WO2016102812A1

WO2016102812A1 - Tear strap

Info

Publication number: WO2016102812A1
Application number: PCT/FR2015/053506
Authority: WO
Inventors: Jean-Marc Hede; Alain Maurice
Original assignee: Zedel
Priority date: 2014-12-22
Filing date: 2015-12-15
Publication date: 2016-06-30
Also published as: FR3030286A1

Abstract

The invention relates to a tear strap (1) which includes a first strap (2) including first warp strands (21) and at least one first weft strand (22), and a second strap (3) including second warp strands (31) and at least one second weft strand (32). At least one breakable strand (4) mechanically connects the first strap (2) to the second strap (3) by weaving, at least one of the breakable strands (4) being configured to dissipate the energy by breaking in the event of a dynamic use of the tear strap (1). The first and second warp strands (21, 31) and the first and second weft strands (22, 32) have a Young's modulus of more than 40 GPa. Finally, at least one of the breakable strands (4) has a loop strength lower than that of the first and second weft strands (22, 32).

Description

Tear strap

Technical field of the invention

The invention relates to a so-called "tear strap" intended to be integrated in an energy absorber, itself intended to be integrated in a safety fastening device for the movement of a user along a handrail.

State of the art

In the field of climbing and work at height, energy absorbers are regularly used to ensure the safety and comfort of the user in case of a fall. Energy absorbers are for example used in the field of via ferrata on lanyards to slow the user down and stop it as quickly as possible without generating too much effort. They are also used in the context of professional activities, for example in association with a self-locking device to enable the user to work remotely from the safety rope to which he is attached.

The energy absorbers generally comprise a so-called "tear strap" with resistance wires having a sufficient tensile strength to resist in case of impact, and so-called "fuse" son intended to absorb the energy by successive breaks during of a fall.

One of the disadvantages of this type of energy absorber is the bulk, which can sometimes be inconvenient for the user. The research weight gain and compactness is therefore an effort appreciated by sportsmen and professionals.

For safety reasons, it is also advantageous for the fall distance to be as short as possible, without the user suffering any significant discomfort, in particular because of a high intensity force. These criteria are notably translated by standards governing sporting activities and professional activities, the standards governing professional activities being more drastic than those governing sports activities.

The materials used to make tear straps are generally chosen from the family of polyesters, including the Young's modulus of between 10 and 20 GPa, or in the family of polyamides whose Young's modulus is between 1 and 6 GPa. .

In prior art embodiments, the tear straps are formed for example by high tenacity polyester or high tenacity polyamide webbing. The straps are connected by fuse threads of polyamides or polyester. It appears that these tear straps are still quite large with comfort perfectible.

Object of the invention

An object of the invention is to provide a tear strap comprising:

A first strap comprising first warp threads and at least one first weft thread,

A second strap comprising second warp threads and at least one second weft thread, At least one fuse wire connecting the first strap to the second strap, at least one of the fusible wires being configured to dissipate the energy by rupture in case of dynamic use of the tear strap.

Advantageously, the fuse wire mechanically connects by weaving the first strap and the second strap. The first and second warp yarns, and the first and second weft yarns advantageously have a Young's modulus greater than 40 GPa. In addition, at least one of the fusible wires has a lower loop resistance than the first and second weft wires.

Different embodiments of the tear strap can be envisaged. For example, we can predict that:

The first warp threads and the second warp threads are formed of the same material,

At least one of the first weft yarns and at least one of the second weft yarns are formed in the same material,

The first warp threads and at least one of the first weft threads are formed in the same material,

The second warp threads and at least one of the second weft threads are formed in the same material.

The first and second warp threads may furthermore have an elongation at break of less than 5%. The same applies to at least one of the first weft yarns, and at least one of the second weft yarns. The elongation at break of the fuse wires can be between 10 and 45%. According to one embodiment, the first and second warp son and the first and second weft son can be made of a material to base of aramid, ceramic, carbon or ultra-high molecular weight polyethylene. The material may in particular be polyethylene of ultra-high molecular weight, that is to say having at least 100,000 monomers per molecule, and having a molar mass approximately equal to 3.10 ⁶ g / mol.

