JP2017067230A - Bearing mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce damage at a bearing mechanism by creep or fretting and the like.SOLUTION: This invention relates to a bearing mechanism comprising outer rings 21 and inner rings 24; a plurality of rollers 22 fitted between these rings; a housing 10 for supporting outer peripheral surfaces of the outer rings 21; and a rotating shaft 30 supported at inner peripheral surfaces of the inner ring 24. Then, one of the outer ring 21 and the inner ring 24 is arranged to be moved toward a rotating axis direction in respect to the other ring, the one ring is pressed toward the rotating axis direction to generate a pre-pressure between the outer ring 21 and the inner ring 24. Then, there is provided a recess 32 at an outer peripheral surface of either an inner peripheral surface of the housing 10 supporting one ring or an outer peripheral surface of the rotating shaft 30. A resilient body 33 is arranged in the recess 32 so as to move toward a direction of the rotating shaft and further the resilient body 33 is press contacted with the bottom surface of the recess 32 and also press contacted with one ring opposing against the bottom surface.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a bearing mechanism suitable as a structure of a bearing, such as a machine tool, which has a high load at low speed rotation and a low load at high speed rotation.

  In general, when a ball bearing is used as a bearing for a high-speed rotating shaft in a spindle motor or the like, preload is applied to the ball bearing in order to improve the rotational accuracy by increasing the radial and axial rigidity of the rotating shaft. Is granted. This preloading is intended to maintain pressure in advance between the inner and outer rings by finely moving the other direction in the axial direction against one of the outer and inner rings constituting the ball bearing. .

By the way, in general machining such as milling, there is a tendency to perform heavy load machining with a deep cut at low rotation and light load machining with a shallow cut at high rotation. In the case of heavy load machining, it is necessary to increase the rigidity between the inner and outer rings of the bearing by adding a preload so that the rotating shaft loses the load and does not adversely affect machining accuracy. In light load machining, it is preferable to reduce the preload appropriately from the viewpoint of not requiring high rigidity and avoiding shortening of the bearing life.
Thus, for example, in the invention described in Patent Document 1, a centrifugal spring that elastically contracts in the axial direction while elastically expanding by centrifugal force is used to automatically apply a preload to the inner ring according to the rotational speed. To make adjustments.

  However, according to the prior art, because of the structure for applying the preload, the rotating shaft and the inner ring are fitted so as to be “clearance fit” so that the inner ring is finely moved in the axial direction with respect to the rotating shaft. Therefore, the inner ring rotates in the circumferential direction relative to the rotation shaft, and the rotation in the circumferential direction may cause creep, fretting, etc., and may damage the sliding surface of the inner ring or the rotation shaft.

JP, 2015-10648, A

  The present invention has been made in view of the above-described conventional circumstances, and a problem to be solved by the present invention is to provide a bearing mechanism that can reduce damage due to creep, fretting, and the like.

  One means for solving the above problems is in the bearing mechanism, the inner ring and the outer ring, a plurality of rolling elements fitted between them, a housing that supports the outer peripheral surface of the outer ring, and the inner peripheral surface of the inner ring. And a supported rotating shaft. Then, one of the outer ring and the inner ring is provided so as to move in the direction of the rotation axis relative to the other ring, and by pressing the one ring in the direction of the rotation axis, Generate preload in between. Then, a recess is provided on the inner peripheral surface of the housing supporting one of the rings or the outer peripheral surface of the rotation shaft, and an elastic body is provided in the recess so as to move in the direction of the rotation axis. It is characterized by being in pressure contact with the bottom surface and also in pressure contact with one of the wheels facing the bottom surface.

  Since the present invention is configured as described above, damage due to creep, fretting, or the like can be reduced.

It is sectional drawing which shows an example of the bearing mechanism which concerns on this invention. It is an expanded sectional view of the bearing mechanism. It is a principal part expansion perspective view of the bearing mechanism. It is a perspective view which shows an example of the centrifugal spring in the bearing mechanism.

  One of the features of the present embodiment is that in the bearing mechanism, an inner ring and an outer ring, a plurality of rolling elements fitted between them, a housing that supports the outer peripheral surface of the outer ring, and an inner peripheral surface of the inner ring And a supported rotating shaft. Then, one of the outer ring and the inner ring is provided so as to move in the direction of the rotation axis relative to the other ring, and by pressing the one ring in the direction of the rotation axis, Generate preload in between. Then, a recess is provided on the inner peripheral surface of the housing supporting one of the rings or the outer peripheral surface of the rotation shaft, and an elastic body is provided in the recess so as to move in the direction of the rotation axis. While pressing against the bottom surface, it was also pressed against one of the wheels facing the bottom surface.

