Bearing device and spindle device

Abstract

To provide a bearing device and a spindle device that can efficiently discharge a lubricant supplied to a bearing, can stably operate continuously for a long time while maintaining a good lubrication state, can elongate the life of the bearing, and are easy to maintain.SOLUTION: A front-side bearing device comprises: a rolling bearing 20 for rotatably supporting a spindle 60 relative to a housing 50; and an outer ring spacer 40 and an outer ring presser which are fitted inside the housing 50 and position an outer ring 22 of the rolling bearing 20 in an axial direction. The bearing device supplies a lubricant G into the rolling bearing 20 via a lubricant supply path 52. One side surface 22b of the outer ring 22 is offset to an axially center side with respect to a side surface 21b of an inner ring 21 of the rolling bearing 20. An opening 41 penetrating the outer ring spacer 40 in a radial direction is formed in an end face 43 of the outer ring spacer 40 which abuts on the offset side surface 22b.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a bearing device and a spindle device using the same, and more particularly to an improvement in a bearing device and a spindle device that can efficiently discharge lubricant that has been replenished to a bearing. [Background technology]

[0002] Bearing devices that support the main spindles of machine tools have traditionally used oil lubrication, such as jet lubrication, oil mist, and oil air, as well as grease lubrication. In recent years, with the increasing speed of spindles, new lubrication methods have been developed, such as lean lubrication, in which a small amount of lubricant oil is applied intermittently to the raceway and rolling surfaces of rolling bearings at high speed, and lubrication methods that intermittently replenish grease into the rolling bearing space. These methods are capable of operating at speeds of 1 million dmN or more (dm: pitch circle diameter of rolling bearing (mm), N: rotational speed (min -1 In lubrication devices that supply or replenish lubricants such as lubricating oil and grease to bearings as described above, it is important to properly discharge the supplied lubricant in order to reduce the stirring resistance of the lubricant caused by the rotation of the spindle and to prevent the bearings from increasing in temperature and torque.

[0003] Grease in a general spindle is filled with 10% to 30% of the space in the bearing, and when the base oil inside the grease, which acts as a lubricant for the rotating bearing, is consumed, lubrication failure occurs and the bearing seizes. Therefore, the life of a grease-filled type spindle is the life of the grease, that is, the time it takes for the base oil to be consumed. In order to extend the life of the grease, there are methods to increase the amount of grease filled inside the bearing or to provide grease in the spacer adjacent to the bearing, but if the amount of grease filled is large, it takes time to break in. In addition, if a large amount of grease in the grease reservoir on the outer ring of the bearing and the spacer gets into the rolling surface of the bearing, there is a risk of a sudden temperature rise and seizure. Furthermore, in the case of a type that requires grease to be replenished, fresh grease is intermittently supplied to the bearing, so the life can be extended compared to a type that is filled with grease, but if the grease is not properly discharged from the bearing, there is a very high risk of seizure due to a sudden temperature rise.

[0004] Patent Document 1 describes a spindle device (bearing device) that includes a plurality of first radial oil passages formed in an outer ring positioning member, a full circumferential groove communicating with the plurality of first radial oil passages, and a second radial oil passage formed in the housing that communicates with an oil drain hole in the housing and the full circumferential groove, respectively. This allows the lubricating oil to be discharged from the oil drain hole regardless of the rotational position, and prevents abnormal heat generation due to an excess amount of lubricant inside the bearing. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-2622 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, conventional bearing devices are configured to push the lubricant out of the bearing by supplying more lubricant into the bearing space already filled with lubricant through continuous supply. Therefore, the force for discharging the lubricant out of the bearing is small. Therefore, it is insufficient to fill the storage space formed in the outer ring spacer with the discharged lubricant, and there is a limit to how long the lubricant can be continuously replenished.

[0007] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide an easy-to-maintain bearing device and spindle device that can efficiently discharge lubricant supplied to the bearings, maintain good lubrication conditions, enable stable continuous operation for long periods of time, and extend the life of the bearings. [Means for solving the problem]

[0008] The above object of the present invention can be achieved by the following configuration. (1) A bearing device comprising: a housing; a rolling bearing that rotatably supports a spindle relative to the housing; and an outer ring positioning member that is fitted into the housing and positions an outer ring of the rolling bearing in an axial direction, the bearing device supplying lubricant to an inside of the rolling bearing through a lubricant supply path, At least one side surface of the outer ring is offset toward the center in the axial direction relative to a side surface of the inner ring of the rolling bearing, an opening is formed in an end surface of the outer race positioning member that abuts against the offset side surface, the opening penetrating the outer race positioning member in a radial direction; A bearing device comprising: (2) A spindle device for a machine tool main shaft, the spindle being rotatably supported by the bearing device described above in (1). (3) A spindle device for a high-speed motor, the spindle being rotatably supported by the bearing device described above in (1). Effect of the Invention

[0009] According to the bearing device of the present invention, the lubricant supplied to the bearing can be efficiently discharged, a good lubricated condition can be maintained, stable continuous operation for long periods of time is possible, and the life of the bearing can be extended. Furthermore, according to the spindle device for a machine tool main shaft and the spindle device for a high-speed motor of the present invention, the spindle is rotatably supported by the bearing device described above. This makes it possible to reduce the stirring resistance of the lubricant caused by the rotation of the spindle and to suppress increases in bearing temperature and torque, thereby extending the life of the bearing and facilitating maintenance. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a sectional view showing a spindle device for a machine tool main shaft to which a bearing device according to a first embodiment of the present invention is applied. [Diagram 2] FIG. 2 is an enlarged view of a main portion of the bearing device shown in FIG. [Diagram 3]FIG. 3 is an enlarged cross-sectional view of a rolling bearing in the second row from the axial front among the four rolling bearings assembled back-to-back shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view of a main portion of a bearing device according to a second embodiment of the present invention. [Diagram 5] FIG. 5 is an enlarged cross-sectional view of the rolling bearing shown in FIG. [Figure 6] FIG. 6 is a cross-sectional view of a main portion of a bearing device according to a third embodiment of the present invention. [Figure 7] FIG. 7 is an enlarged cross-sectional view of the rolling bearing shown in FIG. [Figure 8] FIG. 8 is an enlarged cross-sectional view of a rolling bearing according to a first modified example. [Figure 9] FIG. 9 is an enlarged cross-sectional view of a rolling bearing according to a second modified example. [Figure 10] 10(a) and 10(b) are a top view and a front view of the outer race positioning member. [Figure 11] 11(a) and 11(b) are a top view and a front view of an outer race positioning member according to a modified example. [Figure 12] FIG. 12 is an enlarged cross-sectional view of a main portion of a bearing device according to a fourth embodiment of the present invention. [Figure 13] 13(a) and 13(b) are a top view and a front view of the outer race positioning member shown in FIG. [Figure 14] FIG. 14 is an enlarged cross-sectional view of a main portion of a bearing device according to a fifth embodiment of the present invention. [Figure 15] FIG. 15 is an enlarged cross-sectional view of a main portion of a bearing device according to a sixth embodiment of the present invention. [Figure 16] FIG. 16 is an enlarged cross-sectional view of a bearing device according to a seventh embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, bearing devices and spindle devices according to embodiments of the present invention will be described in detail with reference to the drawings. Note that the bearing devices of the embodiments will be described as being applied to spindle devices for machine tool main spindles, but it goes without saying that they can also be applied to spindle devices for high-speed motors.

