Signal control device, gain control program, and wire rope tester

Abstract

Even without detecting the wire rope's movement speed, the fluctuations in the output signal from the sensor coil based on the wire rope's movement speed are canceled out. [Solution] The signal control device 30 comprises a first PGA 31, a low-pass filter 32, a second PGA 33, a microcontroller 34, and a buffer amplifier 35. The output signal of the sensor coil 17 is amplified by the first and second PGAs 31 and 33. The microcontroller 34 controls the setting gains of the first and second PGAs 31 and 33 to maintain the level of the unevenness output signal (strand noise signal) caused by the unevenness of the wire rope surface at a predetermined target level.

Description

[Technical Field]

[0001] This invention relates to a signal control device, a gain control program, and a wire rope tester. [Background technology]

[0002] Many wire rope testers (wire break detection devices) use semiconductor magnetic sensors (see Patent Document 1). One reason for this is that semiconductor magnetic sensors can output signals that are independent of the wire rope's movement speed, eliminating the need to consider the wire rope's speed.

[0003] On the other hand, semiconductor magnetic sensors have a narrow detection area, and when used on objects with a circular cross-section, such as wire ropes, a large number of semiconductor magnetic sensors must be arranged in a circular pattern around the circumference. Furthermore, a power supply must be provided to these numerous semiconductor magnetic sensors.

[0004] A wire rope tester using a sensor coil is also known (see Patent Document 2). When the leakage magnetic flux from a broken wire rope links with the sensor coil, the signal output from the sensor coil is used to detect the break.

[0005] Unlike semiconductor magnetic sensors, the output signal of a sensor coil is affected by the movement speed of the wire rope, and the output signal increases in proportion to the movement speed of the wire rope. To cancel out the fluctuations in the output signal based on the movement speed, it is common practice to change the gain value setting for amplifying the output signal for each movement speed (inspection speed) of the wire rope, or to detect the movement speed of the wire rope using a distance sensor or speedometer and correct the gain value according to the movement speed. When inspecting a wire rope with an unknown movement speed or a wire rope whose movement speed changes, it is necessary to start by detecting the movement speed of the wire rope. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2023-179205 [Patent Document 2] Japanese Patent Publication No. 2012-103177 [Disclosure of the Invention]

[0007] This invention aims to cancel out fluctuations in the output signal from a sensor coil based on the movement speed of a wire rope, without detecting the movement speed of the wire rope itself.

[0008] The signal control device according to this invention is provided with an output signal from the sensor coil of a magnetization detector, which includes a magnetizer having a pair of spaced-apart magnetic poles and a sensor coil positioned between the pair of magnetic poles and having a periodic surface irregularity for detecting leakage magnetic flux generated from a wire rope magnetized by the magnetizer. The device includes an amplifier that amplifies the output signal from the sensor coil and a gain controller that controls the setting gain of the amplifier to maintain the level of the irregularity output signal, which is caused by the irregularities on the surface of the wire rope, at a predetermined target level.

[0009] This invention also provides a program for controlling the above-mentioned signal control device (gain). The program for controlling a signal control device, which is used with a magnetization detector that includes a magnetizer having a pair of spaced-apart magnetic poles and a sensor coil positioned between the pair of magnetic poles and having a periodic surface irregularity for detecting leakage magnetic flux generated from a wire rope magnetized by the magnetizer, and which includes an amplifier for amplifying the output signal output from the sensor coil, controls the setting gain of the amplifier so as to maintain the level of the irregularity output signal generated from the surface irregularity of the wire rope among the output signals of the sensor coil at a predetermined target level.

[0010] This invention also provides a wire rope tester. The wire rope tester according to this invention includes a magnetization detector comprising a magnetizer having a pair of magnetic poles arranged at a distance from each other, and a sensor coil disposed between the pair of magnetic poles and having periodic irregularities on its surface for detecting leakage magnetic flux generated from a wire rope magnetized by the magnetizer, an amplifier for amplifying the output signal output from the sensor coil, and a gain controller for controlling the setting gain of the amplifier to maintain the level of the irregularity output signal generated from the output signal of the sensor coil due to irregularities on the surface of the wire rope at a predetermined target level, and a damage determination device which determines damage to the wire rope based on a damage signal exceeding the threshold level generated from a damaged location on the wire rope, where a threshold level for levels exceeding the target level is set.

