Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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IMPROVED SAW TOOTH
FIELD OF THE INVENTION
This invention is directed toward an improved saw tooth for
circular saws.
The invention is also directed toward an improved saw tooth
assembly using the improved saw tooth.
BACKGROUND ART
The improved saw tooth of the present invention is of the type
used in circular saws, the circular saws being used in tree
harvesting equipment. The saw tooth is also of the type that can be
replaced on the blade of the circular saw when it becomes dull.
Replacing the saw teeth when they become dull can be
expensive. To reduce the expense of replacing the teeth it is known
to provide a saw tooth having several cutting edges. When one
cutting edge becomes dull, the saw tooth is merely repositioned on
the saw blade to present an unused cutting edge in the cutting
position. Thus one tooth can be used two, or preferably four times,
before it needs to be replaced. Thus the expense of replacing teeth
is greatly reduced. Examples of such saw teeth, with multiple
cutting edges, are shown in US Pat. 4,932,447, issued June 12,
1990, Armand J. Morin inventor; US Pat. 5,058,477, issued Oct. 22,
1991, Charles D. MacLennan inventor; and US Pat. 5,205,199, issued
Apr. 27, 1993, Charles D. MacLennan inventor, by way of example.
The known cutting teeth with four cutting edges are relatively
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expensive however. They usually employ curved cutting edges, as
shown in US Pats. 4,932,447 and 5,058,477, and thus their
manufacture is relatively expensive. Even when the known teeth
employ straight cutting edges, as shown in US Pat. 5,205,199, the
tooth is still relatively expensive to manufacture since the
surfaces of the tooth forming all the cutting edges are quite
numerous and complex.
SUMMARY OF THE INVENTION
It is the purpose of the present invention to provide an
improved cutting tooth of the type with four cutting edges which
tooth is relatively simple in construction and relatively
inexpensive to produce compared to the known cutting teeth. In
accordance with the present invention, the improved cutting tooth
is provided with straight cutting edges which are easier to produce
compared to curved cutting teeth known in the prior art. In
addition, the joining surfaces providing the cutting edges are
fewer in number and simpler than the surfaces used in the prior
art.
In accordance with the present invention the improved saw
tooth is a block-like, or generally parallelopiped, member having
two opposed surfaces with each end of each surface having a cutting
edge. The cutting edges on each surface are parallel to each other
and are also parallel to the cutting edges on the other surface.
The member has a central mounting hole extending between the
surfaces, the axis of the hole transverse to the cutting edges.
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The tooth is mounted on a mounting block on the rim of a
circular saw blade by a bolt extending through the mounting hole in
a manner to have one of the cutting edges on one of the surfaces in
an outer, leading, cutting position. When this cutting edge becomes
dull, the bolt is loosened; the tooth is rotated, relative to the
mounting block, to place the other cutting edge on the same surface
in the outer, leading cutting position; and the bolt is tightened.
When this second cutting edge becomes dull, the bolt is removed,
the tooth is reversed to place a cutting edge on the other surface
in the cutting position, and the bolt is replaced and tightened.
When the third edge becomes dull, the bolt is loosened, the tooth
is rotated to place the other and last unused cutting edge on the
other surface in the cutting position, and the bolt is tightened.
The invention is particularly directed toward a saw tooth
having top and bottom surfaces; side surfaces; and front and back
surfaces. Each front and back surface has cutting edges at their
top and bottom sides, the cutting edges on each surface parallel to
each other and also parallel to the cutting edges on the other
surface.
The invention is also particularly directed toward a saw tooth
assembly having; a saw tooth with top and bottom surfaces; side
surfaces; and front and back surfaces. Each front and back surface
has cutting edges at their top and bottom sides, the cutting edges
on each surface parallel to each other and also parallel to the
cutting edges on the other surface. The assembly includes a
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mounting block adapted to mounted on the rim of a circular saw
blade. Cooperating mounting surfaces on the mounting block and on
the front and back surfaces of the saw tooth locate any one of the
four cutting edges in cutting position when the saw tooth is
detachably mounted on the block. A bolt detachably connects the
tooth to the block with the mounting surface on the block abutting
one of the mounting surfaces on the front or back surfaces of the
tooth.
