Frequently changing parts and small batch sizes require a universal bending technology. The most common bending technology are press brake bending and folding.
During the folding sequence the blank rests on the sheet support table. A gauging system positions the part to the bend line. The upper and lower beam clamp the blank. During the bending cycle the folding beam moves up around a pivot point. On up-down acting machines, the folding beam moves upwards or downwards, depending on the bending direction.
During the bending sequence the blank is positioned outside the machine. The operator holds and supports the weight of the blank. For bending the upper ram moves down into the lower die. Both sides of the part move up and leave the plane. A linear ram movement results in the bend angle. Sequence requires experienced operators.
Folding machines can bend all angles with a single set of tools. The machine automatically adjusts to the material thickness. Higher automated folding machines come with an automatic tool changer.
Press brake bending typically requires a large number of punches and different applications.
During the folding sequence the folding beam tool contacts the outside of the material and moves exactly to the programmed angle.
On press brakes, the punch contacts the material from above and the “V” die from below.
On a folding machine the entire part is inside the machine. Only a short flange stands out of the upper and lower beam tool.
Press brakes normally gauge the short flange. The long flange protrudes from the machine.
Folding reduces the sliding area of tools on the material surfaces to a minimum, or completely eliminates it on some machines (Multibend-Center, ProfileCenter).
Press brakes draw the material over the edges into the “V” die. The long sliding distance is shown results in scratches on the outside of the sheets.
As there are only very slight relative movements between the tool and the material surface, the tooling shows no abrasion wear even after years of use.
The long sliding distances over the “V” die edges lead to wear of the tools.
On folding machines, a radius can be easily created of short bending segments. By using small steps the outside of the radius will be very smooth and the individual steps will not be visible.
Creating a radius with bending steps on a press brake is quite difficult, as the sheet moves upwards at each step.
Folding does not require special tools for hemming.
Press brakes use special tools for hemming.