Abstrict A rock crusher such as a cone or jaw crusher incorporates hardened
tapered inserts in the manganese or other wear liner of at least
one of its crushing elements. The inserts extend outwardly from
the crushing surface of the crushing element towards the facing
crushing surface so as, in use, to act as pick axes that shatter
rock primarily by impact rather than pulverizing the rock by compression.
The inserts are fixed in a heat treated manganese wear liner either
by bonding or by press-fitting. The inserts substantially improve
the life of the wear liner and, unexpectedly, 1) produce product
of a highly uniform gradation in the desired ranges, 2) consistently
produce product with a very high cubicity, 3) dramatically reduce
the crusher's power requirements, and 4) significantly increase
the crusher's capacity.
Claims We claim:
1. A rock crusher comprising:
first and second crushing means for crushing rock, said first crushing
means being movable relative to said second crushing means, wherein
cavities exist within at least one of said first and second crushing
means; and a base, a wear liner detachably mounted on said base
and presenting one of said crushing means which faces a crushing
surface of the other crushing means, and
insert means of a tungsten carbide/cobalt material inserted within
said cavities and extending outwardly from at least one of said
first and second crushing means and facing the other of said first
and second crushing means for impacting and fracturing rock upon
operation of said crusher, wherein said insert means exhibits a
high resistance to wear and a high resistance to impact when compared
to hardened steel.
2. A jaw crusher comprising:
two opposed crushing elements configured to crush to crush rock
therebetween upon pivoting motion of one of said crushing elements,
at least one of said crushing elements including
(1) a base,
(2) a wear liner detachably mounted on said base and presenting
a crushing surface which faces a crushing surface of the other crushing
element, said crushing surface of said wear liner having a plurality
of cavities formed therein, and
(3) a plurality of inserts fixed in said cavities of said wear
liner and extending outwardly from said crushing surface of said
wear liner towards the crushing surface of the other crushing element
so as to impact and fracture rocks upon operation of said jaw crusher.
3. The crusher as defined in claim 2 wherein each of said inserts
is formed from a material which exhibits a high resistance to wear
and a high resistance to impact when compared to hardened steel.
4. The crusher as defined in claim 3 wherein each of said inserts
is formed from a tungsten carbide/cobalt material.
5. The crusher as defined in claim 2 wherein said wear liner is
generally rectangular in shape so as to have an upper end, a lower
end, and opposed side edges, and wherein said inserts are arranged
in straight rows extending from said upper end to said lower end.
6. The crusher as defined in claim 5 wherein the inserts of each
said row are spaced non-uniformly so that the spacing between inserts
is smaller near said lower end of said wear liner than near a central
portion of said wear liner.
7. A crusher for crushing rock, said crusher comprising:
first and second opposed dies, at least one of which is movable
relative to the other to crush rock therebetween, wherein
at least one of said dies includes a base and a manganese wear
liner detachably mounted on said base and presents a crushing surface
which faces a crushing surface of the other die, wherein
said crushing surface of said wear liner has a plurality of cavities
cast therein, each of said cavities including a side wall extending
inwardly from the crushing surface of said wear liner and terminating
at an inner wall, wherein
a plurality of inserts are fixed in said cavities, each of said
inserts 1) extending outwardly from said crushing surface of said
wear liner and terminating in a tapered crushing tip which faces
the crushing surface of the other die so as to impact and fracture
rock upon operation of said crusher, and 2) extending inwardly from
said crushing surface of said wear liner towards said inner wall
of the corresponding cavity, and wherein
each of said inserts is formed from a tungsten carbide/cobalt material.
8. A cone crusher comprising:
two opposed crushing elements including a stationary bowl and a
head rotatable eccentrically within said bowl to crush rock therebetween,
at least one of said crushing elements including
(1) a manganese wear liner mounted on at least a portion of said
at least one crushing element presenting a crushing surface which
faces a crushing surface of the other crushing element, said crushing
surface having a plurality of cavities cast therein, and
(2) a plurality of inserts press-fit in said cavities and extending
from said crushing surface outwardly and towards a crushing surface
of the other crushing element so as to impact and fracture rock
upon operation of said gyratory crusher.
9. The cone crusher of claim 8 wherein each of said inserts is
formed from a material which exhibits a high resistance to wear
and a high resistance to impact when compared to hardened steel.
10. A method of crushing rock comprising:
orientating a first crushing element opposite a second crushing
element to form a gap therebetween, wherein said first and second
crushing elements include crushing surfaces formed from manganese
wear liners, wherein said crushing surface of at least one of said
first and second crushing elements includes a plurality of inserts
that extends outwardly and towards the other of said first and second
crushing elements, wherein said inserts exhibit a high resistance
to wear and a high resistance to impact when compared to hardened
steel;
placing rock into said gap; and
moving at least one of said crushing elements relative to the other
of said crushing elements to a position in which said inserts impact
and fracture rock in said gap.
