OCTOBER 19-20, 2012 - YMCA University of Science & Technology

Proceedings of the National Conference on
Trends and Advances in Mechanical Engineering,
YMCA University of Science & Technology, Faridabad, Haryana, Oct 19-20, 2012
Figure 1 (b) cracks and sidewall wrinkling in a deep drawn part
Figure 1(c) Wrinkles formation on the side wall of the component
1.1. Deep drawing parts
There are the components which are manufactured with the help of deep drawn dies. As shown in the figures-
Figure 2 Car engine part Figure 3 Deep drawn cup Figure 4 Deep drawn sheet
1.2. Wrinkles on deep drawing parts
Material thinning and cracks may arise when local load in the blank increased the level of uniform elongation. In
contrast, sidewall wrinkling occurred when tangential compressive stresses led to buckling in the sidewall area.
In deep-drawing, wrinkling and cracks have to be avoided by control of material flow. Blank holder force, draw
or lock beads, type and amount of lubricant as well as shape and size of initial blank represent possibilities to
influence material flow. Wrinkling is usually undesired in final sheet metal parts for functional and aesthetic
reasons. It is unacceptable in the outer skin panels where the final part appearance is crucial. Wrinkling on the
mating surfaces can adversely affect the part assembly and part functions, such as, sealing and welding. In
addition, severe wrinkles may damage or even destroy dies. Therefore, the prediction and prevention of
wrinkling are extremely important in sheet metal forming parts. One of the variable blank holder forces known
from literature has been published by Sheng and is illustrated in figure 5. The depicted blank holder force profile
has been utilized for optimization of deep- drawing a conical cup. Optimization of variable blank holder force
distributions was a deciding factor too.
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