为实现6061-T4大直径薄壁铝管数控弯曲精确成形,提高其成形极限与质量,需对弯曲过程中壁厚变化进行有效控制.本文以该材料Φ50.8 mm×0.889 mm×101.6 mm（直径D×壁厚t×弯曲半径R）薄壁铝管为研究对象,实验研究了弯曲角度、芯棒伸出量、芯球个数、弯曲速度等可控参数对壁厚的影响规律.研究结果表明：在整个弯曲段内,中性层并不是均匀地发生等距离偏移,中性层偏移量（E）与内外脊线壁厚变化率差值（η）存在线性关系,E随η的增大而增大;增大弯曲角度、芯棒伸出量、弯曲速度都导致内外脊线壁厚变化程度加重,管材壁厚变化不均匀度加剧;芯球个数对壁厚的影响呈非线性;基于优化的工艺参数组合,成功获得最大壁厚减薄率为22%的180°合格弯曲管件.
To realize the precise NC bending and improve the bending quality of 6061-T4 large diameter thin-walled Al-alloy tube,physical experiments of the 6061-T4 Al-alloy tube of Φ50.8 mm×0.889 mm×101.6 mm（out diameter D×wall thickness t×bending radius R） are carried out to investigate the influence of some controllable parameters（including bending angle,mandrel extension,number of mandrel balls and bending rate） on the wall thickness variation.The results show that the strain neutral layer E moves unequally in the bending area,the amount of its movement has a linear relationship with the difference between the wall thickness change ratio of the intrados and extrados（η）,and E increases with the increasing of η.The maximum wall thickness changing degrees at the extrados and intrados increase with the increasing of bending angle,mandrel extension and bending rate,while the influence of number of mandrel balls is nonlinear.Based on the optimized parameters,the 180° bent tube with maximum thinning ratio 22% is successfully obtained.
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