Note: Descriptions are shown in the official language in which they were submitted.
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PLASTIC FASTENERS, NEEDLES FOR DISPENSING AND
METHOD OF MANUFACTURE
BACKGROUND OF THE INVENTION
The present invention relates to the dispensing of plastic fasteners of the
type
that are used, for example, to attach tags to articles of commerce.
Plastic fasteners of the type comprising an elongated flexible filament having
a first cross-bar at one end and a second cross-bar (or other enlargement,
such as
a paddle or a knob) at the opposite end are well-known and have been widely
used
in a variety of applications, such as in the attachment of merchandise tags to
articles
of commerce, in the attachment of buttons to garments, in the lasting of
shoes, and
in various packaging applications. Typically, such plastic fasteners are
mass-produced by molding processes into either one of two different types of
assemblies. One such assembly, an example of which is disclosed in U.S. Patent
No. 3,103,666, inventor Bone, issued September 17, 1963, is a clip-type
assembly,
said clip comprising a plurality of fasteners, each such fastener comprising a
flexible
filament having a first cross-bar at one end thereof and a paddle or second
cross-bar
at the opposite end thereof. The fasteners are arranged in a spaced, side-by-
side
orientation, with the respective first cross-bars parallel to one another and
the
respective paddles or second cross-bars parallel to one another, each of the
first
cross-bars being joined to a common, orthogonally-disposed runner bar by a
severable connector. Adjacent second cross-bars or paddles also may be
interconnected by severable connectors extending therebetween.
The aforementioned fastener clip is typically made by injection molding.
Several commercial embodiments of the above-described fastener clip have been
sold by the present assignee, Avery Dennison Corporation, as DENNISON
SWIFTACH fastener clips.
A second type of fastener assembly, an example of which is disclosed in U.S.
Patent No. 4,533,076, inventor Bourque, issued August 6, 1985,
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is known as continuously connected fastener stock. In one type of continuously
connected stock, the fasteners comprise a flexible filament having a cross-bar
at one
end thereof and a paddle (or second cross-bar) at the opposite end thereof,
the
respective cross-bars and paddles of successive fasteners being arranged
end-to-end and being joined together by severable connectors. In another type
of
continuously connected fastener stock, the fastener stock is formed from two
elongated and continuous side members coupled together by a plurality of
cross-links equidistantly-spaced apart by a distance of 0.25 inch. Individual
fasteners
having an H-shape, often referred to as "plastic staples," are dispensed from
the
fastener stock by cutting the side members at appropriate points between
cross-links, thereby yielding individual fasteners having cross-bars of 0.25
inch in
length.
Continuously connected fastener stock is typically made by a rotary extrusion
process of the type disclosed in U.S. Patent No. 4,462,784, inventor Russell,
which
issued July 31, 1984. Said rotary extrusion process typically involves the use
of a
rotating molding wheel whose periphery is provided with molding cavities that
are
complementary in shape to the desired fastener stock. To form fasteners,
plastic is
extruded into the cavities of the molding wheel, and a knife in substantially
elliptical
contact with the wheel is used to skive the molded plastic from the molding
wheel.
Following molding, the filament portions of the fasteners are typically
stretched.
One consequence of the rotary extrusion process described above,
particularly the skiving step thereof, is that the first cross-bar, the
filament, and the
second cross-bar (or paddle) are flat on one side thereof, with the flattened
sides of
the first cross-bar, the filament and the second cross-bar all lying in the
same plane
(see e.g., Fig. 1 B of U.S. Patent No. 4,462,784). The opposite sides of the
first-cross
bar, the filament, and the second cross-bar (or paddle) conform to the shapes
of the
molding cavities and are typically not flat. In the case of the first cross-
bar, its
opposite side is curved, thereby resulting in a cross-bar whose transverse
cross-section has a shape resembling a semicircle or semi-ellipse.
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Tools (often referred to as "tagging guns" or "fastener attaching tools") for
dispensing individual fasteners from continuously connected fastener stock
above
are known, examples of such tools being disclosed in the following U.S.
patents: U.S.
Patent No. 4,039,078, inventor Bone, which issued August 2, 1977; U.S. Patent
No.
5,433,366, inventors Deschenes et al., which issued July 18, 1995; U.S. Patent
No.
4,121,487, inventor Bone, which issued October 24, 1978; U.S. Patent No.
5,320,269, inventors Deschenes et al., which issued June 14,1994; U.S. Patent
No.
4,955,475, inventors McCarthy et al., which issued September 11, 1990; U.S.
Patent
No. 4,456,161, inventor Russell, which issued June 26, 1984; U.S. Patent No.
5,024,365, inventor Bourque, which issued June 18, 1991; and U.S. Patent No.
4,998,661, inventors Deschenes et al., which issued March 12, 1991.
