Note: Descriptions are shown in the official language in which they were submitted.
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.2148878
This invention relates to shredders, and in particular to a shredders of
the type where the material to be shredded is pulled downwardly through
successive pairs of counter-rotating, intermeshing blades or knives.
The increasing awareness of the need to preserve the quality of the
global ecosystem by conserving natural resources has created societal
pressures to
recycle materials. Because shredding is often the first stage in recycling
operations,
there is now an increased demand for reliable shredders, particularly those
which
can be adapted to shred a wide range of materials. Shredding is also
increasingly
required for applications outside recycling, such as reducing the volume at
land-fill
sites.
Shredders are of course very well known in the prior art. The inventor
has discovered a particular, configuration, not known in the prior art to the
best of
his knowledge, which offers simple and therefore inexpensive construction, and
which seems to provide superior performance for a wide range of materials.
It is an object of the invention to provide an improved shredder which
is reliable, effective with a wide range of materials, and relatively simple
in
construction.
In the invention, the material to be shredded is pulled downwardly
through successive pairs of counter-rotating, intermeshing blades within a
housing.
The blades are mounted on pairs of shafts, one pair above the other.
Preferably,
there are three pairs of shafts, so that the material undergoes three stages
of
shredding, but the number of pairs could be readily varied.
Material inserted through an inlet at the top of the housing is caught
by the blades and pulled down through the shredder, to an outlet at the
bottom, the
material being shredded into successively smaller pieces by virtue of being
sheared
apart by the intermeshing blades.
With three pairs of shafts, i.e. six shafts in total, the shafts may be
driven by two motors, which preferably are arranged at opposite sides of the
housing, one driving four of the shafts, and the other driving two of the
shafts, via
pulleys which are routed to provide the desired counter-rotation. In each pair
of
shafts, one shaft rotates at a different speed from the other shaft.
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The above features and further features of the invention will be
described or will become apparent in the course of the following detailed
description.
In order that the invention may be more clearly understood, the
preferred embodiment thereof will now be described in detail by way of
example,
with reference to the accompanying drawing, in which:
Fig. 1 is a perspective view of the shredder with one side panel of the
housing cut away;
Fig. 2 is a top view of the shredder;
Fig. 3 is a front view of the shredder;
Fig. 4 is a side view of the shredder, in section, to show the
intermeshing of the blades;
Fig. 5 is a first side view of the shredder;
Fig. 6 is a second side view of the shredder;
Fig. 7 is a third embodiment of the housing of the shredder; and
Fig. 8 is a variation of the third embodiment.
Referring to the drawings, Fig. 1 shows a perspective view of the
shredder with one side panel 2 of the housing 4 cut away. Within the housing,
there are three pairs of shafts, which for greater clarity may be referred to
as front
upper shaft 7, the front middle shaft 8, the front bottom shaft 9, the rear
upper
shaft 10, the rear middle shaft 11, and the rear bottom shaft 12. Referring to
Figs.
2, 5 and 6, "front" means away from the motors 14 and 15; i.e. the motors are
at the rear of the shredder.
The upper four shafts are 3 inches in diameter; the lower two shafts
are 2-112 inches in diameter. By the time the material reaches the blades on
the
bottom two shafts, it has already been substantially reduced in piece size, so
a
smaller shaft diameter is possible; the blades on the bottom two shafts do not
have as much work to do as the upper ones, and do not need to be quite as
substantial.
Welded to each shaft are many blades 16. The blades are of any
suitably hard metal. In the preferred embodiment, for example, they are of
T100
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CA 02148878 2000-07-18
steel. The blades are flame cut to their elongated rectangular shapes,
predrilled to
match the applicable shaft diameters, and then welded to the shafts. As seen
in
Figs. 1 and 4 in particular, the blades intermesh. However, they do not always
intermesh in the relative positions as shown in Fig. 4, because there are
different
rotation speeds, as will be explained shortly.
As can be seen from Fig. 2, there are two motors 14 and 15, one on
each side of the shredder. The motor 14 drives four of the shafts via three
belts
18 routed around pulleys on the motor drive shafts and on the six shredder
shafts,
and the motor 15 similarly drives the other two shafts also via three belts
18. As
seen in Fig. 5, the belts from motor 14 are routed first under the pulleys on
the
front bottom shaft 9, then rearwardly and under the pulleys on the rear middle
shaft
11, then downwardly and forwardly under the pulleys on the front middle shaft
8,
then up and over the pulleys on the front upper shaft 7 and back to the motor.
As seen in Fig. 6, the belts from motor 15 are routed first under the
pulleys on the rear bottom shaft 12, then upwardly and over the pulleys on the
rear
upper shaft 10 and back to the motor.
Thus in each pair of shafts, the blades rotate towards each other and
downwardly, to pull the material through the shredder.
Both motors have 6-1/4 inch diameter pulleys. The pulleys on front
upper shaft 7, rear middle shaft 11, and front bottom shaft 9 are 9-1 /4
inches in
diameter. The pulleys on the rear upper shaft 10, front middle shaft 8, and
rear
bottom shaft 12 are 8-1/4 inches in diameter. Each motor is operated at
approximately the same speed, e.g. 17,500 rpm.
Thus in each pair of shafts (upper, middle and lower), there is one
shaft with 8-1 I4 inch pulleys, and the other with 9-1 I4 inch pulleys. The
blades in
each pair therefore rotate at different speeds, so that they do not mesh
together in
the same relative position each time. This is believed to be one factor which
accounts for the extremely effective performance of the shredder.
Since the motor 15 drives only two shafts whereas the motor 14
drives four shafts, the motor 15 can be lesser rated. For example, the motor
14
could be 50 H.P., and the motor 15 could be 40 H.P.. Electric motors are
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CA 02162511 2000-09-25
preferred, although obviously the invention is not restricted to any
particular type
of motor.
A further preferred embodiment of a shredder can be seen in Fig. 7,
wherein the housing is structured modularly, in that it consists of three
frames 19,
20 and 21 arranged above each other. The three frames contain the pairs of
shafts
7, 10 and 8, 11 and 9, 12 respectively, arranged above each other. The frames
with their pairs of shafts each form a module with the bearings and the belt
pulley.
Each module can be replaced as a whole unit, so in case of repair or
maintenance work, easy handling of the shredders is provided. Also, down time
may be shortened by installing a new module, in comparison to the time it
would
take to repair the module. After having mounted the new module, the shredder
can
immediately operate again. Then the replaced module can be repaired or
maintained
without affecting operations.
A variation on the Fig. 7 embodiment is shown in Fig. 8. In this
variation, the frames or housing sections separate from the other in
horizontal
planes 22, 23, and 24 corresponding to the planes of the shafts. This
structure
has the advantage that when a housing section is removed, one pair of shafts
is
exposed to make it relatively easy to repair or replace a damaged shaft.
The configuration of the shredder in general has been found to be
highly effective in shredding a wide range of materials, from automobile body
side
molding and trim, to running shoes, video tapes, computer keyboards,
electronic
items generally, toys, glass bottles, etc., etc.. This list is certainly not
all-inclusive,
since the shredder can be readily adapted to a wide range of materials.
It will be appreciated that the above description relates to the preferred
embodiment by way of example only, and that many variations will be obvious to
those knowledgeable in the field. Such obvious variations are intended to be
within
the scope of the invention as defined by the following claims.
