| 摘要 |
1430690 Making finned tubing UOP Inc 13 July 1973 [14 July 1972] 33511/73 Heading B3A [Also in Division F4] A method of producing a finned heat exchanger tube 10 comprises (a) forming by rolling, integral annular or helical fin convolutions from the material of a plain tube 10, said fins having a plurality of circumferentially spaced zones of reduced fin height and (b) bending the outer portions of all of the fins uniformly so that each convolution has its tip spaced at a small spacing from the side of the adjacent convolution to define therewith partially enclosed spaces 27 entending around the tube. As shown the spaced zones of reduced fin height are in the form of recesses or notches 18 formed either by rolling with a knurling tool longitudinally of the tube or by a cutting or grinding operation: bending of the fins is effected by drawing the finned tube through a suitably dimensioned die. In an alternative embodiment (Figs. 8-11, not shown) the finned tube is formed by advancing a plain tube over a mandrel having one or more helically extending grooves therein, the rolling operation being carried out by a plurality of sets of finning discs. The rolling operation deforms the tube material inwardly into the mandrel grooves thereby producing internal helical ribs in the tube, the fin portions overlying the ribs being of reduced fin height. |
