EP0668382A1 - Shedding process to reinforce the tear resistance of a woven fabric with twill or satin weave and their derivatives - Google Patents

Abstract

To strengthen a woven fabric against rips and tears, the fabric surface is divided into a pattern of adjacent squares defined by opposing warps and wefts for the sides of the squares. At least one additional warp and weft yarn is added to those defining the sides of the squares laid with them and in the same way.

Description

The present invention relates to a method of forming a weave to reinforce the tear resistance of a twill or satin base weave fabric and their derivatives.

Several solutions have been proposed to improve the tear resistance of a fabric.

Thus it has been proposed to modify the web weave by introducing a discontinuity in the homogeneity of the weave in the form of two threads every x thread in warp and weft, these two threads working according to the same evolution. The formation of float lines of 2 is thus obtained, making it possible to offer all the x wires a resistance twice that of the wires of the fabric.

The propagation of the tear is stopped by each stronger resistance line it encounters in the form of floats of two introduced into the basic canvas weave.

The weaving limit of this solution is relatively close to that of the fabric, which is the lowest of all the weaves, given that it corresponds to the maximum possible nesting of the threads. This solution is therefore technically not applicable on all items. Especially heavily textured articles.

The relief of the grid formed by the floats of 2 is significant compared to that of the relatively flat canvas. For many applications, such as those of work or protective clothing for example, this relief poses a problem of early abrasion at the floats of 2, which greatly reduces the longevity of the product. In addition, this relief, when it is important, becomes troublesome in the event of coating of the fabric, or laminating with a membrane or a film.

In certain areas such as work or protective clothing, the grammage and the texture of the articles give very little flexible and not very comfortable fabrics when we want to make them with this weave. A coating or membrane laminated to a fabric of this type then gives an extremely stiff and uncomfortable complex.

Instead of seeking to obtain an increased resistance to tearing by the grouping of two threads, it has also been proposed to substitute all the x threads in warp and in weft a thread if possible of the same title and of the same color, so as not to change the appearance of the fabric, in a more resistant material.

This solution, which gives a heterogeneous tissue, involves several drawbacks. Yarn made of more resistant material is often more expensive, thus increasing the price of the article. In practical terms, the weaver will have to manage two different stocks of yarn, making supply more complex, especially for the production of small quantities.

The two types of wire do not have the same mechanical and / or physicochemical characteristics.

If the elongation at break of the two strands is too far apart, they work separately in breaking strength, which generally results in a drop in performance relative to the fabric without incorporating the more resistant strands.

In addition, the two wires often have a different shrinkage at temperature or at washing, which results in blistering of the article in use.

It has also been proposed to improve the resistance to tearing by the type of complex armor known as reformed armor, which has been specially studied to reveal a large number of floats, combined together so as to be able to slide , which provides a very significant packing effect.

This solution has the drawbacks of requiring strong textures, therefore the use of fine threads, to avoid slippage problems at the seams and to give a fabric which has hold. It is therefore a solution which increases both the cost of the wire and that of production.

The presence of long floats generates abrasion and scuffing problems which are not necessarily compatible with certain uses such as work and protective clothing for example.

The weaving of such armor requires a large number of blades on the looms. The most effective armor in this family requires Jacquard mechanics.

As can be seen, none of the solutions proposed so far provides a satisfactory answer to the problem to be solved.

The object of the present invention is to remedy at least in part the above-mentioned drawbacks.

To this end, the subject of the present invention is a method of forming an armor to reinforce the tear resistance of a twill or satin base weave fabric and their derivatives, characterized in that the surface of the fabric in adjacent quadrangular basic patterns, each bounded by two adjacent warp threads respectively at two opposite sides of the pattern and two weft threads, respectively adjacent to two other opposite sides of the pattern, which are added at least one thread to each warp and weft threads delimiting said patterns, and the thread thus added is changed in the same way as the weft or warp thread to which it has been added.

The advantages of the process which is the subject of the invention are that they allow the production of a fabric the flexibility of which is not appreciably modified compared to the basic reinforcement, the tear resistance of which is better than that of the basic armor. , whose other characteristics do not undergo significant degradation compared to those of the fabric in basic weave and whose manufacturing cost is close to that of the fabric in basic weave.

The appended drawing illustrates, schematically and by way of example, various forms and variants of implementation of the method which is the subject of the present invention.

Figures 1 to 4 are schematic representations of armor illustrating a first form of implementation of this method.

Figures 5 to 8 are schematic representations of armor according to variants of the first embodiment.

Figures 9 to 13 are schematic representations of armor illustrating a second form of implementation of the method.

