FR2790771A1 - Weaving of seersucker fabrics comprises applying heat to the upper level of the warps in the shed followed by cooling before reaching the healds to reduce their module of elasticity - Google Patents

Abstract

During the weaving of a fabric at a loom, the warps (3) are heated at the point where the shed is opened, followed by cooling of the warps in the shed before they reach the healds (7,8). The heating is applied only to a part (34) of the warps in the shed. Downstream of the back rest roller (4), the warps are divided into two levels (33,34) to form the shed. The upper warp level (34) is heated by a plate (20) to a sufficient temperature to give an elongation and reduce the module of elasticity. The temperature of the warps can raised by a heating or scalding stage or by calendering. A transfer paper can be applied to the warps for a colored pattern to be transferred from the paper to the heated warps, and the paper is detached at the same speed as the warp forward movement, leaving the transferred pattern only on the heated warp level (34). The colored pattern is in parallel bands along the line where the paper is peeled away, where the colored bands are lined up near the warps which carry the transfer. An Independent claim is included for a woven fabric where the warps are crepe yarns. Preferred Features: The fabric is woven with a number of different weft yarns. The woven fabric has a pattern of parallel bands, where a part of each band has a higher color intensity than the remainder of the band. At least one band is in two colors.

Description

[PROCESS FOR OBTAINING WOVEN FABRICS, AND FABRICS

  TEXTILES WOVEN OBTAINED ACCORDING TO THIS PROCESS Technical field The invention relates to the field of textile weaving. It relates more precisely to a process making it possible to obtain fabrics having a particularly appearance

  original, approaching the fabrics of cotton pancakes, more generally called "seersucker".

  Previous techniques As is known, the fabrics of cotton pancakes, or seersucker, are generally manufactured according to a specific weaving process, which uses two

beams of beams.

  Thus, the threads from the two beams form two parallel plies which are mixed at the level of tie bars, before entering the area of

  crowd training. The two beams are necessary to allow a different advance of the plies of wires of different nature.

  Such a method, if it makes it possible to combine threads having very varied characteristics which are necessary for the appearance of known embossing phenomena

  on these fabrics, on the other hand has the disadvantage of a great complexity of implementation.

  Indeed, the association of two rollers within the same loom is extremely complex, because it requires precise positioning of each of the threads

from different beams.

  The complexity of such an association obviously makes the fabric manufactured

relatively expensive.

  In addition, the mechanism making it possible to combine the threads from two different beams into a single layer, ensuring only a specific mixing, and a given and fixed distribution of the threads from the two beams.35 In other words, the weaving looms used for making seersuckers are absolutely not versatile, but on the contrary dedicated to making a single

type of fabric.

  In addition, the combination of wires having different mechanical characteristics is relatively sensitive, and therefore does not make it possible to obtain effects.

of great variability.

  One of the objectives of the invention is to allow the production of fabrics having an appearance close to fabrics known in the name of seersucker, and which are extremely versatile, that is to say making articles of great

  variety, using a single loom as simple as possible, and carrying a single beam formed with a single quality of yarn.

  One of the other objectives of the invention is to allow the achievement of particularly pronounced effects by the choice of yarns having characteristics

very diverse mechanical.

Statement of the invention

  The invention therefore relates to a method for obtaining a woven fabric having warp threads of a high modulus of elasticity.

  This process comprises, in a known manner, the following stages in which: - a web of parallel warp yarns is unwound continuously from a beam; - Passing said sheet on a son-carrying roller; - A crowd is formed by means of beams, said crowd being defined in the advanced direction of the chain at the entrance by a crowd opening point, and on the other side by a stitch; - we insert a weft thread in the crowd in the vicinity of the stitching point to form a fabric; - And finally, we regularly tow and roll up the fabric thus formed, and in which in the vicinity of the opening point of the crowd, it causes heating under tension of the warp threads at a temperature sufficient to cause a local decrease in modulus of elasticity of the warp threads, followed by 3 cooling of said warp threads in the crowd before they reach the stringer. The process according to the present invention is characterized in that only part of the warp yarns is heated under tension. In other words, the method according to the invention treats part of the warp threads in a differentiated manner, which means that, over the total width of the fabric, only part of these warp threads has undergone the heat treatment step under tension10 which lengthens them and modifies their potential for subsequent shrinkage, and it can be seen that the elastification of the elongated wires by heating allows them to remain taut at the point of shaping. This alone allows the use of a single beam delivering homogeneous threads but transformed in a differentiated manner during weaving in order to obtain the "seersucker". Thus, when the fabric thus obtained undergoes a subsequent step of removal, the warp threads behave differently depending on whether or not they have undergone the

  heat treatment during weaving.

  It follows that the different length of the warp threads and the phenomenon of complementary shrinkage, cause different deformations in the fabric.

  and distributed according to the selection of the warp threads which have or have not undergone heating during weaving.

