1. Installation reason
The paper pad is flying or the paper pad is seriously damaged; the chuck screw is loose or the chuck screw is not fully installed; the inner ring of the grinding wheel or the joint between the grinding wheel and the chuck slips obviously.
(1) Problems with the installation method
◆ The uneven tightening torque of the tightening bolts causes uneven force on the grinding wheel, which makes the grinding wheel tilt and loosen, and rotate relative to the grinding wheel chuck until the heat bursts.
◆ The long-term uneven bolt locking torque will lead to the wear of the grinding wheel chuck. In this state, even if the qualified grinding wheel is installed correctly, there is a possibility of rupture, which will cause equipment hazards.
(2) Precaution
◆ Use a torque wrench to tighten the bolts to ensure an even tightening torque.
◆ When tightening the bolts, tighten them diagonally in turn to prevent overturning moment.
◆ When installing, make sure that the paper pad is in good condition. If it is damaged, replace it with a spare good paper pad.
◆ During the use of the grinding wheel, use the clearance time such as cleaning slag, loading and unloading, etc. to check the grinding wheel and chuck, and check for hidden dangers such as loosening of the chuck screws due to grinding vibration.
◆ After the grinding wheel is installed, use a chalk to draw a straight line on the flange and grinding wheel. After grinding, check whether the straight line is aligned to judge whether the grinding wheel is slipping.
◆ It is necessary to regularly check the parallelism between the grinding wheel chuck and the pressure plate. When it is larger than 0.1 mm, it is forbidden to use it and repair it.
2. Equipment reason
Sudden shutdown or abnormal running of equipment failure, or obvious abnormality of equipment (broken bearing, broken screw, broken chuck, grinding head jumping, grinding head oil leakage, etc.) A burst occurs.
(1) Analysis of the reasons for the explosion
◆ Temperature distribution of different parts of the grinding wheel
In the grinding process, the outer ring of the grinding wheel directly contacts the continuous casting billet for grinding, which generates a lot of heat, the temperature rises the fastest, and the internal temperature decreases sequentially; during the loading and unloading process, the grinding wheel is cooled, and the temperature of the outer ring drops rapidly.
◆ Reasons for grinding wheel bursts
The temperature distribution of different parts of the grinding wheel is uneven, and the temperature of the same part varies greatly at different times. The grinding wheel is out of balance due to equipment reasons, and a large internal stress will be generated instantly. When this internal stress is greater than the adhesion between the abrasives of the grinding wheel When the force is combined, the abrasive particles will be torn apart, and the crack will continue to extend until the grinding wheel bursts.
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(2) Precaution
◆ Spot inspectors strengthen daily inspection of grinding machine equipment to eliminate possible hidden dangers.
◆ Grinding workers use the time between slag cleaning, buckets and other equipment downtime to check the grinding head, chuck, etc.
◆ If abnormal noise is found during the grinding process, the machine should be stopped immediately and the equipment should be checked to prevent the occurrence of a ruptured disc accident.
3. Operation reason
The edge of the grinding wheel is bumped and the block is dropped; the side of the grinding wheel has traces of contact with the billet; the grinding billet has edges or corners.
(1) Analysis of the reasons for the explosion
The grinding wheel collided with the continuous casting billet, resulting in a partial defect of the grinding wheel and the occurrence of chipping.
(2）Precaution
◆ Fine operation, focus on grinding the corners, and adjust the length compensation value in time.
◆ Reduce the pressure when grinding the corners, and adjust the decompression coefficient or holding pressure to about 90% to 95% of the normal grinding pressure.
◆ When continuous inaccuracy of slab length measurement occurs, timely feedback to equipment personnel for processing.
◆ Ensure the interlock protection function of the program.
4. Grinding wheel quality reasons
The grinding wheel is completely damaged by the root; the steel ring is broken.
(1) Analysis of the reasons for the explosion
◆ The adhesion between the reinforcement layer of the grinding wheel and the used layer is poor, or the grinding wheel itself has cracks, which crack from the root during use, resulting in bursting.
◆ The strength of the steel ring is not enough, and the steel ring breaks when a burst occurs, which does not play a role in preventing the fragments from flying.
(2) Precaution
◆ Before using the grinding wheel, check the grinding wheel and stop using it if it is found to have cracks, water or oil, or obvious bump marks.
◆ Smoothly transport the grinding wheel during handling and installation to avoid bumps and drops.
◆ The grinding billet should control the temperature before grinding, and air it according to the requirements, so as to avoid the bursting of the grinding wheel which is not resistant to high temperature.
