1 Installation reasons

       Paper pad flying or paper pad is damaged seriously; the chuck screw is loose or the chuck screw is not fully installed; the inner ring of the grinding wheel or the combination of the grinding wheel and the chuck is obviously slippery.

       1.1 Problems with the installation method

       1) The tightening torque of the fastening bolt is not uniform, causing uneven force on the grinding wheel, causing the grinding wheel to tilt and loosen, and rotate relative to the grinding wheel chuck until the heat is exploding.

       2) Long-term bolt locking torque is uneven, which will cause wear of the grinding wheel chuck. In this state, even if the qualified grinding wheel is properly installed, there may be a burst, which may cause hidden dangers.

       1.2 Preventive measures

       1) Use a torque wrench to tighten the bolts to ensure a uniform locking torque.

       2) When tightening the bolts, they should be locked along the diagonal line to prevent the overturning moment.

       3) Make sure the paper pad is intact during installation. If it is damaged, replace the spare paper pad.

       4) During the use of the grinding wheel, the grinding wheel and the chuck are inspected by using the clearance time of the slag, the loading and unloading, etc., and the hidden troubles such as the looseness of the chuck screw due to the grinding vibration are investigated.

       5) After the grinding wheel is installed, draw a straight line on the flange and the grinding wheel with chalk. After grinding, check whether the straight line is aligned to judge whether the grinding wheel is slipping.

       6) 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 and repair.

       2 Equipment reasons

       Equipment failure suddenly stops or travels abnormally, or the equipment is obviously abnormal (bearing broken, screw broken, chuck damaged, grinding head jumping, grinding head oil leakage, etc.), causing the grinding wheel to collide with the casting blank or equipment, and the grinding wheel has local defects. A burst occurred.

       2.1 Analysis of the causes of the explosion

       2.1.1 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 large amount of heat, and the temperature rises fastest, and the internal temperature decreases in turn; in the process of loading and unloading, the grinding wheel is cooled and the outer ring temperature is lowered rapidly.

       2.1.2 Reasons for the grinding wheel

       The temperature distribution of different parts of the grinding wheel is uneven, and the temperature of the same part changes greatly at different times. The grinding wheel loses balance due to equipment reasons, and a large internal stress will be generated instantaneously. When this internal stress is greater than the adhesion between the grinding wheel abrasives When the force is combined, the abrasive particles will be torn apart, and the crack will continue to extend until the grinding wheel bursts.

       2.2 Preventive measures

       1) The inspector strengthens the daily inspection of the grinding machine equipment and eliminates possible hidden dangers.

       2) The grinding machine uses the clearance time of the equipment such as cleaning slag and bucket to stop the grinding head and chuck.

       3) If abnormal noise is found during the grinding process, stop immediately and check the equipment to prevent the occurrence of a film accident.

       3 Reasons for operation

       The edge of the grinding wheel is bumped and dropped; the side of the grinding wheel has contact with the slab; the slab is trimmed or angled.

       3.1 Analysis of the causes of the explosion

       The grinding wheel collides with the continuous casting billet, causing partial defects of the grinding wheel and a burst.

       3.2 Preventive measures

       1) Fine operation, focus on the corners of the grinding, and adjust the length compensation value in time.

       2) Reduce the pressure at the corners and adjust the pressure reduction coefficient or holding pressure to about 90%~95% of the normal grinding pressure.

       3) When the continuous measurement of the billet length is inaccurate, the equipment personnel shall be promptly reported for processing.

       4) 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.

       4.1 Analysis of the causes of the explosion

       1) The adhesion between the grinding wheel reinforcement layer and the use layer is poor, or the grinding wheel itself has cracks, which are cracked from the root during use and a burst occurs.

       2) The strength of the steel ring is not enough. When the explosion occurs, the steel ring breaks and does not play a role in preventing the fragments from scattering.

       4.2 Preventive measures

       1) Check the grinding wheel before use, and find that there are cracks or water stains or obvious bumps, stop using.

       2) Smoothly transport the grinding wheel during handling and installation to avoid impact and drop.

       3) Grinding the slab should control the temperature before grinding, and air temperature as required to avoid the explosion of the grinding wheel.