The maintenance of the main bearing of the ball mill is very important to ensure the stable operation of the ball mill. According to years of maintenance and overhaul experience of cement plant, main bearing failure accounts for a relatively high proportion of transmission system failures. In view of this, this article will share some experiences and views on the maintenance of ball mill main bearings.
1. Application of static and static main bearing
Because the ball mill usually needs to be started at full load, especially after a long shutdown, the lubricating oil film between the hollow shaft journal and the bearing shell will gradually thin or even disappear due to extrusion. At this time, if the ball mill is started directly, it may lead to large starting torque and starting current, increase the load of the transmission system, and may damage the bearing alloy on the surface of the bearing bush. The use of static and static pressure main bearing can establish a stable static pressure oil film before starting, ensuring that the journal and the bearing bush are in a full liquid friction state, so as to avoid damage at the start of the moment.
2. Influence of radius gap on lubricating oil film
The radius gap between the spherical tile and the journal of the hollow shaft is very important for the formation of the lubricating oil film. Reasonable radius clearance can improve bearing capacity and reduce friction power consumption. However, too small gap is not conducive to the formation of lubricating oil film, and too large gap may make the oil flow along both sides of the tile edge, affecting the stability of the oil film. Therefore, it is necessary to determine the appropriate radius clearance.
3. Influence of contact Angle
The contact Angle between spherical tile and hollow shaft journal directly affects the formation of oil film. Although the larger envelope Angle helps to improve the bearing capacity, it is not conducive to the formation of oil film. The use of small contact Angle can ensure the smooth entry of lubricating oil into the contact area, conducive to the formation of oil film, and contribute to the heat dissipation of the hollow shaft journal and spherical tile. In practice, the contact Angle should be less than 35°.
4. The influence of the spherical tile on the oil groove
Opening the oil groove on the spherical tile may cause the oil film to break and reduce the effective contact area, which is not conducive to the formation of the oil film. In fact, even if many spherical tiles do not open the oil tank, there will be no abnormal phenomenon after long-term operation. For bearings started by high pressure oil pump, the opening of the oil groove should be carefully considered.
5. Processing of hollow shaft journal
The polishing of the hollow shaft journal should be done carefully. Manual polishing may damage the roundness of the journal and is not conducive to the formation of oil film. Long running hollow shaft journal usually has reached the ideal roundness state, without the need for large area polishing treatment.
6. Scraping treatment of spherical tile
After a period of running between spherical tile and hollow journal, the contact Angle usually does not increase significantly. Due to the uncertain dynamic load during operation, the contact Angle is automatically limited to a certain range. Therefore, for spherical tiles in normal use, there is no need to carry out frequent scraping treatment.
7. Surface contact of spherical tile
When scraping spherical watts, the surface should be kept smooth so that there is no obvious boundary between points and non-points. In fact, after long-term operation, the surface of the spherical tile is close to a smooth whole, which is conducive to the formation of the oil film. Attention should be paid to maintaining the smoothness of the surface when scraping.
8. Matching of spherical tile and tile seat
The fit between the spherical tile and the tile seat should ensure that the spherical tile has enough freedom to flexibly follow up during operation. The spherical radius of the spherical tile should be less than the spherical radius of the tile seat to achieve point contact. The correct coordination can avoid the occurrence of tile burning accidents.
Through the above measures, the stability and service life of the main bearing of the ball mill can be effectively improved to ensure the efficient operation of the ball mill.
