Rope damage diagnostic test device

Abstract

A rope damage diagnostic test device that detects the presence or absence of damage in a wire rope (2) around the outer circumference of which a plurality of outer layer strands (22a ... 22h) are arranged, each of the outer layer strands (22a ... 22h) having a plurality of outer layer wires (24) arranged around an outer circumference thereof, wherein: the rope damage diagnostic test device has: an ultrasound applicator (3) comprising: a magnet (7) which applies a direct current magnetic field to the wire rope (2); an excitation coil (8) which applies an alternating current magnetic field to the wire rope (2), wherein the ultrasonic applicator (3) generates ultrasonic waves in the wire rope (2) by causing the wire rope to vibrate due to the magnetostriction effect; and a detector (5) having a detection element (10) that detects changes in a propagation state of the ultrasonic waves in the wire rope (2); and the excitation coil (8) and the detection element (10) are arranged in a parallelogram which has as a first opposite side length a length of a section of the wire rope (2) in which one of the outer layer strands (22a ... 22h) makes a revolution around the wire rope (2), and which has as a second opposite side length a product of a diameter and a number of the outer layer wires (24) which are contained in one of the outer layer strands (22a ... 22h).

Description

TECHNICAL FIELD

[0001] The present invention relates to a wire rope damage diagnosis test device that detects the presence or absence of wire damage by generating ultrasonic vibrations in a wire rope through the magnetostriction effect. TECHNICAL BACKGROUND

[0002] In conventional magnetostrictive wire rope sensors, a plurality of magnets and a pair of coil assemblies are arranged so as to surround the entire circumference of a wire rope. A magnetostrictive tape is arranged between each of the coil assemblies and the wire rope.

[0003] Each of the magnets applies a direct current magnetic field to the wire rope and the magnetostrictive band. Ultrasonic waves are applied to the wire rope by applying an alternating current magnetic field using the coil assembly to vibrate the magnetostrictive band through the magnetostriction effect. Reflected ultrasonic waves caused by damage to the wire rope are detected by the coil assembly through the reverse magnetostriction effect in the magnetostrictive band (see, for example, US 8 098 065 B2).

[0004] DE 11 2008 003 813 T5 discloses a wire rope flaw detector comprising a magnetizing unit that forms a main magnetic flux in a predetermined portion in an axial direction of a wire rope; a damage detecting unit that detects a damaged portion in the predetermined portion of the wire rope; and a magnetic path member made of a ferromagnetic material around which the detecting coil and the exciting coil are wound.

[0005] JP 2014 - 112 076 A discloses a rope testing device that is installed along rails on which a plurality of parallel wire ropes run, and detects magnetic flux leakage generated by the magnetized wire ropes. A sensor surface of the rope testing device is flat and has a length greater than the entire width of the plurality of parallel wire ropes. The sensor surface of the rope testing device is installed parallel to the plane and spans the entire width of the plurality of parallel wire ropes.

[0006] US 8 098 065 B2 discloses a low-cost, flexible, magnetostrictive probe assembly for use on elongated cylindrical structures for volumetric guided-wave inspection of the structures. The probe assembly comprises probe assemblies, preferably used in pairs, that can be adjusted to conform to the curved contours of the cylindrical surface of the structure under inspection in a manner specifically tailored to wire rope, cable, and anchor rod-type applications. SUMMARY OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION

[0007] With conventional magnetostrictive sensor probes like the one described above, the probe surrounds the entire circumference of the wire rope to detect anomalies along the entire circumference of the wire rope. Therefore, it takes a long time to install the probe. Furthermore, the overall size of the probe is large, and when two or more wire ropes are arranged in close proximity, such as in elevators, it may not be possible to install the probe.

[0008] The present invention aims to solve the above-mentioned problems, and an object of the present invention is to provide a rope damage diagnosis testing apparatus that can detect the presence or absence of damage to a wire rope using a compact structure by facing only a peripheral portion of an outer peripheral surface of the wire rope. MEANS TO SOLVE THE PROBLEM

[0009] In a rope damage diagnosis test apparatus that detects the presence or absence of damage in a wire rope around whose outer circumference a plurality of outer layer strands are arranged, each of the outer layer strands having a plurality of outer layer wires arranged around an outer circumference thereof, the rope damage diagnosis test apparatus according to the present invention comprises: an ultrasonic applicator comprising: a magnet that applies a direct current magnetic field to the wire rope; and an excitation coil that applies an alternating current magnetic field to the wire rope, wherein the ultrasonic applicator generates ultrasonic waves in the wire rope by vibrating the wire rope due to the magnetostriction effect;and a detector having a detection element that detects changes in a propagation state of the ultrasonic waves in the wire rope, and the excitation coil and the detection element are arranged in a parallelogram having, as a first opposite side length, a length of a portion of the wire rope in which one of the outer layer strands makes one revolution around the wire rope, and having, as a second opposite side length, a product of a diameter and a number of the outer layer wires included in one of the outer layer strands.; EFFECTS OF THE INVENTION

