Fall prevention rope and object fall prevention structure using the same

Abstract

To provide a fall prevention rope that makes a loop hardly loosened even when an insertion length of a braided rope is short.SOLUTION: In a fall prevention rope 10, a loop 13 is formed at at least one end of a hollow braided rope 11 by passing a tip 111 of the braided rope 11 through inside the braided rope 11. The braided rope 11 is obtained by braiding a strand 12 with increased hardness by coating an outer peripheral surface of a high-strength fiber bundle, which is a fiber core material, with a polyethylene-based resin.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a fall prevention rope and a structure for preventing an object from falling using the same. [Background technology]

[0002] Conventionally, various ropes using strong fibers have been used as devices to prevent road equipment, etc., installed at high places from falling. Patent Document 1, which was previously filed by the applicant of the present application, describes a fall prevention structure in which a fall prevention rope is further attached to road equipment fixed by mounting brackets.

[0003] The fall prevention rope described in Patent Document 1 has a loop formed at the end of a hollow braided rope made of high-strength fibers by eye processing, in which the tip of the braided rope is passed through the inside of the braided rope and pulled out. The loop formed by eye processing can be easily made or released on-site, so the length of the rope and the size of the loop can be easily adjusted depending on the situation on-site. The fall prevention rope is attached to road equipment, etc. via this loop.

[0004] When tension is applied to the loop of the fall prevention rope, the braided rope shrinks and tightens, and the braided rope passed through the inside is tightened from the outside and restrained. In this way, if the mounting bracket comes off, the base end of the loop is strongly tightened by the impact load, preventing the road equipment from falling.

[0005] In the loop structure formed by the above-mentioned eye processing, the friction between the inserted braided rope and the inserted braided rope keeps the loop from coming undone. If the friction between the braided ropes is small, the braided rope may come undone and the loop may come undone when tension is applied. If the insertion length is increased to prevent the braided rope from coming undone, the entire fall prevention rope becomes longer, which is problematic when the objects to be attached are close to each other.

[0006] The invention described in Patent Document 1 does not have the technical idea of ​​making a braided rope that is difficult to come loose even if the insertion length of the braided rope is short. The fall prevention rope described in Patent Document 1 is a braided rope that has been resin-treated, and the outer circumference of each strand is not resin-coated. Resin-treatment of a braided rope has the effect of increasing the durability of the high-strength fibers, but does not have the effect of improving the resistance of the loop to coming undone. In order to maintain the loop against strong tension in the fall prevention rope described in Patent Document 1, the insertion length of the braided rope needs to be considerably longer, and there is room for improvement in this regard. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Utility Model Registration No. 3226707 Summary of the Invention [Problem to be solved by the invention]

[0008] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to solve the above-mentioned problems of the conventional rope and to provide a fall prevention rope in which the loop is unlikely to come undone even if the insertion length of the braided rope is short. [Means for solving the problem]

[0009] In order to solve the above problems, a fall prevention rope is provided in which a loop is formed at at least one end of a hollow braided rope by passing the tip of the braided rope through the inside of the braided rope, and the braided rope is made by braiding strands whose hardness has been increased by covering the outer surface of a high-strength fiber bundle, which is a fiber core material, with a polyethylene resin.

[0010] The strands preferably have a compressibility of 0.7 or more under a load of 5 N / mm.

[0011] In addition, when the length of the overlapping portion where the braided rope is doubled on the base end side of the loop is defined as the insertion length of the braided rope, it is preferable that the slip-out tension is at least 4 kN when the insertion length is 10 cm.

[0012] In addition, it is preferable that the crossing angle of the strands with respect to the longitudinal direction of the braided rope is 19° or more.

