There are 2 types of bending:
- Air bending
- Bottom bending
LVD electric press brake
In what cases should you choose air bending?
In air bending, the end of the punch and the 2 edges of the V allow the sheet metal to be bent. But this type of bending means there is a spring back effect of the work piece. As the bending force is weaker, the metal sheet springs backwards like an elastic when the punch is removed.
You must therefore adjust the bending angle according to the metal spring back and calculate the margin. As such, for a 90° bend, the punch must go down to 85° for example.
Other elements should be taken into account when calculating this margin, such as the thickness of the punch blade, the length of the fold and the opening of the V.
This type of bending is most commonly used for sheet metal working as it is suitable for machines with reduced capacities, unlike bottom bending, which requires more force.
In what cases should you choose bottom bending?
In bottom bending, the punch curves the metal sheet with a high force (3 to 5 times greater than air bending) which reduces or even prevents the spring back effect generally associated with air bending. The process begins with air bending then continues with cold forging carried out at the bottom of the V.
This method provides a high level of angular precision.
It is suitable for sheet metal over 2 mm thick.