JP4374293B2 - Wire rope and wire rope deterioration detection method - Google Patents

Description

  The present invention relates to a wire rope and its deterioration detection method, and more particularly to a wire rope suitable for an elevator and its deterioration detection method.

  An example of a conventional wire rope is described in Patent Document 1. In the wire rope described in this publication, a resin material is coated on each of a plurality of strands constituting the wire rope so that the life and strength of the rope do not decrease even if the sheave diameter is reduced. . The entire wire rope is also coated with a resin material to reduce wear caused by the mutual slippage of the strands and contact with the sheave caused when the sheave is wound.

  Another example of a conventional wire rope is described in Patent Document 2. The wire rope described in this publication has a ratio of the rope diameter to the strand diameter before the entire covering of 15 to 100 in order to cope with the weight reduction of the rope and the sheave with a small diameter. High-strength steel wire is used. Then, a plurality of side strands are arranged around the core strand formed by twisting the strands and twisted together, and the outer periphery is coated with a polymer compound to form one core schenkel. Around the Schenkel, there are several side Schenkels. The side schenkel is formed by arranging and twisting a plurality of side strands around a core strand formed by twisting strands, and has an outer diameter smaller than that of the polymer compound-coated schenkel. The entire rope is covered with a polymer compound.

JP 2001-262482 A

JP 2002-275773 A

  The wire ropes described in Patent Document 1 and Patent Document 2 have the advantage of reducing the decrease in strength of the resin-coated rope even when the sheave is downsized. However, the metal constituting the wire rope by using the wire rope Sufficient consideration has not been given to reliably detecting the breakage of the wire.

  The elevator wire rope is repeatedly bent by a sheave or a pulley when the elevator is driven. As a result, fatigue fracture may be reached. In order to operate the elevator safely, it is necessary to detect a decrease in strength due to fatigue of the rope and replace the rope before a sudden decrease in strength or rope breakage occurs. In particular, in the case of a wire rope in which the outermost periphery of the rope is covered with a resin, it is not possible to inspect the broken state of the strand from the appearance. Therefore, it is desired to reliably detect a decrease in the strength of the wire rope by a method other than the appearance inspection.

  The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to detect a breakage of a strand with high accuracy in a resin-coated wire rope. Another object of the present invention is to prevent a sudden drop in rope strength due to use in a resin-coated wire rope.

  A feature of the present invention that achieves the above object is that a single core schenkel disposed in the center, a plurality of side schenkels disposed around the core schenkel via a core coating resin, and the plurality of side schenkels. A wire rope that is formed by twisting a plurality of strands formed by twisting metal strands with a core schenkel and a side schenkel. The strand strength of all strands of at least one strand of the side schenkel is lower than the strands of other strands.

  In this feature, the core schenkel and the side schenkel have substantially the same diameter and the number of strands. The core schenkel has a core strand disposed in the center and a plurality of strands disposed around the core strand. A plurality of side strands, the core strand and the side strand having substantially the same diameter and number of strands. Preferably, each core strand and each side strand have substantially the same diameter and the number of strands.

  Also, in the above feature, the surface of the metallic strands should be given a gloss or color that distinguishes between those with low strand strength and those with high strand strength. And a plurality of side strands arranged around the central resin and a coating resin arranged around the plurality of side strands, and the softening temperature of the central resin is preferably equal to or higher than the softening temperature of the coating resin. . Further, each of the plurality of side schenkels has a central resin disposed in the center and a plurality of side strands disposed around the central resin, and the softening temperature of the central resin is equal to or higher than the softening temperature of the outer layer coating resin. Preferably, the core schenkel has a plurality of side strands and a coating resin disposed around the side strands, and the softening temperature of the coating resin is equal to or higher than the softening temperature of the outer layer coating resin. desirable.

  Another feature of the present invention that achieves the above object is to apply a magnetic field to the wire rope, measure a magnetic flux leakage from at least a broken portion of the strand and the strand, and based on the measurement result, the strand or strand This is because the rupture is detected.

  According to the present invention, in the side schenkel of the wire rope, the lower-strength portion is formed in units of strands, so the low-strength strand breaks prior to the other strands, so the deterioration of the wire rope is highly accurate. Can grasp.

