In order to ensure the forming quality of pipe fittings of pipe bending machine, the deformation degree must be controlled within the allowable range. The bending forming limit of pipes depends not only on the mechanical properties and bending methods of materials, but also on the use requirements of pipe fittings.
The forming limit of pipe fittings shall include the following contents:
1. In the compression deformation zone inside the neutral layer, the thin-walled structure under the action of tangential compressive stress will not exceed the instability and wrinkle;
2. If the pipe fitting has the requirement of ovality, control its section to produce distortion;
3 if the pipe fitting has strength requirements to bear internal pressure, control the forming limit of its wall thickness thinning.
4. The maximum elongation deformation in the tensile deformation area outside the neutral layer does not exceed the allowable value of material plasticity, resulting in fracture;