Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to slide fasteners, and
more particularly to a slide fastener stringer having a
continuous zigzag-shaped or meandering thermoplastic molde~
coupling element strip attached to a stringer tape along a
longitudinal edge thereof.
Prior art and the present invention will be described
with referen~e to the accompanying drawings in which:
FIG. 1 is a fragmentary plan view of a pair of
interèngaged slide fastener stringers, each embodying the
present invention;
FIG. 2 iS a cross-sectional view taken along line
II-II of FIG. l;
FIG. 3 is a fragmentary perspective view of a
continuous molded coupling element strip;
FIG. 4 is a cross-sectional view taken along line
IV-IV of FIg. 3;
FIG. 5 illustrates the manner in which the opposed
coupling element strips are bent in opposite edgewise
directions as they are being coupled by a slider;
FIGS. 6, 7, 8 and 9 are cross-sectional views taken
along lines VI-VI, ~II-VII, VIII-VIII and IX-IX,
respectively, of FIG. 5; and
FIGS. 10 and 11 illustrate a prior art problem.
Japanese Utility Model Laid-Open Publication
~Jikkaisho) 58-55513 diqcloses a slide fastener stringer in
which, as illustrated in FIGS. 10 and 11, a continuous
zigzag-shaped strip 51 of thermoplastic molded coupling
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elements 55 is attached to a stringer tape 52 along a
longitudinal edge thereof by sewn stitches 54. The
successive coupling elements 55 are interconnected by a
plurality of thermoplastic molded connecting portions 56
alternat21y disposed at opposite sides of the strip 53 and
extending one between each adjacent pair of the coupling
elements 55. The two adjacent legs (of adjacent coupling
elements 55) interconneted by each connecting portion 56
terminate in a combined foot which is chamfered at 56b,
thus having only a small contact area engageable with the
guide flange 64 of one corresponding wing 63a of the slider
63. With this limited contact area of the combined foot,
the uncoupled individual coupling elements which are about
to enter the Y-shaped guide channel 66 of the slider 63,
would tend to easily roll or turn facewise of the fastener
as the strip 33 is twisted, causing non-smooth closing
operation of the slide fastener. For the same reason, the
individual connecting portions 56 are less resistant to
wearing, making the individual coupling elements 55 and
thus the slide fastener less durable.
Further, because the individual connecting portion
has a uniform thickness equal to the thickness of the
adjacent coupling element leg portions and hence has
relatively high rigidity, the prior stringer is poor in
flexibility, also causing non-s oth coupling-and-
uncoupling operation of the ~lide fastener.
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It is therefore an object of the present invention to
provide a slide fastener 8tringer having a zigzag-shaped
thermoplastic molded coupling element strip which has not
only adequate flexibility but also good durability, thus
enabling smooth and sure coupling operation of the slide
fastener, at which time a row of coupling elements is bent
arcuately away from the coupling elements of a companion
stringer in conformity with the Y-shaped guide channel of a
slider without rolling of the uncoupled individual coupling
elements that are about to enter the slider.
Many other advantages, featur~s and additional
objects of the 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
invention is shown by way of i;Llustrative exmple.
According to the present invention, a continuous
meandering thermop:Lastic molded coupling element strip
comprises a succession of laterally sp~ced coupling
elements, each having a first leg and a second leg
extending from a head in a common transverse direc~ion. ~ plurality
of first and second connecting portions is disposed
alternately at opposite sides of the ~trip and extends one
between each adjacent pair of the coupling elements. The
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individual connecting portio~ is more slender than the adjacent
coupling element legs. ~he two adjacent legs inter-
connected by each connecting portion terminate in a combined
broad foot with opposite corners or ends substantially
~cute angled and thus not cnamfered.
FIGS. 1 and 2 illustrate a pair of coupled slide
fastener stringers 1, 1, each comprising a stringer tape 2
and a continuous zigzag-shaped molded coupling element
strip 3 attached to the tape 2 along an inner longitudinal
edge thereof by sewn threads 4, the strip 3 being folded on
itself along its longitudinal centerline.
The coupling element strip 3 is continuously produced
on a rotating die wheel (not shown) having an endless
zigzag-shaped peripheral cavity receptive of heated
thermoplastic synthetic resin, such as polyamid, delivered
from a fixed extrusion nozzle (not shown) and, before
having been bent into a U-shaped cross section (FIGS. 2, 3
and 4), it has a continuous flat zigzag-shaped structure.
The thus folded strip 3 includes a series of laterally
spaced coupling elements 5 interconnected by a plurality of
first and second solid connectlng portions 6, 7 alternately
disposed at opposite sides of the strip 3 and extending one
between each adjacent pair of the coupling elements 5.
