JP4179149B2 - Wire rope magnetic flaw detector and pulley with magnetic flaw detector - Google Patents

Description

  The present invention relates to a magnetic inspection device for a wire rope that detects damage such as wire breakage or rust using magnetic force.

  Wire ropes used in elevators, lifts, cable cars, cranes, etc. are visually inspected for damage such as wire breakage and rust caused by fatigue and corrosion, and wire breakage is visually counted for each strand. However, the internal disconnection is detected from the change by measuring the outer diameter with a caliper. However, since it takes too much time to inspect the entire length of the wire rope, the total length is estimated by partially sampling with the know-how of the inspector. Similarly, corrosion is visually inspected for changes in outer shape and rust.

  However, since the visual inspection is performed by partially sampling with the know-how of the inspector, there is a variation in individuals and the inspection accuracy is not sufficient. Therefore, in recent years, a magnetic flaw detector using a magnetic sensor has been developed, and the degree of flaws has been quantitatively measured.

  As this magnetic flaw detector, for example, it has a structure as shown in Patent Document 1. 8 to 10 are explanatory views of the magnetic flaw detector for steel cables disclosed in Patent Document 1. FIG.

JP 2002-116187 A

  FIG. 8A is a schematic configuration diagram of the magnetic flaw detection apparatus disclosed in Patent Document 1. FIG. FIG. 8B is an enlarged longitudinal sectional view of the leakage magnetic flux detector. FIG. 9 is a circuit diagram. FIG. 10 is a waveform diagram showing the measurement results. In these drawings, the magnetic flaw detector a includes an exciter c for exciting a wire rope b, which is an object to be measured, and a leakage flux detector d for detecting a leakage flux generated due to damage to the wire rope b. A flaw detector main body e is connected to a power supply device f. A leakage magnetic flux detector d includes a control circuit g, an amplifier h that amplifies a detection signal from the control circuit g, and an A / A that converts the amplified analog signal into a digital signal. A D converter i and a computer j for inputting a digital signal and performing data analysis are sequentially connected.

  The exciter c is composed of a laminated body of a plurality of permanent magnets arranged at both ends in the longitudinal direction of the flaw detector main body e. A so-called rare earth transition element magnet that exhibits an extremely strong magnetic force made of an alloy of a transition element such as cobalt can be used. In the laminated body, one of the magnetic pole portions k and k at the tip is an N pole and the other is an S pole, and the wire rope b can be magnetized uniformly and quickly.

  Further, the leakage flux detector d is installed so as to surround the entire circumference of the wire rope b positioned between the magnetic poles k and k, and the inner surface of the leakage flux detector d is as shown in FIG. In addition, a plurality of magnetic sensors m are arranged with appropriate circumferential intervals. As the magnetic sensor m, a Hall element is usually used.

  As shown in FIG. 9, the analog detection signals from these magnetic sensors m are individually amplified by an amplifier h, further converted into digital signals by an A / D converter i, and analyzed by a computer j. The

The flaw detection procedure for the wire rope b using the magnetic flaw detection apparatus a is as follows. First, the wire rope b serving as an object to be measured is passed through the flaw detector main body e, the switch of the power supply device f is turned on, the exciter c is operated, and the wire rope b is magnetized until saturated. Next, a direct current is supplied from the power supply device f to the control circuit g, and the leakage magnetic flux detector d is operated. If there is a damaged part such as a break in the wire rope b, a leakage magnetic flux is generated. Therefore, the magnetic sensor m attached to the leakage magnetic flux detector d detects it and generates a voltage. The detection signal based on the voltage thus generated is amplified by the amplifier h for each magnetic sensor m, converted into a digital signal by the A / D converter i, and input to the computer j. Thereafter, the baseline amplitude a ₁ measured in advance shown in FIG. 10 (A) is removed from the waveform shown in FIG. 10 (B) formed from the detection signal by the arithmetic unit of computer j, and FIG. ), Only the damage waveforms b ₁ and b ₂ obtained from the damaged portion of the wire rope b are calculated and displayed.

