WO2020075638A1

WO2020075638A1 - Bearing device and preload sensor

Info

Publication number: WO2020075638A1
Application number: PCT/JP2019/039255
Authority: WO
Inventors: 小池　孝誌; 靖之福島; 勇介澁谷
Original assignee: Ntn株式会社
Priority date: 2018-10-09
Filing date: 2019-10-04
Publication date: 2020-04-16
Also published as: JP2020060411A; CN112823271B; KR20210068533A; CN112823271A; DE112019005064T5; JP7165021B2

Abstract

A preload sensor (10) is provided with a pressure-sensitive pattern part (22c) in which the direct-current resistance thereof varies in accordance with pressure applied in a first direction, coating parts (21, 23) for covering the pressure-sensitive pattern part (22c), and a buffer part (30) disposed adjacent to the coating parts (21, 23) in the first direction. The Young's modulus of the material constituting the buffer part (30) is less than the Young's modulus of the material constituting the coating parts (21, 23).

Description

Bearing device and preload sensor

The present invention relates to a bearing device and a preload sensor.

In the spindle device of machine tools, in order to improve machining accuracy and efficiency, preload management of bearings is required. Therefore, there is a demand to detect preload applied to bearings (hereinafter, preload of bearings). There is also a demand for detecting a change in preload as a symptom before a bearing abnormality occurs to prevent the bearing abnormality.

Japanese Unexamined Patent Publication No. 2014-071085 discloses a thin film sensor that includes a metal thin film and detects pressure based on a change in electric resistance when pressure is applied to the metal thin film.

JP, 2014-071085, A

The thin film sensor disclosed in Japanese Patent Laid-Open No. 2014-071085 has a thin thickness on the order of submicrons, and in particular, the thin metal film has a very thin thickness of about 200 nm. It is susceptible to surface properties such as surface roughness and flatness of each of the two surfaces.

When the thin film sensor is applied to a preload sensor of a bearing, a plurality of the thin film sensors are arranged in a circumferential direction between two surfaces of at least one of the bearing and the spacer (hereinafter, bearing) perpendicular to the axial direction. It needs to be spaced apart. On the other hand, the surface texture of a surface of a general bearing or the like perpendicular to the axial direction has a relatively large variation in the circumferential direction. Therefore, it is difficult to measure the preload of the bearing with high accuracy by the thin film sensor arranged between the two surfaces of a general bearing or the like.

A main object of the present invention is to provide a preload sensor capable of detecting a change in bearing preload more stably than a conventional preload sensor, and a bearing device including the preload sensor.

The preload sensor according to the present invention is a preload sensor that has a first surface facing one side in the first direction and a second surface facing the other side in the first direction, and detects the preload of the bearing. The preload sensor connects the first terminal portion and the second terminal portion to the first terminal portion and the second terminal portion, and detects the pressure acting between the first surface and the second surface. Accordingly, the pressure-sensitive pattern portion in which the direct current resistance between the first terminal portion and the second terminal portion changes, the covering portion covering the pressure-sensitive pattern portion, and the pressure-sensitive pattern portion are arranged adjacent to the covering portion in the first direction. And a buffer section. The longitudinal elastic modulus of the material forming the cushioning portion is less than the longitudinal elastic modulus of the material forming the covering portion.

The bearing device according to the present invention includes the preload sensor according to the present invention, a bearing, and a spacer arranged adjacent to the bearing. The preload sensor, the bearing, and the spacer are arranged so that the first direction is along the axial direction of the bearing and the spacer. At least one of the coating portion and the buffer portion of the preload sensor is in contact with the spacer. The longitudinal elastic modulus of the material forming the cushioning portion is less than the longitudinal elastic modulus of the material forming the spacer.

According to the present invention, it is possible to provide a preload sensor capable of stably detecting a change in preload of a bearing and a bearing device including the preload sensor, as compared with a conventional preload sensor.

FIG. 3 is a partial cross-sectional view perpendicular to the circumferential direction of the preload sensor and the bearing device according to Embodiment 1. FIG. 2 is a partially enlarged view of a preload sensor and a bearing device shown in FIG. 1. FIG. 2 is a partial plan view of the preload sensor and the bearing device shown in FIG. 1 viewed from the axial direction. FIG. 3 is a partial cross-sectional view showing an example of an assembling method of the preload sensor and the bearing device shown in FIG. 1. It is the top view seen from the axial direction of the preload sensor and bearing device shown in FIG. It is a figure which shows the detection circuit for detecting the change of preload by a preload sensor. FIG. 7 is a partial cross-sectional view showing a modified example of the preload sensor and the bearing device according to the first embodiment. FIG. 6 is a partial cross-sectional view showing a preload sensor and a bearing device according to a second embodiment. FIG. 9 is a partial cross-sectional view perpendicular to the radial direction of the preload sensor and the bearing device shown in FIG. 8. FIG. 7 is a partial cross-sectional view showing another modified example of the preload sensor and the bearing device according to the second embodiment. FIG. 9 is a partial cross-sectional view showing a preload sensor and a bearing device according to a third embodiment. FIG. 12 is a partially enlarged view of the preload sensor and the bearing device shown in FIG. 11. FIG. 12 is a partial cross-sectional view showing a modified example of the preload sensor and the bearing device shown in FIG. 11. FIG. 7 is a partial cross-sectional view showing a modified example of the preload sensor and the bearing device according to the first to third embodiments.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and the description thereof will not be repeated.

(Embodiment 1)
As shown in FIGS. 1 to 3, the bearing device 100 according to the first embodiment mainly includes a first bearing 1a, a second bearing 1b, an outer ring spacer 6 and an inner ring spacer 7, and a preload sensor 10. . The bearing device 100 is provided so as to rotatably support the main shaft 11 with respect to the housing 8. A fixed position preload is applied to the first bearing 1a and the second bearing 1b, for example.

