When you press form a door panel, or any other shape, the steel is deformed to the required shape through a mixture of elastic and plastic deformation. On removal of the load, i.e. the press forming punch, the steel will springback due to the recovery of some of the elastic strain. The design of the forming tool and die has to accommodate this springback in order to generate the desired shape.
The extent of the springback is very difficult to calculate as it depends on:
- the strength of the steel;
- the strip thickness;
- the bend angle;
- die radius;
- the gap between the die and punch;
- the lubrication conditions.
Therefore when increasing the strength of the steel and reducing the thickness of the strip to achieve a lighter door panel, it is also necessary to modify the punch and die geometry and increase the forming angle from those used for a lower strength and thicker steel strip.
See how much the springback in a simple bending operation varies with steel strength, thickness and bend angle.
Simulation
Definition of Springback
Exercise
References
- Dieter, GE, Mechanical Metallurgy, McGraw Hill, 0071004068
