Variable cutting-angle circular saw device

A variable cutting-angle circular saw device includes a base; a rotary table 2 rotatably disposed in the central portion of the base; a bracket liftably attached to a hinge; a motor, a speed reducer, a circular saw, an outer cover, and a safety cover, all being fixed to the bracket; a fence fixed in a rearward position of the base; a clamp fixed at left- and right-hand positions of the device so as to allow a workpiece to be clamped for cutting the workpiece. A sawdust-guiding frame piece is suspended from a lower end of a rear portion of the cover so as to smoothly block a gap between the lower end of the rear portion of the outer cover and an upper surface of a curved portion in the central portion of the fence, guiding the sawdust blowing up via the blow-up port, to the inner side of the rear end of the outer cover. A sawdust accommodating chamber below the rotary table is closed at the bottom and has a substantially arcuate bag-like shape, and communication with the cover via a port at the rear thereof.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a variable cutting-angle circular saw 
device which is generally referred to as a miter saw or a compound miter 
saw. 
2. Description of the Related Art 
FIG. 5 shows a left-hand side elevational view of a conventional variable 
cutting-angle circular saw device. 
This variable cutting-angle circular saw device is arranged as follows: A 
rotary table 2 is rotatably disposed in the central portion of a base 1, a 
hinge 3 is disposed in the rear of the rotary table 2, and a bracket 4 is 
attached to the hinge 3 in such a manner as to be capable of being lifted 
and lowered. Fixed to the bracket 4 are a motor 5, a speed reducer 6, a 
circular saw 7, an outer cover 8, and a safety cover 9. In addition, a 
fence 10 is fixed in a rearward position of the base 1, and a clamp means 
11 is fixed at left- and right-hand positions thereof so as to allow a 
material (hereinafter referred to as the workpiece) w to be cut, such as 
timber, to be clamped. The circular saw 7 is lowered until it enters a 
slit 12 provided in the rotary table 2 so as to cut the workpiece w. 
The compound miter saw is arranged such that the rotary table 2 is 
rotatable to make the miter angle and bevel angle of the circular saw 7 
variable, and the hinge 3 is rotatable about a pin shaft 13 within a 
vertical plane along a transverse direction of the device. 
Accordingly, with the compound miter saw, since the circular saw 7 can be 
inclined with two degrees of freedom, the workpiece w can be cut at 
virtually any diagonal angle. 
With the miter saw, the rotary table 2 is rotatable so as to make the miter 
angle of the circular saw 7 variable, but the hinge 3 is not rotatable. 
Accordingly, since the circular saw 7 can be inclined with one degree of 
freedom, the workpiece w can be cut at an appropriate miter angle with 
respect to the transverse direction of the device as viewed from its top. 
When the circular saw 7 is lowered and the cutting of the workpiece w is 
commenced, until the circular saw 7 enters the slit 12, the sawdust 
produced by cutting is blown up in such a manner as to pass by the inner 
side of the rear end of the outer cover 8 by means of the air flow 
produced by the rotation of the circular saw 7. The sawdust then passes 
through a sawdust blow-out port 15 provided in an upper rear end of the 
outer cover 8, and is discharged to the outside from a sawdust blow-out 
tube (not shown) provided in such a manner as to pass through an upper 
portion of the bracket 4. Accordingly, if the sawdust blow-out tube is 
provided with an air-permeable dust collecting bag, it is possible to 
collect the sawdust without being scattered. From the time the circular 
saw 7 is further lowered and begins to enter the slit 12 and until cutting 
is completed with the circular saw 7 lowered to a position 7', the sawdust 
passes through the slit 12 and is accommodated in a sawdust accommodating 
space 14. 
Accordingly, the collection of the sawdust accommodated in the sawdust 
accommodating space 14 becomes an issue. 
FIG. 6 illustrates a cross-sectional view taken along the line VI--VI in 
FIG. 5. The sawdust accommodating space 14 has its four sides surrounded 
by rib-like vertical walls 2a, 2b elongated in the transverse direction, a 
front-side inclined wall 2c, and an intermediate inclined wall 2d. An 
extreme end of the sawdust accommodating space 14 at the rear end of the 
slit 12 is made open, thereby constituting a sawdust blow-up port 14a. 
