Roller care and maintenance
In order to reduce the defects caused by the roll scrap, reduce abnormal roll consumption, the following measures should be taken:
(1) Cold rolls should not be used in a state with surface cracks. When the roll rolled strip, the surface may appear slight cracks, such as not found in time and grinding, will lead to the surface of the roll spalling, affecting product quality. This requires the mill operator to check in a timely manner, according to the provisions of the replacement roll.
(2) the use of reasonable rolling process. To reasonably select the rolling force, tension and depression, minimize mill accidents, such as strip slippage and broken strip. The mill operator should correct the excessive deformation of the strip, and the mill should run at a low speed when passing the weld, so as to avoid the impact of the uneven weld on the roll surface.
(3) Let the cooling and lubrication system of the mill work properly. Rolling mill in the process of zapping will produce a lot of heat, and the rolls and the strip between the friction is also very large, if there is no cooling and lubrication capacity, the surface of the rolls and the temperature of the strip will rise, so that it is easy to produce thermal scratches and adhesion. Therefore, there should be coolant pressure, concentration and flow.
(4) preheating cold rolls, reduce stress. Before the new cold rolls are put into use and each time they are used after grinding, the rolls are generally preheated in 110 to 105 ℃ in the oil for 4 to 6h, which can reduce most of the surface stress. After the rolls on the machine, the rolling speed should be slowly increased to preheat the rolls.
(5) winter on the rolls just replaced to keep warm, even cooling, so as to avoid excessive temperature difference caused by stress changes.
(6) correct grinding. Each time the use of roll grinding machine grinding to make the surface of the roll work hardening layer cleaned up, while the required finish, just replaced the roll in the stress reduction before processing.
(7) rolls have a moderate workload, new and old rolls to alternate. Try to give the roll longer aging time.
(8) Strengthen the roll flaw detection. Currently used means of flaw detection are eddy current, magnetic particle and ultrasonic flaw detection, the first two main test surface defects, ultrasonic flaw detection can be found defects. According to the actual situation, take different flaw detection methods or a combination of several flaw detection methods to detect and protect the quality of the roll.