Note: Descriptions are shown in the official language in which they were submitted.
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Background of the Invention
The present invention relates to a swinging blade guard
assembly for a motor driven saw blade, and more particularly, a
swinging blade guard assembly that provides controlled exposure
of the saw blade, as may be desired, from an upper at rest to a
lower operational position.
Powered or compound miter saws are used for the miter and
bevel cutting of wood, metals, and plastics in a variety of
industries. For example, in the construction industry,
moldings, door frames, chair rails and the like must be miter
cut at the corners, and in addition, a combined miter/bevel cut
is required in certain instances for the proper fitting of
parts. In such powered or compound miter saws, blade guards are
used to enclose the blade, typically an upper fixed blade guard
and a lower swinging blade guard that uncovers the rotating
motor driven saw blade when moved from the upper at rest to a
lower operational position where cutting of the workplace takes
place.
The present invention is directed specifically to a new
and improved swinging blade guard assembly which overcomes some
of the problems associated with prior art devices. Examples of
powered miter saws with swinging blade guards are shown, for
example, in U.S. Patent Nos. 4,805,504 and 5,020,406. In each of
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these patents, the lower portion of the motor driven saw blade
is fully covered when the motor driven saw blade is in an upper
at rest position. Each of these patents also rotate the lower
guard during the downward or operational stroke of the motor
driven saw blade to its cutting position.
One of the problems associated with the swinging blade
guard assemblies of the prior art is that the swinging blade
guard does not rotate rapidly enough during the first part of
the downstroke of the motor driven saw blade, in order to enable
the swinging blade guard to clear a workpiece, especially when
performing a bevel cut. At the same time, the swinging blade
guard should not rotate so far that it exposes the front of the
motor driven saw blade above the workpiece, any more than
necessary. The prior art is thus restricted because it does not
provide variable or controlled exposure of the motor driven saw
blade during various phases of the downward or operational
stroke of the motor driven saw blade particularly, in connection
with bevel cuts for which they were not designed.
The present disclosure meets the problems associated with
the prior art for powered miter sa-~s and other types of motor
driven saw blades used in other types of saw constructions which
are moved from an upper to a lower position in cutting
workpieces.
Among the several objects and advantages of the present
disclosure are included:
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~ The provision of a new and improved swinging blade guard
assembly for a motor driven saw blade movable from an upper at
rest to a lower operational position, which overcomes the
aforenoted deficiencies of prior art devices;
The provision of the aforementioned new and improved
swinging blade guard assembly which provides variable or
controlled exposure of the motor driven saw blade during movement
from an upper at rest to a lower operational position;
The provision of the aforementioned new and improved
10 swinging blade guard assembly which rotates a swinging blade
guard assembly rapidly through the first portion of blade travel
in order to clear a workpiece to be cut, with subsequent slower
rotation during the remaining travel of the motor driven saw
blade and eventual stopping of the guard rotation at the desired
15 position;
The provision of the aforementioned new and improved
swinging blade guard assembly in which a pivoting elongated link
has a pre-configured slot and slidable pin combination that
cooperates with a roller that engages a pre-configured shoulder
20 on the elongated link to provide the aforementioned variable or
controlled opening of the swinging blad~ guard assembly;
The provision of the aforementioned new and improved
swinging blade guard assembly which also facilitates access to
the motor driven saw blade shaft for removing or changing the saw
25 blade; and
The provision of the aforementioned new and improved
swinging blade guard assembly which is easy and practical to use
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and operate, simple and inexpensive to maintain and repair, is
extremely durable and long lasting in construction, is
relatively inexpensive permitting individual purchase and
ownership thereof, and is otherwise well adapted for the
purposes intended.
