Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02501622 2003-09-24
RING SLICER WITH EASILY REMOVABLE KNIFE AND KNIFE
ASSEMBLY
Field of the Invention
The present invention relates to a ring sliest having an easily removable
knife and
knife assembly, particularly for use in slicing or flaking logs, refuse
lumber, chips, or
other articles of wood in a lumber mill.
Ring slivers, also tenured ring ffakcrs or stranders, are generally used in
manufacturing facilities for manufacturing particle board, oriented strand
board, and
fiberboard such as MDF. They convert logs, refuse lumber, chips, or other
articles of
wood into flakes, wafers or strands for the manufactured board products. The
ring sliver
includes a cylindrical ring assembly for revolution about an axis of rotation.
The ring
assembly typically includes a large number of elongate knife assemblies,
commonly 49
but which may be as many as 72. The knife assemblies support elongate knives
having
cutting edges extending parallel.to the axis of rotation captured between
annular end
plates. The ring assembly rotates within a chamber into which pieces of wood
to be cut
or chipped are introduced.
The knives are subject to wear from the wood, and in addition rocks, metal
objects
and other hard foreign material carried by or with the wood also wear the
knives, and may
damage or break the knives as well as the knife assemblies. Accordingly, it is
routinely
required to remove the knives to repair or replace them, or to turn them to
expose fresh
~
~ _ CA 02501622 2003-09-24
cutting edges. Moreover, it is episodically required to remove and replace
some or all of
the knives, the knife assemblies, or both, as a result of "crashes" of the
ring slicer
apparatus. The machine downtime and the labor required to effect maintenance
and
repair are costly and desirably kept to a bare minimum.
As described in U.S-. Patent No. 5,313,696, the knives may be mounted to a
portable knife assembly that slides radially into slots in the end plates of
the ring
assembly. Once in place, bolts are inserted through holes in the end plates
into threaded
holes in the knife assembly to hold the knife assembly in place. In turn, the
knife is
similarly mounted to the knife assembly with bolts extending through holes in
the knife
into threaded holes in the knife assembly.
One problem with this approach is that the bolt holes require a tolerance that
permits the knife or knife assemblies to move or creep within the ring
assembly and
thereby to become misaligned or to loosen as a result of the large cutting
forces
encountered during operation. Moreover, removing the knife from the ring
slicer requires
both removing the knife assembly from the ring assembly and removing the knife
from
the knife assembly.
To hold the knife assembly more securely to the ring assembly, the knife
assembly
may be provided with protruding keys that extend axially into corresponding
keyholes in
the end plates. The keys and keyholes can be provided with a minimal tolerance
of fit
that maintains the positional integrity of the knife assembly. However, a
major
disadvantage of this approach is that the knife assemblies may no longer be
simply slid
radially away from the ring assembly for maintenance or repair. Rather, the
end plates
2
CA 02501622 2003-09-24
must be axially spaced apart a sufficient amount to permit the projecting keys
to clear the
end plates, requiring that the entirety of at least one end plate be decoupled
from all of the
knife assemblies.
It is often necessary to remove a knife from the knife assembly under
conditions
where it is not otherwise necessary to remove the knife assembly from the ring
assembly.
U.S. Patent No. 5,937,923 addresses this pmblem by providing a clamp for the
knife that
is biased outwardly by springs disposed in spring holes in the knife assembly,
for
unclamping the knife without requiring removal of the clamping bolts.
A disadvantage of the mechanism is that it requires the clamp to move
radially,
and while a necessary indexing of the clamp is provided to seat the clamp into
proper
position when it is tightened, this is provided in the form of sliding
surfaces that wear
over time so that the position of the clamp and, therefore, the knife are
permitted to
wander. Another disadvantage of the mechanism is that it is difficult to
remove cut wood
fibers introduced into the spring holes when the clamp is loosened. , It is
yet another
disadvantage of the mechanism that the spring forces produced by the multiple
compression springs must be well matched to prevent binding of the clamp.
Accordingly, there is a need for a ring slicer having an easily removable
knife and
knife assembly that provides for positive maintenance of the position of the
knife in the
ring slicer as well as easy removal of the knife and knife assembly therefrom.
