Effect of Die Design in Microchannel Tube Extrusion

Abstract

Microchannel tube (also called Multi-port extrusion tube) with sub-millimeter-diameter ports in the cross-section is a newly developed type of aluminum extrusion with the basis for its design in micro-scale heat transfer theory. Comparing to traditional heat exchanger tube with channel diameter more than 2 mm, microchannel tube has great advantage on high heat transfer efficient, light weight, high pressure bearing capacity. The main difficulty on the tube fabrication is the extrusion porthole die design. In this work, design of the extrusion die of the microchannel tube is studied with both numerical method and experiments. Seam welding strength and microstructures of the tube formed with different designs of die are investigated. Forming experiment and hydrostatic pressure tests to the tubes formed is done for validation. And microstructure of the tube is observed using electron backscatter diffraction (EBSD) method.