Effect of geometrical parameters on forming quality of high-strength TA18 titanium alloy tube in numerical control bending

Advances in Mechanical Engineering

Ouyang

et al. 2021

Self Cite

Wall thinning, as one of the key defects in tube bending determined the forming quality and limit, is more easily to occur due to the specific properties of high strength 0Cr21Ni6Mn9N stainless steel tube (0Cr21Ni6Mn9N-HS tube). To achieve tube accuracy numerical control (NC) bending forming, the wall thinning characteristics of the 0Cr21Ni6Mn9N-HS tube should be clarified. An analytical model was proposed to reveal the essential relation between tube parameters and wall thickness distribution. Considering the varied elastic modulus, a finite element (FE) model was applied to explore the wall thinning under different geometrical and process parameters. Using the modified multi-parameter sensitivity analysis method combined with FE simulation, the sensitivity of the wall thinning to geometrical and process parameters was carried out. The experiments of NC tube bending were conducted to validate the analytical and simulate results. The results show that the varied elastic modulus can enhance the wall thinning degree, but has no obvious effect on wall thinning characteristics. The wall thinning characteristics under different geometrical and process parameters are revealed and the reasonable parameters ranges for the 0Cr21Ni6Mn9N-HS tube in NC bending are obtained. The most sensitive parameter on wall thinning is the relative bending radius, while the bending angle is the least one.

Section: Wall Thinning Characteristics Under Different Geometrical Parameterssupporting

confidence: 47%

Section: Introductionmentioning

confidence: 99%

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

Advances in Mechanical Engineering

Ouyang

et al. 2021

Self Cite

“…Elastic modulus usually changes with the increase of the plastic deformation, whereas it is often deemed to be a constant during tube NC rotary draw bending simulation. [3][4][5] This assumption will make the predicted springback be less than the actual value. For the 21-6-9-HS tube, this difference is more obvious owing to its high ratio of yield strength to elastic modules.…”

Section: Introductionmentioning

confidence: 99%

Variation of elastic modulus of high strength 21-6-9 tube and its influences on forming quality in numerical control rotary draw bending

Proceedings of the Institution of Mechanical Engineers, Part C:

Ouyang

et al. 2021

Self Cite

Elastic modulus is one of the most crucial mechanical property parameters that affects the plastic forming quality of bent parts, especially for springback. Elastic modulus practically varies with plastic deformation, and its precise description is necessary to enhance simulation precision for tube bending and gain steady, high-precision bent components by actual bending. Using repeated loading-unloading tensile tests (RLUTTs), the variation of elastic modulus of high strength 21-6-9 stainless steel tube (21-6-9-HS tube) in terms of plastic strain has been obtained, which its decreases rapidly at the beginning, then decreases tardily and tends to be stable in the end with increasing the plastic strain. The variation can be expressed as a first order exponential decay function. By embedding the variation of elastic modulus with the plastic strain into ABAQUS software to simulate numerical control (NC) rotary draw bending of the 21-6-9-HS tube, the prediction precision for the springback angle, springback radius, maximum cross section distortion ratio and maximum wall thinning ratio can be improved by 11.98%, 7.62%, 35.53% and 11.55%, respectively.

“…The detailed FE modeling process can be seen in literature. 28 To assess the stability of the FE model, the energy change curves of bending stage were provided, as shown in Figure 4. It can be seen from that the ratio of kinetic energy (ALLKE) to internal energy (ALLIE) is less than 5%, which manifests that the FE model has no evident dynamic effect.…”

Section: Finite Element Modeling and Its Verificationmentioning

confidence: 99%

“…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.…”

Section: Introductionmentioning

confidence: 99%

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

Proceedings of the Institution of Mechanical Engineers, Part C:

Wang

et al. 2022

Self Cite

Owing to the unique properties of high strength Ti-3Al-2.5V tube, wall thinning is prone to happen in tube bending. To accomplish tube precision bending forming, the wall thinning needs to be precisely predicted and effectively controlled. A theoretical model considering circumferential deformation was presented to reveal the inherent relationship for wall thickness distribution versus tube geometrical parameters, and its reliability was validated by published experimental results. Using finite element (FE) simulation combined with orthogonal test, the effect rules and significances of process parameters on wall thinning in numerical control (NC) bending for high strength Ti-3Al-2.5V tube were investigated. The results show that the significant factors sort from the largest to the smallest for wall thinning in tube bending as the clearance of tube versus mandrel Cm, axial feed of mandrel e, friction of tube versus mandrel fm, clearance of tube versus bending die Cb, clearance of tube versus wiper die Cw and push assistant speed of pressure die vp; the wall thinning decreases for the larger Cm and vp, while increases for the larger Cb, Cw, fm, and e. Furthermore, the prediction model of maximum wall thinning ratio was established based on the significant process parameters by multiple linear regression method. Compared with the results of orthogonal test, the relative error of that is less than 6.5%, which can be employed for rapidly predicting the wall thinning in tube bending.