"ANALYSIS OF STRESS FIELDS IN COILS WHILE BATCH ANNEALING"
Abstract:
Thermal stresses generated within wound coils during batch annealing contribute to several
problems. High inter-wrap contact pressures are associated with adhesion of coil wraps and
consequent "sticker" defects. Conversely, a thermally induced reduction in
contact pressure may allow wraps to buckle and move. Understanding the as-wound stress
field in a cold rolled coil and how this is modified by thermally induced stresses through
the annealing process has been limited by a lack of investigative tools. Hatch IAS
has now taken the major step of integrating the coil winding and batch
annealing models.
The temperature field within
the coil at each step in the annealing process is utilized to predict thermal stress,
which superimposes upon the stress field previously developed in the coil winding process.
Insights gained have been used in reducing the incidence of several chronic industry
problems, saving scrapped coils and downgrades. This paper describes the causes of various
problems, and how they can be controlled by modifying the coil winding tension practice
and by adjusting the heating and cooling cycle in the annealing furnace. Email hatchias_info@hatch.ca for a copy of this paper. |