Determination device

Abstract

According to the present invention, a probe comprises: a substantially columnar probe body that is in contact with a measurement target surface of a bearing and detects the impedance of the bearing; a housing which has therein a sliding hole extending in the axial direction, and in which the probe body disposed in the sliding hole is accommodated so as to be able to slide in the axial direction; an abutting part that is provided at a tip part of the housing and can abut against the measurement target surface of the bearing; and a biasing spring that is disposed in the sliding hole of the housing and biases the probe body in the axial direction with respect to the housing. The abutting part has four protrusions that protrude in the axial direction, and when viewed in the axial direction, the four protrusions are respectively positioned at the vertices of a rectangle centered on the central axis of the probe body.

Description

Judgment device

[0001] The present invention relates to a determination device.

[0002] For example, rolling bearings used in papermaking machines, wind power generation equipment, mining and construction equipment, and railway vehicles are subject to heavy loads and harsh lubrication conditions that expose them to the intrusion of foreign objects and water, making flaking on the bearing raceway a problem. Flaking on rolling bearings not only has the potential to cause significant damage to products and equipment, but it also impacts manufacturing delivery dates and schedules. To prevent sudden flaking, rolling bearings are sometimes periodically disassembled and cleaned, and visual inspections of the raceway surface are conducted. However, predicting the remaining life of a bearing based on visual inspection (estimating the period until flaking occurs) relies on the experience and skill of the operator, making quantitative predictions difficult.

[0003] In response to this, Patent Document 1 discloses a prediction method for non-destructively inspecting rolling bearings used by users and predicting the fatigue progression or remaining life of the rolling bearing. Specifically, the prediction method in Patent Document 1 includes the steps of: creating a map in advance in which output voltage values ​​obtained by eddy current measurement of the rolling bearing are represented on an X-Y coordinate system, and associating the fatigue progression or remaining life for each coordinate; measuring the output voltage values ​​of the raceway surface or rolling surface of the rolling bearing using an eddy current measurement device; and determining the fatigue progression or remaining life of the rolling bearing by overlaying the measured output voltage values ​​of the rolling bearing on the map. This enables non-destructive inspection of bearings used by users and enables highly accurate prediction of the fatigue progression or remaining life of the rolling bearing before damage due to fatigue progression occurs to the bearing.

[0004] Japanese Patent Application Publication No. 2014-055941

[0005] The eddy current measurement device described in Patent Document 1 nondestructively measures the amount of retained austenite by passing an excitation current through a coil in a probe to induce eddy currents in the metal being measured (the outer ring, inner ring, and rolling elements of a rolling bearing). The eddy currents then generate an output voltage across the coil, which is then detected. Therefore, when measuring the output voltage of an outer ring raceway using an eddy current measurement device, for example, the probe must be stably and correctly positioned in contact with the outer ring raceway. However, if the probe's position relative to the outer ring shifts during measurement, the measured value will also change, making it impossible to accurately predict the fatigue progression or remaining life of the rolling bearing. In particular, when the surface being measured is curved, it is difficult to maintain the probe's position while properly contacting the curved surface.

[0006] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a determination device that can stabilize the attitude of a probe relative to a bearing and accurately determine the fatigue level or remaining life of the bearing.

[0007] Therefore, the above object of the present invention is achieved by the configuration of [1] below. [1] A determination device comprising: a probe that applies an AC magnetic field to induce eddy currents in a bearing and detects the impedance of the bearing; a switch that transmits a measurement control signal that switches between starting and stopping the acquisition of a measurement signal of the impedance detected by the probe; and a fatigue determination unit that determines the fatigue level or remaining life of the bearing based on the impedance of the bearing, wherein the fatigue determination unit comprises: a map storage unit that stores a determination map including the relationship between the impedance characteristics of the bearing and the fatigue level or remaining life of the bearing; a measurement switching unit that switches between a measurement execution state and a measurement non-execution state based on the state of the measurement control signal; a data storage unit that stores the measurement signals in the measurement execution state; an impedance characteristic calculation unit that calculates the impedance characteristics of the bearing based on the stored measurement signals; and a determination unit that determines the fatigue level or remaining life of the bearing based on the impedance characteristics of the bearing and the determination map, wherein the probe comprises: a substantially columnar probe body that comes into contact with a measurement target surface of the bearing to detect the impedance of the bearing; a housing having a sliding hole extending in the axial direction therein, the housing accommodating the probe body arranged in the sliding hole so that the probe body can slide in the axial direction; an abutment portion provided at the tip of the housing and capable of abutting against the measurement target surface of the bearing; and a biasing spring arranged in the sliding hole of the housing and biasing the probe body in the axial direction relative to the housing, wherein the abutment portion has four protrusions protruding in the axial direction, and when viewed from the axial direction, the four protrusions are respectively located at the vertices of a rectangle centered on the central axis of the probe body.

