COF Measurement of Tubes by Hydraulic Bulging with Radial Crushing

2011 ◽  
Vol 189-193 ◽  
pp. 2597-2600
Author(s):  
Lian Fa Yang ◽  
Cong Qiang Wu ◽  
Feng Jun Chen
Keyword(s):  
Internal Pressure ◽  
Fe Simulation ◽  
Tube Hydroforming ◽  
Measuring Method ◽  
Relative Displacement ◽  
Hydraulic Pressure ◽  
Radial Compression ◽  
Forming Process ◽  
The Coefficient Of Friction ◽  
Hydraulic Bulging

A new method of determining the coefficient of friction (COF) in expansion zone of tube hydroforming (THF) is proposed. The measuring method features that a round tube is hydro-formed into a square one by a radial compression accompanying a constant internal hydraulic pressure p, and the difference ΔL of the two diagonal lengths of the square section of deformed tube is taken as measuring index for COF. The relationships between the ΔL and the p, COF, relative displacement S/S0 of moving punches are established by the finite element (FE) simulation of the forming process. The COF can be determined by matching the indexes ΔL from experiments and simulation. The FE simulation results show that the measuring index ΔL is in exponent proportion to COF and the internal pressure p, it is extremely sensitive to the friction force or COF and conveniently measured and especially under a higher internal pressure.

Numerical Simulation of High Inner-Pressure Hydroforming of T-Branch Tube

2011 ◽  
Vol 194-196 ◽  
pp. 2193-2198
Author(s):  
Liang Chu ◽  
Jian Zhang ◽  
Da Sen Bi
Keyword(s):  
Internal Pressure ◽  
Coefficient Of Friction ◽  
Feed Rate ◽  
Tube Hydroforming ◽  
Simulation Software ◽  
Extrusion Force ◽  
Forming Process ◽  
Forming Quality ◽  
Inner Pressure ◽  
The Coefficient Of Friction

The paper studies the forming process of high inner-pressure hydroforming of T-branch tube by using DYNAFORM finite element simulation software based on its technology characteristics. First, the effects of different loading paths of key parameters(internal pressure, axial extrusion force, radial back force) on T-branch tube hydroforming process have been studied. The studies show that enough feed rate is essential to obtaining a certain branch height but excess feed rate can lead to the thickness seriously increased. The way of influence of internal pressure is contrary to radial back force, both excess internal pressure and slight radial back force can cause top branch thinned or fractured. If branch height is too low, radial back force will obstruct the extension of tube and productions cannot be compliance with design requirements. Second, the effects of coefficient of friction and radius of round angles on forming quality of T-branch tube have been discussed. The studies show that forming quality is better when the coefficient of friction is smaller or radius of round angles is larger.

scholarly journals Design of Hydraulic Bulging Die for Automobile Torsion Beam and Optimization of Forming Process Parameters

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Kefan Yang ◽  
Youmin Wang ◽  
Kexun Fu
Keyword(s):  
Friction Coefficient ◽  
Process Parameters ◽  
Orthogonal Experiment ◽  
Die Design ◽  
Molding Pressure ◽  
Hydraulic Pressure ◽  
Forming Process ◽  
Torsion Beam ◽  
Supporting Pressure ◽  
Hydraulic Bulging

The hydraulic bulging technology of tubes can provide hollow parts with special-shaped cross sections. Its manufacturing process can effectively improve material utilization and product accuracy and reduce the number and cost of molds. However, the hydraulic bulging process of parts is very complicated. The size of the tube blank, the design of the loading route, and the forming process parameters will have an effect on the molding quality. Closed tubular torsion automobile beam is considered as the research object to study hydraulic bulging die design and optimize forming process parameters. CATIA software is used to design torsion beam product structure and hydraulic bulging die. AMESim software is employed to design hydraulic synchronous control system for cylinders on both sides of the hydraulic bulging die. Mathematical control model is established and verified in Simulink software. DYNAFORM software is applied to conduct numerical simulation of hydraulic expansion. The supporting pressure, molding pressure, friction coefficient, and feeding quantity are taken as orthogonal experiment level factors. Maximum thinning and maximum thickening rates are taken as hydraulic pressure expansion evaluation indexes to complete the orthogonal experiments. Main molding process parameters are analyzed via orthogonal experiment results and optimized by employing the Taguchi method. Optimal hydraulic bulging parameters are obtained as follows: supporting pressure of 20 MPa, molding pressure of 150 MPa, feeding quantity of 25 mm, and friction coefficient of 0.075. Simulation analysis results indicate that the maximum thinning rate is equal to 9.013%, while the maximum thickening rate is equal to 16.523%. Finally, the design of hydraulic bulging die for torsion beam was completed, and its forming process parameters were optimized.

