Springback law of high-strength 21-6-9 stainless steel tube in numerical control bending under different process parameters

Abstract

In order to achieve the precision bending deformation, the effects of process parameters on springback behaviors should be clarified preliminarily. Taking the 21-6-9 high-strength stainless steel tube of 15.88 mm × 0.84 mm (outer diameter × wall thickness) as the objective, the multi-parameter sensitivity analysis and three-dimensional finite element numerical simulation are conducted to address the effects of process parameters on the springback behaviors in 21-6-9 high-strength stainless steel tube numerical control bending. The results show that (1) springback increases with the increasing of the clearance between tube and mandrel Cm, the friction coefficient between tube and mandrel fm, the friction coefficient between tube and bending die fb, or with the decreasing of the mandrel extension length e, while the springback first increases and then remains unchanged with the increasing of the clearance between tube and bending die Cb. (2) The sensitivity of springback radius to process parameters is larger than that of springback angle. And the sensitivity of springback to process parameters from high to low are e, Cb, Cm, fb and fm. (3) The variation rules of the cross section deformation after springback with different Cm, Cb, fm, fb and e are similar to that before springback. But under same process parameters, the relative difference of the most measurement section is more than 20% and some even more than 70% before and after springback, and a platform deforming characteristics of the cross section deformation is shown after springback.

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

“…On the foundation of study on the effects of geometrical and process parameters on wall thinning degree of the 0Cr21Ni6Mn9N-HS tube during NC bending, using the modified multi-parameter sensitivity analysis model, as shown in equation (29), 27 the sensitivity values S k ( a k ) of different parameters including the ψ , R/D , C m , C p , f m , f p , and e on the maximum wall thinning degree Δ t max are calculated as shown in Table 4. The S k ( a k ) ( k = 1, 2, …, v ) are a set of dimensionless non-negative real number, and the greater the S k ( a k ) is, the more sensitive the wall thinning degree to this parameter is.…”

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

“…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.…”

Influence of local features on twist springback of high-strength steel long channels

“…However, it has been found in the application of high-strength steel sheets that the phenomenon of springback occurs after forming, and the law is difficult to grasp. [1][2][3][4] With the continuous development and maturity of finite element simulation technology, more and more scholars today were using finite element analysis to study the deformation process of sheets. 5,6 Finite element simulation also plays an important role in the study of part springback.…”

“…However, it has been found in the application of high-strength steel sheets that the phenomenon of springback occurs after forming, and the law is difficult to grasp. 1–4…”