Application of rolling bearing in ball mill

Foreword

In recent years, with the rapid development of China's economy, the demand for building materials and steel products has increased year by year, among which the ball mill plays an important role in it, but its power consumption characteristics are also prominent. The environmental protection strategy, through the analysis of the structure of the whole ball mill, found that its sliding bearing is an important reason that affects the transmission efficiency of the ball mill. It is modified by using rolling bearings to improve the transmission efficiency, thereby achieving the purpose of reducing energy consumption.

1 Ball mill introduction

The ball mill is the key equipment for crushing the material after it has been pulverized. Ball mill is one of the high-fine grinding machines widely used in industrial production. There are many types, such as tube ball mill, rod ball mill, cement ball mill, ultra-fine laminating mill, hand ball mill, horizontal ball mill, ball mill bush, energy saving. Ball mill, overflow ball mill, ceramic ball mill, lattice ball mill Ball mill is suitable for grinding all kinds of ore and other materials. It is widely used in mineral processing, building materials and chemical industries. It can be divided into dry and wet grinding methods. According to different mining methods, it can be divided into two types: grid type and overflow type. According to the shape of the cylinder, it can be divided into four types: short tube ball mill, long tube ball mill, tube mill and cone mill.

The ball mill is composed of a horizontal cylinder, a hollow shaft for feeding and discharging, and a grinding head. The cylinder is a long cylinder. The cylinder is provided with an abrasive body. The cylinder is made of steel plate, and the steel liner is fixed with the cylinder. Generally, it is a steel ball, and is loaded into the cylinder according to different diameters and a certain proportion, and the grinding body can also be used as a steel section. According to the particle size of the grinding material, the material is loaded into the cylinder by the hollow shaft of the ball mill feeding end. When the ball mill cylinder rotates, the grinding body acts on the cylinder liner due to the action of inertia and centrifugal force and friction. It is carried away by the cylinder. When it is brought to a certain height, it is thrown off due to its own gravity. The falling abrasive body crushes the material in the cylinder like a projectile. The material is uniformly fed into the first chamber of the mill by the feeding device through the hollow shaft of the feeding material. The chamber has a step liner or a corrugated liner, and various steel balls are loaded therein. The rotation of the cylinder generates centrifugal force to bring the steel ball to a certain extent. The height falls back and the material is hit and ground. After the material reaches the rough grinding in the first warehouse, it enters the second warehouse through the single-layer compartment board. The warehouse is provided with a flat lining plate with steel balls inside to further grind the material. The powder is discharged through the discharge raft to complete the grinding operation. During the process of turning the cylinder, the grinding body also has a sliding phenomenon, and the material is grounded during the sliding process. In order to effectively utilize the grinding effect, when the general size of the material is 20 mesh, the grinding body is used. Separated into two sections by the compartment board, which becomes a double warehouse. When the material enters the first warehouse, it is crushed by the steel ball. When the material enters the second warehouse, the steel section grinds the material, and the finely qualified material is hollow from the discharge end. discharge shaft, the feed material for small particles when finely ground, such as sand II slag, coarse coal ash, mill shell may set partitions, a single-chamber tube mill, grinding segments may be steel. The raw material is ground into a hollow cylinder through a hollow journal, and the cylinder is filled with grinding media of various diameters (steel balls, steel bars or gravels, etc.). When the cylinder rotates around the horizontal axis at a certain rotation speed, the medium and the raw materials contained in the cylinder are separated from the cylinder by the centrifugal force and the friction force, and when the gravity reaches the certain height, when the gravity is greater than the centrifugal force. The body wall is thrown down or rolled down, crushing the ore due to impact. At the same time, during the rotation of the mill, the sliding movement of the grinding media to each other also produces a grinding effect on the raw materials. The ground material is discharged through a hollow journal.

2 Ball mill sliding bearing transmission analysis

Because the ball mill is a large-scale equipment, it is a heavy-duty low-speed equipment. Therefore, the weight of the entire drum and material acts on the sliding bearing, and at the same time, the material will be in the drum during the rolling process of the drum. The impact is applied up and down, which will cause a certain impact load on the bearing. Therefore, the wear of the bearing will be intensified during use, resulting in a decrease in the transmission efficiency of the sliding bearing. In the actual use of the sliding bearing, the following three reasons occur. Causes the failure of the sliding bearing, thus affecting the normal use of the ball mill: (1) in the manufacturing process of the bearing, the bearing bush contains pores, cracks and trachoma due to the manufacture of the bearing bush; (2) installation problems caused by improper installation; 3) Improper lubrication will cause the sliding bearing to wear and accelerate, which affects the transmission efficiency.

