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
2002-09-30
2004-01-06
Saether, Flemming (Department: 3679)
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
active
06672812
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a wood screw, more particularly to a wood screw with a low driving torque requirement.
2. Description of the Related Art
Referring to
FIG. 1
, a conventional wood screw
1
is shown to include a head
11
and a shank
12
extending from the head
11
and formed with a screw thread
13
. It is noted that when the conventional wood screw
1
is in use, a large driving torque is required, which can result in breaking of the same.
To overcome the aforesaid drawback, another conventional wood screw
2
has been proposed heretofore in U.S. Pat. No. 4,874,278, and includes a head
21
, a shank
22
extending from the head
21
, and a chip-removing portion
24
disposed between a tip guide portion
23
and a fastening screw portion
25
of the shank
22
, as best shown in FIG.
2
. In accordance with this design, chips produced at a time when a hole is bored are conveyed and spread toward the side of the shank
22
attached to the head
21
by this chip-removing portion
24
. Therefore, blocking by chips can be prevented, and screw driving with low torque can be achieved.
However, because the structure of the chip-removing portion
24
is difficult to form, a high manufacturing cost cannot be avoided. Moreover, due to the configuration of the chip-removing portion
24
, over-boring can occur and can reduce the holding effect between the wood screw
2
and wood material.
SUMMARY OF THE INVENTION
Therefore, the object of the present invention is to provide a wood screw with a low driving torque requirement, which can be produced at a relatively low cost, and which can maintain a sufficient holding effect with wood material.
According to this invention, a wood screw includes a head part, a tapered insert part, and a shank part disposed between the head part and the tapered insert part and having a shank axis. The shank part has a first shank segment adjacent to the head part, and a second shank segment adjacent to the tapered insert part. The first shank segment has a first radius relative to the shank axis. The second shank segment has a surface that is formed with a screw thread. The screw thread includes interconnected thread sections that have a second radius relative to the shank axis and larger than the first radius. The surface of the second shank segment is further formed with at least one projecting element between two neighboring interconnected ones of the thread sections that are proximate to the tapered insert part. The projecting element has a greatest radial dimension with respect to the shank axis that is greater than the first radius and less than the second radios.
In one embodiment, all of the thread sections on the surface of the second shank segment have the second radius relative to the shank axis.
In another embodiment, the two neighboring interconnected ones of the thread sections on the surface of the second shank segment have a third radius relative to the shank axis that is greater than the first radius and less than the second radius, and remaining ones of the thread sections on the surface of the second shank segment have the second radius relative to the shank axis. Preferably, the third radius is not less than the greatest radial dimension of the projecting element.
REFERENCES:
patent: 2263137 (1941-11-01), Oestereicher
patent: 2371365 (1945-03-01), Tomalis
patent: 4323326 (1982-04-01), Okada
patent: 4834602 (1989-05-01), Takasaki
patent: 4874278 (1989-10-01), Kawashita
patent: 4878793 (1989-11-01), Hewison
patent: 5015134 (1991-05-01), Gotoh
patent: 5827030 (1998-10-01), Dicke
patent: 253960 (1977-04-01), None
Ostrolenk Faber Gerb & Soffen, LLP
Saether Flemming
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