[0012] (First embodiment) FIG. 1 is a cross-sectional view showing a spindle device 200 for a machine tool main spindle to which a front bearing device 10 according to a first embodiment of the present invention is applied. As shown in Fig. 1, the spindle device 200 is of the motor built-in type. The spindle 60 is rotatably supported relative to the housing 50 by a front bearing device 10 arranged in front of the motor 70 and a rear bearing device 110 arranged behind the motor 70. The front bearing device 10 includes four rolling bearings 20 assembled back to back, and the rear bearing device 110 includes one rolling bearing 120. Of course, the number and combination type of the multiple rolling bearings 20 to be assembled are not limited to this.

[0013] The rear bearing device 110 is a bearing device that includes a rolling bearing 120, which is a cylindrical roller bearing that rotatably supports the spindle 60 relative to the housing 50, outer ring holders 140A, 140B which are outer ring positioning members that are fitted into the housing 50 and position the outer ring 122 of the rolling bearing 120 in the axial direction, and inner ring spacers 130A, 130B that are fitted onto the spindle 60 and position the inner ring 121 of the rolling bearing 120 in the axial direction, and supplies lubricant G to the inside of the rolling bearing 120 via a lubricant supply path 52.

[0014] Fig. 2 is an enlarged view of a main portion of the front bearing device 10 shown in Fig. 1. Fig. 3 is an enlarged cross-sectional view of the second row of rolling bearings 20 from the axial front among the four rolling bearings 20 assembled back-to-back shown in Fig. 2. As shown in Figure 2, the front bearing device 10 of the first embodiment is a bearing device that includes a housing 50, a rolling bearing 20 that rotatably supports a spindle 60 relative to the housing 50, an outer ring spacer 40 and an outer ring holder 40B that are outer ring positioning members that are fitted into the housing 50 to position the outer ring 22 of the rolling bearing 20 in the axial direction, and an inner ring spacer 30 that is fitted onto the spindle 60 to position the inner ring 21 of the rolling bearing 20 in the axial direction, and supplies lubricant G to the inside of the rolling bearing 20 via a lubricant supply path 52.

[0015] A plurality of lubricant supply paths 52 are formed in the housing 50, which communicate from the axial rear of the housing 50 to the oil supply holes 26 of the outer rings 22 of the rolling bearings 20 and the oil supply holes 126 of the outer rings 122 of the rolling bearings 120. A lubricant supply unit 201 is provided on the outside of the housing 50, and an opening 202 for passing piping from the lubricant supply unit 201, or a relay joint for relaying the piping from the lubricant supply unit 201, or the like is provided on the axial rear end face of the housing 50.

[0016] Therefore, the supply of lubricant G to the bearing spaces of the multiple rolling bearings 20 is performed via multiple lubricant supply paths 52 by connecting the lubricant supply part 201 to the opening 202. Also, the supply of lubricant G to the bearing space of the rolling bearing 120 is performed via the lubricant supply path 52, which is configured such that the lubricant supply part 201 is connected to an opening 203 provided in the axial rear end face of the outer ring spacer retainer 140A and includes a communication hole 204 formed in the outer ring retainer 140A.

[0017] As shown in Fig. 3, each of the four rolling bearings 20 assembled back-to-back is an angular contact ball bearing and includes an inner ring 21, an outer ring 22, a plurality of balls 23 that are rolling elements arranged to roll freely between an inner ring raceway surface 21a of the inner ring 21 and an outer ring raceway surface 22a of the outer ring 22, and a cage 24 that rotatably holds the plurality of balls 23. The outer ring 22 has a tapered counterbore 25 on its inner circumferential surface on one axial side (left side in Fig. 3) relative to the outer ring raceway surface 22a, and an oil supply hole 26 that penetrates radially and opens into the counterbore 25 near the outer ring raceway surface 22a. As described later, the axial back side of the outer ring 22 is shortened toward the axial center, making it difficult to guide the cage 24 with the inner peripheral surface of the outer ring 22. Therefore, the guide system for the cage 24 in the first embodiment is a ball guide system guided by balls 23 or an inner ring guide system guided by the inner ring 21.

[0018] In addition, in each rolling bearing 20 of this first embodiment, one side surface (axial end surface on the back side) 22b of the outer ring 22 is offset toward the axial center by a dimension δ from the side surface (axial end surface on the back side) 21b of the inner ring 21. That is, in the rolling bearing 20, the axial positions of the axial end faces on the front side of the outer ring 22 and the inner ring 21 are the same, and the axial positions of the axial end faces on the back side of the outer ring 22 and the inner ring 21 are different, and the width of the outer ring 22 is shorter than the width of the inner ring 21. As a result, the bearing space between the outer peripheral surface of the inner ring 21 and the inner peripheral surface of the outer ring 22 is configured so that the axial back side is open radially outward.

[0019] Furthermore, an opening (drain hole) 41 that penetrates the outer ring spacer 40 or the outer ring retainer 40B in the radial direction is formed in an end face 43 of the outer ring spacer 40 and the outer ring retainer 40B that abut against one side surface 22b of the offset outer ring 22. Further, a storage space 51 capable of storing lubricant G discharged from the inside of the rolling bearing 20 is provided in the housing 50 on the radial outside of the opening 41.

[0020] The storage space 51 is an annular space formed on the outer circumferential side of the opening 41. Therefore, the bearing space of the rolling bearing 20 communicates with the storage space 51 via the portion that opens radially outward on the axial back side of the outer ring 22 and the opening 41.

[0021] In the front bearing device 10 configured in this manner, the lubricant G supplied from the lubricant supply unit 201 is supplied to the rolling bearing 20 via the lubricant supply path 52 and the oil supply hole 26 of the outer ring 22. For example, when the lubricant G is grease, a predetermined amount of grease is periodically replenished at predetermined intervals. The lubricant G supplied to the inside of the rolling bearing 20 lubricates each part of the rolling bearing 20, and a part of it is retained inside the rolling bearing 20. Of the lubricant G retained inside the rolling bearing 20, the lubricant G that is no longer needed is pushed out to the outside of the rolling bearing 20 and discharged.

[0022] In addition, a portion of the unnecessary lubricant G is thrown radially outward from the rolling bearing 20 by the centrifugal force caused by the rotational force of the inner ring 21 and the retainer 24, and is forcibly and continuously discharged into the storage space 51 through the radially outward open portion on the axial back side of the outer ring 22 and the opening 41, and is stored in the storage space 51.

[0023] That is, in the rolling bearing 20, one side surface 22b of the outer ring 22 is offset toward the axial center by a dimension δ from the side surface 21b of the inner ring 21, and a portion that is open radially outward on the axial back surface side of the outer ring 22 is formed. Therefore, the lubricant G that has accumulated inside the rolling bearing 20 can be quickly discharged to the opening 41, and the occurrence of abnormal temperature rise due to the lubricant G re-entering the inner ring raceway surface 21a and the outer ring raceway surface 22a of the rolling bearing 20 can be suppressed.

