Note: Descriptions are shown in the official language in which they were submitted.
Z0~7
BAC~GROUND OF TIIE INVENTION
This invention relates to crushers, to primary crusher~, and to
jaw crushers or jaw breakers for crushing bulk materials such as rock and
ores. More specifically, the invention deals with an impro~ed jaw plate
structure for use in the opposed, coacting jaws of jaw crushers such as those
of the overhead eccentric or single toggle type or the Blake type.
The pair of opposed jaw plates of a jaw crusher are usually pro-
vided with corrugated crushing surace so that the bulk material fed may
be readily crushed therebetween. The ridges of the corrugated crushing
surfaces are, of course, subject tG more rapid wear than their furrows or
grooves in the case where the jaw plates are of homogeneous ~aterial. As
a consequence, the crushing surfaces of such jaw plates readily become flat.
This is undesirable since the crushing performance of the jaw crusher
generally declines with the progress of the flattening of the crushing
surfaces, until the particle size of the product becomes far greater than
the setting.
The jaw plates with their corruga~ed crushing surfaces have
customarily been cast rom such matcrials as high manganese cast steel,
low-alloy cast steel, and high chromium cast irons. Of these materials,
high manganese cast steel and low-alloy cast steel are more ductile than
high chromium cast iron and thereore comparatively immune to fracture but
are rather unsatisfactory in wear resistance. High chromium cast iron , on
the other hand, is more wear-resistant than high manganese cast steel or
low-alloy cast steel but, at the same time, is more brittle and therefore
more vulnerable to fracture.
In view of the above explained properties of the listed steel
materials, a proposal has been made in Japanese Utility Model Application
Laid Open No. 48-1~1260 ~101260/1973) to provide a jaw plate comprising a
base which is cast from high manganese cast steel or low-alloy cast steel,
and which has a corrugated crushing surface, and a multiplicity of blocks
of high chromium cast iron which are embedded in the ridges of the crushing
surface of the base. According to this known jaw plate structure, the ridges
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of the corrugated crushing surface is more wear resistant than its furrows,
so that the difference in height between thc ridges and furrows can be
maintained for a greater period of time than with the jaw plates of homog-
eneous material.
A problem has been encountercd, howevcr, in the dimensioning of
the jaw plates according to the above mentioned Japanese utility model
application. Since jaw crushers in general are required to handle materials
of widely varying hardness and other properties, the dimensions of the jaw
plates ~i.e., those of the bases and the blocks) have been determined on a
purely empirical basis. The performance and durability of the jaw plates
have therefore been not truly satisfactory.
SUMMARY OF T~E INVENTION
It is an object of this invention to improve the crushing per-
formance of the jaw plates of the type disclosed in the aforementioned
Japanese utility model application.
Another object of the invention is to increase the useful life
of the jaw plates of the above specified type.
The invention is based upon the discovery that the best possible
crushing performance and the longest possible service life can be derived
from a jaw plate of the type u~der conside~ation only when the latter is
manufactured to some pertinent dimensional specifications. Thus J in
accordance with the invention, such pertinent dimensions of the jaw plate
are specified in relation to the pitch of the corrugations of its crushing
surface. The jaw plate of this invention has the distinct advantage that
the ridges and furrows of its crushing surface are worn at approximately
the same rate. This means that the desired diference in height between
the ridges and furrows of the crushing surface is maintained for an ex-
tended length of time, so that the performance of the jaw plate does not
deterioratewith the progress of its wear.
According to the present invention, there is provided a jaw plate
structure for use in the opposed, coacting jaws of a jaw crusher, compris-
ing a base of relatively ductile material having a crushing surface which
lV91207
is corrugated to p~ovido alt~rnating ridges and furrows at a preselected
pitch, therc being a series of recesses of generally rectangular shape in
the crushing surface of tho base disposed along each ridge thereon, each
recess having a width and a length each ranging from about 0.2 to about 0.8
times the pitch of the crushing surface corrugations, each series of recesses
having spacing gaps therebetween each ranging from about 0.05 to about 0.50
times the pitch of the crushing surface corrugations, a plurality of blocks
made from more wear-resistant material than the base and fitted in respective
recesses in the crushing surface of the base, each block having an exposed
surface shaped to conform to the shape of each ridge of the crushing surface
and having a portion projecting beyond both lateral edges of the base bound-
ing the open end o each recess, the projecting portion of each block having
a height ranging from about 0.3 to about 1.0 times the pitch of the crushing
surface corrugations, and means for securing the blocks to the base.
