Analysis of surface cracking in water-cooled rolls and heat transfer between furnace chamber and rolls in a direct flame furnace

In the direct fired furnace of a continuous annealing line,seal rolls are susceptible to deformation that leads to surface defects of steel strips. According to failure analysis,the reasons include improper structural design and heat imbalance. An improved design has been proposed to reduce stress concentration and thermal radiation. A heat transfer model has been employed to determine the proper water flow rate for roll cooling. Industrial application proves that seal rolls with the new design has less deformation and longer service life.