CN118103318A - Wire rope, elevator, and method for manufacturing wire rope - Google Patents

Abstract

The wire rope (10) is provided with a core rope (20) formed by twisting a plurality of core rope strands (21). The core rope strand (21) has an inner core (22) formed of yarns formed by twisting a plurality of first synthetic fibers and a plurality of outer cores (23) formed of yarns formed by twisting a plurality of second synthetic fibers, and is disposed on the outer periphery of the inner core (22). The second compressive yield strength is higher than the first compressive yield strength, and the second compressive yield strength is a compressive stress at which the second synthetic fiber starts to plastically deform at the time of compressive deformation in the radial direction of the second synthetic fiber, and the first compressive yield strength is a compressive stress at which the first synthetic fiber starts to plastically deform at the time of compressive deformation in the radial direction of the first synthetic fiber. Thus, a steel wire rope (10) having excellent durability can be provided by the outer core (23) while suppressing elastic elongation by the inner core (22).

Description

Wire rope, elevator, and method for manufacturing wire rope

Technical Field

The present invention relates to a wire rope, an elevator provided with the wire rope, and a method for manufacturing the wire rope.

Background

For example, a wire rope for use in an elevator, a crane, and a cableway includes a core rope and a plurality of wire strands arranged on the outer periphery of the core rope. The steel wire strand is formed by twisting a plurality of steel wires. The core rope has a function of maintaining the shape of the wire rope. The core rope is impregnated with oil necessary for lubrication and rust prevention of the steel wire strands, and also has a function of supplying oil to the steel wire strands. Therefore, the conventional core rope is formed of natural fibers such as sisal hemp which is rich in oil retention. However, natural fibers are perishable and short in fiber length, and thus it is difficult to provide strength. Therefore, a core rope made of synthetic fibers having a longer fiber length and having better corrosion resistance than natural fibers is becoming popular.

For example, the steel wire rope of patent document 1 includes a core rope formed of a1 st yarn and a2 nd yarn, the 1 st yarn is formed by twisting fibers composed of a resin having a melting point higher than that of oil, and the 2 nd yarn is formed by twisting a sheet made of polyethylene subjected to a splitting process. Thus, the 1 st yarn can supply oil to the steel wire strands, and the polyethylene forming the 2 nd yarn has a small friction coefficient and excellent wear resistance, so that the wear resistance of the core rope can be improved. Patent document 1 describes that the 2 nd yarn is disposed around the 1 st yarn, and the 1 st yarn is disposed so as not to be exposed to the surface of the core rope. That is, the polyethylene as the 2 nd yarn is disposed at a position contacting the steel wire strands.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2015-205766

Disclosure of Invention

Problems to be solved by the invention

However, in the invention described in patent document 1, it is not considered whether or not the 1 st wire and the 2 nd wire are plastically deformed, and the abrasion resistance of the wire rope is considered to be improved. Generally, in a process for producing a wire rope, a core rope and a wire strand are subjected to compression shaping in a radial direction perpendicular to an axial direction of the wire rope. At this time, the synthetic fibers forming the core rope may be plastically deformed. Whether plastic deformation of the synthetic fiber occurs can be judged by the compressive yield strength. The compressive yield strength is a compressive stress at which the synthetic fiber starts to undergo plastic deformation upon compressive deformation in a radial direction perpendicular to the axial direction of the synthetic fiber. The polyethylene forming the core rope of patent document 1 has a relatively low compressive yield strength as compared with other synthetic fibers. That is, polyethylene is more likely to be plastically deformed by compression shaping in the manufacturing process of the wire rope than other synthetic fibers. Further, when the polyethylene is plastically deformed, the surface area of the polyethylene in contact with the strands becomes large. Accordingly, the wire rope of patent document 1 has problems that the diameter of the core rope is easily reduced due to abrasion between the core rope and the wire strands, and the durability is insufficient.

In addition, for example, in the case of using a wire rope as a hoist rope of an elevator, if the wire rope expands and contracts when passengers get on and off the car, the car vibrates. Therefore, the elastic elongation of the wire rope is preferably small.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a wire rope excellent in durability and small in elastic elongation, an elevator including the wire rope, and a method of manufacturing the wire rope.

Means for solving the problems

The steel wire rope of the present invention comprises: a core rope formed by twisting a plurality of core rope strands, the core rope strands having an inner core formed of at least one of a yarn (yarn) formed by twisting a plurality of first synthetic fibers and a yarn formed by mixing a plurality of first synthetic fibers and a plurality of second synthetic fibers, and a plurality of outer cores formed of a yarn formed by twisting a plurality of second synthetic fibers and disposed on the outer periphery of the inner core; and a plurality of steel wire strands disposed on the outer periphery of the core rope, the plurality of steel wires being twisted together, the second compressive yield strength being higher than the first compressive yield strength, the second compressive yield strength being a compressive stress at which the second synthetic fiber starts to plastically deform upon compressive deformation of the second synthetic fiber in a radial direction perpendicular to the axial direction, the first compressive yield strength being a compressive stress at which the first synthetic fiber starts to plastically deform upon compressive deformation of the first synthetic fiber in a radial direction perpendicular to the axial direction.

An elevator of the present invention includes: a wire rope; the elevator car is connected with one end of the steel wire rope and is suspended in the well; the counterweight is connected with the other end of the steel wire rope and is suspended in the well; and a hoisting machine having a sheave around which a wire rope is wound, the hoisting machine being configured to raise and lower the car and the counterweight by rotating the sheave, the wire rope including: a core rope formed by twisting a plurality of core rope strands, the core rope strands having an inner core formed of at least one of a yarn formed by twisting a plurality of first synthetic fibers and a yarn formed by mixing a plurality of first synthetic fibers and a plurality of second synthetic fibers, and a plurality of outer cores formed of a yarn formed by twisting a plurality of second synthetic fibers and disposed on the outer periphery of the inner core; and a plurality of steel wire strands disposed on the outer periphery of the core rope, the plurality of steel wires being twisted together, the second compressive yield strength being higher than the first compressive yield strength, the second compressive yield strength being a compressive stress at which the second synthetic fiber starts to plastically deform upon compressive deformation of the second synthetic fiber in a radial direction perpendicular to the axial direction, the first compressive yield strength being a compressive stress at which the first synthetic fiber starts to plastically deform upon compressive deformation of the first synthetic fiber in a radial direction perpendicular to the axial direction.

