• Transactions of Materials Processing
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• v.4 no.4
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• pp.322-334
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• 1995

This study presents development of an expert system for process and die design of hot extrusion through square dies. The design of extrusion dies is still an art rathere than a science with increasing complexity of shape and thinness of section. Therefore, most of the die design is still dependent on personal judgement, intuition and experience. The objective of this study is to develop an expert system which includes a rule base system extracted from literatures and experts in the extrusion industry. The system also includes finite element simulation program. The developed system is effectively used to design two types of processes and dies with lead time and trial extrusion.

• Transactions of Materials Processing
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• v.19 no.7
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• pp.399-404
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• 2010

We propose an analysis model for simulating the detailed procedure of pore closing in open die forging of shafts. In the analysis model, an artificial symmetric plane is used, on which initial pores are located to be traced. The analysis model is employed to carry out three-dimensional simulation of pore closing in shaft free forging by both conventional free forging press and radial forging machine. With this result, two typical types of free forging equipment for manufacture of shafts are compared in detail. It has shown that the radial forging machine is much superior to the conventional open die forging press especially in pore closing under high hydrostatic pressure with sound strain.

• Transactions of Materials Processing
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• v.26 no.6
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• pp.372-377
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• 2017

In this paper, an effective design procedure was proposed to design the rib of die structure for auto-body member with ultra-high strength steel (UHSS) having ultimate tensile strength (UTS) of 1.5 GPa. From analysis results of the die structure, structural safety of the die was evaluated with information such as displacement and von-Mises stress. It was concluded that the casting part could be designed in order to reduce tool deformation. A design guideline of the die structure was proposed, especially for the rib structure in the casting part with an optimization scheme and local reinforcement concept. Simulation result following the design guideline fully explained that stability of the tool structure could be obtained simultaneously with weight minimization.

• Journal of the korean Society of Automotive Engineers
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• v.11 no.4
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• pp.35-42
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• 1989

The major purpose of this paper is a study on the effect of die profile radius on the formability of spring-type blankholder system in deep drawing process. By drawing the various materials, formability is studied by means of checking the drawing force, blankholding force variation, limiting drawing ratio and wall wrinkling phenomenon. As the die profile radius increases, the maximum drawing force and maximum blankholding force decrease regardless of lubrication condition. Because better lubrication induces blankholding force to rise, spring type blankholder system is better to protect flange wrinkling phenomenon than constant pressure type. And wall wrinkling phenomenon was not detected in experimental die radius range, so the Miyakawa's upper wrinkling limit is understimated in case of material tested.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.70-73
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• 2002

Using a simple compression test, the viscosity measurement experiment is carried out with the grain-refined Al-Si alloy(A356). The measured rheological data are expressed with power-law(Ostwald-de Waele) model and using commercial package, MAGMAsoft, coefficients of Ostwald-de Waele model and Carreau-Yasuda model are calculated. To verify the viscosity data, the die is designed to be applicable to the semi-solid die casting of automotive component and filling test is carried out. The filling test and the simulation result are compared and in good agreement. Hereafter, these data are considered to be usefully allied other product in the semi-solid die casting.

• Transactions of Materials Processing
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• v.8 no.6
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• pp.569-575
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• 1999

Computer programs have been developed to design the forging dies of turbine and compressor blades. The design of forging dies is based the side force and the filling of die cavity. In this study, slab method has been applied to simulate forging processes numerically. the program composed of Visual Basic also provides the informations of mean stress, total forging load, distribution of temperature, position of neutral line, total volume and volume of flash in the final stage to users. The preform position is predicted by the reverse slab method. The program has been successfully applied to various types of turbine blades.

• Transactions of Materials Processing
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• v.8 no.2
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• pp.188-199
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• 1999

Semi-Solid Forming Process(Thixoforming, Rheocasting) is a novel forming process which has some advantages compared with conventional die casting, squeeze casting and hot/cold forging. In this study. Thixoforming process was selected as analysis processing in terms of billet handling and easiness of automation process. The Thixoforming process consists of reheating process of billet, billet handling, filling inot the die cavity and solidification of SSM part. In filling process, two rheology models which were Newtonian and Non-Nettonian model (Ostwald-deWaele)were verified with experimental results. The Ostwald-deWaele model shows the good agreement to the real flow and filling phenomena in die cavity. To give a boost the economical efficiency of Thixoforming process and to ensure the good forming result, reheating device coupled die set was proposed and the initial billet temperature for system that was found from experimental resluts. This study presents an overview of application of numerical analysis for simulation of semi-solid metal forming process to reduce the lead time for development of manufacturing part in industrial field.

• Transactions of Materials Processing
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• v.6 no.4
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• pp.346-356
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• 1997

The fiber orientation distribution and interface bonding in hot extrusion process have an effect on the maechanical properties of metal matrix composites(MMC's). Aluminium alloy matrix composites reinforced with alumina short fibers are fabricated by compocasting method. MMC's billets are extruded at high temperature through conical and curved shaped dies with various extrusion ratios and temperature. This present study was directed to describe the systematic correlation between extrusion die shape and subsequent results such as fiber breakage, fiber orientation and tensile strength to hot extruded MMC's billet. Extrusion load, tensile strength and hardness for variation of extrusion ratios and temperature are investigated to examine mechanical properties of extruded MMC's SEM fractographs of tensile specimens are observed to analyze the fracture mechanism.

• Transactions of Materials Processing
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• v.8 no.2
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• pp.127-134
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• 1999

This study suggests the practical method which can reduce the lead time of the field trial and design of the dies. The virtual manufacturing, with which the die design is evaluated by computer analysis, reveals the impropriety of a design before die makings. Three methods for reducing the die making process occupying over 60% of the automotive development are like follows: First, the crack and wrinkle occurrence can be prevented by virtually adjusting the blank holding force and drawbead force with a computer simulation. Second, the parts which can not remove the forming defects in spite of the adjustment of forming parameters need to modify the part geometry or punch temporary shape. Third, the simulation before field trial, and field trial simulation can be effectively used in die design.

• Transactions of Materials Processing
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• v.8 no.6
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• pp.604-611
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• 1999

This paper is concerned with the family of parts that generally feature a central hub with radial protrusions. As opposed to conventional forward and backward extrusion, in which the material flows in a direction parallel to that of the punch or die motion, the material flows perpendicular to the punch motion in radial extrusion. Three variants of radial extrusion of a collar or flange are investigated. Case I involves forcing a cylindrical billet against a flat die, Case II involves deformation against a stationary punch recessed in the lower die, and Case III involves both the upper and lower punches moving together toward the center of the billet. Extensive simulational work is performed with each case to see the process conditions in terms of forging load, balanced and symmetrical flow in the flange. Also, the effect of the gap size and die corner radii to the material flow are investigated. In this study, the forming characteristics of radial extrusion will be considered by comparing the forces, shapes etc. The design factors during radial extrusion are investigated by the rigid-plastic FEM simulation.