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Overall review of the tube hydroforming (THF) technology
Abstract
Tube hydroforming is used to describe the metal forming process whereby tubes are formed into complex shapes with a die cavity using internal pressure which is usually obtained by various means such as hydraulic, viscous medium, elastomers, polyurethanes and axial compressive forces simultaneously. Increasing use of hydroforming in automotive applications requires intensive research and development on all aspects of this new technology to satisfy an ever-increasing demand by the industry. A technological review of hydroforming process from its early years to very recent dates on various topics such as material, tribology, equipment, tooling are summarizes.
... Tube hydroforming is an advanced modern manufacturing technology which can be used to form a variety of complex shaped thin-walled com-ponents [1], as shown in Fig. 1.1. Compared with the conventional forming technique, it can not only reduce the complexity and cost of tooling sets, but also improve the dimensional tolerance and surface finish of the product [3][4][5]. Therefore, hydroformed tubular components are widely applied in the automotive, aerospace and aviation industries [6][7][8][9]. ...
... Besides, an accurate evaluation of incoming tube material properties is essential for the input data in the Finite Element Method (FEM). 3 To determine tubular metal properties, a number of industrial tests have been carried out to measure material behaviors. One of the simplest methods is the tensile test which is used to test sheet metal behaviors commonly. ...
... Tube hydroforming technologies are playing an increasingly important role in modern advanced manufacturing processes, which provide more possibilities for lightweight design and precision production of complex tubular components used in the automotive and aerospace industries [1,2] . The stable quality and excellent performance of tubular products in the metal forming processes require essential information such as the hardening and fracture of the incoming metallic tube [3,4] . Further, an accurate output from the finite element (FE) method also depends heavily on the reliable mechanical property characterization [5][6][7] . ...
Tube hydroforming process is an advanced manufacturing technology for complex thin-walled tubular components applied in the aerospace, aviation and automotive industries. The fluid medium is used as a pressure source to deform tubular materials into the desired shape in this process. Finite element model is a popular method to describe and analyze this innovative process. A successful tube hydroforming operation and reliable finite element simulation depend heavily on the accurate characterization of mechanical
properties of the incoming tubular materials. As a result, it is critical to determine these material parameters utilizing suitable experimental tests and evaluation procedures.
This thesis presents the development of an automatic inverse parameter identification framework combining finite element models with gradient-based algorithms and its utilization in determining material parameters for thin-walled metallic tubes. The main principle of the inverse framework is the minimization of the objective function defined as the least square error between simulated results and experimental observations. Finite element methods are used to describe and analyze the experimental testing process and
gradient-based optimization techniques adjust the input material parameters in the model until the calculated results have a good agreement with the experimental measurements.
The feasibility and performance of this proposed inverse framework are demonstrated through applying it to different tube hydraulic bulge tests with fixed and forced end-conditions to identify the flow stress data of thin-walled aluminium tubes. The bulge height, axial compressive force, and pole thickness are measured during the experiment and input into the inverse strategy. Based on the obtained material values, finite element simulated models of hydroforming processes are established and used to predict the shape
properties of final products. The comparison between simulated predictions and experimental data shows that the developed inverse strategy provides a robust and effective method to determine material properties
for thin-walled metallic tubes.
Furthermore, a theoretical analysis is integrated into the inverse framework, and the two are recombined into
a hybrid strategy to avoid local minimums in the parameter identification process. The new strategy is tested
by the experimental data from fixed and forced tube hydraulic bulge tests. As a result of this research,
it is possible to conclude that the novel hybrid strategy does not depend heavily on the initial points and
can improve the computation robustness and identify more accurate constitutive parameters for tubular
materials.
... Tube hydroforming technology has been widely used for forming lightweight or complicated components in the automotive industry and aerospace industry, etc. [1][2][3][4][5]. To obtain the perfect hollow components with the hydroforming process, the appropriate loading path is required. ...
... This unfavorable deformation will occur within the flaring test using a conical tool with a big vertex angle. Generally, the flaring test using a conical tool with a small vertex angle is more meaningful for investigating the tube hydroformability and circumferential mechanical properties [5]. In order to obtain F and n values with high accuracy and reliability, as well as reduce the adverse effect of the wavy deformation of the tube during the flaring test using a conical tool with a semi-angle of 30 • , the m value is chosen to be a little smaller than 1. ...
The investigation into the circumferential mechanical properties of tubular materials has been receiving increasing attention, since the tube hydroforming process has been used in the tubular materials forming field, because the circumferential mechanical properties have a significant effect on the hydroformability of the tubular materials. In the present study, a method for evaluation of the circumferential mechanical properties of the tubular materials with the flaring test was proposed. The expressions for the yield stress, strain hardening coefficient and exponent values of the tube were successfully derived based on the geometrical and mechanical relationships in the tube flaring test. To verify the reliability of this method, the calculated results of the yield stress, strain hardening coefficient and exponent values, obtained from the newly proposed method, were compared to the ones obtained with the conventional tensile tests. It was found that the method proposed in the current study is reliable, with high accuracy. The method is appropriate to evaluate the circumferential mechanical properties of the tubular materials.
... The products of tube hydroforming processes are widely used in different sectors of the industry [2][3][4][5][6], including the production of micro-parts [7,8]. Several comprehensive reviews on hydroforming technologies are available [9][10][11][12], where the advantages and disadvantages of these technologies are discussed in detail. ...
... By definition, ∂r/∂t = u. This equation and Equation (9) combine to give ∂r ∂a ...
The main objective of the present paper is to provide a simple analytical solution for describing the expansion of a two-layer tube under plane-strain conditions for its subsequent use in the preliminary design of hydroforming processes. Each layer’s constitutive equations are an arbitrary pressure-independent yield criterion, its associated plastic flow rule, and an arbitrary hardening law. The elastic portion of strain is neglected. The method of solution is based on two transformations of space variables. Firstly, a Lagrangian coordinate is introduced instead of the Eulerian radial coordinate. Then, the Lagrangian coordinate is replaced with the equivalent strain. The solution reduces to ordinary integrals that, in general, should be evaluated numerically. However, for two hardening laws of practical importance, these integrals are expressed in terms of special functions. Three geometric parameters for the initial configuration, a constitutive parameter, and two arbitrary functions classify the boundary value problem. Therefore, a detailed parametric analysis of the solution is not feasible. The illustrative example demonstrates the effect of the outer layer’s thickness on the pressure applied to the inner radius of the tube.
... Faltenbildung tritt nach Überschreiten der lokalen Knickstabilität in der Napfwand bei der Kraft F Falt auf [9]. Die Kraft ergibt sich aus der kritischen Spannung multipliziert mit der Querschnittfläche des Napfes. ...
... Die Kraft ergibt sich aus der kritischen Spannung multipliziert mit der Querschnittfläche des Napfes. Die Kraft, bei der Faltenbildung auftritt F Falt wurde nach folgender Formel berechnet [9]: ...
Innenhochdruck-Umformen (IHU) eignet sich durch gute dynamische Materialeigenschaften und einen produktiven Prozess für die Serienfertigung von Bauteilen für die Automobilindustrie. In dieser Arbeit wurde ein neuartiges Werkzeugkonzept entwickelt, um IHU von massiven Napfhalbzeugen auf einer einfach wirkenden Presse zu ermöglichen. Zur Substitution des aufwendigen Drucksystems, bestehend aus Dichtstempeln und einem Druckaggregat, wurde ein Elastomer als alternatives Druckmedium verwendet.
Hydroforming is a suitable process due to excellent dynamic material properties and a productive process for the mass production of components for the automotive industry. In this work, a novel tooling concept was developed in order to enable hydroforming of solid cups on a single acting press. For the substitution of the costly pressurizing system – consisting of sealing punches and pressure unit – an elastomer was used as an alternative pressurizing medium.
... Tube hydroforming has been widely employed to create parts in a variety of fields due to increased demand for lighter parts, utilizing light materials will substantially reduce weight. Because of its special advantage of having uniform thickness distribution and its formability, THF has found employment in the aerospace and automobile industries like camshafts, crankshafts, and spaceframes [1][2][3][4][5][6]. THF has some drawbacks, despite a wide range of applications such as leakage of pressurized fluid [7,8], expensive tooling, and process maintenance. ...
For several decades, scientists and engineers have been using the tube hydroforming (THF) process for numerous applications in the automotive and aerospace industries. The inert advantages like weight reduction without compromising on strength, improved part quality, better surface finish, and reduced tooling costs have motivated the use of THF in the fabrication industry. The presence of grooves on the pre-forms was found to immensely help in increasing the pressure-withstanding capacity of the THF tubes, in addition to reducing the stress concentration and achieving the near-net shape during the THF process. This project involves the development of a detailed Finite Element Model, for the THF process. Numerical analysis is carried out in two stages: Stage-1: Groove Formation, and Stage-2: Final THF tube formation. In Stage 1, the numerical model investigates the formation of grooves, predicting the amount of internal pressure and axial feeding that are required to accurately form them. In Stage 2, numerical simulations focus on the actual THF process. This two-stage THF process (Grooved-THF) was compared to a single-stage Generic THF process. The results indicate the Grooved-THF to be producing a relatively lower thickness reduction with a more closely formed corner radius compared to the generic case. The work also involves multi-objective optimization of the process parameters like the number of grooves, coefficient of friction, internal fluid pressure, and die corner radius using the DOE technique – RSM. The results indicate the number of grooves and the friction coefficient to be the most influencing parameters in the THF process.