The manufacturing method of the steel wire rope comprises the following steps: a step of producing a core rope strand in which a plurality of outer cores are arranged on the outer periphery of an inner core, the inner core being formed of at least one of a yarn formed by twisting a plurality of first synthetic fibers and a yarn formed by mixing a plurality of first synthetic fibers and a plurality of second synthetic fibers, and the plurality of outer cores being formed of a yarn formed by twisting a plurality of second synthetic fibers; twisting a plurality of core rope strands to produce a core rope; and disposing a plurality of steel wire strands formed by twisting a plurality of steel wires on the outer periphery of the core rope, and performing compression shaping on the core rope and the plurality of steel wire strands, wherein the second compressive yield strength is higher than the first compressive yield strength, the second compressive yield strength is a compressive stress at which the second synthetic fibers start to be plastically deformed when the second synthetic fibers are compressively deformed in a radial direction perpendicular to the axial direction, and the first compressive yield strength is a compressive stress at which the first synthetic fibers start to be plastically deformed when the first synthetic fibers are compressively deformed in a radial direction perpendicular to the axial direction.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a wire rope includes a core rope formed by twisting a plurality of core rope strands. The core rope strand has an inner core formed of at least one of a yarn formed by twisting a plurality of first synthetic fibers and a yarn formed by mixing a plurality of first synthetic fibers and a plurality of second synthetic fibers, and a plurality of outer cores formed of a yarn formed by twisting a plurality of second synthetic fibers. Further, the second synthetic fiber has a higher compressive yield strength than the first synthetic fiber. This makes it possible to provide a steel wire rope having excellent durability by the inner core while suppressing elastic elongation by the outer core.

Drawings

Fig. 1 is a schematic diagram showing an elevator including a wire rope according to embodiment 1.

Fig. 2 is a schematic sectional view of a steel wire rope according to embodiment 1.

Fig. 3 is a diagram showing a relationship between load and elongation of the wire rope according to embodiment 1.

Fig. 4 is a schematic cross-sectional view of the core rope according to embodiment 1.

Fig. 5 is a graph illustrating compressive yield strength of embodiment 1.

Fig. 6 is a schematic cross-sectional view illustrating a wire rope manufacturing process according to embodiment 1.

Fig. 7 is a cross-sectional view of the core rope according to embodiment 2.

Detailed Description

A wire rope 10 according to an embodiment of the present invention, an elevator 1 including the wire rope 10, and a method of manufacturing the wire rope 10 will be described below with reference to the drawings. In the drawings, the same or equivalent portions are denoted by the same reference numerals. In the rectangular coordinate system XYZ shown in the figure, the axial direction of the wire rope 10 is defined as the X-axis direction, and the radial direction of the wire rope 10, which is the direction perpendicular to the axial direction of the wire rope 10, is defined as the YZ-plane direction. In fig. 1, the axial direction of the wire rope 10 from the car 3 to the sheave 6 is the X-axis direction.

Embodiment 1

An elevator 1 including a wire rope 10 according to embodiment 1 will be described with reference to fig. 1. Fig. 1 is a schematic diagram showing an elevator 1 including a wire rope 10 according to embodiment 1. Fig. 1 shows, as an example, a traction type elevator 1 having a machine room 2 in an upper portion of a hoistway 5. The car 3 and the counterweight 4 for passenger lifting are suspended in the hoistway 5 by a wire rope 10 as a hoist rope. The car 3 is connected to one end of the wire rope 10, and the counterweight 4 is connected to the other end of the wire rope 10. The wire rope 10 is wound around a sheave 6 and a deflector pulley 7 of a hoisting machine provided in the machine room 2. The hoisting machine moves up and down the car 3 and the counterweight 4 by rotating the sheave 6. The lifting and lowering of the car 3 and the counterweight 4 are controlled by a control device 8 provided in the machine room 2. Although not shown, the wire rope 10 is wound around a diverting pulley or a hanging pulley as needed.

Fig. 2 is a schematic sectional view of the wire rope 10 according to embodiment 1. The wire rope 10 includes a core rope 20 and a plurality of wire strands 30 arranged on the outer periphery of the core rope 20.

The core rope 20 is formed by twisting a plurality of core rope strands 21. For example, in fig. 2, a wick 20 shows a wick formed by twisting 3 wick strands 21. In addition, the core rope 20 is impregnated with oil required for lubrication and rust prevention of the wire strands 30. The core rope strand 21 has an inner core 22 and a plurality of outer cores 23 arranged on the outer periphery of the inner core 22. Details of the inner core 22 and the outer core 23 will be described later.

The wire strand 30 is formed by twisting a plurality of wires 31. The plurality of wire strands 30 are spirally wound around the outer circumference of the core rope 20 to cover the surface of the core rope 20. In fig. 2, an example of an 8×s (19) structure defined by JISG3525 is shown. 8×s (19) means that the number of the wire strands 30 is 8, the twisting method of the wire strands 30 is a method generally called siru (Seale), and the number of the wires 31 included in 1 wire strand 30 is 19.

Next, the characteristics required for the wire rope 10 will be described.

