The broken form when changing roller:
1) Horizontal fracture: the roller is broken in the middle, so that one roller becomes two sections, and the fracture is relatively neat
2) Longitudinal brittle fracture: a longitudinal crack begins to appear on a part of the roller, which extends to the center and then breaks. There are two fractures
Roller breaking reasons and suggestions for avoidance:
Horizontal fracture is mainly due to the mechanical force concentrated destruction of the relatively weak links of the roller and the form of broken, such as in the kiln due to the roller by the brick self gravity; Impacted by High temperature and high velocity air flow; The friction force of porous brick — “rub roller”, etc.; Outside the kiln, the roller is directly impacted by external force. The other is easily neglected thermal stress fracture, which is also caused by the uneven thermal stress caused by mechanical stress. Simply, when the high temperature roller is pulled out of the kiln, the other end or the middle part of the roller is supported by metal objects with good thermal conductivity such as iron hooks, which is easy to cause the support point to destroy the structure of the roller due to too fast heat dissipation, and finally the place is broken due to the uneven thermal stress. Of course, because of the quality of the roller itself, such as refractoriness, thermal shock stability at high temperature, wall thickness and uniformity, will also largely lead to the roller in the kiln easy to break.
In conclusion, in order to effectively reduce the Horizontal fracture during changing roller, it is recommended to pay attention to the following details:
1) When pull out and insert the roller, the action should be fast, at the same time more stable, do not shake.
2) Do not drag the roller on the passive bearing supporting the rotation of the roller when pull out and insert the roller, and do not let the high-temperature part stay on the passive bearing to reduce the shake and uneven thermal conductivity;
3) It needs 2 persons to operate: One person takes out the roller, and the other one hold the opposite end of roller with the hook, so that the working part of the roller in the kiln will not be affected by external force, effectively reducing the breaking. However, the roller connecting personnel must not use metal iron hook to connect the roller directly, but should wear asbestos gloves and then use high temperature asbestos to hold the roller.
4) After the roller is pulled out of the kiln, no matter how the roller is cooled, it is necessary to reduce the metal connect with the high-temperature part of the roller. If the roller is supported by two ends, the porcelain rod can be used instead of the iron rod. Stand at the edge of the kiln cooling frame cooling, cooling frame should be sure to wrap asbestos, no metal iron exposed.
5) If a person is in operation when loading the rod, it is difficult for the roller to be timely and accurately loaded into the sleeve of the roller on the active side, while the strong force on the passive side is easy to cause mechanical damage to the roller. Therefore, when loading the rod, it should be a person in the passive side, a person in the active side of the rod, the rod head timely and accurately loaded into the roller sleeve.
Longitudinal brittle fracture of the roller is mainly caused by the uneven internal and external heat dissipation of THE roller in the cooling process. The thicker wall thickness and the larger the diameter, the greater the cooling brittleness probability (because the ceramic roller is a bad conductor of heat).
To reduce roller brittle break, it is recommended to pay attention to the following details:
(1) The thermal insulation cooling method is preferred to cool the roller;
(2) It is forbidden to use fans and other forced cooling methods when changing roller
(3) It is forbidden to have water on the ground when changing roller
Post time: Oct-20-2022