bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of a Novel End-Effector for Kinematic Support in Incremental Sheet Forming
Authors: Brüninghaus Jan , Volfson Yan , Bickendorf Jobst , Brell-Cokcan Sigrid
Published: November 2016

The formability and geometrical accuracy in incremental sheet forming can be increased using a force-controlled support tool. The main problems in using such a kinematic support tool is the positioning of forming and support tools, while maintaining force magnitude and alignment. A new tool for this was developed systematically using a morphological box. It uses a spring controlled rotation of the tool tip to maintain the force. Since the rotation axis is not in line with the tool tip axis and the tool tip can freely rotate around its axis, roll friction conditions can be achieved. The center of gravity of the rotating part of the tool is placed in the rotating axis and the force is therefore independent from the alignment of the tool in space. It has a mechanical stop with locking option in the vertical position and is therefore also fully usable as a forming tool. While the prototype is manually controlled, concepts for a fully automated version have been designed, as well. First tests are in line with results described in literature, showing that direction and magnitude of force have an influence on the formability.
Determination of Processing Windows for the Hot Stamping of AA7075
Authors: Zhang Qun Li , Ji Kang , El Fakir Omer , Liu Xiao Chuan , Wang Li Liang
Published: November 2016

Hot stamping of aluminium alloys is a tailored forming process, with the assigned processing windows determining the quality of each hot stamped component in terms of its post-form strength. In this work, a processing window calculator, ‘Tailor’, was developed in order to define the optimal processing parameters that should be used in a production line to successfully produce a component with the desired post-form strength using hot stamping. ‘Tailor’ was developed using the results of forming tests, air-cooling tests and multi-stage artificial ageing tests, which provided guidance on the values for the die closing force, transfer time and artificial ageing time to be used in the hot stamping process. The effectiveness of ‘Tailor’ was demonstrated in two case studies.
Optimized Cooling Strategies for Bainitic Forging Steels
Authors: Eggbauer Gernot , Buchmayr Bruno
Published: November 2016

New steel grades for forged components are designed to meet the requirements of the automotive industry in order to obtain excellent strength and toughness behavior as well as a high endurance limit. Beside precipitation hardened ferritic-pearlitic steels, bainitic steels have gained more and more importance. Basic considerations on the alloy design (C-, Si-, Cr-; B-content) are done using JMatPro-Calculations and by some experimental trials. Using the thermomechanical testing system Gleeble 3800, various cooling strategies have been applied and the kinetics of the bainite formation has been measured at different holding temperatures and times. A detailed microstructural characterization has been done with relation to the mechanical properties. The isothermal tests are compared to continuous cooling situations. Finally, forging trials are performed to find out the most suitable and robust production schedule to be used in practice. The actual findings support the increasing use of bainitic steels for forged parts, especially regarding material saving, independence of cross section and good fatigue performance.
Prediction of Failure Mode in Hole Clinching of Al Alloy and Advanced High-Strength Steel
Authors: Shen Guo , Lee Chan Joo , Lee Jeong Min , Kang Gil Seok , Park Joon Hong , Kim Byung Min , Ko Dae Cheol
Published: November 2016

Common joining methods used in automotive industry are welding, adhesive bonding, friction stir welding, mechanical fastening, self-piercing rivets, mechanical clinching and so on, for multi-material designed automotive bodies. Among different joining methods, mechanical clinching which achieves geometrical interlocking by plastic deformation has several advantages such as no need of additional joining elements and fast joining. But mechanical clinching is difficult to join a ductile material with a high-strength or low ductility material. Therefore the hole clinching as a new mechanical clinching process has been proposed to join these material combinations. In the hole clinching process, as punch force is applied to a upper sheet (a ductile material), it is indented into hole of lower sheet (low ductile material) on die and then interlocked by plastic deformation. It is very important for a successful design of hole clinching to predict the failure mode such as neck fracture and button separation and the strength of hole-clinched joint. For this an analytical approach was carried out for the hole clinching process of Al6061 and DP980. Tool geometry used in hole clinching was designed by the predicted failure mode. Preliminary finite element simulation was performed to validate the geometrical interlocking and joinability. The predicted failure mode and strength were verified by the results of cross tension test.
The Effectiveness of Cold Rolling for Residual Stress Reduction in Quenched 7050 Aluminium Alloy Forgings
Authors: Pan Ran , Davies Catrin Mair , Zhang Wei , Shi Zhusheng , Pirling Thilo , Lin Jian Guo
Published: November 2016

Residual stresses are often introduced into aluminum alloys through quenching processes performed to generate the required microstructure. Such residual stresses are known to be deleterious to the integrity of the component. Methods to mitigate residual stresses in quenched components are therefore of great importance. Cold rolling has been proposed as an effective technique to remove residual stresses in large components. In this work, the effectiveness of cold rolling in reducing the residual stresses in quenched blocks AA7050 has been quantified using the neutron diffraction technique. Neutron diffraction measurements have been performed on two blocks one quenched and the other quenched & cold rolled block. Comparing the residual stress distributions pre and post rolling it has been found that cold rolling almost eliminates the tensile residual stresses in the core of the block, however it generates large tensile residual stresses d in a shallow region near the surface of the block.
A Fast Three-Dimensional Model for Strip Rolling
Authors: Overhagen Christian , Mauk Paul Josef
Published: November 2016