Fig. 3 is a diagram showing a relationship between load and elongation of the wire rope 10 according to embodiment 1. The load versus elongation relationship shown in FIG. 3 is commonly referred to as a "stress-strain-plot" or "S-S curve". Referred to herein as the S-S curve. For the S-S curve of the wire rope 10, both ends of the wire rope 10 are fixed so that the wire rope 10 does not rotate, and a load is gradually applied in the axial direction of the wire rope 10. Then, the S-S curve can be obtained by taking the load (N) as the vertical axis and the elongation (%) as the horizontal axis for the passage until the wire rope 10 breaks. In the S-S curve of the wire rope 10 shown in fig. 3, the starting point of the elongation range generated in proportion to the load is a, the ending point is B, and the point at which the wire rope 10 breaks is C. In the S-S curve of the wire rope 10 shown in fig. 3, the elongations corresponding to A, B and a 'described later are denoted by a, b, and a', respectively.

Elongation of the wire rope 10 is classified into two types of initial elongation and elastic elongation. Initial elongation refers to the portion 0-a of fig. 3. The initial elongation generally occurs at an initial stage when a new wire rope 10 is used. This is because, in the new wire rope 10, gaps exist between the plurality of wires 31 forming the wire strands 30 and between the plurality of wire strands 30, respectively, and the mutually insufficient adhesion state is not achieved. Accordingly, when a load acts on the wire rope 10, the plurality of wires 31 and the plurality of wire strands 30 are respectively abutted against each other, and the wire rope 10 is elongated during the abutment. The elongation of the wire rope 10 is an initial elongation and does not recover even if the load is removed.

When a load further acts on the wire rope 10 in a state where the plurality of wires 31 and the plurality of strands 30 are abutted against each other, elongation occurs in proportion to the load as shown by a straight line AB in fig. 3. The elastic elongation is the elongation during which the elongation is proportional to the load, and refers to the portions a-b of fig. 3. Moreover, when the load is removed, the elastic elongation returns to the original state. That is, when a load acts on the wire rope 10 from which the initial elongation is removed, the wire strands 30 arranged on the outer periphery of the core rope 20 are tightened in the radial direction of the core rope 20, and the core rope 20 is compressed by the wire strands 30. Thereby, the diameter of the wire rope 10 becomes small, and the wire rope 10 is elongated. Then, when the load is removed from the wire rope 10, the force of the wire strands 30 compressing the core rope 20 in the radial direction is weakened, the diameter of the wire rope 10 is restored, and the wire rope 10 is shortened to the original length before the load acts on the wire rope 10. The radial direction of the core rope 20 is a direction perpendicular to the axial direction of the core rope 20, and is a YZ plane direction in the rectangular coordinate system XYZ shown in fig. 2.

However, in the case where the repulsive force of the core rope 20 against the compressive stress is large, the diameter of the core rope 20 becomes thicker than the original state after the load is removed. As a result, a gap may be generated again between the strands 30, and the elongation returns to a' in fig. 3. In this case, the elastic extension in a broad sense means the portion a' -b of fig. 3. Elastic elongation is used in a broad sense herein.

When the elastic limit B is exceeded, the load is no longer proportional to the elongation, and the breaking point C is reached shortly.

For example, the elastic elongation of the wire rope 10a, in which the repulsive force of the core rope 20 against the compressive stress is small, is a-b of fig. 3. The elastic elongation of the wire rope 10b having a large repulsive force of the core rope 20 against the compressive stress is a' -b of fig. 3. Therefore, the wire rope 10b having a large repulsive force of the core rope 20 against the compressive stress is elastically elongated by an amount a' -a of fig. 3 as compared with the wire rope 10a having a small repulsive force of the core rope 20 against the compressive stress. When the elevator 1 uses the wire rope 10b having a large elastic extension, the wire rope 10b expands and contracts greatly when passengers get on and off the car 3, and thus the car 3 vibrates greatly.

As shown in fig. 1, the wire rope 10 is repeatedly bent at a portion wound around the sheave 6 and the deflector pulley 7 by the lifting and lowering of the car 3. At the bent portion of the wire rope 10, the core rope 20 and the wire strands 30 rub against each other, so that the outer circumferential surface of the core rope 20 wears, and the diameter of the core rope 20 decreases. When the diameter of the core rope 20 is reduced, adjacent strands 30 are rubbed against each other soon thereafter, and the strands 30 are also worn down to reduce the diameter, so that the rope 10 may be broken soon.

Therefore, the wire rope 10 is required to have small elastic elongation and excellent durability.

Based on the above, the structure of the core rope 20 according to the present embodiment for obtaining the wire rope 10 having small elastic elongation and excellent durability will be described in detail. Fig. 4 is a schematic cross-sectional view of the core rope 20 according to embodiment 1, and is an enlarged view of the core rope 20 in fig. 2.

As described above, the core rope 20 is formed by twisting a plurality of core rope strands 21, and the core rope strands 21 have an inner core 22 and a plurality of outer cores 23 arranged on the outer periphery of the inner core 22. The inner core 22 is formed of a yarn (yarn) formed by twisting a plurality of first synthetic fibers. The outer core 23 is formed of a yarn formed by twisting a plurality of second synthetic fibers. Hereinafter, the first synthetic fiber and the second synthetic fiber are collectively referred to as "synthetic fibers". The synthetic fibers are multifilament, monofilament, or textile threads, etc. The yarn is a yarn formed by twisting synthetic fibers.

Here, the compressive yield strength will be described. The compressive yield strength is a compressive stress at which the synthetic fiber starts to undergo plastic deformation upon compressive deformation in the radial direction of the synthetic fiber. In particular, the compressive stress at which the first synthetic fiber starts to undergo plastic deformation upon compressive deformation in the radial direction of the first synthetic fiber is set as the first compressive yield strength. The compressive stress at which the second synthetic fiber starts to undergo plastic deformation at the time of compressive deformation in the radial direction of the second synthetic fiber is set to the second compressive yield strength. In this embodiment, the second compressive yield strength is higher than the first compressive yield strength.

