CN115479985A - Wire rope flaw detection device - Google Patents

Abstract

The invention provides a wire rope flaw detector which can detect the occurrence of wire breakage outside or in the deep of a directional region based on a slightly leaked magnetic signal even if the wire rope flaw detector is a directional magnetic sensor. A wire rope flaw detector that detects damage to a wire rope, the wire rope flaw detector comprising: a magnetizer forming a magnetic path in a predetermined section of the wire rope; a magnetic sensor that is magnetically insulated from the magnetizer and is capable of detecting leakage magnetic flux from a damaged portion of the wire rope; a ferromagnetic body that changes the direction of leakage magnetic flux generated by damage to a wire of a wire rope placed in the magnetic circuit, and concentrates the leakage magnetic flux on the magnetic sensor; a signal collection unit that collects a magnetic signal of a magnetic sensor that detects the leakage magnetic flux; and a signal processing unit for calculating a damage position of the wire based on the magnetic signal collected by the signal collecting unit, wherein the magnetic sensor is disposed between a wire rope placed in the magnetic circuit and the ferromagnetic body.

Description

Wire rope flaw detection device

Technical Field

The present invention relates to a wire rope flaw detector for inspecting a deterioration state of a wire rope made of a magnetic metal material.

Background

As an inspection technique of a hoisting rope applied to safety monitoring of an elevator, there is known a present apparatus for detecting a breakage of a rope wire based on a leakage magnetic flux generated by a wire rope placed in a magnetic circuit (for example, patent document 1). A wire rope used as a hoisting rope of a car of an elevator is formed by twisting wires made of a magnetic metal material. As a magnetic sensor suitable for the inspection of the wire rope, a small coil or a hall element is used.

Further, a leakage magnetic flux detection device is known in which a ferromagnetic body is disposed near a magnetic sensor for detecting a defect in a metal duct wall, thereby detecting a minute defect (for example, patent document 2). The device has the following effects: the magnetic flux selectively passes through the ferromagnetic body as compared with the space around the ferromagnetic body placed in the magnetic field, whereby a minute magnetic signal of the metal conduit wall can be detected.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 6715951

Patent document 2: japanese patent laid-open publication No. 2002-156365

Disclosure of Invention

Problems to be solved by the invention

In the technique disclosed in patent document 1 or the like, in order to increase the signal intensity of the leakage flux, a method of applying an excessive saturation magnetic field to an inspection object has a risk of magnetic adhesion of a plurality of steel cords to each other due to residual magnetism generated in the magnetic metal steel cord. Further, since the wire breakage occurring in the deep portion of the wire rope is distant from the magnetic sensor located on the outer peripheral side of the wire rope, the detectable signal is small. In addition, in the technique disclosed in patent document 2, it is difficult to determine the position of the wire breakage in the direction of the wire rope looping.

Further, in recent years, there have been variations in industrial structures, and it has been difficult to purchase a small coil as a device suitable for a magnetic sensor, and there is a tendency to rely on a hall element which is easily supplied. However, the detection sensitivity characteristic of a magnetic sensor having strong directivity, such as a hall element, is more sensitive to the presence of leakage flux at the closest point along the directivity than a small-sized coil, but is more disadvantageous as the distance from the object deviated from the region is longer. Therefore, the magnetic sensor having directivity as a wire rope flaw detector has a drawback that it is not necessarily suitable for use in detecting a wire breakage outside or in the deep of the direction-finding region.

The present invention has been made in view of the above problems, and an object thereof is to provide a wire rope flaw detector capable of detecting occurrence of a wire breakage outside or in a deep portion of a directional region based on a magnetic signal that leaks minutely even in a magnetic sensor having directivity.

Means for solving the problems

The present invention for solving the above problems is a wire rope flaw detector for detecting damage to a wire rope, the wire rope flaw detector including: a magnetizer forming a magnetic path in a predetermined section of the wire rope; a magnetic sensor that is magnetically insulated from the magnetizer and is capable of detecting leakage magnetic flux from a damaged portion of the wire rope; a ferromagnetic body that changes the direction of leakage magnetic flux generated by damage to a wire of a wire rope placed in the magnetic circuit, and concentrates the leakage magnetic flux on the magnetic sensor; a signal collection unit that collects a magnetic signal of a magnetic sensor that detects the leakage magnetic flux; and a signal processing unit that calculates a damage position of the wire based on the magnetic signal collected by the signal collecting unit, wherein the magnetic sensor is disposed between a wire rope placed in the magnetic circuit and the ferromagnetic body.

