WO2021085156A1 - Wire rope flaw detection device - Google Patents

Abstract

This wire rope flaw detection device comprises a magnetizer, magnetic sensor, and control unit. The magnetizer generates magnetic flux that passes through a portion of a wire rope. The magnetic sensor generates, as a sensor signal, a signal corresponding to leakage magnetic flux that is the magnetic flux that has leaked from the wire rope. The control unit includes a filter unit and processing unit. The control unit processes the sensor signal. The filter unit extracts frequency components of the sensor signal. The processing unit determines whether there is a flaw in a wire in the wire rope on the basis of the distribution of the frequency components extracted by the filter unit.

Description

Wire rope flaw detector

The present invention relates to a wire rope flaw detector.

Conventionally, a wire rope flaw detector having a magnetizer that magnetically saturates the wire rope and a magnetic sensor that detects a leakage magnetic flux leaking from the wire rope due to a damaged portion of the wire rope is known (for example, Patent Document). 1).

Japanese Unexamined Patent Publication No. 09-210966

The amount of leakage magnetic flux leaking from the wire rope decreases as the wire rope becomes thinner. Therefore, in the conventional wire rope flaw detector shown in Patent Document 1, the thinner the wire rope, the smaller the amount of leakage magnetic flux reaching the magnetic sensor, and the lower the output of the magnetic sensor. As a result, the signal-to-noise ratio of the conventional wire rope flaw detector is reduced.

Further, in order to improve the SN ratio of the wire rope flaw detector, it is conceivable to shorten the distance between the wire rope and the magnetic sensor. However, the conventional wire rope flaw detector has restrictions such as assembly accuracy between the wire rope and the magnetic sensor. Therefore, in the conventional wire rope flaw detector, there is a limit in reducing the distance between the wire rope and the magnetic sensor.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a wire rope flaw detector capable of more reliably improving the SN ratio.

The wire rope flaw detector according to the present invention includes a magnetizer that generates a magnetic flux that passes through a part of the wire rope, and a magnetic sensor that generates a signal corresponding to the leakage magnetic flux leaking from the wire rope as a sensor signal. The control unit includes a control unit that processes the sensor signal, and the control unit includes a filter unit that extracts a frequency component of the sensor signal and a wire rope included in the wire rope based on the distribution of the frequency component. It has a processing unit for determining the presence or absence of damage.

According to the wire rope flaw detector according to the present invention, the SN ratio can be improved more reliably.

It is an exploded perspective view which shows the probe of the wire rope flaw detector according to Embodiment 1 of this invention. It is explanatory drawing which shows the flaw detection principle by the probe of FIG. It is an enlarged view of the part A of FIG. It is a figure explaining an example of the positional relationship between the leakage magnetic flux and a coil of FIG. 3 more concretely. It is a figure explaining more concretely an example of the positional relationship between a leakage magnetic flux leaking from a wire rope whose diameter is smaller than that of the wire rope of FIG. 4 and a coil. It is a block diagram which shows the functional structure example of the control part of FIG. It is a figure which shows an example of the frequency characteristic of the filter part of FIG. It is a figure which shows an example of the distribution of the frequency component extracted from the input signal by the filter part of FIG. It is a figure which shows an example of the sequence yk (n) generated by the filter part at the time t1 of FIG. It is a figure which shows an example of the sequence yk (n) generated by the filter part at the time t2 of FIG. It is a flowchart explaining the process by the control part of FIG. FIG. 5 is a block diagram showing a functional configuration example of a control unit that processes a signal corresponding to a leakage magnetic flux leaking from a wire rope according to a second embodiment of the present invention. It is a figure which shows an example of the frequency characteristic of the filter part of FIG. It is a figure which shows the waveform example of the time domain of the mother wavelet by the wavelet transform part of FIG. It is a figure which shows the waveform example of the frequency domain of the mother wavelet by the wavelet transform part of FIG. As another example of the frequency characteristics of the filter unit of FIG. 12, it is a conceptual diagram of the center frequency at the time of 1/3 octave. It is a figure which shows an example of the distribution of the frequency component extracted from the input signal by the filter part of FIG. It is a figure which shows an example of the sequence yk (n) generated by the filter part at the time t1 of FIG. It is a figure which shows an example of the sequence yk (n) generated by the filter part at the time t2 of FIG. It is a flowchart explaining the process by the control part of FIG. It is a figure explaining the hardware configuration example. It is a figure explaining another hardware configuration example. 21 is a diagram showing a system configuration example in which at least one of the control units of FIGS. 6 and 12 is incorporated into a terminal device and used as a specific example of FIG. 21 or FIG. As a specific example of FIG. 21 or FIG. 22, it is a figure which shows the system configuration example which supplies the processing content of the determination device to a data logger by incorporating at least one control part of FIG. 6 and FIG. As a specific example of FIG. 21 or FIG. 22, it is a figure which shows the system configuration example which supplies the processing content of the determination device to an elevator control panel by incorporating at least one control part of FIG. 6 and FIG.

Embodiment 1.
FIG. 1 is an exploded perspective view showing probe 1 of the wire rope flaw detector according to the first embodiment of the present invention. The probe 1 includes a probe main body 3 and a cover 5.

The cover 5 is made of a non-magnetic material. The cover 5 covers the probe body 3. As a result, the cover 5 protects the probe body 3. The cover 5 is provided with a groove 51. The cross section of the groove 51 is formed in a U shape. The groove portion 51 has a first end portion 51_1 and a second end portion 51_2.

The probe main body 3 includes a magnetizer 11 and a magnetic sensor 13.

The magnetizer 11 has a back yoke 111, a first permanent magnet 112_1, a second permanent magnet 112_2, a first pole piece 113_1, and a second pole piece 113_2.

The back yoke 111 is made of a ferromagnetic material. The back yoke 111 has a first yoke end portion 111_1, a second yoke end portion 111_2, and a yoke central portion 111_3. One end of the back yoke 111 in the longitudinal direction is a first yoke end 111_1. The other end of the back yoke 111 in the longitudinal direction is a second yoke end 111_2. The yoke central portion 111_3 is located between the first yoke end portion 111_1 and the second yoke end portion 111_2.

