• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.263-266
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• 2008

We apply a closed die forging technology to a large crankshaft of which forging weight amounts to 850kg. 40ton counter-blow hammer forging machine is used. The forging process is optimized to reduce the forming load using finite element simulation. AFDEX 3D is used for forging simulation. The experiment is compared with finite element prediction and a good agreement is observed. The successful development of a large crankshaft by the closed die forging technology will contribute to opening a new area of closed-die forging application and to enhancing competitiveness of national machinery industries especially including ship part and power generation industries.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 The 8th Asian Symposium on Precision Forging ASPF
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• pp.127-132
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• 2003

This article mainly introduces the research of closed forging on 20MN hot die forging presses. After transforming of the equipments, optimizing of die design and improving of die-manufacturing precision, gear blanks used in car gearbox have been forged out without fins successfully.

• 대한기계학회논문집
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• 제17권12호
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• pp.2970-2981
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• 1993

In hot closed-die forging the load increases rapidly near the final stage. Preforming operation is important to both the sound final forging and die-service life. In this study, the material flows during preforming and final forging are investigated. The physical modeling with Plasticine as a model material showed clear flow patterns. The forging process were numerically simulated by the finite element method with the isothermal and the non-isothermal models. The flow patten of the isothermal simulation showed good agreements with the experiments. Temperature changes and pressure distributions on the die surfaces during one cycle of the forging process were obtained from the non-isothermal simulation. High pressure and temperature were developed at certain areas of the die surfaces. It was concluded that those areas usually coincide with each other and should be distributed by the preforming operations to enhance the die life.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.427-430
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• 2007

Gas turbine disk components have been used by Ni-base superalloys which have high temperature strength for enduring stress induced by high speed rotation. This study introduced the overview of development strategy of precision forging of turbine disk and closed-die forging process for manufacturing good quality gas turbine disk. To make superior quality turbine disk, it is important to select optimal forging process conditions like preform shape, die shape and forging temperature etc. In this paper, closed-die forging process has been studied through the rigid-plastic finite element simulation. Proposed forging process can be used for the successful manufacturing of small-size gas turbine disk.

• 한국기계가공학회지
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• 제2권1호
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• pp.92-99
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• 2003

Bevel gears are important mechanical parts to transmit power in transportation system high precision parts like bevel gears might be manufactured by closed die forging process for dimensional accuracy. Closed die forging of bevel gears offers the high quality and good mechanical properties and also leads to considerable cost saving. To determinate the proper closed-die forging process for bevel gear forms, three-dimensional finite element simulation for the progressive forging process was earned out and also the simulation results were compared with experimental results.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.180-183
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• 2005

The purpose of this study is to evaluate a closed-die forging method for large crank throw using analytical and numerical approaches. A closed-die forging equipment with wedge and links was proposed to forge large crank throw using kinematic analysis. The minimum press capacity for the closed-die forging was established using the comprehensive FEA.

• 한국산업융합학회 논문집
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• 제2권2호
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• pp.187-194
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• 1999

Closed-die forging of spline was analysed using the upper bound elemental technique, Two different forging methods, denoted here as side extrusion-forging and upset forging, were proposed, The kinematically admissible velocity fields for each of the forging methods, which could express trapezoidal, rectangular and serration tooth forms, were presented. Upper bounds to forging loads and deformed configurations were predicted using the velocity fields. Theoretical results were compared with experimental ones. Experiments with lead were carried out at room temperature where grease was used as a lubricant. The present investigation revealed that analytical forging loads were reduced by using the side extrusion-forging but the upset forging could improve configuration of the final forged splines.

• 소성∙가공
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• 제31권2호
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• pp.51-56
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• 2022

In this study, finite element analyses were performed by applying a stress ring and split die design to relieve the tensile stress acting on the die due to high surface pressure during warm-closed forging. The applied material was a yield-ratio-control-steel (YRCS). It was used without quenching or tempering after forging. In the case of stress rings design, the number of stress rings and the tolerance for shrink fit were different. Vertical and horizontal splits were applied for insert die split design. Case 5 die with three stress rings, 0.2 % shrink fit tolerance, and vertical split was selected as an effective die design for tensile stress reduction. Based on die stress reduction analyses, Case 5 die for warm-closed forging was produced and smooth forgeability was secured, making it possible to manufacture forging product of yoke with the required geometry. In addition, controlled cooling using warm forging heat was applied to secure mechanical properties of yokes. When oil cooling was used for direct controlled cooling after warm-closed forging, a relatively uniform Rockwell hardness distribution and high mechanical properties could be obtained.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 추계학술대회 논문집
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• pp.242-247
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• 1998

The conventional closed-die forging processes had been applied to forging of the spur gears. But this type process requires high pressure. The commercial finite element analysis code ANSYS for the stress and elastic deformation of non-axisymmetric die was adopted in this study. In the non-axisymmetric die such as gear forging, maximum stresses were imposed on the tip of the gear tooth. When the stress exceeds yield strength of insert die, many approaches were attemped to prevent the die failure. Good shaped products are forged successfully. This type process could by used as an advanced technique to replace conventional hobbing process of gear.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 춘계학술대회논문집
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• pp.126-129
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• 1998

Proper design of blocker dies is one of the most important aspect of impression and closed-die forging to achieve adequate metal distribution. Determination of the blocker configuration is a very difficult task and is art in itself, requiring skills achieved only by years of extensive experience. To save the cost and time of blocker design, many methods using computer were proposed. In this research, low pass filter method proposed by Oh etc. was applied to blocker die design of spoiler support, part of aircraft and plasticine model experiment of closed die forging of spoiler support was accomplished to verify the validity of the blocker designed.