Note: Descriptions are shown in the official language in which they were submitted.
~322a~3
WINGED CUTTING KNIFE FOR PRODUCING WOOD
CHIPS OR FLAKES
This application is a division of Canadian
Serial No. 549,089, filed October 13, 1987.
~echnic~l l~i~
The present invention relates to the
processing of wood, usually in the form of logs or
brush, and more particularly relates to an improved
apparatus which allows for efficient reduction of the
wood ir.to wood chips or flakes.
In known wood processing machines used to
convert logs into chips or flakes, it has been common
for the machines to include one or more cutting
members mounted either on the face of a rotating disc
or on the circumferential surface of a rotating drum.
During operation of the machines, wood members are
guided or urged into the rotating disc or drum so that
the knife-like cutting members cut away chips or
flakes from the wood members, and the wood members are
ultimately consumed.
Such prior art cutting members are typically
configured to cut a rectangular or similar cross
section in the wood members. However, many of these
configurations do not allow for efficient cutting of
the wood, as they require large surges of power during
the cutting stage, which necessitates the use of large
132~ 3
motors. Therefore such prior art devices tend to be
large, heavy and expensive.
Prior art devices also typically utilize
cutting members which are partially recessed within
the disc or drum. Although this configuration results
in a structurally effective attachment between the
cutting members and the disc or drum, it is
disadvantageous if unprocessable foreign material is
present with the wood. When such foreign material is
encountered, prior art machines typically jam, and
the risk of extensive and costly damage to the
machine is high. One example of such recessed cutter
mounting configurations is shown in applicant's U.S.
Patent No. 4,444,234, which discloses the use of a
drum having a plurality of the knives mounted within
recesses in a rotating drum.
The presence of unprocessable material is a
particular problem in processing stumps, brush and
other material of the kind remaining on the site or a
logging operation. Wood "hogs" used to shred such
material are subject to considerable down time and
damage to cutting elements when the latter encounter
rocks, metal or the like. Cutting members in the
past have been expensive to manufacture and sharpen,
and have been re-sharpened for additional use. Sig-
nificant expenditures of time and money have been
necessary to remove the cutting members, sharpen all
their edges, and reinstall them into the machine. An
example of such resharpenable cutting members is
shown in applicant's U.S. Patent No. 4,569,380, whlch
discloses the use of a cutting element having a
plurality of resharpenable cutting elements.
It has also been known to provide such wood
processing machines with separating grates, which
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_ allow the passage of adequately-reduced wood chips out
of the machine, but direct inadequately-reduced chips
back to the input hopper to be processed further.
These separating grates are typically formed out of a
platelike material which defines a plurality of
selectively-sized slots. Although these configurations
are effective to a degree, they are prone to wear,
which is disadvantageous in that the grate is
typically of unitary construction, and replacement of
the entire grate may be necessary in the case of an
excessively worn grate. Finally, such prior art
separating grates have limited effectiveness when
processing wood which has a tendency to break up into
elongate splinters, as such splinters may pass through
the slots although their length is unacceptable.
Therefore it may be seen that a need has
existed in the wood processing art for a cutting
member which facilitates power-efficient cutting and
shredding of wood products. It may also be seen that a
need has existed for a wood processing machine which
is subject to a minimum of damage when encountering
unprocessable foreign material, and has disposable
cutting members that can be replaced with a minimum of
time and effort. Furthermore, a need has existed for a
chip separating grate to be used in such wood
processing machines which is resistant to wear, and
does not allow the passage of wood chips having an
unacceptable length.
Summary of the In~ention
The present invention provides a cutting
member which facilitates power-efficient cutting and
shredding of wood products. The present invention also
provides a wood processing machine which is subject to
a minimum of damage when encountering unprocessable
foreign material. Finally, the present invention
provides a chip filtering grate which provides improved
processing and filtering.
Briefly the invention in one aspect provides a
5 cutting element extending above a mounting surface,
comprising a first cutting edge positioned a first
distance above the surface, and a second cutting edge
spaced apart from the first cutting edge, the second
cutting edge positioned at a second distance above the
10 surface less than or equal to one half of the first
distance.
