Flange forming with combined blanking and extrusion process on sheet metals by FEM and experiments
Flange forming with combined blanking and extrusion process on sheet metals by FEM and experiments
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DOI：
10.1007/s00170-009-1965-3
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发表时间：
2009-02
期刊：
影响因子：
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通讯作者：
C. Cao;Lin Hua;S. L. Liu
中科院分区：
文献类型：
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作者：
C. Cao;Lin Hua;S. L. Liu
凸缘高度和唇缘厚度通常受到常规成形操作中金属板的可成形性的限制。法兰的边缘容易发生断裂，导致其折叠，影响法兰应用的可持续性。本文采用冲裁-冷挤压复合工艺制造法兰盘零件，以获得适合后续装配的法兰盘。同时，利用有限元软件DEFORM对复合成形过程进行了数值模拟，揭示了复合成形过程的变形特征，并通过实验验证了模拟的准确性。仿真和实验结果均证明，翻边成形断裂主要发生在冲模刃口处，可以通过有限元仿真预测，并可通过以下三种方法消除或避免：（一）在冲模的圆角处将冲模修改为连接圆角和冲头的倒角，以试图减小原材料的流动阻力，并解决骨折问题。(2)应施加足够的反压力以产生静水压力，使剪切区成为压缩的（负的），这导致金属板的延展性的改善，并可以抑制断裂。(3)应安排合适的冲裁和挤压工艺组合。最后通过实验成功地制造出高质量的零件，验证了有限元模拟结果的正确性，为板材冲裁-冷挤压复合工艺的设计奠定了技术基础。
Flange height and lip thickness are generally restricted by the formability of sheet metals in the conventional forming operation. Fracture can easily occur on the edge of the flange, causing it to fold and affecting the sustainability of the application of flange. In the current work, combined blanking and cold extrusion process is applied to manufacture component with the aim to obtain the substantial flange suitable for subsequent assembly with its counterparts. Meanwhile, FEM software DEFORM is utilized to simulate this process and to reveal the deforming features of the combined process and the accuracy of the simulation is experimentally verified. Both the results of simulation and experiment prove that fracture of flange forming mainly occurs in the cutting edge of punch die, which can be predicted by FEM simulation and can be eliminated or avoided by the three following methods: (1) the punch die is modified in the rounded corner of the die as a chamfer connecting the rounded corner and the punch head in an attempt to reduce the flow resistance of the raw material and solve the fracture problem. (2) Sufficient counter-pressure should be applied to bring about the hydrostatic pressure, causing the shear zone to become compressive (negative), and this leads to improvement of ductility of the sheet metals and can restrain fracturing. (3) Suitable combination of blanking and extrusion process should be arranged. Finally, the high-quality components are successfully manufactured through experiment, which confirms that the result of FEM simulation is correct and lays a technical foundation for the design of combined blanking and cold extrusion process on sheet metals.