According to this configuration, when the rotating shaft is rotated, sliding between the rotating shaft and the inner ring or between the housing and the outer ring in the circumferential direction can be reduced by the elastic body. As a result, damage due to creep or fretting can be reduced.
In order to generate preload, when one wheel is pressurized in the direction of the rotation axis and finely moved, the elastic body is elastically deformed and moves in the direction of the rotation axis, so that fine movement is not hindered.
The “elastic body” and the “concave portion” are not limited in the shape in the circumferential direction. The “elastic body” and the “concave portion” may be formed in an annular shape continuous in the circumferential direction, The aspect etc. which were provided intermittently in the direction are included.

  Another feature is that the width of the recess in the rotation axis direction is smaller than the width of the elastic body in the rotation axis direction in order to smoothly finely move the elastic body in the rotation axis direction by pressurization in the rotation axis direction applied to one ring. Also, a clearance for moving the elastic body in the direction of the rotation axis was secured in the recess.

  The other feature is that, as a specific embodiment with particularly good productivity, the concave portion is formed in a concave groove shape continuous in the circumferential direction, and the elastic body is formed in an annular shape continuous in the circumferential direction.

  The other feature is that, as a specific aspect with better productivity, the inner ring is provided so as to move in the axial direction with respect to the rotating shaft, the inner ring is pressurized in the axial direction, and a recess is provided on the outer peripheral surface of the rotating shaft. An elastic body is provided in the recess.

  Another feature is that, as an aspect for effectively obtaining the above action, a centrifugal spring is provided on the outer peripheral surface of the rotating shaft so as to be pressed against the inner ring in the axial direction. The centrifugal spring is integrated with the rotating shaft. It is configured to elastically contract in the axial direction while elastically expanding its diameter by centrifugal force when rotated.

  Next, a preferred embodiment having the above features will be described in detail with reference to the drawings.

FIG. 1 is a side sectional view of a spindle motor A provided with a bearing mechanism of the present embodiment. The bearing mechanism 1 supports the rotating shaft 30 so as to be rotatable on the output side.
FIG. 2 is an enlarged cross-sectional view of a portion of the bearing mechanism 1. As shown in FIG. 2, the bearing mechanism 1 includes a substantially cylindrical housing 10, a plurality of bearings 20 a, 20 b, 20 c supported inside the housing 10, and a center side of these bearings 20 a, 20 b, 20 c. A rotating shaft 30 that is inserted and rotatable, a centrifugal spring 40 that is pressed against the bearing 20a in the axial direction, and a thrust receiving member 50 that receives the centrifugal spring 40 from the opposite side of the bearing 20a in the axial direction; The centrifugal spring 40 is elastically deformed by the centrifugal force generated when the rotary shaft 30 rotates, and the preloads of the bearings 20a, 20b, and 20c that are in pressure contact with the centrifugal spring 40 are automatically adjusted.

The housing 10 is a substantially cylindrical member made of metal.
Bearings 20a, 20b, and 20c are fitted to the inner peripheral surface of the housing 10, and a cylindrical spacer 61 and a fixing sleeve 62 are fitted so as to sandwich the bearings 20a, 20b, and 20c from the front and rear. .

Each of the bearings 20 a, 20 b, and 20 c has an endless annular outer ring 21, a plurality of rolling elements 22 that are rotatably held in the outer ring 21, and a circumferential interval between the rolling elements 22 is maintained substantially constant. And the endless annular inner ring 24 held on the center side of the outer ring 21 so as to rotate via the rolling elements 22, and the contact angle α between the outer ring 21 and the rolling elements 22 is set in the radial direction. An angular ball bearing tilted with respect to the angle is configured.
Each of the bearings 20 a, 20 b, and 20 c has the outer ring 21 fitted into the inner peripheral surface of the housing 10 in a “clearance fit” shape.

An annular recess 21 a is formed on the inner peripheral portion of each outer ring 21 so as to fit on the outer peripheral side of the rolling element 22. As shown in FIG. 3, each annular recess 21 a is formed in an inclined curved surface shape (asymmetric shape) that is biased toward one side in the rotational axis direction with respect to the center of the rolling element 22.
An annular recess 24 a is formed on the outer peripheral portion of each inner ring 24 so as to fit on the outer peripheral side of the rolling element 22. As shown in FIG. 3, each annular recess 24 a is formed in a concave curved surface that is symmetrical in the direction of the rotation axis with respect to the center of the rolling element 22.

