柔性压辊拉形中压辊下压位移量的数值解析

Numerical Solution of Press Amount of Roller in Flexible Roller Stretch Forming

利用柔性压辊拉形的几何关系,得出了使板料完全贴模时压辊的最小下压量及其所对应的板料最小延伸率,并根据不同截面上板料在拉伸方向延伸率相等的原则,建立了压辊最大下压量与延伸率的关系。采用位移加载对08AL马鞍形件和球面件的成形过程进行了数值模拟,并与力加载的成形结果进行了对比,结果表明:位移加载成形曲面件的等效应力和等效塑性应变分布更均匀,成形质量更稳定。利用柔性压辊拉形装置拉伸成形了马鞍形件和球面件,结果表明,采用数值计算所得的压辊下压位移量进行加载是可行的。与力加载相比,压辊下压位移量的数值求解方法可快速计算出对应于不同延伸率时各个压辊加载所需的下压位移量,节省了加载力的调试时间,可应用于柔性压辊拉形工艺参数的调试。

Utilizing the geometrical relationship of flexible roller stretch forming, the minimum press amount of roller and the corresponding minimum sheet elongation were calculated in the case of completer sheet-die joint. Noting that the elongations of a sheet in stretching direction are equal in different cross sections, the relationship of the maximum press amount and elongation was established. The forming processes of 08AL saddle-shaped and spherical parts were simulated by displacement loading method, and the result was compared with the analytical result of the force loading. It reveals that the distributions of both the equivalent stress and equivalent plastic strain of the curvature parts obtained by the displacement loading method are more uniform, and the forming quality more stable. The saddle-shaped and spherical parts were formed by a flexible roller stretch forming device, and the experiment shows that the numerical solution to displacement loading is feasible. The required displacement of each roller corresponding to different elongations can be quickly calculated with shorter force load debugging period. The proposed method could be applied to debugging the parameters of flexible roller stretch forming process.