Air oil lubrication structure for rolling bearing

Abstract

To provide an air oil lubricating structure of a rolling bearing capable of smoothly supplying air oil.SOLUTION: An air oil lubricating structure of a rolling bearing comprises a rolling bearing 1, and a lubricating device 2 for supplying air oil to the rolling bearing 1. The lubricating device 2 includes: an outer ring spacer 11 that is provided adjacent to an outer ring end surface 7b of the roller bearing 1 and has an air oil supply hole 14; and a nozzle spacer 12 that is fixed to the outer ring spacer 11 via a mating surface 12a, has an air oil supply hole 17 communicating with the air oil supply hole 14, and discharges the air oil from the air oil supply hole 17 to the roller bearing 1. The air oil lubricating structure of the rolling bearing comprises: a seal groove 18 that ensures a contact surface f1 between the outer ring spacer 11 and the outer ring end face 7b and is annularly provided on the mating surface 12a, located outside the air oil supply hole 14 and the air oil supply hole 17; and means 13 for securing a straight surface, etc. that secures a straight surface f2 between the boundary portion 19 and the air oil supply hole 14 with a specified area or more.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an air-oil lubrication structure for a rolling bearing that is applied to, for example, an angular contact ball bearing used to support the high-speed rotation of a main spindle or the like in a machine tool. [Background technology]

[0002] The spindle units of machine tools tend to be faster, and an air-oil lubrication structure is being applied (for example, Patent Documents 1 and 2). This air-oil lubrication is a lubrication method in which lubricating oil is mixed with conveying air and sprayed directly onto the inner ring. As shown in Fig. 6, this air-oil lubrication structure includes a rolling bearing 52 with an oil groove 51 provided in the counterbore 50, which is a sloped portion, provided on the outer diameter of the inner ring, an outer ring spacer 53, and a nozzle spacer 54.

[0003] Air-oil is injected from housing 55, a customer's component, through outer ring spacer 53 and nozzle spacer 54 into oil groove 51 of the inner ring, and the centrifugal force caused by the rotation of the inner ring and the surface tension of the oil cause the lubrication to spread along counterbore 50 to rolling surface 56. The outer ring spacer 53 and nozzle spacer 54 are fixed to the outer ring spacer 53 with bolts or the like. An oil supply hole 57 communicates between the outer ring spacer 53 and nozzle spacer 54, and an O-ring 58 is attached at the boundary between them to prevent air-oil leakage. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4261083 [Patent Document 2] Patent No. 4289875 Summary of the Invention [Problem to be solved by the invention]

[0005] In this air-oil lubrication structure, the nozzle spacer 54 is fixed to the outer ring spacer 53 with bolts, and the outer ring spacer 53 and the bearing outer ring 59 are installed in contact with each other. If the radial cross-sectional height h of the nozzle spacer 54 is too large compared to the ball diameter of the bearing, the contact surface between the outer ring spacer 53 and the bearing outer ring 59 cannot be secured. If the radial cross-sectional height h of the nozzle spacer 54 is too small compared to the ball diameter, a straight surface between the O-ring groove and the oil supply hole cannot be secured, and the design is not viable. If the required straight surface cannot be secured, the O-ring 58 may not be able to be fitted, or even if the O-ring 58 can be fitted, the O-ring 58 may not function properly, and air oil may not be smoothly supplied to the rolling bearing 52. For this reason, the radial cross-sectional height h of the nozzle spacer 54 compared to the ball diameter must be set to an optimum value.