[0008] According to the determination device of the present invention, the attitude of the probe relative to the bearing can be stabilized, and the fatigue level or remaining life of the bearing can be accurately determined.

[0009] FIG. 1 is a schematic diagram of a determination device for determining the degree of fatigue or remaining life of a bearing. FIG. 2 is a schematic diagram of a fatigue determination unit. FIG. 3 is a schematic diagram showing a state in which a probe is used to measure the impedance of the raceway surface of the outer ring of a rolling bearing. FIG. 4 is a perspective view of the probe. FIG. 5 is a cross-sectional view of the probe. FIG. 6 is a cross-sectional view showing a state in which a probe is in perpendicular contact with the raceway surface of the outer ring. FIG. 7 is a view seen in the direction of arrow VII in FIG. 6. FIG. 8 is a cross-sectional view taken along arrows VIII1-VIII1 or VIII2-VIII2 in FIG. 6. FIG. 9 is an enlarged view of the probe in FIG. 7. FIG. 10 is a cross-sectional view showing a state in which a probe is in perpendicular contact with the raceway surface of the inner ring. FIG. 11 is a view seen in the direction of arrow XI in FIG. 10. FIG. 12 is a cross-sectional view taken along arrows XII-XII in FIG. 11. FIG. 13 is a cross-sectional view taken along arrows XIII-XIII in FIG. 11. FIG. 14 is an enlarged view of the probe in FIG. 11. FIG. 15 is an enlarged view of a portion of FIG.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a determination device for determining the fatigue level or remaining life of a bearing according to each embodiment of the present invention will be described in detail with reference to the drawings.

[0011] Fig. 1 is a schematic diagram of a determination device for determining the degree of fatigue or remaining life of a bearing. As shown in Fig. 1, the determination device 1 includes a probe 10 that applies an AC magnetic field to induce eddy currents in the bearing and detects the impedance of the bearing, a switch 30 that transmits a measurement control signal S2 that switches the start and end of acquisition of a measurement signal S1 of the impedance detected by the probe 10, an input unit 40 that acquires the measurement signal S1 and the measurement control signal S2, and a fatigue determination unit 50 that determines the degree of fatigue or remaining life of the bearing based on the impedance of the bearing.

[0012] A coil (not shown) is built into the probe 10. An excitation current is passed through the coil in the probe 10 to apply an AC magnetic field to the bearing to be measured (for example, the outer ring, inner ring, or rolling elements of a rolling bearing), thereby inducing eddy currents, and the impedance generated in the coil by the eddy currents is detected to non-destructively measure the metal structure (for example, the amount of retained austenite). Examples of surfaces to be measured in the bearing include the raceway surface, outer peripheral surface, and both axial end faces of the outer ring, the raceway surface, inner peripheral surface, and both axial end faces of the inner ring, and the circumferential surfaces of the rolling elements.

[0013] When the probe 10 is in contact with the measurement target surface of the bearing, a measurement signal S1 of the bearing impedance is always transmitted to the fatigue determination unit 50 via the input unit 40. However, as will be described later, the fatigue determination unit 50 does not always acquire the measurement signal S1, but switches between acquiring and not acquiring the measurement signal S1 based on the state of a measurement control signal S2 transmitted by the switch 30.

[0014] The switch 30 is a member that can be pressed by a user. For example, when the switch 30 is pressed (ON state), a measurement control signal S2 that switches the start and end of acquisition of the measurement signal S1 is sent to the input unit 40, and when the switch 30 is not pressed (OFF state), the measurement control signal S2 is not sent to the input unit 40. For example, when the measurement control signal S2 is sent to the input unit 40, the measurement signal S1 is acquired by the fatigue determination unit 50, resulting in a measurement execution state in which measurement is performed. When the measurement control signal S2 is not sent to the input unit 40, the measurement signal S1 is not acquired by the fatigue determination unit 50, resulting in a measurement non-execution state in which measurement is not performed.

[0015] The input unit 40 is connected to the probe 10 via a cable 25 (see FIG. 3 ) described below, and includes an A / D converter (not shown) that receives a measurement signal S1 of the bearing impedance detected by the probe 10, and a digital input / output unit (not shown) that is connected to the switch 30 and receives a measurement control signal S2 transmitted by the switch 30. The measurement signal S1 and measurement control signal S2 are transmitted to the fatigue determination unit 50 via the input unit 40.

