Abstrict A crusher of the type having a vertical rotary shaft which has
a horizontal rotor secured thereto at its upper end and is rotatively
mounted within the rotor frame, and mounted on the rotor is a hollow
rotary cylinder with an open top end and a closed bottom, the cylinder
having its peripheral wall formed with a number of raw material
ejection slots so as to eject therethrough by centrifugal force
the raw material to be crushed fed into it, and the rotor is further
provided with a number of striking members outside the hollow rotary
cylinder, preferably respectively pivoted to the rotor, for the
purpose of striking the raw material ejected out of the raw material
ejection slots of the hollow rotary cylinder, during the course
of the flight thereof through the space around the rotary cylinder,
whereby the raw material is crushed by the striking members.
Claims What is claimed is:
1. A crusher comprising a frame having a substantially closed hollow
cylindrical form with a raw material supply orifice being formed
in its upper wall, a vertical rotary shaft rotatively supported
within said frame below said raw material supply orifice, a horizontal
motor mounted within said frame at the upper end of said rotary
shaft for rotation in a rotational direction, a hollow rotary cylinder
having a peripheral wall mounted within said frame to the upper
surface of said rotor centrally thereof, said hollow rotary cylinder
having an outer peripheral surface spaced from the inner cylindrical
surface of said frame, being opened at its upper end below said
raw material supply orifice and having a bottom closing its bottom
end, said peripheral wall of said hollow rotary cylinder having
at least one slot for ejecting therethrough by centrifugal force
into an ejection space raw material fed onto said bottom, and at
least one main striking member mounted to said rotor outside said
hollow rotary cylinder, spaced from said outer peripheral wall of
said hollow rotary cylinder to define therebetween the cylindrical
raw material ejection space, the radial width of said ejection space
being much greater than the thickness of said peripheral wall and
having a striking surface facing towards said rotational direction
of said rotor such that said raw material ejected through said slot
impinges upon said striking surface during its movement through
said raw material ejection space.
2. A crusher as claimed in claim 1 wherein said hollow rotary cylinder
is mounted to said rotor so as to have the position of said slot
relative to said main striking member adjustable.
3. A crusher as claimed in claim 1 wherein said main striking member
is pivotably mounted to said rotor so that said striking surface
is maintained at a substantially constant angle in relation to the
impinging direction of said raw material when said main striking
member is pivoted by centrifugal force applied to its center of
gravity due to the rotation of said rotor.
4. A crusher as claimed in claim 3 wherein said constant angle
is somewhat acute when it is measured in the radial direction of
said main striking surface.
5. A crusher as claimed in claim 4 wherein said constant angle
is between 60.degree. and 85.degree..
6. A crusher as claimed in claim 3 wherein said at least one main
striking member comprises means for detachably mounting a supplemental
weight to adjust the location of said center of gravity.
7. A crusher as claimed in claim 1 wherein said rotor is additionally
provided with at least one auxiliary striking member having a striking
surface facing towards the direction of rotation of said rotor,
said at least one auxiliary striking member being located rearward
of said at least one meain striking member in relation to said direction
of rotation of said rotor.
8. A crusher as claimed in claim 7 wherein said at least one auxiliary
striking member comprises a plurality of auxiliary striking elements
each having a thin plate-like form.
9. A crusher as claimed in claim 1 further comprising a raw material
repulsion fence arranged within said frame surrounding said rotor
and spaced from the locus of rotation of said main striking member
as well as the inner wall of said frame.
10. A crusher as claimed in claim 9 wherein said raw material repulsion
fence comprises an array of bars arranged substantially vertically
with a gap being left between the respective neighbouring one of
said bars.
11. A crusher as claimed in claim 10 wherein each of said bars
has a square cross-section.
12. A crusher as claimed in claim 9 further comprising means for
maintaining the space between the inner wall of said frame and said
raw material repulsion fence under a negative pressure.
13. A crusher as claimed in claim 12 wherein said negative pressure
maintaining means comprising duct means for connecting said space
to said raw material supply orifice through said frame, said orifice
being opened in the upper wall of said frame near the opened upper
end of said hollow rotary cylinder.
