JP7224061B2 - Lanyard - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lanyard that is connected to a safety belt to prevent a worker from high places from falling.

Workers engaged in work at heights wear safety belts to prevent them from falling from heights. The safety belt is provided with a lanyard for attachment to a fixed structure (eg, a frame of a building, scaffolding, etc.). The lanyard has an elongated strap and a hook for hooking the strap to the anchoring structure.

Conventionally, as a strap used for a lanyard, a shredded yarn that cuts at a predetermined tensile strength, an elastic yarn having a high degree of elongation characteristics, and a high-strength yarn having higher strength characteristics than the first and elastic yarns are used as warps, It is known that high-strength yarns are woven in such a manner that the yarn legs are longer than other yarns, thereby having a function of absorbing impact energy (see Patent Document 1 below).

In this device, the first yarns provided dispersedly absorb the impact energy by sequentially cutting, thereby controlling the elongation of the elastic yarns and ensuring safety with the high-strength yarns. ing.

As a result, when the strap is used for a lanyard, it is possible to absorb and mitigate the impact received by the operator from the lanyard.

JP 2010-168687 A

However, according to the structure of the conventional strap having the above configuration, the first thread is intermittently cut many times when absorbing the impact energy. Therefore, when the first yarn is sequentially cut, the time between the first cut and the next cut is an intermittent time during which the impact is not absorbed or mitigated.

In addition, a relatively long time is required to absorb the impact energy due to the occurrence of many times during which the impact is not absorbed and mitigated. As a result, in the event that the worker falls, the impact on the worker is absorbed and mitigated, and the fall distance until the fall is stopped becomes long, which is inconvenient for the worker.

The present invention has been made in view of the above points, and not only is it lightweight when attached and does not interfere with work, but also the drop distance until the fall is stopped even if the worker falls. To provide a lanyard which has a short length, is capable of sufficiently absorbing and mitigating impact, and can further improve the safety of working at height.

In order to achieve this object, the present invention provides a strap, a connector provided at one end of the strap to be connected to a safety belt, and a hook provided at the other end of the strap to be hooked to a fixing structure. , wherein the strap comprises a shock-absorbing cord having a predetermined length, and a bellows-shaped high-strength cord having a length larger than that of the shock-absorbing cord and having a number of bends. The buffer cord is formed using a half-stretched yarn that starts to stretch at a predetermined tensile load, and the high-strength cord uses a low-elongation yarn having a higher tensile strength than the buffer cord and when the high-strength cord has a bellows shape, a gap is provided between the shock-absorbing cord and the high-strength cord.

According to the present invention, the strap comprises a cushioning cord made of half-stretched yarn and a high-strength cord made of low-elongation yarn. As a result, when a tensile load greater than a predetermined value is applied to the strap, the cushioning cord is first stretched (additional stretching), and when the cushioning cord is completely stretched, the high-strength cord suppresses excessive stretching.

In this way, when the worker falls and the load is applied to the lanyard, the impact energy is continuously absorbed by the extension of the cushioning string using the half-stretched yarn, and time is wasted during impact absorption. The fall is stopped by a high-strength string using a low elongation thread without causing a fall. Therefore, according to the lanyard of the present invention, it is possible not only to sufficiently absorb the impact of the falling worker, but also to stop the worker from falling early to shorten the falling distance, so that the lanyard at the time of falling can be reduced. The burden on workers can be reduced.

Moreover, in the present invention, it is preferable that the strap includes an elastic string made of a material having elastic contractility.

Further, as a specific embodiment of the lanyard of the present invention, when the cushioning cord body of the strap is set so that the maximum tensile load is at least 7.0 kN, it is at least 1/2 of the gauge length from the start of elongation. For example, the average tensile load is set to 2.8±0.3 kN until the increased elongation.

BRIEF DESCRIPTION OF THE DRAWINGS The top view which shows the external appearance of the lanyard by embodiment of this invention. Explanatory sectional view of the strap in this embodiment. 4 is a graph showing the relationship between tensile load and extension dimension of the lanyard of the present embodiment. FIG. 4A is a graph showing the action of the cushioning string in this embodiment, and FIG. 4B is a graph showing the action of a conventional string using shredded yarn for comparison.

One embodiment of the present invention will be described based on the drawings. As shown in FIG. 1, the lanyard 1 of this embodiment includes a first hook 2, a strap 3, and a second hook 4. As shown in FIG.

The first hook 2 is provided at one end of the strap 3 for hooking onto a D-ring of a harness-type safety belt (not shown). The other end of the strap 3 is provided with a second hook 4 corresponding to the hook in the present invention. The second hook 4 is hooked to a fixing structure (not shown) (for example, a frame of a building or scaffolding). The first hook 2 corresponds to the connector in the present invention, and the second hook 4 corresponds to the hook in the present invention.

The strap 3 has annular portions 5 and 6 at both ends in the longitudinal direction. A first hook 2 is attached to one annular portion 5 and a second hook 4 is attached to the other annular portion 6 . The configuration of the strap 3 will be described in detail below.

