Design of a novel dummy block by finite element simulation to eliminate back end defects in direct extrusion

作者：Liu Cheng Hsien; Yang Jin Bin; Lin Hsin Chih^*

来源：Transactions of the Indian Institute of Metals, 2016, 69(9): 1699-1710.

DOI：10.1007/s12666-016-0830-y

• Direct extrusion
• Back-end defect
• Dummy block
• Funnel defect
• Internal oxide ring
• Inverse segregation

Back-end defect can degrade the production yield and cause a significant quality problem in direct extrusion of the aluminum alloys. This study is concerned with two types of back-end defects, i.e., the funnel defect and the internal oxide ring, which are usually found in the extrudates of aluminum alloys. Hot top and beveled edge dummy blocks are designed to prevent these defects. Due to the high costs of the experimental studies, the effect of two designed dummy blocks on the flow pattern of a deformed billet of aluminum alloys is analyzed by finite element method (FEM) Deform 3D package software. Using simulation, a hot top dummy block with a concave-center is designed to eliminate the formation of the funnel defect. A hot top capacity C is defined at the fixed depth of the concave: C = 1 is a suitable criterion for the design of the hot top dummy block. A beveled edge dummy block is designed to affect and to impede the back flow of the surface layer of the billet into extrudates of aluminum alloys.

• 出版日期2016-11