Such tools typically comprise a needle, the needle typically including a stem
portion. The stem portion typically is generally cylindrical in shape and has
a
longitudinally-extending, cylindrically-shaped bore adapted to receive the
first
cross-bar of a fastener. In addition, said stem portion also typically has a
longitudinally-extending slot adapted to permit the filament portion of a
fastener to
extend therethrough while the first cross-bar of the fastener is disposed in
the
longitudinal bore of the stem portion. The stem portion also typically has a
tip
adapted for insertion into a desired article of commerce. The needle also may
include a base portion, said base portion being attached to the rear of the
stem
portion and being adapted to be removably received in the tool. The stem
portion and
the base portion may be a unitary structure or, as is more often the case, the
base
portion is insert-molded onto the rear end of the stem portion.
Such tools also typically comprise an ejector rod for ejecting a first cross-
bar
from the needle and into the article of commerce and may also include a knife
or
similar severing means for cutting the severable connector between the first
cross-bar being dispensed and its adjacent first cross-bar and feeding means
for
advancing the assembly of fasteners in the tool so as to align the forwardmost
first
cross-bar with the needle.
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One problem that has been noted by the present inventor with respect to the
dispensing of continuously connected fastener stock of the type described
above
using needles of the type described above is that, whereas the longitudinal
bore and
the longitudinal slot together have a symmetric transverse cross-sectional
shape
resembling an inverse lollipop (the longitudinal bore being circular in
transverse
cross-section, the longitudinal slot being rectangular in transverse cross-
section and
bisecting said longitudinal bore at the top thereof), the first cross-bar and
the filament
together have a "d"-shaped cross-section. As a result, a considerable portion
of the
transverse cross-section of the longitudinal bore is not occupied by any of
the first
cross-bar. Because the needle has a circular transverse cross-sectional shape,
the
effect of the bore being larger in cross-sectional shape than the fastener is
that the
needle has an outer width or diameter that is larger than that required by the
fastener.
Consequently, the needle creates an insertion hole in the article of commerce
that is
greater than that required by the fastener. Because it is desirable to
minimize the
size of the insertion hole (to minimize damage to the article), the outcome
described
above is undesirable.
In addition, because a considerable portion of the transverse cross-sectional
area of the bore is not occupied by the cross-bar, proper engagement of the
cross-
bar by the ejector rod and proper translational movement of the cross-bar
through the
length of the bore due to action of the ejector rod is not always achieved.
This results
in occasional malfunctioning of the tool.
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SUMMARY OF THE INVENTION
It is an object of the present invention to provide a new needle useful in the
dispensing of plastic fasteners of the type having a flexible filament and a
cross-bar
at a first end thereof.
It is another object of the present invention to provide a needle as described
above that overcomes at least some of the problems described herein with
respect
to existing needles.
According to one aspect of the invention, there is provided a needle useful in
dispensing plastic fasteners of the type comprising a filament having a cross-
bar at
a first end thereof, said needle comprising a stem portion, said stem portion
terminating in a tip at a front end thereof and being shaped to define a
longitudinally-
extending bore and a longitudinally-extending slot, said longitudinally-
extending bore
being dimensioned to receive said cross-bar, said longitudinally-extending
slot being
dimensioned to permit said filament to extend therethrough while said cross-
bar is
disposed within said longitudinally-extending bore, said longitudinally-
extending bore
having a first flat side, said longitudinally-extending slot having a first
flat side, said
first flat sides of said longitudinally-extending bore and said longitudinally-
extending
slot being coplanar.
As can readily be appreciated, the aforementioned needle is particularly well-
suited for use with plastic fasteners wherein each of the filament and the
cross-bar
has a flat side and wherein said flat sides are coplanar. Examples of such
fasteners
include fasteners formed as part of continuously connected fastener stock made
by
rotary extrusion, such as plastic staples. Where plastic staples of the type
comprising
a filament and a cross-bar that collectively have a "d"-shape are to be
dispensed
using the needle of the present invention, the longitudinally-extending bore
and the
longitudinally-extending slot of the stem portion of the needle preferably
collectively
have a complementary "d"-shaped transverse cross-section. Depending upon the
particular transverse cross-sectional shape of the cross-bar, the
longitudinally-
extending bore may have a generally semi-elliptical transverse cross-sectional
shape,
a generally rectangular transverse cross-sectional shape, a generally B-shaped
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transverse cross-sectional shape, a generally wedge-shaped transverse cross-
sectional shape or a like complementary transverse cross-sectional shape. The
stem
portion of the needle is preferably made of a steel or boron/nickel alloy and
is
preferably fabricated using electroforming. The needle preferably further
comprises
a base portion, said base portion being insert-molded onto a rear end of said
stem
portion.
According to another aspect of the invention, there is provided a needle
useful
in dispensing plastic fasteners of the type comprising a filament having a
cross-bar
at a first end thereof, said needle comprising a stem portion, said stem
portion
terminating at a front end thereof in a tip, said stem portion having a
longitudinally
extending slotted bore, said longitudinally extending slotted bore having a
flat side in
transverse cross-section.
The aforementioned needle may be used with a variety of plastic staples or
other plastic fasteners wherein each of the filament and the cross-bar has a
flat side
and wherein said flat sides are coplanar. An example of such a fastener is a
plastic
staple wherein the filament and the cross-bar have coplanar flat sides and
wherein
the cross-bar has a "B"-shape in transverse cross-section. The needle
preferably has
a slotted bore that is complementary in shape to the cross-bar and filament of
the
fastener.
