In order to investigate the influence of mandrel on the forming quality of bending L-shaped hollow parts, three types of mandrels, which are polyurethane rubber mandrel, low-melting-point mandrel, and ball bearing mandrel. Polyurethane rubber mandrel and low-melting-point mandrel, which supposed as elastic–plastic deformable part in the numerical simulation. The effect of different forms of mandrel on the forming quality of L-shaped hollow parts, such as section deformation and wall thickness variation, were compared with push bending without a mandrel. The results show that the low-melting-alloy mandrel leads to a better formability and a more uniform tube thickness distribution compared with the polyurethane rubber mandrel and ball bearing mandrel, for the low-point-melting mandrel brings about smaller stress in the bending process. Cold push-bending trials of rectangular cross-section tubes were conducted successfully based on the finite element simulation results. The experimental results showed that the formability and quality of L-shaped tubes greatly improved compared to no mandrel, ball bearing mandrel, and rubber mandrel when the low-melting-point-alloy mandrel was used as the flexible mandrel.
L-shaped hollow parts Cold push-bending Low-melting-point-alloy mandrel Numerical simulation
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