Saw machine

A saw machine includes a base body with rear and front portions. A worktable extends from the rear portion toward the front portion, and has a sawing slot formed therethrough. An upright support arm has an intermediate section pivoted to the rear portion of the base body. An upper hollow arm extends above the front portion of the base body from an upper section of the support arm. A lower hollow arm extends below the front portion of the base body from a lower section of the support arm. A pair of upper and lower levers have rear ends pivoted respectively in the upper and lower hollow arms, and front ends aligned with each other to define cooperatively a straight line that passes through the sawing slot. An elongated saw blade has two ends connected to the front ends of the upper and lower levers so as to pass through the sawing slot. An angle-adjusting assembly is connected to the lower hollow arm for turning the lower and upper hollow arms and the upright support arm simultaneously to adjust an inclined position of the saw blade. A driving assembly is disposed adjacent and is connected to the front end of the lower lever to reciprocate the lower lever, thereby moving the saw blade along the straight line.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relate to a sawing machine, more particularly to an improved 
sawing machine which has a driving assembly that is mounted on a base body 
of the sawing machine adjacent to a sawing blade of the sawing machine so 
as to facilitate actuation of the saw blade. 
2. Description of the Related Art 
The improvement of this invention is directed to a conventional sawing 
machine, as shown in FIG. 1, which includes a base body 11, a worktable 
12, a pair of upper and lower hollow arms (13a, 13b), a driving assembly 
14, and a saw blade 15. 
The base body 11 has a rear portion, a front portion, and a hollow support 
body 111 mounted to the rear portion of the base body 11. The worktable 12 
is supported by the base body 11 and has a top working surface 121 which 
extends horizontally above the front portion of the base body 11 and on 
which a workpiece (not shown) can be supported. A sawing slot 122 is 
formed through the worktable 12. The upper hollow arm (13a) is located 
above the worktable 12 and has a rear end that is fixed to an upper 
section of the support body 111 and a front end that extends toward the 
front portion of the base body 11. The lower hollow arm (13b) is located 
below the worktable 12 and has a rear end that is fixed to a lower section 
of the support body 111 and a front end that extends toward the front 
portion of the base body 11. The driving assembly 14 is mounted within the 
support body 111. A pair of upper and lower levers (not shown) are mounted 
respectively and pivotally within the upper and lower hollow arms (13a, 
13b). The upper lever has a rear end driven by the driving assembly 14 in 
a known manner, and a front end extending toward the front end of the 
upper hollow arm (13a). The lower lever has a rear end driven by the 
driving assembly 14 in a known manner, and a front end extending toward 
the front end of the lower hollow arm (13b). The saw blade 15 passes 
through the sawing slot 122 of the worktable 12 and has two ends which are 
mounted respectively to the front ends of the upper and lower levers. 
When the rear ends of the upper and lower levers are driven by the driving 
assembly 14, the upper and lower levers can move reciprocatingly and 
synchronously within the upper and lower hollow arms (13a, 13b) so as to 
reciprocate the saw blade 15 to cut a workpiece on the worktable 12. 
Owing to a longer distance between the saw blade 15 and the driving 
assembly 14, the saw blade 15 can be driven only indirectly by the driving 
assembly 14 via the upper and lower levers. The above described 
transmission system, accordingly, is not the most economical way to 
actuate effectively the saw blade 15 to cut the workpiece. 
Referring to FIG. 2, the conventional sawing machine further includes an 
adjustment rod 16 which is provided at the front portion of the base body 
11 below the worktable 12 in order to incline the worktable 12 to a 
suitable angle in a known manner, thereby adjusting the inclined position 
of the working surface 121 of the worktable 12 so that a beveled cut can 
be made on the workpiece. 
Instead of the workpiece, the worktable 12 is moved and is inclined in the 
conventional sawing machine. This creates a disadvantage in that the 
workpiece tends to slide downward from the inclined worktable 12 due to 
gravity. Thus, the workpiece has to be held in a desired position by an 
operator, thereby causing difficulties and inconveniences during operation 
and even adverse effects on the accuracy of the cutting lines or cutting 
surfaces. 
SUMMARY OF THE INVENTION 
Therefore, the main objective of this invention is to provide an improved 
sawing machine which has a driving assembly mounted to a position adjacent 
to a saw blade thereof in order to actuate effectively and economically 
the saw blade. 