As shown in FIG. 1, the first bearing 1a and the second bearing 1b have, for example, the same configuration. The first bearing 1a and the second bearing 1b are, for example, angular ball bearings. The first bearing 1a and the second bearing 1b are, for example, a back surface combination (DB).

As shown in FIG. 1, the first bearing 1a includes an outer ring 2a, an inner ring 3a, balls 4a, and a cage 5a. The outer ring 2a has an outer ring raceway surface. The inner ring 3a has an inner ring raceway surface which is arranged at a distance from the outer ring raceway surface in the radial direction of the outer ring 2a. The plurality of balls 4a are arranged between the outer ring raceway surface and the inner ring raceway surface. The cage 5a holds a plurality of balls 4a at a constant distance in the circumferential direction of the outer ring 2a. The second bearing 1b includes an outer ring 2b, an inner ring 3b, balls 4b, and a cage 5b. The outer ring 2b, the inner ring 3b, the balls 4b, and the cage 5b have the same configurations as the outer ring 2a, the inner ring 3a, the balls 4a, and the cage 5a. In the bearing device 100, the

outer rings

2a and 2b are fixed wheels, the

inner rings

3a and 3b are rotating wheels, the outer ring spacer 6 is a fixed side spacer, and the inner ring spacer 7 is a rotating side spacer.

As shown in FIG. 1, the outer ring spacer 6 and the inner ring spacer 7 are arranged adjacent to the first bearing 1a and the second bearing 1b. The outer ring spacer 6 and the inner ring spacer 7 are provided in an annular shape, and are arranged so that the respective axial directions are along the respective axial directions of the first bearing 1a and the second bearing 1b. The outer ring spacer 6 and the inner ring spacer 7 hold the relative positions of the first bearing 1a and the second bearing 1b constant in a used state in which the bearing device 100 supports the main shaft 11.

As shown in FIG. 1, the outer ring spacer 6 is sandwiched between the outer ring 2a of the first bearing 1a and the outer ring 2b of the second bearing 1b in the axial direction of the outer ring spacer 6. The outer ring spacer 6 has, for example, a first spacer member 61 and a second spacer member 62. The first spacer member 61 and the second spacer member 62 are annularly provided as separate bodies and arranged side by side in the axial direction. The first spacer member 61 and the second spacer member 62 have inner diameter surfaces facing the inner ring spacer 7 in the radial direction.

As shown in FIGS. 1 and 2, the first spacer member 61 faces the first bearing 1a side in the axial direction and is in contact with the outer ring 2a, and the first end surface 61a and the first end surface 61a. And a second end surface 61b located on the side opposite to. The second end surface 61b faces the axial end surface of the outer ring 2b. The second end surface 61b is the surface closest to the outer ring 2b among the surfaces of the first spacer member 61 facing the axial direction.

As shown in FIG. 1 and FIG. 2, the second spacer member 62 faces the second bearing 1b side in the axial direction, and the second spacer 61 and the second end surface 61b of the first spacer member 61 are arranged in the axial direction. It has the 3rd end surface 62a which opposes, and the 4th end surface 62b located in the opposite side to the 3rd end surface 62a, and contacting the outer ring 2b. The third end surface 62a faces the axial end surface of the outer ring 2a. The third end surface 62a is a surface closest to the outer ring 2a among the surfaces of the second spacer member 62 that face the axial direction.

The third end surface 62a is configured as a fifth surface in contact with the first surface 20a of the preload sensor 10 described later in the bearing device 100. The second end surface 61b is configured as a sixth surface in contact with the second surface 30a of the preload sensor 10 described later in the bearing device 100.

As shown in FIG. 1, the first spacer member 61 is located closer to the first bearing 1a side than the first end face 61a in the axial direction, and faces the first bearing 1a side, and is in the radial direction, for example. In, it further has a fifth end face 61c located inside the first end face 61a.

As shown in FIG. 2, the second spacer member 62 is located closer to the first bearing 1a side than the fourth end surface 62b in the axial direction, and faces the second bearing 1b side, and is in the radial direction, for example. In, it further has a sixth end face 62c located inside the fourth end face 62b.

As shown in FIGS. 1 and 2, the relative positions of the first spacer member 61 and the second spacer member 62 in the radial direction and the circumferential direction are positioned by the positioning member 63. As shown in FIG. 2, the first spacer member 61 is provided with a hole 61h opened to the second end surface 61b. The hole 61h extends, for example, along the axial direction and has a bottom surface. The second spacer member 62 is provided with a through hole 62h penetrating between the third end surface 62a and the sixth end surface 62c. The hole 61h and the through hole 62h are provided so as to be continuous with each other in the axial direction and into which the positioning member 63 is inserted. The positioning member 63 is provided such that when one end of the positioning member 63 is in contact with the bottom surface of the hole 61h, the other end of the positioning member 63 is arranged inside the through hole 62h. The positioning member 63 is provided, for example, in a rod shape.

The surface roughness of each of the second end surface 61b and the third end surface 62a forming the preload sensor 10 is preferably set to be better than the other surfaces.

As shown in FIG. 1, the inner ring spacer 7 is sandwiched between the inner ring 3a of the first bearing 1a and the inner ring 3b of the second bearing 1b in the axial direction. The inner ring spacer 7 has an end surface that is in contact with the inner ring 3a and an end surface that is located on the opposite side of the end surface and that is in contact with the inner ring 3b. The inner ring spacer 7 is arranged so as to face the first spacer member 61 and the second spacer member 62 in the radial direction.

The material forming the outer ring spacer 6 and the inner ring spacer 7 may be the same as the material forming the conventional outer ring spacer and inner ring spacer, and includes, for example, steel.