Effects of the invention

According to the present invention, it is possible to provide a wire rope flaw detector capable of detecting occurrence of a wire breakage outside or in a deep part of a directional region based on a magnetic signal that is leaked to a small extent even in a magnetic sensitive element having directivity.

Drawings

Fig. 1 is a cross-sectional view of a wire rope flaw detector according to an embodiment of the present invention (hereinafter, also referred to as "the present apparatus") in which an axis of a sensor unit is orthogonal (in a direction in which a wire rope is cut into a circular piece).

Fig. 2 is an orthogonal cross-sectional view of sensor portions facing each other at different circumferential pitches with the number ratio of the wire harness to the magnetic sensors set to 8 to 9.

Fig. 3 is a functional block diagram showing the configuration of a signal processing unit and the like of the present apparatus configured by connecting the sensor units shown in fig. 1 and 2.

Fig. 4 is an orthogonal cross-sectional view of the sensor unit of example 1 in which the sensor unit of fig. 1 is modified.

Fig. 5 is an orthogonal cross-sectional view of a sensor part of example 2 in which the sensor part of fig. 1 is modified.

Fig. 6 is an orthogonal cross-sectional view of a sensor portion of example 3 in which the sensor portion of fig. 1 is modified.

Fig. 7 is an orthogonal cross-sectional view of the sensor part of example 4 in which the sensor part of fig. 1 is modified, and an axial cross-sectional view schematically illustrating a state in which a magnetic flux is simulated.

Fig. 8 is a graph showing detection sensitivity characteristics of the hall element.

Fig. 9 is a graph showing the sensitivity of the sensor section for detecting a broken wire of the wire rod, and shows the difference between the sensor output for 1ch to 4ch and the condition with a nonmagnetic material (magnetic material).

Fig. 10 is an orthogonal cross-sectional view of a sensor portion of a comparative example to that of fig. 7 and an axial cross-sectional view illustrating a state in which a magnetic flux is simulated.

In the figure:

1-wire rope flaw detector (this device); 2-steel wire rope; 3-a magnetic sensor; 4. 4A to 4D — ferromagnetic bodies (ferromagnetic raw material, ferromagnetic sheet); 5-a magnetic sensor circuit; 7-a signal analysis section; 8-a data display; 9-a data input; 10-a power supply; 11-a control circuit; 12-a magnetic signal amplifier; 13-a filter circuit; 12-a magnetic signal amplifier; 16-an/D converter; 17-a signal collector; 18-a signal processor; 20. 20AX, 20A to 20E-sensor section; 21-outer protective cover; 22-inside protective cover; 23-a wire harness; 24-a wire; 28- (near the magnetic sensor 3) top break; 29-the bottom (remote from the magnetic sensor 3) is broken.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The steel cord 2 illustrated in fig. 1, 2, 4 to 7, and 10 has eight wire harnesses 23 circumferentially arranged around the outer periphery without gaps, and the entire steel cord including the eight wire harnesses 23 is twisted into one. The wire rope 2 having such a composition is merely an example of the inspection object of the present apparatus 1 (fig. 3). In the drawings, the same reference numerals are given to the same portions having the same effects, and the repetition of the description is avoided.

In addition, with respect to the sensor portions 20A, 20AX, 20AY, and 20B to 20D (collectively 20) of the present apparatus 1, fig. 4 shows the sensor portion 20B of embodiment 1, fig. 5 shows the sensor portion 20C of embodiment 2, fig. 6 shows the sensor portion 20AY of embodiment 3, and fig. 7 shows the sensor portion 20D of embodiment 4. On the other hand, fig. 10 shows a sensor portion 20E of a comparative example. The longitudinal direction of the cord is referred to as the axial direction, and the direction in which the cord is cut into circular pieces is referred to as the direction perpendicular to the axis.

Fig. 1 is an orthogonal cross-sectional view of a sensor unit 20A provided in the present apparatus 1. Fig. 2 is an orthogonal cross-sectional view of the sensor portion 20AX facing at different circumferential pitches with the number ratio of the wire harness 23 to the magnetic sensors 3 being 8 to 9. The vicinity of the outer periphery of the wire rope 2 is surrounded by a plurality of strands 23 stranded by bundling wires 24. The sensor portions 20A and 20AX include a magnetic sensor 3, a ferromagnetic sheet 4A (an embodiment of the ferromagnetic body 4), an outer protective cover 21 (not shown in fig. 2), and an inner protective cover 22.

