U.S. patent number 3,695,321 [Application Number 05/051,152] was granted by the patent office on 1972-10-03 for cavity head screw and driving tool therefor.
Invention is credited to Jacob W. Garehime, Jr..
United States Patent |
3,695,321 |
Garehime, Jr. |
October 3, 1972 |
CAVITY HEAD SCREW AND DRIVING TOOL THEREFOR
Abstract
The upper surface of the head of a screw has wedge-shaped
cavities arranged on either side of, or around, a central hub or
land. The cavities have undercut sidewalls, and the land has a
central hole, preferably circular. A driving tool such as a
screwdriver, or the like, is provided with multiple blades which
are spaced apart on either side of or around a central aperture. A
central pin depends from the shank of the screwdriver and is
adapted to engage the hole in the central land of the screw. The
bottoms of the screwdriver blades are of expanded thickness so that
when these blades are inserted in and engage the screwhead
cavities, the expanded bottom portions of the blades will lock
under the undercut sidewalls of the cavities. Mating of the
screwdriver blades and the screw head cavities is guided, aligned
and axially stabilized by engagement of the screwdriver central pin
in the hole in the central land of the screwhead surface.
Expandable pin sections maintained under tension may be employed to
temporarily lock a screw onto the screwdriver blades and held in
positive axial alignment with said screwdriver for insertion and
withdrawal.
Inventors: |
Garehime, Jr.; Jacob W. (Las
Vegas, NV) |
Family
ID: |
21969663 |
Appl.
No.: |
05/051,152 |
Filed: |
June 30, 1970 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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827627 |
May 26, 1969 |
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Current U.S.
Class: |
81/448; 81/461;
411/919; 411/403 |
Current CPC
Class: |
B25B
15/007 (20130101); F16B 23/0007 (20130101); Y10S
411/919 (20130101) |
Current International
Class: |
B25B
15/00 (20060101); F16B 23/00 (20060101); B25b
015/02 (); F16b 023/00 () |
Field of
Search: |
;145/5A,5D,5E,5R,51,52
;85/45 ;81/9C ;287/DIG.7 ;279/96,102 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Riordon; Robert C.
Assistant Examiner: Bicks; Mark S.
Parent Case Text
This application is a continuation-in-part of my application Ser.
No. 827,627, filed May 26, 1969.
Claims
I claim:
1. The combination of a driving tool and a screw to be driven
thereby, said driving tool having a shank, a plurality of laterally
spaced apart flat blades attached to said shank, the lower portions
of said blades being of expanded thickness, and said screw having a
plurality of radial cuneiform cavities in its head upper surface,
said cavities having undercut sidewalls and a central land
separating said cavities, said central land in said screwhead
surface adapted to mate with the space between said screwdriver
blades, and the expanded portions of said screwdriver blades
engaging said undercut sidewalls of said cavities in the surface of
said screw when said screwdriver and said screw are in working
engagement, in which the improvements comprise:
a said driving tool having a central pin depending from said shank
between said laterally spaced apart blades; and,
b said screw having a hole in the central land separating the
cuneiform cavities in the head thereof adapted to mate with the
said pin depending between the blades of said driving tool.
2. The combination of claim 1 in which the depending pin of said
driving tool has resilient means to temporarily grip the walls of
said hole in said central land of the head surface of said screw
when said driving tool and said screw are in working
engagement.
3. The combination of claim 1 in which the depending pin of said
driving tool has an encircling groove around its outer surface and
expandable spring means in said groove adapted to temporarily grip
the walls of said hole in said central land of the head surface of
said screw when said driving tool and said screw are in working
engagement.
4. The combination of claim 1 in which the depending pin of said
driving tool has an upper shoulder portion adapted to mate with
said hole in the central land of the head surface of said screw,
and a lower bulbous portion split vertically into a plurality of
spaced apart sections and adapted to temporarily grip the walls of
said hole in the central land of the head surface of said screw
when said driving tool and said screw are in working
engagement.
5. The combination of claim 1 in which the depending pin of said
driving tool is of tubular form and split vertically into a
plurality of spaced apart sections and adapted to temporarily grip
the walls of said hole in the central land of the head surface of
said screw when said driving tool and said screw are in working
engagement.
6. The combination of claim 1 in which the cross section of the
depending pin of said driving tool and the cross section of the
hole of the central land of the head surface of said screw are
circular.
Description
This invention relates to a screw or fastener, and to a driving
tool to drive or withdraw such screw.
