BEARING DEVICE, AND SPIDLE DEVICE FOR MACHINE TOOL

Abstract

Provided is a bearing device (1) wherein an outer ring (12) of an angular contact ball bearing (10) has at least one supply hole (15) for supplying a lubricating oil, and an outer ring spacer (30) comprises, on the inner peripheral surface thereof, a tapered surface (32) which increases in diameter with the distance from an axial end surface (31) contacting the outer ring (12), the outer ring spacer (30) also comprising a discharge hole (34) which passes therethrough in the radial direction and through which the lubricating oil is discharged. Further, the inner diameter dimension (D.sub.31) of the axial end surface (31) of the outer ring spacer (30) is set to be equal to or larger than the inner diameter dimension (D.sub.12e) of an axial other side end surface (12e) of the outer ring (12) contacting the outer ring spacer (30).

Claims

1. A bearing device comprising: a rolling bearing comprising: an inner ring having an inner ring raceway groove formed in an outer peripheral surface; an outer ring having an outer ring raceway groove formed in an inner peripheral surface and a counterbore formed at one axial side of the outer ring raceway groove; and a plurality of rolling elements arranged rollably between the inner ring raceway groove and the outer ring raceway groove, wherein the outer ring has at least one supply hole which penetrates from an outer peripheral surface thereof to the inner peripheral surface thereof in a radial direction and which is configured to supply lubricating oil, and wherein the rolling bearing is lubricated by the lubricating oil; and a counterbore-opposite-side peripheral component which is arranged adjacent to the outer ring at a counterbore-opposite-side, wherein the counterbore-opposite-side is the other axial side of the outer ring raceway groove, wherein the counterbore-opposite-side peripheral component comprises: a tapered surface which is formed on an inner peripheral surface thereof and which has a diameter increasing with a distance from an axial end face thereof in contact with the outer ring; and a discharge hole which penetrates therethrough in the radial direction and which is configured to discharge the lubricating oil, and wherein an inner diameter dimension of the axial end face of the counterbore-opposite-side peripheral component is equal to or larger than an inner diameter dimension of the other axial end face of the outer ring in contact with the counterbore-opposite-side peripheral component.

2. The bearing device according to claim 1, wherein the inner peripheral surface of the outer ring has a groove shoulder formed at the other axial side of the outer ring raceway groove, and wherein the inner diameter dimension of the other axial end face of the outer ring is defined by a uniform inner diameter dimension of the groove shoulder.

3. The bearing device according to claim 1 further comprising an inner ring-side peripheral component which is arranged to be adjacent to the inner ring at the other axial side, wherein the inner ring-side peripheral component has a tapered outer peripheral surface which faces the tapered surface of the counterbore-opposite-side peripheral component and which forms a labyrinth between the tapered surface of the counterbore-opposite-side peripheral component and the tapered outer peripheral surface.

4. The bearing device according to claim 1 further comprising a counterbore-side peripheral component which is arranged to be adjacent to the outer ring at a counterbore-side, wherein the counterbore has an inclined surface of which a diameter gradually increases toward one axial end face of the outer ring, wherein the counterbore-side peripheral component has a cutout which is formed in the radial direction at an axial end face in contact with the outer ring, and wherein an inner diameter dimension of the axial end face of the counterbore-side peripheral component is equal to or larger than an inner diameter dimension of the one axial end face of the outer ring in contact with the counterbore-side peripheral component.

5. A bearing device comprising: a rolling bearing comprising: an inner ring having an inner ring raceway groove formed in an outer peripheral surface; an outer ring having an outer ring raceway groove formed in an inner peripheral surface and a counterbore formed at one axial side of the outer ring raceway groove; and a plurality of rolling elements arranged rollably between the inner ring raceway groove and the outer ring raceway groove, wherein the outer ring has at least one supply hole which penetrates from an outer peripheral surface thereof to the inner peripheral surface thereof in a radial direction and which is configured to supply lubricating oil, and wherein the rolling bearing is lubricated by the lubricating oil; and a counterbore-side peripheral component which is arranged to be adjacent to the outer ring at a counterbore-side, wherein the counterbore has an inclined surface of which a diameter gradually increases toward one axial end face of the outer ring, wherein the counterbore-side peripheral component has a cutout which is formed in the radial direction at an axial end face in contact with the outer ring, and wherein an inner diameter dimension of the axial end face of the counterbore-side peripheral component is equal to or larger than an inner diameter dimension of the one axial end face of the outer ring in contact with the counterbore-side peripheral component.