11. The method of claim 10 wherein each of said first and second
crushing elements comprises a respective die, and wherein the moving
step comprises pivoting at least one of said first and second dies
relative towards the other of said dies to crush rock in said gap.
12. The method of claim 10 wherein said first crushing element
comprises a stationary bowl and said second crushing element comprises
a rotatable head, and wherein the moving step further comprises
rotating said head eccentrically within said bowl to crush rock
in said gap.
13. The method of claim 10 wherein each of said inserts is formed
from a tungsten carbide/cobalt material.
Description BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to rock crushers such as cone or jaw crushers
and, more particularly, relates to a rock crusher having inserts
disposed on at least one crushing surface thereof for enhanced crushing
action, enhanced wear resistance, enhanced capacity, and reduced
power requirements. The invention additionally relates to a method
of fabricating a wear liner having such inserts and to an improved
method of crushing rock.
2. Discussion of the Related Art
Rock crushers have been used for centuries in quarry operations
and the like to break large pieces of material, such as rock, stone
and the like (hereinafter "rock"), into smaller pieces
more suitable for applications such as road paving. There are many
types of rock crushers including: cone crushers (also known as gyratory
crushers), jaw crushers, impactors, hammermills, and pulverizers
to name a few.
Cone or gyratory crushers include an eccentrically gyratory conical
head, an opposed bowl, and a crushing cavity or crushing chamber
formed between the head and the bowl. Rock that falls into the crushing
chamber is crushed by compression to a smaller size generally consistent
with the size of the gap in the crushing cavity at the point at
which the rock is struck. The average size of the stone formed from
the crushing operation can be changed by adjusting the minimum gap
between the bowl and the head, which minimum gap is known in the
art as "the closed side setting." For a more detailed
description of the operation of a cone crusher, reference may be
had to U.S. Pat. No. 3750967 to DeDiemar et al., entitled "Gyratory
Crusher Having Interchangeable Head Mantles," issued Aug. 7
1973 and assigned to an assignee common with the present invention
(hereinafter incorporated by reference).
A jaw crusher includes opposed generally rectangular dies, one
of which is swingably movable relatively toward and away from the
other to crush rock therebetween. For a more detailed description
of the operation of a jaw crusher, see U.S. Pat. No. 3804345 to
DeDiemer, entitled "Jaw Crusher Die Mounting," issued
Apr. 16 1979 and assigned to an assignee common with the present
invention (hereinafter incorporated by reference).
The crushing surfaces of both cone crushers and jaw crushers suffer
from severe and relatively rapid wear due to abrasive contact with
the stone being crushed. In order to ameliorate this wear, both
cone crushers and jaw crushers typically utilize as one and usually
both crushing surfaces a replaceable hardened, wear-resistant manganese
wear liner. A jaw crusher incorporating replaceable manganese wear
liners is disclosed, for example, in U.S. Pat. No. 2828925 to
Rumpel. A gyratory or cone crusher incorporating replaceable manganese
wear liners is disclosed, for example, in the DeDiemer '967 patent.
While manganese wear liners serve to increase the useful life of
the crushing elements of a crusher, they are not a cure-all for
all of a crusher's problems.
For instance, manganese wear liners still exhibit relatively rapid
and uneven wear, particularly when subject to contact with an abrasive
material such as sandstone. They therefore must be replaced relatively
frequently--on the order of every 10 days to 3 weeks in the case
of a cone crusher crushing sandstone. The manganese wear liners
are relatively expensive, and their replacement requires several
hours of down time. Frequent replacements of wear liners therefore
can be quite costly.
Another problem that is associated with conventional crushers and
that is not solved by traditional wear liners is that their crushing
action does not consistently produce a product of sufficiently high
cubicity. Cubicity is defined as the ratio of length to width to
thickness of a sample particle. For instance, a particle having
a length of 4", a width of 2",
and a thickness of 1" has a 4:2:1 cubicity ratio. Many industries,
and particularly the paving industry, increasingly are requiring
the production of gravel or other paving materials of consistent,
relatively high cubicity. This need is particularly evident in the
case of materials designed for use in so-called "super paving"
projects in which state highway departments require that no more
than 15% of the crushed rock used in the paving materials may have
a cubicity ratio of greater than 3:1:1. Operators of most cone and
jaw crushers (the crushers most commonly used to produce materials
for the paving industry) sometimes find it exceedingly difficult
to meet these cubicity requirements, particularly if the materials
being crushed are shale-like or otherwise tend to shatter into long,
flat pieces. Crushed product failing to meet the cubicity requirements
cannot be screened or otherwise improved to meet these requirements
and hence must be rejected. As a result, it is not uncommon for
a state highway department to reject several hundred thousand tons
of rock produced for use in a super paving project.
