Note: Descriptions are shown in the official language in which they were submitted.
CA 02475458 2004-07-20
METHOD AND APPARATUS FOR PRODUCING WOOD SHAVINGS
Field of the lnven~on
S This invention relates to the field of wood shaving and chipping machines.
Bacl~round_of the Invention
Devices for producing wood shavings from pieces of wood have long been
known in art. By way of example, Canadian Patent No. 557,559 which issued to
Steiner et al.
on May 20, 1958, for an invention entitled Production of Shavings from Pieces
of Wood
discloses that it was then known to produce shavings for the manufacture of
wood particle
panels and other similar composite products. Pieces of wood waste are
disintegrated on
rotary-disk type shredding machines into shavings having pre-determined and
properly chosen
properties and dimensions, particularly shavings of a flat and pliably thin
shape. Such rotary-
disk machines include a rotating disk equipped with a number of blades whose
edges extend
along respective radii of the disk. Pieces of a wood of a given length are
placed into a feed
box which is traversed against the rotating blades. The shavings may be sub-
divided by the
use of scoring knives rotating together with and ahead of the cutter blades
mounted on the
rotating-disk. The blade-carrying disk extends in a vertical plane and has a
horizontal shaft.
The feed box is pressed and moved along with the woodpieces on a horizontal
path towards
the blades.
Other prior art such as Canadian Patent Application No. 2,132,876 filed by
Rice
and published September 30, 1993, entitled Apparatus and Method for Making
Wood Curls
discloses a mechanized disk flaker for producing curled food flakes. The disk
flaker includes a
rotatable disk plate having one or more cutting knives mounted to the disk
plate so as to
provide a slight rake angle between the tool face and a plane perpendicular to
the direction of
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CA 02475458 2004-07-20
tool travel. The disk flaker include..s rotatable and removable knife holders
and also includes
the use of scoring knives.
In the prior art, applicant is also aware of Canadian Patent No. 991,833 which
S issued to Schaefer on June 29, 1976, for A Knife for a Wood Shaving Machine.
Schaefer
discloses that the use of scoring knives may be replaced by the use scoring
protrusions formed
on the cutting edges of the knives used to produce wood shavings. In
paa.~ticular, Schaefer
discloses the use of a bent-out cutting portion which results in a scoring
edge, or a U or V-
shaped bead which produces a scoring beak located outside the cutting edge, or
the use of a
punched-out flow extending from the cutting edge transversely where the blade
is bent out to
provide a scoring edge.
In the prior art, applicant is also aware of Canadian Patent No. 630,297 which
issued Fahrni on November 7, 1961, for A Process and Apparatus for Producing
Shaving.
I S Consistent with other prior art, Fahrni discloses the use of a shaving
blade and a scoring blade,
both mounted on a rotating disk where both the shaving blade and the scoring
blade project
from the disk face. Scoring blade includes a plurality of spaced groove-
cutting projections
which extend from the disk face by a distance slightly greater than the
distance of the cutting
edge of the shaving blade from the disk face. Fahrni also discloses that the
shaving blade and
the scoring blade may be included in a single unitary cutting means, or may be
separate
elements mounted in contact with each other or spaced from each other.
Summar~of the Invention
The device according to the present invention uses a heavy flywheel disc
having a radially spaced apart array of pockets in which are mounted knives.
In one
embodiment, six pockets are used with the flywheel rotating at approximately
550 rpm. Short
logs, which have been de-barked, are fed in with their long axis parallel to
the face of the
flywheel. A hydraulic ram forces the logs sideways into the plane containing
the rotating
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knives. The use of the hydraulic ram provides for a variable infeed speed to
obtain the
particular thickness of shavings which provides in the end commercially
shavings desirable for
use, for example, in horse stables: If the ram pressure is too great, the
scoring by means of the
present invention of the wood slices so as to form strands, as better
described below, may be
defeated resulting in non-segmented sheets of shavings. The optimal depth of-.
shaving cut may
be approximately 0.004 of an inch, although it is intended that thicker cuts,
for example 0.015
inches, may be made. The knives have notched cutting edges. The notches limit
the width of
each shaving to create strands which are for example '/ inches wide. The
strands are then
chopped in an automated chopping device such as a forage harvester to produce
shavings, for
example approximately 3/4 inch x 3/4 inch x 0.004 inch in shape.
In one aspect, the invention includes the use on the cutting edge on each
knife
of notches or slits formed into the cutting edge of the knife, where the
notches or slits do not
protnzde from the edge of the knife, but which still operate to score the
shaving to limit the
I S length and width of the shaving. 'this creates ribbon-like shaving strands
of controlled length
and width which may then be chopped to form shavings.