The present invention is also directed to a novel method of fabricating a
needle
well-suited for use in the dispensing of plastic fasteners of the type
comprising a
filament having a cross-bar at a first end thereof. According to one aspect of
the
present invention, such a method comprises the steps of (a) fabricating an
unfinished
stem portion, said fabricating step comprising electroforming a metal onto a
master,
said master having a "d"-shaped transverse cross-section, and then removing
the
master from the electroformed metal; and (b) finishing said unfinished stem
portion,
said finishing step comprising machining the unfinished stem portion to yield
a
finished stem portion, said finished stem portion terminating in a tip at a
front end and
being shaped to define a longitudinally-extending bore and a longitudinally-
extending
slot, said longitudinally-extending bore being shaped to receive said cross-
bar, said
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longitudinally-extending slot being shaped to permit said filament to extend
therethrough while said cross-bar is disposed within said longitudinally-
extending
bore, said longitudinally-extending bore and said longitudinally-extending
slot
collectively having a "d"-shaped transverse cross-section.
As can readily be appreciated, the needle made by the aforementioned
method is particularly well-suited for use with plastic staples and other
plastic
fasteners wherein the filament and the cross-bar collectively have a generally
"d"-
shaped longitudinal cross-section (said cross-section being defined as being
along
the longitudinal axis of the filament and perpendicular to the longitudinal
axis of the
cross-bar). Preferably, the metal of the aforementioned method is a steel or
boron/nickel alloy, and said electroforming step preferably comprises
depositing
metal onto said master to a thickness of about 0.003-0.005 inch. The above-
described method preferably further comprises insert-molding a base portion
onto a
rear end of the finished stem portion.
It should be readily understood that, by selecting an appropriately shaped
master, one can adapt the above-described needle fabrication method to make a
needle particularly well-suited for use with a fastener whose filament and
cross-bar
have a coplanar flat side and whose cross-bar is "B"-shaped in transverse
cross-
section or to make a needle particularly well-suited for use with a fastener
whose
filament and cross-bar have a coplanar flat side and whose cross-bar is shaped
to
include one or more humps.
The present invention is also directed to a combination of a plastic fastener
and a needle. In one embodiment, said plastic fastener comprises a flexible
filament
having a cross-bar at a first end thereof, said cross-bar and said flexible
filament
collectively having a generally "d"-shaped longitudinal cross-section, said
needle
comprising a stem portion, said stem portion terminating in a tip at a front
end thereof
and being shaped to define a longitudinally-extending bore and a
longitudinally-
extending slot, said longitudinally-extending bore being dimensioned to
receive said
cross-bar, said longitudinally-extending slot being dimensioned to permit said
flexible
filament to extend therethrough while said cross-bar is disposed within said
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longitudinally-extending bore, said longitudinally-extending bore and said
longitudinally-extending slot collectively having a generally "d"-shaped
transverse
cross-section.
Preferably, the fastener cross-bar of the aforementioned combination is
generally semi-elliptical in transverse cross-sectional shape or is generally
rectangular in transverse cross-sectional shape. In a particularly preferred
embodiment, the cross-bar is generally rectangular in transverse cross-
sectional
shape and has a transverse cross-sectional height and a transverse cross-
sectional
width, said transverse cross-sectional height being greater than said
transverse
cross-sectional width and being parallel to the length of said flexible
filament.
In another embodiment, said plastic fastener comprises a flexible filament
having a cross-bar at a first end thereof, each of said cross-bar and said
flexible
filament having a flat side, said flat sides being coplanar, said cross-bar
being
generally "B"-shaped in transverse cross-section, said needle comprising a
stem
portion, said stem portion terminating in a tip at a front end thereof and
being shaped
to define a longitudinally-extending bore and a longitudinally-extending slot,
said
longitudinally-extending bore and said longitudinally-extending slot being
complementarily shaped to said plastic fastener.
The present invention is also directed to a novel plastic fastener. In one
embodiment, said plastic fastener comprises a flexible filament having a cross-
bar
at a first end thereof, said cross-bar and said flexible filament collectively
having a
generally "d"-shaped cross-section taken along the length of said flexible
filament and
transverse to the length of said cross-bar, said cross-bar having a
substantially
rectangular cross-sectional shape with its transverse length being larger than
its
transverse width.
In another embodiment, said plastic fastener comprises a flexible filament
having a cross-bar at a first end thereof, said cross-bar having a flat side
and being
generally "B"-shaped in transverse cross-section. Preferably, said flexible
filament
also has a flat side, said flat side of said flexible filament and said flat
side of said
cross-bar being coplanar.
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The present invention is also directed to a length of fastener stock, said
length
of fastener stock comprising a pair of continuous side members and a plurality
of
flexible cross-links interconnecting said continuous side members, said
flexible
cross-links being equidistantly-spaced apart at a pitch of about 0.18 inch.
