JP4866892B2 - Shock absorbing net and protective body using the same - Google Patents

Description

  The present invention relates to an impact absorbing net and a protective body using the same.

A rockfall prevention net that protects rockfalls and landslides on slopes by suspending wires on slopes such as cliffs and banks and stretching wire meshes (for example, see Patent Document 1), or connecting multiple ring wires There is known a net-like net unit that is fixed to the ground with a wire rope and an anchor (for example, see Patent Document 2).
Moreover, generally the shock-absorbing device for relieving a huge impact at the time of falling rock collides is provided in the protection body which consists of these wire nets, a wire, an anchor, etc.
For these reasons, the conventional protective body is effective against falling rocks and rocks with a large scale without breaking even if a relatively large impact is applied.

  However, since these protective bodies are heavy, heavy equipment is required for transportation and construction, construction costs increase, and construction areas are limited. For this reason, a protective body that can be easily constructed has been desired in places where it is not necessary to assume a large falling rock.

On the other hand, a protective body whose net is made of a synthetic resin has been proposed (see, for example, Patent Document 3). In such a protector, a plurality of lightweight synthetic fiber filaments such as polyethylene are twisted to form a knotless net, and fixed to a support fixed to the ground with a connector.
Since such a protective body uses a net made of synthetic fiber, the weight can be greatly reduced as compared with the case where the above-described wire net is used. For this reason, since heavy equipment is unnecessary in construction transportation, construction can be simplified, and the net can be wound or folded in a roll shape during transportation, which has the advantage of facilitating work.
JP-A-61-109806 Japanese Patent Laid-Open No. 10-280332 JP 2003-261910 A

However, in the protective body described in Patent Document 3, since the net is made of synthetic fiber, there is a problem in that the shock absorption is greatly reduced. For this reason, such a protective body is unsuitable for use as a permanent body.
On the other hand, according to research by the inventors, although it depends on the terrain to be constructed, it is necessary to have a shock absorbing property of at least 100 kJ as a protective body to be used permanently, and impact of 100 kJ with general-purpose fibers such as polyethylene fibers. In order to achieve absorbency, it is necessary to use hundreds of thousands of denier fibers.
Therefore, even when the net is made of synthetic fiber, it is necessary to make the basis weight considerably large in order to exhibit sufficient shock absorption, and as a result, it is too heavy to handle manually. End up.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an impact-absorbing net that is lightweight and excellent in mechanical strength and shock-absorbing, and a protective body using the same. .

The inventors of the present invention have intensively studied to solve the above-mentioned problems, and the net using general-purpose fibers such as polyethylene, polyester, nylon, etc. is locally deformed due to the impact of falling objects, resulting in low collisions. It has been found that even if it has energy, it has a characteristic that it is easily broken.
Therefore, the present inventors have considered a method of absorbing the impact when the fallen object is dropped by deformation (extension) of the net.
As a result of searching for the elastic modulus of the shock absorbing net in order to absorb the shock, the present inventors have unexpectedly found that the above problems can be solved and have completed the present invention.

  That is, the present invention is (1) an impact absorption net made of a synthetic fiber cord capable of absorbing an impact when a falling object is dropped by stretching, and an elastic modulus before the synthetic fiber cord stretches is 5 cN / dtex or more and 50 cN. It is less than / dtex, the elastic modulus at the maximum elongation of the synthetic fiber cord is 50 cN / dtex or more and 200 cN / dtex or less, and the elastic modulus increases as the synthetic fiber cord stretches.

  The present invention provides the shock absorbing net according to (1), wherein (2) the synthetic fiber cord comprises a first synthetic fiber yarn having an initial modulus of 400 cN / dtex or more and a second synthetic fiber yarn having an initial modulus of 250 cN / dtex or less. Exist.

  In the present invention, (3) the twist coefficient of the first twist of the first synthetic fiber yarn is 10,000 to 25000, the twist coefficient of the second twist of the second synthetic fiber yarn is 10,000 to 30000, and the synthetic fiber cord is the first synthetic fiber The impact absorbing net according to (2) above, wherein the yarn and the second synthetic fiber yarn are twisted.

  This invention exists in the impact-absorbing net | network of the said (3) description whose twist coefficient of (4) top twist is 20000-40000.

  The present invention resides in (5) the impact-absorbing net according to any one of (2) to (4), wherein the first synthetic fiber yarn is a para-aramid fiber.

  The present invention resides in (6) the impact-absorbing net according to any one of (2) to (5), wherein the second synthetic fiber yarn is a polyethylene terephthalate fiber.

  In the present invention, (7) the second synthetic fiber yarn has a strength of 3.0 to 6.0 cN / dtex, an elongation of 30 to 150%, and a 10% elongation stress of 0.1 to 4.0 cN / dtex. (2) It exists in the impact absorption net | network as described in any one of (6).

