Bearing device

Abstract

This bearing device (1) has a structure in which a cylindrical outer ring spacer (26) sandwiched between a first outer ring (32) of a first bearing (24) and a second outer ring (36) of a second bearing (25) in the axial direction has a double structure comprising an outer ring (26a) and an inner ring (26b), and an electric circuit (30) provided in the inner space of the outer ring spacer (26) is divided into a plurality of partial circuits. A circuit board (30a) on which each partial circuit is mounted is disposed such that the mounting surface thereof is parallel to the axial direction of the outer ring spacer (26), and a part of the circuit board is fixed in a state of being fitted into a groove (26e) provided in the inner ring (26b).

Description

Technical Field

[0001] The present invention relates to a bearing device in which a sensor is installed in a spacer between two rolling bearings. Background Art

[0002] In machine tools such as machining centers and lathes, or other industrial machines, a spindle device is used that supports a spindle (rotating shaft) for mounting objects such as tools and workpieces so as to be rotatable. In the fields of use of such spindle devices, high-speed spindle rotation speeds for improving machining accuracy and production efficiency, and high functionality and high performance of condition monitoring are required.

[0003] In order to meet the above-mentioned requirements, as a bearing device for supporting the spindle of the spindle device, a bearing device assembled with various sensors has been proposed.

[0004] For example, in the bearing device proposed in Patent Document 1, two rolling bearings are arranged at intervals in the axial direction inside a cylindrical housing, and sensors such as a vibration sensor and a temperature sensor, and a circuit for processing the outputs of the above sensors are provided inside an outer ring spacer assembled between the outer rings of these two bearings. By controlling a pump for discharging lubricating oil based on the outputs of the respective sensors, bearing burn caused by high-speed spindle rotation speed is prevented.

[0005] In addition, the following bearing device is also often practically applied, that is, a load sensor is installed in an outer ring spacer between two rolling bearings so as to be able to detect changes in load such as an increase in preload caused by heat generation of each bearing and a cutting load applied to the spindle from the outside, thereby making condition monitoring highly functional and high performance.

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2020-031488

[0007] However, in the bearing device of Patent Document 1 described above, the circuit for processing the output of the sensor is divided into a plurality of partial circuits, and each of these partial circuits is separately mounted on a plurality of flat circuit boards and connected to each other by electric wires.

[0008] Here, in each circuit board, the mounting surface (front and back surfaces) on which electronic components such as sensors and partial circuits are mounted is housed in the outer ring spacer in a manner parallel to the axial direction of the outer ring spacer. Therefore, compared with the case where the mounting surface is arranged orthogonal to the axial direction of the outer ring spacer, the mounting area can be expanded and a plurality of electronic components can be mounted.

[0009] However, a plurality of circuit boards connected to each other through wires are not fixed to the outer ring spacer, but are disposed in the outer ring spacer in a movable state. Therefore, the unfixed circuit boards repeatedly collide with the inner side surface of the outer ring spacer due to vibration when the main shaft rotates, which may cause damage to the circuit boards themselves and the electronic components mounted on their mounting surfaces. Summary of the Invention

[0010] Accordingly, an object of the present invention is to provide a bearing device capable of incorporating a plurality of electronic components and enabling the electronic components to function stably for a long period of time.

[0011] To solve the above problems, the bearing device of the present invention adopts the following structure (Structure 1): A first bearing and a second bearing are disposed at intervals in the axial direction inside a cylindrical housing. The first bearing has: a first outer ring, a first inner ring rotatably provided radially inside the first outer ring, and a plurality of first rolling elements assembled between the first outer ring and the first inner ring. The second bearing has: a second outer ring, a second inner ring rotatably provided radially inside the second outer ring, and a plurality of second rolling elements assembled between the second outer ring and the second inner ring. A cylindrical outer ring spacer is disposed in a state of being sandwiched between the first outer ring and the second outer ring in the axial direction. The outer ring spacer is composed of an outer ring that contacts the first outer ring and the second outer ring in the axial direction and an inner ring disposed radially inside the outer ring. A sensor and a circuit for processing the output of the sensor are provided in a space formed between the outer ring and the inner ring. In the bearing device, the circuit is divided into a plurality of partial circuits, and each of the partial circuits is separately mounted on a plurality of flat circuit boards and connected to each other through wires. Each of the circuit boards is fixed to a board fixing portion provided on the outer ring spacer.