The above and other objects, features and advantages of this in-
vention and the manner of atta.ining them will become more readily apparent,
and the invention itself will best be understood, from the following descrip-
tion of preferred embodiments of the invention, which is to be read in
connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a side elevation, in vertical section, schematically
illustrating an example of a jaw crusher having jaw plates which can be
constructed in accordance with the present invention;
Fig. 2 is a perspective view of the jaw plate structure embodying
the principles of the invention;
Fig. 3 is a relatively enlarged, fragmentary plan view of the jaw
plate structure of Fig. 2;
Fig. 4 is a fragmentary sectional view of the jaw plate structure
taken on the line IV-IV of Pig. 3; and
Pig. 5 is a view similar to Fig. 4 but showing a modification of
the embodiment of Figs. 2, 3 and 4.
Z()7
DETAILED DESCRIP~ION
Referring in detail to the above drawings and initially to Fig. 1
thereof, there is shown a jaw crusher of the overhead eccentric or single
toggle type generally designated by reference numeral 10. The jaw crusher
10 comprises a stationary jaw 11 and a movable or "swinging" jaw 12 which
are disposed opposite to each other to define therebetween the usual crush
ing cavity having a feed inlet 13 at the top and a product outlet 14 at the
bottom. The stationary jaw 11 has a jaw plate 15 which is shown to be com-
posed of a plurality of separate sections and which is bolted or otherwise
fastened to a framel6 in vertical disposition.
The movable jaw 12 has a jaw plate 17 which is likewise shown to
be composed of a plurality of sections and which is bolted or otherwise
fastened to a j~w support 18 disposed at its lower end near the lower end
of the stationary jaw 11 and inclined away from the stationary jaw. At its
top end, ~he movable jaw support 18 is rotatably coupled via a ball bearing
19 to an eccentric shaft 20 which in turn is coupled eccentrically to a
flywheel 21 rotated by a suitable drive mechanism ~not shown~. Also in-
cluded in the jaw crusher 10 are a toggle mechanism 22 having a toggle member
23 extending between, and fitted in the bottom end of the movable jaw support
18 and a frame 24, and a spring assembly 25 comprising a coiled compression
spring 26 and a tension rod 27 for biasing the movable jaw 12 away from the
stationary jaw 11.
Thus, as the flywheel 21 is rotated by the drive mechanism, the
movable jaw 12 "swings" in a fashion peculiar to the jaw crusher and coacts
with the stationary jaw 11 to crush rock, ores or other bulk material. This
bulk material is fed into the machine through the feed inlet 13, and the
crushed product is discharged out of the product outlet 14.
The construction and operation of the overhead eccentric jaw
crusher 10 as so far described have been well known in the art, and therein
lies no feature of this invention. The invention is specifically directed
to the jaw plate structure, shown in FIG. 2 and therein generally labelled
30, that can be used as the stationary or the movable jaw plate 15 or 17 or
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as onc of the Gonstituent sectiolls of eitller jaw plate.
With reference now directed to FIGS. 2, 3 and 4, the jaw plate
structure 30 in accordance wîth this invention comprises a baso 31 and a
plurality of multiplicity of substantially rectangular blocks 32 of wear-
resistant material received in respective recesses 33 formed in the base.
Preferably cast from such comparatively ductile material as high manganese
cast steel or low-alloy cast steel and heat-treated, the base 31 has a
crushing surface 34 which is corrugated to form alternating curved ridges
35 and furrows 36. The recesses 33 of generally rectangular shape are
formed in the crushing surface 34 of the base 31 so as to be disposed along
the ridges 35 thereon.
Although the recesses 33 are shown to be aligned in both of the
directions parallel and transverse to the corrugations 35 and 36 of the
crushing surface 34, the recesses may be arranged in a staggered or zigzag
fashion in the transverse direction. It is of absolute necessity, however,
that the recesses 33 be aligned along each ridge 35 of the crushing surface
34.
The blocks 32 fitted into the recesses 33 should be made of more
wear-resistant material than the base 31, such as, preferably, high chromium
cast iron, which may be heat-treated as required. As will be best seen from
FIG. 4, each block 32 has an exposed surface 37 which is curved to conform
to the shape of each ridge 35 of the crushing surface 34, so that the ridges
are formed by both the base and the blocks.
The base 31 and the blocks 32, if they are casting as aforesaid,
are finished by grinding, and each block is fitted into one of the recesses
33 in the base with constant clearance C around the block. The blocks 32
are secured to the base 31, for example, by means of a suitable synthetic
resin adhesive, indicated at 38 in FIG. 4, which is filled in the gaps there-
between.
Shown at 39 FIGS. 3 and 4 are grooves o constant depth formed in
the rear surface 40 of the base 31 in parallel spaced relationship to each
other. These grooves are disposed substantially in register with the
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furrows 36 of the crushi~g surface 34 and are intendod for use i~ mounting
the jaw plate structure 30 in position on the crusher 10.
