Numerical Study on Motions of Rolls in Hot Rolling of Titanium Alloy Large Rings

Titanium alloy is sensitive to strain rate, so motions of rolls are crucial to the hot rolling process of titanium alloy large rings. In the study, firstly, the relative velocity vr was proposed to synthesize motion parameters of rolls, including the rotational velocity of the driver roll n1 and the feed rate of the idle roll v, and then the reasonable range of vr was determined analytically based on the stable forming condition. Secondly, a reliably coupled thermo-mechanical 3D-FE model of the process was developed in the dynamic explicit code ABAQUS/Explicit. Finally, the effect of vr on the process was studied using FE simulation. The results obtained show that although increasing vr by two different ways, i.e., by decreasing n1 or by increasing v, makes the feed amount per revolution Δhi increase, not all of their effects on the process are in agreement, such as for the nonuniformity of strain distribution. An appropriately larger value of vr is helpful to improve the end-plane quality and make strain and temperature distributions in a deformed ring more uniform, but has an adverse influence on the roll force.