V-Bending

V-die bending, process — Fig. 1
Process & force progression during V-die bending & die stamping
① Free bending ② End of free bending ③ Die stamping F_{St max} Maximum force Free bending F_{St max UT} Maximum force Die stamping

① At the beginning the strip bends elastically. In this phase the bending line corresponds to a cubic parabola.

② As soon as the bending stress on the edge fibers exceeds the elastic limit, flow occurs in these areas. The permanent deformations begin in the middle of the strip length, where the bending moment is greatest, and continue towards the contact points on the die. After the legs are in contact with the die, free bending ends.

③ Until the form fit is complete, the strip must on the one hand be curved around the stamp rounding, and on the other hand the legs of the angle piece that have experienced unintentional bending must be straightened again using a straightening bending process. This is also known as counter-embossing or post-forming.569

The maximum forces and the forming work are of particular interest for the process design and the selection of the press. Various computational approaches are presented below:

Maximum bending force F_{St max} according to Oehler

Maximum bending force F_{St max} according to Zünkler

Maximum bending force F_{St max} according to Kluge

Maximum embossing force F_{St max UT} according to Zünkler

Siegert, K. / Blechumformung / Springer Vieweg / Berlin / 2015 / …

Zünkler, B. / Rechnerische WErfassung der Vorgänge beim Biegen im V-förmigen Gesenk / TH Stuttgart / Stuttgart / 1966 / …