Each coupling element 5 has a head 8 and a pair of first
and second legs 9, 10 extending from the head 8 in a common
direction and terminating in their respective feet 9a, lOa
(FIG. 4). Each first connecting portion 6 extends between
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an adjacent pair of the first legs 9, 9 and is disposed
close to tlle feet 9a, 9a thereof, and each second
connecting portion 7 extends between an adjacent pair of
the second legs 10, 10 and is disposed close to the feet
lOa, lOa thereof.
As best shown in FIGS. 2 and 4, the first and second
connecting portion 6, 7 are thinner or more slender than
the first and second legs 9, 10, and are disposed on the
respective inner sides of the first and second legs 9, 10
to provide a recess or bay 6', 7' (FIG. 3) between each
adjacent pair of the coupling elements 5, as viewed in an
edgewise direction of the stringer 1.
A pair of first and second connector theads 11, 12
extends transversely of the successive coupling elements 5
along the entire length of the strip 3 and is embedded in
the first and second legs 9, 10, respectively, of each
coupling element 5. Each of the first and second connector
threads 11, 12 is disposed close to and extends alongside a
respective one o:E the two series of the first and second
connecting portions 6, 7, being disposed close to the side
thereof which faces the coupling heads 8. As shown in
FIGS. 2, 3 and 4, the first and second connactor thaads 11,
12 are disposed on the respective inner sides of the first
and second legs 9, 10.
The leg 9, 10 of each coupling element 5 has a
generally trapezoidal shape, as viewed in plan (FIG. 3),
having a width increasing progressively from the coupling
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head 8 toward the foot 9a, lOa. Thus the foot 9a, lOa of
each leg 9, 10 has a sufficiently large contact area
engageable with a respective one of a pair of flaring guide
flanges 14, 14 of a slider 13 when the opposed stringers 1,
1 of a slide fastener are being coupled or uncoupled. Each
coupling element 5 can be prevented from turning or rolling
facewise of the slide fastener stringer 1 when a thrusting
force is exerted on the slide fastener in a facewise
direction thereof (FIGS. 10 and 11), partly because of such
large contact area of the foot 9a, lOa and parlly because
outer corners or opposite ends 9b, 9b; lOb, lOb of a
combined broad foot extending between the two adjacent
interconnected legs 9, 9 ; 10, 10, respectively, are not
chamfered, having no sloping or round surfaces. This broad
foot makes the corresponding coupling elements 5 less
abrasive, guaranteeing improved durability of the coupling
element strip 3 and thus of the slide fastener stringer 1.
Further, partly because the connecting portions 6, 7
are more slender than the legs 9, 10 and partly because the
connector threads 11, 12 are disposed close to and extend
alongside the respective series of connecting portions 6,
7, the coupling element strip 3 has not only adequate
flexibility but also good durability; the solid slender
connecting portions 6, 7 and the connecting threads 11, 12
close thereto coact to produce such advantageous
characteristics. This construction enables the coupling
element strip 3 to be bent arcuately away from the
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corresponding strip 3 of a companion stringer 1 in
conformity with the curvature of the respective guide
flange 14 of the slider 13 when the opposed stringers 1, 1
of the slide fastener are being coupled or uncoupled, as
shown in FIGS. 5. At that time the connector threads 11 t
12, which are disposed close to the respective sides of the
connecting portions 6, 7 which sides are facing the heads
8, serve to prevent the slender connecting portions 6, 7
from being exc~ssively bent and thus from ~eing broken or
otherwise damaged.
Another advantage o~ the fastener stringer 1 is that
since the first and second slender connecting portion 6, 7
are disposed on the respective inner sides of the first and
second legs 9, 10 to provide the bay 6', 7' (FIG. 3)
between each adjacent pair of the coupling elements 5, the
stringer 1 and thus the coupling element stringer 1. At
that time, the first tupper) connecting portions 6 are bent
so as to expand the upper bays 6 and, on the contrary, the
second (lower) connecting portion 7 are bent so as to
shrink the lower bays 7'. At the same time, the
inter-coupling-element portions of the first (upper)
connector thread 11 are expanded and, on the contrary, the
inter-coupling-element portions of the second (lower)
connector thread 12 are compressed. Accordingly, the
connector threads 11, 12 facilitate expansion of the
connecting portions 6, 7, thus preventing the latter from
being broken. The connecting portions 6, 7 in turn protect
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the connector threads 11, 12 from sudden undue stress,
thus preventing the connector threads 11, 12 either from
being broken or from being removed from the coupling
element legs 9, 10. With this arrangement, smooth and
sure coupling-and-uncoupling of the coupling elements 5
is guaranteed for a long time.
Although various minor modifications may be suggested
by those versed in the art, it should be understood that I
wish to embody within the scope of any patent which
might issue hereon, all such embodiments as reasonably and
properly come within the scope of my contribution to the
art.
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