Roll service condition: The final rolling speed of the normal line is 40-60m/s, and the high line speed is 70-120m/s. The speed is high, the impact is large, and the pollution is serious. The four-row cylindrical roller bearings must be interchangeable. Finishing mill unit service condition: Cone box and roller box bearings are specially designed, and the bearings are paired angular contact bearings and cylindrical roller bearings, 120m/s sixth-generation wire rod finishing mill bearings. The bearing performance indicators reach Class P2, and the rotation speed reaches 12000r /min, and the entire bearing requires high rotation speed and impact resistance.