Abstrict A roll crusher includes a crusher roll; a support for rotatably
and radially shiftably supporting the crusher roll; a stationarily
supported countermember cooperating with the crusher roll to define
a crushing gap therewith; and a hydraulic setting system for radially
displacing the crusher roll for varying the crushing gap. The hydraulic
setting system includes a pressure source and a piston rod executing
strokes and having an end coupled to the roll support for transmitting
to the crusher roll setting forces derived from the pressure source.
Further, an abutment device is provided for limiting the strokes
of the piston rod to set a minimum magnitude of the crushing gap.
The abutment device includes an actuating mechanism for placing
the abutment device into a stroke-limiting state and into a piston
rod-releasing state.
Claims What is claimed is:
1. A roll crusher comprising
(a) a crusher roll;
(b) support means for rotatably and radially shiftably supporting
said crusher roll;
(c) a stationarily supported countermember cooperating with said
crusher roll to define a crushing gap therewith;
(d) a hydraulic setting system for radially displacing said crusher
roll for varying said crushing gap; said hydraulic setting system
including a pressure source and a piston rod executing strokes and
having an end coupled to said support means for transmitting to
said crusher roll setting forces derived from said pressure source;
and
(e) an abutment means for limiting the strokes of said piston rod
to set a minimum magnitude of said crushing gap; said abutment means
including actuating means for placing said abutment means into a
stroke-limiting state and into a piston rod-releasing state.
2. The roll crusher as defined in claim 1 wherein said abutment
means comprises a clamping head mounted on said piston rod; and
further wherein said actuating means comprises
(a) a clamping mechanism contained in said clamping head; said
clamping mechanism having a clamping position in which said clamping
head is clamped to said piston rod and a releasing position in which
said clamping head is slidable on said piston rod relative thereto;
and
(b) operating means for placing said clamping mechanism into one
of said positions thereof.
3. The roll crusher as defined in claim 2 wherein said hydraulic
setting system comprises a pressure limiting valve for limiting
a maximum pressure exerted on said piston rod when said clamping
mechanism is in said clamping position.
4. The roll crusher as defined in claim 2 wherein said clamping
mechanism comprises a spring contained in said clamping head and
surrounding said piston rod; said spring having a relaxed state
in which said spring clamps said piston rod against said clamping
head and a compressed state in which said spring releases said piston
rod from said clamping head; said operating means comprising a setting
piston slidably accommodated in said clamping head and energizing
means for shifting said setting piston to place said spring into
one of said states thereof.
5. The roll crusher as defined in claim 4 wherein said operating
means further comprises a work chamber defined in said clamping
head and bordered by said setting piston and hydraulic means for
pressurizing said work chamber.
6. The roll crusher as defined in claim 5 wherein said hydraulic
means forms part of said hydraulic setting system.
7. The roll crusher as defined in claim 2 wherein said hydraulic
setting system further includes a stationarily supported cylinder
having an inner space; said piston rod passing through said cylinder
and carrying a piston dividing said inner space into first and second
work chambers and valve means for establishing hydraulic communication
between said pressure source and said first and second work chambers
for displacing said piston rod; said clamping head being situated
on said piston rod externally of said cylinder and preventing movement
of said piston rod in a crushing gap-reducing direction when said
clamping mechanism is in said clamping position and said clamping
head is in an abutting relationship with said cylinder.
8. The roll crusher as defined in claim 7 wherein said piston
rod passes through said clamping head; further comprising a piston
rod head secured to said piston rod at an end thereof externally
of said clamping head; said piston rod head being countersupported
on said clamping head.
9. The roll crusher as defined in claim 8 further comprising a
compression spring interposed between and being in contact with
said piston rod head and said clamping head.
10. The roller crusher as defined in claim 1 wherein said abutment
means includes means for allowing said crushing gap to be increased
from said set minimum magnitude when said abutment means is in said
stroke-limiting state.
Description
CROSS REFERENCE TO RELATED APPLICATION
This application claims the priority of German Application Nos.
195 18 061.5 filed May 17 1995 and 195 22 251.2 filed Jun. 20
1995 which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
The invention relates to a roll crusher which may of the type that
has two oppositely rotated rolls spaced from one another by an adjustable
crushing gap. One of the rolls is radially adjustable (shiftable),
while the other roll (countermember) is stationarily supported.