In this way, the base line amplitude a ₁ (strand noise) is detected by the magnetic sensor m, as shown in FIG. 11, even from a normal wire rope b, from a wire rope b excited in a saturated state. The magnetic flux Φ that leaks is uneven around the wire rope b, and is small at the peak b ₃ of the wire rope b and large at the valley b ₄ . Since detects this magnetic sensor m, the longitudinal movement of the wire rope b, as shown in FIG. 10 (A), a periodic waveform a ₁ appears.

The baseline amplitude a ₁ varies depending on various measurement parameters such as the size of the wire rope b to be measured, the twist condition, the excitation force of the exciter c, and the mounting position of the magnetic sensor m. Therefore, measurement is performed in advance and the waveform of the baseline amplitude a ₁ is stored in the computer j.

By removing the baseline amplitude a ₁ from the measured waveform as described above, waveforms such as the damaged waveforms b ₁ and b ₂ in FIG. 10B that cannot be detected because they are hidden in the baseline amplitude a ₁ are detected. It becomes possible.

  There is an equalizer sheave (pulley) in the wire rope for undulations of jib cranes and bridge type cranes. FIG. 7 is an explanatory view of how to hang the hoisting rope that supports the hoisting operation of the bridge crane. The equalizer sheave (pulley) shown in the figure is located at the neutral portion of the wire ropes coming out of the two undulation drums, and the equalizer pulley does not rotate in principle even if the undulation drum is rotated. In other words, the equalizer pulley is a pulley for balancing the difference in tension between the wire ropes coming out of the two undulation drums and the difference in elongation between the left and right wire ropes. The same position of the wire rope is always in contact with the equalizer pulley.

  However, in the conventional wire rope magnetic flaw detector described with reference to FIGS. 8 to 10, since the wire rope cannot be brought close to the nearest, not only the wire rope in contact with the equalizer pulley but also the wire rope near the equalizer pulley Cannot detect damage.

  The present invention has been devised in view of such problems of the prior art, and an object thereof is to provide a wire flaw magnetic flaw detector capable of detecting damage to a wire rope near an equalizer pulley.

  In order to achieve the above object, the wire flaw magnetic flaw detection apparatus according to the first aspect of the present invention excites the wire rope in the vicinity of the equalizer pulley to bring it into a magnetic saturation state, and a magnetic sensor arranged around the wire rope detects leakage magnetic flux. A magnetic flaw detector for detecting damage to the wire rope by exciting a magnetic pulley to the N or S pole, and at the position slightly spaced from the pulley, the wire rope is opposite to the pulley. A magnet that excites the magnetic pole, and a magnetic sensor array that is provided around the wire rope between the end of the magnet that excites the wire rope and the pulley and has a magnetic sensor attached to the inner surface facing the wire rope. It will be.

  According to a second aspect of the present invention, the wire rope magnetic flaw detection apparatus excites the wire rope near the equalizer pulley to obtain a magnetic saturation state, and the magnetic sensor disposed around the wire rope detects the leakage magnetic flux, A magnetic flaw detector for detecting damage to the wire rope, the magnet for exciting the wire rope at both positions slightly away from the non-magnetic pulley, the end of the magnet for exciting the wire rope, and the pulley And a magnetic sensor array having a magnetic sensor attached to the inner surface facing the wire rope.

  The magnetic sensor is a magnetophoretic capsule sheet that changes color when a magnetic field is applied, and the magnetic sensor array may be made of transparent plastic or glass.

  Furthermore, the pulley with a magnetic flaw detector according to claim 4 excites a wire rope to bring it into a magnetic saturation state, and a magnetic sensor arranged around the wire rope detects leakage magnetic flux, thereby damaging the wire rope. And a pulley with a magnetic flaw detector that detects a magnetic flaw detecting device, and the inner surface surrounding the wire rope away from the non-magnetic pulley is an N or S pole and is in contact with the pulley. A magnetic sensor provided on the inner surface facing the wire rope provided around the wire rope between the pulley and the N or S pole of the magnet, the surface facing the wire rope opposite to the magnet. And a magnetic sensor array to which is attached.

