JP5528550B2 - Wire rope flaw detector - Google Patents

Description

  The present invention relates to a wire rope flaw detector for detecting breakage of a wire rope used in an elevator, a construction crane, or the like, or disconnection of an element wire (hereinafter referred to as a wire rope damaged portion).

  As this kind of wire rope flaw detector, there is one shown in Patent Document 1. This is because a wire rope traveling at a constant speed is magnetized by a permanent magnet or an electromagnet in a predetermined section in the axial direction of the wire rope, and leaked from a damaged portion of the wire rope by a magnetic sensor disposed in the predetermined section. It detects magnetic flux. This wire rope flaw detector is a protective plate made of a non-magnetic material having a substantially U-shaped cross section in which a magnetizer composed of a permanent magnet or an electromagnet and a back yoke and a magnetic sensor for detecting leakage magnetic flux substantially wraps around the wire rope. It is in contact with the wire rope through.

  In the wire rope flaw detector of Patent Document 2, the magnetizer and the magnetic sensor are not in contact with the object to be inspected.

Japanese Patent Laid-Open No. 9-210968 JP-A-2005-106602

  In order to detect a damaged portion of the wire rope with high sensitivity, it is preferable to increase the amount of magnetic flux leaking from the vicinity of the damaged portion, and a magnet having the ability to magnetize the wire rope to near magnetic saturation is selected. Many. In Patent Document 1, a wire rope flaw detector includes a magnet plate composed of a magnet and a back yoke, and a magnetic sensor for detecting a magnetic flux leakage, and a protective plate made of a non-magnetic material having a U-shaped cross section that wraps around the wire rope. Via the wire rope. Therefore, there is a problem that the magnet attracts the wire rope strongly, the frictional force generated between the wire rope and the protection plate is large, and the total inspection distance of the wire rope is shortened due to wear of the protection plate. Further, in Patent Document 2, the leakage magnetic flux density of the damaged portion becomes smaller as the distance from the object to be inspected. Therefore, when the distance between the object to be inspected and the magnetic sensor is increased, the detection sensitivity of the damaged portion is lowered and the object to be inspected is also decreased. When the distance from the magnetic sensor fluctuates due to vibration of the magnetic sensor, an erroneous detection signal is generated in the magnetic sensor.

  The present invention has been made in view of the above-described problems, and aims to extend the life of the apparatus without impairing the detection sensitivity and S / N of the damaged portion of the wire rope.

The wire rope flaw detector of the present invention magnetizes a predetermined section in the axial direction of the wire rope with a magnetizer composed of a back yoke and a magnet, and uses a magnetic sensor to detect leakage magnetic flux generated from the damaged portion of the wire rope in the predetermined section. In the wire rope flaw detector that detects and detects the damaged portion of the wire rope, the magnetizer that magnetizes the wire rope is disposed in non-contact with the wire rope, and the axis of the wire rope in the magnetizer Support rollers for supporting the wire rope are respectively disposed in the front and rear directions, the magnetizer and the wire rope are held in a non-contact state at a constant distance, and the sensor unit including the magnetic sensor is interposed via a protective plate. The sensor unit is arranged in contact with the wire rope, and the sensor unit includes the magnetizer or a substrate holding the magnetizer, and a metal bar. Or connected via a slide block having an air spring, the slide position relative to the substrate to hold the magnetizer or said magnetizer in the slide block is configured to be regulated by the stopper, the sensor unit, the metal spring or air A slide block having a spring follows the displacement due to the vibration of the wire rope so that the contact with the wire rope through the protective plate is maintained and the pressing force to be contacted is adjusted .

According to the wire rope flaw detector according to the present invention, a magnetizer composed of a magnet and a back yoke is disposed in a non-contact manner with respect to the wire rope so as not to generate a frictional force between the wire rope and the magnetizer. In addition, the sensor unit including the magnetic sensor is disposed in contact with the wire rope via the protective plate so that the distance between the sensor unit including the magnetic sensor and the wire rope is substantially constant. The wear of the protective plate of the sensor unit including the magnetic sensor can be reduced against the wear of the protective plate of the conventional magnetizer without deteriorating the detection sensitivity and S / N of the damaged part, and the life of the device can be extended. Can be planned. Further, the sensor unit is connected to a magnetizer or a substrate holding the magnetizer via a slide block having a metal spring or an air spring, and the slide position of the slide block with respect to the magnetizer or the substrate holding the magnetizer is a stopper. The sensor unit follows the displacement due to the vibration of the wire rope by the slide block having the metal spring or the air spring, and the contact with the wire rope through the protective plate is maintained . Since the pressing force to be contacted is adjusted, the frictional force with which the sensor unit contacts the wire rope can be easily made smaller than the frictional force with which the magnetizer contacts the wire rope.
Other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention with reference to the drawings.