  FIG. 1 is a cross-sectional view of an embodiment of a wire rope according to the present invention, and FIG. 2 is a perspective view thereof. The wire rope of the present embodiment has a three-stage stranded wire structure. That is, seven strands 16 made of steel are used to form one strand 5, 6, 14, 15 and one Schenkel 11 is formed using seven strands 5, 6, 14, 15 12 is formed. Furthermore, one wire rope 50 is formed using seven Schenkels 11 and 12.

  When forming the strands 5, 6, 14, and 15, six small-diameter side strands 16 b are arranged substantially uniformly in the circumferential direction around one large-diameter core strand 16 a, The strands 16a and 16b are twisted together. Similarly, when the Schenkels 11 and 12 are formed, the six side strands 6 and 15 are arranged substantially evenly around the strands 5 and 14 which are the cores, and the seven strands 5 and 6 are arranged. , 14, 15 are twisted together. Further, around the schenkel 11 serving as one heart, the six side schenkels 12 are arranged substantially evenly in the circumferential direction, and the seven schenkels 11 and 12 are twisted together. This is called an IWRC (Independent Wire Rope Core) rope having a Schenkel structure.

  In the core schenkel 11 arranged in the center of the wire rope 50, the core strand 5, the side strand 6, the gap formed by the side strands 6 and the outer peripheral side of the strand 6 are filled with the core coating resin 1. As a result, the core Schenkel 11 is coated with the core coating resin 1 in a star shape. A gap formed by the core strand 14 and the side strand 15 of the side schenkel 12 and the side strand 15 and the outer periphery side of the core coating resin 1 to the outer periphery side of the side strand 15 are covered with the rope coating resin 4. Thereby, the wire rope 50 is formed as a resin-coated rope having a substantially circular cross section.

  By the way, in this embodiment, among the six side strands 15 of each side schenkel 12, the strands 16 c having lower strength than the other strands 2 are adopted for all the strands of one side strand 3. . Here, low strength means low fatigue strength. Conversely, high strength means high fatigue strength.

  FIG. 8 shows an example of a result of a fatigue strength test with respect to repeated bending stress of a high-strength wire 41 that is a high-strength wire and a low-strength wire 42 that is a low-strength wire. It can be seen that the low-strength wire 42 breaks faster if the bending stress is the same. If all the strands have the same strength, all the strands may break at the same time, and it is difficult to accurately predict or judge the life of the wire rope.

  In this embodiment, only some of the strands are easily cut using low-strength strands, and even if these strands break, other strands guarantee the strength of the wire rope. . Therefore, if the breakage of the low-strength wire can be detected by any method, the rope life can be reliably predicted or judged before the breakage of a large number of strands. In order to easily distinguish between low-strength strands and high-strength strands, the gloss and color of the strands are changed by plating or coloring so that they can be visually discriminated. Thereby, it can be visually confirmed whether the low intensity | strength strand is twisted in before use.

  For the core coating resin 1, a resin such as polyurethane, polypropylene, polyethylene, or nylon is used. The outer diameter shape of the core coating resin 1 is a star shape having a small diameter at the side strand 15 portion located on the innermost side of the side schenkel 12 and a large diameter between the side strands 15, 15 of the adjacent side schenkels 12, 12. Therefore, the groove formed by the concave portion of the small-diameter portion of the core coating resin 1 can be formed as a spiral groove in accordance with the twisting pitch of the side strand 15, and the outermost strand 16 of the core Schenkel 11 when the wire rope 50 is bent. Thus, fretting fracture caused by contact of the innermost strand 16 of the side schenkel 12 and fatigue fracture caused by wear due to contact can be prevented.

  As the rope coating resin 4, a resin such as polyurethane, polypropylene, polyethylene, or nylon is used. Since the outer side of the side schenkel 12 is completely covered with the rope coating resin 4, it is possible to avoid the wire 16 positioned on the outermost side of the side schenkel from directly contacting a sheave (not shown). As a result, it is possible to prevent the wire rope strength from being lowered due to the breakage of the strand 16 due to wear or fretting. When processing the rope coating resin 4 on the wire rope 50, after twisting the core schenkel 11 and the side schenkel 12, the entire schenkel 11, 12 is applied or immersed in the heated rope coating resin 4, and thereafter Cooling. At that time, since the core coating resin 1 may be excessively deformed by the heat of the heated rope coating resin 4, the softening temperature of the core coating resin 1 is set to be equal to or higher than the softening temperature of the rope coating resin 4.

