Abstrict An impact crusher wherein hard particulate material is comminuted
during travel between a rotor provided with beaters and a pivotable
impact or grinding means, the latter being mounted in the housing
of the crusher at a level above the rotor and tends to pivot by
gravity and/or by spring force in a direction to reduce the width
of the gap between its lower portion and the periphery of the circle
swept by the rotor beaters. The impact or grinding means is pivotable
by feed screws which are articulately connected thereto and extend
upwardly through openings in the top wall of the housing. The outer
portions of the feed screws are rigid with a crosshead which can
be moved up and down by a double-acting hydraulic cylinder and piston
unit which has an appropriate lost motion to allow the impact or
grinding means to yield in direction away from the rotor. When the
cylinder and piston unit lifts the crosshead, additional cylinder
and piston units can readily shift stepped or wedge-like inserts
which are movable between the crosshead and the top wall of the
housing to thereby determine the minimum width of the gap. The inserts
can be engaged directly by the underside of the crosshead or by
a platform which can be mounted beneath the crosshead. When the
adjusting mechanism for the impact or grinding means employs a platform,
packages of dished springs are inserted between the platform and
the crosshead.
Claims What is claimed as new and desired to be protected by Letters Patent
is set forth in the appended claims:
1. In an impact crusher, a combination comprising a housing having
an inlet for material to be comminuted and an outlet for comminuted
material; a rotor provided with beaters and mounted in said housing;
an impact or grinding means mounted in said housing for movement
toward and away from said rotor and defining therewith a gap through
which the material to be comminuted passes on its way from said
inlet toward said outlet and is comminuted by said rotor beaters
and said impact or grinding means; and adjusting means for varying
the width of said gap, having a lost motion to allow the impact
or grinding means to yield in direction away from said rotor and
including carrier means connected with said impact or grinding means
and extending from said housing, holder means connected with said
carrier means outside of said housing, motor means operable to move
said holder means at least in a direction to increase the width
of said gap, and at least one insert mounted at the other side of
said housing and having portions of different thicknesses, said
insert being movable between said holder means and said housing
to thereby determine the minimum width of said gap depending on
the thickness of that portion of said insert which is located between
said housing and said holder means.
2. A combination as defined in claim 1 further comprising second
motor means for moving said insert with respect to said housing
and said holder means.
3. A combination as defined in claim 1 wherein said carrier means
comprises a plurality of discrete carriers and said holder means
comprises a crosshead rigid with said carriers.
4. A combination as defined in claim 1 wherein said adjusting
means further comprises a platform interposed between said holder
means and said insert, said adjusting means further comprising yieldable
cushioning means interposed between said holder means and said platform.
5. A combination as defined in claim 4 wherein said cushioning
means comprises at least one set of dished springs.
6. A combination as defined in claim 4 wherein said motor means
comprises a fluid-operated cylinder and piston unit connected between
said platform and said housing.
7. A combination as defined in claim 1 wherein said motor means
comprises a double-acting fluid-operated cylinder and piston unit.
8. A combination as defined in claim 1 wherein said impact or
grinding means is pivotable in said housing and normally tends to
move nearer to said rotor under the action of gravity.
9. A combination as defined in claim 1 further comprising means
for biasing said holder means against said insert.
10. A combination as defined in claim 1 wherein said insert is
a wedge.
11. A combination as defined in claim 1 wherein said insert is
stepped.
Description BACKGROUND OF THE INVENTION
The present invention relates to comminuting apparatus for rock,
concrete or the like, and more particularly to improvements in impact
crushers of the type wherein a rotor provided with beater bars or
the like entrains and propels material to be comminuted against
one or more adjustable impact or grinding means.
It is already known to mount the impact or grinding means, hereafter
called "impact means" for simplicity, for movement about
a pivot axis which is parallel to the rotor axis and to bias the
impact means toward the periphery of the rotor by one or more springs
which assist the action of gravity and tend to reduce the width
of the gap between the impact means and the path of movement of
beater bars, or analogous comminuting elements at the periphery
of the rotor. It is also known to couple the impact means to one
or more elongated members (e.g., feed screws) which extend from
the housing of the impact crusher and are connected to each other
by a crosshead. The extent to which the impact means can pivot toward
the periphery of the rotor is determined by one or more stops which
are mounted at the outer side of the housing and are located in
the path of movement of the crosshead. The crosshead can be moved
relative to the housing by a suitable motor, e.g., a hydraulic cylinder
and piston unit which is disposed between the housing and the crosshead.
