JP5030744B2 - Bearing device - Google Patents

Description

  The present invention relates to a bearing device used for a spindle of a machine tool.

In a spindle device of a machine tool, there is a need to detect a sign of the bearing before the abnormality occurs in the bearing to prevent the bearing abnormality from occurring. In order to detect the abnormality of the bearing, as shown in FIG. 9, a part of the bearing spacer 1 is constituted by a magnetostrictive material 2 or the like to detect a change in magnetic characteristics (see Patent Documents 1 to 3). . The preload of the rolling bearing 3 is detected from the detected value, and for example, a bearing abnormality such as a rapid temperature rise of the inner and outer rings is detected.
JP 2001-254742 A JP 2004-84739 A Japanese Patent Application No. 2007-127763

In a stationary state in which the main shaft 4 of the conventional spindle device is not rotating, the fit between the bearing outer ring 3g and the housing 5 is a clearance fit, so there is a slight gap between the inner peripheral surface 5a of the housing 5 and the outer ring outer diameter surface 3ga. Exists. Therefore, all the preload applied to the bearing 3 is applied to the outer ring spacer 1.
However, when the main shaft 4 is rotated, the bearing 3 expands due to heat generated by the bearing 3. Since the housing 5 of the spindle device is generally cooled by an outer cylinder, the temperature is lower than that of the bearing 3. Therefore, there is no radial gap between the inner peripheral surface 5a of the housing 5 and the outer ring outer diameter surface 3ga, and the fit between the bearing 3 and the housing 5 is tight, that is, an interference fit. Therefore, even if the preload load of the bearing 3 changes due to the static friction between the bearing 3 and the housing 5, there is a problem that the force is not applied to the spacer and the preload detection error becomes large.

  An object of the present invention is to provide a bearing device capable of reducing a preload detection error and accurately detecting a bearing abnormality.

Bearing device of the first invention in this inventions, in the bearing device is interposed configured to receive a preload between seat between raceway of a plurality of rolling bearings arranged in the axial direction, the spacer is axially The outer ring spacer interposed between the inner rings and the inner ring spacer interposed between the inner rings, and a detecting means for detecting a preload applied to the bearing is provided in the outer ring spacer, and the rolling bearing and a housing for fitting the outer ring spacer is provided, only set the rigidity reduction portion to reduce the rigidity of the part amount facing the bearing of the housing, wherein the housing is provided and the housing body, the inner peripheral surface of the housing body The ring member is disposed so as to face the bearing and is formed in a cross-section I shape as the rigidity-decreasing portion, and the ring member is provided at both ends in the axial direction of the inner peripheral portion of the ring member. Element To the outer peripheral portion, it is provided with a axial clearance for displacing the inner peripheral portion axially relative.

  According to this configuration, when the bearing temperature rises and the inner ring expands due to the operation of the rolling bearing, and the preload becomes larger than the initial set value, the axial force applied between both ends of the outer ring spacer increases. Even when the clearance between the bearing and the housing is eliminated and the fit is an interference fit, the rigidity reduction portion is provided in the housing, so the preload applied to the bearing does not escape undesirably to the housing, and the outer ring spacer It takes. That is, it is possible to prevent a change in the preload of the bearing due to the static friction between the bearing and the housing as in the prior art. Therefore, the detection error by the detection means can be reduced and the bearing abnormality can be accurately detected.

