Potential blank reduction

Drawn part metal areas of the drawn part — Fig. 1
Sheet metal areas on the drawn part
① Blank ② Drawn part ③ Blank for penetrating ④ Penetrated drawn part A_b Floor area A_f Flange area A_z Frame area d₀ Initial diameter d_p Blank diameter during penetration d₁ Drawn part diameter h Drawn part height s₀ Initial sheet thickness s_p Wall thickness at the bottom after penetration

A deep-drawn part consists of the base of the drawn part, the frame and possibly a flange. The volume of the starting sheet metal, the blank, is distributed over these three surface areas due to the constant volume after forming.

A redistribution of the material from the base of the drawn part to the frame allows the size of the insert plate to be reduced while the height of the drawn part remains the same. This leads to a considerable saving of material.

Eqn. 1

Eqn. 2

Eqn. 3

Eqn. 4

Difference sheet area	ΔA_p	=	8.3	%
Difference floor area	ΔA_b	=	33.3	%
Draw ratio	β₀	=	2
Floor space	A_b	=	25	%

Blank diameter	d₀	=	200	mm
Diameter punch	d₁	=	100	mm
Elongation thickness	ε_s	=	25	%

200

Calc 1

Saving potential board area

Ex. I For a drawn part with an initial drawing ratio β₀ of 2, the floor area is 25%. If penetration thins the floor area by 25%, it will increase by 40%. As a result, the size of the insert board can be reduced by 8.3%.

Ex. II In the case of a drawn part with an initial drawing ratio β₀ of 1.41, the floor area is 50%. If penetration thins the floor area by 15%, it increases it by 17.6%. As a result, the size of the insert board can be reduced by 8.9%.

The maximum elongation ε_{s max} that can be achieved depends on the material. Common values are:

St14 ε_{s max} = 57%
X5CrNi189 ε_{s max} = 45.3%
AlMg3 W19 ε_{s max} = 17.4%
BHZ 220 ε_{s max} = 29.8%
BHZ 300 ε_{s max} = 25.9%
CHRX 35εs_max = 32.4%
CHLY 40εs_max = 29.4%
PHZ 26 ε_{s max} = 27.6%
ZStE 260 ε_{s max} = 28.7%
ZStE 340 ε_{s max} = 24.9%
ZStE 420 ε_{s max} = 22.3%
Al99.5 W7 ε_{s max} = 32.4%
Al99.5 G9 ε_{s max} = 26.9%
Al99.5 G13 ε_{s max} = 11.8%
AlMg5Mn ε_{s max} = 16.2%
AlMg3 G27 ε_{s max} = 8.5%

Relative floor area — Fig. 2
Area percentage _Ab of the bottom of the drawn part in % in relation
to the total area of the board as a function of the draw ratio β₀

A round deep-drawn part with a diameter d₁ of 100 mm and a blank diameter d₀ of 200 mm has a draw ratio β₀ of 2. In this case, the percentage of the area originally contained in the plate that is now stored in the base of the drawn part is 25 %. However, if the draw ratio β₀ is 1.41, then 50% of the surface area originally contained in the plate is in the bottom of the drawn part.