The industry has recently addressed the cubicity problem and solved
it to a limited extent by increasing the stroke and speed of crushing
machines. For instance, crushed rock produced by the Telsmith H-Series
crusher exhibits improved cubicity when compared to materials produced
by other, earlier crushers. However, meeting cubicity requirements
for super paving projects is often difficult even with these modern
crushers, particularly when the rock is inherently relatively non-cubic,
i.e., it tends to break into long, flat pieces.
Proposals have been made to incorporate inserts into a crushing
surface of a crusher. For instance, U.S. Pat. No. 201187 to Markel
and U.S. Pat. No. 273477 to Dodge both disclose jaw crushers having
replaceable pins or points that are designed to absorb the abrasive
action of the stone being crushed and hence to form the wear surface
of the crusher. Replacement of these pins or points apparently was
considered to be a more attractive option than replacing an entire
die or even an entire liner of a crusher. U.S. Pat. No. 883619
to Canda similarly discloses the use of hardened steel ribs which
are connected to the dies of the jaws and which form the wear elements
of the crusher.
Proposals have also been made to insert elements into the crushing
surface of a jaw crusher to enhance its crushing ability. For instance,
U.S. Pat. No. 1513855 to Phelps proposes the incorporation of
differently-sized crushing and cutting teeth into the facing dies
to give the machine increased capacity. Similarly, U.S. Pat. No.
3241777 to Kuntz proposes the attachment of hardened steel balls
to the opposed dies of a jaw crusher to act as a wear surface. The
balls are independently and separately mounted so that the resistance
to abrasion of the cutting surface can be varied as desired to provide
an optimum crushing surface for a particular material or operation.
None of the prior art patents discussed above disclose the combination
of protruding inserts and a manganese wear liner in a jaw or cone
crusher. Moreover, none of these patents discuss cubicity.
What is needed therefore are a method and apparatus which add life
to the crushing surfaces of a crusher, which increase the cubicity
of the crushed material, and which increase the efficiency of the
crusher.
SUMMARY OF THE INVENTION
One aspect of the present invention is to provide a rock crusher
having hardened inserts that are mounted in cavities formed in the
crushing surface of a wear liner thereof and that extend from the
crushing surface and towards the crushing surface of an opposed
crushing element. The inserts impact the rock so as to crush the
rock by shattering rather than by compression and hence improve
the crusher's operation.
The hardened inserts exhibit a greater resistance to wear and to
impact than hardened steel and preferably are formed from a wear
resistant and impact resistant tungsten carbide cobalt such as 2M12
grade tungsten carbide/cobalt. The inserts increase the life of
the liner substantially while unexpectedly and dramatically improving
the gradation and cubicity of the product. The inserts also increase
the crusher's capacity while reducing its power requirements. Moreover
(and unexpectedly), the inserts retain their superior crushing characteristics
for the life of the liner.
The inserts are preferably provided in the liner(s) of either a
cone crusher or a jaw crusher and are arranged in a pattern having
a configuration and density designed to optimize the desired crushing
effect. For instance, in the case of cone crushers, the inserts
are provided in at least two (and preferably three or more) concentric
circular rows extending around a lower peripheral portion of the
crushing head such that the inserts of each row are spaced from
one another by about 1.25" and such that the rows of inserts
are spaced from one another by about 1.25". In the case of
jaw crushers, the inserts are arranged in straight rows extending
from the upper end of the wear liner to the lower end such that
the inserts of each row are spaced non-uniformly, with the spacing
between inserts being smaller near the ends of the liner than near
a central portion of the liner.
The shape of each insert is preferably selected to strike a balance
between its crushing ability and its wear resistance. Preferably,
the tip of each insert has 1) an inner, essentially linearly-tapered
portion having generally the shape of a truncated elliptic cone
and 2) an outer portion having generally the shape of an elliptic
paraboloid.
Another object of the invention is to provide a method of manufacturing
a wear liner for a rock crusher. Manufacturing is complicated by
the fact that heat-treated manganese is nearly impossible to drill.
The invention avoids the need to drill manganese by casting the
cavities in the manganese wear liner during the liner's fabrication
and mounting the inserts in the cavities of finished wear liner.
It has been found, unexpectedly, that relatively tight tolerances
in cavity diameter can be maintained during the manganese casting
and heat treating process so that an insert can be press-fit into
the cavity of the finished liner, thereby significantly facilitating
insert mounting.
Yet another object of the invention is to provide an improved method
of crushing rock.
This object is achieved by crushing the rock in a crusher such
as a cone crusher or jaw crusher by fracturing the rock via impact
with inserts mounted in a crushing surface of at least one of the
crushing elements of the crusher. The inserts have tips which extend
outwardly from the crushing surface so as to fracture rock upon
impact therewith. Crushed rock produced by a crusher using these
inserts exhibits extremely uniform gradation and extremely high
cubicity. Moreover, the crushing process requires substantially
less power and exhibits much improved capacity compared to corresponding
processes performed by standard crushers lacking inserts.
