Billet Shape Research Articles

Design of a High Performance Predictive Tool for Forging Operation

This paper presents a comparative study of different artificial intelligence techniques to model and optimize a particular manufacturing process known as forging. The present work aims to reduce energy, load and material consumption satisfying at the same time constraints on product quality. A flywheel is considered as specific case study for the investigation. The size of the billet used in the forging process will be optimized so that the molds are correctly filled, and waste, forging load and energy absorbed by the process are minimized. More in particular, the shape of the initial billet is a hollow cylinder and the parameters to be optimized are the billet dimensions (inner diameter, outer diameter and height) and the friction coefficient. The analytical relationship between input and output values will be identified in order to choose the optimal process configuration to obtain the desired output. The input-output relation was mapped with different techniques. First of all a Genetic Algorithm-Neural Network and a Taguchi-Neural Network approach are described where genetic algorithm and Taguchi are used to optimize the neural network architecture. The other techniques are support vector regression, fuzzy logic and response surface. In addition a support vector machine approach was used to check the final product quality.

CAE Analysis on the Precision Forging of Big Semimonocoque of Vehicle Axle

A CAE analysis on the precision forging of big semimonocoque of vehicle axle was conducted based on DEFORM-3D software. It discussed effects of forging billet size and shape on the forging property and effect of forging shape on the flow law of metal materials, and analyzed equivalent stress, strain distribution and load-stroke curve during the forging process. Research results are used to optimize mold structure and technological parameters. Precision forging of big semimonocoque was verified valid by practical production.

The prediction of the evolution of grain size of land-gear forging during the die-forging process

The land-gear forgings are the most important structure parts, made of high strength steel 300M. Because of the bad service environment, the microstructure and performance of the part are very strict requirements. In this article the evolution of grain size during the die-forging process is predicted, the volume fraction of dynamic recrystallization, grain refinement and development of grain size in-homogeneity, and the affection of billet shape on the grain size distribution are analyzed. The simulated results show that the grain size differences on the different billet positions are very large at the deformation beginning. But in final forging stage, the difference of the average grain size is smaller. At some center zones of the part the maximum difference of grain size is bigger than 100 μm.

Research of Anti-Extrusion Process for Cylinder of Spray-Formed Ultra-High Strength Aluminum Alloy

Anti-extrusion process for the cylinder of spray-formed ultra-high strength aluminum alloy is researched in this paper. The spray-formed 7xxx aluminum alloy is treated by a two-step homogenization treatment (440 °C / 12h + 472 °C / 24h) after hot isostatic pressing (HIP), and then hot compression tests are carried out for getting the stress-strain relationship under different forming conditions. Anti-extrusion process for the cylinder is improved including changing the shape of mould and billet, and numerical simulation is used for researching the anti-extrusion process. According to the distribution of strain-effective, it can be seen that the improved scheme of anti-extrusion process can get more deformation than the common scheme at the bottom. The result of anti-extrusion experiments shows that the microstructure is evenly distributed across the cylinder under the improved scheme.

Improvement of helical surfaces machining

The article content is focused on helical surfaces processing, as well as automation of production through the use of CAD systems. There was examined the problem of securing workpieces, and shown the dependence of the method of basing from the way of processing and shape of billet.

Route Effects in I-ECAP of AZ31B Magnesium Alloy

An AZ31B wrought magnesium alloy was processed by incremental equal channel angular pressing (I-ECAP) using routes A and BC. Despite the fact that the measured grain size for both routes was very similar, the mechanical properties were different. Tensile strength was improved using route A comparing to route BC, without ductility loss, while tension-compression anisotropy observed for route A was significantly suppressed when using route BC. Moreover, billet shape evolution resulting from subsequent passes of I-ECAP was studied. Significant distortion after processing using route BC and no occurrence of such effect for route A were observed. Results of a finite element analysis showed that non-uniform strain rate sensitivity might be responsible for different billet shapes. The conclusion is drawn that processing route has a strong influence on the billet shape and mechanical properties when processing magnesium alloys by I-ECAP.