Another aspect of the invention provides a wood
processing element for reducing the size of a wood member
passing across a separating grate defining a filtering
15 slot, the separating grate having a first and a second
side, and the filtering slot including a leading and a
I trailing edge. The wood processing element comprises
means defining at least one cutting edge for engaging the
wood member such that a portion is removed therefrom, the
20 means extending from the trailing edge of said slot,
means extending from the cutting edge for directing the
wood portion into the slot, and means for attaching the
wood processing element to the separating grate.
Although a cutting element or "hammer"
25 embodying the present invention can be used
, advantageously in many wood processing operations, such a
hammer is particularly effective when used on a wood
processing apparatus which also forms part of the present
invention. Generally described, the wood processing
30 apparatus comprises a cutting element for removing wood
from a wooden member, a surface for supporting the
cutting element, means for creating relative movement
between the surface and the wooden member, and breakaway
connecting means for positioning the cutting element on
35 the surface, the breakaway connecting means releasing the
cutting element from the surface responsive to a
predetermined resistance being encountered by the cutting
element.
'
Still another aspect of the invention
comprehends a wood processing machine for reducing the
size of a wood member into reduced wood portions,
comprising a separat.ing grate having a first and a second
side, and defining at least one filtering slot, the
filtering slot including a leading and a trailing edge.
Means are provided for transporting the wood member along
a path defined by the first side of the grate, such that
the wood member is first directed over the leading edge
of the slot and thereafter toward the trailing edge of
the slot. Means define at least one cutting edge, the
means extending from the trailing edge of the slot, and
means extends from the cutting edge for directing wood
portions into the slot such that the cutting edge engages
the wood member, and removes a portion of the wood member
having a size sufficient to pass through the slot, and
the directing means directs the wood portion through the
slot.
The filtering grate may also include a breakup
feature which discourages the passage of excessively long
"splinters" of wood through the grate. Such a
configuration comprises a separating grate having a first
and a second side, and defining at least one filtering
slot, the filtering slot including a leading edge and a
trailing wall, means for transporting wood chips along a
path defined by the first side of the grate, such that
the wood members are first directed over the leading edge
of the slot and thereafter into the slot, and a ledge
extending into the slot from the trailing wall for
engaging the wood chips such that the wood chips engage
the ledge and are further reduced by breakage.
Accordingly the invention further comprehends a
wood processing machine for reducing -the size of wood
chips, comprising a separating grate having a first and a
second side, and defining at least one filtering slot,
the filtering slot including a leading edge and a
trailing wall. Means are provided for transporting wood
chips along a path defined by the first side of the
~ 3 ~
grate, such that the wood chips are first directed over
the leading edge of the slot and thereafter into the
slot, and a ledge extending into the slot from the
trailing wall for engaging the wood chips such that the
wood chips engage the ledge and are further reduced by
breakage.
Further still the invention also provides a
wood processing apparatus comprising an elongate
cylindrical drum rotatably mounted about a horizontal
longitudinal axis, with at least one cutter extending
outwardly from the surface of the drum. Means rotate the
cylindrical drum about its longitudinal axis in a first
direction such that the cutter follows a circular path,
and feed means for mounted rotation adjacent to the drum
in a direction opposite to the first direction for
feeding the wood into the path of the cutter. Sensing
means sense a predetermined level of power required to
rotate the feed means, and reversing means is responsive
to the sersing means for reversing the rotational
ZO direction of the feed means.
Accordingly, the wood processing apparatus of
the present invention may also have a reversable feature.
More particularly the reversable feature includes an
elongate cylindrical drum rotatably mounted about a
horizontal longitudinal axis, at least one cutter
extending outwardly from the surface of the drum, means
for rotating the cylindrical drum about its longitudinal
axis in a first direction such that the cutter follows a
circular path, feed means for mounted rotation adjacent
to the drum in a direction opposite to the first
direction for feeding the wood into the path of the
cutter, sensing means for sensing a predetermined level
of power required to rotate the feed means, and reversing
means responsive to the sensing means for reversing the
rotational direction of the log.
. . .
7 l ~
_ It is a further object of the present
invention to provide an improved wood chip separating
grate.
Other aspectsr features, and advantages of the
present invention will become apparent upon review of
the following detailed description of embodiments of
the invention, when taken in conjunction with the
drawings.
10 ~
Fig. 1 is a pictorial view of the winged
hammer of the present invention as attached to a
typical mounting surface, shown in cutaway.