[0011] The output signal from the sensor coil of the magnetization detector is supplied to the signal control device according to this invention. The magnetization detector comprises a magnetizer having a pair of spaced-apart magnetic poles, and a sensor coil positioned between the pair of magnetic poles. Leakage magnetic flux from the surface of a moving magnetized wire rope links with the sensor coil, generating an electromotive force in the sensor coil. A signal corresponding to this electromotive force is output from the sensor coil.

[0012] A wire rope has a surface with periodic irregularities, and is constructed by twisting together multiple strands, which are made by twisting together multiple metal wires. Each of the multiple strands extends spirally in the longitudinal direction of the wire rope, thereby creating a spiral pattern of irregularities on the surface of the wire rope.

[0013] According to the present invention, the set gain of an amplifier that amplifies the output signal of a sensor coil is controlled so as to keep the uneven output signal caused by the unevenness on the surface of a wire rope at a predetermined target level. The leakage magnetic flux from the wire rope becomes smaller as it moves away from the wire rope. Since the distance between the wire rope and the sensor coil varies periodically due to the periodic unevenness on the surface of the wire rope, the amplitude of the output signal (uneven output signal) output from the sensor coil varies periodically. The set gain of the amplifier is increased or decreased so that this amplitude is kept at a constant level.

[0014] As described above, the output signal from the sensor coil depends on the moving speed of the wire rope. If the moving speed is high, the amplitude becomes large; if it is low, the amplitude becomes small. When the level of the uneven output signal caused by the unevenness on the surface that the wire rope structurally has approaches the level of the damage signal caused by the damaged part of the wire rope, it becomes difficult to detect only the damage signal of the wire rope (typically, detecting an output signal with a level above a predetermined threshold). Therefore, the uneven output signal caused by the unevenness on the surface that the wire rope structurally has may be treated as noise (strand noise).

[0015] According to the present invention, by using the uneven output signal (strand noise) caused by the unevenness on the surface that the wire rope structurally has, the set gain of the amplifier is increased or decreased so as to keep the level of the uneven output signal constant, and the variation in the output signal from the sensor coil based on the moving speed of the wire rope is canceled. Thereby, for example, it is not necessary to set the threshold value excessively large in order to reliably detect the damage signal (to prevent the strand noise from being erroneously detected as the damage signal), and the uneven output signal and the damage signal can be reliably separated. Since it is not necessary to detect the moving speed of the wire rope, the entire wire rope tester can be simplified.

[0016] In one embodiment, the gain controller includes a target gain calculation means for calculating a target gain for setting the level of the measurement signal obtained by amplifying the uneven output signal of the sensor coil by the amplifier to the target level, and a set gain increase / decrease means for increasing or decreasing the set gain by a predetermined value so as to approach the target gain. It is possible to prevent noise generated by rapidly increasing or decreasing the set gain at one time.

[0017] In another embodiment, the gain controller can be switched between an off state in which gain control is not executed and an on state in which gain control is executed, and the gain controller is controlled so that it can be switched from the off state to the on state when the level of the measurement signal is equal to or higher than a predetermined on level smaller than the target gain. For example, when starting to move the wire rope at the start of a test, it is possible to prevent a large value from being immediately set as the set gain and a weak output signal from the sensor coil from being immediately amplified greatly.

[0018] Preferably, the gain controller can be switched between an on state in which gain control is executed, an off state in which gain control is not executed, and an on-off transition state in which the on state is continued and the set gain is gradually decreased. When the gain controller is in the on state, the gain controller is controlled so that it can be switched from the on state to the on-off transition state when the level of the measurement signal is equal to or lower than a predetermined off level smaller than the target gain and the set gain has reached the maximum value of the set gain. For example, when reducing the speed of the wire rope at the end of a wire rope test, it is possible to prevent the output signal from the coil from being suddenly decreased.

