Saw blade mounting structure for curve sawing machines that allows buffer play

A saw blade mounting structure for curve sawing machines that allows buffer play, includes upper and lower saw blade clamps opposedly arranged in a mirror image at front ends of upper and lower support arms adapted to position both pin type and plain type saw blades. an adjusting seat having a post on an upper side for receiving a compression spring therein and a lower side connected to the upper saw blade clamp. The adjusting seat and compression spring are placed in a recess at the front end of the upper support arms with a threaded section of a rotary shaft passing through an upper portion of the recess to lock into a threaded through hole of the adjusting seat to a certain depth, which is adjustable. The rotary shaft has a portion exposed on the outside and connected to a detachable eccentric locking knob. When mounting a saw blade, the locking knob may be turned to exert an eccentric force on the adjusting seat so that the latter elevates to pull the saw blade tight in an optimum position. Replacement of the saw blade is also very easy. When the saw blade hits against a knob in the wood, the compression spring provides sufficient buffer play to avoid breaking of the saw blade. There is also enough play for the upper and lower saw blade clamps to ensure that the saw blade is always in an optimum vertical position with respect to the work table, thus enhancing sawing precision.

BACKGROUND OF THE INVENTION 
(a) Field of the Invention 
The present invention relates generally to a saw blade mounting structure, 
and more particularly to a saw blade mounting structure for curve sawing 
machines that allows buffer play to ensure sawing precision and, avoid 
breaking of the saw blade, and that facilitates the replacement of both 
pin type and plain type saw blades. 
(b) Description of the Prior Art 
Table top curve sawing machines are generally used to obtain small wood 
boards of various shapes and profiles, because their saw blades are 
elongated and can cut out different geometrical patterns or wooden cast 
molds for industrial use when properly operated. 
There are generally two types of saw blades with curve sawing machines and 
their mounting methods are different. One is the plain type. By utilizing 
grooves of clamp blocks between upper and lower arms of the sawing machine 
in combination with bolts, the grooves are caused to become narrow so as 
to tighten and lock the saw blade in position. In the other type, the saw 
blade has cross pin portions at upper and lower ends thereof, and the 
clamp blocks are provided with both longitudinal and transverse grooves 
for receiving the cross pin portions. As there are two types of saw 
blades, purchasers have to take care not to buy the wrong type since 
existing curve sawing machines are not adapted to be used with both types 
of saw blades, which is a major disadvantage with the prior art. 
Furthermore, since the saw blade is mounted rigidly between the upper and 
lower arms of the sawing machine, when it hits against a knot in the wood, 
it may easily break. Besides, since the upper and lower arms of the sawing 
machine are actually swinging when the sawing machine is actuated, the saw 
blade is not operating in a substantially vertical direction so that the 
saw cuts are not consistent and the sawing precision is affected. 
SUMMARY OF THE INVENTION 
A primary object of the present invention is to provide a saw blade 
mounting structure for curve sawing machines that allows buffer play to 
ensure sawing precision and, avoid breaking of the saw blade, and that 
facilitates the replacement of both pin type and plain type saw blades. 
According to the present invention, the structure comprises upper and lower 
saw blade clamps opposedly arranged in a mirror image at front ends of 
upper and lower support arms adapted to position both pin type and plain 
type saw blades, an adjusting seat having a post on an upper side for 
receiving a compression spring therein and a lower side connected to the 
upper saw blade clamp. The adjusting seat and compression spring are 
placed in a recess at the front end of the upper support arm with a 
threaded section of a rotary shaft passing through an upper portion of the 
recess to lock into a threaded through hole of the adjusting seat to a 
certain depth which is adjustable. The rotary shaft has a portion exposed 
on the outside and connected to a detachable eccentric locking knob. When 
mounting a saw blade, the locking knob may be turned to exert an eccentric 
force on the adjusting seat so that the latter elevates to pull the saw 
blade tight in an optimum position. Replacement of the saw blade is also 
very easy. When the saw blade hits against a knob in the wood, the 
compression spring provides sufficient buffer play to avoid breaking of 
the saw blade. There is also enough play for the upper and lower saw blade 
clamps to ensure that the saw blade is always in an optimum vertical 
position with respect to the worktable, thus enhancing sawing precision.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
With reference to FIGS. 1 and 4, the present invention essentially 
comprises an upper support arm 2, an adjusting seat 3, a lower support arm 
4, and upper and lower clamps 5, 5'. 
The upper support arm is provided with a recess 21 at the bottom side of 
its front end. An enclosed upper side of the recess 21 is formed with a 
through hole 22. There is provided a locking knob 23 having a front end 
configured to form an inverted U-shaped portion 231 and a rear end forming 
a holding portion 232. Symmetrical arms of the U-shaped portion are 
provided with respective first spring pin holes 233 to accommodate a first 
spring pin 6 and which are designed to be eccentric with respect to the 
bottom edge of the inverted U-shaped portion 231. There is further 
provided a rotary shaft 24 having a smooth section at an upper end which 
is provided with a second spring pin hole 241 and a threaded section 242 
at a lower end. 
The adjusting seat 3 includes a circular post 31 at an upper end and an 
inverted U-shaped block 32 at a lower end. Side walls of the U-shaped 
block 32 are provided with opposed third spring pin holes 321. The post 31 
is centrally provided with a threaded through hole 311. 
The lower support arm 4 is provided with a substantially U-shaped opening 
41 at its front end. Opposite walls of the opening 41 are provided with 
fourth spring pin holes 411 respectively. 