Summa~r of the Invention
The invention disclosed herein is a ring slicer having an easily removable
knife
3
CA 02501622 2003-09-24
and knife assembly. Within the scope of the invention, there is an apparatus
for cutting
an article of wood, comprising a ring assembly comprising two end plates for
rotation
about an axis of rotation and a plurality of knife assemblies. Each assembly
comprises an
elongate knife having a cutting edge extending along an elongate axis, a base,
and a
clamp for clamping the knife to the base. The assemblies are provided for
installation
between the end plates by one or more bolts extending through one or both of
the end
plates into the respective bases.
According to one aspect of the invention, the bases include one or more first
apertures and at least one of the end plates includes a corresponding set of
one or more
second apertures therethrough for receiving respective dowel pins. The first
apertures are
adapted to snugly slidingly receive the respective dowel pins within a range
defined by a
first position in which the respective dowel pins extend into at least one of
the end plates
to a second position in which the respective dowel pins are substantially
wholly received
within the respective first apertures.
According to another aspect of the invention, for each knife assembly, the
clamp
includes an upper clamping member that is mounted to the base so that a
portion of the
upper clamping member is cantilevered from the base. Each knife assembly
includes
provision for at least one bolt extending through the respective portion of
the upper
clamping portion into the respective base wherein tightening the bolt
elastically deflects
the portion of the upper clamping member against one side of said knife.
Therefore, it is an object of the present invention to provide a novel and
improved
ring slicer having an easily removable knife.
4
CA 02501622 2003-09-24
It is another object of the present invention to provide a novel and improved
ring
slicer having an easily removable knife assembly.
These and other objects, features and advantages of the present invention will
be
more readily understood upon consideration of the following detailed
description of the
invention, taken in conjunction with the following drawings.
Brief Descriution of the Drawines
Figure 1 is a front, partially cut-away view of a prior art ring slicer.
Figure 2 is a plan, section view of the ring slicer of Figure 1, taken along a
line 2-
2 thereof.
Figure 3 is a partially cut-away, elevational view of a prior art knife
assembly for
the ring slicer of Figures l and 2.
Figure 4 is a pictorial view of a ring assembly according to the present
invention.
Figure S is a pictorial view of a knife assembly according to the present
invention.
Figure 6 is an end view of the knife assembly of Figure 5.
1 S Figure 7 is the end view of Figure 6 showing selected phantom lines.
Figure 8A is a top pictorial view of a knife for use in the knife assembly of
Figure
5.
Figure 8B is a bottom pictorial view of the knife of Figure 8A.
Figure 9 is a pictorial view of the knife assembly of Figure 5, showing
partial
removal of the knife therefrom.
Figure 10 is a pictorial view of the knife assembly of Figure 5, showing
complete
5
CA 02501622 2003-09-24
removal of the knife therefrom.
Figure 11 is a pictorial view of a portion of the ring assembly of Figure 4,
showing removal of the knife assembly therefrom.
Figure 12 is a side elevation of the knife assembly of Figure 5.
Detailed Description of a Preferred Embodiment
Referring to Figures 1 and 2, a prior art ring slicer 12 is shown, such as
disclosed
in U.S. Patent No. 5,937,923. The ring slicer has a ring assembly 10 that is
caused to
rotate about an axis of rotation "L." The ring assembly 10 has a number of
cutting knife
assemblies 16 for cutting and chipping pieces of wood 9 that flow in the
direction
indicated as "F" in Figure 2) into the apparatus through an opening 11. The
ring slicer
also includes a "rotor" 14 that counter-rotates with respect to the ring
assembly 10 about
the axis "L," to sling the pieces of wood 9 against the knives of the ring
assembly. A
drive mechanism 13 includes respective motors (not shown) for driving the
rotor through
an arbor shaft 15 and for driving the ring assembly 10 through a coaxially
disposed drive-
shaft 16. The knife assemblies 16 are captured between two annular rings 18
(not shown
in Figure 1 ).
The ring slicer 12 is particularly adapted to manufacture particleboard;
however,
with suitable adaptation the ring slicer may be used to manufacture oriented
strand board
as well. While either of these are preferred contexts for the present
invention, the
principles of the invention may be applied to any cutting apparatus,
particularly any
cutting apparatus for processing articles of wood.
