When the barrel of the ball mill rotates around the horizontal axis at a predetermined number of revolutions, the crushing medium and ore contained in the cylinder are lifted to a certain height with the centrifugal force and the frictional force, and then freely fall or roll off the wall of the cylinder. Under the grinding, the ore is mainly crushed by the impact force when the crushing medium falls and the grinding and peeling action during the movement. The ore is continuously fed from the hollow shaft at one end of the cylinder, and the ground product is continuously discharged through the hollow journal at the other end of the cylinder. The movement of the ore in the cylinder is achieved by continuously applying pressure to the ore. During wet grinding, the ore is carried away by the water flow. When dry grinding, the ore is taken out by the airflow drawn out of the cylinder (exhaust fan).
Ball mill construction
The ball mill consists of the following six parts: the barrel part, the ore supply department, the mine discharge part, the bearing part, the transmission part and the lubrication system.
The structure of the lattice type ball mill is basically the same as that of the overflow type ball mill, and the discharge end of the lattice type ball mill of different points is equipped with a drainage grid plate.
Regardless of whether it is a lattice type ball mill or an overflow type ball mill and a classifier, a closed loop is used in the ore mining department. A drum feeder is often used to form a closed loop with the cyclone.
Construction of MQY2.7×3.6 wet overflow ball mill
1. Feeding drum feeder, feed end cover, feed bushing, end cap liner
2, the cylinder part (slewing part)
Mainly composed of cylinder and cylinder liner
3, the main bearing department
It consists of front and rear bearing, Pap alloy composition tile
The bearing part carries the full load of the rotating part of the main body of the ball mill, and the main bearing shaft adopts the dynamic and static pressure sliding bearing. It is a kind of bearing which has both dynamic pressure lubrication and static pressure floating up. Before the grinding machine starts and stops grinding, The high-pressure oil is supplied into the bearing. At this time, the static pressure acts. After the mill runs for 10 minutes, the high-pressure oil is stopped, and the dynamic pressure acts. This is called a static pressure sliding bearing, so that the high-pressure oil is before the mill starts. The mill barrel is floated about 0.05-0.08 mm. The starting load can be greatly reduced to reduce the impact on the drive part of the mill and to avoid scratching the bearing bush. When the mill stops moving, the high-pressure oil gradually stops the bearing of the journal, so that the bearing bush is not scratched.
The wrap angle of the main bearing bush and the central shaft is 120 degrees. The contact surface is cast with babbitt alloy. The bearing bush is connected with a cooling water pipe and the cooling water is passed to reduce the temperature of the bearing bush.
Normal operating temperature of the main bearing bush: 27-35 ° C in summer. Normal conditions such as oil pressure, water pressure, and normal bearing temperature will not reach 40 ° C. If the temperature on the temperature measuring point of the instrument reaches 40 ° C, the cause should be immediately identified to prevent the temperature from rising.
The seven measuring points of the inspection instrument, 0-2 is the motor temperature measurement point, 3-4 is the front tile temperature point, and 5-6 is the rear bearing temperature measurement point. The main bearing is equipped with a platinum thermal resistance, which can automatically stop the grinding machine when the temperature of the main bearing is greater than the specified value (60 ° C).
4. Transmission department
It mainly includes large and small gear bearing housings, gear covers, clutches (side guard plate brake pads, airbags, housings, brake drums, 0.3m3 air compressors, gas storage tanks, etc.).
¢ 2.4×4.5 grid type ball mill, the transmission part has fewer clutches and one more speed reducer.
5. Department of Mines
Mainly there are discharge end caps, discharge bushings, fan liners and so on. The lattice type grinding machine is mainly composed of a discharge end cover, a grid plate, a center lining plate, a discharge guide rib, a discharge bushing and the like.
6. Lubrication system
It mainly includes fuel tank, high and low pressure oil pump, oil supply filter and oil return filter. Water coolers, pipes, pressure gauges, thermometers, pressure relays, heaters, etc.
Lubrication system for low pressure and large flow main bearing lubrication and starting, stopping high pressure and small flow lubrication, lubrication system oil: summer N320 or N220 closed gear oil; winter N220 or 150 closed gear oil.
The normal oil level of the lubrication system is 400-500mm, and the minimum warning line oil level is 200mm. In winter, the oil should be heated to below 20 °C and below 40 °C before starting.
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