Fig. 2 is a side partial cutaway view of the
winged hammer of Fig. 2.
Fig. 3 is a side cross sectional view of the
rotating drum assembly which supports the winged
hamme- of Fig. 1.
Fig. 4 is a top partial cutaway view of the
rotating drum assembly of Fig. 3.
Fig. 5 is a partial cutaway view of the
interaction of the winged hammers and the stationary
anvils of the rotating drum assembly of Fig. 3.
Fig. 6 is a diagrammatic representation of the
cutting process as the winged hammers pass through the
wood members.
Fig. 7 is a cross sectional view of an
alternative rotating drum embodiment which supports
the winged hammer of Fig. 1.
Fig. 8 is an isolated cutaway side view of
Fig. 3, illustrating the interaction of the winged-
hammers and the grate.
Fig. 9 is a partial pictorial view of the
frame of the wood processing apparatus of Fig. 3,
,`':
~L ~ r~V h~
_ shown without the rotating drum to illustrate the
grate and anvil members.
Fig. 10 is an isolated pictorial view of an
alternative embodiment of ~he grate knife, with a slot
of the grate plate shown in phantom.
Fig. 11 is a plan view of the grate knife of
Fig. 10, as viewed from the left.
p~tai~.e.d .--De~
Referring now to the drawings, in which like
numerals represent like parts throughout the several
views, Figs. 1 and 2 show a winged hammer assembly 10
embodying the present invention. The winged hammer
assembly 10 includes a cutting head 12, a body 14, a
mounting screw 16, and a nut 17. As will be discussed
further in this application, the body 14 is fixed to a
` typical mounting surface 18 by weldments 20, or other
fastening means known in the art.
Referring now to Figs. 1 and 2, the body 14 of
the winged hammer assembly 10 is an elongate
rectangular member and is rigidly affixed to the
mounting surface 18 by a plurality of weldments 20.
The weldments 20 are preferably small beads lying
along the intersection of the body 14 with the
mounting surface 18. As discussed later in this
application, the weldments 20 are configured such that
the body 14 of the winged hammer assembly 10 may break
away from the mounting surface 18 during overstressful
operation of the winged hammer assembly.
The cutting head 12 is attached to the body 14
by the mounting screw 16, which passes through the
center of the cutting head and is captured behind the
body by a nut 17. The head of the mounting screw 16
defines a hex key cavity 19.
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The cutting head 12 is of a unitary
construction and includes a central cutting member 22,
and two wing members 24 extending to each side of the
central cutting member. The central cutting member 22
and the wing members 24 define a central knife 25, and
similarly shaped wing knives 26, respectively. When
the cutting head 12 is in mounted position, it may be
seen that the central knife 25 and wing knives 26 are
directed in a common direction away from the body
member. As shown in Fig. 1, it may also be seen that
the central knife 25 and wing knives 26 include upper
heel surfaces 27, 28, respectively, and side heel
surfaces 29, 31, respectively. The central knife 25 or
the wing knives 26 may be treated with a hardening
lS powder (not shown) to prolong the cutting life of the
cutting head.
Referring also now to Figs. 1 and 2, it may be
seen that the cutting edge 25E of the central knife 25
projects away from the mounting surface 18
approximately twice the distance than the cutting
edges 26E of the wing knives 26, although other
configurations may be used which fall within the
spirit and scope of the present invention.
Furthermore, it may be seen that the cutting edges are
the forwardmost elements of the hammer assembly 10
when in mounted positi.on, and are the first portion of
the cutting head 12 to engage the wood members as
discussed later in this application. Referring now to
Fig. 6, it may be seen that the cutting head is
configured to cut a cavity which is substantially the
shape of an inverted "T" relative to the mounting
surface 18.
Referring now to Fig. 3, the winged hammer
assembly 10 of the ~resent invention may be used in
combination with a rotating drum assembly 30. The drum
~ ~ 2 ~
_ assembly 30 includes a cylindrical rotating drum 32
which defines the previously-discussed mounting
surface 18, a frame 35, a central rotating shaft 37,
upper and lower toothed anvil members 40, 41,
respectively, first and second wood chip guides 42,
43, a separating grate 44, an inlet hopper 49, and an
outlet port 51. As shown in Fig. 4, the rotating drum
assembly 30 also includes bearings 55, and a flywheel
pulley 57.