According to a particular embodiment, the first strap may be provided with a first external face and a first internal face, the first outer face and the first inner face being mechanically connected by at least one first connecting wire. The second strap may also be provided with a second outer face and a second inner face, the second outer face and the second inner face being mechanically connected by at least one second connecting wire.

The invention also relates to a safety fastening device for moving a user along a handrail comprising a tear strap having the aforementioned characteristics.

Brief description of the drawings

Other advantages and features will emerge more clearly from the following description of particular embodiments of the invention given by way of non-limiting example and represented in the accompanying drawings, in which:

FIG. 1 is a comparative graph of the force exerted on the user as a function of the stopping distance for a device according to the prior art and a device according to the invention,

FIGS. 2 and 3 show two possible embodiments of a tear strap,

- Figures 4 and 5 illustrate schematically an embodiment of a safety fastening device. Detailed Description In the field of mountaineering and acrobatic work, besides the elastic materials used to form the tear straps, there are very rigid materials that are used for a very different purpose.

For a dynamic use, current practice formally discourages the use of cords or straps made of these very rigid materials because in case of shock the energy stored by the device can not be dissipated properly. In the event of a fall, all the energy is retransmitted, the forces exerted on the user have a high intensity for a fall distance which is low. This can lead to a rupture of the webbing, a rupture of the shoulder belt and / or an injury of the user whose organs will partly absorb the energy transmitted.

Yet, counter-intuitively, the inventors have noticed that the use of very rigid materials for making tear straps has many advantages.

The energy absorber comprises at least one tear strap made of resistance wires and fuse wires. The tear strap has first and second straps 2 and 3 which are mechanically connected by means of at least one fuse wire 4.

One of the straps is connected to the user while the other strap is connected to a fixed point or a lifeline. During a fall, a traction force appears between the two straps and when the force exceeds a threshold value, the fuse wires deform to their breaking point. Once the rupture threshold is reached, they break and tension the following fusible wires. As the fall, the two straps separate by deforming and breaking the son fuse. By breaking, the fusible wires dissipate the energy accumulated by the absorber and slow down the fall of the user. On the other hand, the first and second straps retain their mechanical integrity so as to ensure the safety of the user when all the fuse wires have yielded.

The first and second straps 2 and 3 are formed by first and second sets of resistance wires. The straps are formed by warp threads and weft threads, both types of thread playing the role of resistance threads.

As in the embodiment illustrated in FIG. 2, the first strap 2 can be formed by first warp threads 21 and by at least one first weft thread 22. The second strap 3 can be formed by second warp threads 31 and at least one second weft thread 32. One or more fusible threads 4 advantageously connect the first weft threads 22 of the first strap 2 to the second weft threads 32 of the second strap 3. They are therefore placed parallel to the threads chain 21 and 31, that is to say along the longitudinal axis of the tear strap 1. They can be at least two in number to increase the resistance of the tear strap in dynamic use. The first and second straps 2 and 3 are woven simultaneously by two framers placed one above the other, so as to be able to weave the fusible son or son 4 directly during the manufacture of the straps 2 and 3 so as to connect mechanically. We distinguish here a device where the fuse wire is sewn on the two straps to connect mechanically. The formation of a tear strap formed by weaving allows better control of efforts as the fall.

The fusible son (s) 4 do not necessarily alternate from one strap to another after each weft thread. As in the embodiment illustrated in Figure 2, the fuse wire 4 can be held outside one of the straps so as to limit the forces exerted on the user if it falls. The portion of fusible wire that does not connect the two straps does not intervene in the absorption of fall energy. By changing the weaving pattern of the fuse wire, that is to say the arrangement of the son between the two straps, it is possible for the same number of son to change the effort to the user.

According to an alternative embodiment of the tear strap 1 shown in Figure 3, the first and second straps 2 and 3 may each have a double thickness. The first and second straps are doubled.

The first strap 2 may comprise a first outer face 2a provided with first warp threads 21a and first weft threads 22a, and a first inner face 2b provided with first warp threads 21b and first weft threads 22b. The first outer face 2a and the first inner face 2b are connected by weaving with the aid of at least one first woven wire 23 to connect the first weft threads 22a of the outer face 2a and the first weft threads 22b of the inner face 2b.