... To save weight, eccentric components could be utilized more frequently in crankshafts, camshafts, and other rotating parts, as shown in a simulation by Zhang et al. [35], who used moveable-die tooling, a process that was suggested long ago as a possible area of research [13] and patented in 1959 [36]. Hydroforming has the potential to replace incremental manufacturing processes in the production of bleed valve ducts, fairings, and complex exhaust systems for gas-turbine engines. ...
Hydroforming is an emerging technological advancement that exhibits extensive potential in various industrial sectors. Typically, components are fabricated with hydroforming through pressure-assisted methodologies. The sheet metal forming technique in question has been in use for a significant duration, dating to the pre-World War II era. Hydroforming is typically classified into two main types, tube and sheet. Both use a fluid (water or oil) as a working medium, but they differ in other aspects like process design, tooling, and range of application. Hydroforming has attracted much attention in the last few decades in numerous industrial applications, especially in automotive industries. Demand for hydroforming technology is increasing exponentially, with many new processes entering the area like warm sheet hydroforming, viscous pressure forming, and hydroforming of sheet metal pairs and tailor-welded blanks. The current review is focused on the main theory behind the two hydroforming processes, the recent research in hydroforming technology, hydroforming applications and challenges, and computational hydroforming modeling along with a summary and perspectives.
... Super long pipes and complicated curved pipe structures are common in engineering applications. Pipe welding technology can be used to complete pipeline construction at low cost and high efficiency according to corresponding engineering needs [4]. Traditional manual welding has difficulty producing the high-quality weld joints required for pipeline docking; thus, semi-automatic and automatic welding have gradually become mainstream in pipeline construction. ...
To solve the shortage of austenite phase precipitation caused by nitrogen loss in the welding process of UNS S2205 duplex stainless steel (DSS), shielding gas nitriding was investigated by adding different N 2 contents in Ar shielding gas during the welding process. A good thin-walled pipe butt joint was formed using the pulsed tungsten inert gas (P-TIG) welding method with Ar-N 2 shielding gas. High cycle fatigue tests of the weld joints were conducted to study the effect of shielding gas nitriding on the fatigue properties. Fatigue tests at three stress levels of 225 MPa, 270 MPa, and 360 MPa were carried out on the weld joints with different N 2 contents, and the fatigue samples were all fractured in the high temperature heat-affected zone (H-HAZ). Within the current process parameters, the fatigue life of the 4 vol.% N 2 welded joints was optimal. Fatigue striations appeared in the fatigue crack propagation zone, and the transient fracture zone was similar to the tensile fracture. Under the low-stress level, the area of the crack propagation zone under 4 vol.% N 2 was the highest, the tear ridges all expanded around the crack source area, and the fatigue crack propagation zone presented a radial distribution. The proliferation and expansion of dislocations were mainly carried out in the austenite grains, and the dislocation density of the fatigue specimens under 4 vol.% N 2 was smaller than that of the Ar specimens. Shielding gas nitriding effectively improved the balance of the two-phase ratio and the hardness of austenite phase, optimized the internal slip system, inhibited the proliferation of dislocations in the austenite phase, and improved the fatigue life of weld joints.
... It is widely utilized in rockets, aircraft, and automobile industries. It can effectively reduce the weight and improve the strength of components [3][4][5]. Because the axis of the formed part is usually a curve, it is difficult to perform hydroforming directly on the original straight tube. ...
To avoid wrinkling and cross-sectional distortion in thin-walled tube bending, a novel bending process called tube press bending under gas internal pressure (abbreviated as TGPB) is proposed. In the TGPB process, internal pressure serves a supportive function and generates an additional tensile stress, which can reduce the axial compressive stress on the inner side of the bend, avoiding the occurrence of wrinkles and cross-sectional distortions. Compared with the previous tube bending technologies, the support pressure inside the tube will not change suddenly with the volume change of the tube cavity due to the compressibility of gas. It is suitable for thin-walled tube bending with large, variable axial curvatures and high strength as the shape of the target part is determined by the die cavity. A theoretical prediction model of critical support pressure for TGPB without wrinkling defects is established. The critical support pressure, wall thickness, and section distortion of tubes with different curvatures bent by TGPB are analyzed through FE simulations and experiments, and tubes with different material properties are also done through FE simulations. The results indicate that the tube can be stably bent to the desired shape under the predicted critical support pressure, which is significantly affected by the bending radius and material characteristics, increases with strength coefficient, and decreases with bending radius and strain hardening exponent. A high-strength steel prebending part with complex variable axial curvatures has been successfully formed by TGPB technology under a support pressure of 5 MPa; the minimum and maximum bending radii of which are 846 mm and 2373 mm, respectively.
... Moreover, an adequate die-tube interface is required for friction minimization [5]. THF takes advantage of lower tooling and assembly costs, fewer secondary operations and waste [6], higher complexity of cross-sections and shapes [7], part weight reduction, higher part quality, strength, surface finish [8] and dimensional accuracy [9]. THF is suitable for several fields as automotive [10], fluids delivery, aircraft, structural components [11], nozzles and home appliances [12]. ...
Tube hydroforming (THF) is an assessed production process for the fabrication of tubular components. Its main advantages are the enhancement of the material strength and the shortening of the production chain. Moreover, THF allows to obtain complex geometries all in one so reducing the number of production steps, assembly time and production costs. For these reasons, THF finds applications in many industrial fields. The design of the production process is typically done in two subsequent steps, using Finite Element Models (FEM) and, then, experiments. FEM allows to outline the process curves globally (punch strokes and pressures) and to estimate the loads (punch and die closing forces), while experiments validate the FEM and perform the final tuning of the process. To reduce the efforts in the experimental phase, a reliable FEM software is necessary. The available commercial software can be divided into two main groups depending on the solving algorithms: explicit and implicit. Explicit software is faster but less reliable, the opposite for implicit one. Moreover, in the case of thin-walled parts (such as tubes or sheets), also the type of mesh adopted can be grouped into two: shell and solid meshes. The main differences are the same as the solver, faster but less precise the first and the opposite for the second. Given these countertrends in computation, this paper aims at comparing two software for THF: an explicit with shell elements (PamStamp) and an implicit with solid elements (DeForm). The comparison will highlight the pro and cons of the two solutions and, finally, a trade-off will be proposed.KeywordsTube HydroformingOptimizationFEMPamStampDeForm
... Tube hydroforming is defined as a process that deforms a tubular blank into a component with complex geometries and variable cross sections by simultaneously applying hydraulic pressure and axial force [1]. This process has been studied from different perspectives, such as, bi-axial characterization of material properties [2,3], impact of friction coefficient [4][5][6], application of warm forming [7,8], pulsating hydraulic pressure to enhance hydroformability [9,10], tool geometry optimization [11], and multistep THF [12,13]. ...
This research presents the detailed tube hydroforming (THF) process to produce an airfoil shape,
which is commonly used in aero-engines and ground gas turbines. LS-DYNA V970 was first used
to develop the 3D Finite Element (FE) model of the hydroforming process and to study the
thickness and strain distributions of the formed tubes. Experiments with two different material
types, Inconel (IN) 718 and stainless steel (SS) 321, were then conducted to validate the
simulation results. The strain distribution on the outer surface of the formed tubes was measured
with a digital image correlation (DIC) system, while an ultrasonic method was used to measure
the thickness of the hydroformed tubes. Also, tube expansion during the THF process was
recorded with a laser measurement system that was implemented directly inside the hydroforming
tool. Good agreement between the experimental and simulation results was obtained, specifically,
for the final shape, tube thickness and strain distribution. Therefore, this study shows clearly that
the THF process is a reliable and feasible method for manufacturing complex airfoils.
... The recent pasts have appealed immense applications of curved tubular parts in automobile, aerospace, oil industries where high strength/weight ratio elements are needed [1,2]. The defectsoccurring in the tube due to bending process are of prime concern and should not be neglected. ...
The strength deformation behavior of thin walled aluminium alloy 6063 tubes under flexure has been presented. The effects of deformation, thinning, thickening of the tube wall surfaces, ovalness of the tube and springback angleat critical cross sections of the aluminium tubes are studiedunder different computer numerical control (CNC) bending conditions. Aluminium alloy tubes of 25mm outer diameter, 390 mm length and varying thickness of 1, 1.5 and 3mm have been used for testing. It is observed that, thinning and thickening of inner and outer bend of tube gradually rises with increase in the bend angle and meantime surface flattening and non-circularity of tube in terms diameters also upsurges for the increase in bend angle.Furthermore, experimental outcome of deformed tube is compared and characteristic result for effect of experimental parameters is found to be in good agreement with literature values.
