JP5842982B2 - Bearing device, rotary table of machine tool, and spindle device - Google Patents

Description

  The present invention relates to a bearing device, a rotary table of a machine tool, and a spindle device, and more particularly to a bearing device capable of switching a preload applied to a rolling bearing, and a rotary table of a machine tool and a spindle device.

  Conventionally, a cross roller having a high rigidity, a three-roller bearing, or the like has been widely used as a rolling bearing used for a rotary table or the like of a machine tool. However, these bearings have a problem that they have large spin slip due to structural problems and are not suitable for high-speed rotation. In recent years, angular ball bearings suitable for high-speed rotation are being adopted, although the rigidity is somewhat inferior to cross roller and three roller bearings. When using angular contact ball bearings, preload is generally applied, but heavy positioning is applied for positioning and turning at low speed to increase rigidity, and light preload is applied for turning at high speed. It is desirable. For this reason, in the rotating shaft used by switching between the low speed rotation and the high speed rotation, a contradiction occurs in the preload surface.

  On the other hand, various devices capable of switching the magnitude of the preload have been devised for the spindle of a machine tool. For example, a preload adjusting ring is provided between the outer ring of the bearing that supports the main shaft and the housing, pressure fluid is supplied from a supply portion provided in the housing, and the outer ring is reduced in diameter through the preload adjusting ring to switch the preload. Such a preload variable bearing unit is known (for example, see Patent Document 1). Further, a groove is formed between the above preload adjusting ring and the housing so that the pressure by the pressure fluid is applied evenly to the preload adjusting ring (for example, see Patent Document 2), the preload adjusting ring and the housing. Are connected with pins to prevent the occurrence of creep (for example, see Patent Document 3). Further, in the angular ball bearing, a pressure chamber is provided between the groove portion and the inner peripheral surface of the housing or the outer peripheral surface of the shaft using a sleeve having a groove portion having a U-shaped cross section. Has been disclosed (see, for example, Patent Document 4).

JP 7-24603 A JP-A-8-174306 JP-A-8-177852 JP 2010-190346 A

However, the variable preload bearing unit described in Patent Documents 1 to 3 has a structure in which the preload adjusting ring is positioned in the radial direction by the housing and the axial positioning is performed by the spacers provided on both sides of the preload adjusting ring. In addition, since it is necessary to provide an O-ring for sealing the pressure chamber in the preload adjusting ring, there is a problem that the axial length of the bearing unit becomes long. For this reason, there has been a problem that it is difficult to adopt the rotary table of the machine tool in which the axial length is limited. Further, by compressing the preload adjusting ring with the pressure fluid, the gap between the housing and the preload adjusting ring is increased, and the rigidity of the entire bearing device system may be reduced, thereby reducing the effect of applying the preload. In the preload variable bearing unit described in Patent Document 2, a groove is provided in the preload adjusting ring so that pressure by the pressure fluid is evenly applied. However, since the thickness of the preload adjusting ring is not uniform, the preload adjusting ring Is not evenly compressed, and as a result, the outer ring cannot be uniformly reduced in diameter, leaving room for improvement. In the case of rotating tables and spindles for machine tools, changes in rotation accuracy due to deformation of the outer ring and inner ring lead to defects in properties such as stitching on the machined surface and deterioration of gloss. It was.
Further, in Patent Document 4, there is a possibility that the clearance between the sleeve and the housing or the shaft increases due to the compression or expansion of the sleeve by the pressure fluid, and the rigidity of the entire system of the bearing device is lowered.

  The present invention has been made in view of the above-described problems, and its purpose is to increase the rigidity of the entire system without increasing the axial length, and to increase the rigidity of the preload continuously or stepwise as necessary. It is an object of the present invention to provide a bearing device that can be switched and maintain good bearing rotation accuracy, and a rotary table and spindle device of a machine tool including the bearing device.

