Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION
Rotor for a Crushing Machine
NAME OF INVENTOR
Kurt R. Feigel, Jr.
FIELD OF THE INVENTION
This invention relates to rotors used in crushing machines.
BACKGROUND OF THE INVENTION
Crushing machines used for shredding wood are well known that use a central
rotor with multiple crushing faces formed around a central block with several
flutes.
Rectangular blades are secured to the crushing faces. The blades impact wood
placed
into the crushing machines and shred the wood. The blades tend to wear out
with time,
particularly when rock contaminants are interspersed with the wood, and also
may
loosen on the rotor. This invention is directed to an improved rotor with
improved
servicing and securing of the blades.
SUMMARY OF THE INVENTION
There is thus provided in accordance with an embodiment of the invention, a
rotor for a crushing machine, the rotor comprising:
a central block mounted on a shaft for rotation;
the central block having tapered blade mounting faces circumferentially spaced
about the central block;
a blade secured to each tapered blade mounting face, each blade having a
tapered rotor mounting face, the tapered rotor mounting face engaging the
tapered blade
mounting face along tapered portions of the tapered rotor mounting face and
the tapered
blade mounting face; and
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plural pins, each pin associated with and secured to a corresponding blade,
each
pin being secured to the rotor to pull the tapered rotor mounting face of the
corresponding blade against a corresponding tapered blade mounting face of the
rotor
and lock the corresponding blade onto the rotor by frictional locking of the
tapered
blade mounting face and the tapered rotor mounting face.
According to a further aspect of the invention, for each blade, one of the
corresponding tapered blade mounting face and the tapered rotor mounting face
of the
blade forms a depression and the other of the tapered blade mounting face and
the
tapered rotor mounting face forms an elevation.
According to a further aspect of the invention, each blade has a square impact
face with four cutting edges and the tapered blade mounting face and tapered
rotor
mounting face match in four rotational positions so that each blade may be
easily rotated
to place any one of its four cutting edges on the outer periphery of the
rotor.
According to a further aspect of the invention, one of the tapered blade
mounting face and the tapered rotor mounting face incorporates a conical
depression,
and the other of the tapered blade mounting face and the tapered rotor
mounting face
incorporates a matching conical elevation.
According to a further aspect of the invention, each pin is threaded into the
corresponding blade.
According to a further aspect of the invention, there is provided a rotor for
a
crushing machine, the rotor comprising:
a central block mounted on a shaft for rotation;
the central block having blade mounting faces circumferentially spaced about
the central block;
a blade secured to each blade mounting face, each blade having a rotor
mounting
face that matches the blade mounting face to which the blade is secured; and
each blade having a square impact face with four edges and the blade mounting
face and rotor mounting face matching in four rotational positions so that
each blade is
rotatable to place any one of its four edges on the outer periphery of the
rotor.
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These and other aspects of the invention are described in the detailed
description
of the invention and claimed in the claims that follow.
BRIEF DESCRIPTION OF THE DRAWINGS
There will now be described preferred embodiments of the invention, with
reference to the drawings, by way of illustration only and not with the
intention of
limiting the scope of the invention, in which like numerals denote like
elements and in
which:
Fig. I is a perspective view of a rotor according to the invention;
Fig. 2 is a side view of the rotor of Fig. 1;
Fig. 3 is an end view of the rotor of Fig. 1;
Fig. 4 is a section through the rotor of Fig. 1;
Fig. 5 is a plan view of the bottom side of a blade used with the rotor of
Fig. 1;
and
Fig. 6 is a section through the blade of Fig. 5.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
In this patent document, the word "comprising" is used in its non-limiting
sense
to mean that items following the word in the sentence are included and that
items not
specifically mentioned are not excluded. The use of the indefinite article "a"
in the
claims before an element means that one of the elements is specified, but does
not
specifically exclude others of the elements being present, unless, unless the
context
clearly requires that there be one and only one of the elements.
Fig. 1 shows a rotor 10 for a crushing machine (not shown), such as the
Universe HOG made by Universe Machine Corporation of Edmonton, Alberta,
Canada.
Apart from what is disclosed here, the crushing machine is otherwise
conventional and
not further described. These crushing machines are used for crushing of waste
material,
and are designed to be able to handle contaminants such as rock. The rotor 10
is formed
as a central block with a series of circumferentially spaced flutes 12. Three
are shown
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but there could be fewer, or more, such as four. Three and four flute rotors
are
commonly used. The central block is mounted for rotation on a shaft 14 which
is
received by the crushing machine. Each flute 12 has a series of axially
extending blade
mounting faces 16. Each blade mounting face 16 is preferably oriented
perpendicularly
to the direction of motion of the flute 12. Successive blade mounting faces 16
are
circumferentially offset from each other in conventional manner. Striker
plates or blades
18 are secured to the blade mounting faces 16. Each blade 18 has a
corresponding rotor
mounting face 20 shown in more detail in Figs. 5 and 6. The rotor mounting
faces 20
match the blade mounting faces 16 for frictional locking. Each blade mounting
face 16
is tapered. For example, at least two opposed portions of the blade mounting
face 16
may be oriented at an angle a, to a perpendicular to the general orientation
of the blade
mounting face 16 such that 00 < a< 900, so that the blade mounting face 16 is
either
convex or concave. Preferably, a< 450, for example 150. The rotor mounting
faces 20
of the blades 18 are correspondingly tapered for a close but not exact fit to
the blade
mounting faces 16. The tapered portions of the blade mounting faces 16 and the
rotor
mounting faces 20 should be so located on the rotor 10 and blades 18 that the
blades 18
may be locked by friction onto the rotor 10. To allow for frictional locking,
the flat
portions of the faces 16 and 20 should not touch, with the contact being along
the
angled or tapered portion of the faces 16 and 20. This may be achieved by for
example
making the elevation slightly larger than the depression. For a six inch wide
blade, a gap
of about 1/32 inches is acceptable between the flat portions of the faces 16
and 20. It is
desirable to minimize this gap without there being actual contact along the
flat portions
of the faces 16 and 20. If there is too much contact between flat faces, the
frictional lock
is diminished and may be eliminated. To ensure stability of the blade 18, it
is preferred
that the tapered portion of the faces 16 and 20 occupy a substantial portion
of the faces,
for example the width of the tapered portion is more than half the width of
the blade.
