When a piece has to be bent that already has edges bent perpendicular to the bending line, to avoid collisions and to enable the piece to be produced, punches must be used which have a length such that they can function inside the sheet metal piece.
When deciding on the punch length it is best to get as close as possible to the edge of the sheet to prevent the sheet from swelling, in the corner to be created.
It is also important to evaluate whether these sides at right angles to the bend will collide with the press brake upper beam.
Therefore, a product designer has to calculate the maximum height of these sides that can be obtained with the equipment available.
This height is dependent on the punch height and on the shape of the press brake upper beam.
The maximum fold height can be obtained by trial and error, but in order to make an assessment prior to carrying out a test we recommend the use of some simple formulae.
For example:
H = tool working height （punch height – tang） + intermediate height （if one is mouned）
W = distance from the bending axis tothe back of the upper beam.
If a box collides with the front of the upper beam, for machines with a Promecam tang W=7 mm,if with the rear, distance W should be measured （see drawing）.
For other standards, measure the indicated dimensions.
Maximum box height = （H – W） × 0.7
On the other hand, to find H:
H = （box height/0.7） + W