[0016] 2 is a schematic diagram of the fatigue determination unit. As shown in Fig. 2, the fatigue determination unit 50 includes a map storage unit 51 that stores a determination map including the relationship between the impedance characteristics (resistance component and reactance component) of the bearing and the fatigue level or remaining life of the bearing, a measurement switching unit 53 that switches between a measurement execution state and a measurement non-execution state based on the state of a measurement control signal S2, a data storage unit 55 that stores a measurement signal S1 in the measurement execution state, an impedance characteristics calculation unit 57 that calculates the impedance characteristics (resistance component and reactance component) of the bearing based on the stored measurement signal S1, a determination unit 59 that determines the fatigue level or remaining life of the bearing based on the impedance characteristics (resistance component and reactance component) of the bearing and the determination map, and a display unit 58 that displays the determination result.

[0017] The fatigue determination unit 50 may include, for example, a computer including a processor and peripheral components such as a storage device. The processor may be, for example, a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit). The storage device may include any of a semiconductor storage device, a magnetic storage device, and an optical storage device. The storage device may include memories such as a register, a cache memory, and a ROM (Read Only Memory) and a RAM (Random Access Memory) used as a main storage device. The fatigue determination unit 50 may be configured with dedicated hardware for executing each information processing. For example, the fatigue determination unit 50 may include a functional logic circuit set in a general-purpose semiconductor integrated circuit. For example, the fatigue determining unit 50 may include a programmable logic device (PLD) such as a field-programmable gate array (FPGA).

[0018] The fatigue determination unit 50 determines the remaining life of the bearing by referring to the correlation between the impedance characteristics measured by the probe 10 and the determination map stored in the map memory unit 51, and displays the remaining life on a display unit 58 such as a display.

[0019] FIG. 3 is a schematic diagram showing how the impedance of the raceway surface 61 of the outer ring 60 of a rolling bearing is measured by the probe 10. As shown in FIG. 3, the probe 10 contacts the raceway surface 61 and applies an AC magnetic field to induce eddy currents in the raceway surface 61, thereby detecting the impedance of the raceway surface 61. A measurement signal S1 of the detected impedance is transmitted to the input unit 40 via the cable 25. In this manner, when the measurement target surface is the raceway surface 61 of the outer ring 60, the map storage unit 51 of the fatigue determination unit 50 pre-stores a determination map that includes the relationship between the resistance component and reactance component, which are the impedance characteristics of the raceway surface 61 of the outer ring 60, and the fatigue degree or remaining life of the outer ring 60. Therefore, by measuring the impedance characteristics of the raceway surface 61 of the outer ring 60, the fatigue degree or remaining life of the outer ring 60 can be determined based on the determination map.

[0020] Based on the state of the measurement control signal S2, the measurement switching unit 53 switches between a measurement implementation state in which the measurement signal S1 is taken into the fatigue determination unit 50 and measurement is performed, and a measurement non-implementation state in which the measurement signal S1 is not taken into the fatigue determination unit 50 and measurement is not performed. For example, the measurement switching unit 53 is in the measurement implementation state when the measurement control signal S2 is being sent from the switch 30 to the input unit 40, and is in the measurement non-implementation state when the measurement control signal S2 is not being sent from the switch 30 to the input unit 40. Therefore, the user confirms that the probe 10 is in contact with the raceway surface 61 of the outer ring 60 in the correct posture, and then presses the switch 30 to transition the determination device 1 to the measurement implementation state.

[0021] The data holding unit 55 holds the measurement signal S1 of the impedance of the raceway surface 61 of the outer ring 60 in the measurement implementation state.

[0022] The impedance characteristic calculation unit 57 calculates the resistance component and the reactance component of the impedance of the raceway surface 61 of the outer ring 60 based on the measurement signal S1 stored in the data storage unit 55 .

[0023] The determination unit 59 determines the degree of fatigue or remaining life of the outer ring 60 based on the resistance component and reactance component of the impedance of the raceway surface 61 of the outer ring 60 calculated by the impedance characteristics calculation unit 57 and the determination map stored in the map storage unit 51. The determined degree of fatigue or remaining life of the outer ring 60 is displayed on the display unit 58.

[0024] The fatigue level or remaining life of a bearing is determined by the determination device 1 having the above-described configuration, but in order to accurately measure the impedance of the bearing, it is necessary to stably contact the probe 10 with the measurement target surface in the correct position. The correct position of the probe 10 means, for example, a position in which the probe 10 is perpendicular to the measurement target surface. The configuration of the probe 10 adopted to stably contact the probe 10 with the bearing in the correct position during measurement will be described in detail below.

