| 摘要 |
PURPOSE:To manufacture continuously a pipe for heat transfer with boiling having an excellent boiling heat transfer rate, by forming a circumferential cavity opened by opening parts arranged regularly in the circumferential direction of a pipe. CONSTITUTION:Each independent projection-like fin F is formed on a blank pipe on which a lot projecting lines 4 and longitudinal grooves 2 extending in the pipe axial direction are formed alternately, by a rolling tool on which plural disks are placed. Also, in the latter half stage of the roll-working, a lot of independent projection-like fins F having a projecting tip part Fa are formed in the circumferential direction. A heat transfer finned pipe is made to pass through a die 8 and is push-elongated, and the projecting tip part Fa of each fin F is drawn extending over the whole circumference in the opposite direction to the push-elongating direction. The promecting tip part Fa of each fin F is incline-deformed and only each projecting tip part Fa placed in series in the axial direction is made to press-contact with each other. Accordingly, a circumferential cavity 10 opened by opening parts 11 arranged regularly in the circumferential direction is formed continuously on the surface of the blank pipe 3. |