[0024] In addition, the discharge from the portion open radially outward on the axial back side of the outer ring 22 can balance the supply amount and discharge amount of the lubricant G depending on the rotation speed of the rolling bearing 20. For example, in the case of high-speed rotation, it is necessary to increase the supply amount of the lubricant G to prevent early damage due to depletion of the lubricant G caused by heat generation. However, if the supply amount is increased carelessly, the lubricant G becomes excessive, which may cause unstable temperature rise and abnormal heat generation. However, since the inner ring 21 and the cage 24 rotate at high speed, the centrifugal force is large, and the discharge amount of the lubricant G also increases accordingly, so that even if the supply amount is increased, the amount of the lubricant G remaining inside the rolling bearing 20 does not increase, and an appropriate amount of the lubricant G can be retained inside and near the rolling bearing 20.

[0025] On the other hand, in the case of low rotation speed, even if the supply amount is reduced, the centrifugal force of the inner ring 21 and the cage 24 is small, so the discharge amount of lubricant G does not increase and there is no excess discharge of lubricant G. In this way, by making the width of the outer ring 22 shorter than the width of the inner ring 21 and providing a portion in the bearing space that is open radially outward, the supply amount and discharge amount of lubricant G are appropriately linked according to the rotation speed, and a good lubrication environment is always obtained.

[0026] Either grease or oil is effective as the lubricant G, and heat generation can be suppressed by reducing the agitation resistance. When the storage space 51 is filled with the lubricant G, it is necessary to discharge it to the outside of the front bearing device 10. According to this embodiment, however, a discharge passage (not shown) is provided that connects the storage space 51 in the housing 50 with the outside space, and most of the lubricant G can be discharged by sucking it from the outside, making maintenance easier. In particular, in the case of oil supply lubrication, a discharge passage to the outside space is effective.

[0027] As described above, according to the front bearing device 10 of the first embodiment, the lubricant G supplied to the inside of the rolling bearing 20 is blasted from the portion open radially outward on the axial back side of the outer ring 22 to the outer diameter side by the action of the centrifugal force due to the rotational force of the inner ring 21 and the cage 24, and is stored in the storage space 51 through the opening 41. This reduces the stirring resistance of the lubricant G, suppresses heat generation, maintains a good lubricated state, and as a result, extends the life of the rolling bearing 20. In addition, the magnitude of the centrifugal force blasting the lubricant G changes depending on the rotational speed of the rolling bearing 20, i.e., the inner ring 21 and the cage 24, so that an appropriate lubricant supply according to the rotational speed is possible.

[0028] Furthermore, according to the spindle device 200 for a machine tool main spindle to which the front bearing device 10 of the first embodiment is applied, the spindle 60 of the spindle device for a machine tool main spindle, which rotates at high speed, can be supported by the rolling bearing 20 which has a long life, making maintenance easier. Of course, when the front bearing device 10 of this first embodiment is applied to a spindle device for a high-speed motor, the spindle of the spindle device for the high-speed motor, which rotates at high speed, can be supported by the rolling bearing 20 which has a long life, making maintenance easier.

[0029] Second embodiment Fig. 4 is a cross-sectional view of a main part of a front bearing device 10A according to a second embodiment of the present invention Fig. 5 is an enlarged cross-sectional view of a rolling bearing 20A shown in Fig. 4. As shown in Figure 4, the front bearing device 10A of the second embodiment is a bearing device that includes a housing 50, a rolling bearing 20A, outer ring positioning members such as an outer ring spacer 40 and an outer ring holder 40B, and an inner ring spacer 30, and supplies lubricant G to the inside of the rolling bearing 20A via a lubricant supply path 52.

[0030] As shown in Fig. 5, each of the four rolling bearings 20A assembled back-to-back is an angular contact ball bearing and includes an inner ring 21, an outer ring 22A, a plurality of balls 23 arranged to roll freely between an inner ring raceway surface 21a of the inner ring 21 and an outer ring raceway surface 22a of the outer ring 22A, and a cage 24. The outer ring 22A has a tapered counterbore 25 on its inner circumferential surface on one axial side (left side in Fig. 5) relative to the outer ring raceway surface 22a, and is provided with an oil supply hole 26 that penetrates radially and opens into the counterbore 25 near the outer ring raceway surface 22a.

[0031] In addition, in each rolling bearing 20A of this second embodiment, one side surface (axial end surface on the front side) 22c of the outer ring 22A is offset by σ toward the axial center from the side surface (axial end surface on the front side) 21c of the inner ring 21. That is, in the rolling bearing 20A, the axial positions of the axial end faces on the back side of the outer ring 22A and the inner ring 21 are the same, and the axial positions of the axial end faces on the front side of the outer ring 22A and the inner ring 21 are different, and the width of the outer ring 22A is shorter than the width of the inner ring 21. As a result, the bearing space between the outer peripheral surface of the inner ring 21 and the inner peripheral surface of the outer ring 22A is configured so that the axial front side is open radially outward.

[0032] Furthermore, an opening 41 that penetrates the outer ring spacer 40 or the outer ring retainer 40B in the radial direction is formed in an end face 44 of the outer ring spacer 40 and the outer ring retainer 40B that abut against one side surface 22c of the offset outer ring 22A. Moreover, a storage space 51 capable of storing lubricant G discharged from the inside of the rolling bearing 20A is provided in the housing 50 on the radially outer side of the opening 41. Therefore, the bearing space of the rolling bearing 20A communicates with the storage space 51 via a portion that opens radially outward on the axial front side of the outer ring 22A and the opening 41.

[0033] In the front bearing device 10A configured in this manner, the lubricant G supplied from the lubricant supply unit 201 is supplied to the rolling bearing 20A via the lubricant supply path 52 and the oil supply hole 26 of the outer ring 22A. For example, when the lubricant G is grease, a predetermined amount of grease is periodically replenished at a predetermined interval. The lubricant G supplied to the inside of the rolling bearing 20A lubricates each part of the rolling bearing 20A, and a part of the lubricant G is retained inside the rolling bearing 20A. Of the lubricant G retained inside the rolling bearing 20A, the unnecessary lubricant G is pushed out to the outside of the rolling bearing 20A and discharged.

[0034] In addition, a portion of the unnecessary lubricant G is thrown radially outward from the rolling bearing 20A by the centrifugal force caused by the rotational force of the inner ring 21 and the retainer 24, and is forcibly and continuously discharged into the storage space 51 through the radially outward opening on the axial front side of the outer ring 22A and the opening 41, and is stored in the storage space 51.

[0035] That is, in the rolling bearing 20A, one side surface 22c of the outer ring 22A is offset by σ toward the axial center from the side surface 21c of the inner ring 21, and a portion that is open radially outward on the axial front side of the outer ring 22A is formed. Therefore, the lubricant G that has accumulated inside the rolling bearing 20A can be quickly discharged to the opening 41, and abnormal temperature rise caused by the lubricant G re-entering the inner ring raceway surface 21a and the outer ring raceway surface 22a of the rolling bearing 20A can be suppressed.