As shown in FIG. 1, the housing 8 has an inner diameter surface 8a that faces the outer diameter surfaces of the

outer rings

2a and 2b and the outer ring spacer 6, and projects inward in the radial direction with respect to the inner diameter surface 8a. It has a convex surface 8b. The convex surface 8b is in contact with the end surface located on the opposite side of the end surface of the outer ring 2a in contact with the outer ring spacer 6. The convex surface 8b is arranged so as to face the first end surface 61a of the outer ring spacer 6 in the axial direction. The inner diameter surface 8a and the convex surface 8b are arranged so that the bearing device 100 inserted into the inner diameter surface 8a from the side opposite to the convex surface 8b in the axial direction moves in the axial direction until the outer ring 2a contacts the convex surface 8b. It is provided. The

outer rings

2a and 2b and the outer ring spacer 6 are loosely fitted to the housing 8, for example.

The housing 8 has, for example, an inner cylinder 81 that houses the bearing device 100 therein, and an outer cylinder 82 that houses a part of the inner cylinder 81 and the main shaft 11 therein. A cooling medium flow path 83 is formed in the housing 8, for example. The cooling medium flow path 83 is configured as a groove that is concave with respect to the outer diameter surface of the inner cylinder 81, for example. The cooling medium passage 83 is provided so as to extend spirally with respect to the rotation center axis O, for example. A cooling medium flows in the cooling medium flow path 83. As a result, the bearing device 100 is cooled.

The front lid 9 is fixed to the housing 8 by a bolt or the like (not shown). As shown in FIG. 1, the front lid 9 is arranged inside the inner diameter surface 8a of the housing 8 in the radial direction and has a pressing surface 9a facing the convex surface 8b of the housing 8 in the axial direction. are doing. The pressing surface 9a is in contact with the end surface located on the opposite side of the end surface of the outer ring 2b in contact with the outer ring spacer 6. The pressing surface 9a is arranged so as to face the fourth end surface 62b of the outer ring spacer 6 in the axial direction. The housing 8 and the front lid 9 position the outer ring 2a, the outer ring 2b, and the outer ring spacer 6 in the axial direction.

As shown in FIG. 1, the main shaft 11 has an outer diameter surface 11a that faces the inner diameter surfaces of the

inner rings

3a and 3b and the inner ring spacer 7, and protrudes outward in the radial direction with respect to the outer diameter surface 11a. Has a convex surface 11b. The convex surface 11b is in contact with the end surface located on the opposite side of the end surface of the inner ring 3b that is in contact with the inner ring spacer 7. The

inner rings

3a and 3b and the inner ring spacer 7 are tightly fitted to the main shaft 11, for example.

As shown in FIG. 1, the fixing member 12 is fixed to the main shaft 11. The fixing member 12 is arranged outside the outer diameter surface 11a of the main shaft 11 in the radial direction and has a pressing surface 14a that faces the convex surface 11b of the main shaft 11 in the axial direction. The pressing surface 14a is in contact with the end surface located on the opposite side of the end surface of the inner ring 3a in contact with the inner ring spacer 7. The main shaft 11 and the fixing member 12 position the inner ring 3a, the inner ring 3b, and the inner ring spacer 7 in the axial direction.

As shown in FIG. 1, the fixing member 12 has, for example, a nut 13 and a spacer 14. The nut 13 is provided so as to be screwed onto the outer diameter surface 11 a of the main shaft 11. The nut 13 is connected to the inner ring 3 a via a spacer 14. The spacer 14 is provided so as to slide on the outer diameter surface 11 a of the main shaft 11. One end face of the spacer 14 in the axial direction is in contact with the nut 13, and the other end face thereof constitutes the pressing face 14a.

The bearing device 100 is assembled, for example, as follows. The second bearing 1b, the outer ring spacer 6 and the inner ring spacer 7, the first bearing 1a, and the spacer 14 are sequentially inserted into the main shaft 11 from the convex surface 12a side. When the outer ring 2a, the outer ring spacer 6, and the outer ring 2b are in contact with each other, a design gap is previously created between the inner ring 3a and the inner ring spacer 7, and between the inner ring 3b and the inner ring spacer 7. It is provided. Next, the nut 13 is tightened. As a result, the first bearing 1a, the second bearing 1b, the outer ring spacer 6, the inner ring spacer 7, the main shaft 11, and the fixing member 12 are connected, and the gap is eliminated.

Next, the first bearing 1a, the second bearing 1b, the outer ring spacer 6, the inner ring spacer 7, the main shaft 11, and the fixing member 12 connected as described above are inserted into the housing 8. The first bearing 1a, the outer ring spacer 6 and the inner ring spacer 7, and the second bearing 1b are sequentially inserted into the housing 8 from the convex surface 8b side. Next, the front lid 9 is fixed to the housing 8. In the bearing device 100 assembled in this way, a preload is applied to the first bearing 1a and the second bearing 1b. Specifically, the axial force applied to the inner ring 3a by tightening the nut 13 is transmitted to the outer ring 2a via the balls 4a, and further from the outer ring 2a to the outer ring 2b via the outer ring spacer 6. It is transmitted. The force transmitted to the outer ring 2b is transmitted to the inner ring 3b via the balls 4b. As a result, compressive stress is applied to each contact point between the outer ring 2a and the inner ring 3a of the first bearing 1a and the ball 4a, and each contact point between the outer ring 2b and the inner ring 3b of the second bearing 1b and the ball 4b. The first bearing 1a, the outer ring spacer 6 and the second bearing 1b constitute a part of a transmission path of the force for applying a preload to the first bearing 1a and the second bearing 1b.

As shown in FIGS. 1 and 2, the preload sensor 10 is disposed, for example, between the first spacer member 61 and the second spacer member 62 of the outer ring spacer 6 in the axial direction. The preload sensor 10 has a first surface 20a facing one side in the first direction and a second surface 30a facing the other side in the first direction. It is provided to detect changes in the applied load. The preload sensor 10 is arranged on the force transmission path for applying a preload to the first bearing 1a and the second bearing 1b such that the first direction is along the axial direction.

As shown in FIGS. 1 and 2, the first surface 20a of the preload sensor 10 is connected to the third end surface 62a of the second spacer member 62, for example. The first surface 20a is connected to a partial region of the third end surface 62a located outside the through hole 62h in the radial direction, for example.

