Abstract: The objective of aluminum alloy profile extrusion process and die design is to ensure the profile quality and die strength. But for large and long cantilever aluminum alloy profiles, the conventional flat die and diversion die design usually cause the damage or failure of die in the cantilever area. Even through increasing the thickness of die in these areas, it is still difficult to ensure the die strength or life-time. With a large cantilever aluminum alloy profile as an example, the fake porthole die design method and cantilever decomposition technique are studied. The material flow velocity, temperature, particle track and the die strength of the two different die design methods are studied and compared. Especially, the die strength and stress distribution are researched. The results indicate that the fake porthole die design method is a useful die design method for large and long cantilever aluminum alloy profiles. It can decrease the die stress significantly and ensure the die strength. The sound material flow and profile quality are also obtained by optimizing the fake porthole die structure. The design rules for fake porthole die structure and the material flow based die shape optimization method are given.

Key words: Die strength, Fake porthole die, Product quality