Spring back due to bending is due to a Elastic recovery is c

Spring back due to bending is due to:

a) Elastic recovery, is corrected by under bending.

b) Elastic recovery, is corrected by over bending.

c) Plastic recovery, is corrected by over bending.

d) Plastic recovery, is corrected by under bending.

Solution

Answer : b

The spring back for each deformation pattern is estimated by the residual differential strains between outer and inner surfaces after elastic recovery. Each of the six deformation patterns has a valid region of applicability.

Spring-back may be corrected by overbending, by bottoming or setting. Bottoming or setting is accomplished by striking the metal severely at the area containing the radius so as to obtain localized flow. Bottoming is sometimes accomplished by placing a bead on the apex of the punch so as to concentrate the plastic deformation at the bead.