[0006] An object of the present invention is to provide an air-oil lubrication structure for a rolling bearing that can smoothly supply air-oil. [Means for solving the problem]

[0007] The air-oil lubrication structure for a rolling bearing of the present invention comprises a rolling bearing and a lubrication device that supplies air oil to the rolling bearing, The lubrication device is an air-oil lubrication structure for a rolling bearing including an outer ring spacer provided adjacent to an outer ring end surface of the rolling bearing and having an air-oil supply hole, and a nozzle spacer fixed to the outer ring spacer via a mating surface, having an air-oil supply hole communicating with the air-oil supply hole, and discharging air-oil from the air-oil supply hole to the rolling bearing, The outer ring spacer and the outer ring end face are in contact with each other, The mating surfaces include a straight surface securing means for securing a straight surface of at least a specified area between the air-oil supply hole and the air-oil feed hole and a seal groove that is annularly provided and located outside the air-oil supply hole and the air-oil feed hole. The air oil is a lubricating oil mixed with conveying air. The "predetermined area" is an area that is arbitrarily determined by design or the like, and is determined by obtaining an appropriate area through, for example, either one or both of a test and a simulation.

[0008] This configuration ensures a contact surface between the outer ring spacer and the outer ring end face. At the same time, by ensuring that the straight surface between the seal groove and the air-oil supply hole of the mating surfaces has a specified area or more, a seal can be attached to the seal groove and the seal function can be exerted. Therefore, air-oil can be smoothly supplied from the lubrication device to the rolling bearing.

[0009] The rolling bearing may be a ball bearing, and the means for ensuring a straight surface etc. may have a nozzle spacer cross-sectional height h and a ball diameter Dw that satisfy the following relationship: 0.8≦h / Dw≦2.0 The nozzle spacer cross-sectional height h is the radial cross section of the nozzle spacer. By satisfying this relationship, a contact surface between the outer ring spacer and the outer ring end face can be secured, and the seal can be reliably fitted in the seal groove.

[0010] The oil supply hole pitch diameter d3 of the nozzle spacer and the pitch circle diameter PCD of the rolling bearing may have the following relationship: 0.9≦d3 / PCD≦1.1 By satisfying the above-mentioned relationship between the oil hole pitch diameter d3 and the pitch circle diameter PCD, it becomes possible to inject air-oil at a specific position on the inner ring, which allows the air-oil to be supplied more smoothly from the lubricating device to the rolling bearing.

[0011] The nozzle diameter A and the oil supply hole diameter B of the nozzle spacer may have the following relationship: 1.0≦B / A≦4.0 The nozzle diameter A is the diameter of the downstream side of the air-oil feed hole facing the rolling bearing, and the oil feed hole diameter B is the diameter of the upstream side of the air-oil feed hole communicating with the air-oil feed hole of the outer ring spacer. By satisfying the above relationship between the nozzle diameter A and the oil supply hole diameter B, the relationship between the air speed and the air pressure can be maintained appropriately, and an O-ring (seal) mechanism can be installed even if the radial dimension freedom around the seal groove is small.

[0012] An oil supply hole diameter B of the nozzle spacer and an inner diameter C of the seal groove may have the following relationship: 1.0 <C / B≦2.5 By satisfying the above relationship between the oil supply hole diameter B and the inner diameter C of the seal groove, the functionality of the O-ring (seal) is improved and smoother air-oil lubrication is possible.

[0013] An inner diameter C of the seal groove and a seal inner diameter D of a seal fitted into the seal groove may have the following relationship: 0.7≦D / C≦1.0 By satisfying the above relationship between the seal groove inner diameter C and the seal inner diameter D, springback of the seal installed in the seal groove can be suppressed, improving the installation of the lubrication device and enabling smoother air-oil lubrication. The seal has a slight interference with the seal groove and does not fall freely. Therefore, when the seal is installed in the nozzle spacer and the outer ring spacer and nozzle spacer are fixed, it is difficult to come off, which improves the installation of the seal. Furthermore, by satisfying these relationships, standard products can be used as the seal, which makes it possible to reduce costs compared to using dedicated seals.