One wire rope 2 is formed of a plurality of wire rods 24, and even if one of the wire rods 24 has a broken portion, the function required for the present apparatus 1 is to reliably detect the broken portion. The magnetizer, not shown, forms a magnetic path in a predetermined section of the wire rope 2. The magnetic sensor 3 is magnetically insulated from the magnetizer and is circumferentially disposed along the cross-sectional outer circumference of the wire rope 2. When the broken wire 24 is a bottom break 29 (fig. 5, 7, and 10) located at a position distant from the magnetic sensor 3, the leakage magnetic flux of the broken wire 24 hardly reaches the magnetic sensor 3 at a distance, and thus the possibility of detection is low.

On the other hand, if no measure is taken, the wire rope flaw detector has low sensitivity and is kept to be less reliable. On the other hand, it is known that magnetic flux tends to be absorbed by a ferromagnetic body having a high magnetic permeability. Therefore, it is considered that the ferromagnetic material pieces 4A formed in a sheet shape function to absorb leakage magnetic flux generated in the vicinity of the broken portion of the wire 24. The present apparatus 1 applies this action to find a positional relationship in which the proportion of the magnetic flux input to the magnetic sensor 3 is increased, and brings the ferromagnetic material piece 4A close to the magnetic sensor 3. As a result, the present apparatus 1 can improve the sensitivity to the bottom fracture 29.

The wire rope 2 is inserted into the ring of the annular sensor unit 20 and inspected. However, it is very difficult to insert and inspect the wire rope 2 in the elevator in operation after completion to the closed loop-shaped sensor unit 20, and then to separate the wire rope therefrom. Therefore, as an actual inspection, the ring-shaped or cylindrical sensor portion 20 is divided into two parts and the wire rope 2 is clamped between the opened inner sides, and then the closed loop is restored to the original closed loop and the inspection is performed. The sensor portion 20A can be divided or combined by a broken line YY (not shown in fig. 2 and 6). Such detailed description of the dividing mechanism is omitted.

Examples of the magnetic sensor 3 include a TMR (Tunnel Magneto resistance) sensor, an AMR (Anisotropic Magneto resistance) sensor, a GMR (Giant Magneto resistance effect) sensor, and a detection coil, in addition to the hall element. The arrangement of the magnetic sensors 3 constituting the sensor unit 20 may be considered to be different from the optimum arrangement depending on the type of the magnetic sensor 3.

In this arrangement, it is preferable that a plurality of the magnetic sensors 3 are arranged at predetermined intervals (pitches) around the outer periphery of the wire rope 2 in order to efficiently detect the broken portion of the wire 24. The arrangement of the magnetic sensors 3 capable of detecting the bottom fracture 29 located far from the magnetic sensor 3 with high sensitivity will be described later with reference to fig. 5, 7, and 10.

As hall elements constituting the magnetic sensor 3 of the actual sensor unit 20, eight (fig. 1, 5, 7, and 10) or nine (fig. 2) ring-shaped sensor groups are formed in a row around the outer periphery of the wire rope 2 at equal intervals. Two rows of annular sensor groups may be axially offset and coaxially adjacent to each other (fig. 6 and 10). The more densely the magnetic sensors 3 constituting the sensor unit 20 are so arranged as to cover the broken portions of the wire 24, the more accurate the detection becomes. In practice, the sensor portion 20 is designed efficiently to the necessary minimum.

Fig. 3 is a functional block diagram showing the configuration of a signal processing unit and the like of the present apparatus 1 configured by connecting the sensor units 20 of fig. 1 and 2. As shown in fig. 3, the present apparatus 1 includes a sensor unit 20, a magnetic sensor circuit 5, a signal analysis unit 7, a data display unit 8, and a data input unit 9. The data input unit 9 has an operation panel (not shown) connected to the power supply 10 and the control circuit 11, and the user operates the operation panel to control the apparatus 1. The control circuit 11 controls the magnetic sensor circuit 5 and the signal analysis unit 7. The data display section 8 clearly displays the detected broken portion of the wire 24.