  Indeed, the warp threads which have undergone the heat treatment during weaving have a lesser shrinkage capacity than those which have not undergone it, and show

  the embossed zones in thickness when the unheated wires retract.

  The effects thus obtained are strongly pronounced, and variable depending on the

wires used.

  In practice, according to the method according to the invention, the web is separated, downstream from the yarn-carrying roller, into two series of yarns, and a spacing is maintained between the two series of warp yarns, so that only one of the two series

the characteristic heating.

  In this way, by means of two simple spanning rods, the tablecloth is divided according to the desired geometry, by selecting the number and the position of the

  wires to be heated under tension.

  Thanks to the simplicity of the separation mechanism, it is possible to vary without any difficulty the distribution between the two series from the sheet,

  selecting at will the desired distribution.

  One can for example, choose to heat only a weaker part of the wires

  chain, retaining a larger number of unheated wires, which will then undergo a strong shrinkage.

  Conversely, it is possible to choose to heat a majority of the warp threads to obtain still other effects.

  The configuration of each series can also be chosen according to the user's wishes, and without any restrictions, with the possibility

  to obtain various effects on the width of the fabric. Thus, it is possible to create each series using identical numbers of wires gathered in groups or 20 bundles.

  It is also possible to vary the number of threads per bundle over the width of the fabric, and with total freedom of choice.

  Advantageously in practice, the method according to the invention also includes a "free" heat treatment step.

  This treatment can advantageously be a scalding or even a hot air treatment without tension constraint as can be obtained on the

  continuous materials called "tumbler".

  Thus, by forcing the withdrawal to free, one accentuates the difference in behavior between the wires having undergone the heating and the others, which causes

  more pronounced volume deformations.

  In an advantageous form of the method, it is possible to follow the step of removing a calendering, or more generally of a crushing of the patterns formed, to

  get a different and flattering appearance.

  The invention also relates to the textile fabrics obtained by the process according to the invention. Advantageously in practice, the warp yarns used can be pancake yarns, or textured pancake yarns, that is to say having undergone a twisting step and

a false twist step.

  We can also vary the effects within the fabric using different weft yarns.

  As already said, the fabric obtained can have extremely varied effects depending on whether the yarns which have undergone the heat treatment during weaving are in number

  equal or more or less numerous than those which retained their capacity of withdrawal without having been heated.

  In addition, the effects can also be varied by choosing, within the series of heated wires, bundles having a distribution, either uniform,

  is variable according to the choice of the manufacturer.

Brief description of the figures

  The manner of carrying out the invention, as well as the advantages which ensue from it, will emerge clearly from the description of the embodiments which follow, with the support

  appended figures, in which: FIG. 1 is a side view of a weaving loom operating according to the method according to the invention.

  FIG. 2 is a top view of the sheet at the level of the characteristic zone of the invention in which the heat treatment is caused

during weaving.

  Figure 3 is a top view of the same area, but with a distribution

  different from the two series of warp threads.

  Figure 4 is a photograph of a fabric obtained in accordance with the invention.

  Figure 5 is a photograph of the fabric of Figure 4 having been calendered.

  Way of realizing the invention As already said, the invention relates to a weaving process intended to be applied to warp threads generally having a high modulus of elasticity. This process can be implemented on a traditional weaving loom, equipped with elements making it possible to ensure a thermal treatment of the warp threads.

  that they undergo tensioning by the take-up roller of the fabric of the loom, and as the Applicant described in the aforementioned patent FR 2 751 350.

  Such a weaving loom further comprises special arrangements making it possible to produce the characteristic fabric of the invention.

  Thus, as illustrated in FIG. 1, a weaving loom has, in the direction of travel of the thread, a beam (1) mounted on a drum (2), and on which are wound.

  all parallel warp threads.

  These warp threads (3), from the beam (1) are unwound up to a thread-carrying roller (4) from which they take a substantially horizontal direction. To cross the characteristic area of the invention described below, the warp threads (3) pass on either side of two spaghetti strips (31, 32). After these sponges (31, 32), they are brought together again in a single ply by the guides (5, 6), then they are supported by healds (7, 8) whose object is '' spread up or down the different warp threads (3) to form the shed (9), and allow the insertion of the weft thread (16) .30 After the heddles (7, 8), the threads of chain meet at the point of facade (10) on which comes to beat the comb (11), after each re-opening of the crowd. From the point of shaping, the fabric (12) thus formed passes through different

  return rollers (13) to lead to the winding system (14).

  As already said, the invention consists in heating only part of the warped wires under tension in the vicinity of the opening point of the crowd, in order to reduce their modulus of elasticity, and if necessary allow them to undergo, thanks to the action of the trade, a jerky print just before weaving itself.

  Thus, various means can be adapted to provide this heating.

  In the illustrated form, it is a heating pad (20) present over the entire width of the set of warp threads, and which can come into contact with part of

  the layer of warp threads, between the spindle strips (31, 32).