[0036] Therefore, similarly to the front bearing device 10 according to the first embodiment, according to the front bearing device 10A according to the second embodiment, the lubricant G supplied to the inside of the rolling bearing 20A is blasted from the part opened radially outward on the axial front side of the outer ring 22A to the outer diameter side by the action of the centrifugal force due to the rotational force of the inner ring 21 and the cage 24, and is stored in the storage space 51 through the opening 41. This reduces the stirring resistance of the lubricant G, suppresses heat generation, maintains a good lubricated state, and as a result, extends the life of the rolling bearing 20A. In addition, the magnitude of the centrifugal force blasting the lubricant G changes depending on the rotational speed of the rolling bearing 20A, i.e., the inner ring 21 and the cage 24, so that the lubricant can be appropriately supplied according to the rotational speed. In addition, since the axial back side of the outer ring 22A is not shortened toward the axial center, the inner peripheral surface of the outer ring 22A can be used to guide the cage 24. Thus, the guide system of the cage 24 in the second embodiment can be an outer ring guide system guided by the inner peripheral surface of the outer ring 22A, in addition to the ball guide system and inner ring guide system.

[0037] Third embodiment Fig. 6 is a cross-sectional view of a main part of a front bearing device 10B according to a third embodiment of the present invention Fig. 7 is an enlarged cross-sectional view of the rolling bearing 20B shown in Fig. 6. As shown in Figure 6, the front bearing device 10B of the third embodiment is a bearing device that includes a housing 50, a rolling bearing 20B, an outer ring spacer 40 and an outer ring holder 40B which are outer ring positioning members, and an inner ring spacer 30, and supplies lubricant G to the inside of the rolling bearing 20B via a lubricant supply path 52.

[0038] 7, each of the four rolling bearings 20B assembled back-to-back is an angular contact ball bearing and includes an inner ring 21, an outer ring 22B, a plurality of balls 23 rollably arranged between the inner ring raceway surface 21a of the inner ring 21 and the outer ring raceway surface 22a of the outer ring 22B, and a cage 24. The outer ring 22B has a tapered counterbore 25 on its inner circumferential surface on one axial side of the outer ring raceway surface 22a, and an oil supply hole 26 that penetrates radially and opens into the counterbore 25 near the outer ring raceway surface 22a.

[0039] In each rolling bearing 20B of the third embodiment, both side surfaces 22b, 22c of the outer ring 22B are offset axially toward the center from both side surfaces 21b, 21c of the inner ring 21 by dimensions δ, σ, respectively. That is, in the rolling bearing 20B, the axial positions of the axial end faces on the back side and front side of the outer ring 22B and the inner ring 21 are different, and the width of the outer ring 22B is shorter than the width of the inner ring 21. As a result, the bearing space between the outer peripheral surface of the inner ring 21 and the inner peripheral surface of the outer ring 22B is configured such that the axial back side and the axial front side are open radially outward.

[0040] Furthermore, openings 41 that penetrate radially through the outer ring spacer 40 or the outer ring retainer 40B are formed in end faces 43, 44 of the outer ring spacer 40 and the outer ring retainer 40B, which abut against both side faces 22b, 22c of the offset outer ring 22B. Moreover, a storage space 51 capable of storing lubricant G discharged from the inside of the rolling bearing 20A is provided in the housing 50 on the radially outer side of the openings 41. Therefore, the bearing space of the rolling bearing 20B communicates with the respective storage spaces 51 via the openings 41 and portions that are open radially outward on the axial back side and axial front side of the outer ring 22A.

[0041] In the front bearing device 10B configured in this manner, the lubricant G supplied from the lubricant supply unit 201 is supplied to the rolling bearing 20B via the lubricant supply path 52 and the oil supply hole 26 of the outer ring 22B. For example, when the lubricant G is grease, a predetermined amount of grease is periodically replenished at a predetermined interval. The lubricant G supplied to the inside of the rolling bearing 20B lubricates each part of the rolling bearing 20B, and a part of the lubricant G is retained inside the rolling bearing 20B. Of the lubricant G retained inside the rolling bearing 20B, the unnecessary lubricant G is pushed out to the outside of the rolling bearing 20B and discharged.

[0042] In addition, a portion of the unnecessary lubricant G is thrown radially outward from the rolling bearing 20B by the centrifugal force caused by the rotational force of the inner ring 21 and the retainer 24, and is forcibly and continuously discharged into each storage space 51 through the radially outwardly open portions and openings 41 on the axial back side and axial front side of the outer ring 22B, and is stored in each storage space 51.

[0043] That is, in the rolling bearing 20B, both side surfaces 22b, 22c of the outer ring 22B are offset toward the axial center by the dimensions δ and σ from both side surfaces 21b, 21c of the inner ring 21, respectively, and portions that are open radially outward are formed on the axial back side and the axial front side of the outer ring 22B. Therefore, the lubricant G that has accumulated inside the rolling bearing 20B can be quickly discharged to the opening 41, and abnormal temperature rise caused by the lubricant G re-entering the inner ring raceway surface 21a and the outer ring raceway surface 22a of the rolling bearing 20B can be suppressed.

[0044] Therefore, similarly to the front bearing device 10 according to the first embodiment, according to the front bearing device 10B according to the third embodiment, the lubricant G supplied to the inside of the rolling bearing 20B is blasted from the radially outwardly opened portions on the axial back side and axial front side of the outer ring 22B to the outer diameter side by the action of the centrifugal force due to the rotational force of the inner ring 21 and the cage 24, and is stored in each storage space 51 through the opening 41. This reduces the stirring resistance of the lubricant G, suppresses heat generation, maintains a good lubricated state, and as a result, extends the life of the rolling bearing 20B. In addition, the magnitude of the centrifugal force blasting the lubricant G changes depending on the rotational speed of the rolling bearing 20B, i.e., the inner ring 21 and the cage 24, so that the lubricant can be appropriately supplied depending on the rotational speed. In addition, the axial back side and the axial front side of the outer ring 22B are shortened toward the axial center, and it is difficult to guide the cage 24 by the inner peripheral surface of the outer ring 22B. Therefore, the guide system of the cage 24 in the third embodiment is a ball guide system or an inner ring guide system.

[0045] In the front bearing devices 10, 10A, 10B of the first to third embodiments described above, the offset dimensions δ, σ of the four rolling bearings 20, 20A, 20B assembled back to back are all set to the same, but if the level of abnormal temperature rise differs depending on the arrangement of the rolling bearings, the offset dimensions δ, σ may be changed as appropriate.

[0046] For example, in a back-to-back assembly of four rolling bearings, if abnormal temperature rises are likely to occur in the first and fourth rows but are rare in the second and third rows, it is possible to make the offset dimensions δ and σ in the first and fourth rows of rolling bearings 20, 20A, 20B larger than the offset dimensions δ and σ in the second and third rows of rolling bearings 20, 20A, 20B.

[0047] It is also possible for one or more of the rolling bearings in the plurality of rolling bearings to have an offset dimension δ (or σ), or for the offset dimension δ (or σ) of one or more of the rolling bearings in the plurality of rolling bearings to vary relative to the offset dimension δ (or σ) of the remaining rolling bearings.

[0048] (Modification of rolling bearing) FIG. 8 is an enlarged cross-sectional view of a rolling bearing 20C according to a first modified example, and FIG. 9 is an enlarged cross-sectional view of a rolling bearing 20D according to a second modified example. As shown in Figure 8, the outer ring 22C of the rolling bearing 20C of the first modified example has a tapered counter bore 25 on its inner surface on one axial side (left side in Figure 8) relative to the outer ring raceway surface 22a, and is provided with an oil supply hole 26 that penetrates radially and opens to the inner surface on the other axial side (right side in Figure 8) closer to the outer ring raceway surface 22a.