Rolling Models have come a long way from the first empirical relations about forward slip and bite conditions to their current state, which allows local quantities to be calculated in two and three dimensions. In this paper, state-of-the-art of analytical modelling of the rolling process is shown with a fully three-dimensional rolling model for hot and cold strip rolling with stress distributions in the longitudinal, vertical and lateral directions. For this purpose, von Karman’s strip approach is extended to account for the stress gradient in lateral direction, as was already shown in different papers. The stress gradient in the vertical (through-thickness) direction is introduced by a modern implementation of Orowan’s inhomogeneous deformation theory. The local stress distributions are compared to results from Finite-Element Calculations obtained with modern FEM codes. It will be shown, under which circumstances expensive FEM calculations can be replaced by simpler models like the one proposed here, which are more time and cost-effective without a significant loss in result precision. The rolling model is extended with a Finite Element Beam Model for work and backup roll deformation, as well as local work roll flattening and thermal crown for hot rolling. The Effects of those features on stress distribution and exit strip profile are shown for hot and cold rolling.
Analysis of Void Closure during Open Die Forging Process of Large Size Steel Ingots
Authors: Harris Nathan , Shahriari Davood , Jahazi Mohammad
Published: November 2016

Large size forged ingots, made of high strength steel, are widely used in aerospace, transport and energy applications. The presence of internal voids in the as-cast ingot may significantly affect the mechanical properties of final products. Thus, such internal defects must be eliminated during first steps of the open die forging process. In this paper, the effect of in-billet void positioning on void closure throughout the ingot breakdown process and specifically the upsetting step in a large ingot size steel is quantitatively investigated. The developed Hansel-Spittel material model for new high strength steel is used in this study. The ingot forging process (3D simulation) was simulated with Forge NxT 1.0® according to existing industrial data. A degree of closure of ten virtual existing voids was evaluated using a semi-analytical void closure model. It is found that the upsetting process is most effective for void closure in core regions and central upper billet including certain areas within the dead metal zone (DMZ). The volumetric strain rate is determined and two types of inertial effects are observed. The dependence of void closure on accumulated equivalent deformation is calculated and discussed in relation to void in-billet locations. The original combination of information from both relative void closure and the volumetric strain rate provides a way to optimize the forging process in terms of void elimination.
A New Approach for Void Closure in Bulk Metal Forming
Authors: Kittner Kai , Wiesner Janine , Kawalla Rudolf
Published: November 2016

At present, the discussion about pores/ voids in large ingots is still actual. Researchers investigated the closing behavior during the open die forging process. Mostly, the approaches take the account into void closure with artificial pores. But artificial pores do not reflect the real closing behavior. This is caused in the surface/ structure of inner voids. During drilling and heating, the voids got a smooth surface and have contact to the atmosphere. Therefore, the material oxidizes on surface and the closing behavior is not similar to the real process. Real pores show a fractal surface with dendrites. And the inner of voids contains a vaccum. In the framework of a new approach, for void closure cast ingots with pores were generated and the structure and the closing behavior were investigated.The final goal is to find out a global closing function “Z”. This closing function should improve the understanding of void behavior and in the future the industrial process. The function depends on different parameters, like yield strength of material (Pkf), the pore size (AEq), the pore structure (Pstruct) and process parameters (Pproc), such as tool geometry or bite ratio. Finally, there is a parameter Pdisturb. This parameter works against the final closure and is important for the understanding of the process, because it represents the influence of dendrites. Furthermore the closing behavior is not comprehensible without the consideration of recrystallization.
Computer Simulation of Transformation during TRIP Steel Rod Drawing
Authors: Konstantinov Dmitriy , Bzowski Krzysztof , Korchunov Aleksey , Pietrzyk Maciej , Kuziak Roman
Published: November 2016

Axis pins, shafts and other rod-like parts are some of the main components of units and machines. They are manufactured from steel rods ranging from 7 to 60 mm in diameter after single-pass drawing. Unalloyed carbon steel grades are generally used to produce these items. TRIP steels application is advantageous in terms of achieving new properties when manufacturing steel rods. The initial billet size, the need to take account a transformation in TRIP steel microstructure and a great number of analysed technological conditions make it challenging to apply new materials into rod drawing process. The research aim is to explore the stress-strain state during rod drawing of steel TRIP700. Modified multiscale computer simulation method has been applied. The simulation method takes into account transformation of retained austenite into martensite during plastic deformation. Decreasing of the computational resource intensity and calculation time has been achieved by application of concept of Statistically Similar Representative Volume Element (SSRVE). Comparative analysis of rod drawing micromodels with and without the TRIP-effect simulation has been performed. The analysis showed that a values of equivalent strains in the deformation zone of a TRIP-ignored micromodel was three-four times lower than in a TRIP-factored micromodel. The analysis of simulation results has revealed that, due to a wide contact area with adjacent grains and interaction between microstructure elements, more intensive martensitic transformation occurred within larger grains of retained austenite. The micromodel shown that position and orientation of grains in the deformed TRIP steel microstructure are some of the factors that predetermine transformation of retained austenite. On the basis of simulation results recommendations on preparation of rod drawing conditions have been developed. Developed technological conditions provides ability to obtain: high-plasticity characteristics and high potential strain-hardening capability during exploitation of a future part; maximum strengthening throughout the cross-section of the rod after drawing; high strain-hardening of the surface layer only. The using of SSRVE concept reduced a number of elements within the micromodel in 20 times, while it lowered the calculation time in 16 times.
Crack Formation and Propagation Mechanism in the Punching Process of High Tensile Strength Steel Sheet
Authors: Okano Takehiro , Sakumoto Kota , Yamazaki Kazuhiko , Toyoda Shunsuke , Suzuki Shinsuke
Published: November 2016