The above object of the present invention can be achieved by the following constitution.
(1) An angular bearing having an outer ring, an inner ring, and a plurality of rolling elements that have a contact angle and are arranged between the outer ring and the inner ring so as to be freely rollable;
An annular sleeve having a hollow cross section, which is fitted to the outer peripheral surface of the outer ring and has a sealed pressure chamber formed therein, capable of supplying pressure fluid;
A bearing device capable of switching the preload of the angular bearing by the pressure of the pressure fluid supplied to the pressure chamber,
A radially inner circumferential surface of the pressure chamber is formed so as to intersect with an extension line of the contact angle,
A pressure fluid supply hole that opens to the pressure chamber is formed in a side portion of the sleeve,
A mounting jig attached to the tip of the pipe for supplying the pressure fluid is fixed to the pressure fluid supply hole, and a part of the mounting jig is formed on a housing or an outer ring presser fastened to the housing. Further, the bearing device is arranged in a hole for piping in which the piping is routed.
(2) an angular bearing having an outer ring, an inner ring, and a plurality of rolling elements that have a contact angle and are arranged between the outer ring and the inner ring so as to be freely rollable;
An annular sleeve having a hollow cross section, which is fitted to the inner peripheral surface of the inner ring and has a sealed pressure chamber formed therein capable of supplying pressure fluid;
A bearing device capable of switching the preload of the angular bearing by the pressure of the pressure fluid supplied to the pressure chamber,
The radially outer peripheral surface of the pressure chamber is formed so as to intersect with an extension line of the contact angle,
A pressure fluid supply hole that opens to the pressure chamber is formed in a side portion of the sleeve,
A mounting jig attached to the tip of a pipe for supplying the pressure fluid is fixed to the pressure fluid supply hole, and a part of the mounting jig is formed on a shaft, and the pipe is routed. A bearing device arranged in a hole for piping.
(3) A fixed position preload is preliminarily applied to the angular bearing, and the bearing device according to (1) or (2) above.
(4) The angular bearing is composed of a pair of angular bearings combined in the rear or front direction,
4. The bearing device according to any one of (1) to (3), wherein a width of the sleeve is equal to or less than a width between outer end surfaces in the axial direction of the pair of angular bearings.
(5) A rotary table for a machine tool comprising the bearing device according to any one of (1) to (4).
(6) A spindle device for a machine tool, comprising the bearing device according to any one of (1) to (4).

  According to the bearing device of the present invention, an angular bearing and an annular sleeve having a hollow cross-section, in which a pressure chamber capable of supplying pressure fluid is formed, and is fitted to the outer peripheral surface of the outer ring or the inner peripheral surface of the inner ring. And the radially inner circumferential surface or the radially outer circumferential surface of the pressure chamber is formed so as to intersect the extended line of the contact angle. Thus, by supplying the pressure fluid to the pressure chamber, it is possible to switch the preload of the angular bearing by reducing the diameter of the outer ring or expanding the diameter of the inner ring via the sleeve. Further, since the pressure chamber is formed inside, the outer diameter of the sleeve is enlarged at the same time and the sleeve and the housing are in close contact, or the inner diameter of the sleeve is reduced and the sleeve and the shaft are in close contact with each other. The rigidity of the system is increased.

  In addition, since a part of the mounting jig fixed to the pressure fluid supply hole is disposed in the piping hole, it is possible to provide a sleeve anti-rotation function.

  Furthermore, since the angular bearing is preliminarily provided with a fixed position preload, by controlling the supply of pressure fluid to the pressure chamber, the preload is switched to light preload during high speed rotation and heavy preload during low speed rotation. A suitable preload can be applied. Further, if necessary, the preload may be switched in two or more stages or continuously by controlling the supply of the pressure fluid.

  Further, since the width of the sleeve is equal to or less than the width between the axial outer end surfaces of the pair of angular bearings, a bearing device capable of switching the preload without increasing the axial length is obtained. It is also possible to suppress the long axis of the mechanical device due to the incorporation of the bearing device.

  Such a bearing device is suitable for application to a rotary table or a spindle device of a machine tool that is used by switching the rotational speed between a low speed and a high speed and has a limited axial length.

It is sectional drawing of the turntable of 1st Embodiment which concerns on this invention. It is principal part sectional drawing of the bearing apparatus which applied the angular bearing combined with the back surface shown in FIG. 1 to the inner ring | wheel rotation mechanism. It is sectional drawing which shows the relationship between the angular bearing and sleeve of the bearing apparatus shown in FIG. It is sectional drawing for demonstrating the relational expression of the pressure which acts on a thick cylinder, and an outer diameter shrinkage | contraction amount. It is a graph which shows the relationship between the pressure of the pressure fluid supplied to a sleeve, and the magnitude | size of a preload. It is a conceptual diagram which shows the state (a) before and behind a deformation | transformation of the sleeve by supply of a pressure fluid, the state (b) before and after a deformation | transformation of a bearing, and the state (c) before and after a deformation | transformation of a bearing apparatus. It is principal part sectional drawing of the bearing apparatus of 2nd Embodiment which applied the angular bearing combined with the back surface to the outer ring | wheel rotation mechanism. It is principal part sectional drawing of the bearing apparatus of 3rd Embodiment which applied the angular bearing combined with the back surface which has a thin outer ring | wheel to the inner ring | wheel rotation mechanism. It is principal part sectional drawing of the bearing apparatus of 4th Embodiment which applied the angular bearing combined with the back surface provided with the non-split type sleeve to the inner ring | wheel rotation mechanism. It is a principal part sectional view of a bearing device of a 5th embodiment which applied a pressure fluid supply hole to the housing side, and applied an angular bearing combined with back to an inner ring rotating mechanism. It is principal part sectional drawing of the bearing apparatus of the modification which shows the case where a pressure fluid supply hole is provided in the internal diameter side ring.