Green manufacturing process for helical pinion gear using cold extrusion process

In this research, a cold extrusion process that can replace conventional machining process is developed for sustainable production. The cold extrusion method requires an analytical design process to assure desired dimensional accuracy of the final product. Therefore, the design must consider the material flow during the process in order to avoid product defects such as folding and underfilling. The forming load and material flow were analyzed using a commercial finite element code, DEFORM3D. To improve the dimensional accuracy, the shape of die and initial billet were designed using minimum distance analysis via FE simulation. Also the developed process included ejection for improving dimensional accuracy, and it was verified by a gear accuracy test. Isothermal annealing and spheroidizing were applied for increasing the formability of high strength workpiece. Finally a helical pinion gear was manufactured using the developed process and the product was compared to the simulation results. In conclusion, the developed process is a scrap reducing and energy saving method for manufacturing extrusion product with high dimensional accuracy.

Numerical study of the friction effects on the metal flow under local loading way

Friction plays an important role in bulk metal-forming process. Especially, it has an important influence on metal flow in the local loading process. In the present study, the influence of friction on the metal flow in local loading forming process of rib-web component was analyzed by using analytical method, numerical simulation, and experiment. Constant shear friction model was employed in the analytical analysis and numerical simulation. Two kinds of local loading experiment were carried out, which differ in the shape of billet. The results in the present study indicated that (a) in local loading state, increasing friction is beneficial to reduce or avoid the occurrence of shearing deformation behavior; (b) the metal flowing into rib cavity would increase if friction factor increases; (c) as the width of local loading increases or thickness difference of variable-thickness region decreases, the friction effect will reduce.

The Numerical Simulation of Multi-Directional Forging 6700 Steering Knuckle

The numerical simulation of multi-directional precise contour forging of 6700 steering knuckle was studied in this paper. A 3D thermodynamic coupling finite element method (FEM) was established for each process of the deformation, based on the rigid-viscoplastic finite element method FEM. The results showed that the shape and size of the blanking billet can be optimized and the materials utilization ratio and the dimensional accuracy can be increased dramatically by using multi-directional precise contour forging

Preform design for large-scale bulkhead of TA15 titanium alloy based on local loading features

Large-scale TA15 (Ti–6Al–2Zr–1Mo–1V) titanium alloy bulkhead is a key lightweight load-bearing structure part in an aircraft, which has a large plane view and has a complex shape with high ribs and thin webs. In its forging process, the forming defects, such as folding and under-filling are prone to occurrence. The near-net shape forming with saving force of this large-scale complex component can be realized with proper preform design combining local loading condition. By analyzing isothermal local loading process characteristic of large-scale bulkhead, it indicates that the simple unequal-thickness billet is suitable for small lot manufacture of large-scale TA15 titanium alloy bulkhead. Considering the geometry and forming characteristics, such as large dimension, complex shape, mass data, etc., a design method of unequal-thickness billet using analytical analysis and numerical simulation is proposed. The preform for a large-scale TA15 titanium alloy bulkhead is designed by the proposed method. The basic three-dimensional shape of billet is determined by the analytical models based on local loading features, and the basic billet is modified according to numerical simulation result and considering the local loading forming characteristic, and then the preform without resulting in folding and under-filling can be obtained after two modifications.

Numerical and Experimental Studies on Extrusion of Fan-Shaped Shell of Magnesium Alloy

This paper presents a case study of optimizing the forming process for a fan-shaped shell component. Numerical simulation was used to study the backward extrusion process of a fan-shaped shell. The underfill defect produced at the opening of the extruded shell due to the billet shape was solved and the minimal base thickness required to avoid the presence of the underfill defect at the bottom corner of the component was defined through the numerical simulation. The extrusion drawing and forming process of the fan-shaped shell were designed on the basis of the results of the numerical simulation. Forming experiments had been performed on the fan-shaped shell at 380 °C and cracking was found on the outside wall in the center of the extruded shell. Choked groove on the inner wall of the die and reducing the lubrication had been used to avoid the presence of cracking. The fan-shaped shell of AZ31 magnesium alloy has been successfully formed by the three-stage forming process of hot upsetting, hot backward extrusion and cold sizing.

