scholarly journals Development and Modelling of the Method of Mandrelless Small-Radius Tube Bending / Opracowanie I Modelowanie Sposobu Beztrzpieniowego Gięcia Rur Na Małych Promieniach

2015 ◽  
Vol 60 (4) ◽  
pp. 2797-2804 ◽  
Author(s):  
J. Michalczyk ◽  
K. Wojsyk
Keyword(s):  
Numerical Modelling ◽  
Cross Section ◽  
Small Radius ◽  
Outer Diameter ◽  
Actual Process ◽  
Tube Bending ◽  
Tube Cross Section ◽  
Wall Thinning ◽  
Bending Process ◽  
Bending Radius

The paper reports the results of research aimed at creating theoretical grounds for a new method of mandrelless small-radius tube bending (1.5Dr<Rg<2.5Dr, where Dr- tube diameter, Rg- bending radius). As the result of applying such a methodology it is possible to carry out the bending process (with an angle of up to 180°) and obtain an ovalization and wall thinning in the bending area, which are much smaller than those in currently manufactured products. The currently used bending methods and bending equipment are able to achieve a minimum bending radius not less than three times the tube outer diameter. The research hypothesis has assumed the existence of tube bending methods that are more efficient that those known so far. Than methods do not rely on circular bending contours, but instead they may use other shaping die contours which has not been explored yet. Circular benders used in practice fail in that they do not yield the expected results on small radii and do not control the material flow (do not ensure its correct behaviour) in the bending zone. The literature review has shown that there are currently no theoretical studies, numerical analyses and experimental verifications related to the processes of mandrelless tube bending on small radii, i.e. for 1.5D≤R≥2.5D, where: (R - bending radius, D - tube outer diameter) up to an angle of 180°. Due to the lack of studies on this subject, in their approach to the numerical modelling of the problem, the authors of the paper were guided by their own experience in this field and made every effort to make the numerical model reflect the actual process as accurately as possible. They were only aided by the general knowledge accumulated in the literature on numerical modelling. To sum up, the purpose of the publication is to demonstrate that the change in the die recess towards a shape resembling an ellipse results in a change in the characteristics of metal flow (movement) along the tube perimeter and in a change in the stress characteristics and, as a consequence, a change in the tube cross-section in the bending zone. The research discussed in this paper seeks to establish the correct flow of material in the tube cross-section in the bending zone by determining the most efficient bender recess shape and friction surface forming, which will eliminate the excessive ovalization and upper wall thinning. The expected effect of implementing this bending technology will be increasing the flow capacity in energy systems, which will directly translate into a reduction of atmospheric CO emissions due to the lower energy consumption. In addition, the paper has presented the concepts of tools intended for the experimental verification of tube bending process.

Theoretical, Numerical and Experimental Investigation of the Effects of Manufacturing Process Parameters on Thin-Walled Tube Bending Defects

2009 ◽  
Vol 83-86 ◽  
pp. 1107-1112
Author(s):  
J. Taheri Kahnamouei ◽  
Mohammad Sedighi
Keyword(s):  
Cross Section ◽  
Wall Thickness ◽  
Thickness Ratio ◽  
Outer Diameter ◽  
Tube Bending ◽  
Effective Parameters ◽  
Bending Process ◽  
Thin Walled Tube ◽  
Bending Radius ◽  
Thin Walled

The aim of this paper is to survey thin-walled tube bending process (without use of mandrel and booster). In tube bending process there are several effective parameters such as wall thickness, outer diameter-to-wall thickness ratio, and centerline bending radius-to-outer diameter ratio. Any mismatch in selecting these parameters would cause defects like wrinkling, variation in wall thickness, and cross section distortion. Firstly, the effects of these parameters on the initiation of the wrinkle, depth of wrinkling, change in wall thickness, and cross section distortion are studied. For this purpose, an FE commercial code has been used to simulate the process. Then, a series of experimental tests have been carried out to verify the results simulation. A comparison between analytical and experimental results shows a reasonable agreement with each other. Based on this comparison, it has been observed that there is a critical bending radius for any tube with a certain radius and thickness, in which the wrinkling begins to occur. For a certain bending angle and radius, it have been observed that the depth of wrinkling, change in wall thickness, and cross section distortion increase with reduction in wall thickness and outer diameter-to-wall thickness ratio

Significance Analysis of Processing Parameters on Wall Thinning in Tube Bending

2012 ◽  
Vol 622-623 ◽  
pp. 437-441
Author(s):  
Heng Li ◽  
Kai Peng Shi ◽  
He Yang ◽  
Yu Li Tian
Keyword(s):  
Coupling Effect ◽  
Processing Parameters ◽  
Al Alloy ◽  
Outer Diameter ◽  
Tube Bending ◽  
Significance Analysis ◽  
Wall Thinning ◽  
Complex Process ◽  
Bending Radius ◽  
Extension Length

