JP4030108B2 - Wear amount measuring method, cutting amount measuring method, wear amount measuring sensor, cutting amount measuring sensor, wear amount measuring device, cutting amount measuring device, bearing and wear amount measuring sensor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a measuring method, a measuring sensor, a measuring device, and an apparatus including a measuring sensor for measuring a wear amount of a bearing or the like or a cutting amount of a workpiece.
[0002]
[Prior art]
In recent years, equipment diagnostic techniques have been developed and put into practical use in various industrial fields, and various diagnostic techniques and systems related to pumps have been proposed.
[0003]
There is a vertical pump as a pump used in a plant, for example, a power plant. This vertical pump is a large-sized machine that is used for intake or pumping of seawater, and its importance is high. Such a vertical pump has a vertically long structure as a whole, a driving motor is disposed on the upper part of the pump, and an input shaft (rotary shaft) of the pump and an output shaft of the driving motor are connected by a coupling. Yes.
[0004]
The fluid in the pump is discharged by an impeller that is rotated by a drive motor. Generally, a mechanical seal or a gland packing is used to prevent the pressurized fluid in the pump from leaking from the rotating shaft. ing.
[0005]
In the pump, a rotating shaft is supported by a slide bearing designed to be used in a fluid lubrication region. Most of the plain bearings are often used as bearings for high loads, high speed ranges, and large devices.
[0006]
Most of the failure or maintenance points of such vertical pumps are concentrated on the bearings and shaft seals that are in contact with the rotating body and require periodic replacement and daily inspection according to the service life. Has been.
[0007]
Various systems have been proposed to monitor the operation status of vertical pumps and diagnose pump abnormalities. One example is the measurement and monitoring of vibrations near the pump bearings during pump operation. Some bearing wear amounts are estimated from vibration analysis. This is based on the fact that if vibration is generated on the rotary shaft of the pump, the bearing will wear, and if the amount of wear increases, the vibration amplitude of the rotary shaft increases. The amount is estimated.
[0008]
[Problems to be solved by the invention]
However, in the method of estimating the wear amount of the vertical pump bearing by measuring the vibration amplitude of such a rotating system, the pump has a gland packing or the like for preventing leakage of pumped liquid as described above. Since the seal is provided between the pump casing and the rotating shaft, this brings about a great damping effect, and there is a problem that the vibration amplitude is also affected by the state of the gland packing and the difference in tightening.
[0009]
For this reason, the present situation is that the bearing is disassembled at the periodic inspection of the pump to observe the wear of the bearing and measure the amount of wear of the bearing.
[0010]
In particular, it is difficult for inspectors to easily approach for inspection, etc., and the friction amount of the inner wall surface of the pipe in a system for transporting powder such as coal or bearings in equipment that requires labor such as disassembly or the like. It has been desired to have high reliability and to measure in real time even during operation.
[0011]
The object of the present invention is made in view of such a conventional problem, and is a measurement method capable of measuring in real time during operation, etc. with high reliability the amount of wear in a pipe or the like in a bearing or pipe transportation system. An object of the present invention is to provide a measurement sensor, a measurement device, a bearing, and a device including the measurement sensor.
[0012]
Further, the other object of the present invention is not limited to wear of the object to be measured, but includes a measuring method, a measuring sensor, a measuring device, a bearing, and a measuring sensor capable of measuring in real time during cutting in cutting and the like. The device is to be provided.
[0013]
[Means for Solving the Problems]
According to a first aspect of the present invention, an eddy current is generated by an eddy current sensor with respect to a dummy measurement body made of an electromagnetic derivative whose surface area is reduced by being worn integrally with a measurement object. This is a wear amount measuring method for measuring the wear amount of the measurement object in accordance with the change in output of the eddy current sensor in accordance with the decrease in the area of the dummy measurement body.
[0014]
According to a second aspect of the present invention, as described in claim 2, an eddy current is generated by an eddy current sensor for a dummy measurement body made of an electromagnetic derivative whose surface area is reduced by being cut integrally with a measurement object, The cutting amount measuring method measures the cutting amount of the measurement object according to the output change of the eddy current sensor according to the decrease in the area of the dummy measuring body.
