Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF TEIE INVENTION
Field of the Invention:
The present inven-tion relates -to a method of manufactur-
ing slide fastener coupling elements successively from a metal
.j '.
I strip by colning and blanking.
Il Prior Art:
A variety of methods have been known to produce so-called
double-acting or ~wo-way coupling elements Eor side fasteners.
U.S. patent 2,622,295, issued December 23, 1952 discloses one
~orm of such double-acting coupling elements, whlch are manufac-
tur~d by roll-coining a wire stock i~ a manner as described in
U.S. patent 2,201,068, issued May 14, 1940. The rolling method
is disadvantageous in that the xolled wire stock must be reversed
in its direction of feed when severed and attached to the beaded
edge of a stringer tape, resulting in an increased expenditure
of time and labor.
~¦ U.S. patent 3,136,046, issued June 9, 1964 shows a metal
! strip having longitudinal medial raised portions which are
deformed by a punch press into longitudinally spaced coupling
pro~ections. With this arrangemenk, the projections thus produced
are o~ a relatively low pro~ile owing to their height being
virtually dependent on the height of the medial lands, and hence
the metal strip must be considerably thick for the projections
to have a required projection height.
SUMM~RY OF THE INVENTION
According to the present inventlon, a metal strip includ~
ln~ a web havin~ longltudinal medial lands on l~s both ~ides is
~tamped to ~eEoxm a pox~lon o~ each o~ the medial lands ~ubstan-
tially in~o ~ txansver~e projec~ion and a palr of longitudinal
-~ee~ one on ~ac~ ~ide o~ the proj~c~ion, and ~imultaneously
a pocket por~ion surrounded by and a base cxtending arolmd ~he
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projection and teeth are stc~nped so as to be thinner than theweb with material from the pocket portion and base flowing into
the projection and teeth. Accordingly, the projection and
teeth are of a rela~ively high profile regardless of a reduced
thickness of ~he web. Tape clamping legs of coupling elements
are then blanked out of the web.
1~ It is an object of ~he present invention to provide a
¦I method of manufacturing double-acting slide fastener coupling
elements having sufficiently high coupling projections from
1, a relatively thin metal strip.
¦~ Another object of the present invention is to provide
a method of manufacturing such coupling elements having relative-
I ly thin tape-clamping legs for smooth movement of a slider
thereon.
1~ Still another object of the present invention i5 to pro-
vide a material-saving method of manufacturing double-acting
slide fastener coupling elements.
j The above and other objects, features and advantages of
the present invention will become apparent from the following
¦description whe~ taken in conjunction with the accompanying
~drawings which illustrate a pre~erred embodiment by way o~
¦lexample.
il BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of a metal strip as it is coined
and punched before being severed into individual coupling
~le~t~;
FXG. 2 is a plan vieW o~ a ccupling elemqnt hqf~re being
~at-tac~ed to a beaded tape edge;
~¦ FIG. 3 i~ a cxo~s-~ectional view taken al~ny lin~ III-III
Oe FIG. 1~
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FIG. 4 is an enlarged fragmentary plan view of a portion
of the metal strip shown in FIG. l;
FIG. 5 is an enlarged perspective view of a coupling
element produced in accordance with the present invention;
FIG. 6 is an enlarged fragmentary plan ~iew of a pair
of slide fastener stringers having coupling elements as
illustrated in FIG. 5;
l FIGS. 7 and 8 are enlarged cross-sectional views of the
I metal strip before being stamped ~etween dies, the views showing !
l dif~erent die cross-sections; and
I FIGS. 9 and 10 are enlarged cross-sectional ~iews of the
metal strip as it is being stamped between the dies, the views
showin~ dif~erent die cross-sections.
DETAILED DESCRIPTION
, As shown in FIGS. 1 and 3, a coupling element blank is
in the foxm of a metal strip 12 comprising an elongate web 13
i and a pair of longitudinal medial lands 14,15 on both sides
thereof, each medial land being of a trapezoidal cross section.
¦ The metal strip 12 is successively stamped or coined so as to be
provided with a series of coupling heads 16 (FIG. 1).
~ In FIGS. 4 and 5, each coupling head 16 includes on each
¦ side thereof a transverse projection 17 located centrally o~ the
strip 12 and a pair o~ longitudinal teeth 18,19 disposed one on
each side o~ and contiguous to the projection 17, the projection
17 being higher than the teeth 18,19 as best illustrated in FIG. ~,
6. ~he projection 17 and teeth 18,19 ara ~ormed substantially
by de~orming ~he medial lands 1~,15 duxin~ ~tamping. The pro~ec-
tlon 17 and the teeth la,19 jointly de~ine ~ pocket 20. A
hor~eshoe-~haped ba~e 21 extends around the proiec~i4n 17 and ~he
~eth 1~,19. A pox~i~n ~ ~he s~rip 12 whlch inalud~s ~he
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pocket 20 and the base 21 that extend all the way around the
projection 17 and the teeth 18,19 has a -thickness _ smaller than
the thickness H of the web 13. During stamping, material ~lows
~rom the pocket 20 and base 21 into the projection 17 and teeth
~, 18,19, whereby -the projection 17 and teeth 18,19 have their
required projection heights.