The connection between the cylinder and piston unit and crosshead
and/or housing is designed to have a lost motion to enable the impact
means to yield freely away from the rotor.
The extent to which the crusher can comminute material which is
being fed into the housing to pass between the rotor and the breaker
depends primarily on the width of the gap between the beating, elements
at the periphery of the rotor and the nearest portion of the impact
means. The adjustability (pivotability) of the impact means is intended
to enable an operator to change the extent of comminuting action
as well as to compensate for pronounced wear on those portions of
the rotor and impact means which come into contact with the material
to be comminuted. The mounting of the impact means in a selected
angular position should not be rigid because the impact means must
be capable of yielding (i.e., of increasing the width of the gap)
if such gap receives one or more non breakable objects which are
sufficiently large to necessitate a temporary widening of the gap.
As mentioned above, the impact means normally tends to pivot nearer
to the rotor, either by gravity alone or by gravity as well as under
the action of one or more resilient elements in the form of helical
springs or the like.
In certain types of presently known impact crushers, the width
of the gap between the impact means and the circle swept by the
beating elements of the rotor is changed by changing the positions
of feed screws relative to the crosshead. This involves rotation
of nuts which mesh with the feed screws at both sides of the crosshead.
In view of the fact that many impact crushers are very large and
are designed to comminute extremely hard substances, the dimensions
of feed screws and nuts are also substantial which means that rotation
of nuts relative to the feed screws necessitates the exertion of
very pronounced effort. Moreover, the nuts are likely to jam because
of the hard shocks they have to take up or to stick due to accumulations
of dust in the threads of feed screws. Therefore, such nuts cannot
always be manipulated by hand which contributes to the cost of the
operation. Moreover, each and every adjustment necessitates a stoppage
of the crusher because the likelihood of injury to attendants is
much too great if the nuts are to be rotated while the beaters of
the rotor propels solid particles against the impact means.
The manner in which the aforementioned cylinder and piston unit
can be used to prevent or eliminate bridging of material in the
interior of the housing of an impact crusher is disclosed in "Prinzip
und Moeglichkeiten der Prallzerkleinerung" aus "Zement-Kalk-Gips"
(Year 18 1965 Vol. 11 pages 580-588). There is described the possibility
of increasing the width of the gap between the rotor and the impact
means; however, the publication does not offer any suggestion to
locate and retain the impact means in any one of several selected
positions. The main purpose of the construction which is disclosed
in that publication is to relieve the nuts on the feed screws in
order to facilitate manual rotation of the nuts. Such operation
is time-consuming because the sequence in which the loosening of
nuts and lifting of the crosshead take place changes in dependency
on the desired direction of adjustment. Moreover, a person must
climb onto the housing of the crusher in order to loosen the nuts.
Purely hydraulic adjusting systems are too complex and the interval
required for an adjustment is too long. Reference may be had to
German Offenlegungsschrift No. 2037104.
SUMMARY OF THE INVENTION
An object of the invention is to provide an impact crusher with
novel and improved means for changing the position of one or more
impact or grinding means with respect to the rotor.
Another object of the invention is to provide an impact crusher
wherein the position of the impact or grinding means relative to
the rotor can be changed with little loss in time, without the exertion
of any appreciable manual effort, and without any danger to attendants.
A further object of the invention is to provide an impact crusher
wherein the width of the gap between the rotor and the orbit circle
of the beaters of the impact or grinding means can be varied within
any desired practical range and wherein the impact or grinding means
invariably assumes (or can be caused to assume) a selected position
with respect to the rotor.
An additional object of the invention is to provide the impact
crusher with novel and improved adjusting means for pivoting the
impact or grinding means between a plurality of positions and for
locating the impact or grinding means in a selected position.
