Prediction of roll temperature with a non-uniform heat flux at tool and workplace interface

In a metal forming process, plastic deformation of the workpiece takes place at tool and workpiece interface region. Tool has been identified as one of the key parameters in controlling the productivity of any manufacturing industry. The deformation of metals and friction at the contact region produce large amount of heat, a part of that heat is conducted towards the tool where it is removed by forced convection. These cooling and heating cycles finally result in a substantial change in the temperature distribution in the roll. In this paper, an attempt is made to study the temperature and heat flux distribution in the roll by considering a non-uniform heat flux at the roll-workpiece interface for a cold rolling process. Adopting an elemental approach, a methodology has been proposed to model non-uniform heat flux at the interface. For this purpose both tool and workpiece has been considered together, thus a coupled approach is used to model both deformation and heat transfer phenomenon. It is demonstrated that the present approach of modeling is more general than that available in the literature. For example, a constant value of heat flux at the interface that is considered by several investigators is shown to be a special case of the present investigation, particularly when the deformation and relative velocity is very small. It is shown that the error in maximum temperature associated with constant heat flux assumption could be more than 5% in situations when reduction and relative velocity is high. The results are presented for temperature and heat flux distributions in the roll for different operating conditions.