14. A crusher as claimed in claim 1 7 or 9 wherein said at least
one main striking member comprises a plurality of main striking
elements put one upon another, each of said plurality of main striking
elements having a thin plate-like form.
15. A crusher comprising a frame having a substantially closed
hollow cylindrical form with a raw material supply orifice being
formed in its upper wall, a vertical rotary shaft rotatably supported
within said frame below said raw material supply orifice, a horizontal
rotor mounted within said frame at the upper end of said rotary
shaft for rotation in a rotational direction, a hollow rotary cylinder
mounted within said frame to the upper surface of said rotor centrally
thereof, said hollow rotary cylinder having an outer peripheral
wall spaced from the inner cylindrical surface of said frame to
define therebetween a cylindrical raw material ejection space, said
hollow rotary cylinder being opened at its upper end below said
raw material supply orifice and having a bottom for closing its
bottom end, said peripheral wall of said hollow rotary cylinder
having at least one slot for ejecting therethrough by centrifugal
force into said ejection space raw material fed onto said bottom,
at least one main striking member mounted to said rotor outside
said hollow rotary cylinder and having a striking surface facing
toward said rotational direction of said rotor such that said raw
material ejected through said slot impinges upon said striking surface
during its movement through said raw material ejection space, a
raw material repulsion fence arranged within said frame surrounding
said rotor and spaced from the loci of rotation of said main striking
member and the inner wall of said frame, and means for maintaining
the space between the inner wall of said frame and said raw material
repulsion fence under a negative pressure, said negative pressure
maintaining means comprising duct means for connecting said space
to said raw material supply orifice through said frame.
Description BACKGROUND OF THE INVENTION
The present invention relates to a crusher and more particularly
to a crusher of the type in which the raw material is crushed by
forcing it to collide with striking members or hammers revolving
at a high speed within a crusher frame.
In general, there have been known two types of crushers in which
a raw material is crushed by causing it to be impinged upon striking
members such as striking plates, hammers, etc. revolving at a high
velocity within the crusher frame, i.e. one in which the rotary
shaft carrying the striking members is disposed horizontally, and
another in which the rotary shaft is vertical. In both types, it
is a well known fact that as the particle diameter of the raw material
to be crushed becomes small the crushing of such material is made
difficult. In order to carry out the crushing effectively it has
been a common practice to increase the rate of rotation of the rotary
shaft for the purpose of realizing a greater impact generated at
the time of the collision of the raw material with the striking
members. However, as the particle diameter of the raw material becomes
small, the mass of the material also becomes small so that not only
does the impact given thereto at the time of the collision with
the striking members become small, but also, since the air surrounding
the material is severely agitated by the stiking members as well
as the parts supporting them which are revolving at a high velocity,
the raw material having a small particle diameter can be easily
accelerated by the agitated air, resulting in a decrease in the
difference in velocity between the material and the striking members,
thus reducing the crushing force caused by the collision. In extreme
cases, it may happen that the raw material escapes sideways without
impinging upon the striking members. Therefore, in the case where
the particle diameter of the raw material is small, it is very difficult
to effectively crush it by merely increasing the rate of rotation
of the striking members. Nevertheless, it is a known fact that although
the known crushers of these types have the defects as above described,
they have been used more than crushers of other types, e.g. rod
mills, roller mills, etc. because they are simple in construction,
small in size in relation to capacity, small in the amount of space
required for the installation, etc.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a crusher of
the type having a vertical rotary shaft as referred to above wherein
the material to be crushed having a relatively small particle diameter
can be effectively crushed without the fear of being disordered
by the agitated air generated by striking members rotating at a
high velocity within the crusher frame together with the rotary
shaft carrying the striking members.
It is another object of the present invention to provide a crusher
of the type having a vertical rotary shaft as referred to above
wherein the crushing of the raw material to be crushed can be easily
adjusted in accordance with the particle diameter of the raw material.