The invention is embodied in an impact crusher which comprises
a housing having an inlet for material to be comminuted and an outlet
for comminuted material, a rotor which is provided with beaters
and mounted in the housing, an impact or grinding means which is
also mounted in the housing for movement toward and away from the
rotor and defines with the circle swept by the rotor beaters a gap
through which the material passes on its way from the inlet toward
the outlet whereby the material is comminuted by the rotor beaters
and the impact or grinding means (the latter is preferably pivotable
in the housing and tends to move nearer to the rotor under tha action
of gravity and/or in response to bias of suitable resilient means),
and adjusting means for varying the width of said gap.
The adjusting means comprises carrier means (e.g., a set of parallel
feed screws) connected with the impact or grinding means and extending
from the housing, holder means (e.g., a cross-head interconnecting
the feed screws or a crosshead and a platform which latter is interposed
between the cross-head and the housing) rigidly connected with the
carrier means outside of the housing, motor means (preferably including
a fluid-operated double-acting cylinder and piston unit) which is
operable to move the holder means in a direction to increase the
width of the gap (and preferably also in a direction to move the
impact or grinding means nearer to the rotor and which has an appropriate
lost motion to allow the impact or grinding means to freely yield
away from the rotor, and at least one insert which is mounted on
the housing and has portions of different thicknesses (such insert
may constitute a wedge or it may be stepped with distinct shoulders
between portions of different thicknesses). The insert is movable
(preferably by one or more double-acting fluid-operated cylinder
and piston units) between the holder means and the housing to thereby
determine the minimum width of the gap depending on the thickness
of that portion of the insert which has been placed between the
housing and the holder means. A discrete insert may be provided
for each feed screw, and each insert may be slotted to straddle
the respective feed screw.
When the holder means comprises a crosshead and a platform, one
or more sets of dished springs or analogous cushioning means may
be interposed between the crosshead and the platform; the motor
which moves the holder means is then connected between the platform
and the housing.
The novel features which are considered as characteristic of the
invention are set forth in particular in the appended claims. The
improved impact crusher itself, however, both as to its construction
and its mode of operation, together with additional features and
advantages thereof, will be best understood upon perusal of the
following detailed description of certain specific embodiments with
reference to the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a schematic longitudinal vertical sectional view of an
impact crusher which embodies one form of the invention;
FIG. 1a is a fragmentary vertical section, showing a detail of
a modification of the FIG. 1 embodiment;
FIG. 2 is a fragmentary transverse sectional view substantially
as seen in the direction of arrows from the line II-II of FIG. 1;
and
FIG. 3 is a similar fragmentary transverse sectional view of a
modified impact crusher.
DESCRIPTION OF THE PREFERRED EMBODIMENTs
Referring first to FIGS. 1 and 2 there is shown an impact crusher
which comprises a housing 100 having an inlet 1 and an outlet 1a.
The housing supports a rotor 2 which can be driven to rotate in
a counterclockwise direction, as viewed in FIG. 1 and carries an
annulus of customary beater bars or analogous beating elements 2a.
Such beating elements are mounted at the periphery y of the rotor
2. The reference character X denotes the horizontal axis of the
shaft which drives the rotor 2 in counterclockwise direction.
The top wall 6 of the housing 100 is located above an impact plate
3 which is mounted on a horizontal pivot member 4 so that its lower
portion 3a can move nearer to or further away from the path of orbital
movement of beating elements at the periphery y of the rotor 2.
Thus, the width of the gap a between the impact plate 3 and the
rotor 2 can be changed by pivoting the impact plate about the axis
of the member 4. The latter is mounted in the side walls of the
housing 100.
The adjusting means for pivoting the impact plate 3 with or relative
to the member 4 comprises two parallel elongated carriers 5 here
shown as feed screws 5 having bifurcated lower end portions 5a which
are articulately connected to a rib 3b at the upper side of the
impact plate by pins 5b. The feed screws 5 extend outwardly and
upwardly through openings in the top wall 6 and are coupled to each
other by a traverse or crosshead 7 forming a holder means. The crosshead
7 is indirectly supported by the top wall 6 through the intermediary
of shiftable inserts 8 which abut against the outer side of the
top wall and are disposed below a platform 16. The means for shifting
the inserts 8 along the outer side of the top wall comprises fluid-operated
(preferably hydraulic) motors here shown as double-acting hydraulic
cylinder and piston units having cylinders 9 and piston rods 10.
