| 摘要 |
PROBLEM TO BE SOLVED: To easily form a flange free from nose cracking by burring. SOLUTION: (A) A planar member 3 is subjected to drawing, and simultaneously, rugged parts 5 are simultaneously integrally formed to the part 4 as the object for burring. (B) Next, the recessed parts 5 are pierced to the object 4 for burring. At this time, in view of the difference between the flange circumferential length in a root part 8 and the standard prepared hole circumferential length of a prepared hole 6, i.e., the quantity of the prepared hole to be stretched, the rugged quantity in the rugged parts 5 is set. (C) Then, the part 4 as the object for burring is subjected to burring with a punch 7 to form a flange 1. In this way, even in the case the circumferential length ratio at the time when rugged parts are not provided around the prepared hole exceeds 1.12, the substantial circumferential length ratio can be controlled to≤1.12, thus the flange 1 free from nose cracking can be formed. COPYRIGHT: (C)2006,JPO&NCIPI
|