[0012] According to the above Structure 1, by arranging a plurality of circuit boards carrying partial circuits such that their mounting surfaces are parallel to the axial direction of the outer ring spacer, it is possible to increase the mounting area of each circuit board and incorporate a plurality of electronic components. Moreover, the circuit boards fixed to the board fixing portion of the outer ring spacer do not collide with the outer ring spacer due to vibration during the rotation of the rotating shaft supported by the bearing device, etc. Therefore, the electronic components can function stably for a long period of time.

[0013] Here, in the above-described structure 1, the following structure (structure 2) can be adopted: A wireless communication module is included in the above circuit. An antenna for wireless communication formed on a circuit board generates directivity such that the radio wave intensity is strong in the normal direction of the plane forming the antenna. Therefore, in the case of adopting structure 2, the following structure (structure 3) can be set: The circuit board on which the above wireless communication module is mounted is arranged in a posture where the mounting surface of the wireless communication module is orthogonal to the axial direction of the above outer ring spacer. In this way, the direction in which the radio wave intensity of the wireless communication module is strong is parallel to the axial direction of the bearing device, so that the radio wave can easily reach the outside of the device in which the bearing device is assembled, and communication with an external control device or the like can be performed more stably.

[0014] In addition, in any of the above structures 1 to 3, when preloading is applied to the above first bearing and the above second bearing, and for the above outer ring spacer, the preloading only acts on the above outer ring, the following structure (structure 4) is preferably adopted: The above sensor is arranged in a state of being in contact with the above outer ring. In this way, changes in the preloading load, temperature changes of each bearing, changes in vibration caused by bearing damage or machining abnormalities, etc. can be detected with higher sensitivity.

[0015] In addition, in any of the above structures 1 to 4, the following structure (structure 5) is preferably adopted: The above outer ring is formed of metal or ceramic to form a high-rigidity outer ring. And, in any of the above structures 1 to 5, considering the ease of forming the substrate fixing portion, the following structure (structure 6) is preferably adopted: The above inner ring is formed of resin.

[0016] In addition, in the above structure 2 or 3, the following structure (structure 7) is preferably adopted: A cover formed of a non-magnetic material plugs one axial side of the space formed between the above outer ring and the above inner ring.

[0017] As described above, in the bearing device of the present invention, the circuit for processing the sensor output is divided into a plurality of partial circuits, and the circuit boards on which electronic components such as the partial circuits are mounted are respectively fixed to the substrate fixing portions of the outer ring spacer. Therefore, a plurality of electronic components can be built in, and even in the face of vibrations or the like, each circuit board will not collide with the outer ring spacer, and the electronic components can function stably for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a cross-sectional view of a spindle device for a machine tool using the bearing device according to an embodiment of the present invention.

[0019] Figure 2 is an enlarged view showing Figure 1 the main part in a cross-sectional view.

[0020] Figure 3 is along the outer ring spacerFigure 2 Cross-sectional view taken along line III-III.

[0021] Figure 4 is Figure 1 Exploded perspective view of the outer ring spacer.

[0022] Figure 5 is Figure 1 Exploded perspective view of a modified example of the outer ring spacer. Detailed implementation mode

[0023] Hereinafter, embodiments of the present invention will be described based on the drawings. Figure 1 A machine tool spindle device using the bearing device 1 according to the embodiment of the present invention is shown. This spindle device has: a spindle 2 of the machine tool, an outer cylinder 3 that houses the spindle 2, a motor 4 that drives the spindle 2 to rotate, a bearing device 1 of the embodiment that supports the spindle 2 rotatably on the front side in the axial direction ( Figure 1 the left side of), and a rear bearing device 5 that supports the spindle 2 rotatably on the rear side in the axial direction with respect to the motor 4.

[0024] The outer cylinder 3 is formed into a hollow cylindrical shape with both ends open, and houses the bearing device 1 and the motor 4 in order from the front side in the axial direction to the rear side. In Figure 1 , the part of the outer cylinder 3 that houses the bearing device 1 and the part of the outer cylinder 3 that houses the motor 4 are formed seamlessly and integrally, but these two parts may also be formed independently and connected and fixed.

