The high-speed rotating rotor with a plate hammer is the main working part of the impact crusher. In order to meet the needs of crushing large ore, the rotor must have sufficient weight and run smoothly.
Regardless of the replacement of a new blow bar or an old blow bar after assembly and repair, attention must be paid to the balance of the rotor; otherwise it will affect the normal operation of the equipment. This article shares the consequences, causes, solutions and precautions for daily maintenance of the rotor imbalance.
- Consequences of unbalanced rotor
1) The unbalance of the rotor will produce a large inertia force and moment of inertia, which will cause the unstable operation of the equipment;
2) The unbalance of the rotor will cause greater vibration of the rotor components, generate additional dynamic loads, destroy the normal operating conditions of the equipment, cause the bearing temperature to rise too high, shorten the service life, and even cause cracks and damage to some parts.
- Reasons for rotor imbalance
1) The quality of the rotor itself is problematic, and the manufacturer does not strictly follow the manufacturing requirements, and the product is unqualified;
2) The end face of the rotor body is severely worn, and the wear is uneven, and the center of mass and the center of the rotor body are not in the same position, which causes the static and dynamic balance of the rotor to be unable to be guaranteed;
3) Uneven feed, causing uneven force on the rotor and breaking the balance.
- Solutions to rotor imbalance
1) Perform a balance experiment on the rotor before putting it into production;
2) Feeding should be uniform to avoid uneven force on the rotor;
3) When replacing the hammer head, it is best to replace it completely or symmetrically, and install it according to the correct method.
- Precautions for rotor maintenance
The impact crusher has been working under severe conditions for a long time, which intensifies the wear of the rotor bearing. Once the rotor fails, the cost of repair and replacement is very high, and replacement is very difficult, often resulting in loss of production shutdown.
It is very important to take effective measures to increase the service life of the impact crusher’s rotor bearings. The following are the precautions when using the impact crusher rotor:
1) Reasonably adjust the matching relationship between the rotor bearings.
The impact load of the rotor bearing broken by the impact crusher is mainly the impact load. The load on the rolling element is different. The rolling element under the combined force of the impact load receives the greatest force. The inner and outer ring raceways are also here and there. The force is greatest when the rolling elements are in contact.
Since the inner ring keeps rotating when it is working, the contact points on the track will continuously circulate from the maximum force to the minimum force. Therefore, it is necessary to make the inner ring fit tightly so that a certain point does not stay under the force.
The outer ring is different. The outer ring is relatively fixed, and the point of maximum force will stay at a fixed point. Therefore, if the outer ring is loosely fitted, it may move slightly under the impact force, thereby increasing the maximum force. Point, and extend the life of the outer ring.
2) Improve the balance accuracy of the rotor.
The rotor of the impact crusher has a large mass and a high speed. The casting deviation of the rotor body and the mass deviation caused by the installation of the hammer will cause the unbalanced centrifugal force to be generated when the rotor rotates. This centrifugal force causes the machine to generate forced vibrations, causing damage to bearings and other mechanical parts. Therefore, the rotor of the crusher must undergo a balance test.
If the diameter of the rotor body is small, the mass of the blocking plates on both sides of the rotor body can be changed for balance. If the diameter of the rotor body is large, the counterweight can be welded to the outer wall of the rotor body. In order to prevent the counterweight from falling during the vibration process, several rows of grooves can be cast in appropriate positions; the counterweight is embedded in it, and then welded, which is firm and beautiful.
3) Correctly select the model of the rotor bearing.
Double-row radial spherical roller bearings have the advantages of strong load-bearing capacity and good self-aligning performance, so this type of bearing is often used as a rotor bearing when selecting.
4) To improve the stress condition of the crusher bearing.
The impact load acting on the bearing depends on the impulse acting on the rotor and the support flexibility of the bearing seat. Increasing the support flexibility of the bearing seat will reduce the impact load on the bearing.
For this reason, a rubber plate of appropriate thickness can be added between the bearing seat and the support frame to improve the support flexibility of the bearing seat.
Due to the addition of the rubber plate, the support flexibility is increased, which absorbs a part of the vibration energy, improves the force condition of the bearing, and achieves the purpose of extending the service life.
Compared with the hammer crusher, the rotor of the impact crusher has a greater momentum, which is suitable for crushing harder materials and has lower energy consumption. The rotor is an important part of impact crusher. Correct use and reasonable maintenance can effectively avoid rotor imbalance faults and avoid unnecessary shutdowns.