• Transactions of Materials Processing
• /
• v.12 no.7
• /
• pp.615-622
• /
• 2003

In the automobile industry, the design of optimal blank shape becomes a significant part of the stamping. It provides many evident advantages, sush as enhancement of formability, reduction of material cost and product development period. However, the nesting process, required for the optimal usage of materials in the blanking becomes more complicated as the blank shape becomes complicated, like most optimal blank shape. In this study, stamping process optimization system for the optimal usage of material has been developed through the integration of optimal blank design and optimal nesting. For optimal blank design, a radius vector method, the modified version of the initial nodal velocity method, the past work of the present author, have been proposed. Both the optimal blank design and optimal nesting programs have been developed under the GUI environment for the convenience of engineers. The efficiency of the optimization system has been verified with some chosen problems.

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

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1997.10a
• /
• pp.93-97
• /
• 1997

Since the modified membrane element has the same external appearance as the ordinary membrane element, it is not able to apply the thickness variation of sheet metal in the blank holder to the contact treatment and the equally distributed blank holding force should be inevitably imposed on sheet metal along the periphery regardless of the contact status. But sheet metal does not contact with the blank holder at the periphery, nor the blank holding force is distributed uniformly along the boundary. To impose the blank holding force properly, the scheme is improved so that the blank holding force at each node imposed on sheet metal is dependent on the calculated thickness derivation and a state of equilibrium with the total blank holding force. The validity of the improved scheme is demonstrated with the simulation of cylindrical and rectangular cup deep drawing.

• Journal of the Korean Society for Precision Engineering
• /
• v.32 no.11
• /
• pp.945-952
• /
• 2015

In drawing sheet metal, the blank holding force is applied to prevent wrinkling of the product and to add a tensile stress to the material for the plastic deformation. Applying an inappropriate blank holding force can cause wrinkling or fracture. Therefore, it is important to determine the appropriate blank holding force. Recent developments of the servo cushion open up the possibility to reduce the possibility of fracture and wrinkling by controlling the blank holding force along the stroke. In this study, a method is presented to find the optimal variable blank holding force curve, which uses statistical analysis with consideration of the nonlinear deformation path. The optimal blank holding force curve was numerically and experimentally applied to door inner parts. Consequently, it was shown that the application of the variable blank holding force curve to door inner parts could effectively reduce the possibility of fracture and wrinkling.

• Journal of the Korean Society for Precision Engineering
• /
• v.15 no.12
• /
• pp.68-71
• /
• 1998

Rectangular deep drawing process is widely used in sheet metal forming. But there are various defects such as earring, wrinkling, tearing, etc. In order to avoid the defects, an optimum blank shape is required. But it has not been generalized to determine the optimum blank shape because deep drawing processes are involved in complex process parameters. So, it is very necessary to do research systematically about determining the optimum blank shape of deep drawing process. In this study a rectangular cup drawing test has been carried out to determine the optimum blank shape for various stainless steel sheets. From the test, a new blank model, which has no earring, is proposed.

• International Journal of Precision Engineering and Manufacturing
• /
• v.4 no.1
• /
• pp.5-8
• /
• 2003

The rectangular deep drawing process is widely used in sheet metal forming, but there are various associated defects, such as earing, wrinkling, tearing, etc. In order to avoid such defects, an optimum blank shape is required. Such an optimum blank shape cannot be generalized because deep drawing processes are involved in complex process parameters. So, it is necessary to do systematic research to determine the optimum blank shape for the deep drawing process. In this study, a rectangular cup drawing test has been carried out to determine the optimum blank shape for various stainless steel sheets. From the test, a new blank model, which has no earing, is propsed.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2000.05a
• /
• pp.753-756
• /
• 2000

The accumulated know-how and trial-and-error procedures are known as the best ways to determine blank shape and dimensions. One of the most important steps to determine the blank shape and dimensions in deep drawing process is to calculate the surface area of the product. In general, the surface area of products is calculated by mathematical or 3-D modeling methods. A blank design system is constructed for elliptical deep drawing products to recognize the geometry of the product in the long side and short side by drafting in another two layers on AutoCAD software. This system consists of input geometry recognition module, 3-D modeling module and blank design module, respectively. Blank dimension of three types is determined by the same area, which was acquired in 3-D modeling module. The suitability of this system is verified by applying to a real deep drawing product.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1997.03a
• /
• pp.55-58
• /
• 1997

In automotive industries, stamping of laser-welded blank gives many merits which brings about dimensional accuracy, strong body assembly and high productivity. However the welding of blanks with different thickness or/and different strength materials introduces many challenging formability problems for process development and tool design. In this paper, the deformation characteristics for deep drawing process of laser-welded blank with different thickness sheets are investigated by experiment and FEM simulation. And also the optimal location of weld line in laser-welded blank with different thickness sheets is calculated to compensate for the movement of weld line on deep drawing process. In addition, the effect of location of weld line is clarified using FEM simulation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2002.05a
• /
• pp.133-137
• /
• 2002

This paper summarizes the results of a numerical study conducted to analyze the determination of optimum blank diameter on material flow and thread profile for Spindle Screw in external thread rolling. Initial blank diameter affect a quality of Spindle Screw in thread rolling process. Therefore, it is very important to determine the optimum blank diameter in thread rolling process. In order to determine the optimum blank diameter, this paper suggest the calculating method of initial blank diameter considering real shape of tooth. The finite element code DEFORM is applied to analyze the metal flow of tooth. then the analytical results are verified by experiment of thread rolling for Spindle Screw.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
• /
• 2004.05a
• /
• pp.129-131
• /
• 2004

극자외선 리소그래피(EUV lithography) 기술은 50nm 이하의 선폭을 가지는 차세대 소자 제작에 있어서 선도적인 기술 중 하나이다. EUVL 에서 필수적인 요소중의 하나가 mirror 로 사용되는 blank mask 이다. Blank mask 에 있어서 가장 중요한 요소는 반사도이다. 이 blank mask 는 Si substrate 위에 반사를 위한 Mo/Si pair 가 40pair 이상 적층되어있다. Blank mask 는 매우 청결해야한다. 만약 결함이 있다면 blank mask 에는 치명적이다 결함은 blank mask 에 있어서 반사도를 떨어뜨리는 주 요소이기 때문이다. 그 결함에는 amplitude defect 과 phase defect 이 있다. FIB 에서는 amplitude defect 을 수정하는 것이 가능하다. 우리는 FIB 를 이용하여 mage mode, spot mode, bar rotation mode 를 사용하여 amplitude defect을 수정하였다. 그리고, 그 결과 효과적으로 amplitude defect을 수정하였다.