Similarly, the second strap 3 has a second outer face 3a with second warp threads 31a and second weft threads 32a, and a second inner face 3b with second warp threads 31b and second weft threads. 32b. The second outer face 3a and the second inner face 3b are connected by weaving with the aid of at least one second woven wire 33 for connecting the second weft son 32a of the outer face 3a and the second weft son 32b of the inner face 3b. The first and second inner faces 2b and 3b of the first and second straps are arranged vis-a-vis and are advantageously in contact with each other.

In a particular embodiment (not shown), additional connecting threads may be sewn to allow the use of the tear strap 1 under more stringent conditions.

The fusible son or son 4 advantageously connect the second weft son 22a and 22b of the first strap 2 to the weft son 32a and 32b of the second strap 3. The fusible son or son 4 can connect weft son 22b and 32b internal faces 2b and 3b, or connect weft son 22a and 32a of the outer faces 2a and 3a, or connect weft son internal faces weft son external faces. According to a particular embodiment, the fuse son or 4 can connect only the weft son 22b and 32b internal faces 2b and 3b them. In this way, the fuse wire 4 is invisible and is protected from external aggressions during the use of the tear strap 1. This may also have a role in safety since seeing the fuse wire may mean that the tear strap 1 has been used dynamically. The thickness of the tear strap 1 is also thinner, which can be useful to meet the space requirements of the device. The fusible son or wires 4 can also connect only the weft wires 22a and 32a of the external faces 2a and 3a so that the forces undergone by the two straps 2 and 3 are more symmetrical. In this way the tear strap 1 can advantageously withstand tensile forces with more intensity than in the case where the fuse son or 4 connect only the inner faces 2b and 3b. This embodiment can be advantageous when the strap must meet particularly stringent safety standards, or when the user is corpulent.

The weaving of the fusible wire (s) 4 may also consist of a combination of the two embodiments which have just been described. The fusible son or son 4 can be alternately connected to the weft son of the outer faces or the inner faces of the straps 2 and 3. They can also be maintained at one of the two straps, or on the side of the face internal, or on the side of the outer face, so as to temporarily block the tear of the tear strap 1 and therefore the forces exerted on the user in case of a fall.

According to another alternative embodiment, the tear strap 1 may comprise a single thickness strap 2 and a double thickness strap 3 connected by at least one fuse wire 4. In this case, the fuse wire 4 may connect the weft son of the 2 to the weft son of the inner face or the outer face of the strap 3. The fuse wire 4 can also be maintained at one of the two straps so that the force exerted on the user is temporarily constant when of his fall. The warp, weft, binding and fusible threads may be made of different materials, each type of thread playing a specific role in the case of dynamic use of the tear strap 1.

The connecting wires 23 and 33 are configured to have better resistance to stress than the fuse wires so that in use, the energy is absorbed by the fusible wires and not by the connecting wires which yield.

The first and second straps 2 and 3 occurring jointly during the fall, it is advantageous to provide that the two straps have the same mechanical characteristics, and preferably the same Young's modulus. In a particular embodiment, the first warp threads 21 are identical to the second warp threads 31 both in their production material and in the diameter and the number of threads used. However, it is also possible to provide that the first and second warp son 21 and 31 are different in their mechanical performance.

To have the same mechanical behavior between the two straps 2 and 3, it is also advantageous to have a first weft material identical to the second weft material. Having two identical straps ensures a good distribution of efforts during the fall.