[0025] Fig. 4 is a perspective view of the probe. Fig. 5 is a cross-sectional view of the probe. As shown in Figs. 4 and 5, the probe 10 includes a substantially cylindrical probe body 11 that abuts against the measurement target surface of the bearing to detect the impedance of the bearing, a housing 13 having a slide hole 14 extending in the axial direction therein and that accommodates the probe body 11 arranged in the slide hole 14 so that it can slide in the axial direction, an abutment portion 15 provided at the tip of the housing 13 and that can abut against the measurement target surface of the bearing, and a coil spring 17 that is arranged in the slide hole 14 of the housing 13 and serves as a biasing spring that axially biases the probe body 11 against the housing 13.

[0026] The housing 13 is a thin, tubular member extending in the axial direction (the longitudinal direction of the housing 13; vertical direction in FIG. 5 ). It is formed by a coaxial, substantially cylindrical base portion 13a and a substantially rectangular parallelepiped tip portion 13b that are integrally connected in the axial direction. The housing 13 is made of resin to minimize any influence on impedance measurement. The sliding hole 14 extends axially through the base portion 13a and tip portion 13b of the housing 13. Since the sliding hole 14 has the same diameter throughout the entire axial range, the inner diameter of the base portion 13a and the inner diameter of the tip portion 13b are the same. Meanwhile, the outer diameter of the tip portion 13b is larger than the outer diameter of the base portion 13a. Therefore, a step portion 13c perpendicular to the axial direction is formed at the connection between the tip portion 13b and the base portion 13a. For example, a user may grasp the base portion 13a of the housing 13 and apply the probe 10 to a surface to be measured. The user may grip the tip portion 13 b of the housing 13 .

[0027] The sliding hole 14 includes a tip opening 14a formed at the tip end (lower part in FIG. 5 ) of the housing 13 and a base opening 14b formed at the base end (upper part in FIG. 5 ) of the housing 13. As will be described later, the probe main body 11 is biased toward the tip end of the probe 10 by a coil spring 17, and this biasing force allows the probe main body 11 to protrude outward from the tip opening 14a of the sliding hole 14. A lid 16 having a through hole 16a at its center is fitted into the base opening 14b of the sliding hole 14. A cable 25 connected to the probe main body 11 is drawn outward from the through hole 16a of the lid 16.

[0028] An elongated hole 13e is formed in one of the four outer peripheral surfaces 13d of the tip portion 13b of the housing 13, penetrating the outer peripheral surface 13d in the radial direction. The elongated hole 13e is an elongated hole whose axial dimension is longer than its dimensions in two directions perpendicular to the axial direction. A pair of pins 24, 24 fixed to a holder portion 22 of the probe main body 11 (described later) is disposed in this elongated hole 13e. When the probe main body 11 slides in the axial direction, the pair of pins 24, 24 slide within the elongated hole 13e. The pair of pins 24, 24 contact both axial ends of the elongated hole 13e (the upper and lower ends in FIG. 5 ) to restrict the sliding, thereby limiting the axial movement distance of the probe main body 11.

[0029] The probe body 11 comprises a probe portion 21 and a holder portion 22, which is separate and stores the probe portion 21 therein and is slidable relative to the sliding hole 14 of the housing 13. By providing the probe portion 21 and the holder portion 22 as separate bodies, if either one is damaged, they can be replaced independently, reducing maintenance costs. The probe portion 21 and the holder portion 22 are made of resin to minimize any influence on impedance measurement.

[0030] The probe section 21 has a generally cylindrical shape and has a coil (not shown) embedded therein. A cable 25 for extracting a measurement signal S1 is connected to the base end side (upper side in FIG. 5 ) of the probe section 21. The cable 25 extends through the sliding hole 14 and is pulled out to the outside from the through-hole 16 a of the lid section 16 installed in the base opening 14 b. The pulled-out cable 25 is connected to the input section 40 (see FIG. 1 ).

[0031] The holder portion 22 has a generally cylindrical shape and covers the outer periphery of the probe portion 21. A pair of female threaded holes 22a, 22a spaced apart from each other in the axial direction is formed in a part of the holder portion 22, and a pin 24 is threadedly engaged with each of the pair of female threaded holes 22a, 22a. The pair of pins 24, 24 fix the probe portion 21 and the holder portion 22. Therefore, when the holder portion 22 slides relative to the slide hole 14, the probe portion 21 also slides integrally. The pair of pins 24, 24 protrude radially outward beyond the pair of female threaded holes 22a, 22a, and contact both axial ends of the elongated hole 13e to restrict sliding, thereby limiting the axial movement distance of the probe main body 11.

[0032] The probe main body 11, which is made up of the probe portion 21 and the holder portion 22, is disposed on the distal end side of the sliding hole 14. Meanwhile, a coil spring 17 is disposed on the proximal end side of the sliding hole 14. The coil spring 17 extends in the axial direction so as to abut against the lid portion 16 fixed to the housing 13 and the probe main body 11. As a result, the probe main body 11 is biased by the coil spring 17 toward the distal end side relative to the housing 13.