[0025] The spindle 2 is inserted into the outer cylinder 3 in a state where its front end in the axial direction protrudes from the front end opening of the outer cylinder 3. A chuck (not shown) for holding a tool or a workpiece is detachably mounted at the front end of the spindle 2. In addition, a through hole 6 is formed through the spindle 2 in the axial direction, and a drawbar (not shown) of the machine tool is slidably housed in the through hole 6 in the axial direction.

[0026] The motor 4 has: a rotor 7 mounted on the outer periphery of the spindle 2, and an annular stator 8 that imparts a rotational force to the rotor 7. The rotor 7 has: a rotor sleeve 9 fitted to the outer periphery of the spindle 2, and a rotor core 10 fixed to the outer periphery of the rotor sleeve 9. The rotor core 10 is, for example, a laminated body of electromagnetic steel sheets. The rotor sleeve 9 is stopped from rotating by the spindle 2 so as to rotate integrally with the spindle 2. The front end in the axial direction of the rotor sleeve 9 contacts a stepped portion 11 formed on the outer periphery of the spindle 2 and having a stepped surface facing the rear side in the axial direction, and is axially positioned by contacting the stepped portion 11.

[0027] The stator 8 has: a stator core 12 fixed to the inner circumference of the outer cylinder 3; and electromagnetic coils 13 wound around a plurality of tooth portions formed at intervals in the circumferential direction on the stator core 12. Moreover, when the electromagnetic coils 13 are energized, a rotational force is generated in the rotor core 10 by the electromagnetic force acting between the stator core 12 and the rotor core 10, causing the rotor 7 and the main shaft 2 to rotate integrally. Here, as the motor 4, an electromagnetic motor that generates a rotational force by electricity is adopted, but instead of the electromagnetic motor, a motor that generates a rotational force by other power sources such as compressed air may be adopted.

[0028] The rear bearing device 5 has: an annular bearing support member 14 coaxially fixed to the rear end of the outer cylinder 3, and a rolling bearing 15 fitted to the inner circumference of the bearing support member 14. The rolling bearing 15 is a cylindrical roller bearing, and the rolling bearing 15 has: an outer ring 16 fitted to the inner circumference of the bearing support member 14; an inner ring 17 fitted to the outer circumference of the main shaft 2; and a plurality of cylindrical rollers 18 assembled between the outer ring 16 and the inner ring 17.

[0029] An outer ring pressing member 19 is installed on the bearing support member 14. The outer ring pressing member 19 fixes the axial position of the outer ring 16 by contacting the axially rear side surface of the outer ring 16. In addition, on the outer circumference of the main shaft 2, there are assembled: a nut member 20 that pushes the inner ring 17 forward in the axial direction, and an annular spacer 21 assembled between the inner ring 17 and the nut member 20. The nut member 20 is threadedly engaged with an internal thread 22 formed on the outer circumference of the rear end portion of the main shaft 2. The spacer 21 is configured such that its axially front end contacts the axially rear side surface of the inner ring 17, and its axially rear end contacts the axially front side surface of the nut member 20. Moreover, the axially front end of the inner ring 17 contacts the axially rear end of the rotor sleeve 9.

[0030] As Figure 1 and Figure 2 shown, the bearing device 1 has: a housing 23 fixedly provided on the outer cylinder 3, a first bearing 24 fitted to the inner circumference of the housing 23, a second bearing 25 fitted to the inner circumference of the housing 23 at a position axially rearward of the first bearing 24, and an outer ring spacer 26 and an inner ring spacer 27 axially sandwiched between the first bearing 24 and the second bearing 25, and the main shaft 2 is supported by the first bearing 24 and the second bearing 25.

[0031] The first bearing 24 is an angular contact ball bearing, and the first bearing 24 has: a non-rotating first outer ring 32 fitted to the inner circumference of the housing 23, a first inner ring 33 rotatably provided radially inside the first outer ring 32, a plurality of first rotating bodies (here, balls) 34 assembled between the first outer ring 32 and the first inner ring 33, and a retainer 35 that holds the first rotating bodies 34 rotatably.