The first compressive yield strength and the second compressive yield strength are collectively referred to herein as "compressive yield strengths". The radial direction of the synthetic fibers is a direction perpendicular to the axial direction of the synthetic fibers, and is a YZ plane direction in the rectangular coordinate system XYZ shown in fig. 4.

The method of calculating the compressive yield strength will be described with reference to fig. 5. Fig. 5 is a graph illustrating compressive yield strength of embodiment 1.

First, a synthetic fiber having a diameter d (μm) and a length L (μm) is compressed in the radial direction of the synthetic fiber using a micro compression tester. As a result of the measurement, a relationship between the compressive strength P (N) and the displacement (μm) as the variation of the synthetic fiber can be obtained. Based on the measurement result, the relation between the compressive strength St (MPa) and the displacement (μm) was obtained using a calculation formula of the compressive strength St (MPa) =2p/pi dL. Fig. 5 is a graph in which the compressive strength St (MPa) obtained above is plotted against the displacement (μm) with the vertical axis representing the compressive strength St (MPa) and the horizontal axis representing the displacement (μm). As shown in fig. 5, the relationship between the compressive strength St (MPa) and the displacement (μm) is such that a gentle curve is drawn after linear displacement. In the linear transition range, it is indicated that the synthetic fiber is undergoing elastic deformation. On the other hand, the start of plastic deformation of the synthetic fiber is indicated from the point of time when the gentle curve starts to be drawn. Here, as shown in fig. 5, an intersection Z between a straight line Y and a curve obtained by moving a straight line X of a linearly moving range by 2% of a diameter d (μm) in parallel is defined as a compressive yield strength (MPa).

The high compressive yield strength means that the compressive stress required for plastically deforming the synthetic fiber is large, and the synthetic fiber is not easily plastically deformed by the compressive stress. Synthetic fibers that have not been plastically deformed are elastically deformed against compressive stress. That is, when the compressive stress is removed, the shape of the synthetic fiber deformed by the compressive stress is restored to the original shape of the synthetic fiber. On the other hand, even when the compressive stress is removed from the synthetic fiber having undergone plastic deformation, the shape of the synthetic fiber deformed by the compressive stress is not restored to the original shape of the synthetic fiber. In general, the cross-sectional shape in the radial direction of the synthetic fibers that are not plastically deformed is circular, but the cross-sectional shape in the radial direction of the synthetic fibers that are plastically deformed becomes angular shape due to the synthetic fibers deforming in a flattened manner.

As described above, the second compressive yield strength is higher than the first compressive yield strength. That is, the second synthetic fiber requires a larger compressive stress for plastic deformation than the first synthetic fiber. Therefore, in the compression shaping in the wire rope manufacturing step described later, the plurality of second synthetic fibers forming the outer core 23 are less likely to be plastically deformed than the plurality of first synthetic fibers forming the inner core 22. Moreover, the radial cross section of the second synthetic fiber maintains a more circular shape than the radial cross section of the first synthetic fiber.

If the second synthetic fibers are plastically deformed, the radial cross-sectional shape of the second synthetic fibers is deformed so as to be flattened by the wire strands 30 and the synthetic fibers, and thus becomes a relatively angular shape. In this case, the surface area of the second synthetic fibers in contact with the strands 30 is larger than in the case where the second synthetic fibers have a circular cross-sectional shape in the radial direction. Therefore, the wire rope 10 is more likely to have a reduction in the diameter of the core rope 20 due to abrasion between the core rope 20 and the wire strands 30 when the second synthetic fibers are plastically deformed than when the second synthetic fibers are not plastically deformed.

In contrast, the wire rope 10 of the present embodiment has a higher second compressive yield strength than the first compressive yield strength, and therefore can reduce the surface area of the second synthetic fibers forming the outer core 23 in contact with the wire strands 30. Therefore, the wire rope 10 can suppress a decrease in the diameter of the core rope 20 due to abrasion between the core rope 20 and the wire strands 30, and thus is excellent in durability.

In another aspect, the first compressive yield strength is lower than the second compressive yield strength. That is, the first synthetic fibers are plastically deformed with respect to a smaller compressive stress than the second synthetic fibers. Therefore, in the compression shaping in the wire rope manufacturing step described later, the plurality of first synthetic fibers forming the inner core 22 are more likely to be plastically deformed than the plurality of second synthetic fibers forming the outer core 23. The cross section in the radial direction of the first synthetic fibers is angular compared with the cross section in the radial direction of the second synthetic fibers, in other words, the first synthetic fibers forming the inner core 22 have smaller voids than the second synthetic fibers forming the outer core 23. In addition, when the load acting on the wire rope 10 is removed, the first synthetic fiber that has undergone plastic deformation does not recover from the state in which plastic deformation has occurred. Thus, for example, the diameter of the inner core 22 formed of the first synthetic fiber is less likely to change than the inner core formed of the second synthetic fiber. Therefore, for example, the inner core 22 formed of the first synthetic fiber is less likely to cause elongation of a' -a of fig. 3 than the inner core formed of the second synthetic fiber, and therefore elastic elongation of the wire rope 10 can be suppressed.

The plurality of outer cores 23 are spirally arranged on the outer periphery of the inner core 22 so that the surface of the inner core 22 is not exposed. Thus, the outer core 23 is located between the inner core 22 and the wire strands 30, and the inner core 22 is not in contact with the wire strands 30. If the inner core 22 is in contact with the strands 30, the first synthetic fibers forming the inner core 22 are more likely to be plastically deformed than the second synthetic fibers, and therefore the contact area between the first synthetic fibers and the strands 30 is increased. Therefore, the wire rope 10 in which the inner core 22 is in contact with the strands 30 is more likely to cause a reduction in the diameter of the core rope 20 than the wire rope 10 in which the inner core 22 is not in contact with the strands 30. Therefore, the wire rope 10 according to the present embodiment is configured such that the inner core 22 and the wire strands 30 are not in contact with each other, and thus the reduction in diameter of the core rope 20 can be suppressed, and thus the durability is excellent.

