Rigid-plastic FEM Research Articles

Numerical Simulation of Continuous Extrusion Extending Forming under the Large Expansion Ratio for Copper Strip

Continuous extrusion under the large expansion ratio is an advanced forming process for manufacturing copper strip, preventing mould structure, die structure, expansion chamber structure and the shape of the billet section is important process paraments of deformation. Based on the characteristic of the forming process, the model of rigid-plastic FEM on DEFORM-3D is established and the numerical simulation of continuous extrusion forming process of the copper strip is carried. The metal flow regularity and the mean-square deviation of velocity with the different process paraments is analyzed. As the result, when using the drum form of preventing mould with promote flow angle and the die with variable calibrating strap, the mean-square deviation of velocity is 0.58. When the second extending angle is 134°, the mean-square deviation of velocity is 0.23. When size of billet is 30 x 1.64 mm2, the mean-square deviation of velocity is only 0.19.

A Single Stage Hot Forging Process of Alternator Poles

Based on precision forging method, a single stage hot forging process of alternator poles is put forword, which the heated blank can be forging by only one press in a special closed die. In the last this process is verified by the software of Deform-3D which is employed rigid-plastic FEM method.

3-D Finite Element Simulation of the Vertical-Horizontal Rolling Process

In order to investigate the deformation behavior of a plate during a vertical-horizontal rolling process, a thermo-mechanical coupling analysis is carried out by three-dimensional (3-D) rigid-plastic FEM to simulate the process. The metal flow and the shape evolution of the plate are focused during this investigation. The thickness and the width of the plate agree well with the measured values.

선박용 과급기 타이타늄합금 압축기휠의 열간단조 공정설계

Hot-forging process and die design were made for a large-scale compressor wheel of Ti-6Al-4V alloy by using the results of 2-D FEM simulation. The design integrated the geometry-controlled approach and the processing contour map based on the dynamic materials model and the flow stability criteria. In order to obtain the processing contour map of Ti-6Al-4V alloy, compression tests were carried out in the temperature range of <TEX>$915^{\circ}C$</TEX> to <TEX>$1015^{\circ}C$</TEX> and the strain rate range of <TEX>$10^{-3}s^{-1}$</TEX> to <TEX>$10s^{-1}$</TEX>. In the die design of the compressor wheel using the rigid-plastic FEM simulation, forging dimensional accuracy, the capacity of the forging machine and defect-free forging were considered as main design factors. The microstructure of hot forged wheel using the designed die showed a typical alpha-beta structure without forging-defects.

The Theoretical and Experimental Research on the Forward Slip Coefficient in Rail Universal Rolling

In rail universal rolling, the forward slip coefficient is one of the most important parameters. For simplifying the analytic model, the vertical roll with box pass has been simplified as an equivalent flat roll firstly. Then the equation of neutral line and the area of forward slip zone on the flank of horizontal roll have been derived. Furthermore, the horizontal resultant force acting on the rolled workpiece has been obtained and the forward slip coefficient of rail universal rolling has been proposed. For verifying the theoretical model, the universal rolling process of 60 kg/m heavy rail and 18 kg/m light rail have been simulated by the Rigid-Plastic FEM software DEFORM-3D V5.0, and the universal rolling experiments of 18 kg/m light rail has been accomplished in the Yanshan University Rolling Laboratory. Moreover, the theoretical results and numerical simulation results of forward slip coefficient are in agreement with the experimental data basically. So, this theoretical model can be applied in rail universal rolling.

An analytical model for the prediction of cross-section profile and mean roll radius in alloy bar rolling

In a round-oval-round pass rolling sequence, the cross-section profile of an outgoing workpiece was predicted first after getting the maximum spread. The concept “critical point on the contact boundary” was proposed and the coordinates of the critical point were solved. The equivalent contact section area was represented and the mean roll radius was determined. The validity of this model was examined by alloy bar rolling experiment and rigid-plastic FEM simulation. Compared with the existing models, the mean roll radius obtained by this model is similar to experiment data.

Meshless method analysis of metal forming process based on consistent radical basis function

Since the radical basis functions satisfy the kronecker δ property, the velocity boundary condition can be employed directly. The polynomial functions can be accurately reproduced through the coupling of the polynomial functions into the radical basis function approximation. The meshless Galerkin method is introduced into the metal forming simulations. A meshless Galerkin method based on the consistent radical basis function approximation is developed under the hypothesis of the rigid plastic theory. The volume strain rate projection method is used to deal with the incompressibility constraint. An arctangent frictional model is used to impose the frictional boundary condition under the local coordinate system. In this way, the meshless simulation of the metal forming processes with arbitrarily shaped die is realized. Several typical metal forming processes are analyzed by using the method developed. The effectiveness of the method is demonstrated through the comparisons of the simulation results with those obtained by using rigid plastic FEM method and experiments data.