Figures 14 and 15 are schematic representations of armor of two variants of the embodiment of Figures 9 to 13.

FIG. 16 is a schematic representation of armor according to another form of implementation.

Figures 17 and 18 are schematic representations of armor made for comparison.

Figures 19 to 21 are even more schematic representations of the only groups of wires moving together in the armor.

To obtain the aforementioned characteristics, the basic float weaves are transformed, namely the twills and their chevron derivatives, etc. which originally offer good flexibility, good abrasion and tear resistance.

However in the case of strong textures one can also take as a base the satins.

To reinforce the tear resistance of these basic weaves, without using a material mixture, the proposed solution consists in introducing a discontinuity in the weave giving a stop to the propagation of the tear.

This discontinuity which is made up of a group of at least two wires must allow the wires which constitute it to work together under duress. For this, it is necessary to weave them in the same evolution so that they are naturally grouped and solicited together simultaneously in the same way.

The weave according to the present invention therefore results from the transformation carried out on basic twill, satin or their derivatives weaves, to incorporate therein groups of threads evolving together in warp and weft surrounding adjacent basic patterns which retain the weave base chosen. This results in a grid effect of the fabric where the grid is formed by these groups of wires evolving together.

avec
   x : entier
   R : rapport de l'armure de base
   a : entier compris entre O et R-1The number of warp and weft threads of each basic pattern corresponds to the formula: $$\text{Nb of wires = x · R + a}$$

with
x: integer
R: basic armor ratio
a: integer between O and R-1

We will now describe with the aid of FIGS. 1 to 4 the process for forming a reinforced weave according to the invention from a basic weave twill 2/1 with groups of two threads moving together around patterns of irregular sizes.

To obtain the weave illustrated in FIG. 4, starting from the twill 2/1 illustrated in FIG. 1, a certain number of conditions must be observed to guarantee the wearability of a fabric free from defects. It is important in particular that the embuvage of the various warp threads of the armor is identical. Indeed, if the evolution of one of the yarns of the armor gives a much stronger embuvage than that of the others, this yarn is subjected to a higher tension which generates an appearance defect which can ultimately lead to the breaking of This thread.

Otherwise, if the embuvage of a thread is weaker than that of the other threads, the tension of this thread becomes progressively weaker, leading to a weaving defect ultimately leading to the stopping of the loom by the chain wire break detectors.

In both cases, the armor is non-woven.

It should be noted, however, that when the differences in embuvage are small, the weave can be woven depending on the title of the threads, the material and the texture. Only a weaving test can tell.

• A. L'armure doit comporter au rapport, un nombre de motifs de base en chaîne et en trame, multiple du rapport de l'armure de base choisie. Dans le présent exemple, avec le sergé 2/1 comme armure de base, le rapport est 3. Le nombre minimum de motifs de chaîne, NbMch est donc de 3 et celui de motifs de trame, NbMtr est aussi de trois ce qui donne pour l'armure selon l'invention un nombre minimum de 3 x 3 = 9 motifs de base.
  Chaque motif de base de l'armure est repéré par la notation M_LC où L est le numéro de ligne du motif et C est le numéro de colonne du motif. L et C étant chacun un nombre entier compris entre 1 et le nombre de motif de la trame, respectivement de la chaîne.
  En reprenant la formule (1) précédente le nombre de fils trame du motif de base M_LC = X_LC · R + A_LC
  et le nombre de fils chaîne du motif de base M_LC = Y_LC · R + B_LC
     avec
     X_LC, Y_LC : entier positif
     A_LC, B_LC : entier positif compris entre 0 et R - 1
• B. Selon la deuxième condition, les motifs de base sur une même colonne C, respectivement une même ligne L, doivent comporter un même nombre de fils en chaîne, respectivement en trame. Ce qui donne donc $${\text{X}}_{\text{L1}}{\text{= X}}_{\text{L2}}{\text{= X}}_{\text{L3}}$$
  
  $${\text{A}}_{\text{L1}}{\text{= A}}_{\text{L2}}{\text{= A}}_{\text{L3}}$$
  
  $${\text{Y}}_{\text{1C}}{\text{= Y}}_{\text{2C}}{\text{= Y}}_{\text{3C}}$$
  
  $${\text{B}}_{\text{1C}}{\text{= B}}_{\text{2C}}{\text{= B}}_{\text{3C}}$$
  
• C. Pour garantir un embuvage identique de tous les fils de chaîne, tous les A_LC respectivement tous les B_LC doivent être égaux entre eux et compris entre 0 et R - 1.
• D. Les X_LC, Y_LC, A_LC et B_LC doivent respecter les formules suivantes :
        Pour L = 1 à NbMtr
  
        Pour C = 1 à NbMch
  
     z_L,w_C : entiers positifs.