Another objective of this invention is to provide an improved sawing 
machine which has an angle-adjusting assembly that can adjust a saw blade 
of the improved sawing machine to an inclined position relative to a top 
working surface of a worktable of the improved sawing machine so as to 
form conveniently and accurately a bevel on the workpiece. 
According to this invention, a sawing machine of this invention includes a 
base body, a worktable, an upright support arm, upper and lower hollow 
arms, upper and lower levers, an elongated saw blade, an angle-adjusting 
assembly, and a driving assembly. The base body has a rear portion and a 
front portion. The worktable is supported by the base body and has a top 
working surface which extends horizontally from the rear portion toward 
the front portion of the base body. A sawing slot is formed through the 
worktable. The upright support arm has an upper section, a lower section, 
and an intermediate section mounted pivotally to the rear portion of the 
base body. The upper hollow arm extends above the worktable and has a rear 
end portion which is fixed to the upper section of the support arm, and a 
front end portion which extends toward the front portion of the base body 
above the worktable. The lower hollow arm extends below the worktable and 
has a rear end portion which is fixed to the lower section of the support 
arm, and a front end portion which extends toward the front portion of the 
base body below the worktable. The upper lever has a rear end mounted 
pivotally in the upper hollow arm and a front end provided with an upper 
saw-blade mounting member. The lower lever has a rear end mounted 
pivotally in the lower hollow arm and a front end provided with a lower 
saw-blade mounting member. The upper and lower saw-blade mounting members 
are aligned with each other and define cooperatively a straight line which 
passes through the sawing slot of the worktable. The elongated saw blade 
has two ends connected respectively to the upper and lower saw-blade 
mounting members so as to extend along the straight line and so as to pass 
through the sawing slot. The driving assembly is disposed adjacent and is 
connected to the front end of the lower lever to reciprocate the lower 
lever so as to move reciprocatingly the saw blade along the straight line. 
The angle-adjusting assembly is mounted to the base body and is connected 
to the lower hollow arm for turning the lower and upper hollow arms, as 
well as the upright support arm, simultaneously so as to adjust an 
inclined position of the saw blade relative to the top working surface of 
the worktable. 
The driving assembly includes a support plate, a motor, a speed reduction 
gear assembly and a crank member. The support plate is coupled with the 
front end portion of the lower hollow arm. The motor is installed on the 
support plate and has an output shaft. The speed reduction gear assembly 
is connected to the motor and is drivable by the motor. The speed 
reduction gear assembly has a driving gear mounted fixedly and coaxially 
on the output shaft of the motor, and a driven gear which is driven by the 
driving gear and which has an eccentric shaft that extends axially 
therefrom. The crank member has a lower end mounted on the eccentric shaft 
of the driven gear, and an upper end connected to the front end of the 
lower lever to reciprocate the lower lever and the saw blade. The support 
plate has a slide portion which is connected to the angle-adjusting 
assembly and which is movable by actuation of the angle-adjusting 
assembly. Movement of the support plate moves correspondingly the upper 
and lower hollow arms so as to adjust the saw blade in the inclined 
position. 
The angle-adjusting assembly is mounted on the front portion of the base 
body and includes a guide plate and a moving unit. The guide plate is 
mounted securely on the front portion of the base body in front of the 
slide portion of the support plate, and has a front side, a rear side 
which contacts face to face the slide portion of the support plate, and an 
arcuate slot formed therethrough. The moving unit is located at the front 
side of the guide plate and has an adjustment threaded rod which is 
mounted rotatably to the guide plate and an adjustment block which is 
sleeved around the adjustment threaded rod so as to be driven by the 
latter. The angle-adjusting assembly further includes means for connecting 
the adjustment block so as to the slide portion of the support plate via 
the arcuate slot of the guide plate so as to slide the slide portion of 
the support plate along the arcuate slot of the guide plate when the 
adjustment threaded rod is operated rotatably, thereby moving the support 
plate and the lower hollow arm along an arcuate path defined by the 
arcuate slot. A stabilizing protrusion projects from the slide portion of 
the support plate into the arcuate slot of the guide plate for guiding the 
slide portion to move stably on the guide plate. The connecting means 
includes a slide plate which is located at the front side of the guide 
plate. The slide plate has an end portion pivoted to the adjustment block 
and another end portion connected pivotally to the stabilizing protrusion 
so as to push the stabilizing protrusion to slide along the arcuate slot 
by virtue of the movement of the adjustment block on the adjustment 
threaded rod. The connecting means further includes a retaining plate 
located between the slide plate of the connecting means and the front side 
of the guide plate and coupled with the stabilizing protrusion of the 
support plate. The retaining plate has a width larger than a height of the 
arcuate slot so as to contact face to face with the front side of the 
guide plate at a peripheral portion thereof, thereby preventing removal of 
the stabilizing protrusion from the arcuate slot of the guide plate. A 
rotary handle is mounted securely on one end of the adjustment threaded 
rod and is located at an exterior of the base body so as to facilitate 
rotation of the adjustment threaded rod.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 3, a preferred embodiment of the sawing machine of this 
invention includes a base body 22, a worktable 23, an upright support arm 
211, upper and lower hollow arms (21a, 21b) (see FIG. 6), upper and lower 
levers (24a, 24b) (see FIG. 6), an elongated saw blade 26, an 
angle-adjusting assembly, and a driving assembly 70 (see FIG. 4). 
