PHASE-CHANGE NON-DESTRUCTIVE PIPE EXPANDING METHOD FOR INNER FINNED PIPE

摘要

A phase-change non-destructive pipe expanding method for an inner finned pipe is disclosed. The method comprises the following steps : bending a copper heat exchange pipe (1) into U shape and removing greasy dirty and oxidized layer on the surface of the copper heat exchange pipe (1); sleeving an aluminum alloy fin group (2) on the copper heat exchange pipe (1) in series, welding all segments of the U-shaped copper heat exchange pipe (1) to obtain a loop, sealing the two ends of the loop, and vacumizing the inside of the loop and pouring a liquid working medium into the loop; and heating the copper heat exchange pipe loop to 250°C - 350°C and keeping the temperature for 10 - 30 minutes, generating a phase-change of the working medium to form an inner pressure which drives the outer diameter of the copper heat exchange pipe (1) to expand to generate plastic deformation and therefore be compactly bonded with a pipe hole (21) on an aluminum alloy fin group (2), further, the aluminum alloy fin group (2) is extruded and an elastic deformation is caused. The invention does not damage a finned groove structure of the inner wall of the copper heat exchange pipe (1), can obtain a thin wall and slim and tall gear, can effectively improve heat exchange efficiency, is particularly favorable for expansion of elongated pipes, ensures the whole process is pollution-free, green and environmental-friendly, and can be applied in the fields of building, heating, ventilation and refrigeration, microelectronic radiation and the like.