The housing includes a plurality of housing constituent members. The housing constituent members include a housing main body and a ring member provided on an inner peripheral surface of the housing main body, and the ring member is disposed so as to face the bearing. In addition, the rigidity reduced portion may be formed by forming an I-shaped cross section.
As described above, by using the ring member having the I-shaped cross section as the rigidity reduced portion, the detection error by the detecting means can be easily reduced. Further, the housing includes a plurality of housing constituent members, and these housing constituent members include a housing main body and a ring member provided on the inner peripheral surface of the housing main body, so that assembly of the ring member and the like to the housing main body is easy. Can be

A bearing device according to a second aspect of the present invention is a bearing device configured to receive a preload by interposing a spacer between race rings of a plurality of rolling bearings arranged in the axial direction. The outer ring spacer has an outer ring spacer interposed between the outer rings and the inner ring spacer interposed between the inner rings, and a detecting means for detecting a preload applied to the bearing is provided in the outer ring spacer, and the rolling bearing and the outer ring A housing that fits the spacer is provided, a rigidity-decreasing portion that reduces the rigidity of the portion facing the outer ring spacer in the housing is provided, and the rigidity-decreasing portion is provided with a groove on the inner peripheral surface of the housing, A through-hole through which the output portion of the detection means is drawn out of the housing is provided so as to penetrate the rigidity-decreasing portion in the radial direction, and the rigidity-decreasing portion depends on the diameter and number of the through-holes. Stiffness is obtained by adjustable configure.
In this case, from the case where the rigidity reduction portion at a portion facing the bearing also can be reduced the number of parts of the entire device. Therefore, the structure of the bearing device can be simplified and the manufacturing cost can be reduced.

A strain generating portion that generates strain due to an axial force acting between both ends of the spacer is provided in a part of the outer ring spacer in the axial direction, and the detection means detects the strain of the strain generating portion. May be.
In this case, the strain generating portion is distorted by an axial force acting between both ends of the outer ring spacer. By providing the detecting means in the strain generating portion, it is possible to detect the strain generated in the strain generating portion. A bearing preload can be obtained based on this detected value, and a bearing abnormality can be accurately detected.

A magnetostrictive material whose magnetic characteristics change due to an axial force acting between both ends of the spacer is provided in a part in the axial direction of the outer ring spacer, and the detecting means detects a change in the magnetic characteristics of the magnetostrictive material. It may be a thing.
In this case, the magnetic characteristics of the magnetostrictive material change due to the axial force acting between both ends of the outer ring spacer. The change in the magnetic characteristics is detected by the detecting means to obtain the bearing preload, and the bearing abnormality can be accurately detected.
You may provide the abnormality detection means which detects the abnormality of a bearing from the detected value detected by the said detection means.

Bearing device of the first invention in this inventions, in the bearing device is interposed configured to receive a preload between seat between raceway of a plurality of rolling bearings arranged in the axial direction, the spacer is axially The outer ring spacer interposed between the inner rings and the inner ring spacer interposed between the inner rings, and a detecting means for detecting a preload applied to the bearing is provided in the outer ring spacer, and the rolling bearing and a housing for fitting the outer ring spacer is provided, only set the rigidity reduction portion to reduce the rigidity of the part amount facing the bearing of the housing, wherein the housing is provided and the housing body, the inner peripheral surface of the housing body The ring member is disposed so as to face the bearing and is formed in a cross-section I shape as the rigidity-decreasing portion, and the ring member is provided at both ends in the axial direction of the inner peripheral portion of the ring member. Element To the outer peripheral portion, due to the provision of the axial clearance for displacing the inner peripheral portion axially relative, it is possible to reduce the detection error of the preload, to accurately detect abnormal bearing condition.
A bearing device according to a second aspect of the present invention is a bearing device configured to receive a preload by interposing a spacer between race rings of a plurality of rolling bearings arranged in the axial direction. The outer ring spacer has an outer ring spacer interposed between the outer rings and the inner ring spacer interposed between the inner rings, and a detecting means for detecting a preload applied to the bearing is provided in the outer ring spacer, and the rolling bearing and the outer ring A housing that fits the spacer is provided, a rigidity-decreasing portion that reduces the rigidity of the portion facing the outer ring spacer in the housing is provided, and the rigidity-decreasing portion is provided with a groove on the inner peripheral surface of the housing, A through-hole through which the output portion of the detection means is drawn out of the housing is provided so as to penetrate the rigidity-decreasing portion in the radial direction, and the rigidity-decreasing portion depends on the diameter and number of the through-holes. Since adjustably configure the rigidity, it is possible to reduce the detection error of the preload, to accurately detect abnormal bearing condition.