As shown in FIG. 2, the strap 3 includes two elastic cords 7, a cushioning cord 8 provided between the elastic cords 7, and a high-strength strap covering the elastic cords 7 and the cushioning cords 8 over the entire length. A string body 9 is provided. Furthermore, as shown in FIG. 1, first covering members 10 and 11 covering the annular portions 5 and 6, respectively, and a second covering member 10 further covering the first covering member 10 at the base end portion of one of the annular portions 5 are provided. 12.
As shown in FIG. 2, the elastic string 7 is formed in a belt shape using an elastic material such as natural rubber, synthetic rubber, silicone rubber, or the like.

The cushioning string 8 is formed in a belt shape using semi-drawn yarn of synthetic fibers such as polyester. When a tensile load is applied, the half-stretched yarn used for the cushioning cord 8 stretches with resistance until it reaches its limit. As a result, the cushioning string 8 functions as a shock absorbing member to the lanyard 1, and there is no need to provide a structure such as a shock absorber.

The high-strength string 9 is woven in a tubular shape from non-stretchable high-strength synthetic fibers (for example, aramid), and is bent at a plurality of points to allow the elastic string 7 and the cushioning string 8 to stretch to a predetermined size. The elastic cords 7 and the cushioning cords 8 are covered in the folded state. The high-strength string 9 is longer than the elastic string 7 and the cushioning string 8, and is kept within the full length of the strap 3 by bending it at a plurality of points.

The first covering members 10 and 11 are formed of high-strength synthetic fibers (such as aramid) that do not stretch similarly to the high-strength cord 9, and the annular portions 5 and 6 formed by the elastic cord 7 and the cushioning cord 8 are strongly protected.

The second covering member 12 is made of a high-strength synthetic fiber (for example, aramid) and is formed in a tubular shape that is thinner than the high-strength cord body 9 and protects the base end portion of one annular portion 5 .

As described above, the lanyard 1 of the present embodiment is provided with the cushioning string 8 made of the half-stretched yarn, so that when a tensile load is applied to the strap 3 due to the operator dropping, the cushioning string 8 provides Due to the elongation with a certain amount of resistance, the impact is absorbed and mitigated.

According to this, compared to the intermittent shock absorption by cutting the string several times using shredded thread like the conventional strap, the shock is absorbed and mitigated in a short time, and the worker's fall is stopped. Since the distance to be covered can be shortened, safety is further improved.

In addition, since the tensile load of the strap 3 can be easily adjusted by the cushioning cord 8 made of the half-stretched yarn, it is possible to obtain a shock absorption performance equal to or higher than that of the conventional cord using shredded yarn, and the operator's comfort is reduced. Setting for shortening the drop stopping distance can be easily performed.

As for the performance of the buffer cord body 8, as shown in FIG. 0.3 kN), elongation starts (elongation start point a), and from 43.2 mm to 129.5 mm (interval b), the average tensile load is 2.8 kN (2.8 ± 0.3 kN) .

In this product, the gauge length is 150 mm, and the average tensile load is 2.8 kN (2.8 ± 0.3 kN ). In addition, in the lanyard 1 of this embodiment, the strap 3 as a whole is set to have a strength of about 25 kN.

As described above, the drop stopping distance of the worker can be shortened, and the impact can be sufficiently absorbed and mitigated. This performance can be obtained by forming the cushioning string 8 using a half-stretched yarn.

Here, test results comparing the effect of the cushioning cord 8 according to the present embodiment using half-stretched yarn and the effect of the conventional cord using shredded yarn will be shown. According to the test results, as shown in FIG. 4A, the cushioning cord 8 according to the present embodiment has an effective impact load absorption time range c of about 0.27 seconds, while the conventional shredded yarn is used. As shown in FIG. 4B, the elastic cord has an effective impact load absorption time range d of about 0.34 seconds. is clear.

As described above, according to the lanyard 1 of the present embodiment, even if the operator falls, the shock absorption and relaxation is short-time because the cushioning string 8 is formed using the half-stretched yarn. Since the fall distance until the fall is stopped is short, it is possible to further improve the safety of high-place work.

DESCRIPTION OF SYMBOLS 1... Lanyard, 2... 1st hook (connector), 3... Strap, 4... 2nd hook (hook), 7... Elastic string, 8... Shock-absorbing string, 9... High-strength string.

Claims (3)

A lanyard comprising a strap, a connector provided at one end of the strap and connected to a safety belt, and a hook provided at the other end of the strap and hooked to a fixing structure,
The strap comprises a cushioning cord having a predetermined length, and a bellows-shaped high-strength cord having a length larger than that of the cushioning cord and being bent at many points,
The buffer string is formed using a half-stretched yarn that starts to stretch at a predetermined tensile load,
The high-strength string is formed using a low-elongation thread having a higher tensile strength than the cushioning string,
A lanyard characterized in that, when the high-strength string has a bellows shape, a gap is provided between the cushioning string and the high-strength string. A lanyard according to claim 1,
A lanyard, wherein the strap comprises an elastic string made of a resiliently contractible material. The lanyard according to claim 1 or 2,
When the buffer cord of the strap is set to have a maximum tensile load of at least 7.0 kN, the average tensile load is 2 from the start of elongation until the elongation increases by at least 1/2 of the gauge length. A lanyard characterized in that it is set to .8±0.3 kN.

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