Simulation of 3-D Deformation and Material Flow During Roll Forging Process Using System of Oval-Round Groove

Basing on the analysis of the traits of the roll forging process, a system-model of computer simulation has been established. Three-dimensional rigid-plastic FEM has been used for the simulation of the deformation process in the oval and round pass rolling, including the entering, rolling, and separating stages. The analysis was conducted using the Deform-3D ver.5.0 code. The important information concerned with the deformation area characteristic, material flow, and velocity field has been presented. Otherwise, the location of the neutral plane in the deformation area was shown clearly.

Hot Forging Comparative Analyses by Using a Combined Finite Element Method

In this paper, single action die and double action die hot forging problems are analyzed by a combined FEM, which consists of the volumetrically elastic and deviatorically rigid-plastic FEM and the heat transfer FEM. The volumetrically elastic and deviatorically rigid-plastic FEM has some merits in comparison with the conventional rigid-plastic FEMs. Differences of calculated results for the two forging processes can be clearly seen in this paper. It is also verified that these calculated results are similar to those of the conventional rigid-plastic FEM in comparison with analyses of the same numerical examples by the penalty rigid-plastic FEM.

A Study on Development of Forming Roller for Miniature Metal Balls Manufacturing Process

According as the demand of miniature metal balls of various diameter increases, processing property and a variety of coverage are important. In this study, especially an optimal groove design of cutting roller was investigated for determining size and shape of metal ball in the manufacturing system. The effects of radius of the groove and radius of the knife-edge of cutting roller and the speed of roller as process parameters were calculated and analyzed. We applied data of rigid-plastic FEM Simulation with DEFORM3D and ANSYS in basic design of equipment to solve these issues, and checked processing parameter about metal balls manufacturing process that use cutting process of metal wire stock in this research. This paper deals with the new improved process of producing miniature STS316L steel balls continuously. Our first goal is to develop a much more efficient equipment and a much more economical production process

Deformation characteristics of Au wire bonding

Abstract In wire bonding, the quality of the bonding between the Al film and the Au wire has an effect on productivity and reliability. It is required to reduce the bonding area to as small as possible without deteriorating the level of bondability to increase the level of integration. The effect of capillary tip shape on bonding was investigated by deformation analysis of the Au ball by the rigid-plastic finite element method and by experiments. The flow stress of Au wire for the numerical analysis was evaluated by conducting the tensile test of Au wire at an ambient temperature of 250 °C. The mean radii and the amount of sliding for the bonded areas were evaluated with respect to the radius of the compression-bonded ball as a parameter under three conditions of capillary tip angle θ : θ = 45°, 60° and 30°. Bonding can be achieved when the amount of sliding is 0.01–0.05 μm or greater. With decreasing the capillary tip angle θ , the amount of sliding tends to increase. The amount of sliding can be controlled by changing the tip shape of the capillary. The results of deformation analysis and experiments on Au ball deformation indicate that the evaluation of the relationship between the shape of the capillary and bondability can be carried out by rigid-plastic FEM. This method used here is effective for determining the optimum bonding conditions and the proper shape of capillaries.

파이프를 이용한 플랜지의 성형특성에 관한 연구

This study is aimed to find out the optimal forming conditions by comparing and analyzing material flow, deformation pattern, and a forming load through rigid-plastic FEM for a flange using pipe. Flanges are widely used for various purposes as connectors of industrial steel pipes which are manufactured by drawing process. The forming feature of flange was reviewed through both heading process and radial extrusion process in a cold working condition. As a result of simulation, the shape of flange can not be made by heading process, but made by radial extrusion process. The effects of design factors, such as gap-height, die-comer radius, and frictional factors on maximum forming load and deformation pattern are investigated for radial extrusion process.

Design and modification of tool to manufacture rectangular cup of Ni-MH battery for hybrid cars

Abstract The shape of rectangular cup of Ni-MH battery which is one of the electric power supplying parts of hybrid cars looks quite simple, but process and tool designs to product the rectangular cup are a little too hard to achieve. Some researches for sheet metal deep drawing process have been performed on the formability of a rectangular Li-Ion battery container for mobile phone. However, there are few concrete reports on the rectangular container as part of vehicles. In this study, tool design for rectangular cup in multi-stage deep drawing process is carried out using the result of FE analysis. This study identified such unfavorable mechanism in deep drawing for rectangular section with ironing and proposed a new tool design of the process through numerical simulation of drawing and ironing process with the thickness control of each wall of the deep drawn cup. Numerical simulation incorporated brick elements for a rigid-plastic FEM with an explicit time integration scheme. The results of FE analysis with the improved tool design confirmed not only reducing thinning of that wall and possibilities of failure but also improving the quality of drawing product through the modification of tools.

Numerical simulation of three-dimensional bulk forming processes by the element-free Galerkin method

A new approach for simulating three-dimensional (3D) bulk metal forming processes is proposed by combining element-free Galerkin method (EFGM) with the flow theory of 3D rigid-plastic/viscoplastic mechanics. Different from the conventional rigid-plastic FEM, the velocity field is constructed by the moving least-squares (MLS) approximation. Special emphasis is placed on the treatments of essential boundary conditions, incompressibility constraint and friction boundaries. The stiffness equation for the analysis of 3D bulk metal forming using EFGM is derived and its key algorithms are given. To test the validity of the proposed meshless approach, a typical 3D upsetting forming process is analyzed and the numerical results are compared with those obtained by commercialized rigid-plastic FEM software Deform3D. As results show, when handling 3D plastic deformations, the proposed approach eliminates the need of expensive meshing and remeshing procedures unavoidable in conventional FEM, and still provides results that are in good agreement with finite element predictions.