[0013] The present invention also provides a structure for preventing an object from falling when the object is fixed by a mounting bracket, in which the fall prevention rope is attached to the object by using the loop. Effect of the Invention

[0014] The present invention can provide a fall prevention rope whose loop is unlikely to come undone even if the insertion length of the braided rope is short. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is a schematic diagram showing a fall prevention rope according to an embodiment. [Diagram 2] 1 is a schematic diagram of a braided rope according to an embodiment, in which (a) shows a side view of the braided rope and (b) shows a cross section of a strand. [Diagram 3] FIG. 13 is an explanatory diagram of the compressibility of a strand. [Figure 4] FIG. 1 is a schematic diagram of a fall prevention rope used in a tensile test. [Diagram 5] 13 is a graph showing the measurement results of the loop slippage tension. [Figure 6] 1(a) is an explanatory diagram showing the relationship between the cross angle of the strands and the tightening force of the braided rope, and (b) is a graph showing an example of calculation of the tightening force of the braided rope. [Figure 7] FIG. 2 is a side view showing the fall prevention structure of the embodiment. [Figure 8] FIG. 8 is a front view showing the fall prevention structure of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] (Fall prevention rope) The following describes an embodiment of the invention. First, a description will be given of the main configuration of a fall prevention rope 10. The fall prevention rope 10 of the embodiment shown in FIG.

[0017] As shown in Fig. 2(a), the braided rope 11 of the embodiment is a hollow rope in which 16 strands 12 are grouped in pairs and braided in a 2 x 8 pattern. The braiding method of the braided rope 11 is not limited to 2 x 8 braiding, and other braiding methods such as 1 x 8 braiding can be used. The configuration of the strands 12 will be described in detail later.

[0018] When the braided rope 11 of the embodiment is contracted in the longitudinal direction, the diameter of the braided rope 11 increases and the gaps in the braid widen. When the braided rope 11 is pulled from both sides in the longitudinal direction, the diameter of the braided rope 11 is reduced and the gaps in the braid narrow. This allows the braided rope 11 of the embodiment to easily form or release loops 13, which will be described later.

[0019] (Method of forming a loop) 1, the fall prevention rope 10 of the embodiment has a loop 13 at at least one end. The loop 13 is formed by passing the tip 111 of the braided rope 11 through the inside of the braided rope 11 and pulling it out.

[0020] The method of forming the loop 13 is the same as the method of forming a loop described in Prior Art Document 1. Specifically, a tape T is wound around the tip 111 of the braided rope 11 to form a tapered shape, and the tip is inserted into an opening at the rear end of a jig (not shown) that is a hollow chopstick-shaped body. Next, the tip of the jig is inserted into the center of the braided rope 11, and pulled out to the outside of the braided rope 11 from a position some distance away.

[0021] Thereafter, the jig is removed from the braided rope 11, and a loop 13 is formed at the end of the fall prevention rope 10 as shown in Fig. 1. On the base end side of the loop 13, an overlapping portion 14 is formed where the braided rope 11 overlaps twice in the radial direction.

[0022] 4, in the overlapping portion 14, the insertion side braided rope 11b is inserted inside the outer braided rope 11a on the radially outer side. The length of the overlapping portion 14 is defined as an insertion length L1 of the braided rope 11.

[0023] When tension is applied outward in the longitudinal direction to both ends of the fall prevention rope 10, the braided rope 11 contracts in diameter. At this time, the outer braided rope 11a frictionally restrains the insertion side braided rope 11b at the overlapping portion 14, so the insertion side braided rope 11b is not pulled out and the loop 13 is maintained. When the tension is released, the insertion side braided rope 11b can be freely pulled out.

[0024] In the fall prevention rope 10, the longer the insertion length L1, the greater the frictional restraining force that can be obtained. If there is ample space in the installation location and there are few restrictions on the overall length of the fall prevention rope 10, the insertion length L1 may be increased as necessary.

[0025] (Strand) 2(b), the strand 12 of the embodiment includes a high-strength fiber bundle 121 formed by bundling high-strength fibers that are a fiber core material, and a resin coating 122 that covers the outer circumferential surface of the high-strength fiber bundle 121. The strand 12 of the embodiment is manufactured by a method of coating the high-strength fiber bundle 121 with a thermoplastic resin.

