Title: Method for monitoring condition of bearings of a crusher, and a crusher
Abstract: Malfunctions of sliding bearings of cone crushers used in crushing stone are anticipated by providing sensors in connection to bearing parts, by means of which sensors it is possible to observe increases in friction forces. A beginning bearing damage can be detected by means of sensors at such an early stage, that extensive damage to bearings and to other parts of the crusher can be prevented.
Patent Number: 6,877,682 Issued on 04/12/2005 to Nieminen, et al.
| Inventors:
|
Nieminen; Ilpo (Siivikkala, FI);
Heikkila ; Juhamatti (Tampere, FI);
Patosalmi; Juha (Tampere, FI)
|
| Assignee:
|
Metso Minerals (Tampere) Oy (Tampere, FI)
|
| Appl. No.:
|
258178 |
| Filed:
|
December 9, 2002 |
| PCT Filed:
|
March 13, 2002
|
| PCT NO:
|
PCT/FI02/00198
|
| 371 Date:
|
December 9, 2002
|
| 102(e) Date:
|
December 9, 2002
|
| PCT PUB.NO.:
|
WO02/07747 |
| PCT PUB. Date:
|
October 3, 2002 |
Foreign Application Priority Data
| Current U.S. Class: |
241/36; 241/207 |
| Intern'l Class: |
B02C 002//04 |
| Field of Search: |
241/36,210,30,207
|
References Cited [Referenced By]
U.S. Patent Documents
| 3459378 | Aug., 1969 | Hill | 241/35.
|
| 3472046 | Oct., 1969 | Potter | 464/32.
|
| 4535942 | Aug., 1985 | Hayashi | 241/36.
|
| 4666092 | May., 1987 | Bremer | 241/214.
|
| 4787563 | Nov., 1988 | Tanaka et al.
| |
| 5451110 | Sep., 1995 | Gams et al. | 384/624.
|
| 5490431 | Feb., 1996 | O'Mahony et al. | 73/862.
|
| 5653393 | Aug., 1997 | Tanaka et al.
| |
| 5667157 | Sep., 1997 | Prew | 241/27.
|
| 5927623 | Jul., 1999 | Ferguson et al. | 241/36.
|
| 6360616 | Mar., 2002 | Halliday et al. | 73/862.
|
| Foreign Patent Documents |
| 100554 | Nov., 1997 | FI.
| |
Primary Examiner: Crane; Daniel C.
Attorney, Agent or Firm: Oliff & Berridge, PLC
Parent Case Text
This application is a 371 of PCT/FI02/00198, filed on Mar. 13, 2002.
Claims
What is claimed is:
1. A method for monitoring the condition of bearings in a cone or a
gyratory crusher and for decreasing damage caused by a deteriorated
bearing wherein friction force between bearing surfaces in a crusher is
monitored by a sensor, and information gained from the monitoring of the
friction force carried out by the sensor is used in an alerting or control
system of the crusher.
2. A method in accordance with claim 1, wherein the friction force between
bearing surfaces of the crusher is monitored by a sensor selected from the
group consisting of a piezoelectric sensor, a force sensor, a mechanical
sensor, a hydraulic sensor or a strain-gauge transducer.
3. A method in accordance with claim 1, wherein the friction force between
bearing surfaces is monitored by a sensor integrated in an adjusting
piston guide.
4. A method in accordance with claim 1, wherein a signal from one or more
sensors is analyzed and by comparing it to reference material previously
stored in a control system information is gained about which bearing
surface is being damaged.
5. A method in accordance with claim 2, wherein the friction force between
bearing surfaces is monitored by a sensor integrated in an adjusting
piston guide.
6. A method in accordance with claim 2, wherein a signal from one or more
sensors is analyzed and by comparing it to reference material previously
stored in a control system information is gained about which bearing
surface is being damaged.
7. A method in accordance with claim 3, wherein a signal from one or more
sensors is analyzed and by comparing it to reference material previously
stored in a control system information is gained about which bearing
surface is being damaged.
8. A method in accordance with claim 5, wherein a signal from one or more
sensors is analyzed and by comparing it to reference material previously
stored in a control system information is gained about which bearing
surface is being damaged.
9. A cone crusher comprising at least one sensor, which provides an output
signal indicating a friction force between bearing surfaces of the
crusher.