To obtain the reinforced armor of figure 4 which constitutes the ideal case on the basis of basic patterns with irregular floats, the following conditions must be respected. We called basic pattern with irregular floats, the basic patterns which form a float of different length to that of the basic weave at the transition basic pattern, grouped threads of the same evolution:

• A. The weave must include on the report a number of basic warp and weft patterns, multiple of the report of the chosen basic weave. In the present example, with the twill 2/1 as basic weave, the ratio is 3. The minimum number of warp patterns, NbMch is therefore 3 and that of weft patterns, NbMtr is also three which gives for the armor according to the invention a minimum number of 3 x 3 = 9 basic patterns.
  Each basic pattern of the weave is identified by the notation M _LC where L is the line number of the pattern and C is the column number of the pattern. L and C each being an integer between 1 and the number of patterns in the frame, respectively in the warp.
  Using the above formula (1) the number of weft threads of the basic pattern M _LC = X _LC · R + A _LC
  and the number of chain threads of the basic pattern M _LC = Y _LC · R + B _LC
  with
  X _LC , Y _LC : positive integer
  A _LC , B _LC : positive integer between 0 and R - 1
• B. According to the second condition, the basic patterns on the same column C, respectively the same row L, must include the same number of threads in warp, respectively in weft. Which therefore gives $${\text{X}}_{\text{L1}}{\text{= X}}_{\text{L2}}{\text{= X}}_{\text{L3}}$$
  
  $${\text{AT}}_{\text{L1}}{\text{= A}}_{\text{L2}}{\text{= A}}_{\text{L3}}$$
  
  $${\text{Y}}_{\text{1 C}}{\text{= Y}}_{\text{2C}}{\text{= Y}}_{\text{3C}}$$
  
  $${\text{B}}_{\text{1 C}}{\text{= B}}_{\text{2C}}{\text{= B}}_{\text{3C}}$$
  
• C. To guarantee identical baking of all the warp threads, all the A _LC respectively all the B _LC must be equal to each other and between 0 and R - 1.
• D. X _LC , Y _LC , A _LC and B _LC must respect the formulas following:
  For L = 1 at NbMtr
  
  For C = 1 at NbMch
  
  z _L , w _C : positive integers.

We will now see how a reinforced armor according to the invention is constructed by observing the above-mentioned conditions.

To avoid making armor too large, the example includes a minimum number of patterns, either: $$\text{NbMch = NbMtr = 3}$$

We determine the size of the basic patterns that we want to achieve by respecting the conditions set out above. In this case it gives: Warp threads Weft threads Y11 = Y12 = Y13 = 1 X11 = X12 = X13 = 1 Y21 = Y22 = Y23 = 1 X21 = X22 = X23 = 1 Y31 = Y32 = Y33 = 1 X31 = X32 = X33 = 2 B _LC = O A _LC = 1

The number of warp and weft threads is then determined in relation to the starting armor according to formulas (6) and (7). In this example, there are 12 warp x 18 picks in the ratio as shown in Figure 1.

We then select in this basic weave the son that we will double by surrounding the basic patterns. We start by convention from the left edge at the top and we draw in gray frame all the takes of the first warp thread in Figure 2. We leave a space equal to the chain ratio of the basic patterns M11, M21 and M31 and we select a second warp thread, the catches of which are shown in gray. A new space is then left equal to the chain ratio of the basic patterns M12, M22, M23 and the next warp thread is selected. It then remains to the right edge of the armor the chain relationship of the patterns M13, M23, M33. By repetition effect of the weave the right edge of the weave becomes adjacent to its left edge, just as the lower edge of this same weave is adjacent to its upper edge, so that all the basic patterns M _LC are surrounded on their four sides by warp threads respectively weft that we want to double. The selection of the weft threads that we want to double is carried out in the same way, starting from the upper edge of the weave and drawing in gray weft, to make it easier to understand, all of the picks of the picks selected for be doubled.

FIG. 3 illustrates the operation which consists in doubling the selected wires of FIG. 2 by giving them the same evolution as the respective wires which they double. We therefore drew the catches of these wires in a gray frame to facilitate understanding and distinguish them from the basic patterns drawn in conventional black and white squares.

Finally, FIG. 4 illustrates, according to the conventional representation, the reinforced armor obtained according to the method which is the subject of the present invention.

The weave of Figure 4 therefore corresponds to basic patterns whose weft ratios are not equal but observing the conditions A, B, C and D above.