Other objects, features, and advantages of the invention will become
more apparent to those skilled in the art from the following detailed
description and the accompanying drawings. It should be understood,
however, that the detailed description and specific examples, while
indicating preferred embodiments of the present invention, are given
by way of illustration and not of limitation. Many changes and modifications
may be made within the scope of the present invention without departing
from the spirit thereof, and the invention includes all such modifications
.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred exemplary embodiments of the invention are illustrated
in the accompanying drawings in which like reference numerals represent
like parts throughout, and in which:
FIG. 1 is a perspective view of a jaw crusher with parts broken
away to show the crusher's dies and inserts constructed in accordance
with a first embodiment of the invention;
FIG. 2 is an enlarged fragmentary cross sectional view of the dies
and inserts of the jaw crusher of FIG. 1 taken generally along
the line 2--2 of FIG. 1;
FIG. 3 is a sectional elevation view of a cone rock crusher employing
inserts constructed in accordance with the first embodiment of the
invention;
FIG. 4 is a top plan view of a head of the cone rock crusher of
FIG. 3;
FIG. 5 is an enlarged fragmentary sectional elevation view of the
head of the cone rock crusher of FIG. 4 taken along the line 5--5
in FIG. 4;
FIG. 6 is an enlarged fragmentary sectional view of an insert protruding
from the wear liner of the conical head shown in FIGS. 4 and 5;
FIG. 7 is a fragmentary sectional elevation view of a portion of
a cone crusher employing inserts constructed in accordance with
a second embodiment of the invention;
FIG. 8 is a sectional elevation view of a bowl of the crusher of
FIG. 7;
FIG. 9 is a top plan view of the bowl of FIGS. 7 and 8;
FIG. 10 is a top plan view of the head of the crusher of FIG. 7;
FIGS. 11 and 12 are enlarged fragmentary sectional elevation view
of a portion of a liner/insert assembly of the bowl of FIGS. 8 and
9 illustrating the assembly in an exploded view and a perspective
view, respectively;
FIG. 13 is an enlarged fragmentary sectional elevation view of
the liner of the bowl of FIG. 10 without inserts;
FIG. 14 is an enlarged fragmentary sectional elevation view of
the liner of FIG. 13 with inserts;
FIG. 15 is an enlarged fragmentary sectional elevation view of
a portion of the liner of FIGS. 13 and 14 illustrating an insert
in the liner;
FIG. 16 is an elevation view of the insert of FIG. 15;
FIG. 17 is a top plan view of the insert of FIG. 16;
FIG. 18 is a top plan view of a wear liner of a jaw crusher employing
inserts constructed in accordance with the second embodiment of
the invention;
FIG. 19 is a sectional end elevation view taken along the lines
19--19 in FIG. 18; and
FIG. 20 is a graph showing gradation curves for crushers with and
without inserts.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
1. Resume
Pursuant to a preferred embodiment of the invention, a rock crusher
such as a one or jaw crusher incorporates hardened tapered inserts
in the manganese or other wear liner of at least one of its crushing
elements. The inserts extend outwardly from the crushing surface
of the crushing element towards the facing crushing surface so as,
in use, to act as pick axes that shatter rock primarily by impact
rather than pulverizing the rock by compression. The inserts are
fixed in a heat treated manganese wear liner either by bonding or
by press-fitting. The inserts substantially improve the life of
the wear liner and, unexpectedly, 1) produce product of a highly
uniform gradation in the desired ranges, 2) consistently produce
product with a very high cubicity, 3) dramatically reduce the crusher's
power requirements, and 4) significantly increase the crusher's
capacity.
2. Construction of Crushers Incorporating Bonded Inserts
Referring more particularly to FIGS. 1-6 wherein like numbers
refer to like parts, a first embodiment of the present invention
is illustrated in which inserts 10 are held in receiving cavities
12 of a wear liner by a bonding agent 14. The inserts 10 of this
embodiment are well-suited for use in any rock crushing machines
having opposed crushing elements. For simplicity, the description
below will focus on the inserts 10 as they are made and used in
a 1) a jaw crusher 17 (FIGS. 1 and 2) and 2) a cone crusher 16 (FIGS.
3-5).
The cone crusher or gyratory crusher 16 as shown in FIG. 3 includes
an upper frame assembly 20 and a stationary lower frame assembly
22 which, in combination, enclose a gyrating conical head 23 mounted
on an eccentric shaft 56. The upper frame assembly 20 includes 1)
a bowl 21 surrounding the conical head 23 and 2) a hopper 28 that
is disposed above the bowl 21 and that has a central opening 30
which allows the entry of the rock to be crushed. A mantle, formed
from a manganese wear liner 24 is detachably mounted on the underlying
base of the conical head 23 to present a crushing surface 32. A
similar wear liner 25 covers the bowl 21 to present a mating, upper
crushing surface 34. A crushing chamber 26 is formed between the
crushing surfaces 32 and 34. This crushing chamber 26 is non-annular
due to the eccentric positioning of the crushing head 23 within
the bowl 21. The minimum width of the crushing chamber 26 (i.e.,
the minimum gap or spacing between the conical head 23 and the bowl
21) is known as the "closed side setting" and typically
varies in diameter from about.sub.-- " up to about 1"
or even wider.
