Textiles: manufacturing – Thread finishing – Surface modification of running length
Patent
1993-06-07
1995-05-30
Woo, Jay H.
Textiles: manufacturing
Thread finishing
Surface modification of running length
28244, 2642107, 2642108, 2642905, 264291, 425 66, D01D 516, D02J 122
Patent
active
054190223
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to an apparatus for spin-drawing at least two thermoplastic filament yarns on at least two pairs of godets, each comprising two rotatable godets, of which at least one godet is driven and their axes of rotation lie skew with respect to each other and are arranged in such a way that the axis of rotation of the one godet is arranged to be able to pivot within a plane and this plane forms an angle with another plane.
BACKGROUND OF THE INVENTION
To spin-draw thermoplastic filament yarns such as polyesters, polyamides and the like, drawing devices having two or more pairs of rolls or godets (DE-A 1 907 782) are used. The axes of rotation of the rolls within the godet pair units are slightly inclined to each other to produce a certain winding pitch of the laid-on thread. Accordingly, the two axes of rotation lie within a common plane. Any change in the winding pitch required can easily be undertaken by changing the angle which the two axes of rotation together form.
It is also known that in a pair of godets, the axes of rotation of the two godets can be pivoted within two different planes, which are parallel to each other, perpendicular to the line connecting the godet axes.
It has been shown that neither the one nor the other of the described axial arrangements is optimal for the simultaneous spin-drawing of more than one thread.
It has been found that the winding pitch of the thread loops on one pair of rolls becomes smaller, the further the filament yarn is laid on towards the front, free end of the rolls. When only one filament yarn is being handled on a drawing frame, this is not of importance. When two or more filament yarns are handled simultaneously, a systematic reduction takes place in the spacings between the thread loops laid on parallel to each other the pair of godets. This reduction propagates itself to each downstream pair of godets, so that when three or more pairs of godets are used, the spacings between the filament yarns become so small that they can no longer be separated or no longer be sufficiently separated from each other. In the spin-drawing of multifilaments, it can moreover occur that individual fibrils from a filament yarn cross over to the neighboring filament yarn; as a result, differences in linear density are caused in the filament yarns which are produced simultaneously in this manner. Furthermore fibril breaks or thread breaks are caused by this on the drawing frame, which influences both the filament yarn quality and the economic efficiency of the process.
SUMMARY OF THE INVENTION
The object of the invention is to provide an apparatus for spin-drawing two or more filament yarns, which apparatus ensures the maintenance of a sufficient spatial separation between the individual yarn loops on the pairs of godets.
The object is achieved according to the invention in that the angle .beta. is 10.degree.-60.degree..
The axes of the respective godets belonging to a pair of godets are arranged to be able to pivot with respect to each other in such a manner that the pivoting plane of a godet axis forms an angle of intersection .beta. with the plane joining the godet axes which contains both the center of this axis and the other godet axis.
It has been shown that the decrease in the winding pitch is dependent on the choice of the angle of intersection .beta.. If the godets are arranged in such a way that the pivoting planes of their axes are perpendicular to the joining plane, angle of intersection .beta.=90.degree., this decrease is considerably more greatly expressed than when the godet axes are arranged to pivot within the common joining plane. However, the decrease in the winding pitch is surprisingly not monotonic, but passes through a minimum.
It is expedient, within a multi-stage drawing frame having more than two pairs of godets, to arrange all pairs of godets in such a way that a sufficient spatial separation of the thread wraps is ensured.
A working width of the godets of 250 mm to 400 mm, in particular of 250 mmm to 350 mm, ha
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patent: 4522774 (1985-06-01), Donnelly et al.
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Leyson Joseph
Rhone-Poulene Viscosuisse SA
Woo Jay H.
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