Abstrict A centrifugal impact rock crusher having a centrally located rotary
impeller table with a feed cone centrally located on it is equipped
with a vertically reciprocating feed chute located above the feed
cone. The mouth of the feed chute periodically moves downward to
partially surround the feed cone to vertically distribute radial
flow of material being crushed and thereby reduce concentration
of impeller shoe and anvil face wear during crushing of uniformly
sized gravel.
Claims What is claimed is:
1. In a centrifugal impact rock crusher of the type having an impeller
table mounted for rotating about a generally vertical axis of rotation,
a plurality of impellers located at angularly spaced intervals on
the table and having faces extending above the table generally perpendicular
thereto, a material distributing feed cone mounted centrally on
the table, a feed chute located above the feed cone for distributing
material to be crushed centrally onto the feed cone, and motor means
for rotating the table and feed cone at a predetermined speed so
that material deposited onto the feed cone is thrown radially outwardly
from the feed cone intermediate the vertical extent of the impeller
faces, the improvement comprising reciprocating means associated
with said feed chute for cyclically raising and lowering the mouth
thereof relative to said material feed cone.
2. The rock crusher of claim 1 wherein said feed chute is oriented
so that said mouth moves between an upper position above the apex
of said feed cone, and a lower position below the apex of said feed
cone so that flow of material from said feed chute is partially
restricted by said feed cone.
3. The rock crusher of claim 1 where said reciprocating means raise
and lower said feed tube at 10-15 cycles per minute.
Description BACKGROUND OF THE INVENTION
The present invention relates to improvements in centrifugal impact
rock crushers, and particularly to feed apparatus for use in such
rock crushers to improve the pattern of abrasive wear on replaceable
portions of the rock crushers in order to reduce the frequency of
need for replacement of those parts.
Centrifugal impact rock crushers generally comprise a horizontal
impeller table which rotates about a vertical axis, at a speed which
is typically about 1400 RPM, while material to be crushed is fed
downwardly onto the center of the impeller table. Impellers mounted
on table direct the material radially outward as the centrifugal
force created by the rotating table throws the material off of the
impellers and against the faces of stationery anvils surrounding
the table, where the impact shatters the material into smaller pieces.
Since the dust and crushed rock created by the crushing operation
is extremely abrasive, the impellers are equipped with replaceable
elements called shoes, and the anvils and other portions of the
rock crusher exposed to contact with the material being crushed
are similarly equipped with replaceable faces or liners.
The impeller table typically includes a central feed cone which
rotates with the table to distribute the material among the several
impellers to evenly distribute wear of the impeller shoes and loading
of the bearings which support the impeller table. When crushing
pieces of rock of mixed sizes, the different sized pieces of material
generally are thrown radially outward from the cone at different
heights corresponding somewhat to the weight of each piece. That
is, smaller pieces leave the cone at a higher location than do heavy
pieces of rock. As a result, abrasive wear is fairly evenly distributed
over the entire wearing surfaces of the impeller shoes, anvils,
and other replaceable parts.
A serious problem, however, is presented when a centrifugal rock
crusher of this type is used to crush gravel of a fairly uniform
size into sand. Gravel or crushed stone which has been graded to
contain only pieces of a fairly small variation of size, such as
in the size range of 3/8-1/2 inch maximum dimension of each piece,
is suitable to be crushed into sand in this type of rock crusher.
Crushing material of such a uniform size, however, results in concentrated
wear of impeller shoes and anvil face surfaces, since the gravel
is consistently being thrown outwardly from the feed cone at about
the same height. With a large proportion of the material concentrated
near one height relative to the impeller, wear is also concentrated
on the surfaces of the impeller shoes and the adjacent anvils at
that same height, causing development of a groove along the faces
of the impeller shoes and anvils. Such grooves, once started, are
self-generating, and eventually require early replacement of impeller
shoes and anvil faces, while much of their surfaces are free of
appreciable wear.
What is needed therefore is a centrifugal impact rock crusher in
which the flow of material to be crushed is distributed over the
entire surface of each impeller shoe and anvil face to evenly spread
abrasive erosion of internal parts of the rock crusher while crushing
material consisting largely of pieces of uniform size.
SUMMARY OF THE INVENTION
The above described need for a centrifugal impact crusher including
a mechanism for evenly distributing the abrasive effects of the
material being crushed over the impeller shoes, anvil faces, and
other crusher parts normally exposed to abrasive material is satisfied
in the present invention, in which a centrifugal impact rock crusher
having a central material distributing feed cone located on a rotary
impeller table includes a feed chute which reciprocates vertically
to periodically restrict pieces of the material to be crushed within
the mouth of the feed chute, thereby causing the material to be
deposited lower on the feed cone than it would otherwise be in order
to allow the material to be thrown radially outward along the lower
portions of the impeller shoes, and in turn strike the lower portions
of the corresponding anvils.
The reciprocating feed chute includes an open lower end or mouth
which is small enough to extend downwardly between the inner ends
of the several impellers, yet which is large enough to surround
at least a portion of the feed cone on the impeller table. When
the feed chute is in its uppermost position, material deposited
from the chute is free to be projected radially away from the upper
portion of the cone, but when the feed chute's mouth is in its lowermost
position, material to be crushed is restricted so that it must flow
outward at a lower height relative to the impeller shoes. The vertically
reciprocating motion of the feed chute mouth thus distributes the
abrasive effects of crushing uniform material over a greater portion
of the impeller shoes, anvil faces, and other crusher components
than was previously obtained.
It is therefore a primary objective of the present invention to
provide an improved centrifugal impact rock crusher which can be
used to crush pieces of material of uniform size into smaller pieces
wherein the operating life of the replacable wear resistant parts
is longer than would otherwise be achieved.