As shown in FIGS. 1 and 2, the second surface 30a of the preload sensor 10 is connected to the second end surface 61b of the first spacer member 61, for example. The second surface 30a is connected to the entire surface of the second end surface 61b, for example.

As shown in FIGS. 1 and 2, the preload sensor 10 includes a pressure sensing unit 20 and a buffer unit 30. The pressure sensitive portion 20 has a first surface 20a and a third surface 20b located on the opposite side of the first surface 20a. The first surface 20a and the third surface 20b form both axial end surfaces of the pressure sensitive portion 20. The first surface 20a is a surface closest to the outer ring 2b among the surfaces of the pressure-sensitive portion 20 facing the axial direction. The third surface 20b is a surface closest to the outer ring 2a among the surfaces of the pressure sensitive portion 20 facing the axial direction.

The buffer section 30 has a second surface 30a and a fourth surface 30b located on the opposite side of the second surface 30a. The second surface 30a and the fourth surface 30b form both end surfaces of the buffer section 30 in the axial direction. The second surface 30a is the surface closest to the outer ring 2a among the surfaces of the buffer section 30 that face the axial direction. The fourth surface 30b is a surface closest to the outer ring 2b among the surfaces of the cushioning section 30 that face the axial direction. The entire third surface 20b of the pressure sensitive portion 20 is in contact with the fourth surface 30b of the buffer portion 30.

As shown in FIGS. 2 and 3, the pressure sensitive portion 20 includes a first terminal portion 22a and a second terminal portion 22b, a pressure sensitive pattern portion 22c, and covering

portions

21 and 23. In FIG. 1, the first terminal portion 22a, the second terminal portion 22b, the pressure-sensitive pattern portion 22c, and the covering

portions

21 and 23 are not shown.

The first terminal portion 22a and the second terminal portion 22b are electrically connected to external wiring via, for example, solder. That is, the first terminal portion 22a and the second terminal portion 22b are exposed from the covering

portions

21 and 23 and the buffer portion 30.

The pressure sensitive pattern portion 22c connects between the first terminal portion 22a and the second terminal portion 22b. The pressure-sensitive pattern portion 22c is covered with the covering

portions

21 and 23, and is arranged so as to overlap the buffer portion 30 in the axial direction. The direct current resistance between the first terminal portion 22a and the second terminal portion 22b of the pressure sensitive pattern portion 22c changes according to the pressure acting between the first surface 20a and the second surface 30a. The first terminal portion 22a, the second terminal portion 22b, and the pressure sensitive pattern portion 22c are formed by, for example, patterning a pressure sensitive film formed on the insulating film 21 described later.

As shown in FIG. 2, the covering

portions

21 and 23 are provided so as to cover the pressure sensitive pattern portion 22c. The

coating portions

21 and 23 have, for example, an insulating film 21 and a protective film 23. The insulating film 21 has the first surface 20a and a surface 21b located on the opposite side of the first surface 20a. The first terminal portion 22a, the second terminal portion 22b, the pressure sensitive pattern portion 22c, and the protective film 23 are arranged on the surface 21b. The protective film 23 is provided so as to cover the pressure sensitive pattern portion 22c of the first terminal portion 22a, the second terminal portion 22b, and the pressure sensitive pattern portion 22c arranged on the surface 21b of the insulating film 21. . The protective film 23 has a surface 23a connected to the surface 21b directly or via the pressure-sensitive pattern portion 22c, and a third surface 20b located on the opposite side of the surface 23a.

The material forming the

coating portions

21 and 23 may be any material having electrical insulation, but is preferably a material that is not easily corroded by lubricating oil, such as silicon dioxide (SiO ₂ ), aluminum oxide (Al). ₂ O ₃ ) and / or diamond-like carbon (DLC). The material forming the pressure-sensitive pattern portion 22c may be the same as an alloy material forming a general strain gauge, for example, a copper nickel alloy (Cu-Ni alloy) and a nickel chromium alloy (Ni-Cr alloy). At least one is included.

As shown in FIGS. 1 and 2, the buffer section 30 is provided so as to overlap the pressure-sensitive pattern section 22c in the axial direction. The radial width of the buffer portion 30 exceeds, for example, the radial width of the pressure sensitive portion 20. The buffer portion 30 has, for example, a second surface 30a connected to the second end surface 61b and a surface 30b connected to the third surface 20b of the pressure sensitive portion 20.

As shown in FIGS. 1 and 2, the second surface 30a of the buffer portion 30 is connected to, for example, the entire second end surface 61b. An escape portion (not shown) is provided on the second surface 30a side so as not to press the wires connected to the first terminal portion 22a and the second terminal portion 22b. The buffer portion 30 has a through hole 30h continuous with the hole 61h and the through hole 62h. The third surface 20b of the pressure-sensitive portion 20 is connected to a partial region of the surface 30b located outside the through hole 30h in the radial direction, for example. The axial thickness of the buffer portion 30 exceeds the thickness of each of the insulating film 21 and the protective film 23, for example. The axial thickness of the buffer portion 30 is, for example, 100 μm or less.

The surface 30b of the buffer portion 30 may or may not be bonded to the pressure-sensitive portion 20 as long as it is in contact with the third surface 20b.

As shown in FIG. 5, the preload sensor 10 includes, for example, a plurality of pressure sensitive parts 20. The plurality of pressure-sensitive portions 20 are arranged, for example, at intervals in the circumferential direction. Each of the plurality of pressure sensitive portions 20 is connected to, for example, one buffer portion 30 provided in a ring shape. It should be noted that the preload sensor 10 may include a plurality of buffer portions 30 arranged at intervals in the circumferential direction. In this case, each buffer section 30 is connected to, for example, one pressure sensitive section 20.