[0019] In another embodiment, when the gain controller is in the on-off transition state, the gain controller is controlled so that it can be switched from the on-off transition state to the off state when the set gain reaches the initial gain. By setting a relatively small value as the initial gain, it is possible to prevent the set gain from being rapidly decreased.

[0020] In another embodiment, when the gain controller is in an on-off transition state, the gain controller is controlled to return from the on-off transition state to the on state when the level of the measurement signal is equal to or greater than the target level. This allows for a quick return to the on state when the wire rope speed is increased after it has entered an on-off transition state due to a decrease in wire rope speed. [Brief explanation of the drawing]

[0021] [Figure 1] The magnetization detector is shown from the side. [Figure 2] This is an enlarged cross-sectional view along line II-II in Figure 1. [Figure 3] This graph shows the measurement signal from a sensor coil based on the leakage magnetic flux from a wire rope moving at a constant speed and exhibiting damage. [Figure 4] This graph shows the measurement signal from a sensor coil based on the leakage magnetic flux from a wire rope as its moving speed is gradually increased, and a graph showing the moving speed of the wire rope. [Figure 5] This is a block diagram of a signal control device. [Figure 6] This is a flowchart showing the processing of a signal control device. [Figure 7] This is a flowchart showing the processing of a signal control device. [Figure 8] This shows the measurement signal after processing by the signal control device. [Modes for carrying out the invention]

[0022] Figure 1 shows a side view of the magnetization detector that makes up the wire rope tester. Figure 2 is an enlarged cross-sectional view along the line II-II in Figure 1.

[0023] The magnetization detector comprises a pair of magnets (permanent magnets) 11 and 12 spaced apart on the upper surface of the back yoke 15, magnetic poles 13 and 14 provided on the upper surfaces of the magnets 11 and 12 respectively, and a sensor coil 17 provided between the pair of magnets 11 and 12. The sensor coil 17 is fixed to the upper surface of a non-magnetic coil base 16 provided on the upper surface of the yoke 15 and is located exactly midway between the magnetic poles 13 and 14.

[0024] The magnetic poles 13 and 14 have roughly semicircular recesses 13a and 14a in their cross-section (Figure 2 shows the semicircular recess 14a of magnetic pole 14). The sensor coil 17 also has a recess in its cross-section (not shown) (the sensor coil 17 is curved in a U-shape), and a wire rope 1 with a circular cross-section is passed through the recesses 13a and 14a of the magnetic poles 13 and 14 and the recess of the sensor coil 17. A magnetic rail (not shown) with a recess may be provided between the magnetic poles 13 and 14, and the wire rope 1 may be passed through the recess of this rail.

[0025] The wire rope 1 is formed by twisting together multiple strands 2 made of multiple steel wires 3 with a circular cross-section, and further twisting together multiple strands 2. A magnetic circuit is formed by a portion of the wire rope 1 sandwiched between magnets 11, 12, yoke 15, magnetic poles 13, 14, and magnetic poles 13, 14.

[0026] If there is damage (missing or broken wires) to the wire rope 1 (strands 2, individual wires 3), magnetic flux leakage (leakage flux) will occur at the damaged area.

[0027] Figure 3 shows the measurement signal output from the sensor coil 17 of the magnetization detector when the damaged wire rope 1 is passed through at a constant speed.

[0028] If the number of turns of the sensor coil 17 is N and the magnetic flux linked with the sensor coil 17 is φ(Wb), then the induced electromotive force V generated at both ends of the sensor coil 17 is given by the following equation.

[0029] Induced electromotive force V(v)=-N×dφ / dt...Equation 1

[0030] If the magnetized wire rope 1 is damaged, magnetic flux leaks outward at the damaged point. When the damaged point of the wire rope 1 passes through the sensor coil 17, a large change occurs in the magnetic flux φ passing through the sensor coil 17, which increases the signal output from the sensor coil 17. Based on the signal output from the sensor coil 17, the presence of damage (damage signal 17A) can be detected.