[0014] The rolling bearing may be an angular contact ball bearing. In the angular contact ball bearing of this air-oil lubrication structure, one side portion of the outer circumferential surface of the inner ring is a counterbore that is a sloped portion for supplying air oil. Effect of the Invention

[0015] The air-oil lubrication structure for a rolling bearing of the present invention ensures a contact surface between the outer ring spacer and the outer ring end face. At the same time, the straight surface between the seal groove and the air-oil supply hole on the mating surfaces of the outer ring spacer and the nozzle spacer has a specified area or more. This allows air-oil to be reliably supplied to the bearing even in a small space. [Brief description of the drawings]

[0016] [Figure 1] 1 is a vertical sectional view of an air-oil lubrication structure for a rolling bearing according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a partially enlarged view of a main part of FIG. [Figure 3A] FIG. 4 is a partial enlarged view of the nozzle spacer of the air-oil lubrication structure as viewed from the axial direction. [Figure 3B] FIG. 4 is a side view of a seal to be installed in a seal groove of the nozzle spacer. [Figure 4A] FIG. 4 is a partially enlarged view of a main portion in which the air-oil lubrication structure is partially modified. [Figure 4B] FIG. 4 is a vertical sectional view of an air-oil lubrication structure for a rolling bearing according to a second embodiment of the present invention. [Diagram 5] FIG. 1 is a cross-sectional view of a spindle device employing any one of the air-oil lubrication structures. [Figure 6] FIG. 1 is a longitudinal sectional view of an air-oil lubrication structure for a rolling bearing according to a conventional example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] [First embodiment] An air-oil lubrication structure for a rolling bearing according to an embodiment of the present invention will be described with reference to Figures 1 to 3B and 5. The air-oil lubrication structure for a rolling bearing according to the present embodiment is applied to, for example, an angular contact ball bearing that rotatably supports the main spindle of a machine tool. As shown in Fig. 1, the air-oil lubrication structure for a rolling bearing comprises an angular ball bearing 1 and a lubrication device 2 that supplies air oil to the angular ball bearing 1. A rotating body, that is, a main shaft 5 (Fig. 5), is rotatably supported in a housing 3 (Fig. 5) via the angular ball bearing 1, the lubrication device 2, an inner ring spacer 4, etc. With multiple angular ball bearings 1, the lubrication device 2, and the inner ring spacer 4 assembled in the housing 3 (Fig. 5) and the main shaft 5 (Fig. 5), a predetermined fixed position preload or constant pressure preload is applied to the angular ball bearing 1.

[0018] <Rolling bearings> The angular contact ball bearing 1, which is a rolling bearing, comprises an inner ring 6, an outer ring 7 which is a fixed raceway ring, a number of rolling elements 8 interposed between the rolling surfaces 6a, 7a of the inner and outer rings 6, 7, and a cage 9 which holds these rolling elements 8. The rolling elements 8 are balls and are held in pockets 9a of the cage 9. A portion 9b of the inner peripheral surface of the cage 9, which is located closer to the width side than the pocket 9a, is a tapered surface with a larger diameter on the width side than in the center of the cage in the width direction. The outer peripheral surface of the outer ring 7 is fitted into a fitting hole in the housing 3 (Fig. 5), and the inner peripheral surface of the inner ring 6 is fitted into the outer peripheral surface of the spindle 5 (Fig. 5).

[0019] As shown in Fig. 2, a counterbore, which is a sloped surface 6b continuing to the rolling surface 6a, is provided on the outer peripheral surface of the non-load side of the inner ring 6. The sloped surface 6b has a tapered shape that gradually reduces in diameter from the rolling surface 6a side toward the inner ring spacer 4 side. A circumferential groove 10 is provided in the sloped surface 6b. The circumferential groove 10 is formed in an annular shape with a V-shaped cross section.

