Ball mills are widely used in mines. In the process of installation and operation, it is often affected by the installation environment, lubrication degree, load conditions, etc., and vibration failures occur. This article mainly introduces four causes and corresponding solutions for abnormal vibration of ball mills for mineral processing.

1. Ball mill gear failure
Gear drive is the main transmission form of beneficiation ball mill. Among the failures of abnormal vibration of ball mill, gear drive failure accounts for a high proportion. The reasons may include the following:

(1) Tooth profile error of ball mill. Ball mill drive gears usually appear with an involute tooth profile, which may cause eccentricity, tooth profile error or pitch error during manufacturing, resulting in abnormal vibration of the ball mill.

(2) The installation of the beneficiation ball mill is wrong. During the installation process, the errors of the top clearance, backlash, coincidence and modulus of the meshing gears will affect the normal operation of the gears. If the coaxiality error of the main shaft and pinion axis of the motor and the parallelism error of the axis of the large and small gears are beyond the standard error range, there is also a too small coincidence degree of meshing gears, tooth tip clearance and tooth side clearance. Equally, in these cases, the gear meshing of the ball mill is affected, which will also lead to abnormal vibration of the ball mill during operation.

(3) The lubricating degree of the ball mill gear is not enough. If the ball mill gear is not sufficiently lubricated, it is difficult to form a complete oil film on the meshing surface of the gear pair, and friction may occur at the local meshing point of the tooth surface. Due to the low sealing performance of the ball mill gear cover, there may be powder particles or ore pulp mixed with grease during operation, which increases gear wear and also causes the ball mill to vibrate.

Solution:

Fully lubricate and adjust the ball mill gear according to the condition of the ball mill, and replace the large gear if necessary. Pay attention to the following points during the installation of the new gear:

(1) Use tools such as angle grinder, sandpaper, kerosene, rag, etc. to clean the end cover flange of the mill cylinder and the joint surfaces on both sides, so that the surface of the end cover flange is smooth and free of impurities and rust.

(2) Remove the top wire of the old ring gear inner ring, clean it and confirm that it can be reused, and then install it on the inner side of the end cover of the new gear ring (the side in contact with the cylinder flange), and apply grease to the bolt holes before installation. .

(3) Thread the positioning bolts on the handle surface (the bolts should not be higher than the handle surface), and ensure that the positioning bolts pass through the new half gear when dropping the new half gear.

(4) Tighten the connecting bolts of the new half ring gear and the cylinder end cover. Tighten one bolt every three bolts to 50% of the standard torque (5404N·m), and the rest do not need to be tightened but need to be penetrated and put on.

(5) Adjust the radial top wire to ensure the roundness and coaxiality of the radial top wire, and ensure that the joint surface gap meets the standard. Check with a 0.05mm feeler gauge, and the insertion depth is less than 20mm.

2. The ball mill anchor screw is loose or broken
Loose or broken anchor bolts of the ball mill may also cause abnormal vibration of the ball mill. The reasons may be as follows:

(1) The anchor screws are fatigued for a long time.

(2) The maintenance of the anchor screws is not in place

(3) The selection of the anchor screws is inappropriate or the screws are too thin

Solution:

The screws should be checked for failure on time, and the screws should be reinforced or replaced in time. In addition, the screws selected in the replacement process should ensure that the thickness and steel are suitable. During the replacement, an appropriate amount of sealing asbestos rope should be added to prevent the screws from loosening. If necessary, a back washer or a double nut can be added. Tighten the screw cap at the end of replacement to prevent slurry leakage.

3. The ball mill produces friction
When the ball mill is installed or repaired, the gap between the inlet and outlet sealing short pipes may be improperly adjusted, which will cause friction during use of the ball mill, which will cause the ball mill to vibrate. On a center line, the limited self-adjustment of the two bearing bushes will also cause friction, which in turn will cause abnormal vibration of the ball mill.

Solution:

If the friction and vibration failure is caused by the unreasonable gap between the inlet elbow and the hollow shaft, you can re-pad to adjust the gap, so that the gap is controlled between 5 and 10mm, and the upper gap is slightly larger than the lower one.

If the vibration failure is caused by the self-adjustment of the two bearing bushes, one of the bearing bushes can be determined as a fixed point and then adjusted to ensure that the center line coincides.

4. Ball mill bearing damage
The bearing damage of the ball mill is also one of the reasons for the abnormal vibration of the ball mill. The reasons for the damage are more complicated, mainly including the following:

(1) The bearing is running overheated.

(2) There is an error in the assembly clearance of the bearing.

(3) The shaft installation is unreasonable, the clearance of each part and the reserved tightening force are not appropriate or the vibration is too large.

(4) There is a lack of lubricating oil, or the lubricating oil is deteriorated or blocked.

(5) Impurities are incorporated between the journal and the bearing bush.

(6) The bearing casting is unqualified, or the proportion of casting components is not equal.

Solution:

Replacing bearings takes a lot of time and the process is cumbersome, which can be solved by replacing the spare pinion shaft set. After the replacement, replace the removed pinion shaft set bearing.

During the replacement process, the bearing temperature of the ball mill should be kept below 120°C. If the temperature is too high, the bearing steel will be annealed and discolored and cannot be used. It is recommended to make special disassembly and assembly tires in advance, and complete the assembly in a short time to avoid the problem that the assembly cannot be assembled due to the decrease of bearing temperature.

After replacing the pinion shaft set, the ulnar side clearance and the coaxiality of the coupling should be re-calibrated as required to ensure that all data indicators are within the standard range.

The above are the reasons and solutions for the abnormal vibration of the ball mill. There are various reasons for the failure of the ball mill. In actual production, it is recommended to purchase qualified production equipment to ensure the quality of the ball mill, install the ball mill under the guidance of a professional installation and debugging team, and regularly check the ball mill during operation to avoid long-term parking. resulting economic losses.