[0031] Magnetic flux leaks even from the undamaged portion of the wire rope 1, and an output signal 17B is generated from the sensor coil 17 even when the undamaged portion passes through the magnetization detector. Even if the leakage magnetic flux is constant, the level (amplitude) of the output signal 17B fluctuates. This is because, as described above, the wire rope 1 is constructed by twisting together multiple strands 2, and the surface of the wire rope 1 is inevitably formed with irregularities. As a result, the diameter of the wire rope 1 passing through the sensor coil 17 fluctuates periodically, and the distance between the wire rope 1 and the sensor coil 17 decreases. When the wire rope 1 is close to the sensor coil 17, the level of the output signal 17B increases, and when it is farther away, the level of the output signal 17B decreases. The output signal 17B from the sensor coil 17, which is caused by the irregularities on the surface of the wire rope 1, is not a signal caused by damage to the wire rope 1, but rather a signal caused by the irregularities on the surface of the wire rope 1, and is treated as noise from the perspective of detecting the damage signal 17A. In the following, the output signal 17B resulting from the surface irregularities of the wire rope 1 will be referred to as the "strand noise signal 17B".

[0032] If the speed of the wire rope 1 (or the speed at which the magnetization detector moves instead of the wire rope 1) is constant, the induced electromotive force, i.e., the amplitude of the output signal of the sensor coil 17, follows the change in magnetic flux. However, from Equation 1, even if there is no change in magnetic flux, if the speed of the wire rope 1 changes, the amplitude of the output signal of the sensor coil 17 will also fluctuate.

[0033] Figure 4 shows the fluctuations in the measurement signal (strand noise signal) from the sensor coil 17 (upper graph of Figure 4) that occur in response to changes in the speed of the wire rope 1 (lower graph of Figure 4). As the speed 17D of the wire rope 1 increases, the level (amplitude) of the measurement signal (strand noise signal) 17C from the sensor coil 17 increases and its frequency also increases.

[0034] For example, by changing the amplification factor of the output signal from the sensor coil 17 according to the speed of the wire rope 1, or by changing the threshold for detecting the damage signal 17A, it is possible to detect the damage signal 17A regardless of the speed of the wire rope 1. However, this requires detecting the speed of the wire rope 1, and an encoder or similar device is needed for speed detection (calculation).

[0035] As described below, in this embodiment of the invention, a signal control device 30 is used that operates to maintain the signal output from the sensor coil 17 at a constant level regardless of the speed of the wire rope 1. The operation of this signal control device 30 will be described in detail below.

[0036] Figure 8 shows the measured signal S, which is the result of processing the strand noise signal 17C shown in Figure 4 by the signal control device 30, which will be described in detail below. The signal control device 30 cancels out the change in signal amplitude according to the speed of the wire rope 1, so that even if the speed of the wire rope 1 changes, the amplitude remains at a predetermined target level S as if the wire rope 1 were running at a constant speed. TG A maintained measurement signal S is output. The damage signal 17A can be detected accurately without detecting the speed of the wire rope 1 and increasing or decreasing the signal amplification factor according to the speed of the wire rope 1, or changing the threshold for determining the damage signal 17A.

[0037] Figure 5 shows a block diagram of the signal control device 30. Figures 6 and 7 are flowcharts showing the processing flow of the signal control device 30.

[0038] The signal control device 30 includes a first PGA (programmable gain amplifier) ​​31 connected to the sensor coil 17 and supplied with the output signal from the sensor coil 17 (the potential difference across the sensor coil 17), an LPF (low-pass filter) 32 supplied with the output signal from the first PGA 31 and blocking high-frequency components in the signal to improve the signal-to-noise ratio, a second PGA 33 that amplifies the low-pass filtered signal, an MCU (microcontroller) 34 that controls the gain (amplification ratio) of the first and second PGAs 31 and 33, and a buffer amplifier 35 that shapes the waveform of the output signal from the MCU 34. In the following description, the signal output from the second PGA 33 and input to the MCU 34 will be referred to as the "measurement signal S". The signal control device 30 operates according to the program stored in the memory of the MCU 34, as described below.

