JP2020008066A - Rolling bearing device - Google Patents

Abstract

To provide a rolling bearing device which enables reduction of satellite oil by reducing output of a pump and efficiently supplies lubrication oil to a raceway even if the output of the pump is reduced.SOLUTION: A rolling bearing device 10 includes: a bearing part 20 which has an inner ring 21, an outer ring 22, and multiple balls 23 and in which the inner ring 21 rotates; and a pump 43 which is provided adjacent to one axial side of the bearing part 20 and jets lubrication oil toward the inner ring 21 as oil droplets. The inner ring 21 has: an inner ring raceway 25; a first outer peripheral surface 31 provided at one axial side of the inner ring raceway 25; and a second outer peripheral surface 32 provided at the other axial side of the inner ring raceway 25. The pump 43 jets oil droplets to the first outer peripheral surface 31. The first outer peripheral surface 31 is formed with a groove 33 in which a groove width narrows toward a groove bottom and the groove bottom is formed into a linear shape.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rolling bearing device provided with a pump for supplying lubricating oil to a bearing unit.

  2. Description of the Related Art In recent years, various types of machine tools have been required to increase the speed of a spindle in order to improve processing efficiency and production efficiency. When the main shaft rotates at a high speed, lubrication becomes a problem particularly in the bearing portion supporting the main shaft. Therefore, there has been proposed a rolling bearing device in which a pump (oil supply unit) for supplying lubricating oil to a bearing portion is provided adjacent to the bearing portion in the axial direction (see Patent Document 1).

JP 2018-17289 A

  The pump of the rolling bearing device disclosed in Patent Literature 1 has a configuration in which a small amount of oil droplets is ejected toward the inner raceway of the bearing portion by the operation of the piezoelectric element. For this reason, the amount of consumed lubricating oil can be reduced to, for example, 1/1000 or less as compared with the oiling method using oil-air lubrication.

  However, since the inner ring orbit is far from the pump, it is necessary to eject (fly) oil droplets with large kinetic energy. Therefore, it is necessary to increase the output of the pump, that is, the driving voltage applied to the piezoelectric element.

  FIG. 7 is an explanatory diagram showing a state where the pump 90 has ejected minute oil droplets 99. When lubricating oil is ejected from the discharge port 91 of the pump 90 as an oil droplet 99, a thread-like portion 98 of lubricating oil (hereinafter referred to as satellite oil 98) is formed after the leading oil droplet 99. There is. The satellite oil 98 is separated from the leading oil droplet 99 and returns to the pump 90 due to viscosity. The satellite oil 98 that has returned to the pump 90 side is not collected inside the pump 90 and adheres to the wall surface 94 of the pump body 93 where the discharge port 91 opens. If the satellite oil 98 adheres to the wall surface 94, the discharge port 91 may be blocked. In this case, it may become an obstacle when the lubricating oil is discharged from the discharge port 91 later, which may result in poor lubricating oil discharge.

It has been empirically found by the present inventors that when the output of the pump 90 is large, that is, when the driving voltage of the piezoelectric element is under a high load condition close to the rated voltage, the satellite oil 98 is likely to be generated. .
Therefore, the present invention makes it possible to reduce the amount of satellite oil by reducing the output of the pump, and even if the output of the pump is reduced, it is possible to efficiently supply the lubricating oil to the orbit. Provide a bearing device.

  The rolling bearing device of the present invention has an inner ring, an outer ring, and a plurality of rolling elements interposed between the inner ring and the outer ring, and a bearing portion on which the inner ring rotates, and an axial one side of the bearing portion. A pump that is provided adjacent to the inner ring and ejects lubricating oil as oil droplets toward the inner ring, wherein the inner ring has a track on which the rolling element rolls, and a first outer circumference provided on one axial side of the track. Surface, a second outer peripheral surface provided on the other axial side of the track, the pump ejects oil droplets toward the first outer peripheral surface, the first outer peripheral surface, The groove width becomes narrower toward the groove bottom, and a groove having a linear groove bottom is formed.

