Billet Size Research Articles

The induction heating process of semi-solid aluminium alloys for thixoforming and their microstructure evaluation

The optimal inductive coil design in the induction heating process of A356 (ALTHIX) alloy billets of 76 mm diameter and 90 mm length to reduce the temperature gradient of the billet and to obtain a globular microstructure was theoretically proposed and tested by reheating experiments. The optimal reheating conditions to apply the thixoforming process were investigated by changing the reheating time, holding time, holding temperatures, capacity of the induction heating system, and adiabatic material size. This study shows that, the larger the billet size, the better the multi-step reheating, and the heating time and the capacity of the induction heating system must be increased. In case of the three-step reheating process, the final holding time is most important factor and 2 min is suitable to maintain a globular microstructure.

Application of neural network and FEM for metal forming processes

This paper proposes a new technique to apply the artificial neural network in metal forming processes. A three-layer neural network is used and a back propagation algorithm is employed to train the network. It is determined by applying the ability of function approximation of the neural network to the initial billets which satisfy the minimum of incomplete filling in the die cavity. The die geometry for cylindrical pulley is designed to satisfy the design conditions of the final product. The proposed schemes have been successfully adapted to find the initial billet size for axisymmetric rib-web product and to design the die geometry for cylindrical pulley. The neural network may reduce the number of finite element simulation for designing the die of forging products and further it is usefully applied to multi-stage process planning.

Preform design of a generic turbine disk forging process

Abstract This work uses the finite-element-based inverse die contact tracking method to design the preform die shapes of a generic turbine-disk forging process. First, for a one-stage forging process, folding defects, extensive flash and underfill resulting from using an improper initial billet size are investigated. Trial forward simulations are performed while varying the height-to-diameter ratio and the optimal aspect ratio of the initial billet for a one-stage forging process is determined. Second, the preform die shapes for a two-stage forging process are designed using the back-stage process. The boundary condition control criterion for the backward simulation is determined by the inverse die contact tracking method. In addition, the optimal ratio of height-to-diameter of the billet is also determined for the preforming stage to achieve a sound preform shape. Finally, the preform design results, including the preforming stage and the final forging stage, are verified by forward simulation. The simulations show that the sequence and newly designed preform die shapes can achieve a net-shape part that avoids the folding defects and reduces the die wear.

Determination of the initial billet geometry for a forged product using neural networks

In the paper, the authors propose a new technique to determine the initial billet geometry for the forged products using a function approximation in neural networks. A three-layer neural network is used and the back-propagation algorithm is employed to train the network. The billet geometry is determined by applying the ability of the function approximation of neural networks to determine an optimal billet which, satisfies the forming limitations; minimises incomplete filling in the die cavity, load, energy; and also secures a more uniform distribution of effective strain. The neural networks are applied to find the optimal initial billet size for a plane-strain rib-web product in cold forging and for an axisymmetric rib-web product in hot forging. The neural networks may reduce the number of finite-element simulation for the determination of the optimal die geometry of forging products and, further, they can be usefully applied in the physical modeling of the forging design.

平角寸法測定装置の開発

In process of pre-finishing and finishing rolling, it is necessary to measure the width and the thickness for the control of roll gap and the quality guarantee of finished products. We have developed the measurement system of hot billet's size using optical instruments. It is possible to control automatically the rolling mill by these systems with a computer and gain the target finished size. We are convinced that these systems will hereafter contribute toward the rolling

Technological study of the roll-forging forming of swords

This paper introduces the advantages of replacing the traditional handwork process to produce swords with the technology of roll-forging forming. The analysis of the technological process of roll-forging forming for the sword is elaborated: producing the forging drawing; selecting the size of the original billet; determining the number of roll-forging passes and the distribution of the deformation in each pass of the process; calculating the billet size in each pass of roll-forging; and drawing the process of roll-forging forming for the sword. In addition, the design of the forming die for each pass of the roll-forging of the sword is introduced. Finally, the technical and economic effects of the new and the old technology for the sword are listed.