Fig. 3 representatively shows only the amounts of two paths (channels, hereinafter also referred to as "ch") corresponding to the two magnetic sensors 3. However, as described above, the magnetic sensors 3 constituting the actual sensor unit 20 are 8, 16, and 24ch (9 ch in fig. 1 only) which are substantially integral multiples of the eight wire harnesses 23. The magnetic signal detected by the magnetic sensor 3 is amplified by removing noise in the magnetic sensor circuit 5, and is output to the signal analysis unit 7.

The magnetic sensor circuit 5 has a magnetic signal amplifier 12 and a filter circuit 13. The magnetic signal amplifier 12 amplifies the output signal from the magnetic sensor 3. The filter circuit 13 performs a normal analog filter process on the output signal amplified by the magnetic signal amplifier 12, and outputs an analog signal. In the analog filtering process, noise components are removed except for commercial frequencies, and only a desired frequency range is passed.

In this way, the magnetic sensor circuit 5 performs analog processing on the magnetic detection signal output from the magnetic sensor 3, and outputs the analog magnetic signal to the signal analysis unit 7. The signal analysis unit 7 includes an a/D converter 16, a signal acquisition unit 17, and a signal processor 18. The a/D converter 16 converts the analog magnetic signal output from the magnetic sensor circuit 5 into a digital signal, and outputs to the signal collector 17. The signal processor 18 is a single chip microcomputer or a general-purpose computer (hereinafter also referred to as "PC 18").

The PC18 reads out and executes a program stored in a memory or a storage by a CPU (Central Processing Unit), and stores the digital magnetic signal output from the a/D converter 16 in the signal acquisition Unit 17 or the like. The signal analysis unit 7 may be a dedicated device, or may be realized by extending the functions of the PC18 beyond the range shown in fig. 3.

When the signal analysis unit 7 is the PC18, the processing of the signal analysis unit 7 can be realized by program processing in the PC18, and the data display unit 8 and the data input unit 9 may be devices related to the PC18 such as a keyboard and a liquid crystal display. Fig. 3 is merely an example, and any functional configuration may be modified in the middle of signal processing from the magnetic sensor 3 to the data display unit 8 as long as the function of the present apparatus 1 can be achieved.

[ example 1]

Fig. 4 is an orthogonal axis cross-sectional view of a sensor unit 20B of example 1 in which the sensor unit 20A of fig. 1 is modified, and the main part is enlarged and the same contents are omitted. The sensor portion 20B of example 1 shown in fig. 4 emphasizes the magnetic sensors 3 associated one-to-one with the wire harnesses 23 and the sheet-like ferromagnetic body pieces 4B (embodiments of the ferromagnetic bodies 4) associated one-to-one with the magnetic sensors 3.

On the other hand, the ferromagnetic sheet 4A illustrated in fig. 1 and 2 is rounded to be formed in a ring shape or a cylindrical shape, and continuously covers the magnetic sensors 3 of 8ch or 9 ch. As in the example of fig. 1 and 2, the magnetizer not shown in example 1 forms a magnetic path in a predetermined section of the wire rope 2. The magnetic sensor 3 is magnetically insulated from the magnetizer and is disposed at a position facing the outer periphery of the wire rope 2. The ferromagnetic body sheet 4B functions to absorb magnetism generated in the vicinity thereof.

In embodiment 1 of fig. 4, the magnetic sensor 3 can monitor the wire harness 23 located in the detection area of directivity spreading forward thereof. The leakage magnetic flux generated when the wire 24 is broken in the wire bundle 23 in the detection region is oriented so as to be absorbed into the ferromagnetic sheet 4B. If the directivity region of the magnetic sensor 3 is expanded in the middle of the orientation, the leakage magnetic flux generated by the broken wire 24 can be detected with high sensitivity.

When the broken wire rod 24 is located at a position distant from the magnetic sensor 3, if the ferromagnetic body 4B is not present, the ratio of the leakage magnetic flux of the broken wire rod 24 to be detected by the magnetic sensor 3 is small. The ferromagnetic body 4 (including other examples) having high magnetic permeability has a characteristic of attracting magnetic flux, and in the magnetic sensor 3 in contact with the ferromagnetic body 4B, the proportion of the magnetic flux attracted and input by the ferromagnetic body 4B increases. As described above, the present apparatus 1 of example 1 shown in fig. 4 can efficiently acquire the leakage magnetic flux generated from the broken wire 24 of the wire rope 2 to be analyzed by the magnetic sensor 3, and can analyze the deterioration state of the wire rope 2 with high accuracy.

