Note: Descriptions are shown in the official language in which they were submitted.
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REPI~CEABLE CUTTING TOOT}~ AND ROTARY TOOL E~SPLO~ lG IT
This invention relates to rotary machining tools
such as heavy duty circular saws and replacement cutting
teeth for such tools. ~his invention i5 particularly
useful on heavy duty circular saws used on whole tree
harvesters such as those commonly known as ~feller-
bunchers".
Backqround of the Invention
A rotary machining tool such as a circular saw will
typically comprise a disk adapted to be driven in a
rotary manner. The disk may have cutting teeth on its
periphery that are either integral with the disk or are
removable. A commonly used circular saw for a feller-
buncher apparatus is the Future 2000* system of Koehring-
Waterous that employs a circular saw disk combined withremovable cutting teeth. Such a saw disk will typically
~! have a diameter o approximately 54 inches; a thickness
~ of approximately 1 inch; and, a plurality (e.g. 16)
! buttresses on the periphery of the disk extending
~' 20 radially in the plane o the disk, that provide support
for replaceable cutting teeth. Each tooth has a rear
surface with a clevis for engagement with a leading edge
o a buttre~s, and a concave front or leading surface.
'l Each tooth and buttress have complementary through holes
~ 25 for receiving a threaded fastener. ~he side of the tooth
,~ closest to the centre of the disk when the tooth is
;~ engaged with the disk, has a cut-away portion with a
~ flat, angled face that engages with a complementary cut-
i~ away portion on the disk to prevent a tendency for a
i~ 30 counter-rotational movement of the cutting tooth that
will translate the cutting tooth in a outward direction
when the tooth comes into contact with the surface to be
cut. The primary cutting edge of the tooth (the first
edge to come into contact with the surface to be cut) is
a generally wedge shaped portion of a sphere having two
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laterally placed leading points that first come into
contact with the surface to be cut and a curved cutting
edge therebetween~ The primary cutting edge is defined
between the concave leading surface of the tooth and a
concave side of the tooth farthest from the centre of the
disk. The primary cutting edge is inclined towards the
direction of rotation of the disk as a result of the
angle of the through hole of the tooth. The two
remaining sides of the tooth define generally linear
secondary cutting edges which are responsible for
clearing the sides of t~e kerf created in the surface to
be cut. The two sides of the cutting tooth are inclined
such that the secondary cutting edges converge towards
the side of the cutting tooth closest to the centre of
the disk, to prevent binding o~ the cutting tooth in the
material to be cut. Such a tooth has a limited capacity
for sharpening of the primary and secondary cutting edges
and it is extremely dif~icult to sharpen the cutting
' edge~ while the tooth is mounted on the saw disk. When
the tooth is no longer functional due to dulling or
damage, the entire tooth must be replaced.
Other kinds of replaceable cutting teeth for
circular saws are known. For example, United States
,1
Patent no. 4,750,396 (Gaddis et al) provides a rotary
cutting tooth that may be removed from a saw disk. The
l tooth comprises a replaceable cutting portion and a
i separate portion for mounting the cutting portion on the
saw disk. This provides a cost advantage since the
amount of material in the disposable cutting portion may
be kept to a minimum and less expensive materials may be
employed in the separate portion used to mount the
cutting portion on a saw disk. A disadvantage of a
, system that employs a separate cutting portion and a
; portion for mounting the cuttlng portion on the saw disk
is that the extreme forces imposed on the cutting tooth
during operation of a heavy duty circular saw will
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inevitably cause movement of the cutting portion relative
to the mounting portion. This is parkicularly true when
the mating surface between the cutting portion and the
mounting portion is flat. Gaddis et al teaches a variety
of means to prevent lateral and radially outward
translation of the cutting portion when in use. However,
these translation prevention means consist of flat and
angular mating surfaces on both the cutting portion and
the mounting portion, which will inevitably wear~ Once
worn, the mating surfaces will no longer be precisely
complementary and it will not be possible to provide a
snug fit ~etween a new, replacement cutting portion and a
previously used mounting portion necessitating at least
. occasional replacement of both the mounting portion and
the cutting portion.
