Technological Characteristics Of Pipe Bender

The bending of pipe by pipe bender is the same as that of sheet metal. In the case of pure bending, when the pipe with outer diameter D and wall thickness t bends under the action of external force moment M, the pipe wall outside the neutral layer bears tensile stress σ 1, the pipe wall becomes thinner; Compression stress of pipe wall inside neutral layer σ 1. The pipe wall becomes thicker. Moreover, the shape of the cross section changes from circular to nearly elliptical due to the combined force F1 and F2. When the deformation is too large, the outer pipe wall will produce cracks and the inner pipe wall will wrinkle.
The deformation degree of pipes depends on the value of relative bending radius R/D and relative thickness t/D. The smaller the value of R/D and t/D, the greater the deformation degree. In order to ensure the forming quality of pipe fittings, the deformation degree must be controlled within the allowable range. The bending forming limit of pipe fittings 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) The maximum elongation deformation in the tensile deformation zone outside the neutral layer does not exceed the plastic allowable value of the material, resulting in cracking;
2) In the compression deformation zone of the inner side of the neutral layer, the thin-walled structure under the action of tangential compressive stress will not wrinkle beyond the buckling;
3) If the pipe fittings have ovality requirements, control the distortion of its section;
4) If the pipe fittings have strength requirements to withstand internal pressure, the forming limit of wall thickness reduction shall be controlled.