A first pole piece 113_1 is fixed to the first yoke end 111_1 via a first permanent magnet 112_1. A second pole piece 113_2 is fixed to the second yoke end 111_2 via a second permanent magnet 112_2. As a result, the first permanent magnet 112_1 and the second permanent magnet 112_2 are arranged apart from each other in the longitudinal direction of the back yoke 111. Further, the first pole piece 113_1 and the second pole piece 113_1 are arranged apart from each other in the longitudinal direction of the back yoke 111.

The first pole piece 113_1 is made of a ferromagnetic material. The first pole piece 113_1 is provided with a first pole piece groove 113_1. The cross section of the first pole piece groove portion 113_11 is formed in a U shape. The first pole piece groove portion 113_1 is fixed to the cover 5 at a position on the back side of the first end portion 51_1.

The second pole piece 113_2 is made of a ferromagnetic material. The second pole piece 113_2 is provided with a second pole piece groove 113_21. The cross section of the second pole piece groove portion 113_21 is formed in a U shape. The second pole piece groove portion 113_21 is fixed to the cover 5 at a position on the back side of the second end portion 51_2.

The first permanent magnet 112_1 is arranged between the first pole piece 113_1 and the first yoke end portion 111_1. The first permanent magnet 112_1 has one magnetic pole surface oriented toward the first pole piece 113_1 and the other magnetic pole surface directed toward the first yoke end 111_1. As the first permanent magnet 112_1, for example, a neodymium magnet is used. The first permanent magnet 112_1 generates a magnetomotive force.

The second permanent magnet 112_2 is arranged between the second pole piece 113_2 and the second yoke end 111_2. The second permanent magnet 112_2 is arranged with one magnetic pole surface facing the second yoke end 111_2 and the other magnetic pole surface facing the second pole piece 113_2. As the second permanent magnet 112_2, for example, a neodymium magnet is used. The second permanent magnet 112_2 generates a magnetomotive force.

The magnetic sensor 13 has a sensor body 13A and a mounting portion 13B.

The mounting portion 13B is mounted on the yoke central portion 111_3. The mounting portion 13B is made of a non-magnetic material.

The sensor body 13A is arranged between the first pole piece 113_1 and the second pole piece 113_2. The sensor body 13A has a base portion 132, a coil holder 133, a first coil 131_1, and a second coil 131_2.

The base portion 132 is attached to the attachment portion 13B. The coil holder 133 is attached to the base portion 132. The coil holder 133 is made of a ferromagnetic material. The first coil 131_1 and the second coil 131_2 are attached to the coil holder 133.

FIG. 2 is an explanatory diagram showing the flaw detection principle by the probe 1 of FIG. The wire rope flaw detector includes a probe 1 and a control unit 9 that receives a signal from the probe 1.

In FIG. 2, for convenience of illustration, the outline of the cover 5 is shown by a chain double-dashed line. Further, in FIG. 2, for convenience of illustration, the cross-sectional shape portion of the groove portion 51 is shown by hatching. When the wire rope flaw detection device performs a flaw detection inspection of the wire rope 2, the wire rope 2 moves with respect to the probe 1 in a specific direction W_D along the longitudinal direction of the groove 51. The probe 1 performs measurement while bringing the wire rope 2 into contact with the groove 51.

In the example of FIG. 2, the direction of the polarity of the first permanent magnet 112_1 is the direction from the first yoke end 111_1 to the first pole piece 113_1. Further, in the example of FIG. 2, the polarity direction of the second permanent magnet 112_2 is the direction from the second pole piece 113_2 toward the second yoke end portion 111_2.

That is, the polarity of the first permanent magnet 112_1 is opposite to the polarity of the second permanent magnet 112_2. Therefore, in the state where the wire rope 2 is arranged in the groove 51, the magnetic flux F passing through the magnetic circuit F_C composed of a part of the wire rope 2 and the magnetizer 11 is transferred to the first permanent magnet 112_1 and the second permanent magnet. 112_2 occurs.

As a result, when the wire rope 2 is arranged in the groove 51, the section W between the portion of the wire rope 2 facing the first pole piece 113_1 and the portion facing the second pole piece 113_2 The wire rope 2 is magnetized at. In the wire rope 2, the magnetic flux F generated by the first permanent magnet 112_1 and the second permanent magnet 112_2 passes along the longitudinal direction of the wire rope 2. That is, the magnetizer 11 generates a magnetic flux F that passes through a part of the wire rope 2.

The magnetic sensor 13 generates a signal corresponding to the leakage magnetic flux L_F leaking from the wire rope 2 among the magnetic flux F as a sensor signal. The control unit 9 processes the sensor signal generated from the magnetic sensor 13. The details of the magnetic flux F and the leakage magnetic flux L_F will be described later.

Hereinafter, when the first permanent magnet 112_1 and the second permanent magnet 112_2 are collectively referred to, they are referred to as the permanent magnet 112. Further, when the first pole piece 113_1 and the second pole piece 113_2 are collectively referred to, they are referred to as the pole piece 113. Further, when the first coil 131_1 and the second coil 131_2 are collectively referred to, they are referred to as a coil 131.

Next, the detection principle of the leakage magnetic flux L_F by the wire rope flaw detector will be specifically described. FIG. 3 is an enlarged view of part A of FIG. As shown in FIG. 3, if there is a damaged portion B_W in the portion of the wire rope 2 through which the magnetic flux F passes, a part of the magnetic flux F leaks from the wire rope 2 as a leakage magnetic flux L_F around the damaged portion B_W. ..

FIG. 4 is a diagram for more specifically explaining an example of the positional relationship between the leakage magnetic flux L_F of FIG. 3 and the coil 131. When the wire rope 2 is moved with respect to the probe 1, the first coil 131_1 and the second coil 131_2 are interlinked with the leakage magnetic flux L_F. Therefore, an induced voltage, which is a signal corresponding to the leakage magnetic flux L_F, is generated in the first coil 131_1 and the second coil 131_2 as sensor signals.

