THERMAL-STRESS OPTIMIZATION IN METAL ROLLING

It is known that internal pressure in rolls has an advantageous effect upon the fatigue life of the rolls. To investigate and optimize this effect, transient and steady-state temperature and thermal stress dist ributions were evaluated in rolls of metal rolling machines heated ove r the rolling region. The problem is formulated as that of a thick-wal led hollow cylinder heated on its outer surface by a rotating source a nd subjected to an internal pressure. For long rolls two-dimensional a nalysis is performed and the temperature distribution is evaluated usi ng the integral transform method. Thermal stresses are evaluated using the Airy's stress function in conjunction with the thermoelastic disp lacement potential technique The convergence and the numerical accurac y of the series solution is investigated. The results for the temperat ure distribution and thermal stresses given by the present method are in good agreement with those previously reported for the case of absen ce if internal pressure. This work is focused on establishing the depe ndence of the equivalent stress on the prestress condition, and numeri cal results are given for various values of the parameters involved. T he pressure value that minimizes the total equivalent stress and the s tress range, thus extending the fatigue life of the roll, is given for some cases of practical interest.