PURPOSE: To provide a process for producing a small-diameter heat transfer tube with grooves on the inside surface capable of suppressing the manufacturing cost, preventing the fracture or fall of the peak parts of the inside surface of the tube caused at the time of pneumatic drawing and improving the productivity.
CONSTITUTION: The tube with the grooves on the inside surface of an outside diameter 1 specified to 5 to 8mm, groove depth 3 to 0.1 to 0.2m, the helix angle of the grooves with the tube axis to 5 to 25°, the peak angle 5 at the section perpendicular to the tube axis to 50 to 80° and groove pitch 8 to 0.29 to 0.8mm is first formed. The outside diameter of this tube with the grooves on the inside surface is then subjected to pneumatic drawing to 3 to 5mm, by which the small-diameter tube with grooves on the inside surface is produced.
ISHIBASHI AKIHIKO
UCHIDA TETSUO