6
CA 02501622 2003-09-24
Turning to Figure 3, a prior art knife assembly 16 is shown, captured between
the
two annular rings 18 of the ring assembly shown in Figure 2. The knife
assembly lb has
an elongate body 21 to which is directly bolted, by use of bolts 15a, an
elongate knife 23
having a cutting edge 24. The body includes threaded holes at ends 26a, 26b
thereof for
bolting the body between the rings 18 by use of bolts 15b. The body also
includes
respective projecting keys 27 at the ends for extending into mating keyholes
in the rings,
the reversal of the keys and keyholes being functionally equivalent. While the
bolts 15
hold the ring assembly together, the keys and keyholes are used to locate the
knife
assemblies with respect to the rings and thereby prevent creep of the knife
assembly
resulting in misalignment during use. A similar strategy could be used to key
the knife 23
to the body 21.
To remove the knife 23 from the knife assembly 16 when it is installed between
the rings 18 requires complete removal of all of the bolts 1 Sa of the knife
assembly. To
remove the knife assembly 16 from the ring assembly 10 requires removing the
bolts 1 Sb,
and moving the rings 18 axially far enough apart so that the projecting keys
27 clear the
inside faces 29 of the rings I8 so that the knife assembly can be slid
outwardly from the
ring assembly. This latter step requires at least loosening and typically
completely
removing the bolts 15b for every knife assembly in the ring assembly. Where
there are
typically 49 or as many as 72 knife assemblies in the ring assembly, this is
an
objectionably laborious and time consuming process.
Turning to Figure 4, a ring assembly 30 according to the present invention is
shown that substantially reduces the time and labor required to change either
the knives
7
CA 02501622 2003-09-24
of the knife assemblies, or the knife assemblies themselves.
The ring assembly 30 includes two end plates 32a, 32b which are preferably but
not necessarily annular in shape. Captured between. the two end plates 32 are
a plurality
of individual knife assemblies 34. There are typically 49 knife assemblies,
but the
number of knife assemblies may vary considerably. For example, ring dicers are
available with as few as 32 knife assemblies and as many as 72 knife
assemblies.
Figures 5 and 6 show a knife assembly 34 according to the present invention.
The
knife assembly includes a knife 36,. a clamp 38 and a base 40. The clamp 38
includes an
upper clamping member 38a and a wearshoe 38b that functions as a lower
clamping
member. Both the wearshoe and the upper clamping member are bolted to the base
such
as shown in Figure 7. A preferred knife 36 for use in the knife assembly 34 is
also shown
in Figures 8A and 8B. Preferably, the knife 36 has two opposed cutting edges
24a and
24b.
The knife 36 is clamped to the base 40 by the clamp 38. Particularly, the
knife is
held between the upper clamping member 38a and the wearshoe 38b. The upper
clamping member is bolted to the base 40 by use of a bolt 45a, and the
wearshoe is bolted
to the base by use of a bolt 45b (Figure 7). However, the knife is not yet
held by the
clamp 38 until a clamp bolt 45c is tightened.
Particularly, the base has a raised support portion 42 (Figure 6) on which one
end
of the upper clamping member 38a is supported. The upper clamping member is
cantilevered out from this support and without any deflection is spaced apart
from the
wearshoe by a distance "d" that is greater than the thickness "t" of the
knife. Tightening
8
CA 02501622 2003-09-24
the clamp bolt 45c therefore deflects the cantilevered upper clamping member
38
elastically so as to bring it into contact with the lrnife, and further
tightening of the clamp
bolt tightens the clamp. Accordingly, loosening the clamp bolt 45c releases
the clamping
force on the knife and the upper clamping member relaxes its elastic
deflection, freeing
the knife for easy removal from the knife assembly 34. The cantilever
arrangement of the
upper clamping member provides the outstanding advantage, as compared to prior
art
spring-clamp mechanisms, of being unaffected by packing and manufacturing
tolerance.
This is because the cantilever can be deflected despite any cut wood fibers
caught
between the upper clamping member and the base, and because the entire upper
clamping
member functions as a single spring, the characteristics of which do not have
to cooperate
with those of any other springs.
Preferably, there is about a 0.004" to 0.008" clearance between the upper
clamping member 38 and the knife when the clamp bolt 45c is fully loosened
and,
therefore, the upper clamping member 38 is in its relaxed, undeflected, state.
