Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Externally threaded fastener element – e.g. – bolt – screw – etc. – Head driving structure
Reexamination Certificate
2000-05-26
2001-10-16
Wilson, Neill (Department: 3627)
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Externally threaded fastener element, e.g., bolt, screw, etc.
Head driving structure
C411S410000, C411S919000
Reexamination Certificate
active
06302632
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a drive recess formed in the head top surface of a screw, and more particular to a novel compound drive recess permitting the screw to drive various types of drive bits, such as Slot, Phillips (cross), Square, Pozi, and Cross-square. In addition, this invention also can be driven by its tailor-made drive bit (U.S. patent Ser. No. 09/373,022) which gives the compound drive recess the capacity to withstand high driving torques with minimal drive bit slip or cam-out. This invention also relates to screws with compound recesses of U.S. Ser. No. 09/193,489 which has been abandoned.
2. Description of the Related Art
Currently, conventional screws or bolts include a variety of head types, such as countersunk, oval, pan, truss, etc., which can adapt to at least five kinds of drive recesses as shown in
FIG. 1
,
2
,
3
,
4
and
5
. Element A in
FIG. 1
is a slot; element B in
FIG. 2
is a cross; element C in
FIG. 3
is a cross-square combination; element D in
FIG. 4
is a square; and element E in
FIG. 5
is a Pozi. Drive recess structures like those mentioned above cannot stand comparatively large torques due to their structural weakness and uneven pressure distribution. The loose fit between the drive recess and the drive bit, which are very common in the above mentioned drive recesses, may produce a large torque causing impaired drive recess or broken drive bit.
U.S. Pat. No. 3,575,080 titled “FASTER WRENCHING MEANS” includes recess composed of inner portions of the pockets (
13
,
14
and
15
); web surface (
19
,
20
and
21
), and a central portion (
22
). This type of recesses limits the range of available drive bits such as slot drive bits (FIG.
6
), cross-square drive bits (FIG.
10
), and Phillips drive bits (FIG.
12
), and Pozi drive bit (FIG.
14
).
Next, U.S. Pat. No. 3,108,623 and 4,187,892 cannot be driven by a drive bit with a fan-shaped tip.
SUMMARY OF THE INVENTION
The drive recesses of the present invention possess the following two features:
A) withstand comparatively large driving torques with high retention of the drive bit; and
B) enable the drive recesses to be driven by various types of drive bits.
This compound drive recess is formed in the top surface of a screw head, which consists of four symmetrical fan-shaped portions, a center square portion and eight chamfer edges intermediate the center square portion and each of the fan-shaped portions. Another version of this compound drive recess consists of all the structures except the eight chamfer edges.
Further objects, features and advantages of the present invention will become apparent from the following detailed description of the invention taken in conjunction with the accompanying drawing wherein like reference numerals designate like elements throughout the several views.
REFERENCES:
patent: 2445978 (1948-07-01), Stellin
patent: 3575080 (1971-04-01), Hannay
patent: 5020954 (1991-06-01), Dreger
Bacon & Thomas PLLC
Wilson Neill
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