FR2503197A1 - WOVEN STRAP, PARTICULARLY FOR A SEAT BELT, AND MANUFACTURING METHOD - Google Patents

Abstract

THE WOVEN STRAP INCLUDES THREADS OF WEFT 3 HAVING A TITLE LESS THAN 2300DTEX OR 1600DTEX AND IN NUMBER OF AT LEAST 70 FOR 10CM, THE CHAIN THREADS 4 BEING AT LEAST 2 SHORTER THAN IN ANALOGUE WEAVINGS WITH WEFT THREADS OF LARGER TITLE AND IN LESS NUMBER AND PRESENTING THE SAME CHARACTERISTICS OF ELONGATION, MECHANICAL STRENGTH AND RESISTANCE TO ABRASION. OBTAINING WEAVING STRAPS OF REDUCED THICKNESS KEEPING THE SAME MECHANICAL STRENGTH CHARACTERISTICS AS CONVENTIONAL STRAPS.

Description

1. The present invention relates to a woven strap

  for seat belt system, more particular-

  2/2 type woven tie or interlacing, as well

  that a method of manufacturing such a strap.

  In the automotive industry, vehicle seat belt systems of the retractable type are provided for the safety of the occupants of a vehicle.

  usual, that is to say three points, or also ty-

  pe says passive. Car manufacturers require manufacturers of seat belt systems to develop miniaturized and lightweight reels. The reduction in the volume of the weight of the belt winders actually brings

  a contribution to improving comfort and efficiency

efficiency of the motor vehicle.

  For the development of strap winders

  small dimensions and light weight, the winding manufacturer

  is particularly interested in having

  thinner straps, due to the fact that a reel

  reduced sions cannot store, compared to

  traditional rollers larger than a length

  weaker traditional thick straps and relati-

heavily heavy.

  The object of the present invention is precisely

  to offer a woven strap of reduced thickness which

2,2503,197

  touting the qualities demanded of the usual bands and relating in particular to the characteristics of elongation, holding

  mechanical and resistance to friction or abrasion.

  To do this, according to a characteristic of the present invention, the titer of the weft threads is less than 2/300 dtex (twice 300 dtex) or 1/600 dtex (once 600 dtex), in that the number weft yarn is at least 70 by 10 centimeters, and in that the warp yarns are at least 2 CC shorter than in woven fabrics comparable to weft yarns of larger weight and fewer weft yarns and having the same elongation characteristics, of mechanical strength

and resistance to friction.

  According to the proposal of the object stated above, namely obtaining a thinner strap, one could endeavor to modify as a significant parameter, the thickness of material per unit of surface, typically per centimeter square. One possibility to achieve this decrease in material thickness per square centimeter

  would consist in reducing the weight of the weft threads. Any-

  times, in this case, the weft threads of the new strap would turn out to be thinner than in the usual straps

  with the disadvantage that the solidity of the seams is not

  would be unduly diminished. Another possibility considered-

  ble would be to decrease the number of weft threads per unit

  length tee. However, one should expect, in this

  case, when obtaining a strap with poor quality

  friction or abrasion resistance beds. On the other hand, the behavior in mechanical behavior of the strap in

  3U transverse direction, i.e. shear strength

  It would also be greatly reduced.

  The Applicant has noted, however, that we could, on the other hand, make the weft threads thinner than in traditional straps, that is to say reduce the

  title of the weft threads. It thus becomes possible, because

  sound of the reduced amount of material per unit area

  of the strap, to get a thinner woven strap. The uni-

  title or linear mass dtex (1 denier = 1.1 dtex)

3 2503197

  is expressed in weight per unit length of 10,000 meters and is currently the decimal unit used to denote the thickness of yarns or fibers, in this case, weft yarn. The expression "2/300 dtex" refers to a woven system in which a 300-denier thread is inserted twice into an opening in a round-trip mode forming a loop while the expression "1/600 dtex "refers to a weaving system in which a thread of 600

  penny is inserted once into an opening.

  Another aspect of the technique according to the present invention relating to the reduction of the thickness of the weft yarn relates to the increase in the number of weft yarns per unit of length. Such a measure can be adopted without recovering an overall quantity of material per

  square centimeter comparable to conventionally woven straps

  nelles. The predominant advantage of this measure is

  increased resistance characteristics to abrasion

  due to the increase in the number of working threads

me.