... In the¯lling stage, the die is closed and both ends of the tube were sealed with axial punches, then the tube is¯lled with water. 2,3 In forming stage, the tube takes the shape of the die on increase of internal pressure with the help of water intensi¯er along with feeding of the stock with the help of axial punches. In calibration phase, the deformed blank con¯rms¯nal dimensions of die. 4 The performance of the tube can be predicted with the help of mechanical properties of sheet and having knowledge on tube making operation. ...
Tube hydroforming (THF) is an unconventional manufacturing technique that uses pressurized fluid in place of conventional punches to deform the tubular blank into the desired shape. In THF process tubular blank is deformed it into the final shape by applying fluid pressure mostly by water using water intensifier through axial punches. Tube hydroforming is mainly used to produce hollow components using tubular blank which find applications in automobile industry, particularly for exhaust systems. The formability of Austenitic stainless steel tubes as function of microstructure is not focused much in literature. Hence, in this study, formability of Austenitic stainless steel tubes is studied as a function of boundary conditions and bulge width (L/D ratio) and correlated with microstructure. Microstructure resulting in axial feed condition showed better formability than microstructure resulting in fixed feed condition. Similarly, formability and fracture behavior of tube predicted with finite element-based simulation using PAMPSTAMP 2G solver found results, particularly bulge height and fracture location are in good agreement with experimental values. The observed fracture mode noted was ductile both for axial feed condition and fixed feed condition as the fracture consists of voids and micro voids. Fracture location was in base metal just, besides, weld line for axial feed condition and fracture location was in base metal which is little away from weld line for fixed feed condition.
... Furthermore, weight reduction in nextgeneration vehicles can be achieved by the replacement of stamped and spot-welded steel assemblies [2]. Many of the structural members of the automobile are now made via a hydroforming manufacturing method that includes such as cradles [3] and pillars, [4]. Therefore, through the THF process, manufacturers are able to produce complex-shaped parts with lightweight and fewer welds than through alternative metal forming techniques [5]. ...
In this research mathematical model was developed utilizing the 3D finite element method and response surface methodology to describe the tube hydroforming production process. This paper is an example of the relatively simple analysis of the influence of the technological parameters on hydroformed T-shaped tube protrusion height, diameter, and thickness utilizing statistical analysis and 3D finite element analysis in the QForm UK 10.2 commercial software. Therefore, this paper could be beneficial for both researchers and engineers interested in tube hydroforming design guidelines and simple optimization methods. The influence of the hydroforming die radius filler, axial tool displacement, and counter punch force on the T tube protrusion height, diameter, and thickness was described and optimized.
... As for the main failure models, they are found to be bursting, wrinkling, and buckling. These failures are mainly related to the key input process parameters, tooling, and workpiece material [7,8]. Among these factors, it is possible to refer more specifically to the load path [9], die design [10], friction at tube-tool interfaces [11], and material properties [6,8]. ...
The design capability, strength, and structural rigidity provided by tube hydroforming (THF) are successfully used in many applications to produce high-strength parts and assemblies with improved mechanical properties, optimized service life, and weight features. In tubular metal forming, output parameters such as branch height, distribution of tube wall material thickness, distribution of damage factor, metal flow, effective stress, and effective strain significantly affect the quality of the product after the forming process. Therefore, this paper aims to evaluate the manufacturing quality of Y-shape joints from AISI304 material steel tube through output parameters of THF process with and without counter punch force on numerical simulation base. The Finite Element Method (FEM) has become an established feature of metal forming technology. The objective of FEM is to replace costly and elaborate experimental testing with fast, low-cost computer simulation. The simulation study uses finite element method-based virtual prototyping techniques to characterize output parameters, gain insight into strain mechanics, and predict mechanical properties of shaped components. The research results are presented clearly and unambiguously through the evaluation of 7 criteria to compare the quality of the specimens hydroformed by two surveyed cases and optimize the crucial input process parameters. And these data can be applied in experiments, more efficient product and process design, calculation, and control of input parameters avoiding costly trial and error in industrial production. The findings can help technologists optimize process parameters in the hydroforming process of products with protrusion from a tubular blank
... Tube hydroforming technology can be divided into three categories according to the different product shapes: variable diameter tube hydroforming, curved axis tube hydroforming, and multi-pass tube hydroforming [3]. Variable diameter components have been widely used as typical structures for automotive exhaust systems and aerospace joints [4]. Variable diameter components are traditionally manufactured by stamping and welding. ...
A new tube axial hydro-pressing method was proposed to solve the problems of high forming pressure and severely uneven wall thickness distribution of traditional tube hydroforming methods to form stepped tubular components. The forming pressure of the traditional hydroforming and the tube axial hydro-pressing method is studied theoretically, the mechanical model of the fillet area is established, and the forming pressure calculation formula is given. Based on this, an investigation of the tube axial hydro-pressing method is carried out by numerical simulation and experimental methods, and compared with the traditional tube hydroforming method. The key to the tube axial hydro-pressing method is to precisely control the relationship between the protrusion height and the axial feed, which is achieved by precisely controlling the feeding pressure and the axial displacement. Therefore, the constant pressure device in the experiment was used to eliminate the influence of the pressure rise caused by the volume compression on its cooperation relationship to achieve accurate control of the loading path and eliminate wrinkles and flash defects. A qualified workpiece is successfully manufactured when the internal pressure is 18.0 MPa and the feed on each side is 15.0 mm. The forming pressure is reduced by 88.0%, and the feed is increased by 6.5%, which reduces the wall thickness reduction by 9.0%. The wall thickness difference of the workpiece can be controlled within 7.0%. The tube axial hydro-pressing method is suitable for forming stepped tubular components, which can achieve more replenishment at lower pressures, thereby effectively improving the uniformity of wall thickness and significantly reducing the forming pressure.
... With the rapid development of the aviation and automobile industry, the multi-way tube hydroforming process has been the focus of research [1]. The principle of hydroforming process is to form various complicated thin-walled hollow section parts by the combined action of mechanical load and hydro-static internal pressure [2,3]. ...
The different branch diameters of five-way tube affect the design of loading internal pressure in the hydroforming process, where the large-diameter branch is broken more easily than the small-diameter one due to the same ultimate stress of tube material in one-step forming method. Therefore, the first four-way and then five-way of multi-step forming (FFTF) method and the first three-way and then five-way of multi-step forming (FTTF) method were proposed to fabricate the 5A02 aluminum alloy five-way tube with two kinds of branch diameters to avoid the burst of large-diameter branch tube. The finite element simulation of five-way tube hydroforming process shows that the height of small-diameter branch tube is lower and serious wrinkles appear at the large-diameter branch tube in the one-step forming and FFTF method. By optimizing the length of punch, a five-way tube with a big branch height and uniform wall thickness was obtained with the FTTF method. The approach of lengthening the punch in the experiment increased the height of formed branch and reduced the wall thickness reduction rate of five-way tube in FTTF method. Overall, the findings mentioned above cannot only offer guide in creating five-way tube with excellent quality, but also be taken as reference to the hydroforming studies on multi-way tube in the future.
... Tube hydroforming is a forming process to form complex-shaped hollow products with closed cross-section geometry from tubes by using internal pressure and axial feeding [1]. To avoid fracture and thinning during the hydroforming of tubes, the material is axially fed along the tube length; however, by increasing the axial force over a critical limit, which is not compatible with the internal pressure, the tube tends to wrinkle [2]. ...
A low pressure sealed-air hot tube gas forming process of ultra-high strength steel tubes was developed not only to change the cross-section of the hollow products by bulging but also to increase the strength of components. Gas-formed components are typically formed by a controlled-gas pressure with extremely high internal pressure, which leads to affected production costs and safety. Moreover, compressing the gas with high pressure requires high energy during its preparation. Therefore, to simplify the internal pressure controlling system and improve the safety factor in gas forming processes, the sealed-air tubes are formed with a quite low initial pressure. The pressure of the sealed air increased with increasing temperature of the air inside the resistance-heated tube, and the bulging deformation was controlled only by axial feeding. The effects of the initial pressure and heating temperature on the bulging deformation and quenchability of the tubes, and the effect of the starting time of axial feeding on the bulging behavior were examined. Consequently, ultra-high strength steel bulged parts were produced even in low initial internal pressure and with the rapid heating of the tubes.
... The stable quality and excellent performance of tubular products in the metal forming processes require essential information such as the hardening and fracture of the incoming metallic tube [3,4] . Further, an accurate output from the finite element (FE) method also depends heavily on the reliable mechanical property characterization [5][6][7] . ...
A T-shape tube hydraulic bulge test under axial feeding force is carried out to characterize the mechanical properties of EN AW 5049-O and 6060-O aluminium alloys. The punch displacement, T-branch height and axial compressive force are recorded online during the experiment. An intelligent inverse identification framework combining the finite element method and numerical optimization algorithm is developed to determine material parameters by fitting simulated results to the experimental data iteratively. The identified constitutive parameters using the inverse modelling technique are compared with those determined by the theoretical analysis and uniaxial tensile test. The comparison shows that the predicted bulge height and punch force based on the material parameters obtained by the three methods are different and the inverse strategy produces the smallest gap between numerical and experimental values. It is possible to conclude that the hydraulic bulge test can be applied to characterize the stress-strain curve of tubular materials at the large strain scope, and the automatic inverse framework is a more accurate post-processing procedure to identify material constitutive parameters compared with the classical analytical model.