  Next, the operation of the present invention will be described. In the equalizer pulley, there is no relative movement between the wire rope and the pulley, so that the conventional magnetic flaw detector that cannot be brought close to the nearest cannot detect the damage in the vicinity of the pulley. In the magnetic flaw detector, the magnetic equalizer pulley is excited to the N or S pole by the magnet, and the wire rope is excited to the opposite magnetic pole at a position slightly away from the equalizer pulley, resulting in a magnetic saturation state. Therefore, if there is damage such as breakage in the wire rope in the meantime, the leakage magnetic flux increases, and the presence or absence of damage can be detected by the magnetic sensor. If each magnetic sensor has a one-to-one correspondence with each strand of the wire rope, it is possible to detect which strand has been damaged. Although the leakage flux is the largest at the damaged part, there is a range where the leakage flux is also large before and after that, so the damage can be detected even if the damaged part is some distance away from the magnetic sensor. Wire rope damage can be detected.

  The wire rope magnetic flaw detector according to claim 2 is different from the invention according to claim 1 in the material of the equalizer pulley. That is, in the invention described in claim 1, the equalizer pulley is a magnetic material, whereas in the invention described in claim 2, it is a non-magnetic material. Therefore, in the first aspect of the invention, the wire rope cannot be magnetically saturated in the portion that is in contact with the equalizer pulley, whereas in the second aspect of the invention, the wire rope is also in the portion that is in contact with the equalizer pulley. The rope can be in a magnetic saturation state, and it is possible to detect damage to the wire rope in the vicinity of the equalizer pulley including the portion in contact with the equalizer pulley.

  In the above two inventions, the magnetic sensor uses, for example, a Hall element, and the output is connected to an amplifier, a filter, an A / D converter, a signal processing unit, a recording device, etc. to detect damage. On the other hand, in the wire rope magnetic flaw detector according to the third aspect of the invention, since the magnetic sensor is a magnetophoretic capsule sheet that changes color when a magnetic field is applied, the leakage magnetic flux can be confirmed directly visually, and the power supply, amplifier, filter, An A / D converter, a signal processing unit, a recording device, etc. are not required.

  Furthermore, the pulley with a magnetic flaw detector according to the fourth aspect of the present invention can be applied not only to an equalizer pulley but also to a normal fixed pulley or a moving pulley, and the attachment of the magnetic flaw detector can be facilitated.

As described above, the wire flaw magnetic flaw detector according to the first to third aspects of the invention can detect damage to the wire rope in the vicinity of the equalizer pulley that cannot be detected by a normal magnetic flaw detector. It has an excellent effect. The pulley with a magnetic flaw detector according to a fourth aspect of the invention has an excellent effect that the mounting of the magnetic flaw detector can be facilitated.

Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a drawing of a wire rope magnetic flaw detector according to the first aspect of the present invention. FIG. 1 (A) is a front view, FIG. 1 (B) is a side view, and FIG. . In the figure, 1 is a wire rope, and 2 is a magnetic equalizer pulley. Reference numeral 3 denotes a magnet that brings the wire rope 1 into a magnetic saturation state, and two magnets are provided as shown in the figure. The magnet 3 may be a permanent magnet or an electromagnet. A bracket 4 supports the equalizer pulley from both sides. Reference numeral 5 denotes a connecting member that connects the lower ends of the two magnets 3, and is fixed to the lower end of the bracket 4 at the center. The magnet 3 has a U-shaped outer shape in a side view, the lower end is fixed to the connecting member 5, and the upper end is formed with a round hole through which the wire rope 1 is inserted.

Reference numeral 6 denotes a semicircular magnetic sensor array, and a magnetic sensor 7 is attached to the inner surface facing the wire rope 1. The magnetic sensor array 6 is provided around the wire rope 1 between the upper end of the magnet 3 and the equalizer pulley 2 and is supported by the bracket 4. Reference numeral 10 denotes a magnetic flaw detector.

Next, the operation of this embodiment will be described. In the equalizer pulley 2, the wire rope 1 does not move relative to the pulley 2, so that the conventional magnetic flaw detector that cannot be brought close to the nearest cannot detect damage in the vicinity of the pulley 2, whereas the wire of the first embodiment In the rope magnetic flaw detector, the magnet equalizer pulley 2 is excited to the S pole by the magnet 3, and the wire rope 1 is excited to the N pole at a position slightly away from the equalizer pulley 2 and is in a magnetic saturation state. Therefore, if there is damage such as disconnection in the wire rope 1 in the meantime, the leakage magnetic flux Φ increases, and the presence or absence of damage can be detected by the magnetic sensor 7. Since each magnetic sensor 7 is made to correspond to each strand of the wire rope 1 on a one-to-one basis, it can be detected which strand has been damaged. Although the leakage magnetic flux Φ is the largest at the damaged portion, there is a range where the leakage magnetic flux is large before and after the damaged portion, so that the damage can be detected even if the damaged portion is separated from the magnetic sensor 7 to some extent. Damage to the wire rope 1 in the vicinity of 2 can be detected.