If these conditions are ideal, the invention is not however limited to compliance with all these conditions. We will now examine, by way of example, different possible variants which do not obey all of the conditions set out above.

In the following example we start again from a 2/1 twill and we respect condition A, that is to say that we have three basic warp and three weft patterns Warp threads Weft threads Y11 = Y12 = Y13 = 1 X11 = X12 = X13 = 1 Y21 = Y22 = Y23 = 1 X21 = X22 = X23 = 1 Y31 = Y32 = Y33 = 1 X31 = X32 = X33 = 1 B _LC = 0 A1C = 2 A2C = 1 A3C = O

As can be seen, the patterns do not respect the weft condition C. Figure 5 illustrates, as explained above, the 9 basic patterns surrounded by the selected and doubled warp and weft threads of which the taps have been illustrated in gray frame for facilitate understanding and allow to distinguish groups of two sons of the same evolution from basic patterns.

The table below makes it possible to check if the embuvage of all the threads is identical by checking for each thread, that its evolution comprises the same number of basic evolutions. We see that sons 2, 3, and 4 do not have the same evolution

These armours can however be woven. Indeed, the difference in embuvage always results from a particular re-combination at the transition between the basic patterns and the groups of threads evolving together.

When the basic patterns are small (X _LC = 1 for example), this particular re-combination has a significant weight taking into account the small number of thread evolutions in the ratio.

On the other hand, the larger the basic patterns, the more the bending tends towards the bogging of the basic weave which is predominant. The difference in shrinkage from the particular re-combination is therefore minimal.

Only a weaving test allows in this case to confirm the wearableness or not of the weave.

If the respect of rule C guarantees an identical shrinking of the threads, its non-compliance does not necessarily mean a difference in shrinking between the threads of the armor. In certain particular cases of backless armor, for example, we manage to keep an identical shrinkage despite non-compliance with these equations. This is for example the case of the weave with irregular patterns on a 2/2 twill base with 3 threads evolving together illustrated by FIG. 6.

Failure to comply with condition A (number of warp and weft patterns respectively multiple of the ratio of the basic weave) has the same consequences as that of non-compliance with condition C. Compliance with this condition A often leads to significant armor reports. By not respecting this condition, it is then possible to reduce the ratio of the weave, for example by putting only two basic patterns in a weft warp instead of three for a weave according to the invention with a 2/1 twill base.

Failure to comply with these conditions A and C simultaneously leads to the same consequences and exceptions. One such example is illustrated in Figure 7.

Failure to comply with fourth condition D necessarily results in non-compliance with condition C. Condition D guarantees that there will be no float formation longer than the length of the floats of the basic armor + the number of threads moving together - 1. In the case of a weave according to the invention with a twill base 2/1 with 2 threads moving together, there will therefore be no floats> 3.

Failure to comply with this condition D therefore leads to the formation of large floats which make the weability of the weave even more problematic by aggravating the problems of embuvage as shown in FIG. 8 with a float of 5 to wires 4 and 7 ( see table below). In addition, the formation of large floats in the middle of clearly smaller floats harms the appearance of the fabric, but above all poses the problem of the early abrasion of these large floats.

After the armor made up of basic patterns with irregular floats, we will examine those made up of basic patterns to regular floats.

Weaves composed of basic patterns with regular floats are called those whose basic patterns do not form floats with grouped threads of the same evolution.

When these armors are not built in compliance with the following four rules, they can lose their regular character. However, by their construction principle, we will still speak of basic patterned armor with regular floats.

Conditions A and B above remain valid here. For condition C the A _LC and B _LC must be different from 1 while being respectively equal to each other.

      Pour C = 1 à NbMch

   z_L,w_C : entiers positifsOn the other hand for condition D, the Y _LC , X _LC , B _LC and A _LC must respect the following formulas:
For L = 1 at NbMtr

For C = 1 at NbMch

z _L , w _C : positive integers

Compliance with these conditions guarantees the construction of a perfectly wearable weave.

We propose to build a reinforced tear resistance armor according to the present invention on the basis of a 2/1 twill with 2 threads evolving together surrounding the basic patterns. To explain the construction of this armor, refer to Figures 9 to 13.

The twill 2/1 leads, according to condition A, to that the weave has at least 3 basic warp and 3 weft patterns, making a total of 9 patterns.

Once the size of the basic patterns has been determined, the number of warp and weft threads is determined in relation to the reinforced weave according to the invention.

In our example, X _LC = Y _LC = 1 and A _LC = B _LC = 0.

