Bent-forming method

摘要

In a first forming step, a metal sheet (P) placed on, and held by a provisional horizontal flat forming portion (11) of a first forming die part (17) is bent along a provisional bend forming portion (12) of the first forming die part (17) to execute bent-forming such that two arch parts of the metal sheet, having respective protuberances oriented in directions opposite from each other, with protuberance surfaces being butted against a provisional inclined flat forming portion (13A) of a second forming die part (18), and a provisional inclined flat forming portion (13) of the first forming die part (17), respectively, are coupled with each other, thereby obtaining a provisional formed member (7) comprising a provisional inclined flat portion (3A) without any warpage, formed continuously from a provisional horizontal flat portion (1A) via a provisional bend (2A), and a flange portion (5) formed continuously from the provisional inclined flat portion (3A) so as to form a target angle ( ¸ d). Subsequently, in a second forming step, the provisional formed member (7) is formed into a target shape by causing the provisional bend to undergo deformation by bending back while bent-forming the provisional horizontal flat portion (1A).