The microstructure (crystal grain and the center segregation of Mn) around the voids and cracks in punching process was investigated using Hot-rolled 780 MPa-grade high tensile strength steel sheets. Steel sheets without center segregation were prepared by grinding only one side, while ones with center segregation were prepared by grinding both side. Punching tests were conducted with these two kind of steel sheets. Crack length and number of cracks on the punched surface were measured and counted by an optical microscope. Steel sheets with center segregation had more cracks in total and longer average crack length than that without center segregation. The Mn mapping and the crystal orientation mapping around the crack obtained through EPMA and EBSD showed that the range larger than 70 µm in crack length tend to cause intergranular fracture along Mn segregated area. Also in the range between 10 µm and 70 µm in crack length, cracks forming both along and away from Mn segregated area were observed. Concentration of Mn around the grain boundary of the center segregation area measured by TEM/EDS revealed that grain boundary contains high Mn concentration. The calculation on distribution of equivalent stress just before the onset of crack for steel sheets with and without center segregation using finite element model showed that equivalent stress concentrates at both edges of the punch and die and the center segregation part. Next, interrupted punching tests were conducted with two kind of steel sheets. The observation around voids through SEM, EPMA, and EBSD showed that voids initiate at the ferrite-Ti precipitate interface. From these results, following tendencies were found, within and near Mn center segregated area, voids initiate at the ferrite-Ti precipitate interface, and crack propagates along Mn center segregation. Moreover, Mn segregates at the grain boundary, and Mn weakens grain boundary cohesion which leads to an intergranular fracture. However, without Mn center segregated area, voids initiate at the ferrite-Ti precipitate interface, and crack propagates easily into the ferrite matrix by cleavage which leads to cause a transgranular fracture.
Elastic-Plastic Thermomechanical Fatigue Analysis of Forging Dies
Authors: Vlasov Andrey , Biba Nikolay , Stebunov Sergey
Published: November 2016

Abrasive wear and low cycle fatigue (LCF) have the greatest influence on the durability of dies. This paper presents a new criterion for estimation of the LCF of forging dies. The deformation model of Manson-Coffin is the classic model for the calculation of LCF. The pulsating cycle of loading dies and the phenomenon of cyclic thermal softening doesn’t provide implementation of the full Manson-Coffin’s model for the analysis of the tool life. At the same time the majority of researchers do not take into account the plastic strain component for estimation the fatigue durability of the dies and use only elastic component of the Manson-Coffin’s law or model of Basquin that is based on the analysis of the stress cycle. The present work uses the strain-kinetic criterion to analyze the durability of the dies that allows taking into account the elastic-plastic strain components and thermos-cyclic softening. During loading in bulk forging the first cycle is to be with plastic deformation while all remaining cycles would have to remain within the elastic limit due to metal hardening. Moreover it has been shown that cyclic softening effect may also be observed in the thermomechanical fatigue. This approach has been implemented for LCF simulation of the die in hot forging in FE program QForm by introducing a special subroutine. The comparison of results of the die fatigue failure simulation has shown good correspondence with practice.
Feasibility Study of Complex Sheet Hydroforming Process: Experimental and Modelling
Authors: Mohamed Mohamed , Carty David , Storr John , Zuelli Nicola , Blackwell Paul , Savings David
Published: November 2016

The application of finite element method (FEM) in the area of metal forming and material processing has significantly increased in the recent years. The presented study provides details of the development of a finite element modelling approach to form a part via sheet hydroforming (SHF) process. Both FEM analysis and experimental trials were introduced in this study to produce a complex shape component from Inconel 718 material. The FEM provides a robust feasibility study for forming this part in terms of blank design, load path and process design optimisation. The simulated hydroformed part was validated by performing experimental trials. The analysis demonstrated close correlation between the predicted FE model and the physical trial.
Finite Element Simulation of Shear Strain during High-Ratio Differential Speed Rolling of Aluminum Alloy 5083
Authors: Pesin Alexander , Pustovoytov Denis
Published: November 2016

