Tools and products for bending and end forming tube and pipe

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Tube bending guide

Principle and parameters of bending

Simply stated, bending can be described as a technological process, which creates external bending by induced bending forces from the tool.
There is then a pulling force on the out radius of the bend which causes the wall of the tube to become thinners and a pressing force on the inner diameter which leads to it becoming wrinkled. Between these layers is a so-called Neutral layer (axis), where forces remains equal to zero.

 A permanent bend occurs, which the pulling force exceeds the yield stress of the material. At the same time however, this force must not exceed the breaking strength of the material (this is also related to the stretch of the material).

The distribution of forces and the position of the neutral layer depends on the parameters and material of the tube; and also on the machine and tools; their set up; and many other factors. The distribution of the forces has a significant impact on the part being bent. When bending a part with an open cavity, like a tube, it is much more complicated than bending a plate metal and there are many more possible defects, which are initiated by the distribution of forces around the bend.
More information on defects, how to predict them and prevent them happening read on!