How to calculate bending force

Calculation of bending force together with main bending parameters allows for the operator to choose correctly the necessary tools as well as to justify the maximum requirements for bend according to the specification of press brake.

LEGEND:

S Sheet metal thickness                                                        α Degree of bending

V Die opening                                                                          h Minimal resting part

Ri Internal radius of bend                                                    F Bending force necessary to make the bend

TS Tensile strength of material, where:

* Mild steel 45 kg/mm

* Stainless steel 80 kg/mm

* Aluminum 45 kg/mm

Determination the V as die opening:

S (mm) ≤ 0,7 0,8 – 3,0 3,1 – 9,0 9,1 – 14,0 > 14,00 Radius bending
V S * 6 S * 8 S * 10 S * 12 S * 14 R * 2 + S * 2

Determination of Ri as internal radius of bend:

Ri = (5 x V) / 32

Determination of h as the minimal resting part:

α 30° 45° 60° 90° 120° 135° 165°
h V * 1,94 V * 1,31 V * 1 V * 0,71 V * 0,58 V * 0,55 V * 0,51

Considered tonnage and parameters for mild steel for 1 meter of bending: