• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.389-392
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• 2009

The application of an equivalent drawbead model(EDM) for sheet metal forming analysis, which adopts the forces instead of complex geometries in modeling the drawbead, to the numerical simulation of auto-panel stamping process is introduced in this study. In terms of the thinning and draw-in, better agreement with experimental measurements was found in EDM than in commercial code models so that the excellence of EDM in the accuracy of drawbead forces for the simulation of auto-body stampings was revealed.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.728-732
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• 2004

In the FE analysis of sheet metal forming, efficient results can be obtained by using shell elements rather than using solid elements. However, shell elements have some limitations to describe three-dimensional material laws. In the recent years, solid-shell element, which has only translational degree of freedom like solid element, has been presented. The assumed nature strain (ANS) and enhanced assumed strain (EAS) methods can be used to remove several solid-shell locking problems. In this paper, ANS method was used for diminish transverse shear locking and EAS method for thickness locking. Using the element, the steel pipe making process from flat plate analyzed effectively, which is including bending and welding.

• Transactions of Materials Processing
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• v.16 no.8
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• pp.603-613
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• 2007

This paper is concerned with joining of thin metal sheets by single stroke clinching process. This method has been used in sheet metal work as it is a simple process and offers the possibility of joining similar-dissimilar thin sheet metals. Clinching generates a joint by overlapping metal sheets deforming plastically by punching and squeezing sequence. AA 5754 aluminum alloy of 0.5 mm thick sheets have been selected as a modal material and the process has been simulated under different process conditions and the results have been analyzed in terms of the quality of clinch joints which are influenced mainly by tool geometries. The rigid-plastic finite element method is applied to analyses in this paper. Analysis is focused mainly on investigation of deformation and material flow patterns influenced by major geometrical parameters such as die diameter, die depth, groove width, and groove corner radius, respectively. To evaluate the quality of clinch joints, four controlling or evaluation parameters have been chosen and they are bottom, neck thickness of bottom and top sheets, and undercut thickness, respectively. It has been concluded from the simulation results that the die geometries such as die depth and diameters are the most decisive process parameters influencing on the quality of clinch joints, and the bottom thickness is the most important evaluation parameter to determine if the quality of clinch joints satisfies the demand for industrial application.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.450-455
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• 2017

A shield connector is an automotive electrical component that is used to connect electrical wiring in a vehicle. This part is made by progressive pressing using a phosphor bronze material with high electrical conductivity. The shape of the product is not complicated, but plastic forming techniques are required, such as deep drawing and bending, as well as shearing techniques such as piercing and notching. The finite element method was used to model the process. The strip layout design stage of the progressive die makes it possible to examine the thickness change, the stability of the forming process, and the spring-back. As a result of this analysis, it is possible to predict the correction values for the tendency of cracks, wrinkles, and incomplete plastic deformation, and to identify possible problems in advance. As a countermeasure against the forming error caused by the drawing process analysis, the drawing shape was modified and applied in the process design. For effective material utilization, a 3D strip layout was designed using an optimized blank shape based on nesting. The results improve the crack stability and spring-back of shield connector products produced through progressive pressing.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.8
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• pp.933-940
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• 2011

Thin sheets with a corrugated structure are generally used for the fabrication of heat exchangers for electronics, airplanes, and vehicles. However, it is difficult to fabricate corrugated structures, especially those with a bent angle, using the conventional stamping process because of its intrinsic formation mechanism. We propose a novel rubber-forming process for the effective pressing of the both tilted sides of a plate under the same pressure to form exact corrugated shapes. We use finite element analysis and experiments to study the rubber-forming process parameters, and we evaluate the maximum allowable bent angle for high-quality formation. We show that the proposed method is effective for the fabrication of bent plates with low cost.

• Transactions of Materials Processing
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• v.22 no.8
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• pp.437-441
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• 2013

Recently, the engraving of letters or a pattern on a product surface has received more attention especially in trying to satisfy the customer requirements. Half-piecing is a protrusion forming process that pierces only 40~50% of the material thickness. In the current study, the half-piercing technique for making clear letters by protruding sheet material was selected and studied. The influence of clearance and penetration depth was investigated by measuring the camber and extruded length of a protrusion after experiments. In addition, a numerical analysis was performed for the same working conditions and compared with experimental results. It is shown that, as the clearance increases, the camber of a protrusion increases rapidly and the extruded length decreases slightly. The deformation pattern around the cutting edge during half-piercing changes from an extrusion mode to a shearing mode as the clearance changes from minus to plus values. It is also confirmed that the experimental results show a good agreement with the numerical analyses.

