Abstrict A device is disclosed to facilitate the crushing of the metal scrap
received from a machine shop as part of a metal and cutting oil
recovery system. The device involves the use of a grate ahead of
the crusher to separate chunky metal parts or heavies and fines
from the enmeshed coils and snarled turnings resulting from machining.
The coils and turnings free of the chunk materials are forcibly
fed into a crusher designed to automatically eject any chunky material
which escapes the separation process.
Claims The embodiments of the invention in which an exclusive property
or privilege is claimed are defined as follows:
1. In combination with a shredding and tearing crusher a device
for separating chunk metal components from the intermeshed turnings
and shavings of metal scrap resulting from machining operations
whereby the turnings and shavings can be passed through the crusher
free of chunk metal, said device having a generally horizontal receiving
section, the crusher having bottom and sides; a horizontally elongated
scrap receiving port in one of said sides and a plurality of crushing
rolls including a pair of vertically spaced receiving and crushing
rolls forming a horizontal scrap receiving path between them at
said scrap receiving port; means to drive said rolls; the scrap
receiving and crushing path between said rolls being so sized as
to be suitable only for turnings and shavings; the improvement in
said device comprising: said receiving section having a discharge
end; a grate member in said receiving section immediately adjacent
said scrap receiving port and means spaced from said grate and said
rolls for pushing the metal scrap across said grate, said grate
member having a plurality of parallel spaced elongated bars extending
lengthwise of said receiving section and over which the scrap is
pushed; said bars being spaced to retain said intermeshed turnings
and to permit small chips and the chunk metal to pass between them
the ends of said bars being so positioned with respect to said crushing
rolls as to introduce said turnings generally horizontally into
said scrap receiving path between the rolls.
2. The device described in claim 1 wherein a screen is provided
in the discharge section at the bottom of said crusher and below
said rolls, said screen having a plurality of spaced elongated bars
extending normal to the axis of rotation of said rolls, said screen
being generally U-shaped to form a concave U-shaped path for the
scrap beneath said rolls, said drive means rotating said rolls in
a direction to return the insufficiently crushed scrap to the receiving
end of said scrap receiving path.
Description BACKGROUND OF THE INVENTION
The invention relates to equipment for recovering and preparing
for reuse the scrap metal produced in machining operations. Basically
this material consists of chips and borings and shavings produced
by such machines as planers, automatic screw machines, boring machines,
lathes, milling machines and saws. This material is normally coated
with the lubricant used in the machining process. The material frequently
has a wide range of sizes and shapes. Some of the material is in
the form of chips and small pieces requiring no size reduction.
Significant quantities of the material consist of elongated spirals
frequently simulating coiled springs. These latter machine turnings
tend to become intermeshed producing a bulky, springy, snarled and
entangling matrix which must be reduced to small chips to permit
efficient extraction of the oil and also to reduce the bulk.
The common method of reducing this type of material to small chips
or pieces is to pass it through a hammermill or a crusher which
reduces these materials to a reasonably uniform small chip or short
length. A number of crushers are available, employing a variety
of reduction means. So far as is known, all of this equipment is
designed for vertical feed, that is, the material to be crushed
is fed from the top, passes down through the crusher and the processed
material is discharged at the bottom.
If the material, as received at the crusher, consisted entirely
of chips, machine turnings, boring and the like, the problem of
effectively crushing and reducing the metallic materials to a reasonably
uniform, small size would be relatively simple. However, normally
these materials, as received at the crusher, contain a substantial
quantity of large pieces or chunks which are not the product of
machining of various metal parts. It is these components of the
material which causes substantial difficulty. These include such
items as ends of bar stock, bolts and steel parts from the machines
on which the materials have been machined, broken and scrap parts.
These materials are not suitable for processing in the crushers.
When such materials enter the crusher, they become jammed in the
teeth or between the rolls of the crusher, causing damage and, in
some cases, stalling the crusher. When this happens, even if the
crusher is not damaged, it is necessary to stop the equipment and
clean out the crusher to free it for further operation. This is
an expensive and time consuming procedure and materially reduces
the economic efficiency of reclaiming the scrap from machining operations.
Heretofore, there has been no successful means by which this problem
could be eliminated despite the fact that it has plagued the machine
turnings recovery field for a number of years.
BRIEF DESCRIPTION OF THE INVENTION
The invention provides a crusher so designed that the material
being fed to the crusher enters from the side rather than from the
top. The invention includes means to positively bias the material
to enter the crusher. In combination with this, the invention provides
a separating grate or grizzly between the end of the conveyor bringing
the metal turnings to the crusher and the entry port where these
materials enter the crushing rolls. The grizzly provides a separation
area across which the entangled turnings are moved. Because they
are so intermeshed, they cannot pass through the grizzly whereas
the larger, heavier metallic chunks and fines are dropped out of
the tangled mass through the grizzly before they can enter the crusher.