The bearing device 100 further includes a sensor signal processing unit 40 shown in FIG. As shown in FIG. 6, the sensor signal processing unit 40 includes resistors R1 to R3 connected to the DC power supply VSDC, the preload sensor 10, and a differential amplifier AMP. The resistors R1 to R3 and the preload sensor 10 form a bridge circuit. A resistor R1 and a resistor R2 are connected in series between the positive electrode and the negative electrode of the DC power source VSDC. Further, the preload sensor 10 and the resistor R3 are connected in series between the positive electrode and the negative electrode of the DC power source VSDC. One input node of the amplifier AMP is connected to the connection node between the resistors R1 and R2. The other input node of the amplifier AMP is connected to the connection node between the preload sensor 10 and the resistor R3. Such a sensor signal processing unit 40 includes the bridge circuit shown in FIG. 6, so that the DC resistance of the preload sensor 10 caused by a change in the preload applied to the first bearing 1a and the second bearing 1b. Can be detected.

The preload sensor 10 is connected to the detection circuit of the sensor signal processing unit 40 via the cable 16 shown in FIG. The housing 8 is provided with an insertion passage 15 through which the cable 16 is passed. One end of the insertion passage 15 is open to the inner diameter surface of the inner cylinder 81 of the housing 8.

The rigidity (longitudinal elastic modulus) of the material forming the cushioning portion 30 is lower than that of the material forming the outer ring spacer 6. The rigidity (longitudinal elastic modulus) of the material forming the cushioning portion 30 is lower than that of the material forming the covering

portions

21 and 23.

The material forming the buffer section 30 may be a metal such as aluminum (Al) or copper (Cu), or an alloy. The buffer section 30 may be formed by, for example, a sputtering method on the second surface 30a and then partially removing the film formed on a region where the buffer section 30 is not required to be formed.

The material forming the buffer portion 30 may include a fluororesin, and may be, for example, a coating material using polyamide-imide as a binder and polytetrafluoroethylene (PTFE) as a solid lubricant. In this case, the buffer section 30 may be formed by masking an area where the buffer section 30 is not required to be formed and then applying, spraying, or spraying the coating material. Alternatively, the cushioning portion 30 may be formed by adhering a preformed sheet material made of PTFE to a region where the cushioning portion 30 is to be formed.

The preload sensor 10 can be formed by any method as long as it has the above configuration. As an example, the preload sensor 10 may be formed by assembling the pressure sensitive portion 20 and the cushioning portion 30, which are formed separately from each other, into the outer ring spacer 6. In this case, in the preload sensor 10, each of the pressure sensing portion 20 and the buffer portion 30 formed separately from the first spacer member 61 and the second spacer member 62 has the first spacer member 61 or the second spacer member. It may be formed by assembling the first spacer member 61 and the second spacer member 62 after being assembled to the seat member 62. Alternatively, in the preload sensor 10, each of the pressure-sensitive portion 20 and the buffer portion 30, which are integrally formed with the first spacer member 61 or the second spacer member 62, has the first spacer member 61 and the second spacer member. It may be formed by assembling 62.

For example, first, the insulating film 21 is formed on the third end surface 62a of the second spacer member 62 by a sputtering method or the like. Next, the first terminal portion 22a, the second terminal portion 22b and the pressure sensitive pattern portion 22c are formed on the surface 21b of the insulating film 21 by a sputtering method or the like. Next, the protective film 23 is formed on the surface 21b of the insulating film 21 so as to cover the pressure sensitive pattern portion 22c by a sputtering method or the like. The protective film 23 formed on the first terminal portion 22a and the second terminal portion 22b is selectively removed, or the protective film 23 is formed on the first terminal portion 22a and the second terminal portion 22b. To prevent this, the first terminal portion 22a and the second terminal portion 22b may be masked before forming the protective film 23. In this way, as shown in FIG. 4, the pressure sensitive portion 20 formed integrally with the second spacer member 62 is prepared.

Further, the buffer portion 30 is formed on the second end surface 61b of the first spacer member 61 by sputtering or the like. Thereby, as shown in FIG. 4, the buffer portion 30 formed integrally with the first spacer member 61 is prepared.

Next, the first spacer member 61 and the second spacer member 62 are relatively positioned by the positioning member 63. Specifically, the positioning member 63 is inserted into the holes 61h and the through holes 62h of the first spacer member 61 and the second spacer member 62 arranged as shown in FIG. The member 61 and the second spacer member 62 are relatively positioned in the circumferential direction and the radial direction. As a result, the preload sensor 10 in which the pressure sensitive portion 20 and the buffer portion 30 are laminated in the axial direction is formed.

As another example, the preload sensor 10 may be integrally formed in advance as a laminated body of the pressure sensitive portion 20 and the buffer portion 30 before being assembled to the outer ring spacer 6. In this case, the preload sensor 10 may be formed as the above-mentioned laminated body formed separately from the first spacer member 61 and the second spacer member 62. Alternatively, the preload sensor 10 may be formed as the above laminated body integrally formed with the first spacer member 61 or the second spacer member 62.

<Effect>
The preload sensor 10 includes a pressure-sensitive pattern portion 22c whose DC resistance changes according to a pressure acting in the first direction,

coating portions

21 and 23 that cover the pressure-sensitive pattern portion 22c, and

coating portions

21 and 23 in the first direction. And a cushioning section 30 disposed adjacent to. The longitudinal elastic modulus of the material forming the cushioning portion 30 is less than the longitudinal elastic modulus of the material forming the covering

portions

21 and 23.

As described above, the detection accuracy of the conventional preload sensor that does not include the buffer section 30 is easily affected by the surface texture such as surface roughness and flatness of each of the two surfaces sandwiching the preload sensor. Specifically, when the surface roughness of at least one of the two surfaces is relatively large, or the flatness of at least one of the two surfaces is relatively low, the pressure-sensitive pattern portion of the preload sensor is Since the two surfaces are not uniformly pressed, it is difficult to measure the change in the force applied by the pressing with high accuracy. In particular, since the surface properties of a surface of a general bearing or the like which is perpendicular to the axial direction have a relatively large variation within the surface, the preload placed between the above two surfaces of the general bearing or the like. It is difficult for a sensor to detect a change in bearing preload with high accuracy.