[0026] The high strength fiber bundle 121 of the embodiment is a polyarylate fiber. The type of the high strength fiber bundle 121 is not particularly limited, but at least one type may be selected from organic fibers such as polyarylate fiber, para-aramid fiber, polyparaphenylene benzobisoxazole fiber, high strength polyolefin fiber, high strength polyester fiber, and high strength polyvinyl alcohol fiber in terms of required strength, durability, economy, and the like.

[0027] The resin coating 122 coats the outer peripheral surface of the high strength fiber bundle 121 over the entire longitudinal direction. The resin composition constituting the resin coating 122 is preferably mainly composed of a polyethylene resin. The resin coating 122 of the embodiment is a black polyethylene resin containing a halogen-free flame retardant, and is a coating material for so-called EM electric wires and EM cables. The resin composition constituting the resin coating 122 preferably contains at least one resin selected from high density polyethylene, low density polyethylene, ethylene copolymer, flame resistant polyethylene, cross-linked polyethylene, EP rubber (ethylene propylene rubber), polyolefin, and flame resistant polyolefin as a main component.

[0028] The strands 12 are made harder to be crushed by covering the high-strength fiber bundles 121 with a resin composition containing a polyethylene resin. In addition, when the outer circumferential surface of each strand 12 is covered with a resin coating 122, the weather resistance of the fall prevention rope 10 against ultraviolet rays, rainwater, condensation, acidic components, alkaline components, temperature changes, and the like is improved.

[0029] The resin composition forming the resin coating 122 may contain flame retardants, antioxidants, reinforcing agents, UV absorbers, stabilizers, plasticizers, pigments, dyes, colorants, antistatic agents, etc., within the scope of the invention.

[0030] In the embodiment, an extruder that melts a resin composition and coats it on a core material is used to perform extrusion coating on the high strength fiber bundle 121 to form the resin coating 122. Although the coating method is not limited to this, extrusion coating is preferable because it is easy to uniformly form the resin coating 122 of a predetermined thickness.

[0031] The strand 12 in this embodiment is formed with dimensions of an outer diameter (strand thickness) of about 1.2 to 2.0 mm, and a thickness of the resin coating 122 of about 0.16 to 0.2 mm. The strand 12 in this embodiment has a strand weight of about 2.0 to 3.8 g / m. Although the dimensions of the strand 12 are not limited thereto, the thickness of the resin coating 122 is preferably 8 to 14% of the outer diameter of the strand 12, more preferably 8 to 12%, and most preferably 8 to 10%.

[0032] (Strand Compression Ratio) As described above, the hardness of the strands 12 in the embodiment is increased by coating the outer periphery of each strand with a resin. In the embodiment, the strands 12 are compressed by applying a predetermined load, and the compression ratio is measured. The compression ratio is used as an index of the crush resistance of the strands 12.

[0033] The compression ratio of the strand 12 will be described with reference to Fig. 3. In this specification, as shown in Fig. 3, when the diameter of the strand 12 before compression when no external force is applied is d0, and the diameter of the strand 12 in the compressed state with a load of 5 N / mm applied is d1, the compression ratio of the strand 12 is expressed as a value of d1 / d0. Note that in the embodiment, the load applied to the strand 12 was measured using a spring scale, and the dimensions of the diameter d0 and the diameter d1 were measured using a vernier caliper.

[0034] Table 1 shows the compression ratio of the strand 12 of the embodiment. Strand A in Table 1 is the strand 12 of the embodiment of the present invention, and is coated with a halogen-free resin (polyethylene resin). For comparison, strand B (black dope-dyed) used in the fall prevention rope described in Patent Document 1 was prepared, and the compression ratio of both strands was measured. Note that both strands A and B use polyarylate fiber as the fiber core material.

[0035] [Table 1]

[0036] As shown in Table 1, the compressibility of Strand A is greater than that of Strand B. Strand A is harder than black dyed wire because its outer circumference is coated with polyethylene resin, making it less likely to deform.