By the way, the wire rope 2 is composed of a core rope and a plurality of strands 21 twisted around the core rope at a constant pitch λ. Therefore, on the outer peripheral portion of the wire rope 2, a plurality of convex portions arranged in the length direction of the wire rope 2 are formed at a constant pitch λ. Further, the strand 21 is formed by twisting a plurality of strands into a single layer or multiple layers. Therefore, if the wire contained in the wire rope 2 is thin, the diameter of the wire rope 2 is reduced.

FIG. 5 is a diagram for more specifically explaining an example of the positional relationship between the leakage magnetic flux L_F leaking from the wire rope 2S having a diameter smaller than that of the wire rope 2 of FIG. 4 and the coil 131. As shown in FIG. 5, when the wire rope 2S having a diameter smaller than that of the wire rope 2 of FIG. 4 moves with respect to the probe 1, the wire rope 2 of FIG. 4 moves with respect to the probe 1 as compared with the case of moving with respect to the probe 1. The amount of leakage magnetic flux L_F interlinking with the first coil 131_1 and the second coil 131_2 is reduced. Therefore, it is difficult for the control unit 9 of FIG. 2 to distinguish whether the sensor signal generated from the magnetic sensor 13 is due to the magnetic flux F due to noise or the magnetic flux F due to the damaged portion B_W. Therefore, in the present embodiment, the control unit 9 of FIG. 2 determines whether or not the wire rope included in the wire rope 2S is damaged based on the distribution of the frequency component of the sensor signal.

As described above, the wire rope 2 is composed of strands 21 twisted at a constant pitch λ. Therefore, the probe 1 detects noise caused by the outer peripheral portion of the wire rope 2 at least every pitch λ. Further, the wire rope 2S is also configured by being twisted at a pitch λS in the same manner. Therefore, a plurality of convex portions arranged in the length direction of the wire rope 2S are similarly formed on the outer peripheral portion of the wire rope 2S at a constant pitch λS. Therefore, the probe 1 detects noise caused by the outer peripheral portion of the wire rope 2S at least for each pitch λS.

FIG. 6 is a block diagram showing a functional configuration example of the control unit 9 of FIG. As shown in FIG. 6, the control unit 9 includes a measuring instrument 91, a synthesizer 92, a filter unit 93, and a processing unit 94.

The measuring instrument 91 has a first measuring instrument 91_1 and a second measuring instrument 91_2. The first measuring instrument 91_1 is connected to both ends of the first coil 131_1. The second measuring instrument 91_2 is connected to both ends of the second coil 131_2. In this example, the first coil 131_1 is located upstream of the second coil 131_2 in the specific direction W_D of the wire rope 2S.

As shown in FIG. 6, when the damaged portion B_W enters between the first pole piece 113_1 and the second pole piece 113_1, the leakage magnetic flux L_F leaks from the wire rope 2 around the damaged portion B_W. The leakage magnetic flux L_F is interlinked with the first coil 131_1 and then with the second coil 131_2. Therefore, the time at which the peak of the induced voltage generated at both ends of the first coil 131_1 occurs is higher than the time at which the peak of the induced voltage generated at both ends of the second coil 131_1 occurs at the first coil 131_1 and the first coil 131_1. The distance P between the centers of the coils 131_2 of 2 is deviated by the delay time τ represented by the value obtained by dividing the distance P between the centers of the coils 131_2 by the moving speed ν of the wire rope 2S.

Therefore, the first measuring instrument 91_1 detects the induced voltage, which is a signal corresponding to the leakage magnetic flux L_F leaking from the wire rope 2S, as the sensor signal f1 (t−τ). Further, the second measuring instrument 91_2 detects the induced voltage, which is a signal corresponding to the leakage magnetic flux L_F leaking from the wire rope 2S, as the sensor signal f2 (t).

The synthesizer 92 superimposes the sensor signal f1 (t−τ) detected by the first measuring instrument 91_1 and the sensor signal f2 (t) detected by the second measuring instrument 91_1 to form the sensor signal x. (T) is generated. Specifically, the synthesizer 92 detects the sensor signal f1 (t−τ) detected by the first measuring instrument 91_1 with the sensor signal f1 (t) delayed by the time τ and the second measuring instrument 91_2. The generated sensor signal f2 (t) is superimposed. As a result, the sensor signal x (t) becomes a signal obtained by combining the peaks of the induced voltage generated across the first coil 131_1 and the peaks of the induced voltage generated across the second coil 131_2.

The synthesizer 92 samples the sensor signal x (t) at a constant period Ts. Since the sampled signal is a signal for each period Ts, the time can be represented by an integer n with the period Ts as a unit. That is, the relationship between the analog time of the sensor signal x (t) and the time of the sampled signal is t = n · Ts. The amplitude of the sampled signal is real. Therefore, the discrete signal, which is a sampled signal, is represented as a sequence of real values {x (0), x (1), x (2), ...}, So it is represented as a sequence x (n). To. The sequence x (n) is supplied to the filter unit 93 as an input signal x (n).

Hereinafter, the sequence x (n) will be referred to as an input signal x (n) of the filter unit 93.

The filter unit 93 extracts the frequency component of the input signal x (n) that samples the sensor signal x (t). The filter unit 93 has a plurality of FIR (Finite Impulse Response) filters 931 as a plurality of bandpass filters, and a plurality of absolute value units 932.

FIG. 7 is a diagram showing an example of the frequency characteristics of the filter unit 93 of FIG. As shown in FIG. 7, the number of taps, the gain, and the bandwidth b are constant in each of the plurality of FIR filters 931. The plurality of FIR filters 931 have a plurality of bands different from each other as individual pass bands. That is, the plurality of FIR filters 931 have different pass bands different from each other. Therefore, the filter unit 93 extracts the frequency component of the input signal x (n) in each of the plurality of bands different from each other.

As shown in FIG. 6, the plurality of absolute value units 932 obtain the absolute values of the frequency components of the input signals x (n) supplied from the plurality of FIR filters 931. Here, the input signal x (n) is a sequence of real values {x (0), x (1), x (2), ...} As described above. Therefore, the plurality of absolute value units 932 quantize the input signal x (n) by dividing it by the quantization unit and rounding it off to obtain a sequence yk (n) of integer values. However, k is a value in ascending order from 1 to N. Also, N is a natural number.

