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The main bearing of the wet overflow type ball mill is mainly responsible for the full load of the rotating part of the ball mill and is used to reduce the friction coefficient during operation to ensure rotation accuracy.
In daily production, it is a common phenomenon that the main bearing of the overflow type ball mill heats up, but if the temperature is too high, it is likely to cause the main bearing of the ball mill to burn. So, what are the reasons that cause the bearing temperature to be too high? Let us understand together.
There are many reasons for the high temperature of the main bearing of the ball mill, such as material or debris entering between the shaft diameter and the bearing surface, improper selection of lubricating oil or too thick or too thin, the scraping of the bearing pair does not meet the requirements, and the installation position of the main bearing is not Reasonable, etc., will cause the main bearing to heat up, and in severe cases, it may even cause bush burning.
Use the table of contents below to navigate through the guide:
01 Materials or sundries enter between the shaft diameter of the ball mill and the bearing surface
02 Improper selection of lubricating oil, too thick or too thin
03 The scraping of the bearing pair of the ball mill does not meet the requirements
04 The installation position of the main bearing is unreasonable
After the ball mill is running for a long time, the friction surface clearance between the journal and the bearing bush will become larger. When debris such as ore or mud enters the friction surface of the journal and the bearing bush, it will destroy the cooperation between the two, making the bearing bush and the shaft diameter surface Raising occurs, increasing wear and tear and causing heat.
In addition, if debris blocks the oil injection hole of the oil spray pipe, the oil will be sprayed to both sides, so that the lubricating oil leaks out of the shaft diameter, causing the main bearing to be short of oil and unable to form an oil film, which will increase the temperature of the bearing and eventually lead to The main bearing is burnt.
Relevant staff should be required to conduct regular inspections and daily cleaning. If there is debris between the shaft diameter and the bearing bushes, stop to eliminate the debris. If the gear is found to be severely worn, it needs to be replaced in time.
Under normal circumstances, each main bearing has a separate circulating lubrication system. When the mill starts and stops, high-pressure lubricating oil is provided from the lower part of the main bush to the surface of the bush to float the grinding body to form a hydrostatic oil film.
During operation, the main bearing of the ball mill will generate a certain amount of heat. A small part of it will be conducted away by the gold chips, and most of the rest will be carried away by the lubricating oil. If the lubricating oil is too thick, the fluidity of the oil will be poor. If the heat generated by the bearing is taken away in time, it will cause the bearing to heat up; if the lubricating oil is too thin, a stable and good oil film cannot be formed, and the metal parts between the bearings will directly rub, causing the bearing to heat up faster.
Lubricating oil should be used in strict accordance with the oil standard for ball mill bearings, and the oil pressure of the ball mill should be checked regularly and the oil volume and oil temperature of each lubrication point should be patrolled. If oil quality problems are found, the oil needs to be changed in time. , The oil should be refilled in time.
Generally, the matching contact between the spherical bush of the main bearing of the ball mill and the hollow shaft journal needs to meet these two requirements: First, the spacing range of the matching side clearance in the non-oil bag part should be between 0.24 and 0.32mm; second, the matching contact The distribution of spots must meet the requirements of "cooperating contact area", that is, the spots are of equal width along the full length of the bus bar, uniformly and continuously distributed, and the spot spacing is less than 5mm.
When the above two items do not meet the requirements, the ball mill bearing pair is allowed to be scraped within the range of the original contact belt, but the contact wrap angle should not be greater than 35°, and the diameter of the pad is 1‰ larger than the shaft diameter. If the scraping does not meet the requirements, It is not easy to form an oil film between the bearing bushes, and friction will cause the bearing to heat up.
The contact between the hollow shaft journal of the ball mill and the main bearing bush should be checked regularly to ensure that the coordination between the shaft journal and the bearing bush meets the specified requirements. Otherwise, the bearing bush should be scraped and repaired in time.
The discharge end of the overflow type ball mill generally adopts a fixed design, and the feed end is a floating design. When installing, it should be installed in strict accordance with the installation requirements. Among them, a 10mm thermal expansion gap should be left at the feed end cover next to the feed device. A 30mm thermal expansion gap should be left on the body side.
In addition, the level tolerance of the main bearing base is 0.1mm per meter, the relative elevation tolerance of the two bases is 0.5mm, and the discharge end should be lower than the feed end. If the installation of the main bearing does not meet the above requirements, the temperature of the main bearing of the mill will be too high.
The operator of the ball mill should be required to regularly check the installation position of the main bearing of the ball mill to ensure that the position meets the specified requirements. If problems are found, they should be adjusted in time according to the standards.
The above introduces the reasons and improvement measures for the easy heating of the main bearing. If the above-mentioned problems occur in the ball mill of your factory, you can improve it according to the relevant countermeasures.
In the solution to the high temperature of the overflow type ball mill, in addition to finding and solving the problem in time, attention should also be paid to the purchase and model selection. It is recommended to choose a reliable and reputable manufacturer to improve the operating efficiency of the ball mill.