  In the present embodiment, the diameter of the core strand 16a of each strand 5, 6, 14, 15 is made slightly larger than the diameter of the side strand 16b, and the strands 16a and 16b are more closely aligned with each other. , 16b or the gap formed between 16b, 16b is made as small as possible. However, since the core strands 5 and 14 and the side strands 6 and 15 have the same structure, only two types of strands 16 having different diameters are used when the strands 5, 6, 14, and 15 are formed. Manufacturing cost can be reduced.

  When the wire rope 50 described in the above embodiment is used as an elevator moving cable, the wire rope 50 receives a tension due to a load of a car or a counterweight. At the same time, it is repeatedly bent every time it passes through the sheave or pulley. In such a state, the adjacent strands 16 of the wire rope 50 contact and slide under high surface pressure and bending stress. When such a load continues, the strand 16 breaks due to fretting fatigue or fatigue accompanying wear.

  Regarding the surface pressure and bending stress that cause fretting fatigue, the surface pressure is higher on the Schenkel core side, and the bending stress is higher near the surface of the rope. It is difficult to estimate the wire 16 that breaks first due to fretting fatigue or wear-related fatigue because the wire 16 having the same specifications depends on variations in wire strength. Therefore, in this embodiment, the strand 16c having a strength lower than the variation in the strand strength is used for a part of the side strands 3 of the side schenkel 12. As a result, if the strands 16 and 16c have reached a state of breaking, the strand 3 composed of the low-strength strand 16c is broken in advance.

  Another embodiment of the wire rope according to the present invention will be described with reference to FIG. FIG. 3 is a cross-sectional view of the wire rope 50a. This embodiment is different from the embodiment shown in FIG. 1 in that the resin wires 7a and 7b such as polyethylene, polypropylene, and nylon are used in place of the core strand in both the core schenkel 11 and the side schenkel 12. is there. A resin wire 7 a having a hexagonal star shape is arranged in the center Schenkel 11, and a resin wire 7 b having a hexagonal star shape in the side Schenkel 12 is arranged at the center of each Schenkel 11 and 12. The resin wire 7a has a circular cross section before being twisted with each side strand 6.

  At the time of twisting with the side strand 6, if the resin is drawn with a mold while heating, the resin wire 7a is softened. And the strand 16 of the side strand 6 near the resin wire 7a bites into the resin wire 7a, and forms a star-shaped cross section. The grooves formed on the surface of the resin wire 7a coincide with the twist pitch of the core schenkel 11 to prevent the side strands 6 from contacting each other.

  When the core schenkel 11 is coated with the resin, the softening temperature of the resin wire 7a of the core schenkel 11 is set in order to prevent the resin wire 7a of the core schenkel 11 from being deformed excessively by the heat of the heated core coating resin 1. The temperature is higher than the softening temperature of the core coating resin 1 of the Schenkel 11. Similarly, when the wire rope 50a is covered, the core of the core schenkel 11 is prevented from excessively deforming the core coating resin 1 of the core schenkel 11 and the resin wire 7b of the side schenkel 11 due to the heat of the rope coating resin 4. The softening temperature of the coating resin 1 and the softening temperature of the resin wire 7 b of the side schenkel 12 are set to be equal to or higher than the softening temperature of the rope coating resin 1.

  In the present embodiment, since the resin wires 7a and 7b are arranged at the center of the core schenkel 11 and the side schenkel 12, the tensile strength of the wire rope 50a is somewhat reduced. However, since the side strands 6 and 15 do not come into contact with the metal core strands, the surface pressure between the side strands 6 and 15 and the resin wires 7a and 7b is reduced, and the fretting wear strength is increased. The life of the wire rope 50a is extended.