  According to this rolling bearing device, the pump provided adjacent to one side in the axial direction of the bearing ejects oil droplets on the first outer peripheral surface on one side in the axial direction of the inner ring, so that the flight distance of the oil droplets is reduced. , Which is shorter than when the oil droplet flies to the orbit. For this reason, the output of the pump can be reduced. Lubricating oil (oil droplets) supplied to the first outer peripheral surface is held in the groove. The cross-sectional shape of the groove is such that the groove width becomes narrower toward the groove bottom, and the groove bottom becomes linear. Spread and spread. Therefore, the lubricating oil easily reaches the orbit. From the above, it is possible to reduce the amount of satellite oil by reducing the output of the pump, and even if the output of the pump is reduced, the lubricating oil can easily flow along the groove to the orbit, and the lubricating oil can be efficiently transferred to the orbit It becomes possible to supply well.

  Further, it is preferable that the groove bottom is inclined so as to be radially outward toward the track. In this case, the lubricating oil retained in the groove on the first outer peripheral surface flows along the groove, but since the groove bottom is inclined radially outward toward the track, the inner ring Due to the centrifugal force generated by the rotation of the lubricating oil, the lubricating oil can flow more easily into the orbit.

  Preferably, the groove extends rearward in the rotation direction of the inner race toward the track. In this case, the lubricating oil held in the groove on the first outer peripheral surface flows along the groove. At this time, the rotation of the inner ring pushes the lubricating oil in the direction toward the track, and the lubricating oil is To flow more easily.

  According to the present invention, it is possible to reduce satellite oil by reducing the output of the pump, and it is possible to efficiently supply lubricating oil to the track even if the output of the pump is reduced.

It is sectional drawing which shows an example of a rolling bearing device. It is the figure which looked at the refueling unit from the axial direction. It is the figure which looked at the inner ring from the radial outside. It is explanatory drawing of the groove | channel formed in the 1st outer peripheral surface. It is sectional drawing explaining the 1st outer peripheral surface of an inner ring. It is sectional drawing which shows the modification of a groove | channel. It is explanatory drawing which shows the state which the pump discharged the very small oil droplet.

[Overall configuration]
FIG. 1 is a sectional view showing an example of the rolling bearing device. Although not shown, a rolling bearing device 10 (hereinafter, referred to as a bearing device 10) shown in FIG. 1 rotatably supports a spindle (shaft) of a spindle device of a machine tool, and a bearing housing of the spindle device. Housed within. The bearing device 10 can be applied to a machine tool other than a machine tool.

  The bearing device 10 includes a bearing unit 20 and a refueling unit 40. The bearing portion 20 includes an inner ring 21, an outer ring 22, a plurality of balls (rolling elements) 23, and a retainer 24 for holding the plurality of balls 23, and constitutes a ball bearing (rolling bearing). . Further, the bearing device 10 includes a cylindrical inner race spacer 17 and an outer race spacer 18. The inner race 21 and the inner race spacer 17 rotate integrally with the main shaft.

  The direction along the center line C of the bearing portion 20 (the inner ring 21) is defined as the "axial direction" of the bearing portion 20, and here, the direction parallel to the center line C is also included in the "axial direction". In FIG. 1 (and FIGS. 3 and 5), the right side is one side in the axial direction of the bearing unit 20, which is called “one side in the axial direction”, and the left side is the one side in the axial direction of the bearing unit 20. The other side is referred to as “the other side in the axial direction”. The direction orthogonal to the center line C is the “radial direction”, and the direction in which the inner ring 21 rotates about the center line C is referred to as the “circumferential direction”.

  The refueling unit 40 has an annular shape as a whole, and is provided on the inner peripheral side of the outer race spacer 18. The refueling unit 40 is located adjacent to one side of the bearing portion 20 in the axial direction. The refueling unit 40 has a pump 43 and the like for refueling the bearing unit 20. The configuration and the like of the refueling unit 40 will be described later. In the embodiment of FIG. 1, a later-described main body 41 and the outer race spacer 18 of the refueling unit 40 are separate members, but they may be formed of the same member.