Optimization of Internal Pressure Loading Path for Tube Hydroforming of T-Shaped Tube Based on Dynaform

2014 ◽  
Vol 800-801 ◽  
pp. 703-707
Author(s):  
Shi Gang Wang ◽  
Shun Chen ◽  
Dan Wang ◽  
Wen Cai Xie
Keyword(s):  
Internal Pressure ◽  
Tube Hydroforming ◽  
Simulation Software ◽  
Loading Path ◽  
Pressure Loading ◽  
Forming Process ◽  
Forming Quality ◽  
Shaped Tube ◽  
Similarities And Differences

Take the T-shaped tube as the research object, studied the principles and theory. The paper researched the influence of single liner internal pressure loading path and bilinear internal pressure loading path and the gradient of internal pressure loading path on the forming quality of T-shaped tube with the help of FEA and DYNAFORAM simulation software. The paper researched the each method of forming process, and the relation between wall thickness thinning/thickening and the loading path of internal pressure, compared the similarities and differences. The results show that the gradient of internal pressure loading path is the best way, and the internal pressure should be increased growth rate in the pre-formed, so that get a small thickness reduction part.

Friction tests in tube hydroforming

2005 ◽  
Vol 219 (8) ◽  
pp. 587-593 ◽  
Author(s):  
Yeong-Maw Hwang ◽  
Li-Shan Huang
Keyword(s):  
Internal Pressure ◽  
Coefficient Of Friction ◽  
Tube Hydroforming ◽  
Test Method ◽  
Experimental Results ◽  
Friction Test ◽  
Friction Forces ◽  
Axial Feeding ◽  
The Coefficient Of Friction ◽  
Friction Test Method

The objective of this paper is to propose a friction test method to evaluate the performance of different kinds of lubricants and determine their coefficients of friction in tube hydroforming processes. A self-designed apparatus is used to conduct the experiments of friction tests. The coefficient of friction between the tube and the die at the guiding zone is determined. The effects of the internal pressure and the axial feeding velocity on the friction forces and coefficients of friction for various lubricants are discussed. From the experimental results, it is known that MoS2 corresponding to a coefficient of friction of 0.018 is the best lubricant among the evaluated lubricants during tube hydroforming processes.

Forming Margin Diagram for Tube Hydroforming with Radial Crushing under Linear Loading Path

2012 ◽  
Vol 538-541 ◽  
pp. 1106-1110 ◽  
Author(s):  
Zhi Hua Tao ◽  
Lian Fa Yang
Keyword(s):  
Fe Simulation ◽  
Tube Hydroforming ◽  
Loading Path ◽  
Fe Model ◽  
Forming Process ◽  
Loading Paths ◽  
Contour Lines ◽  
Working Status ◽  
Simulation Results ◽  
Linear Loading

Tube hydroforming with radial crushing (THFRC) process is one of tube hydroforming methods that is suitable for overlong structure parts forming process avoiding wrinkling and bursting failure. In this paper, the Forming Margin Diagram (FMD) for THFRC process was presented to optimize loading paths. Initially, parameters of Finite Element (FE) simulation in this study were represented, which contained FE model and linear loading paths. Afterwards, boundaries of the FMD were delimited based on real working status. Moreover, curves of corner radius, bursting failure and thickness uniform rate were determined by FE simulation results to establish the FMD, and the curves and zones on the FMD were analyzed simultaneously. Furthermore, features of contour lines were discussed, and the usage of the FMD was introduced.

scholarly journals Deformation Characteristics and Microstructure Analysis of Aluminum Alloy Component with Complex Shape by Cold Orbital Forming

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 808
Author(s):  
Wei Feng ◽  
Chaoyi Jin ◽  
Jiadong Deng ◽  
Wuhao Zhuang
Keyword(s):  
Aluminum Alloy ◽  
Complex Shape ◽  
Fe Simulation ◽  
Effective Strain ◽  
Electron Back Scatter Diffraction ◽  
Main Body ◽  
Deformation Characteristics ◽  
Alloy Component ◽  
Forming Process ◽  
Orbital Forming

This work aimed to study the deformation characteristics and microstructure of AA6063 aluminum alloy component with complex shape manufactured by cold orbital forming processing. The material flowing behavior was analyzed by Finite Element (FE) simulation and forming experiments were carried out using bar blank with different lengths. The microstructure of the boss zone cut from the formed samples was observed using scanning electron microscopy (SEM) and electron back-scatter diffraction (EBSD). FE simulation and experiment results both showed the aluminum base can be formed using cold orbital forming process. The distributions of the effective strain of the component with different blank lengths were almost the same, and the effective strain was bigger at the boss and the flash as the forming finished. The material flow is complex, especially in the boss, and the folding defect was observed at the root of the boss. The distribution of Mg2Si strengthening precipitate is more homogeneous in the matrix, has a different shape, and shows directivity at different position of boss zone. The grains are elongated, and the extent is different at different positions of the boss zone after cold orbital forming, and the crystal orientation discrepancy is smaller in the component main body and bigger in the boss zone. Subsequent forming process and blank optimization need to be further researched to improve forming quality.