The number of warp threads in the ratio corresponds to the sum: warp threads of basic patterns + (number of grouped threads moving together in chain x NbMch), or 15 threads in our example.

The number of weft threads to the ratio corresponds to the sum: weft threads of the basic patterns + (number of grouped threads evolving together in the weft x NbMtr), ie also 15 threads.

We then draw a 15 x 15 grid (Figure 9). We start by leaving free on the left side a number of columns equal to the number of grouped threads moving together in chain. Likewise, a number of lines equal to the number of grouped wires moving together in a weft are left free from the upper edge of the grid. We then draw in double lines a frame corresponding to the first basic pattern. The following pattern is positioned in a chain at the same level after a new interval of two columns in this example, corresponding to the number of grouped threads moving together in a chain. We do the same in the frame and we get the locations of the 9 basic patterns.

We fill the first basic pattern M11 (Figure 9) in the basic weave chosen, in our example in twill 2/1. The filling of the basic pattern according to M12, in a chain, is done in the basic weave, but starting with the last column of the adjacent basic pattern M11. This is repeated for the following chain patterns, up to the last chain pattern. The same is done in the frame, repeating for each pattern along the last line of the previous pattern. We extend this method to all the patterns and we get Figure 10.

Regarding the grouped wire paths evolving together, we establish in black boxes bridging between two white boxes basic patterns that face each other, without forgetting that in the fabric, the weave is repeated and we get Figure 11.

Finally, at the intersections between the grouped son paths evolving together, the color opposite to that of the boxes of the paths adjacent to each intersection is given as illustrated in FIG. 12. The corresponding armor is illustrated in FIG. 13.

The derogation from some of the conditions set out for the construction of the armor which has just been described makes it possible to significantly reduce the armor ratio, while obtaining, in certain cases, a weave armor in the same manner as explained in relation with basic patterned armor with irregular floats. Compliance with condition D is fundamental if we want to maintain the regularity of the armor, as defined above.

If one of the conditions A or C is not respected, there is no longer the guarantee that the rolling in of all the warp threads is identical. These drawbacks will affect the vast majority of cases.

FIG. 14 illustrates a case of non-compliance with conditions A and C on the basis of a satin of 4 with grouped thread paths evolving together of 3. The table below shows the problem of bogging which results therefrom

As previously mentioned, the larger the basic patterns, the more the embuvage of the threads will tend towards the embuvage of the basic weave, which is woven. This is why in in certain cases it is possible and even advantageous to derogate from these two conditions. Particularly on a 2/1 twill base, a perfectly weave weave with an extremely reduced ratio is obtained with a single pattern of the form xR + 1 (FIG. 18).

As we have already said, non-compliance with condition D makes the armor lose its regular character by the appearance of parasitic floats resulting from the re-combination of certain floats of the basic armor with floats of the paths of grouped threads evolving together, which give great floats, penalizing the fabric both in terms of its appearance and its resistance to abrasion. Although the same baking conditions are no longer met, the weave can be woven with large basic patterns.

Figure 15 illustrates this possibility. We see that the warp thread No 6 forms a float of 5 (see table below).

We can also imagine another family of reinforced armor, object of the invention, by only respecting condition A above, that is to say that the basic patterns on the same column, respectively the same line, must have the same number of threads in the warp, respectively in the weft.

We will speak of basic pattern weave with random floats, because the principle of construction of these weaves leads to the formation of floats of random lengths at the transition to basic patterns, grouped wires of the same evolution.

To make this weave, the number and size of the basic patterns are determined by respecting condition A. The different basic patterns are filled with the basic weave without following any rules, at random. Bridging is carried out in the same way between the basic patterns through the paths of grouped wires evolving together. Figure 16 illustrates this possibility on the basis of a 3/1 twill weave with two grouped threads evolving together.

One can also imagine, in this method, filling the basic patterns with different basic weaves. Of course with this variant of the process, it is not possible to know in advance whether the weave will actually be woven or not, whether the resulting fabric will be abrasion resistant and will have a satisfactory appearance.

As is known, the weaving limit and the flexibility of a fabric are closely linked. Both result from the degree of freedom of the threads, which depends, for a given choice of thread, on the weave and the texture.

To show the advantage of the weave produced using the process which is the subject of the invention, in terms of flexibility and wearability limit, we will rely on a theoretical approach for calculating the degree of overlapping of the threads in a tissue. This calculation is based on a modeling of the fabric.