  The inner race 21 is a cylindrical member that fits over the main shaft, and has a track (hereinafter referred to as an inner race track 25) formed on the outer periphery thereof. In the outer peripheral surface of the inner ring 21, a region on one axial side (the pump 43 side) of the inner raceway 25 is the first outer peripheral surface 31, and a region on the other axial side of the inner raceway 25 is a second outer peripheral surface 32. It is. In the present embodiment, the outer peripheral surface of the shoulder on one axial side of the inner ring 21, that is, the first outer peripheral surface 31 is a shoulder lowering surface. Although the inner race 21 and the inner race spacer 17 are separate members, they are not shown, but may be formed of the same member.

  The outer ring 22 is a cylindrical member attached to the inner peripheral surface of the bearing housing, and has a track (hereinafter, referred to as an outer ring track 26) formed on the inner circumference thereof. Although the outer race 22 and the outer race spacer 18 are separate members, they are not shown, but may be formed of the same member.

  The ball 23 is interposed between the inner race 21 and the outer race 22, and when the inner race 21 rotates, it rolls on the inner raceway 25 and the outer raceway 26. In this embodiment, the ball 23 has a contact angle and contacts the inner raceway 25 and the outer raceway 26. The retainer 24 is annular, and has a plurality of pockets 27 formed along the circumferential direction. The ball 23 and the retainer 24 are provided in the annular space 11 formed between the inner ring 21 and the outer ring 22. The retainer 24 is annular as a whole, and has an annular body 28a on one axial side of the ball 23, an annular body 28b on the other axial side of the ball 23, and a plurality of pillars 29 connecting the annular bodies 28a and 28b. And A pocket 27 is formed between the pillars 29, 29 which are between the annular bodies 28 a, 28 b and are adjacent in the circumferential direction, and one ball 23 is accommodated in each pocket 27. In the retainer 24, the annular body 28 a on one side in the axial direction can slide on the shoulder 39 of the outer race 22. Thereby, the retainer 24 is positioned in the radial direction by the outer ring 22. That is, the bearing portion 20 is a bearing in which the cage 24 is guided by the outer ring (guide ring guide).

  FIG. 2 is a diagram of the refueling unit 40 viewed from the axial direction. The refueling unit 40 includes a tank 42, a control unit 44, and a power supply unit 45 in addition to the pump 43. In the present embodiment, the tank 42, the pump 43, the control unit 44, and the power supply unit 45 are provided in an annular main body 41 of the refueling unit 40. The tank 42 stores lubricating oil (oil) and is connected to the pump 43 through a pipe 46 to supply the lubricating oil to the pump 43. The power supply unit 45 supplies electric power for operating the pump 43. The control unit 44 controls the timing at which the pump 43 operates.

  The main body 41 is attached to the inner peripheral side of the outer race spacer 18 and has a function as a frame that holds the pump 43 and the like. Although the main body 41 is an annular member, a hollow space is formed therein, and a tank 42, a pump 43, a control unit 44, and a power supply unit 45 are provided in the hollow space. Thereby, the refueling unit 40 including the main body 41, the tank 42, the pump 43, the control unit 44, and the power supply unit 45 is integrally configured.

  The pump 43 has a piezoelectric element (piezo element) 43a inside. The operation of the piezoelectric element 43 a changes the volume of the oil chamber (internal space) 43 b of the pump 43, and ejects the lubricating oil in the oil chamber 43 b from the discharge port 50. The discharge port 50 is connected to the oil chamber 43b, and opens toward the first outer peripheral surface 31 of the inner ring 21, as shown in FIG. The discharge port 50 is formed by a minute through hole formed in the wall 49 of the pump body 43c. When the piezoelectric element 43a operates, the lubricating oil is discharged from the discharge port 50 as an oil droplet at an initial velocity. That is, for example, the oil droplets fly from the discharge port 50 of the pump 43 so that the ink is discharged from the discharge port formed in the ink jet head used in the printing technique. In FIG. 1 (and FIG. 5), the ejection direction of the oil droplet is indicated by an arrow J.

