Bending forming method for tubes with small bending radius based on push-spin integration

A push-spin integrated (P-SI) bending forming method was proposed for tubes with small bending radius. A spinning wheel device is incorporated on the inner side of the die’s bend, allowing either passive or active rotation of the spinning wheel. This setup can reduce friction or alter the direction of the friction force at the intrados of the bent tube, enhancing the stress-strain condition therein. A finite element model for the P-SI bending forming was established. The simulation results indicate that this forming procedure reduces the sensitivity of the length of the output zone to the tube’s internal medium reverse thrust. This is advantageous in mitigating the wrinkling defect of the bent tube by increasing the internal medium pressure. Additionally, it facilitates material flow at the intrados of the bent tube, extending the output zone’s length and reducing the occurrence of excessive wall thickening. An experiment using a 0.9 D aluminum alloy thin-walled tube with P-SI bending forming was conducted. The experimental results demonstrated that compared to the conventional push-bend forming technique, the output zone’s length in tubes formed by the P-SI process doubled, which was consistent with the finite element simulation results.