Tube bending is a complex process with multi-factor coupling effect and multiple defects occurring. The wall thinning, as one of the important defects in tube bending, determines the bending quality. In this study, taking thin-walled 6061-T4 Al-alloy tube with Φ50.8×t0.889×R101.6mm (outer diameter D × wall thickness t × bending radius R) as the objective, the significance of processing parameters on the wall thinning degree is studied using the orthogonal test under ABAQUS/Explicit platform. The results show that: 1) the bending radius, the clearance between the tube and the pressure die, the friction between the tube and the pressure die, the clearance between the tube and the pressure die, the clearance between the tube and the mandrel and the friction between the tube and the mandrel affect the wall thinning significantly, while the coefficient of boost velocity, the number of mandrel balls, the friction between the tube and the wiper die, the mandrel extension length and the friction between the tube and the bending die have little effect on the wall thinning degree.

Numerical and experimental study on rotary draw bending of aluminium alloy tubes

2011 ◽  
Vol 2 (1) ◽  
pp. 33-38 ◽  
Author(s):  
L. Lăzărescu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Aluminium Alloy ◽  
Cross Section ◽  
Angular Position ◽  
Element Model ◽  
Quality Parameters ◽  
Wall Thinning ◽  
Bending Process ◽  
Bending Radius

Abstract In this paper a 3D finite element model of the bending process for circular aluminium alloy tube has been built using the explicit code eta/Dynaform and validated by comparing the experiments. The experiments were carried out by using a hand bender with the same bending principle as a rotary draw numerical controlled (NC) bender. The relationship between quality parameters of bent tubes, in terms of cross-section distortion and wall thinning, and the angular position along the bent tube is discussed experimentally in combination with FE simulation. Then, the effects of bending radius (R) are investigated using simulation of the bending process based on the finite element model. The results show that with the increase of bending radius, the cross-section degradation factor (Ψ) and wall thinning degree (ξ) decreases rapidly.

Modeling and Experimental Validation of the Effect of Sand Filling on Avoiding Wrinkling Phenomenon in Thin-Walled Tube Bending Process

2010 ◽  
Author(s):  
Jalal Taheri Kahnamouei ◽  
Bashir Behjat
Keyword(s):  
Wall Thickness ◽  
Experimental Tests ◽  
Element Model ◽  
Thickness Ratio ◽  
Outer Diameter ◽  
Tube Bending ◽  
Effective Parameters ◽  
Bending Process ◽  
Bending Radius ◽  
Thin Walled

This paper investigates a method to avoid the wrinkling in thin-walled tubes in bending process. In the tube bending process there are several effective parameters such as wall thickness, outer diameter-to-wall thickness ratio, centerline bending radius-to-outer diameter ratio. Any mismatch in the selection of the process parameters would cause defects like wrinkling, serve changes in wall thickness, and cross section distortion. For example, the depth of wrinkling increases with reduction in wall thickness and outer diameter-to-wall thickness ratio for a certain bending angle and radius. In this research, to avoid wrinkle initiation, tube is filled by sand and then bended. This sandy core is supported the tube from inner, and tube is prepared to bending. After bending process, sand is removed. In this work, to study the process numerically, a 3D finite element model of the horizontal bending process is built using ANSYS software. Then, experimental tests have been carried out to verify the simulation results and are developed to provide additional insight. A comparison between numerical and experimental results shows a reasonable agreement. It shows that wrinkle initiation can be avoided with filler material like sand.

Study of NC Cold Tube Bending Spring-Back Characteristics

2010 ◽  
Vol 154-155 ◽  
pp. 202-208 ◽  
Author(s):  
Yi Nan Lai ◽  
Sheng Le Ren ◽  
Zeng Lou Li ◽  
Jun Tao Gu ◽  
Guang Fei Wu
Keyword(s):  
High Reliability ◽  
Prediction Equation ◽  
Strong Nonlinearity ◽  
Spring Back ◽  
Tube Bending ◽  
Bending Angle ◽  
Bending Process ◽  
Elasto Plasticity ◽  
Bending Radius ◽  
Back Angle

The unloading spring-back of tubes during its manufacturing process shows a strong nonlinearity, which greatly influences the precision of parts. In this paper, the strain distribution of bending tubes was analyzed based on the elasto-plasticity theory, and the theoretical equation for spring-back of tubes was derived. The numerical simulation model for cold tube-bending process was developed with prediction error of 9% compared with experimental results, indicating high reliability of the model. The 12Cr1MoV and 20G tubes were used to analyze the effects of bending angle, bending radius and bending speed on the spring-back of tubes. The prediction equation of spring-back was built, which shows that the spring-back tendency was in accordance with theoretical analysis results. The simulated results show that the spring-back angle is linearly proportional to the bending angle within a certain range. In addition, it is proportional to the relative bending radius and the bending speed.

