An improved wood pulverizer is provided with a rotating disc studded
with a plurality of curved tapered hammers. One or more anvils is
secured to the pulverizer with the anvil having teeth and slots
located adjacent the surface of the disc. The hammers of the rotating
disc pass through the slots of the anvils as the disc rotates to
tear and shard wood into bits and pieces for subsequent use or processing.
The anvils of the present invention are formed with two or more
useable surfaces so that the anvils can be removed, rotated, and
replaced to present fresh cutting surfaces to the disc. Further,
the anvils are formed by a series of bolted together anvil segments
to allow replacement of only single segments in the event of damage.
What is claimed is:
1. A hammer adapted to be secured to the surface of the disc in
a rotating disc-type wood pulverizing apparatus at a predetermined
radius on said disc, said hammer having a body with said body being
curved to follow the radius of curvature of said disc at said predetermined
2. A hammer as claimed in claim 1 and wherein said body has a front
surface and a back surface and wherein said body is inwardly tapered
from its front surface to its back surface.
3. A hammer as claimed in claim 2 and wherein said body has a substantially
rectangular front surface.
4. A hammer as claimed in claim 2 and wherein said body has a substantially
triangular front surface.
5. A hammer as claimed in claim 2 and wherein said body has a substantially
trapezoidal front surface.
6. A hammer as claimed in claim 1 and wherein said body has a front
surface, said hammer further comprising a cutting element removably
attached to said front surface of said body for impacting and pulverizing
wood in the wood pulverizing apparatus.
7. A hammer as claimed in claim 6 and wherein said cutting element
is formed with peripheral edges that project beyond the sides of
8. A hammer as claimed in claim 6 and wherein said body has a back
surface and wherein said body is inwardly tapered from its front
surface toward its back surface.
9. A hammer as claimed in claim 6 and wherein said cutting element
is secured to said front surface of said body with a bolt that extends
through said cutting element and is threaded into said body.
10. A hammer as claimed in claim 6 and wherein said body is formed
with a generally rectangular cross-section.
11. A hammer as claimed in claim 6 and wherein said body is formed
with a generally triangular cross-section.
12. A hammer as claimed in claim 6 and wherein said body is formed
with a generally trapezoidal cross-section.
13. A hammer adapted to be attached to a moving surface in a wood
pulverizing apparatus for impacting and pulverizing wood presented
to the surface, said hammer being curved to follow the arc of its
movement as it is carried by the moving surface.
14. The hammer of claim 13 and wherein said moving surface is a
disc and wherein said hammer is curved to correspond to the radius
of the disc at the location of said hammer.
15. A rotating disc assembly for use in a wood pulverizing apparatus
to pulverize wood presented to the disc into shards, said assembly
comprising a rotatable disc, having a surface, a plurality of hammers
secured to said surface of said disc at selected radii thereon,
at least some of said hammers being curved to correspond to the
arc of the disc at the radius where they are attached, and an anvil
mounted adjacent to said surface of said disc, said anvil being
formed with an array of slots through which some of said hammers
pass as said disc is rotated, at least some of said slots being
curved to accommodate curved hammers as said hammers pass through
said slots in said anvil.
16. The assembly of claim 15 and wherein said curved hammers have
a front end and a back end and wherein said hammers are inwardly
tapered from their front ends toward their back ends.
This invention relates generally to wood and log processing machinery
and more particularly to wood hogs and chippers for shredding wood
into chips and shards for subsequent use or disposal.
BACKGROUND OF THE INVENTION
Cylindrical drum-type wood chippers for reducing logs, branches,
roots, and the like to wood chips are well known. In general, drum-type
chippers comprise a rotating cylindrical drum having an exterior
surface studded either with hammers or sharpened chipper knife blades
depending upon the desired consistency of the finished chips. Sharpened
chipper blades, for example, tend to produce neatly cut wood chips
while hammers tend to pulverize, shred, and tear the wood into randomly
shaped shards. In use, logs and branches are fed to the rotating
drum where the moving hammers or knives reduce them into small pieces
that can be transported easily or be used for pulp, mulch, or the
Examples of drum-type wood chippers are found in U.S. Pat. Nos.
