Die design and process optimization for aluminum flat tube profile with offset small channel

Aluminum tube with single row of small channels used in frequency conversion module of air-conditioner for heat radiation is manufactured by porthole extrusion, which has the characteristics of thin wall and large wall thickness difference. Due to the tiny dimension and offset distribution of channels, the design of process and die faces great challenges. In this study, a porthole extrusion die for aluminum flat tube with offset small channel was designed, and the offset porthole was used to balance the force on the both sides of the die core. The numerical simulation model of porthole extrusion process was established, and then, the structure of the extrusion die was optimized by taking the uniformity of metal flow velocity on the cross-section of the profile at the exit of the die. The effects of extrusion temperature, extrusion speed and die temperature on the displacement of the core, extrusion load, flow velocity and temperature of the metal at the exit of the die were studied. The optimal parameter combination of extrusion speed and temperature was obtained. The result showed that the dimensional accuracy of profile meets requirements. This study can provide guidance for the die design and process optimization of aluminum flat tube profile with offset small channel.