2 is a drawing of a wire rope magnetic flaw detector according to a second aspect of the present invention, wherein (A) is a front view and (B) is a side view. In this figure, the same reference numerals are given to the parts common to FIG. In the figure, 2a is a non-magnetic equalizer pulley. 3a is a magnet that excites the wire rope 1 to a magnetic saturation state at both positions slightly away from the non-magnetic pulley 2a. The magnet 3a has a U-shaped outer shape in a plan view, and has round holes through which the wire rope 1 is inserted at both ends. One end is an N pole and the other end is an S pole.

Next, the operation of this embodiment will be described. The wire flaw magnetic flaw detector of the second embodiment differs from the invention of the first embodiment in the material of the equalizer pulley 2. That is, in the invention described in the first embodiment, the equalizer pulley 2 is a magnetic material, whereas in the invention described in the second embodiment, the equalizer pulley 2 is a non-magnetic material. Therefore, in the invention described in the first embodiment, the wire rope 1 cannot be brought into a magnetic saturation state in the portion in contact with the equalizer pulley 2, whereas in the invention described in the second embodiment, the wire rope 1 is in contact with the equalizer pulley 2a. Even in the portion, the wire rope 1 can be brought into a magnetic saturation state, and the damage of the wire rope 1 in the vicinity of the equalizer pulley 2a can be detected including the portion in contact with the equalizer pulley 2a.

FIG. 3 is a drawing of a pulley with a magnetic flaw detector according to a fourth aspect of the present invention, wherein (A) is a front view and (B) is a side view. Also in this figure, the same reference numerals are given to portions common to FIG. 1 or FIG. 3b is a magnet that excites the wire rope 1 to bring it into a magnetic saturation state. The magnet 3b is shaped by tying two U-shaped magnets in a side view, and the upper end has an S pole on the inner surface surrounding the wire rope 1 away from the nonmagnetic pulley 2a. At the lower end, the surface facing the wire rope 1 in contact with the pulley 2a is an N pole. Reference numeral 15 denotes a pulley with a magnetic flaw detector.

Next, the operation of this embodiment will be described. The pulley with a magnetic flaw detector according to the present invention can be applied not only to an equalizer pulley but also to an ordinary fixed pulley or a moving pulley, and the attachment of the magnetic flaw detector can be facilitated.

FIG. 4 is a drawing of a wire rope magnetic flaw detector according to a third aspect of the present invention, wherein (A) is a front view and (B) is a side view. In this figure, the same reference numerals are given to portions common to those in FIGS. 1 to 3, and a duplicate description is omitted. In this figure, 6a is a magnetic sensor array in which a magnetic sensor 7a is attached to the inner surface facing the wire rope 1, and is made of transparent plastic or glass. The magnetic sensor 7a is a magnetophoretic capsule sheet that changes color when a magnetic field is applied. A magnetophoresis capsule sheet is a microcapsule in which needle-shaped magnetic powders with different tip and side colors are encased in a transparent film, and formed into a sheet shape. By rotating and changing the color tone, the magnetic flux leakage can be detected.

Next, the operation of this embodiment will be described. Since the magnetic sensor 7a is a magnetophoretic capsule sheet that changes color when a magnetic field is applied, the leakage magnetic flux can be checked directly, eliminating the need for power supplies, amplifiers, filters, A / D converters, signal processing units, recording devices, etc. become.

FIG. 5 is a graph showing measurement data obtained with the wire rope magnetic flaw detector of the present invention, with the horizontal axis representing time t and the vertical axis representing leakage flux Φ. FIG. 6 is an explanatory diagram of a processing device 14 for signals from the probe (magnetic flaw detector) 10. In this figure, 8 is an amplifier that amplifies the signal from the magnetic sensor array 6, 9 is a filter that removes noise, 11 is an A / D converter that converts an analog signal into a digital signal, and 12 is a signal processing unit. For example, it may have a function of comparing the value of a signal with a required threshold value and issuing a disconnection alarm if it is larger than that. Reference numeral 13 denotes a signal recording device.

