U.S. patent application number 09/965177 was filed with the patent office on 2002-04-04 for method and an apparatus for strengthening yarns.
Invention is credited to Fehrer, Monika.
Application Number | 20020038499 09/965177 |
Document ID | / |
Family ID | 3688555 |
Filed Date | 2002-04-04 |
United States Patent
Application |
20020038499 |
Kind Code |
A1 |
Fehrer, Monika |
April 4, 2002 |
Method and an apparatus for strengthening yarns
Abstract
A method and an apparatus for strengthening a yarn (6) is
described which is provided with fibers at least in a sheath zone
enclosing a core zone. In order to provide advantageous process
conditions it is proposed that fibers are needled from the sheath
zone through the core zone along the yarn (6).
Inventors: |
Fehrer, Monika; (Leonding,
AT) |
Correspondence
Address: |
Kurt Kelman
KOLLARD & ROE, P.C.
1077 Northern Boulevard
Roslyn
NY
11576
US
|
Family ID: |
3688555 |
Appl. No.: |
09/965177 |
Filed: |
September 27, 2001 |
Current U.S.
Class: |
28/219 ; 28/107;
28/247 |
Current CPC
Class: |
D02G 3/36 20130101; D04H
18/02 20130101 |
Class at
Publication: |
28/219 ; 28/107;
28/247 |
International
Class: |
D02J 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 29, 2000 |
AT |
A 1651/2000 |
Claims
1. A method for strengthening a yarn which is provided with fibers
at least in a sheath region enclosing a core zone, with fibers from
the sheath zone being needled through the core zone along the
yarn.
2. A method according to claim 1, wherein fibers from at least one
fiber sheath wound about a yarn core are needled through the yarn
core.
3. An apparatus for performing the method according to claim 1 or 2
with at least one needle board which is reciprocatingly drivable in
the needle-penetration direction, with the stitch base (1) being
provided with at least one guide groove (5) for the yarn (6)
extending in the direction of passage and the needles (4) of the
needle board (2) penetrating the guide groove (5).
4. An apparatus according to claim 3, wherein the stitch base (1)
comprises several parallel guide grooves (5) for one yarn (6)
each.
5. An apparatus according to claim 3 or 4, wherein the guide groove
(5) or the guide grooves (5) are provided upstream and/or
downstream with guide eyes (9) for the yarn (6) or yarns (6).
6. An apparatus according to one of the claims 3 to 5, wherein the
stitch base (1) extends at least on the inlet and outlet side in a
convexly curved manner in the direction of the guide groove (5) or
guide grooves (5).
Description
FIELD OF THE INVENTION
[0001] The invention relates to a method for strengthening a yarn
which is provided with fibers at least in a sheath zone enclosing
the core zone.
DESCRIPTION OF THE PRIOR ART
[0002] The strength of fibers which are provided with a sheath zone
made of fibers which enclose the core zone depends, among other
things, on the anchoring of the enveloping fibers in the yarn core.
If the yarn is obtained by a twisting of a fiber slubbing, the
enveloping fibers are usually well incorporated in the fiber
structure as a result of the twisting of the stubbing. If a yarn
core is wrapped around with fibers, the connection between the
enveloping fibers and the yarn core remains limited to the friction
between the enveloping fibers and the surface of the yarn core,
thus giving rise to the likelihood that in the case of a respective
load, the fiber sheath may be displaced against the yarn core in
the longitudinal direction of the yarn. This can lead to a
dissolution of the yarn structure, especially whenever the
enveloping fibers are provided with a relatively loose connection
among one another. The yarn strength also suffers by stresses
placed on the yarn which are accompanied by an untwisting of the
twist of the yarn.
SUMMARY OF THE INVENTION
[0003] The invention is thus based on the object of mechanically
strengthening a yarn of the kind mentioned above with the help of a
comparably simple method, so that not only higher strength
requirements can be met, but also the likelihood of an untwisting
of the twist of the yarn can be avoided.
[0004] The invention achieves the above object in such a way that
fibers are needled from the sheath zone through the core zone along
the yarn.
