| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of cold-rolling a metal tube, which is excellent in the dimensional shape (out-of-roundness) and a planar property of the inner surface of the tube after the final finishing by pilger rolling and can guarantee S/N ratio at internal eddy current flaw detection. SOLUTION: In the cold-rolling method by using a pair of roll dies which are composed of a caliber constituted of a caliber diameter Dx and the amount Fx of side relief and by pilger rolling provided with a mandrel, in this cold-rolling method of the metal tube, the final finish rolling is performed by taking a side relief rate SR which is expressed by the formula (1) of the roll die as within the range of 0.5-1.5%, the taperθ1 of a working part of the mandrel as≤0.25°, the taperθ2 of the finishing part of the mandrel as≤0.1°, further, the feed rate F (per pass) of a material to be worked as 1.0-2.5 mm and satisfying a formula (2) in the relationship with the side relief ratio SR. SR(%)=ä(2×Fx)/(2×Fx+Dx)}×100 ... (1), F≤3.0-SR ... (2). COPYRIGHT: (C)2007,JPO&INPIT
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