On the other hand, a force in the first direction is applied to the pressure sensitive pattern portion 22c of the preload sensor 10 via the buffer portion 30. Therefore, the preload sensor 10 changes the force in the first direction regardless of the surface roughness and the flatness of the surface of the buffer section 30 in contact with the second surface 30a, as compared with the conventional preload sensor that does not include the buffer section 30. Can be detected stably. That is, the preload sensor 10 can stably and highly accurately detect a change in the preload applied to the bearing even when the preload sensor 10 is arranged adjacent to a general bearing and a spacer.

Further, the preload sensor 10 can be formed integrally with the outer ring spacer 6 by forming and processing the pressure sensitive portion 20 and the buffer portion 30 on the outer ring spacer 6. In this case, in the bearing device 100 before being attached to the housing 8, the preload sensor 10 is positioned with respect to the outer ring spacer 6. Therefore, such a bearing device 100 is not positioned on the outer ring spacer 6 before being mounted on the housing 8, but is equipped with the preload sensor 10 which is mounted on the housing 8 and positioned on the outer ring spacer 6. It is easier to assemble than the device. For example, the bearing device disclosed in Japanese Unexamined Patent Application Publication No. 2008-286219 has a complicated structure in which a magnetostrictive material and a coil as a preload detection device are sandwiched between axially divided outer ring spacers. In this case, it is necessary to attach the bearing device, which is held so that the pair of spacer members are not separated, to the housing. Such an assembly is difficult. The bearing device 100 is more easily assembled than the bearing device including the preload detection device.

In the above bearing device 100, the

coating portions

21 and 23 further have a third surface 20b located on the opposite side of the first surface 20a. The buffer portion 30 further has a fourth surface 30b located on the opposite side of the second surface 30a. The entire surface of the third surface 20b is in contact with the fourth surface 30b.

In such a preload sensor 10, the buffer portion 30 is reliably arranged on the transmission path of the force applied to the pressure sensitive pattern portion 22c in the first direction.

Further, since the covering

portions

21 and 23 cover the pressure-sensitive pattern portion 22c, the areas of the first surface 20a and the third surface 20b viewed from the first direction exceed the area of the pressure-sensitive pattern portion 22c. Therefore, in the preload sensor 10, the pressure sensing portion 20 and the pressure sensing portion 20 are buffered as compared with the preload sensor 10 in which the planar shape and dimensions of the buffering portion 30 viewed from the first direction are equal to those of the pressure sensing pattern portion 22c. The part 30 is easily positioned.

In the preload sensor 10, the material forming the buffer section 30 includes resin. With this configuration, the buffer portion 30 is relatively easily formed by coating, spraying, spraying, or the like. Further, by using resin as the buffer portion 30, the longitudinal elastic modulus is smaller than that of metal, so that the pressure-sensitive pattern portion 22c can be pressed reliably even if the surface shape (flatness) of the preload sensor 10 is poor.

In the above preload sensor 10, the thickness of the buffer portion 30 in the first direction is 100 μm or less. In the bearing device 100 including the preload sensor 10, the longitudinal elastic modulus of the material forming the cushioning portion 30 is less than the longitudinal elastic modulus of the material forming the first spacer member 61 and the second spacer member 62. When the above-mentioned thickness of the cushioning portion 30 becomes relatively thick, the rigidity of the outer ring spacer 6 decreases. On the other hand, when the thickness of the cushioning portion 30 is 100 μm or less, the rigidity of the outer ring spacer 6 due to the provision of the cushioning portion 30 in the preload sensor 10 causes a decrease in rigidity when the bearing device 100 is used in a machine tool. It is suppressed to the extent that it does not affect the machining accuracy of the machine tool.

The bearing device 100 includes the preload sensor 10, the first bearing 1a and the second bearing 1b, and the outer ring spacer 6 arranged adjacent to the first bearing 1a and the second bearing 1b. The preload sensor 10, the first bearing 1a and the second bearing 1b, and the outer ring spacer 6 are arranged so that the first direction is along the axial direction. The first surface 20a and the second surface 30a of the preload sensor 10 are in contact with the outer ring spacer 6. The longitudinal elastic modulus of the material forming the buffer portion 30 is less than the longitudinal elastic coefficient of the material forming the outer ring spacer 6.

With this configuration, when the force in the axial direction acts on the preload sensor 10, the first bearing 1a, the second bearing 1b, and the outer ring spacer 6, a buffer having relatively low rigidity among these members is used. The portion 30 can reduce the variation in the force due to the variation in the surface properties of the second end surface 61b and the third end surface 62a, which are the surfaces that transmit the force. Therefore, according to the bearing device 100, even if the variation of the surface properties of the second end face 61b and the third end face 62a is equivalent to that in a general bearing device, the preload sensor 10 can detect the change of the preload with high accuracy. can do. The bearing device 100 is suitable for a bearing device that supports a rotating shaft that rotates at high speed, such as a main shaft of a machine tool.

The bearing device 100 includes a plurality of preload sensors 10 arranged at intervals in the circumferential direction. According to such a bearing device 100, the state in which the eccentric load is applied to the first bearing 1a and the second bearing 1b can also be detected by comparing the outputs of the preload sensors 10.

Note that the preload sensor 10 may be arranged at any position on the transmission path. The preload sensor 10 may be arranged, for example, between the inner ring 3 a and the spacer 14. In this case, the outer ring spacer 6 may be integrally formed.