In summary, the present invention may be characterized as a device for
producing shavings from woodpieces which includes an infeed for firanslating
woodpieces in a
direction of flow from an upstream loading position to a downstream shaving
position. The
woodpieces are oriented on the infeed transversely relative to the direction
of flow. A flywheel
is rotatably mounted transversely across the downstream position iri the
infeed. The axis of
rotation of the flywheel may be substantially parallel to the direction of
flow. The axis of
rotation may bisect the infeed at the downstream position. The apertures and
corresponding
knives extend substantially from the axis of rotation radially outwardly. The
flywheel has a
radially spaced apart array of apertures formed therein, radially spaced
around an axis of
rotation of the flywheel.
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CA 02475458 2004-07-20
A radially spaced apart array of elongate slicing knives are mounted to the
flywheel. Each knife has a cutting edge which is elevated and inclined at a
cutting angle
relative to an upstream face of th.e flywheel so as to slice into the
woodpieces when a
woodpiece is pressed against the upstream face by means fox selectively
pressing the
woodpieces. The flywheel is rotated so as to bring sequentially each cutting
edge into slicing
engagement with the woodpiece. 1~aeh cutting edge has a spaced apart array of
slits formed
therein, spaced apart by a distance corresponding to a desired shaving-strand
width dimension.
The slits are formed so as to extend perpendicularly into the each knife from
the cutting edge
without any scoring protrusion protruding from the cutting edge. The strands
are delivered to a
means cooperating with the flywheel for cutting the strands into shavings.
The means cooperating with the flywheel for cutting the strands into shavings
may include a device such as a forage harvester having at least one knife for
chopping the
strands into shavings. The device may include a gravity-feed hopper for
collecting the strands
downstream of the flywheel and for feeding the strands to the chopping knife.
A conveyor
may be provided for conveying the strands from the flywheel into the hopper. A
pair of
counter-rotating rolls may be mounted at the downstream end of the conveyor
far pressing the
strands between the pair of rolls before the strands fall into the hopper. One
roll of the pair of
rolls may have a resilient outer surface.
The strands as they are sliced from the woodpiece by the slicing engagement of
the knives pass through a corresponding pocket and exit from a downstream face
of the
flywheel opposite the upstream face of the flywheel.
The infeed at the downstream position may include a rigid housing for
temporarily storing a queue of parallel woodpieces. The housing has an
upstream infeed
aperture for receiving the woodpieces in the direction of flow, and a
downstream outfeed
aperture adjacent the upstream face of the flywheel. The outfeed aperture i s
generally laterally
centered on the axis of rotation. The means for selectively translating the
woodpieces into the
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CA 02475458 2004-07-20
slicing engagement may include a selectively actuable actuator for urging a
downstream-most
woodpiece in the queue of woodpieces through the outfeed aperture into slicing
engagement
with the knives on the flywheel, The actuator is selectively actuable to
controllably vary the
forward speed of the actuator so as to control the feed speed of the
downstream-most
woodpiece.
Brief Descrip>~on of the Drawing
With reference to the drawings wherein similar characters of reference denote
corresponding parts in each view:
Figure 1 is, in perspective view, the apparatus for producing wood shavings
according to the present invention.
1 S Figure 1 a is an enlarged partially cut away view at the infeed face to
the
shaving disk as illustrated in Figure 1 wherein the view is in front elevation
view relative to
the disk.
Figure 1b is, in partially cut away enlarged view, the infeed and shaving disk
of Figure 1.
Figure 1 c is an enlarged view of a portion of Figure 1 a.
Figure 2 is, in partially cut away front elevation view, the apparatus of
Figure
1.
Figure 3 is, in plan view, the apparatus of Figure 2.
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CA 02475458 2004-07-20
Figure 4 is, in rear elevation view, the apparatus of Figure 1b with the
shaving
disk housing removed.
Figure 4a is, in partially cut away enlarged view, a portion of Figure 4.
Detailed Description of Embodiments of the Invention
A chain conveyor 10 feeds log segments 12, typically logs cut to approximately
three or four foot lengths (collectively herein referred to as logs),
transversely on chainways
10a to an infeed aperture I4 feeding actuated log feeder 16. A log singulator
2 8 singulates and
places logs into aperture 14. Logs from the singulator slide or roll across
sheeted deck 16a so
as to stack in a queue above and upstream of feeder actuator 16b. Actuatar 16b
drives log
bearing member 16c in direction A, thereby driving logs transversely at a
selectively
contxolled rate also in direction A so as to be engaged by log shaver 20.