The base body 22 has a rear portion 222 and a front portion 221. The rear 
portion 222 has an upwardly extending pivot arm 27. 
The worktable 23 is supported by the base body 22 and has a top working 
surface 231 which extends horizontally from the rear portion 222 toward 
the front portion 221 of the base body 22. A sawing slot 232 is formed 
through the worktable 23. 
The upright support arm 211 has an upper section, a lower section, and an 
intermediate section mounted pivotally to the pivot arm 27 of the rear 
portion 222 of the base body 22 by means of a pivot pin 28. A curved 
angle-measuring member 29 is positioned between the pivot arm 27 and the 
upright support arm 211 so as to enable an operator to determine an 
inclined angle of the support arm 211 relative to the working surface 231 
of the worktable 23. 
The upper hollow arm (21a) extends above the worktable 23 and has a rear 
end portion which is fixed to the upper section of the support arm 211 and 
a front end portion which extends toward the front portion of the base 
body 22 above the worktable 23. 
The lower hollow arm (21b), as shown in FIG. 4, extends below the worktable 
23 and has a rear end portion which is fixed to the lower section of the 
support arm 211 and a front end portion which extends toward the front 
portion of the base body 22 below the worktable 23. 
Referring again to FIG. 3, the upper lever (24a) has a rear end which is 
mounted pivotally to the rear end portion of the upper hollow arm (21a), 
and a front end which extends toward the front end portion of the upper 
hollow arm (21a) and which is provided with an upper saw-blade mounting 
member (25a). 
The lower lever (24b), as shown in FIG. 7, has a rear end (not shown) which 
is mounted pivotally to the rear end portion of the lower hollow arm 
(21b), and a front end which extends toward to the front end portion of 
the lower hollow arm (21b) and which is provided with a lower saw-blade 
mounting member (25b). The upper and lower saw-blade mounting members 
(25a, 25b) are aligned with each other and define cooperatively a straight 
line which passes through the sawing slot 232 of the worktable 23, as 
shown in FIG. 3. 
The elongated saw blade 26 has two ends connected respectively to the upper 
and lower saw-blade mounting members (25a, 25b) so as to extend along the 
straight line and so as to pass through the sawing slot 232 of the 
worktable 23. 
Referring to FIGS. 4 and 6, the driving assembly 70 is disposed adjacent 
and is connected to the front end of the lower lever (24b) to reciprocate 
the lower lever (24b) so as to move reciprocatingly the saw blade 26 (see 
FIG. 3) along the straight line defined by the upper and lower saw-blade 
mounting members (25a, 25b). 
The angle-adjusting assembly includes a guide plate 40 and a moving unit 60 
(see FIG. 4) which are mounted to the front portion of the base body 22 
and is connected to the lower hollow arm (21b) for turning the lower and 
upper hollow arms (21b, 21a), as well as the upright support arm 211, 
simultaneously so as to adjust an inclined position of the saw blade 26 
relative to the top working surface 231, as shown in FIG. 9. 
Referring to FIGS. 5 and 7, the driving assembly 70 includes a support 
plate 30, a motor 71, a speed reduction gear assembly, and a crank member 
74. The support plate 30 has a support portion 31 and a slide portion 32 
which extends vertically from a side edge of the support portion 31. 