4802631 of Arasmith, 4785860 of Arasmith, 1418735 of Plaisted,
and 3801027 of Kubitz. In most of these examples, logs to be processed
are fed to the surface of the rotating drum by a feeder mechanism
such as a conveyor or feed roll. The blades of the drum are configured
to impact, cut, and chip the log into pieces of roughly the same
size, whereupon the pieces are discharged from the machine through
a discharge chute.
Disc chippers have been developed as an alternative to drum-type
chippers. These disc chippers employ a rotating knife or hammer
bearing disc rather than a cylindrical drum to reduce wood to chips.
A good example of a disc chipper is presented in U.S. Pat. No. 4827989
of Strong. Other examples are illustrated in U.S. Pat. Nos. 1195774
of Brown, 3732907 of Nystrom, and 4736781 of Morey, et al. In
addition, a unique and improved disc-type chipper is disclosed and
claimed in my own U.S. Pat. No. 5469901 of which the present
Application is a continuation-in-part. The disclosure of my said
patent is hereby incorporated by reference in order to provide a
good background for the particular improvements and disclosures
of the present application.
In general, disc-type chippers comprise a housing that carries
a rapidly spinning metal disc having knives or hammers mounted on
the surface of the disc. Wood to be processed is fed to the disc
surface, usually at an angle, where the knives or hammers reduce
the wood to chips and shards. The chips and shards, when cut, can
either pass through gullets in the disc, can be discharged through
a sizing grate, or can be transferred to the back side of the disc
for additional processing.
Many disc-type chippers and drum-type chippers have moving surfaces
that are studded with hammers or knives that protrude outwardly
from the surface. In the case of disc-type chippers having hammers,
these hammers usually comprise a rectangular block of metal that
is secured with screws or weld joints to the surface of the disc
so that the hammers protrude therefrom. Usually, the hammers are
arranged along preselected radii of the disc so that they can pass
through slots formed in metal anvils that are secured adjacent to
the surface of the disc. The interactions of the hammers and anvils
generate a scissor action that shreds and cuts the wood into small
pieces and shards that can be subsequently processed or discharged
from the machine. Typically, as disclosed in my U.S. Pat. No. 5469901
the anvil of a disc chipping machine is located at the base of an
infeed spout so that wood, usually in the form of tree limbs, is
presented directly to the hammer/anvil interface as it is fed into
the machine. In this way, the wood that is introduced through the
infeed spout is immediately shredded and torn by the scissor action
of the interacting of the hammers and anvil.
In the past, hammers such as those just discussed have generally
been rectangular and have been formed of a single piece of hardened
steel having square transverse grooves cut in one edge thereof.
While this has proved somewhat acceptable for shredding and cutting
wood, it nevertheless is plagued with various problems and shortcomings.
For example in disc-type chippers, relatively large clearance must
be provided in the anvil so that the rectangular hammers, which
are actually traveling in circles, can pass through the slots in
the anvil without engaging the sides thereof. This problem is particularly
acute at positions nearest the hub of the disc, where the arc through
which the hammers travel is the tightest. An additional problem
with prior art wood chippers and hogs has been that the anvils generally
are made of a single solid piece of hardened steel that is securely
fastened to the frame of the machine adjacent to the rotating disc
thereof. Such monolithic anvil designs, which have been relatively
simple to manufacture, are nevertheless plagued with their own problems.
For example, occasionally a stone or piece of metal will inadvertently
be fed into the machine. Such foreign items can cause teeth of the
anvil to be broken off when they encounter the interface between
a moving hammer and an anvil slot. Broken anvil teeth reduce the
efficiency of the entire machine and require that the anvil be replaced.
In addition, anvils in wood chippers and wood hogs tend to wear
at different rates along their length as a function of the distance
along the anvil from the hub of the chipper. Accordingly, in some
instances, the entire anvil must be replaced when only a portion
of it is worn beyond use. Obviously, this is expensive and wasteful.
It will thus be seen that there exists a continuing need for a
wood pulverizing machine such as a chipper or hog having improved
hammer and anvil configurations designed to enhance the efficiency
and function of the machine. Such hammer and anvil configurations
should assure minimum clearance between the walls of the anvil slots
and the hammers passing through to maximize the scissor-like action
that shreds wood into chips and shards within the machine. In addition,
an improved anvil design should permit placement of the anvil adjacent
a hammer-bearing disc in any one of a variety of orientations relative
to the radius of the disc to improve efficiency. Further, the anvil
should be assembled in replaceable segments so that broken teeth
of an anvil can be replaced without replacing the entire anvil.
