| 摘要 |
1,045,618. Producing composite finned tubes. CALUMET & HECLA Inc. Aug. 21, 1964 [Sept. 30, 1963], No. 34423/64. Heading B3A. [Also in Division F4] A method of making a composite tubular device comprises extruding a liner tube 12 having a finned inner surface, assembling over the liner tube a shroud tube 16 having smooth inner and outer surfaces and a smaller yield strength than that of the liner tube and drawing the assembly through a die to stress the liner tube. The liner tube 12 may be of copper or copper alloy and the shroud tube 16 of aluminium or an alloy thereof. After extrusion, the aluminium tube 12 is age-hardened to increase its yield strength. |