  As described above, the pump 43 (see FIG. 1) is provided adjacent to one side in the axial direction of the bearing portion 20 and ejects the lubricating oil toward the inner ring 21 as oil droplets. More specifically, the pump 43 has a configuration in which the lubricating oil in the oil chamber 43b is ejected (flyed) from the discharge port 50 as an oil droplet toward the target of the bearing unit 20. The target in the present embodiment is the first outer peripheral surface 31 of the inner ring 21. From the viewpoint of efficient use of the lubricating oil, the pump 43 ejects a predetermined amount of oil droplets in one discharge operation, and the oil droplets reach the first outer peripheral surface 31. With one operation of the pump 43, several picoliters to several nanoliters of lubricating oil are ejected from the discharge port 50 as oil droplets. The diameter (equivalent diameter) of the oil droplet is, for example, 10 to 30 micrometers.

[About inner ring 21]
In the embodiment shown in FIG. 1, the first outer peripheral surface 31 of the inner ring 21 is an inclined surface (tapered surface) whose diameter increases toward the inner ring raceway 25. FIG. 3 is a view of the inner ring 21 as viewed from the outside in the radial direction. A plurality of grooves 33 are formed on the first outer peripheral surface 31. FIG. 4 is an explanatory diagram of the grooves 33 formed on the first outer peripheral surface 31. The groove 33 of the present embodiment has a V-shaped cross section, the groove width W becomes narrower toward the groove bottom 34, and the groove bottom 34 is linear. An intersection line formed by intersection of the groove side surfaces 35 on both sides becomes the groove bottom 34. In the present embodiment, the groove side surface 35 has a linear shape in the cross section of the groove 33.

  The direction along the linear groove bottom 34 is referred to as the longitudinal direction of the groove 33. The groove width W is a dimension in a direction orthogonal to the longitudinal direction of the groove 33. The depth H (groove depth) of the groove 33 is a dimension from the first outer peripheral surface 31 to the groove bottom 34. For example, the groove width W is larger than the maximum value of the diameter (equivalent diameter) of the oil droplet ejected from the pump 43 and smaller than three times this maximum value. The groove depth H is larger than the maximum value of the diameter (equivalent diameter) of the oil droplet and smaller than three times the maximum value.

  FIG. 5 is a sectional view illustrating the first outer peripheral surface 31. As described above, the first outer peripheral surface 31 is an inclined surface (taper surface) whose diameter increases toward the inner raceway 25. Since the groove depth H (see FIG. 4) is constant along the longitudinal direction of the groove 33, the groove bottom 34 is inclined so as to go radially outward toward the inner raceway 25. Although not shown, when the first outer peripheral surface 31 is a cylindrical surface centered on the center line C, the groove 33 may be configured such that the groove depth H becomes shallower toward the inner raceway 25. Even in this case, the groove bottom 34 is inclined so as to be radially outward toward the inner raceway 25.

  As shown in FIG. 3, when the first outer peripheral surface 31 is viewed from the outside in the radial direction, the groove 33 is inclined. That is, the groove 33 is inclined with respect to the virtual bus L0 on the first outer peripheral surface 31. The angle (inclination angle) θ between the virtual bus L0 and the longitudinal direction of the groove 33 is, for example, 10 ° or more and 60 ° or less. Note that this angle θ may be less than 10 ° or 0 °. When the angle θ is 0 °, the groove 33 is not inclined with respect to the virtual bus L0, but has a form along the virtual bus L0. The groove 33 is formed to extend from the side surface 37 on one axial side of the inner ring 21 to the inner ring track 25. That is, one of the longitudinal directions of the groove 33 opens at the side surface 37, and the other of the longitudinal direction of the groove 33 continues to the inner raceway 25.

