Extrusion of hollow profiles with tailored wall thicknesses

铝中空型材通常用于汽车和航空工业的轻量化应用。由于载荷分布在型材长度上不是恒定的，因此需要根据最大载荷来设计壁厚。为了避免尺寸过大，最好只增加高应力区域的壁厚。型材的其他部分可以设计成更小的壁厚。在要求的项目中，将通过在舷窗模具中使用轴向移动的心轴来改变剖面截面。这导致了一个复杂的物质流动。所要求的项目旨在研究这种复合物的影响，以及不同壁厚、不同材料流动对型材的微观结构和机械性能的影响。为此，在设计和制造所需的工具后，将在不同的温度和速度下进行挤压实验。物料流动对尺寸精度的影响将通过测量挤压型材的尺寸并与fem模拟的预测结果进行比较来研究。最后，根据微观组织和力学性能对重要型材进行表征。

Aluminum hollow profiles are often used for lightweight applications in automotive and aviation industries. Since the load distribution is not constant over the profile length the wall thickness needs to be designed according to the maximum load. In order to avoid oversizing it is desirable to increase the wall thickness in high stressed areas only. Other parts of the profile can be designed with smaller wall thickness. In the requested project the profile cross section will be varied by using an axially moving mandrel in a porthole die. This leads to a complex material flow. The requested project aims at the investigation of the influence of this complex and for the varied wall thicknesses different material flow on microstructure and mechanical properties of the profiles. For that purpose after designing and constructing the needed tools, extrusion experiments will be conducted using different temperatures and velocities. The effect of the material flow on size accuracy will be studied by measuring the dimensions of the extruded profiles and comparison with predictions from FEM-simulations. Finally, significant profile sections will be characterized according to microstructure and mechanical properties.