Note: Descriptions are shown in the official language in which they were submitted.
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~ ACKGROUND OF THE INVENTION
,eld of the Invention:
The present invention relates to a slide fastener
stringer having a longitudinal core cord extending through a
space defined through a row of coiled coupling elements and sewn
together with the latter to a stringer tape.
Prior Art:
There are two kinds of longitudinal core cords used in
mounting a row of coiled coupling elements stably in position on
a stringer tape. One of these comprises a plurality of spun
yarns twisted together. Such core cord is soft and flexible
e~ough to allow a sewing needle to penetrate smoothly
therethrough for sewing a row of coiled coupling elements to a
stringer tape, but it is irregular in diameter and likely to
produce lint. A resulting slide fastener stringer is
flexible. However, the coupling elements are li~ely to become
undulated or out of alignment in the longitudinal direction
thereof. The slide fastener stringer having such undulated
coupling elements is hard to pair with a companion stringer.
Another core cord includes a plurality of multifilament
yarns twisted together. The core cord has a substantially
uniform diameter and is free of lint. On the other hand, it is
relatively rigid and lacks stretchability. Such core cord
hinders a sewing needle from~penetrating smoothly therethrough
and contracts as it is sewn to a stringer tape, with the result
that a row of coupling elements lacks flexibility, and hence a
smooth coupling and uncoupling engagement thereof with a
corresponding row of coupling elements is difficult to achieve.
SUMMAR~ OF THE INVENTION
It is an object of the present invention to provide a
slide fastener stringer having a row of coiled coupling elements
sewn neatly onto a stringer tape. ~ ~
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Another object of the present invention is to provide a
slide fastener stringer having a core cord extending through a
row of coiled coupling elements for reliable attachment of the
same to a stringer tape, which core cord is soft and flexible,
free of lint, and substantially uniform in diameter.
According to the present invention, a slide fastener
stringer includes a longitudinal core cord extending through a
space defined through a row of coiled coupling elements and sewn
together with the latter to a stringer tape. The core cord has
at least one twisted thread having a plurality of textured
multifilament yarns twisted together. Each of the textured
multifilament yarns has an increased degree of bulkiness and
stretchability.
Many other advantages, features and additional objects
of the present invention will become manifest to those versed in
the art upon making reference to the detailed description and
the accompanying drawings in which a preferred embodiment
incorporating the principles of the present invention are shown
by way of illustrative example.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a fragmentary plan view of a slide fastener
stringer according to the present invention;
FIG. 2 is a longitudinal cross-sectional view taken
along line II-II of FIG. l;
FIG. 3 is a schematic transverse cross-sectional view
taken along line III-III of FIG. l;
FIG. 4 is a fragmentary plan view of a core cord of the
slide fastener stringer;
FIG. 5 is a schematic end elevational view of the core
cord; and
FIG. 6 is a schematic fragmentary plan view explaining
a problem associated with a conventional slide fastener stringer.
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DETAILED DESCRIPTION
As shown in FIG. 6, a conventional slide fastener
stringer F comprises a row of coiled coupling elements E sewn by
a row of sewing stitches S to a stringer tape T along a
longitudinal edge thereof. A longitudinal core cord C made of a
plurality of spun yarns twisted together extends through a space
defined through the coiled coupling elements E and is sewn
together with the latter to the stringer tape T. The co~pling
elements E are out of alignment or undulate by a distance d in
the longitudinal direction thereof due to the irregularity in
diameter of the core cord C. The slide fastener stringer F
having such undulated coupling elements E fails to provide
smooth closing and opening operation when it is paired with a
mating fastener stringer F'.
The present invention is described hereinbelow with
reference to FIGS. 1 through 5.
In FIGS. 1 to 3, a slide fastener comprises a pair of
slide fastener stringers 10, 10, each of which has a stringer
tape 11 and a row of coiled coupling elements 12 formed of
synthetic resin sewn by a row of sewing stitches 13 ~shown by
phantom lines for clarity) to the stringer tape 11 along a
longitudinal edge portion thereof. Each of the coupling
elements 12 comprises a coupling head 14 projecting transversely
beyond the longitudinal edge portion of the stringer tape 11,
and a pair of upper and lower legs 15, 16 (FIGS. 2 and 3)
extending from the coupling head 14 in a common direction and
spaced from each other vertically in a direction substantially
perpendicular to the general plane of the stringer tape 11. .The
upper and lower legs 15, 16 are blended into and are
interconnected by a heel portion 17 located remotely from the
coupling head 14. ~he lower legs 16 of the coupling elements 12
are mounted on the longitudinal edge portion of the stringer
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~ape 11. The coiled coupling elements 12 have a space or tunnel
18 (FIGS. 2 and 3) defined jointly by the coupling heads 14, the
upper and lower legs 15, 16 and the heel portions 17 and
extending longitudinally therethrough. A longitudinal core cord
19 extends through the space 18 in the coupling elements 12
adjacent to the heel portions 17 of the latter. The se~ing
stitches 13 pass through the core cord 19 at the spaces between
adjacent coupling elements 12 to secure the coupling elements 12
to the stringer tape 11.
As shown in FIGS. 4 and 5, the core cord 19 includes a
plurality of threads 20 twisted together. Each of the threads
20 has a plurality of textured multifilament yarns 21 twisted
together. To make the core cord 19, a thermoplastic
multifilament yarn is subjected to texturing processes in which
it is highly twisted, heat-set, and untwisted. The
multifilament yarn 21 thus textured has an increased degree of
bulkiness and stretchability. Then, a plurality of such
textured multifilament yarns 21 is twisted together to form a
twisted thread 20. Finally, a plurality of the twisted threads
20 is twisted together to form the core cord 19. The core cord
19 thus arranged has a number of small holes or pores 22 (FIG.
4) not only between the twisted threads 20 but also between the
twisted textured multifilament yarns 21. The pores 22 serve to
accommodate the contraction of the core cord 19 and to allow a
sewing needle (not shown) to penetrate the core cord 19 smoothly
when the coupling elements 12 are being sewn to the stringer
tape 11. Due to the use of the textured multifilament yarns 21
which are bulky, stretchable, uniform in diameter, and free of
lint, the core cord 19 is soft and flexible, has a substantially
uniform diameter, and is prevented from becoming frayed.
As shown in FIG. 2, the core cord 19 has a diameter R
larger than the distance r between the respective upper and
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lower legs 15, 16 of the coupling elements 12 so that it
includes alternating compressed and expanded longitudinal
portions 23, 24. The compressed portions 23 are located
between the upper and lower legs 15, 16 and the expanded
portions are located between adjacent coupling elements 12
such that the portions 23, 24 jointly embrace the upper and
lower legs 15, 16 at substantially a half of the full circum-
ference thereof and hence maintain the coupling elements 12
at a substantially uniform pitch. In FIG. 3, the core cord
19 is held in the space 18 out of contact with the coupling
head 14 of a mating stringer 10. The coupling elements 12
thus arranged provide a uniform meshing length which enables
opposite rows of coupling elements 12, 12 to engage and
disengage smoothly with each other.
Although various minor modifications may be suggested
by those versed in the art, it should be understood that we
wish to embody within the scope of the patent which may be
granted hereon, all such embodiments as reasonably and properly
come within the scope of our contribution to the art.
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