[About the bearing device 10 of the present embodiment]
In the bearing device 10 of the present embodiment (see FIG. 1) having the above configuration, the inner race 21 of the bearing portion 20 is provided on the inner raceway 25 on which the ball 23 as a rolling element rolls and on one axial side of the inner raceway 25. And a second outer peripheral surface 32 provided on the other axial side of the inner raceway 25. The pump 43 is provided adjacent to one side in the axial direction of the bearing portion 20 and ejects oil droplets toward the first outer peripheral surface 31. A groove 33 is formed on the first outer peripheral surface 31, and the groove 33 has a groove width W narrower toward the groove bottom 34, and the groove bottom 34 has a linear shape. According to this bearing device 10, the pump 43 provided adjacent to one side in the axial direction of the bearing portion 20 ejects oil droplets to the first outer peripheral surface 31 on one side in the axial direction of the inner race 21, so that the oil droplets Is shorter than the case where the oil droplet flies to the inner ring orbit 25. Therefore, the output of the pump 43 can be reduced. That is, the drive voltage of the piezoelectric element 43a can be made lower than the rated voltage. Then, the lubricating oil (oil droplet) supplied to the first outer peripheral surface 31 is held in the groove 33. The cross-sectional shape of the groove 33 is such that the groove width W becomes narrower toward the groove bottom 34, and the groove bottom 34 becomes linear. Therefore, even with a small amount of lubricating oil, the lubricating oil permeates and spreads along the longitudinal direction of the groove 33. Therefore, the lubricating oil easily reaches the inner raceway 25.

  As described above, by reducing the output of the pump 43, it is possible to reduce the amount of satellite oil 98 (see FIG. 7) which is conventionally likely to be generated. Then, even if the output of the pump 43 is reduced, the lubricating oil easily flows along the groove 33 to the inner raceway 25, and the lubricating oil can be efficiently supplied to the inner raceway 25. The lubricating oil supplied to the inner raceway 25 becomes an oil film between the balls 23 and is also supplied to the outer raceway 26 so that the lubrication performance of the bearing portion 20 can be maintained.

  If the groove 33 is not formed in the first outer peripheral surface 31 and the first outer peripheral surface 31 is a smooth surface, the lubricating oil supplied to the first outer peripheral surface 31 is not retained and the rotation of the inner ring 21 is not performed. May be scattered in various directions due to the centrifugal force generated by the centrifugal force, and may not be used effectively for lubrication of the bearing portion 20.

  In the bearing device 10 of the present embodiment (see FIG. 5), the lubricating oil held in the groove 33 of the first outer peripheral surface 31 flows along the groove 33, but the groove bottom 34 of the groove 33 is It inclines so that it may go to the radial direction outside toward 25. For this reason, when the inner race 21 rotates, the centrifugal force causes the lubricating oil held in the groove 33 to flow more easily to the inner raceway 25 along the groove 33.

  3, the direction of rotation of the inner race 21 is indicated by an arrow R. As described above, the groove 33 is inclined with respect to the virtual bus L0 on the first outer peripheral surface 31. The inclination direction of the groove 33 with respect to the virtual bus L <b> 0 is a direction in which the groove 33 extends backward (opposite to the arrow R) in the rotation direction (the direction of the arrow R) of the inner ring 21 toward the inner ring track 25. With this configuration, the lubricating oil held in the groove 33 flows along the groove 33. At this time, the rotation of the inner ring 21 causes the lubricating oil to move toward the inner ring raceway 25 (the groove side surface 35; see FIG. 4). ), The lubricating oil flows more easily to the inner raceway 25.