가상모델로부터 산출된 응력 등가정하중을 이용한 금속 성형품 및 단조품의 형상최적설계

본 논문은 응력 등가정하중을 이용하여 금속제조공정에서 원하는 성형품과 단조품의 최종형상을 얻기 위한 형상최적화 방법을 제안한다. 성형품의 최종형상은 블랭크의 형상에 따라 달라지고 단조품의 최종형상은 빌렛의 형상에 따라 달라진다. 따라서 원하는 형상의 제품을 얻기 위해 구조최적화방법 중형상최적화방법을 적용하였다. 금속성형 공정은 비선형 동적해석을 수행하므로 등가정하중법을 이용한다. 등가정하중법 중 가상모델을 이용한 응력 등가정하중은 등가정하중을 산출하는 새로운 방법으로 재료 특성의 가치를 재정의하여 응력 등가정하중을 계산한다. 본 논문에 포함된 예제를 통해 원하는 제품의 최종형상을 얻기 위한 최적의 블랭크 및 빌렛 형상을 도출하여 제안한 방법의 유용성을 검증한다.

Application of thermohydrogen processing to Ti6Al4V alloy blade isothermal forging

Application of thermohydrogen processing to Ti6Al4V alloy blade isothermal forging is researched in this paper. The basic properties relating to hot workability of unhydrogenated and hydrogenated with 0.25wt%H Ti6Al4V alloys are investigated. Isothermal compression tests are used for getting the stress–strain relationship under different forming temperature, and the mechanism of hydrogenation inducing Ti6Al4V alloy softening is researched. The billet shape is optimized by DEFORM-3D software, then force and flow condition are analyzed in the isothermal forging process. The results show that the qualified blades can be forged under the isothermal forging conditions of 0.1mm/s, 1223K for unhydrogenated alloy and 1123K for hydrogenated alloy. After vacuum heat treatment at 973K for 4h, the experiment's results of mechanical properties show that thermohydrogen processing improves the mechanical properties of the blade at both room and high temperature.

Billet Optimization for Steering Knuckle Using Taguchi Methodology

In the present scenario of competitive production, Computer Aided Engineering (CAE) techniques have been applied with great success in metal forming research especially in the cold, warm and hot forging areas for meeting customer expectations. There is growing demand for more efficient and economic manufacturing process to reduce production cost, increase productivity, and reduce lead time and to improve product quality. The traditional forging die design procedure depends upon costly, tedious and time consuming shop floor trials before achieving final acceptable product. More difficulty is experienced when design requirements are stringent and die profiles are complicated. To overcome this problem, computer based simulation technology has come and brought some benefits for optimizing forging processes. In this paper, Taguchi optimization methodology is applied to optimize design parameters for steering knuckle die. Taguchi offers a simple and systematic approach to obtain optimal settings of the design parameters for steering knuckle die. The design parameters evaluated are flash thickness, flash land and billet shape each at three levels. To obtain the results the forging process was modeled (Catia 3D modeling software), simulated (Deform 3D forging simulation software) and examined using Taguchi's L 9 orthogonal array.