~eferring now to Figs. 3 and 4, ~he rotating
drum 32 is rigidly affixed to the rotating shaft 37 by
welding or other means known in the art, such that the
longitudinal axes of the shaft and the drum are
substantially common, and the ends of the shaft
protrude from the ends of the rotating drum 32. The
ends of the shaft 37 are rotatably mounted within the
bearings 55, which are rigidly mounted within the
frame 35. Therefore it may be seen that the rotating
drum 32 is rotatably mounted within the frame 35 along
the longitudinal axis of the rotating shaft 37.
An input hopper 49 is provided above the
rotating drum 32 and accepts the wood products 100 to
be processed by the rotating drum assembly 30.
Referring now to Figs. 3 and 4, the wood members 100
may be inserted into the inlet hopper 49 by hand, if
suitably sized, or larger wood members may be inserted
into the inlet hopper 49 by bulldozers or front-end
loaders (not shown). If an exceptionally long wood
member, such as a large tree, is to be inserted into
the inlet hopper 49, this may be done by use of a
grappler 52, which can grapple one end of a long wood
member and feed the free end into the inlet hopper 49
to be consumed by the rotating drum assembly 30. Long
wood members may also be inserted into the inlet
hopper 49 by attaching one end of a chain or wire rope
î~2~3 ~ ~
11
(not shown) to one end of the wood member, attaching
the other end of the chain or wire rope to the bucket
of an end loader, and slowly lowering the free end of
the wood member into the inlet hopper 49. When a
5sufficient length of the wood member has been consumed
by the rotating drum assembly 30, the chai.n or wire
rope may be removed, and the remainder of the wood
member may then be dumped into the inlet hopper 49 to
be completely consumed by the rotating drum assembly .
10The hopper 49 is defined by the frame 35,
which provides side walls, and the drum surface. Upper
and lower toothed anvils 40, 41, respectively, are
elongate, and are rigidly mounted to the frame 35
adjacent to the mounting surface of the rotating drum
15such that the longitudinal axes of the upper and lower
anvils 40, 41, are parallel to the rotational axis of
the rotating drum 32. The anvils comprise alternating
rectangular teeth 46 and rectangular notches 47. The
teeth extend radially toward the center of the
20rotating drum 32. As will be discussed later in this
application, the hammer assemblies 10 pass through
corresponding notches in the anvils during rotation of
the rot;ating drum 32. The upper anvil 40 is
positioned in a throat formed between the bottom of
25one of the hopper side walls and the surface of the
drum to intercept wood being carried out of the hopper
by rotation of the drum. The upper anvil 40 combines
with the harnmer assemblies 10 to perform the initial
cutting of the wood members. The lower anvil 41 is
30positioned beneath the upper anvil, and performs a
secondary cutting process. The cutting processes are
discussed in detail later in this application.
The first and second chip guides 42, 43, are
rigidly attached to the frame 35 and positioned
beneath the rotating drum 32. The separating grate 44
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12
is rigidly attached to the frame 35 and is positioned
beneath the rotating drum 32 intermediate the first
and second chip guides 42, 43. Together, the chip
guides form a concentric partial sleeve spaced apart
from the rotating drum and communicating at both ends
with the input hopper 49.
Referring now to Fig. 4, the winged hammer
assemblies 10 are helically positioned upon the
circumferential surface of the rotating drum 32. In
the preferred embodiment, the hamrner assemblies 10 are
arranged in a plurality of rows running the length of
the rotating drum, the rows being spaced apart around
the periphery of the drum surface. For the purpose of
explaining the positions of the hammer assemblies on
the surface of the rotating drum 32, each row of
hammer assemblies will,now be assigned a particular
suffix, with one row being assigned as hammer
assernblies lOA, another row as hammer assemblies lOB,
and other rows lOC and lOD. Similarly, each element of
the assemblies will now have a similar suffix, for
example hammer assemblies lOA now include cutting
heads 12A, bodies 14A, central cutting members 22A and
wing members 24A. As the hammer assernblies interact
with the lower anvil 41 in a manner simllar to the
upper anvil 40, only the upper anvil w.ill now be
discussed.