[0032] The second bearing 25 is an angular contact ball bearing, and the second bearing 25 has: a non-rotating second outer ring 36 that is arranged at an interval in the axial rear direction from the first outer ring 32 and is fitted to the inner circumference of the housing 23, a second inner ring 37 that is rotatably provided on the radial inner side of the second outer ring 36, a plurality of second rolling elements (here, balls) 38 that are assembled between the second outer ring 36 and the second inner ring 37, and a retainer 39 that holds the second rolling elements 38 so as to be rotatable.

[0033] Here, in the first bearing 24, a straight line connecting the contact point between the first inner ring 33 and the first rolling element 34 and the contact point between the first outer ring 32 and the first rolling element 34 inclines rearward in the axial direction from the radial inner side toward the radial outer side. On the other hand, in the second bearing 25, a straight line connecting the contact point between the second inner ring 37 and the second rolling element 38 and the contact point between the second outer ring 36 and the second rolling element 38 inclines forward in the axial direction from the radial inner side toward the radial outer side. That is, the first bearing 24 and the second bearing 25 are arranged in a back-to-back combination.

[0034] As Figures 1 to 4 shown, the outer ring spacer 26 is composed of a metal outer ring 26a fitted to the inner circumference of the housing 23 and a resin inner ring 26b disposed on the radial inner side of the outer ring 26a. The outer ring 26a is formed in a hollow cylindrical shape with both ends open, and three convex portions 26a1 are provided at equal intervals in the circumferential direction on the inner circumference of the axial center portion. In addition, two lubricant supply paths 26c penetrating in the radial direction are provided at specified circumferential positions between the convex portions 26a1.

[0035] On the other hand, the inner ring 26b has a convex portion on a part of the outer circumference of the hollow cylindrical portion with both ends open, and two nozzles 26d communicating with the respective lubricant supply paths 26c of the outer ring 26a are provided at the convex portion. Moreover, portions other than the circumferential position where the convex portion is formed are formed in an L-shaped cross section having an outward convex flange portion at the axial rear end of the cylindrical portion, and the convex portion and the convex flange portion are fixed to the inner circumferential surface of the outer ring 26a. As this fixing method, a method of pressing the convex portion and the convex flange portion of the inner ring 26b into the inner circumferential surface of the outer ring 26a, or a method of bonding the convex portion and the convex flange portion of the inner ring 26b to the inner circumferential surface of the outer ring 26a can be adopted, and the above methods can also be used in combination. In addition, an annular groove is provided around the connection portion of each nozzle 26d with the lubricant supply path 26c, and an O-ring 28 is embedded in the annular groove to prevent leakage of the lubricant (and the liquid anti-oil protection member filled at the beginning of assembly). In addition, a sealing material can be filled instead of the O-ring 28.

[0036] In addition, the axial dimension of the outer ring 26a is formed to be larger than that of the inner ring 26b. Thus, the outer ring 26a is configured such that its axially front end contacts the axially rear side surface of the first outer race 32, and its axially rear end contacts the axially front side surface of the second outer race 36. On the other hand, the inner ring 26b does not contact the first outer race 32 and the second outer race 36, and the axially front side surface 26b1 of the flange portion contacts the convex portion 26a1 on the inner circumferential side of the outer ring 26a, thereby being positioned axially.

[0037] Moreover, a sensor 29 and a circuit 30 for processing the output of the sensor 29 are provided in the space formed between the cylindrical portions of the outer ring 26a and the inner ring 26b. The sensor 29 is, for example, a load sensor, a vibration sensor, or a temperature sensor, and is mounted on the inward-facing plane of each convex portion 26a1 on the inner circumference of the outer ring 26a. The circuit 30 is composed of a sensor signal processing unit, a low-pass / high-pass filter, an amplifier, a power supply, a wireless communication module, etc., and is divided into a plurality of partial circuits. Each of these partial circuits is separately mounted on a plurality of rectangular flat circuit boards 30a, 30b (30b is for the wireless communication module) and is interconnected by wires 30c. In addition, the sensor 29 is also connected to the circuit 30 by the wire 30c.

