Cutlery – Cutting tools – Saw
Reexamination Certificate
2000-12-15
2004-01-27
Shoap, Allen N. (Department: 3724)
Cutlery
Cutting tools
Saw
C030S391000
Reexamination Certificate
active
06681493
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to circular saws, and in particular to portable circular saws that have a saw unit inclining mechanism for laterally inclining or pivoting a saw blade with respect to a workpiece. The saw units may, for example, selectively stop in preferred bevel positions depending upon whether a stopper is set to an operative position or a non-operative position.
2. Description of the Related Art
Known portable circular saws comprise a base adapted to contact a workpiece and a saw unit that has a circular saw blade. A lower portion of the saw blade protrudes downwardly through the base so as to cut the workpiece. The circular saw unit can move vertically relative to the base (i.e. in a direction perpendicular to the rotational axis of the saw blade), so that the downward protruding distance of the saw blade from the base can be changed. Thus, the cutting depth can be adjusted. In addition, the circular saw can laterally pivot relative to the base (i.e. in a lateral direction with respect to the saw blade), so that a bevel cutting operation can be performed with the saw blade laterally inclined relative to the workpiece. The incline angle of the saw blade can also be adjusted.
In general, the lateral pivotal position of the saw unit can be adjusted between a 0° position and a 45° position. In the 0° position, the saw blade is perpendicular to the base or the workpiece, so that a normal (vertical) cutting operation can be performed. In the 45° position, the saw blade is inclined at an angle of 45° relative to the base or the workpiece. This 45° position is most frequently selected when a laterally inclined (bevel) cutting operation is performed. This position is referred to as a “standard inclined position” in this description. A stopper device serves to prevent the saw unit from pivoting from the 0° position to a position less than 0° and also from pivoting from the 45° position to a position more than 45°. Therefore, the operator can easily and reliably position the saw unit at either the 0° position or the 45° position.
U.S. Pat. Nos. 5,433,008 and 4,999,916 teach portable circular saws that have a stopper device to stop the inclination of the saw unit selectively at the standard inclined position and at an extra inclined position, in which the circular saw is inclined by an angle of more than 45°.
FIGS. 1 and 3
of U.S. Pat. No. 4,999,916 have been incorporated into the drawings of this application as
FIGS. 41 and 42
, respectively.
FIGS. 41 and 42
show a front view of a portable circular saw and an enlarged front view of a part of the portable circular saw, respectively. As shown in
FIG. 41
, a portable circular saw
101
comprises a base
102
and a saw unit
104
. A circular saw blade
103
is mounted on the saw unit
104
and serves to cut a workpiece W. The saw unit
104
is laterally pivotable relative to the base
102
by means of a pivot shaft
105
.
An angular plate
121
is secured to the base
121
and has an arc-shaped guide slot
121
a
that extends along an arc about the pivot shaft
105
. A substantially L-shaped second guide slot
121
b
is formed in series with the upper end of the guide slot
121
a.
An angular guide
123
is secured to the saw unit
104
and is pivotally supported by the pivot shaft
105
. A substantially L-shaped guide slot
123
a
is formed in the angular guide
123
. A lock screw
126
is inserted through the guide slot
123
a
of the angular guide
123
and the guide slot
121
a
of the angular plate
121
and is engaged with a nut (not shown).
In order to laterally incline the saw unit
104
or the saw blade
103
from a 0° position shown in
FIG. 41
to a 45° position shown in
FIG. 42
, the operator pivots the saw unit
104
in a counterclockwise direction. The pivotal movement of the saw unit
104
stops at the 45° position when the lock screw
126
abuts the upper end of the guide slot
121
a
of the angular plate
121
. The saw unit
104
can be fixed in this position by tightening the lock screw
126
and the nut so as to fix the angular guide
123
to the angular plate
121
.
In order to further laterally incline the saw unit
104
from the 45° position to a 50° position, the operator must loosen the lock screw
126
and then shift the lock screw
126
into the second guide slot
121
b
of the angular plate
121
. During the movement of the lock screw
126
along the guide slots
121
a
and
121
b
, the lock screw
126
also moves along the guide slot
123
a
of the angular guide
123
. The pivotal movement of the saw unit
104
stops at the 50° position when the lock screw
126
abuts the upper end of the second guide slot
121
b
of the angular plate
121
. The saw unit
104
can be fixed in this position by tightening the lock screw
126
.
FIG. 5
of U.S. Pat. No. 5,433,008 has been incorporated into the drawings of this application as FIG.
43
. As shown in
FIG. 43
, a lateral inclining device
200
comprises an upright guide plate
202
that is secured to a base
201
. An arc-shaped slot
203
is formed in the guide plate
202
. A saw unit (not shown in
FIG. 43
) can pivot about a pivot shaft
205
and has a lock screw
204
that is inserted into the arc-shaped slot
203
and that can move along the arc-shaped slot
203
. A stopper screw
207
is mounted on the guide plate
202
at one end of the arc-shaped slot
203
and opposes the lock screw
204
. A disk member is rotatably mounted on the lock screw
204
and has legs
206
positioned on both sides of the lock screw
204
.
In order to prevent the saw unit from pivoting more than an inclined angle of 45° (i.e., the standard inclined position), the disc is rotated to a position in which one of the legs
206
opposes the stopper screw
204
. The operator then pivots the saw unit, so that one of the legs
206
contacts the stopper screw
204
when the saw unit reaches the 45° position. The operator thereafter tightens the lock screw
204
, so that the saw unit can be fixed in position at the 45° position.
In order to move the saw unit to an extra inclined position that is past the 45° position, the operator must rotate the disk member by an angle of 90° while the stopper screw
204
is disposed within an enlarged end portion
203
a
of the slot
203
, so that the lock screw
204
directly opposes the stopper screw
207
. As a result, the saw unit can be fixed at the extra inclined position as shown in
FIG. 43
, in which the lock screw
204
directly contacts the lock screw
207
.
However, in both the above U.S. patents, in order to change the stop position of the saw unit from the 45° inclined position to the extra inclined position that is more than 45°, or from the extra inclined position to the 45° inclined position, the operator must perform a cumbersome operation. That is, the saw unit can not freely move from the 0° position to the 50° position. Instead, the operator must always stop at the 45° position and adjust the stopper device before moving past the 45° position.
For example, in U.S. Pat. No. 4,999,916, in order to change the stop position, the lock screw
129
must be shifted from the first guide recess
126
to the second guide recess
128
or from the second guide recess
128
to the first guide recess
126
with the lock screw
129
positioned at about the upper end of the first guide recess
126
, in which the saw unit
123
is inclined at an angle of about 45°.
Likewise, in U.S. Pat. No. 5,433,008, in order to change the stop position, the disc must be rotated to change the position of the legs
206
with the stopper screw
204
positioned within the enlarged end portion
203
a
of the guide slot
203
. Thus, the pivotal movement of the saw unit must be first stopped at about the 45° inclined position and then the disc must be rotated to further pivotally move the saw unit.
SUMMARY OF THE INVENTION
It is, accordingly, one object of the present invention to teach improved portable circular saws. Preferably, such portable circular saws can simplify the operation of setting the bev
Mori Shinsuke
Okouchi Katsumi
Dennison, Schultz & Dougherty
Makita Corporation
Prone Jason
Shoap Allen N.
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