It is a further object of the present invention to provide a crusher
of the type having a vertical rotary shaft as referred to above
wherein the striking surface of the striking member is always maintained
at a predetermined position irrespective of its degree of wear until
the wear progresses to a predetermined limit.
It is another object of the present invention to provide a crusher
of the type having a vertical rotary shaft as referred to above
wherein the raw material to be crushed is effectively crushed even
if the raw material to be crushed is fed into the crusher in relatively
large amounts, so that the crushing efficiency is increased.
It is a further object of the present invention to provide a crusher
of the type having a vertical rotary shaft as referred to above
wherein the raw material to be crushed is crushed so as to have
a relatively uniform particle diameter.
It is still a further object of the present invention to provide
a crusher of the type having a vertical rotary shaft as referred
to above wherein the striking members have excellent wear-resistance.
In accordance with the present invention a crusher of the type
referred to above is provided which comprises a frame, a vertical
rotary shaft, a horizontal rotor rotatively supported at the top
end of the vertical rotary shaft within the frame, a hollow rotary
cylinder mounted to the upper surface of the rotor centrally thereof
and having an open upper end as well as a closed bottom, the peripheral
wall of the hollow rotary cylinder being formed with a number of
vertical raw material ejection slots, and a number of main striking
members arranged on the horizontal rotor outside the hollow rotary
cylinder at a position where the raw material fed into the hollow
rotary cylinder and ejected therefrom, due to centrifugal force
through the raw material ejection slots, impinges thereupon.
In a preferred embodiment of the present invention the main striking
members are pivoted to the horizontal rotor so that they can maintain
a predetermined position relative to the rotor due to the centrifugal
force applied to their center of gravity.
In accordance with one aspect of the present invention each of
the main striking members comprises a number of main striking elements
lying one on top of another, each having an identical configuration
of relative thinness so that the element can be fully heat treated.
It is a further aspect of the present invention that the horizontal
rotor mounts a number of auxiliary striking members each disposed
between neighbouring main striking members so that the material
to be crushed can be crushed by the main striking members in association
with the auxiliary striking members.
In accordance with another preferred embodiment of the present
invention a fence to repulse the raw material crushed by the main
and auxiliary striking members is arranged within the crusher frame
around the horizontal rotor and outside the rotation loci of the
main and auxiliary striking members, whereby the space formed between
the inside wall of the frame and the outside of the fence is maintained
under a negative pressure so that the crushed materials which have
already been crushed to a particle diameter below a predetermined
diameter are sucked out of the crushing chamber to be discharged
from the crusher, whereby the material to be crushed is prevented
from being excessively crushed.
In a preferred form of the fence it comprises an array of bars
each having a square cross-section and arranged vertically with
a suitable gap being left between the respective neighbouring ones
thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects and advantages of the present invention will become
apparent from the following description taken in conjunction with
the accompanying drawings wherein are set forth by way of illustration
and example certain embodiments of this invention.
FIG. 1 is a side elevational view of one embodiment of the present
invention, partly broken away;
FIG. 2 is a longitudinal sectional view of the crusher shown in
FIG. 1;
FIG. 3 is a plan view of the crusher shown in FIG. 2 as viewed
from above with the top plate of the crusher frame taken away;
FIG. 4 is a plan view of the rotor of the crusher shown in FIG.
