Abstrict A jaw crusher for crushing rocks combines a hydraulic adjustment
of the bite with an air spring tensioning arrangement which maintains
a desired tensile force even with variation of the bite. The air
spring arrangement is reliable in the dirty environment and also
has long life. The use of several air springs in combination with
a pressure sensing arrangement adds a safety factor. The more consistent
tensioning force allows adjustment of both the tensioning arrangement
and the bite of the rock crusher during operation thereof.
Claims The embodiments of the invention in which an exclusive property
or privilege is claimed are defined as follows:
1. A jaw crusher for crushing rock having a fixed jaw mounted on
a frame and a movable jaw mounted on said frame and connected to
a drive for cyclable movement of said movable jaw toward and away
from said fixed jaw, said movable jaw and said fixed jaw adjacent
a lower edge of said movable jaw being spaced and define a bite
therebetween, said bite between said jaws being variable by adjusting
a double acting hydraulic cylinder arrangement extending between
the lower edge of said movable jaw and said frame, said hydraulic
cylinder arrangement allowing movement of said movable jaw from
a narrow bite position between said jaws to an open bite position
which allows removal of obstructing material between said jaws,
said jaw crusher further including a tensioning arrangement for
biasing said movable jaw against said double acting hydraulic cylinder
and accommodating the cyclable movement of said movable jaw, said
tensioning arrangement including at least one tensioning rod having
one end thereof connected to said lower edge of said movable jaw
and an opposite end cooperating with a biasing member applying a
tensile force on said at least one tensioning rod to bias said movable
jaw, and wherein said biasing member is an air spring structure.
2. A jaw crusher as claimed in claim 1 wherein said air spring
structure includes at least two air springs.
3. A jaw crusher as claimed in claim 2 wherein each air spring
includes an auxiliary air pressure vessel connected to said air
spring to modulate the operating pressure range of the air spring
while accommodating the cyclable movement of said air spring in
sympathy with the cyclable movement of said movable jaw.
4. A jaw crusher as claimed in claim 1 wherein said at least one
tensioning rod is two spaced tensioning rods with the ends of said
tensioning rods remote from said movable jaw being structurally
connected by a common header, and wherein said air spring structure
applies said bias to said tensioning rods using said common header
as an intermediary transfer member.
5. A jaw crusher as claimed in claim 4 wherein said header includes
a support arrangement accommodating movement of said header generally
along the longitudinal axis of said tension rods and supporting
said header against downward pivoting movement.
6. A jaw crusher as claimed in claim 5 wherein said air spring
structure includes two side by side air springs acting on said header
and located between said tension rods.
7. A jaw crusher as claimed in claim 6 wherein each of said air
springs is connected to an air pressure supply having a volume equal
to or greater than the volume of the air spring to modulate the
operating pressure of the air spring.
8. A jaw crusher as claimed in claim 1 wherein said tensioning
arrangement includes at least two air springs and each air spring
includes a connected pressure supply tank to modulate the operating
pressure of the air spring.
Description FIELD OF THE INVENTION
The present invention relates to jaw crushers for crushing rock
and in particular, relates to an improved system for applying a
tensile force to the tension rods of a jaw crusher.
BACKGROUND OF THE INVENTION
In conventional jaw crushers, a moving jaw is supported at its
lower end by a plate type structure which is commonly known as a
toggle plate. The upper end of the moving jaw is controlled by an
elliptical drive, causing the jaw to move back and forth, relative
to a fixed jaw. The jaw crusher can be a single toggle design or
a double toggle design.
Our U.S. Pat. No. 4927089 which is incorporated herein by reference,
discloses a hydraulic control system which replaces the rigid toggle
plate of the prior art. This hydraulic control arrangement allows
adjustment of the bite between the moving jaw and the fixed jaw.
With the hydraulic control arrangement adjustment of the bite can
be carried out during operation of the rock crusher. Such adjustment
is desirable to maintain a desired throughput through the rock crusher,
and this throughput varies as a function of the amount of material
received and the type and size of the material. The adjustable bite
provides the operator with an on the fly adjustment that directly
affects the throughput of the rock crusher and also simplifies clearing
of the rock crusher in the event of a non-crushable material becoming
lodged in the bite.
The hydraulic ram disclosed in our patent is a double acting arrangement
and includes a safety relief arrangement in the event of a non-crushable
material being encountered.
Adjustment of the hydraulic control arrangement to vary the bite
also varies a tensioning arrangement of the jaw crusher. The tensioning
arrangement includes two coil springs used to apply a force on tension
rods of the rock crusher attached near the base of the movable jaw.