BRIEF DESCRIPTION OF THE FIGURES IN THE DRAWINGS
Fig. 1 is an exploded perspective view of the saw tooth
assembly;
Fig. 2 is a side view of the saw tooth assembly mounted on a
saw blade;
Figs. 3A, 3B, and 3C are detail side views of the saw tooth
assembly showing repositioning of the saw tooth on the mounting
block to provide new cutting edges;
Fig. 4 is a cross-section view taken along line 4-4 in Fig. 1;
and
Fig. 5 is a side view of another embodiment of the saw tooth.
DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INV~N'1'1ON
The saw tooth 1 of the present invention, as shown in Figs. 1
and 2, has a generally parallelopiped shape with opposed top and
bottom surfaces 3, 5; side surfaces 7; and front and back surfaces
9, 11. The top and bottom surfaces 3, 5 are preferably parallel and
the sides 7 are also preferably parallel. The terms "top" and
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"bottom" refer to the location of the surfaces relative to a saw
blade that the tooth is mounted on, the surface closest to the saw
blade being the "bottom" surface. The terms "front" and "back" also
refer to the location of the surfaces relative to a saw blade that
the tooth is mounted on, the surface facing in the direction of
rotation being the "front" surface.
The front surface 9 has front, top and bottom sections
13, 15 that extend inwardly away from a plane 17 joining the front
sides 19, 21 of the top and bottom surfaces 3, 5. The front, top
and bottom sections 13, 15 of the front surface 9 are preferably
angled inwardly at an angle B from the front plane 17 and are
joined by a front, central section 23 that is transverse to the top
and bottom surfaces 3, 5. Similarly, the back surface 11 has back,
top and bottom sections 25, 27 that extend inwardly from a back
plane 29 joining the back sides 31, 33 of the top and bottom
surfaces 3, 5. The back, top and bottom sections 25, 27 of the back
surface 11 are preferably angled inwardly at an angle B from the
back plane 29 and are joined by a back, central section 35 that is
transverse to the top and bottom surfaces 3, 5. The angle B is
approximately 45~ but can vary between 20~ and 65~. If desired, a
small radius (not shown) can be formed at the juncture of the
front, top and bottom sections 13, 15 with the front, central
section 23 and at the juncture of the back, top and bottom sections
25, 27 with the back central section 35 to reduce stress.
The joining of the front, top section 13 of the front
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surface 9 to the top surface 3, at its front side 19, forms a first
cutting edge 41. The joining of the front, bottom section 15 of the
front surface 9 to the bottom surface 5, at its front side 21,
forms a second cutting edge 43. The first and second cutting edges
41, 43 on the front surface 9 are parallel to each other and
transverse to the side surfaces 7.
The joining of the back, top section 25 of the back surface 11
to the top surface 3, at its back side 31, forms a third cutting
edge 45. The joining of the back, bottom section 27 of the back
surface 11 to the bottom surface 5, at its back side 33, forms a
fourth cutting edge 47. The third and fourth cutting edges 45, 47
are parallel to each other and transverse to the side surfaces 7.
The third and fourth cutting edges 45, 47 are also parallel to the
first and second cutting edges 41, 43.
The tooth 1 has a threaded, central, mounting hole 49
extending through the tooth between the central sections 23, 35 on
the front and back surfaces 9, 11. The hole 49 is centrally located
on the tooth between the top and bottom surfaces 3, 5 and is also
centrally located between the side surfaces 7. The hole 49 extends
transverse to the cutting edges 41, 43, 45, 47 and its center is
equidistant from all of them.
The back, central section 35 on the back surface 11 of the
tooth together with adjacent portions of the top and bottom
sections 25, 27 on the back surface 11 form a first mounting
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surface S1 for the tooth as shown in Fig. 3C and as will be
described. The front, central section 19 on the front surface 9
together with adjacent portions of the top and bottom sections 13,
15 on the front surface 9 form a second mounting surface 53 for the
tooth as shown in Fig. 3A and as will be described.
The saw tooth 1 is adapted to be mounted on a mounting block
55 to form a saw tooth assembly 57. The mounting block 55, as shown
in Figs. 1 and 2, has a top and a bottom surface 59, 61; side
surfaces 63; and front and back surfaces 65, 67. The top and bottom
surfaces 59, 61 converge slightly toward the back; the front and
back surfaces 65, 67 are parallel; and the side surfaces 63 are
also parallel. The front of the block 55 is under cut back from the
front surface 65, as shown at 69, to produce a forwardly extending
projection 71 having a bottom surface 73 that is parallel to the
top surface 59.
