Aim.The introduction of the full paper reviews a number of papers in the open literature and, in its last paragraph, proposes exploring the effect of spinning gap.Section 1 explains the method of our exploration, whose core consists of: ( 1 ) by introducing the shape size of a workpiece and its field variables after the first pass of spinning and springback, we establish the 3D finite element simulation model for the second pass which includes springback analysis and annealing operation; (2) using the simulation model, we investigate the effect of spinning gap on the forming quality of the second pass of spinning of large-sized complicated thin-walled metallic shell.Section 2 presents the simulation results and experimental results and their analysis.Its simulation results, given in Figs.7 through 14 and Figs.16 and 17, and their analysis show preliminarily that: ( 1 ) the forming height first increases and then decreases with increasing spinning gap, and there is a local wall-thickness reduction in the small cone angle segment of large-sized biconical workpiece; (2) the circumferential compression stress and tangential tensile stress both decrease with increasing spinning gap, thus reducing the possibility of fracture and wrinkle.Section 2's experimental results, given in Figs.18, 19 and 20, and their analysis show preliminarily that: (1) during the multi-pass of spinning of large-sized complicated thin-walled metallic shell, the wall-thickness of its workpiece should be reduced as much as possible in the first pass of spinning; (2)after the first pass, the shape of workpiece should be close to that of the next pass so that the spinning process can go on smoothly.Finally, through our exploration, we believe we have succeeded in making the shape of workpiece after the second pass of spinning meet the requirements for the final pass of spinning of large-sized complicated thin-walled metallic shell.%文章研究旋压间隙对大型复杂薄壁壳体多道次复合旋压的影响.通过采用导入第一道次旋压卸载回弹后工件形状尺寸与场变量信息的方法,建立了包含回弹和退火的第二道次旋压成形实体单元模型.研究了旋压间隙对大型复杂薄壁壳体第二道次成形质量的影响.结果表明:①随着旋压间隙的增加,成形高度先增加后减小,不同旋压间隙下大型双锥形件小锥角段均不同程度地存在局部壁厚减薄现象;随着旋压间隙的增加,周向压应力和切向拉应力减小,因此起皱和拉裂的可能性减小.②在大型复杂薄壁壳体多道次的旋压过程中,第一道次必须尽量减薄,形状尽量逼近后续道次成形形状.基于数值模拟结果确定的实验方案,获得了满足终旋要求的大型复杂薄壁壳体旋压预成形件.
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