[0010] In the rope damage diagnosis test apparatus according to the present invention, because the excitation coil and the detection element are arranged in a parallelogram having, as a first opposite side length, a length of a portion of the wire rope in which one of the outer layer strands makes one circuit of the wire rope, and having, as a second opposite side length, a product of a diameter and a number of the outer layer wires included in one of the outer layer strands, the presence or absence of damage in the wire rope can be detected using a compact structure by facing only a peripheral portion of an outer peripheral surface of the wire rope. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an oblique view showing a rope damage diagnosis testing apparatus according to Embodiment 1 of the present invention; Fig. 2 is a circuit diagram for the rope damage diagnosis test device in Fig. 1; Fig. 3 is a cross-section of a wire rope made of Fig. 1; Fig. 4 is a construction diagram showing a layout of an excitation coil with respect to the wire rope of Fig. 1, viewed parallel to a direction perpendicular to a longitudinal direction of the wire rope; Fig. 5 is a construction diagram showing a first variation of the excitation coil in Fig. 4 shows; Fig. 6 is a construction diagram showing a second variation of the excitation coil in Fig. 4 shows; Fig. Figure 7 is a construction diagram showing a third variation of the excitation coil in Fig. 4 shows; Fig. 8 is an oblique view showing a rope damage diagnosis testing apparatus according to Embodiment 2 of the present invention; and Fig. 9 is an oblique view showing a rope damage diagnosis testing apparatus according to Embodiment 3 of the present invention. DESCRIPTION OF THE EMBODIMENTS

[0011] Preferred embodiments of the present invention will now be explained with reference to the drawings. Embodiment 1

[0012] Fig. 1 is an oblique view showing a rope damage diagnosis testing apparatus according to Embodiment 1 of the present invention, and Fig. 2 is a circuit diagram for the rope damage diagnosis test device in Fig. 1. In the figures, a housing 1 of a cable damage diagnostic device is arranged so that it faces a longitudinal section of a wire rope 2. During testing of the wire rope 2, the wire rope 2 is moved relative to the housing 1. In Fig. 1 the housing 1 is shown transparent.

[0013] An ultrasonic applicator 3, an excitation source 4, a detector 5, and a signal processing unit 6 are housed in the housing 1. The ultrasonic applicator 3 has an excitation magnet 7 and an excitation coil 8. The excitation magnet 7 consists of a permanent magnet and applies a direct current magnetic field to the wire rope 2, which forms a magnetic body. The excitation coil 8 applies an alternating current magnetic field to the wire rope 2 and causes induced currents (eddy currents, alternating currents) to flow in the circumferential direction of the wire rope 2.

[0014] The ultrasonic applicator 3 causes the wire rope 2 to vibrate axially through the magnetostriction effect, generating ultrasonic waves in the wire rope 2. The ultrasonic waves generated in the wire rope 2 propagate axially through the wire rope 2 along a helical wire structure. If there is damage to the wire rope 2, i.e., a wire break, the ultrasonic waves are reflected or significantly attenuated at the damaged area.

[0015] The excitation source 4 is connected to the excitation coil 8 and has a high-frequency source 4a that generates high-frequency electric current in a kHz to MHz range.

[0016] The detector 5 is arranged so that it is spaced apart from the ultrasonic applicator 3 in the longitudinal direction of the wire rope 2. The detector 5 has a detection magnet 9 and a detection coil 10, which functions as a detection element. The detection magnet 9 consists of a permanent magnet and applies a direct current magnetic field to the wire rope 2. The detection coil 10 detects the ultrasonic waves propagating through the wire rope 2 as an alternating voltage. The detection coil 10 detects changes in the propagation state of the ultrasonic waves in the wire rope 2.

[0017] The signal processing unit 6 includes a waveform determination circuit 11 and a control communication circuit 12. The waveform determination circuit 11 detects the presence or absence of wire breakage in the wire rope 2 from a high-frequency electric current waveform and the detection voltage waveform in the detection coil 10. The control communication circuit 12 controls the high-frequency source 4a and the waveform determination circuit 11. The control communication circuit 12 also transmits measurement results, i.e., information about the presence or absence of wire breakage, to an external computer. In addition, the control communication circuit 12 receives signals from the external computer such as operation settings, i.e., the start and end of the measurement, the frequency and amplitude of the high-frequency source 4a, and wire breakage criteria, etc.

