Simulation Of0Cr21Ni6Mn9N Stainless Steel Tube Section Quality In NC Bending Process

Tube bending forming is an important part of tube plastic processing. Theapplication range of0Cr21Ni6Mn9N stainless steel bent tubes are more and morewidely because of it’s high strength, high pressure resistance, corrosion resistanceadvantages. Tube NC bending process is a complex physical process, and easily toproduce many defects, such as external wall thinning and cross section distortion. Wallthinning will reduce the bearing capacity of tube, cross section distortion will cause thepressure loss and flow pulsation of the conveying fluid. So, it has important theoreticalconsequences and application value to carry out the reach of0Cr21Ni6Mn9N stainlesssteel tube’s wall thinning and cross section distortion in NC bending. The main contentsand results of this research are as follows:A finite element model of φ6.35mm×0.41mm×19.05mm(tube externaldiameter×wall thickness×bending radius)0Cr21Ni6Mn9N stainless steel tube NCbending was established based on ABAQUS/Explicit platform, the key technology ofmodel was disposed, and its reliability was verified. The distribution of stress strain andthe influence laws of material parameters, geometric parameters and process parameterson wall thinning and cross section distortion in tube NC bending process were studiedusing the model. The results show that:(1) As the tube bending, the plastic deformationarea’s size and relative position remains the same, the outside tension is stronger thaninside compression of the tube;(2) The stress strain neutral layer’s ingression of theprocess with mandrel is smaller than without mandrel, outside tangential tensile stressand tensile strain of tube bending with mandrel is greater than that without mandrel,inside tangential compressed stress and compressed strain of tube bending with mandrelis less than that without mandrel;(3) According to tracking the nodes of the tube,tangential stress is largest at the bending tangent point, while tangential strain is largestat15°after passing bending tangent point;(4) The effect order of usage of mandrel fortube bending on wall thickness thinning from high to low is bulb mandrel, cylindermandrel,withot mandrel, and that on cross section distortion is just opposite;(5) Wallthinning increases with the increase of elastic modulus E, Poisson’s ratio, mandrelextension length e, clearance between benddie and tube Cb, clearance betweenpressuredie and tube Cp, and friction coefficient between mandrel and tube fmor withthe decrease of anisotropy exponent r, hardening exponent n, strength coefficient K,relative bending radius R/D, clearance between mandrel and tube Cm, and clearance between wiperdie and tube Cw; Yield stress s, bending angle α, bending speedω,pressuredie booster speed Vp, friction coefficient between benddie and tube fb, frictioncoefficient between pressuredie and tube fpand friction coefficient between wiperdieand tube fwhave no significant effect on wall thinning;(6) The cross section distortiondecreases with the decrease of r, K, s, α, Cband fmor with the increase of E, n,R/D, e and Cp; The cross section distortion decreases firstly and then hardly unchangedwith the increase of ω and Cw. The cross section distortion decreases firstly and thenincreased with the increase of Cm;, Vp, fb, fpand fwhave no significant effecton cross section deformation degree.