Stretch forming is the basic bending forming method for aluminum profiles commonly used in the metal components of roof racks, which are important for both the appearance and load-bearing of vehicles. To address issues such as wrinkling on the inner side, surface depressions, and springback during the stretch forming process, these defects can be effectively resolved by selecting appropriate materials, optimizing cross-sectional shapes, and adjusting process parameters, thereby improving the forming accuracy.
- The stretch forming process enables the realization of the large curvature requirements for the Roof Rack made of aluminum alloy. The formability of the stretch forming process mainly includes section retention, final shaping, and fracture resistance.
- During the stretch forming process, certain defects such as surface straight marks, surface depressions, inner layer wrinkling due to instability, and springback may occur. However, under the premise of reasonable material selection, these defects can be effectively avoided or improved through cross-section optimization and process optimization.
- The elimination of support edges perpendicular to the outer surface of the cross-section can eliminate surface straight marks.
- Within a reasonable range, increasing the relative height, relative thickness of the upper panel, and minimum relative bending radius while setting an upper limit for the stretching amount can effectively improve surface depressions on the upper panel. Additionally, using core molds can also help to improve depressions.
- Ensuring sufficient pre-stretching and avoiding excessively small bending radii are fundamental measures to prevent wrinkling. The supplementary stretching process and the use of core molds can significantly improve mild wrinkling.
- Within a certain range, setting a reasonable stretching amount, increasing the relative height and minimum relative bending radius, reducing the coefficient of friction, and modifying the mold’s arc surface can effectively control springback.
Stretch forming is a complex process, and it requires a combination of simulation calculations and rational analysis to formulate the most suitable product structure and process plan.