  The present invention includes (8) the shock absorbing net according to any one of (1) to (7), a peripheral rope provided at a peripheral edge of the shock absorbing net, and a support rope that supports the peripheral rope. And a support body that is disposed on both sides of the shock absorbing net and has a support rope attached thereto, and a support that supports the support pole.

In the impact absorbing net of the present invention, the elastic modulus before elongation of the synthetic fiber cord and the elastic modulus at the maximum elongation are within the above range, and the elastic modulus increases as the synthetic fiber cord elongates. Thereby, the stress to the impact at the time of fall of a fallen object is disperse | distributed effectively.
Thereby, the impact at the time of falling of a falling object can be absorbed reliably.
For example, even when a large impact is received on a part of the impact absorbing net, it is difficult to cause destruction due to local deformation, and the impact can be effectively mitigated.

Moreover, since the said shock absorption net | network consists of a synthetic fiber cord, it is lightweight. For this reason, construction becomes easy, and heavy machinery and specialized equipment are unnecessary. In addition, it can be easily constructed even in places where the scaffolds such as cliffs and slopes are bad.
Therefore, the impact absorbing net (hereinafter, also simply referred to as “net”) is lightweight and excellent in mechanical strength and shock absorbing properties.

If the synthetic fiber cord is composed of the first synthetic fiber yarn and the second synthetic fiber yarn having different initial moduli, the elastic modulus increases as the synthetic fiber cord stretches, so that the impact absorbing net is subjected to an impact. In this case, there is an advantage that the entire net can receive an impact and can easily absorb the impact.
Here, the initial modulus means the value of stress when a certain strain is applied to the synthetic fiber cord before stretching. The initial modulus can be measured according to JIS L-1013.

  When the twist coefficient of the first twist of the first synthetic fiber yarn and the second synthetic fiber yarn is within the above range, the impact absorbing net is easy to perform the upper twist and the net knitting process, and the durability of the net is improved. If the synthetic fiber cord is one in which the first synthetic fiber yarn and the second synthetic fiber yarn are twisted, the net knitting process is easy and the durability of the net is enhanced. There is an advantage. In addition, it is preferable that the twist coefficient of this top twist is in the said range.

When the first synthetic fiber yarn is a para-aramid fiber, the strength of the material itself is excellent, so that the weight can be further reduced while maintaining the strength.
Moreover, since the weather resistance and versatility are excellent when the second synthetic fiber yarn is a polyethylene terephthalate fiber, it can be used at low cost for a long time.
Moreover, it has moderate strength and is excellent in elasticity.

  The impact absorbing net has the advantage that when the strength, elongation, and 10% elongation stress of the second synthetic fiber yarn are within the above ranges, the net can be provided with appropriate strength and elongation, and the impact absorption can be improved. is there.

  Since the protective body of the present invention includes the above-described shock absorbing net, it is lightweight and has excellent mechanical strength and shock absorbing properties.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as necessary.
In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.
Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified.
Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

FIG. 1 is a front view showing an embodiment of an impact absorbing net according to the present invention.
As shown in FIG. 1, the shock absorbing net 10 according to the present embodiment has a net structure in which the gaps are rhombic.

The shock absorbing net 10 is made of a lightweight synthetic fiber cord 1.
Therefore, the shock absorbing net 10 is easy to construct and does not require heavy machinery or specialized equipment. In addition, the shock absorbing net 10 can be constructed even in places where the scaffolding such as cliffs and slopes is bad.

The shock absorbing net 10 may be a knotted network in which the synthetic fiber cord 1 is tied or tied, and a plurality of synthetic fiber cords 1 are twisted to form a strand, and these are twisted in a lattice shape. It may be a knot network.
When the shock absorbing net 10 is a knot network, a large shearing force may be applied to the knot portion due to excessive stress, and the knot may be broken at the knot point. Therefore, the shock absorbing net 10 may be a knotless network. preferable.

The impact absorbing net 10 preferably has a strength of the synthetic fiber cord 1 of 5 to 20 cN / dtex.
When the strength of the synthetic fiber cord 1 is less than 5 cN / dtex, the strength of the net tends to be too low in practical use compared to the case where the strength is in the above range, and when the strength exceeds 20 cN / dtex. Compared with the case where the strength is in the above range, the elongation tends to be too low and the impact absorbing performance tends to be low. In addition, this intensity | strength is the value measured based on JISL2707 (polyester rope).

The impact absorbing net 10 absorbs the impact by elastic deformation and permanent deformation, and receives the impact while taking a certain time. Therefore, the elongation of the synthetic fiber cord 1 is preferably 3 to 100%, and more preferably 5 to 50%.
When the elongation of the synthetic fiber cord 1 is less than 3%, the impact absorption performance is lowered as compared with the case where the elongation is within the above range, and an excessive burden is placed on the support column that supports the impact absorption net. When the elongation exceeds 100%, the net stretches too much before the impact is completely received, and falling people hit objects and objects compared to the case where the elongation is within the above range. there is a possibility. The elongation is a value measured according to JIS L 2707 (polyester rope).

