• Journal of the Korean Society for Precision Engineering
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• v.20 no.12
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• pp.168-175
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• 2003

In this paper, the tube forming by radial-forward extrusion is analyzed by numerical simulation and experiments. The paper discusses the effects of process variables such as gap height, relative gap width and die corner radius on tube forming. The influence of deformation patterns of flange in radial extrusion on forward extrusion for tube forming is investigated and summarized in terms of the maximum forming force and hardness variations along the extrusion path. Furthermore the external defects are shown experimentally during the forming operation. Based on finite element analysis in conjunction with experimental test in Al alloy, analysis is performed for important parameter combination in order to reduce forming defects. Eventually, the process parameters for safe forming are suggested in order to reduce the forming defects.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4381-4387
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• 2015

Ship hull is a compound curved shape and most of shipyards have been using gas heating method for the surface forming of steel plate. This traditional forming process have problems such as difficulties in heat input control and poor working conditions due to loud noise and air contamination. Recently, researches on automatic hull forming system have been conducted using high frequency induction heating method which have good control ability and favorable working environment. In this study, the induction heating simulation system for curved surface forming of steel plate was developed and induction heating experiments were performed. Based on the results of this study, efficient induction heating coil design and optimal heating conditions for the automatic hull forming system can be obtained.

• Transactions of Materials Processing
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• v.29 no.4
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• pp.203-210
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• 2020

In this study, formability and springback behavior of 1.5 GPa grade ultra-high strength steel (UHSS) sheet were predicted through the finite element simulation, and structural stability of the forming dies was verified by the coupled forming-structural analysis. Uniaxial tension and uniaxial tension-compression tests were performed to obtain experimental data for modeling the springback properties of the sheet material. The springback values predicted by simulation were compared with those from actual measurements. The results calculated from the kinematic hardening model were found to be much more accurate than those from the isotropic hardening model. Deformation of the forming die and springback of the product were calculated by the coupled forming-structural analysis. The higher the strength of the die material, the smaller the surface displacement of the die and the springback of the product. The internal stresses of the dies made of three materials, FC300, FCD550 and STD11 were compared with the yield stress of each material. The results provided a basis for determining the most suitable material for each part of the die set. As a result, simulation techniques have been established for predicting formability and springback in the UHSS sheet forming process.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.799-803
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• 2008

The possibility of manufacturing titanium hollow cylinder tank for ramjet engine was demonstrated with superplastic forming of subscale article. An innovative manufacturing method to produce complex configuration from titanium multi-sheets by low hydrostatic pressure was presented. Finite element analysis on superplastic blow forming process has been carried out in order to improve the forming process when manufacturing subscale hollow cylinder structure using Ti-6Al-4V multi-sheets. The simulation focused on the reduction of forming time and obtaining finally required shape throughout investigating the deformation mode of sheet according to the forming conditions and die geometry. From pre-sized titanium sheets, near net shape of hollow cylinder tank is obtained by superplastic blow forming conducted using gas pressure of 15bar at 1148K. The result shows that the manufacturing method with superplastic forming of multi-sheets of titanium alloy has been successful for near net shape forming of subscale hollow cylinder tank of ramjet engine.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.559-560
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.585-586
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• 2007

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1313-1314
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• 2011

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.282-284
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• 2007

The hardening and the constitutive equation based on the crystal plasticity are introduced for the numerical simulation of hemispherical sheet metal forming. For calculating the deformation and the stress of the crystal, Taylor's model of the crystalline aggregate is employed. The hardening is evaluated by using the Taylor factor, the critical resolved shear stress of the slip system, and the sum of the crystallographic shears. During the hemispherical forming process, the texture of the sheet metal is evolved by the plastic deformation of the crystal. By observing the texture evolution of the BCC sheet, the texture evolution of the sheet is traced during the forming process. Deformation texture of the BCC sheet is represented by using the pole figure. The comparison of the strain distribution and punch force in the hemispherical forming process between crystal plasticity and experiment shows the verification of the crystal-based formulation and the accuracy of the hardening and constitutive equation obtained from the crystal plasticity.

• Journal of Power System Engineering
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• v.17 no.3
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• pp.65-71
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• 2013

The under rail slide is the latest device to make accurate rectilinear reciprocating motion. In these day, 3-point type is used mostly for the products requiring high strength and performance such as refrigerator door guide or furniture drawer guide. However, It is all imported from foreign countries due to lack of the roll forming technique to make 3-point type under rail slide in domestic. Therefore, design and manufacturing technology for the 3-point type under rail slide are need to development through systematic study. In this paper, to make center member of 3-point ball-type under rail slide for the refrigerator doors, the roll forming modeling and simulation are performed using Shape-RF software. Tensile test is performed about SCP-1 1/2H for determine the mechanical properties of materials. Interference between the roll and the final shape are predicted from the results of the simulation ; this result show that the desirable performance and usefulness of the designed roll forming process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1376-1380
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• 2005

In recent automotive industry, vehicle weight can be reduced by one-step forming of tailored blanks welded with two or more sheets of metal blanks. Tailored blank(TB) welding is a production method for blanks involving welding together materials of different quality, thickness, and coating, and has proved popular in fabrication automotive parts. This paper deals with the forming characteristics of mash seam welded tailored blanks. Using these forming characteristics, the bumper beam was developed using the mash seam welded tailored blank with the different thickness. We performed the forming simulation with respect to strain distribution on blank during the stamping of the bumper rail part. Based on these results, we made some stamping tryouts with selected types of blank designs to investigate the formability of tailored blank with different thickness. During the tryouts, we knew that it was important the BHF(Blank Holding Force). We obtained to reducing 10.5% weight and cost with adapting the bumper beam of automotive component using the tailored blank of mash seam welding.