The difficulty in weaving a given weave fabric can come from the warp texture, the weft texture, the combination of the two. It is therefore necessary to consider each of these factors in isolation.

$${\text{I}}_{\text{T}}\text{=}\frac{\text{duitage réel}}{\text{duitage maxi}}\text{x 100}$$

On the condition of clearly defining a maximum warp and weft count respectively corresponding to a given yarn title, the difficulty of weaving in warp I _C and in weft I _T can be expressed in%: $${\text{I}}_{\text{VS}}\text{=}\frac{\text{real chain account}}{\text{max chain account}}\text{x 100}$$

$${\text{I}}_{\text{T}}\text{=}\frac{\text{real duitage}}{\text{max duiting}}\text{x 100}$$

The difficulty of binding linked to the conjugation of I _C and I _T is given by an overall index I _E $${\text{I}}_{\text{E}}\text{=}\frac{{\text{I}}_{\text{VS}}{\text{+ I}}_{\text{T}}}{\text{100}}$$

To determine the maximum warp count, it is assumed that the yarns of known title are of cylindrical section and that in the case of the tightest texture, the warp threads are joined under the weft floats and are only separated by one weft thickness during face changes.

où
   Rc est le rapport d'armure en chaîne
   n_T le nombre de changements de faces de la duite
   dc le diamètre de la chaîne
   d_T le diamètre de la trameThe width x occupied by all the threads of a weave ratio binding on the pick making the most change is: $${\text{x = Rc · dc + n}}_{\text{T}}{\text{· D}}_{\text{T}}$$

or
Rc is the chain armor ratio
n _T the number of change of faces of the pick
dc the diameter of the chain
d _T the diameter of the frame

   C_M étant le compte maximal en chaîne
   1/c_M est le pas moyen en chaîneFurthermore and provided that x is expressed in the same unit of account as the chain, that is to say in cm, we have: $$\text{x =}\frac{\text{1}}{{\text{VS}}_{\text{M}}}\text{· Rc}$$

C _M being the maximum chain count
1 / c _M is the average chain pitch

d'où $${\text{I}}_{\text{c}}\text{=}\frac{\text{C}}{\text{Rc}}{\text{(Rc · dc + n}}_{\text{T}}{\text{· d}}_{\text{T}}\text{) x 100}$$

$${\text{I}}_{\text{c}}\text{= C (dc +}\frac{{\text{n}}_{\text{T}}}{\text{Rc}}{\text{· d}}_{\text{T}}\text{) x 100}$$

   où C, est le compte en chaîne réelFrom equations (9) and (10) we derive: $${\text{VS}}_{\text{M}}\text{=}\frac{\text{Rc}}{{\text{Rcdc + n}}_{\text{T}}{\text{d}}_{\text{T}}}$$

from where $${\text{I}}_{\text{vs}}\text{=}\frac{\text{VS}}{\text{Rc}}{\text{(Rc · dc + n}}_{\text{T}}{\text{· D}}_{\text{T}}\text{) x 100}$$

$${\text{I}}_{\text{vs}}\text{= C (dc +}\frac{{\text{not}}_{\text{T}}}{\text{Rc}}{\text{· D}}_{\text{T}}\text{) x 100}$$

where C, is the real chain account

où

D

: duitage réel

nc

: nombre de changement de faces du fil de chaîne faisant le plus d'évolutions sur le rapport de trame

R_T

: rapport de trame

By analogy : $${\text{I}}_{\text{T}}{\text{= D (d}}_{\text{T}}\text{+}\frac{\text{nc}}{{\text{R}}_{\text{T}}}\text{Dc) x 100}$$

or

D

: real duitation

nc

: number of change of faces of the warp thread making the most changes on the weft ratio

R _T

: frame ratio

The titer and density ρ of the wire are assumed to be known and homogeneous.

$$\text{d =}\frac{\text{0,00357}}{\text{√ρ}}\text{· √T}$$

avec
   d en cm
   en g/cm³
   T en tex

By considering a cylinder having the diameter d of the wire, 1 meter in height, we have $$\text{d =}\frac{\text{2}}{\sqrt{\text{π ρ}}}\sqrt{\frac{\text{T}}{\text{10³}}}$$

$$\text{d =}\frac{\text{0.00357}}{\text{√ρ}}\text{√T}$$

with
d in cm
in g / cm³
T in tex

If the maximum theoretical limits of I _C , I _T and I _E are 100, the practical limits according to the authors, are <94 or <80 to 85 for I _C and I _T and for I _E <74 respectively <64 to 72, for perfectly wearable items.

For I _C or I _T between 94 and 120 and I _E ≦ 74 we can consider weaving.

Indeed, taking into account the approximations made in the theoretical approach, one can obtain indices> 100 for articles which prove to be wearable.

