What are the key points of daily maintenance for the roller bearings of Two High Rolling Machine

       Roll bearings are core load-bearing parts of Two High Rolling Machine. They work under heavy load and impact load, and are exposed to contaminants such as rolling emulsion, cooling water and metal dust. Bearing failure may lead to roll seizure, roll neck damage and unexpected shutdown. Standard daily maintenance focuses on lubrication, sealing protection, condition monitoring, roll change inspection and clearance control.

1. Standardize lubrication, select suitable lubricants and follow correct filling quantity and cycle

       Lubrication is the top priority for bearing maintenance. For hot rolling, high-temperature and water-resistant extreme-pressure grease is recommended. For cold rolling, oil-air lubrication or circulating oil lubrication can be adopted according to configuration. Never mix different greases, as incompatibility will break the lubricating film.

       Filling volume must be controlled properly. Overfilling causes excessive heat build-up. Normally fill about one third of the bearing cavity. Follow the re-lubrication interval specified by the manual. Shorten intervals for high-speed, heavy-load and high-temperature rolling conditions. Clean old grease and debris from chocks during every roll change before adding fresh lubricant.

2. Inspect sealing components regularly to block water, emulsion and debris

       Seal failure is the leading cause of premature bearing damage. Check oil seals, labyrinth seals and dust rings for aging, crack or distortion during daily inspection. Cooling water in hot rolling and rolling emulsion in cold rolling will dilute lubricant, trigger rust and spalling once entering the bearing cavity.

       Replace worn seals during roll disassembly. Check sealing mating surfaces for wear grooves. Stop production immediately if leakage is found.

3. Monitor temperature, vibration and noise continuously for early warning

       Carry out periodic inspection with thermal guns and vibration meters, or install online sensors for continuous monitoring.

       Stable temperature rise is normal. Continuous temperature rise, abnormal vibration or irregular knocking and friction noise indicate damage on raceways, rollers or cages. Technicians need to identify root causes: insufficient lubrication, water ingress, unbalanced load or fatigue spalling, to avoid bearing seizure.

4. Disassembly, cleaning and internal clearance check during roll change

       Roll change is the best maintenance window. Disassemble chocks and clean bearings thoroughly. Inspect raceways, rolling elements and cages for pitting, flaking, indentation and corrosion.

       Bearing internal clearance is critical. Too small clearance leads to overheating and seizure; excessive clearance increases impact and vibration, and worsens strip shape. Replace bearings when clearance exceeds allowable tolerance. Also check roll neck surface; scratches or wear on roll neck will destroy fit and accelerate bearing failure.

5. Maintain roll alignment and balanced load to reduce eccentric load

       Misalignment between two rolls and frame offset will cause continuous overload on one side of bearings, concentrating local stress and shortening service life. Regularly calibrate roll parallelism and screw-down synchronization to prevent strip wandering and uneven loading.

Avoid over-reduction and overload rolling to reduce fatigue damage from impact load.

6. Keep maintenance records and implement bearing life management

       Record installation time, rolling material, total running hours, fault history and replacement logs for each bearing set. Schedule preventive replacement based on historical data instead of emergency repair after breakdown. For high-volume two-high mills, preventive maintenance greatly cuts unplanned downtime.