| 摘要 |
1,078,882. Making fluid tubes; drawing; extruding. PATTERSON-KELLEY CO. Inc. Sept. 1, 1964 [Sept. 16, 1963], No. 35699/64. Headings B3A and B3P. [Also in Divisions B5 and F4] A method of making an internally finned heat exchange tube comprises extruding an outer shell 10 having radially inwardly extending fins 12 and 14, fins 14 being spaced away from the tube centre, Fig. 1, and then reducing said shell portion through dies so that the fins 14 are brought into closer relationship. Some of the fins may meet each other at the centre of the tube. The tube may be twisted before or after reducing, Figs. 7 and 8 (not shown), to give the fins a helical configuration. A tightfitting sleeve 15, Fig. 3 (not shown), may be fitted over the tube and the tube grooved as at 20, Figs. 9 and 10 (not shown), to improve the grip. |
