Textiles: weaving – Miscellaneous – Loom cleaning
Patent
1998-12-14
2000-04-18
Calvert, John J.
Textiles: weaving
Miscellaneous
Loom cleaning
139 11, 139 35, D03D 4100, D03D 900
Patent
active
060503033
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to the field of textile weaving and, more specifically, to a method making it possible to improve the weaving of a fabric of warp yarns having a high modulus of elasticity.
BACKGROUND OF THE INVENTION
As is known, in a conventional weaving loom, the warp yarns are unwound from a beam and then pass over a back-rest roller. Downstream of the latter, depending on the selected weave, the various parallel warp yarns are drawn alternately upwards and downwards in order to form the shed. The various warp yarns subsequently meet again at the fell point, where the comb beats up the cloth after each weft insertion.
Within the shed, the yarns are drawn upwards and downwards by means of healds. It will easily be appreciated that these warp yarns drawn in this way undergo mechanical stresses whenever the shed opens. These stresses lay the yarns very firmly onto their successive guides (yarn guides, shield eyes, comb, etc.), thus causing fraying and bringing about yarn breaks which bring the weaving loom to a stop, thus slowing the actual production speed and impairing the uniformity of the cloth obtained.
Some designers of weaving looms attempt to reduce the stresses imparted to the yarns by giving the back-rest roller a reciprocating movement in synchronism with the opening of the shed. Unfortunately, the considerable weight of the back-rest roller and, consequently, its high inertia reduces mobility, the more so because the beating-up frequency is high.
It will be appreciated that the mechanical stresses which the yarns undergo are the greater the higher the beating-up speeds. Thus, it was found that, for high-speed weaving looms, that is to say mainly those in which the weft yarn is driven by water jet or air jet, it is difficult to exceed the speed of 1000 to 1200 beats per minute, without seeing signs of serious damage to the warp yarns and a large number of breaks, the more so because the warp yarns have a high modulus of elasticity.
This phenomenon, which is the more pronounced, the more rigid the warp yarns are, gives rise, in particular, to more frequent malfunctions during the weaving of polyester than during the weaving of polyarnide.
The invention therefore attempts to solve the problem of warp yarn breaks following high mechanical stresses experienced by the yarns at the moment the shed opens and, as a consequence, to increase the beating-up speed of the looms, whilst at the same time maintaining the same weaving quality.
SUMMARY OF THE INVENTION
The invention relates to a method for improving the weaving of a fabric comprising warp yarns having a high modulus of elasticity, in which: direction of advance of the warp, by a shed opening point at the entrance and by a fell point on the other side; order to form a fabric;
This method is characterized in that, in the vicinity of the opening point of the shed, the warp yarns are heated to a temperature sufficient to bring about a local reduction in the modulus of elasticity of the warp yarns, followed by cooling of the warp yarns in the shed before they reach the healds.
As defined herein modulus of elasticity (or Young's modulus) means the leading coefficient (or the slope of the origin) of the curve which gives, on the ordinate, the pulling force and, on the abscissa, the elongation which this force causes. This modulus is expressed in newtons/tex or in gigapascals (GPa). As an example, the modulus of elasticity of cold polyester yarns is of the order of 10 GPa for textile yarns having high residual elongation or elongation at break (greater than 35%). It may reach 15 GPa for high-strength yarns with low residual elongation (of the order of 15%). By way of comparison, the Young's modulus of polyarnide yarns is of the order of 5 GPa. In both cases, heating beyond the second-order transition temperature causes a considerable reduction in the modulus of elasticity when the yarn is then stretched. Typically, the modulus of elasticity under hot conditions may decrease, and, in some cases, reaches one tenth of the
REFERENCES:
patent: 3772872 (1973-11-01), Piazza et al.
patent: 4024003 (1977-05-01), Buhler
Calvert John J.
Corbiere S.A.
Muromoto Jr. Robert H.
LandOfFree
Method for enhancing the weaving of a warp yarn fabric having a does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for enhancing the weaving of a warp yarn fabric having a , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for enhancing the weaving of a warp yarn fabric having a will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2329009