2 in an enlarged scale;
FIG. 5 is a sectional view taken along the line V--V of FIG. 4;
FIG. 6 is a schematical view to explain the ejection of the raw
material through the raw material ejection slot formed in the wall
of the hollow rotary cylinder of the crusher shown in FIGS. 3 to
5;
FIG. 7 is a side elevational view of the hollow rotary cylinder
of the crusher shown in FIG. 2;
FIG. 8 is a sectional view of the hollow rotary cylinder taken
along the line VIII--VIII of FIG. 7;
FIG. 9 is a bottom view of the hollow rotary cylinder shown in
FIGS. 7 and 8;
FIG. 10 is a plan view of the rotor proper with the main and auxiliary
striking members being removed from the rotor shown in FIGS. 3 and
4;
FIG. 1 is a sectional view of the rotor taken along the line XI--XI
of FIG. 10;
FIG. 12 is an enlarged plan view of a portion of the rotor shown
in FIG. 4;
FIG. 13 is a schematical view similar to FIG. 6 to explain the
ejection of the raw material through the raw material ejection slot;
FIG. 14 is a diagram representing the results of experiments made
with the crusher shown in FIG. 1;
FIG. 15 is a longitudinal sectional view of another embodiment
of the crusher according to the present invention;
FIG. 16 is a plan view of the crusher shown in FIG. 15 as viewed
from above with the top plate of the crusher frame taken away;
FIG. 17 is an enlarged plan view of a part of the raw material
repulsing fence shown in FIG. 16;
FIG. 18 is a sectional view of the raw material repulsing fence
shown in FIG. 17 taken along the line XVIII--XVIII of FIG. 17;
FIG. 19 is a plan view of the main striking member shown in FIG.
12;
FIG. 20 is a sectional view of the main striking member shown in
FIG. 12 taken along the line XX--XX of FIG. 19;
FIG. 21 is a sectional view similar to FIG. 20 of a modified main
striking member;
FIG. 22 is a plan view of a supplemental weight to be cooperated
with the main striking member shown in FIG. 21; and
FIG. 23 is a sectional view of the supplemental weight shown in
FIG. 22 taken along the line XXIII--XXIII of FIG. 22.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Now the first preferred embodiment of the present invention will
be explained with reference to FIGS. 1 to 12 of the attached drawings.
As shown in FIGS. 1 to 4 rotatively journaled within a cylindrical
crusher frame 1 centrally thereof by means of bearings 31 and 32
is a vertical rotary shaft 2 to the upper end of which is fixedly
secured a horizontal rotor 3 through a fixing means 27 of any known
suitable design so as to have its center line aligned with the center
line a of shaft 2. Mounted on rotor 3 centrally thereof is a hollow
rotary cylinder 4 so as to have its center line aligned with center
line a of rotor 3 cylinder 4 being opened at its upper end and
closed by a bottom at its lower end, and a number of raw material
discharge slots 5 are formed in the peripheral wall of cylinder
4 at substantially equi-angular intervals as best shown in FIG.
5. On the upper surface of rotor 3 there are provided a number of
main striking members 7 outside rotary cylinder 4 each pivoted
to rotor 3 by a pin 8 vertically secured thereto, such that they
are located in a rearward direction relative to the direction of
rotation of rotor 3 shown by the arrow b in FIG. 6 from radial planes
c passing through center line a and the raw material ejection guide
surfaces 5' of raw material ejection slots 5 whereby guide surfaces
5' are formed by the side walls of slots 5 respectively facing
towards direction b of rotation of rotor 3. The walls of rotary
cylinder 4 are relatively narrow compared to the width of the ejection
space 6 formed between cylinder 4 and main striking members 7 and
the distance between each pins 8 and the outer peripheral surface
of cylinder 4. Thus, it will be appreciated that when a raw material
is fed onto the bottom of rotary cylinder 4 it will be ejected through
slots 5 thereof by the centrifugal force applied to it so as to
leave ejection guide surface 5' and freely fly in raw material ejection
space 6 formed between cylinder 4 and main striking members 7 along
an ejection line d as shown by the dot-and-dash line in FIG. 6 to
impinge upon vertical striking surfaces 7' of main striking members
7 each facing towards direction of rotation b of rotor 3 whereby
the material is crushed by impact. In this case, the angle .theta.'
made between a radial direction of rotor 3 passing through its center
line a and striking surface 7' at the time when main striking member
7 is swung about pin 8 due to the centrifugal force applied to its
center of gravity during the rotation of rotor 3 is preferably selected
to be between 30.degree. and 60.degree., inclined forwards as viewed
in the direction of rotation b of rotor 3. As shown in FIGS. 7 to
9 hollow rotary cylinder 4 is formed with a number of arcuate rib
elements 9 lying on a circle on the lower surface of the bottom,
respective neighbouring ribs 9 having gaps 9' left therebetween
such that gaps 9' are distributed at irregular angular intervals
around the center. In the upper surface of rotor 3 as shown in
FIGS. 10 and 11 an annular groove 10 is coaxially formed with center
line a and having a configuration corresponding to that of arcuate
rib elements 9 and a number of screw threaded holes 11 12 13
are formed in the bottom of groove 10 at irregular angular intervals.
