JP4579123B2 - Ultra thin rolling bearing and cage for the same - Google Patents

Description

  The present invention relates to an ultra-thin type rolling bearing used for medical equipment, industrial robots, machine tools, and the like, and a cage thereof.

  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 50 are irradiated onto a subject 56 through a wedge filter 52 for uniforming the intensity distribution and a slit 54 for limiting the intensity distribution. X-rays that have passed through the subject 56 are received by the detector 58, converted into electrical signals, and sent to a computer (not shown). Each component such as the X-ray tube device 50, the wedge filter 52, the slit 54, and the detector 58 is attached to a substantially cylindrical rotary mount 64 that is rotatably supported by a fixed mount 62 via a bearing 60. With the rotation of 64, the periphery of the subject 56 is rotated. Then, the X-ray tube device 50 and the detector 58 facing each other rotate around the subject 56 to obtain projection data covering all angles at every point in the inspection cross section of the subject 56, and from these data, A tomographic image is obtained by a preprogrammed reconstruction program.

In the CT scanner apparatus, in order to make the inner peripheral surface of the fixed base 62 have a large diameter of about 1 m so that the subject 56 can enter, the bearing 60 between the fixed base 62 and the rotary base 64 has a diameter relative to the diameter. So-called ultra-thin type rolling bearings having a remarkably small cross section are used. As shown in FIG. 3A, the ultra-thin type rolling bearing 60 includes a plurality of rolling members 66, an inner member 68, and a plurality of rolling members interposed between the outer member 66 and the inner member 68. The moving body 70 and the holder | retainer 72 for hold | maintaining the rolling element 70 in the circumferential direction at predetermined intervals are provided.
JP 2001-304266 A

  The resin-made cage used for the ultra-thin type rolling bearing is composed of a plurality of segments s, and each has a structure joined in the circumferential direction (FIG. 4A). In view of the structure of the molding die, a shape having no chamfer at the corner of the cage is less expensive, and therefore, the corner of the cage is generally not chamfered. Further, in the case of a bearing with a rubber seal as shown in FIG. 3B, the structure in which the contact between the cage 72 and the rubber seal 74 is unavoidable, or that the cage 72 is intentionally guided by the rubber seal 74, or is held. Even when a sufficient clearance is secured between the cage 72 and the rubber seal 74, when the cage is pressed against the rubber seal 74 due to an excessive load, the cage 72 and the rubber seal 74 are rubbed and the rubber seal 74 is rubbed. May wear out. As a result, there are concerns about problems such as an increase in rotational torque, premature deterioration of grease due to rubber seal wear powder, and a decrease in bearing life.

  Further, in the case of the segment type retainer 72, as shown in FIG. 4B, it is impossible to completely eliminate the formation of a step at the joint. Due to this step, the corners of the segment s come into contact with the rubber seal 74, so that the rubber seal 74 is worn.

  A main object of the present invention is to suppress wear of a rubber seal in an ultra-thin type rolling bearing.

  This invention solves the problem by adopting a cage structure that can suppress the stress concentration at the rubber seal contact position with the cage corners when the cage and the rubber seal come into contact with each other.

The invention of claim 1 includes an outer member having a track on the inner peripheral surface, an inner member having a track on the outer peripheral surface, and a plurality of members interposed between the track of the outer member and the track of the inner member. A cage for an ultra-thin type rolling bearing comprising a rolling element, a cage having a pocket for accommodating the rolling element, and a rubber seal attached to the outer member or the inner member,
Consists of a plurality of resin segments joined in the circumferential direction, each segment having a pocket opened at one end face in the axial direction, at least on the back side opposite to the one end face, on the seal An ultra-thin type rolling bearing cage in which corners of the inner and outer peripheral surfaces are rounded and at least the end surface of the segment joint portion on the back side opposite to the one end surface is wiped. By rounding the corners on the back of the cage, the stress generated in the rubber seal is alleviated and the wear of the rubber seal is suppressed even if it comes into contact with the rubber seal. Here, the cage back means the end surface of the cage in the axial direction opposite to the side where the pockets are open.

  The corner may be chamfered linearly (Claim 2) or a convex arc-shaped cross section (Claim 3).

In addition, by rubbing the end face on the back side in the vicinity of the segment coupling part, even when a step occurs in the segment joint part due to a manufacturing error, for example, the influence on the rubber seal is reduced as much as possible to suppress the rubber seal wear. Is.

The end surface on the back side may be straightened (Claim 4 ) or may be curbed (Claim 5 ).

