How to maintain ventilation and wind speed control inside the ball mill?

Gears are a critical component of a ball mill. Failure can have a significant impact on the operation of a Shenyang ball mill. So, what are some common ball mill gear failures and how to fix them? Today, we'll briefly discuss them.

1. Cracks in the Large Ring Gear of a Ball Mill

After long-term operation, if a ball mill experiences a sudden increase in vibration and noise, it's likely that the mill has developed a serious crack. Minor cracks in the large ring gear should be repaired immediately. Otherwise, under long-term heavy-load operation, this condition will recur, and this is considered fatigue cracking.

Treatment:

If the large ring gear is otherwise intact and only a severe crack is present locally, a localized repair can be performed. To begin repair, first remove all steel balls, material, and other components from the ball mill cylinder. Then, loosen the bolts on the large ring gear, locate the crack, and weld two steel plates of the same size at each end of the large gear.

2. Violent Vibration of the Ball Mill Pinion

During normal operation, a ball mill rotates using a motor. This motor directly connects the pinion to the large ring gear via an elastic pin coupling, which in turn drives the large ring gear. If the pinion and its base vibrate violently during operation, it's likely because the pinion is too far from the anchor bolts, lacking a fixed point in between. This causes large vibrations in the center of the pinion base. Frequent vibrations can lead to severe wear on the pinion.

Solution:

Replace the ball mill's pinion gear and add two anchor bolts on the inner side of the pinion that meshes with the large gear. Re-reinforce the base.

After work, clean the foundation and verify the surface levelness, elevation, and anchor bolt position and height. Drill holes (hole size depends on the ball mill model), install the anchor bolts, and grout. After solidification, use wedges for preliminary alignment.

3. Sudden Temperature Rise of the Rolling Bearing at the Feed End of the Ball Mill

During normal operation of the ball mill, the temperature of the rolling bearing at the feed end suddenly rose to over 160°C, significantly exceeding the normal bearing temperature (50-60°C). This condition is often caused by severe bearing wear. For example, deformation of the bearing's rolling elements or wear of the outer diameter of the hollow shaft that secures the bearing, resulting in a reduced diameter, are the main causes of the sudden rise in bearing temperature.

Solution:

1. For minor wear, the worn hollow shaft neck can be repaired by welding. The outer diameter can be divided into 12 equal sections, with a weld width of 40 mm and a length equal to the entire bearing installation length. After welding, grind along the axial direction. Since the outer diameter of the hollow shaft is already tapered, set the reference on the outer diameter of the unworn shoulder area. Use an outside micrometer to measure the outer diameter in all directions after the repair. Use a gauge to measure straightness to ensure that the tolerance of the hollow shaft is within the designed interference fit range.

2. For severe wear, the bearing needs to be replaced. First, measure the tolerance of the new bearing and prepare a test rod. The test rod tolerance should be 50 μm larger than the outer diameter of the hollow shaft. Prepare the necessary installation tools, such as a heating oil bath and thermometer, and heat the bearing. When the bearing is heated to approximately 120°C and the test rod can pass smoothly through the bearing inner diameter, install the bearing immediately. Lubricate the bearing promptly after installation.

These are common problems with ball mill gear failures. I hope this helps.

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