飞机的框、肋骨架零件,除采用滚弯成形外,多数都采用拉弯成形的方法。型材拉弯成形的方法有多种,这里介绍我们在生产实践中采用的淬火二次拉弯成形方法,简称二次拉弯。无产阶级文化大革命前,由于受苏修旧的工艺方法的束缚,长期沿用M料一次拉弯成形的方法。这种方法的工艺过程是:M料预拉伸—弯曲—补拉—手工校形—淬火—手工校形。少数零件也采用淬火一次拉弯的方法。这 Aircraft frame, rib frame parts, in addition to using roll forming, the majority of the use of bending forming method. Bending forming a wide range of methods, here introduced in our production practice quenching secondary bending forming method, referred to as secondary bending. Before the Great Proletarian Cultural Revolution, due to the shackles of the old Soviet methods of repair, long-term use of M material forming a pull-bending method. The process of this method is: M expected pre-stretch material - bending - Bulai - hand shape - quenching - hand-shaped. A few parts also quenched a method of bending. This