Note: Descriptions are shown in the official language in which they were submitted.
1268750
CONE DISC~ARGE FOR DIAPHRAGM
DISCHARGE ROTARY GRINDING MILL
The invention broadly relates to discharge end
assemblies for rotary grinding mills, and is specifi-
cally directed to an improved discharge cone casting for
such assemblies~
Rotary grinding mills are used to reduce or
comminute ore fragments by tumbling the fragments to
impact upon themselves, or to be impacted by balls or
rods.
The rotary grinding mill conventionally con-
; 10 sists of a large cylindrical drum having an axial inlet
centrally disposed in one end of the drum and a cen-
trally disposed outlet at the other. The ore charge is
introduced into the inlet, from which it is disseminated
radially outward through an assembly of feeder castings
to the inner cylindrical surface of the drum. The drum
surface is provided with a liner assembly having axially
extending lifter bars to lift the ore fragments and
cause them to tumble and become comminuted.
As the ore fragments are reduced in size, they
progress toward the discharge end of the mill, which is
provided with an assembly of discharge castings the
function of which is to channel the comminuted ore
radially inward and then axially outward to the mill
outlet.
12687'5!~)
Conventionally, the discharge end assembly
comprises a plurality of tiers of castings, each tier
itself comprising a plurality of castings and being
disposed in an annular configuration. The respective
tiers have progressively smaller diameters and are con-
centrically disposed, occupying the mill discharge end
from the cylindrical shell surface approximately to a
point where the mill end curves to the axial discharge
outlet.
The radially outermost tier is provided with
grates adjacent the cylindrical surface of the drum to
receive the comminuted ore, and the grates communicate
with a plurality of radial channels defined within the
tiers of castings that guide the comminuted ore toward
the mill outlet.
The discharge end assembly further comprises a
plurality of discharge cone castings, disposed centrally
of the drum between the innermost tier and the mill
outlet, the function of which is to receive the com-
minuted ore from the radial channels within tiers ofcastings and cause it to flow smoothly in the transition
from radially inward flow to axially flow.
Because the discharge cone castings channel
the flow of comminuted material through substantially a
90 turn, and coupled with the fact that the flow of
material converges radially toward the axial outlet, the
discharge cone castings are subjected to significant
abrasion and wear. The problem is compounded by prior
art discharge cone castings which, due to their complex
configuration, have been made up of a plurality of com-
ponents that are bolted together at the time of
installation. The multi-component discharge cone
castings necessarily have internal joints, and the com-
minuted material wears the castings in the joint area
much more rapidly.
12687~,()
In addition, the multi-component aspect of the
discharge cone casting makes it more difficult to
install and remove, and due to the extreme weight of the
individual castings, this also represents a potential
hazard to personnel involved in casting removal and
replacement.
Another problem encountered with prior art
discharge cone castings is shifting of the casting
assembly during operation. This is the result of using
mechanical wedging in prior art structures, both in
radial and lateral directions, to hold the assembly in
place. With such mechanical wedging, it is possible for
the wedges to become loosened during operation, which
results in shifting or movement of the assembly and in
reduction in effectiveness.
Last, because of the multi-component approach,
wear of the castings is often uneven, necessitating the
premature replacement of one component while the
remaining components do not require replacement. This
problem is compounded by the fact that the component
immediately adjacent the mill end generally wears most
rapidly, requiring removal of all components of the cone
discharge casting for replacement purposes. This
results in increased maintenance and downtime, thus
decreasing the effectiveness of the mill and increasing
its cost of operation.
1268750
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An aspect of the invention is as follows:
~ discharge cone casting Eor the discharge end
of a rotary mill, comprising:
a generally flat base member having a bottom
surface adapted to conEorm to the mill di~scharge end and
a top surface, the base mPmber generally taking the form
of a truncated triangle and having a predeter,nined
longitudinal dimension wi-th converging sides;
a top member having converging sides similar
to those of the base member and a greater lo~gitudinal
dimension, one portion of the top member be.ing generally
flat and disposed in substantially parallel, overlying
relation to the base member, and a second portion of the
top member extending beyond the base member and curving
toward the plane thereof;
and an interconnecting web member extending
transversely between the base and top members and
disposed centrally thereof to define a generally I-
shaped cross section therewith, the web member being
integrally formed with said base and top members to
create a jointless single casting.