[0038] Here, the circuit boards 30a on which partial circuits other than the wireless communication module are mounted are all arranged such that the mounting surface (front and back surfaces) is parallel to the axis of the outer race spacer 26. Only the circuit board 30b on which the wireless communication module is mounted is arranged in a posture where the mounting surface is orthogonal to the axis of the outer race spacer 26, so that the normal direction of the circuit board surface on which the antenna is formed, that is, the direction in which the radio wave intensity of the wireless communication module is strong, is parallel to the axis of the bearing device 1. Moreover, each of the circuit boards 30a, 30b is configured such that a part thereof is embedded in the grooves 26e, 26f as substrate fixing portions and is fixed by an adhesive, and the grooves 26e, 26f are provided on the axially front side surface 26b1 of the flange portion of the inner ring 26b.

[0039] In addition, a cover 31 is provided on the axially front side of the outer race spacer 26 and is embedded between the inner circumferential surface of the outer ring 26a and the outer circumferential surface of the cylindrical portion of the inner ring 26b to prevent the intrusion of oil containing foreign matter into the space between the outer ring 26a and the inner ring 26b (the space around the sensor 29 and the circuit 30). The cover 31 is fixed to the outer ring 26a and the inner ring 26b by an adhesive, and this adhesive also serves as a sealing material for preventing the intrusion of oil. Considering the ease of wireless communication, the material of the cover 31 is preferably a non-magnetic material with a small relative dielectric constant and dielectric loss tangent.

[0040] In addition, the outer ring 26a is preferably a high-rigidity outer ring. Thus, although it is made of metal in the above example, it can also be made of ceramic. On the other hand, although the inner ring 26b can also be made of metal or ceramic, considering the ease of forming the substrate fixing portion, as in the above example, it is preferably formed of resin. In addition, although the sensor 29 is directly mounted on the plane of the convex portion 26a1 on the inner peripheral side of the outer ring 26a in the above example, a substrate on which the sensor is mounted can also be mounted on the outer ring, and the substrate can be connected to the circuit by wires.

[0041] Next, as Figure 1 and Figure 2 shown, the inner ring spacer 27, like the outer ring 26a of the outer ring spacer 26, is formed in a hollow cylindrical shape with both ends open. Its front end in the axial direction contacts the side surface on the rear side in the axial direction of the first inner ring 33, and its rear end in the axial direction contacts the side surface on the front side in the axial direction of the second inner ring 37.

[0042] An outer ring pressing member 40 is fixed to the front end in the axial direction of the outer cylinder 3. The outer ring pressing member 40 fixes the axial position of the first outer ring 32 by contacting the side surface on the front side in the axial direction of the first outer ring 32. The outer ring pressing member 40 has a cylindrical portion 41 fitted to the inner periphery of the housing 23 and a flange portion 42 extending radially outward from the front end in the axial direction of the cylindrical portion 41. The flange portion 42 is fixed to the side surface on the front side in the axial direction of the housing 23. In addition, a stepped portion 43 that contacts the side surface on the front side in the axial direction of the first inner ring 33 is formed on the outer periphery of the front end portion in the axial direction of the main shaft 2. The first inner ring 33 is axially positioned by contacting the stepped portion 43.

[0043] A preload nut 44 that pushes the second inner ring 37 forward in the axial direction and an annular spacer 45 assembled between the second inner ring 37 and the preload nut 44 are assembled on the outer periphery of the main shaft 2. The preload nut 44 is threadedly engaged with an internal thread 46 formed in a portion extending forward in the axial direction from a stepped portion 11 on the outer periphery of the main shaft 2. The spacer 45 is configured such that its front end in the axial direction contacts the side surface on the rear side in the axial direction of the second inner ring 37, and its rear end in the axial direction contacts the side surface on the front side in the axial direction of the preload nut 44. A stepped portion 47 that contacts the side surface on the rear side in the axial direction of the second outer ring 36 is formed on the inner periphery of the housing 23. The second outer ring 36 is axially positioned by contacting the stepped portion 47.