Referring now to Figs. 4 and 5, the row of
hammer assemblies lOA interact intimately with spaced
apart notches 47 during rotation of the drum 32. The
central cutting members 22A pass through particular
notches 47 durin-g rotation of the drum, as the
associated wing members 24A pass closely outside the
teeth 46 of the upper anvil 40. As the drum rotates,
the row of hammer assemblies lOB rotate in different
radial planes from hammer assemblies lOA and interact
: - .
~ ~3 f~ 3
13
_ with notches 47 which are adjacent to the notches
through which hammer assemblies lOA passed. As the
drum 32 continues to rotate, hammer assemblies lOC and
lOD likewise pass through the remaining notches 47 in
the upper anvil 40. Therefore it may be seen that
after hammer assemblies lOA, lOB, lOC, and lOD have
sequentially passed through the upper anvil, all of
the notches 47 in the anvil have undergone interaction
by one hammer assembly, and the drum has rotated
approximately 180 degrees.
As shown in Fig. 3, the rows of hammer
assemblies are evenly disposed about the
circumferential surface of the rotating drum.
Therefore it may be seen that a similar cutting
lS process similar to the one just described occurs as
the drum rotates another 180 degrees. It may also be
seen that each notch 47 interacts with two different
hammer assemblies during each rotation of the drum 32.
Referring now to Figs 3 and 4, the method of
operation of the rotating drum assembly 30 with the
winged hammer assemblies lO is now discussed. A motor
(not shown) drives a belt (not shown) which drives the
flywheel pulley 57, thus rotating the center shaft 37
and the r.otating drum 32. As the drum 32 is rotated,
the halnmer assemblies lO intimately interact with the
upper and lower anvils 40, 41, as previously
discussed.
When wood members lO0 are placed into the
hopper, they contact the top of the rotating drum 32
and are drawn toward the stationary upper anvil 40.
When the wood members encounter the upper anvil, the
upper anvil prevents further movement of the wood
members. Referring now also to Fig. 6, the cutting
heads 12 of the hammer assemblies lO then make a first
pass through the wood members lO0, removing a cross
14 ~ 3 ~ 3
section similar to that previously discussed. As the
cross section of wood is removed, the wood members
drop down to the drum surface and are further consumed
by succeeding cutting heads 12, until the wood members
are eventually completely consumed.
As portions of the wood mer~ers 100 are cut
away by the cutting heads and displaced through the
upper anvil 40, they break up along the grain into the
form of wood chips 101, and are drawn toward the lower
anvil 41 by the hammer assemblies 10 and by the
influence of gravity. As previously discussed, the
hammer assemblies 10 interact with the lower anvil 41
as with the upper anvil 40. Therefore it may be seen
that a similar cutting action is imparted to the wood
chips lO1 by the hammer assemblies 10 and the lower
anvil 41, further pulverizing, shredding and breaking
up the wood chips.
After passing the lower anvil 41, the wood
chips 101 fall upon the first chip guide 42, and are
drawn toward the separating grate 44 by the hammer
assemblies 10 and by the influence of gravity. When
the wood chips 101 contact the separating grate 44,
chips srnall enough to pass through the separating
grate do so and fall into the outlet port 51, and are
then removed from the rotating drum assembly 30 by a
conventional conveying means (not shown). The wood
chips 101 too large to fall through the separating
grate 44 are dragged across the top of the separating
grate and along the second chip guide 43, and are then
returned to the inlet hopper 49. These chips 101 are
then subjected to another processing cycle until they
are small enough to pass through the separating grate
44.
Referring now to Figs. 8 and 9, the particular
interaction of the harnmer assemblies 10 and the
i
. : . . . ~ ~ :-
;
... .
_ separating grate 44 is now discussed. The separating
grate 44 includes a plurality of D-shaped slots 45. As
shown in Fig. 9, the D-shaped slots 45 are arranged in
a series of spaced-apart rows with each row being
substantially parallel to the rotating axis of the
rotating drum, and the linear edges of the D-shaped
slots 45 in each row being in substantial alignment,
and also being on the "trailing" edge of ~he slot with
respect to rotation of the rotating drum 32.
A grate knife 70 is positioned in a
corresponding slot 45 against the trailing linear edge
of the slot. It may be seen that the grate knife 70
includes a wall portion 72, a cutting portion 74
defining a cutting edge 75, a breakup ledge 76, and a
lS positioning stop 78. It should be understood that the
grate knives 70 have uniform cross sections as taken
through a plane normal to the rotational axis of the
rotating drum.