The support portion 31 of the support plate 30 has a passage 312 formed 
therethrough, a hole 313 formed therethrough below the passage 312, and an 
upwardly extending positioning plate 311 coupled with one of the side 
walls of the front end portion of the lower hollow arm (21b) by means of a 
bolt 351 so as to fix the lower hollow arm (21b) on the support plate 30. 
The motor 71 is installed on the support plate 30 and has an output shaft 
711 which extends through the hole 313 of the support portion 31. The 
speed reduction gear assembly has a driving gear 72 mounted fixedly and 
coaxially on the output shaft 711 of the motor 71, and a driven gear 73 
which is mounted pivotally on the outer side of the support portion 31 and 
which meshes with the driving gear 72 so as to be driven by the latter. 
Accordingly, the speed reduction gear assembly is connected to the motor 
71 and is drivable by the same. The driven gear 73 has an eccentric shaft 
731 which extends axially therefrom. The crank member 74 has a lower end 
which is sleeved on the eccentric shaft 731 of the driven gear 73, and an 
upper end which extends through the passage 312 of the support portion 31 
and through an opening 212 of the lower hollow arm (21b) so as to be 
connected to the front end of the lower lever (24b). The crank member 74 
is drivable indirectly by the motor 71 via the speed reduction gear 
assembly to reciprocate the lower lever (24b). 
Because the front end of the lower lever (24b) is provided with the lower 
saw-blade mounting member (25b), the reciprocation of the lower lever 
(24b) can actuate the lower saw-blade mounting member (25b) so as to 
reciprocate the saw blade 26 (see FIG. 3). Owing to its being connected 
directly to the lower saw-blade mounting member (25b), the driving 
assembly 70 can drive effectively the saw blade 26 in a simple and 
economical way. 
The slide portion 32 of the support plate 30 has a horizontal plate 34 (see 
FIG. 5) extending rearwards from a top end thereof for bearing the lower 
hollow arm (21b) thereon. By extending a bolt 352 through the horizontal 
plate 34 and the bottom wall of the lower hollow arm (21b), the lower 
hollow arm (21b) can be fixed on the support plate 30. The support plate 
30 further has a stabilizing protrusion 33 projecting from a front surface 
of the slide portion 32, two threaded holes 331 formed through the 
stabilizing protrusion 33 and the slide portion 32 at two end portions of 
the stabilizing protrusion 33, and a pivot hole 332 formed through the 
stabilizing protrusion 33 and the slide portion 32 between the threaded 
holes 331. The slide portion 32 of the support plate 30 is connected to 
the angle-adjusting assembly and is movable by actuation of the 
angle-adjusting assembly. Movement of the support plate 30 moves 
correspondingly the upper and lower hollow arms (21a, 21b) as well as the 
upright support arm 211 so as to adjust the saw blade 26 in the inclined 
position. The connection between the support plate 30 and the 
angle-adjusting assembly and the actuation of the angle-adjusting assembly 
will be described in the following paragraphs. 
The guide plate 40 of the angle-adjusting assembly has a front side, a rear 
side, a curved upper end 41 for allowing the lower hollow arm (21b) to 
move thereabove (see FIG. 8), and an arcuate slot 42 formed therethrough. 
The stabilizing protrusion 33 of the support plate 30 extends into the 
arcuate slot 42 of the guide plate 40 for guiding the support plate 30 to 
move stably on the guide plate 40 when the support plate 30 is driven by 
the angle-adjusting assembly. A pair of mounting members 43 are formed on 
the lower ends of the front side of the guide plate 40 and are spaced 
apart from each other at a predetermined distance. A pair of forwardly 
extending positioning plates 44 are formed on the guide plate 40 above the 
mounting members 43 and are mounted threadably on the top surface of the 
front portion 221 of the base body 22, as shown in FIGS. 4 and 7, so as to 
fix the guide plate 40 on the base body 22 in front of the slide portion 
32 of the support plate 30. In this way, the rear side of the guide plate 
40 can contact face to face the slide portion 32 of the support plate 30. 