The present invention is also directed to a length of fastener stock, said
length
of fastener stock comprising a plurality of fasteners, each of said fasteners
comprising a flexible filament and a cross-bar disposed at one end of said
flexible
filament, said cross-bar having a"B"- shape in transverse cross-section.
The present invention is further directed to a length of fastener stock, said
length of fastener stock comprising a pair of continuous side members and a
plurality
of flexible cross-links interconnecting said continuous side members, at least
one of
said continuous side members having a "B"-shape in transverse cross-section.
The present invention is still further directed to a length of fastener stock,
said
length of fastener stock comprising a pair of continuous side members and a
plurality
of fiexible cross-links interconnecting said continuous side members, at least
one of
said continuous side members being wedge-shaped in transverse cross-section.
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Additional objects, features, aspects and advantages of the present invention
will be set forth, in part, in the description which follows and, in part,
will be obvious
from the description or may be learned by practice of the invention. In the
description, reference is made to the accompanying drawings which form a part
thereof and in which is shown by way of illustration specific embodiments for
practicing the invention. These embodiments will be described in sufficient
detail to
enable those skilled in the art to practice the invention, and it is to be
understood that
other embodiments may be utilized and that structural changes may be made
without
departing from the scope of the invention. The following detailed description
is,
therefore, not to be taken in a limiting sense, and the scope of the present
invention
is best defined by the appended claims.
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BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are hereby incorporated into and
constitute a part of this specification, illustrate preferred embodiments of
the invention
and, together with the description, serve to explain the principles of the
invention. In
the drawings wherein like reference numerals represent like parts:
Fig. 1 is a perspective view of a length of conventional continuously
connected
fastener stock of the plastic staple variety;
Fig. 2 is an enlarged end view of an individual plastic staple obtained from
the
length of conventional continuously connected fastener stock of Fig. 1;
Fig. 3 is a top view of a conventional needle adapted for use in dispensing
fasteners, such as the plastic staple of Fig. 2;
Fig. 4 is a left side view of the needle shown in Fig. 3;
Fig. 5 is a front view of the stem portion of the needle shown in Fig. 3;
Fig. 6 is a transverse section view of the stem portion of the needle of Fig.
3,
the plastic staple of Fig. 2 being disposed therewithin;
Fig. 7 is a side view of a first embodiment of a needle constructed according
to the teachings of the present invention;
Fig. 8 is a transverse section view of the stem portion of the needle of Fig.
7,
a conventional plastic staple being shown disposed therein in phantom;
Fig. 9 is a transverse section view of a second embodiment of a stem portion
of a needle constructed according to the teachings of the present invention;
Fig. 10 is a fragmentary section view of a plastic fastener adapted for use in
a needle comprising the stem portion of Fig. 9;
Fig. 11 is a side view of a first embodiment of a length of plastic staple
stock
constructed according to the teachings of the present invention;
Fig. 12 is a perspective view of the length of plastic staple stock shown in
Fig.
11;
Fig. 13 is a fragmentary enlarged end view of an individual plastic staple
obtained from the length of plastic staple stock of Fig. 11;
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Fig. 14 is a fragmentary perspective view of a third embodiment of a needle
constructed according to the teachings of the present invention, said needle
being
adapted for use with the plastic staple of Fig. 13;
Fig. 15 is a transverse section view of the needle of Fig. 14, the plastic
staple
of Fig. 13 being shown disposed therein;
Fig. 16 is a fragmentary end view of a third embodiment of a plastic staple
constructed according to the teachings of the present invention;
Fig. 17 is a transverse section view of a fourth embodiment of a needle
constructed according to the teachings of the present invention, the plastic
staple of
Fig. 16 being shown disposed therein;
Fig. 18 is a fragmentary end view of a fourth embodiment of a plastic staple
constructed according to the teachings of the present invention;
Fig. 19 is a transverse section view of a fifth embodiment of a needle
constructed according to the teachings of the present invention, the plastic
staple of
Fig. 18 being shown disposed therein;
Fig. 20 is a fragmentary end view of a fifth embodiment of a plastic staple
constructed according to the teachings of the present invention;
Fig. 21 is a transverse section view of a sixth embodiment of a needle
constructed according to the teachings of the present invention, the plastic
staple of
Fig. 20 being shown disposed therein;
Fig. 22 is a fragmentary end view of a sixth embodiment of a plastic staple
constructed according to the teachings of the present invention; and
Fig. 23 is a transverse section view of a seventh embodiment of a needle
constructed according to the teachings of the present invention, the plastic
staple of
Fig. 22 being shown disposed therein.
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DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring now to Fig. 1, there is shown a perspective view of a length of
conventional continuously connected fastener stock of the plastic staple
variety, said
length of fastener stock being represented generally by reference numeral 11.
Fastener stock 11, which is made by the above-described rotary extrusion
method and is typically made of polyurethane, comprises two elongated and
continuous side members 13-1 and 13-2. Side members 13-1 and 13-2 are coupled
together by a plurality of flexible cross-links or filaments 15, cross-links
15 being
equidistantly-spaced apart by a distance of 0.25 inch. By cutting side members
13-1
and 13-2 at appropriate points between cross-links 15, individual fasteners
having an
H-shape, often referred to as "plastic staples," are produced. Each of the
cross-bars
of an individual plastic staple has a length of 0.25 inch.