[0033] In this embodiment, the coil spring 17 abuts against the holder portion 22 located on the outer periphery of the probe body 11. Therefore, the outer diameter of the coil spring 17 can be set to be approximately equal to the inner diameter of the sliding hole 14, and the coil spring 17 can be configured to be guided by the sliding hole 14, which prevents the coil spring 17 from buckling and stabilizes the biasing force.

[0034] Furthermore, a gap exists on the inner diameter side of the coil spring 17, and the cable 25 of the probe main body 11 extends through this gap. In this way, the cable 25 is disposed in the dead space on the inner diameter side of the coil spring 17, which contributes to miniaturization of the probe 10.

[0035] Fig. 6 is a cross-sectional view showing a state in which a probe is in contact perpendicularly with the raceway surface of the outer ring. Fig. 7 is a view seen in the direction of arrow VII in Fig. 6. Fig. 8 is a cross-sectional view taken along arrows VIII1-VIII1 or VIII2-VIII2 in Fig. 6. Fig. 9 is an enlarged view of the probe in Fig. 7.

[0036] As shown in Figures 4 to 9, the substantially rectangular parallelepiped tip 13b of the housing 13 is provided with an abutment 15 that can abut against the raceway surface 61 of the outer ring 60, which is the surface to be measured. The raceway surface 61 of the outer ring 60 used in the description of the embodiment is a concave spherical surface. The raceway surface 61 may have any shape, and may be cylindrical, for example. As shown in Figures 7 and 9 in particular, the shape of the abutment 15 as viewed from the axial direction is preferably rectangular, and in the illustrated example, it is square.

[0037] The abutting portion 15 has four protrusions 26 of the same shape that protrude in the axial direction. As shown in FIG. 9 , the protrusions 26 are substantially rectangular, and the tip surfaces 26 a of the protrusions 26 are rectangular. The four protrusions 26 are arranged at the vertices of the rectangle of the abutting portion 15. Furthermore, when viewed from the axial direction, the four protrusions 26 are each located at the vertices of a rectangle R whose center is the central axis O1 of the probe main body 11. In FIG. 9 , the rectangle R is a square indicated by a dashed line, and is formed by connecting the centers of the tip surfaces 26 a of the four protrusions 26. Therefore, the four protrusions 26 are arranged at positions equidistant from the central axis O1 and at equal intervals in the circumferential direction around the central axis O1. Note that the rectangle R does not necessarily have to be square and may be, for example, rectangular. Furthermore, it is preferable that the rectangle R has a similar shape to the rectangle of the abutting portion 15.

[0038] 6 to 9, during measurement, it is necessary to maintain the correct posture of the probe 10 so that it is perpendicular to the raceway surface 61 of the outer ring 60. Therefore, the user makes sure that all four protrusions 26 of the abutment portion 15 are in contact with the raceway surface 61 of the outer ring 60.

[0039] The four protrusions 26 contact the raceway surface 61, which is a concave spherical surface, at the outer corners 26b that are farthest from the central axis O1 of the probe main body 11. By bringing the outer corners 26b of each of the four protrusions 26 into contact with the raceway surface 61 in this way, the probe main body 11 can be maintained perpendicular to the raceway surface 61, and stable measurement results can be obtained.

[0040] When the outer corners 26b of all four protrusions 26 come into contact with the raceway surface 61, the user can perceive that the wobble of the probe 10 being held has been resolved and the posture of the probe 10 has stabilized. The user then presses the switch 30 to start capturing the measurement signal S1, and the fatigue level or remaining life of the bearing is determined.

[0041] If the raceway surface 61 has a cylindrical shape concentric with the central axis O2 of the outer ring 60, it is necessary to maintain the probe 10 in a correct orientation perpendicular to the raceway surface 61 during measurement. In this case, as shown in FIG. 9 , adjustments are made so that the central axis O1 of the probe body 11 and the central axis O2 of the outer ring 60 are perpendicular, two parallel sides r1 and r2 of the four sides constituting the rectangle R are parallel to the central axis O2 of the outer ring 60, and the other two parallel sides r3 and r4 of the four sides constituting the rectangle R are perpendicular to the central axis O2 of the outer ring 60. A pair of protrusions 26, 26 on one circumferential side (upper side in FIG. 9 ) are spaced apart in the direction of the central axis O2 of the outer ring 60, and similarly, a pair of protrusions 26, 26 on the other circumferential side (lower side in FIG. 9 ) are also spaced apart in the direction of the central axis O2 of the outer ring 60. Note that the locations at which the four protrusions 26 contact the raceway surface 61 differ from those in the case where the raceway surface 61 is a concave spherical surface. When the raceway surface 61 has a cylindrical shape, the four protrusions 26 contact the raceway surface 61 at the circumferential outer sides 26d including the outer corners 26b.

