The roller sleeve of the vertical mill is an important part of the vertical mill. It is mainly responsible for the rolling of the material. It must have high hardness, so the toughness is relatively poor. The roller sleeve often bursts in the using process. Thus to avoid accident, it is important to carry out cause analysis and follow the standard operation.
The main reasons for the burst of the vertical grinding roller sleeve are as follows:
1. The temperature rises and falls too fast
Due to the thickness of the vertical grinding roller sleeve, if the external temperature rises and falls rapidly, the thermal expansion and contraction inside and outside the roller sleeve cannot be synchronized, which will generate strong stress and cause the roller sleeve to burst. Therefore, during the operation, it should be noted that the temperature rise and fall should be slow, and should not exceed 0.5 degrees per minute.
2. Enter large metal foreign bodies
In order to ensure work efficiency and quality, the vertical mill roller sleeve will increase a lot of pressure during the working process. If a large metal foreign body enters the vertical mill, it will not be crushed or thrown away, and it will be repeatedly rolled. A large reaction force is generated during the rolling process, which will cause the roller sleeve to burst. Precautionary measures are to install metal detectors and iron separators to prevent the entry of large pieces of metal materials. In addition, if the vertical mill has abnormal vibration, it is necessary to stop and check in time to prevent accidents.
3. Improper installation
The diameter of the vertical grinding roller sleeve is relatively large. If it does not fit well with the roller shaft during installation, the coaxiality deviation will be too large, and the phenomenon of unbalanced force will appear during the operation. The roller sleeve may burst after a long period of such operation. Therefore, a professional team should be selected for the installation of the roller sleeve, and the installation should be carried out in strict accordance with the specifications, and the bolts should be re-tightened after 8 hours and 24 hours of operation.
4. Unstable grinding condition
During the operation of the vertical mill, it is necessary to maintain a certain stability, otherwise there will be a relatively large vibration, which will easily cause the roller sleeve to burst. The first is that the feeding system must run stably, otherwise the inner material layer of the mill will be unstable and it is easy to generate relatively large vibrations. The second is the pre-homogenization of the material. If the powder material and the block material are not uniform, the material layer in the mill will be unstable, and the vibration will exceed the standard.
5. The quality of the roller sleeve
The production of vertical grinding roller sleeves, from the selection of ingredients to casting to heat treatment to machining, is more strict than the general casting requirements, and the production cost is relatively high. Completed independently, no outsourcing is required, otherwise the quality cannot be guaranteed. In addition, strict acceptance is required, including external dimensions, internal flaw detection, etc.
Post time: Jul-04-2022