Solid material comminution or disintegration – Apparatus – With automatic control
Patent
1994-01-31
1996-12-03
Husar, John M.
Solid material comminution or disintegration
Apparatus
With automatic control
241 36, B02C 200, B02C 2500
Patent
active
055800033
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method for controlling a gyratory crusher so as to maintain a substantially constant crushing gap or to adjust the particle size distribution of the crushed goods, or both to maintain a substantially constant crushing gap and to adjust the particle distribution of the crushed goods.
The invention relates to a gyratory crusher having a crushing head with a first crushing shell, and a second crushing shell defining, together with the first crushing shell, a crushing gap whose width is adjustable by changing the relative position of the first and the second crushing shell in the axial direction by means of a hydraulic adjusting device, the material to be crushed being introduced into the crushing gap and a driving device causing the crushing head to execute a gyratory pendulum movement.
In the operation of such gyratory crushers, the crushing head is so adjusted that a certain predetermined width of the gap between the first, inner crushing shell and the second, outer crushing shell is obtained. The adjustment operation is performed manually and in such a manner that there is a certain safety margin up to maximum permissible crusher load. Since the load on the crusher will vary during the crushing operation, too narrow a gap would involve the risk of overload on the crusher with ensuing damage. As crushing proceeds, the shell surfaces are worn, which increases the gap width, thereby reducing productivity. To counteract this development, the axial position of the crushing head is adjusted gradually, either manually or automatically, to obtain the gap width as originally set.
Swedish Patent Specification 8601504-7 (SE-B-456,798) teaches a method for controlling such a gyratory crusher in order to avoid damage caused by caking in the crushing chamber between the outer and the inner crushing shell. Caking may arise if the material is supplied incorrectly or if the composition of the material supplied is not right (e.g. if the material contains too much moisture or too many pieces of stone which are harder than the remaining material). Thus, caking may cause high, but brief load peaks resulting in brief pressure increases, so-called pressure surges. Prior-art crushers are therefore equipped with a load-relieving system dealing with such temporary load peaks. In the above Swedish patent, such a system for dealing with temporary load peaks is combined with adjustment based on a determined value of the number of pressure surges in the hydraulic fluid of the adjusting device that exceed a predetermined pressure level in a given period of time, the relative position of the crushing shells being changed depending on this value to increase the width of the crushing gap if the calculated number of pressure surges exceeds a predetermined sum.
PCT Publication WO87/01305 discloses a readjustment of the width of the crushing gap by now and then bringing the crushing shells together to obtain a reference value for the subsequent adjustment of the crushing gap during the next operational period. Thus, this publication merely describes conventional calibration of a cone crusher during a crushing operation.
EP-A-0 429 237 discloses a safety device for preventing overload of the cone crusher with ensuing damage. In this device, the upper part of the chamber housing of the crusher is pressed downwards towards the main frame of the crusher. If there is an overload, the downwardly-directed force is relieved by temporarily raising the upper part of the chamber housing of the crusher. The use of this safety device does not involve any controlled variation of the crushing force.
Swedish Published Application 8601353-9 (SE-B456,138) and the corresponding U.S. Pat. No. 4,856,716 disclose a method for operating a cone crusher, in which the power consumption, the pressure load on the crushing head and the width of the crushing gap are continuously measured. The measured values are then used for maintaining the width of the crushing gap on a level above a determined minimum value by correlating the power co
REFERENCES:
patent: 4712743 (1987-12-01), Nordin
patent: 4793560 (1988-12-01), Schrodl
patent: 4856716 (1989-08-01), Burstedt
patent: 4967967 (1990-11-01), Magerowski et al.
Malone William
Scott Alexander J.
Svensson Arvid L.
Husar John M.
Svedala Arbra AB
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