The outer ring spacer 6 shown in FIGS. 1 to 3 has a portion projecting inward in the radial direction with respect to the

outer rings

2a and 2b, but is not limited to this. The inner diameter surfaces of the first spacer member 61 and the second spacer member 62 of the outer ring spacer 6 may be provided, for example, so as to be continuous with the inner diameter surfaces of the

outer rings

2a and 2b in the axial direction. In this case, the entire surface of the third surface 20b of the pressure sensitive portion 20 is provided so as to contact the entire surface of the fourth surface 30b of the buffer portion 30, for example.

Further, as shown in FIG. 7, the first surface 20a of the preload sensor 10 is in contact with the second end surface 61b of the first spacer member 61, and the second surface 30a is the third end surface 62a of the second spacer member 62. You may touch. That is, the second end surface 61b of the first spacer member 61 may be configured as the fifth surface, and the third end surface 62a of the second spacer member 62 may be configured as the sixth surface.

(Embodiment 2)
As shown in FIGS. 8 and 9, the bearing device 101 according to the second embodiment has basically the same configuration as the bearing device 100 according to the first embodiment, but the second space of the outer ring spacer 6 is different. The difference is that the seat member 62 has a protruding portion 62p protruding in the axial direction, and the top surface of the protruding portion 62p constitutes the third end surface 62a. In other words, the bearing device 101 according to the second embodiment is different from the bearing device 100 in that the top surface of the protrusion 62p is configured as the fifth surface in contact with the first surface 20a of the preload sensor 10. 8 and 9, the first terminal portion 22a, the second terminal portion 22b, the pressure-sensitive pattern portion 22c, and the covering

portions

21 and 23 are not shown. Further, in FIG. 8, the positioning member 63 is not shown.

The protruding portion 62p is provided so as to be continuous with the outer diameter surface of the second spacer member 62, for example. The protruding portion 62p is provided so as to overlap at least a part of the

outer rings

2a and 2b in the axial direction, and is provided so as to overlap the entire

outer rings

2a and 2b in the axial direction, for example. The top surface of the protrusion 62p is the surface of the first spacer member 61 that faces the axial direction and that is closest to the outer ring 2a. The top surface of the protrusion 62p constitutes the third end surface 62a.

The preload sensor 10 according to the second embodiment has basically the same configuration as the preload sensor 10 according to the first embodiment. The radial width of the buffer portion 30 is, for example, equal to the radial width of the pressure sensitive portion 20. The second surface 30a of the preload sensor 10 is in contact with only a partial region of the second end surface 61b located outside in the radial direction. The first surface 20a of the preload sensor 10 is in contact with the entire surface of the third end surface 62a, for example. The area of the first surface 20a of the preload sensor 10 is smaller than the area of the first surface 20a of the preload sensor 10 according to the first embodiment, for example.

Since the preload sensor 10 and the bearing device 101 according to the second embodiment have basically the same configurations as the preload sensor 10 and the bearing device 100 according to the first embodiment, the preload sensor 10 and the bearing according to the first embodiment are provided. The same effect as the device 100 can be obtained.

In the bearing device 101 according to the second embodiment, the area of the region subjected to the finishing process is smaller than that in the case where the finishing process is performed on the entire third end face 62a shown in FIG. Finishing can be performed relatively easily.

As shown in FIG. 10, in the bearing device 101 according to the second embodiment, in addition to the second spacer member 62, the first spacer member 61 also has the protrusion 61p protruding in the axial direction. Good. The top surface of the protrusion 61p is provided so as to contact the top surface of the protrusion 62p. The top surface of the protrusion 61p constitutes the second end surface 61b, and is in contact with, for example, the second surface 30a of the preload sensor 10. The top surface of the protrusion 61p may be in contact with the first surface 20a of the preload sensor 10, and the top surface of the protrusion 62p may be in contact with the second surface 30a of the preload sensor.

The area of the second surface 30a of the preload sensor 10 shown in FIG. 10 is smaller than the area of the second surface 30a of the preload sensor 10 shown in FIGS. 8 and 9. Since the area of the second end face 61b is also small, the area where high processing accuracy is required is small, and thus the processing is easy.

In the bearing device 101 according to the second embodiment, the second spacer member 62 does not have the protrusion 62p, and only the first spacer member 61 may have the protrusion 61p.

(Embodiment 3)
As shown in FIGS. 11 and 12, the bearing device 102 according to the third embodiment has basically the same configuration as the bearing device 100 according to the first embodiment, but the second surface 30a of the preload sensor 10 is different. Are arranged so as to contact the outer ring 2b of the second bearing 1b. In other words, the bearing device 102 according to the third embodiment is different from the bearing device 100 in that the axial end surface 2c of the outer ring 2b is configured as a sixth surface in contact with the second surface 30a of the preload sensor 10. . Note that, in FIG. 11, the first terminal portion 22a, the second terminal portion 22b, the pressure-sensitive pattern portion 22c, and the covering

portions

21 and 23 are not shown.

The outer ring spacer 6 is, for example, integrally configured. The outer ring spacer 6 faces the first bearing 1a side in the axial direction and is located on the side opposite to the seventh end surface 6a in contact with the outer ring 2a and the seventh end surface 6a, and the second bearing 1b side. And an eighth end face 6b arranged so as to face the end face 2c of the outer ring 2b in the axial direction. The area of the eighth end surface 6b is, for example, equal to the area of the end surface 2c of the outer ring 2b.

The first surface 20a of the preload sensor 10 is in contact with the eighth end surface 6b of the outer ring spacer 6. The second surface 30a is in contact with the end surface 2c of the outer ring 2b. That is, the eighth end surface 6b of the outer ring spacer 6 is configured as a fifth surface, and the end surface 2c of the outer ring 2b is configured as a sixth surface.

Since the preload sensor 10 and the bearing device 102 according to the third embodiment have basically the same configurations as the preload sensor 10 and the bearing device 100 according to the first embodiment, the preload sensor 10 and the bearing according to the first embodiment are provided. The same effect as the device 100 can be obtained.

