| 摘要 |
PROBLEM TO BE SOLVED: To provide a tube with a spiral grooved inner surface that is a thin tube and that has a great twist angle, and a manufacturing method therefor. ! SOLUTION: A tube with a spiral grooved inner surface is manufactured by forming a plurality of straight grooves along a length direction on an inner surface at a distance in a circumferential direction, and directly applying twisting to an aluminum alloy extruded stock tube with a fin formed between the straight grooves. An outside diameter φ is equal to or less than 5 mm, a twist angle of the groove is equal to or more than 20° and equal to or less than 40°, and a mean crystal grain size is equal to or less than 120 μm in a crystal grain structure. ! COPYRIGHT: (C)2014,JPO&INPIT |