In an advantageous embodiment, the first weft material is identical to the first warp material. It is also possible to provide that the second warp material is identical to the second weft material. The first strap 2 can be made with the same type of wire, that is to say son made of the same material and having the same diameter. It may be the same for the second strap 3. While the straps of the prior art use elastic materials to dissipate the energy of the fall, the tear strap according to the invention uses chain son and son very rigid weft, that is to say having a Young's modulus of greater than or equal to 40 GPa, whereas the warp and weft threads used in the prior art have a Young's modulus generally understood between 10 and 20 GPa. Advantageously, the warp yarns and the weft yarns are made of a material having an elongation at break of less than 10%, and preferably less than 5%, to further reduce the oscillation phenomena during the breakage of the yarns. Fuses 4. The elongation at break of the fuse wire 4 may be less than 45% and even more advantageously between 10 and 45%. In this way, the energy dissipated by the fuse wire during dynamic use of the tear strap 1 is important. By way of example, the materials of the warp and weft yarns are chosen from poly (p-phenyleneterephthalamide) (PPD-T) marketed for example under the names Keviar® or Twaron®, ultra-high molecular weight polyethylene, which is marketed in particular under the names Dyneema® or Spectra®. By ultra high molecular weight is meant that the polyethylene used has at least 100,000 monomers per molecule, and preferably has a molar mass of about 3 × 10 ⁶ g / mol. These materials have a Young's modulus generally greater than 130 GPa. It is also possible to use warp and weft yarns of para-aramid copolymers marketed for example under the name Technora®, or aromatic polyesters such as the one sold under the name Vectran®.

The fuse wires are advantageously made of a material based on polyester, polyamide, or polypropylene, having the property of being less solid than the material of the weft son. By less solid, it is meant that the loop resistance of each fuse wire is less than that of a weft yarn. This means that when two loops are formed with a weft and a fuse wire, and a pulling force is exerted on the loops, the fuse wire breaks first. According to an advantageous embodiment, it is possible to vary the value of the force causing the rupture of the fuse wire depending on the position on the tear strap. This variation of the force can be obtained in different ways, for example by changing the number of fusible son that connect the first strap to the second strap on a given cross section. The more the number of fusible wires is important and the greater the effort to break them will be important. Another way to change the effort is to change the diameter of the threads and / or change the material of the threads along the strap.

Using fuse wires made of the same material and having a constant diameter, and varying the number of these fuse wires in the tear strap 1 is a particularly advantageous embodiment because it can be directly implemented by weaving. However, the use of fuse son of different diameters and / or fuse son made of different materials requires sewing the fuse son. These embodiments of the tear strap 1 can be combined, and thus the connection of the first and second straps 2 and 3 can be achieved by both woven fusible threads and sewn fusible threads.

Preferably, the number of fusible wires that must yield to absorb energy increases from the beginning of the fall until reaching a threshold value. In this way, the effort felt by the user during the fall is progressive.

Then the number of son that connects the two straps can be constant so as to have a constant effort.

It is also possible to predict changes in the effort in stages. Each bearing is associated with a number of wires connecting the two straps and / or a wire diameter and / or a wire nature. The number of resistance threads of each strap can also be chosen according to the aspect that is to be preferred: compactness or shorter stopping distance.

For example, at number of son equal resistance between a tear strap according to the prior art and a tear strap according to the invention, the stopping distance will be shorter with the tear strap according to the invention. In contrast, at a stopping distance equal between a tear strap according to the prior art and a tear strap according to the invention, the tear strap according to the invention will be more compact.

The use of warp and weft threads made of very rigid material also makes it possible to produce a more compact tear strap as fewer warp threads will be needed.

Unexpectedly, the rigidity of the material of the warp and fuse threads does not affect the effectiveness of the absorber in case of impact and especially on the comfort of the user during the fall.

It has been observed that the use of a very rigid material for making the warp and weft threads of the tear strap makes it possible, on the contrary, to limit the resonance effect felt by the user during a fall. . Indeed, the elasticity of the son according to the prior art provides the discomfort of the user who experiences a sinusoidal braking force during its fall when the energy absorber is stressed. This force is illustrated on the curve A of FIG.

The tear strap proposed brakes the user more regularly in its fall, without this being done at the expense of safety. Curves B and C in Figure 1 illustrate two particular cases where: The stopping distance is identical for the strap according to the invention and for a strap of the prior art, but the maximum force exerted by the strap on the user is lower than that of the prior art (curve B )

The maximum force exerted on the user is identical for a strap according to the invention and for a strap of the prior art, but the user is stopped on a smaller distance with the strap according to the invention (curve C) . Whatever the embodiment of the tear strap, the curves illustrating the variations of the force exerted by the strap on the user according to the stopping distance are all between the curves B and C. The pace curves can be substantially identical to those of curves B and C if the number of resistance wires of the tear strap is evenly distributed along the strap.