10. A crusher in accordance with claim 9, wherein the crusher is a gyratory
crusher.
11. A crusher in accordance with claim 9, wherein the sensor is selected
from the group consisting of a piezoelectric sensor, a force sensor, a
mechanical sensor, a hydraulic sensor or a strain-gauge transducer.
12. A crusher in accordance with claim 9, wherein the sensor is integrated
in an adjusting piston guide.
13. A crusher in accordance with claim 10, wherein the sensor is selected
from the group consisting of a piezoelectric sensor, a force sensor a
mechanical sensor, a hydraulic sensor or a strain-gauge transducer.
14. A crusher in accordance with claim 10, wherein the sensor is integrated
in an adjusting piston guide.
15. A crusher in accordance with claim 11, wherein the sensor is integrated
in an adjusting piston guide.
16. A crusher in accordance with claim 13, wherein the sensor is integrated
in an adjusting piston guide.
Description
TECHNICAL FIELD
This invention relates to cone and gyratory crushers. More specifically,
the invention relates to the monitoring of sliding bearings of a cone or
gyratory crusher so, that an incipient bearing failure can be detected at
such an early stage, that extensive damage to bearings and to other parts
of the crusher can be prevented.
BACKGROUND ART
In cone crushers there is a perpendicular eccentric shaft and in that shaft
an oblique inner bore. In the bore is fitted a main shaft, to which shaft
a crushing head is usually attached. The head is laterally surrounded by
the crusher frame, to which frame is attached a concave, functioning as a
wear part. To the head is correspondingly attached a mantle, functioning
as a wear part. The mantle and the concave together form a crushing
cavity, and within this, feed material is crushed. When the eccentric
shaft is rotated, the main shaft together with the head is forced into an
oscillating movement, whereby the gap between the mantle and the concave
varies at each location during the work cycle. The smallest gap during a
work cycle is called the crusher setting, and the difference between
maximum gap and minimum gap is called the crusher stroke. By means of the
crusher setting and the crusher stroke, e.g. the particle size
distribution of produced crushed stone and the production capacity of the
crusher can be controlled.
The main shaft of a crusher is often supported in the crusher frame by a
top bearing at its upper end. This subtype of cone crusher is usually
referred to as a gyratory crusher.
A gyratory crusher is usually adjustable by a hydraulic system thus, that
the main shaft can be moved vertically relative to the crusher frame. This
makes possible a change of the setting so, that the particle size of
crushed stone will conform to the required size, and/or keeping the
setting constant during wearing of the wear parts.
In other types of cone crushers, the adjustment can be made also by raising
and lowering the upper crusher frame and the concave attached to it
relative to the lower crusher frame and to the main shaft, which remains
vertically stationary relative to the lower frame.
In a crusher there are many surfaces associated by sliding bearings.
Depending on the type of crusher these include, for example, surfaces
between:
main shaft and eccentric shaft
eccentric shaft and lower frame
eccentric shaft and adjusting piston
main shaft and upper frame
main shaft and adjusting piston
The above-mentioned members are not usually in immediate contact with each
other, but in practice there are usually one or more bearing sleeves
between them, so the actual bearing surfaces usually form between the
above-mentioned members and these bearings.
When the bearings of a crusher work properly, friction forces between the
crusher bearing surfaces are minimal. If a crusher is affected by a
disturbance in lubrication, the friction forces between bearing surfaces
will increase and the bearings will be in danger of seizure. This kind of
disturbances can be, for example, crusher overload, contaminants in
lubricating oil, or pressure or flow decrease of lubricating oil.
Seizure damage has a tendency to advance in a crusher from one bearing
surface to another. Lets assume, for example, that there is a disturbance
in the lubrication between the main shaft and the eccentric shaft of a
crusher and the mentioned bearing surfaces start to seize. This causes
heating of the eccentric shaft. When the heat is conducted to the bearing
surface between the eccentric shaft and the crusher frame, the lubrication
of this bearing surface can also be impaired, which causes also this
bearing surface to start to seize.
The seizure described in this example can also advance in the opposite
direction from one bearing surface to another, or it can also advance
between other bearing surfaces.