6. A spindle device for machine tool comprising the bearing device according to claim 1.

7. A spindle device for machine tool comprising the bearing device according to claim 2.

8. A spindle device for machine tool comprising the bearing device according to claim 3.

9. A spindle device for machine tool comprising the bearing device according to claim 4.

10. A spindle device for machine tool comprising the bearing device according to claim 5.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0041] FIG. 1 is a sectional view depicting a bearing device in accordance with a first embodiment of the present invention.

[0042] FIG. 2 is a sectional view depicting a bearing device in accordance with a first modified embodiment of the first embodiment of the present invention.

[0043] FIG. 3 is a sectional view depicting a bearing device in accordance with a second modified embodiment of the first embodiment of the present invention.

[0044] FIG. 4 is a sectional view depicting a bearing device in accordance with a third modified embodiment of the first embodiment of the present invention.

[0045] FIG. 5 is a sectional view depicting a bearing device in accordance with a fourth modified embodiment of the first embodiment of the present invention.

[0046] FIG. 6 depicts a bearing device in accordance with a second embodiment of the present invention.

[0047] FIG. 7 is a sectional view depicting a bearing device in accordance with a first modified embodiment of the second embodiment of the present invention.

[0048] FIG. 8 is a sectional view depicting a bearing device in accordance with a second modified embodiment of the second embodiment of the present invention.

[0049] FIG. 9 is a sectional view depicting a bearing device in accordance with a third modified embodiment of the second embodiment of the present invention.

[0050] FIG. 10 is a sectional view depicting a bearing device in accordance with a modified embodiment of the present invention.

[0051] FIGS. 11A and 11B are sectional views depicting oil/air lubrication of the related art in which a nozzle piece is used.

[0052] FIG. 12 is a sectional view of a ball bearing of oil/air lubrication of an outer ring oil supply specification.

[0053] FIG. 13 is a sectional view depicting a spindle where oil/air lubrication of an outer ring oil supply specification is performed (upper half) and is a sectional view depicting a spindle where oil/air lubrication using a nozzle piece is performed (lower half).

[0054] FIG. 14A is a sectional view depicting a ball bearing of the outer ring oil supply specification having an oil discharge structure in accordance with the related art, and FIG. 14B is a side view thereof.

[0055] FIG. 15A is a sectional view depicting a ball bearing of the outer ring oil supply specification having another oil discharge structure in accordance with the related art, and FIG. 15B is a side view thereof.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0056] Hereinafter, a bearing device and a spindle device for machine tool in accordance with each embodiment of the present invention will be described in detail with reference to the drawings.

First Embodiment

[0057] As shown in FIG. 1, a bearing device 1 in accordance with a first embodiment can be applied to a spindle device for machine tool, and includes at least an angular ball bearing (rolling bearing) 10, and an outer ring spacer (counterbore-opposite-side peripheral component) 30.

[0058] The angular ball bearing 10 includes an inner ring 11 having a circular arc-shaped inner ring raceway groove 11a formed in an outer peripheral surface, an outer ring 12 having a circular arc-shaped outer ring raceway groove 12a formed in an inner peripheral surface, a plurality of balls (rolling elements) 13 each of which has a predetermined contact angle and is arranged rollably between the inner ring raceway groove 11a and the outer ring raceway groove 12a, and a cage 14 configured to keep the plurality of balls 13. An inner peripheral surface of one axial side of the outer ring 12 is formed with a counterbore 12b, and an inner peripheral surface of the other axial side is formed with a groove shoulder 12c. The counterbore 12b has an inclined surface of which a diameter gradually increases toward one axial end face 12d of the outer ring 12. Also, the groove shoulder 12c has a uniform inner diameter dimension from a boundary position with the outer ring raceway groove 12a of the outer ring 12 to the other axial end face 12e of the outer ring. The cage 14 is an outer ring guide type, and specifically, is guided by an inner peripheral surface of the groove shoulder 12c of the outer ring 12.