Next, a method of manufacturing the wire rope 10 will be described. Hereinafter, the steps of producing the core rope, producing the strands, and producing the wire rope will be described.

In the core rope manufacturing process, the core rope 20 is manufactured as follows.

First, a yarn obtained by twisting a plurality of first synthetic fibers and a yarn obtained by twisting a plurality of second synthetic fibers are produced. The individual yarns may be impregnated with oil.

Then, the inner core 22 is formed by a yarn formed by twisting a plurality of first synthetic fibers, and the outer core 23 is formed by a plurality of yarns formed by twisting a plurality of second synthetic fibers.

Next, the core rope strands 21 are produced. The core rope strands 21 are spirally arranged with the plurality of outer cores 23 on the outer periphery of the inner core 22 so that the surface of the inner core 22 is not exposed.

Then, the plurality of core rope strands 21 are twisted to produce the core rope 20. For example, 3 core rope strands 21 are twisted to produce the core rope 20.

Next, in the strand manufacturing step, the plurality of steel wires 31 are bundled and twisted to manufacture the strand 30.

In the wire rope manufacturing step, the wire rope 10 is manufactured by disposing the plurality of wire strands 30 on the outer periphery of the core rope 20 and subjecting the core rope 20 and the plurality of wire strands 30 to compression shaping.

The wire rope manufacturing process will be described in detail with reference to fig. 6. Fig. 6 is a schematic cross-sectional view illustrating a wire rope manufacturing process according to embodiment 1. First, the plurality of steel wire strands 30 are twisted at a predetermined interval to cover the outer circumference of the core rope 20 so that the surface of the core rope 20 is not exposed. Then, the structure of the plurality of strands 30 on the outer Zhou Niange of the core rope 20 is passed through a clamp for shaping, i.e., a vice, and compression shaping is performed by two post-forming rollers 40 as shown in fig. 6. The rear forming roller 40 is a roller having semicircular grooves, and the two rear forming rollers 40 are disposed so that the grooves face each other. The wire rope 10 passes between the grooves of the two rear forming rollers 40, and is thus compressively shaped to the diameter of the semicircular groove provided in the rear forming roller 40. More specifically, the wire rope 10 moves in the axial direction of the wire rope 10 and passes between the grooves of the two post-forming rollers 40. Thereby, the wire rope 10 is compressively reshaped in the radial direction of the wire rope 10 by the two post-forming rollers 40.

Through the above steps, the wire rope 10 is manufactured.

Next, the results of evaluating the radial cross section of the wire rope 10 according to embodiment 1 and the relationship between the load and elongation of the wire rope 10 shown in fig. 3 will be described with reference to table 1. Table 1 shows the evaluation results of the wire rope 10 according to embodiment 1 and the wire ropes 11 and 12 according to the comparative example. The "good" is determined when the elastic elongation is suppressed compared to a general conventional wire rope, and the "bad" is determined when the elastic elongation is not suppressed compared to a conventional wire rope. Further, the "good" is determined when the durability is superior to that of the conventional wire rope, and the "poor" is determined when the durability is inferior to that of the conventional wire rope.

Table 1 evaluation results of the wire rope 10 according to embodiment 1 and the wire ropes 11 and 12 according to the comparative example

The evaluation targets were the wire rope 10 of embodiment 1, the wire rope 11 of comparative example 1, and the wire rope 12 of comparative example 2. These steel cords 10, 11, 12 have a core yarn 21 made of at least one of polypropylene fibers and polyester fibers. The polypropylene fiber is manufactured by Mitsubishi chemical, trade name "Pylen",760dtex. Polyester fibers are manufactured by Tory under the trade name "Tetoron",560dtex. The compressive yield strength of the polyester fiber is higher than that of the polypropylene fiber.

The wire rope 10 of embodiment 1 is manufactured by the manufacturing method described above. The inner core 22 is formed of yarns in which 52 polypropylene fibers are bundled and twisted as first synthetic fibers. The outer core 23 is formed of a yarn obtained by bundling and twisting 4 polyester fibers as the second synthetic fibers. The wire rope 10 according to embodiment 1 has a structure in which 24 outer cores 23 are disposed on the outer periphery of the inner core 22, and the wire rope 10 is compressed and formed to have a diameter of 12mm by two post-forming rollers 40.

Both the inner core 22 and the outer core 23 of the steel wire rope 11 of comparative example 1 are formed of yarns obtained by bundling and twisting polyester fibers. Both the inner core 22 and the outer core 23 of the steel wire rope 12 of comparative example 2 are formed of yarns obtained by bundling and twisting polypropylene fibers. The wire rope 11 of comparative example 1 and the wire rope 12 of comparative example 2 have the same structure as the wire rope 10 of embodiment 1 described above, except that the type of synthetic fiber forming the core rope 20 is one.

As a result of observation of the radial cross section of the steel wire rope 11 of comparative example 1, the radial cross section of the polyester fiber was not plastically deformed but was maintained in a circular shape, and a state where there were many voids between the polyester fibers was obtained. The evaluation result means that the surface area of the polyester fiber forming the outer core 23 in contact with the strands 30 is small, and therefore, the reduction in the diameter of the core rope 20 due to abrasion between the core rope 20 and the strands 30 is suppressed. Therefore, the steel wire rope 11 of comparative example 1 is excellent in durability.