It is a block diagram which shows the wire rope flaw detector in Embodiment 1 of this invention. It is explanatory drawing which shows the detection principle of the wire rope flaw detector in Embodiment 1, and shows the case where there is no wire rope damage part. It is explanatory drawing which shows the detection principle of the wire rope flaw detector in Embodiment 1, and shows the case where a wire rope damage part exists. 1 is a perspective view of a wire rope flaw detector according to Embodiment 1. FIG. It is a block diagram which shows the wire rope flaw detector in Embodiment 2. It is a perspective view of the wire rope flaw detector in Embodiment 2.

Embodiment 1 FIG.
1A and 1B are configuration diagrams showing a wire rope flaw detector according to Embodiment 1 of the present invention, in which FIG. 1A is a front view and FIG. 1B is a cross-sectional view taken along line AA in FIG. FIG. 2 is an explanatory view showing the detection principle of the wire rope flaw detector according to Embodiment 1, and shows a case where there is no wire rope damaged part. FIG. 3 is an explanatory diagram showing the detection principle of the wire rope flaw detector according to Embodiment 1, and shows a case where there is a damaged portion of the wire rope. 4 is a perspective view of the wire rope flaw detector according to Embodiment 1. FIG. 1 to 4, the magnetizer 2 is configured such that the wire rope 1 and the magnet cover 4 of the magnet 3 are separated by a predetermined distance (for example, about 5 to 10 mm when the diameter of the wire rope 1 is 10 to 15 mm). It is arranged in a non-contact manner with the rope 1 and magnetizes a predetermined axial section L of the wire rope 1. The magnetizer 2 includes a back yoke 6, a pair of magnets 3 disposed at both ends thereof, a magnet cover 4, and other support parts. The predetermined section is a predetermined section in the axial direction of the wire rope 1 sandwiched between portions of the wire rope 1 facing the permanent magnets or electromagnets of the NS pair disposed at both ends of the back yoke 6 of the magnetizer 2. This is a section indicated by L in FIG.

  In order to prevent damage to the magnet 3, the magnetizer 2 is provided with a magnet cover 4, but the magnet cover 4 and the wire rope 1 are not in contact with each other. In order to prevent the wire rope 1 from coming into contact with the magnet cover 4 due to the attractive force of the magnet 3, support rollers 5 fixed to the substrate 26 are respectively provided before and after the wire rope 1 in the magnetizer 2 in the axial direction. Yes. Since the support roller 5 corresponds to the wire ropes 1 having different diameters, the support roller 5 may be slid at a fixed position. Further, in order to accommodate wire ropes 1 having different diameters, the magnetizer 2 includes a slide mechanism (guides and screws) between the substrate 26 and the distance between the wire rope 1 and the magnet cover 4 can be adjusted. Good.

  As shown in FIG. 2, the sensor unit 7 protects the magnetic sensor 8, the iron core 11, the holder 9 that holds the magnetic sensor 8, the magnetic sensor 8 from sliding of the wire rope 1, and the magnetic sensor 8 and the wire rope 1. The protective plate 12 and the base plate 25 are maintained in an appropriate positional relationship. The most suitable magnetic sensor 8 is a variety of elements such as a search coil, a Hall element, a magnetoresistive effect element (MR, GMR), a magnetoimpedance element (MI), and the accuracy, durability, and cost are examined. Can be selected. Here, a magnetic sensor 8 composed of a search coil 10 and an iron core 11 that increases the amount of magnetic flux linked to the search coil 10 is employed. As shown in FIGS. 1B and 3, the search coil 10 and the iron core 11 have a U-shaped cross section so that the wire rope 1 is substantially half-circumferentially in order to widen the capture range of the damaged portion of the wire rope 19 as much as possible. It is shaped into a shape. The protection plate 12 is formed so as to cover the inner periphery of the magnetic sensor 8 in close contact with each other, and is made of a nonmagnetic material such as austenitic stainless steel. The function of the protective plate 12 can be substituted by embedding the magnetic sensor 8 with a resin having a small friction coefficient and forming it in a U shape.

  In FIG. 1, a pair of end blocks 24 are fixed on a substrate 26, and a lower shaft 23 is fixed between both end blocks 24. A lower shaft 23 passes through the slide block 22, and the slide block 22 can slide along the lower shaft 23. The lower shaft 23 is provided with a stopper 27 that passes through the lower shaft 23 and is slidable along the lower shaft 23. By fixing the stopper 27 to a desired position of the lower shaft 23 with a set screw 28, The range in which the slide block 22 slides on the lower shaft 23 is restricted. That is, the slide block 22 can slide between the one end block 24 and the stopper 27, but cannot slide between the other end block 24 and the stopper 27.