Briefly stated, the swinging blade guard assembly here
described is designed for use with a motor driven saw blade,
such as in a powered or compound miter saw or the like. The
swinging blade guard assembly includes a supporting arm
pivotally mounted at one end to a frame support with the
rotatably mounted motor driven saw blade at an opposite end of
the supporting arm. The motor driven saw blade is movable about
the pivotal mounting of the supporting arm from an upper at rest
to a lower operational position. An upper blade guard is fixed
to the supporting arm for encasing upper areas of the saw blade
on a permanent basis, while the lower swinging blade guard is
pivotally mounted to the upper blade guard for fully covering
the blade when in its at rest position and for exposing the saw
blade when moved to its operational position. An elongated link
is pivotally attached at one end to the frame support and
includes a pre-configured slot at an opposite end which
receives a slidable pin that is attached to a lower
swinging blade guard adjacent the pivotal mounting of
the lower swinging blade guard to the upper blade guard. A
bearing element is attached to the upper blade guard in
laterally spaced relationship to the pin for engaging
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~~the upper surface of the elongated link. As a result of the
aforementioned construction, rotation of the saw blade from an
upper at rest to a lower operational position causes the bearing
to press against the side of the elongated link while also
causing edge surface areas surrounding the pre-configured slot in
the elongated link to press against the slidable pin to rotate
the lower swinging blade guard for exposure of the saw blade.
The upper surface of the elongated link includes a
pre-configured shoulder which cooperates with the pre-configured
slot to control the exposure of the lower swinging blade guard
relative to the saw blade. The pre-configured shoulder and
pre-configured slot are constructed to facilitate rapid rotation
of the lower swinging blade guard and exposure of the saw blade
relative to a workpiece during initial downward movement of the
motor driven saw blade, with subsequent slower rotation of the
lower swinging blade guard and slower exposure of the saw blade
during the remainder of the motor driven saw blade travel. The
pre-configured slot includes upper and lower slot sections
connected by an intermediate curvilinear slot section, and the
pre-configured shoulder includes upper and lower surface areas
connected by an intermediate inclined s-~rface area.
The lower swinging blade guard is pivotally mounted on
the upper blade guard in an eccentrically offset position
relative to a saw blade shaft rotatably supporting the motor
driven saw blade. The eccentrically offset pivotal mounting of
the lower swinging blade guard is located on a detachable
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mounting plate that also pivots on a second eccentrically offset
pivot mounting when detached from the upper blade guard to
facilitate access to the saw blade shaft for removing or
changing the saw blade. The slidable pin is mounted on the
lower swinging guard ret~in;ng plate.
Embodiments of the invention will now be described with
reference to the accompanying drawings wherein:
Figure 1 is a side elevational view of a powered miter saw
with a motor driven saw blade including the new lower swinging
blade guard assembly in the full raised or at rest position;
Figure 2 is also a side elevational view of the powered
miter saw employing the swinging blade guard assembly
illustrated in ~igure l where the motor driven saw blade is
moved a short distance downward in its travel while the lower
swinging blade guard assembly is rapidly rotated open to clear a
workpiece during the first portion of the travel of the motor
driven saw blade;
Figure 3 is another side elevational view of the powered
miter saw employing the swinging blade guard assembly where the
motor driven saw blade is moved to a further downward position
with the lower swinging blade guard assembly rapidly and
substantially opened to expose the saw blade for cutting, while
still covering a substantial portion of the saw blade along the
front or operator side of the powered miter saw;
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Figure 4 is a further side elevational view of the powered
miter saw employing the swinging blade guard assembly with
further downward travel of the motor driven saw blade and even
further exposure of the saw blade to the workpiece for cutting
thereof, while still partially covering the front or operator
side o~ the saw blade;
Figure 5 is a still further side elevational view of the
powered miter saw with the swinging blade guard assembly where
the motor driven saw blade is in its full down position for
workpiece cutting, with the swinging lower blade guard assembly
still providing front or operator side protection above the
workpiece, as illustrated;
Figures 6-10 are side elevational views of the powered
miter saw with swinging blade guard assembly illustrating on a
single sheet of paper the full range of upper at rest to lower
operational positions, including during the various phases of
movement, as previously illustrated in Figures 1-5 of the
drawings; and
Figure 11 is an enlarged side elevational view of the
powered miter saw with the swingin~ blade guard assembly in an
upper at rest position and further illustrating the manner in
which a swinging blade guard assembly is detachably mounted to
an upper blade guard for access to the saw blade shaft to
facilitate removal or replacement thereof.