As shown in FIG. 5 with a screw 14 being screwed into any one of
screw threaded holes 11 12 13 and with its head being put into
any one of gaps 9' formed between neighbouring rib elements 9 on
the lower surface of the bottom of rotary cylinder 4 the relative
position between raw material ejection guide surface 5' of raw material
ejection slots 5 formed in the peripheral wall of rotary cylinder
4 and main striking members 7 can be adjusted. The angle .theta.
at which the ejected raw material impinges upon striking surface
7' of main striking member 7 as shown in FIG. 6 is preferably between
60.degree. and 85.degree.. As shown in FIGS. 4 and 12 in addition
to striking members 7 arranged on the upper surface of rotor 3 on
a circle near its outer periphery at equi-angular intervals, there
are arranged also auxiliary striking members 15 on rotor 3 alternately
so as to be swingable about pins 8' secured to rotor 3 in a circle,
each of auxiliary striking members 15 having a vertical striking
surface 15' which extends substantially in the radial direction
of rotor 3 and is inclined rearwards relative to the direction of
rotation b of rotor 3 whereby auxiliary striking member 15 is disposed
within respective indented regions 3' formed in the upper surface
of circular rotor 3 which region 3' has a stopper 16 at the position
where striking surface 15' meets, shaped so as to prevent auxiliary
striking member 15 from swinging towards the direction of rotation
b of rotor 3. At this point it should be noted that raw material
ejection space 6 referred to above means in the embodiment shown
that no guide element exists to guide the ejected raw material between
raw material ejection guide surfaces 5' of raw material ejection
slots 5 of hollow rotary cylinder 4 and striking surfaces 7' of
main striking members 7 and after the raw material ejected through
slots 5 flies freely into this space 6 along ejection line d as
shown in FIG. 6 it impinges upon striking surfaces 7'.
As shown in FIG. 2 a cover 33 detachably mounted to the upper end
of crusher frame 1 is provided with a flat cylindrical casing 34
on its surface somewhat eccentrically of the center line a of shaft
2 with a raw material supply orifice 19 being opened in its top
plate in alignment with center line a, a raw material hopper 20
being secured to the top plate of casing 34 coaxially with raw material
supply orifice 19 so as to surround it. The upper portion of crusher
frame 1 and the top plate of flat cylindrical casing 33 may be connected
by an ejection air suction duct 18 if required, as in the second
embodiment to be explained later. As shown in FIGS. 1 and 2 shaft
2 is adapted to be driven by a prime mover 21 arranged in a side-by-side
relationship with crusher frame 1 on a common base through a pulley
23 mounted on shaft 2 at its lower end, a pulley 22 mounted to the
output shaft of prime mover 21 and endless belts 24 reeved on pulleys
22 23. Further, a crushed material guide plate 35 is mounted within
crusher frame 1 below rotor 3 obliquely so as to extend substantially
from the upper peripheral portion of frame 1 to the lower central
portion thereof where a discharge orifice 36 is provided vertically
through the common base.
The operation of the crusher the constitution of which has been
explained so far will now be described fully.