  The follow-up mechanism 13 prevents the sensor unit 7 from moving away from the wire rope 1 due to the influence of the vibration of the wire rope 1 and the distance between the magnetic sensor 8 and the wire rope 1 fluctuating and causing the magnetic sensor 8 to erroneously detect. Provided. The follow-up mechanism 13 is an example of a mechanism using a slide and a spring, and includes a sensor unit stage 20, an upper shaft 21, a slide block 22, a spring 14, a retaining screw 29, and a retaining plate 31. The sensor unit 7 is detachably fixed to the sensor unit stage 20 with screws 30 (FIG. 4). The upper shaft 21 is embedded and fixed in the sensor unit stage 20, the slide block 22 penetrates slidably, and has a retaining screw 29 and a retaining plate 31 at the tip. The upper shaft 21 does not come out of the slide block 22 by the retaining screw 29 and the retaining plate 31. A spring 14 is compressed and interposed between the slide block 22 whose sliding range is restricted by the stopper 27 and the sensor unit stage 20.

  The sensor unit 7 follows the displacement of the wire rope 1 by the pressing force of the spring 14 and is kept in contact with the wire rope 1. At this time, in order to prevent the protection plate 12 from being worn, it is necessary to keep the spring constant at a necessary and sufficient size and to make sure that the natural frequency does not overlap the frequency of the wire rope 1. The spring 14 is an example of a metal spring, but may be an air spring. In addition, the sensor unit stage 20 and the sensor unit 7 have a structure that can be separated by a screw 30. When inspecting wire ropes 1 having different diameters, the sensor units 7 having different U-shaped cross-sectional dimensions can be used. When the inspection is not performed, the sensor unit 7 can be separated from the wire rope 1 by loosening the set screw 28 and sliding the stopper 27 and sliding the slide block 22 on the lower shaft 23.

  Next, the operation will be described. As shown in FIGS. 2 and 3, the main magnetic flux 18 generated from one magnet 3 of the magnetizer 2 passes through the wire rope 1, passes through the other magnet 3 of the magnetizer 2 and the back yoke 6, and the one magnet A magnetic circuit returning to 3 is formed. The magnetomotive force of the magnetizer 2 is set so that the magnetic flux density in the wire rope 1 reaches approximately magnetic saturation. Here, when the wire rope damaged portion 19 exists in the wire rope 1, the leakage magnetic flux 16 is generated in the vicinity thereof. When the leakage magnetic flux 16 passes near the magnetic sensor 8, the amount of magnetic flux in the iron core 11 changes, and an induced voltage is generated at both ends of the search coil 10. Thereby, the presence of the wire rope damaged part 19 can be detected.

  By the way, even when the wire rope damaged part 19 is not present, the wire rope external magnetic flux 17 is present in the vicinity of the magnetic sensor 8. These sizes and distributions depend on the positional relationship among the magnetizer 2, the wire rope 1, and the magnetic sensor 8. Therefore, when the wire rope 1 vibrates and the positional relationship among the wire rope 1, the magnetizer 2, and the magnetic sensor 8 changes, the magnitude of the magnetic flux 17 outside the wire rope also changes. As a result, the output of the magnetic sensor 8 fluctuates and erroneous detection occurs. Therefore, support rollers 5 are installed in the magnetizer 2 before and after the wire rope 1 in the axial direction, the wire rope 1 is pressed by the support rollers 5, and the positional relationship between the magnetizer 2 and the wire rope 1 is maintained at a constant distance without contact. Further, the sensor unit 7 is brought into contact with the wire rope 1 by the follow-up mechanism 13 so that the distance between the magnetic sensor 8 and the wire rope 1 is kept constant.

  Even if vibration of the wire rope 1 occurs during the inspection, the sensor unit 7 is pressed against the wire rope 1 by the spring 14 in order to keep the distance between the magnetic sensor 8 and the wire rope 1 constant. However, in order to prevent the protection plate 12 from being worn, the pressing force of the spring 14 is the pressing force when the magnetizer 2 is brought into contact with the wire rope 1 through the protection plate with a strong magnetic flux by the magnetizer 2 as in the prior art. It can be easily set to be smaller than the force. That is, it is easier to make the frictional force that the magnetic sensor 8 contacts the wire rope 1 smaller than the frictional force that the magnetizer 2 contacts the wire rope 1. Therefore, the wear of the protection plate 12 of the magnetic sensor 8 according to the first embodiment can be reduced compared to the wear of the protection plate of the conventional magnetizer 2.

