| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for ironing a metal tube where, even in the case a metal tube in which thickness deviation in the circumferential direction of the tube is relatively large is used as a tube stock, the roundness of the metal tube after one process ironing with one die is not reduced. SOLUTION: In the method for ironing a metal tube where a metal tube 3 is pushed through a die 1 by a punch 2 with a columnar shape inserted into the inner face side of the tube, so as to be subjected to ironing, using a die provided with two step ironing faces, the second step ironing ratio (=(gap A-gap B)/gap A×100(%)) is controlled to≥0.5%; wherein, the gap A and the gap B are spacing distances between the first and second step ironing faces respectively from the inlet side of the die and the outer circumferential face of the punch coaxially arranged with the die. COPYRIGHT: (C)2007,JPO&INPIT
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