[0037] The strands 12 preferably have a compression ratio of 0.7 or more at a load of 5 N / mm. If the strands 12 are hard and not easily crushed, the interlocking force due to the unevenness of the braided ropes 11 increases, improving the frictional force. This makes it difficult for the insertion side braided rope 11b to come loose when tension is applied to the fall-prevention rope 10. By improving the difficulty of the insertion side braided rope 11b to come loose, the fall-prevention rope 10 can have loops 13 that are difficult to unravel even if the insertion length L1 is short.

[0038] (Example) Using the strand A, three hollow braided ropes 11 were made in which 16 strands were grouped into pairs and braided in a 2×8 pattern. Next, as shown in Fig. 4, loops 13 were formed on both ends of each braided rope 11 by passing the tip of the braided rope 11 through the inside of the braided rope 11 and pulling it out, thereby making three fall prevention ropes 10 with different insertion lengths L1. The insertion lengths L1 were 10 cm for Example 1, 15 cm for Example 2, and 20 cm for Example 3.

[0039] (Comparative Example) Using Strand B, three hollow braided ropes were made in which 16 strands were grouped into pairs and braided in a 2×8 pattern. Next, loops were formed on both ends of each braided rope in the same manner as in each example, and three fall prevention ropes with different insertion lengths L1 were made. The insertion lengths L1 were 10 cm for Comparative Example 1, 15 cm for Comparative Example 2, and 20 cm for Comparative Example 3.

[0040] As shown in Fig. 4, in Examples 1 to 3 and Comparative Examples 1 to 3, the rope length L2, which is the length from the base end of one loop 13 to the base end of the other loop 13, was set to be approximately twice the insertion length L1. All loops 13 were set to the same size. In Examples and Comparative Examples having the same insertion length L1, the entire length of the fall prevention rope was set to be the same.

[0041] (Loop slip tension measurement 1) A tensile tester was used to carry out tensile tests on the fall prevention ropes of Examples 1 to 3 and Comparative Examples 1 to 3, and the slippage tension was measured when the loop was released. The results are shown in Table 2 and FIG.

[0042] [Table 2]

[0043] In both the Examples and Comparative Examples, where the insertion length L1 is the same, the slippage tension of the Examples is greater. In Example 1, even though the insertion length L1 is quite short at 10 cm, the loop 13 was maintained without unraveling until the tension reached 4 kN. Similarly, when the insertion length L1 was 15 cm or 20 cm, it was found that the fall prevention rope 10 of the Examples could withstand a greater tension than the Comparative Example, and the braided rope 11 was less likely to slip out.

[0044] (Braided rope braiding structure) Next, a preferred braiding configuration of the braided rope 11 will be described. It is preferred that the braided rope 11 of the present invention has a large crossing angle θ of the strands 12. In this specification, the crossing angle θ of the strands 12 refers to an acute angle (0°<θ<90°) at which any strand 12 crosses with a virtual line C that passes through the center of the braided rope 11 and extends in the longitudinal direction of the braided rope 11, as shown in Fig. 2(a).

[0045] The tightening force of the outer braided rope 11a when tension is applied can be further improved by increasing the crossing angle θ of the strands 12 to a certain extent. The mechanism by which the tightening force of the outer braided rope 11a increases when the crossing angle θ of the strands 12 is large will be described with reference to Fig. 6.

[0046] 6(a) is a schematic diagram showing two arbitrary strands 12 constituting the outer braided rope 11a. When the distance between the peaks of the strands 12 going around the outer braided rope 11a is defined as a pitch P, the greater the crossing angle θ of the strands 12, the shorter the length of the pitch P.

[0047] When tension F is applied to the outer braided rope 11a in the longitudinal outward direction, the outer braided rope 11a contracts in diameter, and a tightening force (tightening force R) acts in the radially inward direction. The tightening force R increases as the crossing angle θ of the strands 12 increases and the pitch P decreases.