Summary of the Invention
The subject invention is directed to an
improved discharge cone casting which is uniquely con-
figured to be integrally cast in a single component.The single casting has no joints, and inherently resists
abrasive wear by the comminuted material and lasts
longer. Further, the integral casting is advantageously
designed with rounded areas where joints previously
~687~0
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existed to further reduce wear, and it is thickened in
high-wear areas and thinned in low-wear areas so that
overall wear is balanced and uniform. As a result, pre-
mature wear in critical areas is avoided, and replace-
ment of all cone discharge castings is predictable and
accomplished at the same time.
The integral casting is also designed with a
single, centrally located upstanding web in which a
plurality of mounting bolt holes are formed. This
enables the cone discharge castings to be bolted dir-
ectly to the mill end firmly and securely, obviating the
wedge-type approach of prior art structures and the
problem of shifting.
Further, the integral cone discharge casting
is far easier to remove and install, obviating the pro-
blem of multiple components, which require individual
handling, difficulty in assembly and alignment, and
related hazards.
Based on the foregoing features and advan-
tages, the inventive integral discharge cone casting
lasts longer, requires less maintenance, decreases
replacement time and thus leads to less mill downtime
and reduced mill maintenance costs.
Brief Description of the Drawinqs
Figure 1 is a fragmentary end view of the
discharge end of a rotary grinding mill as viewed within
the mill;
Figure 2 is a fragmentary sectional view of
the discharge end of the rotary mill as viewed along
line 2-2 of Figure l;
Figure 3 is an enlarged sectional view taken
along the line 3-3 of Figure l;
Figure 4 is an enlarged sectional view taken
along the line 4-4 of Figure l;
126875C)
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Figure 5 is an enlarged sectional view taken
along the line 5-5 of Figure l;
Figure 6 i.5 an enlarged end view of a cone
discharge casting forming part of the mill discharge end
assembly viewed from the same perspective as Figure l;
Figure 7 is a view in side elevation of the
cone discharge casting of Figure 6;
Figure 8 is an enlarged bottom view of the
cone discharge casting as viewed from the line 8-8 of
Figure 7;
Figure 9 is an enlarged sectional view taken
along the line 9-9 of Figure 7;
Figure 10 is an enlarged sectional view taken
along the line 10-10 of Figure 7;
Figure 11 is an enlarged sectional view taken
along the line 11-11 of Figure 7;
Figure 12 is an enlarged fragmentary sectional
view exemplifying connection of the cone discharge
casting to the mill;
Figure 13 is an enlarged fragmentary end view
of an alternate form of the cone discharge casting; and
Figure 14 is an enlarged fragmentary side view
of the cone discharge casting of Figure 13.
Description of the Preferred Embodiment
With initial reference to Figures 1 and 2, a
discharge end assembly for a rotary grinding mill is
referred to generally by the numeral 11. The assembly
11 comprises a number of component castings discussed in
further detail below, which are individually secured to
the structure of the mill end. This structure includes
a trunnion 12, an endplate 13, a cylindrical shell plate
14 and a retainer ring 15.
The mill end components 12-15 rotate about the
rotational axis of a hollow trunnion 12 to comminute ore
~X68750
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fragments introduced through an opposed inlet or charge
end (not shown). The purpose of the discharge end
assembly 11, which generally takes the form of a curved
cone, is to receive and conduct the flow of slurry or
dry comminuted material out of the mill. To accomplish
this, the flow direction of the comminuted material must
change from axial, along the internal cylindrical sur-
face of the mill as it rotates, radially inward toward
the center of the mill, and then axial at the mill
discharge end within the trunnion, which defines the
mill outlet.
The discharge end assembly consists of four
separate sets of castings, which bear general reference
numerals 16-19, respectively. The castings 16 are dis-
posed the farthest radial distance from the mill axis,and together define an annular array or ring extending
360 around the discharge end. The castings 17 are
disposed radially contiguous with the castings 16, and
also define an annular ring or array extending 360
around the mill discharge end. Similarly, the castings
18 are radially contiguous with the castings 17 and
define a smaller annular array radially within the other
two.
