How to Avoid Accidents in Cold Rolling?

In many steel rolling plants, especially in cold rolling production, accidents are most likely to occur, including operation accidents, equipment accidents, and quality accidents. All those directly affect equipment, quality, and output. So when accidents occur, remedies should be taken immediately.

1. The rolling piece is deviated, which usually occurs when the head is worn or the tail deviates when the belt is worn. It is caused by the uneven thickness of the incoming material, unskillful operation, old-fashioned roll holes, electrical problems, etc. The slight deviation during threading can be eliminated by timely adjusting and screwing down; for serious deviation, it is necessary to cut the strip steel in front of the frame, find out the cause of deviation, and then re-thread the strip; if it is found that the strip tail is deviated during tailing off, it is necessary to stop immediately, and lift the screw-down according to the situation to make the strip steel pass or cut it. When rolling a very thin strip, the roll is easy to be damaged due to deviation, so special attention should be paid.

　　

2. The rolling mill runout. Rolling mill runout usually occurs during high-speed rolling of extremely thin strip. Because of the beating, the thickness of the strip fluctuates, it is easy to break the strip. Therefore, once the rolling mill has obvious beating sound, the rolling speed shall be reduced immediately to eliminate the vibration. There are many reasons for the runout, such as high rolling speed, thin product thickness, low rolling pressure and small deformation of the finished pass, large tension before the strip steel, too good or too bad lubrication, insufficient roughness of the working roll, damage of the supporting roll, sudden change of various rolling parameters, large gap between the roll bearing and the bearing seat, etc. The cause of rolling mill vibration is complex and it is not easy to make a correct judgment. Through careful search and analysis, before the correct conclusion is reached, only the method of limiting rolling speed is used to prevent the occurrence of run out. 

2. The broken strip of rolled piece. There are many reasons for the broken strip of the rolled piece. Generally, it can be concluded as four kinds: defective incoming material, poor weld quality, misoperation, electrical and mechanical failure. In case of strip breaking, stop the mill immediately to reduce the loss. Serious belt breaking not only makes the work roll and even the support roll bond seriously, but also makes the treatment of the waste belt and the extraction of the work roll very difficult after bonding. Moreover, the treatment time is long and the labor intensity is large. After the belt breaking treatment, the equipment shall be inspected. The surface quality of the first coil of steel to be rolled after roll change shall be checked carefully. For the coil with weld, the mark of the weld position shall be accurate and clear. The rolling speed shall be reduced before the weld passes through the rolling mill. The steel coil with defects must be rolled slowly to minimize the occurrence of accidents in cold rolling production.

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The Operating Rules of Rolling Mills

Eight Precautions for Rolling Mills

1. Every time the rolling mill appears to be jogging, it must not exceed one second. The worm gear should be adjusted in place, and the adjustment amount should be completely equal on both sides to avoid side bends.

2. When operating the cold rolling mill, there should be a special person to guard, and there should be no phenomenon of no one to guard, so as not to find the equipment failure and not find it in time.

3. Under normal circumstances, a single cold rolling mill should not exceed 40% of the aluminum plate in a single thickness.

4. There must be no debris in the production line.

5. Adjust the amount of reduction and the number of passes according to the material of the incoming material and the capacity of the rolling mill.

6. When using a cold rolling mill, the relevant technical parameters must be in full compliance with the requirements, and it should not be operated under load.

7. Rolls should not be subjected to more serious wear and should be replaced if they are found to be worn out.

8. During the whole rolling process, if the roll affects the surface quality of the rolled piece due to wear, or the size and precision, the roll should be replaced immediately, and after the roll is replaced, the driving operation must be guaranteed 2 to 3 minutes.