Returning now to FIG. 5 to resume the description, the fence 10 is arranged 
such that its central portion corresponding to the circular saw 7 is 
formed as a curved portion 10a for avoiding interference with the circular 
saw 7 by detouring the rear side of the sawdust blow-up port 14a, and the 
wall surface of the curved portion 10a is formed as a conical wall surface 
101 disposed in proximity to an edge of the sawdust blow-up port 14a. 
Accordingly, when the circular saw 7 is lowered in such a manner as to 
enter the slit 12, the sawdust accommodated in the sawdust accommodating 
space 14 is blown up by the air flow caused by the rotation of the 
circular saw 7, in such a manner as to pass the sawdust blow-up port 14a 
and pass by the inner side of the rear end of the outer cover 8. Then the 
sawdust passes through the sawdust discharging blow-out port 15 provided 
in the upper rear end of the outer cover 8, and is discharged to the 
outside through the sawdust blow-out tube provided in the bracket 4. 
In accordance with the above-described conventional variable cutting-angle 
circular saw device, since the gap between the lower end of the rear 
portion of the outer cover 8 and the upper portion of the curved portion 
10a in the central portion of the fence 10 is wide open, it does not 
necessarily follow that the entire volume of the sawdust blown up through 
the sawdust blow-up port 14a will pass through the gap between the lower 
end of the rear portion of the outer cover 8 and the upper surface of the 
curved portion 10a in the central portion of the fence 10. Instead, some 
of the sawdust will be scattered rearwardly of the device. In addition, 
during the initial period of cutting when the cutting of the workpiece w 
is commenced after lowering the circular saw 7, the sawdust is scattered 
low and rearwardly of the upper surface of the workpiece w. In this case 
as well, the sawdust passes through the gap between the lower end of the 
rear portion of the outer cover 8 and the upper surface of the curved 
portion 10a in the central portion of the fence 10, so that cleaning is 
troublesome. 
Meanwhile, the sawdust accommodating space 14 has its lower portion open 
owing to the pattern drawing involved in die casting, and communicates 
with an opening 1a of the base 1. As a result, the dust accommodated in 
the sawdust accommodating space 14 is discharged to the outside through 
the gap in the lower surface of the base 1, so that cleaning is 
troublesome. 
SUMMARY OF THE INVENTION 
Accordingly, an object of the present invention is to provide a variable 
cutting-angle circular saw device as a compound miter saw or a miter saw 
which is capable of preventing the sawdust from scattering rearwardly of 
the device through a gap between the lower end of a rear portion of an 
outer cover and an upper surface of a curved portion in a central portion 
of a fence, and capable of allowing the total volume of sawdust 
accommodated in a sawdust accommodating space to be blown out from a 
sawdust blow-out port at a rear end of a slit, thereby substantially 
enhancing the sawdust recovering efficiency, thereby overcoming the 
above-described drawbacks of the conventional art. 
Another object of the present invention is to provide a variable 
cutting-angle circular saw device as a compound miter saw or a miter saw 
which is capable of preventing the discharge of the sawdust to the 
surroundings of the device from a lower portion of a base so that a large 
volume of sawdust will not scatter to the surroundings of the device, 
thereby facilitating the cleaning. 
