文摘
Aluminum microextrusion is an efficient technology to fabricate profiles with micro/meso features at low cost. However, die failure is often observed during the process of high extrusion ratio due to excessive stress concentration, which is caused by irrational design. This study aims at extruding a certain aluminum alloy profile with the symmetrical micro/meso features of twin wing and double hole based on microbulging extrusion process. 3D FE simulations illustrated that the bulging angle had a major impact on velocity and temperature distribution of the extrudate, as well as internal stress distribution and elastic deformation of the dies. A series of detachable mandrels with various bulging angles were designed and fabricated. By experiments and simulations, velocity distribution was obtained, which indicated that the bulging angle was beneficial to the balance of metal flow. An appropriate bulging angle could achieve better material flow uniformity with a lower standard deviation of velocity (SDV), which contributed significantly to the success of extrusion. However, an overlarge bulging angle would increase the deformation of mandrel core and raise the temperature of extrudate, which led to the local defects in final products.
