• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.6
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• pp.216-225
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• 2023

This paper describes the finite element analysis and die design change of cold heading punching process to increase the cold forging tool life and reduce the tool wear and stress concentration. Through this study, the optimization of punch tool design has been studied by an analysis of tool stress and wear distribution to improve the tool life. Plastic deformation analysis was carried out in order to understand the cold heading process between tool and workpiece stress distribution. Cold heading punch die design was set up to each process with different four types analysis progressing, the cold heading punch dies shapes with combination of point angle and punch edge corner radius shapes of cold forging dies, punch die material properties and frictional coefficient. The design parameters of point angle and corner radius of punch die geometry, die material properties and frictional coefficient were selected to apply optimization with the DoE (design of experiment) and Taguchi method. DoE and Taguchi method was performed to optimize the cold heading punch die design parameters optimization for bolt head cold forging process, it was possible to expect an reduce the cold heading punch die wear to the 37 % compared with current using cold heading punch in the shop floor.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.71-76
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• 2001

This paper describes a research work of developing system for conceptual die design system for Fine blanking. The method of approaching to the system is based on the knowledge-based rules. Knowledge for the system is formulated from experimental results and the empirical knowledge of field experts. This system has been written in VisualLISP on the AutoCAD using a personal computer and in Microsoft Visual Basic ver.6.0. Transference of data is accomplished by DXF (Drawing Exchange Format) method. This system consists of six modules, which are cognition of a drawing, cognition of shear length, calculation of shear force, materials properties database, determination of degree of difficulty of the product, determination of approximate life of punch and die modules. Results carried out in each module will provide efficiency to the designer and the manufacturer of die for Fine blanking. But the main focus of this system is the design of die for Fine blanking in the level of general concept. In order to use powerful tool in this field, developed system will be studied continuously.

• Transactions of Materials Processing
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• v.19 no.5
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• pp.283-289
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• 2010

Extrusion process in the bulk material for fabrication of miniature helical gears has problems such as a high forming load and short tool life because the cross-section is complex and asymmetry. To overcome these problems, in this study, miniature helical gears were fabricated by Zn-22Al powder hot extrusion. The included die angle for minimum extrusion load and improving die filling was determined by FE-simulation. The Zn-22Al spheroidal powder produced by gasatomization were compacted and sintered for extrusion experiment. The dimension of helical-gear is 0.3mm in module, 3.35mm in pitch diameter, $15^{\circ}$ in helix angle and the number of teeth is 12. All of the extrusion experiments were performed with internal helical gear die which was machined by precision electric discharge machining using the electrode. The experiment was conducted at $190^{\circ}C$ to $310^{\circ}C$ to obtain extrusive and mechanical properties. The extruded helical gears were analyzed through extrusion load, Vickers hardness and SEM images for each extrusion temperature. The powder hot extrusion process was successfully applied to fabricate a miniature helical gear.

• Journal of the East Asian Society of Dietary Life
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• v.6 no.2
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• pp.213-219
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• 1996

Addition of reducing agents during extrusion markedly affected physical and chemical properties of wheat flour and gluten extrudates. Expansion at the die was increased for wheat flour and gluten extrudates. Organic materials containing sulfur were evaporated as a flavor from gluten at the die and total sulfur contents were decreased. Physical shape was different for gluten extrudates without reducing agents. It was difficult to form the long strand of gluten extrudate without cooling die. Hydroquinone accelerated cell breakdown and produced more irregular shape of extrudate. However, addition of cysteine decreased the cell breakdown and produced the long strand of gluten extrudates. Chemical reactions of reducing agents such as cysteine and hydroquinone were different for high content (＜80%) of wheat gluten. It was assumed that reducing agents donated hydrogen to inhibit the formation of disulfide crosslinking, decreased the dough strength and produced the broken cell and irregular shape of extrudates. Whereas, cysteine reacted as a binder as well as reducing agent and formed long strands. The evidence of reaction of reducing agents was shown from the fact that non-protein disulfide was increased and protein disulfide was slightly decreased from cysteine added gluten extrudate.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.10
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• pp.879-886
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• 2016

Tractrix dies, used in the deep drawing process, can be used to form CNG pressure vessels without a blank holder. Previous studies had only applied tractrix profiles to perform the first deep drawing process of DDI; but an optimal design of the tractrix die that focuses on improving die life and reducing production cost has not been performed yet. In this study, finite element analyses of deep drawing processes were conducted according to heights of the tractrix die by using translating asymptotes. In addition, researchers analyzed von-Mises stresses at the part of stress concentration of the die according to the forming punch loads in order to propose an optimal tractrix die design.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.5
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• pp.391-395
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• 2005

This paper has comparatively analyzed the characteristics of the machined surface of a specimen made by machining Die Steel STD11 and a specimen obtained by W-EDM steel. If a press die is manufactured through W-EDM, products of shapes that cannot easily be made through machining can be manufactured easily. However, the life of the press die is significantly reduced compared with the press die made through machining. This is believed to be caused by the deformed layer that has occurred on the surface of the press die that was made through W-EDM. The roughness of the 2 specimens was measured, and it was learned that the distribution of the roughness of the specimen made through the 1st W-EDM was rough. When the specimens were observed using a scanning-electron microscope, there was significant difference between the surface and the cross-section of the 2 specimens, while the cross section of the specimen obtained through W-EDM had the tempered and quenched surface structure which exists in the form of a deformed layer.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.06b
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• pp.141-146
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• 1999

In the stage of process design, many factors affecting tool life should be considered. Wear, Damage Accumulation and excessive die Stress are those. Most Engineer think wear and damage accumulation affection deeply to the cold forging dies and wear for the hot forging dies. In this report, the example that wear and stress distribution affect tool life in hot forging together will be introduced and the way to solve that problem using Finite Element Method.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.233-235
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• 2001

Residual stress in the forged parts affects the resistance to mechanical failure, dimensional uniformity, and the service life of the parts. In order to elucidate the development of residual stress in open-die forging process, elasto-plastic finite element analysis was implemented to radial forging process. Super duplex stainless steel SAF 2507 was selected as workpiece material and a series of mechanical tests followed by numerical compensation to deformation heating was conducted to obtain necessary flow data. The residual stress distributions were calculated using commercial 3-D FEM code and the effects of process design were evaluated from selected results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.698-701
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• 2005

Nowadays, because of the frequent market change and variable customer's requirements, product's life-circle is becoming shorter. So, automobile companies are forced to rapidly develop new products and efficiently reduce both manufacturing lead time and cost, with the world level quality. Among them, Press Die is not only just a bottle neck but also an important resource exerting certain effect in quality of car body appearance. Since 2000, due to efforts to reduce the time of design phase, many companies have used 3D design methods. Actually the method didn't reduce the period of design because the company didn't develop the best practice. This paper wish to solve this problem by modular based hybrid dies template.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.03b
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• pp.145-155
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• 1996

The extrusion velocity of billet through a die and the shapes of the die are the important factors in the metal forming process of the extrusion of billet. in recent years, the life cycle of products is goingfaster. Although the former finite element method was capable of yielding a detailed analysis, it requires lots of time and extensive coding effort. Then, some simple devices were developed and based on upper bound method. For this purpose , a kinematically admiasible velocity field is formulated for extrusion of cylinders with arbitrary cross section and die profile on their outer surfaces by using a modified upper bound approach, which configures simulataneous extruding speeds in three directions . Also, In order to display mesh of the cold forward extrusion process using the approach , the automatic three-dimentional mesh generation produced by the approach coupled finite element method with upper bound method.