[0020] <Lubrication device> The lubrication device 2 includes an outer ring spacer 11 and a nozzle spacer 12. The lubrication device 2 includes a means 13 for ensuring a straight surface, etc., which will be described later. The outer ring spacer 11 has an air-oil supply hole 14 provided adjacent to the outer ring end face 7b of the angular contact ball bearing 1. This air-oil supply hole 14 is connected by piping to an air-oil supply source via an air-oil supply passage 15 (FIG. 5) of the housing 3 (FIG. 5). The outer ring end face 7b is the back surface of the outer ring on the side supporting the axial load. An annular communication groove 16 communicating with the air-oil supply passage is provided on the outer peripheral surface of the outer ring spacer 11, and this communication groove 16 communicates with the air-oil supply hole 14. This air-oil supply hole 14 includes an upstream supply hole portion 14a and a downstream supply hole portion 14b. The upstream supply hole 14a communicates with the communication groove 16 and extends a predetermined length in the radial direction, and the downstream supply hole 14b communicates with the upstream supply hole 14a and extends a predetermined length in the axial direction.

[0021] The nozzle spacer 12 is fixed to the outer ring spacer 11 via a mating surface 12a, and has an air-oil feed hole 17 that communicates with a downstream supply hole portion 14b of the air-oil feed hole 14 of the outer ring spacer 11. The mating surface 12a is along a plane perpendicular to the bearing center line C1 (FIG. 1) of the rolling bearing 1. The nozzle spacer 12 discharges air-oil from the air-oil feed hole 17 to the rolling bearing 1. An annular notched recess 11a is formed in the inner diameter portion of one side surface of the outer ring spacer 11, and the nozzle spacer 12 is fixed to the notched recess 11a with a bolt.

[0022] The nozzle spacer 12 is provided along the inclined surface 6b of the inner ring 6 with a predetermined gap δ therebetween. The nozzle spacer 12 has its tip end 12ba positioned near the rolling element 8 between the inner peripheral surface of the cage 9 and the outer peripheral surface of the inner ring 6. The nozzle spacer 12 is a ring-shaped member provided adjacent to the rolling bearing 1 in the axial direction and has a flange-shaped portion 12b extending axially from the inner diameter side portion of the side surface. The inner peripheral surface of the nozzle spacer 12 at the portion outside the bearing faces the outer peripheral surface of the inner ring spacer 4 with a predetermined radial gap therebetween. In this specification, the "axial direction" refers to the direction along the bearing center line C1 (FIG. 1) of the rolling bearing 1. The "radial direction" refers to the direction perpendicular to the straight line forming the "axial direction".

[0023] The flange portion 12b has a flat inner peripheral surface formed as an inclined surface at the same angle as the inclined surface 6b of the inner ring 6, and extends to just below the cage 9. The tip of this flange portion 12b becomes the tip portion 12ba of the nozzle spacer 12. The gap δ between the flange portion 12b and the inclined surface 6b is set within a range that does not cause contact during operation, taking into consideration the fit between the inner ring 6 and the shaft, and the expansion of the inner ring 6 due to a temperature rise and centrifugal force.

[0024] The nozzle spacer 12 is provided with the air-oil oil supply hole 17, whose discharge port 17ba opens facing the circumferential groove 10 of the inner ring 6. The air-oil supply hole 17 is provided at one or more locations in the circumferential direction of the nozzle spacer 12. The air-oil supply hole 17 has an upstream oil supply hole 17a that communicates with the air-oil supply hole 14 of the outer ring spacer 11, and a downstream nozzle hole 17b in which the discharge port 17ba is formed.

[0025] The upstream oil supply hole 17a extends a predetermined length in the axial direction and communicates with the downstream oil supply hole 17b at its tip. The downstream nozzle hole 17b is provided so that the air / oil discharge direction of the discharge port 17ba faces the circumferential groove 10 and has a set inclination angle with respect to the axial direction. This allows the air / oil discharged from the discharge port 17ba to be sprayed directly onto the circumferential groove 10. The side wall slope 10a of the circumferential groove 10 closer to the rolling surface 6a is set to have a larger inclination angle with respect to the axial direction than the slope portion 6b of the inner ring 6.

