| 摘要 |
PROBLEM TO BE SOLVED: To reduce generation of droop during boring in spite of providing a clearance to satisfy workability during detaching/attaching of a core die and a hollow material in a method for boring both faces of one surface and the opposing other surface of the hollow material by inserting the core die into the hollow material, and a device for boring the hollow material. SOLUTION: In the method for boring both faces of one surface 1a and the other surface 1b opposing to the one surface 1a of the hollow material 1 by inserting the core die 2 into the hollow material 1 and by moving a first punch 11 and a second punch 21 to advance in the opposite direction of the first punch 11, after one surface 1a is blanked by advancing the first punch 11 toward the core die 2, the other surface 1b is blanked by advancing the second punch 21 toward the core die 2, after that, the first punch 11 and the second punch 21 are retreated. COPYRIGHT: (C)2003,JPO
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