scholarly journals Selecting Parameters for Bending of Tubes Made of the X70 Steel by Numerical Modelling

2017 ◽  
Vol 62 (4) ◽  
pp. 2339-2342
Author(s):  
G. Junak ◽  
M. Cieśla ◽  
J. Tomczak
Keyword(s):  
Numerical Modelling ◽  
Induction Heating ◽  
Process Parameters ◽  
Numerical Analyses ◽  
Geometric Features ◽  
Tube Bending ◽  
Gas Distribution ◽  
Probability Of Occurrence ◽  
Bending Process ◽  
Pipe Lines

AbstractThis paper addresses numerical analyses of the bending process for tubes made of the X70 steel used in gas distribution pipe-lines. The calculations performed under the research involved simulation of processes of tube bending with local induction heating. The purpose of these calculations was to establish process parameters making it possible to develop pipe bends of geometric features conforming with requirements of the applicable standards. While performing the calculations, an analysis was conducted to determine the probability of occurrence of folding and fractures according to the Cockcroft-Latham criterion.

Wrinkling Limit in Tube Bending

2000 ◽  
Vol 123 (4) ◽  
pp. 430-435 ◽  
Author(s):  
Xi Wang ◽  
Jian Cao
Keyword(s):  
Material Properties ◽  
Deformation Theory ◽  
Energy Approach ◽  
Tube Bending ◽  
Predictive Tool ◽  
Bending Process ◽  
Thin Walled Tube ◽  
Bending Radius ◽  
Thin Walled ◽  
Doubly Curved

Thin-walled tube bending has found many of its applications in the automobile and aerospace industries. This paper presents an energy approach to provide the minimum bending radius, which does not yield wrinkling in the bending process, as a function of tube and tooling geometry and material properties. A doubly-curved sheet model is established following the deformation theory. This approach provides a predictive tool in designing/optimizing the tooling parameters in tube bending.

Controlling Wrinkling and Flatness during the Processing of the Bend Section of a Pipe by Applying Vibration to the Mandrel

2015 ◽  
Vol 656-657 ◽  
pp. 600-603 ◽  
Author(s):  
Xia Zhu ◽  
Narumi Wada ◽  
Keiji Ogi ◽  
Hiroshi Kurosu ◽  
Manabu Takahashi ◽  
...  
Keyword(s):  
Nonlinear Finite Element ◽  
Outer Diameter ◽  
Bend Section ◽  
Finite Element Software ◽  
Bending Process ◽  
Bending Radius ◽  
Metal Pipes ◽  
Thin Walled ◽  
Pipe Processing ◽  
Distribution Of Stresses

Metal pipes have a long history as fluid conduits, and are commonly joined with components such as elbows to form bent transport paths. However, with the increasing demands for economy and energy saving, pipes with reduced joints and thinner walls are desired. The number of joints can be reduced by a drawing and bending process that forms a bend section at any position in the pipe. However, this approach incurs problems such as wrinkling and flattening, especially under conditions of large bending angle, decreased bending radius, and thin pipe walls. In this research, applying vibrations to the mandrel was trialed as an approach for controlling the wrinkle depth and flattening. First, processing experiments were performed on thin walled pipes (wall thickness = 0.5 mm; outer diameter = 14 mm). The change of flattening and the number and depths of wrinkles were investigated in the presence and absence of vibrations. Next, simulations were performed using the commercial nonlinear finite element software. Through these simulations, the flatness and appearance of wrinkles were analyzed by modeling the behavior and distribution of stresses and strains in the processing process. The application of vibration to the mandrel appears to be a promising approach for controlling the wrinkling and flattening problems during pipe processing.

Wrinkling Limit in Tube Bending

2000 ◽  
Author(s):  
Xi Wang ◽  
Jian Cao
Keyword(s):  
Material Properties ◽  
Deformation Theory ◽  
Energy Approach ◽  
Tube Bending ◽  
Predictive Tool ◽  
Bending Process ◽  
Thin Walled Tube ◽  
Bending Radius ◽  
Thin Walled ◽  
Doubly Curved

Abstract Thin-walled tube bending has found many of its applications in the automobile and aerospace industries. This paper presents an energy approach to provide the minimum bending radius, which does not yield wrinkling in the bending process, as a function of tube and tooling geometry and material properties. A doubly-curved sheet model is established following the deformation theory. This approach provides a predictive tool in designing/optimizing the tooling parameters in the tube bending.

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