A first embodiment of the present invention will be described with reference to FIGS. In the first embodiment, in particular, a ring member having an I-shaped cross section is provided as a rigidity reducing member at a portion facing the bearing of the housing. Details will be described below.
As shown in FIG. 1, the bearing device according to the first embodiment is a housing 10 in which a shaft 11 is rotatably supported by a plurality of bearings 12. This bearing device is applied to, for example, a spindle device of a machine tool. In this case, the shaft 11 becomes the main shaft 11 of the spindle device. A motor 13 for rotating the spindle 11 is incorporated in the spindle device. In the present embodiment, the rotor 14 of the motor 13 is attached to the main shaft 11, and the stator 15 of the motor 13 is attached to the housing 10. The rotor 14 is made of a permanent magnet or the like, and the stator 15 is made of a coil, a core, or the like.

  As shown in FIG. 2, a plurality of axially spaced bearings 12 are fitted to the main shaft 11 in an interference fit state, an inner ring spacer 16 is provided between the inner rings 12i and 12i, and an outer ring is provided between the outer rings 12g and 12g. A seat 17 is interposed. The bearing 12 is a rolling bearing in which a plurality of rolling elements T are interposed between the inner ring 12i and the outer ring 12g, and these rolling elements T are held by a cage Rt. The bearing 12 is a bearing capable of applying an axial preload, and an angular ball bearing, a deep groove ball bearing, a tapered roller bearing, or the like is used. In the illustrated example, an angular ball bearing is used, and the two bearings 12 and 12 are installed in a back surface combination. A motor 13 is arranged in the vicinity of one of the bearings 12, 12 so as to be spaced apart in the axial direction.

  As shown in FIGS. 1 and 2, the outer ring spacer 17 includes a ring-shaped spacer main body 18 and a ring-shaped strain generating portion 19. The spacer body 18 includes a first divided spacer body 18a and a second divided spacer body 18b. The ring-shaped strain generating portion 19 is sandwiched between a first split spacer body 18a provided on one axial side and a second split spacer body 18b provided on the other axial side. As shown in FIG. 1, the width dimension of the first and second divided spacer main bodies 18a and 18b and the strain generating portion 19, that is, the width dimension H1 of the outer ring spacer 17 is equal to the width dimension H2 of the inner ring spacer 16. The nut 20 is brought into contact with the end face of the inner ring of one bearing 12 and the nut 20 is tightened, whereby a preload is applied to the bearing in accordance with the width dimension difference between the outer ring spacer 17 and the inner ring spacer 16. The

The housing 10 includes a plurality of housing components. These housing constituent members include a housing body 10a, first to fourth ring members 10b, 10c, 10d, and 10e, and a lid member 10f. As shown in FIG. 2, first to fourth ring members 10b, 10c, 10d, and 10e are sequentially provided adjacent to the inner peripheral surface 10aa of the housing body 10a in the axial direction. A lid member 10f that closes one end edge portion is provided.
As shown in FIG. 2 and FIG. 3, the first ring member 10b as a reduced-rigidity portion arranged on the right side is an annular member having an I-shaped cross section and is fitted to the inner peripheral surface 10aa of the housing body 10a. The outer peripheral portion 10ba to be joined, the inner peripheral portion 10bb facing the outer ring outer diameter surface of the one bearing 12, and the annular portion 10bc connecting the outer peripheral portion 10ba and the inner peripheral portion 10bb. The annular portion 10bc is formed in parallel to the radial plane. However, the annular portion 10bc is provided near the left end in the axial direction of the inner and outer peripheral portions 10bb and 10ba. The first ring member 10b is integrally formed from, for example, a steel material. However, it is not limited only to steel materials.