For example, when a real value x (0) is input to the plurality of FIR filters 931, the plurality of FIR filters 931 extract the frequency component of the real value x (0) in each of a plurality of bands different from each other. The absolute value unit 932 obtains the absolute value of the frequency component of the real value x (0) for each individual pass band, and then the integer values y1 (0), y2 (0), ..., And yN (0). Ask for.

Hereinafter, the integer values y1 (0), y2 (0), ... And yN (0) are referred to as a sequence of integer values {y1 (0), y2 (0), ... And yN (0)}. It is expressed as a sequence yk (0).

The filter unit 93 performs the same processing on the real value x (1) to obtain yk (1). The filter unit 93 performs the same processing on the real value x (2) and later, and obtains yk (2) and later. From the above description, the filter unit 93 obtains the sequence yk (n) from the input signal x (n).

FIG. 8 is a diagram showing an example of the distribution of frequency components extracted from the input signal x (n) by the filter unit 93 of FIG. As shown in FIG. 8, the moving speed ν of the wire rope 2S is trapezoidally controlled, for example. Therefore, when the wire rope 2S is moving at a constant velocity, the periodic fluctuation of the input signal x (n) due to the shape of the outer peripheral portion of the wire rope 2S is constant. Periodic variation of the input signal x (n) due to the shape on the outer peripheral portion of the wire rope 2S occurs for each pitch λS of the strand 21S as described above. Therefore, the constant periodic fluctuation of the input signal x (n) occurs at a specific frequency.

For example, as shown in FIG. 8, the noise frequency component f_n of the input signal x (n) appears in the bands when k = 6 and k = 8 when the wire rope 2S is moving at a constant velocity. To do.

Therefore, the frequency component of the constant periodic fluctuation of the input signal x (n) can be regarded as the noise frequency component f_n of the input signal x (n) among the frequency components of the input signal x (n).

Further, when the input signal x (n) is a signal synthesized by the synthesizer 92 according to the leakage magnetic flux L_F, the signal generated during the local minute time Δt and the input signal x (n) in the time domain. ) Is equivalent. Therefore, when the input signal x (n) is a signal synthesized by the synthesizer 92 according to the leakage magnetic flux L_F, the shorter the minute time Δt, the more the frequency component of the input signal x (n) appears in the band. The number increases.

For example, as shown in FIG. 8, the damage frequency component f_s of the input signal x (n) is k = 3, k = 4, k = 5, k = 6, k = 7, k = 8 and k = 9. Appears in each band of time.

As a result, the distribution of the frequency components of the input signal x (n) becomes a distribution over a plurality of bands. Therefore, among the frequency components of the input signal x (n), the damaged frequency component f_s of the input signal x (n) also appears in a band other than the band in which the noise frequency component f_n of the input signal x (n) appears.

The distribution of frequency components is composed of a sequence yk (n). As described above, the sequence yk (n) is composed of integer values y1 (n), y2 (n), ..., And yN (n). Therefore, the distribution of frequency components is composed of a plurality of values y1 (n) to yN (n).

As shown in FIG. 6, the processing unit 94 has a calculation unit 941 and a determination unit 943. The processing unit 94 determines whether or not the wire rope included in the wire rope 2S is damaged based on the distribution of the frequency components of the input signal x (n) extracted by the filter unit 93.

The calculation unit 941 extracts a feature amount by statistical calculation from a plurality of values constituting the distribution of the frequency components of the input signal x (n) over a plurality of bands. The feature amount is a representative value that characterizes the distribution of the frequency component of the input signal x (n). The statistical operation is, for example, an operation for obtaining the median value m (n). The median m (n) is a value located at the center when the integer values y1 (n), y2 (n), ..., And yN (n) constituting the sequence yk (n) are arranged in ascending order. is there.

FIG. 9 is a diagram showing an example of the sequence yk (n) generated by the filter unit 93 at the time t1 of FIG. In an example of FIG. 9, among a plurality of values y1 (n) to yN (n) constituting the sequence yk (n), the values y1 (n) to y5 (n) when k = 1 to 5, 7 and 9 ), Y7 (n) and y9 (n) are zero, and the values y6 (n) and y8 (n) when k = 6 and 8 are larger than zero. Therefore, when a plurality of values y1 (n) to yN (n) constituting the sequence yk (n) are arranged in ascending order, the value located at the center becomes zero.

FIG. 10 is a diagram showing an example of the sequence yk (n) generated by the filter unit 93 at the time t2 of FIG. In one example of FIG. 10, when a plurality of values y1 (n) to yN (n) constituting the sequence yk (n) are arranged in ascending order, the value located at the center is the value when k = 5. Therefore, as the median value m (n), the value when k = 5 is adopted. Here, at time t2, as shown in FIG. 8, the distribution of the frequency component of the input signal x (n) includes the damaged frequency component f_s. Therefore, the determination unit 943 sets the setting threshold value for determining whether or not the damage frequency component f_s is included in the frequency component distribution to be 0 or more and less than the value y5 (n) when k = 5. ..

The determination unit 943 determines whether or not the wire rope included in the wire rope 2S is damaged based on the feature amount. Specifically, the determination unit 943 determines whether or not the wire rope included in the wire rope 2S is damaged by comparing the feature amount extracted by the calculation unit 941 with the set threshold value. More specifically, the determination unit 943 determines that the wire rope 2S is damaged when the feature amount exceeds the set threshold value. On the other hand, when the feature amount is equal to or less than the set threshold value, the determination unit 943 determines that the wire rope 2S is not damaged.

Here, the damage to the wire contained in the wire rope 2S is the physical damage caused to at least a part of the wire rope 2S. Physical damage is, for example, damage to at least one of wire breakage, partial wire breakage, and scratch marks on the wire.

Hereinafter, damage to the wire contained in the wire rope 2S will be appropriately referred to as damage to the wire.

Note that the set threshold value differs depending on the value obtained by statistical calculation. Specifically, in the statistical calculation, in addition to the calculation of the median value m (n), for example, the maximum value, the minimum value, the range, the average value, the standard deviation, the effective value, the crest factor, and the kurtosis are obtained. There is an operation. Further, among the values obtained by the statistical calculation, the range is the value obtained by the calculation for finding the difference between the maximum value and the minimum value. Further, among the values obtained by statistical calculation, the crest factor is a value obtained by calculation for obtaining the ratio of the maximum value to the effective value. Different setting threshold values are set in the determination unit 96 according to the value obtained by the above statistical calculation.