Then, the marginal edges of the web 13 are successively
cut out to form notches 23 that serve to define outer profiles
;lof clamping legs 24,25, as shown in FIG. 1. Thereafter, the
metal strip 12 thus coined is severed by punching in-to an
~individual coupling element 28 (FIG. 2) having a concave edge
i 26 defining the inner pro~ile of the clamping legs 24,25 and
a convex edge 27 defining the outer profile of the coupling
head 16. The thickness of the clamping legs 24,25 remains the
same as the thickness H of the web 13.
The coupling element 28 is attached to a stringer tape
29 by clinching the legs 24,25 around a beaded edge 30 of the
stringer tape 29 (FIGS. 2 and 6).
FIGS. 7 and 8 show a punch press including a pair of
upper and lower dies 32,33 for stamping or coining the metal
strip 12 longitudinally fed therebetween. Each o~ the
dies 32,33 includes a central xecess 34 and a pair of spaced
side cavities 35,36 extending respectively transversely
and longitudinally o~ the direction o~ ~ePd o~ the mekal
s~rip 12, the central recesg 34 beirlg deeper than the (3ide
cavities 35,36. The slde aavities 35l36 are located one
on each side o~ the central recess 34 in communication
~herewith. A central pre~ing sur~ace 37 lies between the
jspaced side cavi~ies 35,36 and adjacent to the central Lecess
34. ~ pressing sur~ace 38 which is horseshoe-shaped though nQt
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showrl eY.tends arouncl the recess 34 and side cavities 35,36 in
surroundiny rela-tlon to the central pressing surface 37. The
pressing surfaces 37,38 are raised with respect to a surface 39
, of each die 32,33 so that the pressing surfaces 37,38 on the
.I dies 32,33 coact wi-th each other to press the metal strip 12.
More speci~ically, the metal strip 12 is first advanced
longitudinally between the upper and lower dies 32,33 with the
imedial lands 14,15 being held in vertica:L registry with the
¦upper and lower recesses 34,34, respectively. Upon stoppage
~o~ the metal strip 12, the upper and lower dies 32,33 move
relatively toward each other to press the metal strip 12
I therebetween. ~rhe medial lands 14,15 starts being squeezed into
the upper and lower recesses 34,34, respectively. Since the
side cavities 35,36 are located partly above and below the
medial lands 14,15 and communicate with the recesses 34,34,
. a portion o the medial lands 14,15 is also squeezed into the
cavities 35,36. The central pressing surfaces 37,37 press an
adjacent portion of the medial lands 14,15, which flows into
the recesses 34,34 and the side cavities 35,36 (FIG. 10). As
the upper and lower dies 32,33 are further pressed toward each
other,the central pressing surfaces 37,37 and the horseshoe-shaped
pressing surfaces 38,38 are thrust into the web 13 to ~orm the
, thinned pockets 20,20 and the horseshoe-shaped bases 21,21 in
both s.ides o~ the strip 12. At khis time, material ~lows ~ro~
the pockets 2~,~0 and the horseshoe~shaped bases ~1,21 into the
.reces~s 34,3~ and the side cavities 35,36, whenupon the projec-
tion~ 17rl7 and the teeth 18,19 are completely ~ormed. Since
a substantial amount o~ metal ~low is s~ueezed into the recesse.s
34,34 and cavities 35,36, the web 13 d~es not expand widthwise
by bein~ pressed between the upper and lower dies 32,33.
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Accord-ngly, the thickness of the clamping legs 24,25 remains
the same as the thickness ~ of the web 13.
As best illustrated in FIG. 6, the projections 17 and
the teeth 18,19 of each of the coupling elements 28 thus pro-
duced have a large projection height for secure and reliable
interdigitating engayement between couplin~ elements 28,28 on
opposed stringer tapes 29,29. Nonetheless, the clamping legs
24,25 have a minimum thickness such that they are securely
clamped on the beaded edge 30 and, at the same time, allow
smooth sliding movement of a slider thereon. As part of the
I material o~ the projections 17,17 and the teeth la,l9 is available
by thinning down ~he base 21, the medial lands 14,15 and hence
the web 13 need not originally be thick. Accordingly, material
! saving can be achieved in accordance with the method of the
l~pres~nt invention.
Although a certain preferred embodiment has been shown
and described in detail, it should be understood that changes
¦and modifications may be made therein without departing from
ths scope of the appended cLaims.
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