[0039] Refer to Figure 6, and first, the set value, specifically the initial gain G. INI (For example, 500), maximum gain G MAX (For example, 6000), AGC on level S AGC_ON (For example, 0.400V), AGC off level S AGC_OFF (For example, 0.20V) and target level S TG A value such as 0.30V is set. Details of these settings will be described later. The settings are stored in the memory (not shown) of the MCU34 (step 51).

[0040] The first and second PGAs 31 and 33 can take on one of three processing states: "AGC off" (no gain control), "AGC on" (gain control enabled), or "transitioning to AGC off" (gradual gain reduction). The processing states of the first and second PGAs 31 and 33 are also stored in the memory (not shown) of the MCU 34.

[0041] Initially, the processing states of the first and second AGCs 31 and 33 are set to "AGC off" (step 52).

[0042] The initial gain G is set (applied) as the gain G for the first and second PGA31 and 33.INI is set (step 53), and the signal from the sensor coil 17 is amplified by the set initial gain G INI (step 54).

[0043] The measurement signal S amplified by the first and second PGAs 31 and 33 and given to the MCU 34 is output from the signal control device 30 after being shaped in waveform by the buffer amplifier 35 (step 55). The signal output from the signal control device 30 is used to determine the presence or absence of the damage signal 17A (that is, whether there is damage to the wire rope 1) by being compared with, for example, a predetermined threshold value (for example, 1.5V).

[0044] It is determined whether the processing state is "AGC on" or "transitioning to AGC off", or "AGC off" (step 56).

[0045] As described above, in the initial state, the processing state "AGC off" is set (step 52). This is to prevent the weak measurement signal S generated when the wire rope 1 starts to move (typically at the start of the test of the wire rope 1) from being amplified immediately by a large set gain G. When the processing state is set to "AGC off", the automatic gain control (AGC) processing is not performed.

[0046] When the processing state "AGC off" is set (in step 56, "AGC off"), it is determined whether the measurement signal S input to the MCU 34 is equal to or greater than the AGC on level S AGC_ON (step 57). When the moving speed of the wire rope 1 is only a speed that outputs a weak measurement signal S, the difference between the damage signal 17A and the strand noise signal 17B does not occur or occurs less likely. In this case, the AGC processing is skipped (NO in step 57, step 54).

[0047] When the moving speed of the wire rope 1 increases, the measurement signal S increases (see FIG. 4). When the measurement signal S is equal to or greater than the AGC on level S AGC_ONIf the above conditions are met (YES in step 57), the processing state is switched from "AGC off" to "AGC on," and the automatic gain control process begins (steps 58, 59). The automatic gain control process is performed when the processing state is "AGC on" or "transitioning to AGC off" ("AGC on" or "transitioning to AGC off" in step 56, step 59).

[0048] Referring to Figure 7, if the processing state is "AGC On" (AGC On in step 61), the measurement signal S is at the AGC off level S. AGC_OFF The following conditions apply, and the set gain G is the maximum gain G MAX It is determined whether the value has reached the maximum gain G (step 62). This is because the measurement signal S is reduced by slowing down the movement speed of the wire rope 1 being inspected, and the set gain G is reduced by the automatic gain control process described in detail below. MAX This indicates that the speed has been raised to the point where the movement speed of wire rope 1 is continuously decreasing (typically at the end of the inspection of wire rope 1). AGC_OFF The following conditions apply, and the set gain G is equal to the maximum gain G. MAX If this is reached, the processing state is switched from "AGC On" to "Transitioning to AGC Off" (YES in step 62, step 64), and the gain is reduced by a predetermined value, for example, 100 ("Transitioning to AGC Off" in step 66, step 69). Gradually reducing the set gain G is equivalent to suddenly turning off the AGC process (or the maximum gain G MAX Initial gain G INI This is to avoid a sudden drop in gain, which would generate a large amount of noise and cause the processing state to be set to "AGC ON" again (YES in step 63, processing in step 65, described later).