High-ratio differential speed rolling (HRDSR) is a process of severe plastic deformation (SPD) that can be used to improve the structure and properties of aluminum alloys. The mechanism of SPD during HRDSR comes from its large equivalent strain, which is composed of compressive strain and additional shear strain. Plastic strain control of aluminum alloys are of importance for improvement of sheet microstructure and properties. This paper presents the results of the finite element simulation of shear strain during high-ratio differential speed rolling of aluminum alloy 5083. Four deformation routes UD, TD, RD and ND were simulated. By the route UD the sheet was not rotated between two deformation steps, while by the other three cases it was rotated with 180° degrees. By the route RD the rotation axis was the rolling direction, by the route TD the transverse direction and by the route ND the normal direction. The effect of rolls velocity ratio, friction coefficient and deformation route on the shear strain and the effective strain of Al 5083 was found. The results of investigation can be used to optimize the high-ratio differential speed rolling process to improve microstructure and mechanical properties of aluminum sheets.
Influence of Die Geometry on Drawing Force in Cold Drawing of Steel Tubes Using Numerical Simulation
Authors: Bella Peter , Buček Pavol , Ridzoň Martin , Mojžiš Milan , Parilák Ľudovít
Published: November 2016

In Železiarne Podbrezová, cold drawing process is the final process in production of precision seamless steel tubes. This particular technology utilizes multiple drawing sequences and intermediate annealing. From the physical point of view, it is nothing just the optimal use of plastic deformation during cold forming that grants the final tube dimensions. The drawing process itself is significantly affected by physical and metallurgical properties of the tube, the tool geometry, the lubrication, and the sequence of operations. This paper deals with the relationship between the tool geometry and the drawing force. The FEM-based numerical model of the process was prepared in DEFORM 3D in order to optimize the geometry of the die; eight die geometries were investigated in total. The numerical simulation itself considered a hot rolled hollow at Ø32 mm × 4 mm, cold drawn into Ø25 mm × 4 mm using die drawing (sinking) sequences only. Calculated drawing force showed that the change of the run-in angle of the die led to a decrease of the drawing force.
Investigation into the Numerical Model Behaviour of Belleville Washers in Cold Roll Forming
Authors: Tsang Kwun Sing , Ion William , English Martin
Published: November 2016

With the steady increase in demand for roll formed products, due to their application in fields such as automotive, construction, architecture, etc., roll forming companies are challenged with rising customer demands. Companies are struggling to bring a product through from design to manufacture at improved rates, whilst achieving tighter tolerances. The roll forming process may also induce undesirable forming defects such as twist, distortion and straightness problems. Over the years, numerical simulations have been deployed to assist with the geometric validation of these effects. For the purpose of this paper, an investigation shall focus on an individual parameter within the finite element analysis of the cold roll forming process, i.e. the ’unknown’ spring effect acting of the top roll during the forming process due to the implementation of Belleville washers in the pillar set up. This parameter is assessed over a range of applied loads and compared with a standard friction model with fixed top and bottom rolls. The longitudinal strains on the final profile, the geometric accuracy and thickness variation are observed and presented in this paper. Reasoning is also provided to explain why the final profile bows in the vertical direction.
Supercritical Debinding of Environmentally Friendly Inconel 718 Feedstock to Metal Injection Moulding Process
Authors: Royer Alexandre , Gelin Jean Claude , Barrière Thierry
Published: November 2016

In the MIM process the debinding is a long, complicated and polluting step. The supercritical fluid debinding is a new method to reduce the time of debinding, the default of the pieces and the pollution. The goal of this study is to study the behaviour of an environmentally friendly feedstock of Inconel 718. For this, a binder formulation based on polyethylene glycol, because of is water debinding properties, and bio sourced polymer was made. Polylactic acid was investigated as bio sourced polymer. The debinding is realized with supercritical CO2 as solvent. The results were compared to the traditional debinding method using water at 60°C.
Unconventional Methods of Sintering Inconel 718 MIM Samples
Authors: Dugauguez Olivier , Torralba Jose Manuel , Barrière Thierry , Gelin Jean Claude
Published: November 2016

In this investigation, three different ways of sintering Inconel 718 MIM samples are compared. The conventional way of sintering in a furnace will be compared to FAHP and microwave sintering. The difficulty of these two methods is to be able to control the shrinkage of the sample and so its shape. These methods have yet not been investigated with a super alloy powder and so, the effects of a high sintering rate on a MIM sample. By accelerating the sintering kinetics, the thermal behavior may be modified. Hence, the behavior of the Inconel 718 sintered by field assisted and microwave sintering has been investigated. The sintered samples were all injected from a feedstock composed of a fine particle Inconel powder and a binder principally composed of CAB and PEG. They were debinded into water for 24h and put in a furnace at 500°C during 2 hours. The heating rate of the furnace was set to 5°C/min until 1290°C during 2 hours. The heating rate of the FAHP was set to 50°C/min until 1250°C during 15 minutes. The microwave samples were sintered around 1300°C during 1 hour, the temperature was increased progressively by steps of 100°C. The effects of the different process on the microstructure and the mechanical properties are then compared. There was no difference in distribution of pores between the conventional sintering and the FAHP sintering but a finer grain size showed better hardness. The microwave sintering of a MIM sample is more complex and the best properties were not obtained.
A Review of Microstructure and Microtexture of Tertiary Oxide Scale in a Hot Strip Mill
Authors: Yu Xiang Long , Jiang Zheng Yi , Zhao Jing Wei , Wei Dong Bin , Zhou Ji
Published: November 2016