The roll crusher may also be of the type which has a single, shiftable
roll cooperating with a crusher plate (countermember). In either
structure, the shiftable roll is connected with at least one piston
rod with the intermediary of a bearing housing and is displaceable
by a hydraulic system.
In roll crushers or roll mills of the above-outlined type the crushing
gap between the shiftable roll and the countermember (stationary
crusher roll or crusher plate) is conventionally set in such a manner
that the shiftable roll is mechanically or hydraulically displaced
and thereafter mechanically immobilized. Such a process is relatively
complex because the support and immobilizing systems for the shiftable
roll first have to be rendered accessible. Further, the gap setting
requires substantial skill as well as great care; these assets cannot
be assumed to necessarily characterize the operating personnel.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an improved roll crusher
of the above-outlined type which makes possible a simpler and operationally
safer setting of the roll gap (crushing gap) and also permits a
stepless remote adjustment.
This object and others to become apparent as the specification
progresses, are accomplished by the invention, according to which,
briefly stated, the roll crusher includes a crusher roll; a support
for rotatably and radially shiftably supporting the crusher roll;
a stationarily supported countermember cooperating with the crusher
roll to define a crushing gap therewith; and a hydraulic setting
system for radially displacing the crusher roll for varying the
crushing gap. The hydraulic setting system includes a pressure source
and a piston rod executing strokes and having an end coupled to
the roll support for transmitting to the crusher roll setting forces
derived from the pressure source. Further, an abutment device is
provided for limiting the strokes of the piston rod to set a minimum
magnitude of the crushing gap. The abutment device includes an actuating
mechanism for placing the abutment device into a stroke-limiting
state and into a piston rod-releasing state.
The invention may find application in twin-roll crushers having
oppositely rotated rolls as well as single-roll crushers having
only a single roll which is shiftably mounted and which cooperates
with a crusher plate.
The shiftable roll is connected, with the intermediary of a bearing
housing, with at least one piston rod whose stroke is limited by
a preferably hydraulically regulatable abutment device. The abutment
device serves not only for providing a mechanical securement based
on the principle of a counternut, but also makes possible individually
settable relative displacements of the piston rod which are easily
reproducible and may also be remote-controlled and thus automated.
The handling of the roll crusher is thereby significantly facilitated.
Further, the abutment device limits the piston stroke only in one
direction, that is, the abutment functions only to prevent the crusher
roll from assuming a distance from the countermember which is less
than the desired roll clearance while, by means of a spring support
or a hydraulic support, the shiftable roll may, as before, yield
in case of excessive loads.
According to an advantageous feature of the invention, a clamping
head, serving as the abutment device, is releasably immobilized
on the piston rod. The clamping head is an easily operable securing
element. According to a further advantageous feature of the invention,
the piston rod is passed through the bottom of a double acting hydraulic
cylinder which is connected to the roll crusher housing on which
the clamping head is countersupported. The double-acting cylinder
has two work chambers chargeable with a hydraulic fluid to provide
for a desired piston rod adjustment according to the crushing gap.
Such a hydraulic cylinder acts as a safety device against excessive
loads by permitting the piston rod to yield in case a predetermined
pressure value is exceeded. In such a case, the clamping head remains
in its immobilized position on the piston rod and after elimination
of the excessive load conditions, the piston rod is again moved
out to an extent until the clamping head abuts the hydraulic cylinder,
whereby the desired crushing gap has been reestablished.
According to a further advantageous feature of the invention, the
piston rod has, at one end, a head which engages the clamping head
either directly or with the interposition of an additional compression
spring.
According to a further feature of the invention, the maximum pressure
acting on the arrested piston rod is limited by a pressure limiting
valve, that is, the piston rod yields when a certain pressing force
exerted on the shiftable crusher roll is exceeded.
According to another feature of the invention, one of the work
chambers of the double-acting cylinder is hydraulically coupled
with a pressure accumulator whose bias pressure may be adjusted
for limiting the maximum crushing force.
The shiftable roll of the roll crusher may be connected with one
or more piston rods. In case a plurality of piston rods are used,
each piston rod is associated with separate respective hydraulic
cylinder units which are coupled to one another preferably by means
of a synchronous control mechanism.
It is possible in principle to provide a remote control for regulating
the biasing pressure of the clamping head and/or the double-acting
cylinder; such a control may be realized by a single hydraulic circuit.