Although it would be desirable to have a constant tensioning force,
adjustment of the hydraulic cylinders causes a change in the tensioning
force. This can be corrected by manually adjusting adjustment nuts
at the end of the tension rods, however, this is typically not practical
with the rock crusher in operation. There have been proposals to
use hydraulic cylinders for maintaining a constant tensioning force,
however, these systems often have not proven entirely satisfactory,
and appreciably add to the cost of the system.
SUMMARY OF THE INVENTION
A jaw crusher for crushing rock, according to the present invention,
has a fixed jaw mounted on a frame and a moveable jaw mounted on
the frame and connected to a drive for cyclical movement of the
moveable jaw toward and away from the fixed jaw. The moveable jaw
and the fixed jaw adjacent a lower edge of the moveable jaw are
spaced and define a bite therebetween. The bite between the jaws
is variable by adjusting a double acting hydraulic cylinder extending
between the lower edge of the moveable jaw and the frame. The hydraulic
cylinder arrangement allows movement of the movable jaw from a narrow
bite position between the jaws to an open bite position which allows
removal of obstructing material between the jaws. The jaw crusher
further includes a tensioning arrangement for biasing the moveable
jaw against the double acting hydraulic cylinder and accommodating
the cyclical movement of the moveable jaw. The tensioning arrangement
includes at least one tensioning rod having one end thereof connected
to the lower edge of said moveable jaw and an opposite end cooperating
with a biasing member applying a tensile force on said at least
one tensioning rod to bias said moveable jaw where the biasing member
is an air spring structure.
According to an aspect of the invention, the air spring structure
includes at least two air springs.
According to a further aspect of the invention, each air spring
includes an auxiliary pressure vessel connected to pressurize the
air spring to modulate the operating pressure of said air spring
while accommodating the cyclical movement of said air springs in
sympathy with the cyclical movement of said moveable jaw.
According to yet a further aspect of the invention, two spaced
tensioning rods are provided with the ends of said tensioning rods
remote the removable jaw being connected by a yoke arrangement biased
by said air spring structure. The air spring structure applies the
bias force to said tensioning rods using said common header as an
intermediary transfer member.
According to yet a further aspect of the invention, the header
includes a support structure accommodating movement of the header
generally along the longitudinal axis of the tension rods and supporting
the header against downward pivoting movement.
According to yet a further aspect of the invention, the air spring
structure includes two side by side air springs acting on said header
and located in a non coaxial manner relative to such tension rods.
According to yet a further aspect of the invention, each air spring
is connected to an air pressure supply vessel that modulates the
operating pressure of the air spring regardless of the bite position
of said moveable jaw.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention are shown in the drawings,
wherein:
FIG. 1 is a schematic side elevation showing the rock crusher with
a narrow bite;
FIG. 2 is the view similar to FIG. 1 with the jaws in an open
position;
FIG. 3 is a schematic perspective view of the double acting hydraulic
cylinder arrangement;
FIG. 4 is a partial top view showing the tensioning arrangement
according to one embodiment;
FIG. 5 is a partial side view showing the structure of FIG. 4;
FIG. 6 is an end view of the embodiment of FIG. 4; and
FIG. 7 is a top view showing an alternate air spring tensioning
arrangement .
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The jaw crusher 2 schematically shown in FIGS. 1 and 2 is of
a single toggle design and has a frame 4 a fixed jaw 6 and a moveable
jaw 8. A bite 9 which is the spacing between the moveable jaw and
the fixed jaw, is controlled by the double acting hydraulic cylinders
10 and 12. It can be seen that one end of these double acting hydraulic
cylinders is lodged against the frame and the opposite end is in
engagement with the lower edge of the moveable jaw. This double
acting hydraulic cylinder arrangement as shown in FIG. 3 replaces
a stationary toggle plate and wedge members of a conventional jaw
crusher. Tension rods 18 extend rearwardly from the lower edge of
the moveable jaw and cooperate with tensioning arrangements 24.
The tensioning arrangement 24 includes tie rods 19 which form a
continuation of the tension rods 18.
The eccentric drive 20 causes a cyclical movement of the moveable
jaw 8 towards and away from the fixed jaw, as well as limited vertical
motion. The double acting hydraulic cylinders, in combination with
a nose bearing member 14 and the rear bearing member 16 accommodate
this movement of the moveable jaw while maintaining a particular
operating bite 9 between the moving jaw and the fixed jaw 6. During
operation of the rock crusher, the operator can adjust the double
acting hydraulic cylinders to vary the particular bite. It should
be noted that some variation of the bite occurs due to the cyclical
movement, but the size of the bite is controlled by the double acting
hydraulic cylinders. The cyclical movement of the moveable jaw is
indicated by the arrows 22. These are exaggerated, but generally
describes the action.
