JP2007078056A - Rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce an acoustic level during the rotation of a rolling bearing. <P>SOLUTION: The rolling bearing comprises an outer ring 10 having a raceway 14 on an inner peripheral face 12, an inner ring 20 having a raceway 24 on an outer peripheral face 22, rolling elements 30 laid between the raceway 14 of the outer ring 10 and the raceway 24 of the inner ring 20, and a cage 40 for holding the rolling elements 30 between the outer ring 10 and the inner ring 20. Shock absorbing members 52, 54 are installed on at least one of the inner peripheral face 12 of the outer ring 10 and the outer peripheral face 22 of the inner ring 20 in a region of the width of the cage 40. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rolling bearing, and more specifically, can be applied to an ultra-thin and large-sized rolling bearing used for medical equipment, industrial robots, machine tools and the like.

  FIG. 2 shows an example of a CT scanner device which is a kind of medical equipment. In this CT scanner device, X-rays generated by the X-ray tube device 70 are irradiated onto a subject 76 via a wedge filter 72 for uniforming the intensity distribution and a slit 74 for limiting the intensity distribution. X-rays that have passed through the object 76 are received by a detector 78, converted into electrical signals, 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 attached to a substantially cylindrical rotary mount 84 that is rotatably supported by a fixed mount 82 via a bearing 80. With the rotation of 84, the periphery of the object 76 is rotated. Then, the X-ray tube device 70 and the detector 78 facing each other rotate around the object 76 to obtain projection data covering all angles at every point in the inspection cross section of the object 76. From these data, A tomographic image is obtained by a preprogrammed reconstruction program.

  In the CT scanner device, in order to make the inner peripheral surface of the fixed gantry 82 have a large diameter of about 1 m so that the subject 76 can enter, the bearing 80 between the fixed gantry 82 and the rotary gantry 84 has a diameter relative to the diameter. A so-called ultra-thin large-sized rolling bearing having a remarkably small cross section is used. As shown in FIG. 3A, the ultra-thin large-sized rolling bearing 80 includes a plurality of outer members 86, inner members 88, and outer members 86 and inner members 88. A rolling element 90 and a holder 92 for holding the rolling element 90 at a predetermined interval in the circumferential direction are provided.

In general, a resin segment type is used for a cage used for an ultra-thin and large-sized rolling bearing for manufacturing and assembly reasons. As shown in FIG. 3B, the segment type resin cage is configured by connecting arc-shaped segments s in the circumferential direction. Then, it is assembled to the bearing by pushing in one pocket at a time in the axial direction and incorporating rolling elements (balls). Because of such an assembling method, the basic shape is a crown type or comb type that can be inserted from the side in which the pocket is opened in the axial direction (Patent Documents 1 and 2).
JP 2004-218745 A JP 2004-162879 A

  The CT scanner device bearing is required to be quiet, and there is a demand for sound pressure value (for example, 70 dBA or less at 1 m from the rotation center) and no annoying noise. However, the CT scanner device bearing is a thin-walled type and has a configuration in which it is difficult to obtain rigidity of the cage.

  Even if the cage is a rolling element guide, a ball advance / delay occurs depending on use conditions, and the thin-wall type cage is deformed due to the advance / delay. As a result, the cage and the race are brought into contact with each other and abnormal noise is generated. The CT scanner device bearing is required to reduce the sound level when the bearing rotates in order to reduce the mental burden on the patient.

  The main object of the present invention is to reduce the sound level when the rolling bearing rotates.

  The rolling bearing according to the present invention includes an outer ring having a raceway on an inner peripheral surface, an inner ring having a raceway on an outer peripheral surface, a rolling element interposed between the raceway of the outer ring and the race of the inner ring, an outer ring and an inner ring, And a retainer for holding the rolling element between them, and a buffer member is installed in a region of the width of the retainer on at least one of the inner peripheral surface of the outer ring and the outer peripheral surface of the inner ring. To do.

  As a result, even if the cage hits the outer ring or the inner ring, the contact sound is reduced by the buffering action of the buffer member, and the sound level during rotation of the bearing is reduced. The buffer members are preferably provided on both sides in the axial direction of the track, but may be provided only on one side as long as they are within the width of the cage. If such a cushioning member is installed in the cage, the weight balance of the cage may be lost and the generation of contact noise may be promoted. However, when installed on the raceway, there is no such concern.

  According to a second aspect of the present invention, in the rolling bearing of the first aspect, the buffer member is rubber. A specific example of the rubber cushioning member is an O-ring. In that case, as is well known, an annular groove is formed in the race, and an O-ring is mounted therein. In addition to or without such a groove, the buffer member may be attached to the race by an adhesive, baking, or other similar means.