On the other hand, as a result of evaluating the relationship between the load and elongation of the wire rope 11 of comparative example 1, it was found that the elongation between a' -a of fig. 3 occurred. This is because, as described above, since the polyester fiber is not plastically deformed, the core rope 20 exerts a high repulsive force against compressive stress.

As a result of observation of the radial cross section of the steel wire rope 12 in comparative example 2, the radial cross section of the polypropylene fiber was plastically deformed, and the polypropylene fiber was in a dense state with few voids between the polypropylene fibers. Further, since the polypropylene fibers are plastically deformed, the surface area of the polypropylene fibers forming the outer core 23 in contact with the wire strands 30 becomes large. Therefore, the diameter of the core rope 20 tends to be reduced by abrasion between the core rope 20 and the wire strands 30, and the wire rope 12 of comparative example 2 is inferior in durability to the wire rope 11 of comparative example 1.

On the other hand, as a result of evaluating the relationship between the load and elongation of the wire rope 12 of comparative example 2, it was found that the elongation between a' -a of fig. 3 was suppressed, and the elastic elongation was smaller than that of the wire rope 11 of comparative example 1. This is because, as described above, since the polypropylene fiber is plastically deformed, the diameter of the core rope 20 is not recovered even if the load is removed from the wire rope 12 of comparative example 2.

Next, the results obtained by observing the radial cross section of the wire rope 10 of embodiment 1 will be described. The radial cross section of the inner core 22 was deformed plastically, and the gaps between the polypropylene fibers were small, as in the case of the steel wire rope 12 of comparative example 2, in the radial cross section of the polypropylene fibers forming the inner core 22. The radial cross section of the outer core 23 is circular without plastic deformation, as in the case of the wire rope 11 of comparative example 1, and the number of voids between the polyester fibers is large in the radial cross section of the polyester fibers forming the outer core 23.

As a result of evaluating the relationship between the load and the elongation of the wire rope 10 according to embodiment 1, it was found that the elastic elongation was smaller than that of the wire rope 11 according to comparative example 1, and the elongation between a' -a in fig. 3 was suppressed as much as that of the wire rope 12 according to comparative example 2.

The reason why the elastic elongation is suppressed is considered to be that the polypropylene fibers forming the inner core 22 are plastically deformed so that the diameter of the inner core 22 is not recovered even if the load is removed. Further, since the radial cross section of the polyester fiber forming the outer core 23 is maintained in a circular shape without plastic deformation, the decrease in diameter of the core rope 20 due to abrasion between the core rope 20 and the wire strands 30 is suppressed. Therefore, the durability of the wire rope 10 of embodiment 1 is as excellent as the durability of the wire rope 11 of comparative example 1.

As described above, the wire rope 10 of the present embodiment includes the core rope 20 formed by twisting the plurality of core rope strands 21. The core rope yarn 21 has an inner core 22 and a plurality of outer cores 23, the inner core 22 being formed of yarns formed by twisting a plurality of first synthetic fibers, the plurality of outer cores 23 being formed of yarns formed by twisting a plurality of second synthetic fibers, and being disposed on the outer periphery of the inner core 22. The second compressive yield strength is higher than the first compressive yield strength, and is a compressive stress at which the second synthetic fiber starts to undergo plastic deformation when the second synthetic fiber is compressively deformed in a radial direction perpendicular to the axial direction, and the first compressive yield strength is a compressive stress at which the first synthetic fiber starts to undergo plastic deformation when the first synthetic fiber is compressively deformed in a radial direction perpendicular to the axial direction. This makes it possible to provide the steel wire rope 10 excellent in durability by the outer core 23 while suppressing elastic elongation by the inner core 22.

The first synthetic fiber has a radial cross section having an angular shape that is larger than the radial cross section of the second synthetic fiber. This means that the first synthetic fibers forming the inner core 22 are in a state of plastic deformation compared to the second synthetic fibers. This makes it possible to provide the steel wire rope 10 excellent in durability by the outer core 23 while suppressing elastic elongation by the inner core 22.

The elevator 10 of the present embodiment includes a wire rope 10, a car 3 connected to one end of the wire rope 10, a counterweight 4 connected to the other end of the wire rope 10, and a hoisting machine for lifting and lowering the car 3 and the counterweight 4 by rotating a sheave 6 around which the wire rope 10 is wound. As described above, the elastic elongation of the wire rope 10 is suppressed. Therefore, the expansion and contraction of the wire rope 10 generated when the passenger gets on and off the car 3 is suppressed. Thus, the elevator 1 of the present embodiment can suppress vibration of the car 3. In addition, as described above, the durability of the wire rope 10 is excellent. Thus, the elevator 1 of the present embodiment can extend the product life of the elevator 1.

Embodiment 2

The wire rope 10 of embodiment 2 will be described.

In embodiment 1, it is described that the first synthetic fiber and the second synthetic fiber have different compressive yield strengths, and the second compressive yield strength is higher than the first compressive yield strength. In the present embodiment, in the step of producing the core rope 20, the first compressive yield strength is 15MPa or less, and the second compressive yield strength is higher than 15 MPa. The structure of the wire rope 10 is the same as that of embodiment 1 except for this. The same reference numerals are given to the same structures as those of embodiment 1.

First, the results obtained by calculating the compressive yield strengths of various synthetic fibers will be described. The calculation method is the same as the calculation method of the compressive yield strength described in embodiment 1. The compression yield strength of the polyarylate fiber is 15MPa, and the compression yield strength of the polyester fiber is 22MPa. In addition, it is known that the compressive yield strength of polypropylene fibers is lower than that of polyarylate fibers, and that the compressive yield strength of polyethylene naphthalate fibers, polyphenylene sulfide fibers, and aramid fibers is higher than that of polyester fibers.