The outer peripheral surface 10b1 of the outer peripheral portion 10ba is fitted to the inner peripheral surface 10aa of the housing body 10a by an interference fit. The right end edge portion 10b2 of the outer peripheral portion 10ba is brought into contact with the bottom surface 10a1 of the housing body 10a, and the right end convex portion 10ca of the second ring member 10c described later is brought into contact with the left end edge portion 10b5 of the outer peripheral portion 10ba. .
The bottom surface 10a1 of the housing body 10a is formed with an annular groove KM that is annular when viewed from the axial direction via a stepped portion 10a2. As a result, the right end edge portion 10b3 of the inner peripheral portion 10bb of the first ring member 10b is arranged with a predetermined small distance and an axial gap δ1 from the annular groove KM. Further, a gap fit between the inner peripheral surface 10b4 of the inner peripheral portion 10bb and the outer ring outer diameter surface 12ga is a gap.

The second ring member 10 c is interposed between the first and third ring members 10 b and 10 d and is disposed so as to face the outer diameter surface of the outer ring spacer 17. The second ring member 10c is formed with a through hole 21 penetrating in the radial direction. The through-hole 21 is a hole for drawing out a wiring Sa, which is an output part of a sensor described later, out of the housing 10.
The right end portion in the axial direction of the second ring member 10c has a right end convex portion 10ca formed on the outer diameter side, and a flat surface 10cb connected to the right end convex portion 10ca on the inner diameter side through a stepped portion. Among these, the right end convex portion 10ca abuts on the left end edge portion 10b5 of the outer peripheral portion 10ba of the first ring member 10b. The flat surface 10cb is formed in a flat shape along a so-called radial plane, and is disposed at the left end edge portion 10b6 of the inner peripheral portion 10bb of the first ring member 10b with an axial gap δ2 therebetween. Further, a gap fit is provided between the inner peripheral surface of the second ring member 10 c and the outer diameter surface of the outer ring spacer 17.

  As shown in FIGS. 2 and 4, the left end of the second ring member 10c in the axial direction has a left end convex portion 10cc formed on the outer diameter side, and an inner diameter side of the left end convex portion 10cc via a stepped portion. And a continuous flat surface 10cd. Of these, the left end convex portion 10cc comes into contact with the right end edge portion 10d1 of the outer peripheral portion 10da of the third ring member 10d. The flat surface 10cd is formed in a flat shape along a radial plane, and is disposed on the right end edge portion 10d2 of the inner peripheral portion 10db of the third ring member 10d with an axial gap δ3 therebetween.

  As shown in FIG. 2 and FIG. 4, the third ring member 10d as the rigidity-decreasing portion disposed on the left side is an annular member having an I-shaped cross section, and is fitted to the inner peripheral surface 10aa of the housing body 10a. The outer peripheral part 10da to be joined, the inner peripheral part 10db facing the outer ring outer diameter surface 12ga of the other bearing 12, and the annular part 10dc connecting these inner and outer peripheral parts 10db, 10da. The annular portion 10dc is formed in parallel to the radial plane, and is provided near the right end in the axial direction of the inner and outer peripheral portions 10db and 10da. The third ring member 10d is also integrally formed from a steel material or the like similarly to the first ring member 10b. However, it is not limited only to steel materials.

The outer peripheral surface 10d3 of the outer peripheral portion 10da is fitted into the inner peripheral surface 10aa of the housing body 10a by an interference fit. The right end edge portion 10d1 of the outer peripheral portion 10da is brought into contact with the left end edge portion 10c1 of the second ring member 10c, and the right end convex portion 10ea of the fourth ring member 10e is contacted with the left end edge portion 10d4 of the outer peripheral portion 10da. Touching. A gap fit between the inner peripheral surface 10d5 of the inner peripheral portion 10db of the third ring member 10d and the outer ring outer diameter surface 12ga is a slight clearance. Further, in a state where the right end convex portion 10ea of the fourth ring member 10e is in contact with the left end edge portion 10d4 of the outer peripheral portion 10da, the left end edge portion 10d6 of the inner peripheral portion 10db and the axial direction of the fourth ring member 10e An axial gap δ4 is formed between the flat surface 10eb at the right end portion.
The lid member 10f abuts on one axial edge of the housing body 10a, abuts on the left axial end of the fourth ring member 10e, and abuts on the outer ring front surface 12gs of the other bearing 12. Be placed.