  According to a third aspect of the present invention, in the rolling bearing of the first aspect, the buffer member is a resin.

  According to this invention, even if the cage comes into contact with the raceway, the buffer member exhibits a buffering action and reduces the contact sound. Therefore, the rolling bearing according to the present invention reduces the sound level during rotation.

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

  The rolling bearing shown in FIG. 1 includes an outer ring 10 as an outer member, an inner ring 20 as an inner member, a rolling element 30 and a cage 40 as main components. The outer ring 10 is ring-shaped, and a track 14 is formed on the inner peripheral surface 12. The inner ring 20 is also ring-shaped, and a track 24 is formed on the outer peripheral surface 22. A plurality of rolling elements 30 are interposed between the track 14 of the outer ring 10 and the track 24 of the inner ring 20, and the outer ring 10 and the inner ring 20 are relatively rotatable. In addition, although the ball | bowl is illustrated as the rolling element 30 here, a roller can also be used. The cage 40 is interposed between the outer ring 10 and the inner ring 20 and holds the plurality of rolling elements 30 at predetermined intervals in the circumferential direction. Generally, a seal for sealing both ends of the bearing is attached, but the illustration is omitted here.

  Buffer members are provided on the inner peripheral surface 12 of the outer ring 10 and the outer peripheral surface 22 of the inner ring 20. Here, the case where O-rings 52 and 54 are employed as buffer members is illustrated. That is, an annular groove 16 is formed in the inner peripheral surface 12 of the outer ring 10 and an O-ring 52 is mounted therein. Further, an annular groove 26 is formed in the outer peripheral surface 22 of the inner ring 20, and an O-ring 54 is mounted therein. Here, a case where a pair of O-rings 52 and 54 are disposed with the tracks 14 and 24 interposed therebetween is illustrated. By installing the buffer member in this way, even if the retainer 40 hits the outer ring 10 or the inner ring 20, the contact sound is reduced by the buffer action of the buffer member, and the sound level at the time of bearing rotation is reduced.

  As described above, since the buffer member is for preventing or suppressing the contact between the cage 40 and the races 10 and 20 and generating a contact sound, the width of the cage 40 as viewed in the axial direction. Install in the area. The annular grooves 16 and 26 are not necessarily required. When the annular groove is provided, the groove depth and cross-sectional area, and the O-ring wire diameter and cross-sectional area are set so that the O-rings 52 and 54 partially protrude from the annular groove.

  The O-rings 52, 54 may be attached to the race rings 10, 20 by adhesive, baking, or other similar means in addition to or without the annular grooves 16, 26. In particular, the O-ring 52 installed on the inner peripheral surface 12 of the outer ring 10 needs to be prevented from being detached from the outer ring 10.

  As a material of the buffer members 52 and 54, a resin or an elastomer may be used in addition to the rubber exemplified above. For example, commercially available from NTN Corporation, a fluororesin-based sliding rubber (trade name “Bearly ER3000”) that combines rubber-specific material properties and sliding properties, low friction properties while maintaining rubber properties, low It is also possible to employ NBR-based sliding rubber (trade name “Bearly ER3201”) imparted with wear characteristics.

The rolling bearing having the above-described configuration can be applied as an ultra-thin and large-sized rolling bearing for the CT scanner apparatus already described with reference to FIG. Ultra thin large rolling bearing, and the value phi of the ratio of the diameter _{D B} and the pitch circle diameter PCD of the balls 30 0.03 (φ ₌ D B /PCD≦0.03), primarily the PCD 500mm~ A specific example of a large-diameter bearing of about 1500 mm is as follows.
D _B: 1/2 inch (12.7mm)
PCD: 1041.4mm
φ: 0.012

(A) is sectional drawing of the rolling bearing which shows embodiment of this invention, (b) is an expanded sectional view of a buffer member part Cross section of CT scanner device (A) is an enlarged view of the bearing in FIG. 2, (b) is a front view of the cage.

Explanation of symbols

10 Outer ring (outer member)
12 inner peripheral surface 14 track 16 annular groove 20 inner ring (inner member)
22 outer peripheral surface 24 track 26 annular groove 30 rolling element 40 cage 52, 54 O-ring (buffer member)

Claims (3)

  An outer ring having a track on the inner peripheral surface, an inner ring having a track on the outer peripheral surface, a rolling element interposed between the outer ring track and the inner ring track, and the rolling element is held between the outer ring and the inner ring. A rolling bearing provided with a buffer member in a region of the width of the cage, at least one of the inner circumferential surface of the outer ring and the outer circumferential surface of the inner ring.   The rolling bearing according to claim 1, wherein the buffer member is rubber.   The rolling bearing according to claim 1, wherein the buffer member is a resin.

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