Inserts 10 are mounted in either or both of the opposed crushing
surfaces 32 34 and protrude therefrom so as to extend towards the
opposed crushing surface. The inserts 10 can be mounted in any of
several patterns which cover the upper crushing surface 34 on the
cone crusher's bowl liner 24 the lower crushing surface 32 on the
cone crusher's mantle or head liner 25 or a portion or all of the
surface of both. One such pattern is illustrated in FIG. 4 and is
formed by three concentric circular rings of evenly-spaced inserts
10.
The jaw crusher 17 as shown in FIGS. 1 and 2 includes a housing
60 a swinging jaw assembly 62 mounted in the housing 60 and a
stationary jaw assembly 64 mounted in the housing 60. Dies 36 37
are mounted on facing surfaces of the jaw assemblies 62 64 respectively.
Each die 36 37 receives a replaceable manganese wear liner 39
40 having a corrugated crushing surface. The swinging jaw assembly
62 incorporates a pitman 66 mounted on the housing 60 by way of
an eccentric shaft 68. A driving sheave 70 and a flywheel 72 are
mounted on opposite ends of the shaft 68 such that, when a rotational
force is imparted to the sheave 70 by a belt (not shown), the swinging
jaw assembly 62 swings cyclically towards and away from the stationary
jaw assembly 64 to crush rock between the facing dies 36 37.
Inserts 10 are mounted in the crushing surface of one or both of
the wear liners 39 40 so as to extend towards the crushing surface
of the opposed wear liner. The inserts 10 can be arranged in various
patterns on the liner 39 or 40 of one or both of two opposed dies
36 37. In the illustrated embodiment, the inserts 10 are arranged
in straight rows extending along the peaks of the liner's corrugations.
The same inserts 10 are used in the wear liner(s) of both the cone
crusher 16 and the jaw crusher 17. The inserts 10 also operate identically
in both crushers 16 and 17. Accordingly, the inserts 10 will be
detailed only with respect to the cone crusher 16 it being understood
that the discussion applies equally to the jaw crusher 17.
The inserts 10 are made from a material having greater wear and
impact resistance than hardened steel. The preferred material is
a hard tungsten carbide material incorporating cobalt to increase
its impact resistance. The preferred material grade is known as
a 2M12 tungsten carbide/cobalt having 10.5% by weight cobalt. It
is believed that 2M1 or 2M11 product grades (having 9.5% and 11%
cobalt, respectively) also would work acceptably. It is also believed
that materials having a grade designation of RX007 or lower would
lack the desired impact resistance, while materials having a grade
designation of 2M13 or higher would lack the desired wear resistance.
It should also be noted that the inserts could be made from another
suitably hard, impact resistant, and wear-resistant material and
that, even in the case of a tungsten carbide insert, another low-stacking
fault energy metal such as nickel or chromium may be used in place
of or in addition to the cobalt.
In the embodiment illustrated in FIGS. 1-6 the carbide inserts
10 have 1) a generally cylindrical body 42 having a generally cylindrical
flange 44 and an inner end 45 and 2) an outer tip 46. The flange
44 is wider than the remainder of the body 42 as best shown in FIG.
6. Alternatively, the body 42 of the insert 10 may be any of several
shapes, including polyhedronal, frusto-conical, egg-shaped, or wedge-shaped.
The terms "flange" and "flanged" therefore are
used to describe the spreading or
expanding out of the body of the insert and the side wall of the
cavity so that the flange 44 and flanged portion 52 have a greater
cross sectional area than the adjacent areas of the cavity and insert.
The tip 46 is generally frusto-conical in shape, extends from the
end of the insert body 42 and protrudes about 0.25" beyond
the crushing surface 32 34 to form an impact point.
The cavity 12 has a shape generally corresponding to that of the
carbide insert 10. Accordingly, as seen in the embodiment shown
in FIG. 6 the cavity 12 has a peripheral side wall 50 and terminates
in an inner end wall 54. The side wall 50 has a generally cylindrical
outer portion 51 and a flanged inner portion 52 which expands radially
outwardly to generally compliment the shape of the flange 44 on
the insert 10. The inner end 45 of the insert 10 preferably abuts
the inner wall 54 of the cavity 12.
The diameter of the flange 44 on the insert 10 is roughly equal
to the diameter of the outer portion 51 of the cavity 12 so that
the insert 10 can be placed in the cavity 12 with a slight radial
clearance. The body 51 and the flanged portion 52 both have diameters
larger than the diameters of the body 42 and flange 44 of the insert
10 such that, in use, a generally annular space is formed between
the circumferential surfaces of the insert 10 and the facing peripheral
surface 50 of the cavity 12. A bonding agent 14 such as an epoxy,
fills this space to hold the insert 10 in the cavity 12. The volume
of this space should be minimized as much as possible while still
permitting insertion of the flanged insert 10 into the cavity 12
in order to maximize the strength of the bond formed by the agent
14.
