Page 166 - Module DMV20173

EXERCISE 4.3

Identify the factors that influence the deep-drawing force, F, in Figure 4, and explain
why they do.

Figure 4: Deep drawing

Solution:
The blank diameter because the larger the diameter, the greater the circumference,
and therefore the greater the volume of material to be deformed. The clearance, c,

between the punch and die directly affects the force because at smaller clearances,
ironing begins to take place, thus increasing the force. Blank thickness also
increases the area of the volume deformed. The blank holder force and friction affect

the punch force because they restrict the flow of the material into the die.

EXERCISE 4.4

Please explain why the drawability of a material is higher in the hydroform process
than in the deep-drawing process?

Solution:
The hydroform process the inner surface of the cup being formed is pressed against
the cylindrical surface of the punch by the pressure in the forming chamber. This
situation allows the cup to move with the punch, whereby the tensile stresses (that
could eventually lead to cup tearing) are reduced due to the friction between the cup

and the punch.