Saw blade with aperture

The present invention covers a saw blade having a row of teeth with a unique arrangement along its edge and the blade has at least one closed aperture which extends in the direction away from the row of teeth, wherein the part of the saw blade between the row of teeth and the aperture comprises a strip-like element.

BACKGROUND OF THE INVENTION 
The present invention relates to a saw blade with a row of teeth with a 
unique arrangement along its edge. It is characterized in that the blade 
has at least one closed aperture which extends in the direction away from 
the row of teeth, wherein the part of the saw blade between the row of 
teeth and the aperture comprises a strip-like element. 
It is known in the art that in a sawing process saw chips or saw dust, i.e. 
saw waste, is produced with the waste hindering the cutting process. The 
saw chips can stick to the saw blade and produce a strong friction between 
the saw blade and the material to be cut. This leads to clamping and to a 
detrimental warming up. It is also known that the saw dust will weld onto 
the side sectios and round sections. This is the so-called cold-welding. 
SUMMARY OF THE INVENTION 
These disadvantages are to be avoided according to this invention, which is 
characterized in that the saw blade has at least one closed aperture, 
which extends in the direction away from the row of teeth, wherein the 
part of the saw blade between the row of teeth and the aperture comprises 
a strip-like element. 
In particular, in the field of bone surgery a cool cutting, as obtained by 
the inventive device, is of great importance. As a consequence of the 
provision of an aperture, the surface of the saw blade exposed to friction 
with the object to be sawn is markedly reduced. Thereby, in the cutting 
process of a bone, there will result less bleeding of the adjacent tissue, 
so that the view of the cut is much better. Thereby, cuts of the highest 
precision are possible and in addition the subsequent healing process is 
speedier. It is also important that, as a consequence of the presence of 
the aperture, there is always enough room for saw chips or saw dust, thus 
avoiding a compound of bone dust. If it is necessary to use a rinsing with 
a fluid, the sterile fluid can flush the bone dust away. It is not 
necessary that the fluid run down the sidewalls of the blade; it will 
enter directly into the aperture. A corresponding process applies to a 
cooling fluid in an industrial use.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The saw blade shown in the FIGS. 1, 2, and 3 has an indentation of indent 
11 which serves to fix the blade to the saw and to drive it by a motor. 
The saw blade has along its edge a row of teeth 12. The blade has a closed 
aperture 13; this means the aperture 13 is all around surrounded by the 
blade body. On each side of the blade face there is a shallow section, 
which extends from the border line 14 to the border line 15 at the teeth 
12, which is located over a part of height 16 (FIG. 3) of the teeth 12. 
The points 17 of the teeth 12 are therefore thicker than is the thickness 
of the teeth 12 in between the line 15 and the base of the teeth. They are 
aso thicher than is the thickness of the saw blade between the teeth 12, 
respectively, the border line 15, and the border line 14. 
Thus it can be seen that the provision of an aperture 13 appreciably 
reeuces the surface of the blade which comes into contact with the 
material to be cut, as compared with a full blade or blade body. If, after 
the sawing process, the row of teeth 12 and its strip-like element 18 have 
passed through the cut, a friction can take place only at two arms 19. 
Therefrom there result the above-mentioned advantages of a cool cut and an 
improved surgical working condition. Under normal conditions it is of 
advantage if, as shown in FIG. 3, the height 16 of the teeth 12 is 
approximately equal to the width of the element 18. 
In view of the specific construction of the teeth, they do not have to be 
set. They are arranged parallel to the center plane, which is parallel to 
the side faces of the blade. Therefrom there results that the blade, in 
comparison to regular blades with a setting, has practically no vibration 
during operation. This again means that this sort of saw blade is 
particularly well suited to be provided with an aperture. 
The embodiment shown in FIGS. 4 and 5 has again an indent 11 for the 
fixation and the drive of the saw blade. The latter is again provided with 
a row of teeth 12 along its outer edge. As shown in the foregoing example, 
an aperture 13 is provided. Between the border lines 14 and 15 and on both 
side faces of the saw blades there is a shallow section which extends at 
the location of the teeth 12 outwardly over a part of their height. 
A strip-like element 21 carries a row of teeth 12 and indentations 22, each 
of which is in registry with a tooth. It is seen that in this way the 
surface contacting during cutting will be even smaller and the weight of 
the blade will be even lighter than it is in the embodiment shown in FIGS. 
1, 2, and 3. 
