Question

A 1 mm thick sheet of metal is bent to a radius of 12 mm. After springback, it is observed that the radius is 13 mm. If this sheet is to be bent to achieve a bend angle of 90o after springback, to what angle should it be bent before springback

Answer 1

To solve this problem it is necessary to apply the concepts related to Arc Length.

From practical terms we know that the Angle can be calculated based on the arc length and the radius of the circle, in other words

$\theta = \frac{S}{r}$ or

$S = \theta r$

Where,

S = Length of the arc

r = Radius

From the information given, the object to bending has a millimeter thick and a radius of 12 mm. This way your net radio is given by

$R_1 = r_B+\frac{t}{2}$

After Springback the radius increases and the thickness ratio is therefore maintained.

$R_2 = r_S+\frac{t}{2}$

For both cases we have different angles but that maintains the electron-magnetic proportions, therefore the arc length is maintained:

$S_B = S_S$

$\theta_B R_1 = \theta_S R_2$

$\theta_B (r_B+\frac{t}{2})=\theta_S(r_S+\frac{t}{2})$

Re-arrange to find $\theta_S$

$\theta_S = \frac{\theta_B (r_B+\frac{t}{2})}{(r_S+\frac{t}{2})}$

$\theta_S= \frac{90\°*(12+\frac{1}{2})}{13+\frac{1}{2}}$

$\theta_S= 83.33\°$

Therefore the angle that should be bent before springback is 83.33°