Hereinafter, each embodiment of the bearing device according to the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a sectional view of a turntable to which a bearing device according to a first embodiment of the present invention is applied. The rotary table 10 of the machine tool includes a housing 11, a bearing device 12, and a table 13. The bearing device 12 supports the rotating shaft 14 of the table 13 on the housing 11 so as to be rotatable. The rotary table 10 includes a motor 17 including a rotor 15 that is externally fitted and fixed to a rotary shaft 14 and a stator 16 that is internally fitted and fixed to the housing 11 so as to face the rotor 15, and supplies power to the stator 16. Therefore, the rotating shaft 14, that is, the table 13 is rotatable.

  As shown in FIG. 2, the bearing device 12 has an inner ring 21, an outer ring 22, and balls 23 that are a plurality of rolling elements that are arranged to freely roll between the inner and outer rings 21 and 22, and are combined in the back surface. A pair of angular bearings 24, 24 and an annular sleeve 30 that is fitted onto the outer peripheral surfaces 22a, 22a of the outer rings 22, 22 are provided.

  Each outer ring 22, 22 is fitted into the housing 11 via a sleeve 30. Specifically, the sleeve 30 is fitted into the housing 11, and the outer rings 22 and 22 are fitted into the sleeve 30. Each outer ring 22, 22 is sandwiched and fixed between a step part 26 provided in the housing 11 by an outer ring presser 25 fastened to the housing 11. The fitting between the housing 11 and the sleeve 30 and the fitting between the sleeve 30 and each of the outer rings 22 and 22 of the angular bearings 24 and 24 may be any of an interference fit, an intermediate fit, and a clearance fit.

  Each inner ring 21, 21 is externally fitted to the small-diameter portion 14 a of the rotating shaft 14, and is pressed in the axial direction by an inner ring presser 27 fastened to the rotating shaft 14, so that it is narrow between the step portion 28 of the rotating shaft 14. It is held and fixed. Thereby, a fixed position preload (light preload described later) is applied to the pair of angular bearings 24, 24.

  Referring also to FIG. 3, the sleeve 30 has substantially the same axial width, and includes an inner diameter side ring 31 and an outer diameter side ring 32 that are fitted to each other. The inner diameter side ring 31 has outward flanges 31 a at both axial ends of the outer peripheral surface, and an annular outer peripheral groove 33 is formed at the axial intermediate portion of the outer peripheral surface. Further, the outer diameter side ring 32 has inward flanges 32a at both axial ends of the inner peripheral surface, and an annular inner peripheral groove 34 is formed in the middle of the inner peripheral surface in the axial direction. That is, the axially intermediate portion of the inner diameter side ring 31 and the outer diameter side ring 32 is a thin portion having a uniform thickness that can be easily elastically deformed in the radial direction.

  The outer diameter side ring 32 is fitted into the inner diameter side ring 31 at both ends in the axial direction, and is fitted by press fitting, shrink fitting or the like. Thereby, a hollow cross section is defined by the annular outer circumferential groove 33 and the annular inner circumferential groove 34, and a sealed pressure chamber 35 is formed inside the sleeve 30.

  The diameters of the two fitting portions at both axial ends of the inner diameter side ring 31 and the outer diameter side ring 32 are as shown in FIG. 3 in consideration of the ease of assembly of the inner diameter side ring 31 and the outer diameter side ring 32. Moreover, it is preferable that the diameters are different from each other. In addition, the diameter of the fitting part of the inner diameter side ring 31 and the outer diameter side ring 32 may be the same diameter.

  As shown in FIG. 2, a pressure fluid supply hole 36 communicating with the pressure chamber 35 is formed in the side portion of the sleeve, that is, the inward flange 32 a of the outer diameter side ring 32, and screwed into the pressure fluid supply hole 36. A pressure fluid supply device (not shown) is connected via a pipe 37 connected to a nipple 38 as a mounting jig. As a result, the pressure fluid is supplied from the pressure fluid supply device to the pressure chamber 35 via the pipe 37.

  Since a part of the pipe 37 and the nipple 38 is disposed in the pipe hole 25a provided in the outer ring retainer 25, the nipple 38 also functions as a rotation stop of the sleeve 30, and a dedicated rotation stop such as a pin is provided. There is no need to provide it. As the pressure fluid, any pressure fluid such as compressed air or pressure oil can be used.

  In the inner ring 31, the outer circumferential surface of the annular outer circumferential groove 33 that constitutes the radially inner circumferential surface of the pressure chamber 35 has an extension line CL of the contact angle α of the pair of angular bearings 24, 24 and a position Pa in the axial direction. , Pa so as to intersect with each other. For this reason, the axial length L3 of the annular outer circumferential groove 33 of the inner ring 31 is such that the extension line CL of the contact angle α of the pair of angular bearings 24, 24 intersects the outer circumferential surface of the annular outer circumferential groove 33. It is longer than the length L4 (L4 <L3).

  As shown in FIG. 3, the axial length L2 of the sleeve 30 is equal to the width L1 between the axial outer end surfaces of the pair of angular bearings 24, 24 or is preferably 0 to 0 than the width L1. 0.5 mm, and more desirably about 0.010 to 0.050 mm (L2 ≦ L1).

  The outer rings 22 and 22 of the pair of angular bearings 24 and 24 are compressed and fixed in the axial direction by about 0.01 mm to 0.03 mm by an outer ring presser 25 fastened to the housing 11. Moreover, since the axial direction intermediate part of the pressure chamber 35 of the sleeve 30 is a thin part, when an axial force is applied, the shape is distorted and the bearing outer ring may be deformed unevenly. Accordingly, it is desirable that the axial length L2 of the sleeve 30 is smaller than the width L1 between the axial outer end surfaces of the pair of angular bearings 24, 24.

  FIG. 4 is a cross-sectional view for explaining the relational expression between the pressure acting on the thick cylinder and the outer diameter contraction amount. When the pressure fluid is applied to the sleeve 30, the contraction of the groove portion of the inner diameter side ring 31 is shown. The amount is determined from equation (1).

  Here, ΔD is the groove outer diameter contraction amount of the inner ring 31, D is the groove outer diameter, d is the inner diameter, P is the pressure of the pressure fluid, E is the Young's modulus, and υ is the Poisson's ratio.

  As can be seen from the equation (1), the closer the inner diameter d is to the outer diameter D, in other words, the smaller the wall thickness (D−d) is, the larger the outer diameter shrinkage ΔD is, which acts on the outer rings 22 and 22. The radial compression force to be increased. Accordingly, in order to effectively apply the pressure fluid to the angular bearings 24, 24, the radial thickness (thickness) (D−d) / 2 of the groove portion of the inner diameter side ring 31 should be made as small as possible. Is desirable.

  FIG. 5 shows that the pressure fluid pressure is applied to the entire outer ring 22, 22 of the pair of angular bearings 24, 24 combined on the back, in other words, the radial thickness ((D−d) / 2) is zero. It shows the relationship between the pressure fluid pressure when the pressure fluid pressure is applied to the sleeve 30 and the change (increase) in the bearing preload that occurs when the outer rings 22 are contracted and deformed by this pressure. Here, FIG. 5 uses angular bearings 24 and 24 each having a bearing size of 170 mm in inner diameter × 215 mm in outer diameter × 13.5 mm in width and made of bearing steel, and a sleeve made of carbon steel for machine structure. Thus, the initial preload load before the sleeve hydraulic load is calculated as 1000N. As can be seen from FIG. 5, the bearing preload changes approximately in proportion to the pressure fluid pressure, so that the preload can be switched by controlling the pressure fluid pressure.

  Hereinafter, based on FIG. 6 which shows the state before and behind a deformation | transformation of the sleeve by the supply of pressure fluid, a bearing, and a bearing apparatus, the effect | action of this embodiment is demonstrated.

  In the bearing device 12 of the first embodiment, as shown in FIG. 6B, when the angular bearings 24, 24 are combined, in general, in an unloaded state, the contact angle extension lines of the bearings 24, 24 are extended. Clearance g is set in the raceway (inner ring or outer ring) far from the position where CL intersects. Preload is applied to the bearing by applying load p until the normal clearance g is in close contact with the clearance ring. Is done. For this reason, a fixed position preload (light preload) is applied by pressing the inner rings 21, 21 of the pair of angular bearings 24, 24 combined in the back surface in a direction approaching each other. In general, each inner ring 21, 21 that is a rotating wheel is fitted to the rotating shaft 14 with a tight fit, so that deformation of the bearing due to preload appears in each outer ring 22, 22. That is, by applying a preload, a force in the direction of arrow A acts on each outer ring 22, 22 via a ball 23, and an extension line CL of the contact angle α and outer peripheral surfaces 22 a, 22 a of each outer ring 22, 22 are connected. It is elastically deformed (expanded diameter) outward in the radial direction with the vicinity of the intersecting position as the center.

  On the other hand, when the pressure fluid supplied from the pressure fluid supply device is supplied to the pressure chamber 35 through the pressure fluid supply hole 36, as shown in FIG. Part) is elastically deformed in the radial direction. That is, the thin portion of the inner diameter side ring 31 is elastically deformed and reduced in diameter in the radial direction, and the thin portion of the outer diameter side ring 32 is elastically deformed in the radial direction and expanded in diameter. At this time, the position where the deformation amount of the sleeve 30 is large is in the vicinity of the substantially central portion in the axial direction, and the elastic deformation positions of the outer rings 22 and 22 when the preload is applied to the pair of angular bearings 24 and 24 combined on the back surface, That is, it corresponds to the position where the extended line CL of the contact angle α intersects the outer peripheral surfaces 22a, 22a of the outer rings 22, 22.

  Accordingly, as shown in FIG. 6C, when the pressure fluid is supplied to the pressure chamber 35, the sleeve 30 is elastically deformed (the inner diameter side ring 31 is reduced in diameter), and the outer rings 22 of the pair of angular bearings 24, 24 are respectively. , 22, in particular, the vicinity of the position where elastic deformation (expansion) is caused by the fixed position preload is compressed in the radial direction, and the deformation of the outer rings 22, 22 and the sleeve 30 is offset. Thereby, in addition to the fixed position preload provided previously, the preload by pressure fluid is further added to a pair of angular bearings 24 and 24, and a heavy preload is provided.

  At the same time, the thin portion of the outer diameter side ring 32 expands radially outward, the outer diameter side ring 32 contacts the housing 11, and the contact rigidity between the housing 11 and the sleeve 30 increases. Thus, the rigidity of the entire system is improved. As a result, when the pressure fluid is supplied, the gap between the housing 11 and the sleeve 30 is increased, and as a result, the problem that the rigidity of the entire system of the bearing device 12 is reduced is solved. Due to the same effect, when the sleeve 30 and the housing 11 are fitted to each other with a clearance, the clearance between the sleeve 30 and the housing 11 is reduced by the expansion of the outer diameter side ring 32 of the sleeve 30, so that the sleeve 30 and the housing 11 are coaxial. The degree of rotation is improved and the rotation accuracy is improved.

  Therefore, by controlling the pressure fluid supplied to the pressure chamber 35, the preload of the pair of angular bearings 24, 24 can be switched between the light preload and the heavy preload. Thereby, when rotating the rotating shaft 14 at a high speed, a light preload by a fixed position preload is applied, and when rotating at a low speed, a pressure fluid is supplied to the pressure chamber 35 to apply a heavy preload.

  The fitting between the housing 11 and the sleeve 30 and the fitting between the sleeve 30 and each of the outer rings 22 and 22 of the angular bearings 24 and 24 are any of an interference fit, an intermediate fit, and a clearance fit. Although the outer diameter of the sleeve 30 is increased and the inner diameter is reduced, the sleeve 30 is brought into contact with the outer rings 22 and 22 of the housing 11 and the angular bearings 24 and 24, and the pressure fluid pressure is increased. It is desirable that the gaps C1 and C2 between the housing 11 and the sleeve 30 and between the sleeve 30 and the outer rings 22 and 22 are as small as possible. Considering the assemblability, for example, it is preferably about 5 to 30 μm.