[0015]
According to a third aspect of the present invention, the eddy current sensor includes: an eddy current sensor; and a dummy measuring body made of an electromagnetic derivative that generates an eddy current by a magnetic field generated by the eddy current sensor. The dummy measurement body is held at a fixed position with respect to the sensor, the area is reduced by wearing the dummy measurement body integrally with the measurement object, and the area of the dummy measurement body is reduced from the eddy current sensor. The wear amount measuring sensor is characterized by outputting a signal.
[0016]
According to a fourth aspect of the present invention, the eddy current sensor includes a eddy current sensor and a dummy measuring body made of an electromagnetic derivative that generates an eddy current by a magnetic field generated by the eddy current sensor. The dummy measurement body is held in a fixed position with respect to the sensor, the area is reduced by cutting the dummy measurement body integrally with the measurement object, and the area of the dummy measurement body is reduced from the eddy current sensor. A cutting amount measuring sensor is characterized by outputting a signal.
[0017]
According to a fifth aspect of the present invention, as described in the fifth aspect, in the third aspect described above, the dummy measurement body is inclined with respect to the wear surface of the measurement object.
[0018]
According to a sixth aspect of the present invention, as described in the sixth aspect, in the fourth aspect described above, the dummy measuring body is inclined with respect to the cutting surface of the measurement object.
[0019]
According to a seventh aspect, as described in the seventh aspect, the wear amount measurement sensor according to the third or fifth aspect described above and the wear amount data corresponding to the output of the dummy measurement body are stored in advance. A wear amount of the object to be measured based on the output from the wear amount measurement sensor and the data stored in advance. This is a measuring device.
[0020]
According to an eighth aspect, as described in the eighth aspect, the cutting amount measurement sensor according to the fourth or sixth aspect described above and cutting amount data corresponding to the output of the dummy measuring body are stored in advance. A processing amount, and the processing device calculates a cutting amount of a measurement object based on an output from the cutting amount measuring sensor and the previously stored data. This is a measuring device.
[0021]
According to a ninth aspect of the present invention, in the bearing in which the rotating shaft is pivotally supported by the bearing member, the wear amount measuring sensor according to the third or fifth aspect described above is provided, and the measurement object is provided. The dummy measuring body of the wear amount measuring sensor is provided on the bearing member using an object as the bearing member.
[0022]
A tenth aspect of the invention includes a bearing according to the ninth aspect of the invention, a rotary shaft that is pivotally supported by the bearing, and a driven body that is rotated by the rotary shaft. This is an apparatus provided with a wear amount measuring sensor.
[0023]
According to an eleventh aspect of the present invention, as set forth in the eleventh aspect, in the tenth aspect described above, the device is a saddle type pump and the driven body is an impeller.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on embodiments shown in the drawings.
[0025]
FIG. 1 is a partially cutaway perspective view showing a schematic configuration of a saddle-type pump showing a first embodiment of the present invention and an enlarged view of a bearing portion.
[0026]
A vertical pump 1 shown in FIG. 1 has a rotary shaft 3 arranged in a pump casing 2 extending in the vertical direction supported rotatably by a bearing 4 and is below the bearing 4 arranged in the lower part of the pump. An impeller 5 is attached to the lower end portion of the extending rotating shaft 3. A motor 6 is attached to the upper part of the pump 1, and the impeller 5 is rotated by the rotational power of the motor 6, and the liquid is pumped up through the casing 2. In such a saddle type pump 1, since the bearing 4 is in a state of being submerged in the liquid, in order to measure the wear amount of the bearing 4 as in the prior art, the motor 6 and the pump 1 are separated by pulling up the pump. It was necessary to disassemble the pump 1 and further disassemble the bearing 4.
[0027]
However, in this embodiment, a wear amount measuring sensor 7 for measuring the wear amount is attached to the bearing 4 which is a slide bearing.