FIG. 2 is a graph showing a stress-strain curve of the synthetic fiber cord constituting the shock absorbing net according to the present embodiment.
As shown in FIG. 2, the synthetic fiber cord 1 has a downward load convex curve in the stress-strain curve.
In the synthetic fiber cord 1 in the impact absorbing net 10 according to the present embodiment, as described later, the first synthetic fiber yarn and the second synthetic fiber yarn having different primary yield points are used to form the above curve. .
By setting it as such a curve, there exists an advantage that an elastic modulus increases according to the expansion | extension of a synthetic fiber cord, impact stress, such as falling rock, is disperse | distributed effectively, and an impact can be absorbed.

The synthetic fiber cord 1 has an elastic modulus before elongation of 5 cN / dtex or more and less than 50 cN / dtex, and an elastic modulus at the maximum elongation of 50 cN / dtex or more and 200 cN / dtex or less.
Here, the elastic modulus before extension (hereinafter referred to as “initial elastic modulus”) means the elastic modulus in a state where the synthetic fiber cord 1 is not extended, and the elastic modulus at the maximum extension (hereinafter referred to as “final elastic modulus”). The term “elastic modulus”) means the elastic modulus immediately before the synthetic fiber cord 1 is stretched and broken.
The initial elastic modulus is a value obtained by extrapolating the stress when the elongation is 2% to 100% elongation, and the final elastic modulus is a value obtained by extrapolating the stress increment at 2% immediately before the break to 100% elongation. It is.

  In the impact absorbing net 10, if the initial elastic modulus of the synthetic fiber cord 1 is less than 5 cN / dtex, the impact absorbing net 10 is stretched too much to secure a sufficient distance from an adjacent road or building. If the initial elastic modulus of the synthetic fiber cord 1 is 50 cN / dtex or more, the effect of absorbing the impact when the fallen object falls is not exerted, and the post supporting the shock absorbing net 10 is excessive. Will be burdensome.

  On the other hand, if the final elastic modulus of the synthetic fiber cord 1 is less than 50 cN / dtex, sufficient strength cannot be obtained, and if it exceeds 200 cN / dtex, the difference from the initial elastic modulus increases, The change becomes steep and the load on the column becomes large.

The synthetic fiber cord 1 preferably has a diameter of 10 to 40 mm.
In this case, the balance between strength and handleability is excellent. More preferably, the diameter is 15 to 30 mm.

The synthetic fiber cord 1 includes a first synthetic fiber yarn having a high initial modulus and a second synthetic fiber yarn having an initial modulus at least lower than that of the first synthetic fiber yarn. That is, the synthetic fiber cord 1 is a hybrid cord of two types of synthetic fibers having different initial moduli. The details of the first synthetic fiber yarn and the second synthetic fiber yarn will be described later.
Here, the initial modulus means a stress value when a certain strain is applied to the synthetic fiber cord 1 before stretching. The initial modulus can be measured according to JIS L-1013.

In the impact absorbing net 10, the synthetic fiber cord 1 is composed of the first synthetic fiber yarn and the second synthetic fiber yarn, so that the elastic modulus of the synthetic fiber cord 1 increases as the synthetic fiber cord 1 extends. It is like that.
The theory of this phenomenon is not clear, but as the synthetic fiber cord 1 extends, the second synthetic fiber yarn having a small initial modulus first exhibits its own elastic modulus, and then the initial modulus becomes the second synthetic fiber yarn. Since the larger first synthetic fiber yarn exhibits its own elastic modulus, it is considered that the apparent elastic modulus of the synthetic fiber cord 1 may increase.

The shock absorbing net 10 has an elastic modulus before the synthetic fiber cord 1 stretches and an elastic modulus at the maximum stretch within the above range, and the elastic modulus increases as the synthetic fiber cord 1 stretches. Thus, it is possible to reliably absorb the impact when the fallen object falls.
For example, even when a large impact is received on a part of the impact absorbing net 10, it is difficult to cause destruction due to local deformation, and the impact can be effectively mitigated.

FIG. 3 is a schematic view showing a synthetic fiber cord constituting the shock absorbing net according to the present embodiment.
As shown in FIG. 3, the synthetic fiber cord 1 includes a first synthetic fiber yarn 2 that is a single twisted yarn cord subjected to a lower twist, and a second synthetic fiber yarn 3 that is a single twisted yarn cord subjected to a lower twist. It is preferable that the upper twist is applied.
As a result, a function of increasing the elastic modulus as the synthetic fiber cord 1 extends is developed.

  Here, the upper twist means that two or more yarns subjected to the lower twist (when making the various twisted yarns) are combined and twisted in the opposite direction to the lower twist direction. This means the twist that is applied to a single yarn first (when making a twisted yarn).