Multiple
instances of the clamp bolt 45c are preferably provided such as shown in
Figure 5 to
ensure that the required clamping force can be exerted and maintained.
The wearshoe 38b and the base 40 advantageously include cooperatively locking
portions 41 and 43, respectively, that function to index, strengthen and
secure the
attachment of the wearshoe to the base. Particularly, the locking portions 41
and 43
prevent movement of the wearshoe with respect to the base in the direction
indicated as
"A," and thereby ensure that the distance "d" is and remains fixed.
Referring to Figures 9 and 10, the knife 36, once unclamped by loosening the
9
CA 02501622 2003-09-24
clamp bolts) 45c, can be installed into or removed from the knife assembly 34
in the
direction of the arrows. Taming back to Figure 4, these operations can be
accomplished
while the knife assembly is still in place in the ring assembly 30 simply by
sliding the
knife axially out of the ring assembly 34 through a corresponding slot 44 (see
also Figure
11) in the end plates 32. It is an outstanding advantage of the ring assembly
30 that
neither the clamp bolts nor the knife assembly needs to be removed in order to
remove
the knife.
Preferably, slots 44 corresponding to a particular knife assembly 34 are
provided
on both end plates 32a and 32b (Figure 11), so that the knife may be
conveniently
removed through one a slot in one of the end plates, e.g., 32a, by pushing
another knife
into place through the corresponding slot in the other end plate. For example,
a knife 36
may be pushed into the knife assembly 34 while the knife assembly is installed
in the ring
assembly 10 of Figure 11 through slot 44b in the end plate 32b. This will push
the knife
already in the knife assembly 34 out the slot 44a of the end plate 32a, though
the knife
1 S could also be removed through a single slot, and the knife need not be
replaced with
another knife. Rather, alternatively, where the knife 36 has double cutting
edges 24a and
24b such as shown in Figures 8A and 8B and the cutting edge 24a is worn, the
knife may
be advantageously turned end-for end and reinstalled through the slot to
expose or present
a fresh cutting edge 24b of the same knife 36. This function is facilitated by
providing
that the knife 36 is symmetric with respect to being turned end-for-end, i.e.,
about the
bisecting plane "P" in Figure 8A.
Turning to another aspect of the invention, Figures 6, 9, 10 and 11 show dowel
CA 02501622 2003-09-24
pins 48 extending from the base 40. Referring to Figure 12, the dowel pins 48
are
slidingly disposed in dowel holes 50 in the base and extend into or through
dowel holes
S 1 in the end plates 32. Bolts 45d (see also Figure 7) extend through the end
plates 32
into holes 53 (Figure 6) in the base to hold the ring assembly together. The
dowel pins
are tight-fitting in the respective dowel holes, but are preferably slidingly
movable
therein by pressing or punching the pins with hand tools. The dowel holes
extend deeply
enough into the base that the dowel pins may be pressed or punched into the
holes and
wholly contained thereby, so that outer ends 49 of the dowel pins may be
substantially
flush with or beneath outer end surfaces 55 of the base. Accordingly, if the
length of the
dowel pins is "Ll," the depth of the dowel holes "L2," is preferably at least
as great as
"L ,~~
i
In the ring assembly 30, the dowel pins are ordinarily positioned to extend
from
the dowel holes, into or through the plates 32, to locate the base 40 to the
plates 32.
However, to remove the knife assembly 34 from the ring assembly, the dowel
pins on at
least one end of the knife assembly may be pressed or punched into the dowel
holes so
that the knife assembly is free to slide radially out of the ring assembly. It
is an
outstanding advantage of the ring assembly 30 that the knife assembly can be
removed
from the ring assembly simply by removing the bolts 45d and pressing or
punching the
dowel pins on at least one end of the knife assembly into their respective
dowel holes.
It is to be recognized that, while a particular ring slicer having an easily
removable knife and knife assembly has been shown and described as preferred,
other
configurations and methods could be utilized, in addition to those already
mentioned,
without departing from the principles of the invention.
11
CA 02501622 2003-09-24
The terms and expressions which have been employed in the foregoing
specification are used therein as terms of description and not of limitation,
and there is no
intention in the use of such terms and expressions to exclude equivalents of
the features
shown and described or portions thereof, it being recognized that the scope of
the
invention is defined and limited only by the claims which follow.
12