The invention of claim 6 includes a plurality of outer members having a track on the inner peripheral surface, an inner member having a track on the outer peripheral surface, and a track between the outer member track and the inner member track. A retainer according to any one of claims 1 to 5 , comprising a rolling element, a cage having a pocket for accommodating the rolling element, and a rubber seal attached to the outer member or the inner member. It is an ultra-thin type rolling bearing characterized by being.

  According to the present invention, even if the cage and the rubber seal are in contact with each other, it is possible to suppress an increase in rotational torque and rubber seal wear. Further, this cage is inserted into the bearing by manually pushing the back surface (contact surface with the seal), but workability and safety are improved by rounding the corners.

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

  FIG. 1A shows a cross section of a bearing used in the CT scanner apparatus already described with reference to FIG. 2 as an example of an ultra-thin type rolling bearing. This bearing has an outer member 10, an inner member 20, a rolling element 30, a cage 40, and a rubber seal 18 as main components.

  The outer member 10 is ring-shaped, and a track 14 is formed on the inner peripheral surface 12. The inner member 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 member 10 and the track 24 of the inner member 20, and the outer member 10 and the inner member 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 member 10 and the inner member 20, and holds the plurality of rolling elements 30 at a predetermined interval in the circumferential direction. A rubber seal 18 for sealing both ends of the bearing is attached to the outer member 10.

In this bearing, ultrathin-walled 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), mainly PCD Is applied to large-diameter bearings of about 500 mm to 1500 mm. A specific example is as follows.
Ball diameter _D B: 1/2 inch (12.7mm)
PCD: 1041.4mm
The value of the ratio of the ball diameter _{D B} and the pitch circle diameter PCD phi: 0.012

  A mounting hole 16 is formed on the end face of one of the outer members 10 (the right side in FIG. 1A). By screwing a fastening means such as a bolt (not shown) into the mounting hole 16, the outer member 10 is fixed to the rotary base 64 (FIG. 2) of the CT scanner device. Similarly, an attachment hole 26 is formed in the end face of the inner member 20, and the inner member 20 is fixed to the fixed base 62 (FIG. 2) by screwing fastening means such as a bolt (not shown) into the attachment hole 26. The The outer member 10 becomes a rotating member that rotates together with the rotating mount 64, and the inner member 20 becomes a non-rotating fixed member. Depending on the structure of the CT scanner device, the outer member 10 can be the fixed side and the inner member 20 can be the rotating side, contrary to the above.

The cage 40 is molded from a resin material. This resin-made cage 40 is a so-called segment type, in which arc-shaped segments S are joined together in the circumferential direction to form an annular shape. Figure 1 (c), the concave-shaped joint 4 8 segments S next to the convex joint portions 4 8 a and the concave-shaped joint 4 8 b formed at both ends of each segment S, a binding partner segment S together by mating with b and convex joint portions 4 8 a are joined, an annular retainer 40 is formed.

  In the illustrated example, each segment S includes a base portion 42 and a column portion 44. The column portion 44 extends in the axial direction from the base portion 42, and a pocket is formed between the adjacent column portions 44. Here, the pocket is divided into two types depending on its shape. That is, the first pocket 46a and the second pocket 46b.

  In the case of the illustrated example, the first pocket 46a includes a tapered portion whose separation distance gradually increases toward the opening end, a straight portion parallel to the axis, and a concave spherical portion having a curvature radius slightly larger than the curvature radius of the ball 30. , Arranged sequentially from the opening side. The tapered portion and the straight portion are flat surfaces extending in the radial direction. The distance between the straight portions is slightly smaller than the diameter of the ball 30. Therefore, the straight portion restricts the ball 30 from jumping to the pocket opening side, and the ball 30 is held in the pocket 46a (ball holding). function).

  On the other hand, the second pocket 46b is composed of a concave spherical portion having a radius of curvature slightly larger than the radius of curvature of the ball 30, and a partial cylindrical portion extending axially and tangentially from the concave spherical portion. The ball 30 accommodated in the second pocket 46b is movable in the axial direction. Therefore, the second pocket 46b does not have a ball holding function like the first pocket 46a.

  The shapes and structures of the above-described pockets 46a and 46b are merely examples. For example, pockets having various shapes and structures can be adopted depending on the use conditions of the bearing, such as a single pocket.