It is to the provision of a wood pulverizing machine having such
improved hammer and anvil configurations that the present invention
is primarily directed.
SUMMARY OF THE INVENTION
Briefly described, the present invention comprises a wood pulverizing
machine such as a disc hog having greatly improved hammers and anvil
configurations for providing more efficient and effective pulverization
of wood such as limbs and the like. The improved hammer and anvil
designs of the present invention are primarily intended for use
with disc hogs; however, the concepts disclosed and claimed herein
are also applicable to drum chippers having cylindrical drums with
hammer studded surfaces.
In one embodiment, the present invention comprises an anvil/hammer
combination wherein the hammers are curved to correspond roughly
to the radius of curvature at the location of the hammer on the
disc. Correspondingly, the slots formed in the anvils, through which
the hammers pass, are curved to correspond to the curvature of the
hammers. In this way, the space between the moving hammers and the
slots in the anvils can be minimized to increase the pulverizing
efficiency of the machine. The improved anvils of the present invention
have slots formed to accommodate anvils positioned either along
a radius or skewed relative to a radius of the disc, even to the
point of being perpendicular to be radius.
Preferably, the anvils of this invention have one or more useable
edges or surfaces so that the anvil can be removed and turned over
or repositioned to present fresh slots and cutting surfaces to the
hammers and the disc of the machine. In this way, the anvil, when
worn, can simply be turned over to present a fresh cutting edge,
thus prolonging the life of the anvil.
In one preferred embodiment, the anvil is formed from a series
of anvil segments bolted together to form the elongated anvil. With
this embodiment, if one tooth of the anvil should become broken
or unacceptably worn, only the single anvil element requires replacing,
thus increasing the efficiency and economy of the machine as a whole.
Each anvil segment is formed with a tooth and a shoulder that aligns
with the shoulder of an adjacent anvil segment to define a slot
through which a moving hammer can pass. The anvil segments have
alignment means so that they are automatically aligning when secured
together to form the entire anvil.
The invention further comprises an improved disc hog-type wood
chipper having a first anvil aligned along a first predetermined
orientation relative to the disc radius and a second anvil oriented
along a second predetermined orientation. In the preferred embodiment,
the anvils are aligned along a radius and perpendicular to a radius
on the bottom and side of the infeed spout. In this way, the shredding,
tearing, and pulverizing process is greatly enhanced over prior
Thus, it is an object of the invention to provide an improved hammer
and anvil design useable in conjunction with a wood pulverizing
machine to increase the efficiency of the machine.
It is another object of the invention to provide an improved anvil
design for use with a wood pulverizing machine wherein the anvil
has at least two useable surfaces for increased anvil life.
An additional object of the invention is to provide an improved
anvil for use with a wood pulverizing machine wherein the anvil
is formed of a series of anvil segments interconnected together
so that individual segments can be removed and replaced if desired.
Another object of the invention is to provide an improved design
for hammers useable with a disc hog-type wood pulverizing machine
wherein the hammers are curved to correspond to a radius of the
disc and wherein the slots formed in the anvil are also curved to
accommodate the curved hammers.
A further object of the invention is to provide an improved disc
hog-type wood pulverizing machine having at least two anvils oriented
along selected perimeters of the machine's infeed port to provide
increased wood pulverizing efficiency.
These and other objects, features, and advantages of the invention
will become more apparent upon review of the detailed description
set forth below taken in conjunction with the accompanying drawings
which are briefly described as follows.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a perspective view of an improved anvil that embodies
principles of the present invention in a preferred form.
FIG. 1B illustrates an alternate embodiment of the anvil of FIG.
1A illustrating an anvil with two useable edges.
FIG. 1C is a perspective view of an anvil embodying principles
of the present invention and intended for use with a drum-type wood
FIG. 1D illustrates formation of an anvil of the present invention
from anvil segments connected together with bolts.
