轻合金矩形管件充液压制成形缺陷及横截面尺寸控制

Tube hydro-pressing is an advanced less-loading hydroforming process. It can be used for integral forming of the thin-walled tubular components with complex shape. Different from the high-pressure hydroforming, the internal pressure only plays a supporting role in the tube hydro-pressing process to avoid buckling instability, and the components is mainly formed by the die pressing to form the complex contour. However, there is a stress gradient of tensile and compressive stress in the thickness direction of the tube during the hydro-pressing process, which cause the springback on the cross-sections easily after unloading. This can affect the dimensional accuracy of the components. In this investigation, the hydro-pressing experiment was conducted on three light alloy tubes, including 5052 aluminum alloy, AZ31B magnesium alloy and TA1 titanium alloy. The effects of internal supporting pressure and circumferential compression ratio on the cross-sectional dimension of rectangular tubular components were analyzed. The results show that the tubular components have the smallest springback when the internal supporting pressure is between 0.6p_s and 0.8p_s. The maximum springback amount is less than 1.5 mm, and the corresponding springback ratio is less than 5.2%. Moreover, the difference between the upper and lower corner radius is less than 0.1mm. The springback of the tubular components can be reduced by controlling the circumferential compression ratio during the hydro-pressing process. In this case, the difference between the actual cross-sectional dimension and the design value after spring back is less than 0.2mm, which corresponds to a dimension deviation of less than 0.7%. For the 5052-H, 5052-O, AZ31B-M and TA1-Y rectangular tubular components, the critical circumferential compression ratios required to control dimensional accuracy are 1.8%, 1.7%, 1.9% and 1.8%, respectively.