Formation mechanism and control method of multiple geometric defects in conical-section profiled ring rolling

In the conical-section profiled ring rolling (CSPRR), due to the asymmetrical geometric features and uncoordinated deformation of the ring along the axial direction, multiple geometric defects may occur, such as diameter error (i.e., the diameter of big and small ends cannot simultaneously reach the target values), roundness error and tilting. In this work, a growth velocity model, describing the ring diameter growing behavior at different axial positions, is developed through the theoretical analysis. Based on the growth velocity model, the largest growth velocity difference along the axial direction is expressed by a mathematical function which relates to the ring geometry parameters (including inner slope angle alpha(1), outer slope angle alpha(2), ring height H) and the mandrel feed rate v(f). Further, combined with a mass of FE simulations, it is found that the growth velocity difference along the axial direction is the formation mechanism of multiple geometric defects in CSPRR process. By adjusting alpha(1) or alpha(2), reducing H or reducing v(f), the largest growth velocity difference along the axial direction can be made close to zero, which is beneficial to improving geometric accuracy. Following the above understanding, three methods to avoid geometric defects are proposed, including the improved design of target rolled ring (forging drawing), the reduction of v(f) and the improved design of ring blank, which are applied in the process design for a complex conical-section casing ring. The corresponding simulations and industrial experiment indicate that the proposed methods work well to avoid multiple geometric defects.

Automated summary

This study investigates the formation mechanism and avoidance methods of geometric defects in the conical-section profiled ring rolling process through a growth velocity model and finite element simulations, proposing design adjustment schemes to improve geometric accuracy.