FIG. 11 is a flowchart illustrating processing by the control unit 9 of FIG. In step S11, the synthesizer 92 inputs the input signal x (n) corresponding to the sensor signal x (t) to the filter unit 93. In step S12, the filter unit 93 extracts the frequency component of the input signal x (n) with a plurality of bandpass filters. In step S13, the calculation unit 941 performs a statistical calculation on the sequence yk (n) composed of the frequency components extracted by the plurality of bandpass filters. In step S14, the determination unit 943 determines whether or not the feature amount extracted by the statistical calculation exceeds the set threshold value. When the determination unit 943 determines that the feature amount extracted by the statistical calculation exceeds the set threshold value, the determination unit 943 shifts to the process of step S15. In step S15, the determination unit 943 determines that the wire is damaged, and ends the process. On the other hand, when the determination unit 943 determines that the feature amount extracted by the statistical calculation does not exceed the set threshold value, that is, is equal to or less than the set threshold value, the determination unit 943 shifts to the process of step S16. In step S16, the determination unit 943 determines that there is no damage to the wire, and ends the process.

The process of step S14 is a process assuming that the values obtained by the statistical calculation are, for example, the maximum value, the median value m (n), the average value, the standard deviation, the execution value, and the crest factor. Therefore, when the value obtained by the statistical calculation is other than, for example, the maximum value, the median value m (n), the average value, the standard deviation, the execution value, and the crest factor, the determination unit 943 performs the process of step S14. Performs a different comparison process.

For example, when assuming the minimum value as the value obtained by the statistical calculation, in step S14, the determination unit 943 determines whether or not the feature amount extracted by the statistical calculation is less than the set threshold value. In this way, even when the value yk (n) constituting the noise frequency component f_n is larger than the value yk (n) constituting the damage frequency component f_s, the control unit 9 may or may not damage the wire. Can be determined. That is, the determination unit 943 changes the magnitude relationship between the feature amount and the setting threshold value in the comparison process according to the value obtained by the statistical calculation.

From the above description, the wire rope flaw detector uses a magnetometer 11 that generates a magnetic flux F that passes through a part of the wire rope 2S, and a sensor signal x that corresponds to the leakage magnetic flux L_F that leaks from the wire rope 2S among the magnetic flux F. It includes a magnetic sensor 13 generated as (t) and a control unit 9 for processing the sensor signal x (t). The control unit 9 includes a filter unit 93 that extracts the frequency component of the sensor signal x (t), and a processing unit 94 that determines whether or not the wire rope included in the wire rope 2S is damaged based on the distribution of the frequency component. ,have.

Therefore, when the magnetic flux F detected by the measuring instrument 91 is the leakage magnetic flux L_F leaking from the periphery of the damaged portion B_W, the frequency component of the sensor signal x (t) is the distribution of the frequency component spreading in the frequency axis direction. Become. Therefore, the control unit 9 can identify whether the damage frequency component f_s is superimposed as well as the noise frequency component f_n. Therefore, in the control unit 9, the difference between the noise frequency component f_n and the damaged frequency component f_s becomes clear in the frequency domain even if the SN ratio is low due to the low induced voltage generated in the magnetic sensor 13 in the time domain. The SN ratio can be increased.

In other words, the wire rope flaw detector can more reliably improve the SN ratio by determining the presence or absence of wire damage based on the distribution of frequency components.

Further, the filter unit 93 extracts frequency components in each of a plurality of bands different from each other. Therefore, the filter unit 93 can generate a distribution of frequency components including various frequency components in the frequency axis direction. The damaged frequency component f_s exists in a wider range in the frequency axis direction than the noise frequency component f_n in the frequency domain. Therefore, the filter unit 93 can more reliably make the damaged frequency component f_s appear by generating a distribution of frequency components including various frequency components in the frequency axis direction. As a result, the processing unit 94 can execute the determination processing for the presence or absence of damage to the strands in the frequency domain.

Further, the processing unit 94 is based on a calculation unit 941 that extracts a feature amount by statistical calculation from a plurality of values y1 (n) to yN (n) constituting a distribution of frequency components over a plurality of bands, and a feature amount. It has a determination unit 943 for determining the presence or absence of damage to the wire. Therefore, the processing unit 94 does not need to compare all of the plurality of values y1 (n) to yN (n), so that the amount of calculation can be reduced. Therefore, the processing unit 94 can significantly reduce the calculation cost of the comparison processing.

As described above, the calculation unit 941 constitutes a plurality of distributions of frequency components when the wire rope 2S is extracted by the filter unit 93 while the wire rope 2S is moving at a constant velocity with respect to the probe 1. Features are extracted from the values y1 (n) to yN (n) by statistical calculation.

Therefore, the value yk (n) detected during the acceleration period and the deceleration period of the wire rope 2S is not used for extracting the feature amount, and the value yk (n) detected during the constant velocity movement period of the wire rope 2S is the feature amount. It is adopted for the extraction of. As a result of limiting the period for extracting the feature amount in this way, the control unit 9 can clarify the periodic fluctuation of the induced voltage caused by the outer shape of the strand 21S.

For this reason, the control unit 9 can clearly distinguish between the noise frequency component f_n and the damaged frequency component f_s among the frequency components. Therefore, the control unit 9 can improve the accuracy of determining whether or not the wire rope included in the wire rope 2S is damaged.

Further, the determination unit 943 determines whether or not the wire is damaged by comparing the feature amount with the set threshold value. Therefore, the determination unit 943 can reduce the amount of data for performing the determination process. Therefore, the determination unit 943 can shorten the calculation time required for the determination process.

Further, the filter unit 93 has a plurality of bandpass filters in which a plurality of bands different from each other are set as individual pass bands. Therefore, the filter unit 93 can extract frequency components of a plurality of bands different from each other. The damaged frequency component f_s exists in a wider range in the frequency axis direction than the noise frequency component f_n in the frequency domain. Therefore, the filter unit 93 can surely make the damaged frequency component f_s appear by generating the distribution of the frequency component including various frequency components in the frequency axis direction. As a result, the control unit 9 can analyze the induced voltage generated by the magnetic sensor 13 as the sensor signal x (t) in the frequency domain.