In hot rolling, metal oxides formed on steel surface can generally be classified as primary, secondary and tertiary oxide scales, corresponding to the reheating stages, the roughing stages and the finishing passes of continuous mills, respectively. The tertiary oxide scale grows into the final products on the hot-rolled steel strip during the finishing rolling and the subsequent cooling down to ambient temperature. We provide here a systematic overview of the oxidation mechanism, microstructure and microtexture development of the tertiary oxide scale. Mechanism of oxidation and Fe3O4 precipitation in tertiary oxide has been given as the fundamental theory. Three main sections has been divided in this review. The first section includes experimental investigations on microstructure evolution from the formation of oxide scale during hot rolling, then through continuous cooling, to Fe3O4 precipitation behaviour in storage cooling of hot-coiled strip. By using electron backscatter diffraction (EBSD) to characterise both the steel substrate and the oxide scale concurrently, the second section has further dealed with the texture-based analysis of oxide scale: phase identification, orientation analysis and coincident site lattice (CSL) boundaries. The third section has provided the general type of crystallographic texture and its evolutions in deformed Fe3O4 and steel substrate. Finally, the upcoming challenges have been addressed in this intriguing and promising research field.
Deep Drawing of One-Sided, Stiffness Increasing Sheet Metal Composites
Authors: Hofmann Dennis , Liewald Mathias
Published: November 2016

Hybrid sheet metal composites do show advantages compared to monolithic materials when strength, stiffness, and damping characteristics are set to a global optimum. Even though the mechanical properties of hybrid sheet metal composites have been improved in recent years, the application of such hybrid materials in the automotive industry is not well-established due to insufficient knowledge about their forming characteristics (e.g. in deep drawing process). Stiffness increasing composites consist of two metal sheets and a viscoelastic damping layer in-between: the outer sheet reveals stamped beads which increases stiffness of composite while the inner sheet serves as cover sheet. This paper deals with challenges of formability of stiffness increasing composites in industrial deep-drawing processes. The main concern is dimensional stability and accuracy of those layered materials after finishing the forming process. In order to ensure accuracy of formed parts, a methodology was developed for increased quality of sheet metal composites. Depending on the drawing limit ratios and blankholder forces, which evaluate the drawability of component in general, the drawing limit ratio is influenced for profound or insufficient residual bead heights and widths. Besides insufficient bead height, which causes a reduction in moment of inertia, inner marks on the visible outer sheet hamper a broad application in practical use. Finally, paper provides detailed recipies for manufacturing and tool layout for deep drawing objectives of such composite material.
Influence of Geometrical Shapes and Sheet Thicknesses on the Dimensional Accuracy of Single and Assembled Parts
Authors: Konrad Tobias , Schöllhammer Steffen , Roll Karl , Merklein Marion
Published: November 2016

Based on elastic stress and strain states after forming and joining processes, single and assembled parts show deviations regarding their dimensional accuracy. Therefore an analysis of selected influencing factors and their influence on the dimensional accuracy of assembled parts is performed in this paper. In this article a novel approach is presented that characterizes the impact of three geometrical shapes (convex/concave/straight) and different sheet thicknesses on the dimensional accuracy along a linked forming and joining process chain. The process chain consists of a deep drawing and a clinching process. Depending on sheet thickness, material and geometrical shape, the dimensional accuracy of single parts and joined assemblies varies.
For the single parts the geometry of the specimen S-rail is used. Several types of assemblies are used for the proposed approach combining this specimen with a plane sheet or a second S-rail. The FEM-tools LS-DYNA and Abaqus, are used to demonstrate this approach. Simulations and experiments with aluminum alloy 6014, mild steel CR3 and sheet thicknesses of 0.7, 1.0 and 2.0 mm are conducted for single and assembled parts.
In summary, a significant improvement of the dimensional accuracy of an S-rail assembly is demonstrated using two non-dimensional accurate single parts. Future work will be to analyze frequently occurring part segmentations for the joining technologies and to optimize material mix and sheet thicknesses in order to improve deviations of the assembly to the nominal CAD geometry.
Stability of a Suppression Method of Dent and Spring-Back in Zigzag Bending of Sheet Metal/Plate
Authors: Kuboki Takashi , Yamada Takuma , Kajikawa Shohei , Abe Hiroyuki
Published: November 2016

