Deformation behaviors of 21-6-9 stainless steel tube numerical control bending under different friction conditions

Abstract

For contact dominated numerical control (NC) bending process of tube, the effect of friction on bending deformation behaviors should be focused on to achieve precision bending forming. A three dimensional (3D) elastic-plastic finite element (FE) model of NC bending process was established under ABAQUS/Explicit platform, and its reliability was validated by the experiment. Then, numerical study on bending deformation behaviors under different frictions between tube and various dies was explored from multiple aspects such as wrinkling, wall thickness change and cross section deformation. The results show that the large friction of wiper die−tube reduces the wrinkling wave ratio η and cross section deformation degree ΔD and increases the wall thinning degree Δt. The large friction of mandrel−tube causes large η, Δt and ΔD, and the onset of wrinkling near clamp die. The large friction of pressure die−tube reduces Δt and ΔD, and the friction on this interface has little effect on η. The large friction of bending die−tube reduces η and ΔD, and the friction on this interface has little effect on Δt. The reasonable friction coefficients on wiper die−tube, mandrel−tube, pressure die−tube and bending die−tube of 21-6-9 (0Cr21Ni6Mn9N) stainless steel tube in NC bending are 0.05−0.15, 0.05−0.15, 0.25−0.35 and 0.25−0.35, respectively. The results can provide a guideline for applying the friction conditions to establish the robust bending environment for stable and precise bending deformation of tube bending.

Wall thinning behaviors of high strength 0Cr21Ni6Mn9N tube in numerical control bending considering variation of elastic modulus

“…Where m is the distance from the measure position to geometrical neutral layer, which can be determined by equation (19).…”

“…The effects of different push assistant loading conditions on wall thinning, cross section distortion, and wrinkling behaviors of thin-walled aluminum alloy and stainless steel tube during NC bending were studied based on ABAQUS code by Li et al 16 Using FE analysis, Zhan et al 17 researched the wall thinning and cross section distortion of medium strength TA18 tube in NC bending under different die sets. Recently, for the 0Cr21Ni6Mn9N-HS tube bending, Fang et al 18 established a three dimensional (3D) elastic plastic FE model of the 0Cr21Ni6Mn9N-HS tube in NC bending and explored the influences of friction conditions 19 and mandrel parameters 20 on wall thinning and cross section distortion.…”

Wall thinning characteristics and prediction in numerical control bending of high strength Ti-3Al-2.5V tube

“…A three-dimension (3D) elastoplastic FE model of the whole process for high strength 0Cr21Ni6Mn9N stainless steel tube during NC bending was established under the platform of ABAQUS, and its dependability was verified in literature. 13 Then, using the model, the influences of friction conditions, 14 clearance of tube versus dies, 15 and mandrel parameters 16 on wall thinning and cross-section deformation were investigated, and the sound friction coefficients, clearance, and mandrel parameters were obtained for tube bending. Li et al 17 numerically researched the effects of push assistant loading conditions on wall thinning, cross-section distortion and wrinkling of thin-walled aluminum alloy and stainless steel tube NC bending.…”

Effect of clearance on wrinkling of 21-6-9 high-strength stainless steel tubes in numerical control rotary draw bending process

“…By theory and numerical simulation, Han et al [3] researched the influence of bending radius, the clearance between mandrel and tube, the position of mandrel and whether the wiper die exists or not on the wrinkling of tube bending using numerical simulation and experimental methods. Fang et al [4,5] numerically investigated the effect of geometrical parameters and friction between tube and die on wrinkling instability of the HSST in NC bending. Chen et al [6] explored the effect of processing parameters on wrinkling of thin-walled circular tube under bending process.…”