Achieving an Interference Fit Between Two Rings During Composite Ring Rolling

Composite ring rolling could bring substantial material, cost, and energy savings and allow for lighter weight components, by joining concentric rings with different material properties. For there to be any possibility of achieving a material bond, an interference fit between the rings must be maintained. In this paper, a force equilibrium-based model is introduced to predict when such a fit is possible. This model, for radial composite rolling, predicts a limit to the flow stress of the inner ring relative to the outer ring, suggesting a maximum ratio of about 160%. It also shows that the inner tool’s diameter must often be significantly smaller than the outer tool’s. The model is tested in four composite ring rolling experiments with two grades of Aluminium alloy, 1050 and 6063, and different tool sizes. An interference fit was achieved in two cases: (1) when the inner ring is Al 1050 (flow stress 52% of the outer ring); and (2) when the two rings are both Al 6063 and the inner tool diameter was 39% of the outer tool. It was not achieved when (1) the materials were reversed nor when (2) the inner tool increased to 59% of the outer tool diameter. These outcomes were all predicted by the model, a potentially valuable new guide to designing composite ring rolling processes