The castings 19 are of considerably greater
radial dimension than any of the castings 16-18, as
shown in Figure 1, and they occupy the radial distance
between the innermost end of the castings 18 and the
retaining ring 15.
With continued reference to Figure 1, and with
additional reference to Figures 3-5, it will be seen
that the castings 16-18 are in essence caps that overlie
and are carried by wear castings 21, 22 that contact the
mill end. These castings 21, 22 are also respectively
arranged in annular arrays, and together occupy the same
radial distance as the castings 16-18.
1~68750
With reference to Figures 1, 2 and 5, each of
the wear castings 21 has a cross section taking the form
of an inverted T defined by a flat base 21a and an up-
standing web 21b. Three bolt holes 21c are formed
through the upstanding rib 21b in spaced apart relation.
The cap casting 16 that overlies a portion of
wear casting 21 comprises a relatively flat but thicker
base 16a, a large, centrally disposed rib 16b and
smaller half ribs 16c that together form a full but
smaller rib with the adjacent casting. A plurality of
grates 16d, 16e are formed on opposite sides of the
large rib 16b, and these grates accept the slurry or dry
comminuted material from within the mill to initiate the
flow of material toward the mill outlet.
With specific reference to Figure 5, it will
be seen that each of the cap castings 16 has a centrally
disposed recess 16f below the rib 16b sized to receive
the web 21b of the underlying wear casting 21. This
interrelationship insures that the casting 16 is located
properly.
Casting 16 further includes mounting bores 16g
that are aligned with two of the mounting bores 21c,
permitting a single bolt to pass through the aligned
openings in the castings and an aligned opening in the
endplate 13. A typical mounting bolt 23 with sealing
washer 24 and nut 25 is shown in Figure 2 in connection
with the casting 17, and the same mechanical arrangement
is used for all of castings 16-18 and 21-22.
As assembled, and with reference to Figure 5,
a channel 26 is defined between the castings 16 and 21
through which comminuted material begins its upward
flow.
With reference to Figures 1, 2 and 4, casting
22 also comprises a flat base 22a and a taller up-
standing web 22b having essentially straight sides. A
1~68750
plurality oE bolt holes 22c are formed in the upstanding
web 22b and extend entirely therethrough.
The overlying cap casting 17 also has a sub-
stantially flat base 17a and large upstanding rib 17b
with half ribs 17c formed along each edge. Mounting
bolt holes 17d are formed in alignment with two of the
mounting openings 22c and the mounting opening 21c that
is overlapped by the casting 17. These castings are
also mounted by locking bolts 23, sealing washers 24 and
nuts 25.
As assembled, and with reference to Figure 4,
the channel 26 continues radially inward between the
castings 17, 22, although its width is diminished
because it is closer to the center of the mill, and its
depth is commensurately increased by the height of web
22b so that the volume flow of the slurry or comminuted
ore is not reduced.
With reference to Figures 1-3, the upright web
22b of casting 22 has diverging sides where it underlies
the cap casting 18. Cap casting 18 itself comprises a
flat but relatively thick base 18a and an upright thick
rib 18b. Mounting bolt openings 18c are formed in
alignment with the remaining mounting openings 22c, and
the assembly is bolted to the endplate 13 as described
above.
The channel 26 at the point shown in Figure 3
has a further reduced width and a slightly greater depth
with slightly rounded sides.
The discharge castings 19 are shown in Figures
1-2 and 6-11. With reference to Figure 6, each of the
discharge castings 19 generally takes the form of a
truncated triangle, having straight converging sides and
arcuate upper and lower edges. As pointed out above,
the castings together define an annular array occupying
1268750
g
the area between the retainer ring 15 and the upper edge
of castings 18 and 22.
With reference to Figures 8-11, it will be
seen that the discharge casting 19 comprises a base l9a
that is generally flat and relatively thick at the lower
end of the casting (the base of the truncated triangle),
and which diminishes in width as it approaches the upper
portions oE the casting due to the converging sides of
the triangular configuration, and which also diminishes
in thickness toward the upper portions of the casting
(see Figures 7, 10 and 11).
Casting 19 further comprises a top or outer
plate 19b that also takes the form of a truncated
triangle, although it is less truncated due to its
greater length. The top plate has a first portion that
is generally flat and disposed in substantially parallel
overlying relation to the base plate l9a. A second por-
tion of the top plate l9b extends longitudinally beyond
the base l9a and curves arcuately inward toward the
plane of the base plate l9a and toward the axial
discharge within the hollow trunnion 12 (Figure 2).