The wall portion 72 of the grate knife is
substantially rectangular in cross section. When the
grate knife 70 is installed, the wall portion 72
contacts the trailing wall of the D-shaped slot 45,
and the primary planar sur~aces of the wall portion
extend substantially radially from the drum 32.
The cutting portion 74 is substantially wedge-
shaped, extends from one corner of the inner edge of
the wall portion, and converges to the cutting edge
75. When the grate knife 70 is installed, the cutting
portion 74 extends inwardly toward the drum and away
from the trailing edge of the corresponding D-shaped
slot, and the cutting edge 75 is substantially
parallel to the rotational axis of the rotating drum
32, and extends on the drum side surface 50 of the
separating grate 44.
16
The breakup ledge 76 extends at a right angle
from the end of the wall portion 72 on the same side
as the cutting portion 74, and combines with the wall
portion to define a corner 77. When the grate knife 70
is installed, the breakup ledge 76 extends outside of
and tangentially away from the separating grate 44.
The positioning stop 78 extends away from the
wall portion 72 at a right angle on the opposite side
of the wall portion from the breakup ledge 76. The
positioning stop 78 is positioned along the wall
portion 72 such that during installation of the grate
knife 70, the positioning stop 78 contacts the outer
surface 48 of the separating grate 44, and the cutting
edge 75 and breakup ledge 76 are thereby positively
lS positioned relative to the separating grate 44 as
previously described. The grate knife 70 is then
rigidly secured to the grate 44 by a weldment 80,
although other securing means may be used such as
threaded fasteners, rivets, or glue.
Interaction of the separating grate 44 and a
hammer assembly 10 is now discussed. As the hammer
assembly 10 rotates relative to the separating grate
49 and attached grate knives 70 as indicated by the
arrow in Fig. 8, it may be seen that the cutting edge
25E of the hammer assembly 10 passes closely alongside
the cutting edge 75 of the grate knives 74. A passing
distance of one-eighth of an inch is suggested between
the two cutting edges, although other distances may be
used without departing from the spirit and scope of
the present invention. As the hammer assemblies 10
pass by the grate knives 70, it may be seen that wood
~embers (not shown) may be caught between the grate
knives 70 and the hammer assemblies 10, and cut by the
cutting edges 75, 2SE, respectively, thus
supplementing the previously-discussed processing done
17 ~ 3 2 ~
by the hammer assemblies and the upper and lower
anvils 40, 41, respectively.
As previously discussed, the configuration of
prior art grates tended to allow excessively long wood
members having an acceptable cross section to
disadvantageously pass through their respective slots.
Rubbing of the wood over the corners of the slots can
rapidly round off the corners and make the grate less
effective in breaking up the wood. However, it should
be understood that the applicant's configuration
significantly reduces this tendency. Should an
excessively long wood member pass through one of the
slots 45, it will tend to contact the breakup ledge 76
of a corresponding grate knife 70 and become jammed
within the corner 77 of the grate knife. As the hammer
assemblies continue to pass over the slot 45, it
should be seen that an excessively long wood member
would be bent over and broken or cut, thus reducing
its length.
An alternative grate knife 170 is shown in
Figs. 10 and 11. The knife 170 possesses all of the
~ advantages of the grate knife 70, but further includes
; ear members 175. It may be understood that wood chips
could tend to jam in the acutely angled space between
the cutting portion 74 of the grate knife 70, and the
side edges of the slot 45, in grate knife 70. However,
the ear members 175 of the alternative grate
configuration 170 extend outwardly from the side edges
of the cutting portion 174, to define a vertical
cutting edge at each side of the knife 175. This
increases the angle formed by the grate knife 170 and
the slot 45, thus decreasing the possibility of wood
jamming at that point. It should be understood that
the alternative embodiment also includes the
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18 ~ 3 2 ~J ~ ~ ~
previously-discussed wall portion 72, the cutting edge
75, the breakup ledge 76, and the positioning stop 78.
It should be understood that grate knives 70,
170, have been described in combination with the
S hammer assemblies 10 of the present invention.
However, it should be understood that the grate knives
of the present invention may be effective with
conventional prior art cutting members. Furthermore,
it is not necessary that the grate knives 70, 170, be
separate in construction from the grate. It is
possible that the cutting edges 75 and breakup ledges
76 be defined by the grate itself, while remaining
within the spirit and scope of the present invention.