Log shaver 20 includes a planar flywheel 22 rotatably mounted on drive shaft
24 in a vertical plane orthogonal to direction A. A motor and drive coupling
(not shown)
rotates drive shaft 24 so as to rotate flywheel 22 in direction B. FlywhE;e1
22 includes a
radially spaced apart array of radially extending pockets or slots 22a. Slots
22a extend radially
outwardly of axis of rotation C of flywheel 22. An elongate knife 26 is
mounted in each slot
22a by a knife holder 28 bolted to the flywheel. Each knife 26 is angularly
offset by
approximately thirty degrees from the plane of the upstream face 32b of the
flywheel and
positioned so that a cutting edge 26a protrudes slightly beyond the plane of
the upstream face
22b oppositely disposed to knives 26 across slots 22a. Wear plates 30 are
inset almost entirely
into upstream face 22b. The depth of cut of knives 26 is regulated by the
mounting of knives
26 relative to the upstream surface of the wear plates. Optimally cutting
edges 26a protrude
approximately 0.004 - 0.015 inches beyond the wear surface of wear plates 30.
In practice, the
shaving thickness may vary depending on application and market of final
products.
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CA 02475458 2004-07-20
Cutting edges 26a have notches or slits 32 in spaced apart array along their
length.
Slits may advantageously be 1/16 inches in width by 3/I6 inches deep, and may
be spaced
apart approximately 3/4 inches between each slit. A log 12 engaging cutting
edges 2ba while
the flywheel is turning at approximately 550 rpm are shaved into strands 34 by
the slicing into
S the log of successive cutting edges 26a and slits 32 moving in an arc
relative to the
transversely oriented. log pressed against shaving face 22b and wear plates
30. The translation
of cutting edges 26a and slits 32 in their arc, illustrated by way of example
ass arc D, slice the
knives across the grain of the log shaving an elongate strand 34 having its
length oriented
generally at an angle across the wood grain direction. Strands 34 are
truncated by engaging
slits 32 in slicing engagement so as to slice across the log as the slits move
in their semi- .
circular path relative to the log face so as to keep the strand from getting
unmanageably long.
For example, strands 34 may be in the order of four to 24 inches long. Strands
34 exit from
the slots at the rear face 22c of the flywheel and drop onto, for transport in
direction E, a
conveyor 36. Conveyor 36 delivers strands 34 to a strand chopper 38 which
reduces the length
I S of strands 34 to a chip length of for example 3/a inch resulting in
shavings which may be
approximately '/a x 3/a inches by 0.004 inches thick, depending on the pre-set
depth-of cut of
the knives. The key to the shavings thickness is the very accurate control of
the forward speed
of the ram that presents the log to the disk. That is: Disk rpm of 550 x 6
pockets x .004 inches
per cut = I3.2 inches of wood presented to the disc to be shaved to .004
inches per minute.
The key to controlling the shavings to .004 inches is to control the forward
speed of the ram to
the 13.2 inches, not the pressure. If less than 13 inches is presented the
shavings will be
thinner, if more than 13 inches is presented, the shavings will be thicker.
There are a number
of ways to control the speed. In one embodiment, a controlled high pressure
hydraulic system
is used to control forward speed. Other systems that may be used include
mechanical,
pneumatic, variable frequency drives, gears etc.
Strand chopper 38 includes a pair of transversely aligned closed adjacent
parallel feed rolls 40a and 40b counter-rotating respectively in directions F
and G. The surface
of roll 40a has a softly resilient raised tread. The counter-rotating pair of
rolls 40a and 40b
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CA 02475458 2004-07-20
form a nip 42 therebetween for accepting strands 34 from conveyor 36 into
pinched
engagement between the rolls. Strands 34 are pressed between the rolls,
commencing through
nip 42 and exiting downstream in direction H for gravity feed into a hopper 44
gravity feeding
a strand chopper 46, such as a John Deere ~'M 3970 forage harvester. The
forage harvester is
statically-mounted and turned on end for the gravity infeed from hopper 44, to
chop strands 34
into shorter shavings 34a by means of knives in the harvester cutting the
strands against
corresponding anvils or stationary blades.
As will be apparent to those skilled in the art in the light of the foregoing
disclosure, many alterations and modifications are possible in the practice of
this invention
without departing from the spirit or scope thereof. Accordingly, the scope of
the invention is
to be construed in accordance with the substance defined by the following
claims.
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