Note: Descriptions are shown in the official language in which they were submitted.
Background of the Invention
Plastic drlve fasteners of various configurations are
known in the art and more particularly particular reference
should he made to the paten-t to Edwin Grant Swick and
John ~rederick Nelson, Vnited States Letters Patent 3,810,279
issued May 14, 197~ and assigned to the common assignee of the
present invention. Such fasteners while suitable for many
applications have a single inherent problem, namely, the
insertion force for installing the fastener in an aperture or
bore of a work piece is substantially equal to the force
required for removal of the fastener from such an aperture or
bore. In some applications it has been found desirable to
provide a fastener which can be xeadily installed but which
requires an excessive amount of force to remove same.
Summar _ - ch~ Inv--~.ion
The present invention is an improvement over the
teachings of United States Letters Patent 3,810,279 and provides
a one piece plastic drive fastener including a head and a shank
with -the shank having an axis and comprising an elongate body
portion having a generally polygonal cross-section and providing
a plurality of radially outwardly facing substantially flat
surfaces. A first plurality of integral resilient independent
wings extend radially outwardly from at least one of the flat
surfaces at axially spaced intervals. The junctures of the
first plurality of wings along the at least one of the surfaces
is each along a respective straight line forming a bend line for
flexure of the first wings during introduction of the
fastener into a complementarily apertured workpiece. A
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second plurality of intecJral resilient independent wings
extend from and are positioned in axially spaced relation
along at least one of the other of the surfaces and are
angularly disposed so as to ineline in the direetion of the
headO Each of the second wings has a thickened section formed
at its juncture,whereby each thickened section eoacts with its
respective second wing to define a bend line along whieh each
second wing flexes which bend line is spaced radially from the
respective surface to which each of the second wings is
attached.
More partieularly, the present invention seeks -to
provide a fastener of the type generally described i.mmediately
above, having angled wing elements which are knuckled, whexei.n
eaeh wing element ls provided wi.th an angularly disposed
1.5 :reinforcing portion on its upper surfaee whieh eauses the wing
e:LemeTlts t.o flex cJe.rlerally parallel to the .flat surfaee but at
a poin~ radial:Ly removed therefrom.
The present invention provides an eeonomieal fastener
which can he readily molded in a two-plate mold, and one eapable
of being utilized with multiplieity of head styles as well as a
plurality of di.ffering designs of entry or nose eonfigurations.
Other aspeets will be apparent to those skilled in the
art when the speeification is read in eonjunc-tion wi.th the
following drawings.
Brief Description of the Drawinc
. _
Fi.g. 1 i.s an elevational view of one embodiment of the
present invention,
.~ -3-
;' 1
Case 3623
3~7
Fig. 2 is a cross~ection~l elevational view tal;~in along
line 2-2 of Fig. li
Fig. 3 is a sectional vlew taken along 1ine 3 - 3 of
Fig~ 2;
Fig. 4 is a fragmentary enlarged cross-sectional view
of the improved wing portions of the present invention;
Fig, 5 is an elevational view of a prior art drive fast-
ener;
li'ig. 6 i9 a fragment~ry view of a drive fastener h~ving
angled wing elements without the improvement of th~ pre~ent
invention;
Fig, 7 is a .Eragmentary vi~w of a drlve eastener havl.n~
the knuckled ancJle~l w1.ng element of the present inv~ntion;
Fig. 8 A is a ~chematic view of wing elements of the
prior art;
Fig. 8 B is an intermediate development of the type ehown
in Fig. 6;
and Fig. 8 C is a ~chematic view of the present invention.
Detailed Description of the Preferred Emhodiment
-- -- .. ... , _
A plastic drive fastener of the improved variety con-
templated by the pre~ent invention i9 generally designated by the
mlmeral 10 and include~ ~ head (12) ~nd a chank (14). While the
present invention shows the head ~2) ~ being 8 domed sealing
head, it should be recognized by tho~e ~killed in the art that this
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:, `
37~7 Case 3fi23
is merely one showing of a head form. Such a fastener, as con-
ternplat~d by the present invention, can have a single head (12),
as shown, or may include a multiplicity of axially spaced heads
of the type norrnally used to fasten trim panels to ~utomotive
5 door interiors, not shown.