The tensioning arrangement 24 applies a bias force, urging the
lower edge 7 of the movable jaw to maintain contact with the hydraulic
cylinders 10 and 12. The tensioning arrangement provides a net force
on the tensioning rods 18 as indicated by the arrow 23. The tensioning
arrangement as shown in FIG. 4 includes tie rods 19 attached to
a header 32. The header 32 is biased in the direction 23 by air
springs 30. The air springs contact a fixed part of the frame of
the crusher bias the header 32. These air springs are positioned
in a non-coaxial manner relative to the rods 19. This is in contrast
to conventional coil springs which sleeve tension rods in a conventional
rock crusher. The structure of the air spring is simplified by using
an air spring which does not sleeve the tie rod. The tensioning
arrangement with the header acting on each air spring serves to
distribute the forces to both air springs.
FIGS. 5 and 6 show additional details of the tensioning arrangement
of FIG. 4. The two tie rods 19 are connected by the common header
member 32 which is mechanically fastened by bolts, for example,
to the ends of the tie rods 19 as clearly shown in FIG. 5. The two
air springs 30 each have three stages. Each air spring is located
between the header and a hinged plate member 44 pivotally attached
to the fixed frame of the crusher. The header also includes wheels
50 which move within the track 52 and support the tie rods 19 against
downward pivoting movement. The cyclical movement of the moving
jaw moves the header back and forth in the track 52. The actual
extent of movement is smaller than the length of the track, however,
the track has been sized to accommodate the various operating positions
of the moveable jaw, which positions are controlled by the bite
setting of the hydraulic cylinders.
As shown in FIG. 5 each air spring 30 is connected to an air supply
tank 40. The air springs are maintained within a desired pressure
range and the air tank 40 basically increases the volume of pressurized
air and modulates the operating pressure, such that the cyclical
movement of the moving jaw and the adjustable movement caused by
the hydraulic cylinders will not produce wide variations in the
operating pressure of the air springs. In this way, the tensioning
force exerted by the air springs is within a desired range and is
not unduly affected either by the particular bite set by the hydraulic
cylinders, nor the cyclical movement of the moveable jaw. Fortunately,
the air springs 30 are quite tolerant with respect to lateral misalignment,
and therefore, the exact mounting structure of the air springs is
not as critical.
FIG. 7 shows an alternate tensioning arrangement which can be used
with a rock crusher having tension rods 18 generally centrally located,
as opposed to either side of the rock crusher. An additional yoke
33 connects
tension rods 18 to tie rods 19. The location of the tension rods
and the number of tension rods vary depending on the manufacturer.
The header arrangement allows the position and number of tension
rods to remain the same. Typically, for a retrofit application,
the tension rods are shortened or replaced, however, the location
of the connection to the removable jaw remains unchanged. Shortening
of the tension rods allows locating of the air springs in the general
location where conventional coil springs would be located.
The air springs operate extremely well in the generally dirty environment
of a rock crusher. As can be appreciated, there is a lot of abrasive
dust produced in the crushing of rock, and the air springs are not
adversely affected by these conditions. With this arrangement, the
air springs can provide a tensioning force on the tension rods which
is maintained in a desired range, while accommodating different
operating positions of the moveable jaw and the cyclical movement
of the jaw. The air springs accommodate to a hydraulic cylinder
stroke of approximately 8 inches. The actual effective adjustment
of the moveable jaw is normally about 7 inches to assure that there
is a cushion of hydraulic oil between the piston and an end of the
cylinder. The three stage air springs, which are shown, have proven
quite satisfactory. The operating pressure of the air spring and
the tank is 50 to 90 psi. More commonly, the operating range is
70 to 90 psi. The number of air springs and the size thereof are
selected according to the structure and capacity of the particular
jaw crusher. The tank associated with each air spring, has a volume
at least two times, and preferrably two and one half times the volume
of the air spring.
The air pressure tank 40 also includes controls for adjusting the
air pressure. In this way the operator can, if necessary, adjust
the pressure of the air springs at a position remote the tension
rods during operation of the rock crusher. Furthermore, the tension
force exerted by the air springs is not as sensitive to changes
in length of the air spring relative to conventional springs. Each
tank includes a pressure sensing arrangement 70 which can include
warning signals if the sensing pressure is not in a desired range.
A pressure relief valve can also be included.
The air spring arrangement has improved operating characteristics,
allows adjustment during running of the rock crusher, is cost effective
and extremely tolerant of the work environment.
Although various preferred embodiments of the present invention
have been described herein in detail, it will be appreciated by
those skilled in the art, that variations may be made thereto without
departing from the spirit of the invention or the scope of the appended
claims. |