[0049] In addition, in the rolling bearing 20C, one side surface (axial end surface on the front side) 22c of the outer ring 22C is offset toward the axial center by σ from the side surface (axial end surface on the front side) 21c of the inner ring 21. That is, in the rolling bearing 20C, the axial positions of the axial end surfaces on the back side (right side in FIG. 8) of the outer ring 22C and the inner ring 21 are the same, and the axial positions of the axial end surfaces on the front side (left side in FIG. 8) of the outer ring 22C and the inner ring 21 are different, and the width of the outer ring 22C is shorter than the width of the inner ring 21. As a result, the bearing space between the outer peripheral surface of the inner ring 21 and the inner peripheral surface of the outer ring 22C is configured so that the axial front side is open radially outward.

[0050] In the rolling bearing 20C according to the first modification, an oil supply hole 26 for supplying lubricant G is provided on the back side of the outer ring 22C. The lubricant G supplied to the inside of the rolling bearing 20C from the oil supply hole 26 provided on the back side of the outer ring 22C lubricates each part of the rolling bearing 20C, and some of the lubricant G is retained inside the rolling bearing 20C. Of the lubricant G retained inside the rolling bearing 20C, some of the lubricant G that is no longer needed is splashed outward in the radial direction of the rolling bearing 20C from a part that is open outward in the radial direction provided on the front side of the outer ring 22C, and is discharged to the opening 41. In addition, the outer ring 22C is provided with an oil supply hole 26 on the axial back side, and it is difficult to guide the cage 24 by the inner peripheral surface of the outer ring 22C. Therefore, the guide system of the cage 24 in this first modified example is a ball guide system or an inner ring guide system.

[0051] As shown in Figure 9, in the rolling bearing 20D of the second modified example, the inner ring 21D has a tapered counter bore 25D on the inner surface on one axial side (left side in Figure 9) of the inner ring raceway surface 21a, and the outer ring 22D has an oil supply hole 26 that penetrates radially and opens to the inner surface on one axial side near the outer ring raceway surface 22a.

[0052] In addition, in the rolling bearing 20D, one side surface (axial end surface on the back side) 22c of the outer ring 22D is offset toward the axial center by σ from the side surface (axial end surface on the back side) 21c of the inner ring 21D. That is, in the rolling bearing 20D, the axial positions of the axial end surfaces on the front side (right side in FIG. 9) of the outer ring 22D and the inner ring 21D are the same, and the axial positions of the axial end surfaces on the back side (left side in FIG. 9) of the outer ring 22D and the inner ring 21D are different, and the width of the outer ring 22D is shorter than the width of the inner ring 21D. As a result, the bearing space between the outer peripheral surface of the inner ring 21D and the inner peripheral surface of the outer ring 22D is configured so that the axial back side is open radially outward. In a rolling bearing 20D according to the second modified example, a counterbore 25D is provided in an inner ring 21D. Since the axial front side of the outer ring 22D is not shortened toward the axial center, the inner peripheral surface of the outer ring 22D can be used to guide the cage 24. Thus, the guide system of the cage 24 in this second modified example can be an outer ring guide system in addition to a ball guide system and an inner ring guide system.

[0053] (Outer ring positioning member) As shown in FIGS. 10(a) and 10(b), the outer ring spacer 40 serving as an outer ring positioning member in the bearing device of this embodiment is formed in an annular shape that is fitted inside the housing 50. A plurality of (eight in this embodiment) openings 41 that penetrate radially are formed in the outer ring spacer 40 and have a circumferential width w by cutting out a portion of the circumferential direction in a rectangular shape in the axial direction from an end face 44 that abuts against the side surface of the outer ring 22. It is desirable that a plurality of openings 41 are formed in the outer ring spacer 40 at equal intervals in the circumferential direction, but it is sufficient that at least one opening is provided.

[0054] 11(a) and 11(b), the opening 41c penetrating in the radial direction can be formed in a semicircular shape. The opening in this embodiment is not limited to these rectangular and semicircular shapes, and various opening shapes can be used as long as the lubricant that is splashed to the outer diameter side from the portion that opens radially outward on at least one axial end face side of the outer ring can be discharged.

[0055] The outer ring positioning member in the bearing device of this embodiment also includes the outer ring holder 40B that is bolted to the front side of the housing 50. Thus, an end face 44 of the outer ring holder 40B that abuts against the side face of the outer ring 22 is also cut out in a rectangular shape in the axial direction, thereby forming a plurality of openings 41 that penetrate in the radial direction.

[0056] (Fourth embodiment) 12 is an enlarged cross-sectional view of a main portion of a front bearing device 10C according to a fourth embodiment of the present invention. As shown in Figure 12, the front bearing device 10C of the fourth embodiment is a bearing device that includes a housing 50A, a rolling bearing 20E that rotatably supports a spindle 60 relative to the housing 50A, an outer ring spacer 40E and an outer ring holder 40F that are outer ring positioning members that are fitted into the housing 50A to position the outer ring 22E of the rolling bearing 20E in the axial direction, and an inner ring spacer 30 that is fitted onto the spindle 60 to position the inner ring 21 of the rolling bearing 20E in the axial direction, and supplies lubricant G to the inside of the rolling bearing 20E via a lubricant supply path 52.

[0057] Each rolling bearing 20E is an angular ball bearing and includes an inner ring 21, an outer ring 22E, a plurality of balls 23 which are rolling elements arranged freely to roll between the inner ring raceway surface 21a of the inner ring 21 and the outer ring raceway surface 22a of the outer ring 22E, and a retainer 24 which holds the plurality of balls 23 freely rotatably.

[0058] The outer ring 22E has a tapered counterbore 25 on its inner peripheral surface on one axial side (left side in FIG. 12) of the outer ring raceway surface 22a. One side surface (axial end surface on the front side) 22c of the outer ring 22E is offset σ toward the axial center from the side surface (axial end surface on the front side) 21c of the inner ring 21.

[0059] That is, in the rolling bearing 20E, the axial positions of the axial end faces on the back side of the outer ring 22E and the inner ring 21 are the same, and the axial positions of the axial end faces on the front side of the outer ring 22E and the inner ring 21 are different, and the width of the outer ring 22E is shorter than the width of the inner ring 21. As a result, the bearing space between the outer peripheral surface of the inner ring 21 and the inner peripheral surface of the outer ring 22E is configured so that the axial front side is open radially outward.

[0060] 13, an opening 41 that penetrates the outer ring spacer 40E (outer ring holder 40F) in the radial direction is formed in an end face 44 of the outer ring spacer 40E (outer ring holder 40F) that abuts against one side surface 22c of the offset outer ring 22E. The outer ring spacer 40E (outer ring holder 40F) also has an oil supply hole 42 that penetrates in the radial direction and opens near the counter bore 25.

[0061] In the front bearing device 10C configured in this manner, the lubricant G made of grease supplied from the lubricant supply section 201 is supplied to the rolling bearing 20E via the lubricant supply path 52 and the oil supply hole 42 of the outer ring spacer 40E. The lubricant G supplied to the inside of the rolling bearing 20E lubricates each part of the rolling bearing 20E, and a part of the lubricant G is retained inside the rolling bearing 20E. Of the lubricant G retained inside the rolling bearing 20E, the lubricant G that is no longer needed is pushed out to the outside of the rolling bearing 20E and discharged.

