Pipe bending machine
Contact: Eric Hwang
Contact: Andy Wang
pipe bending machine is the same as the bending of the pipe and the bending of the sheet. In the case of pure bending, when the outer diameter is D and the wall thickness is t, the tensile stress of the lateral wall of the neutral layer is acted on by the action of external force M when the bending moment is M, and the tube wall becomes thinner. The tensile stress of the inner side wall of the neutral layer is 1, and the pipe wall becomes thicker. Moreover, the shape of the cross section is changed from circular to approximately elliptical due to the action of resultant force F1 and F2. When the deformation is too large, cracks will appear on the outer wall and wrinkles will appear in the inner wall.
The degree of deformation of bends made by tube bending machine depends on the relative bending radius R/D and relative thickness t/D value, and the smaller the R/D and t/D value, the greater the degree of deformation. To ensure the quality of tube forming, we must control the degree of deformation in the scope of license. The forming limit of pipes depends not only on the mechanical properties and bending methods of materials, but also on the requirements of pipe fittings. The forming limit of the pipe should contain the following contents:
1) in the compression deformation zone of the neutral layer, the thin-walled structure part affected by the shear stress can not exceed the instability and wrinkle.
2) the maximum elongation deformation in the tensile deformation zone of the neutral layer is not more than the plastic permissible value, and the fracture is produced.
3) if the pipe has the strength required to withstand the internal pressure, the forming limit of the wall thickness reduction is controlled.
4) if the tube has the requirement of ellipticity, the distortion of the section is controlled.