The tear strap 1 can be integrated into a security fastener 5 used to allow a user to move along a handrail safely. Such a device 5 may for example take one of the forms illustrated in Figures 4 or 5.

According to these embodiments, the ends of the straps 2 and 3 are sewn to one another and partially folded back on themselves so as to leave two passages 6 and 6 'for the introduction of a carabiner or a fast link. To ensure safety, these seams 7 and 7 'must not break.

If the user equipped with a safety fastening device 5 falls, the straps 2 and 3 are suddenly placed in tension, and the fuse wire 4 breaks up gradually during the fall of the user, since the parts A to middle B of the tear strap 1. The user is braked whenever a portion of fusible wire 4 breaks. The low elasticity of the warp threads helps to avoid jolts and to ensure a more regular braking.

The straps 2 and 3 remain secured at least at the seams 7 and 7 ', and the fuse son or 4 can be partially or completely broken according to the weight of the user. For a better distribution of the forces exerted on the straps 2 and 3, at least one of the two seams 7 or 7 'can be made in the manner illustrated in FIG.

Thus, the tear strap 1 and the safety fastening device 5 offer greater comfort to the user in case of dynamic use, and greater security since these two devices can be configured to stop more quickly the fall of the user.

Claims

claims

A tear strap (1) comprising:

A first strap (2) comprising first warp threads (21) and at least one first weft thread (22),

A second strap (3) comprising second warp threads (31) and at least one second weft thread (32),

At least one fuse wire (4) connecting the first strap (2) to the second strap (3), at least one of the fusible wires (4) being configured to dissipate the energy by breaking in case of dynamic use the tear strap (1),

characterized in that

• the fuse wire (4) mechanically connects by weaving the first strap (2) and the second strap (3),

The first and second warp yarns (21, 31), and the first and second weft yarns (22, 32) have a Young's modulus greater than 40 GPa,

Each fuse wire (4) has a lower loop resistance than the first and second weft wires (22, 32).

The tear strap (1) according to claim 1, wherein the first warp threads (21) and the second warp threads (31) are formed of the same material.

3. A tear strap (1) according to any one of claims 1 or 2, wherein at least one of the first weft son (22) and at least one of the second weft son (32) are formed in the same material.

The tear strap (1) according to any of claims 1 to 3, wherein the first warp yarns (21) and at least one of the first weft yarns (22) are formed from the same material.

The tear strap (1) according to any one of claims 1 to 4, wherein the second warp yarns (31) and at least one of the second weft yarns (32) are formed of the same material.

The tear strap (1) according to any one of claims 1 to 5, wherein the first and second warp threads (21, 31) have an elongation at break of less than 5%.

The tear strap (1) according to any one of claims 1 to 6, wherein at least one of the first weft yarns (22) and at least one of the second weft yarns (32) have a elongation at break less than 5%.

The tear strap (1) according to any one of claims 1 to 7, wherein the first and second warp threads (21, 31) and first and second weft threads (22, 32) are made in one material based on aramid, ceramic, carbon or ultra high molecular weight polyethylene.

9. A tear strap (1) according to claim 8, wherein the first and second warp threads (21, 31) and the first and second weft threads (22, 32) are made of polyethylene having at least 100,000 monomers per molecule, and preferably having a molar mass approximately equal to 3.10 ⁶ g / mol.

10. A tear strap (1) according to any one of claims 1 to 9, wherein at least one of the fusible son (4) is made of polyester, polyamide, or polypropylene.

11. A tear strap (1) according to any one of claims 1 to 10, wherein at least one of the fusible wires (4) has an elongation at break of between 10 and 45%.

The tear strap (1) according to claim 1, wherein:

The first strap (2) has a first outer face (2a) and a first inner face (2b), the first outer face (2a) and the first inner face (2b) being mechanically connected by at least a first connecting wire (23),

The second strap (3) is provided with a second outer face (3a) and a second inner face (3b), the second outer face (3a) and the second inner face (3b) being mechanically connected by at least a second connecting wire (33).

13. Safety fastening device (5) for moving a user along a handrail comprising a tear strap (1) according to any one of claims 1 to 12.