[0062] In addition, a portion of the unnecessary lubricant G is thrown radially outward from the rolling bearing 20E by the centrifugal force caused by the rotational force of the inner ring 21 and the retainer 24, and is forcibly and continuously discharged into the storage space 51 through the radially outward open portion on the axial front side of the outer ring 22E and the opening 41, and is stored in the storage space 51.

[0063] That is, in the rolling bearing 20E, one side surface 22c of the outer ring 22E is offset toward the axial center by a dimension σ from the side surface 21c of the inner ring 21, and a portion that is open radially outward on the axial front side of the outer ring 22E is formed. Therefore, the lubricant G that has accumulated inside the rolling bearing 20E can be quickly discharged to the opening 41, and the occurrence of abnormal temperature rise due to the lubricant G re-entering the inner ring raceway surface 21a and the outer ring raceway surface 22a of the rolling bearing 20E can be suppressed.

[0064] Therefore, similarly to the front bearing device 10 according to the first embodiment, according to the front bearing device 10C according to the fourth embodiment, the lubricant G supplied to the inside of the rolling bearing 20E is flicked outward from the portion that opens radially outward on the axial front side of the outer ring 22E by the action of the centrifugal force due to the rotational force of the inner ring 21 and the cage 24, and is stored in each storage space 51 through the opening 41. This reduces the stirring resistance of the lubricant G, suppresses heat generation, maintains a good lubricated state, and as a result, extends the life of the rolling bearing 20E. In addition, since the axial back side of the outer ring 22E is not shortened toward the axial center, the inner peripheral surface of the outer ring 22E can be used to guide the cage 24. Therefore, the guide system of the cage 24 in the fourth embodiment can be an outer ring guide system in addition to a ball guide system and an inner ring guide system.

[0065] Fifth embodiment FIG. 14 is an enlarged cross-sectional view of a main portion of a front bearing device 10D according to a fifth embodiment of the present invention. As shown in Figure 14, the front bearing device 10D of the fifth embodiment is a bearing device that includes a housing 50B, a rolling bearing 20F, outer ring spacers 40, 40G which are outer ring positioning members, and an inner ring spacer 30, and supplies lubricant G to the inside of the rolling bearing 20F via a lubricant supply path 52.

[0066] Each rolling bearing 20F is an angular ball bearing and includes an inner ring 21, an outer ring 22F, a plurality of balls 23 which are rolling elements arranged freely to roll between the inner ring raceway surface 21a of the inner ring 21 and the outer ring raceway surface 22a of the outer ring 22F, and a retainer 24 which holds the plurality of balls 23 freely rotatably.

[0067] The outer ring 22F has a tapered counterbore 25 on its inner peripheral surface on one axial side (left side in FIG. 14) of the outer ring raceway surface 22a. In addition, both side surfaces 22b, 22c of the outer ring 22F are offset axially toward the center by dimensions δ and σ from both side surfaces 21b, 21c of the inner ring 21, respectively. That is, in the rolling bearing 20F, the axial positions of the axial end faces on the back side and front side of the outer ring 22F and the inner ring 21 are different, and the width of the outer ring 22F is shorter than the width of the inner ring 21. As a result, the bearing space between the outer peripheral surface of the inner ring 21 and the inner peripheral surface of the outer ring 22F is configured such that the axial back side and the axial front side are open radially outward.

[0068] Furthermore, openings 41 that penetrate the outer ring spacer 40G in the radial direction are formed in end faces 43, 44 of the outer ring spacer 40G that abut against both side faces 22b, 22c of the offset outer ring 22F. Also, an oil supply hole 45 that supplies lubricant G from the side face of the adjacent rolling bearing 20F is provided in the axial center of the outer ring spacer 40G.

[0069] In the front bearing device 10D configured in this manner, the lubricant G consisting of oil-air supplied from the lubricant supply section 201 is supplied to the rolling bearing 20F via the lubricant supply path 52 and the oil supply hole 45 of the outer ring spacer 40G. The lubricant G supplied to the inside of the rolling bearing 20F lubricates each part of the rolling bearing 20F, and a part of the lubricant G is retained inside the rolling bearing 20F. Of the lubricant G retained inside the rolling bearing 20F, the lubricant G that is no longer needed is pushed out to the outside of the rolling bearing 20F and discharged.

[0070] In addition, a portion of the unnecessary lubricant G is thrown radially outward from the rolling bearing 20F by the centrifugal force caused by the rotational force of the inner ring 21 and the retainer 24, and is forcibly and continuously discharged into each storage space 51 through the radially outwardly open portions and openings 41 on the axial back side and axial front side of the outer ring 22F, and is stored in each storage space 51.

[0071] That is, in the rolling bearing 20F, both side surfaces 22b, 22c of the outer ring 22F are offset toward the axial center by the dimensions δ and σ from both side surfaces 21b, 21c of the inner ring 21, respectively, and portions that are open radially outward are formed on the axial back side and the axial front side of the outer ring 22F. Therefore, the lubricant G that has accumulated inside the rolling bearing 20F can be quickly discharged to the opening 41, and the occurrence of abnormal temperature rise due to the lubricant G re-entering the inner ring raceway surface 21a and the outer ring raceway surface 22a of the rolling bearing 20F can be suppressed.

[0072] Therefore, similarly to the front bearing device 10 according to the first embodiment, according to the front bearing device 10D of the fifth embodiment, the lubricant G supplied to the inside of the rolling bearing 20F is flicked outward from the radially outwardly opened portions on the axial back side and axial front side of the outer ring 22F by the action of the centrifugal force due to the rotational force of the inner ring 21 and the cage 24, and is stored in each storage space 51 through the opening 41. This reduces the stirring resistance of the lubricant G, suppresses heat generation, maintains a good lubricated state, and as a result, extends the life of the rolling bearing 20F. In addition, the axial back side and the axial front side of the outer ring 22F are shortened toward the axial center, and it is difficult to guide the cage 24 by the inner peripheral surface of the outer ring 22F. Therefore, the guide system of the cage 24 in the fifth embodiment is a ball guide system or an inner ring guide system.

[0073] Sixth embodiment FIG. 15 is an enlarged cross-sectional view of a main portion of a front bearing device 10E according to a sixth embodiment of the present invention. As shown in Figure 15, the front bearing device 10E of the sixth embodiment is a bearing device that includes a housing 50C, a rolling bearing 20G, an outer ring spacer 40G which is an outer ring positioning member, and an inner ring spacer 30, and supplies lubricant G to the inside of the rolling bearing 20G via a lubricant supply path 52.

[0074] Each rolling bearing 20G is an angular ball bearing and includes an inner ring 21G, an outer ring 22G, a plurality of balls 23 arranged freely rollable between the inner ring raceway surface 21a of the inner ring 21G and the outer ring raceway surface 22a of the outer ring 22F, and a retainer 24.