  In addition, when the sleeve 30 is formed by the inner diameter side ring 31 and the outer diameter side ring 32 that are fitted to each other, the inner and outer diameters of the sleeve 30 change due to the fitting of the rings 31 and 32, and the housing 11 and each Although there is a possibility of affecting the fit with the outer rings 22, 22, after fitting both the rings 31, 32, the inner and outer peripheral surfaces of the sleeve 30 are finished and the accuracy is controlled, whereby the housing 11 and each outer ring 22, The fitting with 22 can be managed in an appropriate state.

  As described above, in the bearing device 12 according to the present embodiment, the pressure of the pressure fluid is applied to the elastically deformed position by the fixed position preload of the pair of angular bearings 24, 24 via the sleeve 30, so that Unlike the bearing device, it is not necessary to apply pressure by the pressure fluid to the entire surface of the outer ring. Therefore, the axial width L2 of the sleeve 30 can be made smaller than the width L1 between the axial outer end surfaces of the pair of angular bearings 24, 24, and the preload can be switched without increasing the length of the bearing device 12. The bearing device 12 can be made.

  Further, since the sleeve 30 is formed with a sealed annular pressure chamber, the sleeve is deformed in both radial directions so that pressure is applied to the outer rings 22 and 22 and simultaneously pressure is applied to the housing 11. The rigidity of the entire system can be improved by the close contact between the sleeve 30 and the housing 11.

  Further, since the pressure chamber 35 is formed by fitting the inner diameter side ring 31 and the outer diameter side ring 32, the sleeve 30 can operate the fluid pressure without leakage by managing the interference of the fitting portion. Therefore, the O-ring for sealing the pressure chamber, which has been conventionally required, can be eliminated.

In addition, since a part of the nipple 38 fixed to the pressure fluid supply hole 36 is disposed in the piping hole 25a provided in the outer ring retainer 25, it is possible to give a sleeve detent function.
In addition, although the bearing apparatus 12 of this embodiment demonstrated the pair of angular bearings 24 and 24 combined with the back surface, it is applied similarly to a pair of angular bearings 24 and 24 combined with the front surface.

(Second Embodiment)
FIG. 7 is a cross-sectional view of a main part of a bearing device according to a second embodiment in which an angular bearing combined with a back surface is applied to an outer ring rotating mechanism. In the bearing device 40 of the second embodiment, a pair of angular bearings 24, 24 are arranged in a rear combination, and the sleeve 30 is arranged between the inner peripheral surface of each inner ring 21, 21 and the outer peripheral surface of the fixed shaft 41. Is done. That is, each inner ring 21, 21 is fitted on the fixed shaft 41 via the sleeve 30, and each outer ring 22, 22 is fitted on the housing 11. Each of the inner rings 21 and 21 is pressed in the axial direction by an inner ring presser 27 fastened to the fixed shaft 41 and is sandwiched and fixed between the step portions 28 of the fixed shaft 41. Further, each outer ring 22, 22 is fitted in the rotating housing 11, and is sandwiched and fixed between a step part 26 provided in the housing 11 by an outer ring presser 25 fastened to the housing 11. As a result, a fixed position preload (light preload) is applied to the pair of angular bearings 24, 24.

  Similar to the sleeve of the first embodiment, the sleeve 30 includes an inner diameter side ring 31 in which an annular outer circumferential groove 33 is formed in the axially intermediate portion of the outer circumferential surface, and an annular inner circumferential groove 34 in the middle of the inner circumferential surface in the axial direction. The formed outer diameter side ring 32 is fitted to each other to form a sealed annular pressure chamber 35 inside the sleeve 30.

  In the outer diameter side ring 32, the inner peripheral surface of the annular inner peripheral groove 34 that constitutes the outer peripheral surface in the radial direction of the pressure chamber 35 has an extension line CL of the contact angle α of the pair of angular bearings 24, 24 in the axial direction. , At positions Pa and Pa. That is, the axial length L3 of the annular inner circumferential groove 34 of the outer diameter side ring 32 is a position where the extension line CL of the contact angle α of the pair of angular bearings 24, 24 intersects the inner circumferential surface of the annular inner circumferential groove 34. It is longer than the length L4 between Pa and Pa (L4 <L3). Further, the intermediate portion in the axial direction of the sleeve 30 forming the annular inner circumferential groove 34 constitutes a thin portion that can be easily elastically deformed in the radial direction.

  A pressure fluid supply hole 36 communicating with the pressure chamber 35 is formed in the inward flange 32 a of the outer diameter side ring 32, and is connected to a pressure fluid supply device (not shown) via a pipe 37 and a nipple 38. Fluid is supplied.