Of the plurality of bearings 20a, 20b, and 20c, the first bearing 20a, counted from the centrifugal spring 40 side, has a contact angle α between the annular recess 21a of the outer ring 21 and the rolling element 22 on the anti-centrifugal spring 40 side (in FIG. 2). The second bearing 20b is configured to have a contact angle α on the centrifugal spring 40 side. Such a relationship may be referred to as a back combination.
The third bearing 20c counted from the centrifugal spring 40 side is configured to have a contact angle α on the centrifugal spring 40 side. The relationship between the bearing 20b and the bearing 20c may be referred to as a parallel combination.
A minute gap is provided between the inner ring 24 of the bearing 20a and the inner ring 24 of the bearing 20b for generating a preload in the bearing 20a.

Moreover, the rotating shaft 30 is a columnar or cylindrical elongate body, and is penetrated by the inner ring | wheel 24 of bearing 20a, 20b, 20c.
More specifically, the inner ring 24 of the bearing 20a closest to the centrifugal spring 40 is fitted to the outer peripheral surface of the rotary shaft 30 in a “clearance fit” shape. The inner rings 24 and 24 of the other two bearings 20b and 20c are fitted in a “fitting fit” shape on the outer peripheral surface of the rotating shaft 30, respectively.

  An annular step portion 31 formed by reducing the diameter of the bearing 20a, 20b, 20c side portion is formed on the anti-centrifugal spring 40 side (the left end side according to FIG. 2) of the outer peripheral portion of the rotating shaft 30. The end surface of the inner ring 24 of the bearing 20c is in contact with the step portion 31.

  In addition, a recess 32 is provided at a position corresponding to the bearing 20a closest to the centrifugal spring 40 in the outer peripheral portion of the rotating shaft 30, and an elastic body 33 is disposed in the recess 32 so as to move in the direction of the rotating shaft. Provided.

The concave portion 32 is formed in a concave groove shape that continues to the entire circumference of the rotating shaft 30.
The elastic body 33 is an O-ring that extends around the entire circumference of the rotating shaft 30 in the recess 32, and is formed of rubber, an elastic resin material, or the like.
The width W of the concave portion 32 in the rotational axis direction is set to be larger than the width (outer diameter D) of the elastic body 33 in the rotational axis direction, so that the elastic body 33 moves in the rotational axis direction in the concave portion 32. A gap s that enables this is secured (see FIG. 3). Note that the gap s may not be provided when the amount of movement of the elastic body 33 in the rotation axis direction can be ensured only by the amount of displacement due to the elasticity of the elastic body 33.
The elastic body 33 is in pressure contact with the bottom surface of the recess 32 and is also in pressure contact with the outer peripheral surface of the inner ring 24 facing the bottom surface.
That is, the outer diameter D of the linear portion of the elastic body 33 is set larger than the depth H of the recess 32.

  2 is an annular lid member that prevents foreign matter and the like from entering the bearing side from the gap between the fixed sleeve 62 and the rotary shaft 30, and covers the gap between the fixed sleeve 62 and the rotary shaft 30. Thus, it is being fixed to the outer peripheral surface of the rotating shaft 30. FIG.

Further, the centrifugal spring 40 is formed from a hard synthetic resin material that can be elastically deformed, and as shown in FIG. 4, a cylindrical portion 41 that is annularly attached to the rotary shaft 30, and an axial center of the cylindrical portion 41 It has integrally the protrusion part 42 protruded in the radial outward direction from the near side. The centrifugal spring 40 is fitted in a “clearance fit” shape with respect to the rotary shaft 30, and elastically moves near the center of the cylindrical portion 41 in the axial direction by centrifugal force when rotating integrally with the rotary shaft 30. The cylindrical portion 41 is elastically contracted in the axial direction while the diameter is increased.
As long as this centrifugal spring 40 has the same function, it is possible to use other materials or shapes other than the illustrated example. For example, a metal spring material or the like may be used as the material.

The thrust receiving member 50 is formed in a cylindrical shape from a metal material or the like, and is disposed so as to sandwich the cylindrical portion 41 of the centrifugal spring 40 between the inner ring 24 of the bearing 20a.
The thrust receiving member 50 is fixed to the outer peripheral surface of the rotary shaft 30 in a state where the cylinder portion 41 is pressurized in the axial direction so as to generate a preload on the bearing 20a via the cylinder portion 41 of the centrifugal spring 40. . The means for fixing the thrust receiving member 50 to the rotary shaft 30 can be press-fitting, screwing, uneven fitting, or the like.