To these ends, in accordance with the present invention, there is provided 
a variable cutting-angle circular saw device wherein a rotary table 2 is 
provided rotatably on a base 1, a circular saw 7 rotated by driving means 
is supported on the rotary table 2 in such a manner as to be capable of 
being lifted and lowered, an outer cover 8 for covering an upper portion 
of the circular saw 7 is provided, a fence for receiving a rear surface of 
a material to be cut, such as timber, is provided at a required position 
adjacent to a rear end on the base 1, a linear slit 12 allowing the 
circular saw 7 to pass therethrough is provided in the rotary table 2 so 
as to allow a lower end of the circular saw 7 to be lowered from an upper 
surface of the rotary table 2, a longitudinally elongated sawdust 
accommodating space 14 for accommodating the sawdust is formed on the 
lower side of the slit 12 provided in the rotary table 2, a sawdust 
blow-up port 14a communicating with the sawdust accommodating space 14 is 
provided at a rear end of the slit 12 in an upper surface of the rotary 
table 2, a central portion of the fence 10 is formed as a curved portion 
10a for avoiding interference with the circular saw 7 by detouring a rear 
side of the sawdust blow-up port 14a, a wall surface of the curved portion 
10a is formed as a conical wall surface 101 disposed in proximity to an 
edge of the sawdust blow-up port 14a, 
wherein when the circular saw 7 is lowered and begins to enter the slit 12, 
the sawdust in the sawdust accommodating space 14 is blown up by an air 
flow produced by the rotation of the circular saw 7, in such a manner as 
to pass by an inner side of a rear end of the outer cover 8 via the 
sawdust blow-up port 14a, and is discharged to an outside from a necessary 
exit port, the variable cutting-angle circular saw device being 
characterized in that 
a bottom of the sawdust accommodating space 14 is closed by a cover 16, the 
sawdust accommodating space 14, as viewed from a side of the device, being 
formed into a substantially arcuate bag-like shape, and that 
a sawdust-guiding frame piece 17 is provided in such a manner as to be 
suspended from a lower end of a rear portion of the cover 8 such that, 
when the circular saw 7 is lowered to a maximum level, a gap between the 
lower end of the rear portion of the outer cover 8 and an upper surface of 
the curved portion 10a in the central portion of the fence 10 is blocked 
substantially smoothly, thereby guiding the sawdust blowing up via the 
blow-up port 14a, to the inner side of the rear end of the outer cover 8. 
In operation, when the circular saw 7 is lowered and the cutting of the 
workpiece w is commenced, during the initial period of cutting, sawdust is 
scattered low and rearwardly of the upper surface of the workpiece w. 
However, the sawdust then collides against the sawdust-guiding frame piece 
17, and part of the sawdust is blown up in such a manner as to pass by the 
inner side of the rear end of the outer cover 8, by means of the air flow 
caused by the rotation of the circular saw 7, and is then discharged to 
the outside through the necessary exit port. The remaining portion of the 
sawdust falls down and is collected through the guiding action of the 
conical wall surface 101 of the curved portion 10a in the central portion 
of the fence 10, then passes through the sawdust blow-up port 14a and is 
accommodated in the sawdust accommodating space 14. 
When the cutting by the circular saw 7 reaches the bottom side of the 
workpiece w and the circular saw 7 substantially enters the slit 12, the 
circular saw 7 scrapes up the sawdust accommodated in the sawdust 
accommodating space 14, the sawdust is blown up through the sawdust 
blow-up port 14a by means of the air flow produced by the rotation of the 
circular saw 7. At this time, the sawdust-guiding frame piece 17 is 
lowered to the vicinity of the upper surface of the curved portion 10a in 
the central portion of the fence 10 so as to block the gap. Hence, the 
sawdust blown up through the sawdust blow-up port 14a is blown up in such 
a manner as to pass by the inner side of the rear end of the outer cover 8 
along the conical wall surface 101 and the sawdust-guiding frame piece 17 
before it is discharged to the outside through the necessary exit port. 
Thus, the sawdust is collected without scattering rearwardly over the 
curved portion 10a, and the sawdust in the sawdust accommodating space 14 
is collected without being filled.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIGS. 1 to 4 illustrate an embodiment in which a variable cutting-angle 
circular saw device in accordance with the present invention is applied to 
a compound miter saw. 
This compound miter saw is arranged as follows: A rotary table 2 is 
rotatably disposed on a substantially central portion of a base 1 on which 
a workpiece w, such as timber, can be laid. A bracket 4 is attached to a 
hinge 3 which is disposed from the rear of the rotary table 2 and is 
bolted by a tightening lever 20 so as to be stopped at a transversely 
arbitrary, inclined position. An outer cover 8, a safety cover 9 and power 
means constituted by a motor 5 and a speed reducer 6, are fixed to the 
bracket 4 in such a manner as to be located above the rotary table 2. A 
circular saw 7 rotated by the power means is rotatably supported to the 
bracket 4 so that the circular saw 7 can be located above the rotary table 
2. The outer cover 8 covers an upper portion of the circular saw 7. The 
safety cover 9 is adapted to rotate upwardly of a front end of the outer 
cover 8 through the action of a link with the lowering of the circular saw 
7 and enter the inside of the outer cover 8 so as to expose a lower 
portion of the circular saw 7 and ensure cutting by the circular saw 7. 
After the circular saw 7 is positioned to an appropriate posture, if the 
saw is rotatively driven and lowered, then the workpiece w, such as 
timber, fixed by a clamp means 11 can be cut. 