FIG. 2 is an edge elevational view illustrating the curved teeth
and slots formed in an anvil designed to be oriented along a radius
of a disc hog.
FIG. 3 is a side elevational view of an anvil adapted to be positioned
in a skewed orientation relative to a radius of a wood chipper disc.
FIGS. 4A through 6B illustrate various improved hammer designs
for use with disc hog-type wood pulverizing machines.
FIGS. 7A through 9B illustrate alternate embodiments of hammers
designed for use with disc hog-type wood pulverizing machines.
FIG. 10 is an edge elevational view of the teeth and grooves of
an anvil adapted to be oriented perpendicular to the radius of a
disc hog disc.
FIG. 11 illustrates an improved disc hog-type wood pulverizing
machine having curved hammers and two anvils oriented along selected
perimeters of the infeed spout of the machine.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now in more detail to the drawings, in which like numerals
refer to like parts throughout the several views, FIGS. 1A through
1D illustrate anvils for use with disc hog-type wood chippers with
the anvils embodying principles of the present invention in preferred
forms. FIG. 1A illustrates a simple one-sided anvil formed with
curved teeth and slots to accommodate the passage of hammers on
an adjacent rotating disc. The anvil 11 has an elongated generally
rectangular shape with a series of protruding teeth 12 formed along
one edge thereof. Separating the teeth 12 are a set of slots 13.
As described in more detail below, the anvil 11 is adapted to be
mounted to a disc hog-type wood pulverizing machine with its teeth
12 extending toward the surface of the rotating disc of the machine
and with its slots 13 positioned so that hammers protruding from
the surface of the disc pass through the slots. The action of the
hammers and slots functions to tear and shred wood into chips and
shards for subsequent processing or other use.
The anvil 11 in FIG. 1A is also seen to be formed by a series of
anvil segments 14. The segments 14 are aligned edge to edge and
are secured firmly together by a pair of bolts 16 to form a substantially
monolithic anvil structure. Formation of the anvil 11 from a series
of anvil segments permits easy and economic replacement of single
segments in the event that the tooth associated with a segment becomes
broken, damaged, or worn beyond use. This represents a benefit over
prior art anvils made of a single piece of metal wherein the entire
anvil must be replaced if any portion thereof is damaged.
FIG. 1B illustrates an anvil with teeth and slots formed along
two opposed edges thereof. Specifically, a series of teeth 12 are
formed along one edge defining slots 13 therebetween and a corresponding
series of teeth 17 defining slots 18 are formed along the opposed
edge of the anvil 15. As with the embodiment of FIG. 1A, the anvil
of FIG. 1B is also formed by a series of side by side anvil segments
19 that are bolted together with a pair of bolts 21. With the embodiment
of FIG. 1B, should the teeth and slots on one edge become worn or
broken, the entire anvil 15 can be removed, rotated 180 degrees,
and reinstalled to present fresh teeth and grooves to the rotating
disc of a disc hog machine. Alternatively, if one of the teeth on
one edge of the anvil should become broken, the anvil can be removed,
disassembled, and the affected segment rotated 180 degrees. The
anvil can then be reinstalled so that a fresh tooth is presented
in place of the broken tooth. Should both teeth of a particular
segment become broken or worn beyond use, it is only necessary to
replace one segment rather than the entire anvil to bring the machine
back to operating standards.
FIG. 1C illustrates an anvil for use with a rotating drum-type
wood pulverizing machine. With this embodiment, the anvil 22 is
formed from a series of bolted together anvil segments 23. The segments
are formed so that, when they are bolted together, they define four
sets of teeth and slots that can be presented to the surface of
a rotating drum to accommodate the passing hammers or knives on
the drum. With this embodiment, should a set of teeth become worn
or broken, the anvil can be rotated and reinstalled with a fresh
set of teeth presented to the drum. This can be done up to three
times. In addition, individual segments can be removed and replaced
or rotated if necessary to present fresh teeth and slots to the
rotating drum surface.
