Sendzimir mill backup bearing|support roller

The Sendzimir mill backup bearing or support roller is a critical component in a Sendzimir (Z-mill) rolling mill, which is used for cold rolling thin strips of metal, particularly stainless steel and high-strength alloys. These mills are known for their ability to achieve high reductions with excellent strip flatness control.

Function of Backup Bearings/Support Rollers in a Sendzimir Mill:
In a Sendzimir mill, the work rolls (small-diameter rolls that directly contact the strip) are supported by a cluster of backup bearings (also called support rollers or intermediate rolls). These bearings help:
– Absorb rolling forces to prevent deflection of the work rolls.
– Maintain precise roll alignment for consistent strip thickness.
– Reduce vibration and chatter during high-speed rolling.
– Extend work roll life by distributing load evenly.

Types of Backup Bearings/Support Rollers:
1. First Intermediate Backup Bearings – Directly support the work rolls.
2. Second Intermediate Backup Bearings– Support the first intermediate bearings.
3. Main Backup Bearings – The largest bearings in the system, absorbing the bulk of rolling forces.

Common Issues & Maintenance:
– Wear & Fatigue: Due to high cyclic loads, backup bearings can develop spalling or brinelling.
– Misalignment: Can cause uneven strip thickness or bearing failure.
– Lubrication Failure: Poor lubrication leads to overheating and premature wear.
– Contamination: Dirt or metal particles can damage bearing surfaces.

Materials & Design Considerations:
– High-grade alloy steel (e.g., bearing steel like 52100 or tool steel) for durability.
– Precision grinding & hardening to ensure smooth operation.
– Advanced sealing systems to prevent lubricant leakage and contamination.

Replacement & Upgrades:
– Regular inspections (vibration analysis, temperature monitoring).
– Using ceramic hybrid bearings for higher speed and longer life.
– Optimized lubrication systems, oil-air or gas systems.