My aforesaid application Ser. No. 827,627 describes and claims a
screw or rotatable fastener, and a screwdriver for such fastener in
which the screwdriver blades are locked in screwhead cavities so
that the screwdriver blades cannot slip endwise to mar the work,
nor can the blade slip upwardly out of the cavities. No pressure
whatsoever is required to maintain the screwdriver blades and the
screwhead in proper working engagement. This is accomplished by
providing a screw or rotatable fastener having a plurality of
radial, cuneiform cavities in its head upper surface. The generally
radial side walls of the cavities are undercut and the cavities are
arranged on either side of, or around, a central land in the
screwhead surface. A screwdriver having a plurality of spaced apart
blades is employed to engage the cavities in the screwhead and to
drive the screw. Each screwdriver blade has its bottom portion of
expanded thickness so that these expanded portions can lock in
under the undercut side walls of the screwhead cavities. The
screwdriver blades are laterally spaced apart from each other on
either side of, or around a central aperture into which fits or
mates the central land in the head of the screw. Thus when the
screwdriver blades are in working engagement with the screw their
expanded bottom portions are locked under the undercut cavity side
walls and the central land in the screwhead surface mates with the
aperture between the screwdriver blades to maintain positive
central alignment. The screwdriver cannot slip endwise, or up out
of a slot, and no pressure is required to maintain the screwdriver
blades in working engagement with the screw.
The screw and driving tool of this invention comprise an
improvement over those described above in that the screw can be
accurately guided or piloted into proper position to receive the
blades in the cavities in the screwhead and is axially aligned and
stabilized with respect to the driving tool. This is accomplished
by providing a central pin depending from the shank of the
screwdriver between the spaced apart blades, and a hole in the
central land of the screwhead surface with which the screwdriver
pin can mate. If desired, the screw can be temporarily fastened or
held in such position so that easy and positive entry of the screw
shank into its threaded mating piece is readily made. Split pins or
other resilient means can be employed to provide tension against
the walls of the hole in the screwhead land to hold a screw
temporarily in place with screwhead cavities engaging the
screwdriver blades.
Details of the construction and operation of this invention will be
more readily apparent from the following detailed description
thereof, and from the annexed drawings in which:
FIG. 1 shows a side view of a driving tool such as a screwdriver
embodying features of this invention.
FIG. 2 shows the blade portion of the screwdriver of FIG. 1,
considerably enlarged.
FIG. 3 shows an end view of the blade portion of the screwdriver of
FIG. 1, considerably enlarged.
FIG. 4 shows a perspective view of a screw embodying features of
this invention.
FIG. 5 shows a perspective view of a screwdriver and screw
according to this invention in working engagement.
FIG. 6 shows a side view, enlarged, of the blade portion of the
screwdriver of FIG. 1 having a modified central pin.
FIG. 7 shows a bottom view of the screwdriver blade portion of FIG.
6.
FIG. 8 shows a side view, enlarged, of the blade portion of the
screwdriver of FIG. 1 having another type of modified central
pin.
FIG. 9 shows a bottom view of the screwdriver blade portion of FIG.
8.
FIG. 10 shows a side view, enlarged of the blade portion of the
screwdriver of FIG. 1 having yet another modification of the
central pin.
FIG. 11 shows a bottom view of the screwdriver blade portion of
FIG. 10.
Referring to FIGS. 1, 2 and 3 the driving tool, is shown, for
example, having a conventional screwdriver handle 12 to which is
attached a shank 14 to which are attached a plurality, two in the
example shown, of radial, laterally spaced apart blades 16. These
blades 16 are are characterized by a bottom 18 of expanded
thickness as will be most clearly seen in FIG. 3. Between blades 16
and depending from the shank 14 is a central pin 20 which is
preferably longer, as shown, than the height of blades 16.
Referring now particularly to FIG. 4 the screw comprises a shank 22
and a head 24 which is characterized by having in its head surface
a plurality, two in the example shown, of radial cuneiform cavities
26 having undercut sidewalls 28. Cavities 26 are separated by a
central land 30 in which is a hole 32 adapted to mate with pin 20
depending from the driving tool shank as shown in FIGS. 1 and
2.
In FIG. 5 the screwdriver of FIG. 1 and the screw of FIG. 4 are
shown in working engagement. Screwdriver blades 16 are in cavities
26 in the screwhead 24 with their side faces engaging the undercut
side walls, and pin 20 depending from screwdriver shank 14 is mated
with hole 32 in the central land 30 of the screwhead 24.
In FIGS. 6 and 7 is shown, enlarged, the blade portion of a driving
tool with a modified central pin 34 having resilient means
including an encircling or girdling groove 36 in which is placed
split spring expansion ring 38 whose purpose is to temporarily grip
the sidewalls of hole 32 in the screw. Preferably ring 38 is
laterally curvate to provide easy entry and withdrawal from hole
32, and the bottom edge of pin 34 is also radiused as at 40 to
provide easy entry.
In FIGS. 8 and 9 is shown, enlarged, the blade portion of a driving
tool with another type of modified central pin comprising an upper
shoulder portion 42 adapted to mate with hole 32 in the head of the
screw, and a lower bulbous portion 44 attached to shoulder 42 by
neck 46. This assembly is vertically split into a plurality of
spaced apart sections to provide spring tension or resilience
against the walls of hole 32 when inserted therein.
