Note: Descriptions are shown in the official language in which they were submitted.
2165629
MODIFIED QUICK CHANGE IN~hl~ EDGES ANVIL
SYSTEM FOR WOOD CHIPPERS
The present invention relates to the field of wood
chipping equipment. In particular the present invention
provides an improved anvil system for a chipper.
A chipper, or chipping machine, can be considered as
consisting of three essential pieces or parts within a robust,
rigid framework. A spout serves to guide debarked logs that
are to be formed into wood chips for subsequent pulpmaking
into a knife radially mounted on a rotating disk, which slices
through the wood at the angle of the spout. As the knife
bears against the log, the opposite surface of the log is
pressed against an anvil. The knife acts as a wedge, creating
a shearing force in the grain of the wood. As the shearing
force builds to a critical point, the stress parallel to the
grain of the wood causes chips to be formed, as will be
illustrated herein.
The anvil, together with the spout, is intended to carry
the piece at the correct location and orientation for the chip
forming action of the knives and disk. Wear of the infeed
spout causes misalignment of solid wood at the anvil/knife
contact point, producing inconsistent chip size. The anvil
edge needs to be sharp. If the knives and the anvil act
together in a close scissor-like configuration, the log or
piece can "ride easy" in the spout. Otherwise, especially if
the log or piece is short or small in cross section, it can
be tipped or thrown out of its correct position, resulting in
bad chips. Dull knives aggravate this effect.
It will be understood then, that it is necessary to
maintain the anvil of a chipper in prime condition, if
efficient operation of the chipper is desired. To this end,
the American Pulpwood Association recommends servicing the
anvil of a chipper once a week. Servicing of an anvil will
entail replacement, renewal (i.e., edge grinding, if enough
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stock remains) or turning, if an unworn edge of the anvil is
available. It will be appreciated that replacement of an
anvil, which is a heavy piece of very high grade tooled steel
can be quite expensive, and renewal of anvils edges, while
less expensive in material consumption, requires a machine to
be shut down while the edge is reground by a skilled wright.
Turning an anvil is a temporary solution only, since an anvil
provide four edges at most. Moreover, to be turned, the anvil
must be completely removed from its mounting.
An object of the present invention is to provide an anvil
for use with a wood chipper that is easy to service.
A further object of the present invention is to provide
an anvil for use with a wood chipper that may be serviced, and
the edges thereof turned, without the need to remove the anvil
from its mounting on the chipper.
A further object of the present invention is to provide
an anvil for a wood chipper that is provided with a leading
edge incorporating a removal and replaceable insert that can
be serviced and/or replaced without having to replace the
entire anvil.
In a broad aspect, then, the present invention relates
to an anvil for a wood chipper including: an anvil body
having a top surface, a bottom surface, and longitudinally
extending side surfaces between the top and bottom surfaces,
at least one of said side surfaces being channelled with a V-
shaped groove and having a substantially circular slot
inwardly of the V-shaped groove; an insert shaped and
dimensioned to fit into said V-shaped groove and circular slot
in said side surface of said body; and means within said body
for firmly holding said insert in contact with said V-shaped
groove and circular slot in said side surface; said insert
presenting a leading edge functioning as the anvil's leading
edge.
In a further aspect of the present invention, there is
provided an anvil for a wood chipper including: an anvil body
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having a top surface, a bottom surface, longitudinally
extending side surfaces between the top and bottom surfaces,
at least one of said side surfaces being adapted to accept an
insert; a narrow slot extending into said anvil body inward
of said insert a sufficient distance to permit the sides of
said anvil body to be deflected inwardly upon clamping
pressure being exerted against the top and/or bottom surface
of said anvil body; and a bore in said anvil body
perpendicular to and extending through said narrow slot; an
insert shaped and dimensioned to fit into said adapted side
surface of said body; and means engageable with said bore to
cause the sides of said anvil to be deflected inwardly and
thereby maintain said insert firmly in said groove; said
insert presenting a leading edge functioning as the anvil's
leading edge.
In drawings that illustrate the present invention by way
of example:
Figure 1 is a side view of a generalized form of diagonal
or drop feed chipper showing an anvil according to the prior
art, in unworn condition;
Figure 2 is a side view of a generalized form of
horizontal feed chipper showing an anvil according to the
prior art, in worn condition;
Figure 3 is a perspective view of a first embodiment of
the present invention; and
Figure 4 is an end view of a second embodiment of the
present invention.
Figure 5 is an end view of a third embodiment of the
present invention.
