocket 23b, such time and effort is not required, so that the rolling element 15 is transferred to the cage 16. The process of incorporating the moving body 15 can be simplified. The shapes and structures of the pockets 23a and 23b described above are merely examples, and pockets having various shapes and structures can be used depending on the bearing usage conditions and the like, for example, the pockets have a single shape.

In this bearing, stepped surfaces 25 and 25 having a large dimension between the cage 16 and the cage 16 are provided on the surface of the raceway ring 12, which is the inner ring, on which the raceway surface 14 is provided (that is, the outer diameter surface of the inner ring). In this case, when the wall thickness dimension of the cage 16 is α1 and the contact width between the cage 16 and the raceway ring 11 (12) is α2 when the step surface 25 is not provided, the step surface 25 is set. It is preferable that the contact width α3 between the cage 16 and the raceway ring 12 is 0.3α2 or more and the step dimension α4 of the step surface is 0.25α1 or less. Further, when considering the stability when the cage contacts the raceway ring and the reduction of the contact noise due to the deflection and inclination of the cage, the contact width is 0.3α2 and the step size is close to 0.25α1. Is more preferable. If the contact width between the cage and the raceway ring is less than 0.3α2, the guidance may become unstable when the cage comes into contact with the raceway ring. When the step size is larger than 0.25α1, the processing man-hours increase. Further, it is not preferable because the required amount of grease to be sealed becomes larger.

With this bearing, the contact area between the cage 16 and the raceway ring 12 can be reduced, and the generation of contact noise can be suppressed. Moreover, it is not necessary to use a cushioning member or the like which is a separate member. That is, since the contact area between the cage 16 and the raceway ring 12 can be reduced, the energy when the cage 16 and the raceway ring 12 come into contact with each other is reduced, so that the contact sound is reduced and the sound pressure value is reduced. Can be planned. As a result, the rolling bearing becomes a bearing having more required functions (high speed and quietness) of the gantry bearing. Moreover, the number of parts does not increase as compared with the conventional one, which does not cause a decrease in assembling property and a high cost.

In the rolling bearings shown in FIGS. 4 and 5, step surfaces 26, 26 are provided on the raceway ring 11 side, which is the outer ring, that is, the surface (that is, the outer ring) on which the raceway surface 13 of the raceway ring 11 is provided. The inner diameter surface) is provided with stepped surfaces 26, 26 having a large dimension between the cage 16 and the cage 16. Also in this case, when the wall thickness dimension of the cage 16 is α1 and the contact width between the cage 16 and the raceway ring 11 (12) is α2 when the step surface 26 is not provided, the step surface 26 is also defined. The contact width α3 between the cage 16 and the raceway ring 11 is set to 0.3α2 or more, and the step dimension α4 of the step surfaces 26 and 26 is set to 0.25α1 or less. Since the other configurations of the rolling bearings shown in FIGS. 4 and 5 are the same as those of the bearings shown in FIGS. 1 and 2, they are designated by the same reference numerals as those given in FIGS. 1 and 2. Therefore, the description will be omitted.

Therefore, the rolling bearings shown in FIGS. 4 and 5 have the same effects as those of the rolling bearings shown in FIGS. 1 and 2.

By the way, when the contact area between the raceway ring 11 (12) and the cage 16 is reduced, a stepped surface is provided on the raceway ring 11 (12) side as shown in FIGS. 1 and 2 and 4 and 5. It is preferable to secure the rigidity of the cage 16. However, if the driving wheel 11 (12) cannot be scraped to provide the stepped surface, the cage 16 side may be scraped to provide the stepped surface.

In the bearings shown in FIGS. 6 and 7, a step surface 27 is provided on the cage side. That is, a stepped surface 27 having a large dimension between the raceway rings is provided on the inner ring facing surface (opposing surface of the raceway ring 12) of the cage 16. In this case, when the wall thickness dimension of the cage 16 is α1 and the contact width of the cage 16 with the raceway ring 11 (12) is α2, the bearing axial length α35 of the stepped surface 27 is 0.7α2 or less. The step dimension α4 of the step surface 27 is set to 0.2α1 or less. If the bearing axial length α5 of the stepped surface 27 exceeds 0.7α2 or the stepped dimension α4 of the stepped surface 17 exceeds 0.2α1, the rigidity and strength of the cage 16 may be significantly lowered.