Expert system for multi-stage cold-forging process design with a re-designing algorithm

Cold forging has recently become one of the competitive technologies in manufacturing. In order to improve the productivity of cold forging at low production cost, an integrated systems approach is necessary in handling the material preparation and the optimum process design considering the forming machines, tooling, and operation, including quality control. As the first step toward this approach, an expert system for multi-stage cold-forging process design for axi-symmetric geometries with or without a hole in one end has been developed using Prolog language on IBM 486 PC. The system consists of a user interface, a system shell, a material data-base, and a design rule-base. According to the given input data, the system generates the forgeable geometry and the basic process design, depending on the initial billet size and material or the order of upsetting and forward extrusion. In addition, it can provide a flexible process re-design based on either the reduction in the number of forming sequences by combining the possible two processes in sequence, or the reduction of deviation of the distribution and the level of the required forming loads at the last forging step by controlling the forming ratios. The required forming loads and global strain distributions at each step are calculated and displayed on a PC monitor. The designed process sequences can be obtained by AutoCAD or a text file including the dimensions of the drawing. The system developed will be useful in reducing trial-and-error by design engineers in determining the diameter and height of the initial cyclindrical billet from the final product geometry and the intermediate necessary sequences.

High energy physics conductor scale-up progress of the Supercon artificial pinning center process

The Supercon APC process is briefly reviewed. Process parameters requiring optimization for commercial production are discussed. Issues involved in successful monofilament and multifilament billet size scale-up the APC process for HEP composites, nominally 6 /spl mu/m filaments and composite diameters <1 mm, are presented. The Supercon APC composite piece length and mechanical properties are excellent. The present best composite J/sub c/ results are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Results of SSC vendor qualification program at Outokumpu superconductors

Outokumpu Superconductors is engaged as one of the suppliers in the developing of Superconducting Super Collider (SSC) dipole outer cable in the vendor qualification program. In the program, the authors used a billet size of 278 mm in the outer diameter. In phase IB, 15 billets were extruded and drawn down to the final diameter. The phase IA goal was to optimize some production process parameters. In this phase, 18 billets were processed. The wires for the phases IA and IB have been finished, and a summary of the results of phase IB is presented, focusing on the uniformity of quality. Some results of the different optimizing programs of phase IA are presented. >

Comments on the use of the model-material technique in the hot forging of brass

Using the model material technique, it is possible — in a simple and relatively inexpensive way — to avoid defects and unnecessarily large material consumption in hot forging. The tool designer can, by way of experiment, achieve a good cavity shape at an early stage and the process planner can select the correct sequence of operations and billet size before the material has been ordered.

Submicron multifilamentary high performance Nb3Sn produced by powder metallurgy processing of large powders

Powder metallurgy processed submicron multifilamentary Nb3Sn superconducting wires were fabricated starting with 250–500-μm-diam powders. A multiple strand bundling procedure was used to simulate large scale production with actual areal reductions greater than 106 to achieve submicron fibers. Both external tin and tin core processing were successful. Typical Cu-36 wt.% Nb-Sn materials gave overall critical current densities of 8×104 A/cm2 at 12 T, 3×104 A/cm2 at 14 T, and 6×103 A/cm2 at 16 T. These results demonstrate that particle size and billet size can be scaled from earlier laboratory scale to large scale fabrication to produce high performance materials.

The influence of mold behavior on the production of continuously cast steel billets

The origins of rhomboidity, longitudinal corner cracks, and breakouts in the continuous casting of steel billets have been investigated with the aid of heat flow and stress analyses of the mold wall. It has been shown that these problems can be linked to intermittent boiling in the cooling water channel, which may occur asynchronously on different faces of the mold. A mechanism based on asynchronous, intermittent boiling and nonsymmetrical cooling of the mold wall has been formulated which explains the influence of billet size, cooling-water velocity, water pressure, cold face roughness, and steel carbon content on the formation of rhomboidity and longitudinal corner cracks. Prevention of intermittent boiling is thereby shown to be a key factor in the production of defect-free billets. This can be accomplished by raising cooling water velocity, increasing mold wall thickness, increasing water back pressure, or roughening the cold face near the meniscus. These measures should also be effective in reducing the frequency of breakouts beneath the mold.