  As shown in FIG. 2, among the spacer main bodies 18, the right first divided spacer main body 18a has an axial right end in contact with the outer ring rear surface 12gh of one of the bearings 3 and along a radial plane. The flat left end in the axial direction is in contact with the strain-generating part 19. The right end of the first split spacer body 18a in the axial direction is connected to a contact surface 18aa that contacts the outer ring back surface 12gh on the outer diameter side, and a bearing 12 that is connected to the contact surface 18aa on the inner diameter side via a stepped portion. And a non-contact surface that does not contact.

  In the second split spacer main body 18b, the left end in the axial direction abuts on the outer ring rear surface 12gh of the other bearing 12, and the right end in the axial direction forms a radial plane and abuts on the straining portion 19. The left end of the second split spacer main body 18b in the axial direction is connected to the contact surface 18ba that contacts the outer ring rear surface 12gh on the outer diameter side, and the bearing 12 that is continuous to the inner diameter side of the contact surface 18ba via a stepped portion. And a non-contact surface that does not contact.

The strain generating unit 19, the sensor, and the like will be described.
As shown in FIGS. 1 and 2, the strain generating portion 19 is a ring-shaped member that generates strain due to an axial force acting between both ends of the spacer 17. The strain generating portion 19 has, for example, a weak portion at a part in the radial direction that is relatively less rigid than the other parts in the radial direction. An axial force is applied to the weak part of the strain generating part 19 from the first split spacer body 18a. For example, a strain sensor S1 such as a strain gauge is provided on the right end surface of the strain generating section 19, and the strain of the strain generating section 19 is detected by the strain sensor S1 serving as a detecting means. In this example, the distortion of a portion where a so-called beam on the right end surface of the strain generating portion 19 is extended is detected, but the present invention is not limited to this example. For example, a strain sensor S <b> 1 may be provided on the left end surface of the strain generating portion 19, and the strain of the so-called compressed portion of the left end surface of the strain generating portion 19 may be detected by the strain sensor S <b> 1. Further, the strain detection sensitivity may be increased by providing strain sensors S1 at a plurality of locations in the circumferential direction and adding the sensor outputs of the plurality of strain sensors S1.

  The wiring Sa, which is the output portion of the strain sensor S1, is drawn out of the housing 10 through the through hole 21 of the second ring member 10c and the hole 22 provided in the housing body 10a communicating with the through hole 21. Further, it is electrically connected to an abnormality detecting means 23 for detecting an abnormality of the rolling bearing. The strain detected by the strain sensor S1 is converted into an electric signal. The abnormality detection means 23 includes an electronic circuit or the like that calculates an abnormality detection value proportional to the electrical signal input via the wiring Sa.

  The abnormality detection means 23 has a relationship setting means (not shown) in which the relationship between the electrical signal and the abnormality detection value is set by an arithmetic expression or a table, and the relationship setting means Calculate the detection value in light of. Further, the abnormality detection means 23 may measure the peak voltage of the electrical signal by, for example, peak hold processing, and determine that the bearing is abnormal when the peak voltage falls outside a predetermined threshold. The abnormality detection means 23 may be an electronic circuit provided independently, or may be a part of a control device that controls the spindle device.