Further, in the bearings shown in FIGS. 8 and 9, a stepped surface 28 having a large dimension between the raceway rings is provided on the outer ring facing surface (opposing surface of the raceway ring 11) of the cage 16. In this case, when the wall thickness dimension of the cage 16 is α1 and the contact width of the cage 16 with the raceway ring 11 (12) is α2, the bearing axial length α5 of the stepped surface 28 is 0.7 α2 or less. The step dimension α4 of the step surface 28 is set to 0.2α1 or less.

As described above, even if the stepped surfaces 27 and 28 are provided on the cage side, the contact area between the cage 16 and the raceway wheels 12 and 11 can be reduced, and the generation of contact noise can be suppressed. Moreover, it is not necessary to use a cushioning member or the like which is a separate member. That is, it is possible to obtain the same effect as that of the rolling bearings shown in FIGS. 1 and 2.

Although the embodiment of the present invention has been described above, the present invention is not limited to the embodiment, and various modifications can be made. In the bearings shown in FIGS. 1 and 2, the stepped surface 25 is on the inner ring 12 side. In the bearings shown in FIGS. 4 and 5, the stepped surface 26 was provided on the outer ring 11 side, but in the bearings shown in FIGS. 1 and 2, even if the stepped surface 26 is provided on the outer ring 11 side, FIG. In the bearing shown in FIG. 5, a stepped surface 25 may be provided on the inner ring 12 side. Further, when the stepped surface 27 (28) is provided on the cage 16 side, it may be provided on the inner ring side and the outer ring side. By the way, as shown in FIGS. 1 and 4, when the step surfaces 25 and 26 are provided on the raceway rings 12 and 11, a pair of stepped surfaces 25 and 26 are provided symmetrically with respect to the raceway surfaces. This is provided in pairs symmetrically in order to reduce assembly mistakes when the raceway wheels 12 and 11 are cut, but a stepped surface 25 (26) may be provided in only one of them.

11 Orbital ring (outer ring)
12 Orbital ring (inner ring)
13,14 Orbital plane 15 Rolling element 16 Cage 25, 26, 27, 28 Stepped plane

Claims (5)

A rolling bearing including a pair of raceway wheels, a rolling element interposed between the raceway surfaces of the pair of raceway wheels, and a cage for holding the rolling element between the pair of raceway wheels.
A rolling bearing characterized in that a stepped surface having a large dimension between the bearing and the bearing is provided on the surface of at least one of the pair of bearing wheels on which the raceway surface is provided. When the wall thickness dimension of the cage is α1 and the contact width between the cage and the raceway ring is α2 when the stepped surface is not provided, the cage and the raceway ring are provided by providing the stepped surface. The rolling bearing according to claim 1, wherein the contact width of the bearing is 0.3α2 or more and the step dimension of the stepped surface is 0.25α1 or less. A rolling bearing including a pair of raceway wheels, a rolling element interposed between the raceway surfaces of the pair of raceway wheels, and a cage for holding the rolling element between the pair of raceway wheels.
A rolling bearing characterized in that a stepped surface having a large dimension between the raceway wheels is provided on at least one of the pair of raceway ring facing surfaces of the cage. When the wall thickness dimension of the cage is α1, the wall thickness dimension of the cage is α1, and the contact width of the cage with the raceway ring is α2, the length of the stepped surface on the cage side in the bearing axial direction is set. The rolling bearing according to claim 3, wherein the step size of the step surface is 0.7 α2 or less and the step size of the step surface is 0.2 α1 or less. The rolling bearing according to any one of claims 1 to 4, which is a four-point contact ball bearing.

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