[0048] The relationship between the tightening force R and the crossing angle θ will be explained. As shown in Fig. 6(a) as a schematic, when any one point on the strand 12 is defined as the point of application WP, the vector of the tightening force R with the point of application WP as the base point is perpendicular to the imaginary line C and points radially inward. In this case, if the angle between the vector of the tightening force R and the strand 12, with the point of application WP as the vertex, is defined as α, the smaller the angle α, the greater the magnitude of the tightening force R. Here, since the smaller the angle α, the greater the crossing angle θ of the strand 12, it can be said that the greater the crossing angle θ of the strand 12, the greater the tightening force R.

[0049] 6(b) is a graph showing the relationship between the tightening force R and the pitch P, calculated assuming that the outer diameter D of the outer braided rope 11a is 8 mm and the tension F is 100 N. The tightening force R can be calculated by the following formula (1). R = F cosα (1)

[0050] Cos α in equation (1) can be calculated using the following equation (2). cosα = D / HL (2) D: Outer diameter of the outer braided rope 11a HL: Length required for the strand 12 to make a half turn (1 / 2 pitch) around the outer braided rope 11a

[0051] HL in equation (2) can be calculated using the following equation (3). HL = √{(P / 2) 2 +D 2}···(3)

[0052] Substituting equations (2) and (3) into equation (1) gives the following equation (4). R=F·{D / √{(P / 2) 2 +D 2}}···(4)

[0053] By substituting the values ​​of outer diameter D = 8 (mm) and tension F = 100 (N) into formula (4), the clamping force R was calculated when the pitch P was 5 mm, 10 mm, 15 mm, and 20 mm. The results are shown in Table 3 and Figure 6 (b).

[0054] [Table 3]

[0055] 6(b), it can be seen that the shorter the pitch P (the larger the crossing angle θ), the greater the tightening force R. Since the frictional force acting between the outer braided rope 11a and the insertion side braided rope 11b is proportional to the tightening force R, which is the load, when the tightening force R is large, the frictional force between the braided ropes 11 at the overlapping portion 14 increases, making it difficult for the insertion side braided rope 11b to slip out.

[0056] In order to verify the effect of increasing the crossing angle θ of the strands 12 to improve the resistance of the insertion side braided rope 11b to coming loose, fall prevention ropes 10 according to the following Examples 4 and 5 were prepared and subjected to tensile tests.

[0057] (Example) The configuration of the braided rope 11 used in Examples 4 and 5 is as shown in Table 4. Since there are slight individual differences in the outer diameter and mass of the braided rope 11, three braided ropes 11 were prepared and their average values ​​were calculated. The outer diameter and mass of the braided rope 11 shown in Table 4 are the average values ​​of the three braided ropes 11.

[0058] [Table 4]

[0059] Example 4 is a 2×8 braided rope 11, and Example 5 is a 1×8 braided rope 11. The strands 12 in Examples 4 and 5 are all covered with a halogen-free polyethylene resin, but Example 5, which is 1×8 braided, uses strands 12 that are thicker and harder than those in Example 4, which is 2×8 braided.

[0060] The crossing angle θ and pitch P of the strands 12 are different between Example 4 and Example 5. Example 4 is woven so that the crossing angle θ is larger and the pitch P is smaller than that of Example 5.

[0061] (Loop slip tension measurement 2) A loop 13 was formed on both ends of each braided rope 11 of Examples 4 to 5 to create a total of six fall prevention ropes 10. The insertion length L1 was 20 cm for all of them. A tensile tester was used to conduct a tensile test on the fall prevention ropes 10 of Examples 4 to 5 to measure the tension at which the loop begins to slip when released. The results are shown in Table 5.

[0062] [Table 5]

[0063] In all of Examples 4 and 5, sufficient strength was maintained even though the insertion length L1 was short at 20 cm.

[0064] Incidentally, in Example 5, the strands 12 are thick and hard, and it is assumed that the meshing force due to the unevenness of the braided ropes 11 is large, resulting in large frictional force. Example 4 is composed of strands 12 with a smaller diameter than Example 5, but is braided so that the crossing angle θ is large, and therefore it is able to withstand the same level of tension as Example 5 and maintain the constraint of the overlapping portion 14.