Referring now to Fig. 2, there is shown an enlarged end view of an individual
plastic staple obtained in the aforementioned manner from a length of fastener
stock
11, the individual plastic staple being represented generally by reference
numeral 21.
Staple 21 comprises a first cross-bar 23-1, which has been cut from side
member 13-1, and a second cross-bar 23-2, which has been cut from side member
13-2, cross-bars 23-1 and 23-2 being interconnected by flexible filament 15.
As can
be seen, due to the rotary extrusion process by which stock 11 is formed,
cross-bars
23-1 and 23-2 and filament 15 are flat on sides 25-1, 25-2 and 25-3,
respectively,
sides 25-1, 25-2 and 25-3 being coplanar with one another. As a result, as can
be
seen, cross-bar 23-1 and filament 15 collectively have a generally "d"-shape
when
viewed from an end, with cross-bar 23-1 having a substantially semi-oval shape
in
cross-section and being generally symmetric about line 1-1. Cross-bar 23-1 has
a
transverse width Twl greater than its transverse length TI,. Cross-bar 23-2
and
filament 15 also collectively have a generally "d"-shape when viewed from an
end,
with cross-bar 23-2 being sized and shaped identically to cross-bar 23-1.
Referring now to Figs. 3 and 4, there are shown top and left side views,
respectively, of a conventional needle adapted for use in dispensing
fasteners, such
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as the plastic staple of Fig. 2, said needle being represented generally by
reference
numeral 51.
Needle 51 comprises a stem portion 53 and a base portion 55. Stem portion
53 may be made, for example, by stamping and rolling or by machining a piece
of
metal (e.g., stainless steel) or by the electroforming/machining technique
described
in U.S. Pat. No. 5,489,057, inventor Deschenes, issued February 6, 1996.
Referring now to Figs. 3 through 5, stem portion 53 can be seen to be an
elongated memberthat is substantially cylindrical over most of its length (and
annular
in transverse cross-section). The front end of stem portion 53 is formed into
a
spoon-shaped tip 57, tip 57 being sufficiently sharp to enable its penetration
into a
desired article of commerce. A generally cylindrical bore 59 extends
longitudinally
across substantially the entire length of stem portion 53. Bore 59 is
appropriately
dimensioned to receive a cross-bar of a plastic fastener, such as cross-bar 23-
1 of
plastic staple 21. Stem portion 53 is also shaped to include a slot 61
extending
longitudinally across substantially the entire length of stem portion 53, slot
61 being
appropriately dimensioned to permit a filament, such as filament 15, to extend
therethrough while its associated cross-bar is disposed within bore 59.
A conventional stamped and rolled stainless steel stem portion 53 used in the
dispensing of plastic staples 21 typically has a width w, of about 0.065 inch
and a
cross-sectional thickness t, of about 0.008-0.010 inch.
Referring back to Figs. 3 and 4, base portion 55 is made in the conventional
manner by insert-molding plastic onto the rear end 60 of stem portion 53. Base
portion 55, which is generally cylindrical in shape, inciudes a generally
cylindrically-shaped longitudinal bore aligned with (and sized similarly to)
bore 59 of
stem portion 53 and also includes a longitudinal slot aligned with (and sized
similarly
to) slot 61 of stem portion 53. Base portion 55 is provided with a recessed
area 63
for use in correctly positioning needle 51 within a fastener dispensing tool
and for
locking the same into place.
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Referring now to Fig. 6, there is shown a transverse section view of stem
portion 53, with plastic staple 21 being loaded therein. As described above,
the
present inventor has noted that, because filament 15 and cross-bar 23-1 are
flat on
sides 25-3 and 25-1, respectively, whereas bore 59 is circular in transverse
cross-
section and slot 61 bisects bore 59 from the top thereof, a considerable
portion of
bore 59 is left unoccupied by staple 21. Consequently, because bore 59 is
larger
than necessary to hold staple 21, the overall size or width w, of stem portion
53 is
unnecessarily large, thereby leading to an insertion hole created by stem
portion 53
that is larger than needed. In addition, because cross-bar 23-1 is much
smaller than
bore 59 and has considerable freedom to move laterally within bore 59, the
proper
translational movement of cross-bar 23-1 through bore 59 during ejection
cannot be
assured.
Referring now to Fig. 7, there is shown a left side view of a first embodiment
of a needle constructed according to the teachings of the present invention,
the
needle being represented generally by reference numeral 101.
Needle 101 comprises a stem portion 103 and a base portion 105. Base
portion 105, which is identical in all respects to base portion 55, may be
made by
insert-molding plastic onto the rear end of stem portion 103.
