| 摘要 |
Manufacture of integral finned tube utilising a succession of plugged convergent, cold draw die stages. To produce a tube 70 (Fig. 6) with diametrically opposed integral fins 72 an initial stage die has an exit with an approximately elliptical outer periphery to form a tube with diametrically opposed thicker, or bulged walls. An intermediate stage has an exit of generally circular periphery with a pair of part circular, diametrically opposed, recesses to form a tube 44 (Fig. 4) with more pronounced bulges 45. A final stage die has an exit of generally circular periphery with a pair of diametrically opposed, straight sided recesses to form a tube 70 with bulges constituting planar faced fins 72. Between each successive stage the circumferential extent of each bulge is reduced whilst the maximum thickness is increased. |