... Process run-in typically requires several trial and error from an experienced operator where initial punch position, initial pressure, pressure profile, and initial tube length are adjusted/manipulated. The primary objective during run-in is to identify a set of process parameters that are geometrically feasible and robust, i.e., avoiding the three major failure modes, see Koc and Altan [4]: ...
The present work will address the problem of designing an in-process control system for a tube hydro-forming process, controlling the tool filling forming a T-tube. The control problem is nontrivial as wrinkling and bursting will develop rapidly and, in most cases, are irreversible—thus, the control system must react fast and without extensive overshoot. The objective is to control the tool filling, reproducing a reference filling trajectory, where the controller input is defined as a correction of the reference forming pressure. The control system was verified experimentally, using four different error scenarios. Initially, the error was provoked, by manipulating the input signal, and for all three cases, the control system successfully eliminates both wrinkling and bursting. Finally, the material was changed going from an aluminum grade 5049-0 to 6060-T6 also; in this case, the control system eliminates the error and stabilizes the process. The control strategy and implementation was developed using numerical simulation (explicit finite element), and the controller implementation was reused directly in the experimental setup without manipulating or scaling the gain factors.
... Manufacturing high-strength parts and extra light metals that are difficult to shape using conventional sheet metal shaping techniques are also advantages of the VPF process. [28]. The innovative Solid Granular Medium Forming (SGMF) technology addresses hydroforming disadvantages, such as leakage and low heat resistance. ...
The present research focused on reviewing forming technology and inspired various method forming processes for different lightweight materials. Nowadays, to improve modern automobiles' fuel economy while preserving safety and efficiency, advanced materials are essential. Since accelerating a lighter object requires less energy than a heavier one, lightweight materials offer great potential to improve vehicle performance. Innovative forming technologies are discussed concerning each approach and their contribution to lightweight material application. New metal forming methods are implemented to fulfill lightweight material applications in various fields.
... Tube hydroforming technology can be divided into three categories according to the different product shapes: variable diameter tube hydroforming, curved axis tube hydroforming and multi-pass tube hydroforming [3]. Variable diameter components have been widely used as typical structures for automotive exhaust systems and aerospace joints [4]. Variable diameter components are traditionally manufactured by stamping and welding. ...
A new tube axial hydro-pressing method was proposed to solve the problems of high forming pressure and severely uneven wall thickness distribution of traditional tube hydroforming methods to form stepped tubular components. The forming pressure of the traditional hydroforming and the tube axial hydro-pressing method is studied theoretically, the mechanical model of the fillet area is established, and the forming pressure calculation formula is given. Based on this, an investigation of the tube axial hydro-pressing method is carried out by numerical simulation and experimental methods, and compared with the traditional tube hydroforming method. The key to the tube axial hydro-pressing method is to precisely control the relationship between the protrusion height and the axial feed, which is achieved by precisely controlling the feeding pressure and the axial displacement. Therefore, the constant pressure device in the experiment was used to eliminate the influence of the pressure rise caused by the volume compression on its cooperation relationship, to achieve accurate control of the loading path, eliminate wrinkles and flash defects. A qualified workpiece is successfully manufactured when the internal pressure is 18.0 MPa and the feed on each side is 15.0 mm. The forming pressure is reduced by 88.0%, and the feed is increased by 6.5%, which reduces the wall thickness reduction by 9.0%. The wall thickness difference of the workpiece can be controlled within 7.0%. The tube axial hydro-pressing method is suitable for forming stepped tubular components, which can achieve more replenishment at lower pressures, thereby effectively improving the uniformity of wall thickness and significantly reducing the forming pressure.
... With the rapid development of the aviation and automobile industry, the multi-way tube hydroforming process has been the focus of research [1] . The principle of hydroforming process is to form various complicated thin-walled hollow section parts by the combined action of mechanical load and hydro-static internal pressure [2,3] . ...
The different branch diameter of five-way tube affects the design of loading internal pressure in the hydroforming process, where the large-diameter branch is broken more easily than the small-diameter one due to the same ultimate stress of tube material in one-step forming method. Therefore, the first four-way and then five-way of multi-step forming (FFTF) method and the first three-way and then five-way of multi-step forming (FTTF) method were proposed to fabricate the 5A02 aluminum alloy five-way tube with two kinds of branch diameters to avoid the burst of large-diameter branch tube. The finite element simulation of five-way tube hydroforming process shows that the height of small-diameter branch tube is lower and serious wrinkles appear at the large-diameter branch tube in the one-step forming and FFTF method. By optimizing the length of punch, a five-way tube with a big branch height and uniform wall thickness was obtained with the FTTF method. The approach of lengthening the punch in the experiment increased the height of formed branch and reduced the wall thickness reduction rate of five-way tube in FTTF method. Overall, the findings mentioned above can not only offer guide in creating five-way tube with excellent quality, but also be taken as reference to the hydroforming studies on multi-way tube in the future.
... World-class numerical predictions required for minimizing the time and cost due to manufacturing the prototypes are indeed related to the accuracy of the constitutive models used in the simulations. Identification models accounting for hardening, anisotropy, and ductile damage are still essential for the control design problems related particularly to spring back deformation, forming limits, dimensional tolerances, and cost of production (Achouri et al., 2014;Koç & Altan, 2001;Naceur et al., 2006;Varma et al., 2007). Plastic forming of metal sheets with incremental strain rates and optimized load paths is the most used process. ...
The sheet metals are prone to large plastic deformation during forming processes. The study purpose is to investigate 1050A aluminum sheets thermomechanical behavior with ductile damage. A modified Swift model coupled to isotropic ductile damage and thermal effects was used. The forming parameters are introduced using Swift model coefficients and Erichsen index. An inverse identification procedure is applied to nonhomogeneous Erichsen test results. Bulge test is then used to validate the identified parameters. Erichsen test (Punch force vs displacement) results were obtained by experimental testing and simulation to build the objective function. Aluminum 1050A plasticity flow parameters and ductile damage variables were identified using a part of Erichsen test results. The remaining part of Erichsen test and bulge test results were used for validation. The numerical approach allowed the detection of failure zones with respect to thermal gradient induced by heat exchange. Within the isothermal condition, equivalent stresses and strains for 1050A Aluminum were obtained by simulations and experimental data.
... The hydroforming procedure obtain popularity after his study and specialists carried on more studies on this subject to manufactured tubes with complicated protrusions. Koc and Altan [6] introduced a general survey of the tube hydroforming procedure. This paper briefs a technological survey of hydro forming technology from its initial years to very modern years on different subjects for example tube hydroforming parts, technology, process, hydraulic and control system, materials and formability in THF, friction and evaluation lubrication, performing of tube for hydroforming process, at last advancements and directions in hydroforming innovation, so another researchers at different regions around the world can application it for further studies here. ...
... Muammer et al. [9] summarize a technological review of hydroforming process from its early years to the end of the twentieth century on various topics such as material, tribology, equipment, and tooling, and put forward the future development direction of hydroforming process, which provided great convenience for other scholars in this field. Wang et al. [10] investigated the effect of temperature on vacuum thermal bulging of BT20 titanium alloy ring by means of finite element simulation and put forward the optimum temperature for vacuum thermal bulging of BT20 alloy. ...
Ring rolling technology is widely used in the production of GH4738 aerospace rings, but the ring produced by ring rolling often has the phenomenon of uneven stress and unqualified strength. To solve these problems, the thick-walled ring bulge forming technology was proposed. In this paper, a 3D-coupled thermo-mechanical FE model of the GH4738 rectangular ring bulging process was developed, which is verified to be in good agreement with the experimental process. Based on this model, the thermal parameter distribution and evolution of GH4738 rectangular ring during the bulging process were investigated systematically. Then, the evolution of the minimum bulging displacement (BD) required for rings with the change of ring size was obtained by comparing the stress distribution of rings during the bulging process in seven cases. All these provide a theoretical basis for the selection of optimal BD in practical production. Finally, the influence of the bulging process on the microstructure and mechanical properties of GH4738 alloy ring was analyzed by experimental means, and it was verified that the bulging process can play a good role in improving the strength of the ring from the perspective of the average geometrically necessary dislocation (GND) density. The experimental results indicate that with the increase of BD, the grain size of the ring does not change that much, but the average GND density increases gradually, and the yield strength and tensile strength of the ring increase significantly.
... Deep drawing is a process in which a sheet, usually controlled by a compression plate (i.e. blank holder), is drawn by a punch into the die and forms a final shape (i.e. the product), whose thickness is about the initial sheet thickness [1]. Determining the appropriate blank holder force during the process is one of the most important parameters of DD, which low enough forces could cause wrinkling and excessive high forces causes rupture in the sample [2]. ...