The case described as an example can lead also to a situation, where the
bearings of a crusher along with the main parts of a crusher, such as the
frame, the main shaft, the eccentric shaft etc. are completely damaged.
Repair costs of this kind of total damage are difficult to estimate,
because the costs differ greatly from case to case depending on, for
example, the crusher type. On an average, the costs may be about between
EUR 20 000-50 000 (at year 2000 prices). In addition, the stoppage of a
crusher causes considerable costs.
In Finnish patent 100554, a method is disclosed for monitoring the
condition of crusher bearings by monitoring the rotation speed of a main
shaft around its axis. When the gap of a crusher is full of stones, these
stones will decrease the rotation speed of the head and the main shaft.
Thus, a relatively large increase in friction between the main shaft and
the eccentric shaft is necessary before a change in the rotation speed of
the main shaft can be detected. At this point, the damage at the sliding
surface between the eccentric shaft and the main shaft has already
advanced relatively far.
DETAILED DESCRIPTION OF THE INVENTION
General Description
If an increase of friction forces at the bearing surfaces of a crusher can
be detected early enough, it will give an indication of a beginning
seizure. Then it is possible to create a procedure to inform the crusher
operator about the disturbance. In its simplest form, such an alarm system
can be, for example, a light or sound signal. It is also possible to
connect the mentioned indication to the control system for the crusher or
the whole crushing process thus, that the initial failure will control the
crusher or the crushing process in order to keep the damage as small as
possible. The indication can be arranged, for example, to:
open the overpressure valve of the crusher, which will cause the crusher
setting to increase quickly and the bearing load to decrease
disengage the crusher power transmission coupling, which will cause the
crusher to stop and the bearing load to decrease
stop the crusher drive motor, which will cause the crusher to stop and the
bearing load to decrease
shorten the stroke of the crusher, which will cause the bearing load to
decrease
stop the crusher feeder, which will decrease the load of the crusher and
the bearings when the crusher becomes empty.
When a beginning seizure can be detected early, the damage cannot advance
from one bearing surface to another. It is sufficient to change detachably
fitted bearing sleeves or other similar bearing members and to grind the
corresponding surface on the major crusher parts. Repair costs are then
only about 10-20% of the repair costs caused by total damage. Also the
production losses of a crushing plant will decrease because of shorter
stoppage. If damage is detected early enough and the damage remains
minimal, it is in certain circumstances even possible to postpone repair
of the damage to a normal maintenance break.
DETAILED DESCRIPTION
The invention is described in detail in the following with references to
the enclosed drawings, wherein
FIGS. 1 and 2 represent typical gyratory crushers in accordance with the
state of the art,
FIG. 3 represents a typical cone crusher in accordance with the state of
the art,
FIG. 4 is an enlarged cross-section bottom view of a detail from the
crusher of FIG. 1, also showing forces appearing in bearings and their
behavior,
FIG. 5a is an enlarged representation of an embodiment of the invention
applied in the bottom section of the crusher of FIG. 1,
FIG. 5b is an enlarged representation of an embodiment of the invention
applied in the top section of the crusher of FIG. 1,
FIG. 6a is an enlarged representation of an embodiment of the invention
applied in a bottom section of the crusher shown in FIG. 2,
FIG. 6b is an enlarged representation of an embodiment of the invention
applied in a top section of the crusher shown in FIG. 2, and
FIG. 7 is an enlarged representation of an embodiment of the invention
applied in the crusher shown in FIG. 3.
The main parts of the crusher shown in FIG. 1 are lower frame 1, upper
frame 2, main shaft 3, head 4, concave 5, mantle 6, crushing cavity 7,
transmission 8, eccentric shaft 9, adjusting piston 10, adjusting piston
guide 11, axial bearing 12 of the eccentric shaft, radial bearing 13 of
the eccentric shaft, axial bearing 14, 15, 16 of the main shaft, radial
bearing 17 of the main shaft, main shaft protecting sleeve 18, and support
bearing 19.
The crusher frame consists of two main units: lower frame 1 and upper frame
2. The concave 5 attached to the upper frame and the mantle 6 attached by
means of head 4 to the main shaft 3 forms the crushing cavity 7, into
which material to be crushed will be fed from top of the crusher.
