Fig 1.
Schematic diagram of the calibration process.
Fig 2.
Schematic diagram of roller-shape.
Section Ⅰ: Loading section; Section Ⅱ: Ovality calibration section; Section Ⅲ: Ovality and straightness calibration section; Section Ⅳ: Ovality complement calibration section; Section Ⅴ: Unloading section.
Fig 3.
Diagram of loading parameters.
Fig 4.
Deformation path of particle along axial direction.
Fig 5.
Deformation path of particle along circumferential direction.
Fig 6.
Flow chart for formulating the calibration scheme.
Fig 7.
Finite element model.
Table 1.
Mechanical properties and geometric dimensions of pipes.
Table 2.
Geometric dimension of rollers.
Fig 8.
Experimental device for pipe calibration.
1. Screw 2. Lead screw drive 3. Servo motor 4. Support assembly 5. Push plate 6. Control cabinet 7. Pipe 8. Upper roller 9. Frame 10. Lower roller 11. Slider 12. Pedestal.
Fig 9.
Distribution of equivalent stress along the one-third pipe.
Fig 10.
Distribution of radial stress along the thickness direction.
a) Positive bending region; b) Reserve bending region.
Fig 11.
Distribution of axial stress along the thickness direction.
a) Positive bending region; b) Reserve bending region.
Fig 12.
Distribution of shear stress along the thickness direction.
a) Positive bending region; b) Reserve bending region.
Fig 13.
Distribution of equivalent strain in the ovality calibration section.
Fig 14.
Distribution of residual stress of 304 pipe after calibration.
Fig 15.
Effect of the ratio of Vr to Vf on residual ovality and residual straightness.
Fig 16.
Effect of radial reduction on residual ovality and residual straightness of pipes.
a) Residual ovality; b) Residual straightness; the times of reciprocating bending ψ is 50.
Fig 17.
Effect of the times of reciprocating bending on residual ovality and residual straightness of pipes.
a) Residual ovality; b) Residual straightness; t = 2.0mm.
Fig 18.
Forming effect of 304 stainless steel pipes.