wire rope

Abstract

To provide a wire rope enabling bending durability to be improved.SOLUTION: A wire rope 1 includes strands 10, 20 formed by winding a plurality of metal strands and has core wires 11, 21 disposed at the center of the plurality of metal strands and side wires 12, 22 that are the other plurality of metal strands and disposed at the outer circumference of the core wires 11, 21, respectively. The side wires 12, 22 have ends 12A, 22A positioned at both ends in a circumferential direction of the core wires 11, 21 at cross sections thereof. At the ends 12A, 22A, Vickers hardness of parts 12A1, 22A1 contacting the ends 12A, 22A of the other adjacent side wires 12, 22 is higher by 1% or more than Vickers hardness of parts 12A2, 22A2 that do not contact the other adjacent side wires 12, 22, and surface roughness Ra of outer peripheral surfaces 12B, 22B of the side wires 12, 22 is 0.10 μm or less.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a wire rope.

Background Art

[0002] Patent Document 1 discloses an elastic wire formed by twisting a plurality of strands having a circular cross-section and subjecting each strand to compression deformation to a non-circular cross-sectional shape by swaging.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since the elastic wire of Patent Document 1 is formed by swaging, the hardness distribution of the cross-section of the side wire is substantially uniform, and the surface roughness of the outer surface of the side wire is not smooth. Therefore, the elastic wire of Patent Document 1 has poor bending durability.

[0005] An object of the present disclosure is to provide a wire rope capable of improving bending durability.

Means for Solving the Problems

[0006] To solve the above problems, a wire rope according to one embodiment of the present disclosure is a wire rope including a strand formed by winding a plurality of metal wires, wherein the strand comprises a core wire located in the center of the plurality of metal wires, and other plurality of metal wires, each of which is located on the outer circumference of the core wire, wherein the side wires have ends located at both ends in the circumferential direction of the core wire in their cross-section, and the Vickers hardness of the portion of the end that contacts the end of an adjacent side wire is 1% or more higher than the Vickers hardness of the portion that does not contact the adjacent side wire, and the surface roughness Ra of the outer surface of the side wire is 0.10 μm or less.

[0007] The Vickers hardness of the portion of the strand that contacts the end of an adjacent siding at its end may be 3% or more higher than the Vickers hardness of the portion that does not contact the adjacent siding.

[0008] A wire rope according to one embodiment of the present disclosure may be formed by winding a plurality of the above-mentioned strands together. [Effects of the Invention]

[0009] This disclosure can provide a wire rope that can improve bending durability. [Brief explanation of the drawing]

[0010] [Figure 1] This is an external view of the wire rope according to the embodiment. [Figure 2] This is a cross-sectional view of a wire rope. [Figure 3] This is a cross-sectional view of the core strand (side strand). [Figure 4] This is a cross-sectional view of the core strand (side strand) during the manufacturing process. [Figure 5] This is an explanatory diagram of the Vickers hardness measurement locations on the side of a wire rope. [Figure 6] This figure shows the results of the bending durability evaluation. [Modes for carrying out the invention]

[0011] Hereinafter, an embodiment of this disclosure will be described with reference to the drawings, but this disclosure is not limited to the embodiment shown in the drawings.

[0012] Figure 1 is an external view of a wire rope 1 according to one embodiment of the present disclosure. Figure 2 is a cross-sectional view of the wire rope 1. Figure 3 is a cross-sectional view of the core strand 10 (side strand 20).

[0013] As shown in Figures 1 and 2, the wire rope 1 is composed of a stranded wire having a core strand 10 and a plurality of (e.g., 6) side strands 20, which are twisted together. The core strand 10 and each side strand 20 are composed of a stranded wire having a plurality of (e.g., 7) strands twisted together. As shown in Figure 3, the core strand 10 comprises a core wire 11 positioned at the center of the core strand 10 from among the plurality of strands, and side wires 12 of the other plurality of (6) strands, each positioned on the outer circumference of the core wire 11 so as to be in contact with the core wire 11.

[0014] The core wire 11 is a metal wire with a circular cross-section that extends from the tip to the base of the core strand 10. The material of the core wire 11 is not particularly limited, but stainless steel is used, for example. The core wire 11 is configured such that the Vickers hardness of the outer circumference in the cross-section is higher than that of the central part in the cross-section. This maintains the flexibility of the core wire 11, improves abrasion resistance due to contact with the side wires 12, and consequently improves bending durability.

[0015] Multiple side wires 12 are metal strands that are in contact with the core wire 11 and wound spirally around the core wire 11 along its longitudinal direction. The material of the core wire 12 is not particularly limited, but stainless steel is used, for example. The cross-sectional shape of the side wires 12 is non-circular and approximately trapezoidal. The side wires 12 have ends 12A located at both ends in the circumferential direction of the core wire 11 in their cross-section. Each end 12A is in surface contact with the end 12A of the adjacent side wire 12. Each side wire 12 has an outer peripheral surface 12B that is exposed to the outside.