In recent decades, the use of aluminium alloys is developed in the automotive industry with regard to the need for lightweight and anti-corrosion components, one of which is AA7075 Al alloy. In this study, the multi-step deep drawing process of AA7075 aluminium sheets under various blank holder forces is investigated through a numerical simulation and is then validated with experimental results. Simulations were conducted by ABAQUS finite element software, and the influences of the blank holder force on the wrinkling height, rupture occurrence and thickness distribution of the sheet were studied. The optimum amount of blank holder force at each drawing step is determined so that the height of wrinkling, and the thinning percentage do not exceed the permissible value. Based on the results, the blank holder force magnitude should be considered descending during the four successive steps to achieve more uniform thickness distribution, and also the wrinkling height could be reduced by increasing the blank holder force in the analysed force range. The optimum amount of blank holder force in the four drawing steps was 28000, 2500, 1500 and 600 N, respectively. In general, the minimum thickness was created in the corner of the punch. The results also showed that an excessive increase in the blank holder force in order to eliminate the wrinkling caused the thinning percentage to increase. Finally, a good accordance between the experimental and numerical results was observed.
... In hydroforming technology, a pressurized liquid (water or oil) is used for forming products [4]. Shaping flat and tubular metal sheet products by the above-mentioned technology is in common use [5]. ...
The subject of research is car exhaust system piping made of chromium–nickel steel of grade AISI304L with a unique, complex shape that was obtained by hydroforming technology. The purpose of the research was to determine the relation between the microstructure features, surface condition, hardness and the stresses on the external surface as determined by the sin ² ψ X-ray method. We found that the stresses were tensile and correlated with the steel hardness, i.e. they were greater where the hardness was higher. Moreover, longitudinal stresses showed a relationship with pipe wall thickness, while circumferential stresses did so only partially. According to our data, the greatest value of stress determined in the pipe amounted to 290 MPa, and was close to the yield point of the strain hardened 304L steel. As depicted via XRD and SEM examination, the pipe stress level and hardness were influenced by the transition γ→α’. Furthermore, in the region of higher stress and hardness, the amount of martensite was 10 vol.%. We also noted that the pipe’s outer surface when subjected to friction against the die shows lesser roughness compared to its inner surface upon exposure to water under pressure.
... S 0 Initial tube thickness (mm) S 1 Wall thickness at the side of movable punch (mm) S 2 Wall thickness at the side of fixed punch (mm) d a Initial outer diameter of the tube (mm) di Initial inner diameter of the tube (mm) d i1 Final inner diameter of the tube at the side of movable punch (mm) THF (tube hydroforming) is a non-conventional metalforming process where an initial tube can be converted into a preferred shape within a die using internal pressure and feeding instantaneously [1]. Tube hydroforming has several advantages such as high structural and weight integrity of the product and reduces production cost, material saving, less joining processes, improvement in product reliability, and high load carrying capacity of structures with uniform wall thickness. ...
In tube hydroforming, a desired shape is obtained by applying internal pressure and axial feeding instantaneously. To yield the material, the internal pressure offers the stress required, whereas axial feeding facilities metal flow which help to produce a part without crinkles and with even wall thickness. Pressure hydroforming applies loading path with fluctuating pressures. In this research work, hydroforming with high pressure is used to manufacture metal expansion bellows experimentally. Four process parameters are selected in pressure loading path to decide most dominating parameter. Using Taguchi DOE (design of experiments) with four parameters and three levels for each parameter, 9 experiments are conducted to study the effects of pressure parameters on the parts defects with shape accuracy. S/N ratio and ANOVA (analysis of variance) are applied to regulate the important process parameters affecting the final part in terms of wear rate and COF (coefficient of friction) for three different materials such as SS304, SS316, and SS316L. Three linear regressions without any interaction between the parameters are extracted for three quality responses and are evaluated through three extra experiments. The results show reasonable agreement between the experimental and linear regression models. The results of the present study could be used as a basis of designing a new type of the metal bellows manufactured by tube hydroforming.
... The 'bulge test' term in literature refers to a variety of test systems including both testing of the sheet and tube-formed samples with several differences in practice [4]. Tube bulge test is preferred mainly for determining the hydro-formability of the tubular materials as developed and explained in various previously published studies [11,12]. On the other hand, sheet bulge test systems can be categorised in terms of the pressure source for the bulging, the die shape or die dimensions used. ...
In this paper, analytical, finite element modelling (FEM) and experimental studies are conducted on the biaxial stretching of extra deep drawing steel sheet using hydraulic bulge test, where the true plastic strain exceeds 70%, in contrast to the 20–30% strain achieved in the conventional uniaxial tensile test. The analytical modelling includes four different approaches, namely, Hill, Panknin, Chakrabarty and Kruglov. FEM is done using three yield criteria, Hill-48, Barlat-89 and Barlat-2000. Experimental results show that the stress-strain relationship using bulge radius based on Panknin approach and thickness based on Kruglov approach in the analytical study and using Barlat-2000 yield model in FEM study are in close agreement with the experimental curve. Fractography study, conducted on specimens from tensile and bulge test, reveals/confirms the presence of more deep elongated shear dimples in bulge test compared to equiaxed dimples in the tensile test. This corroborates with the experimental results of achieving the high level of plastic deformation till fracture in the hydraulic bulge test.
... Tube bulge test is mostly utilized to know the formability of the tube specimen as developed and clarified in different recently published investigations. [25][26][27][28][29] Similarly in sheet hydraulic bulge tests also fluid pressure is used to bulge/protrude as per the die cavity. Bulging in the sheet hydroforming is carried out by pumping hydraulic fluid into the die cavity. ...
Advanced forming technologies have been evolving at a rapid pace with the products applicability in the industrial fields of aerospace and automobile especially for the materials like aluminum and titanium alloys (light weight) and ultra-high strength steels. Innovative forming methods like hydroforming (tube and sheet) have been proposed for industries throughout the world. The ever-increasing needs of the automotive industry have made hydroforming technology an impetus one for the development and innovations. In this paper, the review on various developments towards lightweight materials for different applications is presented. The influencing process parameters considering the different characteristics of the tube and sheet hydroforming process have also been presented. General ideas and mechanical improvements in sheet and tube hydroforming are given late innovative work exercises. This review will help researchers and industrialists about the history, state of the art in hydroforming technologies of the lightweight materials.
... One of the main strategies to achieve lightweighting is to use hydroformed welded tubular structures of suitable steel grades for various vehicular component. This not only reduces the weight but also results in cost savings due to higher productivity and lower assembly cost because of part consolidation [1,13,14]. The combined utilization of welded tubes and hydroforming technology yields multiple benefits in automotive and aerospace manufacturing sector. ...
A drawing quality welded steel tube with outer diameter of 57.15 mm and thickness of 1.6 mm was used in this study. These tubes were hydroformed at bulge ratio (or L/D ratio) of 1, 2 and 3 to achieve different strain paths. It was observed that the tubes after hydroforming fractures in the base metal near the weld for L/D=1 whereas for L/D=2, 3 the fracture occurs in the base metal opposite to the weld which was a novel observation. The experimental and simulated strain paths for two extreme L/D ratios of 1, 3 were analysed. It was found that the maximum value of major strain was found at the base metal for all L/D ratios, however, its location and subsequent fracture depends upon L/D ratio. Therefore, to investigate this anomaly, the detailed FE analysis was carried out by varying the ratio of strain hardening exponent between base and weld metal and by introducing the thickness imperfection in the tube. The FE analysis predicts the trade-off between the material inhomogeneity and thickness imperfection leading to fracture at specific location for both L/D. The present study concludes that the relative sensitivity of thickness imperfection versus material inhomogeneity is dictated by the tube bulge ratio.
... Due to the advantages of smaller stiffness, greater compensation capabilities and longer lifetime, multi-layered metallic bellows have excellent performance in the complicated working conditions, such as high pressure, high frequency vibration and large axial displacement, and have become important and almost irreplaceable elastic components used in piping, automotive, rocket engine and micro-electromechanical systems, etc [1][2][3][4] . Among various forming methods, such as rolling, electroforming, etc., the hydroforming has become an advanced and preferred technology to form the bellows nowadays because of its advantages of high efficiency and flexibility [5][6][7][8] . A typical bellow hydroforming process is shown in Fig.1 The multi-layered bellow hydroforming is a three-dimensional nonlinear physical process with complicated contact behaviors and constraint effects occurred among layers. ...
Because of the complex constraint effects among layers in multi-layered metallic bellows hydroforming, the stress concentration and defects such as wrinkling and fracture may easily occur. It is a key to reveal the deformation behaviors in order to obtain a sound product. Based on the ABAQUS platform, a 3D-FE model of the four-layered U-shaped metallic bellow hydroforming process is established and validated by experiment. The stress and strain distributions, wall thickness variations and bellow profiles of each layer in the whole process, including bulging, folding and springback stages, are studied. Then deformation behaviors of bellows under different forming conditions are discussed. It is found that the wall thinning degrees of different layer vary after hydroforming, and is the largest for the inner layer and smallest for the outer layer. At folding stage, the wall thinning degree of the crown point increases lineally, and the difference among layers increases as the process going. The displacements of the crown point decrease from the inner layer to the outer layer. After springback, the U-shaped cross section changes to a tongue shape, the change of convolution pitch is much larger than the change of convolution height, and the springback values of the inner layer are smaller than the outer layer. An increase in the internal pressure and die spacing cause the maximum wall thinning degree and springback increase. With changing of process parameters, bellows with deep convolution are easily encountered wall thinning during hydroforming and convolution distortion after springback. This research is helpful for precision forming of multi-layered bellows.
