The bending is a processing of plastic deformation that allows to obtain open section elements, developed essentially in the length direction. It consists in subjecting the sheet to a bending stress with a load higher than the elastic limit, to deform it permanently.
The equipment used is a mold consisting of a punch and a matrix of appropriate shape, depending on the type of bending to be made. The punch is driven by a press which provides the bending force necessary to perform the machining.
The material has an elastic return for which the bending angles of the mold must provide an increase to the bending angles of the piece.
There are minimal bending radii below which it isn’t possible to go without breaking or cracking the sheet. (see image 2)
There are two types of bending:
- Free: that’s without the use of a specific mold, but only by placing the sheet on supports and deforming a punch;
- In mold: when the shape isn’t trivial and requires a real mold consisting of a die and a punch.
Below there are tables of various types of punches with their dimensions:
IMAGE 1- Tools for bending machines
IMAGE 2- Minimum fold edge
IMAGE 3- Tool dimensions bending machines