[0042] Next, a case where a raceway surface 71 formed on the outer peripheral surface of the inner ring 70 is measured will be described. Fig. 10 is a cross-sectional view showing a state where a probe is brought into contact perpendicularly with the raceway surface of the inner ring. Fig. 11 is a view seen in the direction of arrow XI in Fig. 10. Fig. 12 is a cross-sectional view taken along arrows XII-XII in Fig. 11. Fig. 13 is a cross-sectional view taken along arrows XIII-XIII in Fig. 11. Fig. 14 is an enlarged view of the probe in Fig. 11. Fig. 15 is a partial enlarged view of Fig. 10.

[0043] In the illustrated example, double-row raceway surfaces 71, 71 are formed on the outer peripheral surface of the inner ring 70. The raceway surfaces 71 are convexly curved. The raceway surfaces 71 may have any shape, for example, a cylindrical shape. As shown in FIGS. 10 to 15 , during measurement, the probe 10 must be maintained in a correct orientation perpendicular to the raceway surface 71 of the inner ring 70. Therefore, the user adjusts the orientation of the probe 10 so that all four protrusions 26 of the abutment portion 15 are in contact with the raceway surface 71 of the inner ring 70. Specifically, as shown in FIGS. 14 and 15 , the central axis O1 of the probe body 11 and the normal direction O4 of the contact angle α of the inner ring 70 are perpendicular, two parallel sides r1 and r2 of the four sides constituting the rectangle R are parallel to the normal direction O4 of the contact angle α, and the other two parallel sides r3 and r4 of the four sides constituting the rectangle R are perpendicular to the normal direction O4 of the contact angle α.

[0044] Here, the normal direction O4 of the contact angle α will be described with reference to FIG. 15 . In FIG. 15 , α is the contact angle, O3 is the central axis of the inner ring 70, O4 is the normal direction of the contact angle α, and O5 is the contact angle direction. The contact angle α is defined as the "nominal contact angle" described in Japanese Industrial Standard JIS B 0104-1991, "Rolling Bearing Terminology," and is the angle formed by a plane S perpendicular to the central axis O3 of the inner ring 70 and the contact angle direction O5. The contact angle direction O5 is the direction of the line of action of the load, which is the direction of the force applied to the inner ring 70 from the rolling elements (not shown). The normal direction O4 of the contact angle α is a direction passing through the raceway surface 71 and perpendicular to the contact angle direction O5. When the probe 10 is correctly oriented perpendicular to the raceway surface 71, the central axis O1 of the probe body 11 coincides with the contact angle direction O5 and is perpendicular to the normal direction O4 of the contact angle α.

[0045] When the four protrusions 26 are brought into contact with the raceway surface 71 in this way, a pair of the protrusions 26 is located on each side in the circumferential direction, sandwiching the normal direction O4 of the contact angle α, as shown in Fig. 14. The pair of protrusions 26, 26 on one circumferential side (upper side in Fig. 14) are spaced apart in the normal direction O4 of the contact angle α, and similarly, the pair of protrusions 26, 26 on the other circumferential side (lower side in Fig. 14) are also spaced apart in the normal direction O4 of the contact angle α of the inner ring 70.

[0046] The four protrusions 26 contact the raceway surface 71, which is a convex curved surface, at their inner corners 26c. Of the four corners of the tip surface 26a of the protrusions 26, the inner corners 26c are those that are located on the outer side with respect to the normal direction O4 of the contact angle α and on the inner side in the circumferential direction. By bringing the inner corners 26c of each of the four protrusions 26 into contact with the raceway surface 71 in this way, the probe main body 11 can be maintained perpendicular to the raceway surface 71, and stable measurement results can be obtained.

[0047] When the inner corners 26c of all four protrusions 26 come into contact with the raceway surface 71, the user can perceive that the wobble of the probe 10 being held has been eliminated and the posture of the probe 10 has stabilized. The user then presses the switch 30 to start capturing the measurement signal S1, and the fatigue level or remaining life of the bearing is determined.