The above-described upper twist preferably has a twist number of 200 to 600 T / m.
If the number of twists of the upper twist is less than 200 T / m, the elongation of the synthetic fiber cord 1 tends to be too low compared with the case where the number of twists is within the above range, and the impact absorption performance tends to be low. When the number of twists exceeds 600 T / m, the elongation of the synthetic fiber cord 1 tends to be too high and the strength tends to be lower than when the number of twists is within the above range.

Moreover, it is preferable that a twist coefficient is 20000-40000.
Here, in this specification, the twist coefficient is calculated by the following formula.
Twisting coefficient = twisting number (T / m) × √ (fineness dtex)

  When the twist coefficient of the upper twist is less than 20000, the first synthetic fiber yarn 2 and the second synthetic fiber yarn 3 are independently broken as compared with the case where the twist coefficient is in the above range, As a hybrid cord, stress-strain characteristics where the elastic modulus continuously increases may not be obtained. When the twist coefficient exceeds 40000, the synthetic fiber cord is compared with the case where the twist coefficient is within the above range. The elongation of 1 tends to be too high and the strength tends to be low.

  Examples of the material constituting the first synthetic fiber yarn 2 include carbon fiber, para-aramid fiber, ultrahigh molecular weight polyethylene fiber, poly-p-phenylenebenzobisoxazole fiber, polyoxyketone fiber, and glass fiber. These may be used alone or in combination of two or more.

Among these, it is preferable that the raw material which comprises the 1st synthetic fiber yarn 2 is a para-aramid fiber (para-aromatic amide fiber).
More specifically, there is Technora (registered trademark) fiber manufactured by Teijin Techno Products Limited.
In this case, since the strength of the material itself is excellent, the weight can be further reduced while maintaining the strength.
The first synthetic fiber yarn 2 may contain a pigment such as carbon or an ultraviolet absorber for the purpose of imparting light resistance, and is coated with a resin for the purpose of protecting the surface of the shock absorbing net 10. Etc. may be processed.

The fineness of the first synthetic fiber yarn 2 is preferably 500 to 5000 dtex, and more preferably 1100 to 3300 dtex.
When the fineness of the fibers constituting the first synthetic fiber yarn 2 is less than 500 dtex, the fineness may be lower than that in the above range and may break, and when the fineness exceeds 5000 dtex, Compared with the case where the fineness is within the above range, the weight becomes too large, so that the workability tends to be lowered.

The number of filaments constituting the first synthetic fiber yarn 2 is preferably 100 to 2000 fil.
When the number of filaments constituting the first synthetic fiber yarn 2 is less than 100, the fineness per filament is higher than in the case where the number of filaments is within the above range. The difficulty level may increase and the cost may increase, and if the number of filaments exceeds 2000, the number of filaments is too large compared to the case where the number of filaments is within the above range, so that the fibers are not aligned. It may be sufficient and the strength may be reduced.

The first synthetic fiber yarn 2 preferably has an initial modulus of 400 cN / dtex or more.
When the initial modulus of the first synthetic fiber yarn 2 is less than 400 cN / dtex, compared to the case where the initial modulus is within the above range, the synthetic fiber cord 1 having a stress-strain curve convex to the lower right is obtained. There is no tendency.
The initial modulus of the first synthetic fiber yarn 2 is preferably 2000 cN / dtex or less from the viewpoint of durability and twist processing.

At this time, the number of twists of the lower twist is preferably 200 to 600 T / m.
When the number of twists of the lower twist is less than 200 T / m, compared to the case where the number of twists is within the above range, the elongation is low and the independent breakage tends to occur, and the function as a hybrid cord tends not to be exhibited. Yes, when the number of twists exceeds 600 T / m, the strength tends to be lower than when the number of twists is within the above range.

Further, the twist coefficient of the lower twist is preferably in the range of 10,000 to 25,000.
When the twist coefficient of the lower twist is less than 10,000, the final elastic modulus tends to be too high as compared with the case where the twist coefficient is in the above range, and when the twist coefficient exceeds 25,000, the twist coefficient is within the above range. Compared with the case where it exists in inside, since the intensity | strength of the synthetic fiber cord 1 falls, it exists in the tendency for it to become a weak net | network.

  As a material constituting the second synthetic fiber yarn 3, 6 nylon fiber, 6,6 nylon fiber, polyethylene terephthalate fiber, polyethylene-2,6-naphthalate fiber, polypropylene fiber, low pressure polyethylene fiber, acrylic fiber, rayon fiber, etc. Is mentioned. These may be used alone or in combination of two or more.

Among these, the second synthetic fiber yarn 3 is preferably a polyethylene terephthalate fiber. More specifically, a polyethylene terephthalate fiber manufactured by Teijin Techno Products Limited can be mentioned.
In this case, since weather resistance and versatility are excellent, it can be used for a long time at low cost. Moreover, it has moderate strength and is excellent in elasticity. The second synthetic fiber yarn 3 may be provided with a pigment such as carbon or an ultraviolet absorber for the purpose of imparting light resistance, and is coated with a resin for the purpose of protecting the surface of the shock absorbing net 10. Etc. may be processed.