In accordance with this invention, some pertinent dimensions of
the jaw plate structure 30 of the above described configuration are specified
as follows in relation to the pitch P (FIG. 4) of the corrugations 35 and
36 of the crushing surface 34 in order to derive the best possible crushing
performance and enduring ~uality thererom. The actual length of the pitch P
of the crushing surface corrugations is subject to change depending upon the
size of the feed material and of the p~ocessed product. Roughly speaking,
however, this pitch can be in the range of 200 through 250 millimeters for
coarse crushing, of 90 through 200 millimeters for intermediate crushingJ
and of 40 through 90 millimeters for fine crushing.
The width W and the length L of each recess 33 in the base 31
each range from about 0.2 to about 0.8 times the pitch P. The spacing gap
S between any two adjacent recesses 33 of each series ranges rom about 0.05
to about 0.50 times the pitch P. The height H of the portion 41 of each
block 32 projecting beyond the opposite lateral edges ~2 of the base 31 bound-
ing the open end of each recess 33 ranges rom about 0.3 to about 1.0 times
the pitch P.
Furthermore, the depth D of each recess 33 ~as measured from the
lateral edges 42 down to the bottom of the recess) preferably ranges from
about 0.1 to about 0.8 times the pitch P. The thickness T of the portion 43
of the base 31 lying between the recesses 33 and the grooves 39 ranges from
about 0.03 to about 0.50 times the pitch P. The clearance C with which each
block 32 is fitted in one of the recesses 33 ranges from about 0.02 to about
0.10 times the pitch P. Although the dimensions of each block 32 are not
specifically set forth except for the height H of its portion 41, the block
dimensions can be easily computed from the above speciied dimensions of each
recess 33 and clearance C.
The width W of each recess 33 is set in the range of from about 0~2
to about 0.8 times the pitch P because, at widths less than about 0.2 times
the pitch P, the corresponding width of each block 32 would be so small that
lt~91207
the furrow portions of the base 31 would suffer rapid wcar, resulting in the
excessive prot~usion of the blocks 32 out of the crushing surface 34, es-
pecially in the case of jaw plates designed for fine crushing. Such protrud-
ing blocks would easily fracture, and the performance and durability of the
jaw plates would be materially reduced. If the width W of each recess 33
were more than about 0.8 times the pitch P, on th~ othor hand, then the
corresponding width of the furrow portions of the base 31 would be so reduced
that the desired difference in height between the ridges 35 and furrows 36
of the crushing surface 34 would not be maintained for any extended length
of time.
The length L of each recess 33 is also set in the range of from
about 0.2 to about 0.8 times the pitch P. This is because, if the recess
length L were less than about 0.2 times the pitch P, the corresponding length
of each block 32 would be so small that an unnecessarily large number of such
blocks would have to bc embedded in each ridge 35 of the crushing surface 34,
thereby causing an increase in the manufacturing cost of the jaw plate.
Alternatively, such reduction in the length L of each recess 33 might result
in a corresponding increase in the spacing gap S between the recesses of each
series. In this case, the base portions lying between the recesses of each
series would suffer rapid wear, again resulting in the excessive protrusion
of the blocks 32 out of the c~ushing surface 34, and the worn base portions
would form pockets in which the material would easily to be caught while being
crushed. If the recess length L were more than about 0.8 times the pitch P,
on the other hand, then the blocks 32 of correspondingly increased length
would be vulnerable to fracture.
The spacing gap S between any two adjacent ones of the recesses 33
of each series is speciied as being in the range of from about 0.05 to about
0.50 times the pitch P. The reason for this is that, should the spacing gap
S be less than about 0.05 times the pitch P, the molten metal would not flow
smoothly in the mold during the casing of the jaw plate base 31, resulting in
the production of defective articles. The spacing gap S of more than about
0.50 times the pitch P is also undesirable for the reasons set forth already
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in conjunction with the length L of each recess 33.
The height 11 of the projecting portion ~1 of each block 32 is set
in ~he range of from about 0.3 to about 1.0 times the pitch P. If the height
H were less than about 0.3 times the pitch P, there would not be a suffici-
ent difference in height between the ridges 35 and furrows 36 of the crush-
ing surface 34, resulting in poor crushing performance. If the height H
were more than about 1.0 times the pitch P, on the other hand, then there
would be too great a difference in height between the ridges and furrows of
the crushing surface to cause smooth flow of the material down ~he crushing
cavity of the jaw crusher. The material might then be scattered about while
being crushed, and the blocks 32 would be vulnerable to fracture or damage.
The depth D of each recess 33 is specified as ranging from about
0.1 to about 0.8 times the pitch P. If the depth D were less than about
0.1 times the pitch P, the blocks 32 fitted in the recesses 33 would be of
such small thickness that they would be susceptible to fracture or damage
and might even be thrown out of the recesses in use. If the depth D were
more than about 0.8 times the pitch P, on the other hand, then unnecessarily
large amounts of materials would have to be used for the manufacture of the
base 31 and the blocks 32.