Transmission 8, by means of which the eccentric shaft 9 is rotated, is
mounted in the lower frame. In the eccentric shaft there is a bore at
slanted angle in relation to the crusher central axis, into which bore the
main shaft is fitted. When the transmission rotates the eccentric shaft
inside the crusher frame, it causes an oscillating movement in the main
shaft fitted in the bore in the eccentric shaft.
The crusher setting is adjusted by pumping hydraulic medium into a space
between the adjusting piston 10 and the lower frame. In this application,
the adjusting piston of the crusher is shaped as a cylinder, open at its
upper end and closed at its bottom end, and the hem of the adjusting
piston fits between the lower frame of the crusher and the eccentric
shaft.
Between the main shaft and the eccentric shaft is the radial bearing 17 of
the main shaft, which bearing conveys radial forces affecting the main
shaft to the crusher frame. Between the eccentric shaft and the adjusting
piston is the radial bearing 13 of the eccentric shaft, carrying out the
same task. The axial bearing 12 of the eccentric shaft conveys axial
forces between the eccentric shaft and the lower frame.
In the outer surface of the adjusting piston there is a groove, into which
is fitted the adjusting piston guide 11, attached to the lower frame of
the crusher. The task of the guide is to prevent rotation of the adjusting
piston inside the frame of the crusher due to friction forces in the
radial bearing of the eccentric shaft and the axial bearing of the main
shaft. The prevention of rotation is important, because in this way a
sufficiently high relative speed is achieved in parts moving in respect to
each other, so that a lubrication film will form.
Axial forces of the main shaft are conveyed to the crusher frame through
pressurized hydraulic medium and the axial bearing 14, 15, 16 of the main
shaft. In this application the axial bearing consists of three separate
parts, whereby at least two of those parts have counter-surfaces which are
part of a spherical surface.
Radial forces of the main shaft are conveyed to the upper frame of the
crusher through the support bearing 19. Usually, a main shaft protection
sleeve is provided in crushers to protect the main shaft from the wearing
effect of the material to be crushed.
The same main crusher parts shown in FIG. 1 appear in the crusher shown in
FIG. 2. The crusher setting is adjusted by pumping hydraulic medium into a
space between the adjusting piston 10 and the lower frame. In this
application, the adjusting piston is located wholly below the main shaft,
and it does not function as a member conveying radial forces of the main
shaft to the lower frame of the crusher.
The main parts of the crusher shown in FIG. 3 are frame 20, bowl 21, main
shaft 3, head 4, concave 5, mantle 6, crushing cavity 7, transmission 8,
eccentric shaft 9, adjusting motor 22, adjustment ring 23, axial bearing
12 of the eccentric shaft, radial bearing 13 of the head, axial bearing
24, 25, 26 of the head, and radial bearing 17 of the main shaft. The
concave 5 attached to bowl 21 and mantle 6 attached to head 4 form the
crushing cavity 7, into which material to be crushed will be fed from top
of the crusher.
In the lower frame is placed transmission 8, by means of which the
eccentric shaft 9 is rotated. In the eccentric shaft, there is a bore,
into which main shaft 3, which is fixed to the frame of the crusher, is
fitted. When the transmission rotates the eccentric shaft around the main
shaft, it brings the head, which is connected at the main shaft through
bearings, into an oscillating movement.
The setting of the crusher is adjusted by rotating the bowl 21 with the
adjusting motor 22, which will cause the bowl to rise or lower itself
along the threads of the adjustment ring 23.
Between the main shaft and the eccentric shaft there is the radial bearing
17 of the main shaft, which bearing conveys radial forces of the head to
the crusher frame. Between the eccentric shaft and the head there is the
head radial bearing 13, having the same function. The axial bearing 12 of
the eccentric shaft conveys axial forces between the eccentric shaft and
the frame of the crusher.
Axial forces of the head are conveyed to the frame of the crusher through
head axial bearing 24, 25, 26. In this application, the axial bearing
consists of three separate parts, at least two of those parts having
counterpart surfaces, which are part of a spherical surface.
Radial forces of the head are conveyed through the radial bearing 17 of the
main shaft to the main shaft and further to the frame of the crusher.
FIG. 4 represents a horizontal cross-section of a lower part of the crusher
shown in FIG. 1. The main parts shown are lower frame 1, main shaft 3,
eccentric shaft 9, adjusting piston guide 11, radial bearing 13 of the
eccentric shaft, and radial bearing 17 of the main shaft.
