Forming characteristics of tube free-bending with small bending radii based on a new spherical connection

Guo, Xunzhong; Xiong, Hao; Li, Heng; Xu, Yan; Ma, Ziqi; El-Aty, Ali Abd; Yan, Ma; Jin, Kai

doi:10.1016/j.ijmachtools.2018.05.005

Cited by 47 publications

(12 citation statements)

References 19 publications

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“…This value for the coefficient of friction was considered according to the pre-lubrication, and the material of tubes and bearing raceway. This value for the friction coefficient was used in a similar situation in Guo et al 11 The tube and the bearing shell movements were according to the movement pattern shown in Figure 3. According to Figure 3, in the asynchronous mechanism, the bearing is first moved as specified and the tube displacement is then applied.…”

Section: Methodsmentioning

confidence: 99%

“…The use of a third connection allows for greater control over the movement of the die. 11 In bending with the free connection, the movement mechanism is simple but with less controllability. In this paper, due to the low cost and simplicity, this kind of connection was used.…”

Section: Introductionmentioning

confidence: 99%

“…They presented relationships that predict the bending radius value based on the adjustment parameters of the machine. Guo et al 11 showed that the conventional bending die design has some drawbacks because of unstable motion. They suggested a plan based on a spherical connection in which the bending die would be more controllable.…”

Section: Introductionmentioning

confidence: 99%

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The effects of loading path on process parameters in the free tube forming process

Mosavi

Mazdak

Sheykholeslami

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part B:

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The free bending method is the simplest method among the tube bending processes without the use of a die. Despite the simplicity of the process, there is no proper control over the geometrical tolerance of the product. The loading path or in other words the bearing movement mechanism is one of the effective factors on product geometry. In this paper, a finite element simulation has been carried out to investigate two different bearing movement time-paths (synchronous and asynchronous mechanisms); then, the results have been verified with experimental tests. The thickness distribution in different directions, ovality, bending radius, and applied forces on the bearing and the tube for both bearing movement mechanisms are the main results of this paper. The amplitude of thickness change in both mechanisms was equal. But there is a uniform trend in variation of thickness distribution in synchronous mechanisms. So, better geometrical quality of products is expected in this mechanism. On the other hand, because of uniform force distribution with tube movement in the bearing and tube, the stability of the asynchronous mechanism is higher than the synchronous mechanism.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The effects of loading path on process parameters in the free tube forming process

Mosavi

Mazdak

Sheykholeslami

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part B:

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show abstract

“…Other than for sheet metals, pure bending devices have been developed and used for various materials, such as for composite materials by Ben Zineb et al [2], weldments by Bu & Gardner [11], flexible electronics by Hoefnagels et al [12], micro electro-mechanical systems (MEMS) by Elhebeary & Saif [13], micro thin sheet by Stölken & Evans [14] and metal tubes by Guo et al [15]. Alternative testing methods such as shear tests [16][17][18] and bulge tests [19][20][21] can also be used to obtain stress-strain data at high strains.…”

Section: Introductionmentioning

confidence: 99%

A New in-Plane Bending Test to Determine Flow Curves for Materials with Low Uniform Elongation

et al. 2020

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Background Flow curves can easily be obtained by uniaxial tensile tests, but strains are then limited by diffuse necking. For many applications, the flow stress must be known above this limit. Objective The main objective of this paper is to obtain flow curves for material with low uniform elongation to relatively high strains compared to a uniaxial tensile test. Method A novel in-plane sheet bending experiment and stress evaluation procedure is presented. The developed bending device can be mounted in a tensile test machine and can produce very high bending curvatures compared to previously proposed pure bending setups. The bending angle and curvature are obtained by image processing and the bending moment is calculated directly from the force measured from the tensile test machine and the bending angle. The moment–curvature relation is used to determine the uniaxial stress–strain relation using an analytical approach, without presuming any hardening model. The bending process and the analytical procedure are validated by a numerical simulation as well as by experiments. Results The numerical validation shows good agreement between the stress–strain curve obtained from the bending process and that of the uniaxial input flow curve up to 12% strain. Experimentally the model is validated by comparing the stress–strain curve obtained from the bending test with the results directly obtained from a tensile test for mild steel. Good agreement is observed up to 12% strain. As an application example, bending tests were performed on a martensitic steel (MS) with low uniform strain (less than 3%). For this material, flow curves could be obtained up to relatively high strains (~12%), compared to a tensile test. Conclusion This bending test setup allows to study materials with low uniform elongation up to significantly higher strains than are readily obtained in a tensile test.

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“…In current literatures, there contains several flexible push bending processes, such as freebending (Guo et al, 2018a(Guo et al, , 2018b(Guo et al, , 2018c and the three-roll-push-bending. For three-roll-pushbending process, Plettke (Plettke et al, 2010;Plettke and Vipavc, 2011;Plettke et al, 2012;Plettke and Vatter, 2014) established a FEM model and numerically investigated the relation of bending radii and the positions of setting roll.…”

mentioning

confidence: 99%

A new strategy for describing the characteristics of bending line in flexible push bending

Zhang

Shang

et al. 2019

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Purpose When manufacturing an arc-shaped tube product using push bending process, the transition zone and outfeed zone will inevitably occur. Transition zone and outfeed zone are caused by the kinematical motion of mobile tools. The existence of transition zone and outfeed zone will lead to a big deviation between the forming product and desired shape. To improve the forming quality of arc-shaped products in push bending, the transition zone and outfeed zone are investigated in this paper. Design/methodology/approach A piecewise function is used to describe the bending characteristics along bending line, in which a series of vibration parameters are extracted and considered as control values. Findings The new strategy is helpful for finding the relationship between tools motion and curvature distribution and improving the bending lines design procedure in flexible push bending. Originality/value The new strategy is helpful for finding the relationship between tools motion and curvature distribution and improving the bending lines design procedure in flexible push bending.

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Forming characteristics of tube free-bending with small bending radii based on a new spherical connection

Cited by 47 publications

References 19 publications

The effects of loading path on process parameters in the free tube forming process

The effects of loading path on process parameters in the free tube forming process

A New in-Plane Bending Test to Determine Flow Curves for Materials with Low Uniform Elongation

A new strategy for describing the characteristics of bending line in flexible push bending

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