Consider the bending process illustrated above The bending a

Consider the bending process illustrated above. The bending allowance is generally considered to equal alpha(R + 1/2T) when which one of the following is true? R

Solution

38) Bending allowence (L_b) is given by

L_b = (R + kT)

Where,

is bend angle (radian)

R is bend radius (mm)

T is thickness of the sheet (mm),

and

k = constant

Now value of k is 1/3 when R<2T and 1/2 when R>2T

In the question value of \"k\" is 0.5 so correct option is d) R>2T

39) The thicker and harder the material sheet is, it will require a larger minimum bend radius. If R/T decreases beyond a certain limit cracks start to appear on the material surface . This limit is known as minimum bend radius. So when T increases, R need to be increases too.

So the option (b) is not true as The minimum bend radius increses with increasing material thickness