The inserts 10 cannot be cast into place in the manganese liners
25 prior to heat treating because the hard inserts 10 would shatter
during the heat treating and quenching operation of the manganese.
Moreover, it is difficult or impossible to drill holes in a heat
treated manganese liner. These problems are eliminated in the present
embodiment by bonding the inserts 10 in the cavities 12 of a finished
liner. Specifically, after the wear liner has been cast with the
cavities 12 in it, heat treated, and cooled, the inserts 10 are
placed in the cavities 12 and held in position while a bonding agent
14 is injected into the cavities 12 to fill the spaces between the
inserts 10 and the peripheral surfaces of the cavities 12. Alternatively,
the bonding agent 14 may be injected into the cavities 12 and the
inserts 10 then may be placed in the cavities 12 preferably abutting
the inner walls 54 of the cavities 12. The insert's flange 44 and
the flanged portion 52 of the side wall 50 of the corresponding
cavity 12 serve to keep the insert 10 securely fastened in the wear
liner by ensuring that the bonding agent 14 works in compression
in the space "A" between the flange 44 of the insert 10
and the flanged portion 52 of the cavity 12 after it hardens.
The preferred bonding agent is a two-part epoxy known as "SMITHBOND.RTM."
and produced by Telsmith, Inc. of Mequon, Wis. However, one can
imagine several other bonding agents which have a high compressive
strength suitable for fastening the inserts 10 in the cavities 12.
3. Construction of Crushers Incorporating Press-Fit Inserts
As discussed above, tungsten carbide/cobalt inserts cannot as a
practical matter be mounted in a manganese liner prior to heat treating
because the inserts would shatter during the heat treating process.
Moreover, cavities suitable for receiving inserts cannot be drilled
into heat treated manganese liners because the heat treated manganese
is too hard. However, it has been discovered that an insert can
be press-fit into a preformed cavity of a manganese liner if 1)
the cavities are cast into the liner with a relatively high degree
of precision, and 2) the insert is fluted or otherwise shaped to
dig into the peripheral sidewalls of the cavity. Referring to FIGS.
7-19 a cone crusher and a jaw crusher now will be described incorporating
press-fit inserts 110.
Referring initially to FIGS. 7-14 a portion of a cone crusher
116 is illustrated which is identical to the cone crusher 16 of
the first embodiment except that the inserts 110 are of a different
configuration and are arranged in a different pattern than inserts
10 of FIGS. 1-6. Components of the crusher 116 that correspond to
components of the crusher 16 of the first embodiment are designated
by the same reference numerals, incremented by 100.
The crusher 116 comprises an upper frame assembly 120 and a lower
frame assembly 122 which, in combination, enclose a gyratory conical
head 123 mounted on an eccentric shaft 156 in the conventional manner.
The upper frame assembly 120 includes 1) an upper hopper 128 having
a central opening 130 and 2) a lower bowl 121 that surrounds and
opposes the conical head 123. A mantle, formed from a manganese
wear liner 124 is detachably mounted on the underlying base of
the conical head 123 to present a lower crushing surface 132. A
similar wear liner 125 covers the bowl 121 to present a mating,
upper crushing surface 134. A non-annular crushing chamber 126 having
an adjustable closed side setting is formed between the crushing
surfaces 132 and 134.
The inserts 110 can be mounted in either or both of the crusher's
opposing crushing surfaces 132 134 so as to extend from the crushing
surface 132 or 134 and towards the opposed crushing surface 134
or 132. In the illustrated embodiment, inserts 110 are provided
in both crushing surfaces 132 and 134 in a pattern designed so as
to achieve a desired crushing effect. The illustrated pattern takes
the form of three concentric circular rings of evenly-spaced inserts
110 located adjacent the bottom of the corresponding wear liner
124 or 125. Inserts of each row are spaced about 1.25" apart,
and each row is spaced about 1.25" from the adjacent row. The
pattern of the illustrated embodiment is designed to produce a high
percentage of relatively small gravel or coarse fines. This pattern
could and preferably would change depending upon the results sought.
For instance, a looser pattern (i.e., one in which the inserts are
more widely spaced) could be employed to produce higher percentages
of larger rock. Rows of inserts could also be mounted near the middle
or top of the crushing chamber 126 instead of or in addition to
one or more of the illustrated rows.
In the case of a jaw crusher, the inserts 110 can be arranged in
various patterns on one or both of the crusher's opposed wear liners.
A wear liner 140 suitable for mounting on a die 36 or 37 of the
jaw crusher 17 of FIGS. 1 and 2 is illustrated in FIGS. 18 and 19.
