As important structural freeform panels (FFPs) for medical implants and aerospace system, lightweight thin wall panels with lower ductility are conventionally produced by hot forming process by utilizing the die on the press, which is not efficient or cost-effective for small batch or customized manufacturing. The dieless incremental sheet forming (ISF) provides a promising solution with increased formability, but making sheet metal panels with low-ductility at room temperature is still a challenging work. Targeting to solve this puzzle, a novel ISF without edge constraint on the target blank between the two edge-fixed supporting layers is developed to get flexible and free plastic deformation for the target blank. To reveal the deformation mechanism of this new method, an analytical prediction model of sheet thickness in ISF process is developed to calculate the deformed thickness in severe thinning region, which indicates that the undesired severe thinning region of conventional ISF process is caused by different stress states near the constrained edge, and can be completely eliminated by this proposed method to obtain uniform plastic deformation and improved formability. Different FFPs of magnesium alloy AZ31 and titanium alloy TC4 are fabricated by the novel flexible free ISF (FFISF) to validate the improved formability, and compared with conventional ISF and three-sheet incremental forming. Experimental studies demonstrate that the proposed method provides potentials for flexible fabrication of FFPs with low ductility at room temperature. More importantly, the promising geometric accuracy without trimming can be obtained by this new method, and multiple axisymmetric parts can also be formed within a cycle time.

作为用于医疗植入物和航空航天系统的重要结构自由成型面板（FFP），传统上利用压力机上的模具通过热成型工艺生产延展性较低的轻质薄壁面板，这对于小批量或定制的效率或成本效益不高制造业。无模增量板成形 (ISF) 提供了一种具有更高可成形性的有前景的解决方案，但在室温下制造具有低延展性的金属板仍然是一项具有挑战性的工作。为了解决这个难题，开发了一种在两个边缘固定支撑层之间对目标毛坯没有边缘约束的新型 ISF，以获得目标毛坯的柔性和自由塑性变形。为了揭示这种新方法的变形机制，建立了ISF工艺板材厚度解析预测模型，计算了严重减薄区域的变形厚度，表明常规ISF工艺的非预期严重减薄区域是由约束边缘附近的不同应力状态引起的，可以完全消除通过这种建议的方法获得均匀的塑性变形和改善的成形性。镁合金AZ31和钛合金TC4的不同FFP由新型柔性自由ISF（FFISF）制造，以验证改进的成形性，并与传统的ISF和三片渐进成形进行比较。实验研究表明，所提出的方法为柔性制造室温下具有低延展性的 FFP 提供了潜力。更重要的是，