Bending procedures
Bending procedures are classified in three methods
Air bend
Coining
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 |