Influence of 1st Step Shape on Formability of Circular Truncated Cone Stretch Forming in Two-Step Forming

抄録

The formability of steel sheets must be improved in order to form complicated car parts. Multistep forming is one way to improve formability. Although the shape after preforming can influence formability in the main step of multistep forming, no relationship has been reported between the shape after preforming and the final shape in stretch forming.

In this study, circular truncated cones were formed by a two-step forming process consisting of preforming and main forming with combinations of various shapes after preforming and final shapes in order to investigate the effect of the shape after preforming on the forming limit in main forming. The results confirmed that the forming limit height in main forming is affected by the preforming shape. It was also found that the forming limit height in main forming is determined by the central cross-sectional line length of the shape after preforming.

 

This Paper was Originally Published in Japanese in J. JSTP 61 (2020) 87–92. Abstract was slightly modified.

Fig. 13 Relationship between central cross-sectional line length after preforming and main forming (D_M ≧ D_P).