[0005] Since as a result of this measure the enveloping fibers are
anchored additionally in the core zone of the yarn, the mutual
connection between the enveloping fibers and the core zone of the
yarn is strengthened considerably, which has a direct influence on
the yarn strength since the needling of enveloping fibers through
the core zone of the yarn produces a fixing of the twist of the
yarn. This means that yarns with a predetermined degree of twisting
are provided with better strength properties or that a lower twist
of the yarn is required for a required yarn strength. This applies
to yarns from twisted fiber slubbings, but especially to yarns with
a fiber sheath wound about a yarn core, because in this case a
mutual connection, which otherwise would not be possible, can be
achieved between the enveloping fibers and the yarn core. An
additional aspect is that the condensation of the fiber structure
which is caused by the needling leads to a certain compensation of
thick and thin places, which is disclosed by an even yarn
quality.
[0006] In order to perform the needling of yarns, it is possible to
assume a conventional apparatus with a drivable needle board
reciprocating in the direction of the needle penetration and a
stitch base opposite of the needle board. It is merely necessary to
ensure that the needles are disposed behind one another in the
traveling direction of the yarn and the yarn cannot escape the
penetrating needles to the side. For this reason the stitch base is
provided with at least one guide groove for the yarn which extends
in the direction of yarn passage, with the needles of the needle
board penetrating into the guide groove. The side walls of the
guide groove, which can be formed by a groove in the stitch base or
guide rules provided on the stitch base, prevent a lateral
migration of the yarn to be needled, so that the needles need
merely be disposed in one row on the needle board in the direction
of the guide groove in order to needle the yarn pulled through the
guide groove in such a way that the enveloping fibers are pulled
through the core zone of the yarn. The enveloping fibers extending
through the core zone to the opposite sheath zone substantially
prevent any relative movements between the sheath and core zones,
so that a yarn needled in this manner is provided not only with
favorable strength values, but is also advantageously protected
against untwisting.
[0007] Since the desired unity of the fiber structure between the
sheath and the core zones of a yarn requires a comparably low
stitching density, the passage speed of the yarns to be needled can
be kept relatively high in the apparatuses provided for such
purposes, which allows a favorable adaptation to the working speed
of downstream yarn treatment. In order to enable the simultaneous
needling of several yarns, the stitch base can be provided with
several parallel guide grooves for one yarn each. The smooth entry
and exit of the yarns into and out of the guide grooves can be
enforced in a simple way by guide eyes for the yarns.
[0008] In order to obtain a lateral guidance within the guide
groove which is advantageous for the needling of a yarn, the
clearance of the guide groove can decrease in the direction of
needle penetration so that the yarn, depending on its respective
thickness, rests on the two side walls of the guide groove when the
yarn to be needled is pulled into the guide groove. For this
purpose the stitch base can be provided with a convexly arched
arrangement at least in the entrance and exit zones, so that in the
case of a tensile stress on the yarn to be needled, a force
component is obtained which presses the yarn against the stitch
base in the guide groove. If the curvature extends over the entire
length of the guide groove, this effect is also extended to the
needling zone with the advantage that the needle-penetration angle
of the needles into the yarn changes along the guide groove, which
influences the strength properties accordingly. This effect of the
curvature of the stitch base is naturally not dependent on any
special arrangement of the cross section of the guide groove which
in the case of low requirements placed on the lateral guidance of
the yarn can also have a rectangular cross section.
[0009] Although a convex stitch base causes a force component which
is perpendicular to the stitch base in the case of a respective
tensile load of the yarn which presses the yarn against the stitch
base, the provision of a stripper between the stitch base and the
needle board is recommended because in this way it is possible to
achieve a substantially calmed yarn guidance with a simultaneously
lower yarn tension.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The method in accordance with the invention is now explained
in closer detail by reference to the enclosed drawing, wherein:
[0011] FIG. 1 shows an apparatus in accordance with the invention
for strengthening a yarn in a simplified, partly sectional side
view;
[0012] FIG. 2 shows a sectional view along line II-II of FIG. 1 on
an enlarged scale;
[0013] FIG. 3 shows an embodiment of an apparatus in accordance
with the invention in a representation corresponding to FIG. 1;
[0014] FIG. 4 shows on an enlarged scale a schematic longitudinal
sectional view through a yarn which is strengthened according to
FIG. 1, and
[0015] FIG. 5 shows a schematic longitudinal sectional view through
a yarn strengthened according to FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] The apparatus according to FIG. 1 consists substantially of
a stitch base 1 and a needle board 2 which is opposite of stitch
base 1 and is inserted in a conventional manner in a needle beam 3.