The invention contemplates the use of an automatic, reversing mechanism
for the crushing rollers which will eject a larger piece of chunk
material before it results in damage to the crushing rolls. The
grizzly will permit the chunk to drop out, eliminating the problem.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of the crusher of this invention together
with a chunk removing grizzly or grate ahead of it; and
FIG. 2 is a fragmentary sectional, elevational view taken along
the plane II--II of FIG. 1; and
FIG. 3 is a sectional view taken along the plane III--III of FIG.
1; and
FIG. 4 is a bottom view of the separator screen provided at the
base of the crusher chamber; and
FIG. 5 is a sectional, elevational view similar to FIG. 2 showing
a modified construction for the invention; and
FIG. 6 is a sectional, elevational view illustrating a modification
of the grate; and
FIG. 7 is a flow diagram of a process utilizing this invention.
DESCRIPTION OF THE INVENTION
The numeral 10 identifies a conveyor which terminates in a grate
or grizzly 11. The grate 11 connects the conveyor to the crusher
12. The crusher 12 has a housing 13 which encloses a chamber 14.
Mounted within the chamber are a pair of crushing rolls 20 and 21
generally arranged vertically one above the other. The crusher rolls
20 and 21 form a scrap receiving path 22 between them. The scrap
receiving path faces a receiving port 23 which is an opening in
one side of the housing 13. The receiving port 23 is aligned with
the end of the grizzly or grate 11 and it is through this port that
scrap is received by the crusher.
Behind the crushing rolls 20 and 21 is a third crushing roll 24.
This roll is so located that it intercepts the scrap or turnings
material as it exits from the path between the roll 20 and 21. The
crushing rolls 20 21 and 24 can be of any of a number of conventional
designs currently used for crushing and breaking up materials. Conventionally,
these rolls include rows of teeth arranged so that the teeth of
one roll will intermesh between the teeth of an adjacent roll resulting
in the metal turnings being broken and torn as they pass between
the rolls. The rolls 20 and 21 are rotated, as indicated by the
arrows, in a manner to draw the metal turnings or scrap from the
grate 11 and pull it between the rolls.
The crushing roll 24 is rotated in the same direction as the lower
roll 20 thus, tending to wipe the metallic material upwardly where
some of it may become entangled with the teeth of the upper roll
and be swept around to be passed, once again, through the crushing
path. Other portions of the metal are carried around the roll 24
and are crushed as they are dragged through the teeth of the combing
bar 25. It will be recognized that as the metal becomes broken down
into short lengths or small, chip-like fragments, it is too small
to be trapped by the teeth of the rolls and drops away from the
rolls to be discharged through the bottom of the crushing chamber
14.
The bottom of the crushing chamber 14 is formed by the screen 26
which is seen in the bottom view in FIG. 4. The screen consists
of a plurality of spaced, parallel bars 27 so shaped as to form
a concave bottom for the chamber. The bars are spaced such that
that portion of the metal which has been crushed or broken down
to the desired size will drop between them but that portion of the
metal requiring further crushing is retained. Because of the shape
of the screen 26 a generally U-shaped path indicated by the arrow
A is created. This path, by its shape, cooperates with the lower
roll 20 to cause the metal scrap requiring further crushing to be
swept upwardly and returned to the entrance of the scrap receiving
path 22. The crushed metal dropping through the screen 26 falls
into the discharge chamber 28. At the bottom of the chamber 28 a
screw conveyor 29 is provided to remove the crushed metal to other
processing equipment. It will be recognized that any other type
of conveyor, suitable for transporting the crushed metal can be
substituted for the screw conveyor 29. This conveyor does not form
any part of this invention.
The supply conveyor 10 can be of various designs suitable for moving
the entangled mass of metal turnings created by a typical machine
shop operation. In the particular embodiment illustrated, the conveyor
is of the harpoon type, having flights 40 mounted on and reciprocated
by a rod 41 (FIG. 3). The conveyor is at the bottom of a V-shaped
trough 42. The conveyor, as so described, is conventional and the
details of its construction form no part of this invention. The
supply conveyor 10 discharges onto the grate or grizzly 11. The
grate is confined between upright sides 43 and consists of a plurality
of spaced parallel bars 44 extending lengthwise of the conveyor
and thus in the direction of movement of the metallic scrap material
as it is pushed by the conveyor to the crusher 12. The spacing between
the bars 44 is such that larger metal chunks along with bar ends,
nuts, bolts, screws and other chunky, extraneous metal material,
not properly a part of the machine turnings or borings or chips
will drop between the bars. Thus, they are separated from the entangled
mass of turnings. Also small chips and other components of the scrap
metal which are already small enough to be acceptable without passing
through the crusher will also drop through the grate. The remainder
of the scrap metal will be an entangled collection of turnings and
materials which will simply slide across the grate to the crusher.
