Sendzimir Bearings or Z-mill Bearings
Characteristics of Sendzimir Mill Bearings:
1. Heavy workload:
The unit pressure of supporting roll bearings is 2-4 times higher than that of general purpose bearings.
PV value (product of bearing unit pressure and linear velocity) is 3-20 times that of ordinary bearing.
2. Poor working conditions:
There are oxidation spatter during roll cooling.
The processing lubricant can not be mixed with bearing lubricant, and there is higher requirement of bearing seals.
3. High requirement for bearing manufacturing precision:
Bearing’s rotational accuracy need to reach P4.
Interface height difference of all bearings on the same shaft ≤ 0.005mm.
The difference between the wall thickness of adjacent bearings ≤ 0.002mm.
Failure modes of Sendzimir bearings:
1. Fracture of Outer Ring:
The bending moment of the inner raceway will be produced by the local force on the outer diameter of the supporting roller bearing. If the strength of the outer ring is not enough, it often causes the outer circle to break.
2. Improper roll adjustment and maintenance:
Due to the different installation position and tolerance of the bearing, the bearing force is uneven, and the outer ring of the bearing is easily worn, which leads to the recess of the work roll shaft line and the defect of the rolled thin plate. Therefore, it need to adjust the deflection of the supporting roller shaft to compensate for the bearing. With maximum force and easy overload, it results in the increase of internal wear of the bearing.
TEDIN have our own strict producing control system:
1. Raw Material: TEDIN use imported raw material of TIMKEN 3311 & 4320 for sendzimir bearings. Compared with internal carburizing steel, imported material have higher purity of chemical composition.
2. Forging Process: The forging is heated by temperature-controlled furnace, and many times the pier diameter and cold drawn, which makes the forging ring’s internal streamline distribution is more uniform and the crystal is better.
3. Heat Treatment Process: We apply AICHELIN heat treatment furnace, which is no different from the foreign heat treatment technology. It can effectively ensure the bearing parts with no oxidation, heat treatment quality grade and the high reliability and stability of metallographic structure during heat treatment process.
4. Quality Control: TEDIN has its own bearing rollers producing line. The rollers can be produced with logarithmic curve, which can reduce the stress concentration of the bearing roller’s edges. It effectively increase the serve life of the sendzimir mill bearings.
Typical success cases:
Case I:
Sendzimir mill (Z-mill): 20 high cold rolling mills for steel strip.
Applied bearing types: NNCF3680181X （sealed type), NNCF2660168X （sealed type）
Rolling mills for steel types: alloy steel, stainless steel, beryllium copper, etc.
Working roll：Φ45~50×550 mm
Blank width：300~450 mm
Blank thickness：< 2.0mm
Rolling speed：<420M/min
Coiling tension：2.5~100KN
Rolling Pressure：<1500KN
Case 2:
Sendzimir mill (Z-mill): 12 high cold rolling mills for steel strip.
Applied bearing types: NNCF43110205X （sealed type), NNCF3680171X （sealed type), NNCF3680224X （sealed type）
Rolling steel types：Carbon Steel、Nonoriented silicon steel、Oriented silicon steel, etc.
Working roll：Φ150~140mm×1450 mm
Blank width：900~1350 mm
Blank thickness：< 3.5mm
Rolling speed：<750M/min
Coiling tension：≤300KN
Rolling Pressure：<10000KN
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