Embodiment 2.
In the second embodiment, the description of the same or equivalent configuration and function as the first embodiment will be omitted. The second embodiment is different from the first embodiment in that the bandpass filter of the first embodiment is realized by the wavelet transform. Other configurations are the same as those in the first embodiment. That is, the other configurations are the same as or equivalent to those of the first embodiment, and these parts are designated by the same reference numerals.

FIG. 12 is a block diagram showing a functional configuration example of the control unit 9 that processes a signal corresponding to the leakage magnetic flux L_F leaking from the wire rope 2S according to the second embodiment of the present invention. As shown in FIG. 12, the filter unit 193 uses a wavelet transform unit 1931 as a bandpass filter to generate a distribution of frequency components of the sensor signal x (t) by performing a wavelet transform on the sensor signal x (t). I have.

FIG. 13 is a diagram showing an example of the frequency characteristics of the filter unit 193 of FIG. The bandpass filter is realized by the basis function of the wavelet transform processed by the wavelet transform unit 1931. As shown in FIG. 13, each of the bandwidth b _k of the plurality of bands, the center frequency omega _ck bandwidth becomes narrower lower.

Next, Mollet Wavelet will be described as an example of the basis function of the wavelet transform. FIG. 14 is a diagram showing an example of a waveform in the time domain of the mother wavelet by the wavelet transform unit 1931 of FIG. The mother wavelet is expressed by the following equation (1).

The daughter wavelet is expressed by the following equation (2). The scale of the daughter wavelet is expressed by the following equation (3). The daughter wavelet represented by the formula (2) can increase or decrease the amplitude of the waveform shown in FIG. 14 according to the scale represented by the formula (3). Further, the daughter wavelet represented by the equation (2) can translate the waveform shown in FIG. 14 in the time axis direction according to the scale represented by the equation (3). Here, s ₀ is a constant of scale. _sk is a scale function that takes k as an argument and _{is multiplied by s 0.}

Next, the Fourier transform of the mother wavelet and the daughter wavelet will be described. First, the Fourier transform equation of the mother wavelet is expressed by the following equation (4). On the other hand, the Fourier transform of the daughter wavelet is expressed in Eq. (5).

FIG. 15 is a diagram showing an example of waveforms in the frequency domain of the mother wavelet by the wavelet transform unit 1931 of FIG. As shown in FIG. 15, the frequency characteristic of Morlet Wavelet, among the frequency components of the input signal x (n), the frequency of the pass band specified by the center frequency omega ₀ of bandwidth b _k and bandwidth b _k It becomes a bandpass filter to pass. The center frequency ω _{ck in} FIG. 15 is expressed by the following equation (6). As expressed in equation (6), the center frequency ω _ck is _{expressed by the value obtained by dividing ω 0} / s ₀ by the power of the root of 2 to the power of m. Here, as explained above, m is a natural number.

Also, the bandwidth b _k in FIG. 15 is expressed by the following equation (7).

Here, the equations (6) and (7) when m = 1 will be described. First, the following equation (8) is an equation when m = 1 in the equation (6). From the description of equation (8), the center frequency ω _ck is expressed by the value obtained by dividing _{ω 0} / s _{0 by 2.}

On the other hand, the following equation (9) is the equation when m = 1 in the equation (7). From the description of equation (9), the bandwidth _bc is expressed by the value obtained by doubling the square root of the natural logarithm of 2 _{and dividing by s 0 by dividing by 2.}

_{Therefore, the relationship between the bandwidth b k of} one of the two adjacent bands and the bandwidth b _{k + 1} of the other band having a lower center frequency ω _ck than that of one band is Δk = 1. Since / m = ^{1/1 = 1} , the relationship of _{b k + 1} = 2-Δk · b _k = b _{k + 1} = 2 -1 · b _{k is satisfied.} Thus, for m = 1, the relationship between the bandwidth b _k, the bandwidth b _{k + 1} of the other band of one band is 1 octave.

Specifically, in the equation (8), when k = 0, the center frequency ω _ck becomes the frequency ω ₀ / s ₀ . Further, in the equation (9), when k = 0, the bandwidth _bc is expressed by the following equation (10). Therefore, from equations (8) and (9), for each k increases 1, the center frequency omega _ck and bandwidth b _k becomes 1/2.

Further, when the m is a natural number other than 1, of the two bands which are adjacent to each other, and bandwidth b _k of the one band, the band width b _k of the lower other band center frequencies omega _ck than one band _Since the relationship with +1 is Δk = 1 / m, the relationship of b _{k + 1} = 2- ^Δk · b _k = b _{k + 1} = ^{2-1 / m} · b _k is satisfied. Thus, if m is not 1, the relationship between the bandwidth b _k, the bandwidth b _{k + 1} of the other band of one band becomes 1 / m octave. Next, the center frequency ω _ck when m = 3 will be described.

FIG. 16 is a conceptual diagram of _{the center frequency ω ck} at the time of 1/3 octave as another example of the frequency characteristics of the filter unit 193 of FIG. As shown in FIG. 16, the center frequency ω _ck can be expressed by a value obtained by dividing ω ₀ / s ₀ by the power of the cube root of 2.

From the above description, the center frequency ω _ck and the center frequency ω _{ck + 1 of the} two bands adjacent to each other are expressed by the following equation (11). Equation (11) expresses the difference in magnitude between _{the center frequency ω ck} and the center frequency ω _{ck + 1 of} two bands adjacent to each other based on the equation (8). From equation (11), the center frequency ω _ck becomes ^{2-1 / m} each time k is incremented by 1.

_{Further, the bandwidth b k} and the bandwidth b _{k + 1} in each of the two adjacent bands are expressed by the following equation (12). Equation (12) expresses the difference in magnitude _{between the bandwidth b k} and the bandwidth b _{k + 1 of} two adjacent bands based on the equation (9). From equation (12), for each k increases 1, the bandwidth b _k will 2 ^{-1 / m.}

FIG. 17 is a diagram showing an example of the distribution of the frequency component extracted from the signal corresponding to the leakage magnetic flux L_F by the filter unit 193 of FIG. An example of FIG. 17, except bandwidth b _k and the center frequency omega _ck two bands adjacent to each other, is similar to an example of FIG. 8. Therefore, the description of FIG. 17 will be omitted.