[0048] Even when the raceway surface 71 has a cylindrical shape concentric with the central axis O3 of the inner ring 70, it is necessary to maintain the probe 10 in a correct orientation perpendicular to the raceway surface 71 during measurement. In this case, although not specifically shown, adjustments can be made so that the central axis O1 of the probe body 11 and the central axis O3 of the inner ring 70 are perpendicular, two parallel sides r1 and r2 of the four sides that make up the rectangle R are parallel to the central axis O3 of the inner ring 70, and the other two parallel sides r3 and r4 of the four sides that make up the rectangle R are perpendicular to the central axis O3 of the inner ring 70. A pair of protrusions 26, 26 on one circumferential side (upper side in FIG. 14 ) are spaced apart from each other in the direction of the central axis O3 of the inner ring 70, and similarly, a pair of protrusions 26, 26 on the other circumferential side (lower side in FIG. 14 ) are also spaced apart from each other in the direction of the central axis O3 of the inner ring 70. The locations at which the four protrusions 26 contact the raceway surface 71 differ from those in the case where the raceway surface 71 is a convex spherical surface. When the raceway surface 71 has a cylindrical shape, the four protrusions 26 contact the raceway surface 61 at the circumferential inner sides 26e (see FIG. 14) including the inner corners 26c.

[0049] In the illustrated example, the shape of the abutting portion 15 when viewed from the axial direction is rectangular, and the four protrusions 26 are arranged at the vertices of the rectangle of the abutting portion 15. Therefore, the four protrusions 26 can be provided on the abutting portion 15 with efficient use of space, and the distance between adjacent protrusions 26 can be increased, thereby stabilizing the posture of the probe 10.

[0050] The shape of the abutment portion 15 as viewed from the axial direction is not limited to a rectangle, but may be any shape, for example, a circle for ease of manufacture.

[0051] In the illustrated example, the tip surfaces 26a of the protrusions 26 are rectangular when viewed in the axial direction. This allows the orientation of the probe 10 to be stably maintained when the measurement target surface is the raceway surface 61 of the outer ring 60, which is a concave spherical surface, by bringing the outer corners 26b of each of the four protrusions 26 into contact with the raceway surface 61. If the measurement target surface is the raceway surface 71 of the inner ring 70, which is a convex curved surface, the orientation of the probe 10 can be stably maintained by bringing the inner corners 26c of each of the four protrusions 26 into contact with the measurement target surface. Furthermore, although not specifically illustrated, when the measurement target surface is a flat surface, the orientation of the probe 10 can be stably maintained by bringing the entire tip surfaces 26a of the four protrusions 26 into contact with the measurement target surface.

[0052] The shape of the tip surface 26a of the projection 26 as viewed in the axial direction is not limited to a rectangle, but may be any shape, for example, a circle for ease of manufacture.

[0053] In the illustrated example, the protrusion 26 is provided integrally with the abutment portion 15, but the protrusion 26 may also be a pin separate from the abutment portion 15. In this case, the pin constituting the protrusion 26 may be fixed by any method, for example, by gluing it to the abutment portion 15 or by press-fitting or screwing it into a hole formed in the abutment portion 15. By providing the protrusion 26 as a separate part in this way, the protrusion 26 can be replaced if it is damaged or worn. Furthermore, the protrusion 26 can be replaced with an appropriate protrusion 26 for different measurement target surfaces depending on their characteristics such as shape and roughness.

[0054] The present invention is not limited to the above-described embodiments, and modifications and improvements are possible as appropriate.

[0055] As described above, the present specification discloses the following: (1) A determination device comprising: a probe that applies an AC magnetic field to induce eddy currents in a bearing and detects the impedance of the bearing; a switch that transmits a measurement control signal that switches between starting and stopping acquisition of a measurement signal of the impedance detected by the probe; and a fatigue determination unit that determines the fatigue level or remaining life of the bearing based on the impedance of the bearing, wherein the fatigue determination unit comprises: a map storage unit that stores a determination map including the relationship between the impedance characteristics of the bearing and the fatigue level or remaining life of the bearing; a measurement switching unit that switches between a measurement execution state and a measurement non-execution state based on the state of the measurement control signal; a data storage unit that stores the measurement signals in the measurement execution state; an impedance characteristics calculation unit that calculates the impedance characteristics of the bearing based on the stored measurement signals; and a determination unit that determines the fatigue level or remaining life of the bearing based on the impedance characteristics of the bearing and the determination map, wherein the probe comprises: a substantially columnar probe body that abuts on a measurement target surface of the bearing to detect the impedance of the bearing; A determination device comprising: a housing having a sliding hole extending in the axial direction therein, the housing accommodating the probe main body arranged in the sliding hole so as to be slidable in the axial direction; an abutment portion provided at a tip end of the housing and capable of abutting against the measurement target surface of the bearing; and a biasing spring arranged in the sliding hole of the housing and biasing the probe main body in the axial direction relative to the housing, wherein the abutment portion has four protrusions protruding in the axial direction, and the four protrusions are respectively located at vertices of a rectangle centered on the central axis of the probe main body as viewed in the axial direction. (2) The determination device according to (1), wherein the abutment portion has a rectangular shape as viewed in the axial direction, and the four protrusions are located at vertices of the rectangle of the abutment portion. (3) The determination device according to (1), wherein the abutment portion has a circular shape as viewed in the axial direction. (4) The determination device according to any one of (1) to (3), wherein the shape of the tip end surface of the protrusion is rectangular as viewed in the axial direction.(5) The determination device according to any one of (1) to (3), wherein the tip surface of the protrusion has a circular shape when viewed in the axial direction. (6) The determination device according to any one of (1) to (5), wherein the protrusion is a pin separate from the abutting portion and is fixed to the abutting portion. (7) The determination device according to any one of (1) to (6), wherein the probe main body separately comprises: a probe portion having a coil; and a holder portion that houses the probe portion therein and is slidable relative to the sliding hole of the housing. (8) The determination device according to (7), wherein the biasing spring is a coil spring, and the coil spring biases the holder portion of the probe main body. (9) The determination device according to (8), wherein the probe main body includes a cable for extracting the measurement signal, and the cable passes through an inner diameter side of the coil spring.