Finally, it should be understood that the cutting
edges 75 and breakup ledges 76 need not be used in
combination, but may be used independentLy.
Referring now to Fig. 6, the particular manner
in which the cutting heads pass through the wood
members after the first pass is shown
diagrammatically. As previously discussed, the cutting
heads 12 of the hammer assemblies 10 remove a cross
section 60 of wood similar to that of the cutting
heads as the cutting heads make their first pass
through the wood members. After this cut is made, the
wood members drop down under the influence of gravity
to contact the surface of the drum 32. It may be seen
that the distance which the wood member drops after
each cut is approximately equal to the depth of cut of
the wing members 24, since the wood members 100
contact the rotating drum on the portions of the wood
members which have just been previously cut by the
wing members. For wing members as described above
having a 3/4" height, the wood member drops about
3/4". This movement of the wood aLso determines the
depth of subsequent cuts of the central cutting
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19
_ members 22, which would cut 3/4" in the preferred
embodiment. By limiting the depth of cut, the power
required to drive each cutting member through the wood
members is also limited. If a reasonable number of
S cutting members is placed in each row (such as four,
shown in Fig. 4), the number of cutting members that
can simultaneously engage the wood is limited, and the
size of the drive motor can be limited
correspondingly. However, production capacity need not
be sacrificed, because the number of rows on the
rotating drum can be increased. For example, six
layers of wood could be removed in a single rotation
of the rotating drum. Because the cutter configuratio~.
and method of mounting is 50 inexpensive and
lS uncomplicated, many more cutters can be economically
and selectively installed on a drum than was the case
with conventional wood processing machines. A 48 inch
drum configured as shown in Fig. 4 which makes two
cuts per revolution, can be operated with a 400
horsepower engine. The same drum carrying half as
many knives and making one cut per revolution could be
operated with a 200 horsepower engine.
When another hammer comes along ln the same
radial plane aligned to pass through the same notch in
the anvil as the first hammer, the second hammer
removes three separate rectangular cross sections: the
central cutting member 22 removes a rectangular cross
section 61 representing a depth of cut equal to the
height of the wing members, and each of the two wing
members remove a cross section 62 similar to their
cross sections. Therefore it may be seen that the
unique cross section of the cutting heads allows for
removal of three separate cross sections of wood for
each pass of each cutting head through the wood
members.
~3~ 3
As previously discussed, the hammer assemblies
10 are affixed to the surface of the rotating drum 32
by weldments 20. These weldments 20 are configured
such that if a piece of unprocessable material such as
metal is encountered by a particular hammer assembly
10, the weldments 20 associated with that hammer
assembly 10 are torn away, thus allowing the hammer
assembly to break away from the drum, and allowing the
drum to continue rotation without damage to more
expensive elements of the machine, such as the
rotating shaft or motor.
In the event that a hammer assembly 10 breaks
away from the surface of the rotating drum 32 as
previously described, the cutting process is
terminated by the machine operator. ~ replacement
weldement 20 is then provided to replace the hammer
assembly 10. If the hammer assembly is damaged, a
replacement is provided. Providing such replacement
weldments and hammer assemblies is a relatively simple
and inexpensive process, especially in comparison to
such alternatives as replacing a drive shaft or motor.
After processing of wood for a time by the
rotating drum assembly 30, the cutting edges of the
cutting head 12 become dull. The lifetime of the
cutting edges depends upon the nature of the material
being cut, and whether it includes soil, sand or
debris wlth the wood. Dulling of the edges decreases
the efficiency of the rotating drum assembly 30, as
more power is required to drive the cutting heads 12
through the wood members. In this event, the rotating
drum assembly 30 is turned off, and the dull cutting
heads are removed and replaced with new cutting heads
by simply removing the bolt 17 and mounting screw 16,
removing the dull cutting head, and securing a new
cutting head in its place. If desired, the cutting
21 1 3 ~J 2 ~ ~
_ edges of the dull cutting heads may then be
resharpened. However, because of the manner in which
the relatively small and simple cutting head 12 is
attached to the body 14, the applicant has found that
S it is more economically advantageous to fabricate new
cutting heads instead of sharpening dull cutting
heads, and therefore the cutting heads can be treated
as a disposable item.