Each cylinder 9 is fixed to the top wall 6 and the piston rods 10
are attached to the respective inserts 8. It is clear that a single
cylinder and piston unit can be used to move all of the inserts
8 in unison.
The adjusting means for pivoting the impact plate 3 further comprises
an additional fluid-operated (preferably hydraulic) motor having
a double-acting cylinder 11 and a piston rod 13 which is coupled
to a plate-like guide 14. The lower end portion of the cylinder
11 is articulately connected to upwardly extending lugs 12 of the
top wall 6; such lugs extend through openings in the platform 16.
The guide 14 at the upper end of the piston rod 13 is reciprocable
in an elongated casing or support 15 having a cover or lid 17 above
the guide 14 and being mounted on the platform 16.
The crosshead 7 is secured to the feed screws 5 by pairs of nuts
18 and the lower nut of each pair is biased upwardly by a set of
dished springs 19 reacting against the upper side of the platform
16. As mentioned above, the platform 16 overlies the inserts 8 which
are slotted to enable them to move transversely of the respective
feed screws 5 and to prevent the feed screws 5 from being subjected
to bending stresses.
The crosshead 7 is biased toward the outer side of the top wall
6 by helical springs 20 which bear against the upper side of the
crosshead and react against retainers 21a at the upper ends of rods
21 whose lower end portions are anchored in the top wall 6. The
rods 21 extend through openings in the platform 16 and crosshead
7. It will be noted that the springs 20 tend to pivot the impact
plate 3 in a counterclockwise direction, as viewed in FIG. 1 so
as to reduce the width of the gap a. The crosshead 7 has upwardly
extending side panels or cheeks 7a for stops 22 which can be engaged
by the guide 14 at the upper end of the piston rod 13.
The structure which is shown in FIG. 1 and 2 protects the threads
of the feed screws 5 and nuts 18 against excessive shocks which
could develop when the impact plate 3 has yielded in response to
penetration of relatively large nonbreakable objects through the
gap a and has thereupon pivoted back toward the orbit y of the beaters
of the rotor 2. The dished springs 19 absorb such shocks by undergoing
deformation between the platform 16 and crosshead 7. These springs
are lifted with the platform 16 when the operator decides to change
the width of the gap which can be increased or reduced, depending
upon whether the operator decides to place relatively thick or relatively
thin portions of inserts 8 between the wall 6 and platform 16.
In a relatively small impact mill, the springs 19 can be dispensed
with because the stresses due to movements of the masses can be
controlled by appropriate dimensioning of threads on the feed screws
and nuts as well as by appropriate dimensioning of the hydraulic
cylinder and piston unit 11 13.
FIG. 3 shows a simplified impact mill wherein the casing 15 is
rigid with the crosshead 7. The latter is rigidly connected to the
feed screws 5 by nuts 18 18' and carries the stops 22 which can
cooperate with the guide 14 on the piston rod 13. The lower nuts
18' are located immediately above disk-shaped washers 23 which,
in turn, abut against the upper sides of adjacent portions of the
inserts 8. These inserts can be shifted in the same way as shown
in FIG. 2.
If the operators wish to increase the width of the gap a, e.g.,
to increase the width from a relatively small to a median or average
value, the piston rod 13 of FIG. 2 is caused to move upwardly so
as to push the guide 14 against the cover 17 of the casing 15. The
platform 16 lifts the crosshead 7 through the medium of dished springs
19 and lower nuts 18 whereby the nuts lift the feed screws 5 and
pivot the impact plate, 3 clockwise, as viewed in FIG. 1. (in FIG.
3 the casing 15 is rigid with the platform 7; therefore, the latter
will lift the feed screws 5 by way of the upper nuts 18). The impact
plate 3 is pivoted against the action of gravity as well as against
the resistance of helical springs 20 which tend to pivot the impact
plate counterclockwise, as viewed in FIG. 1. This means that the
lifted platform 16 (FIG. 2) or the lifted crosshead 7 (FIG. 3) does
not urge the inserts 8 against the upper side of the top wall 6.