The wear liner 140 has an inner face 159 configured for mounting
on the die 36 or 37 and an outer, corrugated face forming the crushing
surface 160. The wear liner 140 is generally rectangular (hence
matching the shape of the die 36 or 37) and hence has an upper end
162 a lower end 164 and opposed side edges 166 and 168. The inserts
110 are mounted on the crushing surface 160 of the wear liner 140--preferably
at the peaks 170 of the corrugations as illustrated. In the illustrated
embodiment, the inserts 110 are arranged in straight rows extending
from the upper end 162 of the wear liner 140 to the lower end 164.
The inserts 110 of each row are spaced non-uniformly so that the
spacing between inserts is smaller near the ends of the wear liner
140 than near a central portion so that the spacing is at a minimum
where the crushing action is at a maximum. In the illustrated embodiment
in which the wear liner 140 has a length of 70", the inserts
110 of each row are spaced as follows: 1) the distance from the
first, bottom insert to the second insert is 2"; 2) the distance
between each of the second and third, third and fourth, and fourth
and fifth inserts is 3"; and 3) the distance between each of
the fifth and sixth and sixth and seventh inserts is 6". This
pattern is repeated at the opposite or upper end of the liner 140.
The same inserts 110 are used in the wear liner(s) 124 and 125
of the cone crusher 16 and the wear liner 140 of the jaw crusher
17. The inserts 110 also operate identically in both types of wear
liner. Accordingly, the inserts 110 will be detailed only with respect
to the wear liners 124 or 125 for the cone crusher 116 it being
understood that the discussion applies equally to the wear liner
140 for the jaw crusher 17.
The inserts 110 which are made from the same tungsten carbide/cobalt
material as the inserts 10 described above, are designed to be press-fit
into cavities 112 so that their tips extend outwardly away from
the crushing surface of the wear liner 124 or 125. Towards these
ends, the inserts 110 assume a fluted, generally cylindrical shape
having a tapered tip. More specifically, each insert 110 has a generally
cylindrical body 142 disposed within the cavity 112 and an outer
tip 146 extending outwardly from the liner's crushing surface as
seen particularly in FIGS. 15-17. The cavity 112 and insert body
142 each have a length of about 1". However, it maybe desirable
to provide a deeper cavity and correspondingly longer insert so
as to increase the effective life of the insert as the insert and
the manganese liner wear. Increasing the depth of the cavity to
2" or even 2.5" with a commensurate increase in the length
of the insert would not be out of the question.
The major portion of the body 142 (excluding the inner end 145)
is fluted to present serrations that facilitate press-fitting. Press
fitting is possible due in part to the fact that is has been discovered
that the cavities 112 can be cast into manganese liners and that
the manganese can be heat treated such that the cavities maintain
their dimensions with a relatively tight tolerance after the heat
treating and subsequent cooling processes. Nevertheless, it is impossible
to hold these tolerances perfectly during liner manufacturing. The
provision of the serrations on the body 142 facilitates the accommodation
some variations in cavity diameter. In the illustrated embodiment
in which the cavity 112 is cylindrical and is about 0.550"
wide (with a tolerance of about 0.005"), the body 142 has a
major diameter M of essentially 0.590", a root diameter R of
essentially 0.530", and a pitch diameter P of essentially 0.564"
(see FIG. 17). Enough serrations should be incorporated in the body
142 to provide sufficient contact area to hold the insert 110 in
place within the cavity 112 after press-fitting. Sixteen serrations
are provided in the illustrated embodiment.
The inner end 145 of the body 142 is tapered downwardly and inwardly
so as to facilitate insertion of the insert 110 into the corresponding
recess 112 during the fabrication process. The inner or bottom surface
148 of the insert 110 should be flat so that, after the press fitting
operation, the inner surface 148 rests firmly on the inner end 154
of the cavity 112 as best seen in FIG. 15.
While the insert 110 is designed to resist wear by abrasion so
as to increase the overall life of the liner in which it is mounted,
it is also designed to act in use like a pick-axe that shatters
rock by impact with it as opposed to merely crushing the rock by
compression. Were it not for this intended shattering effect, the
tip 146 could be squared off or even eliminated altogether. However,
in order to take advantage of the impact effect, the tip 146 is
provided with a tapered profile that is designed to strike an acceptable
balance between impact efficiency and wear resistance. The illustrated
tip 146 extends about 0.25" beyond the crushing surface 132
or 134 of the wear liner 124 or 125 and includes 1) an inner, essentially
linearly-tapered portion 156 having generally the shape of a truncated
elliptic cone and 2) an outer portion 158 having generally the shape
of an elliptic paraboloid.
The manner in which a liner/insert assembly is fabricated will
now be detailed with respect to the cone crusher 116 it being understood
that virtually the identical operation would be used to mount inserts
110 in the cavities 112 of the liner 140 of a jaw crusher.