Series manufacturers in the field of hydroforming do not always have the necessary database for predictive maintenance, especially for the production of complex hydroformed components. Small and medium-sized companies in particular often lack the resources to acquire, process and profitably utilize these data sets under production conditions. The IHU processes that occur in practice are usually highly complex, both in terms of geometry and against the background of additional process steps (punching, plunging). This results in large amounts of data and complex data analyses, which are reflected in the data processing costs. A data analysis is to be carried out on the basis of a complex hydroforming process and its additional benefit for quality management and predictive maintenance is to be explained.
In the present work, we perform a numerical study that explore the influence of the variability of mechanical properties and process parameters on the prediction of the pole height evolution in tube hydroforming process. In order to carry out this study, a mild steel S235 was chosen as the reference material and the free tube hydroforming process was considered. The factors selected for this variability study were the coefficient of friction (μ), the anisotropy coefficients (R0°, R45°, R90°), the dies length (L) and the initial tube thickness (t0). The variability of all factors was described by a probabilistic normal distribution, with a well-defined mean and standard deviation. Different simulations were performed by varying the process parameters for each trial of the Box-Behnken table of the experimental design. This numerical study was followed by response surface modelling and graphical analysis. ANOVA was also performed to determine the significant parameters and their impact on the response. Finally, we can conclude that the factors (L) and (t0) have a clear effect on the height-pole response of the bulge zone.
Hot metal gas forming (HMGF) of tubular profiles enables intricate designs for lightweight material production. HMGF showed an immense manufacturing potential, due to the excellent strength and toughness of the formed parts, better material formability, and better dimensional accuracy of the final product. Existing part production methods, such as weld-assembly of stampings and hydroforming, have significant problems in terms of residual tensile stresses, which can affect the formability and negatively affect the performance capability of the structural components. Due to the lack of a detailed review report, the primary focus of this review article is to provide in-depth analysis of recent developments, innovations, and challenges in HMGF while comparing it to existing manufacturing methods. This examination includes different essential aspects, such as the process principle, material applications, deformation mechanisms, process parameter optimization, and microstructure modeling. Additionally, the article explores future research directions and the potential of HMGF in the manufacturing industry. Our review underscores the critical importance of optimizing process parameters and conducting microstructural analysis to meet evolving challenges. Further research on material models and the interplay of microstructural variables is essential for advancing the field and facilitating precise predictions in HMGF processes.
This study aims to investigate the feasibility of hydroforming (HF) technology coupled with response surface optimization for producing high-quality five-branched AISI 304 stainless steel tubes with different diameters, addressing the shortcomings of traditional manufacturing processes. Conventional techniques often result in issues with multiple consumables, low precision, and subpar performance. The research focuses on finding optimal forming parameters for a more effective process. Initial attempts at a five-branched tube proved unfeasible. Instead, a multi-step forming approach was adopted, starting with the formation of the upper branch tube followed by the two reducing lower branch tubes, a strategy termed “first three, then five”. This method, enhanced by a subsequent solid solution treatment, yielded promising results: the combined height of the upper and lower branches was 141.1 mm, with a maximum thinning rate of 26.67%, reduced to 25.33% after trimming. These outcomes met the product usage requirements. Additionally, the study involved designing and developing dies for manufacturing five-branched tubes with different diameters using servo HF equipment. The effectiveness of the multi-step forming process and parameter combinations was confirmed through experimental validation, aligning closely with the FE simulation results. The maximum thinning rate observed in the experiments was 27.60%, indicating that FE simulation and response surface methodology can effectively guide the production of high-quality parts with superior performance.
The assembled camshaft is a novel manufacturing product which connects the cam and the mandrel by tube hydroforming (THF) technology after they are processed separately. However, in the process of THF, the structure of the cam-bores has a crucial influence on the connection strength of the assembled camshafts. Therefore, three kinds of cam-bores with circular structure, isometric-trilateral profile and logarithmic spiral profile are selected for hydroforming with a hollow mandrel (tube) in this study. The finite-element-analysis is carried out by ABAQUS software, the variations of (residual) contact pressure and contact area under different structures are obtained, and the torsional angle variations after assembly are measured. Further, the connection strength of the assembled camshaft under three structures is discussed. The results show that the evaluation of connection strength of the assembled camshaft is affected by many factors, including contact pressure, maximum residual contact pressure, axial and circular residual contact pressure, contact area and its rate, residual contact area percentage and torsional angle. Through the comprehensive analysis of various factors, the torsional angle of the camshaft with circular structure is the largest, i.e. poor connection strength. By contrast, the torsional strength of the camshaft with isometric-trilateral profile is the largest, namely, the best connection strength.
Piecing of the aluminum alloy A6063-T6 tube was attempted with the help of impulsive water pressure in the tube caused by the impact of drop-hammer. The availability of this approach was investigated. Shapes of the die hole were circular, square and long rectangle. The outer diameter was 40 mm, and the wall thickness was 1 mm. The maximum impact velocity was 10 m·s⁻¹. The pressure at the occurrence of crack was almost same for different impact velocity of the drop-hammer. However, if the number of holes was increased from 2 to 4, all the holes could not be pierced. The circular hole with a diameter of 10 mm and the square hole with an edge length of 10 mm were successfully created. When the size was doubled, the material did not partially separate. The water pressure rapidly increased and crack occurs at around 1 ms depending on the impact velocity. The effect of positive strain-rate sensitivity of the material was observed in comparison with the quasistatic experimental result. Profile of the hole edge was tapered. Burr formation was not observed, which is a significant advantage of this process.
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The assembled camshaft under hydraulic expansion has the advantages of low cost, lightweight and high performance, which is an advanced technology with great development potential. By applying the tube hydroforming to the fabrication of assembled camshaft, the expansion principle is due to the different degrees of resilience of the cam and the shaft. Therefore, the effective detection method of elastic recovery of camshaft is of great significance to research how to improve the connection strength of the assembled camshaft. This paper introduces several springback detection methods for assembled camshaft under hydraulic expansion, namely resistance strain detection method, gap dynamic detection method and finite element simulation.
Virtual technology development for medium-sized companies using the example of hydroforming. Companies do not always have the necessary databases for virtual technology development. Especially small and medium-sized companies often lack the resources to acquire process and profitably use these data sets under production conditions. The derivation of synthetic data sets on the hybrid basis of technological expert knowledge, analytical and empirical calculations as well as numerical simulations and their utilization by mathematical modeling creates intelligent solution approaches with which this so far missing database can be compensated to a large extent. On the basis of a selected component manufactured by the hydroforming process, a methodology for the realization of synthetic data sets will be outlined and its application in quality management and predictive maintenance will be explained.
The precision forming of thin-walled hollow components with the complex surface is difficult due to the excessive thinning of small radius circular arcs and the springback of small curvature surfaces. The difficulty is because the pressure required for forming a small radius circular arc is larger than that needed for other regions, while the pressure supplied inside the hollow blank in a conventional hydroforming process is equal everywhere causing the forming pressure cannot meet the requirements of different deformation regions. To solve this problem, the thin-walled hollow component with the complex surface is formed precisely by employing self-adaptive non-uniform pressure. Herein, theoretical analysis of the self-adaptive non-uniform pressure of viscous medium acting on the blank and the stress distribution of blank during the circular arc filling process is conducted. Then, different viscous medium parameters are employed in the forming of hollow components with different circular arc radii by numerical simulation. The results indicate that the non-uniform pressure is formed during the forming process, and is affected by the mechanical properties of viscous medium. The stress and strain distribution of blank are uniform, as well as the wall thickness thinning ratio and springback are small when the appropriate viscous medium is selected. As an application, the thin-walled hollow turbine blade is manufactured. The wall thickness is uniform and the dimensional deviation is kept at a lower level.
Macro-/meso-scaled tubular structures, as one kind of key high-performance and light-weight structural or functional components for loading carrying, heat and mass transfer with enormous quantities and diversities in geometrical characteristics and material types, have been widely used in many high-end equipments in various industrial fields such as aviation, aerospace,energy transportation and bio-technology. For satisfying the diversy demands of macro-/meso-scaled tubular structures/components in different industrial clusrters, many forming technologies have been developed based on the advanced design methods. This article systematically introduces the common deformation-based materials processing methods for fabrication of macro-/meso-scaled tubular materials including rolling, extrusion and drawing. Meanwhile, some typical forming methods for manufacturing of tubular components such as tube bending, tube joining and tube hydroforming are summarized. Finally, the trends and challenges in macro-/meso-scaled forming of tubular structures/components towards high-performance, light-weight, high-precision, environmental-friendly, and smart and extreme manufacturing are also discussed and elucidated.
This study focuses on the dieless free bulging of thin-walled stainless cylinders closed by two heavy plates. Using the plastic mechanics of shells of revolution and by making several basic assumptions, a family of analytical formulae are derived to evaluate the shell bulging properties such as surface area, internal capacity, thickness distribution, equivalent strain, and bulging pressure. The analytical and numerical data were found to be in good agreement with each other; the results were validated through a free bulging experiments carried out on three nominally identical thin-walled cylinders, which will provide a reference for the manufacture of underwater thin-walled pressure structures.