In its preferred construction the discharge ends of the bars forming
the grate terminate short of the ends of the teeth of the rolls.
Since the teeth are arranged in rows spaced circumferentially of
the rolls with the teeth of one row circumferentially spaced from
the teeth of adjacent rows, the length of the gap in the interspace
between teeth can be up to about four inches. This arrangement is
effective to prevent balls of snarled, coil material from falling
between the ends of the grate and the rolls, yet permitting the
normal chunk or heavy to drop out.
The crushing rolls 20 21 and 24 of the crusher are driven by a
prime mover 50 which operates through a gear reducer 51 to drive
the rollers. Connected to the gear reducer 51 is a torque demand
sensor 52. If the torque demanded by the crushing rolls exceeds
a certain value, the sensor will stop the rolls and reverse their
direction of rotation. By this means, should a large chunk fail
to be removed from the scrap material by the grate 11 and enter
the crusher to become wedged between the rolls, the rolls will stop,
be reversed and the chunk ejected before the rolls are damaged.
Preferably, the chunk will be ejected from the rolls with sufficient
force to eject it back onto the grate where it can drop through.
The rolls then, after a pause, will be caused to restart the crushing
action.
FIG. 5 illustrates the fact that the grate 11 need not necessarily
be horizontal but can be inclined downwardly toward the crusher
12. This arrangement is particularly useful if the metal turnings
or scrap are of a nature which will not readily slide across the
grate as a result of being pushed from behind by the conveyor. The
inclination of the grate 11a urges the materials to slide down into
the path of the crusher rolls. This arrangement is essential where
no conveyor is used, the material being dumped in mass into a hopper
to be fed to the crusher. In this case the grizzly 11a serves as
the bottom of the hopper.
It has been found to be essential that the scrap be positively
biased to enter the crusher rolls. This necessity is a result of
the physical nature of the scrap. The snarled, bulky material which
requires crushing tends to roll up into a ball. Unless it is positively
forced to enter the crushing path between the rolls, it will simply
roll into a ball ahead of the rolls. While gravity can be used to
provide the positive feed, a powered conveyor is preferred.
FIG. 6 illustrates the fact that the bars 44a of the grate 11b
need not necessarily form a laterally flat surface. In this construction,
the grate surface is laterally concave, thus continuing the general
shape of the trough-like conveyor.
The invention provides an effective by-pass for the crusher. It
will be noted that the scrap material which is passed through this
equipment is reunited in the chamber 28 since, in subsequent treatment
of the scrap, the product will be classified according to weight
and size. Thus, the invention provides a by-pass for the crusher,
permitting the bulky, stringy, spring-like coils to be reduced to
small pieces without the interference and delay heretofore occasioned
by the chunk materials present in the machine scrap as it is received.
The invention materially increases the efficiency of the equipment
by either eliminating or substantially eliminating operational shutdowns
of the crusher which have previously been required to permit removal
of chunk type scrap entering the crusher. It also eliminates the
time loss incident to replacement of the crusher rolls or their
teeth damaged when large chunks become trapped between them.
The invention also makes possible utilization of a method of continuous,
automated machine scrap processing. In this process, as illustrated
in FIG. 7 the scrap is forcibly passed over a separator where the
fines and chunks are separated from the material requiring crushing.
The fines and chunks are discharged along path A and the material
to be crushed along path B. The crushed material is discharged from
the crusher along path C where it is recombined with the material
from path A and conveyed along path D to the classifier. At the
classifier the chunks are separated and discharged at E and the
remaining fines and crushed material is forwarded along path F to
the wringer where the lubricant is removed and the basically lubricant-free
scrap discharged to a suitable conveyor or container. A wringer
suitable for use in this process is disclosed in U.S. Pat. No. 4137176
issued Jan. 30 1979 entitled "Chip Discharge For Continuous
Chip Wringer".
The invention accomplishes its objectives by relatively simple
and inexpensive equipment. Being uncomplicated, it is dependable
and durable.
While a preferred embodiment of the invention has been described
together with a modification, it will be recognized that other modifications
can be made within the scope of this invention. Such modifications
as do not depart from the principles of the invention are to be
considered as included in the hereinafter appended claims unless
these claims, by their language, expressly state otherwise. |