Nippon Light Metal Company, Ltd.

Honda Giken Kkk

Masayoshi Ohhashi

Keiichi Sugiyama

Kunihiro Yasunaga

Mitsuo Tsuge

Tadashi Hakamada

A method of bending extruded shapes of the present invention controls a bending radius and a bending angle in accordance with a moving distance of a movable bending die. In the bending process, hardness of an extruded shape to be processed is measured and converted into proof stress, and the bending condition for compensating the springback is determined. A correction coefficient C showing a ratio of a practical value of the moving distance and a theoretical value of the moving distance in a case of no spring-back occurring is defined by a function of Young's modulus E, geometrical coefficient Z, bending radius R and proof stress .sigma..sub.0.2 for the extruded shape to be processed. The correction coefficient C is obtained by measuring the hardness of the extruded shape to be processed, converting the measured hardness into the proof stress, and substituting the proof stress and a predetermined bending radius R into the function, and the practical value of the moving distance of the movable bending die is determined.

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Saitama, Japan

Masayoshi Ohhashi