[0049] When the wire rope 1 is moving at a predetermined speed or higher, the measurement signal S is at the AGC off level S. AGC_OFF In summary, the set gain G is the maximum gain G. MAXIt is less than (NO in step 62, "AGC ON" in step 66). In this case, automatic gain control is performed. The measured signal S is set to the target level S. TG The target gain to achieve this is determined (step 67), and the current set gain G is increased or decreased within a range of up to 100 so that it approaches the target gain (step 68). The increased or decreased new set gain G is set in the first and second PGA31 and 33, and the signal is amplified under the new set gain G (steps 72, 54). Even if the measurement signal S increases or decreases due to an increase or decrease in the speed of the wire rope 1, the signal output from the signal control device 30 is at the target level S. TG It is controlled to maintain a constant level accordingly (see Figure 8).

[0050] If damage is present in the wire rope 1, a high-level measurement signal S is output from the sensor coil 17 (see damage signal 17A in Figure 3). When a high-level measurement signal S is given, the measurement signal S is set to the target level S TG A relatively large value (a negative value) is calculated as the target gain to achieve this, but since the range of increase or decrease of the set gain G is fixed at a maximum of 100 (step 68), the set gain G will not fluctuate beyond 100. In other words, noise will not be generated by a large temporary gain fluctuation. After the detection of the damaged signal 17A, the range of increase or decrease of the set gain G gradually decreases as the normal strand noise signal 18A follows.

[0051] When the processing state is changed to "Transitioning to AGC" and the set gain G is reduced by a predetermined value (for example, 100) (steps 64, 66: "Transitioning to AGC Off", step 69), the set gain G reduced by the predetermined value, for example, 100, becomes the initial gain G INI It is determined whether the target has been reached (step 70). The set gain G is reduced by 100 each time, and the initial gain G INI When this is reached, the processing state is switched from "Transitioning to AGC Off" to "AGC Off" (Step 71).

[0052] The reduced set gain G is equal to the initial gain GINI If the target has not yet been reached (NO in step 70), the reduced setting gain G is set to the first and second PGA31 and 33 and AGC processing is performed again (steps 72, 54, 55, 56 "Transitioning to AGC off", step 59).

[0053] As the speed of the wire rope 1 is being reduced as the test is completed, i.e., when the processing state is "transitioning to AGC off", the measurement signal S generally gradually weakens, and the level of the measurement signal S reaches a predetermined target level S. TG It becomes less than (NO in step 63). The set gain G is equal to the initial gain G. INI The gain reduction by a predetermined value is repeated until it reaches (steps 69, 70). If the movement speed of the wire rope 1 is increased while the processing state "transitioning to AGC off" is in progress, the measurement signal S reaches the target level S. TG If the above occurs, the processing state is switched back from "Transitioning to AGC Off" to "AGC On" (YES in step 63, step 65). Automatic gain control can be continued if the movement speed of wire rope 1 is temporarily slowed down but then increased again.

[0054] Maximum gain G MAX The initial gain is 6000, G INI If the value is 500, the process will loop approximately 55 times from "AGC On" through "Transitioning to AGC Off" to "AGC Off".

[0055] The gain control in the signal control device 30 described above utilizes the strand noise signal 17B generated by the periodic irregularities on the surface of the wire rope 1. While the strand noise signal 17B is an unwanted signal when focusing on the detection of the damage signal 17A, it is effectively utilized to eliminate fluctuations in the amplitude of the output signal due to speed fluctuations of the wire rope 1 (to keep the signal amplitude constant regardless of speed). The strand noise signal 17B detected by the sensor coil 17 becomes smaller as the distance L between the two magnetic poles 13 and 14 increases, and larger as they get closer. On the other hand, the damage signal 17A is based on the leakage flux generated by the polarization of the damaged (broken) location into an S pole and an N pole, so the magnitude of the damage signal 17A is not related to the distance L between the magnetic poles. Preferably, a distance L is secured between the magnetic poles 13 and 14 such that the signal ratio (S / N ratio) of the damage signal 17A to the strand noise signal 17B is approximately 3.

