Research On The Technological Theory Of Radial-axial Large Ring Rolling

Radial-axial large ring rolling is an advanced plastic forming technique which to reduce the thickness and height, enlarge the diameter and form the profile of the ring by ring rolling machine. It has been used to manufacture large seamless rings applied in many industry fields, such as heavy machine, energy equipment, aeronautics and astronautics etc, due to its technical superiorities such as high efficiency, good quality, energy and material saving. Radial-axial large ring rolling also is a complicated forming process with multi-factors coupling interactive effects. At present, the relative researches of radial-axial large ring rolling are few, which results in that there are lack of theoretic guidelines in the actual radial-axial large ring rolling production, and seriously restricts the further development and application of this technique.Based on the theory of radial ring rolling, the mechanical and kinematic conditions of radial-axial large ring rolling were researched in this paper. The stable mechanical conditions and calculation methods of force and power parameters for radial-axial large ring rolling were proposed. And the reasonable ranges of feed speeds of mandrel and upper axial roll, follow rolling speeds of axial rolls, and rotational speeds of main roll and axial rolls were determined. The research results provided valuable guidelines for selection of the rolling parameters in the actual radial-axial large ring rolling production.Through the experiment of hot compression, the true stress-strain curves of 42CrMo steel at different temperatures and strain rates were obtained, and the constitutive model for elevated temperature flow behavior of 42CrMo steel was established. Then a 3D coupled thermo-mechanical FE model of radial-axial large ring rolling was explored using the dynamic explicit code ABAQUS/Explicit, and its reliability was verified. Using FE simulation and analysis, the distribution and evolution laws of the strain, temperature, spread and force and power parameter of radial-axial large ring rolling were investigated in particular. The study provided a base for further understanding and investigation on the deformation mechanism of radial-axial large ring rolling.Using theoretical analysis, the design methods of blank size, rolls sizes, and rolls movements were established. Based on the valid 3D FE model, the effect laws of rolling parameters including blank size, rolls sizes, rolls movements, and other parameters on radial-axial large ring rolling were systematically studied. The study results provided useful guidelines for the design and optimization of the rolling parameters in the actual radial-axial large ring rolling production.