During tube hydroforming process, the friction conditions between the tube and the die have a great importance on the material plastic flow and the distribution of residual stresses of the final component. Indeed, a three-dimensional finite element model of a tube hydroforming process in the case of square section die has been performed, using dynamic and static approaches, to study the effect of the friction conditions on both plastic flow and residual stresses induced by the process. First, a comparative study between numerical and experimental results has been carried out to validate the finite element model. After that, various coefficients of friction were considered to study their effect on the thinning phenomenon and the residual stresses distribution. Different points have been retained from this study. The thinning is located in the transition zone cited between the straight wall and the corner zones of hydroformed tube due to the die–tube contact conditions changes during the process. In addition, it is clear that both die–tube friction conditions and the tube bending effects, which occurs respectively in the tube straight wall and corner zones, are the principal causes of the obtained residual stresses distribution along the tube cross-section.
The hydroforming of overlapping blanks (HOB) is a novel method that uses overlapping tubular blanks rather than closed cross-sectional tubes to enhance the forming limit. However, the deformation and instability mechanism of HOB has not been elucidated yet. In this paper, theoretical analysis models were developed for the material flow field, the critical wrinkling stress, and the critical supporting pressure. On the basis of it, the HOB approach was performed experimentally and numerically to validate the proposed models, taking a variable-diameter part as an example. A new self-sealing loading tool made of highly elastic material was developed to realize the sealing. The deformation mechanism in HOB was revealed and the occurrence of material flow along the circumferential direction was demonstrated. In addition, the location and the morphology of potential wrinkles were well predicted. Wrinkling defects were prevented effectively by applying the normal load, which was achieved by a sub-plate covered upon the overlap at the outer layer. The comparison of the required internal pressure and the wall thickness distribution was analyzed in the HOB and the THF processes. It is feasible to reduce the forming pressure and the wall thinning using an overlapping blank.
The purposes of this review are to summarize the historical progress in the last 60 years of lightweight metal forming, to analyze the state-of-the-art, and to identify future directions in the context of Cyber-physically enabled circular economy. In honoring the 100th anniversary of the establishment of the Manufacturing Engineering Division of ASME, this review paper first provides the impact of the metal forming sector on the economy and historical perspectives of metal forming research work published by the ASME Journal of Manufacturing Science and Engineering, followed by the motivations and trends in lightweighting. To achieve lightweighting, one needs to systematically consider: (1) materials and material characterization; (2) innovative forming processes; and (3) simulation tools for integrated part design and process design. A new approach for process innovation, i.e., the Performance-Constraints-Mechanism-Innovation (PCMI) framework, is proposed to systematically seek new processes. Finally, trends and challenges for the further development in circular economy are presented for future exploration.
For QSTE700 high-strength steel rectangular welded tube, the mechanical properties of the weld zone vary with the distance from the centerline of the weld. Therefore, the accurate description of constitutive relationship of the weld zone is of great significance for the study of formability of QSTE700 rectangular welded tube. Firstly, the mechanical properties of parent and mixed specimens containing weld zone and parent zone were obtained by uniaxial tensile test. And based on the microhardness test, the width and the microhardness distribution of the weld zone were determined. Secondly, by subdividing the weld zone into several small areas, and combining with the rule of mixtures and nanoindentation test, the continuous functional relationships of strength coefficient K, hardening coeffecient n and elastic modulus E were obtained, and then, the continuous constitutive relationship of QSTE700 rectangular welded tube was established. Finally, the validity and reliability of the continuous constitutive relationship of welded tube were verified by nanoindentation test and rotary draw bending of rectangular welded tube. Besides, it was found that the finite element model of rotary draw bending of QSTE700 rectangular welded tube established by using the continuous constitutive relationship can well simulate the cross section deformation and wall thickness variation.
Tubular components are indispensable in manufacturing industry, but when its size decreases to micro level, the formability of micro tube will become undesirable. To improve the formability of micro tube, this study suggested a novel laser shock hydroforming method. This method used laser-induced shock wave as energy source and liquid as medium to transmit pressure wave. It was the pressure wave that forced the material of micro tube to flow into the die cavity and replicated the shape of that. The dynamic forming process of micro tube was first studied by numerical means, and the numerical results agreed with experimental ones. Then, the middle section thickness of formed micro tube was researched experimentally. The results shown that the uniformity of thickness distribution was improved compared to that in quasi-static condition, and the improvement of that was analyzed by numerical means. In addition, the reason for the increase of formability was investigated in the aspect of contact stress, and numerical results confirmed that the impact of the material of micro tube on the die caused the increase in compressive stress, a phenomenon beneficial to the formability enhancement. Finally, the paper compared the deformation behaviors—deformation velocity and strain rate—with and without a die, proving that the die was one factor that contributed to the formability improvement.
Magyarországon a járműipar a kiemelt stratégiai húzóágazatok közé tartozik, magas hozzáadott értékű, a hazai GDP mintegy egytizedét biztosító tudás-intenzív ágazat. A világméretű globális versenyben az autóipari fejlesztéseket számos, gyakran egymásnak is ellentmondó követelmények határozzák meg. Fogyasztói oldalról a gazdaságos üzemeltetés mellett, a növelt teljesítmény, fokozott biztonság és kényelem igénye a meghatározó, amelyekhez a fokozott környezetvédelem szempontjait tükröző törvényi előírások társulnak. Ezek az összetett követelmények részben összhangban vannak egymással, részben jelentős ellentmondásokat is jelentenek, amelyek kielégítése új anyagok és új eljárások alkalmazását igénylik. A könyv a Járműipari anyag- és technológia fejlesztéseket támogató nemzeti kutatási program (TÁMOP-4.2.2.A) keretében elért eredményeket összegzi.
The article deals with the effects of material properties on forming characteristics during tube nosing and bulging. It is shown that bulging, maximum internal pressure P//m//a//x is influenced not only by the length of tube, but also by the workhardening exponent n. In addition, this workhardening exponent affects the forming limit and strain distribution. Unlike strain distribution, stress distribution is only slightly dependent on the plastic anisotropy r. In order to reduce the necessary force for nosing, it has proved advantagous to employ a raw material with higher n and r values.
This paper reports on a study that investigates the method of applying a thermal load to a cylinder in order to reduce the maximum elastic stress. It is assumed that the cylinder is only subjected to a uniform internal pressure. An analytical method is used for thermo-elastic analysis of the problem. It is supposed that the cylinder obeys the Tresca yield criterion. An optimization procedure is proposed to find the optimum value of the unknown thermal load. Several examples are presented. Obtained results verify the efficiency of the proposed method. Using the approach discussed here, one can easily prevent failure or increase the load capacity of the cylinders under internal pressure.
The idea that in-plane pure shear can be used for reaching “infinite” forming strains is examined via the bulging process of thin walled tubes. The principal stress ratio of −1 (which represents a pure shear) and other negative ratios were attempted by applying simultaneously internal pressure and axial compression in a synchronized fashion. It turned out that bulging of the tubes with negative stress ratios failed by early buckling of the tubes. On the other extreme, tensile dominated bulging failed by diffused (or localized) necking. An optimized loading path for maximizing the bulging strain between the above opposing trends was experimentally explored, guided by a limit analysis formulation. The experiments were done on Aluminum (Al 5052-0) tubes, using a specially-dedicated machine.
Bulge forming has been further applied in the forming of non-axially symmetrical hollow-ware which cannot be produced by spinning or flow forming. The technique is also being applied in an industrial project aimed at developing a process for forming tube joints from flat blanks.
The use of oil as a medium for the transmission of load to work-piece has become more widespread during recent years. In research on sheet metal forming, the hydraulic bulge test has been extensively employed to study the behavior of flat sheet metal subjected to biaxial stresses without the complications arising from friction between metal tool and work-piece. Industrial metal forming processes using fluid pressure for the manufacture of some items of copper plumbing are established.
Application of axial compression during hydraulic bulge forming of tubular components greatly increases the extent of bulging which may be obtained with a given initial wall thickness. Using this technique, Tee-joints and other types of tubular joint are successfully being formed on a commercial basis.
A hydraulic tube-forming machine has been designed and manufactured to investigate the cold forming of axisymmetric and asymmetric components from circular tube. Radial expansions of 50 per cent have been achieved with axisymmetric components, and tee-pieces have been successfully formed in a wide range of materials.
A numerical solution for analysis of the bulging process of a thin-walled tube under internal pressure and axial force is proposed. The solution is applied to a case in which the longitudinal stress resulted from internal pressure and external compressive load is tensile along the whole length of the bulged tube. To verify whether the solution is applicable, theoretical and experimental results on the bulging of copper tubes have been obtained and are compared.
Stress and strain distributions developed in a tube during the tube bending operation is important in estimating the limit bending radii, springback and structural properties of the tube. In this paper, A new strain distribution model for tube bending, considering stretching, circumferential strain and cross section flattening, is presented. The axial, circumferential, thickness and effective strains on the outer surface, inner surface and mid-surface of a bending tube were calculated from grid measurement, and are shown in different ways. Thickness strain was also obtained from thickness measurement. Comparison is made among the results from measurement and modeling and a very good agreement is obtained between the new model and the measurement.