The reason why the ball mill adopts the sliding bearing as its main bearing is that the performance of the sliding bearing is better due to the compliance and the embedding property, and at the same time, it can resist the gluing caused by the starting under the condition of heavy load, but the contact area of ​​the sliding bearing Larger, and the temperature rise caused by the rotation process requires the transmission efficiency of the sliding bearing to be low, the energy utilization rate is not high, and the wear of the sliding bearing is serious. Especially in the use of cement plants and building materials factories, due to the need to operate all day, the amount of materials handled at the same time is relatively large, the wear caused by the sliding bearings is more serious, and the ball mill will cause nearly tens of stops per hour of downtime. The loss of 10,000 yuan, the high-power motor used at the same time will make the electricity cost per hour reach tens of hundreds of yuan, and each time the transmission efficiency is increased by one percentage point, a lot of power consumption will be reduced in one year. Therefore, it is very important to select bearings with good reliability and high transmission efficiency. Through the rapid development of the rolling bearing industry, the materials and reliability of the bearings have been greatly improved. By using rolling bearings, the original sliding bearings are used. Replacement is performed to increase the transmission efficiency of the ball mill.

3 Ball mill rolling bearing use and transformation

The frictional torque of the ball mill is the result of a combination of various factors, including rolling friction, sliding friction, and friction between solids and viscous resistance of the lubricant. Since the rolling bearing has a smaller contact area than the sliding bearing and is only one-ninth of the sliding frictional power consumption of the sliding bearing, it is economical to use the rolling bearing instead of the sliding bearing. At the same time, the use of rolling bearings instead of sliding bearings can greatly reduce the number of replacements for sliding bearing bushings and reduce the number of days that ball mills are shut down, thus greatly improving the economic efficiency of ball mills. Moreover, compared with the sliding bearing, it is more convenient in terms of management and maintenance. Since the ball mill is a low-speed heavy-duty device, the drum part is heated due to heat, which causes axial sway. Therefore, the double-row spherical roller bearing is selected. Can meet the needs of ball mills.

The modification of the ball mill requires the modification of the feed end cap and the feed port and the discharge end cap and the discharge port to meet the bearing installation requirements. The modification of the feed end cap and the feed port is as follows: due to the hollow shaft of the ball mill They are installed on the feed end cover and the discharge end cover, which means that the bearings are also installed on the inlet and outlet end caps respectively. It is necessary to keep the center position of the bearing installation unchanged during the transformation, and the bearing needs to be installed. The part is designed to be inferior, and the installation positioning sleeve is designed to be inferior. At the same time, the asphalt is sealed at the gap between the feeding end cover and the feeding port, and the sealing needs to be completely sealed during sealing to avoid leaving a gap and causing leakage. The impurities enter the bearing and affect the service life of the bearing. In order to avoid the slurry from overflowing from the end face, it is necessary to design a sealing groove at the joint surface of the feeding end cover and the feeding port, and install a special sealing ring. Sealing is carried out in this way. It is only necessary to use the original feeding end cover spare parts or the modified parts to repair the bearing parts and then use the lathe for processing, thereby reducing the The modification of the discharge port is also the same as that of the feed port. After the transformation into a rolling bearing, an automatic lubrication unit is needed to automatically add lubricant to the rolling bearing to ensure the service life of the rolling bearing. The lubrication point is periodically lubricated by using a rolling bearing. The oil thus ensures the lubrication of the rolling bearings.

However, the modification of the rolling bearing of the ball mill has a certain scope of application. It is suitable for those ball mills that operate relatively smoothly and have little impact. Therefore, in the process of transformation, the selection and modification of the bearing need to be fully considered to ensure the transformation work. Rationality.

4 Conclusion

China is a country with relatively scarce energy. Therefore, the country has vigorously promoted energy conservation and consumption reduction, and the ball bearing machine is a high-energy-consuming equipment. The rolling bearing is modified, which improves the transmission efficiency of the ball mill and reduces the power consumption of the ball mill. The country has saved energy and brought more economic benefits to enterprises.

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