  The operation and effect of the above configuration will be described. When the main shaft 11 is rotated by the motor 13 and the temperature of the bearing 12 rises, the inner ring 12i expands, and the preload becomes larger than the initial set value, the axial force applied between both ends of the outer ring spacer 17 increases. When an axial force is applied to the strain generating portion 19 of the outer ring spacer 17 from the first split spacer main body 18a, stress is applied to the strain generating portion 19. As a result, strain is generated in the strain sensor S1 provided in the strain generating portion 19. The abnormality detection means 23 calculates an amount of preload by illuminating an electrical signal based on the detected strain against the relationship setting means. Therefore, if the relationship between the axial external force applied to the strain generating portion 19 and the electrical signal is examined in advance, the initial preload of the bearing 12 incorporated in the bearing device and the preload increased during operation can be known. A bearing abnormality can be determined based on the increased preload.

  The bearing 12 expands due to the temperature rise of the bearing 12 due to the rotation of the main shaft 11, whereas the housing 10 is cooled by the outer cylinder and the temperature is lower than that of the bearing 12. Therefore, there is no slight radial gap between the inner peripheral surfaces 10b4 and 10d5 of the inner peripheral portions 10bb and 10db of the first and third ring members 10b and 10d and the outer ring outer diameter surface 12ga, and an interference fit is obtained.

  Even in the case of such an interference fit, since the first and third ring members 10b and 10d as the rigidity-decreasing portions are provided in the housing 10, the preload applied to the bearing escapes to the housing 10 undesirably. Instead, it takes over the outer ring spacer 17. That is, the inner peripheral surfaces 10b4 and 10d5 of the inner peripheral portions 10bb and 10db of the ring members 10b and 10d and the outer ring outer diameter surface 12ga corresponding thereto are integrated with an interference fit. , 10d are displaced in the axial direction together with the outer rings 12g, 12g. That is, each of the ring members 10b and 10d has a cantilever shape in which the outer peripheral portions 10ba and 10da are so-called fixed ends and the inner peripheral portions 10bb and 10db are free ends. As shown in FIG. 3, the inner peripheral portion 10bb of the first ring member 10b is formed with axial gaps δ1, δ2 at both left and right ends, and the inner diameter side portion of the annular portion 10bc can be elastically deformed. The inner peripheral portion 10bb is relatively displaced in the axial direction of the axial gaps δ1, δ2 relative to the outer peripheral portion 10ba.

  Accordingly, it is possible to prevent a change in the preload of the bearing due to static friction between the bearing and the housing as in the past. Therefore, the detection error by the strain sensor S1 can be reduced and the bearing abnormality can be accurately detected. Further, since the housing constituent member includes the housing main body 10a and the first to fourth ring members 10b, 10c, 10d, and 10e provided on the inner peripheral surface 10aa of the housing main body 10, the ring member to the housing main body 10a is provided. Etc. can be easily assembled.

Next, a second embodiment of the present invention will be described with reference to FIG.
In the following description, the same reference numerals are given to portions corresponding to the matters described in the preceding forms in each embodiment, and overlapping description may be omitted. When only a part of the configuration is described, the other parts of the configuration are the same as those described in the preceding section. Not only the combination of the parts specifically described in each embodiment, but also the embodiments can be partially combined as long as the combination does not hinder.

In the bearing device according to the second embodiment, in particular, a rigidity-decreasing portion is provided in a portion facing the outer ring spacer 17 of the housing 10A.
The housing 10A includes a housing main body 10Aa and a lid member 10f, and a groove 24 is provided on an inner peripheral surface of the housing main body 10Aa facing the outer ring spacer 17. The groove 24 is an annular groove having a rectangular cross section, and a portion of the housing main body 10Aa in which the groove 24 is provided to reduce the thickness is a rigidity-decreasing portion 25. The rigidity reduced portion 25 is configured to have a rigidity lower than that of the thick portion 26 of the housing main body 10Aa. In addition, the rigidity reduced portion 25 is formed with a through hole 25a through which the wiring Sa of the strain sensor S1 is drawn out of the housing 10A. The through hole 25a is formed so as to penetrate in the radial direction. Other configurations are the same as those in the first embodiment.