[ example 2]

Fig. 5 is an orthogonal cross-sectional view of a sensor portion 20C of example 2, which is a modification of the sensor portion 20A of fig. 1. As shown in fig. 5, the ferromagnetic sheet 4 has a simultaneous arch shape folded back with legs attached to the back of the magnetic sensor 3. Such a simultaneous arch-shaped ferromagnetic material piece 4C (embodiment of ferromagnetic material 4) captures a weak magnetic signal like a parabolic antenna, and turns back with legs attached to the back of magnetic sensor 3, thereby allowing magnetic flux to pass through from the front of magnetic sensor 3 to the back in a concentrated manner. As a result, the ferromagnetic sheet 4C exhibits an effect of being able to detect, with higher sensitivity, either the top fracture 28 near the magnetic sensor 3 or the bottom fracture 29 far from the magnetic sensor 3, as compared with the case without this.

[ example 3]

Fig. 6 is an orthogonal cross-sectional view of a sensor unit 20AY of example 3, which is a modification of the sensor unit 20A of fig. 1. The hall elements of the magnetic sensor 3 constituting the sensor unit 20AY are eight hall elements which are arranged in a row around the outer periphery of the wire rope 2 at equal intervals to form a ring-shaped sensor group, and the two rows are axially shifted and coaxially adjacent to each other. The sensor unit 20AY in fig. 6 can be divided or combined by a broken line YY.

The greater the number of magnetic sensors 3 constituting the sensor unit 20, the more the number of magnetic sensors can cover the broken portion of the wire 24, the more accurate the detection can be performed. In practice, the sensor portion 20 (including other examples) is designed efficiently to the minimum necessary. Therefore, the sensor unit 20AY in fig. 6 may be configured such that eight magnetic sensors 31 to 34, 35 to 38 are arranged in two rows on the inner circumferential surface of only one half of the dividing mechanism.

Alternatively, the sensor unit 20AY in fig. 6 may be formed not by one half of the dividing mechanism but by sixteen magnetic sensors that are twice as many as the magnetic sensors 31 to 34 and 35 to 38, which are provided around the entire inner peripheral surfaces of both the sensors. In this configuration, the ferromagnetic sheet 4A exhibits an effect of being able to detect, with higher sensitivity, either the top fracture 28 near the magnetic sensor 3 or the bottom fracture 29 far from the magnetic sensor 3, as compared with the case without this.

Next, the results of performing magnetic simulation on the sensor unit 20D of example 4 shown in fig. 7, the sensor unit 20E of the comparative example shown in fig. 10, and the flaw detection test of each wire rope will be described with reference to fig. 8 and 9. The example 4 (fig. 7) is different from the comparative example (fig. 10) in the presence or absence of the ferromagnetic body 4D (embodiment of the ferromagnetic body 4), and the example 4 including the magnetic body 4D is more preferable (see G3 and G4 in fig. 8).

[ example 4]

Fig. 7 is an orthogonal cross-sectional view of a sensor portion 20D of example 4 in which the sensor portion 20A of fig. 1 is modified, and an axial cross-sectional view schematically illustrating a state of a magnetic flux MF. As shown in fig. 7, the magnetic flux MF is a leakage magnetic flux generated by the top break 28. The magnetic sensors 31 to 34 8230are disposed in a posture facing the axial center from the outer periphery of the wire rope 2 because they have directivity in front. The magnetic sensors 31 to 34 \8230thathave no directivity at the rear and have ferromagnetic bodies 4D attached to the respective rear surfaces.

The ferromagnetic sheet 4A of example 1 shown in fig. 1 and 2 is annular or cylindrical, and continuously covers the 8ch magnetic sensor 3. In contrast, the ferromagnetic sheet 4B illustrated in fig. 4 is different in that it is associated with the magnetic sensors 3 in a one-to-one manner. The simulation of example 4 shown in the lower part of fig. 7 can confirm that the magnetic flux MF passing through the center part of the magnetic sensor 3 is larger than the simulation of the comparative example shown in the lower part of fig. 10.