A fence 10 extending transversely is located in the vicinity of a rear end 
of an upper surface of the base 1 and is arranged to receive a rear side 
surface of the workpiece w. The clamp means 11 is provided in such a 
manner as to fix the upper surface of the workpiece w. 
A linear slit 12 for allowing the circular saw 7 to pass therethrough is 
provided in the rotary table 2 so as to permit the lower end of the 
circular saw 7 to be lowered to a position 7' lower than the upper surface 
of the rotary table 2. A transversely elongated sawdust accommodating 
space 14 for accommodating sawdust is formed on the lower side of the slit 
12 of the rotary table 2. 
A sawdust blow-up port 14a communicating with the sawdust accommodating 
space 14 is provided in the rear end of the slit 12 in the upper surface 
of the rotary table 2. The central portion of the fence 10 serves as a 
curved portion 10a for avoiding interference with the circular saw 7 by 
detouring the rearside of the sawdust blow-up port 14a. The wall surface 
of the curved portion 10a is formed as a conical wall surface 101 located 
in proximity to an edge of the sawdust blow-up port 14a. 
FIG. 4 shows a cross-sectional view taken along the line IV--IV in FIG. 3. 
The three sides of the sawdust accommodating space 14 are surrounded by 
rib-like vertical walls 2a, 2b located on the left- and right-hand sides 
of the slit 12 and formed into an arcuate configuration and by a 
front-side inclined wall 2C (see FIG. 3). An opening between the rib-like 
vertical walls 2a, 2b serves as a bag-like space enclosed by a cover 16. 
An extreme rear end of the slit 12 is made open, serving as the sawdust 
blow-up port 14a. 
On the upper side of the sawdust accommodating space 14, synthetic 
resin-made edge plates 19a, 19b having a hardness sufficient to allow the 
edge plates to be cut by the circular saw 7 are bolted to the rotary table 
2. The space between the edge plates 19a, 19b constitutes the slit 12. The 
slit 12 has its cross section formed into a required trapezoid of a 
required minimum configuration for allowing the circular saw 7 set 
vertically or inclined at a maximum bevel angle to pass therethrough. 
Accordingly, the sawdust accommodated in the sawdust accommodating space 14 
through the slit 12 is arranged to be blown upward through the sawdust 
blow-up port 14a by means of the air flow caused inside the sawdust 
accommodating space 14 as the circular saw 7 enters the sawdust 
accommodating space 14 through the slit 12. As a result, the arrangement 
provided is such that the sawdust scraped off and scattered by the 
circular saw 7 will not easily escape upwardly through the slit 12. 
A sawdust-guiding frame piece 17, whose horizontal cross section is a 
groove type with the groove facing the front side, is suspended from a 
lower end of a rear portion of the outer cover 8. When the circular saw 7 
is lowered to a maximum level, the sawdust-guiding frame piece 17 is 
adapted to block substantially smoothly the gap between the lower end of 
the rear portion of the outer cover 8 and the upper surface of the curved 
portion 10a in the central portion of the fence 10, and serves to guide 
the sawdust being blown up through the sawdust blow-up port 14a to the 
inner side of the rear end of the outer cover 8. Then, the sawdust blown 
up in such a manner as to pass by the inner side of the rear end of the 
outer cover 8 passes through a sawdust blow-out port 15 provided in the 
rear end of the upper portion of the outer cover, and is discharged 
through a sawdust blow-out tube 18 provided in the bracket 4. An 
air-permeable dust collecting bag H for collecting the sawdust is attached 
to the sawdust blow-out tube 18. 
Accordingly, when the circular saw 7 is lowered and the cutting of the 
workpiece w is commenced, during the initial period of cutting, the 
sawdust is scattered low and rearwardly of the upper surface of the 
workpiece w, but most of it collides against the sawdust-guiding frame 
piece 17. As a result, part of the sawdust is blown upward in such a 
manner as to pass by the inner side of the rear end of the outer cover 8 
by means of the air flow occurring due to the rotation of the circular saw 
7, passes through the sawdust blow-out port 15, and is collected in the 
dust collecting bag H through the sawdust blow-out tube 18. Meanwhile, the 
remaining portion of the sawdust falls down, is collected through the 
guiding action of the conical wall surface 101 of the curved portion 10a 
in the central portion of the fence 10, passes through the sawdust blowup 
port 14a, and is accommodated in the sawdust accommodating space 14. 
