Simulation of Interference Fitted Joint Strength as Used in Hot Rolling Work Rolls

Abstract

Composite work rolls consisting of a hard, wear resistant cast iron hub interference fitted to a tough, fracture resistant alloy steel shaft are typically used in the hot rolling of sections (e.g. rails, I-beams). The hubs are susceptible to fracture (due to their brittleness) and radial/axial slipping (due to overloading or improper design) when in service. The shaft may be reworked several times and new hubs fitted in order to extend the life, although an optimised solution is sought to identify the interference conditions at the interface that will minimise the probability of failure of both failure modes. This paper looks at the simulation and optimisation of interference fitted work rolls to try and minimise the torsional failure mode observed in practice under steady state as well as more extreme working conditions that work rolls are exposed to in service. Finite element models are validated experimentally using scaled laboratory tests. These models are then used to investigate the probability of failure during a normal working cycle and during extreme working conditions like cobbles (mill stalls). A number of key parameters are identified which support the effective design of interference fitted joints generally and under competing failure conditions.