Gear cutting – milling – or planing – Milling – Randomly manipulated – work supported – or work following device
Reexamination Certificate
2000-12-12
2002-07-16
Briggs, William (Department: 3722)
Gear cutting, milling, or planing
Milling
Randomly manipulated, work supported, or work following device
C030S300000, C030S310000, C144S024000
Reexamination Certificate
active
06419428
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to circular hole cutting devices which are used for making holes for passing electric wires or water pipes, for instance, in ceilings, walls or floors in a building or house.
2. Description of the Background Art
FIG. 14
shows an example of a conventionally known circular hole cutting device
100
. This circular hole cutting device
100
comprises a cylindrical attachment
101
, a guide rod
102
passing through the cylindrical attachment
101
at right angles to but at a slight distance from its central axis, and a stopper
103
which is screwed into a curved wall of the cylindrical attachment
101
at right angles to the guide rod
102
in such a way that an extreme end of the stopper
103
comes into contact with the guide rod
102
.
The cylindrical attachment
101
is securely attached to an electric power tool
105
as one end of the cylindrical attachment
101
is fitted over a far end of the electric power tool
105
as illustrated. A bit
104
which is turned at high speeds about a central axis of the electric power tool
105
is detachably fitted to its far end. The physical size of the cylindrical attachment
101
is determined such that the bit
104
protrudes to the outside of the cylindrical attachment
101
when the cylindrical attachment
101
is mounted on the electric power tool
105
.
The guide rod
102
has a pivot shaft
102
a
at one end formed by bending a terminal part of the guide rod
102
at right angles to its main part. The extreme end of the pivot shaft
102
a
is sharply pointed.
The circular hole cutting device
100
thus constructed is used as follows. First, a small center hole is made by the bit
104
at the center of a circular hole to be formed in a ceiling, for instance, operating the electric power tool
105
. Then, with the pivot shaft
102
a
fitted into the center hole, the electric power tool
105
is turned about the pivot shaft
102
a
while turning the bit
104
at a high speed. As the bit
104
moves in a circle all around the pivot shaft
102
a
, the ceiling is cut by the bit
104
so that the circular hole for passing an electric wire or a water pipe, for instance, is made therein.
In the conventional circular hole cutting device
100
, the cylindrical attachment
101
is mounted on the electric power tool
105
as described above. It is to be noted, however, that different types of electric power tools have different shapes. Accordingly, one problem of the conventional circular hole cutting device
100
is that it lacks flexibility in use due to the need to prepare various cylindrical attachments specially designed for use with different types of electric power tools.
Furthermore, when turning the electric power tool
105
about the pivot shaft
102
a
, it is necessary to continuously turn the electric power tool
105
about its own axis so that an operator has to change his or her working posture. This poses another problem of the conventional circular hole cutting device
100
that it involves low labor efficiency.
SUMMARY OF THE INVENTION
This invention is intended to solve the aforementioned problems of the prior art. It is therefore an object of the invention to provide a circular hole cutting device featuring high flexibility in use with adaptability to various types of power tools and ease of operation.
According to a principal feature of the invention, a circular hole cutting device which makes a circular hole in an object when turned about a center hole formed in the object comprises a bit holder which can be attached to a drive shaft of an electric power tool in such a way that the bit holder with a bit attached to a far end rotates together with the drive shaft on a common axis, a relatively rotatable part fitted to the bit holder relatively rotatably about the axis of the drive shaft, and a pivot shaft which can be inserted into the center hole formed by the bit, wherein the pivot shaft connected to the relatively rotatable part is located at a position offset from the bit in its radial direction.
With this circular hole cutting device, it is possible to form a circular hole whose radius corresponds to the distance between the bit and the pivot shaft in the object by inserting the pivot shaft in the center hole, activating the electric power tool to turn the bit at a high speed, and slowly turning the electric power tool about the pivot shaft with the bit passing through the object so that the bit turning at the high speed cuts the object along a circular path.
The drive shaft of the electric power tool usually has a chuck complying with industrially standardized dimensional specifications. Therefore, the circular hole cutting device of this invention can be connected to practically any electric power tool regardless of its manufacturer or type, so that the circular hole cutting device provides great flexibility in application.
Furthermore, since the relatively rotatable part and the bit holder are connected relatively rotatably with each other, the relatively rotatable part does not rotate together with the drive shaft of the electric power tool even when the relatively rotatable part is turned about the pivot shaft. Accordingly, it is not necessary for an operator to change his or her working posture to turn the circular hole cutting device about its own axis when making a hole in a ceiling, for instance. This would help increase labor efficiency in hole-cutting operation.
REFERENCES:
patent: 3146675 (1964-09-01), Anderson
patent: 3292494 (1966-12-01), Anderson et al.
patent: 4397593 (1983-08-01), Fordeck
patent: 4759666 (1988-07-01), Grab
patent: 5895183 (1999-04-01), McDaniel
patent: 41 25 005 (1993-01-01), None
patent: 41 25 006 (1993-01-01), None
patent: 55-29223 (1980-03-01), None
patent: 57-18088 (1982-04-01), None
patent: 2521081 (1996-12-01), None
Ajimi Kunio
Uemura Akihito
Briggs William
House B.M. Co., Ltd.
Smith Patent Office
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