Corresponding reference numerals will be used throughout
the various figures of the drawings.
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Description of the Preferred Embodiments
The following detailed description illustrates the
invention by way of example and not by way of limitation. This
description will clearly enable one skilled in the art to make
and use the invention, and describes several embodiments,
adaptions, variations, alternatives and uses of the invention,
including what I presently believe is the best mode of carrying
out the invention.
Although the swinging blade guard assembly is shown and
described in connection with a powered or compound miter saw, it
is to be understood that the swinging blade guard assembly of
the present invention may be used with other types of rotating
saw constructions which are moved from an upper to a lower
position, as will be apparent.
Figures 1-5 are shown on several sheets of the drawings
and illustrate various positions of the swinging blade guard
assembly from an upper at rest to a lower operational position,
while Figures 6-10 illustrate, on a single sheet, the same
positions illustrated in Figures 1-5, in order to facilitate
quick review of the various positions of the swinging blade
guard assembly on a single sheet of drawings. Figure 11
illustrates a disassembled position of the swinging blade guard
assembly to facilitate access to the saw blade shaft for removal
or replacement of the saw blade.
As discussed above, the new swinging blade
guard assembly is constructed to provide variable or
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controlled exposure of the saw blade, as may be desired, from an
upper at rest to a lower operational position. As will now be
discussed, this enables early and rapid rotation of the swinging
blade guard assembly during the first part of the downward
stroke of the saw blade, in order to clear a workpiece to be
cut, especially when performing a bevel cut or for thicker
workpieces. As will be appreciated, the swinging blade guard
assembly, at the same time, should not rotate so far as to
expose the front or operator side of the saw blade above the
workpiece any more than is nececs~ry. Subsequent downward
movement of the saw blade exposes the saw blade at a slower rate
until movement of the swinging blade guard assembly is stopped.
For a complete description of the powered or compound
miter saw apparatus, reference is made to applicant's U.S.
patent 5,181,448 in order to understand the various operating
components of the powered or compound miter saw.
Attention can now be focused on the swinging blade
guard assembly that is used in connection with the powered or
compound miter saw 1 illustrated in the drawings.
The powered or compound miter saw 1 includes a motor
driven saw blade 3 which is rotatably mounted within a fixed
upper blade guard and housing 5 and is power driven by an
electric motor (not shown) that is mounted to the non-visible
side of the upper blade guard and housing 5. The upper blade
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guard and housing 5 is fixedly mounted to a supporting arm 7
that is pivotally mounted at 9 to a frame support such as upper
closed cylinder 11 in a pair of transversely extending closed
cylinders 11, 13, the latter being mounted to a turntable 15
shown only in diagrammatic form in the drawings. Again,
reference is made to applicant's aforementioned U.S. patent
5,181,448 for a more specific description and illustration of
such components, including the motor.
The upper blade guard and housing 5, with the electric
motor (not shown) are both mounted to the pivotally mounted
supporting arm 7, with the saw blade shaft 17 extending through
the supporting arm 7 for rotatably mounting the saw blade 3
within the upper blade guard and housing 5, as illustrated in
the drawings.
For collecting dust and other debris generated from cut
workpieces, a dust bag (not shown) may be attached to an exhaust
outlet 19 at the rear of the upper blade guard and housing 5,
while a handle 21, for raising and lowering the power driven saw
blade between an upper at rest and lower operational position,
is mounted to the front or operator side of the power miter saw
apparatus 1.
