Deformation allocation is an important factor that affects 720° curling forming from copper-coated steel strips to double-walled brazed tubes (DWBTs). In this study, four schemes of deformation allocation, considering different weights of the total feed distance, are proposed, and a 3D finite element (FE) model of the multi-pass roll forming process for DWBT is developed and verified to investigate the cross-sectional evolution and deformation features. The results show the following. (i) In the 720° curling forming process from the steel strip into double-walled tubes, the curvature of the formed circular arc initially increases and then remains stable with roll forming, and the inner and outer tubes of the DWBT are formed in the third and fifth forming passes. Size forming can eliminate the gap between the double walls and improve the overall roundness. (ii) For different deformation allocations, the cross-sectional profiles of the roll-formed parts exhibit a discrepancy, and the deformation amount varies with the roll-forming process. The deformation amount in Scheme three is the maximum, and the cross-sectional profile deviates significantly from the ideal shape and fails to form a DWBT, which indicates that the deformation allocation is unsuitable. (iii) The roundness of the outer tube is better than that of the inner tube. Therefore, the roundness of the inner tube is the key to restricting the forming accuracy of the DWBT. Compared with Schemes one and two, Scheme four with a linear allocation of the total feed distance exhibits the best roundness, and the deformation allocation is reasonable; i.e., when the contact points between the rollers and steel strip are in a straight line, the roundness of the DWBT is in good agreement with the ideal condition.

变形分配是影响从镀铜钢带到双壁钎焊管 (DWBT) 的 720° 卷曲成形的重要因素。在这项研究中，提出了四种变形分配方案，考虑了总进给距离的不同权重，并开发并验证了 DWBT 多道次辊压成形过程的 3D 有限元 (FE) 模型，以研究交叉断面演化和变形特征。结果显示如下。(i) 在钢带720°卷曲成型双壁管过程中，成型圆弧的曲率先增大后随辊压成型保持稳定，双壁钢管的内外管在第三和第五次成型。尺寸成型可以消除双壁之间的间隙，提高整体圆度。(ii) 对于不同的变形分配，轧制件的横截面轮廓存在差异，并且变形量随轧制工艺而变化。方案三变形量最大，断面轮廓与理想形状偏差较大，未能形成DWBT，说明变形分配不当。(iii) 外管的圆度优于内管。因此，内管圆度是制约DWBT成形精度的关键。与方案一、方案二相比，总进给距离线性分配的方案四圆度最好，变形分配合理；IE