Speaker
Description
This study investigates the bulging deformation and poor dimensional accuracy observed during the roll bending of longitudinal pipes with a large length-to-diameter ratio, which arise primarily from insufficient upper-roll stiffness and a lack of external support. To address these issues, a novel anti-deflection roll bending (ADRB) process is proposed in combination with an optimized upper-roll profile design. Analytical models for the rolling force and side-roll displacement are developed under conditions where the plate's entry end is straight and where the C value is taken into account. Based on the principle of superposition, deflection models of the upper roll for both conventional roll bending and anti-deflection roll bending are established, and a mathematical model together with an optimization algorithm for the anti-deflection compensation displacement is formulated. Finite element models are constructed in ABAQUS to perform process parameter optimization and to correct the proposed theoretical models. Numerical results indicate that, compared with conventional roll bending, the maximum upper-roll deflection during the pre-bending and roll-bending stages is reduced by 77% and 71%, respectively, leading to a significant improvement in pipe geometry. To further mitigate the residual deflection of the upper roll in the ADRB process and enhance forming accuracy, a Fourier series fitting method is employed to optimize the upper-roll profile. After optimization, the maximum generatrix straightness in both forming stages is reduced by more than 80%, resulting in a substantial improvement in forming precision. The results demonstrate the feasibility and effectiveness of the combined anti-deflection compensation and roll-shape optimization strategy for improving the dimensional accuracy of large-diameter welded pipes with large length-to-diameter ratios.
| Speaker Company/University | Yanshan University |
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