[0059] The angular ball bearing 10 is an outer ring oil supply-type bearing, and the outer ring 12 has a supply hole 15 penetrating from the outer peripheral surface to the inner peripheral surface in a radial direction. Also, the outer peripheral surface of the outer ring 12 is formed with a concave groove 16 which is formed along a circumferential direction and which is configured to communicate with the supply hole 15. Thereby, in the angular ball bearing 10, oil particles and lubricating air supplied from an oil supply passage of a housing (not shown) are directly supplied to the ball 13 through the concave groove 16 and the supply hole 15 of the outer ring 12, so that the oil/air lubrication is performed.

[0060] On the other hand, instead of the configuration where the outer ring 12 is formed with the circumferential concave groove, the circumferential concave groove may be formed at a position of an opening of the oil supply passage that is formed in an inner peripheral surface of the housing and is configured to communicate with the supply hole 15.

[0061] Also, in the first embodiment, an inner diameter-side opening of the supply hole 15 is provided in an inner peripheral surface of a contact angle-side with respect to a groove bottom position A of the outer ring 12.

[0062] In particular, from a standpoint of lubricity during rotation of the bearing, the inner diameter-side opening of the supply hole 15 is preferably provided in the outer ring raceway groove 12a.

[0063] Also, from a standpoint of suppressing an increase in contact surface pressure at contact positions of the inner and outer rings 11, 12 and the ball 13, the inner diameter-side opening of the supply hole 15 is set to a position spaced from a contact ellipse E between the ball 13 and the outer ring raceway groove 12a. The contact ellipse E means a contact ellipse that is to be generated only by an initial preload, more preferably a contact ellipse that is to be generated by a bearing internal load including an external load to be generated when processing a member to be processed.

[0064] Meanwhile, in the first embodiment, the diameter of the supply hole 15 is set to 0.5 to 1.5 mm, considering the supply ability of the lubricating oil and the interference prevention with the contact ellipse E. Also, in the first embodiment, the supply hole 15 has a uniform diameter in the radial direction.

[0065] Also, the outer ring spacer 30 is arranged to be adjacent to the outer ring 12 at the counterbore-opposite-side. Also, an inner diameter dimension D.sub.31 of an axial end face 31 of the outer ring spacer 30 is set to be the same as an inner diameter dimension D.sub.12e of the other axial end face 12e of the outer ring 12 in contact with the outer ring spacer 30.

[0066] An inner peripheral surface of the outer ring spacer 30 has a tapered surface 32 of which a diameter increases with a distance from the axial end face 31 in contact with the outer ring 12, and a cylindrical surface 33 extending from a larger diameter-side end portion of the tapered surface 32.

[0067] Also, the outer ring spacer 30 has a discharge hole 34 penetrating therethrough in the radial direction and configured to discharge the lubricating oil. In the first embodiment, the discharge hole 34 is formed over the tapered surface 32 and the cylindrical surface 33. However, the present invention is not limited thereto. For example, the discharge hole 34 may be provided in a part of the tapered surface 32.

[0068] In the meantime, the supply hole 15 of the outer ring 12 and the discharge hole 34 of the outer ring spacer 30 are shown with the same phase for convenience of illustration. However, the present invention is not limited thereto.

[0069] According to the bearing device 1 configured as described above, the inner peripheral surface of the outer ring spacer 30 is configured by the tapered surface 32, and the discharge hole 34 is provided on the tapered surface 32, so that the lubricating oil delivered to the outer ring by the centrifugal force is efficiently discharged to an outside. That is, during the high-speed rotation, a circumferential high-speed stream is generated in the bearing by the revolution of the ball 13 and the cage 14, so that the lubricating oil flows in the circumferential direction with being attached to the inner peripheral surface of the outer ring 12. Due to the phenomenon, the inner peripheral surface of the outer ring spacer 30 is configured by the tapered surface 32 of which a diameter is larger at the discharge hole 34-side, so that it is possible to guide the lubricating oil to the discharge hole 34 while spirally rotating the same along the tapered surface 32.

