METHOD AND EQUIPMENT FOR SYNTHETIC YARNS STRETCH BY USING STEAM AS HEATING MEANS

PROCEDE ET INSTALLATION POUR L'ETIRAGE DE FILES ELASTIQUES SYNTHETIQUES A L'AIDE DE VAPEUR

English Abstract

Method for stretching a thermoplastic synthetic yarns set, in the form
of warp chain characterized in that steam is used as heating means, in
the form of laminar jets directed on to the yarn transversally with
respect to the direction run of the yarn.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for stretching a set of synthetic thermoplastic yarns in
the form of warp chain characterized in that, as heating means of the
yarn, steam is used in the form of laminar jets directed on to the yarn
transversally with respect to the direction run of the yarn.
2. The method according to claim 1 wherein the fed yarn to be
stretched is previously washed in hot water to remove the residual
spinning oil.
3. The method according to claim 1 wherein low pressure saturated steam
is used.
4. The method according to claim 1 wherein as supplemental heating
means a device (coil) is used in which diathermal oil flows, placed
inside the steam supply chamber.
5. Equipment for the realization of the stretching method according to
claim 1, characterized in that it comprises heating plates B and B'
supplying steam in the form of numerous laminar jets coming out from
parallel splits placed in said plates and having a perpendicular
direction with respect to the yarn run.
6. The equipment according to claim 5 wherein the steam supply chamber
is provided inwardly with a coil for supplemental heating suitable for
diathermal oil circulation.

Description

f~ S 4 S 3
METHOD AND EQUIPMENT FOR ~YN~ lC YARNS ~lnh~ BY USING STEAM AS
HEATING MEANS
FIELD OF THE ~.~ lON
The present invention relates to a method for stretching more or less
interlaced thermoplastic yarns, characterized in that steam and the
relative equipment are used as yarn heating means.
PRIOR ART
Some known methods for stretching synthetic yarns encompass an aqueous
liquid bath maintained at the stretch temperature. The vat cont~ining
the thermostated liquid must be sufficiently large in the bath to
realize a yarn path sufficiently long to allow the desired temperature
to be reached.
Other known methods realize yarn heating by means of heating elements
(plates or cylinders) on which the yarn is run. In other cases the yarn
is passed in a chamber cont~ining a gas (air) at a sufficiently high
temperature.
These methods however do not allow a quick precise and constant with
the time heating.
~UMMARY OF 1~ lNV~.llON
The method according to the present invention is based on the use of
steam in the form of a series of laminar jets having a transversal
direction with respect to that of the yarn run. The method and the
corresponding equipment are directed to the stretch of a set of many
yarns, in particular of a warp chain (or chain fraction).

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In this device saturated steam is used, at the pressure usually
available in the factory, in the order of 295 KpA.
BRIEF DESCRIPTION OF I~IE DRAWINGS
Fig. 1 represents in a purely schematic manner the whole equipment
comprising rollers F and F' system for controlling inlet and outlet
velocity of the yarns D, heating plates B and B', a hot water wash
device L, and diathermal oil heating system E.
Fig. 2 represents in detail the heating plates B and B' placed in a
containment chamber C provided with steam inlet (through regulation
group R) and residual non utilized steam discharge A.
Fig. 3 represents a section of the heating plate according to a
vertical plane parallel to the yarn run.
Fig. 4 shows the path of the diathermal oil coil.
DRTATT.~n DESCRIPTION OF THE lNVh~llON
The yarn fed at the heating and stretch equipment of Figure 1 is
previously washed (device L) with hot water to remove the residual
spinning oil, resulting detrimental to sizing operation, successive to
stretching, and to prepare it to interlacing operation. The yarn is
passed between the heating plates B, B' without coming into contact
with them. The whole yarns beam (warp chain) is uniformly collided with
numerous laminar jets of steam coming from the splits N of the heating
plates B, B' as shown in Figure 3, wherein V indicates the steam supply
chamber and G the closing plates fastened with screws H and placed next
each other thus forming a small interstice in the order of 0.3 mm in

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order to form splits N parallel to the plates and transversal to the
yarns direction. The equipment also encompasses conventional device R
(Figure 2) for inlet steam pressure reduction and flow regulation.
The yarn is thus very quickly brought to the desired stretch
temperature.
The heating regulation is carried out by varying the fed steam flow and
the distance of the plates from the yarns beam : the distance between
the lower and the upper plate, in the order of 7 cm, can be regulated.
A further possibility to regulate the heating is given by the fact that
the steam supply chamber is provided inwardly with a coil M (Figures 3
and 4) in which diathermal oil flows, whose temperature is strictly
controlled.
By means of the supplemental heat provided by the above coil,
dispersion heat losses can be counterbalanced avoiding steam
con~n~ation in the steam chamber, moreover it is possible to regulate,
within restricted limits, the steam jet temperature coming out from
the splits.
The method according to the present invention has the advantage
consisting in a very quick heating of the yarn and a high heating
uniformity for all the yarns beam also in the case of warp chain,
having a large number of yarns.
These advantages are due, besides to the use of steam as heating fluid,
also to the steam use conditions in the form of numerous laminar jets,
having specific disposition and direction.
As above said a further regulation possibility is given by the

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supplemental heating of the steam rh~ r by means of diathermal oil
flowing through the coil inside the steam supply chamber.

Representative Drawing