An Analysis on the Force Requirement of Combined Operations for Forward and Backward Tube Forming

In the present study, the finite element analysis has been conducted to investigate the deformation characteristics of forward and backward can extrusion process using AA 1100 aluminum alloy tubes in terms of maximum forming load and extruded length ratio in a combined material flow. A commercially available code is used to conduct rigid-plastic FEM simulation. Hollow tubes are selected as initial billets and the punch geometries follow the recommendation of ICFG. Selected design parametrs involved in simulation includes punch nose radius, die corner radius, frictional condition, and punch face angle. The investigation is foucused on the analysis of deformation pattern and its characteristics in a forward tube extrusion combined simultaneously with backward tube extrusion process main in terms of force requirements for this operation according to various punch nose radii and backward tube thickness. The simulation results are summarized in terms of load-stroke relationships for different process parameters such as backward tube thickness, die corner radii, and punch face angle, respectively, and pressure distributions exerted on die, and comparison of die pressure and forming load between combined extrusion and two stage extrusion process in sequencial operation. Extensive analyses are also made to investigate the relationships between process parameters and extruded lengths in both forward and backward directions. It has been concluded from simulation results that a) the combined operation is superior to multi-stage extrusion process in sequential operation in terms of maximum forming load and maximum pressure exerted on die, b) the length of forward extruded tube increases and that of backward extruded tube decreases as the thickness ratio decreases, and c) the forming load is influenced much by the thickness ratio and the other design factors such as die corner radius and punch face angle does not affect much on the force requirement for the combined extrusion process.

Computer Modeling of Extrusion by the Rigid-Plastic Hybrid Element Method

In this paper, a rigid-plastic hybrid element method is formulated, which is a mixed approach of the rigid-plastic domain-BEM and the rigid-plastic FEM based on the theory of slightly compressible plasticity. Since compatibilities of velocity and velocity's derivative between adjoining boundary elements and finite elements can be met, the velocity and the derivative of velocity can be calculated with the same precision for this hybrid element method. While, the compatibility of the velocity's derivative cannot be met for the rigid-plastic FEMs.

A New Analytical Model for the Calculation of Mean Roll Radius in Round-oval-round Alloy Bar Rolling

In rod (or bar) rolling process, the roll surface is not flat for the groove on the roll, so the roll radius is not constant along the roll axis direction. In this paper, a suitable spread formula was determined to calculate the maximum spread of alloyed steel, then the surface profile of outgoing workpiece and the critical point on the contact boundary has been predicted. Furthermore, the formula of the equivalent contact section area has been proposed and the mean roll radius has been obtained.The validity of the new model has been examined by the bar rolling experiment and the rigid-plastic FEM simulation. Compared with the existing models, the mean roll radius obtained by the new analytical model approach the experiment data more closer than other models. So, it can be used as a available reference in practice and the theoretical derivation.

A Design of Manufacturing Processes for Valve-Spring Retainer Component

New manufacturing processes for a valve-spring retainer (VSR) are proposed by replacing the initial solid billet for commercially available thick-walled pipes. The rigid-plastic FEM has been applied to simulate the conventional five-stage manufacturing process for VSR component. The existing process includes mainly backward extrusion and heading operations. A process design methodology is proposed and applied for the analysis. The process design criteria are the maximum force requirement within the available press limit, and the material saving by reducing the wastes from the process. As a result, several simulations of one-step process from selected stocks to the final product shape are performed for a possibly better process than the conventional one. Statistics among different processes are summarized and compared each other in terms of number of required operations for final product, forging load, material waste, number of individual die, process time, and even the possibility of fracture during service. Experiment also has been conducted to ensure that the proposed one-step process is safe operation without geometrical defects.

Research on simulation and prediction of extrusion defects of automotive parts

Taking the forming processes of half-shaft bushing, wayshaft, and starter socket as examples and aiming at the typical problems in extrusion of automotive parts, some defects such as folding, underfilling, and cracking were numerically simulated and predicted in this paper with rigid-plastic FEM, rigid-viscoplastic FEM, and thermo-mechanically coupled methods by means of DEFORM3D. The distribution laws for the stress, strain, velocity, and temperature in the forming processes were analysed. The reasons for the defect generation were discussed, and some optimum measures for these processes were put forward. The results agree well with the experiments. Several proposals for prediction and simulation of extrusion defects of these automotive parts are put forward. It was instructional to apply FEM to the quality control of the extrusion.

1925 3次元剛塑性有限要素法によるネジ転造シミュレーション(S19-3 構造物の変形強度解析,S19 材料の非弾性変形とそのモデル化)

1925 3次元剛塑性有限要素法によるネジ転造シミュレーション(S19-3 構造物の変形強度解析,S19 材料の非弾性変形とそのモデル化)