Vertical Coal Mill In Cement Industry

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Discussion on Optimization Plan of Grinding Roller of Vertical Coal Mill

Optimization of the grinding roller drive system

In the drive scheme of Vertical Coal Mill, the commonly used transmission types are gear transmission, chain drive, two-way synchronous belt drive, step wedge composite belt drive and so on. In these solutions, the gear transmission can meet the requirements of the opposite speed of the two rollers, the speed difference between the fast and the slow rollers, and the transmission is smooth and efficient, but when different grains are added, the center distance between the two rollers needs to be adjusted. Once the center distance is too large, the impact of the gear working surface will be caused, and the noise is large and the transmission reliability is low. At present, only a small number of small Vertical Coal Mills use gear transmission to grind a single grain, which is simple in structure, small in size, and inexpensive.

The chain drive can overcome the inconvenience of the center distance adjustment, but the chain drive is polluted, the multi-variation effect is serious, and the work is unreliable. At present, it has been rarely used. The double-sided synchronous belt drive can overcome serious pollution. The disadvantage of large noise, at the same time, the center distance adjustment can be carried out, but the jump band phenomenon is easy to occur at the start, the break band phenomenon is easy to occur during the work process, and the price is expensive, and then the step wedge composite belt drive for the Vertical Coal Mill comes. It can overcome the phenomenon of the broken belt and the start jump band of the double-sided timing belt, and has been widely used in large and medium-sized mills, and has achieved good results;

Optimization of grinding roller fixing method

At present, there are three common fixing methods for Vertical Coal Mills. The three fixed methods and their respective advantages and disadvantages are mainly as follows. In actual production, you can choose according to your own needs:

1) The interference fit between the bearing and the grinding roller shaft is adopted. This method is to directly match the bearing with the grinding roller shaft, and does not adopt the structural transition such as the tightening sleeve to ensure the reliable positioning of the grinding roller shaft. However, the radial runout of the grinding roller shaft itself is only affected by the precision of the grinding roller itself, and the high rotation precision can be ensured under the ordinary processing and manufacturing precision, but the disassembly and assembly is difficult;

2) A tight connection between the bearing and the grinding roller shaft is used to form a detachable connection. If the Vertical Coal Mill adopts this fixing method, the grinding roller shaft and the bearing are connected by the adapter sleeve. The advantage is that the position of the adapter sleeve relative to the grinding roller shaft can be adjusted, the axial dimension error of the grinding roller shaft processing is loose, and the sealing of the two ends of the grinding roller relative to the wall panel can be ensured, and the leakage of the material is reduced. Opportunity, the disadvantage is that the machining accuracy is relatively low, and the tight clamping of the set will cause the grinding roller to be displaced relative to the bearing, which is difficult to disassemble and install;

3) A tapered joint is used on the bearing on the grinding roller shaft to form a detachable fit with the same tapered bearing. If the Vertical Coal Mill adopts this fixing method, the advantage is that the two tapered surfaces Direct matching, without adding any transition elements, to ensure accurate and reliable rotary positioning of the grinding roller, and the radial runout of the grinding roller itself depends only on its own machining accuracy. When disassembling, only special hydraulic tools need to be used in the bearing. The high-pressure oil film formed on the tapered surface between the grinding roller can be smoothly disassembled. The disadvantage is that the processing precision of the parts is high and the processing is difficult;

In the current situation, the fixing method using the adapter sleeve has been less and less, and the fixing method using the interference fit is mostly used in the small-sized, single-grain mill, for the large and medium-sized mill. The connection structure of the tapered surface is better.

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