  In FIG. 5, the range B of the first outer peripheral surface 31 where the groove 33 is formed is as follows. The range B of the groove 33 is a region that is not in contact with the ball 23 from a position P0 where the side surface 37 on one side in the axial direction of the inner ring 21 and the first outer peripheral surface 31 intersect. Up to the radially inner region of the ball 23. One axial end of the groove 33 coincides with the side surface 37 of the inner race 21. The other axial end of the groove 33 is located at a position P1 on the inner raceway 25 side with respect to a radially inner region K1 (first region K1) of the annular body 28a of the retainer 24. A plurality of grooves 33 are formed over the entire axial range B from the side surface 37 (the position P0) to the position P1. The pump 43 (discharge port 50) is arranged so that the oil droplets ejected from the pump 43 (discharge port 50) reach this range B.

  In the first outer peripheral surface 31, the arrival position of the oil droplets from the pump 43 may be a region K1 (first region K1) radially inward of the annular body 28a of the retainer 24, and may be a first region K1. It may be a region K2 (second region K2) on one side in the axial direction.

  Here, when the inner ring 21 rotates, the air existing in the annular space 11 is rotated by the inner ring 21 and the like. That is, a circumferential air flow (air curtain) is generated between the inner race 21 and the outer race 20 in the annular space 11. When the inner ring 21 rotates at a high speed, the flow of the air also increases. The oil droplets ejected from the pump 43 fly in this air flow (air curtain). When the arrival position of the oil droplet is in the second area K2, the oil droplet flying from the pump 43 is hardly affected by the distance flying in the air curtain because it is short. Therefore, the oil droplet can easily reach a desired position. On the other hand, when the arrival position of the oil droplet is in the first region K1, the oil droplet is liable to be influenced by a long flight distance in the air curtain, but the arrival position is close to the inner raceway 25 and the inner raceway 25 Supply of lubricating oil to the vehicle becomes easy.

  In the above-described embodiment (see FIG. 4), the groove 33 is V-shaped. However, the groove 33 may have a groove shape in which the groove width W becomes narrower toward the groove bottom 34 and the groove bottom 34 becomes linear. For example, as another example, as shown in FIG. 6A, in the cross section of the groove 33, the groove side surface 35 may have a convex curve shape, or as shown in FIG. In the cross section of the groove 33, the groove side surface 35 may have a concave curve shape or the like. According to such a shape, as in the embodiment shown in FIG. 4, the oil droplets that have reached the groove 33 of the first outer peripheral surface 31 are held along the groove bottom 34 by surface tension, and the amount of lubricating oil is small. However, it easily penetrates and spreads in the longitudinal direction of the groove 33 and is easily supplied to the inner raceway 25.

The embodiment disclosed this time is an example in all respects and is not restrictive. The scope of rights of the present invention is not limited to the above-described embodiment, but includes all modifications within a scope equivalent to the configuration described in the claims.
In the above-described embodiment, the case where the bearing portion 20 is an angular ball bearing is described. However, the type of the bearing is not limited to this, and may be a deep groove ball bearing, or may be a conical rolling bearing or a cylindrical roller bearing. May be.

20: Bearing part 21: Inner ring 22: Outer ring 23: Ball (rolling element) 25: Inner ring raceway 31: First outer peripheral surface 32: Second outer peripheral surface 33: Groove 34: Groove bottom 43: Pump W: Groove width

Claims (3)

An inner ring, an outer ring, and a plurality of rolling elements interposed between the inner ring and the outer ring, and a bearing portion around which the inner ring rotates,
A pump that is provided adjacent to one side in the axial direction of the bearing portion and that ejects lubricating oil as oil droplets toward the inner ring,
The inner race has a track on which the rolling element rolls, a first outer circumferential surface provided on one axial side of the track, and a second outer circumferential surface provided on the other axial side of the track.
The pump ejects oil droplets toward the first outer peripheral surface,
On the first outer peripheral surface, a groove is formed in which the groove width becomes narrower toward the groove bottom and the groove bottom becomes linear.
Rolling bearing device.   The rolling bearing device according to claim 1, wherein the groove bottom is inclined so as to be radially outward toward the track.   The rolling bearing device according to claim 1, wherein the groove extends rearward in the rotation direction of the inner race toward the track.

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