Consequently, the motors including the cylinders 9 can easily shift
the inserts 8 in the longitudinal direction of the respective piston
rods 10. The inserts 8 have portions of different thickness so that,
when the fluid pressure in the lower chamber of the cylinder 11
(below the piston) is reduced, the impact plate 3 can pivot by gravity
or spring force to assume a position which is determined by the
thickness of insert portions below the respective dished springs
19 (FIG. 2) or lower nuts 18' (FIG. 3). FIG. 1 shows that an insert
8 may have three portions 8a, 8b, 8c of different thickness. The
thickness of the median portion 8b is less than that of the outer
portion 8a or 8c, and the thickness of portion 8a is less than that
of portion 8c. Thus, the portion 8a will be placed below the platform
16 if the width of the gap a is to be an average width, the portion
8b will be located below the platform 16 if the width of the gap
a is to be reduced to a minimum value, and the portion 8c will be
shifted below the platform 16 if the width of the gap a is to be
increased to a maximum value.
It will be noted that the mechanisms shown in FIGS. 2 and 3 allow
the impact plate 3 to yield (by pivoting clockwise, as viewed in
FIG. 1) if the beating elements of the rotor 2 introduce a bulky
and non breakable object into the gap a adjacent the lower portion
3a of the impact plate. The feed screws 5 then merely lift the crosshead
7 which stresses the springs 20. It will be recalled that the feed
screws 5 shown in FIG. 2 are free to move up or down in openings
provided therefor in the platform 16.
The cylinder 11 could be replaced with a single-acting cylinder
since it is normally only necessary to lift the crosshead 7 so as
to allow for shifting of inserts 8 with a minimum of effort. However,
it is presently preferred to use a double-acting cylinder 11 for
the following reasons: Particulate material flying around in the
interior of the housing 100 is likely to accumulate on the walls
of the housing and on the impact plate so as to jam the impact plate
in the housing. Therefore, the force furnished by the relatively
weak helical springs 20 and/or gravity might not suffice to cause
the impact plate 3 to pivot counterclockwise (as viewed in FIG.
1) when the pressure in the lower chamber of the cylinder 11 is
reduced or terminated (i.e., upon completed adjustment of the inserts
8). The upper chamber of the cylinder 11 then receives pressurized
hydraulic fluid which causes the guide 14 to bear against the stops
22 and to push the crosshead 7 downwardly whereby the crosshead
pushes the feed screws 5 in a direction to pivot the impact plate
3 counterclockwise until the platform 16 comes to rest on the adjusted
inserts 8 or until the inserts 8 are engaged by the washers 23 shown
in FIG. 3.
The stepped inserts 8 can be replaced by wedges 8d which can be
moved to a practically infinite number of different positions to
thereby effect desired changes in the minimum width of the gap a.
This is shown in FIG. 1a which otherwise is the same as FIG. 1
although parts of FIG. 1 have been omitted for simplicity.
The various motors can be started or arrested by depressing knobs
or analogous actuating elements on a control panel which can be
placed close to or at any desired distance from the crusher.
The springs 19 of FIG. 2 or analogous cushioning means perform
an additional useful function, namely of protecting the motor 11
13 against excessive shocks if the adjustment takes place while
the crusher is in operation. The springs 19 take up shocks which
develop when the impact plate 3 is lifted by material during adjustment
and is thereupon allowed to pivot toward the rotor under the action
of gravity. In the absence of such springs, the just discussed shocks
would have to be taken up by the cylinder 11 piston rod 13 and/or
by hydraulic fluid which operates the cylinder.
The clearances with which the feed screws 5 extend through the
top wall 6 and the clearances between various articulately connected
parts are selected with a view to insure unobstructed pivoting of
the impact plate 3 by gravity, under the action of springs 20 in
response to upward movement of the piston rod 13 and/or in response
to downward movement of the piston rod 13 (when the guide 14 bears
against the stops 22).
Without further analysis, the foregoing will so fully reveal the
gist of the present invention that others can, by applying current
knowledge, readily adapt it for various applications without omitting
features which fairly constitute essential characteristics of the
generic and specific aspects of my contribution to the art and,
therefore, such adaptations should and are intended to be comprehended
within the meaning and range of equivalence of the claims. |