Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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1~2780
Background of the Invention
The present invention is generally directed to an
improved fastener and more particularly to an improved threaded
fastener which establishes a seal between the fastener and a
work piece surface into which it is driven.
There are many applications where fasteners must be
threadingly received by work pieces. Thread tapping and thread
forming fasteners are very popular for this purpose because the
work piece openings to receive the fasteners need not be pre-
tapped with internal threads. Also, drilling screws are popularbecause they include their own drill tip and therefore do not
even require a pre-drilled hole.
Screws or fasteners of this type, when driven into a
work piece, scrape paint or other corrosion resistant coatings
from the work piece surface immediately adjacent or around the
connection between the fastener and the work piece. The ex-
posed bare work piece surface areas are thus subject to corrosion
or rust unless means are provided to seal the connection between
the work piece opening surrounding areas and the fastener.
Further, work piece fragments are produced by thread tapping
and drilling screws. These fragments can interfere with the
aforementioned seal unless they are displaced from the seal
area. These fragments can further be harmful to or damage
moving parts or electrical components associated with or near
to the fastener connection.
Prior art fasteners have therefore been proposed
and used which include a moisture impervious cover about the
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head of the fastener which are arranged to enclose and seal the
exposed work piece surface areas. ~lowever, fasteners of this
type in the prior art have not been structured to both provide
an effective seal and cope with the work piece fragments.
Hence, moisture sealing fasteners of the prior art suffer from
the collection of work piece fragments in the seal area which
eventually, if not immediately, destroy the intended seal of
the connection between the fastener and the work piece.
Further, those fragments which are not lodged in the moisture
sealing area are rendered free for displacement to moving or
electrical components associated with or near to the fastener
connection. As previously mentioned, these fragments can cause
harm or damage to such components.
Therefore the present invention seeks to provide a new
and improved moisture sealing fastener and more specifically
seeks to provide a moisture sealing threaded fastener which
provides a complete and effective moisture seal notwithstanding
the production of work piece fragments as the fastener is driven
into a work piece. Further the present invention provides such
a fastener which deflects work piece fragments away from the
seal area and further traps the fragments to preclude their
free displacement.
The invention provides a screw threaded fastener
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including a head and a self-threading threaded shank, the head
including a driving recess that is oversize in relation to the
tool normally adapted -to drive such a fastener. The head has a
clamping surface facillg in the direction of the shank and
shoulder means having edge surfaces are spaced laterally
inwardly from the outer margin of the clamping surface and
surround the shank while extending axially a predetermined
distance from the head clamping surface to space the threaded
shank from the head. A unitary substantially uniform thickness
plas-tic cap is insert molded about the head and includes both
conformance with the oversize recess as well as extending
partially under the head clamping surface. The recess formed
in the cap accepts the normal size tool adapted to drive such
fastener. The inner margin of the cap under the head clamping
surface has a thickness substantially equal to the
predetermined thickness and terminates in radially spaced
relation to the shoulder means edge surfaces to form a cavity
therebetween having a predetermined volume. The device
includes continuous deflectable flange means which is thinner
than the uniform thickness and has a volume not greater than
the cavity, the flange means initially extending axially from
the clamping surface a distance greater than the shoulder means
whereby when the fastener is inserted into a complimentary
workpiece aperture, the flange is inwardly deflected into the
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cavity upon contacting the workpiece surface and deflects any
workpiece fragments adjacent the aperture into the cavity.
Thus the fragments are sealingly captured in the cavity to
preclude the fragments from damaging the aesthetic appearance
of the workpiece. The shoulder means is adapted to bottom on
the workpiece and prevents crushing of the inner margin of the
cap and the flange.
Brief Description of the Drawings
The features of the present invention which are
believed to be novel are set forth with particularity in the
appended claims. The invention, together with further objects
and advantages thereof, may best be understood by making
reference to the following description taken in conjunction
with the accompanying drawings, and the several figures of which
like reference numerals identify identical elements, and
wherein:
FIG. 1 is a side view, partly in cross-section, of a
fastener embodying the present invention;
FIG. 2 is a top plan view of the fastener of FIG. l;
and
FIG. 3 is a side view, partly in cross-section,
illustrating the fastener of FIG. 1 after being fully driven
into a work piece.