Subsequently, as cutting progresses, the direction in which the sawdust is 
scattered rearwardly becomes gradually high. For this reason, the volume 
of the sawdust blown upward in such a manner as to pass by the inner side 
of the rear end of the outer cover 8 becomes gradually large by means of 
the air flow produced by the rotation of the circular saw 7. Hence, the 
volume of the sawdust accommodated in the sawdust accommodating space 14, 
after falling and passing through the sawdust blowup port 14a, becomes 
gradually small. At the point of time when the circular saw 7 is lowered 
immediately before entering the slit 12, substantially all the volume of 
it is blown upward in such a manner as to pass by the inner side of the 
rear end of the outer cover 8, passes through the sawdust blow-out port 15 
provided in the rear end of the upper portion of the outer cover 8, and is 
discharged to the outside through the sawdust blow-out tube 18 provided in 
the bracket 18. Subsequently, when the cutting of the circular saw 7 
reaches the bottom of the workpiece w and the circular saw 7 begins to 
enter the slit 12, the sawdust in the vicinity of the bottom of the 
workpiece w passes through the slit 12 and is accommodated in the sawdust 
accommodating space 14. The sawdust located away from the bottom of the 
workpiece w is blown upward in such as manner as to pass by the inner side 
of the rear end of the outer cover 8. Then, as the circular saw 7 is 
further lowered and substantially enters the slit 12, the sawdust-guiding 
frame piece 17 is lowered to the vicinity of the upper surface of the 
curved portion 10a in the central portion of the fence 10. Meanwhile, 
since the sawdust accommodating space 14, as viewed from the side of the 
device, is configured into an arcuate bag-like space, the air flow caused 
by the rotation of the circular saw 7 inside the sawdust accommodating 
space 14 is blown upward through the sawdust blow-up port 14a. Hence, the 
sawdust is carried upward by the air flow in such a manner as to pass by 
the inner side of the rear end of the outer cover 8 along the conical wall 
surface 101 and the sawdust-guiding frame piece 17, and passes through the 
sawdust blow-out port 15 and the sawdust blow-out tube 18 before it is 
collected in the sawdust collecting bag H. 
As described above, in accordance with the variable cutting-angle circular 
saw device of the present invention, the following arrangement is 
provided: The bottom of the sawdust accommodating space provided below the 
slit in the upper surface portion of the rotary table is closed by the 
cover. The sawdust accommodating space, as viewed from the side of the 
device is configured into a substantially arcuate bag-like space. The 
sawdust-guiding frame piece is suspended from the lower end of the rear 
portion of the outer cover. When the circular saw has been lowered until 
it begins to enter the slit, the sawdust-guiding frame piece smoothly 
blocks the opening, ranging from the upper surface of the curved portion 
in the central portion of the fence to the lower end of the rear portion 
of the outer cover, thereby guiding the sawdust which has blown out from 
the sawdust blow-out port by constituting a smooth wall surface leading to 
the lower end of the rear portion of the outer cover. 
Accordingly, the sawdust accommodated in the sawdust accommodating space 
can be effectively blown out from the sawdust blow-out port at the rear 
end of the slit by means of the air flow produced by the rotation of the 
circular saw. Furthermore, the sawdust which has blown out from the 
sawdust blow-out through the guiding action of the sawdust-guiding frame 
piece can be blown out the outside from the necessary exit port via the 
inner side of the rear end of the outer cover. Hence, it is possible to 
substantially enhance the efficiency with which the sawdust is recovered. 
In addition, in accordance with the variable cutting-angle circular saw 
device of the present invention, the sawdust which tends to be scattered 
from above the curved portion in the central portion of the fence by 
scattering low rearwardly of the device during the initial period of 
cutting can be received by the sawdust-guiding frame piece suspended from 
the lower end of the rear portion of the outer cover, thereby making it 
possible to prevent the sawdust from scattering rearwardly of the device. 
In addition, since the sawdust accommodating space is formed into a 
bag-like space, the sawdust is prevented from being discharged from the 
lower portion of the base to the surroundings of the device. Hence, the 
working environment can be kept clean, and the cleaning of the 
surroundings of the device can be facilitated.