Automatic Optimization Techniques Applied to a Large Range of Industrial Test Cases

The use of material processing numerical simulation has spread widely in recent years in the engineering industry. It allows a strategy of trial and error to improve virtual processes without incurring material costs or interrupting production and therefore save a lot of money. On the other hand, it requires user time to analyze the results, adjust the operating conditions and restart the simulation. Automatic optimization seems the perfect complement to simulation. Evolutionary Algorithm coupled with metamodelling makes it possible to obtain industrially relevant results on a very large range of applications within a few tens of simulations and without any specific automatic optimization technique knowledge. In the frame of the LOGIC ANR French project, ten industrial partners have been selected to cover the different area of the mechanical forging industry and provide different examples of the forming simulation tools. An optimization module, fully embedded within the Forge2009 IHM, makes possible to cover all the defined examples, and the use of new multicore hardware to compute several simulations at the same time reduces the needed time dramatically. The presented examples demonstrate the method versatility. They include billet shape optimization of a common rail and the cogging of a bar.

Modeling the Deposition Dynamics of a Twin-Atomizer Spray Forming System

A numerical study of the deposition dynamics of twin-atomizer spray-forming of large-diameter billets is presented with a focus on the coupled effect of the twin-atomizer scan frequency and substrate rotation frequency. The common period of the two frequencies ξ was the dominant parameter to govern the deposited droplet mass and billet shape. When ξ ≥ 10, a uniform mass distribution at the deposition surface was predicted, and the calculated shape agreed with experiments.

Construction of a composite model of decreasing flow stress scale effect

Based on the composite model of polycrystalline plastic deformation, a new composite model was built, with which the relation of flow stress to grain size, dimension and shape of the billet can be well explained. Through the comparison of this model with experimental data and the surface layer model, its rationality was testified. Based on this model, with the definition of scale effect factor, the decrease of flow stress in micro scale was discussed and predicted, and conclusions were drawn as below: with the downscaling of billet dimension, the decrease of flow stress is gradually increased; with the increase of grain size, the decrease of flow stress is also gradually increased; the shape of billet has a significant influence on the decreasing flow stress scale effect.

ИсслЕдованиЕ процессА равнОканальнОгО Т-ОбразнОгО прессованиЯ МетодоМ конечныХ элементоВ

Исследованы особенности течения и напряженно-деформированного состояния материала при равноканальном Т-образном прессовании методом конечных элементов. Показано влияние таких факторов как трение и упрочнение материала на форму, распределение деформаций, силовой режим при прессовании заготовки.

New methods of rolling and straightening rails from continuous-cast billet at OAO NKMK

The structure of rail steel is mainly determined by the temperature and deformation in rolling. The required deformation conditions over the profile from the initial blank to its final cross section are ensured by the groove structure and configuration in the system. The grooves determine the stress‐strain state and physicomechanical properties of the rolled metal. Therefore, rail manufacturers pay particular attention to the groove configuration, which is fundamental to the rolling process. In this context, it is important to establish the change in shape of continuous-cast billet in rail rolling. In the present work, we analyze the change in shape of the metal in the rolling grooves during rail production from continuous-cast billet and improve the rolling technology developed for rail production from ingots.

Melting Mechanism of Water-Cooled Billet-Type Bottom Electrode of Direct Current Arc Furnace: A Numerical Approach

The direct current (DC) furnace, the earliest type of the electric arc furnace (EAF), was popularized at the end of the 1980s. Even in its heyday, there were always doubts about its superiority due to some imperfections of the DC furnace (e.g., the problems of the bottom electrode system). The water-cooled billet electrode, which is classified as one of the four types of the bottom electrodes, has been in use for more than two decades. However, so far its melting mechanism has not been well understood. A sophisticated numerical model was thus constructed by coupling the heat transfer and the fluid flow, and taking into account the electromagnetic effect as well as the influence of the gap between the billet and the copper jacket. The observed phenomena could readily be explained using the model. The computed results show that the axial component of the electromagnetic force plays an essential role in driving the strong flow within the electrode hole, and that the Joule effect does not contribute the majority of the heat taken away by cooling water. An important conclusion is reached that there is a double-edged effect by changing the billet diameter. Accordingly, a modification of the billet shape is suggested, i.e., a diameter-variable structure, which should greatly assist in improving the thermal state of the billet.