Comprehensive pressure tests have been carried out on thick-walled, closed-ended cylinders made from a mild steel and a hardened and tempered steel, the maximum pressure reached being 94,000 lb/in.2 The complete theoretical behavior of the cylinders is computed from shear stress-strain data obtained from torsion tests and is shown to be in very close agreement with the experimental results. In addition, a method is given for deriving the large strain behavior of the cylinders from tension test data. When compared with the experimental results this approach gives larger errors, the theoretical values of pressure being consistently high. Finally, ultimate pressures have been calculated from two empirical expressions.
Based on the applied maximum tensile force in the necking direction, a general necking criterion for thin shells was developed. The effective strain at necking depends on the prestrain, the strain hardening exponent and the ratio between the two principal stresses at the onset of necking, and does not depend on the strain path. A computer program was developed to determine the bulge shape when load increments are specified on a step by step basis, simulating the whole process until failure.
Data obtained from nearly 100 static cylinder tests under internal pressure have been examined statistically and design formulas proposed for elastic-breakdown pressure and bursting pressure. The formulas are reliable within ± 15 per cent of the observed value on a 90 per cent certainty basis.
The anisotropy of tubular material is assessed from the values of the width/thickness strain ratio determined in the tension tests. Applying Hill's theory of plastic anisotropy, these values are incorporated in the expressions for determining the stress/strain characteristics for anisotropic material in the tension and bulgtests, and also in the theoretical analysis of the hydraulic bulging of anisotropic tubes. Experiments have been carried out on copper tubes. Taking into account the anisotropy effect, the stress/strain curves determined in the tesnion and bulge tests agree closely except at the low strain region. In the analysis of the bulging process, comparison is made between the theoretical and the experimental circumferential strain distribution. The results appear satisfactory.
A hydraulic bulging machine with independent pressure and axial-force control has been designed and constructed. This machine consists of a horizontal press frame with two opposed hydraulic units at the ends of two sliding units carrying the die halves. Two sets of three hydraulic cylinders open and close the die halves containing the tube to be bulged. Once the die halves are closed, two differential pistons operating in two pressure vessels attached to the end plates move in and seal the tube. Then hydraulic pressure is applied to the tube through the central bore of one of the differential pistons. Thereafter, by actuating another hydraulic circuit, the pistons apply an axial compressive force on the tube. During the bulging process, the hydraulic pressure inside the tube and the axial force on the tube can be varied independently. When the bulging is complete, the tube is de-pressurized, the pistons withdrawn, the die halves opened and the bulged tube removed. Initially, a PLC was used to control the internal hydraulic pressure, the axial load, compression of the tube and the operating sequence of the process, but experiments conducted with this control system in place indicated that closer control of the process parameters was needed. Recently, a personal computer together with a data logger was used to monitor the axial force and the hydraulic pressure. Results of the bulging experiments conducted with this set-up are reported in this paper.
This paper represents the structure of a flexible tool system for internal high-pressure metal forming, together with the forming possibilities that it opens up and looks into the results of studies that shows the applicability of the system.
The ultimate strength of thin-walled cylinders, spherical shells and circular diaphragms subjected to hydrostatic pressure is investigated for materials whose strain-hardening characteristics can be fitted by the empirical equation . Experimental values of maximum pressure obtaining in the deforming of circular diaphragms of initially cold-worked materials are shown to be in good agrement with a theoretical treatment by Hill.
Making use of experimentally determined friction-characteristics of urethane under pressure, the initial yield conditions in tube bulging with an internal urethane rod are analyzed. The analysis predicts a neutral cross-section where the urethane friction changes direction. The effects of the tube diameter, the length of the urethane rod, the applied pressure and the material properties on the position of the neutral zone are determined and the effects of various process parameters on the range of stress ratios that exist at initial yield of the tube being bulged are studied, the initial yield conditions predicted by the present analysis being compared with those from an earlier analysis.
Using an empirical friction characteristic for urethane under pressure, an approximate theory for determining the initial yield pressure and the final forming pressure needed on an internal urethane rod to bulge a tube is put forward. The results of experimental investigations agree well with the theoretical predictions for aluminium tubes.
At THD/PtU a manufacturing technique was developed in order to form tubes under internal hydraulic pressure and axial farce. The forming of the bulging tube can be influenced by pressure control. Algorithms can be developed to define pressure depending on the axial force or parameters to that, such as displacement and time.
The most important parameters of geometry and load are recorded during the process.
Most finite element analysis of bulge forming or more specifically bulge testing were done for possible simplest cases. These analyses used pressure as forming load holding the periphery fixed thus involving no contact phenomenon. In real forming cases contact is an essential feature and involves pushing of material into the bulge. Ahmed and Hashmi[4] simulated bulge forming of a circular plate applying pressure on plate surface and inward displacement of the plate periphery in a die configuration. It was observed that the bulge formed by the combined load is higher, has more uniform thickness and has less stress and strain. It is expected that if the bulge is restrained at the polar region rather than allowed to form free, it might result in a bulge with longer cylindrical part which is more desirable from manufacturing point of view. This paper presents the results of simulation of bulge forming by combined load with and without a restraining load and without one. It is found that the bulge formed with a restraining load not only has longer cylindrical part but also has higher bulge height than in that obtained without a restraining load at the polar region. However, the restrained bulge developed more stress and strain but their distribution in the bulge are relatively smoother.
Increasing acceptance and use of hydroforming technology within the automotive industry demands a comprehensive understanding of related issues such as material characteristics, tribology, part and tooling design. Among these issues, characterization and specification of tubular material properties under hydro- forming conditions is the main concern of this paper. Analytical improvements and their comparison with experimental findings on measurement of material properties of tubes under hydraulic bulging conditions are explained. With these improvements, 'on-line' and continuous measurement of flow stress for tubular materials become possible, and are proven to be in good agreement with previous 'off-line' measurements presented by the authors. © 2001 Elsevier Science Ltd. All rights reserved.
A general method of analysis has been formulated for the study of the axisymmetric forming processes of sheet metal. The method involves successive approximations of stresses and strains in the material according to its known stress-strain characteristic and by the application of the plasticity theories. The stresses and strains so determined are correct when they satisfy the equilibrium conditions.In this paper, an application of the method to the hydrostatic bulging process is given. Comparisons are made between the theoretical and experimental results for soft copper and mild steel.
An analytical solution is presented for the bursting conditions of thin-walled cylinders with finite ratios, . The approach is based on the Ludwik strain-hardening law, the Mises effective stress-strain criterion and the total deformation theory of plastic flow. The ends of the cylinder are held against radial growth, but are permitted to translate laterally. Closed-form solutions are obtained on the assumption that the bulged meridional profile can be represented by successively larger circular sections at increasing pressures. Numerical calculations were carried out for varying between 1 and ∞, and for values of the strain-hardening exponent, n, ranging from 0 to 1.0.
Tube material properties are required for accurate design of the parts and tooling for the hydroforming process. Tensile test properties which are obtained using specimens taken from flat sheet prior to roll forming and welding change during the tube manufacturing process. This paper describes a practical test method for determining the flow stress of tube materials. This tool set, a simple stand alone hydraulic bulging fixture, was developed to expand the tubes under bi-axial loading conditions. With the use of this tool, along with analytical methods and finite element simulation, material properties can be determined for tubular workpieces. These material properties are used for subsequent finite element computer simulation of complex components manufactured from the same material. The tooling, designed for this test, may also be used to evaluate the formability and quality of the tubes.
Hydroforming is a method for forming circular metal tubes. If this technology is to be applied economically, it is essential to have knowledge of the avoidance of failure cases as well as of the behaviour of the tube in the tool under the compressive stress and forces that are exerted by the machine. This knowledge marks the underlying basis to specify the process control for hydroforming processes. These correlations are set out in this contribution. It presents proceedings and methods to develop process controls and highlights the significance of process control for the quality of the forming result.
This paper presents a brief overview of developments in bulge forming of tubular components. A theoretical method of estimating the parameters such as internal pressure, axial load and clamping load required for the forming of tubular components as well as for the design of dies and tools is presented. In the discussion typical values of these parameters for particular tube size and material are presented and their implications on the design and operation of the process are noted.
Application of polyurethane to the bulging and piercing of thin-walled tubes
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Comparison between the bulging of thin-walled tubes using rubber forming technique and hydraulic forming process
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The research of tube bulging using polyurethane under compound external forces and its application
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W. Tonghai, S. Sheng, M. Dexiu, The research of tube bulging using polyurethane under compound external forces and its application, Adv. Technol. Plasticity (1993) 494±499.
Theoretical basis and applications of high pressure forming
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Simulation of hydroforming process
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Formability and design issues in tube hydroforming
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THF process overview and applications
- C Bruggeman
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An introduction to recognizing potential applications and product design
- B Longhouse
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Hydroforming - from feasibility analysis to series production
- F U Leitloff
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Tubular hydroforming: ability and flexibility of pressure sequencing
- G Morphy
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Innovational possibilities of internal high pressure forming with superimposed bending stresses
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With water to the shape
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