By virtue of a conventional displacement measuring arrangement,
the position of the shiftable roll and thus indirectly the crushing
gap between the rolls may be measured, so that any desired crushing
gap may be remotely set and monitored.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic top plan view of a two-roll crusher and a
hydraulic circuit for controlling the motion of the shiftable roll
according to the invention.
FIG. 2 is a top plan view, on an enlarged scale, of a detail of
the structure shown in FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The two-roll crusher illustrated in FIG. 1 has a fixed roll 10
which is stationarily supported for rotation. Opposite ends of a
shiftable roll 11 are held in respective bearing housings 12 coupled
to piston rods 13 by means of which the shiftable roll 11 is radially
displaceable relative to the fixed roll (countermember) 10. Each
piston rod 13 is part of identically structured respective double-acting
cylinders 14 each having two cylinder chambers (work chambers)
15 and 16 which are separated from one another by a slidable piston
13a affixed to the piston rod 13 and which may be selectively charged
with a hydraulic fluid. The resulting pressure in the opposite work
chambers varies the axial position of the piston rod 13. As shown
in FIG. 2 the piston rod 13 is passed through the bottom 17 of
the associated double acting hydraulic cylinder 14 and has, at its
free end, a head 18 which is connected to the bottom 20 of a clamping
head 21 with the intermediary of a spring 19. The clamping head
21 has a setting piston 22 which is movable against the force of
a spring 23 situated between the setting piston 22 and the bottom
20 of the clamping head 21. When in the relaxed, expanded state,
the spring 23 locks the piston rod 13 to the clamping head 21 by
a wedging effect, whereas in an axially compressed state the spring
23 is released from the piston rod 13 so that the latter is shiftable
relative to the clamping head 21.
The cylinder chambers 15 and 16 as well as a clamping head chamber
24 may be charged with hydraulic fluid.
Since the two piston rods 13 operate in synchronism and are of
identical construction, the mode of operation and construction of
the hydraulic circuit will be discussed below in conjunction with
a single piston rod 13 and the clamping head 21 belonging thereto.
The position of the piston rod 13 may be set by pressurizing the
work chambers 15 and 16 by means of a valve 25 which establishes
a hydraulic connection between a pump 31 which draws hydraulic fluid
from a sump 32 and the work chambers 15 16. Before such an operation
is effected, a valve 26 is actuated which pressurizes the work chamber
24 of the clamping head 21 whereby the clamping head 21 is released
from the piston rod 13 by compressing the spring 23. When the desired
position of the piston rod 13 is reached, the work chamber 24 of
the clamping head 21 is depressurized, whereby the spring 23 again
expands and thus locks the piston rod 13 to the clamping head 21
which lies against the outer radial face of the cylinder 14 corresponding
to the position illustrated in FIG. 1.
A check valve 27 ensures that an oil leakage-free closing of the
cylinder chamber 15 is effected which is pre-pressurized via a valve
28. The pressure is limited to a maximum magnitude by a pressure
limiting valve 29. If the crushing forces exceed the set maximum
pressure, hydraulic fluid flows from the work chamber 15 through
the pressure limiting valve 29 into the work chamber 16 and, as
a result, the piston rod 13 is withdrawn into the cylinder 14 that
is, the piston rod 13 assumes its position approximately as shown
in FIG. 2. In such a position the shiftable roll 11 has greater
clearance from the stationary roll 10 than the set crushing gap.
The clamping head 21 remains firmly in its position relative to
the piston rod 13 and thus has moved away from the radial outer
face of the cylinder 14. To reset the desired clearance (crushing
gap), the valve 25 is actuated, whereby the pressure increases in
the work chamber 15 of the cylinder 14 until the piston rod 13 has
reached its position shown in FIG. 1 in which the clamping head
21 again abuts the outer radial face of the cylinder 14. During
renewed actuation the clamping head 21 remains in its closed (locking)
state. The settable pressure in the cylinder chamber 15 may be regulated
in a stepless manner by a valve 30.
The synchronous control of the two cylinders 14 and the two piston
rods 13 is effected in a conventional manner. Additionally, in the
cylinder chamber 15 the pressure may be monitored by means of a
sensor. If required, the cylinder chamber 15 may be coupled with
a non-illustrated accumulator which has an adjustable biasing pressure
for limiting the maximum crushing force.
It will be understood that the above description of the present
invention is susceptible to various modifications, changes and adaptations,
and the same are intended to be comprehended within the meaning
and range of equivalents of the appended claims. |