  According to the configuration of the second embodiment, the number of parts of the entire apparatus can be reduced as compared with that of the first embodiment shown in FIG. That is, the first to fourth ring members and the like are not required as the plurality of housing constituent members, the structure of the bearing device can be simplified, and the manufacturing cost can be reduced. Further, the groove 24 of the housing main body 10Aa can be easily formed by turning or the like.

In the second embodiment, the bearing 12 expands due to the temperature rise of the bearing 12 due to the rotation of the main shaft 11, and the fit between the housing main body 10Aa and the outer ring outer diameter surface becomes a tight fit from the gap fit. However, since the reduced rigidity portion 25 of the housing body 10Aa having the reduced thickness is elastically deformed, the preload applied to the bearing 12 does not escape undesirably to the housing body 10Aa but is applied to the outer ring spacer 17. Therefore, the detection error by the strain sensor S1 can be reduced and the bearing abnormality can be accurately detected.
In the second embodiment, the rigidity is adjusted by the thickness of the rigidity reduced portion 25 of the housing main body 10Aa. However, the rigidity is determined by the diameter of the through hole 25a formed in the rigidity reduced portion 25 and the number of the through holes 25a. Can be adjusted . The rigidity can be adjusted by the thickness of the reduced rigidity portion 25 and the hole diameter of the through hole 25a.

Next, a third embodiment of the present invention will be described with reference to FIGS. This will be described with reference to FIGS. 1 and 6 as well.
In the third embodiment, a plurality of magnetostrictive materials 27, a plurality of coils 28, and the magnetostrictive materials 27 and 28 are held instead of the strain generating portion and the strain sensor of the first or second embodiment. And a ring member RB to be provided.
A plurality (three in this embodiment) of the magnetostrictive material 27 is provided on the ring member RB at regular intervals in the circumferential direction. The ring member RB is made of, for example, a nonmagnetic material such as stainless steel, and has an accommodation hole RBa that holds or accommodates the magnetostrictive material 27. It is also possible to provide a plurality of magnetostrictive materials 127 at appropriate intervals in the circumferential direction. Further, the number of magnetostrictive materials is not limited to three, and an appropriate number may be selected according to the situation. Each magnetostrictive material 27 is a cylindrical member parallel to the axial direction of the main shaft 11 (see FIG. 1 and the like). A coil bobbin (not shown) is fitted to the outer periphery of the cylindrical member, and a coil 28 is fitted to the coil bobbin. It is wound. A magnetostrictive sensor S2 is configured by winding a coil 28 around each magnetostrictive material 27 via a coil bobbin. The coil 28 may be connected in series across the plurality of magnetostrictive materials 27. The coil 28 is made of enameled wire, for example.

  The wiring Sa, which is the output part at both ends of the coil of the magnetostrictive sensor S2, is drawn out of the housing 10 (10A) through the through hole of the housing 11, and is electrically connected to the abnormality detecting means 23. In this case, the abnormality detection means 23 is composed of an electronic circuit that applies a sine wave having a fixed period to the coil 28 constituting the magnetostrictive sensor S2, detects an inductance from the phase delay, and calculates a preload amount and the like. The abnormality detection means 23 has a relationship setting means (not shown) in which the relationship between the phase delay and the preload amount is set by an arithmetic expression or a table, and the preload is detected in light of the detected phase delay. Calculate the amount. In addition to the above, the inductance of the coil 28 may be detected by measuring the resonance frequency of the capacitor and the coil, or using a bridge circuit. Further, the coil inductance may be detected using a phase detection circuit. This inductance measurement method using a phase detector circuit is a method in which a sine wave current having a constant period and constant amplitude is applied to the coil and the inductance component of the voltage across the coil is detected by the phase detector circuit, and is not affected by the resistance component of the coil. Inductance can be accurately measured.