[0016] At end 12A, the Vickers hardness of the contact portion 12A1 that contacts the end 12A of the adjacent side wire 12 is set to be higher than the Vickers hardness of the non-contact portion 12A2 that does not contact the adjacent side wire 12. For example, the Vickers hardness of the contact portion 12A1 is set to be 1% or more higher than the Vickers hardness of the non-contact portion 12A2. The surface roughness Ra of the outer circumferential surface 12B of the side wire 12 is set to be 0.10 μm or less.

[0017] Each side strand 20, like the core strand 10, is equipped with a core wire 21 and side wires 22, and has the same configuration as the core strand 10. That is, the side wires 22 have ends 22A located at both ends of the core wire 21 in the circumferential direction in their cross-section. Each end 22A is in surface contact with the end 22A of the adjacent side wire 22.

[0018] At the end portion 22A, the Vickers hardness of the contact portion 22A1 is configured to be higher than that of the non-contact portion 22A2. For example, the Vickers hardness of the contact portion 22A1 is 1% or more higher than that of the non-contact portion 22A2, and the surface roughness Ra of the outer peripheral surface 22B of the side wire 22 is configured to be 0.10 μm or less. Thus, since the Vickers hardness of the portions that come into contact with each other in the side wires 12 and 22 of each strand 10 and 20 is configured to be 1% or more higher than that of the other portions, and the surface roughness Ra of the outer peripheral surfaces 12B and 22B of the side wires 12 and 22 is configured to be 0.10 μm or less, the wear resistance and bending durability of each strand 10 and 20 can be improved. Consequently, the wear resistance and bending durability of the wire rope 1 can be improved.

[0019] Preferably, the Vickers hardness of the contact portions 12A1 and 22A1 is 3% or more higher than that of the non-contact portions 12A2 and 22A2, and more preferably 5% or more higher. Thereby, the wear resistance and bending durability of each strand 10 and 20 can be further improved. Also, preferably, the surface roughness Ra of the outer peripheral surfaces 12B and 22B of the side wires 12 and 22 is 0.04 μm or less.

[0020] Next, an example of the manufacturing method of the wire rope 1 will be described. FIG. 4 is a cross-sectional view of the core strand 14 (side strand 24) in the manufacturing process. First, the core strand 10 and a plurality of side strands 20 are produced. First, a core wire 11 and a plurality of side wires 13 having a circular cross-section are prepared and twisted together. Thereby, as shown in FIG. 4, a core twisted wire 14 in which all the elemental wires have a circular cross-section is formed. This core twisted wire 14 is drawn through a die to form a core strand 10 having a side wire 12 with a substantially trapezoidal cross-sectional shape as shown in FIG. 3. Similarly to the core strand 10, for the plurality of side strands 20, a side twisted wire 24 in which all the elemental wires have a circular cross-section is formed by a core wire 21 and a plurality of side wires 23 having a circular cross-section, and the side twisted wire 24 is drawn through a die to form a side strand 20 having a side wire 22 with a substantially trapezoidal cross-sectional shape as shown in FIG. 3. The wire rope 1 is manufactured by twisting the core strand 10 and the plurality of side strands 20 together.

[0021] The diameters of the core wires 11 and 21 are, for example, 0.05 to 0.07 mm, and the diameters of the side wires 13 and 23 are, for example, 0.05 to 0.07 mm. The diameter of the core strand 10 after die drawing is, for example, 0.12 to 0.18 mm, and the diameter of the side strand 20 after die drawing is, for example, 0.09 to 0.15 mm. The materials of the core wires 11 and 21 and the side wires 13 and 23 are stainless steel.

[0022] Next, the results of measuring the Vickers hardness of the contact portion 12A1 and the non-contact portion 12A2 of the end portion 12A of the side wire 12 of the wire rope 1 manufactured by the above manufacturing method will be described. FIG. 5 is an explanatory diagram of the Vickers hardness measurement positions of the side wire 12 of the wire rope 1.

[0023] The core strand 10 is cut at an arbitrary position in its longitudinal direction, and the Vickers hardness is measured at the measurement points P1 to P8 of the contact portion 12A1 and the non-contact portion 12A2 of the end portion 12A of the side wire 12. The measurement points P1 to P8 are positions in the range of 10 to 20 μm from the surface of the side wire 12, respectively. The Vickers hardness can be measured by a method conforming to JIS Z 2244:2009 using a micro-Vickers hardness tester (for example, a micro-Vickers hardness meter manufactured by Shimadzu Corporation). The test load is 1 kgf (9.8 N).