The figure also shows the following forces appearing in a crusher:
a radial component F.sub.L of a force acting on the frame of the crusher
from the main shaft while material is being crushed
a friction force F.sub..mu.1 caused by the force F.sub.L at the surface
between the main shaft and the radial bearing of the main shaft
a friction force F.sub..mu.2 caused by the force F.sub.L at the surface
between the eccentric shaft and the radial bearing of the eccentric shaft
a torque M caused by the friction forces F.sub..mu.1 and F.sub..mu.2 and
acting on the adjusting piston
a reaction force F, created by the adjusting piston guide and opposing the
torque M, which force F prevents the adjusting piston from revolving.
From the main shaft is conveyed the force F.sub.L, which causes friction
forces F.sub..mu.1 and F.sub..mu.2, of which the first is a friction force
between the main shaft and the radial bearing of the main shaft, and the
second is a friction force between the eccentric shaft and the radial
bearing of the eccentric shaft. In a normal lubrication situation, the
friction coefficient is very small, for example 0,001, which causes the
friction force to be also very small.
If the lubrication situation deteriorates, the friction coefficient will
increase dramatically and with it the friction force, for example 10 . . .
100 times. Bearing friction causes the torque M at the adjusting piston,
which torque is countered by the support reaction F of the adjusting
piston guide. By measuring the force F or its effects, information about
bearing friction forces can be attained. By simultaneously observing the
power used by the crusher, the crusher setting, and the control pressure
of the crusher, a fair apprehension of the load situations of different
bearings can be gained. If the load and lubrication situation of the
bearings turns critical, the damage can be prevented or minimized by
controlling the crusher or the material feed, for example by decreasing or
halting the input of feed material, by enlarging the crusher setting, by
stopping the crusher, or by giving the crusher operator an alert, based on
which the operator decides what actions should be taken to eliminate the
problem.
In FIG. 5a is represented the lower part of a crusher which is of the type
shown in FIG. 1, and which includes, among other things, an eccentric
shaft 9, an adjusting piston 10, an axial bearing 12 of the eccentric
shaft, a radial bearing 13 of the eccentric shaft, an axial bearing 14,
15, 16 of the main shaft, and a radial bearing 17 of the main shaft as
well as sensors 27 and 28. In a crusher in accordance with FIG. 5a, the
reaction force of the torque caused by sensor 27 and affecting the
adjusting piston 10 is observed by sensor 27. If the sensor detects an
increase in the reaction force, it is a sign of a beginning damage at
radial bearing 13 of the eccentric shaft, or the axial bearing 17 of the
main shaft. The sensor is fitted in the adjusting piston guide 11. The
reaction force of a torque caused by the eccentric shaft and acting on the
axial bearing 12 of the eccentric shaft is observed by sensor 28. If the
sensor detects an increase in the reaction force, it is a sign of
beginning damage at the axial bearing of the eccentric shaft.
In FIG. 5b is represented the upper part of a crusher which is of the same
type as the one shown in FIG. 1, and which includes among other things a
main shaft 3, a support bearing 19 and a sensor 29. In a crusher in
accordance with FIG. 5b, the reaction force of a torque caused by sensor
29 and affecting the support bearing is observed by sensor 29. If the
sensor detects an increase in the reaction force, it is a sign of
beginning damage at the support bearing.
In crushers equipped in accordance with FIGS. 5a and 5b can, for example,
the shape of the following bearing surfaces be controlled by sensors:
bearing surfaces of the axial bearing combination 14, 15, 16
eccentric shaft 9--axial bearing 12 of the eccentric shaft
eccentric shaft 9--radial bearing 13 of the eccentric shaft
main shaft 3--support(top) bearing 19.
FIG. 6a represents the lower part of a crusher of the same type as the one
shown in FIG. 2 and in accordance with the present invention, and which
includes, among others, a main shaft 3, an eccentric shaft 9, an adjusting
piston 10, an axial bearing 12 of the eccentric shaft, a radial bearing 13
of the eccentric shaft, an axial bearing 14, 15, 16 of the main shaft, a
radial bearing 17 of the main shaft, and sensors 29 and 30. In FIG. 6b is
similarly represented the upper part of a crusher in accordance with the
present invention, which includes among others a main shaft 3, a support
bearing 31, 32, and a sensor 33.