Upon starting the drive of prime mover 21 rotor 3 is rotated at
high speed in the direction shown by the arrow b in FIG. 6 through
pulleys 22 23 belts 24 and vertical rotary shaft 2. When the raw
material having a relatively small diameter, say, smaller than about
40 mm is supplied to hollow cylindrical rotor 4 through raw material
supply orifice 19 via hopper 20 it comes into contact with the
bottom surface of hollow rotary cylinder 4 and is thereby given
a rotational force around center line a, whereby it is ejected through
raw material ejection guide surfaces 5' of raw material ejection
slots 5 of rotary cylinder 4 due to the centrifugal force, into
raw material ejection space 6. The raw material thus ejected flies
in space 6 along ejection line d shown by the dot-and-dash line
in FIG. 6 and impinges upon striking surfaces 7' of main striking
members 7 maintaining impinging angle .theta. therebetween as shown
in FIG. 6 whereby the raw material is crushed. Since striking surface
7' is located outside raw material ejection slots 5 of cylinder
4 the peripheral velocity centered at center line a of striking
surfaces 7' is larger than that of ejection guide surfaces 5', so
the raw material ejected from guide surfaces 5' flies out therefrom
into raw material ejection space 6 and impinges upon striking surfaces
7' of main striking members 7 which are moving at a faster peripheral
velocity. In this case the locus of the raw material ejected from
guide surfaces 5' to fly out into space 6 is substantially constant
regardless of the rate of rotation of rotor 3 that is, the locus
being in a direction substantially tangential to the outer periphery
of hollow rotary cylinder 4 after the raw material leaves guide
surfaces 5' as shown by the arrow d' in FIG. 13 and striking surfaces
7' which are moving at a high peripheral velocity impinge upon the
raw material which flies along locus d'. The position on striking
surfaces 7' at which the raw material impinges thereupon can be
adjusted by changing the position of raw material ejection slots
5 or raw material ejection guide surfaces 5' relative to that of
main striking members 7. Thus, after the raw material impinges upon
striking surfaces 7' near the boss of main striking members 7 it
rolls on them to their tip and is thrown towards the inner surface
of crusher frame 1. Since the peripheral velocity of the portion
near the boss of main striking surface 7' is less than that of the
tip the crushing force at the former is less than that at the latter,
so there arises the effect that the shape of the crushed particle
is made nearly spherical by causing it to be rolled on striking
surfaces 7'. Contrarily, if the raw material impinges upon striking
surfaces 7' near their tip end, although it is subjected to a greater
crushing force, the effect that the crushed particle is made spherical
in shape can not be expected. Therefore, the part at which the raw
material impinges upon striking surfaces 7' can be selected according
to whether it is a greater crushing force or a better shape of the
crushed particle that it is desired to obtain.
As shown in FIG. 14 which expresses the results of experiments
made with the crusher so far explained, it is clear that, when angle
.theta. at which the raw material impinges upon striking surfaces
7' is somewhat acute outwardly, relative to the direction of rotation
b of rotor 3 as shown in FIG. 6 if angle .theta. falls between
60.degree. and 85.degree. rather than being 90.degree., the proportion
of particles with a diameter larger than 2.5 mm is small and yet
the modal diameter is small, demonstrating effective crushing.
As to striking surfaces 15' of auxiliary striking members 15 which
are arranged on rotor 3 in its indented regions 3' below main striking
members 7 and rearwardly of main striking members 7 with regard
to the direction of rotation b of rotor 3 they have the purpose
of crushing the raw material which has not been crushed by striking
surfaces 7' of main striking members 7 i.e. if the raw material
is fed to rotary cylinder 4 in excessive amounts, the raw material
thrown into raw material ejection space 6 after being ejected from
raw material ejection guide surfaces 5' has its ejection energy
merely damped by impinging upon striking surfaces 7' in layers,
without being crushed, but during its fall under the influence of
gravity it impinges upon striking surfaces 15' of auxiliary striking
members 15 to be crushed by them.
It is needless to say that the striking angle .theta. made between
striking surfaces 7' of main striking members 7 and the raw material
impinging upon them is maintained by centrifugal force applied to
main striking members 7 at their center of gravity.
Next another embodiment of the present invention will be explained
with reference to FIGS. 15 to 18.
