• Journal of Advanced Marine Engineering and Technology
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• v.23 no.5
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• pp.678-685
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• 1999

A UBET program is developed for determining flash the optimum sizes of preform and initial billet in plane-strain closed-die forging. The program consists of forward and backward tracing processes. In the forward program, flash, die filling and forging load are predicted. In backward tracing process the optimum dimensions of initial billet and preform are determined from the final-shape data based on flash design. Experiments are carried out with pure plasticine billets ar room temperature. The theoretical predictions of forging load and flow pattern are in good agree-ment with the experimental results.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.2
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• pp.96-103
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• 2011

Rotor grip is used as a component of rotor system in unmanned helicopter. Instead of usual machining, hot forging process has been considered to improve its proof stress against repeated loading conditions and crash in the farm-field. Die design and forming analysis have been performed according to the conditions such as billet volume, flash, cavity filling, and the distribution of damage during the forming by using FE analysis. In the results of analysis, the possibility of structural failure in the model has not been found because its maximum effective stress is much lower than yield strength of the titanium alloy. In the forging die design, flash has been allowed because of low production in the industrial field. Preform design was studied by using FE-analysis, and its optimal dimension was obtained in the hot forging of rotor grip with titanium alloy.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.5
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• pp.727-734
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• 1997

In practice, the design of forging processes is performed based on an experience-oriented technology, that is designer's experience and expensive trial and errors. Using the finite element simulation and the artificial neural network, we propose an optimal die geometry satisfying the design conditions of final product. A three-layer neural network is used and the back propagation algorithm is employed to train the network. An optimal die geometry that satisfied the same between inner extruded rib and outer extruded one is determined by applying the ability of function approximation of neural network. The neural networks may reduce the number of finite element simulation for determine the optimal die geometry of forging products and further they are usefully applied to physical modelling for the forging design.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.114-117
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• 2004

The isothermal forging design of a Ti-6Al-4V wing shape was performed by 3D FE simulation. The design focuses on near-net shape forming by the single stage. The process variables such as the die design, pre-form shape and size, ram speed and forging temperature were investigated. The minimization of forging load and uniform strain distribution in a given forging condition were considered as main design factors. The FE simulation results fur the final process design were compared with the isothermal forging tests. Finally, the modified process design for producing the uniform Ti-6Al-4V wing product without forming defects was suggested.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.7
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• pp.729-734
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• 2015

This research developed a new deep-bore, cup-shape, large forging process by combining die forging and free forging methods. In the proposed process, a preform for cup-shape large forging is produced by die forging, and a product with a deep bore is finally manufactured using an open die forging method, which is generally produced using a backward extrusion process. Finite element analysis results showed a higher effective strain distribution with a smaller forging load using the proposed method compared to the backward extrusion method. The production of a prototype with good internal quality using a small press capacity verified the proposed method.

• Transactions of Materials Processing
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• v.32 no.1
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• pp.5-11
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• 2023

The aim of this study is to manufacture an aluminum pipe yoke of automotive steering system for lightweight. In a multistage cold forging process for aluminum pipe yoke, the surface defects frequently occur due to excessive deformation or friction during extrusion process for forming hollow pipe part. It is import to reduce the friction between the material and the forging die. This study investigated a multistage forging process with sliding die to reduce friction for aluminum pipe yoke. After evaluating by FE analysis, the forging experiment with the sliding die was carried out. As a result, it was possible to manufacture a sound aluminum pipe yoke.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.1
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• pp.190-198
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• 1989

Some Developments in computer aided procedures for cold forging process and tool design of rotationally symmetric cup shape parts are described. The developed system enables appropriate forging sequence to be determined automatically, together with details of corresponding preform, die and punch design. The computer program developed is interactive and written in BASIC. This system not only assist the heavy work of designers but greatly shorten the time of design.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.277-280
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• 2005

A shape optimization is applied to achieve a design objective in three-dimensional forging processes. In multi-stage forging processes, among the important design aspects, the die shape fur preforming is regarded as the design variable since it influences the forged part relatively higher than the others. The rigid-plastic finite element method and the sensitivity method are employed and formulated to solve a formulated optimization problem. An approximation scheme is also used for the direction search during the optimization. The upset forging of a square box is selected as a test example in order to demonstrate and verify the optimization process of this study. After the optimization, the optimized shape of the die yields a finial product of desire shape.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.119-123
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• 2009

In this paper, effects of major design parameters of cold forging dies on die mechanics are quantitatively investigated with emphasis on shrink fit using a thermoelastic finite element method. A ball-stud cold forging process found in a cold forging company is selected as a test process and the effects of die insert material, shrink fit, dimension of ring, partition of die inert and clamping force on effective stress and circumferential stress are analyzed.

• Transactions of Materials Processing
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• v.13 no.2
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• pp.148-153
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• 2004

Finite element analysis of open die forging process to make rectangular billet has been performed in this study. Three dimensional rigid-plastic finite element method was used to analyze the effects of process variables, forging pass design and die configurations on the void closure phenomena to maximize the internal deformation for better structural homogeneity and center-line consolidation of the rectangular billet. The effect of anvil width ratio, anvil pitch, anvil shape and number of pass has been estimated by the degree of void closure ratio. Although it is difficult to optimize process parameters in the operational environments, favourable process conditions are suggested for better product quality.