  Still another embodiment of the wire rope 50b according to the present invention is shown in FIG. FIG. 4 is a cross-sectional view of the wire rope 50b. This embodiment differs from the embodiment shown in FIG. 3 in the number of strands 3 made of low-strength strands 16c. Other configurations are the same as those of the embodiment shown in FIG. In the embodiment shown in FIG. 3, each side schenkel 12 always has a strand 3 composed of one low-strength strand 16c, but in this embodiment, only one of the six side schenkels is provided. The strand 3 is made of a low-strength strand 16c. Since the number of the side strands 3 made of the low-strength strands 16c is reduced, the output indicating the breakage of the wire rope 50a is reduced. it can.

  FIG. 9 shows still another embodiment of the wire rope 50c according to the present invention. FIG. 10 is a cross-sectional view of the wire rope 50c. This embodiment is different from the embodiment shown in FIG. 3 in that, in the side strand 15 of the side schenkel 12, the strand of the central portion of the side strand 2 using the high-strength strand is changed to the resin wire 8. It is in. Other configurations are the same as those of the embodiment shown in FIG. According to the present embodiment, it is possible to prevent the metal strands 16 of the side strands 15 from coming into contact with each other and increase the surface pressure, and the life of the side strands 15 and thus the wire rope 50c is extended. Moreover, this can confirm visually whether the low intensity | strength strand is twisted in before use. Resins such as polyethylene, polypropylene, and nylon are used for the core wire 8 of the side strand 15.

  A method of detecting the deterioration of the wire rope using the wire rope shown in the above embodiments will be described with reference to FIG. The rope coating resin 4 is removed so that the side strands 2 and 3 of the side schenkel 12 inside the wire rope 51 can be seen. The exciter 21 is disposed so as to wrap the wire rope 51 at two locations separated in the axial direction of the wire rope 51. The exciter 21 generates a magnetic flux flow 23. The magnetic flux 23 passes through the rope coating resin 4 that is an electrical non-conductor and passes through the metallic strand 16 that is an electrical conductor. When the wire 16 of the wire rope 51 is broken, the magnetic flux 24 leaks from the broken portion 25, and the magnetic flux detector 22 detects the leaked magnetic flux. Thereby, the breakage of the strand 16 is detected.

  In the wire ropes shown in the above embodiments, the low-strength strand 3 made of a low-strength strand breaks first, so that a strong magnetic flux leaks from the broken strand 25. The magnetic flux detector 22 detects this leakage magnetic flux and detects a decrease in strength of the wire rope 51. In the conventional wire rope, the break position changes due to the variation in the wire strength, so that no significant peak appears in the leakage magnetic flux, and it is difficult to accurately grasp the break.

  The repeated bending strength of the wire rope 51 will be described with reference to FIGS. 6 and 7. FIG. 6 shows an example of the characteristics of the wire rope in which all the strands have the same strength (nominal strength), and FIG. 7 shows an example of the characteristics of the wire rope 51 shown in the above embodiments. The tensile strength 31 of the wire rope 51 and the number of strand breaks 32 are shown with respect to the number of times the wire rope 51 is repeatedly bent. If the strengths of all the strands 16 are the same, the tensile strength hardly decreases even if the number of bendings is increased at the beginning of the life of the wire rope 51. And the tensile strength falls rapidly at the end of the life of the wire rope 51.

  This indicates that as a result of many strands 16 being repeatedly bent with substantially the same stress amplitude, the fretting life is concentrated almost at the same time, and the strand breaks occur at the same time. In the wire rope 51 having a characteristic in which the tensile strength sharply decreases, when the number of the broken wires 16 increases and reaches a detectable level, the tensile strength of the wire rope is significantly decreased, and the usable state can be maintained ( Remaining life) (N2-N1) becomes very short. In this case, it is necessary to check the wire rope 51 at a high frequency.