Prediction of linear noise-load relationship for impact forming machines

INTRODUCTION NOlSE emitted during hot forming on a high-energy-rate-forming (HERF) machine bears a linear relationship with the magnitude of the forming load [ 1]. The existence of this linear correlation has been confirmed for a drop hammer [2] : though the slope and the intercept of the noise-load line differed from the H E R F case. It appears that for every hammer this noise-load relationship can be expected to be unique and independent of the process variables, i.e. input energy, billet size and properties, etc. A linear noise emission vs forming load variation, independent of the process variables, with a unique gradient and intercept for each hammer, could be used as a measure of the overall acoustic quality of the hammer structure. Such a criterion might prove in certain cases to be more meaningful than the conventional power criterion, especially when the prime concern is the avoidance of the operator's hearing damage. Furthermore, such a criterion would be easier to apply than that of the sound power. The present paper contains a theoretical analysis furnishing an explanation of the observed linear noise-load variation.

Die wear characteristics in high speed cropping

The pattern of blade wear arising in a high speed cropping machine when cropping En8, En31 and En2 are discussed. The wear land was found to be “moon crescent” shaped while the wear profile was either of the “crater” or the “triangular” type. The development of these characteristics and that of the wear volume were monitored over long runs and the resulting deterioration of the billet quality was noted. Means for arriving at an “optimum blade life” are proposed and the results obtained are discussed on the basis of that concept. Blade life depends on the materual cropped, billet size and the tolerance limits of billet quality required. Broadly speaking, tool life obtained at high cropping speeds was of the same order as that customary at conventional speeds, through in the former case a far higher billet quality is obtained.

An experimental procedure for studying the flow in plane strain extrusion

An experimental procedure is described for observing the flow of aluminium through near frictionless wedge-shaped plane strain extrusion dies. The selection of the billet size and shape, type of lubrication, die design and photographic grid printing technique are described. It is shown that the use of a square chequerboard pattern of 0.1 mm side enables the flow to be observed in considerable detail and flow fields are given for the extrusion of annealed aluminium alloy 5086 through 15° and 60° half angle dies with 50% reduction in thickness.

連続鋳造における溶鋼の流動現象と非金属介在物について

In order to understand mechanism of entrapment of large non-metallic inclusions in surface layer of continuously cast billets, scheme of molten metal flow in tundish and mold and distribution of large inclusions of billets were investigated.Results obtained are as follows.1) Non-metallic inclusions which become larger up to 1.2mmφ by collision at tubulent zone in mold are mainly entrapped inside of solidified shell. This tendency is especially recognized in case of smaller billet size.2) In order to promote float separation in mold, it is necessary to give a little tubulent zone in mold, to eliminate dead zone of metal flow and to wash out inside solidified shell by high speed metal flow.Especially it is recognized that influence of metal flow pattern in mold by submerged nozzle shape has more considerable effect on decreasing non-metallic inclusions in surface layer, compared with influence of casting speed, tundish metal flow pattern and billet size.

Part family methods for bulk metal forming

Abstract The use of part family or group technology methods for machining operations is well established and several manufacturing systems baaed on this approach are in existence, as well as rationalized and automated procedures for design, process planning, etc. It is less well recognized that a similar approach to metal forming operations can lead to substantial benefits also. In this paper the possibilities for extending this approach to bulk metal forming operations (forging, stamping, etc.)are outlined. In particular systematic procedures for component and die design are described based on classification and coding systems for formed parts. In this context, the selection of forging features (draft, allowances, etc.), billet size estimation, and so on are considered. The use of group die sets, with interchangeable inserts, for families of similar parts is outlined. This technique enables die coats to be substantially reduced thus making forming operations more economically viable for small batches of ...

Case Study in the Rolling of Steel Bars

Some variables affecting the rolling operations of steel bars are discussed, including the effect of bar cross-section variations on length variations. The distribution of bar lengths is obtained from the ratio of billet (inlet) to bar (outlet) cross-sections and the effect of burning losses during the process is studied. It was found that the ratio of bar length to billet length is virtually independent of input length and that the distribution of these ratios is approximately normal. These results were compared with observations of lengths ratio in an experiment, which included various inputs. The lengths ratios distribution and its parameters facilitate process adjustment by an appropriate selection of billet size in order to obtain a desirable mean bar length. They also provide a basis for further analysis of scrap, which occurs when the bars have to be trimmed to specific lengths.