The needle beam 3 is driven reciprocatingly by way of an eccentric
drive in the needle-penetration direction of needles 4. In contrast
to conventional stitch bases, the stitch base 1 in accordance with
the invention is associated with parallel guide grooves 5 for the
yarns 6 to be needled which are held under tensile load between a
roller feed 7 and a roller draw-off 8. Additional guide eyes 9 can
be provided for the purpose of improved guidance of the yarns
6.
[0017] Although the guide grooves 5 are arranged in the form of
guide channels in the stitch base 1, this arrangement is in no way
mandatory. The guide grooves 5 could also be formed by guide rules
on the stitch base 1, since the lateral guidance of the yarns 6 is
concerned in particular. The channels of the guide grooves 5 are
rounded off towards the groove base according to FIG. 2, which
leads to an advantageous lateral guidance for the yarns 6, which
are pulled into the guide grooves because the stitch base 1 is
provided on the inlet and outlet side with a convex curvature in
the direction of passage of yarns 6, so that force components are
obtained as a result of the tensile load of yarns 6, which force
components press against the stitch base 1. Said force components
which occur in the curvature zone are not sufficient, however, in
order to allow the omission of a stripper 10 which is disposed
between the stitch base 1 and the needle board 2.
[0018] The embodiment according to FIG. 3 differs from the one
according to FIG. 1 merely by the arrangement of the stitch base 1
which is continuously curved in a convex manner from the inlet to
the outlet side, so that force components which are perpendicular
to the stitch base 1 are obtained over the entire guide length of
the guide grooves 5, which force components press the yarns 6
against the stitch base 1. A stripper 10 is used nevertheless in
order to ensure a calmed yarn guidance which is advantageous for
the needling process.
[0019] The embodiments according to FIGS. 1 and 3 differ not only
with respect to the forces acting upon the yarns 6, but
particularly by the type of needling as is illustrated by the FIGS.
4 and 5 which each show a yarn 6 with a yarn core 11 and a fiber
sheath 12 which can consist of enveloping fibers which are wound
about the fiber core 11.
[0020] The yarn core 11 and the fiber sheath 12 can also be formed
by core and sheath zones of a fiber strand twisted into a yarn.
Since according to FIG. 1 the needles 4 of the needle board 2
penetrate the yarns 6 perpendicular to the stitch base 1,
enveloping fibers are needled substantially perpendicular to the
yarn axis through the yarn core 11 according to FIG. 4, as is
illustrated by the indicated fiber bridges 13. Said fiber bridges
13 connect the fiber sheath 12 with the yarn core 11 and
additionally hold the twist of the yarn 6, which causes the desired
yarn strengthening.
[0021] According to FIG. 3, the needles 4 are made to penetrate
under different needle-penetration angles the yarns 6 which are
guided along the convex stitch base 1, which leads to fiber bridges
13 which are inclined differently with respect to the longitudinal
yarn axis, as is schematically indicated in FIG. 5 in a purely
schematic way. The differently inclined fiber bridges 13 lead to a
different interfelting between enveloping fibers and yarn core in
comparison with FIG. 4, so that an influence on the yarn
strengthening can be made through the arrangement of the curvature
of the stitch base 1.
[0022] Although the needles 4 penetrate the yarns 6 substantially
in a common axial plane when the needles 4 are not disposed in a
mutually slightly offset way, the fiber bridges 13 are usually not
disposed in a common axial plane because a twist of the yarn during
the passage through the guide grooves cannot be prevented due to
the tensile load on the yarns 6, so that needle penetrations are
obtained which are distributed over the circumference of the yarn
which is advantageous for an even strengthening of the yarns 6.
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