The thickness T of the base portion 43 between the recesses 33 and
the grooves 39 is set in the range of from about 0.03 to about 0.50 times
the pitch P. If the thickness T were less than about 0.03 times the pitch
P, the base 31 would be difficult to manufacture by casting and might be
fractured in use. If the thickness T were more than about 0.5 times the
pitch P, on the other hand, then an unnecessarily large amount of material
would be required for the manufacture of the base 31.
The clearance C with which each block 32 is fitted in the respect- ;
i~e recess 33 is set in the range of from about 0.02 to about 0.10 times the
pitch P. If the clearance C were less than about 0.02 times the pitch P,
the amount of ~n adhesive filled into the clear space would be insufficient
to securely retain each block 32 in the recess 33. On the contrary, if the
clearance C were more than about 0.1 times the pitch P, the amount of an
_g
lt~9~Z~7
adhesive filled into the clear space would bc too much to securely retain
each block in the recess. In either case, therefore, the blocks might be
dislodged out of the recesses in use.
Having thus set forth the grounds on which are based thc dimension-
al specifications of the jaw plate structure 30 in accordance with this in-
vention, it is clear that the jaw plate structure is well calculated to
attain the above stated objectives. In order to demonstrate this fact,
several different pairs of jaw plates were manufactured in accordance with
the teachings of this invention and wore put to practical tests as to their
crushing performance and durability. The test results were further compared
against the results of similar tests conducted on prior art pairs of jaw
plates.
For these tests, four sample pairs o jaw plates I, II, III and IV
were manufactured in accordance with ~he invention, with the respective sets
of dimensions specified in the table below, I and II being intended for fine
crushing and III and IV for coarse crushing. Also, two prior art pairs of
jaw plates V ~for fine crushing) and VI ~for coarse crushing) were employed
which were both cast solely from high manganese steel, with corrugations on
their crushing surfaces similar to the corrugations on the jaw plates of this
invention. The difference in height between the ridges and furrows of the
crushing suraces was 25 millimeters in the prior art jaw plates V and 60
millimeters in the prior art jaw plates VI. Mounted on one and the same jaw
crusher, the pairs of jaw plates of the invention and the prior art were
used for ore crushing under the same working conditions to determine their
per-hour capacities and wear ratios between the ridges and furrows of the
crushing surfaces. The results are tabulated in the following table.
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_ ~
~d h ~ ~ ~ _~ ~ ~
h ~ ,, .. .. .. .. ..
Cd 3 ~: u~ ~ )
3 ~i _
:5
U~ o o Oo
~ O ~ ~ ~ U~ U~ ~ O
h ~ Il~ ~C) Ll~ ~:
h~,
_ ~ o : : : ~ '
O U~ O o . .
3 ~ ~ O) N
. ~ .. .
~ 00 0 o~ O . .
~ ~ _I N t~ ~ .
.~ .. ., .
U~ O L~ N N . ~:
.~ . `' '''
O 0 00 ~ . .
~-1 ~ ~ ~0 ~C)
_ . .
N t~ O O . .
3 N ~) O N
_
O O O O O O
~ t'~ Lt~ ~ N ~ 00
l _ _
4 bl~ b~
a~
h .S7-1 .S
~> u
:~ h ~ h~) ~ U. ~ O
__ ....................................... _
. .,~
~ ~ ~ ~ S~ ~
,,
_
()7
It will be readily seen from the above table that the jaw plates
constructed in accordance with this invention serve to materially increase
the capacity of jaw crushers. Moreover, th0 ridges and furrows of the in-
ventive jaw plates are worn at a substantially even ratio; indeed, in the
inventive jaw plates designed for coarse crushing, hardly any difference
exists in the rates of wear of the ridges and furrows. This is in marked
contrast to the extremely uneven wear of the ridges and urrows of the prior
art jaw plates. It is therefore apparent that the useful life of the in-
ventive jaw plates is significantly longer than that of the prior art.
In FIG. 5 is shown a slight modification of the above described
jaw plate structure 30, in which modification each block 32a of wear-resistant
material has a plurality of grooves 45 formed in its lateral surfaces in
parallel spaced relationship to each other and in parallel relationship to
the plane of the jaw plate structure. These grooves are intended to receive
the synthetic resin adhesive 38 as the latter is filled into the gaps be-
tween each block 32a and the surrounding recess walls of the base 31. In
this manner the blocks 32a will be retained in the respective recesses 33
still more positively than the blocks 32 having no such grooves. It is to
be understood, however, that the illustrated grooves 45 are by way of ex-
ample only and can be replaced by other depressions of any desired shape or
arrangement.
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