Abstract: To solve the reaction force inference on forming quality and precision which was generated by continuously compressed air in sealed cavity that was formed between the sheet and support in the CNC incremental negative forming process,a method to automatically generate a support die with vents of triangular mesh model by sheet metal parts CAD model was proposed.The algorithm to calculate empty cavity volume and pressure of support die,to identify the number of concave part on complex sheet parts and to generate a vent in the location of right place automatically which in turn generates a support die with vents of triangular mesh model were introduced.The case studies showed that the proposed algorithm could automatically generate a support die with vents.Sheet forming experiments indicated that the formation of confined spaces in the forming process leaded to a bulge deformation or fracture on sheet parts,but the support die with vents could effectively solve the problems mentioned above.

Key words: sheet forming, CNC incremental forming, support body, confined space, vent

摘要： 为解决数控渐进反向成形过程中板材与支撑之间形成密闭空腔,腔内空气不断被压缩而产生的对板材的反作用力影响板材件成形质量和成形精度问题,提出一种可由待成形板材件的CAD模型自动生成带有通气孔特征的支撑体三角网格模型的方法。给出了计算支撑体空腔体积与空腔内压强的算法、自动识别复杂板材件凹部数量与位置的算法,及其在合适的位置生成通气孔进而生成带有通气孔的支撑体三角网格模型的算法。应用实例表明,所提算法能够自动生成带有通气孔的支撑体。成形实验表明,板材件成形过程中密闭空间的形成会导致成形件鼓包变形甚至破裂,而带有通气孔的支撑体能够有效地解决上述问题。

关键词: 板材成形, 数控渐进成形, 支撑体, 密闭空间, 通气孔