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Ball mill machines are widely used in mines. In the process of installation and operation, the ball mill machine is often affected by the installation environment, lubrication degree, load conditions, etc., resulting in vibration failures. From the following, you will learn about the four causes of abnormal vibration of the ball mill for mineral processing and the corresponding solutions.
Use the table of contents below to navigate through the guide:
Gear drive is the main transmission form of beneficiation ball mill. Among the faults of abnormal vibration of ball mills, gear drive faults account for a relatively 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. This kind of tooth shape may have bad conditions such as eccentricity, tooth shape error or tooth pitch error during the manufacture, resulting in abnormal vibration of the ball mill.
(2) The installation of the beneficiation ball mill is wrong. During the installation process, the error of the top clearance, side clearance, coincidence and modulus of the meshing gear will affect the normal operation of the ball mill gear. If the coaxiality error of the main shaft of the motor and the pinion axis and the parallelism error of the large and small gear axes are beyond the standard error range. Too small meshing gear coincidence, tooth tip clearance and tooth side clearance are not equal in tooth width. In these cases, the gear meshing of the ball mill will be affected, and it will also cause 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. 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.
Fully lubricate and adjust according to the condition of the ball mill gear, and replace the large gear if necessary. The following points should be noted during the installation of new gears:
(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 inner ring of the old ring gear, clean it and confirm that it can be reused, then install it on the inner side of the end cover of the new ring gear (the side in contact with the flange of the cylinder body), 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, and tighten one bolt every three bolts to 50% of the standard torque (5404N·m), the rest do not need to be tightened but need to be inserted 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.
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
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 appropriate. 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.
When the ball mill is installed or repaired and reassembled, the gap of 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.
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 it 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.
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 inappropriate 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.
Replacing bearings is time-consuming and 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℃. 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 equipment produced by a qualified ball mill manufacturer 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 problems. Economic losses due to time parking.