In FIGS. 10 and 11 is shown, enlarged, the blade portion of a
driving tool with yet another type of modified central pin
comprising a tube 48 vertically split into a plurality of spaced
apart sections to provide spring tension or resilience against the
wall of hole 32 when inserted therein.
The term "screw" as employed herein in the specification and claims
is intended to embrace all types of headed fasteners and other
elements which are set, tightened, or adjusted by rotation. This
will include wood screws, sheet metal screws, machine screws, and
cap screws, as well as applications wherein a screwhead is adapted
for rotation of control rods and shafts for a wide variety of
purposes.
The term "radial" as applied to the cuneiform cavities in the head
surfaces of the screw of this invention is intended to convey a
description within the limits of available language. The side walls
of these cavities may not be, accurately speaking, true radii since
they may not, or may not if extended, meet at the center of the
screwhead surface. They are shown with opposite sides of the facing
cavities parallel so that the opposite sides of the driving tool
can be parallel and perfect alignment and contact obtained. Their
appearance in the example illustrated is, however, similar to
radiating surfaces and for clarity they are thus described.
Cavities sides as true radii may of course be used, with driver
blades corresponding.
Operation of this invention may be described with reference to
FIGS. 1 to 5. The driving tool or screwdriver blades 16 are engaged
with a screwhead 24 initially with the blades 16 centrally in
cavities 26, and with pin 20 between the screwdriver blades 16
mating with hole 32 in the land 30 between the screwhead cavities
26. Then the screwdriver may be rotated clockwise in FIG. 5 to
drive the screw, and, while driving, the expanded bottom portions
18 of blades 16 will lock under the undercut side walls 28 of
screwhead cavities 26 and prevent any slipping or displacement of
the blades 16 with respect to the screw. To remove the screwdriver,
the blades 16 are backed counterclockwise sufficiently so that they
are centered in cavities 26 from which the blades 16 may now be
readily withdrawn. For withdrawal of the screw, the screwdriver
blades 16 are inserted into the cavities 26 as before and the
screwdriver rotated counter-clockwise as will be obvious. During
the withdrawal the same advantageous locking action between the
screwdriver blades 16 and the screwhead cavities 26 is
obtained.
The embodiments of the driving tool or screwdriver illustrated in
FIGS. 6 to 11 are particularly advantageous for temporarily locking
the screwdriver to a screw. When the central pin is inserted in
hole 32 in the screwhead, the split ring 38 in FIGS. 6 and 7, the
split bulb 44 in FIGS. 8 and 9, or the split tube 48 in FIGS. 10
and 11 expand to grip the inner wall of hole 32 to temporarily lock
the screw and screwdriver together.
The driving tool and fastener of this invention are useful for many
applications in which positive control of the screw by the driving
tool is important. The pin between the driving tool blades makes
for ready alignment of the driver blades when engaged in the
corresponding hole in the screwhead surface. Additionally resilient
or tension means incorporated into the driving tool pin provides
temporary locking together of the screw and screwdriver. While the
inner edges of the driving tool blades will contact the outer edges
of the screw central land and to a degree pilot these elements into
proper relationship, the pin and hole combination of this invention
provides positive, strong piloting and guiding effect.
Additionally, when the driving tool pin is longer than the height
of the driver blades it will enter its mating hole in the screw
before the blades enter the screwhead cavities, thus providing
proper alignment before blade and screw contact. This may be more
important when the driving tool is power driven or automatically
operated and when it might be disadvantageous for rotating force to
be applied before the screw and driving blades are properly
aligned.
The driver central pin, when inserted in its mating hole in a
fastener, also serves to provide longitudinal or axial stability
between the driver and the screw. This is particularly useful when
the driving tool is power or automatically operated and also when
the driving tool is provided with a right angle handle for exerting
powerful torque. Under these conditions, it is advantageous to
provide the pin and hole for central alignment and accurate bearing
so that the pin acts as a type of central shaft for guidance and
control while the blades can exert full unrestricted rotative
power. The embodiment in which the pin is of greater length than
the driver blade height provides additional bearing area for even
greater central alignment and axial stabilization.
Provision of resilient means in the driver pin construction is
valuable for use with any embodiment wherein a temporary locking of
the screw onto the driver blades may be required, such as fastening
assemblies under weightless conditions or the like. Various
resilient mechanisms may be employed including springs, resilient
expanding assemblies or resilient materials such as rubber or
neoprene in suitable configurations, as will be apparent. This
feature is important since the driving tool can be used for
one-handed operation and the screw accurately guided into its
threaded mating piece. Thus the fastener can be accurately guided
into proper position even in remote or difficult-of-access
locations and at the same time is held in positive, accurate
alignment with the driving tool. When torque is applied the driver
pin holds the fastener in proper axial position for most effective
application of rotative driving force. After driving, the driving
tool blades and the central pin can readily be withdrawn from the
screw.
* * * * *