~ It is desirable to provide a cutting tooth having
1 the advantages of the prior devices described above and
l which is also adapted to minimize any tendency of a
~ separate cutting portion to move relative to the
,~ 20 supporting surface on which it is mounted. It is also
.~ desirable to provide a rotary cutting too]. comprising a
.~l disk shaped tool adapted to receive such an improved
I cutting tooth. It is also advantageous to provide a kit
1 for replacement of a one-piece cutting tooth such as that
jl, 25 described above, whereby the tooth may be replaced with a
separate cutting portion and a portion for mounting the
'`' cutting portion on the disk,. It is also desirable to
,'l provide an improved cutting tooth having cutting ~urfaces
! that allow for repeated sharpening, even while the tooth
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.1 30 is mounted on a rotary tool.
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~ Summary of the Invention
.-3 This invention provides a cutting insert for a
... ' xotary cutting tool of the kind comprising a disk and a~ plurality of removable cutting teeth, wherein the cutting
i~ 35 insert i~ shaped substantially as a section of a hollow
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cylinder having a concave front surface and a convex rear
surface, and at least three sides, wherein the rear
surface has means for removable attachment of the cutting
insert to a saw disk, and a first of said sides is angled
5 relative to the front and rear surfaces to define a first
cutting edge adjacent the front surface.
This invention also provides a cutting insert for a
rotary cutting tool of the kind comprising a saw disk
having a plurality of removable cutting teeth, wherein
10 the cutting insert is shaped substantially as a section
of a hollow cylinder having a concave front surface and a
convex rear surface, and at least three sides, wherein
the rear surface has means for removable attachment of
the cutting insert to said saw disk~ and a first of said
15 sides is concave and is angled relative to the front and
rear surfaces to define a curved primary cutting edge
~ adjacent the front surface, and wherein second and third
i~Z sides of the insert adjacent the first side converge in a
¦ direction away from the first side, the second and third
.l 20 sides defining substantially linear secondary cutting
i edges adjacent the front surface.
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`, Thi.s invention also provides the aforementioned
i cutting in~erts in combination with a disk of a rotaryl cutting tool, wherein the disk has a part-cylindrical:~ 25 concave supporting surface on a peripheral surace of the
~i disk, wherein the suppcrting surface is shaped to be
~, complementary to the rear surface of the insert for
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.~ receiving said rear surface.
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~3 This invention also provides a tree felling circulax
30 saw disk having a plurality of elements extending
radially from a periphery of the disk for supporting
Z cutting teeth, wherein each of said elements has a
I leading face having a part-cylindrical concave surface
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for supporting a cutting tooth, and means for removable
attachment of the cutting tooth to each of said elements.
This invention also provides a kit for replacement
of a cutting tooth removably attached to a peripheral
5 surface of a tree felling circular saw disk comprising:
cutting insert shaped substantially as a section of
a hollow cylinder having a concave front surface and a
convex rear surface and at least three sides, wherein a
first of said sides is concave and is angled relative to
10 the front and rear surfaces to define a curved primary
cutting edge adjacent the front surface, and wherein the
second and third sides define substantially linear
secondary cutting edges adjacent the front surface;
an intermediate element having a concave front
15 surface shaped complementary to the rear surface of the
cutting insert; and
' wherein said cutting insert and intermediate element
J have means for receiving a removable fastener for
;l attachment of the insert and the intermediate element to
~ 20 the disk.
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l A cutting insert of thi~ invention is particularly
,l useful as the cutting portion of a replaceahle cutting
.. l tooth ~or the heavy duty circular saws employed i.n the
;, logging industry (such as on a feller-buncher apparatus)
sl 25 and has application ln similar forms of circular saws and
~; rotary cutting tools. The cutting insert may be
constructed from a hollow, generally cylindrical object
comprising an appropriate material for the cutting
insert. For example, a cutting insert for a feller-
30 buncher saw disk may be conveniently prepared from a
~i, section taken from the wall of an annealed steel alloy
./ pipe that is appropriately hardened to retain a cutting
l edge. Preferably, the section wlll have four sides (e.g.
i square or rectangular) although the insert may be
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constructed as a triangular section or a section having
more than four sides. The surfaces of the section may be
machined to appropriate dimensions and means for
fastening the cutting insert to the rotary tool may be
provided, such as a through hole in the cutting insert
for receiving a removable fastener such as a threaded
bolt. The cutting insert is preferably machined to
provide cutting surfaces that will extend radially and
optionally, in a lateral direction beyond the supporting
means for the insert and the disk of the rotary cutting
tool to allow for repeated sharpening of the cutting
insert while mounted on a rotary cutting tool disk. Such
a cutting insert may be produced at a cosit substantially
lesis than typical one-piece cutting teeth. In addition
to the cost savings resulting from the construction of a
cutting tooth of this invention, provision of sharpenable
cutting edges on the cutting insert will increase the
life expectancy of the cutting insert and provide further
cost savings.