  As described above, according to the wire rope flaw detector of the first embodiment, the magnetizer 2 including the magnet 3 and the back yoke 6 is disposed in a non-contact manner with respect to the wire rope 1, and the wire rope 1 and the magnetizing device are magnetized. The magnetic sensor 8 is disposed in contact with the wire rope 1 through the protective plate 12 so that a frictional force is not generated between the devices 2, and the distance between the magnetic sensor 8 and the wire rope 1 is made substantially constant. Thus, the wear of the protective plate 12 of the magnetic sensor 8 can be reduced without impairing the detection sensitivity and S / N of the damaged portion of the wire rope, and the life of the apparatus can be extended.

Embodiment 2. FIG.
A wire rope flaw detector according to Embodiment 2 will be described. FIG. 5 is a configuration diagram showing the wire rope flaw detector according to the second embodiment. FIG. 6 is a perspective view showing a wire rope flaw detector according to the second embodiment. In the drawings, the same reference numerals indicate the same or corresponding parts. In the second embodiment, two sets of each constituent element constituting the wire rope flaw detector according to the first embodiment are provided and arranged in a direction opposed to the wire rope 1 by 180 °. The stopper 27 near the end block 24 can be slid on the lower shaft 23 and fixed at a desired position.

  By arranging the two sets of magnetizers 2 in a direction opposite to the wire rope 1 by 180 °, the uniformity of the magnetic flux distribution in the wire rope 1 is increased. In the case of Embodiment 2, in the magnetizer 2, the wire rope 1 and the magnet cover 4 of the magnet 3 are separated by a predetermined distance (for example, about 2 to 5 mm when the diameter of the wire rope 1 is 10 to 15 mm), The wire rope 1 is disposed without contact. In addition, two sets of sensor units 7 are arranged in a direction opposite to each other by 180 ° with respect to the wire rope 1, so that the low sensitivity region of each sensor unit 7, that is, the vicinity of the opening of the U-shaped cross section is damaged by the wire rope. The detection sensitivities when the part 19 passes can be supplemented with each other.

  Similarly, when the sensor unit 7 including the magnetic sensor 8 has a U-shaped cross-sectional structure that wraps around the wire rope 1 more than half a circumference, P sensor units 7 are arranged per wire rope. When this is done, the sensor units 7 are arranged at intervals of 360 / P degrees in the circumferential direction of the wire rope. In this way, by making the cross-sectional shape of the sensor unit 7 U-shaped, it is easy to attach and detach to the wire rope 1, and a wire rope damaged portion occurs in any part in the circumferential direction of the wire rope 1. Even uniform detection sensitivity can be obtained.

Further, when Q magnetizers 2 are arranged per wire rope, the magnetizers 2 are arranged at intervals of 360 / Q degrees in the circumferential direction of the wire rope. If it does in this way, the strength of magnetization in wire rope 1 can be brought close to a uniform state about the peripheral direction of wire rope 1, and a wire rope damage part will occur in any part about the peripheral direction of wire rope 1. Even, a uniform leakage magnetic flux can be obtained.
Various modifications or alterations of the present invention can be realized by related skilled engineers without departing from the scope and spirit of the present invention, and are not limited to the embodiments described in this specification. Should be understood.

Claims (3)

A predetermined section in the axial direction of the wire rope is magnetized by a magnetizer composed of a back yoke and a magnet, and a leakage magnetic flux generated from the damaged portion of the wire rope in the predetermined section is detected by a magnetic sensor. In the wire rope flaw detector that detects
Arranging the magnetizer for magnetizing the wire rope in a non-contact manner with respect to the wire rope;
Support rollers for supporting the wire rope are respectively arranged before and after the wire rope in the magnetizer, and the magnetizer and the wire rope are held in a non-contact state at a constant distance.
A sensor unit including the magnetic sensor is disposed in contact with the wire rope through a protective plate,
The sensor unit is connected to the magnetizer or a substrate holding the magnetizer via a slide block having a metal spring or an air spring,
The slide position with respect to the magnetizer or the substrate holding the magnetizer in the slide block is regulated by a stopper,
The sensor unit follows the displacement due to the vibration of the wire rope by the slide block having the metal spring or the air spring, and the contact with the wire rope through the protective plate is maintained and the pressing force to contact A wire rope flaw detector that adjusts the angle.   The sensor unit has a U-shaped cross-sectional structure that wraps around the wire rope more than half a circumference, and the sensor unit having a U-shaped cross section with different dimensions for the wire ropes having different diameters can be used. The wire rope flaw detector according to claim 1, wherein the sensor unit is detachable.   The wire rope flaw detector according to claim 1 or 2, wherein the magnetizer is provided with a slide mechanism so that a distance from the wire rope can be adjusted according to the wire ropes having different diameters.

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