[0024] The average Vickers hardness of measurement points P1 to P4 is taken as the Vickers hardness of the contact portion 12A1, and the average Vickers hardness of measurement points P5 to P8 is taken as the Vickers hardness of the non-contact portion 12A2. The Vickers hardness of the contact portion 12A1 is approximately 605 HV, and the Vickers hardness of the non-contact portion 12A2 is approximately 570 HV. Thus, at the end portion 12A, the Vickers hardness of the contact portion 12A1 is higher than that of the non-contact portion 12A2. Specifically, the Vickers hardness of the contact portion 12A1 is at least 1% higher than that of the non-contact portion 12A2. Because the contact portion 12A1 is harder than the non-contact portion 12A2, the abrasion resistance and bending durability of the wire rope 1 can be improved. The Vickers hardness of the contact portion 12A1 is preferably 3% or more higher than the Vickers hardness of the non-contact portion 12A2, and more preferably 5% or more higher.

[0025] As a comparative example, the Vickers hardness was similarly measured for core strands produced by swaging a core strand 14 in which all individual wires have a circular cross-section. However, there was almost no difference in the measured values ​​between the contact and non-contact portions.

[0026] Next, we will describe the results of measuring the surface roughness of the outer surfaces 12B and 22B of the side wires 12 and 22 of the strands 10 and 20 manufactured by the above manufacturing method. The surface roughness is calculated by measuring the Ra of the outer surfaces 12B and 22B of each side wire 12 and 22 that constitute the strands 10 and 20 and averaging them. Specifically, for example, as shown in Figure 3, when the circumferential width of the individual wires 12 and 22 that constitute the strands 10 and 20 is D, the surface roughness can be measured in a range of D / 5 centered on the center M of the outer surfaces 12B and 22B of the individual wires 12 and 22, and the surface roughness of each side wire 12 and 22 can be averaged to obtain the result. The surface roughness Ra of the outer surfaces 12B and 22B of each side wire 12 and 22 was measured at an arbitrary position in the axial direction of the wire rope 1. The surface roughness Ra of the outer surfaces 12B and 22B of the side lines 12 and 22 was measured using a surface texture measuring instrument (e.g., a laser microscope manufactured by Keyence Corporation) in accordance with JIS B 0601, for example, to obtain the arithmetic mean roughness (Ra). The average value of all measured surface roughness Ra was 0.04 μm.

[0027] As a comparative example, the surface roughness Ra was similarly measured for a core strand made by swaging a core strand 14 in which all strands have a circular cross-section, but the minimum value was 0.12 μm. This is insufficient to improve the bending durability of the wire rope. Therefore, in this embodiment, the surface roughness Ra of the outer surface 12B of the side wire 12 is set to 0.10 μm or less. As a result, the surface roughness of the outer surface 22B of the side wire 22 is very smooth, which improves the abrasion resistance and bending durability of the wire rope 1.

[0028] The bending durability of wire rope 1 from the above embodiment and the wire rope of the comparative example was evaluated. The bending durability evaluation involved using wire rope 1 and the wire rope of the comparative example, both with an outer diameter of approximately 0.45 mm. A tension of 2.5 kgf was applied, and the number of times the rope was pulled by a 10 mm diameter pulley until it broke was measured. The results are shown in Figure 6.

[0029] As can be seen from Figure 6 above, the wire rope of the comparative example, which has almost no difference in Vickers hardness at the contact area, has a bending durability of approximately 20,000 times, while the wire rope of example 1, which has a higher Vickers hardness at the contact area, has a bending durability of approximately 55,000 times, demonstrating a significant improvement in bending durability.

[0030] This disclosure is not limited to the configuration of the embodiments described above, but is intended to include all modifications within the meaning and scope of the claims as shown, and equivalents of the claims.

[0031] For example, the number of side strands 20 in the wire rope 1 of the above embodiment, and the number of individual wires constituting the core strand 10 and the side strands 20, can be varied in various ways. [Explanation of symbols]

[0032] 1: Wire rope 10: Core Strand 11, 21: Core wire 12, 22: Siding 12A, 22A: End 12A1, 22A1: Contact part 12A2, 22A2: Non-contact part 20: Side strand

Claims

1. A wire rope comprising a core strand and a plurality of side strands, the strands of which are twisted together, The core strand and the plurality of side strands are each formed by twisting together a plurality of metal wires made of stainless steel. Among the plurality of metal strands, the core wire is positioned in the center, The other plurality of metal strands, each comprising a side wire arranged on the outer circumference of the core wire, The aforementioned side line has ends located at both ends of the core line in the circumferential direction in its cross-section, At the aforementioned end, the Vickers hardness of the portion in contact with the end of an adjacent siding is 1% or more higher than the Vickers hardness of the portion not in contact with an adjacent siding. A wire rope having a surface roughness Ra of 0.10 μm or less on the outer surface of the aforementioned side wire.

2. The wire rope according to Claim 1, wherein the core strand and the plurality of side strands each have a Vickers hardness of 3% or more higher in the portion that contacts the end of an adjacent side strand at the end of the strand than in the portion that does not contact an adjacent side strand.

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