Based on this theory, we compared a reinforced canvas weave called "Rip stop" (RP index) to a reinforced weave on a 2/1 twill base with two grouped threads of the same evolution of the process object of the invention (index A). . It should be noted that in terms of improvement in tear resistance and flexibility, it is the least efficient armor obtained using this process. The two armours are shown in FIGS. 17 and 18 respectively.

$${\text{I}}_{\text{CA}}{\text{= C · d · 100 (1 + n}}_{\text{TA}}{\text{/R}}_{\text{C}}\text{)}$$

$${\text{C · d · 100 = I}}_{\text{CA}}{\text{/(1 + n}}_{\text{TA}}{\text{/R}}_{\text{C}}\text{)}$$

donc $${\text{I}}_{\text{CRP}}{\text{= I}}_{\text{CA}}\text{x}\frac{{\text{(1 + n}}_{\text{TRP}}{\text{/R}}_{\text{C}}\text{)}}{{\text{(1 + n}}_{\text{TA}}{\text{/R}}_{\text{C}}\text{)}}$$

$${\text{I}}_{\text{CRP}}{\text{= I}}_{\text{CA}}\text{x}\frac{{\text{(R}}_{\text{C}}{\text{+ n}}_{\text{TRP}}\text{)}}{{\text{(R}}_{\text{C}}{\text{+ n}}_{\text{TA}}\text{)}}{\text{= 1,18 · I}}_{\text{CA}}$$

The ratios in chain R _CRP and R _CA and in frame R _TRP and R _TA of the two weaves are identical, respectively 27 and 22.
n _TRP = 26 n _CRP = 20 n _TA = 18 n _CA = 14
in the case of a comparison, the calculation is carried out on the assumption of the use of the same yarn in warp and in weft for the two articles either: d _TRP = d _TA = d _CRP = d _CA = d $${\text{I}}_{\text{CRP}}{\text{= C · d · 100 (1 + n}}_{\text{TRP}}{\text{/ R}}_{\text{VS}}\text{)}$$

$${\text{I}}_{\text{IT}}{\text{= C · d · 100 (1 + n}}_{\text{YOUR}}{\text{/ R}}_{\text{VS}}\text{)}$$

$${\text{C · 100 = I}}_{\text{IT}}{\text{/ (1 + n}}_{\text{YOUR}}{\text{/ R}}_{\text{VS}}\text{)}$$

so $${\text{I}}_{\text{CRP}}{\text{= I}}_{\text{IT}}\text{x}\frac{{\text{(1 + n}}_{\text{TRP}}{\text{/ R}}_{\text{VS}}\text{)}}{{\text{(1 + n}}_{\text{YOUR}}{\text{/ R}}_{\text{VS}}\text{)}}$$

$${\text{I}}_{\text{CRP}}{\text{= I}}_{\text{IT}}\text{x}\frac{{\text{(R}}_{\text{VS}}{\text{+ n}}_{\text{TRP}}\text{)}}{{\text{(R}}_{\text{VS}}{\text{+ n}}_{\text{YOUR}}\text{)}}{\text{= 1.18I}}_{\text{IT}}$$

In the same way we can calculate $${\text{I}}_{\text{TRP}}{\text{= 1.16 I}}_{\text{YOUR}}$$

So the overall index gives $${\text{I}}_{\text{ERP}}{\text{= 1.37 I}}_{\text{EA}}$$

This means that the "Rip stop" weave is 37% more difficult to weave than the 2/1 twill weave obtained according to the process which is the subject of the present invention.

With equal thread and texture, this difference of 37% is clearly noticeable to the touch, the flexibility of the weave, according to FIG. 18, being greater. In addition, when the weave according to FIG. 17 is no longer wearable, due to a too strong texture, the weave obtained according to the process which is the subject of the present invention still makes it possible to weave under perfectly satisfactory conditions.

Different comparative weaving tests were carried out in order to verify the above theoretical approach.

We woven an article 50% Kermel ® 50% Viscose FR Nm 45/2 warp and weft, 32 threads / cm and 22 picks / cm. 2/1 twill weave.