Fig. 8 is a graph showing detection sensitivity characteristics of the hall element. The graph of fig. 8 shows the distance (mm) between the sensor and the magnet on the horizontal axis and the signal (mT) detected by the hall element on the vertical axis. As shown in the graph, since the detection output is approximately inversely proportional to the square of the distance, in the sensor unit 20 of the present apparatus 1, the top fracture 28 closer to the detection target on the magnetic sensor 3 is detected with higher sensitivity than the bottom fracture 29 farther from the detection target.

Fig. 9 is a graph showing the sensitivity of the sensor unit 20 for detecting a wire breakage, and shows the difference between the sensor output for 1ch to 4ch and the condition with the presence of the nonmagnetic material (magnetic material) 4D. The magnetic sensors 31 to 34 of the sensor unit 20E of the comparative example of fig. 10, which has no magnetic material, i.e., no ferromagnetic material attached to the left side of fig. 9, are classified into points ch1 to ch 4. The results of example 3 of fig. 7 having a magnetic material on the right side of fig. 9, that is, a ferromagnetic material 4D added thereto are shown for the magnetic sensors 31 to 34 corresponding to ch1 to ch 4.

As shown in G3 and G4, the magnetic sensor 32 of the sensor unit 20D of fig. 7 detects with high sensitivity the leakage magnetic flux of the wire 24 that is broken by the top break 28 at a close position. Further, since the magnetic flux tends to be absorbed by the ferromagnetic material 4D having a high magnetic permeability, when the ferromagnetic material sheet 4D comes into contact with the magnetic sensor 32, the proportion of the magnetic flux input to the magnetic sensor 32 increases. Therefore, the presence of the ferromagnetic sheet 4D in the top break 28 makes the magnetic sensor 32 having directivity in the front direction detect more strongly.

On the right side of fig. 9, ch4 is the output of the magnetic sensor 34 regardless of the disconnection, and therefore the output is the minimum. ch3 is the output of the magnetic sensor 33 adjacent to the top break 28 at a small angle, and therefore the output is larger than ch 4. ch1 is the output of the magnetic sensor 31 that captures the bottom break 29 in the directional region, and therefore the output is greater than ch 3. When comparing left and right for each ch in fig. 9, that is, comparing the presence or absence of the ferromagnetic body 4D (magnetic material), the output of the ferromagnetic body 4D (magnetic material) is large for each of ch1 to ch3 that are effective for detection.

[ comparative example ]

Fig. 10 is an orthogonal cross-sectional view of a sensor portion 20E of a comparative example, which is compared with the sensor portion 20D of fig. 7, and an axial cross-sectional view schematically illustrating a state in which a magnetic flux is simulated. As described above, in fig. 9, if the left side G1, G2 and the right side G3, G4 are compared, it can be clearly confirmed that the outputs of G1, G2 without the ferromagnetic body 4D (magnetic material) are small. The simulation of the comparative example shown in the lower part of fig. 10 can confirm that the magnetic flux MF passing through the center part of the magnetic sensor 3 is smaller than the simulation of the example 4 shown in the lower part of fig. 7. In the sensor unit 20E of fig. 10, sixteen magnetic sensors including the magnetic sensors 31 to 34 and 35 to 38 are disposed so as to surround the entire inner circumferential surface densely, thereby compensating for the lack of sensitivity of the respective magnetic sensors.

The wire rope flaw detector (present apparatus) 1 according to the embodiment of the present invention can be summarized as follows.

[1] As shown in fig. 1 to 3, the present apparatus 1 is a wire rope flaw detector 1 that includes a magnetizer (not shown), a magnetic sensor 3, a ferromagnetic body 4, a signal collection unit 5, and a signal processing unit 7 and detects damage to a wire rope 2.

The magnetizer forms a magnetic path in a predetermined section of the wire rope 2. The magnetic sensor 3 is provided so as to surround the magnetizer so as to be magnetically insulated from the magnetizer, and is disposed at a position facing the outer periphery of the wire rope 2, and is capable of detecting leakage flux from a damaged portion of the wire rope 2. The ferromagnetic body 4 disposed on the opposite side of the wire rope 2 changes the direction of the leakage magnetic flux generated by the breakage of the wire 24 of the wire rope 2 placed in the magnetic circuit, and concentrates the leakage magnetic flux on the magnetic sensor 3.