  Also in this case, since the pipe 37 and a part of the nipple 38 are disposed in the pipe hole 41a provided in the fixed shaft 41, the nipple 38 also functions as a rotation stop of the sleeve 30, and a pin or the like There is no need to provide a dedicated rotation stop.

When a heavy preload is applied to the pair of angular bearings 24, 24, the pressure fluid is supplied from the pressure fluid supply hole 36 to the pressure chamber 35, and the thin portion of the sleeve 30 (the inner diameter side ring 31 and the outer diameter side ring 32) has a diameter. A fixed position preload (light weight) applied in advance to the pair of angular bearings 24, 24 by elastically deforming (expanding diameter) outward in the direction and pressing the inner rings 21, 21 outward in the radial direction to expand the diameter. In addition to the preload), a preload is further applied by a pressurized fluid to give a heavy preload. At this time, since the sleeve 30 applies pressure to the inner rings 21 and 21 as well as pressure to the fixed shaft 41, the tightness between the sleeve 30 and the fixed shaft 41 improves the rigidity of the entire system. can do.
In addition, about another structure and effect | action, it is the same as that of the bearing apparatus 12 of 1st Embodiment.

  In addition, although the bearing apparatus 40 of this embodiment demonstrated the pair of angular bearings 24 and 24 combined with the back surface, it is applied similarly to a pair of angular bearings 24 and 24 combined with the front surface.

(Third embodiment)
FIG. 8 is a cross-sectional view of a main part of a bearing device in which an angular bearing combined with a back surface having a thin outer ring is applied to an inner ring rotating mechanism. In the pair of angular bearings 24, 24 shown in FIG. 8, the pitch circle diameter φdm of the rolling element 23 is based on the average diameter (φD + φd) / 2 of the outer diameter of each outer ring 22, 22 and the inner diameter of each inner ring 21, 21. It is set large (φdm> (φD + φd) / 2). Here, φD is the outer diameter of each outer ring 22, 22, and φd is the inner diameter of each inner ring 21, 21. That is, the outer rings 22 and 22 are formed thinner than the normal angular bearings 24 and 24 described in the first and second embodiments, and the inner rings 21 and 21 are formed thick.

As described with reference to FIG. 4 and Formula (1), when pressure is applied to the outer periphery of the thick cylinder, the outer diameter shrinkage increases as the wall thickness decreases, so that each outer ring 22, 22 as in this embodiment. By forming the wall thickness of the thin film into a small thickness, the pressure of the pressure fluid acts more effectively, and a large preload can be applied to the angular bearings 24, 24.
About another structure and effect | action, it is the same as that of the bearing apparatus 12 of 1st Embodiment.

(Fourth embodiment)
FIG. 9 is a cross-sectional view of a main part in which a bearing device including a non-dividing sleeve is applied to an inner ring rotating mechanism. In the sleeve 50 of this embodiment, the inner diameter side ring 31 and the outer diameter side ring 32 are integrally formed, and a pressure chamber 35 sealed inside is formed. Such an integrated sleeve 50 is realized, for example, by fitting the inner diameter side ring 31 and the outer diameter side ring 32 and then welding the fitting portion. The integrated sleeve 50 has an advantage that pressure can be effectively used compared to a sleeve formed by fitting the inner diameter side ring 31 and the outer diameter side ring 32 with no risk of leakage of pressure fluid. Have.
Other configurations and functions are the same as those of the bearing device 12 of the first embodiment.

(Fifth embodiment)
FIG. 10 is a cross-sectional view of an essential part of an embodiment in which a pressure fluid supply hole is provided on the housing side in a bearing device in which an angular bearing combined with a back surface is applied to an inner ring rotating mechanism.
In the bearing device 12 of the present embodiment, the pressure fluid supply hole 36, the pipe 37, and the nipple 38 are provided on the outer peripheral surface side of the sleeve 30 (outer diameter side ring 32), and from the pipe hole 11 a provided in the housing 11. It is led out and connected to a pressure fluid supply device (not shown). In the figure, reference numeral 39 denotes a plug.

Also in this embodiment, the pipe 37 and a part of the nipple 38 are disposed in the pipe hole 11a, and a part of the nipple 38 has a function of preventing the sleeve 30 from rotating, so that a dedicated locking part such as a pin is not necessary. .
Other configurations and functions are the same as those of the bearing device 12 of the first embodiment.