In addition, when the 2nd synthetic fiber yarn 3 is a polyethylene terephthalate fiber, when synthesize | combining the 2nd synthetic fiber yarn 3, in addition to the raw material of a polyethylene terephthalate fiber, isophthalic acid, neopentyl glycol, bisphenol A ethylene oxide adduct, etc. The third component may be included. In other words, the polyester raw material and the third component may be copolymerized.
In this case, physical properties based on the third component can be added.

Here, as described above, it is particularly preferable that the fibers constituting the first synthetic fiber yarn 2 are para-aramid fibers and the fibers constituting the second synthetic fiber yarn 3 are polyethylene terephthalate fibers.
In this case, there are advantages such as excellent weather resistance, resistance to scratching, a high melting point that can withstand heat generated by friction, and availability at a relatively low cost.

The fineness of the second synthetic fiber yarn 3 is preferably 500 to 5000 dtex.
If the fineness of the second synthetic fiber yarn 3 is less than 500 dtex, the fineness may be lower than that when the fineness is within the above range and may break. If the fineness exceeds 5000 dtex, the fineness is within the above range. Compared with the case of being inside, since the weight becomes too large, workability tends to be lowered.

The number of filaments constituting the second synthetic fiber yarn 3 is preferably 50 to 2000 fil, more preferably 100 to 500 fil.
When the number of filaments constituting the second synthetic fiber yarn 3 is less than 50, the fineness per filament is higher than in the case where the number of filaments is within the above range. The difficulty level may increase and the cost may increase, and if the number of filaments exceeds 2000, the number of filaments is too large compared to the case where the number of filaments is within the above range, so that the fibers are not aligned. It tends to be sufficient and the strength decreases.

The second synthetic fiber yarn 3 is preferably a fiber having an initial modulus smaller than that of the first synthetic fiber yarn. Specifically, it is preferably 250 cN / dtex or less.
When the initial modulus of the second synthetic fiber yarn 3 exceeds 250 cN / dtex, the synthetic fiber cord 1 having a stress-strain curve convex to the lower right cannot be obtained as compared with the case where the initial modulus is within the above range. There is a tendency. The initial modulus of the second synthetic fiber yarn 3 is preferably 100 cN / dtex or less from the viewpoint of handleability.

At this time, the number of twists of the lower twist is preferably 200 to 600 T / m.
When the number of twists of the lower twist is less than 200 T / m, the initial modulus of the synthetic fiber cord 1 tends to be too high as compared with the case where the number of twists is within the above range, and the number of twists is 600 T / m. If it exceeds, the elongation of the second synthetic fiber yarn 3 becomes too high as compared with the case where the number of twists is within the above range, so that the first synthetic fiber yarn 2 and the second synthetic fiber yarn 3 in the hybrid cord It tends to break independently and tends not to function as a hybrid cord.

The twist coefficient is preferably in the range of 10,000 to 30,000.
If the twist coefficient of the lower twist is less than 10,000, the initial modulus tends to be too high and a sufficient impact absorbing effect tends not to be exhibited as compared with the case where the twist coefficient is within the above range, and the twist coefficient is 30000. If it exceeds, the elongation of the second synthetic fiber yarn 3 becomes too high as compared with the case where the twist coefficient is in the above range, so that the first synthetic fiber yarn 2 and the second synthetic fiber yarn 3 in the hybrid cord It tends to break independently and tends not to function as a hybrid cord.

The second synthetic fiber yarn 3 preferably has a strength of 3.0 to 6.0 cN / dtex.
When the strength is less than 3.0 cN / dtex, the strength of the impact absorbing net 10 is low compared to the case where the strength is within the above range, and the strength tends not to withstand a high impact force. When it exceeds 0 cN / dtex, compared to the case where the strength is in the above range, it becomes difficult to obtain a highly stretched fiber, so that the difficulty in fiber production tends to increase and the cost tends to increase.

The second synthetic fiber yarn 3 preferably has an elongation of 30 to 150%.
When the elongation of the second synthetic fiber yarn 3 is less than 30%, compared to the case where the elongation is within the above range, there is a tendency that a sufficient impact absorbing effect is not obtained, and the elongation is 150%. If it exceeds, the elongation tends to be lower than when the elongation is in the above range.

The second synthetic fiber yarn 3 preferably has a 10% elongation stress of 0.1 to 4.0 cN / dtex, and more preferably 1.5 to 2.5 cN / dtex.
When the 10% elongation stress of the second synthetic fiber yarn 3 exceeds 4.0 cN / dtex, the impact absorption effect tends to be smaller than when the 10% elongation stress is within the above range.
In addition, it is substantially difficult to make 10% elongation stress less than 0.1 cN / dtex.
Here, 10% elongation stress means the stress when the second synthetic fiber yarn 3 is elongated by 10% in the longitudinal direction.

