Numerically controlled bending performance of medium strength TA18 titanium alloy tubes under different die sets

Abstract

The rapid development of aviation and aerospace technologies has led to increased interest in the application of numerically controlled (NC) technology for bending light-weight titanium alloy tubes. In order to study and develop advanced NC bending technology, it is necessary to understand the bending performance of medium strength TA18 (Ti-3Al-2.5V, ASTM Gr. 9) titanium alloy tubes during NC bending under different die sets. This paper focuses on the bending performance of medium strength TA18 tubes under different NC bending die sets, including the variations in the stress, strain, wall thickness, cross sectional deformation, and defects. The results show that adding a wiper die to the base die set decreases the radial, hoop, and tangential compressive stress and the tangential compressive strain, and adding a mandrel to the base die set also decreases these stresses, but increases the radial and hoop tensile stress and decreases the hoop compressive strain obviously, and brings about a three-dimensional tensile stress concentration where the mandrel provides support. For the NC bending of medium strength TA18 tubes, the flattening of cross section is more sensitive index than the thinning of wall thickness. Introducing a mandrel can improve the flattening of cross section obviously but it has a little worse effect on the thinning of wall thickness, and adding a wiper die to the base die set can inhibit the occurrence of the inside bulge but worsen the flattening of the cross section remarkably. Considering the above effects of the mandrel and wiper die on bending performance, it is reasonable to apply the die set comprising a bending die, clamp die, and pressure die for tubes with a small diameter and the die set including an appropriate mandrel additionally for tubes with a larger diameter, in order to bend the medium strength TA18 tubes with high quality and at low cost.bending performance, medium strength titanium alloy tube, numerically controlled bending, die set Citation:Zhan M, Jiang Z Q, Yang H, et al. Numerically controlled bending performance of medium strength TA18 titanium alloy tubes under different die sets.

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

“…Jeong et al 15 numerically investigated the effects of bending radius on wall thickness variation and ovality of Inconel 625 fine tube with the size of 1.5 mm 3 0.12 mm (outer diameter 3 wall thickness) during bending process. 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.…”

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“…For the Ti-3Al-2.5V tube bending, Zhan et al 25,26 addressed the variation in wall thickness and cross-section under all kinds of process parameters, mandrel parameters and die sets of the medium strength Ti-3Al-2.5V tubes during NC bending by FE analysis, proposed a method for fast determination mandrel extension length range, obtained the optimal process parameters and die sets for the medium strength Ti-3Al-2.5V tubes in NC bending. Fang et al 27,28 numerically explored the influence laws of boosting velocity and geometric parameters such as bending angle, relative bending radius, and tube sizes on wall thinning, wall thickening, and cross-section distortion of the high strength Ti-3Al-2.5V tube during NC bending.…”

Investigation on the Mechanical Properties and Formability of Ti3Al2.5V Tubes Deformed at Elevated Temperatures

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