  In addition, this invention is not limited to each embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably. For example, in the above description, the example in which the bearing device is applied to the rotary table of the machine tool has been described. However, the bearing device is not limited to the rotary table, and can be similarly applied to the spindle device of the machine tool. Play.

  Further, the form of the supply path for supplying the pressure fluid to the pressure chamber 35 of the sleeve 30 is not particularly limited as long as the pressure fluid can be supplied to the pressure chamber 35, and any form can be adopted. In particular, the pressure fluid supply hole 36 may be set at any position on the side portion of the sleeve 30. In the present embodiment, the pressure fluid supply hole 36 is formed on the inward flange 32a of the outer diameter side ring 32 of the sleeve 30, As shown in FIG. 11, it may be formed on the outward flange 31 a of the inner diameter side ring 31. When the sleeve 30 made of two parts of the inner diameter side and outer diameter side rings 31 and 32 is fitted by interference fit, it is necessary to heat the outer diameter side ring 32 to a high temperature depending on the amount of interference. is there. At this time, if the pressure fluid supply hole 36 is provided in the large-diameter part, thermoplastic deformation or burn-out may occur, and desired performance may not be obtained. In addition, when a female screw is formed in the pressure fluid supply hole 36, the function may be impaired due to thermoplastic deformation or burning cracking. Therefore, by providing the pressure fluid supply hole 36 in the inner diameter side ring 31 in advance, it is possible to avoid the above-described problem due to heating.

  In the bearing device of the present invention, the number of rows of angular ball bearings may be a combination of two or more rows depending on the required rigidity.

DESCRIPTION OF SYMBOLS 10 Rotary table 12, 40 Bearing apparatus 21 Inner ring 22 Outer ring 22a Outer ring outer peripheral surface 23 Ball (rolling element)
24 Angular Bearing 30 Sleeve 31 Inner Diameter Side Ring 32 Outer Diameter Side Ring 33 Annular Outer Groove 34 Annular Inner Groove 35 Pressure Chamber CL Contact Angle Extension Line L1 Width Between Each Axial Outer End Face of Paired Angular Bearing L2 Sleeve Width Pa Position where the extended line of the contact angle intersects the radial circumferential surface of the pressure chamber α Contact angle

Claims (6)

An angular bearing having an outer ring, an inner ring, and a plurality of rolling elements that have a contact angle and are arranged between the outer ring and the inner ring so as to be freely rollable;
An annular sleeve having a hollow cross section, which is fitted to the outer peripheral surface of the outer ring and has a sealed pressure chamber formed therein, capable of supplying pressure fluid;
A bearing device capable of switching the preload of the angular bearing by the pressure of the pressure fluid supplied to the pressure chamber,
A radially inner circumferential surface of the pressure chamber is formed so as to intersect with an extension line of the contact angle,
A pressure fluid supply hole that opens to the pressure chamber is formed in a side portion of the sleeve,
A mounting jig attached to the tip of the pipe for supplying the pressure fluid is fixed to the pressure fluid supply hole, and a part of the mounting jig is formed on a housing or an outer ring presser fastened to the housing. Further, the bearing device is arranged in a hole for piping in which the piping is routed. An angular bearing having an outer ring, an inner ring, and a plurality of rolling elements that have a contact angle and are arranged between the outer ring and the inner ring so as to be freely rollable;
An annular sleeve having a hollow cross section, which is fitted to the inner peripheral surface of the inner ring and has a sealed pressure chamber formed therein capable of supplying pressure fluid;
A bearing device capable of switching the preload of the angular bearing by the pressure of the pressure fluid supplied to the pressure chamber,
The radially outer peripheral surface of the pressure chamber is formed so as to intersect with an extension line of the contact angle,
A pressure fluid supply hole that opens to the pressure chamber is formed in a side portion of the sleeve,
A mounting jig attached to the tip of a pipe for supplying the pressure fluid is fixed to the pressure fluid supply hole, and a part of the mounting jig is formed on a shaft, and the pipe is routed. A bearing device arranged in a hole for piping.   The bearing device according to claim 1, wherein a fixed position preload is preliminarily applied to the angular bearing. The angular bearing is composed of a pair of angular bearings that are combined in a rear surface or a front surface.
4. The bearing device according to claim 1, wherein a width of the sleeve is equal to or less than a width between outer end surfaces in the axial direction of the pair of angular bearings. 5.   A rotary table for a machine tool, comprising the bearing device according to any one of claims 1 to 4.   A spindle device for a machine tool, comprising the bearing device according to any one of claims 1 to 4.

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