Upper and lower saw blade clamps 5, 5' each have a narrower section and a 
wider section. The narrower section is configured to be a T-shaped head 51 
provided with a fifth spring pin hole 52. The wider section is configured 
to have a transverse through groove 53 and a longitudinal groove 54. 
Opposed threaded through holes 55 are further provided in a lateral side 
of the wider section and communicate with the longitudinal groove 54. Two 
pin adapter plates 56 in a matching configuration are respectively fitted 
in between the transverse groove 53 and the longitudinal groove 54 when it 
is desired to mount a pin-type saw blade rather than a plain type saw 
blade, as will be described in more detail below. 
During assembly, the T-shaped head 51 of the upper saw blade clamp 5 is 
inserted into the inverted U-shaped block 32 of the adjusting seat 3, with 
a second spring pin 6' passing through third and fifth spring pin holes 
321 and 52 to be positioned therein. Then the T-shaped head 51 of the 
lower saw blade clamp 5' is inserted into the U-shaped opening 41 of the 
lower support arm 4 with a third spring pin 6 passing through fourth and 
fifth spring holes 411 and 52 respectively to be positioned therein. As 
shown in the drawings, the upper and lower saw blade clamps 5, 5' are 
assembled end to end in a mirror image. After assembly, there is enough 
play between the upper and lower saw blade clamps 5, 5'. 
A compression spring 33 is planted into the post 31 at the upper side of 
the adjusting seat 3 and spring 33 and post 31 are together placed in the 
recess 21 of the upper support arm 2. The threaded section 242 of the 
rotary shaft 24 is passed through the through hole 22 at the upper side of 
the recess 21 through the bore of the compression spring 33 into the 
threaded through hole 311 of the adjusting seat 3 to a certain depth, 
which is adjustable as desired. A washer 34 is fitted onto that portion of 
the rotary shaft 24 exposed on the upper support arm 2, with the inverted 
U-shaped portion 231 of the locking knob 23 straddling the exposed portion 
of the rotary shaft 24. The first spring pin 6 passes through the spring 
pin holes 233 and 241 of the locking knob 23 and rotary shaft 24 
respectively for positioning purposes. 
When it is desired to mount a pin type saw blade 7 having upper and lower 
cross end portions 71, the cross end portions 71 are respectively fitted 
into the transverse grooves 53 and longitudinal grooves 54 of the upper 
and lower saw blade clamps 5, 5' respectively, and held by the pin adapter 
56. By turning the holding portion 232 of the locking knob 23 to a first 
position the bottom edge of the locking knob being in sliding engagement 
with the upper side of the support arm, an eccentric pressure will be 
exerted on the adjusting seat 3 so that it elevates to thereby pull the 
saw blade 7 taut (as shown in FIG. 2). If necessary, the locking knob 23 
may be pulled reversely to a second position to release the pressure to 
allow adjustment of the depth of the rotary shaft 24 so that the saw blade 
7 may be mounted at an optimum position. Furthermore, during the process 
of sawing, if the saw blade 7 hits against a knot hidden in the wood, the 
compression spring 33 will allow buffer play to avoid breaking of the saw 
blade 7. In addition, since the upper and lower saw blade clamps 5, 5' 
have enough play during sawing, the saw blade 7 may be kept in an optimum 
vertical state with respect to the work table 1 (workpiece) regardless of 
whether the upper and lower support arms 2, 4 are performing a rowing 
motion. Therefore, when the saw blade 7 is working on a relatively thick 
piece of wood, the saw cut on the upper and lower surfaces of the wood 
will be consistent, thus enhancing sawing precision. 
Furthermore, with reference to FIG. 4, when mounting a plain type saw blade 
7', upper and lower end portions thereof are respectively inserted into 
the longitudinal grooves 54 of the upper and lower saw blade clamps 5, 5' 
directly. Tightening knobs 8,8' and securing bolts 9,9' are passed into 
the corresponding threaded through holes 55 at the lateral side of the 
upper and lower saw blade clamps 5, 5' to lock the upper and lower end 
portions of the plain type saw blade 7'. By turning the holding portion 
232 of the locking knob 23 to exert an eccentric pressure to cause the 
adjusting seat 3 to elevate, the plain type saw blade 7' can be pulled 
tight and positioned. The pressure on the locking knob 23 may be released 
to allow adjustment of the depth of the rotary shaft 24 to lock the plain 
type saw blade 7' at an optimum position and then exert an eccentric 
pressure on and thereby position the locking knob 23. Likewise, during the 
process of sawing, if the plain type saw blade 7' hits against a knot 
hidden in the wood, the compression spring 33 will allow buffer play to 
avoid breaking of the saw blade 7'. In addition, since the upper and lower 
saw blade clamps 5, 5' have enough play during sawing, the saw blade 7 may 
be kept in an optimum vertical state with respect to the work table 1 
(workpiece) regardless of whether the upper and lower support arms 2, 4 
are not truly moving or linking-up in a vertical manner. Therefore, when 
the saw blade 7' is working on a relatively thick piece of wood, the saw 
cut on the upper and lower surfaces of the wood will be consistent, thus 
enhancing sawing precision. 
Although the present invention has been illustrated and described with 
reference to the preferred embodiment thereof, it should be understood 
that it is in no way limited to the details of such embodiment but is 
capable of numerous modifications within the scope of the appended claims.