Question: Explain the steps in designing bending dies.
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Subject : Production Process 2

Difficulty : Medium

renu • 168 views
 modified 6 weeks ago by Ankit Pandey ★ 60 written 3 months ago by RB • 100
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Fig. bending terminology.

• Bending is the process in which a straight length is transformed into a curved length.

• During bending, the outer surface of the material is under tension and inner under compression.

• Parameters to be considered while designing bending die.

• It is the radius of curvature on inside surface on the bend.

• If the bend radius is very small, then outer surface of material cracks due to higher tension.

• To prevent the damage the bend radius should not be less than 0.8 mm.

b) Bend allowance (B) :

• The length of the bend area which is more than blank length before bending is known as bend allowance.

• Bend allowance is calculated using

B = $\alpha$ ( r + k)

Where, B = Bend allowance

$\alpha$ = Bend angle in radius

K = Distance of neutral axis from inside surface of the bend.

c) Bending pressure or bending force (f)

• Bending force depends on the stock thickness, bend length, die opening width and type of bend.

• For r = bending

F =$\frac{ k.l. 6_ut . t^2}{w}$

Where,

l = length of bend

6ut = ultimate tensile strength

T = Blank thickness

K = Dia opening factor ( 1.2 to 1.33 )

W = width of die opening

W = $R_1$ + $R_2$ + C

Where, c = t = clearance

$R_1$ = punch edge radius.

$R_2$ = die edge radius.