Referring again to FIGS. 5 and 7, the moving unit 60 of the angle-adjusting 
assembly includes an adjustment threaded rod 62 with two ends which engage 
rotatably two holes 431 in the mounting members 43 of the guide plate 40, 
and an adjustment block 63 with an inward threaded portion 631 engaging 
movably an outwardly threaded portion 621 of the adjustment threaded rod 
62 when the adjustment block 63 is sleeved around the adjustment threaded 
rod 62. Accordingly, when the adjustment threaded rod 62 is rotated, the 
adjustment block 63 can be moved along the adjustment threaded rod 62. The 
moving unit 60 further includes a rotary handle 61 which is mounted 
securely on one end of the adjustment threaded rod 62 and which is located 
at an exterior of the front portion 221 of the base body 22 (see FIG. 7) 
so as to facilitate rotation of the adjustment threaded rod 62. 
The angle-adjusting assembly further includes means for connecting the 
adjustment block 63 to the slide portion 32 of the support plate 30 via 
the arcuate slot 42 of the guide plate 40 so as to slide the stabilizing 
protrusion 33 of the slide portion 32 along the arcuate slot 42 when the 
adjustment threaded rod 62 is operated rotatably, thereby moving the 
support plate 30 and the lower hollow arm (21b) along an arcuate path 
which is defined by the arcuate slot 42. 
The connecting means includes a slide plate 50 which is located at the 
front side of the guide plate 40 and which has two pivot holes 51 formed 
in two end portions thereof. The slide plate 50 is mounted pivotally to 
the adjustment block 63 by extending a pivot pin 65 through the right one 
of the pivot holes 51 of the slide plate 50 and through a hole 632 of the 
adjustment block 63. Then, a lock element 66 is sleeved on a distal end of 
the pivot pin 65 so as to lock the pivot pin 65. A pivot bolt 52 extends 
through the pivot hole 332 of the support plate 30 and through the left 
one of the pivot holes 51 of the slide plate 50, and is locked on the 
slide plate 50 by means of a threaded nut 54 so as to connect pivotally 
the stabilizing protrusion 33 to the slide plate 50. Accordingly, the 
slide plate 50 can push the stabilizing protrusion 33 to slide along the 
arcuate slot 42 of the guide plate 40 by virtue of the movement of the 
adjustment nut 63 on the adjustment threaded rod 62. The connecting means 
further includes a retaining plate 45 which is located between the slide 
plate 50 and the front side of the guide plate 40 and which is coupled 
with the stabilizing protrusion 33 of the support plate 30 by means of two 
bolts 56, each of which extends through a respective one of the threaded 
holes 331 of the support plate 30 and through a respective one of two 
spaced threaded holes 452 of the retaining plate 45. The retaining plate 
45 has a width larger than a height of the arcuate slot 42 so as to 
contact face to face with the front side of the guide plate 40 at a 
peripheral portion thereof, thereby preventing removal of the stabilizing 
protrusion 33 from the arcuate slot 42 of the guide plate 40. A washer 53 
is sleeved around the pivot bolt 52 between the retaining plate 45 and the 
slide plate 50 so as to avoid excess friction between the retaining plate 
45 and the slide plate 50 when the angle-adjusting assembly is in use. 
Referring to FIGS. 8 and 9, when the adjustment block 63 is moved along the 
adjustment threaded rod 62, the slide plate 50 can slide the stabilizing 
protrusion 33 of the support plate 30 along the arcuate slot 42 of the 
guide plate 40 so as to move the support plate 30 on the guide plate 40 
along the arcuate path which is defined by the arcuate slot 42. Movement 
of the support plate 30 moves the lower hollow arm (21b) and the upper 
hollow arm (21a), as well as the support arm 211, along the arcuate path 
in order to place the saw blade 26 in an inclined position relative to the 
top working surface 231 of the worktable 23, as shown in FIG. 9. In this 
way, when the saw blade 26 is actuated to cut the workpiece, a bevel can 
be formed on the workpiece. Preferably, the angle-measuring member 29 can 
facilitate observing of the inclined angle of the saw blade 26. 
With the provision of the angle-adjusting assembly to adjust the inclined 
position of the saw blade 26, the worktable 23 of this invention does not 
have to be moved and inclined in order to adjust the inclined position of 
the working surface 231. Thus, the workpiece can be supported stably on 
the working surface 231 of the worktable 23 without the risk of downward 
sliding. 
While the present invention has been described in connection with what is 
considered the most practical and preferred embodiment, it is understood 
that this invention is not limited to the disclosed embodiments but is 
intended to cover various arrangements included within the spirit and 
scope of the broadest interpretations and equivalent arrangements.