  The above-described shock absorbing net 10 is provided with pigments, ultraviolet absorbers, resins, flame retardants, heat, and the like for the purpose of improving weather resistance, wear resistance, thermal stability, smoothness, imparting functionality, and form stability. Components such as a stabilizer, an oil agent, a smoothing agent, and an antibacterial agent may be added. In addition, this grant may be given in a manufacturing process, and may be given after manufacture.

In particular, when the impact absorbing net 10 is used outdoors, it is effective to blend a pigment or an ultraviolet absorber or coat a resin.
Moreover, when the synthetic fiber cord 1 is processed into the impact absorbing net 10 and an oil agent is applied, fluff and thread breakage due to friction can be suppressed, which is effective. There is no restriction | limiting in particular in such various additives, What is necessary is just to use what is considered effective suitably.

  The shock absorbing net 10 is preferably used as a net for a protector that receives a fallen object.

Next, a method for manufacturing the shock absorbing net 10 according to the present embodiment will be described.
First, the first synthetic fiber yarn 2 is produced.
For example, a para-aramid fiber having a predetermined fineness and the number of filaments is subjected to a lower twist by a Z twist using a ring twisting machine. Thereby, the 1st synthetic fiber yarn 2 which is a single twist yarn cord is obtained.

Next, the second synthetic fiber yarn 3 is produced.
For example, a polyethylene terephthalate fiber having a predetermined fineness and number of filaments is subjected to a lower twist by a Z twist using a ring twisting machine.
Thereby, the 2nd synthetic fiber yarn 3 which is a single twist yarn cord is obtained. In addition, it is also possible to adjust the physical property of the synthetic fiber cord 1 obtained by changing the number of twists between the first synthetic fiber yarn 2 and the second synthetic fiber yarn 3.

Then, the first synthetic fiber yarn 2 and the second synthetic fiber yarn 3 are subjected to an upper twist using an S twist in the direction opposite to the lower twist using a ring twisting machine.
Thereby, the synthetic fiber cord 1 is obtained.
In addition, when applying an upper twist, it is preferable that the direction of the first twist of the first synthetic fiber yarn 2 and the direction of the second twist of the second synthetic fiber yarn 3 are the same direction.
Moreover, it is preferable that the number of the 1st synthetic fiber yarn 2 and the 2nd synthetic fiber yarn 3 is one each. Furthermore, it is preferable for stable production that the first synthetic fiber yarn 2 and the second synthetic fiber yarn 3 have the same number of twists within 10%. The lower twist may be S twist and the upper twist may be Z twist.

Here, the initial modulus, strength, and elongation of the first synthetic fiber yarn or the second synthetic fiber yarn described above are the intrinsic viscosity, the degree of drawing, and the treatment of the fibers constituting the first synthetic fiber yarn or the second synthetic fiber yarn. It can be adjusted according to conditions.
For example, in order to increase the intrinsic viscosity of the fibers constituting the first synthetic fiber yarn or the second synthetic fiber yarn, the polymerized chip may be further subjected to solid phase polymerization using a tumble dryer or the like.
This chip is usually kneaded and melted with an extruder, extruded from a spinneret, and spun. The discharged polymer passes through a delayed cooling zone directly under the die, and then cooled by blowing cooling air. It is also possible to apply and take out a spinning oil.
Then, the drawn undrawn yarn is continuously supplied to the drawing process without being wound or wound up once, drawn, and then heated and set using a heated roller to obtain a drawn yarn.

  Then, the synthetic fiber cord 1 is knitted by a Raschel machine of a warp knitting machine to obtain the impact absorbing net 10 according to the present embodiment. Depending on the performance of the shock absorbing net, the synthetic fiber cord may be used for both the chain knitting yarn and the insertion yarn, or may be used alone for the chain knitting yarn and the insertion yarn.

Next, the protection body 20 using the shock absorbing net 10 will be described.
FIG. 4 is a front view showing an example of an embodiment of a protective body according to the present invention.
As shown in FIG. 4, the protection body 20 according to the present embodiment includes the above-described shock absorbing net 10, a peripheral rope 12 provided at the periphery of the shock absorbing net 10, and a support rope that supports the peripheral rope 12. 13, a support column 15 that is disposed on both sides of the shock absorbing net 10 and to which the support rope 13 is attached, and a support 17 that supports the support column 15.

  The protective body 20 has a structure in which the shock absorbing net 10 receives falling objects such as stones, earth and sand, and snow. That is, when there is a fallen object, the protective body 20 is stretched by the peripheral rope 12 and the support rope 13 so that the shock absorbing net 10 is bent and the impact force when the fallen object falls is absorbed.

Thus, since the protective body 20 is provided with the above-described impact absorption net 10, it is excellent in mechanical strength and shock absorption while being lightweight.
Therefore, since an impact such as falling rocks can be absorbed, damage to the members of the protective body 20 is suppressed.