Referring first to Figures 1 and 2, it will be observed
that the anvil A is mounted on the lowermost edge of spout 5
through which a log L is fed. A knife K is mounted on a disk
D that rotates, causing the knife K to shear chips C from the
log L. It will be observed that the forward edges 1 of the
anvil A may be either bevelled, or squared, depending on the
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angle of the spout. In either case, it is essential that the
knife blade pass by the edge of the anvil with an extremely
close tolerance. Moreover, the leading edge of the anvil must
be quite sharp, or, as is illustrated in Figure 2, it will not
correctly support the lower surface of the log against the
pressure of the knife, causing poorly formed chips to be cut.
As the leading edge of the anvil assumes the worn
condition shown in generalized form in Figure 2, the anvil
must be serviced. It can be turned over, and flipped end to
end, until each of its maximum of four edges la, lb, lc and
ld is worn out. Then it is removed for regrinding at each
edge, a labour intensive process. If each edge has been
ground beyond specified tolerances, the anvil must be
replaced.
Referring to Figure 3, the present invention provides an
anvil having a removable edge insert Z with two leading edges
la and lb. When these edges become worn, it is not necessary
to remove the entire anvil for servicing. Rather, the anvil
is merely loosened from its clamp mount C (see Figure 1) and
the insert 2 is removed therefrom by loosening two or more
bolts accessible from the opposite side 3 of the anvil. In
this regard, the anvil of Figure 3 is provided with two or
more, for instance three, lateral bores 4 extending from and
centred just beneath the insert, in a V-shaped (as
illustrated~ or squared channel 5, to the opposite side of the
anvil. Each bore 4 is provided with a shoulder 6 against
which the head of a threaded bolt 7 may bear, the bolt
threading into a tapped bore 8 in the insert 2 that is aligned
with the bore 4 in the anvil. The head of the bolt 7 is
tooled to accept an allen key, or any other suitable turning
tool.
Utilizing the anvil system shown in Figure 3, the edge
insert 2 of the anvil may be reversed to present the lower
edge thereof, or it may be replaced, as required, in a minimum
of time. Since the edge insert will be much less expensive
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than an entire anvil, after it has worn out from repeated
grinding, it can be replaced at much less cost than an entire
anvil.
Another embodiment of the present invention is shown in
Figure 4. In Figure 4, the edge insert 2 is provided with a
dovetail fitting 9 along its inner edge, dimensioned and
conformed to fit, like a key into a lock, into a corresponding
dovetail slot 10 in the body of the anvil. A longitudinal
slot 11 extends into the body of the anvil from the centre of
the dovetail slot 11. Servicing of the anvil of Figure 4 is
very efficient, requiring only that the clamp C holding the
anvil in place be loosened. Loosening the clamp, which fits
into one of the longitudinal side channel 12 on the anvil,
above the longitudinal slot 12 removes pressure exerted on the
insert and holding it in place. The clamp is able to put
pressure on the insert because the sides of the anvil will
tend to deflect inwardly under pressure of the clamp, pressing
the sides of the slot 11 together, when the clamp is
tightened. This causes the dovetail slot 10 to constrict, and
firmly clamp the dovetail fitting 9. Accordingly, it will be
understood that the anvil of Figure 4, to be serviced, need
not be removed from the chipper. The clamp holding the anvil
is loosened, and the insert is slid out of the anvil, and
reversed or replaced. The clamp is then tightened.
A further preferred embodiment of the present invention
is shown in Figure 5. In Figure 5, the edge insert 2 is
provided with a modified retainer fitting 15 along its inner
edge, dimensioned and conformed to fit into a corresponding
insert keyway slot 17 in the body of the anvil. The inside
edge of the fitting of the edge insert 2 is generally circular
in end view, being shaped like a partial cylinder.
As in the embodiment illustrated in Figure 4, a
longitudinal slot 11 extends into the body of the anvil from
the centre of the insert slot 17. Into the side of the anvil
and through the longitudinal slot is threaded a set screw 19
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which is tightened to aid the clamp C in the retention of the
edge insert 2 in the anvil. Loosening the clamp C and the set
screw 19 removes the pressure exerted on the insert 2 and
allows it to be removed from the anvil for replacement or
service. Tightening the set screw 19 and the clamp C exerts
pressure on the insert 2 thereby holding it firmly in place.
It is to be understood that the examples described above
are not meant to limit the scope of the present invention.
It is expected that numerous variants will be obvious to the
person skilled in the field to which the present invention
pertains without any departure from the spirit of the
invention. The appended claims, properly construed, form the
only limitation upon the scope of the invention.