chaîne

: 110 daN

trame

: 80 daN

   Résistance à la déchirure amorcée force vive NF G07-148

chaîne

: 5,5 daN

trame

: 4,9 daN

The characteristics of this fabric are as follows:
Breaking strength according to standard NF G07-001

chain

: 110 daN

weft

: 80 daN

Resistance to tearing initiated live force NF G07-148

chain

: 5.5 daN

weft

: 4.9 daN

chaîne

: 112 daN

trame

: 83 daN

   Résistance à la déchirure amorcée vive selon norme NF G07-148

chaîne

: 9,3 daN

trame

: 8,9 daN

The same article of armor obtained according to the process which is the subject of the invention was produced with regular basic patterns with a 2/1 twill base with paths of two grouped threads of the same evolution in a drawing corresponding to that of FIG. 18. The results are as follows:
Breaking strength according to standard NF G07-001

chain

: 112 daN

weft

: 83 daN

Resistance to tearing initiated live according to standard NF G07-148

chain

: 9.3 daN

weft

: 8.9 daN

There is a marked improvement in resistance to tears started. The flexibility of the base fabric 2/1 twill is fully preserved, and even slightly improved, as shown by the calculation of the indices of the two fabrics. Twill 2/1 2/1 twill base reinforced with 2 bundled threads I _C = 106 I _C = 106.6 I _T = 73.3 I _T = 72 I _E = 77.7 I _E = 76.3

We have so far described three families of armor obtained according to the process which is the subject of the invention. The families with basic patterns with irregular floats, with basic patterns with regular floats and with basic patterns with random floats. We can still imagine a family with offset patterns in warp or weft. It is this fourth family which is illustrated by FIGS. 19 to 21. The rectangles drawn in FIG. 19 represent the paths of groups of thread of the same evolution surrounding the basic patterns. We see that if these patterns are aligned in warp, they are offset in weft. To obtain this result, it is sufficient for the groups of weft threads evolving together to cease to evolve together in order to integrate into the basic weave of the adjacent offset basic pattern of the second column. When these weft threads emerge from this basic pattern, they again evolve together over the entire width of the third column so as to be again integrated into the weave of the adjacent basic pattern of the fourth column. Other groups of weft threads border the basic patterns of the second and fourth columns while evolving together and are integrated into the basic patterns of the first and third column. This same principle is used in the case of FIGS. 20 and 21. In this last figure, the offset is effected by applying the same principle to the warp threads thus shifting the basic patterns in the direction of the columns and not in that of the rows. .

The tests carried out have shown that the resistance to tearing increases appreciably from a spacing between the grouped wire paths moving together from 10 to 70 mm. Below 10 mm the increase is good and the results become excellent below 5 mm.

Claims (10)

A method of forming a weave to reinforce the tear resistance of a twill or satin base weave fabric and their derivatives, characterized in that the surface of the fabric is divided into adjacent quadrangular base patterns, each delimited by two warp threads adjacent respectively to two opposite sides of the pattern and two weft threads, respectively adjacent to two other opposite sides of the pattern, which are added at least one thread to each of the warp and weft threads delimiting said patterns, and that the thread thus added is made to evolve in the same way as the weft or warp thread to which it has been added. Method according to claim 1, characterized in that the said basic patterns are sized to align them both in warp and in weft. Method according to claim 1, characterized in that the weave ratio of the fabric is dimensioned so that it comprises a number of said basic patterns in warp and weft, multiple of the ratio of said chosen basic weave. Method according to claim 3, characterized in that the basic patterns (M _LC ) are chosen so that they always have a number of threads N in warp and weft of the form:
N in frame of M _LC = X _LC · R + A _LC
N in chain of M _LC = Y _LC · R + B _LC
or
L = line number of the pattern
C = column number of the pattern
R = ratio of base armor

X _LC , Y _LC : positive integer
A _LC , B _LC : positive integer between 0 and R-1 Method according to claim 2 or claim 4, characterized in that said basic patterns are sized on the same column C, respectively the same row L so that they have the same number of threads in warp, respectively in weft. Method according to claim 4 or 5, characterized in that in order to guarantee identical bundling of all the warp threads, all the equal A _LCs between 0 and R - 1 are chosen and all the equal B _LCs between 0 and R - 1. Method according to claim 4 or 6, characterized in that the Y _LC , X _LC , B _LC and A _LC comply with the following formulas:
For L = 1 at NbMtr

For C = 1 at NbMch

z _L and w _C = positive integers
NbMch = number of basic chain patterns
NbMtr = number of basic patterns in the frame Method according to claim 4 or 5, characterized in that the Y _LC , X _LC , B _LC and A _LC comply with the following formulas:
For L = 1 at NbMtr

For C = 1 at NbMch

z _L , w _C : positive integers A method according to claim 5 or 8, characterized in that to guarantee identical bundling of all the wires, all the A _LC equal and different from 1 and all the B _LC equal and different from 1 are chosen. Method according to one of claims 1 to 4, 6 to 9, according to which the spacing between the two warp threads and the two weft threads delimiting said patterns is between 1 and 70 mm.

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