The world No. 1 in crude steel production steel plant, over 70% of the HSS for bar and wire are from us.

YUAN HUI

YUAN HUI

LMM GROUP main products focus on the cold and hot plate & wide strip mill rolls and heavy section mill rolls and big casting & forging pieces.

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Causes of mill rolls breakage

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1: Brittle fracture
The fracture shape of this type of roll is relatively flat, and the surface of the roll body around the fracture is relatively neat;

2: Ductile fracture
The fracture shape of such rolls is mostly “mushroom head”, and the roll body near the fracture is crushed. Comparing the two, it is found that the form of roll breakage in this roll breaking accident is ductile fracture.

Both brittle and ductile fractures are caused by roll stress exceeding core strength. The reasons for this are related to the residual stress of the roll itself, the mechanical stress during rolling and the thermal stress of the roll, especially when the temperature difference between the surface and the core of the roll body is large.
This temperature difference can be caused by poor roll cooling, interruptions in cooling, or overheating of the roll surface at the start of a new rolling cycle. This huge temperature difference between the surface and the core of the roll causes large thermal stress, and when the large thermal stress, mechanical stress and residual stress of the roll exceeds the core strength of the roll, it causes the roll to break. For example, when the temperature difference between the surface of the roll and the core is 70°C, the roll will increase the longitudinal thermal stress of 100MPa. The greater the temperature difference, the greater the increased thermal stress. Compared with rolls with brittle fractures, the core material of rolls with ductile fractures has better toughness and is less prone to fracture. There are four types of stresses that cause roll failure:

  1. Residual stress in the manufacturing process;
  2. Mechanical stress during rolling;
  3. The tissue stress of the roll during the rolling process;
  4. Thermal stress caused by the temperature difference between the inside and outside of the roll.

rolling mill rolls steel roller

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Rolling mill rolls product

Classification by roll material:

Cast iron mill rolls

  • Alloy indefinite chilled cast iron rolls
  • Alloy chilled cast iron rolls
  • Alloy SG ductile cast iron roll
  • Pearlitic ductile cast iron roll
  • Bainite ductile cast iron roll
  • Centrifugal cast iron roll


Cast steel mill rolls   

  • Alloy cast steel rolls
  • Semi-steel roller
  • Graphite steel rolls
  • High-chromium steel roll
  • High-speed steel roll


Forging mill rolls

Sort by position on the rolling mill:

Work rolls
backup rolls

Intermediate roll

Product advantage

The world No. 1 in crude steel production steel plant, over 70% of the HSS for bar and wire are from us.

LMM high-speed steel rolls have higher steel passing per groove (times) due to their good wear resistance, which saves roll changing time, improves rolling mill operation rate, reduces roll consumption, and improve the overall efficiency of the factory.
Generally, the amount of steel passing in a single groove (times) is 3 to 5 times that of cast iron rolls.

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