PURPOSE: To easily manufacture a heat transfer tube with high performance and a low pressure loss by a rolling method.
CONSTITUTION: This manufacture consists of a process using a roll 12 with grooves and a pressure roll 14 forming the first grooves, and a process using a roll 13 with grooves and a pressure roll 14 forming the second grooves. As a roll with grooves, forming the first grooves, a roll with grooves, on which a lot of grooves is formed at a certain pitch in the perpendicular direction to the roll axis, is used. As a roll with grooves, forming the second grooves, a roll with grooves, on which a lot of grooves shallower than the first grooves is formed at a certain pitch in an oblique direction (lead angle>0°) to the roll axis, is used. Since the first grooves are formed in parallel (lead angle 0°) along the tube axis direction, the meandering of a metallic bar, caused by rolling, is eliminated.
KOTO KUNIO
KONDO HISASHI
OGI EIJI