This paper focuses upon zigzag-shape bending for suppression of defects, including dent and springback. A series of finite element analyses was carried out in order to optimize the bending condition for suppression of these defects. As a result, it was clarified that a diagonal movement of the upper die was effective for suppression of dents while a rather vertical movement of the upper die was effective for suppression of springback. In order to suppress dent and springback at the same time, this paper proposes another method of bending method, whereby the upper die with special shape moves in a diagonal way. Moreover, the stability of the method against variation of tool dead position, which would be caused by elastic deformation of supporting members, was studied by FEM, followed by experimental verification.
Studies on the Hot Forming and Cold-Die Quenching of AA6082 Tailor Welded Blanks
Authors: Liu Jun , Wang Ai Ling , Gao Hao Xiang , El Fakir Omer , Luan Xi , Wang Li Liang , Lin Jian Guo
Published: November 2016

An advanced forming process involving hot forming and cold-die quenching, also known as HFQ®, has been employed to form AA6082 tailor welded blanks (TWBs). The HFQ® process combines both forming and heat treatment in a single operation, whereby upon heating the TWB, it is stamped and held between cold tools to quench the component to room temperature. The material therefore undergoes temperature, strain rate or strain path changes during the operation. In this paper, a finite element model (FEM) was developed to investigate the formability and deformation characteristics of the TWBs under HFQ® conditions. Experimental results, i.e. strain distribution, were used to compare and validate the simulation results. A good agreement between the experiment and simulation has been achieved. The developed temperature, strain rate and strain path dependent forming limit prediction model has been implemented into FE simulation to capture the complicated failure features of the HFQ® formed TWBs. It is found from both experiment and simulation that the forming speed has important effects on the occurrence of failure position, where the failure mode for the 1.5-2 mm TWBs may change from localised circumferential necking to parallel weld necking.HFQ® is a registered trademark of Impression Technologies Ltd.
The Influence of Strain Rate and Strain on the Behavior of Stress Relaxation in 980 MPa-Grade Dual Phase Steel Sheets
Authors: Murasawa Kodai , Komine Hayato , Otake Yoshie , Sunaga Hideyuki , Takamura Masato , Ikeda Yoshimasa , Suzuki Shinsuke
Published: November 2016

The specimens (980 MPa-grade dual phase steel sheets) were stretched until the pre-defined strain was obtained. Then the specimens were held at the pre-defined strain and measured the change of stress durng holding. We investigated the effects of strain rate and strain at the starting time of holding and whether the stress change during holding could be described by Krempl model. The following results were obtained. First, the stress drop increased with increase of strain rate and the holding time. On the other hand, the stress drop was not affected by strain change at the starting time of holding. Second, initial stress relaxation rate increased with increase of strain rate. However, this strain rate dependency to stress relaxation rate diminished as the holding time became long enough roughly more than 100 s. Third, the stress change during holding obtained by Krempl model accurately agreed with experimental result. It was found that the stress change during holding could be well described by using Krempl model. This suggests that dislocation moves viscously. In addition, the strain rate dependency on stress change during holding could be described by change of the parameter A.
Investigation about the Oil Pressure Rate in the Warm Hydroforming of an Al-Mg Alloy Component
Authors: Palumbo Gianfranco , Piccininni Antonio , Guglielmi Pasquale , Piglionico Vito , Sorgente Donato , Tricarico Luigi
Published: November 2016

In this work, the hydroforming process in warm conditions was used for manufacturing an Al-Mg alloy (AA5754) benchmark component displaying different strain levels due to its geometry. The attention was focused on the effect of the rate to increase the forming pressure (PR), strictly related to the strain rate the material is subjected to. In fact, preliminary tensile and Nakajima tests (both at room temperature and in warm conditions) revealed that the mechanical and formability properties of the investigated alloy are strongly affected by the strain rate. Warm Hydroforming tests were conducted in order to investigate both the working temperature and the parameter PR. The Blank Holder Force profile was varied according to an experimentally determined profile able to avoid oil leakages. Experimental results were collected in terms of output variables related to the die cavity filling and to the strain level reached on the component: in such a way a multi-objective optimization could be carried out using the commercial integration platform modeFRONTIER. The best compromise between the high level of the component deformation and the cycle time could be obtained by conducting the warm hydroforming process at the temperature of 250°C and setting the parameter PR equal to 0.1 MPa/sec.
Design of Injection Mold and Research of Process for Plastic Parts Based on CAE Analysis
Authors: Jiao Dong Mei , Deng Fang , Yang Wei Min
Published: November 2016

The injection molding of plastic parts was simulated and analyzed by MOLDFLOW. Based on the result of mold flow analysis, we can optimize the structure of the mold, select equipment, determine parameters of process, and predict potential defects. The CAE technology could improve mold design ability, shorten plastic parts development cycle, improve the quality of plastic parts, reduce costs, and strengthen competitive power.
Study on Carbon Nanotube Dispersion Behavior in Epoxy Resin under Synergistic Effect of Continuous Stretching Flow and Ultrasound Oscillation
Authors: Dai Kun Tian , An Ying , Jiao Zhi Wei , Zhuang Jin Yu , Qin Yong Xin , Ding Yu Mei , Yang Wei Min
Published: November 2016