Stem portion 103 is similar in certain respects to stem portion 53. For
example, stem portion 103 is an elongated member terminating at its front end
in a
spoon-shaped tip 107, tip 107 being sufficiently sharp to enable its
penetration into
a desired article of commerce. However, as shown in Fig. 8, stem portion 103
differs
markedly from stem portion 53 in that stem portion 103 has a generally "d"-
shaped
transverse cross-section, instead of the generally annular transverse cross-
section
of stem portion 53. As such, stem portion 103 defines a generally semi-
elliptical bore
109 and a generally rectangular slot 111, bore 109 and slot 111 communicating
with
one another and extending longitudinally across substantially the entire
length of
stem portion 103. Bore 109 is bounded on one side thereof by a flat side 109-1
and
is bounded on its opposite side by a curved or"single-humped" side 109-2. Slot
111-
1 is bounded one on side thereof by a flat side 111-1, flat sides 109-1 and
111-1 lying
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in the same plane and forming a single continuous wall. Bore 109 is
appropriately
dimensioned to receive a cross-bar of a plastic fastener, such as cross-bar 23-
1 of
plastic staple 21, and slot 111 is appropriately dimensioned to permit a
filament, such
as filament 15, to extend therethrough while its associated cross-bar is
disposed
within bore 109.
As can be seen in Fig. 8, because the shape of stem portion 103 more closely
conforms to that of staple 21, the amount of unoccupied or wasted space in
bore 109
is considerably less than that in bore 59, and the overall size or width w2 of
stem
portion 103 can be made to be smaller than that for stem portion 53. Moreover,
because of the truncated shape of bore 109, cross-bar 23-1 has much less
freedom
to move laterally within bore 109 as it is being ejected therefrom.
Furthermore,
because slot 111 is shaped so as to surround comparatively more of the length
of
filament 15 than does slot 61, staple 21 is afforded increased protection
against
becoming broken in the vicinity of the juncture between filament 15 and cross-
bar 23-
1.
Stem portion 103 may be made by extrusion or by any of the same techniques
discussed above in connection with the fabrication of stem portion 53;
however, the
above-described electroforming/machining technique is preferred. Said
electroforming step is preferably performed using a suitably shaped master
(e.g., a
"d"-shaped master) and preferably involves depositing a boron/nickel (or
steel) alloy
onto the master to a substantially uniform thickness of about 0.003-0.005
inch. One
of the advantages of using electroforming and the aforementioned boron/nickel
alloy
to form stem portion 103 is that the cross-sectional thickness t2 of stem
portion 103
can be kept smaller than that for stem portion 53 (i.e., about 0.003-0.005
inch versus
about 0.008-0.010 inch), without a concurrent loss in strength (or even with
an
improvement in strength). This reduction in the cross-sectional thickness of
stem
portion 103, together with the truncated shape of stem portion 103, permits
the
overall size or width w2 of stem portion 103 to be kept to a minimum (e.g.,
about
0.050 inch for stem portion 103 versus about 0.065 inch for stem portion 53).
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Referring now to Fig. 9, there is shown a transverse section view of a second
embodiment of a stem portion of a needle constructed according to the
teachings of
the present invention, the stem portion being represented generally by
reference
numeral 151.
Stem portion 151 is identical in virtually all respects to stem portion 103,
the
principal difference between stem portion 151 and stem portion 103 being that
stem
portion 151 is shaped to define a generally rectangular bore 153, instead of
the
generally semi-elliptical bore 109 of stem portion 103. Bore 153 has a
transverse
cross-sectional height h, and a transverse cross-sectional width w3, height h,
being
greater than width w3 and extending parallel to the length of a filament in
slot 155.
Stem portion 151 is preferably made in the same manner as stem portion 103,
and a suitably shaped base portion (not shown) is preferably insert-molded
onto the
rear end of stem portion 151 in the conventional manner.
Because of the generally rectangular transverse cross-sectional shape of bore
153, stem portion 151 is particularly well-suited for use with a plastic
fastener having
a complementary generally rectangular cross-sectional shape. An example of
such
a fastener is shown in Fig. 10 and is represented generally by reference
numeral 171.
As compared to cross-bar 23-1, cross-bar 173 of fastener 171 has a
substantially
rectangular cross-section, ratherthan a substantially semi-oval shaped cross-
section,
and has a comparatively increased transverse cross-sectional length TI2 and a
comparatively decreased transverse cross-sectional width Tw2, with length TIZ
being
larger than width Tw,. The overall masses of cross-bar 23-1 and cross 173 are
generally equivalent. The increased transverse cross-sectional height endows
cross-
bar 173 with increased strength to resist collapsing towards its midpoint and
being
withdrawn through an article when a withdrawing force is applied to filament
175 (a
phenomenon known in the art as "Y"-ing).
Referring now to Figs. 11 and 12, there are shown side and perspective views,
respectively, of a first embodiment of a length of plastic staple stock
constructed
according to the teachings of the present invention, said length of plastic
staple stock
being represented generally by reference numeral 201.
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Stock 201, which is preferably made a rotary extrusion method of the type
described above and which is preferably made of polyurethane or the like,
comprises
two elongated and continuous side members 203-1 and 203-2. Side members 203-1
and 203-2 are coupled together by a plurality of flexible cross-links or
filaments 205,
cross-links 205 being equidistantly-spaced apart by a distance of about 0.18
inch.