According to the embodiment of FIGS. 4 and 5, the edge of the aperture 13 
is bevelled, which means the edge has a broken rim 23 as can be seen in 
FIG. 5. This bevelled rim can extend over the entire perimeter of the 
aperture 13 or only over a part of it. This bevelling causes the edge to 
be more resistant and stronger. The formation of hair cracks in the blade 
material is thereby reduced. The formation of hair cracks in the blade 
material can also be reduced if the indentations 22 are rounded, in 
particular at their deepest location. The same is true for the base of the 
teeth 12. The widening of the indentations 22 in the direction away from 
their deepest location and toward the aperture 13 causes the saw chips to 
be moved in the direction toward the aperture 13. They will, therefore, 
move only slightly into the area between the element 21 and the teeth 12 
and the cutting faces of the object to be sawn. 
The aperture 13 shown in FIG. 4 has a form tapered in the direction away 
from the element 21, which is shaped similar to an isosceles triangle, of 
which the base line extends along the row of teeth 12. The structure shown 
in FIG. 4 represents a stable saw blade, which is free from vibrations and 
has comparatively small sidefaces. According to the circumstances and 
particularly for deep cuts, in lieu of the blade shape of FIG. 4, an 
aperture 13 of a form may be chosen in which the entire length of the arms 
is substantially equal to the width, which the arms of FIG. 4 have in the 
neighborhood of element 21, i.e. the arms over their entire length are of 
constant width. 
Another embodiment is shown in FIG. 5 in the form of a circular saw blade 
which is provided with teeth 25 over its entire perimeter. Additionally 
there is provided a plurality of apertures 27. Also, this blade has on its 
upper and lower side face a shallow section. The shallow section shown in 
FIG. 6 extends from the borderline 28 toward the outside in such a way 
that it will include the part of the height of the teeth up to the border 
line 29. While it is known that with a circular saw a great deal of the 
saw chips is moved away sideways, the apertures 27 still add to the fact 
that a smaller amount of saw dust will get between the sides of the blade 
and the sides of the cut. Particularly, in a mutual contact of the side 
faces and the cut, for instance due to an inaccurate guiding of the saw, 
less heat is produced, because with a circular saw blade, relatively 
little surface is present which will cause friction. The circular saw 
serves in particular for industrial use. 
The saw blade according to FIG. 7, which is still a further embodiment, is 
for a hack saw. The blade is tightened with the holes 31 to a bow (not 
shown). Along a longitudinal edge of the saw blade there is provided a row 
of teeth 12. A bridge 34 is provided between two apertures 33. On each 
side face of the saw blade there is a shallow section. These shallow 
sections extend from the border lines 36 over the entire width of the 
blade, i.e. to the longitudinal side of the blade opposite to the teeth 
12. This kind of blade also is intended mostly for industrial use. 
Still another embodiment is shown in FIGS. 8 and 9 and relates again to an 
oscillating saw. It has again an indent 11. Three apertures 43 extend in 
the direction away from the eeth 42. The apertures are limited on the 
sides by arms 44, which are to improve the stability, in particular to 
reduce vibrations, and to keep the row of teeth 42 in a straight line. As 
can be seen in FIG. 9, this blade has no shallow sections, but its teeth 
42 are set. Also with a saw blade with set teeth, the provision of an 
aperture has the advantage of reduced obstructions by the saw chips, of 
less friction and therewith a cool cutting. The cold welding of chips is 
practically avoided. 
The present invention is also applicable to saw blades with a wavy setting. 
In using a saw blade of hardened steel, it is very important that in the 
manufacture of the blade the hardening process is made first and the 
aperture in the blade is made afterward. A warping of the blade is thereby 
avoided. The waste pieces resulting from the production of the apertures 
can be used as valuable basic material for other kinds of tools. 
Also, in the use of a blade according to the invention there result the 
advantages that the waste chips stick less onto the blade so that the 
detrimental heating up of the blade, the jamming and the decrease of the 
quality of the cut are prevented or greatly reduced. In particular, in 
bone surgery the resulting cool sawing process is of high value. 
Additionally, the tissue coming into contact with the saw blade is less 
subject to bleeding. 
Applicant is the owner of application for U.S. Letters Patent Ser. No. 
394,187 filed July 1, 1982, entitled "Saw Blade With Shallow Section," the 
disclosure of which is made a part of this application by way of 
reference. 
Although the invention is described in detail for the purpose of 
illustration, it is to be understood that such detail is solely for that 
purpose and that variations can be made therein by those skilled in the 
art without departing from the spirit and scope of the invention except as 
it may be limited by the claims.