[0028]
As shown in the enlarged view of FIG. 1, the plain bearing 4 in the present embodiment has a structure in which a cylindrical bush 9 is attached to an inner peripheral portion of a casing 8 made of, for example, a stainless casting, and the bush 9 has a cylindrical shape. A plurality of bearing members 11 made of fluororesin such as Teflon (registered trademark) formed in a rectangular parallelepiped extending in the axial direction are fixed to the inner peripheral portion of the rubber member 10 in the circumferential direction, and the rotating shaft 3 is secured by these bearing members 11. Is supported. Then, due to the rotation of the rotating shaft 3, the surfaces of the plurality of bearing members 11 that are in frictional contact with the rotating shaft 3 are worn, and as the wear progresses, the thickness of the bearing member 11 decreases.
[0029]
The wear amount measuring sensor 7 includes an eddy current sensor 12, an electromagnetic derivative (hereinafter referred to as a dummy measuring body) 13 such as a metal or a non-ferrous metal disposed so as to cross obliquely with respect to the magnetic field generated by the eddy current sensor 12. Is the basic configuration. The dummy measurement body 13 is formed of, for example, aluminum foil, and the dummy measurement body 13 made of aluminum foil is embedded in a fluororesin that is the same resin material as the bearing member 11.
[0030]
In this embodiment, an embedded body 14 formed by embedding a dummy measuring body 13 in a fluororesin in a cylindrical shape is embedded in one of the plurality of bearing members 11, and the embedded body is the same as the bearing member 11. 14 also wears, and at that time, the wear starts from the tip end side (rotating shaft side) where the dummy measurement body 13 in the embedded body 14 is also inclined, and the surface area gradually decreases.
[0031]
On the other hand, the eddy current sensor 12 is screwed into an attachment hole 15 that penetrates the casing 8 corresponding to the embedded body 14. The thickness of the embedded body 14 is set to a thickness until it comes into contact with the front surface of the eddy current sensor 12, and the outer end surface of the embedded body 14 penetrates the rubber member 10 and the front end of the eddy current sensor 12 in the mounting hole 15 of the casing 8. The distance between the embedded body 14 and the eddy current sensor 12 is prevented from changing by contacting the surface. Since the eddy current sensor 12 is screwed to the casing 8, the distance between the embedded body 14 and the eddy current sensor 12 can be kept constant by fixing the embedded body 14 to the bush 9 or the casing 8. it can.
[0032]
The eddy current sensor 12 is generally called an eddy current displacement sensor, and an LC resonance circuit is formed by the inductance L of the coil of the sensor unit and the capacitor C of the conversion unit, and this LC resonance circuit is brought into a resonance state by a crystal oscillator, for example. When used as a displacement sensor, when an electromagnetic derivative (measuring object) such as a metal to be measured is brought close to a sensor part comprising the coil through which a high-frequency current is passed, the object to be measured is measured by an alternating magnetic field generated by the coil Eddy current flows in the object. Since the strength of the eddy current depends on the strength of the magnetic field lines that reach, that is, the distance (gap) between the coil and the object to be measured, the inductance L changes depending on the strength of the eddy current. As a result, a change occurs in the terminal voltage of the resonance circuit, and the change is a function of distance, so that the gap can be obtained based on this terminal voltage. Thus, since this sensor was used to measure the gap to the object to be measured, it is called an eddy current displacement sensor. However, in the present invention, it does not measure the gap to the object to be measured. This is simply called an eddy current sensor.
[0033]
Here, since the terminal voltage of the eddy current displacement sensor decreases as the object to be measured approaches, the sensor output P is set to the distance d between the sensor and the object to be measured by correcting the linearity by the linearize circuit. It is directly proportional and is represented by the formula (1).
[0034]
P = k ₁ d (1)
However, k ₁ represents a sensor sensitivity is a constant determined by the type of electromagnetic derivative to be measured.
