Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Externally threaded fastener element – e.g. – bolt – screw – etc. – Pilot end having means enhancing fastening or installation
Reexamination Certificate
2000-12-29
2002-08-06
Saether, Flemming (Department: 3627)
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Externally threaded fastener element, e.g., bolt, screw, etc.
Pilot end having means enhancing fastening or installation
C411S387100
Reexamination Certificate
active
06428259
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flat headed screw structure, and more particularly to a flat headed screw structure provided with a scrap draining chute, thereby preventing the scraps from blocking the cut groove opening, so that the screw body may be tapped and locked into a workpiece quickly and conveniently.
2. Description of the Related Prior Art
A first conventional flat headed screw in accordance with the prior art shown in
FIGS. 1 and 2
comprises a screw body
1
defining a groove
3
having two cut edges
301
and a groove opening
5
. The two cut edges
301
are straight edges, and the groove opening
5
is substantially 90 degree, so that the tangent angle &thgr; between the outer periphery of the screw body
1
and the cut edge
301
is greater than or equal to 90 degree. In such a manner, when the screw body
1
is tapped into a workpiece to a depth exceeding the length of the groove
3
, the scrap produced from the workpiece will block the groove opening
5
, thereby greatly decreasing the cutting effect and velocity of the two cut edges
301
of the groove
3
. In addition, the screw body
1
is subjected to a larger torque due to the blocked scrap, so that the screw body
1
is easily worn out during a period of utilization, thereby decreasing the lifetime of the screw body
1
.
A second conventional flat headed screw in accordance with the prior art shown in
FIGS. 3 and 4
comprises a screw body
2
defining a groove
4
having two cut edges
401
and a groove opening
6
. The two cut edges
401
are inclined edges, and the groove opening
6
is substantially 90 degree, so that the tangent angle &thgr; between the outer periphery of the screw body
2
and the cut edge
401
is greater than or equal to 90 degree. In such a manner, when the screw body
2
is tapped into a workpiece to a depth exceeding the length of the groove
4
, the scrap produced from the workpiece will block the groove opening
6
, thereby greatly decreasing the cutting effect and velocity of the two cut edges
401
of the groove
4
. In addition, the screw body
2
is subjected to a larger torque due to the blocked scrap, so that the screw body
2
is easily worn out during a period of utilization, thereby decreasing the lifetime of the screw body
2
.
SUMMARY OF THE INVENTION
The present invention has arisen to mitigate and/or obviate the disadvantage of the conventional flat headed screw.
The primary objective of the present invention is to provide a flat headed screw structure which is provided with a scrap draining chute, thereby preventing the scraps from blocking the cut groove opening so as to drain the scraps conveniently, so that the screw body may be tapped and locked into a workpiece quickly and conveniently.
In accordance with one aspect of the present invention, there is provided a flat headed screw structure comprising: a screw body, the screw body having an axle face formed with an axially extended thread, and having a tail end provided with at least one cut groove;
the improvement comprising:
the cut groove having a top defining a cut groove opening, the cut groove opening further defining a scrap draining chute toward a center of the screw body, the scrap draining chute extending into an inner portion of the screw body and exceeding a central line of the screw body through a predetermined angle, thereby preventing scraps from blocking the cut groove opening.
Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.
REFERENCES:
patent: 3094893 (1963-06-01), Lindstrom
patent: 3648560 (1972-03-01), Roser
patent: 4028987 (1977-06-01), Wilson
patent: 4271554 (1981-06-01), Grenell
patent: 4386882 (1983-06-01), Bereiter
patent: 4697969 (1987-10-01), Sparkes
patent: 2551510 (1977-05-01), None
Chen Chin-Sun
Yu Chao-Hsin
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