[0070] Also, in the rolling bearing 10 for a machine tool spindle, in order to implement favorable bearing performance in a high-speed rotation region, it is important to efficiently discharge the lubricating oil supplied into the bearing and to extremely suppress heat generation and the like caused due to the lubricating oil staying in the bearing. As described above, the outer ring spacer 30 is provided with the oil discharge structure of the first embodiment, so that it is possible to solve a collision problem between an outer diameter surface of the cage 14 and a cutout edge, and to efficiently discharge the lubricating oil supplied into the bearing from the supply hole 15 formed in the outer ring 12, thereby achieving the stable bearing performance in the high-speed rotation region.

[0071] Meanwhile, in the first embodiment, like a first modified embodiment shown in FIG. 2, the outer peripheral surface of the outer ring 12 is formed with annular grooves 19 along the circumferential direction at both axial sides with the concave groove 16 being interposed therebetween, and a seal member 20, which is an annular elastic member such as an O-ring, is arranged in each of the annular grooves 19, so that it is possible to prevent the oil leakage.

[0072] Also, in the first embodiment, the inner diameter dimension D.sub.31 of the axial end face 31 of the outer ring spacer 30 may be set equal to or larger than the inner diameter dimension D.sub.12e of the other axial end face 12e of the outer ring 12 in contact with the outer ring spacer 30, and may be the same, like the first embodiment. On the other hand, like a second modified embodiment shown in FIG. 3, the inner diameter dimension D.sub.31 of the axial end face 31 of the outer ring spacer 30 may be designed to be larger than the inner diameter dimension D.sub.12e of the other axial end face 12e of the outer ring 12 in contact with the outer ring spacer 30.

[0073] Also, in the first embodiment, the inner diameter-side opening of the supply hole 15 is preferably provided in the inner peripheral surface of the contact angle-side with respect to the groove bottom position A of the outer ring 12 so as to be adjacent to the outer ring spacer 30 having the discharge hole 34. On the other hand, like a third modified embodiment shown in FIG. 4, the inner diameter-side opening of the supply hole 15 may be provided in an inner peripheral surface of a contact angle-opposite-side with respect to the groove bottom position A of the outer ring 12.

[0074] Also, like a fourth modified embodiment shown in FIG. 5, the bearing device 1 further includes an inner ring spacer 50 (an inner ring-side peripheral component) arranged to be adjacent to the inner ring 11 at the other axial side (a counterbore-opposite-side of the outer ring 12). The inner ring spacer 50 has a tapered outer peripheral surface 51 that faces the tapered surface 32 of the outer ring spacer 30 and forms a labyrinth L between the tapered outer peripheral surface 51 and the tapered surface 32.

[0075] Thereby, the labyrinth L is formed between the inner peripheral surface of the outer ring spacer 30 and the outer peripheral surface of the inner ring spacer 50, and when the tapered outer peripheral surface 51 of the inner ring spacer 50 generates a peripheral speed difference in the direction of the rotary shaft of the bearing 10, a pressure difference is correspondingly generated in the labyrinth L and an air flow toward the discharge hole 34 is generated, so that the oil discharge ability is improved. In the meantime, the tapered outer peripheral surface 51 of the inner ring spacer 50 is formed at a position spaced from an axial end face in contact with the inner ring 11.

[0076] Meanwhile, in the second to fourth modified embodiments shown in FIGS. 3 to 5, the seal members 20 are arranged on the outer peripheral surface of the outer ring 12. However, like FIG. 1, the seal member may not be provided.

Second Embodiment

[0077] Subsequently, a bearing device of a second embodiment is described with reference to FIG. 6. In the second embodiment, the position of the supply hole 15 and the configuration of the outer ring spacer are different from the first embodiment shown in FIG. 1. The other configurations are the same as the first embodiment, and the parts, which are the same as or equivalent to the first embodiment, are denoted with the same reference numerals, and the descriptions thereof are omitted or simplified.