[0035]
In the eddy current displacement sensor used as the gap sensor of the present invention, as shown in FIG. 2, the sensor output P may be influenced by the size of the area S of the electromagnetic derivative that intersects the magnetic field. It was made paying attention to the point. In this case, Equation (1) can be rewritten as Equation (2) below.
[0036]
P = P ′ {1 + k ₂ f (S / S ₀ )} (2)
However, P'formula (1), S ₀ represents the range in which all the magnetic field lines intersect the dummy measurement object, K ₂ is a function _{f (S / S 0),} 0 ≦ f (S / S 0) ≦ 1, and so as to for, that is a constant for normalizing the function f (S / S _0). The sign before the function f (S / S ₀ ) in equation (2) is a plus sign for decreasing (increasing) the sensor output as the eddy current generated in the dummy measurement body increases (decreases). is there.
[0037]
Further, when S≈S ₀ , all the magnetic fields intersect with the dummy measurement body, the maximum eddy current is generated, and the sensor output is minimized. In other words, the function f (S / S ₀ ) becomes 0 when f (1), resulting in the expression (1).
[0038]
However, as shown in FIG. 2A, when the area of the dummy measurement body decreases from S0 to S, f (S / S ₀ ) increases and finally f (0) = 1. Such a state can be simulated by horizontally moving the dummy measurement body as shown in FIG. This indicates that even if the distance between the sensor and the dummy measurement body is kept constant, the change can be measured if the size of the dummy measurement body changes.
[0039]
That is, in the present invention, for example, the amount of wear of the bearing member 11 can be directly measured by the eddy current sensor 12 due to the reduction in the size of the dummy measurement body.
[0040]
Therefore, in the present embodiment, the rotating shaft 3 is tangent to the bearing member 11 so that the area of the dummy measuring body 13 formed of aluminum foil is reduced by the rotating shaft 3 in accordance with the wear of the bearing member 11. On the other hand, the dummy measuring body 13 is disposed with an inclination angle of θ, and the magnetic field is disposed across the eddy current sensor 12 diagonally. Then, a decrease in the area of the dummy measurement body 13 is detected by the eddy current sensor 12, and the detection output is transmitted to a monitoring device (not shown) which is an arithmetic processing unit to determine the amount of wear of the bearing.
[0041]
FIG. 3 shows the relationship between the dummy measurement body 13 and the eddy current sensor 12 formed of an aluminum foil having a width W, and the relationship between the wear region of the bearing member 11 and the dummy measurement body 13. The calculation of the output P of the eddy current sensor will be described on the assumption that the inclined rear end of the dummy measurement body 13 inclined with respect to the eddy current sensor 12 extends to the front end of the eddy current sensor 12.
[0042]
In FIG. 3, the output P of the eddy current sensor 12 is a function of the distance d and the area S of the dummy measurement body 13, and therefore is expressed by Expression (3).
[0043]
P = P ′ {1 + k ₃ g (d _max , S / S ₀ )}
However, d _max is a maximum value of the distance d, and k3 is a constant for normalization so that 0 ≦ g (d _max , S / S ₀ ) ≦ 1.
[0044]
d _max decreases in direct proportion to the decrease in the effective area S of the dummy measurement body 13,
Further, since there is a relationship of S = Wd _max / sin θ, the above equation (3) can be simplified as the following equation (4).
[0045]
P = g (D-d _max ) (4)
Here, D is as can be seen from Figure 3, the distance between the dummy measurement object 13 and the eddy current sensor 12 when setting the dummy measurement object 13 in the first (when no wear), namely of d _max It is the maximum value. Therefore, D-d _max indicates the amount of wear of the bearing member 11 and is obtained from the above-described equation (4).
[0046]
The function g (D-d _max ) is experimentally obtained in advance, stored in the monitoring device, and used as a calibration curve for the bearing wear amount.