• Journal of Computational Design and Engineering
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• v.3 no.1
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• pp.63-70
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• 2016

Deep drawing is a forming process in which a blank of sheet metal is radially drawn into a forming die by the mechanical action of a punch and converted to required shape. Deep drawing involves complex material flow conditions and force distributions. Radial drawing stresses and tangential compressive stresses are induced in flange region due to the material retention property. These compressive stresses result in wrinkling phenomenon in flange region. Normally blank holder is applied for restricting wrinkles. Tensile stresses in radial direction initiate thinning in the wall region of cup. The thinning results into cracking or fracture. The finite element method is widely applied worldwide to simulate the deep drawing process. For real-life simulations of deep drawing process an accurate numerical model, as well as an accurate description of material behavior and contact conditions, is necessary. The finite element method is a powerful tool to predict material thinning deformations before prototypes are made. The proposed innovative methodology combines two techniques for prediction and optimization of thinning in automotive sealing cover. Taguchi design of experiments and analysis of variance has been applied to analyze the influencing process parameters on Thinning. Mathematical relations have been developed to correlate input process parameters and Thinning. Optimization problem has been formulated for thinning and Genetic Algorithm has been applied for optimization. Experimental validation of results proves the applicability of newly proposed approach. The optimized component when manufactured is observed to be safe, no thinning or fracture is observed.

• Transactions of Materials Processing
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• v.18 no.6
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• pp.488-493
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• 2009

The very big springback of advanced high strength steel(AHSS) sheets invokes undesired shape defects, which can be generally eliminated by die correction or process parameter control. The springback reduction by controlling the forming process parameters is easy for the application, but limited for the bulky achievement. In this study, the effective die correction method, which obtains the modification of tool shape from the relationship between die design variable and springback, is introduced and is applied to the TWB tool of automotive side rail to show the validity and usefulness. Among the die correction trials repeatedly performed, the first trial is carried out by correcting the tool shape to the opposite direction to the springbacks of several tool sections. Next trials are done by extrapolating the springbacks of among the original tool uncorrected and the tools corrected negative amounts of the springback and by finding tool shapes without springbacks. After the angle of side wall and radius of curvature of horizontal bottom floor are chosen as design variables in the tool design of side rail, the tool shape is corrected 3 times. The accuracy of final shape within the assembly limit of 1mm and the springback reduction of 75.8% compared to the uncorrected tool are achieved.

• Transactions of Materials Processing
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• v.14 no.4 s.76
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• pp.303-309
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• 2005

Reverse Engineering 기술을 이용하여 금형 형상을 측정하고 이를 이용하여 자동차 주요 대형 성형 부품에 대하여 유한 요소 성형 해석을 수행하여 성형 인자들의 영향에 대하여 분석한 결과 다음과 같은 결론을 얻었다. (1) Reverse Engineering 기술의 사용은 대형 자동차 성형 부품에 대하여 성형 해석을 위한 금형 CAD 데이터를 확보하는데 유용함을 알 수 있었다. 그러나 보다 적극적으로 사용되기 위해서는 곡면 생성의 시간 단축과 제품 면에 발생한 주름에 의한 형상 차이 등의 문제를 해결하여야 할 과제가 남아 있다. (2) 성형 해석을 위하여 자동차 외판 부품 Trunk lid outer에 대하여 성형 해석을 수행 결과 부픔의 성형성에 영향을 주지 않는 한도 내에서 r값과 n 값이 낮은 소재를 사용하는 것이 부품의 형상 동결성을 확보하는데 유리한 것을 알 수 있었다. (3) 판재 성형 부품에 대한 적절한 소재의 재질 선정 방법으로서 유한 요소 해석이 매우 유용한 것을 알 수 있었다.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.2
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• pp.56-61
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• 1999

The fine blanking is a process of pressworking which makes possible to produce thick sheet metal parts of finished sheared surface and close dimensional accuracy over whole material thickness in single blanki ng operation. Fine blanked parts in general are characterized by their cleanly sheared surface over the whole sock thickness and accurate size for the specific functions. The fine blanking technology is urgently needed to remove secondary operations which are necessary in conventional blanking operation and cost reduction. In this study, the effect of material texture and vee-ring on parts for automobile is investigated by experimental observation and analysis.