The signal collection unit 5 collects a magnetic signal from the magnetic sensor 3 that detects the leakage magnetic flux. The signal processing unit 7 calculates the fracture position of the wire 24 based on the magnetic signal collected by the signal collection unit 5. The magnetic sensor 3 is disposed so as to be sandwiched between the wire rope 2 and the ferromagnetic body 4 placed in the magnetic circuit. The present device 1 can detect the occurrence of a wire breakage (bottom breakage 29) outside or in a deep part of the direction-finding region based on a magnetic signal that leaks slightly, even if the magnetic sensor (magnetic sensor 3) is a magnetic sensitive element such as a hall element 3 having directivity. Even with a directional magnetic induction element, it is possible to detect the cutting of the wire 24 outside the directional region or in the deep portion of the wire rope 2 based on a slightly leaked magnetic signal.

[2] In the above [1], the plurality of strands 23 twisted by bundling the wires 24 may be opposed to the magnetic sensors 3 at different circumferential pitches. Even if the magnetic sensor 3 has a sharp and small directivity, the facing postures of the magnetic sensor 3 close to the tangent of the wire harness 23 and the magnetic sensor 3 far from the wire harness 23 are not uniform and vary widely, and therefore a wide range of objects is covered. In other words, the possibility that the broken position of the wire 24 can be captured is increased in the high-sensitivity directional capture range extending forward from the center of the magnetic sensor 3.

As shown in fig. 2, if the number of the wire harnesses 23 and the magnetic sensors 3 is set at a ratio of 8 to 9, a face posture rich in variation can be realized. For example, in the sensor portion 20AX configured by combining nine magnetic sensors 3, which approach the minimum, in a ring shape in a row, with respect to the eight normal wire harnesses 23, there is an effect that any one of the top fracture 28 that approaches the magnetic sensor 3 and the bottom fracture 29 that is distant from the magnetic sensor 3 can be detected with high sensitivity.

[3] In the above [1], the outer periphery of the wire rope 2 is surrounded by a plurality of strands 23 twisted by bundling wires 24. The magnetic sensors 3, the number of which is an integral multiple of one or more times the number of the harnesses 23, are aligned so as to be close to the respective tangents of the harnesses 23. In the present apparatus 1 having such a configuration, the directivity region of the magnetic sensor 3 is efficiently spread forward.

Therefore, the leakage magnetic flux generated by the breakage of the wire 24 of the wire rope 2 is easily captured by both the top break 28 close to the magnetic sensor 3 and the bottom break 29 far from the magnetic sensor 3. As a result, the present apparatus 1 can obtain an effect of detecting with high sensitivity.

[4] In [3] above, as shown in fig. 10, the number of the magnetic sensors 3 with respect to the harnesses 23 is an integral multiple of two or more times, and the magnetic sensors 3 positioned close to the respective tangents of the harnesses 23 and the magnetic sensors 3 positioned far from the respective tangents of the harnesses 23 may be mixed.

The directivity region of the magnetic sensor 3 close to the tangent of the wire harness 23 and the directivity region of the magnetic sensor 3 far from the tangent of the wire harness 23 face each other more densely, and therefore the present apparatus 1 having such a structure encompasses an object over a wide range. Therefore, the leakage magnetic flux generated by the breakage of the wire 24 of the wire rope 2 is easily captured by both the top break 28 close to the magnetic sensor 3 and the bottom break 29 far from the magnetic sensor 3. As a result, the present apparatus 1 can obtain an effect of being able to perform detection with high sensitivity.

[5] In [4] above, as shown in fig. 1, 2, 5, and 6, the ferromagnetic body 4 is formed as a sheet-shaped ferromagnetic body sheet 4, and covers the back of the magnetic sensor 3 that is circumferentially disposed at a position that can face the outer periphery of the wire rope 2. The sheet-like ferromagnetic sheet 4 for such applications can be easily manufactured by supplying and processing the corresponding components.

When viewed from the magnetic sensor 3, the ferromagnetic body 4 disposed on the opposite side of the wire rope 2 changes its direction and concentrates on the magnetic sensor 3 to absorb the leakage magnetic flux generated by the breakage of the wire 24 of the wire rope 2 placed in the magnetic circuit. The present apparatus 1 having such a configuration can obtain an effect of being able to detect with high sensitivity either the top fracture 28 approaching the magnetic sensor 3 or the bottom fracture 29 distant from the magnetic sensor 3.