[0047]
Therefore, the wear amount measuring sensor 7 in the present embodiment is configured so that the wear amount that the bearing member 11 of the bearing 4 wears due to friction with the rotating shaft 3 during the operation of the saddle type pump is measured by the dummy measuring body 13 made of aluminum foil. The eddy current sensor 12 measures the decrease in the area, and the sensor output from the eddy current sensor 12 is calibrated with the function g (D-d _max ) obtained in advance by the monitoring device. The amount of wear of the member 11 can be measured in real time.
[0048]
Example 1
Regarding the relationship between the tilt angle θ of the dummy measurement body 13 and the output of the eddy current sensor 12, the tilt angles θ are A: 18.6 degrees, B: 15.6 degrees, and C: 12.6 degrees, as shown in FIG. , Θ is attached to a wedge-shaped polyester plate 16 having an angle of θ, and is pressed against a rotating grindstone 18 that is integrated with the eddy current sensor 12 to gradually move from the tip of the aluminum foil 17. The amount of movement of the eddy current sensor 12 at that time (corresponding to the wear amount and corresponding to the D-d _max ) was measured with a laser displacement meter 19. The relationship between the output of the eddy current sensor 12 and the amount of wear at this time is shown in FIG.
[0049]
The characteristic curves of A to C at these three angles are similar although there is a slight variation in sensitivity. Similar results were obtained even when the angle θ was 20 degrees or more.
[0050]
Therefore, the angle θ is determined by the measurement distance of the eddy current sensor 12, the bearing wear amount, and the like. For example, when the wear amount is large, the angle θ may be increased.
[0051]
As described above, according to the present embodiment, the embedded member 14 is provided in the bearing member 11 of the bearing 4 of the vertical pump 1, and the dummy measuring member 13 made of aluminum foil, which is an electromagnetic derivative embedded in the embedded member 14. The bearing member 11 is inclined with respect to the tangent to the outer peripheral surface of the rotary shaft 3, and the dummy measuring body 13 is worn away from the front end side along with the wear of the bearing member 11 by the rotating shaft 3. 13, the eddy current sensor 12 detects a decrease in the surface area of the dummy measurement body 13 as an increase in output, so that the relationship between the wear amount and the surface area of the dummy measurement body 13 and the eddy current sensor 12 at that time are detected in advance. Is obtained, the amount of wear of the friction member 11 of the bearing 4 during operation of the pump can be measured in real time.
[0052]
Further, the coil portion of the eddy current sensor 12 faces the rotating shaft 3, but a dummy made of aluminum foil, which is an electromagnetic derivative, is interposed between the eddy current sensor 12 and, for example, a stainless steel rotating shaft 3, which is an electromagnetic derivative. Since the measuring body 13 is interposed, the dummy measuring body 13 acts as a shield member with respect to the rotating shaft 3, and particularly when the dummy measuring body 13 is new, the magnetic field exerted on the rotating shaft 3 is completely shielded. Therefore, since no eddy current is generated by the eddy current sensor 12 on the rotating shaft 3, the rotating shaft 3 is not affected by the vibration of the rotating shaft 3. However, as shown in FIG. 5, eddy current is generated in the rotating shaft 3 due to the magnetic field of the eddy current sensor 12 due to wear of the dummy measurement body 13, so that the eddy current sensor 12 is affected by the eddy current formed on the rotating shaft 3. Receive. Due to the eddy current formed on the rotating shaft 3, the sensor output of the eddy current sensor 12 periodically decreases. This periodic decrease depends on the constant frequency f of the shaft vibration caused by the rotation of the rotating shaft 3. In contrast, the output signal of the eddy current sensor 12 corresponding to the wear of the bearing is a change in units of days, months, and years. Compared with the change caused by vibration, it is considered to be a constant DC change. Therefore, the influence of the eddy current generated on the rotating shaft 3 is affected by, for example, smoothing processing such as averaging over a digital number of 10 Hz (frequency of shaft vibration of the rotating shaft) or an analog low-pass filter (frequency f Ignoring the signal in the vicinity), the signal corresponding to the wear amount of the bearing can be taken out to measure the wear amount of the bearing.