In a crusher in accordance with FIG. 6a, the reaction force of a torque
caused by sensor 29 and directed at the radial bearing of the eccentric
shaft, is monitored by means of sensor 29. If the sensor detects an
increase in the reaction force, it is a sign of a beginning damage in the
radial bearing of the eccentric shaft. By means of sensor 30, a reaction
force of a torque, caused by the sensor and directed at the adjusting
piston, is monitored. If the sensor detects an increase in the reaction
force, it is a sign of a beginning damage in the axial bearing of the main
shaft.
In a crusher in accordance with FIG. 6b, the reaction force of a torque
caused by sensor 33 and directed at the support bearing 31, 32 is
monitored by means of sensor 33. If the sensor detects an increase in the
reaction force, it is a sign of a beginning damage in the support bearing.
In a crusher in accordance with FIG. 2 and equipped in accordance with FIG.
6, the following bearing surfaces, for example, can be monitored by
sensors:
the bearing surfaces of a bearing combination 14, 15, 16 of the main shaft,
eccentric shaft 9--axial bearing 12 of the eccentric shaft,
eccentric shaft 9--radial bearing 13 of the eccentric shaft,
bearing surfaces 3, 26, 27, 2 between the support bearing combination, the
frame, and the main shaft.
FIG. 7 is a representation of the middle part of a crusher in accordance
with FIG. 3 and equipped with sensors placed in accordance with the
present invention. The figure shows, among others, main shaft 3, head 4,
eccentric shaft 9, axial bearing 12 of the eccentric shaft, radial bearing
13 of the head, axial bearing 24, 25, 26 of the head, radial bearing 17 of
the main shaft, and sensors 34, 35, 36 and 37.
In a crusher in accordance with the FIG. 7, the reaction force of a torque
caused by sensor 34 and acting on the axial bearing of the eccentric shaft
is monitored by sensor 34. If the sensor detects an increase in the
reaction force, it is a sign of a beginning damage in the axial bearing of
the eccentric shaft. By means of sensor 35, the reaction force of a torque
caused by the head and aimed at the axial bearing of the head, is
monitored. If the sensor detects an increase in the reaction force, it is
a sign of a beginning damage in the axial bearing of the head. By means of
sensor 36, the reaction force of a torque caused by the main shaft and
acting on the radial bearing of the main shaft, is monitored. If the
sensor detects an increase in the reaction force, it is a sign of a
beginning damage in the radial bearing of the main shaft. By means of
sensor 37, the reaction force of a torque caused by the sensor and acting
on the radial bearing of the head is monitored. If the sensor detects an
increase in the reaction force, it is a sign of a beginning damage in the
radial bearing of the head.
The sensors 36 and 37 are not in a fixed position with respect to the
crusher, but sensor 36 moves with the eccentric shaft and sensor 37 moves
with the head. Therefore, the transfer of the sensor signal from the
sensor to the outside of the crusher requires special arrangements.
However, this function can be accomplished with a slip ring or with a
transmitter connected to the sensor and a receiver located outside of the
crusher.
In a crusher in accordance with FIG. 7, for example, the following bearing
surfaces can be monitored by sensors:
the bearing surfaces of the axial bearing combination 24, 25 of the head,
the bearing surfaces between the frame 20 and the eccentric shaft 9,
main shaft 3--radial bearing 17 of the main shaft,
eccentric shaft 9--radial bearing 13 of the head.
The present invention is not restricted to any particular sensor
technology. Monitoring the condition of a bearing can be based not only on
measuring a force, but also on measuring a dislocation or, for example, on
measurement of a surface pressure. In addition to a force, a bending
moment can also be measured as well as a distortion caused by it.
Therefore, for example, a piezoelectric sensor, a force sensor, a
mechanical sensor, a pressure sensor or a strain-gauge transducer can be
used as a sensor.
From the point of view of the invention, it is insignificant in which
manner the sensor indicates damage: the indication can be transferred
mechanically, hydraulically or electrically. Monitoring can be based not
only on the direct monitoring of a bearing, but also on indirect
monitoring, through some other part.
*