Next, from among the synthetic fibers for which the compressive yield strength is calculated, the first synthetic fiber and the second synthetic fiber are selected in various combinations, and the steel wire rope 10 is produced by the production method described in embodiment 1. The first and second synthetic fibers are selected in such a way that the second compressive yield strength is higher than the first compressive yield strength. Then, the radial cross sections of the produced wire ropes 10 were observed. The results are described below.

Here, the values of the first compressive yield strength and the second compressive yield strength are changed by the compression shaping by the post forming roll 40 described in embodiment 1. However, the magnitude relationship of the first compressive yield strength to the second compressive yield strength is unchanged. That is, in the core rope manufacturing step described in embodiment 1, when the first synthetic fiber and the second synthetic fiber are selected so that the second compressive yield strength is higher than the first compressive yield strength based on the value of the compressive yield strength, the second compressive yield strength is higher than the first compressive yield strength even after the compression shaping by the post-forming roller 40.

The results of the steel wire rope 10 in which the inner core 22 is formed of a yarn obtained by bundling and twisting the polyarylate fibers as the first synthetic fibers, and the outer core 23 is formed of a yarn obtained by bundling and twisting the polyester fibers as the second synthetic fibers will be described. Fig. 7 is a cross-sectional view of the wick 20 of embodiment 2. The inner core 22 is to the right of the broken line of fig. 7, and the outer core 23 is to the left of the broken line. As can be seen from fig. 7, in the polyarylate fiber forming the inner core 22, the cross section of the polyarylate fiber in the radial direction is plastically deformed and takes the shape of an angular shape. On the other hand, it is found that the polyester fiber forming the outer core 23 is not plastically deformed in the radial cross section, and is maintained in a circular shape as compared with the polyarylate fiber.

Although other evaluation results of the produced wire rope 10 were omitted, synthetic fibers having a compressive yield strength of 15MPa or less, which is the compressive yield strength of the polyarylate fibers, were likely to undergo plastic deformation, and synthetic fibers having a compressive yield strength higher than 15MPa, which is the compressive yield strength of the polyarylate fibers, were not likely to undergo plastic deformation.

It is also found that the elongation of a' -a in fig. 3 is suppressed in the steel wire rope 10 in which the inner core 22 is made of synthetic fibers having a compressive yield strength of 15MPa or less, compared with the steel wire rope 10 in which the inner core 22 is made of synthetic fibers having a compressive yield strength of 15MPa or more. This is considered to be because synthetic fibers having a compressive yield strength of 15MPa or less are easily plastically deformed, and the diameter of the inner core 22 is not recovered even if the load is removed from the wire rope 10.

Further, the durability of the steel wire rope 10 in which the outer core 23 is made of synthetic fibers having a compressive yield strength of 15Mpa or less is excellent as compared with the steel wire rope 10 in which the outer core 23 is made of synthetic fibers having a compressive yield strength of 15Mpa or less. This is because synthetic fibers having a compressive yield strength higher than 15Mpa are less likely to be plastically deformed, and therefore, by maintaining the synthetic fibers in a circular cross section, the diameter of the core rope 20 is prevented from decreasing due to abrasion between the core rope 20 and the wire strands 30.

Based on the above results, the first synthetic fiber and the second synthetic fiber according to the present embodiment are configured as follows.

In the core rope manufacturing process described in embodiment 1, the first compressive yield strength of the first synthetic fiber is 15MPa or less. For example, the first synthetic fiber is at least one of a polypropylene fiber and a polyarylate fiber. In particular, polypropylene fibers are less expensive than other synthetic fibers and are therefore preferred for use as the first synthetic fibers. Further, since the core rope 20 has a function of supplying oil necessary for lubrication and rust prevention of the wire strands 30, synthetic fibers having a melting point higher than that of the oil are suitable as the first synthetic fibers.

In the core rope manufacturing step described in embodiment 1, the second compressive yield strength of the second synthetic fiber is higher than 15 Mpa. For example, the second synthetic fiber is at least one of a polyester fiber, a polyphenylene sulfide fiber, a polyethylene naphthalate fiber, and an aramid fiber. In particular, polyester fibers are inexpensive compared with other fibers and are excellent in retention of tensile strength after abrasion, and therefore are suitable as second synthetic fibers.

As in embodiment 1, the wire rope 10 of the present embodiment includes a core rope 20 formed by twisting a plurality of core rope strands 21. The core rope yarn 21 has an inner core 22 and a plurality of outer cores 23, the inner core 22 is formed of yarns formed by twisting a plurality of first synthetic fibers, the plurality of outer cores 23 is formed of yarns formed by twisting a plurality of second synthetic fibers, and the plurality of outer cores are disposed on the outer periphery of the inner core 22. Moreover, the second compressive yield strength is higher than the first compressive yield strength. This makes it possible to provide the steel wire rope 10 excellent in durability by the outer core 23 while suppressing elastic elongation by the inner core 22.

In the process of producing the core rope 20, the wire rope 10 of the present embodiment has a first compressive yield strength of 15MPa or less and a second compressive yield strength higher than 15MPa, so that the effect of suppressing elastic elongation and having excellent durability is more remarkable.

The first synthetic fiber is at least one of a polypropylene fiber and a polyarylate fiber. In this way, in the step of producing the core rope 20, the first compressive yield strength can be set to 15MPa or less. Therefore, the wire rope 10 of the present embodiment can suppress elastic elongation by the inner core 22.

The second synthetic fiber is at least one of a polyester fiber, a polyphenylene sulfide fiber, a polyethylene naphthalate fiber, and an aramid fiber. In this way, in the step of producing the core rope 20, the second compressive yield strength can be made higher than 15 Mpa. Therefore, the wire rope 10 of the present embodiment is excellent in durability by the outer core 23.