[0044] The housing 23 has a cylindrical portion 48 fitted to the inner periphery of the outer cylinder 3 and a flange portion 49 extending radially outward from the front end in the axial direction of the cylindrical portion 48. Cooling grooves 50 for the refrigerant flow for cooling the bearing device 1 are formed on the outer periphery of the cylindrical portion 48. The cooling grooves 50 are a plurality of annular grooves formed at intervals in the axial direction on the outer periphery of the cylindrical portion 48 or spiral grooves extending in a spiral shape on the outer periphery of the cylindrical portion 48. The flange portion 49 contacts and is fixed to the front end in the axial direction of the outer cylinder 3.

[0045] The spindle device for this machine tool has the above structure. By tightening the preload nut 44 when assembling the bearing device 1, the axial force thereof is sequentially transmitted to the spacer 45, the second inner ring 37, the second rolling element 38, the second outer ring 36, the outer ring 26a of the outer ring spacer 26, the first outer ring 32, the first rolling element 34, and the first inner ring 33, and is received by the stepped portion 43 of the spindle 2, thereby applying preload to the first bearing 24 and the second bearing 25. In addition, when a machining load is applied to the spindle 2 due to machining, the machining load is transmitted in the order of the stepped portion 43 of the spindle 2, the first inner ring 33, the first rolling element 34, the first outer ring 32, the outer ring 26a of the outer ring spacer 26, and the second outer ring 36, and is received by the stepped portion 47 on the inner circumference of the housing 23. Therefore, by setting the sensor 29 mounted on the outer ring 26a as a load sensor, the preload and cutting loads can be detected with high sensitivity.

[0046] Moreover, in the bearing device 1 of this embodiment, the outer ring spacer 26 is provided with a double structure composed of an outer ring 26a and an inner ring 26b. The circuit 30 disposed in the inner space of the outer ring spacer 26 together with the sensor 29 is divided into a plurality of partial circuits. The circuit board 30a carrying each partial circuit, among the circuit boards 30a and 30b carrying each partial circuit, on which a partial circuit other than the wireless communication module is mounted, is arranged such that its mounting surface (front and back surfaces) is parallel to the axial direction of the outer ring spacer 26. Therefore, compared with the case where the mounting surface is arranged orthogonal to the axial direction of the outer ring spacer 26, the mounting area can be expanded and a plurality of electronic components can be incorporated.

[0047] In addition, the circuit board 30b carrying only the wireless communication module is arranged with its mounting surface orthogonal to the axial direction of the outer ring spacer 26, such that the direction in which the radio wave intensity of the wireless communication module is strong is parallel to the axial direction of the bearing device 1. Therefore, the radio wave can easily reach the outside of the spindle device in which the bearing device 1 is assembled, and stable communication with an external control device or the like can be performed.

[0048] Furthermore, each of the circuit boards 30a and 30b is fixed to the inner ring 26b of the outer ring spacer 26. Therefore, even when subjected to vibrations during the rotation of the spindle 2 or the like, they will not collide with the outer ring 26a or the inner ring 26b, and the electronic components mounted on each of the circuit boards 30a and 30b can function stably for a long time.

[0049] Figure 5 Shows Figures 1 to 4 A modified example of the shown outer ring spacer 26. In the outer ring spacer 26 of this modified example, three concave portions 26a2 are provided at equal intervals in the circumferential direction on the inner circumference of the outer ring 26a. Considering the workability, each of the above concave portions 26a2 is formed to extend along the entire axial length of the outer ring 26a, and the sensor 29 is mounted at the axial center of each of them.

[0050] Moreover, the inner ring 26b is adhesively fixed to the outer ring 26a in a state where three convex portions 26b2 provided on the outer periphery of its flange portion are respectively inserted into the respective concave portions 26a2 of the outer ring 26a. The axial positioning of the inner ring 26b relative to the outer ring 26a is performed by core alignment of a jig (not shown) with the lubricant supply path 26c of the outer ring 26a and the nozzle 26d of the inner ring 26b.

[0051] In addition, after the outer ring 26a and the inner ring 26b are adhesively fixed, the cover 31 is adhesively fixed to the outer ring 26a in a state where three convex portions 31a provided on its outer periphery are respectively inserted into the respective concave portions 26a2 of the outer ring 26a. The axial positioning of the cover 31 is performed by bringing the side surface on the rear side in the axial direction of the cover 31 into contact with a plurality of protrusions 26b3 provided on the outer periphery on the front side in the axial direction of the inner ring 26b.

