Extrusion of hollow profiles with tailored wall thicknesses

铝中空型材在汽车和航空工业中经常用于轻量化应用。由于荷载在型材长度上的分布不是恒定的，因此需要根据最大荷载来设计壁厚。为了避免尺寸过大，只在高应力区域增加壁厚是可取的。型材的其他部分可以设计成较小的壁厚。在所要求的项目中，型材横截面将通过在分流模中使用轴向移动的心轴来改变。这导致了复杂的物质流动。所要求的项目旨在研究这种复合体的影响，以及对于不同的壁厚，不同的材料流动对型材的微观结构和力学性能的影响。为此，在设计和制造所需工具后，将使用不同的温度和速度进行挤压实验。材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有限元模拟的预测进行比较来研究。最后，将根据显微组织和机械性能来表征重要的型材截面。

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.