[0075] The outer ring 22G has a tapered counterbore 25 on its inner peripheral surface on the other axial side (right side in FIG. 15) relative to the outer ring raceway surface 22a. A side surface 22c of the outer ring 22G is offset by a dimension σ toward the axial center from a side surface 21c of the inner ring 21G. A side surface 22b of the outer ring 22G is offset by a dimension δ toward the axial center from a side surface 21b of the inner ring 21G that extends to the back side (left side in FIG. 15) so as to face a circumferential groove 47 formed on the inner peripheral surface of an outer ring spacer 40G, which will be described later. That is, in the rolling bearing 20G, the axial positions of the axial end faces on the back side and front side of the outer ring 22G and the inner ring 21G are different, and the width of the outer ring 22G is shorter than the width of the inner ring 21G. As a result, the bearing space between the outer peripheral surface of the inner ring 21G and the inner peripheral surface of the outer ring 22G is configured so that the axial back side and the axial front side are open radially outward.

[0076] Furthermore, openings 41 that penetrate the outer ring spacer 40G in the radial direction are formed in end faces 43, 44 of the outer ring spacer 40G that abut against both side faces 22b, 22c of the offset outer ring 22F. Also, an oil supply hole 46 that supplies lubricant G to the outer peripheral surface of the inner ring 21G of the adjacent rolling bearing 20G, and a circumferential groove 47 that communicates with the oil supply hole 46 are provided in the axial center of the outer ring spacer 40G. The circumferential groove 47 is formed in the inner peripheral surface of the outer ring spacer 40G so as to face the extended portion of the inner ring 21G.

[0077] In the front bearing device 10E configured in this manner, lubricant G consisting of oil-air supplied from the lubricant supply section 201 is supplied to the outer peripheral surface of the inner ring 21G via the lubricant supply path 52, the oil supply hole 46 of the outer ring spacer 40G, and the circumferential groove 47. The lubricant G supplied from the outer circumferential surface of the inner ring 21G to the inside of the rolling bearing 20G lubricates each part of the rolling bearing 20G, and a part of the lubricant G is retained inside the rolling bearing 20G. Of the lubricant G retained inside the rolling bearing 20G, the lubricant G that is no longer needed is pushed out and discharged to the outside of the rolling bearing 20G.

[0078] In addition, a portion of the unnecessary lubricant G is thrown radially outward from the rolling bearing 20G by the centrifugal force caused by the rotational force of the inner ring 21G and the retainer 24, and is forcibly and continuously discharged into each storage space 51 through the radially outwardly open portions and openings 41 on the axial back side and axial front side of the outer ring 22G, and is stored in each storage space 51.

[0079] That is, in the rolling bearing 20G, both side surfaces 22b, 22c of the outer ring 22G are offset toward the axial center by the dimensions δ and σ from both side surfaces 21b, 21c of the inner ring 21G, respectively, and portions that are open radially outward are formed on the axial back side and the axial front side of the outer ring 22G. Therefore, the lubricant G that has accumulated inside the rolling bearing 20G can be quickly discharged to the opening 41, and the occurrence of abnormal temperature rise due to the lubricant G re-entering the inner ring raceway surface 21a and the outer ring raceway surface 22a of the rolling bearing 20G can be suppressed.

[0080] Therefore, similarly to the front bearing device 10 according to the first embodiment, according to the front bearing device 10E of the sixth embodiment, the lubricant G supplied to the inside of the rolling bearing 20G is flicked outward from the radially outwardly opened portions on the axial back side and axial front side of the outer ring 22G by the action of the centrifugal force due to the rotational force of the inner ring 21G and the cage 24, and is stored in each storage space 51 through the opening 41. This reduces the stirring resistance of the lubricant G, suppresses heat generation, maintains a good lubricated state, and as a result, extends the life of the rolling bearing 20G. In addition, the outer ring 22G has its axial back side and axial front side shortened toward the axial center, making it difficult to guide the cage 24 with the inner peripheral surface of the outer ring 22G. Therefore, the guide system of the cage 24 in the sixth embodiment is a ball guide system or an inner ring guide system.

[0081] Seventh embodiment FIG. 16 is an enlarged cross-sectional view of a rear bearing device 110A according to a seventh embodiment of the present invention. As shown in Figure 16, the rear bearing device 110A of the seventh embodiment is a bearing device that includes a rolling bearing 120A that rotatably supports the spindle 60 relative to the housing 50, outer ring holders 140C, 140D that are outer ring positioning members, and inner ring spacers 130A, 130B, and supplies lubricant G to the inside of the rolling bearing 120A via a lubricant supply path 152.

[0082] The rolling bearing 120A is a cylindrical roller bearing and includes an inner ring 121 with double ribs, an outer ring 122 without a rib, a plurality of rollers 123 that are rolling elements arranged to roll freely between an inner ring raceway surface 121a of the inner ring 121 and an outer ring raceway surface 122a of the outer ring 122, and a cage (not shown). The outer ring 122 has an oil supply hole 126 that penetrates radially and opens forward in the inner circumferential surface of the outer ring 122.

[0083] In the rolling bearing 120A of the seventh embodiment, one side surface (rear axial end surface) 122b of the outer ring 122 is offset from the side surface 121b of the inner ring 121 toward the center in the axial direction by a dimension δ. That is, in the rolling bearing 120A, the axial positions of the front axial end faces of the outer ring 122 and the inner ring 121 are the same, and the axial positions of the rear axial end faces of the outer ring 122 and the inner ring 121 are different, and the width of the outer ring 122 is shorter than the width of the inner ring 121. As a result, the bearing space between the outer peripheral surface of the inner ring 121 and the inner peripheral surface of the outer ring 122 is configured so that the axial rear side (the right side in FIG. 16) is open radially outward.

[0084] Furthermore, an opening (drain hole) 141 that penetrates the outer ring holder 140C in the radial direction is formed in an end face 143 of the outer ring holder 140C that abuts against one side face 122b of the offset outer ring 122. Also, outer ring holder 140D on the radial outside of opening 141 is provided with a storage space 151 that can store lubricant G discharged from the inside of rolling bearing 120A.

[0085] The storage space 151 is an annular space formed on the outer circumferential side of the opening 141. Therefore, the bearing space of the rolling bearing 120A communicates with the storage space 151 via the portion of the outer ring 122 on the axial rear side that is open radially outward and the opening 141.

[0086] In the rear bearing device 110A configured in this manner, the lubricant G supplied from the lubricant supply unit 201 is supplied to the rolling bearing 120A via the lubricant supply path 152 and the oil supply hole 126 of the outer ring 122. For example, when the lubricant G is grease, a predetermined amount of grease is periodically replenished at a predetermined interval. The lubricant G supplied to the inside of the rolling bearing 120A lubricates each part of the rolling bearing 120A, and a part of the lubricant G is retained inside the rolling bearing 120A. Of the lubricant G retained inside the rolling bearing 120A, the unnecessary lubricant G is pushed out to the outside of the rolling bearing 120A and discharged.

[0087] In addition, a portion of the unnecessary lubricant G is thrown radially outward from the rolling bearing 120A by the centrifugal force caused by the rotational force of the inner ring 121 and the retainer, and is forcibly and continuously discharged into the storage space 151 through the radially outward open portion on the axial rear side of the outer ring 122 and the opening 141, and is stored in the storage space 151.