[0026] <Means for securing straight surfaces, etc.> The means for ensuring straight surfaces, etc. 13 ensures a contact surface f1 between the outer ring spacer 11 and the outer ring end face 7b, and also ensures a straight surface f2 of at least a specified area between the seal groove 18 and the boundary 19 of the air-oil supply hole 14 and the air-oil feed hole 17. In other words, the means for ensuring straight surfaces, etc. 13 ensures the contact surface f1, and also ensures a straight surface f2 of at least a specified area between the seal groove 18 and the air-oil feed hole 17. The contact surface f1 is the contact surface between the outer ring end face 7b on the outer ring back side and one side of the outer ring spacer 11 facing this outer ring end face 7b.

[0027] An annular seal groove 18 is provided on a mating surface 12a of the nozzle spacer 12 with the outer ring spacer 11. The annular seal groove 18 is located radially outward from a boundary portion 19 around the base end of the upstream oil supply hole 17a. As shown in FIG. 3A, the annular seal groove 18 is provided concentrically with the oil supply hole 17a. A seal 20 such as an O-ring shown in FIG. 3B is fitted into the annular seal groove 18, and as shown in FIG. 2, the outer ring spacer 11 and the nozzle spacer 12 are fixed with a fastener (not shown) such as a bolt, and the seal 20 elastically deforms in the seal groove 18 to seal the periphery of the boundary portion 19, thereby preventing air-oil from leaking from the boundary portion 19. For the O-ring, a standard product defined by, for example, ISO is applied.

[0028] <About parameters etc.> If the radial cross-sectional height h of the nozzle spacer 12 is too large compared to the ball diameter of the rolling bearing 1, the contact surface f1 between the outer ring spacer 11 and the outer ring 7 cannot be ensured. If the radial cross-sectional height h of the nozzle spacer 12 is too small compared to the ball diameter, the straight surface f2 between the O-ring groove 18 and the oil supply hole cannot be ensured, and the system will not function. For this reason, the nozzle spacer cross-sectional height h relative to the ball diameter Dw must be set to an optimum value. Specifically, in the means 13 for ensuring a straight surface, etc., the nozzle spacer cross-sectional height h and the ball diameter Dw have the following relationship. 0.8≦h / Dw≦2.0

[0029] Furthermore, the air oil is injected from the outer ring spacer 11 through the nozzle spacer 12 into the oil groove 10 in the inner ring 6. The nozzle hole A of the nozzle spacer 12 has a certain angle with respect to a radial perpendicular line. Therefore, unless the oil feed hole pitch diameter d3 of the nozzle spacer 12 is optimally positioned with respect to the pitch circle diameter PCD of the rolling bearing 1, it is not possible to achieve a structure in which the nozzle hole tip is aimed at the oil groove 10 in the inner ring 6. In other words, the relationship between the oil feed hole pitch diameter d3 and the bearing PCD is important. Therefore, the oil supply hole pitch diameter d3 of the nozzle spacer 12 and the pitch circle diameter PCD of the rolling bearing 1 are set to the following relationship: 0.9≦d3 / PCD≦1.1

[0030] The O-ring used in the nozzle spacer 12 has a very small diameter due to dimensional restrictions. To reduce costs, we would like to use the manufacturer's standard O-rings. Considering ease of assembly, it is desirable for the O-ring to have the same diameter as the O-ring groove inner diameter or to have a slight interference. However, the dimensions around the O-ring groove have little free space in the radial direction, and the design often has a large interference. Therefore, even if one were to reduce the inner diameter of the O-ring groove to reduce the interference, it would be difficult to set the dimensions because there is oil supply hole 17a in the center of O-ring groove 18 and a straight section must be secured between oil supply hole 17a and the inner diameter of the O-ring groove. If the interference of the O-ring is too large, spring back will occur when the O-ring is inserted, and the spacer will be tightened in a state where the O-ring is floating out of the groove, which may cause the O-ring to seize. If galling occurs, the O-ring will not function properly, which may lead to leakage. From this, it is necessary to optimize the dimensions of the following three things: (1) the relationship between nozzle hole diameter A and oil supply hole diameter B, (2) the relationship between oil supply hole diameter B and O-ring groove inner diameter C, and (3) the relationship between O-ring groove inner diameter C and O-ring inner diameter D.