Next, characteristic effects of the bearing mechanism 1 having the above-described configuration will be described in detail.
When the rotary shaft 30 is rotated, the inner ring 24 of the bearing 20 a is fitted in a “clearance fit” shape with respect to the rotary shaft 30, but is pressed against the outer peripheral surface of the rotary shaft 30 via the elastic body 33. Therefore, it rotates integrally with the rotating shaft 30. Therefore, the inner ring 24 of the bearing 20a can be prevented from rubbing against the outer peripheral surface of the rotary shaft 30.
Further, when the rotational speed of the rotary shaft 30 changes, the pressing force received by the inner ring 24 of the bearing 20a from the centrifugal spring 40 also changes due to the change in the axial dimension of the centrifugal spring 40, and the inner ring 24 moves in the rotational axis direction. The fine movement is ensured by elastic deformation of the elastic body 33 and movement in the recess 32. For this reason, the preload of bearing 20a, 20b, 20c can be changed normally.
Therefore, according to the bearing mechanism 1 of the present embodiment, the inner ring 24 of the bearing 20a can be prevented from sliding in the circumferential direction relative to the rotary shaft 30 without hindering the automatic preload adjustment function by the centrifugal spring 40. As a result, damage due to creep or fretting can be prevented.

  In addition, according to the said Example, although the recessed part 32 and the elastic body 33 were provided in the outer peripheral surface of the rotating shaft 30, as another example, the recessed part 32 and the elastic body 33 are housings so that it may respond | correspond to the position of the bearing 20a. It is also possible to prevent the outer ring 21 of the bearing 20a from slipping in the circumferential direction against the housing 10 and to prevent damage due to creep, fretting, or the like.

  According to the above embodiment, as a particularly preferable aspect, the preload is applied to the bearings 20a, 20b, and 20c using the centrifugal spring 40. However, as other examples, other than the coil spring and the other centrifugal springs 40 are used. It is also possible to apply a preload to the bearings 20a, 20b, and 20c by this mechanism, and even in this case, creep or fretting between the inner ring 24 and the rotating shaft 30, or between the outer ring 21 and the housing 10 is performed. It can be suppressed by the recess 32 and the elastic body 33 described above.

  Moreover, in the said Example, although the inner ring | wheel 24 was pressurized to the axial direction by the centrifugal spring 40, it is set as the structure by which the outer ring | wheel 21 is pressurized to the axial direction by the centrifugal spring 40, and a preload is provided. It is also possible.

  Moreover, although the angular contact ball bearing was comprised in the bearings 20a, 20b, and 20c of the said Example, a tapered roller bearing, a deep groove bearing, etc. can also be comprised as another example.

1: bearing mechanism 10: housing 21: outer ring 21a: annular recess 22: rolling element 24a: annular recess 24: inner ring 30: rotating shaft 32: recess 33: elastic body 40: centrifugal spring s: gap

Claims (5)

An inner ring and an outer ring; a plurality of rolling elements fitted between them; a housing that supports an outer peripheral surface of the outer ring; and a rotating shaft supported by the inner peripheral surface of the inner ring, the outer ring and the One of the inner rings is provided so as to move in the direction of the rotation axis relative to the other ring, and this one wheel is pressurized in the direction of the rotation axis, thereby generating a preload between the outer ring and the inner ring. In the bearing mechanism designed to be
A concave portion is provided on the inner peripheral surface of the housing supporting the one wheel or the outer peripheral surface of the rotary shaft, and an elastic body is provided in the concave portion so as to move in the direction of the rotary shaft. A bearing mechanism, wherein the bearing mechanism is in pressure contact with the bottom surface of the recess, and is also in pressure contact with the one wheel facing the bottom surface.   The width of the concave portion in the rotation axis direction is made larger than the width of the elastic body in the rotation axis direction, and a clearance for moving the elastic body in the rotation axis direction is secured in the concave portion. The bearing mechanism described.   The bearing mechanism according to claim 1 or 2, wherein the concave portion is formed in a concave groove shape continuous in the circumferential direction, and the elastic body is formed in an annular shape continuous in the circumferential direction.   The inner ring is provided so as to move in the axial direction with respect to the rotating shaft, the inner ring is pressurized in the axial direction, the concave portion is provided on the outer peripheral surface of the rotating shaft, and the elastic body is provided in the concave portion. The bearing mechanism according to any one of claims 1 to 3, wherein   A centrifugal spring is provided on the outer peripheral surface of the rotating shaft so as to be pressed against the inner ring in the axial direction. The centrifugal spring is elastically expanded by a centrifugal force when rotating integrally with the rotating shaft. 5. The bearing mechanism according to claim 4, wherein the bearing mechanism is configured to elastically contract in the axial direction.

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