In the protective body 20, the peripheral rope 12 is attached to the shock absorbing net 10 by alternately inserting the meshes at the peripheral edge of the shock absorbing net 10. That is, by mounting in this way, the shock absorbing net 10 is secured with a degree of freedom of movement with respect to the peripheral rope 12.
Further, since the attachment of the peripheral rope 12 to the shock absorbing net 10 is extremely simple, the protective body 20 can be easily assembled.

For these reasons, the protective body 20 is easy to construct and requires no heavy machinery or dedicated equipment. Moreover, construction is possible even in places where the scaffolding such as cliffs and slopes is bad.
Furthermore, since the above-described shock absorbing net 10 is light and excellent in workability, it is easy to replace a rope damaged by falling rocks, etc., and whether it is damaged or not easily depends on how much permanent deformation has occurred. Since it can be confirmed, appropriate maintenance and early member replacement are possible. Therefore, the performance of the protective body 20 can be maintained at a high level.

A known rope is used as the peripheral rope 12 and the support rope 13. These physical properties are not particularly limited.
The peripheral rope 12 and the support rope 13 may have the same physical properties, and the peripheral rope 12 may also serve as the support rope 13.

The strut 15 is appropriately designed in strength, structure, etc. according to the scale of rock fall expected at the place where it is constructed.
For example, concrete struts, and structures composed of concrete and steel pipes embedded in basic concrete or underground can be used. In addition, when standing rock fall is expected to be relatively small, natural standing trees may be used as struts.

As the support 17, a conventional one is used as appropriate.
Since the protective body 20 is lightweight, it is not always necessary to make the support 17 robust, but it is preferable to make it robust like a wire rope from the viewpoint of improving safety.

The protector 20 may include a shock absorber (not shown).
As such a shock absorber, a fiber rope is preferably used.
Examples of the rope fiber include synthetic fibers such as polyamide fiber, polyester fiber, vinyl chloride fiber, and polypropylene fiber, and natural fibers such as hemp.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

For example, in the impact absorbing net 10 according to the present embodiment, two types of materials, the first synthetic fiber yarn 2 and the second synthetic fiber yarn 3, are used, but a single material may be used.
In addition, even if it is a raw material which consists of a raw material with the same primary yield point, the stress-strain curve shown in FIG. 2 can be obtained by changing the draw ratio and changing the balance between elongation and strength.

The protective body 20 may further include an auxiliary rope that is supported by the support column 15 and attached linearly to the back surface of the shock absorbing net 10.
In this case, local expansion of the shock absorbing net 10 due to the falling object is suppressed.
Such auxiliary ropes may be alternately passed through the mesh of the shock absorbing net 10, or may be arranged in parallel with the protective net 11 so as to contact the back surface of the shock absorbing net 10 without passing through the mesh.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

Example 1
As a fiber constituting the first synthetic fiber yarn (hereinafter referred to as “fiber A”), “Technola (registered trademark)” (fineness: 1670 dtex, filament number: 1000 fil) manufactured by Teijin Techno Products Co., Ltd. was used.
As the fiber constituting the second synthetic fiber yarn (hereinafter referred to as “fiber B”), a drawn yarn made of a polyester fiber produced by the following method was used.
First, a polyester chip having an intrinsic viscosity of 0.6 was subjected to solid-phase polymerization in a tumble dryer having a temperature of 235 ° C. to obtain a polyester chip having an intrinsic viscosity of 1.0. This chip was kneaded and melted with an extruder, extruded from a spinneret having 250 pores having a diameter of 0.6 mm, and spun. The discharged polymer passed through a 300 mm delayed cooling zone directly below the die, cooled by blowing cooling air adjusted to 25 ° C., and applied with a spinning oil, and then taken up at a speed of 700 m / min. The drawn undrawn yarn is continuously supplied to the drawing process without being wound once, drawn at a draw ratio of 3.5 times, and then heat-set using a roller heated to 220 ° C. to take up the drawn yarn ( A fineness of 2110 dtex and a filament number of 250 fil) were obtained.
The physical properties of fiber A and fiber B are shown in Table 1. In Table 1, strength, elongation at break, and initial modulus are values measured according to JIS L-1013 using Shimadzu Autograph S-100.

Next, the fiber A was used and twisted at a twist number of 400 T / m to obtain a single twisted yarn cord A (first synthetic fiber yarn).
Moreover, the fiber B was used and the single twisted-yarn cord B was obtained by twisting at a twist number of 400 T / m (second synthetic fiber yarn).
Then, the single twisted yarn cord A and the single twisted yarn cord B were twisted at a twist number of 400 T / m to obtain a cord A (synthetic fiber cord) of twin-twisting (two twists). Table 2 shows the physical properties of the obtained code A.

  Next, 32 synthetic fibers cords and 36 fibers B twisted at a twisting number of 80 T / m were used to form a raschel net, and a net A (impact absorbing net) having a mesh size of 100 mm was obtained. It was.