This embodiment is substantially identical in constitution to that
of the first one except in that in this embodiment a raw material
repulsion fence 112 is arranged within the upper portion of crusher
frame 1 so as to surround rotor 3 outside the rotating loci of main
striking members 7 and auxiliary striking members 15. Therefore,
in FIGS. 15 to 18 like numerals refer to like parts in the first
embodiment. Fence 112 comprises a number of vertical bars 114 each
having a square cross-section and arranged in a circle at equi-intervals,
whereby bars 114 are swingably supported between an upper and a
lower support rings 116 116 with upper and lower pins 114', 114'
projected outwards centrally of each of bars 114 at its upper and
lower ends being rotatively fitted within corresponding openings
117 117 formed in upper and lower support rings 116 116. Further,
a serrated ring plate 115 having a number of serrations formed around
its inner periphery is fixedly secured to crusher frame 1 the number
of serrations corresponding to that of bars 114 and the configuration
of each of them is so formed that when serrated ring plate 115 is
fixedly disposed close to bars 114 outwards thereof the serration
can maintain one of the four faces of each of bars 114 substantially
towards the moving direction of the raw material repulsed by main
striking members 7 and auxiliary striking members 15 whereby a
sorting or screening slit t is left between respective adjoining
bars 114. The shape of slit t should preferably widen, in the downwards
direction.
In the present embodiment, upon rotation of rotary shaft 2 through
prime mover 21 the raw materials fed to the bottom of hollow rotary
cylinder 4 through raw material hopper 20 and raw material supply
orifice 19 are ejected in a direction tangential to the outer periphery
of cylinder 4 through raw material ejection slots 5 due to centrifugal
force and are crushed by main striking members 7 and auxiliary striking
members 15 whereby the crushed raw material repulsed by them impinges
upon fence 112 so that material having a larger dimension is additionally
crushed again. In this case, the generated finely crushed particles
are sucked through sorting slits t formed between respective neighbouring
bars 114 due to the negative pressure prevailing in the space between
the inner wall of crusher frame 1 and the outer periphery of fence
112 as explained later and discharged out of crusher frame 1 by
any suitable means not shown. In this case, such negative pressure
is generated by duct 18 which connects the space around fence 112
to flat cylindrical casing 34 and acts to induce a negative pressure
due to the negative pressure existing within hollow rotary cylinder
4. Alternatively, a suction blower or the like may be connected
to the upper portion of crusher frame 1 to maintain the space around
fence 112 in a negative pressure condition.
In this embodiment, if the one face of any of bars 114 is subjected
to excessive wear at its upper part it may continue to be used by
having it upper and lower sides reversed. Therefore, each of the
4 faces of bars 114 may be used twice for a total of eight applications
of the one bar.
Thus, it will be appreciated that this embodiment makes it possible
to carry out the more effective crushing of raw materials, and at
the same time the prevention of excessive crushing is assured. In
addition, the use of bars with a square cross-section as the repulsion
fence reduces clogging and increases the life of the fence.
In the two embodiments shown and explained above, main and/or auxiliary
striking members 7 15 may comprise a number of relatively thin
striking elements as shown or suggested in FIGS. 2 5 and 19 to
23 instead of being constituted integrally. Since the striking elements
have respectively a similar shape such that the centers of gravity
thereof coincide, when they are subjected to centrifugal force,
they occupy respectively exactly the same position relative to pins
8 or 8'. During the operation of the crusher main or auxiliary striking
members 7 or 15 have their striking surfaces 7' or 15' subjected
to wear due to the impinging of raw materials. In this case, assuming
that striking members 7 or 15 comprise three striking elements,
it is generally true that the striking surface of the middle element
has a much higher possibility of impinging the raw materials than
one located above or below it. Therefore, the striking surface of
the middle element is subjected to greater wear than the others.
In this case, the middle element may be replaced by the one above
or below.
It is inevitable that the striking surfaces of the striking members
will become worn out. In order to resist wear the striking member
has customarily been made of a material which can be hardened by
heat treatment. However, in this case, the cooling during the process
of heat treatment is difficult when the depth from the surface is
great, resulting in poor hardening.