[0018] Fig. 3 is a cross-section of a wire rope made of Fig. 1 and shows a cross section perpendicular to a longitudinal direction. The wire rope 2 has: a core rope 21 arranged centrally; and a plurality of outer layer strands 22a to 22h twisted together around an outer circumference of the core rope 21. In this example, eight outer layer strands 22a to 22h are used. A cross-sectional construction of the core rope 21 is omitted in Fig. 3, but different constructions can be used for this.

[0019] Each of the outer layer strands 22a to 22h is a stranded wire comprising: a central wire 23 made of steel; nine outer layer wires 24 made of steel arranged on an outer circumference; and nine intermediate wires 25 made of steel arranged between the central wire 23 and the outer layer wires 24. A diameter of the intermediate wires 25 is smaller than a diameter of the central wire 23 and a diameter of the outer layer wires 24.

[0020] In elevator wire ropes 2, a breakage of the outer layer wires 24 of the outer layer strands 22a to 22h may occur at the sections that contact rope pulleys, referred to as "crown breakage", and a breakage of the outer layer wires 24 at the sections that contact the adjacent outer layer strands 22a to 22h, referred to as "valley breakage".

[0021] Fig. 4 is a construction diagram showing a layout of the excitation coil 8 with respect to the wire rope 2 of Fig. 1, which is viewed parallel to a direction (a Z-axis direction) perpendicular to a longitudinal direction of the wire rope 8. The excitation coil 8 is arranged in a parallelogram having, as a first opposite side length, a length of a portion of the wire rope 2 in which a single outer layer strand, such as the outer layer strand 22a, makes one revolution around the wire rope 2, and having, as a second opposite side length, a product of a diameter and a number of the outer layer wires 24 included in a single outer layer strand, such as the outer layer strand 22a.

[0022] In Fig. 4, the excitation coil 8 is arranged around the outer circumference of the parallelogram so as to completely surround the area of ​​the aforementioned parallelogram. Thus, the excitation coil 8 will not apply ultrasonic waves to an identical outer-layer wire 24 at two or more positions simultaneously, while all outer-layer wires 24 of all outer-layer strands 22a to 22h are subjected to ultrasonic waves.

[0023] The detector coil 10 is also arranged similarly or identically to the excitation coil 8. Thus, the detection coil 10 will not simultaneously detect ultrasonic waves from an identical outer layer wire 24 at two or more positions while detecting the ultrasonic waves from all outer layer wires 24 of all outer layer strands 22a to 22h.

[0024] The ultrasonic waves generated by the vibration of the wire rope 2 propagate axially through the wire rope 2 along a helical wire structure 24. If there are irregularities inside the wire rope 2, the ultrasonic waves are reflected or attenuated at that point. The detector 5 detects the ultrasonic waves, which propagate as alternating current through the wire rope 2, by reverse-converting the applied ultrasonic waves. Thus, damage to the wire rope 2 caused by alternating current fluctuations is detected.

[0025] In such a rope damage diagnosis test apparatus, since the excitation coil 8 and the detection coil 10 are arranged on the above-mentioned parallelograms, the presence or absence of damage to the wire rope 2 can be detected using a compact structure by facing only a peripheral portion of an outer peripheral surface of the wire rope 2.

[0026] The device can thus be assembled and disassembled in a short time. Furthermore, the device can be easily installed even when two or more wire ropes 2 are arranged in close proximity, such as in elevators.

[0027] Furthermore, in the above example, the excitation coil 8 is arranged to completely enclose the area of ​​the aforementioned parallelogram, but the excitation coil 8 may be divided into segmented coils 8a to 8h corresponding to the number of outer layer strands 22a to 22h so that adjacent segmented coils are connected as shown in Fig. 5. As shown in Fig. As shown in Figure 6, the adjacent segmented coils 8a to 8h can be connected in the opposite direction. Modifications similar or identical to those of the excitation coil 8 are also possible for the detection coil 10.

[0028] As in Fig. As shown in Figure 7, each of the outer layer strands 22a to 22h can be exposed to ultrasonic waves without connecting the segmented coils 8a to 8h, with ultrasonic waves also being detected in the detection coil 10 for each of the outer layer strands 22a to 22h. The signal-to-noise ratio in wire break detection can thereby be improved.