[0031] Based on the above, the parameters are set as follows: The nozzle diameter A and the oil supply hole diameter B of the nozzle spacer 12 have the following relationship. 1.0≦B / A≦4.0

[0032] The oil supply hole diameter B of the nozzle spacer 12 and the inner diameter C of the seal groove 18 have the following relationship: 1.0 <C / B≦2.5

[0033] The inner diameter C of the seal groove 18 and the seal inner diameter D of the seal 20 fitted into the seal groove 18 have the following relationship. 0.7≦D / C≦1.0

[0034] <Comparison between this embodiment and comparative example> Here, in order to evaluate the air-oil lubrication structures of the rolling bearings of the present Examples 1 to 4 and the air-oil lubrication structures of the rolling bearings of the Comparative Examples, a comparison was made on the air speed, air pressure, O-ring design, O-ring functionality, O-ring assembly, etc. as shown in Table 1. In Table 1, ◎ indicates that it is possible to implement and has excellent effects, ○ indicates that it is possible to implement and has good effects, △ indicates that it is possible to implement, and × indicates that it is not very effective.

[0035] [Table 1]

[0036] <Action and effect> According to the air-oil lubrication structure for the rolling bearing described above, the air-oil supplied from the air-oil supply hole 14 is sprayed into the circumferential groove 10 of the inner ring sloped surface portion 6b through the air-oil supply hole 17 of the nozzle spacer 12. The oil adhering to the circumferential groove 10 is guided along the inner ring sloped surface portion 6b by the action of centrifugal force, and flows into the interior of the angular contact ball bearing 1 as lubricating oil.

[0037] The means for securing a straight surface, etc. 13 secures the contact surface f1 between the outer ring spacer 11 and the outer ring end surface 7b. As a result, when the angular ball bearings 1, the lubricating device 2 and the inner ring spacer 4 are assembled into the housing 3 (FIG. 5) and the main shaft 5 (FIG. 5), a predetermined preload can be applied to the angular ball bearing 1, and a predetermined gap δ can be secured between the nozzle spacer 12 and the inclined surface portion 6b of the inner ring 6. At the same time, by securing a straight surface f2 between the seal groove 18 and the air-oil supply hole 19 of the mating surface 12a with a specified area or more, the seal 20 can be fitted to the seal groove 18 and can function as the seal 20. Therefore, air oil can be smoothly supplied from the lubricating device 2 to the rolling bearing 1.

[0038] The means 13 for ensuring a straight surface, etc. has the following relationship between the nozzle spacer cross-sectional height h and the ball diameter Dw. 0.8≦h / Dw≦2.0 By satisfying the above relationship, the contact surface f1 between the outer ring spacer 11 and the outer ring end face 7b can be secured, and the seal 20 can be reliably fitted in the seal groove 18.

[0039] The oil supply hole pitch diameter d3 of the nozzle spacer 12 and the pitch circle diameter PCD of the rolling bearing 1 have the following relationship. 0.9≦d3 / PCD≦1.1 By satisfying the above-mentioned relationship between the oil feed hole pitch diameter d3 and the pitch circle diameter PCD, it becomes possible to inject air-oil aimed at a predetermined position on the inner ring 6. This enables the air-oil to be supplied from the lubricating device 2 to the rolling bearing 1 more smoothly.

[0040] The nozzle diameter A and the oil supply hole diameter B of the nozzle spacer 12 have the following relationship. 1.0≦B / A≦4.0 By satisfying the above relationship between the nozzle diameter A and the oil supply hole diameter B, the relationship between the air speed and the air pressure can be maintained appropriately, and an O-ring (seal) mechanism can be installed even if the radial dimension freedom around the seal groove is small.

