Occurrence and prevention of transverse and vertical cracking of medium frequenc
Date：2020-09-27 / Hits：355
Vertical game
The vertical cracking of lining materials often occurs in large induction furnace lining, mainly due to the stress cracking caused by cooling shrinkage.
Preventive measures:
1. According to the sintering operation instructions (temperature rise vs. sintering temperature curve), the sintering layer with sufficient thickness is produced in the furnace lining to resist the stress cracking caused by cooling shrinkage.
2. The silica lining should not be cooled in the air and should be kept above 800 ℃. Even if it is intermittent operation, it should not be cooled in air. The correct method is as follows: first, clear the molten iron, then hoist in the red hot activated iron block, cover the furnace cover, do not close the cooling water, continue to keep the temperature above 800 ℃.
3. As far as possible, the continuous production operation shall be carried out 24 hours without interruption; if the production must be stopped at the weekend, the insulation shall also be conducted as mentioned in Item 2 above.
4. If it is necessary to check the furnace lining when the production is stopped, it is not allowed to use fans to blow down the furnace wall, so as to prevent the phenomenon of rapid cooling cracking.
Horizontal cracking:
The phenomenon of horizontal cracking is mainly caused by particle size segregation and interlayer produced by construction, such as the particle size segregation of dry beating materials in the packaging bag due to transportation, uneven distribution during furnace beating, poor furnace beating tools and process, fine powder outflow due to mold gap, and poor lamination. Secondly, it may be caused by mechanical impact or vibration during production operation,
Preventive measures:
1. Before making the furnace, check whether the package of the dry beating material is complete and whether the material in the bag has particle size segregation. If there is particle size segregation, it should be evenly mixed again before use.
2. Check whether the intima is intact and whether the joint is tight. If there are holes or gaps, repair them.
3. Uniform distribution is required during feeding, and single point distribution is not allowed to prevent particle segregation caused by uneven distribution.
4. It is better to select the construction vibration tools (high vibration frequency) and mold equipment (cross type internal mold vibration or three arm air hammer) recommended by the original company, which can reduce the lack of construction technology, shorten the construction time, improve the density of furnace lining (about 10% higher than that of manual firing), and improve the durability of furnace lining.
5. If the furnace is manually fired, the flat head air hammer head is not allowed to be used, but the fork type or cross type hammer head should be used to prevent the occurrence of interlayer phenomenon.
6. The best filling density can be obtained by moderate vibration or furnace blowing. Excessive or insufficient filling density is harmful.
7. When making the joint layer, the surface should be flowered first to facilitate the bonding effect of the material
The vertical cracking of lining materials often occurs in large induction furnace lining, mainly due to the stress cracking caused by cooling shrinkage.
Preventive measures:
1. According to the sintering operation instructions (temperature rise vs. sintering temperature curve), the sintering layer with sufficient thickness is produced in the furnace lining to resist the stress cracking caused by cooling shrinkage.
2. The silica lining should not be cooled in the air and should be kept above 800 ℃. Even if it is intermittent operation, it should not be cooled in air. The correct method is as follows: first, clear the molten iron, then hoist in the red hot activated iron block, cover the furnace cover, do not close the cooling water, continue to keep the temperature above 800 ℃.
3. As far as possible, the continuous production operation shall be carried out 24 hours without interruption; if the production must be stopped at the weekend, the insulation shall also be conducted as mentioned in Item 2 above.
4. If it is necessary to check the furnace lining when the production is stopped, it is not allowed to use fans to blow down the furnace wall, so as to prevent the phenomenon of rapid cooling cracking.
Horizontal cracking:
The phenomenon of horizontal cracking is mainly caused by particle size segregation and interlayer produced by construction, such as the particle size segregation of dry beating materials in the packaging bag due to transportation, uneven distribution during furnace beating, poor furnace beating tools and process, fine powder outflow due to mold gap, and poor lamination. Secondly, it may be caused by mechanical impact or vibration during production operation,
Preventive measures:
1. Before making the furnace, check whether the package of the dry beating material is complete and whether the material in the bag has particle size segregation. If there is particle size segregation, it should be evenly mixed again before use.
2. Check whether the intima is intact and whether the joint is tight. If there are holes or gaps, repair them.
3. Uniform distribution is required during feeding, and single point distribution is not allowed to prevent particle segregation caused by uneven distribution.
4. It is better to select the construction vibration tools (high vibration frequency) and mold equipment (cross type internal mold vibration or three arm air hammer) recommended by the original company, which can reduce the lack of construction technology, shorten the construction time, improve the density of furnace lining (about 10% higher than that of manual firing), and improve the durability of furnace lining.
5. If the furnace is manually fired, the flat head air hammer head is not allowed to be used, but the fork type or cross type hammer head should be used to prevent the occurrence of interlayer phenomenon.
6. The best filling density can be obtained by moderate vibration or furnace blowing. Excessive or insufficient filling density is harmful.
7. When making the joint layer, the surface should be flowered first to facilitate the bonding effect of the material