Manufacturing Heat Pipe by Combined Ploughing-Extrusion Process

Abstract

Since the capillary structures in the internal wall of heat pipe dominate the heat transfer performance, the research of surface heat functional structure is being gradually extended to the fields of metastructure and microstructure. This paper proposes a combined ploughing-extrusion method with a multi-tooth tool to form the micro-groove structures in the internal surface of copper pipe. Experiments indicate that the combined ploughing-extrusion process can create rougher surface than the single ploughing-extrusion process, and some phoenix-feather-like structures appear. The capillary force comparative experiment indicates that the heat pipe manufactured by the combined method can absorb 0.2ml more liquid than the one made by single process, supposing there is 90ml liquid in the container. The heat transfer testing experiment also indicates this heat pipe can transfer more heat when the inclination angle is small, but with the increase of inclination angle, this superiority becomes not so evident due to the increased reflow resistance. The combined process that comprises more than two processes makes metal yield and generates cracks in the internal wall.