Figures 2 and 7 also show that the top plate 19b is
longer than the base plate l9a to establish the
necessary curvature to channel the comminuted output
from radially inward to axially outward flow.
The first portion of top plate l9b is substan-
tially the same thickness over its length, although it
is somewhat thicker at the inlet end. Also, as shown in
Figures 7 and 8, it has a relatively thick rib l9c along
its lower edge that supports and carries a lifting hook
l9d. In the arcuate second portion of top plate l9b,
another rib l9e of somewhat greater length but smaller
in cross sectional size carries a lifting hook l9f.
Further, the second portion gradually increases in
thickness through its curvature, as the sides converge.
l~ti8~75()
-10-
With reference to Figures 6 and 7, the top
plate l9b terminates at its upper end in an upwardly
projecting flange or mounting ear 19g that is configured
to receive the retainer ring 15, and includes a bolt
hole l9h. As shown in Figures 1 and 2, the retainer
ring 15 fits over the ears l9g, and a plurality of nut
and bolt assemblies 27 mechanically secure these com-
ponents together.
With reference to Figures 6 and 8-11, the base
plate l9a and top plate 19b are interconnec-ted by a
single centrally disposed upstanding web l9i, and the
cross section of cone discharge casting 19 thus takes
the form of an I-beam.
~djacent discharge cone castings 19 define a
continuation of the channel 25, and as best shown in
Figure 2, the channel 25 within casting 19 is initially
directed radially inward of the rotary mill (generally
upward as viewed in Figure 2), then sweeping into an
axial direction within the hollow trunnion 12 as a
result of curvature of the top plate l9b. This cur-
vature is arcuate and smooth to minimize the abrasive
force of the discharged slurry or dry material. It will
also be noticed in Figures 8-11 that the regions of con-
nection of the base plate l9a and top plate l9b with the
upstanding web l9i are in all cases smooth and con-
toured, as indicated by the filets l9j, l9k.
Two mounting holes 191 are formed directly
through the web l9i in alignment with holes in the mill
endplate 13 to receive mounting bolts. Directly
bolting the castings 19 to the endplate 13 positively
secures them during all phases of operation, avoiding
problems of shifting encountered with prior art
assemblies.
1~8750
It is oE essential importance that the dis-
charge cone casting 19 is integrally formed as a one-
piece casting, obviating the existence of seams or
joints at critical points which, in prior art structures,
abrade easily and wear much more quickly. The filets
l9j, l9k assist in this regard, exposing only rounded
corner surfaces to the slurry, and avoiding the high
abrasion and wear encountered with prior art castings.
Also important is the recognition of potential
wear areas within the casting 19, and providing thicker
walls for more material in such areas so that wear of
the casting is balanced and uniform throughout. Such
areas include the filets l9j, l9k, and the thicker por-
tions of the base plate l9a and top plate l9b as
described above.
The lifting hooks l9d, l9f may be used singly
or together in removing or installing the castings 19.
Figures 13 and 14 disclose an alternate form
of the casting 19, in which the curved portion of the
top plate l9b has an arcuate rib l9e' from which an ear
l9g' projects upwardly with a mounting bolt opening l9h'
formed therein. The location of the ear l9g' requires a
retainer ring 15 of greater diameter, but the ear l9g'
and bolt opening l9h' also serve as a lifting hook, thus
obviating the need for two lifting hooks as shown in the
primary embodiment.
Because the casting 19 has no joints, it
inherently resists abrasive wear by the comminuted
material and lasts longer. The use of filets where
joints exist in prior art castings further reduce wear,
and the thickened portions in high wear areas result in
balanced and uniform overall wear of the casting. The
single, centrally located upstanding web receives
mounting bolt holes for mounting the casting directly to
lZ687~jO
-12-
the mill end firmly and securely, obviating the problems
of shifting with prior art structures.
The integral cone discharge casting is easier
to remove and install than the prior art structures
because it is more easily handled and does not require
assembly of multiple components and alignment. It lasts
longer, requires less maintenance, decreases replacement
time and leads to less mill downtime and reduced mill
maintenance costs.