  In assembling the ball 30 and the cage 40, the cage 40 is pushed in, not the ball 30. That is, if the end surface opposite to the side where the pockets 46a and 46b are open is called the back surface 41, the rolling elements between the outer member 10 and the inner member 20 will be described. In the state where the 30s are arranged, the openings of the pockets 46a and 46b are aligned with the positions of the rolling elements 30, and the back surface 41 of the retainer 40 is pushed, so that the ball 30 is accommodated in the pockets 46a and 46b.

  In both the first pocket 46a and the second pocket 46b, there is a gap (hereinafter referred to as a pocket clearance) between the surface of the ball 30 and the inner surface of the pocket, and is retained by the presence of the pocket clearance during rotation of the bearing. The vessel 40 moves relative to the ball 30 in the radial direction. Along with this relative movement, the cage 40 contacts either the inner circumferential surface 12 of the outer member 10 or the outer circumferential surface 22 of the inner member 20, and the rotation of the cage 40 is guided. In this embodiment, the outer peripheral surface of the cage 40 is in contact with the inner peripheral surface 12 of the outer member 10. The retainer 40 rotates by receiving a driving force from the outer member 10.

  As shown in FIG.1 (b), the corner | angular part of the outer peripheral surface and inner peripheral surface of the holder | retainer 40 is rounded. As shown in the figure, the corners may be chamfered in a straight line instead of having a convex arc-shaped cross section. By rounding the corners in this way, excessive stress is prevented from being generated in the rubber seal 18 even when the cage 40 comes into contact with the rubber seal 18, and wear of the rubber seal 18 can be suppressed. In this embodiment, only the back surface 41 has rounded corners. The corners may be rounded at both end faces, such as when both end faces may come into contact with the rubber seal 18.

  Further, as shown by reference numeral 49 in FIG. The shape of the relief portion may be a gentle curved shape in addition to the linear shape shown in the figure. As shown in FIG. 1 (d), even if a step is formed in the joint due to a manufacturing error or the like as shown in FIG. 1 (d), the step portion is retracted from the end face of the cage. Therefore, the influence on the rubber seal 18 can be minimized. The loosening portion may be provided not only on the back surface 41 but also on both end surfaces of the cage 40.

(A) is a cross-sectional view of an ultra-thin type rolling bearing, (b) is a partially enlarged view of FIG. 1 (a), (c) is a partial development view of a cage, and (d) is a portion of FIG. 1 (c). Enlarged view Cross section of CT scanner device (A) is the fragmentary sectional view of the ultra-thin type rolling bearing which shows a prior art, (b) is the elements on larger scale of Fig.3 (a). (A) is the partial expanded view of the holder | retainer which shows a prior art, (b) is the elements on larger scale of Fig.4 (a), (c) is a front view of a holder | retainer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Outer member 12 Inner peripheral surface 14 Track 16 Mounting hole 18 Seal 20 Inner member 22 Outer peripheral surface 24 Track 26 Mounting hole 30 Rolling element 40 Retainer 41 Back surface 42 Base 44 Pillar portion 46a First pocket 46b Second pocket 48a Convex Joint 48b Concave joint 49 Nusumi

Claims (6)

An outer member having a track on the inner peripheral surface, an inner member having a track on the outer peripheral surface, a plurality of rolling elements interposed between the track of the outer member and the track of the inner member, and a rolling element A cage for an ultra-thin type rolling bearing comprising a cage having a pocket for accommodating and a rubber seal attached to the outer member or the inner member,
Consists of a plurality of resin segments joined in the circumferential direction, each segment having a pocket opened at one end face in the axial direction, at least on the back side opposite to the one end face, on the seal An ultra-thin type rolling bearing retainer that rounds the corners of the inner and outer peripheral surfaces that face each other, and at least the end surface of the segment joint portion on the back side opposite to the one end surface.   The cage for an ultra-thin type rolling bearing according to claim 1, wherein the corner is linearly chamfered.   2. The ultra-thin type rolling bearing retainer according to claim 1, wherein the corner has a convex arc shape in cross section. The cage for an ultra-thin type rolling bearing according to claim 1, wherein the end surface on the back side is straightened . The cage for an ultra-thin type rolling bearing according to claim 1 , wherein the end surface on the back side is gently curved . An outer member having a track on the inner peripheral surface, an inner member having a track on the outer peripheral surface, a plurality of rolling elements interposed between the track of the outer member and the track of the inner member, and a rolling element A retainer having a pocket for accommodating and a rubber seal attached to the outer member or the inner member, wherein the retainer is the retainer according to any one of claims 1 to 5. Ultra-thin type rolling bearing.

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