In the embodiments, the yarn formed by twisting the plurality of first synthetic fibers is shown as an example of the inner core 22, but the present invention is not limited thereto. The yarn may be formed of a yarn in which a plurality of first synthetic fibers and a plurality of second synthetic fibers are mixed. The inner core 22 may be formed by twisting two kinds of yarns, that is, a yarn obtained by twisting a plurality of first synthetic fibers and a yarn obtained by mixing a plurality of first synthetic fibers and a plurality of second synthetic fibers. That is, the inner core 22 is formed of at least one of a yarn formed by twisting a plurality of first synthetic fibers and a yarn formed by mixing a plurality of first synthetic fibers and a plurality of second synthetic fibers. In these inner cores 22, the plurality of first synthetic fibers are plastically deformed by the compression shaping in the above-described wire rope manufacturing step, and the gaps between the synthetic fibers are made small. Further, since the first synthetic fiber is in a state where plastic deformation occurs, elongation of a' -a of fig. 3 is suppressed. This makes it possible to provide the steel wire rope 10 excellent in durability by the outer core 23 while suppressing elastic elongation by the inner core 22.

In the embodiments, the wire rope 10 having the 8×s (19) structure is described as an example, but the invention is not limited thereto, and may be, for example, 8×s (19), 8×w (19), or 8×fi (25) structures defined by JISG 3525. The use of the wire rope 10 according to each embodiment is not limited to the elevator 1, and can be used for machines, buildings, ships, fishery, forestry, mining, and cableways.

It is needless to say that various design changes can be made within a range in which the object of the present invention can be achieved without departing from the gist of the present invention.

Description of the reference numerals

1 Elevator, 2 machine room, 3 car, 4 counterweight, 5 hoistway, 6 sheave, 7 deflector sheave, 8 control device, 10 wire rope, 20 core rope, 21 core rope strand, 22 inner core, 23 outer core, 30 wire strand, 31 wire, 40 post forming roll.

Claims (7)

1. A steel wire rope comprising:

A core rope formed by twisting a plurality of core rope strands, the core rope strands having an inner core formed of at least one of a yarn formed by twisting a plurality of first synthetic fibers and a yarn formed by mixing a plurality of first synthetic fibers and a plurality of second synthetic fibers, and a plurality of outer cores formed of a yarn formed by twisting a plurality of second synthetic fibers and disposed on the outer periphery of the inner core; and

A plurality of steel wire strands disposed on the outer periphery of the core rope, the plurality of steel wires being twisted,

The second compressive yield strength is higher than the first compressive yield strength, and is a compressive stress at which the second synthetic fiber starts to be plastically deformed when the second synthetic fiber is compressively deformed in a radial direction perpendicular to the axial direction, and the first compressive yield strength is a compressive stress at which the first synthetic fiber starts to be plastically deformed when the first synthetic fiber is compressively deformed in a radial direction perpendicular to the axial direction.

2. A steel cord according to claim 1, characterized in that,

The radial cross section of the first synthetic fiber is angular in shape from the radial cross section of the second synthetic fiber.

3. A steel cord according to claim 1 or 2, characterized in that,

The first synthetic fiber is at least one of a polypropylene fiber and a polyarylate fiber.

4. A steel cord as claimed in any one of claims 1 to 3, characterized in that,

The second synthetic fiber is at least one of polyester fiber, polyphenylene sulfide fiber, polyethylene naphthalate fiber and aramid fiber.

5. An elevator, characterized by comprising:

a wire rope;

the elevator car is connected with one end of the steel wire rope and is suspended in a hoistway;

the counterweight is connected with the other end of the steel wire rope and is suspended in the hoistway; and

A hoisting machine having a sheave around which the wire rope is wound, the hoisting machine being configured to raise and lower the car and the counterweight by rotating the sheave,

The steel wire rope has:

A core rope formed by twisting a plurality of core rope strands, the core rope strands having an inner core formed of at least one of a yarn formed by twisting a plurality of first synthetic fibers and a yarn formed by mixing a plurality of first synthetic fibers and a plurality of second synthetic fibers, and a plurality of outer cores formed of a yarn formed by twisting a plurality of second synthetic fibers and disposed on the outer periphery of the inner core; and

A plurality of steel wire strands disposed on the outer periphery of the core rope, the plurality of steel wires being twisted,

The second compressive yield strength is higher than the first compressive yield strength, and is a compressive stress at which the second synthetic fiber starts to be plastically deformed when the second synthetic fiber is compressively deformed in a radial direction perpendicular to the axial direction, and the first compressive yield strength is a compressive stress at which the first synthetic fiber starts to be plastically deformed when the first synthetic fiber is compressively deformed in a radial direction perpendicular to the axial direction.

6. A method for manufacturing a wire rope, comprising:

A step of producing a core rope strand in which a plurality of outer cores are arranged on the outer periphery of an inner core, the inner core being formed of at least one of a yarn formed by twisting a plurality of first synthetic fibers and a yarn formed by mixing a plurality of first synthetic fibers and a plurality of second synthetic fibers, and the plurality of outer cores being formed of a yarn formed by twisting a plurality of second synthetic fibers;

Twisting a plurality of the core rope strands to produce a core rope; and

A step of arranging a plurality of strands of twisted steel wires on the outer periphery of the core rope, and performing compression shaping on the core rope and the plurality of strands of steel wires,

The second compressive yield strength is higher than the first compressive yield strength, and is a compressive stress at which the second synthetic fiber starts to be plastically deformed when the second synthetic fiber is compressively deformed in a radial direction perpendicular to the axial direction, and the first compressive yield strength is a compressive stress at which the first synthetic fiber starts to be plastically deformed when the first synthetic fiber is compressively deformed in a radial direction perpendicular to the axial direction.

7. The method of manufacturing a steel wire rope according to claim 6, wherein,

In the step of producing the core rope strand, the first compressive yield strength is 15MPa or less, and the second compressive yield strength is higher than 15 MPa.