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Case 348~-00
Z780
Description of the Preferred Embodiment
Referring now to FIGS. 1 and 2, the fastener 10
embodying the present invention is of a type commonly referred
to as a drilling screw. However, it will be apparent herein-
after that the present invention may also be advantageously
employed in thread tapping or thread forming screws as well
or in any fastener for that matter wherein a seal between
the fastener and a work piece is desired. The screw 10
generally includes a head portion 12, a shank portion 14,
and a moisture impervious cover 16 overlying the head
portion 12. The shank portion 14 of the fastener or screw
10 includes a dr;ll point 18 at the end of shank 14 opposite
the head portion 12. The drill point 18 is fluted and includes
a pair of segments, one of which is shown at 20, removed from
the circular cross-section of the shank and leaving land por-
tions 22 remaining therebetween. The drill point 18 has an
effective transverse width substantially equal to the transverse
width of the shank roots 24 and of lesser dimension than the
effective transverse dimension of the thread crests 26. The
thread of shank portion 14 defined by the roots 24 and crests
26 extends helically from the drill point 18 to the head por-
tion 12.
The drill point 18 terminates in a pair of cutting
edges, one of which is shown at 28, which drill into the work
to create an opening in the work piece. As the screw 10 is
driven, the threads 30 defined by the roots 24 and crests 26
form a cooperating thread in the drilled work piece opening
and permit the screw to be driven home.
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The head portion 12 includes an upper surface 32
which is contoured to form a drill receiving recess to afford
interlocking engagement of the head portion 12 with a driver
(not shown). The head portion 12 further includes an under
surface 36 including a raised surface portion 38 having a
generally square outer periphery and an under cut or relief
surface ?ortion 40 which extends from the perimeter of the
raised portion 38 out to the periphery of the under surface
36.
The moisture impervious cover 16 completely overlies
the upper surface 32 of the head portion 12 and is contoured in
correspondence with the upper surface to further define the
drill receiving recess 34 and rotationally fix the cover 12
with respect to the head 12. The cover 16 axially extends
from the clamping under surface 36 of the head portion 12
toward the shank portion 14. As a result, an annular flange
or seal ring 42 is formed. The annular flange 42 is coaxially
disposed with respect to the shank portion 14 and is of greater
diameter dimension than the transverse dimension of the shank
portion. As a result, a cavity 44 is formed by the annular
flange 42 and the clamping surface 36 of the head portion 12.
As may be further noted in FIG. 1, the annular
flange 42 terminates in a narrow edge 46 having a curved
surface portion 48. Preferably, the moisture impervious
coverlng 16 is formed from a resilient material so that, with
the relatively narrow edge portion 46 and its outer curved
surface 48 ! the annular flange 42 is rendered inwardly
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deformable upon contacting the surface of the work piece into
which the fastener or screw 10 is driven.
As has been previously noted, when a fastener such
as fastener or screw 10 of FIG. 1 is driven into an opening of
a work piece, outer surface paint of the work piece around the
opening is scraped by the fastener. Further, in the case of
drilling screws and thread tapping screws, work piece fragments
are produced. As can be appreciated from the foregoing, as
the fastener 10 of FIG. 1 is driven into the work
piece, and as the annular flange 42 contacts the work piece
surface, the annular flange 42 will inwardly deform (as best
seen in FIG. 3) to create a seal between the fastener and the
work piece. Also, as the flange inwardly deforms, it will de-
flect work piece fragments into the cavity or pocket 44 and
away from the sealing area established by the annular flange
42.
Referring more specifically now to FIG. 3, it illus-
trates the fastener 10 after being fully driven into a work
piece 50. As can be noted in FIG. 3, the annular flange 42
has been inwardly deformed and received by the relief surface
portion 40 of the clamping surface 36. It may be further
noted in FIG. 3 that as the annular flange 42 was inwardly
deformed, it deflected work piece fragments or paint chips
into the cavity 44 (FIG. 1) and eventually up against the
relief surface portion 40 and the periphery of the surface
portion 38. As a result, the work piece fragments and paint
chips 52 were deflected away from the seal area between the
annular flange 42 and the surface 54 of the work piece 50.
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As can be further appreciated from the foregoing,
the fragments 52 are also confined within the fastener 10 to
prevent their free displacement into moving parts or electrical
components associated with the connection between the fastener
10 and the work piece 50. As a result, a complete and effective
seal is provided between the fastener 10 and the work piece
50 which is free from work piece fragments or paint chips which
could immediately or eventually destroy the intended seal of
the connection between the fastener and the work piece.
While a particular embodiment of the present invention
has been shown and described, modifications may be made, and it
is therefore intended to cover in the appended claims all such
changes and modifications which fall within the true spirit
and scope of the invention.
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