Hole cutter

Details Hole cutter Hole cutter

2002-06-13

2004-01-13

Eley, Timothy V. (Department: 3724)

Bleaching and dyeing; fluid treatment and chemical modification

Treatment of hides, skins, feathers and animal tissues

Tanning

C083S851000, C408S204000

Reexamination Certificate

active

06676711

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to improvement of cutting edges of blades of a hole cutter in which each one of the blades is disposed alternately with a corresponding one of grooves in a rotational direction of the hole cutter.
FIGS.
6
(
a
) to
8
show a prior art hole cutter. With reference to FIGS.
6
(
a
) and
6
(
b
), the hole cutter includes a cylindrical blade body
2
with an inner hollow space
9
. Blades
4
and grooves
5
are located at a circumferential wall of the blade body
2
. Each one of the blades
4
is disposed alternately with a corresponding one of the grooves
5
in a rotational direction of the blade body
2
. Referring to
FIG. 7
, a cutting edge
8
of each blade
4
includes an outer cutting edge
10
, an inner cutting edge
11
, and a stepped cutting edge
12
, which is located between the outer cutting edge
10
and the inner cutting edge
11
. More specifically, in each cutting edge
8
, the outer cutting edge
10
extends from an outermost point
13
to a corner portion
14
in a radial direction Y of the blade body
2
. The inner cutting edge
10
extends from an intermediate point
15
to an innermost point
16
in the radial direction Y. The stepped cutting edge
12
extends from the corner portion
14
to the intermediate point
15
in a rotational direction X of the blade body
2
. That is, the outer cutting edge
10
and the inner cutting edge
11
of each cutting edge
8
are located slightly offset from each other in the rotational direction X.
With reference to
FIG. 7
, the heights H
15
of the intermediate points
15
, which are located at radial outer positions of the inner cutting edges
11
, are equal for all blades
4
. Also, the heights H
13
of the outermost points
13
, which are located at radial outer positions of the outer cutting edges
10
, are equal for all blades
4
. The heights H
13
and H
15
are measured along the rotational axis
1
a
of the blade body
2
with respect to a predetermined reference plane P, which is shown in FIG.
6
(
a
).
With reference to FIGS.
6
(
a
),
8
(
a
), and
8
(
b
), when the blade body
2
is rotated as abutted against a machining material M, the machining material M is cut first by the inner cutting edge
11
of each blade
4
and then by the outer cutting edge
10
after a slight delay. FIG.
8
(
a
) shows a momentary state in which the cutting amount with respect to the machining material M is maintained at a constant level. In this state, all inner cutting edges
11
and outer cutting edges
10
cut the machining material M to a uniform depth {circle around (1)} at the same time. FIG.
8
(
b
) shows a momentary state in which the cutting amount with respect to the machining material M is gradually increased from the state of FIG.
8
(
a
). In this state, like the state of FIG.
8
(
a
), all inner cutting edges
11
and outer cutting edges
10
cut the machining material M to a uniform depth {circle around (2)} at the same time. This increases anti-cutting resistance, which is disadvantageous.
SUMMARY OF THE INVENTION
Accordingly, it is an objective of the present invention to reduce anti-cutting resistance and obtain an optimal cutting state.
To achieve the foregoing and other objectives and in accordance with the purpose of the present invention, the invention provides a hole cutter. The hole cutter includes a cylindrical blade body with a rotational axis. The blade body includes a plurality of blades and a plurality of grooves, and each of the blades is arranged alternately with a corresponding one of the grooves around the rotational axis of the blade body. Each of the blades includes a cutting edge formed at an end of the blade. The blades include multiple types of blades with cutting edges that have different heights with respect to a predetermined reference plane perpendicular to the rotational axis.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.


REFERENCES:
patent: 2412433 (1946-12-01), Taylor
patent: 3609056 (1971-09-01), Hougen
patent: 4322188 (1982-03-01), Hougen
patent: 4586857 (1986-05-01), Ohmi
patent: 4758120 (1988-07-01), Bijl
patent: 4952102 (1990-08-01), Hougen
patent: 5240357 (1993-08-01), Omi
patent: 5417526 (1995-05-01), Stock et al.
patent: 5988956 (1999-11-01), Omi et al.

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