The fixed upper blade guard and housing 5, along with
the supporting arm 7, are pivotally mounted at 9 to the
supporting frame, including transversely extending closed
cylinders 11, 13, for movement of the rotatably driven saw blade
3 from an upper at rest position to a lower operational or full
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-cut position. As the rotatably driven saw blade 3 is moved from
the upper at rest to the lower operational position, in the
sequential illustrations of Figures 1-5 and the single sheet of
drawings containing Figures 6-10, the lower swinging blade guard
assembly 23 provides a variable or controlled exposure of the
rotatably driven saw blade 3, as will now be described.
The swinging blade assembly generally identified at 23
includes a molded plastic housing 25, molded as illustrated in
the drawings as a transparent plastic cover or shroud that
surrounds the rotating saw blade 3. The molded plastic cover 25
is pivotally mounted to the fixed upper blade guard 5 at the
swinging blade guard pivot point 27. The swinging blade guard
pivot point 27, as best seen in Figure 11 of the drawings, is
part of a detachable mounting plate 29. Note in Figure 11 that
the detachable mounting plate 29 may be rotated or pivoted about
the rivet or other fastener 31, shown in dotted lines, when it is
desired to obtain access to the saw blade shaft 17, for removal
or replacement of the saw blade. The detachable mounting plate
29 is rotated from the blade changing or removal position shown
in Figure 11 to that illustrated in Figures 1-5 and 6-lO of the
drawings where an outer finger or hook 33 is received over a
screw 35 attached to the upper blade guard 5.
The pivot point 27 for the lower swinging blade guard 25
is mounted within a ring support 37 that is positioned by spaced
bosses 39 and secured to the detachable mounting plate 29 by a
suitable fastener through pivot point 27. It will be seen that
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pivot point 27 is eccentrically offset from the saw blade shaft
17, with the detachable mounting plate 29 also eccentrically
offset on a second pivot mounting 31 when the detachable
mounting plate 29 is detached from the upper blade guard 5, as
illustrated in Figure 11 of the drawings.
A torsional or coil spring (not shown) is used to normally
urge the swinging blade guard 25 into a closed position fully
covering the saw blade 3 when in its upper at rest position as
shown in Figure 1. The type of torsional or coil spring
employed is illustrated in Figure 12 of U.S. Patent No.
4,934,233 where a torsional spring is mounted between the lower
swinging blade guard and the detachable mounting plate for
normally resiliently biasing the lower swinging blade guard to
fully cover the motor driven saw blade 3 when in its at rest
position. The same type of torsional or coil spring will be
utilized for the same purpose in the present construction. As
the motor driven saw blade 3 is moved from its at rest position
shown in Figure 1, in a downward stroke to its lower operational
position as sequentially illustrated in Figures 2-5, the present
device employs an actuator arm cr ~ ngated link combined with
other components to overcome the normal resilient bias of the
torsional or coil spring (not shown) to provide controlled
exposure of the motor driven saw blade 3.
Specifically, the present device employs an elongated link
41 pivotally attached to an upstanding flange or ear 43 forming
part of the frame support. At the opposite end of the
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~longated link 41, there is a pre-configured slot 45 that
receives a slidable pin 47 attached to the lower swinging blade
guard adjacent to the pivotal mounting 27 of the lower swinging
blade guard 25. Specifically, the slidable pin 47 is mounted to
the ring support 37 surrounding the pivot support 27, as is
clearly illustrated in the drawings. A bearing element 49 is
attached to the upper blade guard 5 in laterally spaced
relationship to the slidable pin 47 for engaging an upper surface
of the elongated link 41.
It will also be noted that the pre-configured slot 45
includes upper and lower slot sections 51, 53 connected by an
intermediate curvilinear slot section 55. The upper surface 57
of the elongated link 41 includes a pre-configured shoulder 59
that defines an intermediate inclined surface area between upper
and lower surface areas 61, 63 on the upper surface S7 of the
elongated link 41.
With the above construction, movement of the saw blade 3
from an upper at rest to a lower operational position,
sequentially illustrated in Figures 1-5 and 6-10 of the drawings,
causes the bearing 49 to press against an upper surface 57 of the
elongated link 41, while causing edge surface areas surrounding
the pre-configured slot 45 in the link 41 to press against the
slidable pin 47 for rotating the lower swinging blade guard 25
against the resilient or biasing force of the torsional or coil
spring (not shown), thus exposing the saw blade 3.