[0078] As shown in FIG. 6, a bearing device 1a in accordance with the second embodiment can be applied to a spindle device for machine tool, and includes at least the angular ball bearing (rolling bearing) 10, and an outer ring spacer (counterbore-side peripheral component) 40.

[0079] In the angular ball bearing 10 of the second embodiment, like the third modified embodiment of the first embodiment, the inner diameter-side opening of the supply hole 15 is provided in the inner peripheral surface of the contact angle-opposite-side with respect to the groove bottom position A of the outer ring 12.

[0080] In particular, from the lubricity during the rotation of the bearing, the inner diameter-side opening of the supply hole 15 is preferably provided in the outer ring raceway groove 12a.

[0081] The outer ring spacer 40 is arranged to be adjacent to the outer ring 12 at the counterbore-side. An inner diameter dimension D.sub.41 of an axial end face 41 of the outer ring spacer 40 is designed to be the same as an inner diameter dimension D.sub.12d of one axial end face 12d of the outer ring 12 in contact with the outer ring spacer 40.

[0082] Also, the outer ring spacer 40 has a cutout for discharge 42 formed in the radial direction at the axial end face 41 in contact with the outer ring 12.

[0083] In the meantime, the supply hole 15 of the outer ring 12 and the cutout for discharge 42 of the outer ring spacer 40 are shown with the same phase for convenience of illustration. However, the present invention is not limited thereto.

[0084] Thereby, in the bearing device 1a of the second embodiment, during the high-speed rotation, a circumferential high-speed stream is generated in the bearing by the revolution of the ball 13 and the cage 14, so that the lubricating oil flows in the circumferential direction with being attached to the inner peripheral surface of the outer ring 12. Due to the phenomenon, it is possible to guide the lubricating oil to the cutout for discharge 42 while spirally rotating the same along the counterbore 12b, which is the inclined surface.

[0085] Also, in the second embodiment, since the counterbore 12b of the outer ring 12 is configured by the inclined surface, it is not necessary to provide the inner peripheral surface of the outer ring spacer 40 with a tapered surface, and the cutout for discharge 42 is provided at the axial end face 41 of the outer ring spacer 40, i.e., at a part in contact with the outer ring 12 in the direction of the rotary shaft of the bearing, so that it is possible to efficiently discharge the oil. Therefore, the outer ring spacer 40 is preferably formed to have a ring shape of a uniform height.

[0086] The other configurations and operations are the same as the first embodiment.

[0087] Meanwhile, in the second embodiment, like a first modified embodiment shown in FIG. 7, the outer peripheral surface of the outer ring 12 is formed with annular grooves 19 at both axial sides with the concave groove 16 being interposed therebetween along the circumferential direction, and a seal member 20, which is an annular elastic member such as an O-ring, is arranged in each of the annular grooves 19, so that it is possible to prevent the oil leakage.

[0088] Also, in the second embodiment, the inner diameter dimension D.sub.41 of the axial end face 41 of the outer ring spacer 40 may be set equal to or larger than the inner diameter dimension D.sub.12d of one axial end face 12d of the outer ring 12 in contact with the outer ring spacer 40, and may be the same, like the second embodiment. On the other hand, like a second modified embodiment shown in FIG. 8, the inner diameter dimension D.sub.41 of the axial end face 41 of the outer ring spacer 40 may be designed to be larger than the inner diameter dimension D.sub.12d of one axial end face 12d of the outer ring 12 in contact with the outer ring spacer 40.

[0089] Also, in the second embodiment, the inner diameter-side opening of the supply hole 15 is preferably provided in the inner peripheral surface of the contact angle-opposite-side with respect to the groove bottom position A of the outer ring 12 so as to be adjacent to the outer ring spacer 30 having the discharge hole 34. On the other hand, like a third modified embodiment shown in FIG. 9, the inner diameter-side opening of the supply hole 15 may be provided in the inner peripheral surface of the contact angle-side with respect to the groove bottom position A of the outer ring 12. Also in this case, the inner diameter-side opening of the supply hole 15 is set to a position spaced from the contact ellipse E between the ball 13 and the outer ring raceway groove 12a.