By constituting a striking member from a number of striking elements
such that these are arranged one upon another as stated above, each
of the elements may be relatively thin so that its striking surface
can be sufficiently hardened in all parts. Further, since it is
usual that among the striking elements one disposed intermediately
is subjected to greater wear than others, when it has been worn
out by more than a predetermined value, it is necessitated only
that the worn out element be replaced by a new one or by one of
those disposed above or below it, otherwise, when a specific portion
of a striking surface of a striking member has worn out, the striking
member itself would have to be discarded as a whole. Thus, this
constitution of a striking member exhibits substantial economy in
terms of material.
Further, as shown in FIGS. 12 22 and 23 striking member 7 may
have a supplemental weight 26 detachably mounted thereto for the
purpose of the adjustment of the position of the center of gravity.
From the foregoing, it will be apparent that according to the present
invention, such various excellent effects as explained below can
be obtained.
1. Raw material with a relatively small particle size can impinge
strongly upon the striking surfaces of the main striking members
in an orderly way regardless of the rate of rotation of the rotor,
without being in danger of being subjected to disorder due to air
turbulence caused by the revolving striking members, so that fine
particles can be obtained, i.e. the crushing efficiency is remarkably
improved, the yield of the crushed material with a fine particle
diameter being increased.
2. Since the relative position between the raw material ejection
guide surfaces of the raw material ejection slots of the hollow
rotary cylinder and the striking members can be adjusted, the raw
material can be made to impinge upon the striking surfaces at either
the outer end portion or inner end portion thereof, depending upon
the particle size of the crushed material to be obtained, so that
the crushing can be carried out at will depending upon the object
of the crushing, being such as that the raw material is to be crushed
to have a fine particle size, or that the shape of the particle
of the crushed material is due consideration, etc.
3. The width of the loci of the raw materials ejected from the
hollow rotary cylinder differs depending upon the amount of raw
materials fed in, and, when the outer periphery of the width comes
off the outer end of the striking surfaces of the striking members,
it is possible that the raw materials are made to impinge with certainty
upon the striking surfaces by controlling the outer margin of the
loci of the raw materials with the position of the hollow rotary
cylinder being adjusted relative to that of the striking members
depending upon the amount of the materials fed in. Further, the
relative position between the striking members and the hollow rotary
cylinder can be similarly adjusted depending upon the wear of the
raw material ejection guide surfaces of the raw material ejection
slots of the hollow rotary cylinder.
4. The impinging angle .theta. made between the impinging raw materials
and the striking surfaces can be made optimum so that the crushing
efficiency can be improved.
5. Since the striking surfaces of the striking members are maintained
by having the striking members swingably supported by the pins so
that centrifugal force is applied to the center of gravity of the
striking members the maintaining of the striking surfaces at their
optimum position is made quite easy. The recession of the striking
surfaces of the striking members due to their wear makes the center
of gravity of the striking members recede so that the striking surfaces
are automatically advanced by an amount corresponding to half the
amount of wear. A further advancing of the striking surfaces can
be effected by mounting or dismounting the supplemental weights
as appropriate. The mounting of the striking members by pins 8 so
as to be swingable therearound eliminates the fear of the destruction
of the striking members due to striking against some uncrushable
foreign matter is, so the safety of the striking members is enhanced.
6. The auxiliary striking members catch the noncrushed raw materials
and can crush them. Therefore, the crushing efficiency of the raw
material can be considerably improved even if the amount of raw
material fed in is large.
7. By the provision of the raw material repulsion fence around
the rotor the excessive crushing of the raw material can be effectively
prevented.
8. By constituting the main and auxiliary striking members so as
to respectively comprise a number of striking elements each having
a relatively thin plate-like configuration, each of the striking
elements can be heat treated throughly so that it can be fully hardened,
thereby resisting wear. And, if any one of the striking elements
wears out to a predetermined value, it is necessary only that the
worn out element alone has to be replaced by a new one or exchanged
with another element that has not yet been subjected to such a degree
of wear. This makes it possible to not have to replace the whole
lot of the main or auxiliary striking members, as is required when
they are respectively constituted as an integral body.
It will be apparent to those skilled in the art that various changes
in the structure and relative arrangement of parts may be made without
necessarily departing from the scope of the present invention as
defined in the claims appended. |