By cutting side members 203-1 and 203-2 at appropriate points between cross-
links
205, individual fasteners having an overall H-shape and a cross-bar length of
about
0.18 inch are produced. One advantage of stock 201 having a pitch of about
0.18
inch, as opposed to the 0.25 pitch of stock 11, is that the number of
fasteners per
unit length of stock is greater in stock 201 than in stock 11, thereby
permitting more
fasteners to be fitted to a length of stock 201 than to a comparable length of
stock 11.
One would not want to further reduce the pitch of the stock much more beyond
0.18
inch (i.e., in the vicinity of 0.1 inch) since, for many applications, a cross-
bar much
shorter than about 0.18 inch is too short to be retained in an item and will
too easily
be withdrawn through the item when subjected to a substantial withdrawal
force.
Referring now to Fig. 13, there is shown a fragmentary enlarged end view of
an individual plastic staple obtained in the aforementioned manner from a
length of
fastener stock 201, the individual plastic staple being represented generally
by
reference numeral 221.
Staple 221 comprises a first cross-bar 223-1, which has been cut from side
member 203-1, and a second cross-bar 223-2, which has been cut from side
member
203-2, cross-bars 223-1 and 223-2 being interconnected by flexible filament
205. As
can be seen, due to the rotary extrusion process by which stock 201 is formed,
cross-
bars 223-1 and 223-2 and filament 205 are flat on sides 225-1, 225-2 and 225-
3,
respectively, with sides 225-1, 225-2 and 225-3 being coplanar with one
another. As
can also be seen, cross-bars 223-1 and 223-2 are shaped to include a pair of
protrusions or humps on sides 225-4 and 225-5, respectively. Consequently,
each
of cross-bars 223-1 and 223-2 has a generally "B"-shape when viewed from the
ends
thereof.
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Referring now to Fig. 14, there is shown a fragmentary perspective view of a
third embodiment of a needle constructed according to the teachings of the
present
invention, said needle being represented generally by reference numeral 251.
Needle 251 comprises a stem portion 253 and a base portion (not shown),
said base portion being similar to base portion 55 and preferably being made
by
insert-molding plastic onto the rear end of stem portion 253.
Stem portion 253 is similar in many respects to stem portion 103. For
example, stem portion 253 is an elongated member terminating at its front end
in a
spoon-shaped tip 257, tip 257 being sufficiently sharp to enable its
penetration into
a desired article of commerce. However, as seen best in Fig. 15, stem portion
253
differs primarily from stem portion 103 in that stem portion 253 has a
longitudinal bore
259 of a generally "B"-shaped transverse cross-section, instead of the
generally
semi-elliptical bore 109 of stem portion 103. Bore 259 is bounded on one side
thereof by a flat side 259-1 and on an opposite side thereof by a curved or
"double-
humped" side 259-2. Stem portion 253 defines a longitudinal slot 261 bounded
one
on side thereof by a flat side 261-1, flat sides 259-1 and 261-1 lying in the
same
plane and forming a single continuous wall. Bore 259 is appropriately
dimensioned
to receive a cross-bar of a plastic staple, such as cross-bar 223-2 of plastic
staple
221, and slot 261 is appropriately dimensioned to permit a filament, such as
filament
205, to extend therethrough while its associated cross-bar is disposed within
bore
259. The outer width of stem portion is about 0.042 inch.
Many of the advantages discussed above that result from the use of needle
101 with conventional plastic staples also result from the use of staple 221
and
needle 251.
Referring now to Fig. 16, there is shown a fragmentary end view of a third
embodiment of an individual plastic staple constructed according to the
teachings of
the present invention, said plastic staple being referred to generally by
reference
numeral 301.
Staple 301 is similar in virtually all respects to staple 221, staple 301
comprising a pair of mirror image cross-bars (only first cross-bar 303-1 being
shown)
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interconnected by a flexible filament 305. As can be seen, cross-bar 303-1 and
filament 305 are flat on sides 307-1 and 307-2, with sides 307-1 and 307-2
being
coplanar with one another. As can also be seen, cross-bar 303-1 is shaped to
include a pair of protrusions or humps 311-1 and 311-2 on opposite side 309-1,
humps 311-1 and 311-2 being spaced further apart than the corresponding humps
on cross-bar 223.
Referring now to Fig. 17, staple 301 is shown inserted into the stem portion
321 of a needle. Stem portion 321 is similar in virtually all respects to stem
portion
253 of needle 251, stem portion 321 being an elongated member terminating at
its
front end in a spoon-shaped tip and being shaped to include a longitudinal
bore 323
and a longitudinal slot 325. Bore 323, which has a generally "B"-shaped
transverse
cross-section, is bounded on one side thereof by a flat side 327-1 and on an
opposite
side thereof by a curved or "double-humped" side 327-2. Slot 325 is bounded
one
on side thereof by a flat side 329-1, flat sides 327-1 and 329-1 lying in the
same
plane and forming a single continuous wall. Stem portion 321 differs from stem
portion 253 only in that bore 323 is appropriately shaped to conform to the
shape of
side 309-1 of cross bar 303-1, as opposed to side 225-4 of cross-bar 223-1.