Force is required to hole the blade mounting faces 16 and the rotor mounting
faces 20 frictionally locked. For this purpose, pins 22, for example socket
cap screws,
one pin associated with and secured to each blade 18 pass through holes in the
flutes 12
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rotor 10 to pull
the rotor mounting face 20 of the corresponding blade 18 against a
corresponding
tapered blade mounting face 16 of the rotor 12. The pins 22 thus lock the
corresponding
blades 16 onto the rotor 12 by frictional engagement of the tapered blade
mounting face
16 and the tapered rotor mounting face 20. The pins 22 may also pass through
countersunk holes in the blades 18 and thread into the rotor 10. Since the
countersunk
holes weaken the blades 18, care must be taken to ensure the blades are thick
enough to
avoid easily being broken.
Although the opposed tapered portions of the rotor mounting faces 20 may form
ridges, it is preferred that the rotor mounting faces 20 are tapered to form
conical
elevations 21 as illustrated in Fig. 6. The corresponding blade mounting faces
16 then
form conical depressions as illustrated in Fig. 4, with parts of the elevation
extending
above the flat portions of the rotor mounting face 20 slightly more than equal
diameter
parts of the depression are recessed from the blade mounting face 16 to allow
for
frictional locking of the depression with the elevation before contact occurs
on the flat
portions of the faces 16 and 20.
When the blade mounting faces 16 form ridges, the blades may be rotated into
two rotational positions, 180 apart. That is, there are two rotational
positions of the
blade mounting faces 16 that are identical to each other. A blade 18 may then
have two
cutting edges 24 opposed to each other, and may be placed initially with one
cutting
edge 24 at the outer periphery of the rotor, and when that wears out may be
rotated 180
so that the other cutting edge 24 is at the outer periphery of the rotor 10.
Preferably,
however, the blades 18 have square impact faces 28 with four equal cutting
edges 24,
and the tapered blade mounting face 16 and tapered rotor mounting face 20
match in
four rotational positions so that each blade may be easily rotated, in 90
increments, to
place any one of its four edges 24 on the outer periphery of the rotor 10. A
conical
depression or elevation may match in infinite positions, including the four
positions at
90 to each other. A conical depression or elevation is easy to machine,
though the
depression and elevation could be a section of a square pyramid (square, with
sloping
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sides), or any of a variety of shapes that allow rotation of the blade to
place any one of
its cutting edges at the outer periphery of the rotor. Either the blade 18 may
have the
elevation or the rotor 10, and the other the depression. As shown, it is
preferred that the
rotor mounting face 20 be raised, the blade mounting face 16 be depressed.
The blades 18 and rotor 20 should all be made of materials that are strong
enough for the intended purpose. Such materials are well known and need not be
described here. The blades 18 are preferably mounted square on the blade
mounting
faces 16, with the edges 24 at the outer periphery of the rotor 10 aligned
parallel to the
shaft 14. In addition, the impact face 28 of each blade 18 is preferably
aligned so that it
is essentially parallel to a radius R (see Fig. 3), and the faces of the
cutting edges 24 are
each flat and perpendicular to the impact face 28, with consecutive faces of
the cutting
edges 24 each being perpendicular to each other. The cutting edges 24 are
provided with
low clearance with the interior of the crushing machine so they must be
mounted
carefully and making them with square edges facilitates making the required
clearance.
As a cutting edge 24 of a blade 18 wears out, it may be rotated 90 and a
fresh
cutting edge 24 is placed into cutting position at the outer periphery of the
rotor 10.
Successive rotations place each cutting edge 24 into cutting position. Due to
wear of the
cutting edges 24, by the time the last cutting edge 24 is placed into cutting
position, if all
of the other cutting edges are too worn, it may be difficult to properly align
the last
cutting edge 24 and in practice it may be useful only to use three of the four
cutting
edges 24 before replacing the blade 18. Instead of a single conical
depression/elevation
for the matching faces, multiple depressions and elevations may be used. For
rotation of
the blade 18 into four positions, the depressions and elevations on the blade
18 must
then be configured so that the blade is rotatable, as for example when there
are four
circular depressions/elevations on the blade and rotor arranged at for example
the
corners of a square. In this instance, a central depression and elevation may
also be
used, and the central depression could be located on a mounting face that has
four
elevations at the corners of the square. Various other configurations of
depression and
elevation having four fold symmetry about an axis perpendicular to the
mounting faces
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may also be used, such as a cross shaped depression and elevation formed with
intersecting troughs on one of the mounting faces and intersecting ridges on
the other.
A person skilled in the art could make immaterial modifications to the
invention
described in this patent document without departing from the essence of the
invention
that is intended to be covered by the scope of the claims that follow.