Experimental Researches upon Changes of a Pipe's Roughness after Hydroformation

2013 ◽  
Vol 371 ◽  
pp. 111-115
Author(s):  
Bogdan Constantin Vaceanu ◽  
Gheorghe Nagit ◽  
Vasile Huian
Keyword(s):  
Surface Roughness ◽  
Tube Hydroforming ◽  
Work Piece ◽  
Copper Pipe ◽  
Work Area ◽  
The Coefficient Of Friction ◽  
Hydroforming Process ◽  
Aluminum Pipe ◽  
Experimental Researches

Surface roughness was studied in the tube hydroforming process, considering the quality of the material and the coefficient of friction between the work piece and die. Other researchers have studied the surface roughness to the front of an aluminum pipe [. The aim of this work was to analyze changes in a copper pipe roughness occurred after hydroforming process with fluid. Effects of changing roughness were studied, following the deformation of the material in the work area and roughness changes occurring in the material flow. After achieving hydroforming process, the surface roughness was measured by electron microscopy SEM in different areas of the hydro formed tube. After hydroforming process, an increase of surface roughness in connection areas of the mold to the curvature and the transverse direction of the pipe.

scholarly journals Methods of determination of frictional resistances in sheet metal forming of car body sheets

2018 ◽  
Vol 19 (6) ◽  
pp. 756-760
Author(s):  
Tomasz Trzepieciński ◽  
Irena Nowotyńska
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Complex Function ◽  
Forming Process ◽  
The Coefficient Of Friction ◽  
Displacement Speed ◽  
Almost All ◽  
Lubrication Conditions

The friction phenomenon existed in almost all plastic working processes, in particular sheet metal forming, is a complex function of the material's properties, parameters of the forming process, surface topography of the sheet and tools, and lubrication conditions. During the stamping of the drawpieces there are zones differentiated in terms of stress and strain state, displacement speed and friction conditions. This article describes the methods for determining the value of the coefficient of friction in selected areas of sheet metal and presents the drawbacks and limitations of these methods.

Plastic Instability of Thin Shells Deformed by Rigid Punches and by Hydraulic Pressure

1973 ◽  
Vol 95 (1) ◽  
pp. 36-40 ◽  
Author(s):  
Bilgin Kaftanog˘lu
Keyword(s):  
Large Deformations ◽  
Initial Conditions ◽  
Plastic Anisotropy ◽  
Plastic Instability ◽  
Strain History ◽  
Thin Shells ◽  
Hydraulic Pressure ◽  
Varying Thickness ◽  
New Criterion ◽  
Hydraulic Bulging

A theory has been developed to provide a solution for axisymmetrical shells in the plastic range for large deformations up to fracture. It includes the effects of strain history, nonlinear strain-hardening characteristics of materials, plastic anisotropy in the thickness direction, prestrain, through-thickness stress, and boundary tractions. It is also possible to use nonuniform initial conditions such as varying thickness and varying prestrain. A numerical solution has been developed especially suitable for stretch forming by a rigid punch and for hydraulic bulging of shells or diaphragms. It can easily be modified for the deep-drawing problem. Different instability criteria have been studied. It was found that the conventional criteria would not yield satisfactory results. A new criterion called the “strain propagation” criterion gave satisfactory results in the prediction of the onset of fracture. It could expalin the fracture taking place at increasing or decreasing pressures in the hydraulic bulging problem.

Advanced In-Process Control System for Sheet Stamping and Tube Hydroforming Processes

2014 ◽  
Vol 622-623 ◽  
pp. 3-14 ◽  
Author(s):  
Kenichi Manabe
Keyword(s):  
Process Control ◽  
Metal Forming ◽  
Tube Hydroforming ◽  
Essential Element ◽  
Forming Limit ◽  
Forming Process ◽  
Intelligent Technique ◽  
Sheet Stamping ◽  
Adaptive Process Control ◽  
Metal Forming Process

A sophisticated servo press with the digital control has been developed and attracted attention in recent years. By utilizing its high function in-process, servo presses have a potential to enhance the forming limit and to improve quality and accuracy of product not only in sheet stamping but also in tube hydroforming processes. On the other hand, in-process control and adaptive process control technologies in metal forming processes using intelligent technique and soft computing have been investigated and developed previously. Nowadays we are in a good environment to realize further advanced adaptive in-process control in metal forming process. To further advance this technology, sensing system is essential element and it should be applied to feedback control optimally in their forming operation. This paper describes the current situation on advanced intelligent process control technology for sheet stamping and tube hydroforming processes on the basis of the research results by the author.

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