The bearing device described above can also be applied to devices other than spindle devices, robots, and the like. In the present embodiment, the two bearings are installed in the rear combination, but may be installed in the front combination. Further, the number of bearings is not necessarily limited to two.
In the present embodiment, the strain-generating body is provided at the axial ends of the first and second spacer members of the outer ring spacer. However, in an apparatus other than the spindle device, for example, the shaft of the inner ring spacer body You may provide a strain body in the direction edge part. In this case, it is desirable to rotate the outer ring and to draw the sensor output wiring out of the bearing device through the shaft.

It is sectional drawing of the bearing apparatus etc. which concern on 1st Embodiment of this invention. It is sectional drawing of the principal part of the bearing apparatus. It is an expanded sectional view of the principal part of a housing structural member. It is an expanded sectional view of another principal part of a housing structural member. It is sectional drawing of the ring member of the cross-section I shape of the same bearing apparatus. It is sectional drawing of the bearing apparatus etc. which concern on 2nd Embodiment of this invention. It is sectional drawing of the principal part of the sensor part of the bearing apparatus which concerns on 3rd Embodiment of this invention. It is an expanded sectional view of the magnetostriction type sensor of the sensor part. It is sectional drawing of the bearing apparatus etc. of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Housing 10a ... Housing main body 10b ... 1st ring member 10d ... 3rd ring member 11 ... Main shaft 12 ... Bearing 12g ... Outer ring 16 ... Inner ring spacer 17 ... Outer ring spacer 18 ... Spacer main body 19 ... Strain part 23 ... Abnormality detection means 24 ... Groove 25 ... Decrease in rigidity S1 ... Strain sensor S2 ... Magnetostrictive sensor

Claims (5)

In a bearing device configured to receive a preload with a spacer interposed between race rings of a plurality of rolling bearings arranged in the axial direction,
The spacer includes an outer ring spacer interposed between the outer rings arranged in the axial direction and an inner ring spacer interposed between the inner rings, and detecting means for detecting a preload applied to the bearing is provided as the outer ring spacer. Provided in
A housing for fitting the rolling bearing and the outer ring spacer is provided, only set the rigidity reduction portion to reduce the rigidity of the part amount facing the bearing of the housing, wherein the housing includes a housing body, the inner periphery of the housing body A ring member provided on a surface of the ring member, the ring member is disposed so as to face the bearing, and is formed in a cross-section I shape as the rigidity-decreasing portion. The axial direction clearance which displaces the said inner peripheral part to an axial direction relatively with respect to the outer peripheral part of the said ring member is provided . In a bearing device configured to receive a preload with a spacer interposed between race rings of a plurality of rolling bearings arranged in the axial direction,
The spacer includes an outer ring spacer interposed between the outer rings arranged in the axial direction and an inner ring spacer interposed between the inner rings, and detecting means for detecting a preload applied to the bearing is provided as the outer ring spacer. Provided in
A housing for fitting the rolling bearing and the outer ring spacer is provided, and a rigidity decreasing portion for decreasing the rigidity of the portion facing the outer ring spacer is provided in the housing, and the rigidity decreasing portion is a groove on the inner peripheral surface of the housing. By providing a through-hole through which the output portion of the detection means is drawn out of the housing, so as to penetrate the rigidity-reduced portion in the radial direction, the diameter and number of the through-holes are provided. The bearing device is configured so that the rigidity of the rigidity-decreasing portion can be adjusted. In Claim 1 or Claim 2 , the strain generating part which generates distortion by the axial direction force which acts between the both ends of this spacer is provided in a part of the axial direction of said outer ring spacer, and the above-mentioned detection means Bearing device that detects the distortion of the part. 3. The magnetostrictive material according to claim 1 or 2 , wherein a magnetic characteristic is changed in part in an axial direction of the outer ring spacer due to an axial force acting between both ends of the spacer, and the detecting means includes the magnetostrictive member. Bearing device that detects changes in magnetic properties of materials. In any one of claims 1 to 4, wherein the detection value detected by the detecting means, a bearing device provided with abnormality detecting means for detecting an abnormality of the bearing.

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