[0041] The oil supply hole diameter B of the nozzle spacer 12 and the inner diameter C of the seal groove 18 have the following relationship: 1.0 <C / B≦2.5 By satisfying the above-mentioned relationship between the oil supply hole diameter B and the inner diameter C of the seal groove 18, the functionality of the O-ring (seal) is improved and smoother air-oil lubrication is possible.

[0042] The inner diameter C of the seal groove 18 and the seal inner diameter D of the seal 20 fitted into the seal groove 18 have the following relationship. 0.7≦D / C≦1.0 By satisfying the above relationship between the inner diameter C of the seal groove 18 and the seal inner diameter D, springback of the seal 20 attached to the seal groove 18 can be suppressed, improving the installation of the lubrication device 2 and enabling smoother air-oil lubrication. The seal 20 has a slight interference with the seal groove 18 and does not fall freely. Therefore, when the seal 20 is attached to the nozzle spacer 12 and the outer ring spacer 11 and the nozzle spacer 12 are fixed, it is difficult for the seal 20 to come off, improving the installation of the seal 20. Furthermore, by satisfying these relationships, a standard product can be used as the seal 20, which makes it possible to reduce costs compared to using a dedicated seal.

[0043] The rolling bearing is an angular contact ball bearing 1. In the angular contact ball bearing 1 with this air-oil lubrication structure, one side portion of the outer circumferential surface of the inner ring 6 is a counterbore that is a sloped portion 6b for supplying air oil.

[0044] <Other embodiments> In the following description, parts corresponding to matters previously described in each embodiment are given the same reference numerals, and duplicated description is omitted. When only a part of the configuration is described, the other parts of the configuration are the same as the previously described embodiment unless otherwise specified. The same configuration has the same action and effect. It is possible to combine not only the parts specifically described in each embodiment, but also partially combine embodiments together, provided that there is no particular problem with the combination.

[0045] [Example of a seal groove provided in the outer ring spacer, Fig. 4A] 4A , an annular seal groove 18 may be provided in mating surface 11b of outer ring spacer 11 that interfaces with nozzle spacer 12. An annular seal groove 18 is located radially outward from boundary portion 19 around the downstream side of downstream supply hole 14b. An annular seal groove 18 is provided concentrically with downstream supply hole 14b. A seal 20, such as an O-ring, is fitted into annular seal groove 18. In this case as well, the same effects as those of the above-described embodiment are achieved.

[0046] [Second embodiment: cylindrical roller bearing, FIG. 4B] As shown in Fig. 4B, a cylindrical roller bearing 1A may be used as the rolling bearing. An inclined surface 6b continuing from the rolling surface 6a is provided on the outer peripheral surface of the inner ring 6 of the cylindrical roller bearing 1A. A circumferential groove 10 is provided on one of the inclined surfaces 6b. A nozzle spacer 12 is provided along one of the inclined surfaces 6b of the inner ring 6 with a predetermined gap δ therebetween. The second embodiment also provides substantially the same effects as the previous embodiments.

[0047] <Example of application to spindle device, Fig. 5> FIG. 5 shows an example of a spindle device employing the air-oil lubrication structure of the rolling bearing according to the first embodiment. This spindle device is applied to a machine tool, and a chuck for a tool or workpiece is attached to the end of a main spindle 5. The main spindle 5 is supported by a plurality of rolling bearings 1,1 (a pair in this example) spaced apart in the axial direction. The pair of rolling bearings 1,1 are arranged so that their back surfaces face each other. Each inner ring 6 is fitted to the outer peripheral surface of the main spindle 5, and each outer ring 7 is fitted to the inner peripheral surface of the housing 3. These inner and outer rings 6,7 are fixed to the main spindle 5 and the housing 3 by an inner ring holder 21 and an outer ring holder 22, respectively.