FIG. 5 illustrates the case where the number of strands of the wire rope 1 is 3, and the corresponding magnetic sensors are the sensor A, the sensor B, and the sensor C. The signal processing unit 12 acquires a signal from the magnetic sensor array 6 and extracts a signal equal to or higher than the threshold value by comparing with a threshold value of the disconnection signal determined in advance by calibration. A portion of the signal that is equal to or greater than the extracted threshold is diagnosed as a broken portion. As shown in the figure, for the sensors A and B, the leakage flux Φ hardly changes, but for the sensor C, the leakage flux Φ increases with the elapsed time, and exceeds a threshold value after a certain time. Therefore, it is determined that there is a break in the strand corresponding to the sensor C.

  The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the scope of the invention. For example, in FIGS. 1 to 4, the wire rope is shown as being wound 180 degrees around the pulley, but may be in a state where it is wound 90 degrees as shown in FIG. 7.

It is drawing of the magnetic flaw detector of invention of Claim 1, (A) is a front view, (B) is a side view, (C) is CC sectional view taken on the line of (A). It is drawing of the magnetic flaw detector of invention of Claim 2, (A) is a front view, (B) is a side view. It is drawing of the pulley with a magnetic flaw detector of Claim 4 invention, (A) is a front view, (B) is a side view. It is drawing of the magnetic flaw detector of invention of Claim 3, (A) is a front view, (B) is a side view. It is a graph which shows the measurement data obtained with the magnetic flaw detector of the wire rope of this invention. It is explanatory drawing of the processing apparatus of the signal from a probe (magnetic flaw detector). It is explanatory drawing of how to hang the hoisting rope which supports the hoisting operation | movement of a bridge crane. It is the structure schematic of the conventional magnetic flaw detector. It is a circuit diagram of the conventional magnetic flaw detector. It is a wave form diagram which shows the measurement result of the conventional magnetic flaw detector. It is a figure which shows distribution of the leakage magnetic flux around a wire rope.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wire rope 2, 2a Pulley 3, 3a, 3b Magnet 6, 6a Magnetic sensor array 7, 7a Magnetic sensor

Claims (4)

A magnetic flaw detection device that detects damage to the wire rope by exciting a wire rope near the equalizer pulley to a magnetic saturation state and detecting a magnetic flux leaked by a magnetic sensor disposed around the wire rope. Exciting the body pulley to the N or S pole and exciting the wire rope to the magnetic pole opposite to the pulley at a position slightly away from the pulley, the end of the magnet exciting the wire rope, and the pulley And a magnetic sensor array having a magnetic sensor attached to an inner surface facing the wire rope. A magnetic flaw detection device that detects damage to the wire rope by exciting a wire rope near the equalizer pulley to a magnetic saturation state and detecting a leakage magnetic flux by a magnetic sensor disposed around the wire rope. A magnet that excites the wire rope at both positions slightly away from the pulley of the magnetic material, and an inner surface that is provided around the wire rope between the end of the magnet that excites the wire rope and the pulley and that faces the wire rope And a magnetic sensor array having a magnetic sensor attached thereto. 3. The magnetic flaw detector according to claim 1, wherein the magnetic sensor is a magnetophoretic capsule sheet that changes color when a magnetic field is applied, and the magnetic sensor array is made of transparent plastic or glass. With a magnetic flaw detector combined with a pulley, a magnetic flaw detector that detects damage to the wire rope by exciting a wire rope to a magnetic saturation state and detecting a magnetic flux leaked by a magnetic sensor arranged around the wire rope The inner surface surrounding the wire rope away from the non-magnetic pulley is a N or S pole, and the surface facing the wire rope in contact with the pulley is a magnetic pole opposite to the above. And a magnetic sensor array provided around the wire rope between the pulley and the N or S pole of the magnet and having a magnetic sensor attached to the inner surface facing the wire rope. A pulley with a magnetic flaw detector.

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