[0065] As described above, in the present invention, by forming the resin coating 122 on the outer periphery of each strand 12 to increase the hardness of each strand 12 itself, the frictional force between the braided ropes 11 is improved, and a fall prevention rope 10 can be obtained in which the loops 13 are less likely to come undone even if the insertion length L1 is short. In the present invention, the loops 13 are maintained even under a stronger tension than in the past, so the inherent strength of the high-strength fiber bundle 121 can be effectively utilized.

[0066] In addition, by making the crossing angle θ of the strands 12 19° or more, the frictional force between the braided ropes 11 can be further improved, making the loops 13 of the fall prevention rope 10 less likely to come undone.

[0067] (Fall prevention structure for objects) Next, a fall prevention structure that prevents an object from falling using the fall prevention rope 10 of the embodiment will be described.

[0068] 7 and 8 show an example of a fall prevention structure for a lighting equipment 20 using a fall prevention rope 10. The lighting equipment 20 of the embodiment is fixed to a wall surface W of a tunnel via a mounting bracket 21. Above the lighting equipment 20, a cable rack 30 is attached to the wall surface W via a cable rack support bracket 31. The cable rack 30 of the embodiment is a generally ladder-shaped rack in which multiple child girders are hung between two opposing parent girders 301 with a gap therebetween.

[0069] 7 and 8, one loop 13 of the fall prevention rope 10 hung on the lighting equipment 20 is attached to the parent beam 301 of the cable rack 30. Therefore, even if the lighting equipment 20 comes off the wall surface W due to deterioration of the mounting bracket 21, each loop 13 is tightly tightened by the impact load, preventing the lighting equipment 20 from falling.

[0070] The example shown in Figures 7 and 8 is a structure in which one loop 13 is attached to a cable rack 30, and the braided rope 11 is passed through the other loop 13 to create a large loop, and the lighting equipment 20 is held inside this loop, but the present invention is not limited to this structure.

[0071] For example, one of the loops 13 may be fixed to the wall surface W via an anchor bolt without using the cable rack 30. Also, the lighting fixture 20 may be provided with a mounting hole for passing the loop 13 therethrough, and the other loop 13 may be attached to this mounting hole.

[0072] The fall prevention structure of the present invention is not limited to the lighting equipment 20, but can be widely applied to prevent the fall of road equipment installed at high places, and can be used for various road equipment such as traffic lights and destination signs on roads other than tunnels. Also, it can be applied to various objects other than road equipment.

[0073] Although the present invention has been described above by taking the embodiment as an example, the present invention is not limited to the above embodiment and can be embodied in various forms. [Explanation of symbols]

[0074] 10 Fall prevention rope 11 Braided Rope 11a Outer braided rope 11b Insertion side braided rope 12 Strand 121 High-strength fiber bundle 122 Resin coating 13 Loop 14 Overlapping Parts L1 Insertion length θ intersection angle R Tightening force 20 Lighting equipment 21 Mounting bracket W wall 30 Cable rack

Claims

1. A fall prevention rope having a loop formed at at least one end of a hollow braided rope by passing a tip of the braided rope through the inside of the braided rope, The braided rope is This fall prevention rope is made by braiding strands whose hardness has been increased by covering the outer surface of a high-strength fiber bundle, which is the fiber core material, with a polyethylene resin.

2. 2. A fall prevention rope as described in claim 1, wherein the strand has a compressibility of 0.7 or more at a load of 5 N / mm.

3. When the length of the overlapping portion where the braided rope is overlapped twice on the base end side of the loop is defined as the insertion length of the braided rope, 3. A fall prevention rope as claimed in claim 1 or 2, wherein the slip-out tension when the insertion length is 10 cm is at least 4 kN.

4. 3. A fall prevention rope as claimed in claim 1 or 2, wherein the crossing angle of the strands with respect to the longitudinal direction of the braided rope is 19° or more.

5. A structure for preventing an object from falling that is fixed by a mounting bracket, A structure for preventing an object from falling, in which the fall prevention rope according to claim 1 is attached to the object by means of the loop.

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