Other Embodiments In the above-described embodiment, the amount of wear of the bearing member of the slide bearing that supports the rotary shaft of the vertical pump is measured. It is not limited to measuring the amount of wear of a member. In a transportation system for transferring steam, gas turbine bearings, engine crankshaft bearings, powders such as coal, etc., pipe inner wall It can also be applied to the measurement of the amount of wear or the measurement of the amount of cutting when the workpiece is cut in cutting or the like.
[0053]
In the transport system for transferring powder such as coal through the pipe, when measuring the wear amount of the inner wall of the pipe, the wear amount measurement sensor is composed of the embedded body 14 and the eddy current sensor 12 as in the above-described embodiment. The embedded body 14 is attached to a through-hole portion formed in the peripheral wall of the pipe, and the eddy current sensor 12 is attached to the outside thereof. The buried body 14 may be made of a resin that embeds an object to be measured made of aluminum foil and is made of a material that wears under the same conditions as the inner wall of the pipe. In particular, a lining member is provided on the inner wall surface of the pipe body. For example, the same material as that of the lining member may be used.
[0054]
Further, when measuring the amount of cutting when cutting a workpiece in cutting or the like, a measurement sensor (in this case) configured by integrating the embedded body 14 and the eddy current sensor 12 at the end of the workpiece. A cutting amount measurement sensor) is fixed to, for example, an end of the workpiece by aligning the upper surface of the embedded body 14 with the upper surface of the workpiece.
[0055]
Then, when the upper surface of the workpiece is cut, the upper surface of the embedded body 14 is also cut, and the cutting amount measuring sensor can measure the cutting amount of the workpiece in the same manner as the measurement of the wear amount described above. At that time, a dummy measuring body such as an aluminum foil made of an electromagnetic derivative embedded in the embedded body 14 is inclined with respect to the cutting surface. An eddy current is formed in the dummy measurement body by the magnetic field from the current sensor 12, and the cutting amount of the dummy measurement body is measured based on the output of the eddy current sensor 12 according to the reduction of the area due to the cutting of the dummy measurement body. May be. In this case, since the cutting amount measuring sensor can be arranged at the end of the workpiece, the dummy measuring body is arranged at a right angle with respect to the cutting surface, and the eddy current sensor with respect to the dummy measuring body extending below the workpiece. 12 can be arranged at right angles or with an angle.
[0056]
Moreover, in the above-described embodiment, aluminum foil is used as the dummy measurement body, but metal foil made of electromagnetic derivatives made of other materials, such as platinum, titanium, etc., can be used, and particularly excellent in corrosion resistance. If platinum, titanium, or the like is used for the pump bearing of the above embodiment, the life of the dummy measuring body can be extended, and as a result, the life of the sensor can be extended.
[0057]
【The invention's effect】
As described above, according to the measurement method of the present invention, the amount of wear or the amount of cutting can be measured in real time, for example, the amount of wear under conditions that are difficult to measure visually or directly from the outside. Enable measurement.
[0058]
Further, according to the measurement sensor of the present invention, it can be constituted by an eddy current sensor and a dummy measurement body, and the arrangement of the eddy current sensor, the dummy measurement body and the measurement object is appropriately set, for example, the measurement object If the area of the dummy measurement body is reduced according to wear, the output of the eddy current sensor becomes a value corresponding to the area of the dummy measurement body that decreases due to wear, and the wear amount (cutting amount) can be obtained. It becomes.
[0059]
According to the measuring device of the present invention, the wear amount and the cutting amount are calculated from the output from the measurement sensor based on the relationship between the wear amount (cutting amount) stored in advance in a memory and the eddy current sensor output. Can do.
[0060]
According to the bearing of the present invention, the wear amount measuring sensor can be configured to have no movable part such as a dummy measuring body such as an aluminum foil made of an eddy current sensor and an electromagnetic derivative. In addition, it is possible to measure in real time the amount of wear of the bearing member in a bearing of a device that is troublesome to repair.