(Comparative Example 1)
A cord B was obtained in the same manner as in Example 1 except that only the fiber B was used without using the fiber A. The cord B is obtained by twisting the fiber B at a twist number of 400 T / m and further twisting the two together at 400 T / m.
Table 2 shows the physical properties of the obtained code B.

  Next, the cord B was used to make a Russell net using 32 on the front and 36 on the back, and a net B having a mesh size of 100 mm was obtained.

(Comparative Example 2)
A cord C was obtained in the same manner as in Example 1 except that only the fiber A was used without using the fiber B. The cord C is obtained by twisting Technora with a twist number of 400 T / m and further twisting two together with a twist of 400 T / m.
Table 2 shows the physical properties of the obtained code C.

  Next, the cord C was used to make a Russell net by using 32 on the front and 36 on the back to obtain a net C having a mesh size of 100 mm.

(Evaluation 1) Impact absorption test Net A, net B and net C obtained in the above-described examples and comparative examples were each fixed to a load cell of a tensile tester, and the other end was fixed to a 1.0 kg weight. . The weight was dropped from a height of 50 cm (energy amount 5.0 J), and the impact force due to the weight was recorded with a recorder. The initial stress peak value at this time was defined as the maximum impact force. Further, the detected maximum impact force was 4.5N or more (impact absorption rate 10% or less), and x was less than 4.5N (impact absorption rate 10% or more).
The obtained results are shown in Table 3.

(Evaluation 2) Weight drop test Weights of 3 tons were lifted with a crane above the net A, net B, and net C obtained in the above-described examples and comparative examples, and each net was stretched horizontally. Were allowed to fall freely from a height of 1 m. After dropping the weight, it was marked as x when the net was broken, and marked as o when it was not broken.
The obtained results are shown in Table 3.

As described above, according to the net A of Example 1 which has a predetermined initial elastic modulus and a final elastic modulus, and the elastic modulus increases as the cord stretches, it has excellent mechanical strength and shock absorption. Was also confirmed to be excellent.
On the other hand, it was found that the net B of Comparative Example 1 having a low final elastic modulus was inferior in mechanical strength, and the net C of Comparative Example 2 having a high initial elastic modulus and high final elastic modulus was inferior in impact absorption.

FIG. 1 is a front view showing an embodiment of an impact absorbing net according to the present invention. FIG. 2 is a graph showing a stress-strain curve of the synthetic fiber cord constituting the shock absorbing net according to the present embodiment. FIG. 3 is a schematic view showing a synthetic fiber cord constituting the shock absorbing net according to the present embodiment. FIG. 4 is a front view showing an example of an embodiment of a protective body according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Synthetic fiber cord 2 ... 1st synthetic fiber yarn 3 ... 2nd synthetic fiber yarn 10 ... Shock absorption net 12 ... Perimeter rope 13 ... Support rope 15 ... Post 17 ... Supporting equipment 20 ... Protective body

Claims (8)

It is an impact absorption net consisting of a synthetic fiber cord that can absorb the impact of falling objects by stretching,
The elastic modulus before elongation of the synthetic fiber cord is 5 cN / dtex or more and less than 50 cN / dtex, the elastic modulus at the maximum elongation of the synthetic fiber cord is 50 cN / dtex or more and 200 cN / dtex or less, and the synthetic fiber cord is Shock absorbing net whose elastic modulus increases as it stretches.   2. The impact absorbing net according to claim 1, wherein the synthetic fiber cord includes a first synthetic fiber yarn having an initial modulus of 400 cN / dtex or more and a second synthetic fiber yarn having an initial modulus of 250 cN / dtex or less. The twist coefficient of the first twist of the first synthetic fiber yarn is 10,000 to 25000, the twist coefficient of the twist of the second synthetic fiber yarn is 10,000 to 30000,
The impact-absorbing net according to claim 2, wherein the synthetic fiber cord is formed by twisting the first synthetic fiber yarn and the second synthetic fiber yarn.   The impact absorbing net according to claim 3, wherein a twist coefficient of the upper twist is 20000 to 40000.   The impact absorption net according to any one of claims 2 to 4, wherein the first synthetic fiber yarn is a para-aramid fiber.   The impact-absorbing net according to any one of claims 2 to 5, wherein the second synthetic fiber yarn is a polyethylene terephthalate fiber.   The strength of the second synthetic fiber yarn is 3.0 to 6.0 cN / dtex, the elongation is 30 to 150%, and the 10% elongation stress is 0.1 to 4.0 cN / dtex. The shock absorbing net according to claim 1. The shock absorption net according to any one of claims 1 to 7,
A peripheral rope provided at the periphery of the shock absorbing net;
A support rope for supporting the peripheral rope;
Struts arranged on both sides of the shock absorbing net and attached with the support ropes;
A support for supporting the support;
Protective body equipped with.

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