A cutting insert of this invention used in
conjunction with a disk having a supporting surface for
!l the insert that is concave and complementary in shape to
the convex rear surface of the insiert will extend the
life expectancy of both the cutting insert and the
supporting surface since movement of the insert relative
to the supporting surface is prevented, thereby reducing
wear. In addition, any wear that iis incurred will be
evenly distributed across the mating surfaces of the
cutting insert and its support allowing for continued
i 30 reuse of the supporting surface with replacement cutting
,~ inserts.
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~,~ A cutting insert of this invention constructed as
described above may be machined to provide a particularly
~; useful primary cutting edge having two laterally sipaced
;l 35 cutting points and a curved cutting edge therebetween.
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Furthermore, machining of the section of the hollow
cylinder to provide a primary cutting edge between the
inside (concave) surface of the hollow cylinder and a
side of the section having a plane that crosses the
cylindrical axis of the section, allows for production of
a primary cutting edge as a suhstantially spherical
wedge, as is the case with the Future 2000* cutting
tooth. However, it is also possible to provide the
primary cutting edge on a side of the section of the
hollow cylinder that is generally parallel with the
cylindrical axis of the section.
While it is intended that a cutting insert of thi
invention be constructed from a hollow cylinder such as a
pipe, it is not necessary that the section be that of a
hollow, precisely cylindrical object. In order to
complement a concave surface on a supporting element or
to provide a desired curved cutting edge, it may be
¦ advantageous for the radii of the convex rear surface and
concave front surface of the cutting insert to differ.
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In applications where a cutting insert of this
;~ invention is intended to replace a cutting tooth of a
¦ pre-existing rotary cutting tool, it is preferable to
provide an intermediate element adapted to support the
cutting insert on the disk of the rotary cutting tool.
~ 25 Such an intermediate element will have a concave front
;~ surface complementary to the convex rear surface of the
;~ cutting insert and means for attachment to a pre-existing
rotary cutting tool disk. For example, the intermediate
Z element may have a clevis portion that engages with the
30 periphery of the disk and fastening means for attachment
to the disk. The fastening means may be complementary
~l with the fastening means of the cutting insert. For
¦ replacement of a Future 2000* cutting tooth, the
~¦ intermediate element may be similar in shape to the
35 original cutting tooth, except that the intermediate
element's dimensions will be smaller in order to allow
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for proper positioning of the cutting insert relative to
the saw disk; and, both the cutting insert and the
intermediate element will have complementary through
holes to receive a threaded fastener for attachment to
the saw disk.
Preferably, the intermediate element will be
constructed from a suitable, non-hardened metal. It is
also preferable for the concave front surface of the
intermediate element to have dimensions les~ than the
convex rear surface of the cutting insert in order that
the sides of the cutting insert defining the cutting
edges extend beyond the intermediate element allowing for
sharpening of the cutting edges while the insert is
mounted on a saw disk.
A cutting insert of this invention may be used on an
~ improved rotary cutting tool disk that is adapted to
j support a plurality of cutting inserts without the
1 interpo~ition of separate supporting means. Such a disk
i will preferably have a plurality of buttresses that
extend radially from the periphery of the disk, and may
~ have a profile similar to the buttresses of the Future
.~ 2000* saw disk~ The buttresse~ also extend beyond the
plane of the disk to allow a concave front ~urface to be
~ con~tructed on a leading face of the buttress to support
,.~ 25 a cutting insert of this invention. A leading face of a
buttress substantially faces the direction of rotation of
the disk. To facilitate machining of the concave
~urface, a through hole may be provided on the periphery
.i o the disk immediately adjacent the leading face of the
buttress. The hole acts as a clearance hole and it may
:l be plugged with a removable plug. The peripheral ~urface
i¦ of the removable plug may be shaped to accommodate means
3~! on the cutting insert intended to limit outward
~ kranslation of the cutting insert when in use. For
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211~617
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example, the cutting insert may have an angled cut-away
portion on its side closest to the centre of the disk
that is complementary to an angled cut-away portion on
the clearance hole plug resulting in a translation
preventing means similar to that used in the Future 2000*
system. It is also preferable that the dimensions of the
convex rear surface of the cutting insert exceed those of
the concave front supporting surface of the buttress in
order that the surfaces of the cutting insert defining
its cutting edges extend beyond the buttress of the disk
to allow for sharpening of the cutting edges~ while the
cutting insert is mounted on the disk.