FIG. 1D illustrates one preferred method of securing anvil segments
together to define an 10 anvil. The embodiment shown in FIG. 1D
corresponds to the anvil shown in FIG. 1B; however, it will be understood
that the configuration illustrated in FIG. 1D is applicable to any
of the other anvil designs disclosed in this application. Each of
the anvil segments 19 is formed with a tooth 17 on one end and an
opposing tooth 12 on the other end. The teeth 12 and 17 are curved
to accommodate a moving hammer of a rotating disc and the curved
protruding sides of the teeth are visible at 24. The teeth 12 and
17 define shoulders 26. When two segments 19 are secured together
as illustrated in FIG. 1B, the shoulders 26 of adjacent segments
along with the walls of adjacent teeth from the slots 13 and 18
between the teeth as shown in FIG. 1B.
A pair of alignment pins 27 are formed along one edge of segment
19. The alignment pins 27 are sized and positioned to be received
in a pair of corresponding alignment dimples 28 formed in the facing
edge of the adjacent anvil segment 19. In this way, when two segments
19 are brought together, they are automatically aligned with each
other by means of the alignment pins 27 and dimples 28.
Pairs of through bores 32 are formed in the segments and are positioned
to align with each other and to receive a pair of bolts 29 and nuts
31 for securing the two segments together side by side to define
a composite anvil. Naturally, in use, several of the segments 19
would be bolted together to form a long anvil having a series of
teeth and slots. Only two anvil segments 19 are illustrated in FIG.
1D for clarity and simplicity of discussion.
FIG. 2 is a side elevational view of an anvil that embodies principles
of this invention in a preferred form. The anvil 33 is seen to be
formed from a series of bolted together anvil segments 34. Each
segment 34 has a protruding tooth 36 and a pair of shoulders 37
that, in conjunction with the shoulders of adjacent segments, define
slots 38 between adjacent teeth 36. The teeth 36 and therefore the
slots 38 are curved in order to accommodate the circular path take
by a hammer on a rotating disc of a disc hog-type wood pulverizer.
In the embodiment of FIG. 2 the anvil 33 is adapted to be oriented
substantially along a radius of the disc. Thus, the curvature of
each tooth corresponds to the radius of curvature of the disc at
the position where the tooth is located. With the curved teeth and
curved slot configuration shown in FIG. 2 a much closer clearance
can be provided between a moving hammer and the slot through which
it passes to enhance the efficiency of the wood pulverization process.
FIG. 3 illustrates an anvil that embodies principles of the present
invention and that is designed to be oriented at a skewed angle
relative to a radius of a rotating disc with which the anvil is
used. As with previous embodiments, the anvil 39 is formed by a
series of bolted together anvil segments 41. Each segment is formed
with a tooth 42 43 and 44 respectively. Since the anvil 39 of
FIG. 3 is adapted to be positioned in skewed relationship with respect
to a radius of its associated rotating disc, the teeth 42 43 and
44 are progressively skewed to correspond to the radius of curvature
at the position on the disc where the tooth is located. With this
configuration, the slots 46 defined between the teeth 43 and through
which the hammers on the rotating disc pass, are also progressively
skewed to accommodate the path of the moving hammers on the disc.
FIGS. 4A and 4B illustrate from the top and side respectively,
one configuration of a hammer for use with a corresponding anvil
of the present invention. The hammer 47 is seen to have a front
surface 48 a rear surface 49 an inner side surface 51 an outer
side surface 52 and a top surface 53. The hammer 47 is adapted
to be secured at its base 54 to the disc of a disc hog-type wood
pulverizing machine with appropriate attachment means such as a
bolt or by welding. The hammer 47 of FIGS. 4A and 4B is seen to
be inwardly tapered from side to side and along its top from its
front surface 48 to its back surface 49. In addition, the hammer
47 is curved to correspond to the radius of curvature at the position
on the disc where the hammer is to be located. The size of the front
surface 48 of the hammer 47 is selected to be just smaller than
the size of a slot 48 (FIG. 2) in an associated anvil so that the
clearance between the moving hammer and the slot is small. The curved
and tapered shape of the hammer 47 accommodates the movement of
the hammer through the slot and further enhances the scissor action
as the front surface 48 of the hammer passes through the slot 38.