As shown in FIG. 13, the first surface 20a of the preload sensor 10 may be in contact with the end surface 2c of the outer ring 2b, and the second surface 30a may be in contact with the eighth end surface 6b of the outer ring spacer 6. That is, the end surface 2c of the outer ring 2b may be configured as the fifth surface, and the eighth end surface 6b of the outer ring spacer 6 may be configured as the sixth surface.

In the

above bearing devices

100, 101, 102, at least one of the first surface 20a and the second surface 30a of the preload sensor 10 is in contact with the outer ring spacer 6, but the invention is not limited to this. As shown in FIG. 14, at least one of the first surface 20a and the second surface 30a of the preload sensor 10 may be in contact with the inner ring spacer 7. In this case, the longitudinal elastic modulus of the material forming the buffer portion 30 may be less than the longitudinal elastic coefficient of the material forming the inner ring spacer 7.

In the bearing device 103 shown in FIG. 14, the first bearing 1a and the second bearing 1b are a front face combination (DF). In this case, by tightening the front lid 9 to the housing 8 with a bolt or the like (not shown), a preload is applied from the second bearing 1b side toward the first bearing 1a side. The axial force applied to the outer ring 2b by tightening the front lid 9 is transmitted to the inner ring 3b via the balls 4b, and further from the inner ring 3b to the inner ring 3a via the inner ring spacer 7. The force transmitted to the inner ring 3a is transmitted to the outer ring 2a via the balls 4a. As a result, compressive stress is applied to each contact point between the outer ring 2a and the inner ring 3a of the first bearing 1a and the ball 4a, and each contact point between the outer ring 2b and the inner ring 3b of the second bearing 1b and the ball 4b. The second bearing 1b, the inner ring spacer 7, and the first bearing 1a form a part of a transmission path of the force for applying a preload to the first bearing 1a and the second bearing 1b.

The preload sensor 10 is arranged, for example, between the inner ring 3b and the inner ring spacer 7 in the transmission path. The position of the preload sensor 10 may be another position on the transmission path.

As shown in FIG. 14, when the preload sensor 10 is arranged between the inner ring 3b as the rotating wheel and the inner ring spacer 7 as the rotating side spacer, the preload sensor 10 also has the main shaft 11, the inner ring 3b, and the inner ring 3b. It rotates together with the inner ring spacer 7. Therefore, in the bearing device 103 shown in FIG. 14, the transmitter 51 for transmitting the output of the preload sensor 10 to the external device is arranged on the outer diameter surface of the inner ring spacer 7. Further, a receiver 52 is arranged at a position facing the transmitter 51 on the inner diameter surface of the outer ring spacer 6. The transmitter 51 and the receiver 52 are provided so as to communicate and supply power to each other in a non-contact manner.

The embodiments disclosed this time are to be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1a 1st bearing, 1b 2nd bearing, 2a, 2b outer ring, 2c end surface, 3a, 3b inner ring, 4a, 4b ball, 5a, 5b retainer, 6 outer ring spacer, 6a 7th end surface, 6b 8th end surface, 61p , 62p protrusion, 7 inner ring spacer, 8 housing, 8a inner diameter surface, 8b, 11b convex surface, 9 front lid, 9a, 12a holding surface, 10 preload sensor, 11 spindle, 11a outer diameter surface, 12 fixing member, 13 nut , 14 spacers, 15 insertion passages, 16 cables, 20 pressure sensitive parts, 20a first surface, 20b third surface, 21 insulating film (covering part), 23 protective film (covering part), 22a first terminal part, 22b first 2 terminal parts, 22c pressure sensitive pattern part, 30 shock absorbing part, 30a second surface, 30b fourth surface, 40 sensor signal processing part, 61 first spacer member, 61a first End face, 61b second end face, 61c fifth end face, 62 second spacer member, 62a third end face, 62b fourth end face, 62c sixth end face, 63 positioning member, 81 inner cylinder, 82 outer cylinder, 83 cooling medium flow Road, 100 bearing device.

Claims

A pressure sensitive pattern portion in which a direct current resistance changes according to a pressure acting in a first direction,
A covering portion that covers the pressure-sensitive pattern portion,
A buffer portion arranged adjacent to the covering portion in the first direction,
The preload sensor, wherein the longitudinal elastic modulus of the material forming the buffer portion is less than the longitudinal elastic coefficient of the material forming the covering portion.
The covering portion has a first surface facing one side of the first direction,
The buffer portion has a second surface facing the other side of the first direction,
The covering portion further has a third surface located on the side opposite to the first surface,
The buffer portion further has a fourth surface located on the side opposite to the second surface,
The preload sensor according to claim 1, wherein the third surface is in contact with the fourth surface.
The preload sensor according to claim 1 or 2, wherein the material forming the buffer portion includes a resin.
The preload sensor according to any one of claims 1 to 3, wherein the thickness of the buffer portion in the first direction is 100 µm or less.
A preload sensor according to any one of claims 1 to 4,
Bearings,
A spacer arranged adjacent to the bearing,
The preload sensor, the bearing, and the spacer are arranged such that the first direction is along the axial direction of the bearing and the spacer,
At least one of the covering portion and the buffer portion of the preload sensor is in contact with the spacer,
The bearing device in which the longitudinal elastic modulus of the material forming the buffer portion is less than the longitudinal elastic coefficient of the material forming the spacer.
The bearing device according to claim 5, wherein the preload sensor is arranged between the bearing and the spacer in the axial direction.
The spacer is a second spacer member that is configured separately from the first spacer member and the first spacer member, and is arranged side by side with the first spacer member in the axial direction. Including and
The bearing device according to claim 5, wherein the preload sensor is arranged between the first spacer member and the second spacer member in the axial direction.
The spacer includes at least one protrusion protruding in the axial direction,
The bearing device according to claim 6 or 7, wherein the preload sensor is arranged adjacent to the protrusion in the axial direction.
The bearing device according to any one of claims 5 to 8, wherein the buffer portion is configured as an annular member coaxial with the bearing and the spacer.