It is preerable that an intermediate element for
supporting a cutting insert o-~ this invention and an
improved saw disk of this invention be construated of a
metal that is relatively resistant to abrasion and may be
repaired by welding. This is particularly advantageous
when threaded fasteners are used to attach a cutting
tooth to a disk, since use of a cutting torch is
sometimes necessary for removal of the fastener. A
suitable material for such an intermediate element or
I improved disk is Sc~ndia 400* steel. While many known
materials may be employed in the cutting teeth and disks
of thi~ invention, the combined use of an alloy such as
i 25 Scandia 400 in the disk or the intermediate element, and
a suitably hardened annealed steel alloy for the cutting
insert is cost effective.
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Brief_Description of the Drawinqs
Fig. 1 is a plan view of circular saw disk of the
Future 2000* kind for a feller-buncher apparatus. A
single cutting tooth is shown in phantom outline. The
il direction of rotation o~ the disk is illustrated by the
~ arrow.
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Fig. 2 is a partial plan view of a circular saw disk
of the Future 2000* kind showing a buttress of the ~aw
disk partially cut away and a cross~section of a cutting
tooth mounted on the saw disk. The direction of rotation
of the disk is illustrated by the arrow.
Fig. 3 is a perspective view of a cutting tooth of
the Future 2Q00* kind.
Fig. 4 is a partial plan view of a circular saw disk
of the Future 2000* kind showing a buttress of the ~aw
disk partially cut away and a cross-section of an
intermediate element and cutting insert of this invention
mounted on the saw disk.
.!
Fig. 5 is an exploded perspective view of a cutting
insert and intermediate element of this invention.
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Fig. 6 is a partial plan view o a saw disk of thi~
invention showing a buttress of the saw disk partially
cut away and a cross-section of a cutting insert of this
invention mounted on the saw disk.
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Fig. 7 is an exploded perspective of a buttress of a
saw disk of this invention and a cutting insert of this
invention.
De~cription of the Preferred Emhodiments
Preferred embodiments of this invention will be
described for use in a circular saw suitable for a
feller-buncher apparatus; and, in comparison to the
~¦ circular saw disk and cutting tooth of the Future 2000*
s~ system.
, i
The Future 2000* system is illustrated in Figs. 1 -
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3 as prior art. A plurality of buttresses 1 are formed
on the periphery of saw disk 2. The direction of
rotation is illustrated by arrow A. A typical saw disk
will have a radiu~ of approximately 54 inches, there will
5 be approximately 16 buttresses and the buttresses and the
, disk will have a thickness of about one inch. Each
i~ buttress is adapted to support a cutting tooth 3 on its
leading face. The buttress and cutting tooth have
complementary through holes 4a and 4b adapted to receive
10 a threaded fastener 5 for attachment of the cutting tooth
' to the buttress. The cutting tooth has a concave front
or leading surface 6 an~ a concave surface 7 furthest
from the centre of the disk which together define a
', primary, curved cutting edge 8 and leading points 9a and15 9b. The primary cutting edge is shaped substantially as
a spherical wedge and the leading points are first to
, contact the surface to be cut. The angle of through
j hole 4b in the cutting tooth is such that when the toothis mounted, leading points 9a and 9b and primary cutting
20 ed~e 8 are inclined in the direction of rotation of the
saw disk. Side surfaces lO and 11 of the cutting tooth
, are slightly inclined towards a clevis 12 formed in the
rear surface of the cutting tooth. 5ide surfaces 1~ and
11 define secondary linear cutting edges 13 and 14 which
25 converge in the direction of the bottom surface 15 of the
tooth providing for material removal from the side~ of
the kerf, without binding of the saw tooth in the ker.