The importance of the present invention relates to a
plastic drive fastener which can be readily installed into an
apertured panel or a bore within a thicls panel in which the re-
moval force is far in excess of the force of installation. An em bodiment
of such a fastener is shown in Fig. 1 through 4, 7 and
8C. ~he shank (14) of such a fastener i6 generally non-circular
or polygonal in cDnfiguration and provides a plurality of axially
extending flat surfaces (16~ which in the present embodiment
are four is~ nul~l)er, however, it ~houlcl he appreciated that any
15 equal number of flat surfaces will suffice. Extending outwardly from
the flat surfaces (16) are a plurality of axially spaced flexible
resilient wing elements (l8~ which are provided with a generally
tapered undersurface (20) and a radinlly extending upper ~urface
(22), as best seen in Fi~. 2.
Along at least one flat 6urfsce (16) ~re ~ plurality of
certain resilient wing elements (30) which are angularly dispos-
ed relative to the ~xis of the 8hank (14~ and tilt or are inclined
upwardly, as viewed in the drawing, toward the head (12).
The initial devel~pment work of this fastener was t~ ~ltili.ze
a tilted wing, as seen in Fig. 6, which had substantially
the same configuration as the flexible wing elements
~18) that extend radially outwardly. As
37~7 Case 3623
can be seen in Fig. 6 these elements ~enerally designated (32)
fle7~ed along a straight line formed by their juncture with the
flat ~urface (16). ~he insertion and removal forces of such
items were slightly different.
Further development resulted in the present embodi.~nt shown
in Fig. 1 through 4 and Fig. 7 wh~rein a thickened section or
portion (34) is added to each of the angled wing elem~nts (30)
this results in the certain wing elements (30) having a bend line
(36), as best seen in Fig. 7, which is generally parallel to sur-
face (16) but laterally spaced outwarclly therefrom. In essence,
this creates a short stubby wing element (30) that can be readily
inserted into an aperture or bore but which resists with great
tenacity the removal of the fa~tener from the aperture or bore.
'I ests were conductecl on various configurations of wings and
the results of SUCII tests are shown in pourlds of force require(l
to push the fastener in and to pull the fastener out. ~rhe figures
are displayed in reference to the wing configurations shown in
Fig. 8A, 8B and 8C, the latter being the embodiment of the
present in~tention. These test results are a6 follows:
Fig. 8 A_ Fi~. 8 B Fig. 8 C
IN OU~ IN OU~ IN OUT
24 32 10 18. 5 30 75
21 23 11. 5 14. 5 35 75
23 11 ~16. 5 20 70
1~ 22 1~. 5 13 25 80
2~1 21 10.5 15 25 82.5
2~ 21 10 1~. 5 35 6S
22 2~ 1~. 5 12~ 5 25 87. 5
22 20 10 12. 5 20 75
2~ 19 10 12 22. 5 75
2~ 18 lO 12 27. 5 72. 5
~ ~ ~33~7
AVER AG; ES
21. 5 22. 2 10. 4 14. l ?3. 8 75. 8
R EMOVA~ / INSER TION
R A~105
_._
1.0 1.4 3.2
As will be noted there is a dramAtic unexpected result
in the device of the present invention a6 shown in Fig. 8C.
In the present disclo6ure the improved form of resili-
ent wing (30) with its thickened portion q34) is shown extending in
opposite directions ~rom two of the flat wall surfaces (16) of the
shank (14) with the radially extending wing element (183 occupy-
ing the other two flat opposed surfaces. It will be recognized
that the amount of force removal can be controlled for a fastener
of this design dependent upon the number of surfaces provided
with t~.ickene~ ~ngled wing elements i30). Wing elements (30~ ex-
tending from one or more of the surfac~es i~ all that is requir~?d,
however, all of the 6urfaces can utilize such a wing element.
Where wing elements (30) or (18) are extending from only one or
two ~urfaces, not shown, it ha6 been found desirable to provide
means, such a6 an axially extending centering rib, not shown, to
locate the fastener for optimum operating conditions relative to
the cooperating aperture or bore. Ideally the wing elementson at
least one of the surfaces are axially offset reiative to the
wing elements of at :least one of the other surfaces to provide
varying gxip lengths.
While the preserJt shank ~14) includes four flat surfaces
(16) it should be appreciated that the wing element (18) and ~30)
can extend from and cover the entire width of the flat surface or
alternatively the ~hank (14) can include, if desired, a plurality
7~
3~ o~ v
o~ axially extending recesses (40) which interrupt and space ad-
jacent flat surfa-es for pu ?oses of accepting an axially extend-
ing tool.
The nose portion (44) in the preserlt embodiment is
5 shown as an arrow-shaped member but it will be appreciated
that other configurations are equally usable. ~he shank (16~
can be blunt at the end, rounded, arrow-shaped, or pointed as
may be desired.
Other embodiments of the present invention will be
10 apparent to those skilled in the art.
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