[0056] In the above-described embodiment, an example was explained in which both the damage signal 17A and the strand noise signal 17B are detected by a single sensor coil 17. However, it is also possible to provide two sensor coils: one for detecting the damage signal 17A and another for detecting the strand noise signal 17B. The sensor coil for detecting the damage signal 17A is preferably placed midway between the magnetic poles 13 and 14 to cancel out the influence of the magnetic poles 13 and 14 on the magnetic flux generated at the damaged area. On the other hand, the sensor coil for detecting the strand noise signal 17B can be placed near either of the magnetic poles 13 or 14 without any problem. When providing two sensor coils, they can be arranged so that they do not physically interfere with each other. [Explanation of Symbols]

[0057] 1 Wire rope 2 strands 3 strands 11,12 Magnets 13,14 magnetic pole 15 Back yoke 17 Sensor coil 17A damage signal 17B Strand noise signal 30 Signal control device 31. First PGA (amplifier) 33. Second PGA (amplifier) 34 Microcontrollers (Gain Controllers)

Claims

1. A magnetization detector comprising a magnetizer having a pair of magnetic poles spaced apart, and a sensor coil positioned between the pair of magnetic poles and having periodic irregularities on its surface for detecting leakage magnetic flux generated from a wire rope magnetized by the magnetizer, is provided with an output signal from the sensor coil, and an amplifier is provided to amplify the output signal from the sensor coil, and The system includes a gain controller that controls the amplifier's setting gain to maintain the level of the unevenness output signal, which is caused by surface irregularities of the wire rope, at a predetermined target level among the output signals of the sensor coil. Signal control device.

2. The above wire rope is constructed by twisting together multiple strands, each strand being made by twisting together multiple metal wires. The signal control device according to claim 1.

3. The above gain controller, A target gain calculation means for calculating a target gain to bring the level of the measurement signal, which is amplified by the amplifier, from the uneven output signal of the sensor coil to the target level, and The system includes a setting gain increase / decrease means for increasing or decreasing the setting gain by a predetermined amount so as to approach the target gain. The signal control device according to claim 1.

4. The above gain controller, It is possible to switch between an off state where gain control is not performed and an on state where gain control is performed. The gain controller is controlled to switch from the off state to the on state when the level of the measurement signal is above a predetermined on level that is lower than the target gain. The signal control device according to claim 1.

5. The above gain controller, It is possible to switch between an ON state in which gain control is performed, an OFF state in which gain control is not performed, and an ON-OFF transition state in which the ON state continues and the set gain is gradually reduced. When the gain controller is in the ON state, the gain controller is controlled to switch from the ON state to the ON-OFF transition state when the level of the measurement signal is below a predetermined OFF level which is lower than the target gain and the set gain has reached the maximum value of the set gain. The signal control device according to claim 1.

6. When the above-mentioned gain controller is in an on-off transition state, the gain controller is controlled so that it switches from the on-off transition state to the off state when the above-mentioned set gain reaches the initial gain. The signal control device according to claim 5.

7. When the gain controller is in an on-off transition state, it is controlled to return from the on-off transition state to the on state when the level of the measurement signal is equal to or greater than the target level. The signal control device according to claim 5.

8. A program for controlling a signal control device, which is used with a magnetization detector that includes a magnetizer having a pair of magnetic poles spaced apart, and a sensor coil positioned between the pair of magnetic poles and having a periodic surface irregularity for detecting leakage magnetic flux generated from a wire rope magnetized by the magnetizer, and which includes an amplifier for amplifying the output signal output from the sensor coil, The amplifier's setting gain is controlled so that the level of the unevenness output signal, which is caused by the unevenness on the surface of the wire rope, is maintained at a predetermined target level among the output signals of the sensor coil. Gain control program.

9. A magnetizer having a pair of magnetic poles spaced apart, and a magnetization detector having a sensor coil positioned between the pair of magnetic poles and having periodic irregularities on its surface for detecting leakage magnetic flux generated from a wire rope magnetized by the magnetizer, A signal control device comprising an amplifier for amplifying the output signal output from the sensor coil, and a gain controller for controlling the setting gain of the amplifier to maintain the level of the unevenness output signal, which is caused by the unevenness on the surface of the wire rope, at a predetermined target level, among the output signals of the sensor coil, and A threshold level is set for levels exceeding the above target level, and the device is equipped with a damage determination device that determines the damage to the wire rope based on a damage signal that exceeds the threshold level generated from the damaged part of the wire rope. Wire rope tester.

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