In the production of hot rolled sheet, because the working roll contacts the rolling piece directly, bears certain high temperature, certain rolling pressure and transfers considerable rolling moment at the same time, its damage is quite serious in the rolling process compared with other parts of the rolling mill. The work roll is a large tool and die, which is expensive and inconvenient to replace. Once damaged, it directly affects the normal production. Moreover, it greatly increases the rolling cost. This article combines with our factory. In the production of Qinhe-Qin alloy sheet by four-roll reversible hot rolling mill, the damage of work rolls in hot rolling over the past ten years is classified and the failure causes are preliminarily qualitatively analyzed.
Failure form of work rolls：
The working roll is worn and grinded continuously during rolling. After each grinding, the diameter of the roll decreases and the service life lasts for a long time. When the surface hardened layer is grinded or the diameter of the roll decreases to a dangerous section which can withstand the rated rolling pressure, the service life of the roll terminates. This failure mode belongs to normal destruction. But most of the hot rolling work rolls in our factory are discarded due to the following abnormal damage forms in the normal use process.
Surface cracks, cracks, local slag dropping, local peeling, skin bursting, roll body breaking, roll neck twisting, roll surface printing, roll concave pit, sticking roll, casting shrinkage hole and shrinkage. By investigating the causes of failure of work rolls, the failure caused by accidents and the causes of rolls themselves is eliminated. In normal use, most of the failure modes are cracks, slag dropping and roll neck twisting.
Failure Reasons of hot rolling work rolls：
Through the analysis of rolling process, the main causes of work roll failure are the change of roll temperature and the huge rolling moment of work roll.