According to the rolling material, pass, reduction, rolling speed and type of rolling products, etc., the material of the mill roll and the hardness of the working face of the mill roll body are reasonably selected. The principle of using mill rolls is: high hardness is suitable for finishing rolling, medium hardness is suitable for intermediate rolling, and low hardness is suitable for preliminary rolling. The following matters should be paid attention to during the use of the roll:
1. The mill rolls are protected from any collision damage during transportation.
2. The mill roll should be stored in a dry and ventilated room to prevent moisture, and the surface should be coated with anti-rust oil.
3. The surface oil, dust, and rust should be wiped off before the mill roll is used, and then a routine inspection is carried out to check whether there are any scratches on the surface of the roll body and roll neck (including indentations, rust spots, cracks, and other defects), and the rolls with surface defects are not allowed to be removed Use on the machine.
4. Before the mill roll is put into use, a roll quality account should be established, the roll number, size, and relevant test results should be recorded, and the original records should be archived.
5. Do a good job in the installation of the mill rolls. Before installing the roll neck bearings, all debris should be removed. The assembled bearings must be in place accurately. The horizontal and vertical parallelism on the frame should be corrected on-site to prevent scratches or bumps on the roll surface.
6. Before rolling, the quality of the rolled billet should be carefully checked, and the operation should be carried out in strict accordance with the rolling process to prevent the rolling of low-temperature steel, and to prevent the overloading of the rolling process from affecting the service life of the roll and the occurrence of roll breakage accidents.
7. The mill rolls should meet sufficient cooling and lubrication conditions during the rolling process to reduce the hot corrosion, thermal fatigue, and thermal stress of the rolled products on the surface of the rolls, and prevent hot cracks, chipping, and peeling during the rolling process. Ensure the lubrication between each transmission shaft to prevent quality accidents caused by transmission obstruction.
8. The cooling water used in rolling should be neutral to prevent it from being polluted by impurities. Water with strong acidity or alkalinity will corrode the roll. The water temperature should be kept at ≤30℃. The cooling water quality, water temperature, and water pressure all directly affect the wear resistance of the roll.
9. During the rolling process, the rolling products should be prevented from deviating, stacking, stacking, or bringing in foreign objects, so as to prevent the corrosion products from being embedded in the metal, damaging the rolls, and causing the rolls to be scrapped.
10. The hot rolls replaced from the rolling mill should not be stacked on the wet and cold ground to prevent the uneven heating and corrosion of the roll surface from affecting the service life, and the direct collision of the rolls should be avoided.
11. Establish a reasonable mill roll change cycle, formulate a roll change grinding system, and cooperate with corresponding non-destructive testing methods to ensure that the machining, turning and grinding processes comply with the grinding system.
12. When cutting or grinding work rolls, the minimum cutting amount and grinding amount for each processing should ensure that the fatigue layer is eradicated. The depth of this layer is generally 0.15-0.30mm. The fatigue layer should be completely removed (the depth of this layer is generally 2-5mm) to prevent the crack extension from leading to spalling.