In this paper, carbon nanotubes (CNTs) dispersion behavior in epoxy resin under synergistic effect of continuous stretching flow and ultrasound oscillation was studied. A small continuous stretching machine which could provide continuous stretching flow for polymer was designed and manufactured for studying the synergistic effect of continuous stretching flow and ultrasound oscillation on dispersive property. Firstly, the influence of different initial phase angle of dual rotor and mixing time on dispersive property were studied by preparing specimens of CNTs/epoxy resin composite under continuous stretching machine. Then, the synergistic effect of continuous stretching flow and ultrasound oscillation on dispersive property was studied with various ultrasonic power and synergistic time. In this study, the morphology of blends was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that initial phase angle of dual rotor and mixing time had great effect on the dispersion of CNTs in epoxy resin. The degree of CNTs dispersion was best when the initial phase angle of dual rotor was 0°, and increasing mixing time could improve the degree of CNTs dispersion. Increasing ultrasonic power and synergistic time were helpful to disperse CNTs in epoxy resin. It demonstrated that the synergistic effect of continuous stretching flow and ultrasound oscillation had obviously effect on the dispersion of CNTs.
Experimental Study on Self-Made Similar Material of Soft Rock
Authors: Li Jian Guang , Wu Yang , Wang Yong Yan , Qin Nan , Wang Wei Xing
Published: November 2016

Similar material of soft rock used at domestic and abroad are analyzed and compared and researched the advantages and disadvantages of them. Self-made similar material of soft rock mixed with cement, plaster mixed mortar as a cementing agent and sand, rubber powder as aggregate were analyzed and compared. After analyzed multi physical and mechanical characteristics, different ratios of specimens were verified by adjusting the ratio of different materials in similar material to obtain the ideal similar material of soft rock. It was provided reference for similar material model experiment of soft rock.
Effect of Rotation Speed and Discharging Temperature on SSBR-Silica Interaction
Authors: Liu Ji Wen , Zhuang Tao , Yu Guang Shui , Zhao Shu Gao
Published: November 2016

The effects of rotor speed and discharging temperature on silica 1165MP-SSBR 5025-2 interaction as well as the mechanical properties and dynamic viscoelasticity are investigated in this work. The result shows that the discharging temperature increases linearly with increase of rotation speed, leading to increase of bound rubber content. The tensile strength, elongation at break and tear strength increase firstly, and then decrease with increase of rotation speed. However, the strength at 100% and 300% deformation decrease, and then they increase. The wet skid resistance of SSBR5025-2 filled with silica 1165MP improves with increase of rotation speed and discharging temperature, and the rolling resistance decreases.
Study on the Reinforcement of ZDMA in EPDM
Authors: Guo Shang Zhen , Zhuang Tao , Luan Xiao Fang , Zhao Shu Gao
Published: November 2016

We researched the reinforcement effect of commercial Zinc methacrylate (ZDMA) on ethylene propylene diene monomer (EPDM), ZDMA was added to EPDM directly with hakke internal mixer. The mechanical properties, SEM, RPA and FTIR were synthetically used to study the reinforcement effect, compared with the reinforcement of CB N330. The results showed that the reinforcement effect of ZDMA on EPDM was better than that of CB N330. The tensile strength of vulcanizate with ZDMA was up to 17MPa, and the elongation at break was 493%. It could possess great resilience under the condition of high hardness. After adding ZDMA, the processing fluidity and crosslink density of EPDM were improved.
Studies on Mechanical Properties and Dynamic Performance of SSBR/CB/Silica Composites
Authors: Liu Wei , Li Lin , Han Bing Kai , Zong Cheng Zhong
Published: November 2016

Carbon black ( CB ) and silica were used as two-component fillers to enhance the practicability of rubber. In this study, the microstructure, mechanical and dynamic properties of solution-polymerized styrene-butadiene rubber ( SSBR ) vulcanizates filled with carbon black and silica were characterized. 50 phr of total hybrid fillers was used as the base. A series of experiments with different ratios of CB/silica were carried out to determine the best contribution to the performance of SSBR vulcanizates. The studies have shown that when the vulcanizates exhibited the better overall mechanical and dynamic performance with 20 phr silica loading and 30 phr CB loading.
Thermal Performance of a Shape-Stabilized Phase Change Material Floor with Different Heating Positions
Authors: Zhang Bin , Sun Qin He , Liu Wei Tong
Published: November 2016

An effective method to reduce energy consumption for heating a building is by incorporating shape–stabilized phase change material (SSPCM) in building floors. In this study, a new type of SSPCM with increased thermal conductivity is formulated through a self–established experimental device. A model to analyze the thermal performance of the SSPCM floor is developed. The model is used to analyze the thermal performance of the SSPCM floor with two heating positions, one at the bottom and the other in the middle of the SSPCM. Results show that when the heating position is in the middle of the SSPCM, the melting speed is faster and the melting degree of SSPCM is larger than when it is at the bottom.
Research on the Passenger Car Tire Retreading Technology and Processing
Authors: Fu Ping , Zhao Xiao Peng , Su Xiao Feng , Yan Hao
Published: November 2016