The cutting assemblies may be mounted onto
various existing apparatus The apparatus 130 shown in
Fig. 7 is similar to that of the apparatus disclosed
in U. S. Patent No. 4,444,234, which patent may
be reviewed for further details of such apparatus. A
rotat-ny drum 132 which supnorts the winged hammer
assemblies is rigidly mounted upon a shaft 133
rotatably mounted to a frame 135. A set of toothed
support rollers 137 are rigidly mounted to a second
shaft 138, which is also rotatably mounted to the
frame 135. The longitudinal axes of the two shafts are
substantially parallel. During operation of the
apparatus, to process brush and the like, the toothed
support rollers 137 are rotated clockwise relative to
the viewer to force feed the material toward the drum
132, and the drum 132 rotates counterclockwise. The
hammer assemblies 10 on the drum 132 cut through the
wood being forced toward the drum by the rollers 137.
Alternately, the apparatus 130 may be operated
to process large wood members such as logs in the
manner described in U. S. Patent No. 9,444,234. A wood
supply conveyor 139 supplies wood members 100 into a
"cradle" formed by the drum 132 and the toothed
support rollers 137, such that the longitudinal axis
of the wood member is substantially parallel to the
rotational axes of the toothed support rollers and the
drum. As the drum 132 and the toothed support rollers
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~2 ~ ~2~
_ 137 rotate, the wood member rotates counterclockwise,
and is cut about its outer circumferential surface by
the hammer assemblies. As the wood member is
continuously rotating relative to the drum, it should
be understood that the horsepower requirements are
minimized by minimizing the length of cut made by the
hammer assemblies 10 extending from the drum. This
cutting process may continued until the wood member
100 is completely consumed, or may be terminated when
a desired rounding of the wood members is achieved,
upon which the toothed support rollers 137 pivot
downwardly relative to the drum, and guide plates 140
guide the wood members downwardly and away from the
drum.
lS Should at any time the power requirements for
driving the apparatus 130 in the force feed
configuration become excessive, the rotational
direction of the second shaft 13~ (and attached
toothed support rollers) may be switched and reversed.
This reversal may be done via conventional hydraulic
control circuitry by a manual operator, or may be done
in response to a load-indicating signal associated
with the power source, such as a tachometer in the
case of a combustion engine, or an ammeter in the case
of an electric motor.
~ lthough Fig. 7 discloses the use of toothed
support rollers 137 in combination with the drum 132,
it should be understood that any roller means may be
used which rotate the logs relative to the drum 132 as
previously described. For example, a drum having
radially protruding spikes could be used in place of
the support rollers 137. Similarly, a series of
direction rollers could be provided which could be
mounted to a shaft similar to the toothed support
rollers 137, except that the disklike rollers could be
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_ provided with staggered notches about their periphery,
configured to engage the wood members similar to the
teeth in the toothed rollers 137.
Although the use of the hammer assemblies has
S been disclosed only in combination with a drum-shaped
supporting apparatus, it should be understood that a
rotating disc configuration of the type shown in U. S.
Patent No. 4,569,380 could also be used
to support the hammer assemblies. Suçh
a configuration could include a disc
mounted on a rotating shaft which is driven in a
manner simi'ar to that of the rotating drum assembly.
The hammer assemblies could be mounted by break-away
weldments to the disc, as replacements for traditional
knives. If desired, anvils could be positioned
relative to the hammer assemblies such that the hammer
assemblies pass in intimate relation to the anvils
during rotation of the disc. The hammer assemblies
could also be used in a counterrotating dual drum
configuration, with the hammer assemblies being
mounted on one drum and cooperating with pockets
defined by the second drum.
Therefore it may be seen that the present
invention provides a novel and improved wood cutting
member which facilitates power-efficient cutting and
shredding of wood products. The present invention also
provides a wood processing machine which is subject to
a minimum of damage when encountering unprocessable
foreign material. Additionally, the present invention
provides a chip filtering grate which provides
improved wood chip processing and filtering, resulting
in a consistently sized wood chip or fuel product.
While this invention has been described in
detail with reference to preferred embodiments
thereof, it will be understood that variations and
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24
modifications can be made within the spirit and scope
of the invention as described here and above as
defined in the appended claims.
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