[0048] The housing 3 has a double structure consisting of an inner housing 3A and an outer housing 3B, and a coolant flow path 32 is formed between the inner and outer housings 3A, 3B. The inner housing 3A is provided with an air-oil supply path 15 and its air-oil supply port 15a. The housing 3 is fixed to a support base 37. The housing 3 is provided with an air-oil exhaust groove 34 near the installation portion of each bearing 1 on the inner circumferential surface, and an air-oil exhaust path 39 that is open to the atmosphere from the air-oil exhaust groove 34 is provided.

[0049] The nozzle spacer 12 shown in FIG. 1 etc. is an annular member, but depending on the application and conditions of use, it may be an arc-shaped member extending a predetermined length in the circumferential direction. The air-oil lubrication structure of each rolling bearing can also be applied to applications other than machine tool applications.

[0050] Although the embodiment of the present invention has been described above, the disclosed embodiment is illustrative in all respects and is not restrictive. The scope of the present invention is indicated by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0051] Reference Signs List 1...angular contact ball bearing (rolling bearing), 1A...cylindrical roller bearing (rolling bearing), 2...lubrication device, 7b...outer ring end face, 11...outer ring spacer, 11b...mating surface, 12...nozzle spacer, 12a...mating surface, 13...means for securing straight surface, etc., 14...air oil supply hole, 17...air oil supply hole, 18...seal groove, 19...boundary portion, f1...contact surface, f2...straight surface

Claims

1. The present invention is provided with a rolling bearing and a lubrication device that supplies air oil to the rolling bearing, The lubrication device is an air-oil lubrication structure for a rolling bearing including an outer ring spacer provided adjacent to an outer ring end surface of the rolling bearing and having an air-oil supply hole, and a nozzle spacer fixed to the outer ring spacer via a mating surface, having an air-oil supply hole communicating with the air-oil supply hole, and discharging air-oil from the air-oil supply hole to the rolling bearing, The outer ring spacer and the outer ring end face are in contact with each other, an air-oil lubrication structure for a rolling bearing, the air-oil lubrication structure comprising: a seal groove that is annularly positioned outside the air-oil supply hole and the air-oil feed hole, and a straight surface securing means that secures a specified area or more for a straight surface between the air-oil feed hole and the seal groove that is annularly positioned outside the air-oil supply hole and the air-oil feed hole, the straight surface being between the air-oil feed hole and the seal groove.

2. 2. The air-oil lubrication structure for a rolling bearing according to claim 1, wherein the rolling bearing is a ball bearing, and the means for ensuring a straight surface, etc. is an air-oil lubrication structure for a rolling bearing, wherein a nozzle spacer cross-sectional height h and a ball diameter Dw have the following relationship: 0.8≦h / Dw≦2.0

3. 3. The air-oil lubrication structure for a rolling bearing according to claim 1, wherein an oil supply hole pitch diameter d3 of the nozzle spacer and a pitch circle diameter PCD of the rolling bearing have the following relationship: 0.9≦d3 / PCD≦1.1

4. 3. The air-oil lubrication structure for a rolling bearing according to claim 1, wherein a nozzle diameter A and an oil supply hole diameter B of the nozzle spacer have the following relationship: 1.0≦B / A≦4.0

5. 5. The air-oil lubrication structure for a rolling bearing according to claim 4, wherein a diameter B of the oil supply hole of said nozzle spacer and an inner diameter C of said seal groove have the following relationship: 1.0<C / B≦2.5

6. 6. An air-oil lubrication structure for a rolling bearing according to claim 4, wherein an inner diameter C of the seal groove and an inner diameter D of a seal fitted into the seal groove have the following relationship: 0.7≦D / C≦1.0

7. 3. The air-oil lubrication structure for a rolling bearing according to claim 1, wherein the rolling bearing is an angular contact ball bearing.

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