FIGS. 5A and 5B illustrate an alternate hammer having a triangular
configuration. As with the hammer of FIGS. 4A and 4B, the triangular
hammer 56 has a curved tapered configuration with a triangular shaped
front surface 57. The hammer of FIGS. 5A and 5B is for use in conjunction
with an anvil having triangular shaped slots formed between corresponding
FIGS. 6A and 6B illustrate still another embodiment of a hammer
58 wherein the front surface 59 of the hammer has a trapezoidal
shape, being taller along the outside edge of the hammer than along
the inside edge of the hammer. As with the previously discussed
hammers, the hammer of FIG. 6A and 6B is curved and tapered and
is intended to be used with a corresponding anvil having slots that
match the trapezoidal shape of the front surface of the hammer.
FIGS. 7A through 9B illustrate alternate embodiments of the hammers
shown in FIGS. 4A through 6B respectively. The function of these
hammers is the same as that of the previously described hammers
except that the hammers of FIGS. 7A through 9B each comprise a body
that is welded to the rotating disc and a removable front surface
that can be made of carbon steel or other hard material. The advantage
of the hammers of FIGS. 7A through 9B is that the front or cutting
surface of the hammers can be replaced if worn or broken. Each of
the front or cutting surfaces 61 is secured to its corresponding
hammer body 62 by means of a bolt 63. With this embodiment, the
hammer body 62 can be permanently fixed to the disc with weld joints
so that only the front or cutting surfaces 61 need to be replaced
FIG. 10 is an edge elevational view of an anvil 64 adapted to be
oriented along a line perpendicular to a radius of the rotating
disc of a disc hog-type wood pulverizing machine. In this embodiment,
the teeth 66 and corresponding slots 67 are seen to be configured
to accommodate the hammers on the rotating disc when the anvil is
oriented perpendicular to a radius. Obviously, any configuration
of hammers and slots between the configuration shown in FIG. 2 and
that shown in FIG. 10 is possible, depending upon the position where
an anvil will be located and the orientation of the anvil relative
to a radius of the disc.
FIG. 11 illustrates a wood pulverizing machine in the form of a
disc hog that embodies principles of the present invention in a
preferred form. For simplicity, only the disc, hammers, anvils,
and infeed spout are shown in FIG. 11. Other functional components
of a disc hog-type wood pulverizing machine, such as the housing,
are illustrated in my U.S. Pat. No. 5469901 and are well known
in the art. In FIG. 11 the rotating disc 71 of the disc hog pulverizing
machine is seen to be studded with a plurality of protruding hammers
72 arrayed about its hub. The hammers 72 can take on any of the
configurations illustrated in FIGS. 4A through 6B or FIGS. 7A through
9B or can take on other configurations according to the intended
use of the machine. An infeed spout 73 is indicated in phantom lines
in FIG. 11. In use, the infeed spout would be mounted to the front
wall of the housing of the disc hog and would provide a feeder opening
through which limbs and other lumber to be pulverized could be inserted.
A first anvil 74 is mounted to the housing of the machine at the
base of the infeed spout 73. In the embodiment of FIG. 11 the anvil
74 is oriented substantially along a radius of the disc and thus
would have teeth and slots shaped substantially as shown in FIGS.
1A, 1B, and 2. The slots formed in the anvil 74 are positioned to
accommodate the hammers 72 which pass through the slots to shred
and shard the wood as previously described.
A second anvil 76 is positioned along one side of the infeed spout
73 and is oriented substantially perpendicular to a radius of the
disc 71. As with the anvil 74 the slots and teeth formed in the
anvil 76 are positioned and oriented to accommodate the movement
of the hammer 72 past the anvil 76 and through the slots formed
therein. With the embodiment of FIG. 11 as wood in the form of
limbs or otherwise, is fed into the infeed spout 73 it is engaged
by the hammer 72 which tears and cuts the wood against both the
radially oriented anvil 74 and the perpendicularly oriented anvil
76. The efficiency of the pulverization process is thus enhanced
by the addition of a second anvil oriented at right angles with
respect to the first anvil. Clearly, a third anvil could also be
added along the other side of the inlet spout 73 and other anvils
could be added as desired around the periphery of the rotating disc
71 to further tear and shard the wood as it is carried about the
The invention has been described herein in terms of preferred embodiments.
It will be obvious to those of skill in the art, however, that various
modifications, additions, and deletions might well be made to the
embodiments illustrated herein without departing from the spirit
and scope of the invention as set forth in the claims.