[0061]
Especially when applied to bearings that are always submerged in water, such as bearings for rotary shafts that rotate the impellers of vertical pumps, the wear amount measurement sensor always measures wear amounts with high reliability. can do.
[Brief description of the drawings]
FIG. 1 is a partially cutaway perspective view showing a schematic configuration of a saddle type pump showing a first embodiment of the present invention and an enlarged view of a bearing portion.
FIG. 2 is a diagram showing the relationship between the decrease in the area of the object to be measured and the magnetic field of the eddy current sensor.
FIG. 3 is a diagram showing the relationship between the amount of wear and the area change.
FIG. 4 is a diagram showing a relationship between an amount of wear and a sensor output according to an inclination angle.
FIG. 5 is a chart showing sensor output including the influence of a rotation axis.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vertical pump 2 Pump casing 3 Rotating shaft 4 Bearing 5 Impeller 6 Motor 7 Wear amount measuring sensor 8 Casing 9 Bush 10 Rubber 11 Bearing member 12 Eddy current sensor 13 Dummy measuring body 14 Embedded body 15 Mounting hole 16 Polyester plate 17 Aluminum Foil 18 Whetstone

Claims (11)

An eddy current is generated by an eddy current sensor with respect to a dummy measurement body made of an electromagnetic derivative whose surface area is reduced by being worn integrally with the measurement object, and the eddy current sensor corresponding to the decrease in the area of the dummy measurement body A wear amount measuring method for measuring the wear amount of the measurement object in accordance with a change in output. An eddy current is generated by an eddy current sensor with respect to a dummy measurement body made of an electromagnetic derivative whose surface area is reduced by being cut integrally with the measurement object, and the eddy current sensor according to the decrease in the area of the dummy measurement body A cutting amount measuring method for measuring a cutting amount of the measurement object in accordance with a change in output. An eddy current sensor and a dummy measuring body made of an electromagnetic derivative that generates eddy current by a magnetic field generated by the eddy current sensor, and holds the dummy measuring body at a fixed position with respect to the eddy current sensor; A wear amount measuring sensor, wherein the dummy measuring body is worn integrally with a measurement object to reduce the area, and the eddy current sensor outputs a signal corresponding to the area reduction of the dummy measuring body. An eddy current sensor and a dummy measuring body made of an electromagnetic derivative that generates eddy current by a magnetic field generated by the eddy current sensor, and holds the dummy measuring body at a fixed position with respect to the eddy current sensor; A cutting amount measuring sensor, wherein the dummy measuring body is cut integrally with a measurement object to reduce the area, and the eddy current sensor outputs a signal corresponding to the area reduction of the dummy measuring body. The wear amount measuring sensor according to claim 3, wherein the dummy measurement body is inclined with respect to a wear surface of the measurement object. The sensor for cutting amount measurement according to claim 4, wherein the dummy measuring body is inclined with respect to a cutting surface of the measurement object. The wear amount measurement sensor according to claim 3 or 5, and a processing device in which wear amount data corresponding to the output of the dummy measurement body is stored in advance, wherein the processing device is used for the wear amount measurement. A wear amount measuring apparatus for calculating a wear amount of an object to be measured based on an output from a sensor and the previously stored data. The cutting amount measurement sensor according to claim 4 or 6, and a processing device in which cutting amount data corresponding to the output of the dummy measuring body is stored in advance, and the processing device is used for the cutting amount measurement. A cutting amount measuring apparatus that calculates a cutting amount of an object to be measured based on an output from a sensor and the data stored in advance. A bearing for supporting a rotating shaft by a bearing member, the wear amount measuring sensor according to claim 3 or 5, wherein the measurement object is the bearing member, and the dummy measuring body of the wear amount measuring sensor is used. A bearing provided on the bearing member. An apparatus provided with a wear amount measuring sensor, comprising the bearing according to claim 9, a rotating shaft supported by the bearing, and a driven body rotated by the rotating shaft. 11. The apparatus with a wear amount measuring sensor according to claim 10, wherein the apparatus is a saddle type pump and the driven body is an impeller.

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