Clevis 12 straddles the buttress. A cut-away portion 16
is located on the periphery of the saw disk immediately
] 30 adjacent the leading face of the buttress. The cut-away
portion has a flat, inclined surface 17 lying in the
~¦ direction of rotation of the disk that is complementaryl to the flat inclined surface 18 of a cut-away portion 19 in the bottom surface 15 of the cutting tooth.
35 Engagement of the complementary cut-away portions of the
cutting tooth and the disk limit a tendency of the
cutting tooth to rotate in a direction oppo~ite to that
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of the saw disk upon contact of the primary cutting edge
with a surface to be cut which would result in outward
translation of the cutting tooth from the saw disk.
A preferred cutting insert 20 of this invention is
illu~trated in Figs. 4 and 5 in conjunction with an
intermediate element 40 of this invention. The
intermediate element is adapted to attach the cutting
insert to buttress 1 of a saw disk 2 of the kind
fl illustrated in Figs. 1 and 2 wherein the buttress has a
through hole 4a adapted to receive a threaded fastener 5.
Cutting insert 20 is preferably constructed from a
generally rectangular section taken from the wall of a
pipe constructed of 4140 annealed steel alloy and the
insert is heat treated to approximately 50-52 on the
Rockwell Scale. For use on the saw disk described in
'1 Figs. 1 and 2, the pipe may have an outer radius of
approximately 2-inches which will become the radius of a
convex rear surface 21 of the cutting insert.
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In the preferred embodiment illustrated, the cutting
insert 20 is oriented so that the cylindrical axis of the
section illustrated by dotted line 22 will be in the
plane of the disk when the insert is mounted on the disk.
Concava front surface a3 of the cutting insert will be
the leading surface of the insert. Concave front ~urface
23 may be ground to provide a curved surface having a
l greater radius than the rear surface 21 of the in~ertO
For example, where 2-inch outer radius pipe is used, the
front surface 23 may be ground to have an approximately
J 2.4-inch radiu~.
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~il 30 First side surface 24 of the cutting insert, which
in Figs. 4 and 5 will be the surface of the insert
; furthest from the centre of the diskt is angled relative
~; to the front and rear surfaces of the insert to provide a
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curved primary or first cutting edge 25 and leading
points 30a and 30b o Side surface 24 may be ground in
order that the surface is concave resulting in primary
cutting edge 25 being defined by a substantially
spherical wedge comprising side surface 24 and front
surface 23.
Front surface 23, and adjacent second and third side
surfaces 26a and ~6b define substantially linear second
and third (secondary) cutting edges 27 and 28 Side
surfaces 26a and 26b converge in a direction away from
first surface 24 towards a fourth side surface 29 in
order that secondary cutting edges 27 and 28 be inclined,
preferably approximately 3, to limit binding of the
- cutting insert in the kerf. Preferably, edges 31a and
i 15 31~ are chamfered or rounded, thus leading points 30a and
i! 30b will also be rounded and the primary and secondary
`i cutting edges will be of a continuous nature.
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~I Side surface 29 of the cutting insert has a cut-away
portion 32 having a flat, inclined surface 33 that is
`!'. 20 adapted to complement the flat inclined surface 17 of the
cut-away portion 16 of the saw disk shown in Figs. 1 and
2. Countersunk through hole 34 i9 adapted to receive
threaded ~astener 5 and is angled in order that the
leading points 30a and 30b will be inclined in the
direction of rotation of the saw disk.
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'J'~l The cutting insert 20 may be readily attached to a
il saw disk of the kind shown in Figs. 1 and 2 by
~¦ interposing intermediate element 40 between the cutting
Yil insert and buttress 1 of the saw disk. In the
illustrated embodiment, the intermediate element is
,~ similar in shape to the cutting tooth illustrated in Fig.
3 and i9 constructed from Scandia 400* steel. The
intermediate element has a concave front surface 41 that
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is complementary to the convex rear surface 21 o-f the
cutting insert and which receives the cutting insert.