  According to another aspect of the invention, in order to

  solve the problem, the warp threads have a length reduced by 2% compared to the warp threads of the products

  comparable woven fabrics. By "comparable woven product" we mean

  tightens the conventional straps, having a weft thread title greater than for example 2/300 dtex and a number of

  weft yarns less than for example 70 for 10 cm

  very while resistance to elongation, mechanical strength and abrasion resistance of thick straps

  and heavy traditional bill are the same as

  thin straps according to the present invention. A re-

  reduction in the length of chain wire, compared to

  warp threads in conventional straps, can be obtained

  even if the number of warp threads per unit of length

  heat is increased, always in comparison with health

  conventional gles, to increase strength or resistance

  seams and abrasion resistance. Another effect of using thinner warp yarns

  is that the undulation of the warp threads

4. 1D [(73107

  i.e. their deflection or reorientation around the weft threads in the woven frame is reduced, which allows better use of the resistance

warp threads.

  So, for example, assuming a charge

  100% linear for a straight warp thread, i.e.

  say without creases or ripples, the holding in charge of

  this wire is reduced to eg 80 'W due to the short-

  bures or reorientations of the yarn around the weft yarns, l0 as is well known in the art.Therefore, a more judicious use of the mechanical strength

  linear of the warp thread plays an important role.

  The basic concern of the present invention

  tion being to reduce the thickness of the weft threads to reduce as much as possible the thickness of the final woven strap, the common opinion would tend to assume then

  that the number of warp threads should not be reduced

  naked, so as not to reduce thoughtlessly the resistance

  the tension of the strap. However, due to the ef-

  advantageous effects due to the reduction in undulations and the best use of the linear mechanical strength of the wires, it is perfectly possible, according to another aspect of the invention, to reduce the number of wires of

  warp in relation to the number of warp threads usual-

  met in conventional straps. It was thus found that, if there was an increase

  relative ripple due to the increase in name-

  bre of weft threads, these undulations could however be kept within relatively low limits in order to achieve the aforementioned best use of the mechanical strength of the warp threads. It is thus possible to reduce the number of warp threads of the order of 5 to 7 A without reducing the mechanical strength of the

final woven strap.

  These characteristics specific to the invention are by no means evident in the field of weaving,

  especially as the safety criteria reached by health-

5.

  In no case can conventional agreements be

  in accordance with the very strict regulations in force

  but these criteria are in no way called into question by the technique according to the invention, notwithstanding the final production of a thinner strap. According to another characteristic of the present invention, the number of weft threads per 10 cm in the new strap is between approximately 70 and 85, preferably between 73 and 80. The most suitable values

  can be determined according to particular requirements

  required for certain product categories, taking into account that many parameters must

  be taken into consideration, while we think first

  take place with the nature of the material to be chosen for

  the production of weft and warp threads. In principle

  eg, the title of the weft threads can be chosen as low as

  ble as possible; however, in practice, the lower limit

  is determined by the mechanical strength required for

  seams and abrasion resistance characteristics.

  According to a characteristic of the invention, a pro-

  assigned to manufacture a woven strap in accordance with the

  vention is characterized in that we use in the weaving of the web weft threads having a titer less than or equal to 2/300 dtex or 1/600 dtex, their number per 10 cm being at least 70 for weaving with warp yarns, the latter being at least 2 'O shorter than in comparable weavings with weft yarns of larger weight and in smaller numbers to still offer the same characteristics to the elongation of

  mechanical and abrasion resistance.

  According to one technique, this results in a reduced quantity of material per square centimeter, and a reduction in the undulations of the warp threads in the woven strap, which, although being finer, exhibits no reduction in the usual characteristics of the straps, such as the characteristics of elongation, mechanical strength and

  abrasion resistance. These considerations apply not only

6.

  also for weaving with 2/2 type fasteners, more

  particularly targeted here, but also for weaving with 3/3, 4/4 and 5/5 fasteners or even for fasteners of the 3/2 type for the formation of hollow corners. Preferably, the fibers are polyester or nylon. A conventional strap has a typical elongation of the order of 8 to 10 'O for a strap thickness - not calendered - of about 1.2 mm. Such a strap has a mechanical strength of 2900 daN, weighs 60 grams per meter, the weaving density, that is to say the number of weft threads per unit of length, referred to 10 cm being

  68. The title of the polyester threads is then 2/550 dtex.

  A thinner strap according to the present invention

  has the same elongation, mechanical strength and

  abrasion-resistant than those of the classic strap, mentioned above. However, in one embodiment of the new strap according to the invention, the strap thickness is 1.0 mm, its weight being 52 grams per meter, the weaving density of 79 per 10 cm and the title

  polyester threads of 2/280 dtex.

