Li Ruxiong, Wang Tao, Li Feng
Faculty of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 211100, China.
Faculty of Mechatronics Engineering, Jingdezhen Ceramic University, Jingdezhen 333403, China.
Materials (Basel). 2023 Apr 18;16(8):3176. doi: 10.3390/ma16083176.
In light of the analysis on the single point incremental forming (SPIF) principle of perforated titanium sheet and the corresponding peculiarities during the forming process, it is found that the wall angle constitutes the pivotal parameter influencing the SPIF quality of the perforated titanium sheet, and this is also the key evaluation index to test the application of SPIF technology on a complex surface. This method for integrating the experiment and the finite element modelling was utilized in this paper to study the wall angle range and fracture mechanism of Grade 1 commercially-pure α titanium (TA1) perforated plate, plus the effect of different wall angles on the quality of perforated titanium sheet components. The forming limiting angle, fracture, and deformation mechanism of the perforated TA1 sheet in the incremental forming were obtained. In accordance with the results, the forming limit is related to the forming wall angle. When the limiting angle of the perforated TA1 sheet in the incremental forming is around 60 degrees, the fracture mode is the ductile fracture. Parts with a changing wall angle have a larger wall angle than parts with a constant angle. The thickness of the perforated plate formed part does not fully satisfy the sine law, and the thickness of the thinnest point of the perforated titanium mesh with different wall angles is lower than that predicted by the sine law; therefore, the actual forming limit angle of the perforated titanium sheet should be less than that predicted by a theoretical calculation. With the increase in the forming wall angle, the effective strain, the thinning rate, and the forming force of the perforated TA1 titanium sheet all increase, while the geometric error decreases. When the wall angle of the perforated TA1 titanium sheet is 45 degrees, the parts with a uniform thickness distribution and good geometric accuracy can be obtained.
通过对穿孔钛板单点增量成形（SPIF）原理及成形过程中相应特点的分析，发现壁角是影响穿孔钛板SPIF质量的关键参数，也是检验SPIF技术在复杂曲面应用的关键评价指标。本文采用实验与有限元模拟相结合的方法，研究了1级工业纯α钛（TA1）穿孔板的壁角范围和断裂机理，以及不同壁角对穿孔钛板零件质量的影响。得出了穿孔TA1板在增量成形中的成形极限角、断裂及变形机理。结果表明，成形极限与成形壁角有关。穿孔TA1板在增量成形中的极限角约为60°时，断裂模式为韧性断裂。壁角变化的零件比壁角不变的零件壁角大。穿孔板成形件的厚度不完全符合正弦定律，不同壁角的穿孔钛网最薄点的厚度低于正弦定律预测值；因此，穿孔钛板的实际成形极限角应小于理论计算值。随着成形壁角的增大，穿孔TA1钛板的有效应变、变薄率和成形力均增大，而几何误差减小。当穿孔TA1钛板的壁角为45°时，可获得厚度分布均匀、几何精度良好的零件。