Since complementary surfaces 41 and 21 have
substantially circular profiles, friction between the
parts will be evenly distributed over the complementary
surfaces. Furthermore, cutting insert 20 will not be
able to turn relative to intermediate element 40 when the
fastener 5 is used to attach the cutting insert to the
intermediate element and the buttress 1.
Clevis 42 is provided on the surface of the
intermediate el0ment opposite the front surface, which
corresponds to clevis 12 in Figc 3. Angled through hole
43 is provided in the intermediate component and is
; complementary to through hole 34 of the cutting insert.
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, 15 As is shown in the exploded view of Fig. 5, the
`I height and width dimensions of the front surface 1 of
intermediate element 40 are less than that of the rear
surface 21 of cutting insert 20. Thus, when the cutting
insert is attached to the intermediate element, side
~ 20 surfaces 26a, 26b, and 24 will extend beyond the
;l peripheral surfaces of the intermediate element to permitrepeated sharpening of the cutting edge~ while the
1 cutting insert is mounted on a saw dislc. Surface 44 of
the intermediate element is inclined and is concave to
provide clearance similar to that of surface 7 of the
cutting tooth in Fig. 3.
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This invention makes it possible to provide a kit
for replacement of cutting teeth on a rotary cutting
-~ tool. Such a kit will include one or more cutting
c~ 30 inserts of this invention, together with one or more
intermediate elements shaped to permit the cutting insert
of this invention to be attached to the disk of a pre
~l existing rotary cutting tool. For example, a kit for
`;, replacement of the cutting teeth of the disk shown in
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Figs. 1 - 3 may comprise cutting insert 20 and
intermediate element 40 shown in Fig. 5 and, optionally,
a threaded fastener 5 suitable for attachment of the
cutting insert and intermediate component to the saw
disk. The kit may comprise additional cutting inserts
since it is expected that the intermediate component will
not have to he replaced unless it is severely damaged.
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Figs. 6 and 7 illustrate an improved disk for a
rotary cutting tool that may be used with a cutting
insert of this invention. In the illustrated embodiment,
buttress 51 is built-up on the periphery of circular saw
disk 52. For example, while di~k 52 may have a thickness
of approximately 1-inch, buttress 51 extends both above
and below the plane of the disk and radially beyond the
periphery of the disk to provide a support having
¦ dimensions similar to that provided by intermediate
¦ element 40 mounted on buttress 1 shown in Fig. 4O It is
intended that disk 52 will have a plurality of spaced
apart buttresses 51 around the periphery of the disk, as
is the case with disk 2 ~hown in Fig. 1.
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¦ Buttress 51 has a concave, part-cylindrical shaped
¦ leading surface 53 that is complementary to the convex
rear surface 21 of cutting insert 20, and an inclined,
concave surface 56 that provides clearance in the same
l 25 way as surface 44 of the intermediate element shown in
¦ Fig. 5. As is shown in the exploded view of Fig. 7, the
dimensions of leading surface 53 are preferably less than
that of rear surface 21 of the insert to provide an
~l extension of the cutting surfaces of the insert beyond
.~ 30 the periphery of buttress 51, to facilitate sharpening.
Clearance hole with removable plug 54 i6 positioned
through the periphery of the disk immediately adjacent
leading surface 53. The clearance hole facilitate~
grinding of leading surface 53. The plug may have angled
outer surface 57 that is flat and i~ complementary to
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angled surface 33 of cutting insert 20 shown in Fig. 4.
Plug 54 may be removed to facilitate repair of the disk.
The disk is constructed from a suitable metal alloy such
as Scandia 400* steel that may be repaired by welding.
Buttress 51 has a through hole 55 that is complementary
to through hole 34 of cutting insert 20 and is adapted to
~i; receive threaded fastener 5 which may be a bolt and nut
combination in cases where it is desirable ko not thread
the interior of through hole 55.
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The improved rotary cutting tool disk having
buttresses provide a plurality of supporting surfaces for
cutting inserts of this invention may have a substantial
amount of mass distributed on the periphery of the disk
which may improve the efficiency of the disk when in use.
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-! 15 It will be apparent to those skilled in the art that
many variations may be made in the inventions described
l herein. It is the intention of the inventor that such
3 variations be included within the scope of this invention
as if they were illustrated and specifically described
i3~ 20 herein.
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