[0090] In the second and third modified embodiments shown in FIGS. 8 and 9, the seal members 20 are arranged on the outer peripheral surface of the outer ring 12. However, like FIG. 6, the seal member may not be provided.

[0091] In the meantime, the present invention is not limited to the above embodiments, and can be appropriately modified and changed.

[0092] For example, like a modified embodiment shown in FIG. 10, the outer ring spacer 30 of the first embodiment and the outer ring spacer 40 of the second embodiment may be applied to a bearing device 1b at the same time. Thereby, it is possible to further improve the oil discharge ability, so that it is possible to achieve the more stable bearing performance in the high-speed rotation region.

[0093] Also, the supply hole may be any supply hole penetrating the outer ring from the outer peripheral surface to the inner peripheral surface in the radial direction, and may be inclined in the direction of the rotary shaft or the circumferential direction of the bearing, in addition to the second embodiment where it is formed in the radial direction (parallel with a plane taken along the radial direction).

[0094] Also, in the above embodiments, the outer ring 12 has one supply hole. However, the present invention is not limited thereto. For example, the outer ring may have a plurality of supply holes.

[0095] Also, the discharge hole 34 and the cutout for discharge 42 may be provided in plural in the circumferential direction, respectively.

[0096] In the meantime, as the method of supply the lubricating oil into the supply hole of the outer ring, oil/mist lubrication may be adopted, in addition to the oil/air lubrication. Oil/jet lubrication may also be adopted, depending on situations. However, in a grease supply method of supplying grease from the supply hole 15 of the outer ring 12 by using a lubricant supply device provided around the bearing or outside the spindle, if the supply hole 15 is formed to open toward an inside of the outer ring raceway groove 12a, the semisolid grease containing thickener is supplied into the outer ring raceway groove 12a.

[0097] In this case, since the grease is caught into the outer ring raceway groove 12a, the problems such as increase in torque and abnormal heat generation are generated due to stirring resistance. Particularly, the problems are more likely to be generated during the high-speed rotation, like the second embodiment. Therefore, the oil lubrication method of supplying the lubricating oil, which does not contain the thickener, is preferable in the present invention.

[0098] Also, the ball bearing of the present invention is not limited to the spindle device for machine tool and can be applied as a ball bearing of a general industrial machine and a high-speed rotating device such as a motor, too.

[0099] Also, the inner peripheral surface of one axial end face of the outer ring and the inner peripheral surface of the other axial end face may be chamfered. In this case, the inner diameter dimensions of the axial end faces of the counterbore-opposite-side peripheral component and the counterbore-side peripheral component in contact with the outer ring may be set, considering the chamfering dimensions.

[0100] That is, when the inner diameter dimension of the axial end face of each peripheral component is set equal to or larger than the inner diameter dimension of the axial end face of the outer ring, except the chamfering dimension, the lubricating oil discharged from the inside of the bearing does not stay in a concave part formed between the chamfered part of the outer ring and each peripheral component, so that it is possible to achieve the more excellent discharge effect.

[0101] In the meantime, the discharge hole 34 or the cutout for discharge 42 may be provided at a lower part in a gravity direction, so that the lubricating oil may be discharged from a discharge passage of a housing (not shown) in communication with the same or the lubricating oil may be discharged by an external suction device (not shown).

[0102] The subject application is based on Japanese Patent Application No. 2016-filed on Aug. 15, 2016, the contents of which are incorporated herein by reference.

DESCRIPTION OF REFERENCE NUMERALS

[0103] 1, 1a, 1b: bearing device [0104] 10: angular ball bearing (rolling bearing) [0105] 11: inner ring [0106] 11a: inner ring raceway groove [0107] 12: outer ring [0108] 12a: outer ring raceway groove [0109] 12b: counterbore [0110] 12c: groove shoulder [0111] 13: ball (rolling element) [0112] 14: cage [0113] 15: supply hole [0114] 16: concave groove [0115] 30: outer ring spacer (counterbore-opposite-side peripheral component) [0116] 32: tapered surface [0117] 34: discharge hole [0118] 40: outer ring spacer (counterbore-side peripheral component) [0119] 42: cutout for discharge (cutout) [0120] E: contact ellipse