[0056] This application is based on a Japanese patent application (Patent Application No. 2024-023325) filed on February 20, 2024, the contents of which are incorporated herein by reference.

[0057] 1 Determination device 10 Probe 11 Probe body 13 Housing 13a Base 13b Tip 13c Step 13d Outer circumferential surface 13e Long hole 14 Slide hole 14a Tip opening 14b Base opening 15 Abutment 17 Coil spring (biasing spring) 21 Probe part 22 Holder part 22a Female thread hole 24 Pin 25 Cable 26 Protrusion 26a Tip surface 26b Outer corner 26c Inner corner 26d Circumferential outer side 26e Circumferential inner side 30 Switch 40 Input part 50 Fatigue determination part 51 Map storage part 53 Measurement switching part 55 Data storage part 57 Impedance characteristic calculation part 58 Display part 59 Determination part 60 Outer ring (bearing) 61 Raceway surface (surface to be measured) 70 Inner ring (bearing) 71 Raceway surface (surface to be measured) O1 Central axis of probe body O2 Central axis of outer ring O3 Central axis of inner ring O4 Normal direction of contact angle O5 Contact angle direction

Claims

1. A determination device comprising: a probe that applies an AC magnetic field to induce eddy currents in a bearing and detects the impedance of the bearing; a switch that transmits a measurement control signal that switches between starting and stopping the acquisition of a measurement signal of the impedance detected by the probe; and a fatigue determination unit that determines the fatigue level or remaining life of the bearing based on the impedance of the bearing, wherein the fatigue determination unit comprises: a map storage unit that stores a determination map including the relationship between the impedance characteristics of the bearing and the fatigue level or remaining life of the bearing; a measurement switching unit that switches between a measurement execution state and a measurement non-execution state based on the state of the measurement control signal; a data retention unit that retains the measurement signals in the measurement execution state; an impedance characteristic calculation unit that calculates the impedance characteristics of the bearing based on the retained measurement signals; and a determination unit that determines the fatigue level or remaining life of the bearing based on the impedance characteristics of the bearing and the determination map, wherein the probe comprises: a substantially columnar probe body that abuts on the measurement target surface of the bearing to detect the impedance of the bearing; a housing having a sliding hole extending in the axial direction therein, the housing accommodating the probe body arranged in the sliding hole so that the probe body can slide in the axial direction; an abutment portion provided at the tip of the housing and capable of abutting against the measurement target surface of the bearing; and a biasing spring arranged in the sliding hole of the housing and biasing the probe body in the axial direction relative to the housing, wherein the abutment portion has four protrusions protruding in the axial direction, and when viewed from the axial direction, the four protrusions are respectively located at the vertices of a rectangle centered on the central axis of the probe body.

2. The determination device according to claim 1, wherein the abutment portion has a rectangular shape when viewed in the axial direction, and the four protrusions are arranged at the vertices of the rectangle of the abutment portion.

3. The determination device according to claim 1, wherein the shape of the abutment portion is circular when viewed in the axial direction.

4. The determination device according to claim 1, wherein the tip surface of the protrusion has a rectangular shape when viewed in the axial direction.

5. The determination device according to claim 1, wherein the tip surface of the protrusion has a circular shape when viewed in the axial direction.

6. The determination device according to claim 1, wherein the protrusion is a pin separate from the abutment portion and fixed to the abutment portion.

7. The determination device according to claim 1, wherein the probe main body comprises a probe portion having a coil and a holder portion that stores the probe portion therein and is slidable relative to the sliding hole of the housing, as separate parts.

8. The determination device according to claim 7, wherein the biasing spring is a coil spring, and the coil spring biases the holder portion of the probe main body.

9. The determination device according to claim 8, wherein the probe body includes a cable for extracting the measurement signal, and the cable passes through the inner diameter side of the coil spring.

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