FIG. 18 is a diagram showing an example of the sequence yk (n) generated by the filter unit 193 at the time t1 of FIG. In an example of FIG. 18, among a plurality of values y1 (n) to yN (n) constituting the sequence yk (n), the values y1 (n) to y3 (n) when k = 1 to 3, 5 and 7 ), Y5 (n) and y7 (n) are zero, and the values y4 (n) and y6 (n) when k = 4 and 6 are larger than zero. Therefore, when a plurality of values y1 (n) to yN (n) constituting the sequence yk (n) are arranged in ascending order, the value located at the center becomes zero.

FIG. 19 is a diagram showing an example of the sequence yk (n) generated by the filter unit 193 at the time t2 of FIG. In one example of FIG. 19, when a plurality of values y1 (n) to yN (n) constituting the sequence yk (n) are arranged in ascending order, the value located at the center is the value when k = 5. Therefore, as the median value m (n), the value when k = 5 is adopted. Here, at time t2, as shown in FIG. 17, the distribution of the frequency component of the input signal x (n) includes the damaged frequency component f_s. Therefore, the determination unit 943 sets the value y5 (n) when k = 5 as a setting threshold value for determining whether or not the damaged frequency component f_s is included in the frequency component distribution.

FIG. 20 is a flowchart illustrating processing by the control unit 9 of FIG. Since the processes of steps S31 and S34 to S36 are the same as the processes of steps S11 and S14 to S16 shown in FIG. 11 of the first embodiment, their description will be omitted. In step S32, the filter unit 193 extracts the frequency component by the wavelet transform unit 1931. In step S33, the calculation unit 941 performs a statistical calculation on the sequence yk (n) composed of the frequency components extracted by the wavelet transform unit 1931.

From the above description, in the wire rope flaw detector, each of the bandwidth b _k of the plurality of bands, the center frequency omega _ck bandwidth becomes narrower lower. Therefore, the lower the center frequency ω _{ck of the} band, the higher the frequency resolution and the lower the time resolution. The higher the center frequency ω _{ck of the} band, the lower the frequency resolution and the higher the time resolution. Therefore, it is possible to more accurately detect where the sudden fluctuation occurred on the time axis, and to determine the frequency of the slow fluctuation more accurately, which enables efficient analysis.

_{Further, the relationship between the bandwidth b k of} one of the two adjacent _{bands and the bandwidth b k + 1} of the other band having a lower center frequency than one band is Δk = 1 / m. ^Then , the relationship of b _{k + 1} = 2-Δk · b _{k is satisfied.} Therefore, the band can be changed by the root of 2 m. Therefore, the time resolution is particularly improved in the high frequency region, and the spatial resolution is particularly improved in the low frequency region.

Further, the filter unit 193 extracts a frequency component from the sensor signal x (t) by executing a wavelet transform on the sensor signal x (t). Since the wavelet is a local function, there is a high correlation between the wavelet and the detection of the locally generated wire damage portion B_W. Therefore, the damaged frequency component f_s among the frequency components can be emphasized. Therefore, since the frequency component of the induced voltage generated when the wire is damaged can be emphasized, the SN ratio can be particularly improved.

Further, for each embodiment, the functions of each part of the wire rope flaw detector are realized by the processing circuit. That is, the wire rope flaw detector includes a processing circuit for executing the synthesizer 92, the filter unit 93, the filter unit 193, the calculation unit 941 and the determination unit 943. Even if the processing circuit is dedicated hardware, it is also called a CPU (Central Processing Unit, central processing unit, processing unit, arithmetic unit, microprocessor, microprocessor, processor, DSP) that executes a program stored in the memory. It may be.

FIG. 21 is a diagram illustrating a hardware configuration example. In FIG. 21, the processing circuit 201 is connected to the bus 202. When the processing circuit 201 is dedicated hardware, the processing circuit 201 corresponds to, for example, a single circuit, a composite circuit, a programmed processor, an ASIC, an FPGA, or a combination thereof. The functions of each part of the wire rope flaw detector may be realized by the processing circuit 201, or the functions of each part may be collectively realized by the processing circuit 201.

FIG. 22 is a diagram illustrating another hardware configuration example. In FIG. 22, the processor 203 and the memory 204 are connected to the bus 202. When the processing circuit is a CPU, the functions of each part of the wire rope flaw detector are realized by software, firmware, or a combination of software and firmware. The software or firmware is written as a program and stored in memory 204. The processing circuit realizes the functions of each part by reading and executing the program stored in the memory 204. That is, when the wire rope flaw detector is executed by the processing circuit, the steps of controlling the synthesizer 92, the filter unit 93, the filter unit 193, the calculation unit 941 and the determination unit 943 are eventually executed. It has a memory 204 for storing a program. Further, it can be said that these programs cause the computer to execute the procedure and method for executing the synthesizer 92, the filter unit 93, the filter unit 193, the calculation unit 941 and the determination unit 943. Here, the memory 204 includes, for example, non-volatile or volatile semiconductor memories such as RAM, ROM, flash memory, EPROM, EEPROM, magnetic disks, flexible disks, optical disks, compact disks, mini disks, DVDs, and the like. Applicable.

Note that some of the functions of each part of the wire rope flaw detector may be realized by dedicated hardware, and some may be realized by software or firmware. For example, the filter unit 93 and the filter unit 193 realize their functions with a processing circuit as dedicated hardware, and the processing circuit reads and executes a program stored in the memory 204 for the calculation unit 941 and the determination unit 943. By doing so, it is possible to realize the function.

In this way, the processing circuit can realize each of the above-mentioned functions by hardware, software, firmware, or a combination thereof. Next, an example of realizing each of the above-mentioned functions will be specifically described.

FIG. 23 is a diagram showing a system configuration example in which at least one of the control units 9 of FIGS. 6 and 12 is incorporated into the terminal device 501 and used as a specific example of FIG. 21 or FIG. In the wire rope flaw detector, as shown in FIG. 23, the probe 1 detects damage to the wire rope 2S. The wire rope 2S, for example, suspends an elevator car. The wire rope 2S may be used for a crane.

