Expansion screw

Details Expansion screw Expansion screw

2002-10-04

2004-04-13

Wilson, Neill (Department: 3679)

Expanded, threaded, driven, headed, tool-deformed, or locked-thr

Having separate expander means

Made up of plural expansible segments or sections

C411S038000, C411S061000

Reexamination Certificate

active

06719509

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an improved expansion screw and particularly an expansion screw for securely anchoring on a solid wall or a hollow wall.
2. Description of the Prior Art
There are a wide variety of expansion screws known in the art. In general, they can be grouped in two types as shown in
FIGS. 1 and 2
. In
FIG. 1
, the expansion screw
10
mainly includes a bolt
11
coupling with a washer
12
, a nail tube
13
and a compression cone
14
. The nail tube
13
has a front section formed an expansion section
131
to couple with the smaller end of the compression cone
14
so that when that expansion screw
10
is inserted into a construction hole
21
of a solid wall
20
(as shown in
FIG. 3
) the bolt
11
may be turned and tightened to pull the compression cone
14
into the nail tube
13
and force the expansion section
131
to expand outwards to squeeze the inner wall of the construction hole
21
to form anchoring. Then the bolt
11
may be used to hang or support articles. Such type of expansion screw
10
generally is suitable only for solid walls, but is not desirable for brick walls that have cavities inside.
FIG. 2
illustrates another type of conventional expansion screw
10
′ which includes a bolt
11
′ coupling with a washer
12
′ and a nail tube
13
′. The nail tube
13
′ has a front end fastened to a nut
14
′ to engage with the bolt
11
′. The front section of the nail tube
13
′ forms an expansion section
131
′ which has carved slots formed thereon in an annular manner. When the expansion screw
10
′ is inserted into a construction hole
21
′ of a hollow wall
20
′, the expansion section
131
′ may be expanded to a greater degree than the expansion screw
10
mentioned above. However, it is still difficult to control the expansion section
131
′ to move away from the hollow portion
210
′ of the wall
20
′. It could happen that the extended expansion section
131
′ be located in the hollow portion
210
′ as shown in FIG.
4
and result in not secured coupling with the inner wall of the construction hole
21
′. In practical constructions, it is often difficult to accurately determine whether the interior of a wall is solid or hollow, hence to nail the expansion screw into a wall often cause construction problems. How to resolve the problems occurred to the conventional expansion screws and to design an improved expansion screw that is suitable for solid walls and hollow walls thereby to effectively overcome the troubles in construction is the goal of the present invention.
SUMMARY OF THE INVENTION
The primary object of the invention is to provide an improved expansion screw that is applicable to various types of construction holes formed on a wide variety of solid walls and hollow walls.
Another object of the invention is provide an improved expansion screw that has a plurality of expansion flaps on an expansion section located on the front end of the nail tube to form a double overlap and to generate a double squeeze in the construction hole to achieve a secured fastening.
A further object of the invention is provide an improved expansion screw that has a plurality of expansion sections on the nail tube so that at least one expansion section may be extended to form a tight coupling with the interior structure of the wall to enhance success probability of construction.
In order to achieve the foregoing objects, the invention includes a bolt coupled with a washer and a nail tube which has a front end fastened to a nut. The nail tube has carved slots formed on the middle portion to form at least one expansion section. Between the expansion section and the nut, the nail tube has a plurality of
-shaped slots formed thereon. On an inner side of each
-shaped slot, there is an expansion flap. Each the
-shaped slot borders a longitudinal connection strip to form a bend section. The nail tube beyond the connection strip forms an annular ring with an outer edge formed a plurality of jutting lugs for soldering a nut. The expansion screw thus constructed has at least one expansion section to generate expansion on a plurality of sections.


REFERENCES:
patent: 4657456 (1987-04-01), Anquetin
patent: 4986710 (1991-01-01), Kovarik
patent: 5018919 (1991-05-01), Stephan
patent: 5725341 (1998-03-01), Hofmeister

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