[0052] The structure other than the above of this modification example, including the arrangement of the circuit boards 30a and 30b and the fixed state to the inner ring 26b, is the same as that of Figures 1 to 4 Therefore, even when this modification example is used, the same effects as those when using the structure of Figures 1 to 4 are obtained.

[0053] It should be considered that the embodiments disclosed this time are illustrative in all aspects and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and is intended to include all changes within the meaning and scope equivalent to the claims.

[0054] For example, since the outer ring spacer constituting the bearing device may have a double structure composed of an outer ring and an inner ring, the outer ring and the inner ring may be independent as in the embodiment or may be integrally formed.

[0055] In addition, in the embodiment, the circuit board equipped with the wireless communication module is arranged in a posture where the mounting surface is orthogonal to the axial direction of the outer ring spacer, but it is not limited thereto, and it may be arranged as long as the direction with strong radio wave intensity is parallel to the axial direction of the bearing device.

[0056] Moreover, the bearing device of the present invention can be effectively applied not only to the spindle device for machine tools as in the embodiment but also to various machine tools and equipment having a rotating shaft.

[0057] Description of Reference Numerals

[0058] 1... Bearing device; 2... Spindle; 3... Outer cylinder; 4... Motor; 23... Housing; 24... First bearing; 25... Second bearing; 26... Outer ring spacer; 26a... Outer ring; 26b... Inner ring; 26e, 26f... Grooves (substrate fixing parts); 29... Sensor; 30... Circuit; 30a, 30b... Circuit boards; 30c... Electric wire; 31... Cover; 32... First outer ring; 33... First inner ring; 34... First rolling element; 36... Second outer ring; 37... Second inner ring; 38... Second rolling element.

Claims

1. A bearing device, A first bearing (24) and a second bearing (25) are arranged inside a cylindrical housing (23) at an interval in the axial direction. The first bearing (24) comprises: a first outer ring (32), a first inner ring (33) rotatably arranged radially inside the first outer ring (32), and a plurality of first rotating bodies (34) assembled between the first outer ring (32) and the first inner ring (33). The second bearing (25) comprises: a second outer ring (36), a second inner ring (37) rotatably arranged radially inside the second outer ring (36), and a plurality of second rotating bodies (38) assembled between the second outer ring (36) and the second inner ring (37). A cylindrical outer ring spacer (26) is arranged in a state of being sandwiched between the first outer ring (32) and the second outer ring (36) in the axial direction. The outer ring spacer (26) is composed of an outer ring (26a) that contacts the first outer ring (32) and the second outer ring (36) in the axial direction, and an inner ring (26b) that is arranged radially inward of the outer ring (26a). A sensor (29) and a circuit (30) for processing the output of the sensor (29) are provided in a space formed between the outer ring (26a) and the inner ring (26b). The bearing device is characterized in that The circuit (30) is divided into a plurality of partial circuits, each of which is individually mounted on a plurality of flat circuit substrates (30a, 30b) and connected to each other via wires (30c). The circuit substrates (30a, 30b) are respectively fixed to substrate fixing portions (26e, 26f), and the substrate fixing portions (26e, 26f) are provided on the outer ring spacer (26).

2. The bearing device according to claim 1, It is characterized in that The circuit (30) includes a wireless communication module.

3. The bearing device according to claim 2, It is characterized in that The circuit board (30b) on which the wireless communication module is mounted is arranged in a posture in which a mounting surface of the wireless communication module is perpendicular to an axial direction of the outer race spacer (26).

4. The bearing device according to any one of claims 1 to 3, It is characterized in that A preload is applied to the first bearing (24) and the second bearing (25). For the outer ring spacer (26), the preload acts only on the outer ring (26a). The sensor (29) is arranged in contact with the outer ring (26a).

5. The bearing device according to any one of claims 1 to 4, It is characterized in that The outer ring (26a) is formed of metal or ceramics.

6. The bearing device according to any one of claims 1 to 5, It is characterized in that The inner ring (26b) is formed of resin.

7. The bearing device according to claim 2 or 3, It is characterized in that A cover (31) is formed of a non-magnetic body and blocks one axial side of a space formed between the outer ring (26a) and the inner ring (26b).

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