The front of the projection 71 is beveled at the top and
bottom as shown at 75, 77 at an angle ~. The distance "L" between
the beveled surfaces 75, 77 on the front surface 65 of the
projection 71 is equal to the distance "L" between the top and
bottom sections 13, 15 or 25, 27 on the front or back surfaces 9,
11 of the tooth 1. The depth "d" of the projection 71 is slightly
less than the depth "D" of the tooth between its top and bottom
surfaces 3, 5. The front surface 65 together with the beveled
surfaces 75, 77 form a saw tooth mounting surface 79 as shown in
Fig. 3.
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The mounting block 55 is adapted to be mounted on the rim 81
of a circular saw 83, as shown in Figs. 1 and 3. To this end, the
bottom surface 61 of the block 55 has a longitudinal, central,
groove 85 for receiving the rim 81. The block can be welded onto
the rim or bolted on by bolts (not shown). The mounting block 55
also has a longitudinal mounting hole 87 that is centered on the
front surface 65 of the projection 71 and extends transversely
therefrom through the block.
With the mounting block 55 mounted on the rim of a saw 83, the
saw tooth 1 is mounted on the block 55 by locating its first
mounting surface 51 adjacent the mounting surface 79 on the
projection 71 as shown in Fig. 3A. A bolt 91 is then passed through
the longitudinal mounting hole 87 in the block and threaded into
the threaded mounting hole 49 on the tooth 1. As the bolt 91 is
tightened it draws the central section 35 of the back surface 11 of
the tooth tight against the front surface 65 of the projection 71
and the back, end sections 25, 27 of the back surface 11 tight onto
the beveled surfaces 75, 77. The beveled surfaces 75, 77 help to
locate the tooth 1 on the projection 71 on the block 55. Thus the
tooth 1 is locked onto the projection 71 with its first cutting
edge 41 in the cutting position slightly above the block 55 and
leading in the directiion of rotation, as shown by the arrow "R",
in Fig. 1. The undercut 69 on the block 55 provides clearance for
the bottom portion of the tooth 1 from the rim 81 of the saw blade
83 when the tooth 1 is mounted on the projection 71.
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When the first cutting edge 41 on the tooth 1 becomes dull, as
shown in Fig. 3A, the bolt 91 is loosened and the tooth is rotated,
as shown by the arrow "A", to place the dull cutting edge on the
bottom and the second, unused cutting edge 43, on the same front
surface 9, on the top at the front. The bolt 91 is retightened.
When the second cutting edge 43 becomes dull, the bolt 91 is
loosened and removed and the tooth is turned around, as shown by
the arrow "B" in Fig. 3B to put its back surface 11 at the front.
The tooth is then remounted on the block 55 with the bolt 91 with
its second mounting surface 53 adjacent the mounting surface 79 on
the projection 71 as shown in Fig. 3C. The third cutting edge 45 is
at the front and top of the block 55. When this third cutting edge
45 becomes dull, the bolt 91 is again loosened and the tooth is
once again rotated, as shown by the arrow "C" in Fig. 3C, to place
the fourth cutting edge 47 on the top and in front of the block 55,
still with the second mounting surface 53 on the tooth adjacent the
mounting surface 79 on the block.
It will be seen that the improved saw tooth is easily and
correctly mounted on the saw, through the mounting block, and also
easily manipulated to locate any one of four cutting edges in the
proper cutting position.
While the cutting edges on the saw tooth have been shown to be
formed by straight, angled surfaces on the front and back surfaces
joining the top and bottom surfaces, they could also be formed with
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curved surfaces on the front and back surfaces joining the top and
bottom surfaces. As shown in Fig. 5, a saw tooth 1' can be provided
having front and back surfaces 9', 11' with concavely curved top
and bottom sections 13', 15' and 25', 27' respectively. The front,
curved, top and bottom serctions 13', 15' merge smoothly with the
straight, front central section 23' and the back, curved, top and
bottom sections 25', 27' merge smoothly with the straight, back,
central section 35'. The juncture of the front, top and bottom
sections 13', 15, with the top and bottom surfaces 3', 5', produce
straight cutting edges 41', 43' and the juncture of the back, top
and bottom sections 25', 27' with the top and bottom surfaces 3',
5' produce straight cutting edges 45', 47'. The top and bottom
sections 13', 15' and 25', 27, can be curved along a radius "r" of
suitable length.
If the tooth employs curved surfaces to form the cutting
edges, then the projection also employs similar, complementary
curved surfaces in place of the beveled surfaces in order to
properly mount the tooth on the block.
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