[0088] That is, in the rolling bearing 120A, one side surface 122b of the outer ring 122 is offset by δ toward the axial center from the side surface 121b of the inner ring 121, and a portion that is open radially outward is formed on the axial rear side of the outer ring 122. Therefore, the lubricant G that has accumulated inside the rolling bearing 120A can be quickly discharged to the opening 141, and the occurrence of abnormal temperature rise due to the lubricant G re-entering the inner ring raceway surface 121a and the outer ring raceway surface 122a of the rolling bearing 120A can be suppressed.

[0089] Therefore, similarly to the front bearing device 10 according to the first embodiment, according to the rear bearing device 110A according to the seventh embodiment, the lubricant G supplied to the inside of the rolling bearing 120A is blasted from the part opened radially outward at the axial rear side of the outer ring 122 to the outer diameter side by the centrifugal force caused by the rotational force of the inner ring 121 and the cage, and is stored in the storage space 151 through the opening 141. This reduces the stirring resistance of the lubricant G, suppresses heat generation, and maintains a good lubricated state, resulting in a longer life of the rolling bearing 120A. In addition, the magnitude of the centrifugal force blasting the lubricant G changes depending on the rotational speed of the rolling bearing 120A, i.e., the inner ring 121 and the cage, so that the lubricant can be appropriately supplied according to the rotational speed.

[0090] As with the rolling bearings in each of the above-mentioned embodiments, it goes without saying that modifications can be made as appropriate by offsetting both side surfaces 122b, 122c of the outer ring 122 in rolling bearing 120A by dimensions δ and σ respectively toward the axial center from both side surfaces 121b, 121c of the inner ring 121, by opening the oil supply hole 126 of the outer ring 122 on the front side of the outer ring 122, or by changing the oil supply structure for lubricant G to rolling bearing 120A.

[0091] The present invention is not limited to the above-described embodiment, and can be appropriately modified, improved, etc. In addition, the material, shape, size, number, arrangement location, etc. of each component in the above-described embodiment are arbitrary as long as the present invention can be achieved, and are not limited.

[0092] Here, the features of the embodiments of the bearing device and spindle device according to the present invention described above will be briefly summarized and listed in the following [1] to [4]. [1] A bearing device (front bearing device 10, 10A, 10B, 10C, 10D, 10E, rear bearing device 110A) comprising: a housing (50, 50A, 50B, 50C); a rolling bearing (20, 20A, 20B, 20C, 20D, 20E, 20F, 20G, 120A) that rotatably supports a spindle (60) relative to the housing; and an outer ring positioning member (outer ring spacer 40, outer ring holder 40B, 140C) that is fitted into the housing and axially positions an outer ring (22, 22A, 22B, 22C, 22D, 22E, 22F, 22G, 122) of the rolling bearing, the bearing device supplying a lubricant (G) to an inside of the rolling bearing via a lubricant supply path (52, 152), At least one side surface (22b) of the outer ring is offset toward the center in the axial direction with respect to a side surface (21b) of the inner ring (21) of the rolling bearing, An opening (41, 141) that penetrates the outer race positioning member in the radial direction is formed in an end face (43, 44, 143) of the outer race positioning member that abuts against the offset side surface. The bearing device (front bearing device 10, 10A, 10B, 10C, 10D, 10E, rear bearing device 110A) is characterized by the above.

[0093] According to the configuration [1], the lubricant (G) supplied to the inside of the rolling bearing (20, 20A, 20B, 20C, 20D, 20E, 20F, 20G, 120A) is partly thrown outward through the openings (41, 141) and the radially outwardly open portion on the axial back side of the outer ring (22, 22A, 22B, 22C, 22D, 22E, 22F, 22G, 122) by the centrifugal force caused by the rotational force of the inner ring and the cage. This reduces the stirring resistance of the lubricant (G) and suppresses heat generation, maintaining a good lubricated state, and as a result, the life of the rolling bearing (20, 20A, 20B, 20C, 20D, 20E, 20F, 20G, 120A) is extended. In addition, since the magnitude of the centrifugal force that repels the lubricant (G) changes depending on the rotational speed of the rolling bearings (20, 20A, 20B, 20C, 20D, 20E, 20F, 20G, 120A), i.e., the inner ring and the retainer, it becomes possible to supply lubricant appropriately according to the rotational speed.

[0094] [2] A storage space (51, 151) capable of storing the lubricant (G) discharged from the inside of the rolling bearing (20, 20A, 20B, 20C, 20D, 20E, 20F, 20G, 120A) is provided in the housing (50, 50A, 50B, 50C) on the radially outer side of the opening (41, 141). The bearing device (front bearing device 10, 10A, 10B, 10C, 10D, 10E, rear bearing device 110A) according to the above item [1] is characterized in that

[0095] According to the above configuration [2], a portion of the lubricant (G) that has been splashed radially outward from the rolling bearing (20, 20A, 20B, 20C, 20D, 20E, 20F, 20G, 120A) is forcibly and continuously discharged into the storage space (51, 151) through the portion that opens radially outward on the axial back side of the outer ring (22, 22A, 22B, 22C, 22D, 22E, 22F, 22G, 122) and the opening (41, 141), and is stored in the storage space (51, 151).

[0096] [3] A spindle device (200) for a machine tool main shaft, in which a spindle (60) is rotatably supported by the bearing device (front bearing device 10, 10A, 10B, 10C, 10D, 10E, rear bearing device 110A) described in [1] or [2] above.

[0097] According to the configuration of [3] above, The spindle (60) of the spindle device for the main shaft of a machine tool, which rotates at high speed, can be supported by the rolling bearings (20, 20A, 20B, 20C, 20D, 20E, 20F, 20G, 120A) with a long life, making maintenance easier.

[0098] [4] A spindle device for a high-speed motor, the spindle being rotatably supported by the bearing device (front bearing device 10, 10A, 10B, 10C, 10D, 10E, rear bearing device 110A) described in [1] or [2] above.

[0099] According to the above configuration [4], the spindle (60) of the spindle device for a high-speed motor, which rotates at high speed, can be supported by rolling bearings (20, 20A, 20B, 20C, 20D, 20E, 20F, 20G, 120A) with a long life, making maintenance easier. [Explanation of symbols]

[0100] 10 Front bearing device (bearing device) 20 Rolling bearings 22 Outer ring 40 Outer ring spacer (outer ring positioning member) 50 Housing 40B Outer ring holder (outer ring positioning member) 52 Lubricant supply path 60 Spindle 200 Spindle device for machine tool main shaft G. Lubricant

Claims

1. A bearing device comprising: a housing; a rolling bearing that rotatably supports a spindle relative to the housing; and an outer ring positioning member that is fitted into the housing and positions an outer ring of the rolling bearing in an axial direction, the bearing device supplying a lubricant to an inside of the rolling bearing through a lubricant supply path, At least one side surface of the outer ring is offset toward the center in the axial direction relative to a side surface of the inner ring of the rolling bearing, An opening is formed in an end surface of the outer race positioning member that abuts against the offset side surface, the opening penetrating the outer race positioning member in a radial direction. A bearing device comprising:

2. A storage space capable of storing the lubricant discharged from the inside of the rolling bearing is provided in the housing radially outside of the opening.

2. The bearing device according to claim 1.

3. 3. A spindle device for a machine tool main shaft, the spindle being rotatably supported by the bearing device according to claim 1 or 2.

4. 3. A spindle device for a high-speed motor, the spindle being rotatably supported by the bearing device according to claim 1 or 2.

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