First, the liner 124 or 125 is cast and then heat treated with
the cavities 112 formed in it. As mentioned above, it has been discovered
that the cavities can be formed with a relatively high degree of
uniformity so that the cavities of the finished liner have a generally
uniform diameter (within an acceptable tolerance) and a generally
uniform depth. The inserts 110 are then set into the cavities 112
manually so that the tapered ends 145 rest in the openings of the
cavities 112. The inserts 110 are then press-fit into the cavities
112 one at a time using a hydraulic ram that can be moved around
the periphery of the liner 124 or 125. During the pressing operation,
the flutes or serrations on each insert body 142 dig into the peripheral
wall 150 of the corresponding cavity 112 so that the insert 110
is held firmly in place within the cavity 112. The resultant retention
forces are very high. Tests have shown that few if any inserts 110
fall out of the liner 124 or 125 during crushing until the liner
has worn to the extent that the cavities 112 are entirely or nearly
entirely worn away.
4. Operation of Crusher
The basic operation of the cone crushers 16 116 is identical and
is not affected by the mounting technique for the insert 10 or 110.
That is, material falling into the crushing chamber 26 or 126 is
crushed by the cooperation of the inserts 10 or 110 on the liner
125 of the gyrating head 123 and the mating crushing surface of
the bowl liner 24 124. The addition of the inserts 10 110 extends
the "point of contact" of the crushing surfaces 32 34;
132 134 outwardly so that the compression forces of the crushing
surface are concentrated on the protruding tips 46 146 which directly
engage the rock. The inserts 10 110 thus allow the enhanced crushing
surfaces 32 34; 132 134 to provide an impact crushing action which
shatters the rock (much like the action which occurs upon impact
with a pick axe) rather than pulverizing the rock by compression.
This shattering action increases the crusher's crushing efficiency
and reduces the amount of undesirable "fines" (material
of extremely small size) typically produced by crushing surfaces
of conventional rock crushers. Similar beneficial effects are achieved
during operation of a jaw crusher 17 employing inserts 10 or 110.
Substantial testing of a cone crusher incorporating the inventive
inserts has revealed several surprising and unexpected results.
Similar results have been obtained during more limited testing of
a jaw crusher. However, because more extensive testing has been
performed to-date on cone crushers, these results and the unexpectedness
thereof will be discussed in conjunction with a cone crusher.
5. Example: Testing of a Telsmith Model 52FC Gyrasphere Crusher
Field tests of a Telsmith Model 52FC or cone crusher were conducted
both with and without inserts. This crusher included all of the
basic components discussed above in conjunction with the crushers
16 and 116. During the tests conducted with inserts, the manganese
liner of the bowl of this crusher contained inserts, while the liner
of the mantle lacked inserts. The inserts were of the "press-fit"
type discussed in Section 3 above and were arranged in the pattern
discussed in that section. Tests were run at various close side
settings both with and without inserts. Sandstone (a very abrasive
substance) was crushed during all tests discussed below. Some of
the results of these tests could be anticipated at least to some
extent. Other results were wholly unexpected. These results will
now be summarized.
a. Wear Life
As one might expect, the inserts significantly extended the life
of the wear liners so that the time between liner changes was increased.
In fact, on average, the life of the liners containing the inserts
was increased by about 100%. This increase alone might not justify
the costs of the inserts because the cost of a liner having inserts
is currently about 3 times the cost of a liner lacking inserts.
However, the manner in which this wear occurs was unexpected. More
specifically, the manganese liner wore in valleys around the inserts
so that the inserts continued to protrude from the crushing surface
of the liner as the crushing surface wore. The "pick axe"
effect of the inserts' crushing action therefore was retained as
they wore. Indeed, and unexpectedly, the tips of the inserts retained
their rounded or tapered profile as they wore so that the impact
effect was retained with a high degree. Hence, the improved crushing
capabilities (as detailed below) were retained essentially throughout
the entire life of the wear liner.
b. Gradation
Gradation is an important consideration in crusher design. Gradation
is defined by the percentage of a sample above or below a particular
size, i.e., by the percentage of a sample passing through or being
retained on a particular screen such as a 3/16" square cloth.
An ideal crusher is one
which consistently produces a high percentage of product material
of a desired diameter range. The consistency of a crusher's operation
can be monitored by comparing the gradation of incoming or feed
product with the gradation of outgoing or crushed product. As one
might expect, the gradation of crushed product varies with 1) the
gradation of the raw or feed material fed to the crusher and 2)
the closed side setting of the crusher.
During testing, the crusher was operated-both with and without
inserts at a closed side setting of.sub.-- (0.875) inches. A gradation
analysis of a sample crushed with inserts in the liner is tabulated
in Tables 1 and 2 in which Table 1 reflects the gradation analysis
for the feed or raw material to the crusher and Table 2 reflects
the gradation analysis for the product material, i.e., the crushed
rock. |