The wire rope 2S detects damage to the wire while moving with respect to the probe 1 along, for example, the specific direction W_D. The probe 1 supplies, for example, a sensor signal x (t), which is an analog signal, to the AD converter 301 via a cable. The AD converter 301 converts an analog signal into a digital signal. The digital signal converted by the AD converter 301 is input to the terminal device 501. As the terminal device 501, for example, a personal computer is used. The terminal device 501 determines whether or not the wire is damaged by performing various signal processing on the digital signal input from the AD converter 301. In addition, the terminal device 501 displays the determination result of the presence or absence of damage to the wire.

FIG. 24 shows a system configuration example in which the processing content of the determination device 401 is supplied to the data logger 601 by incorporating at least one of the control units 9 of FIGS. 6 and 12 into the determination device 401 as a specific example of FIG. 21 or FIG. It is a figure which shows. The probe 1 supplies, for example, a sensor signal x (t) composed of an analog signal to the determination device 401 via a cable. The determination device 401 is equipped with a microcomputer. The determination device 401 is dedicated hardware. The determination device 401 converts an analog signal into a digital signal. The determination device 401 determines whether or not the wire is damaged by performing various signal processing on the converted digital signal. In addition, the determination device 401 notifies the determination result of the presence or absence of damage to the wire.

Note that the determination device 401 can supply various internally processed signals to an external device as analog signals or digital signals. As the external device, for example, a data logger 601 is used. The data logger 601 can display a waveform by inputting an analog signal or a digital signal from the determination device 401. Further, the data logger 601 can record the processing contents of the determination device 401.

FIG. 25 shows a system configuration in which the processing content of the determination device 401 is supplied to the elevator control panel 701 by incorporating at least one of the control units 9 of FIGS. 6 and 12 into the determination device 401 as a specific example of FIG. 21 or FIG. It is a figure which shows an example. By inputting a digital signal from the determination device 401, the elevator control panel 701 can transmit monitoring information such as which wire rope 2 of which property is broken to the central monitoring center.

The wire rope flaw detector has been described above based on the first and second embodiments, but the present invention is not limited to this.

In the first and second embodiments, an example in which the upper limit frequency and the lower limit frequency in the frequency band are fixed within a certain range regardless of the moving speed ν of the wire rope 2S and the diameter of the wire rope 2S has been described. However, it is not particularly limited to this. For example, the upper limit frequency and the lower limit frequency in the frequency band may be determined based on at least one of the moving speed ν of the wire rope 2S and the diameter of the wire rope 2S.

Specifically, the faster the moving speed ν of the wire rope 2S, the higher the frequency component becomes the frequency component that contributes to the determination. Therefore, as the moving speed ν of the wire rope 2S becomes faster, the upper limit frequency and the lower limit frequency in the frequency band are shifted to higher than the preset default range, so that the frequency band is more suitable. The frequency component can be used for the determination. On the other hand, as the diameter of the wire rope 2S becomes smaller, a higher frequency component becomes a frequency component that contributes to the determination. Therefore, as the diameter of the wire rope 2S becomes smaller, the upper limit frequency and the lower limit frequency in the frequency band are shifted to higher than the preset default range, so that the frequency component of the more suitable frequency band is obtained. Can be used for determination.

Further, as the moving speed ν of the wire rope 2S becomes slower, the lower frequency component becomes the frequency component that contributes to the determination. Therefore, as the moving speed ν of the wire rope 2 becomes slower, the upper limit frequency and the lower limit frequency in the frequency band are shifted to be lower than the preset default range, so that the frequency band is more suitable. The frequency component can be used for the determination. On the other hand, as the diameter of the wire rope 2S becomes larger, the lower frequency component becomes the frequency component that contributes to the determination. Therefore, as the diameter of the wire rope 2S becomes larger, the upper limit frequency and the lower limit frequency in the frequency band are shifted to lower than the preset default range, so that the frequency component of the more suitable frequency band is obtained. Can be used for determination.

2,2S wire rope, 11 magnetometer, 13 magnetic sensor, 9 control unit, 93,193 filter unit, 94 processing unit, 941 calculation unit, 943 judgment unit.

Claims (8)

1. A magnetizer that generates magnetic flux that passes through a part of the wire rope,
   A magnetic sensor that generates a signal corresponding to the leakage magnetic flux leaking from the wire rope as a sensor signal among the magnetic fluxes,
   A control unit that processes the sensor signal and
   With
   The control unit
   A filter unit that extracts the frequency component of the sensor signal and
   Based on the distribution of the frequency component, a processing unit that determines whether or not the wire rope contained in the wire rope is damaged, and a processing unit.
   Has a wire rope flaw detector.
2. The wire rope flaw detector according to claim 1, wherein the filter unit extracts the frequency component in each of a plurality of bands different from each other.
3. The processing unit
   A calculation unit that extracts features by statistical calculation from a plurality of values constituting the distribution of the frequency components over the plurality of bands.
   A determination unit for determining the presence or absence of damage to the wire based on the feature amount,
   The wire rope flaw detector according to claim 2.
4. The wire rope flaw detector according to claim 3, wherein the determination unit determines whether or not the wire is damaged by comparing the feature amount with the set threshold value.
5. The wire rope flaw detector according to any one of claims 2 to 4, wherein the filter unit has a plurality of bandpass filters having the plurality of bands as individual pass bands.
6. The wire rope flaw detector according to any one of claims 2 to 5, wherein the bandwidth of each of the plurality of bands becomes narrower as the center frequency of the band becomes lower.
7. Of the adjacent two of the bands, and bandwidth b _k of the one band, the relationship between the bandwidth b _{k + 1} of the other band lower center frequency than the band of the one is, m is a natural number, If Δk = 1 / m,
   ^{The wire rope flaw detector according} to claim 6, which satisfies the relationship of b _{k + 1} = 2-Δk · b _k.
8. The filter unit
   The wire rope flaw detector according to claim 6 or 7, wherein the frequency component is extracted from the sensor signal by performing a wavelet transform on the sensor signal.

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