It is another important objective of the present invention to produce
even patterns of wear on the impeller shoes and anvil faces of a
centrifugal impact rock crusher while crushing substantially uniform
pieces of rock over a long time.
It is yet another objective of the present invention to reduce
the expense of operation of a centrifugal impact rock crusher by
extending the useable life of the impeller shoes, anvil faces, and
other internal parts of such a rock crusher which are normally subject
to abrasion by rock being crushed.
It is a principal feature of the present invention that it provides
a vertically oscillating feed chute for use in a centrifugal impact
rock crusher to distribute material being crushed over a vertical
range, thus distributing the abrasion effects of the material over
a wider portion of rock crusher internal surfaces.
It is another important feature of the present invention that it
provides a centrifugal impact rock crusher having a feed chute which
periodically descends to surround a portion of the feed cone of
the impeller table, restricting radial movement of the material
being crushed.
It is a principal advantage of the present invention that it provides
a mechanism for distributing the radial flow of material being crushed
over a range of heights relative to the rotary impeller table, thus
distributing abrasive wear of impeller shoes, anvil faces, and other
surfaces more evenly than has previously been accomplished.
It is another important advantage of the present invention that
it permits operation of such a centrifugal impact rock crusher over
longer periods without the necessity of replacement of impeller
shoes, anvil faces, and other internal surfaces subject to abrasion
by the materials being crushed, thus reducing expenses of operating
such a rock crusher below what was previously possible when crushing
uniform sized gravel.
The foregoing and other objectives, features, and advantages of
the invention will be more readily understood upon consideration
of the following detailed description of the invention, taken in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partially cut away pictorial view of a centrifugal
impact rock crusher of the type to which the present invention is
applicable, with the cover of the rock crusher removed.
FIG. 2 is a fragmentary sectional view of the rock crusher shown
in FIG. 1 equipped with a reciprocating feed chute embodying the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, a centrifugal impact rock crusher
10 shown in FIG. 1 is seen to include a base 12 a drive motor
14 located behind a shield 16 and a generally cylindrical crusher
housing 18. Located within the housing 18 is an impeller table 20
supported by a stand 22 having a generally horizontally oriented
top, and arranged for rotation about a generally vertical axis of
rotation, as it is rotated by a shaft 24 (FIG. 2) driven by the
motor 14.
The impeller table 20 includes a plurality of replaceable top liners
26 rim liners 28 and impellers 30 having shoes 32 including generally
vertically and radially extending forward faces. A material distribution
feed cone 34 is located centrally on the impeller table 20 to receive
material to be crushed and to distribute the material to the several
impellers 30. Around the periphery of the housing 18 a plurality
of replaceable anvil faces 36 are located in horizontal alignment
with the impellers 30 and housing liners 38 are mounted on interal
surfaces of the housing 18 below the anvils 36. A generally horizontally
extending cover member 40 encloses the upper portion of the housing
18 and a feed chute 42 extends downwardly through an opening in
the cover member 40. The feed chute 42 has a downwardly open mouth
44 at its lower end, and is supported, for example, by a support
member 46.
The support member 46 is supported by a pair of links 48 connected
to reciprocating apparatus 50 adapted to move the feed chute 42
reciprocally upward and downward as indicated by the arrows 52.
The reciprocating apparatus 50 may, for example, consist of a cam
and follower assembly, a crank assembly, or hydraulic piston and
cylinder assembly, the only requirement being that it be capable
of periodically raising and lowering the mouth 44 of the feed chute
42 through a range of motion approximately equal to the height of
the impellers. The rate at which the feed chute is cycled somewhat
effects the manner in which the material is distributed on the feed
cone and it has been found that optimum distribution occurs at approximately
10-15 cycles per minute. An infeed hopper 54 is supported immovably
in a position convenient for receiving material to be crushed by
the rock crusher 10 with provision being made for the feed chute
42 to move relative to the infeed hopper without interference.
In operation of the rock crusher 10 according to the invention,
material to be crushed is introduced into the infeed hopper 54
from which it flows downward as indicated by the arrow 56 encountering
the feed cone 34 as it exits from the mouth of the feed chute 42.
As the material comes into contact with the feed cone 34 which
is rotating along with the entire impeller table at an exemplary
speed of 1400 RPM, the pieces of material experience an angular
acceleration tending to throw them radially outward into the path
of rotation of an impeller 30 as indicated by the arrow 58. The
horizontal level at which the material leaves the feed cone depends
on the weight of the individual pieces of material and the speed
at which the feed cone is rotating. Accordingly if the pieces of
material are fairly uniform in size they are thrown off of the feed
cone over a relatively narrow band.
The mouth 44 of the chute 42 when in the position shown in FIG.
2 restricts movement of the material in a radially outward direction
until the material has descended to the level indicated by the arrows
58 and thereby forces the material to a lower portion of the feed
cone than it would otherwise strike so that the material proceeds
along the lower portions of the impeller shoes 32 as indicated
by arrow 60. As the reciprocating apparatus 50 lifts the feed chute
42 upward, raising the mouth 44 to the position indicated in broken
line in FIG. 2 material being crushed in the normal manner is permitted
to flow outwardly away from the feed cone 34 along the top portions
of the impeller shoes 32 as indicated by the arrow 62. As the mouth
44 of the feed chute 42 reciprocates in this manner, the material
being crushed is forced to move radially away from the feed cone
at various heights, with resultant abrasion of the impeller shoe
faces and the anvil faces against which the material is impelled
also being distributed vertically, rather than concentrated at a
single height determined by only the size of the individual pieces
of material to be crushed. As a result, the rock crusher 10 may
be used to crush a far greater amount of material of uniform size
before replacement of impeller shoes, anvil faces, and liners is
required by wear.
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, of excluding 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. |