[6] In the above [5], as shown in fig. 5, the ferromagnetic sheet 4 may be a simultaneous arch shape folded back with a leg attached to the back of the magnetic sensor 3. The simultaneous arch-shaped ferromagnetic sheet 4C captures a weak magnetic signal as in a parabolic antenna, and turns back with a leg attached to the back of the magnetic sensor 3, thereby allowing magnetic flux to pass through from the back of the magnetic sensor 3 to the front in a concentrated manner.

As a result, the ferromagnetic sheet 4C can detect either the top break 28 close to the magnetic sensor 3 or the bottom break 29 far from the magnetic sensor 3 with higher sensitivity than the case without the same.

Here, by inverting the NS pole, the same operational effect can be obtained even if the direction of the magnetic flux is opposite. Therefore, the magnetic lines of force are concentrated along the directivity extending forward from the center of the magnetic sensor 3, and therefore the detection sensitivity can be improved.

[7] In [5] above, the ferromagnetic material sheet 4 is in the form of a coaxial cylindrical shape as shown in fig. 1 and 2, but such a corresponding member is easy to purchase and manufacture such as machining.

[8] In any of the above [1] to [8], the magnetic sensor 3 is a hall element, and the stronger the property of the ferromagnetic body 4 to absorb the leakage magnetic flux, the more preferable. Such a ferromagnetic body 4 can be located close to the back of the directivity with respect to the magnetic sensor 3 provided around the wire rope 2 at a position capable of facing the outer periphery thereof.

If the magnetic sensor 3 is a hall element, the ferromagnetic body 4 concentrates magnetic lines of force along a directivity extending forward from the center of the magnetic sensor 3. On the other hand, the ferromagnetic body 4 is deflected so as to be introduced into the magnetic induction portion of the hall element 3 while absorbing the leakage flux from the cut portion of the wire 24. In other words, the magnetic sensor 3 can easily capture the object in the directional region thereof, and thus can improve the detection sensitivity.

Possibility of industrial utilization

The present invention may be used as a wire rope flaw detector for inspecting a hoisting rope in safety monitoring of an elevator.

Claims (8)

1. A wire rope flaw detector detects damage to a wire rope,

the wire rope flaw detector is characterized by comprising:

a magnetizer forming a magnetic path in a predetermined section of the wire rope;

a magnetic sensor magnetically insulated from the magnetizer and capable of detecting leakage magnetic flux from a damaged portion of the wire rope;

a ferromagnetic body that changes a direction of leakage magnetic flux generated by damage to a wire of the wire rope placed in the magnetic circuit, and concentrates the leakage magnetic flux on the magnetic sensor;

a signal collection unit that collects a magnetic signal of the magnetic sensor that detects the leakage magnetic flux; and

a signal processing unit that calculates a damage position of the wire based on the magnetic signal collected by the signal collecting unit,

the magnetic sensor is disposed between the wire rope placed in the magnetic circuit and the ferromagnetic body.

2. The wire rope flaw detector according to claim 1,

a plurality of strands twisted by bundling the wires are made to face the magnetic sensors at different circumferential pitches.

3. The wire rope flaw detector according to claim 1,

the outer circumference of the wire rope is surrounded by a plurality of strands bundled and twisted together,

the magnetic sensors, the number of which is an integral multiple of one or more times the number of the wire harnesses, are aligned so as to be close to respective tangents of the wire harnesses.

4. The wire rope flaw detector according to claim 3,

the number of the magnetic sensors is an integral multiple of two or more times the number of the harnesses, and the magnetic sensors aligned so as to be close to the respective tangents of the harnesses and the magnetic sensors aligned so as to be distant from the respective tangents of the harnesses are mixed.

5. The wire rope flaw detector according to claim 4,

the ferromagnetic material forms a sheet-shaped ferromagnetic material sheet, and covers the back of the magnetic sensor at a position where the sheet-shaped ferromagnetic material sheet can face the outer periphery of the wire rope.

6. The wire rope flaw detector according to claim 5,

the ferromagnetic sheet has a simultaneous arch shape with legs attached to the back of the magnetic sensor and folded back.

7. The wire rope flaw detector according to claim 5,

the ferromagnetic sheet is in the shape of a coaxial cylinder.

8. The wire rope flaw detector according to any one of claims 1 to 7,

the magnetic sensor is a hall element,

the ferromagnetic body has a characteristic of absorbing the leakage magnetic flux,

and is located close to the back of the directivity of the magnetic sensor provided around the wire rope at a position capable of facing the outer periphery of the wire rope.

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