  This example particularly illustrates

  the improvements of the new sanitary weaving

  gle according to the invention compared to conventional weavings

  tional in terms of thickness reductions and

  weight while keeping the characteristics unchanged

mechanical safety ques.

  The two straps which have just been described

are of the 2/2 attachment type.

  To prevent a thinner strap depending on the

  present invention to become soft, that is, excess

  Another flexible feature is that, according to another characteristic,

  teristic of the invention to fix it thermally by subjecting it to irradiation of infrared rays. We

  knows that certain physical properties, such as al-

  long, the abrasion resistance and flexibility can be changed by subjecting a woven material to curing or thermal fixing. However, this

2503 1 97

  7. thermal fixing is generally obtained by direct thermal contact or licking by hot air, typically at a temperature of 2300C. It follows a gathering, a fixing or a stretching of the woven material. However, this technique has the disadvantage that the heat supply almost exclusively interests the external surfaces of the

woven band to fix.

  On the contrary, the use of infrared rays

  red provides full or total fixation of the strap fibers, the infrared rays heating substantially all of the strap material. In this way, it is possible to give a fine strap, employing in particular finer weft threads, a suitable rigidity, that is to say flexibility.

required.

  By using a woven strap according to the present invention, it is possible to gain up to 32 grams for the development of seat belt systems, thereby contributing to the technical progress of the reels.

strap.

  Other features and benefits of the

  - present invention will emerge from the following description

  of embodiments, given by way of illustration but in no way limiting, made in relation to the appended drawings, in which: FIG. 1 is a schematic view, in section, greatly enlarged, of a portion of a strap woven according to the prior art; and Figure 2 is a view similar to that of the

  Figure 1, of a thinner strap according to the present invention

  tion using finer weft threads.

  In the two embodiments shown in Figures 1 and 2, the weaving is of the fastener type

  2/2. In the prior art shown in the figure

  re 1, the warp thread 1 undergoes significant undulations due to the type of attachment 2/2. It follows that, for relatively thick son, the calendered thickness D of a conventional 8. strap is about 1.25 mm, as mentioned above.

  In the thinner strap according to the invention,

  presented in FIG. 2, the weft threads 3 are thinner, and the warp threads 4 consequently have less pronounced undulations, so that the final uncalendered thickness d of the strap is reduced to approximately

1.0 mm.

  Although the present invention has been described in relation to particular embodiments, it

  is not limited but is on the contrary suscep-

  tible of modifications and variants which will appear

to the skilled person.

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Claims (4)

  1 - Woven strap for seat belt system   curity, more particularly of the type with 2/2 attachment,   characterized in that the title of the weft threads (3) is in-   less than 2/300 dtex or 1/600 dtex, in that the number of weft threads per 10 cm is greater than or equal to 70, and in that the warp threads (4) are at least 2% shorter than in conventional weavings using weft yarns with a higher titer and a smaller number of weft yarns and having the same characteristics of elongation, mechanical strength and resistance to abrasion. 2 - Woven strap according to claim 1, characterized in that the number of weft threads (3)   per 10 centimeters is between 70 and 85, preferably this between 73 and 80.   3 - Method of manufacturing a woven strap se-   lon claim 1 or claim 2, characterized in that it consists in using weft threads (3) having a titer less than 2/300 dtex or 1/600 dtex and in number per 10 cm greater than 70 , for weaving with warp yarns (4) at least 2% shorter than in conventional weavings having weft yarns of larger and fewer titer and having the same elongation characteristics,   mechanical resistance and abrasion resistance.   4 - Method according to claim 3, characterized   in that it includes the step of subjecting the woven material   irradiation with infrared rays to fix it thermally.