Bending procedures are classified in three methods
Punch edge penetrates into the work and this prevents thework from spring-back.Very good accuracy is gained but 5 - 8 time bigger tonnageis required than bottoming.
Die V-width selection
V-opening is determined by the work thickness:t as well as bending tonnage, product's inner radius(iR) and minimum flange length.
Although V-width selection by thickness: t is shown in the table below, two vital factors must bechecked whether iR is acceptable or not and min. flange length by V value is acceptable or notbecause once V-width is selected iR becomes approx. iR=V/6 and min.flange length is fixed by V-value.
|Thickness (t)||0.5 - 2.6 mm||3.0 - 8 mm||9 - 10 mm||12 mm <|
|Bottoming||6 x t||8 x t||10 x t||12 x t|
|Partial bending||12 - 15 x t||12 - 15 x t||12 - 15 x t||12 - 15 x t|
|Coining||5 x t||5 x t||5 x t||5 x t|