Tire retreading refers to the waste tire repair, polishing and gluing, pressing process, and then curing,which restore its use value. So far it is one of the most direct and most effective and the most economic way of the utilization of waste tire. Normally, because of the high profit, the retreading of truck tire and engineering tire had received much attention, while that of passenger car tire had been ignored. However, as the number of car has been increasing for many years, the passenger tire retreading is urgently needed. In this article, after the further study of related retreading theory, it is determined by using the prevulcanization retreading technology for renovation of radial tire. The renovation process including the carcass of tire inspection, repair, polishing, brush glue, tread molding (including post pad, pre vulcanized tread and pressed), vulcanization, final inspection. And the related equipment has been developed for the passenger tire retreading molding, include lifting inspection machine, model profile grinding machine, winding machine, model setting vulcanizing machine and tread of orientation of short fiber extrusion and other special equipment. This research solved the problem of backward technology, the short service life and poor quality.
The Numerical and Experimental Research of Impacts that Shearing Action and Stretching Action of Open Mill Mixing Have on Rubber Mixing Properties
Authors: Bian Hui Guang , Tian Xiao Long , Pan Yi Ren , Xu Xiao Lin
Published: November 2016

In the process of open mill mixing, the rubber material is mainly affected by shearing action and stretching action. In order to research the impacts that shearing action and stretching action have on the final mixing properties of rubber, firstly, the mill mixing process was simulated and calculated by PLOYFLOW software in the paper, and worked out the magnitude of shearing action and stretching action under different mixing conditions; then tested the properties of different kinds of mixing rubber which were mixed under different mixing conditions of open mill; finally, worked out the impacts which shearing action and stretching action have on the properties of mixing rubber by comparisons of the result of simulation and of the properties of mixing rubber.
Study of Grinding Hardening Force Based on the Influence of Grinding Arc Temperature and Workpiece Deformation
Authors: Zhang Ying , Meng Xian Ju , Yuan Zheng Jun
Published: November 2016

The grinding hardening workpiece deformation caused by high temperature leads to the variation of the grinding force. Grinding force of dynamic variation affects the grinding depth of hardened layer distribution. So it is necessary to study the variation rule of grinding hardening force. Through grinding arc temperature analysis and deformation analysis, the influence factor for grinding arc temperature and workpiece deformation on grinding force is analyzed. The analysis results are compared with the experimental results.
Effects of Si Addition on the Microstructure and Tensile Property of Al-xMg Alloys with Al2Ca during Heat Treatment (x: 5 and 7 Mass%)
Authors: Ha Seong Ho , Yoon Young Ok , Kim Shae K.
Published: November 2016

Effects of Si addition on the microstructure, fluidity and tensile property of Al-5/7mass%Mg alloys with Mg+Al2Ca master alloy as Mg raw material were investigated in this study. With 7 mass%Si addition, the fluidity was remarkably improved in both Al-5Mg and Al-7Mg alloys. With increasing the Si content, the amount of the eutectic phases was increased in the microstructures. As a result of the tensile test, there was a drastic reduction in elongation with increasing Si content. Al-5Mg-7Si alloy showed a significant improvement of strength after solution heat treatment and artificial aging.
Investigation of Phosphorus-Containing Compounds in Aluminium Alloys with Emphasis on the Formation Mechanism
Authors: Komarov Sergey , Kazuki Miyamoto
Published: November 2016

It is well known that the presence of phosphorus in hypoeutectic Al-Si alloys causes coarsening of Al-Si eutectic even when the phosphorus concentration is as low as a few ppm. The reason is that phosphorus reacts with aluminum to form AlP, the particles of which serve as potential nuclei for silicon due to a very similar lattice parameter with Si. The purpose of this study is to investigate the possibilities for reducing the nucleation potency of AlP by changing the alloy chemistry. The experiments include melting and solidification of a number of aluminum alloys under different conditions. After that, the samples are examined using SEM and TEM microscopy to elucidate the presence of phosphorus-containing compounds and to explain their formation mechanism. The experimentally obtained data are discussed on a systematic basis of thermodynamic calculations and compared with the corresponding data from the relevant literature. Particularly, the results reveal that such elements as Mg, Ca and Sr are potentially capable of neutralizing the nucleation activity of AlP although their effect is dependent on the presence of other chemical elements in the aluminium alloy.
Effects of Si Content on the Tensile Strength and Machinability of Al-Mg-Si-Cu-Mn-Cr Alloys
Authors: Xing Jie , Owada Yasuyuki , Anami Toshiya
Published: November 2016

This study investigated the effects of the Si content on the tensile properties and machinability of 6xxx−series aluminum alloys for application in hydrogen container valve housing. Four types of extruded Al−Mg−Si−Cu−Mn−Cr alloy specimens with different Si contents of 0.6−3.0 mass% were prepared. The effects of the Si content on characteristics such as microstructural features, tensile strength, and drill machinability were examined and compared with those of a commercial A6061 alloy. These specimens were found to exhibit different microstructures, tensile strengths, and chip segmentation behaviors after T6 heat treatment. These results were attributed to the interaction of the amount of second phase particles and solid-solute Mn and Cr with changes in the Si content.