  More specifically, it is a transverse heating element the underside of which is covered with a material with very high surface hardness and low

  friction rate to avoid abrasion by the warp threads which would cause subsequent deterioration of the warp threads themselves.

  It may in particular be an anodized or chromed or ceramic outer layer (24).

  Obviously, the invention covers all types of heating of the skate, and in particular those using electrical energy, to the appropriate connection means (22). As already said, according to an essential characteristic of the invention, only one

  part of the warp threads undergoes heat treatment due to the shoe.

  Thus, as illustrated in FIG. 1, downstream of the wire-carrying roller (4), the loom has at least one spanning rod (31) allowing the separation of the

  ply (30) in two series, namely a series (34) passing over the bar30 (31), and therefore intended to come close to the shoe (20).

  In contrast, the other series (33) passes below the bar (31), and is therefore further from the shoe (20) than the series (34).

  The two series (33) and (34) travel parallel paths until reaching

  to the second spreading rod (32) marking the end of the zone of separation of the two series (33, 34).

  Depending on the distribution of the different bundles forming the two series, a distribution is obtained inside the final fabric, of threads capable of undergoing shrinkage,

  and elongated and already fixed wires.

  FIG. 2 illustrates a distribution of these wires inside each of the

series.

  Thus, as illustrated diagrammatically, the series of wires traversing the characteristic zone while being distant from the shoe, is broken down into several bundles (40,

  42, 44) passing under the bars (31) and (32).

  Conversely, the beams (41, 43, 45) pass them, over the bars

  (31, 32) and therefore have a route passing close to the skate.

  In FIG. 2, the different beams (40, 45) have identical widths,

  which results in the final product by deformations uniformly distributed approximately in a regular grid.

  Conversely, the breakdown of the sheet according to the diagram in FIG. 3, in which the different beams (50, 55) all have different widths,

  induces a different distribution of effects on the finished fabric causing particular patterns.

  As provided in the document of the Applicant FR 2 751 350, the shoe can be associated with any advantageous device making it possible to avoid degradation or even

  fusion of the threads when the progression of the threads is stopped.

  In addition, different types of heating can also be adopted.

  In accordance with the method of the invention, a fabric was made from warp threads made of polyester, of a count of 50 decitex, with 36 strands, twisted to

  1300 turns per meter, and having previously undergone a false twist step.

  So this textured crepe warp yarn was woven with weft yarns

  also in polyester, 50 decitex, 36 strands and twisted at 750 turns per meter.

  By using a heating pad making it possible to raise the temperature in the vicinity of 220 ° C., the fabric was obtained, a photographic reproduction of which constitutes FIG. 4. Such a fabric has multiple hollow and raised areas.

  formed by a differentiated length of the threads and accentuated by the differentiated withdrawal of the different areas of the fabric.

  This shrinkage is further accentuated by the implementation of a subsequent free heat treatment such as scalding.

  The effects obtained can still have a greater variety, by subjecting an additional calendering or ironing step allowing

  1 5 to overwrite the different patterns, as shown in the photograph in Figure 5.

  It appears from the above that the process according to the invention makes it possible to obtain fabrics having a particularly attractive and original appearance,

  presenting multiple zones in relief and in hollow, like among other fabrics20 of seersucker.

  In addition, the process according to the invention allows, by the simplicity of the means which it uses, a very great versatility, and the economic and

  fabric of a wide variety without particular modification of the simplest loom25.

Claims (6)

  1 / A method for obtaining a woven fabric having warp yarns with a high elasticity module, in which: a continuous web of warp yarns (3) is unwound continuously from a single beam (1); - said ply is passed over a thread-carrying roller (4) - a crowd (9) is formed, by means of heddles (7, 8), defined in the advanced direction of the chain at the entrance by a point d 'opening (15) of the crowd, and on the other side by a stitch (10); - a weft thread is inserted into the shed in the vicinity of the stitch (10) to form a fabric; - And finally, we regularly tow and roll up the fabric thus formed, and in which in the vicinity of the opening point of the crowd, we cause under tension a heating of the warp threads (3) to a temperature sufficient to cause a elongation and a local decrease in the modulus of elasticity of the warp threads, followed by cooling of said warp threads in the crowd before they reach the stringers (7, 8), characterized in that one causes overheating on only part of the wires chain.   2 / A method according to claim 1, characterized in that: - downstream of the thread-carrying roller, the sheet is separated into two series of threads (33, 34); maintaining a spacing between the two series of warp threads (33, 34) to   only subject one of the two series to warm-up.   3 / Method according to one of claims 1 or 2, characterized in that it further comprises, a subsequent step of free heat treatment.   4 / A method according to claim 3, characterized in that the free heat treatment step is a scalding.   / Method according to one of claims 1 to 4, characterized in that it further comprises, a calendering step.   6 / Textile fabric obtained according to the method according to one of claims 1 to 5.   1I 7 / Textile fabric according to claim 6, characterized in that the warp threads are pancake yarns.   8 / textile fabric according to claim 6, characterized in that it comprises several different weft son.