Referring now to Fig. 18, there is shown a fragmentary end view of a fourth
embodiment of an individual plastic staple constructed according to the
teachings of
the present invention, said plastic staple being referred to generally by
reference
numeral 401.
Staple 401 is similar in many respects to staple 221, staple 401 comprising a
pair of mirror image cross-bars (only first cross-bar 403-1 being shown)
interconnected by a flexible filament 405. As can be seen, cross-bar 403-1 and
filament 405 are flat on sides 407-1 and 407-2, with sides 407-1 and 407-2
being
coplanar with one another. As can also be seen, cross-bar 403-1 is shaped to
include a sloped side 411 opposite to side 407-1, sloped side 411 giving cross-
bar
403-1 a generally wedge-shaped transverse cross-section.
Referring now to Fig. 19, staple 401 is shown inserted into the stem portion
421 of a needle. Stem portion 421 is similar in many respects to stem portion
253 of
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needle 251, stem portion 421 being an elongated member terminating at its
front end
in a spoon-shaped tip and being shaped to include a longitudinal bore 423 and
a
longitudinal slot 425. Bore 423, which has a generally wedge-shaped transverse
cross-section, is bounded on one side thereof by a flat side 427-1 and on an
opposite
side thereof by a sloped side 427-2. Slot 425 is bounded one on side thereof
by a
flat side 429-1, flat sides 427-1 and 429-1 lying in the same plane and
forming a
single continuous wall. As can be seen, bore 423 of stem portion 421 is
appropriately
shaped to conform to the shape of cross bar 403-1.
Referring now to Fig. 20, there is shown a fifth embodiment of an individual
plastic staple constructed according to the teachings of the present
invention, said
plastic staple being referred to generally by reference numeral 501.
Staple 501 is similar in virtually all respects to staple 301, staple 501
comprising a pair of mirror image cross-bars (only first cross-bar 503-1 being
shown)
interconnected by a flexible filament 505. As can be seen, cross-bar 503-1 and
filament 505 are flat on sides 507-1 and 507-2, with sides 507-1 and 507-2
being
coplanar with one another. As can also be seen, cross-bar 503-1 is shaped to
include a pair of protrusions or humps 511-1 and 511-2 on opposite side 509-1,
humps 511-1 and 511-2 differing from humps 311-1 and 311-2 of staple 301 in
that
hump 511-1 protrudes further away from side 507-1 than does hump 511-2.
Referring now to Fig. 21, staple 501 is shown inserted into the stem portion
521 of a needle. Stem portion 521 is similar in virtually all respects to stem
portion
321, stem portion 521 being an elongated member terminating at its front end
in a
spoon-shaped tip and being shaped to include a longitudinal bore 523 and a
longitudinal slot 525. Bore 523, which has a generally "B"-shaped transverse
cross-
section, is bounded on one side thereof by a flat side 527-1 and on an
opposite side
thereof by a curved or "double-humped" side 527-2. Slot 525 is bounded one on
side
thereof by a flat side 529-1, flat sides 527-1 and 529-1 lying in the same
plane and
forming a single continuous wall. Stem portion 521 differs from stem portion
321 only
in that bore 523 is appropriately shaped to conform to the shape of side 509-1
of
cross bar 503-1, as opposed to side 309-1 of cross-bar 303-1.
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Referring now to Fig. 22, there is shown a fragmentary end view of a sixth
embodiment of an individual plastic staple constructed according to the
teachings of
the present invention, said plastic staple being referred to generally by
reference
numeral 601.
Staple 601 is similar in many respects to staple 401, staple 601 comprising a
pair of mirror image cross-bars (only first cross-bar 603-1 being shown)
interconnected by a flexible filament 605. As can be seen, cross-bar 603-1 and
filament 605 are flat on sides 607-1 and 607-2, with sides 607-1 and 607-2
being
coplanar with one another. As can also be seen, cross-bar 603-1 is shaped to
include a protrusion or hump 609 on a side 611 opposite to side 607-1.
Referring now to Fig. 23, staple 601 is shown inserted into the stem portion
621 of a needle. Stem portion 621 is similar in many respects to stem portion
421,
stem portion 621 being an elongated member terminating at its front end in a
spoon-
shaped tip and being shaped to include a longitudinal bore 623 and a
longitudinal slot
625. Bore 623 is bounded on one side thereof by a flat side 627-1 and on an
opposite side thereof by a side 627-2 shaped to conform to side 611 of cross-
bar
603-1. Slot 625 is bounded one on side thereof by a flat side 629-1, flat
sides 627-1
and 629-1 lying in the same plane and forming a single continuous wall.
The embodiments of the present invention recited herein are intended to be
merely exemplary and those skilled in the art will be able to make numerous
variations and modifications to it without departing from the spirit of the
present
invention. All such variations and modifications are intended to be within the
scope
of the present invention as defined by the claims appended hereto.
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