  On the other hand, when the wire rope 51 described in each of the above embodiments is used, the tensile strength of the wire rope 51 is only gradually reduced even when the number of bendings is increased as shown in FIG. This is because the low-strength strand 3 made of the low-strength strand 16c breaks prior to the high-strength strand. In other words, the low-strength strand 16c already has a detectable level because it changes on the breaking curve indicated by the dotted line 32a when the number of flexures is N1. At this time, since the high-strength strand changes on the broken line 32b, it is not yet at the detection level. When the number of times of bending reaches N2, the high-strength strand starts to break, and the life is reached. In each of the above embodiments, since the low-strength strand 3 is twisted, the bending life of the wire rope 51 is slightly reduced. However, after the number of breaks of the low-strength strand 3 reaches a detectable level, the tensile strength of the rope is reduced. The lifetime (N2-N1) until it falls below the usable range can be extended. Thereby, the test | inspection space | interval of a wire rope can be lengthened.

It is a cross-sectional view of one embodiment of a wire rope according to the present invention. It is the perspective view of the wire rope shown in FIG. 1, and is the figure shown excluding some coating | covers. It is a cross-sectional view of another embodiment of the wire rope according to the present invention. It is a cross-sectional view of still another embodiment of the wire rope according to the present invention. It is a figure explaining the deterioration detection method of the wire rope which concerns on this invention. It is a graph explaining the characteristic of a wire rope. It is a graph explaining the characteristic of a wire rope. It is a graph explaining the characteristic of a wire rope. It is a cross-sectional view of still another embodiment of the wire rope according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Heart coating resin, 2, 3 ... Strand, 4 ... Rope coating resin, 5 ... Heart strand, 6 ... Side strand, 7a, 7b ... Resin core, 11 ... Heart schenkel, 12 ... Side schenkel, 14 ... Heart strand, DESCRIPTION OF SYMBOLS 15 ... Side strand, 16 ... Strand, 21 ... Exciter, 22 ... Magnetic flux detector, 23 ... Magnetic flux, 24 ... Leakage magnetic flux, 25 ... Strand break, 26 ... Strand break, 31 ... Tensile strength ratio, 32 ... Strand Number of breaks, 32a ... Number of breaks in low-strength strands, 32b ... Number of breaks in high-strength strands, 41 ... High-strength strands, 42 ... Low-strength strands, 50, 50a, 50b, 51, 51a ... Wire ropes.

Claims (9)

  A core schenkel disposed in the center of the cross section of the wire rope, a plurality of side schenkels disposed around the center schenkel via a core coating resin, and an outer layer coating resin disposed on the outer periphery of the plurality of side schenkels A wire rope formed by twisting a plurality of strands formed by twisting metal strands, and at least one of the plurality of side shenzels. A wire rope characterized in that all strands of the strands have lower strand strength than strands of other strands.   The wire rope according to claim 1, wherein the core schenkel and the side schenkel have substantially the same diameter and the number of strands.   The core schenkel has a core strand disposed in the center portion and a plurality of side strands disposed around the core strand, and the core strand and the side strand have substantially the same diameter and number of strands. The wire rope according to claim 1, wherein the wire rope is the same.   Each of the plurality of side schenkels has a core strand disposed in the center portion and a plurality of side strands disposed around the core strand, and each core strand and each side strand has a strand diameter and a strand. The wire rope according to any one of claims 1 to 3, wherein the number is substantially the same.   The surface of the said metallic strand was given the luster or the color which discriminate | determines a thing with low strand strength and a strand strength high, The any one of Claim 1 thru | or 4 characterized by the above-mentioned. Wire rope. The core Schenkel has a central resin disposed in the center, a plurality of side strands disposed around the central resin, and a coating resin disposed around the plurality of side strands, and the central resin is softened. The wire rope according to claim 1, wherein the temperature is equal to or higher than a softening temperature of the coating resin. Each of the plurality of side schenkels has a central resin disposed in the center and a plurality of side strands disposed around the central resin, and the softening temperature of the central resin is equal to or higher than the softening temperature of the outer layer coating resin. The wire rope according to claim 1, wherein there is a wire rope.   The core schenkel has a plurality of side strands and a coating resin disposed around the plurality of side strands, and the softening temperature of the coating resin is equal to or higher than the softening temperature of the outer layer coating resin. The wire rope according to any one of claims 1 to 5.   A magnetic field is applied to the wire rope according to any one of claims 1 to 8, and at least leakage magnetic flux from a broken portion of either the strand or the strand is measured, and the strand or strand is broken based on the measurement result. Deterioration detection method for wire rope to be detected.

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