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~ The upper surface 57 of the elongated link 41 includes a
pre-configured shoulder 59 which cooperates with the
pre-configured slot 45 to control the exposure of the lower
swinging blade guard relative to the saw blade. In other words,
S by adjusting the shape of the pre-configured slot 45 with the
upper surface 57 of the elongated link, the incremental motion
and movement of the lower swinging blade guard 25 can be
controlled, as desired.
In the embodiment illustrated in the drawings, it will
be noted that the pre-configured shoulder 59 is an intermediate
inclined surface area between upper and lower surface areas 61,
63, all of which cooperate with the upper and lower slot sections
51, 53 and the intermediate curvilinear slot section 55 of the
pre-configured slot. The arrangement of the pre-configured
shoulder and the pre-configured slot in the illustrated
construction facilitates rapid rotation of the lower swinging
blade guard 25 to expose the saw blade 3 relative to a workpiece
during initial downward movement of the motor driven saw blade 3,
with subsequent slower rotation of the lower swinging blade guard
25 and slower exposure of the saw blade 3 during the remainder of
the motor driven saw blade travel.
This can be understood by comparing the position of the
lower swinging blade guard 25 when the saw blade 3 is in an upper
at rest position, as shown in Figure 1, with the relative
position of the lower swinging blade guard 25 relative to the saw
blade 3 when the supporting arm 7 is rotated about pivot point 9
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to an approximate 5 downward position as illustrated in
Figure 2. In the Figure 1 illustration, the lower swinging
blade guard 25 fully covers the portion of blade 3 not covered
by the upper guard. However, when rotated approximately 5
downward as shown in Figure 2 of the drawings, it will be noted
that the lower swinging blade guard 25 is rotated approximately
34 open by action of the bearing element 49 on the upper
surface 57 of the elongated link 41, together with the slidable
movement of the pin 47 in the pre-configured slot 45.
When rotated about the pivot point 9 approximately 15
downward as illustrated in Figure 3 of the drawings, the lower
swinging blade guard 25 is rotated approximately 86 open, thus
showing the rapid rotation of the lower swinging blade guard 25
and exposure of the saw blade 3 to a workpiece during initial
lS downward movement of the saw blade 3.
In Figure 4 of the drawings, the saw blade 3 is rotated
about pivot point 9 approximately 25 downward, and this enables
the lower swinging blade guard 25 to be rotated approximately
108 open. As will be appreciated, the lower swinging blade
guard 25 has a slower rotation in tfle Figure 4 illustration than
in the Figures 2-3 illustrations, providing slower exposure of
the saw blade 3 near the bottom of the saw blade travel. In
Figure 4, it will be noted that the lower swinging blade guard
25 has a substantial area thereof on the front or operator side
of the saw 1.
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~ In the final illustration shown in Figure 5 of the
drawings, the saw blade 3 is rotated in its full down or
operational position, and it will be seen that the lower swinging
blade guard 25 still provides protection to the operator above
the workpiece, even though the saw blade 3 is fully exposed for
cutting.
Figures 6-10 of the drawings illustrate on a single
sheet and the relative sequential positions of the saw in Figures
1-5, respectively. Comparison of each of Figures 6-10 shows the
relative position of the lower swinging blade guard 25 to the saw
blade 3, for ease of understanding the sequential movements and
positions of the lower swinging blade guard 25 relative to the
saw blade 3.
From the foregoing, it will now be appreciated that the
swinging blade guard assembly of the present invention provides a
variable or controlled exposure of the saw blade in a powered
miter saw or other saw construction, thus meeting the objects,
features and advantageous results of the present invention, as
noted above.
As various changes could be made in the above
constructions without departing from the scope of the invention,
it is intended that all matter contained in the above description
or shown in the accompanying drawings shall be interpreted as
illustrative and not in a limiting sense.
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