[0029] Furthermore, the detection element is not limited to the detection coil 10 and can be, for example, a Hall element or a magnetoresistive element. An anisotropic magnetoresistive (AMR) element, a supermagnetoresistive (GMR) element, or a tunneling magnetoresistive (TMR) element can be used as the magnetoresistive element. Embodiment 2

[0030] Fig. 8 is an oblique view showing a rope damage diagnosis test apparatus according to Embodiment 2 of the present invention. In Embodiment 2, an excitation coil 8 detects reflected ultrasonic waves propagating through a wire rope 2 after being subjected to ultrasonic waves. In other words, the excitation coil 8 is used as another detection coil, and reflected waves from a damaged portion 2a of the wire rope 2 are detected by the excitation coil 8. A remaining part of the structure is similar or identical to that of Embodiment 1.

[0031] In such a rope damage diagnosis test apparatus, the signal-to-noise ratio in wire breakage detection can be improved by detecting the reflected waves from the damaged portion 2a in addition to the ultrasonic waves transmitted through a portion of the wire rope 2 between the ultrasonic applicator 3 and the detector 5.

[0032] In addition, by comparing the arrival times of the reflected ultrasonic waves and the transmitted waves, the distance from the excitation coil 8 to the damaged portion 2a can be determined, and speed fluctuations of the ultrasonic waves due to tension fluctuations of the wire rope 2 can be canceled.

[0033] Furthermore, a modification of the structure of the excitation coil 8 and the detection coil 10 in a similar or identical manner to that in Embodiment 1 is also possible in Embodiment 2.

[0034] A modification of the detection element in the detector 5 in a similar or identical manner as in embodiment 1 is also possible in embodiment 2. Embodiment 3

[0035] Next is Fig. 9 is an oblique view showing a wire rope damage diagnosis test apparatus according to Embodiment 3 of the present invention. In Embodiment 3, a detector 5 from the structure of Embodiment 2 is omitted. The ultrasonic applicator 3 also functions as a detector by using the excitation coil 8 as a detection element. The excitation coil 8 detects reflected ultrasonic waves propagating through a wire rope 2 after being applied with ultrasonic waves. The signal processing unit 6 detects the presence or absence of wire breaks using the reflected ultrasonic waves.

[0036] In such a rope damage diagnosis test apparatus, the overall size can be reduced by omitting the detector 5.

[0037] Furthermore, a modification of the structure of the excitation coil 8 in a similar or identical manner to that in Embodiment 1 is also possible in Embodiment 3.

[0038] In embodiments 1 to 3, electromagnets can be used as magnets that apply DC magnetic fields to the wire rope 2.

[0039] Furthermore, the rope damage diagnosis test apparatus according to the present invention can also be applied to ropes other than elevator ropes.

Claims

[1] A rope damage diagnostic test device that detects the presence or absence of damage in a wire rope (2) around the outer circumference of which a plurality of outer layer strands (22a ... 22h) are arranged, each of the outer layer strands (22a ... 22h) having a plurality of outer layer wires (24) arranged around an outer circumference thereof, wherein: the rope damage diagnostic test device has: an ultrasound applicator (3) comprising: a magnet (7) which applies a direct current magnetic field to the wire rope (2); an excitation coil (8) which applies an alternating current magnetic field to the wire rope (2), wherein the ultrasonic applicator (3) generates ultrasonic waves in the wire rope (2) by causing the wire rope to vibrate due to the magnetostriction effect; and a detector (5) having a detection element (10) that detects changes in a propagation state of the ultrasonic waves in the wire rope (2); and the excitation coil (8) and the detection element (10) are arranged in a parallelogram which has as a first opposite side length a length of a section of the wire rope (2) in which one of the outer layer strands (22a ... 22h) makes a revolution around the wire rope (2), and which has as a second opposite side length a product of a diameter and a number of the outer layer wires (24) which are contained in one of the outer layer strands (22a ... 22h). [2] A rope damage diagnosis test device according to claim 1, wherein: the magnet (7) is a loading magnet (7); and the detector (5) has: a detection magnet (9) which applies a direct current magnetic field to the wire rope (2); and a detection coil (10) facing the wire rope (2), the detection coil (10) forming the detection element (10). [3] A rope damage diagnosis test device according to claim 2, wherein the excitation coil (8) and the detection coil (10) are divided into segmented coils (8a ... 8h) corresponding in number to the outer layer strands (22a ... 22h). [4] A rope damage diagnosis test apparatus according to claim 3, wherein the application and detection of ultrasonic waves is performed separately by each of the segmented coils (8a ... 8h). [5] A rope damage diagnosis test apparatus according to any one of claims 1 to 4, wherein reflected ultrasonic waves propagating through the wire rope (2) are detected by the excitation coil (8). [6] A rope damage diagnosis test apparatus according to claim 1, wherein the ultrasonic applicator (3) also serves as a detector (5) by using the excitation coil (8) also as a detection element (10), wherein reflected ultrasonic waves propagating through the wire rope (2) are detected by the excitation coil (8).

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