• Journal of the Korean Society for Precision Engineering
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• v.16 no.11
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• pp.174-182
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• 1999

This paper describes a research work of developing a computer-aided design of product with bending constraints and piercing for progressive working. an approach to the CAD system is based on the knowledge-based rules. Knowledge for the CAD system is formulated from plasticity theories, experimental results and the empirical knowledge of field experts. The system has been written AutoLISP on the AutoCAD with a personal computer and is composed of four main modules, which are input and shape treatment, flat pattern layout, production feasibility check, and strip-layout module. Based on knowledge-based rules, the system is designed by considering several factors, such as radius and angle of bend, material and thickness of product, complexities of blank geometry and punch profile, bending sequence, availability of press. Strip layout drawing generated by piercing with punch profiles divide into automatically for external area is shown into graphic forms, including bending sequences for the product with piercing and bending constraints. Results obtained using the modules enable the designer and manufacturer of piercing and bending dies to be more efficient in this field.

• Transactions of Materials Processing
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• v.11 no.8
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• pp.682-690
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• 2002

The formation of adiabatic shearband in tungsten heavy alloys(WHA) was studied in this investigation. Five prismatic specimens were loaded by high velocity impacts and treated as plane strain problems. To find out the effect of particle's volume ratio, specimens containing 81%, 93% and 97% volume percents of tungsten particles were used. Also the effects of particle's geometry and size on the formation of shearband were studied for 81% volume percent alloys by small size particle model, large size particle model and undulated particle models, and the results were discussed.be used to diagnose the causes of necking and fracture in industrial practice and to investigate whether these defects were caused by material property variation, changes in lubrication, or incorrect press settings. In non-axisymmetric deep drawing, three modes of forming regimes are found: draw, stretch, plane strain. The stretch mode for non-axisymmetric deep drawing could be defined when the major and minor strains are positive. The draw mode could be defined when the major strain is positive and minor strain is negative, and plane strain mode could be defined when the major strain is positive and minor strain is zero. Through experiments the draw mode was shown on the wall and flange are one of a drawn cup, while the plane strain and the stretch mode were on the punch head and the punch corner area respectively, We observed that the punch load of elliptical deep drawing was decreased according to increase of die corner radius and the thickness deformation of minor side was more large than major side.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.6
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• pp.87-93
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• 2004

An experimental is carried out to investigate the characteristics of blanking for nickel alloy Alloy42 (t=0.203mm), a kind of IC lead frame material. By varying clearance between die and punch the shapes of shear profile are examined. Finite element analysis with element deletion algorithm for ductile fracture mode is also carried out to study the effect of clearance theoretically and to compare with experimental results. The rectangular shape specimen with four different comer radius is used to study the characteristics of blanking for straight side and comer region simultaneously. As the result the ratios measured k(m experiment of roll over, burnish and fracture zone based on initial blank thickness are compared with those of FE analysis. Both experiment and FE analysis show that the amount of mil over and fracture is increased as the clearance increases. When the radius of comer is less than thickness of blank it has been found that larger clearance is required than that of straight region in order to maintain same quality of shear profile at the comer region.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.3
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• pp.182-188
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• 2001

An experiment is carried out to investigate the characteristics of blanking for copper alloy C194 (t=0.254mm), a kind of IC lead frame material. By varying clearance between die and punch, the shapes of shear profile are examined. Finite element analysis with element deletion algorithm for ductile fracture mode is also carried out to study the effect of clearance theoretically and to compare with experimental results. The rectangular shape specimen with four different corner radius is used to study the characteristics of blanking for straight side and corner region simultaneously. As the result, the ratios measured from the experiment of roll over, burnish, and fracture zone based on intial blank thickness are compared with those of FE analysis. Both experiment and FE analysis show that the amount of roll over and fracture is increased as the clearance increases. It has been found that larger clearance is required than that of straight region when the radius of corner is less than thickness of blank, in order to maintain same quality of shear profile at the corner region.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.2
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• pp.177-185
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• 2001

This study shows the process design and forming analysis of permalloy shielding can that support the automobile multi-display parts to indicate the accurate information of car. This study is particularly important, since the strain and thickness of permalloy shielding can is known to affect the magnetic properties such as coercivity and permeability quite thickness of permalloy shielding can is known to affect the magnetic properties such as coercivity and permeability quite sensitively. The objective functions are strain and thickness deviation. The punch radius, die radius and blank holding force are considered as design parameters. Orthogonal array (OA) table and characteristics are applied to neural network (NN) as train data. After training, the optimal and robust condition of design parameters is selected. This study shows the correlation between the design methodology of NN and the statistical design of experiments (DOE) approach.

• Journal of the Korean Society for Precision Engineering
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• v.5 no.3
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• pp.31-42
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• 1988

This paper describes a computer aided process planning system called "Deep-Drawing", "Deep-Drawing" is designed for the drawing sequence of cylindrical and rectangular cups with or without taper and flange. The computer program has written in BASIC language with personal computer. Design Rules for process planning are formulated from process limitation, plasticity theory and experimental results including the know-how of many manufacturing factories. "Deep-Drawing" Capabilities include the analysis of drawing sequence by the determination of optimal drawing ratio, the determination of intermediate shape, dimensions, punch and die radius etc., the calculation of drawing loads and blank holder force to perform each drawing step, and the graphic outputs for the operation sheet.tputs for the operation sheet.

• Design & Manufacturing
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• v.6 no.2
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• pp.42-47
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• 2012

The paper deals with an analysis of an extrusion process with a divided material flow in a combined radial - backward extrusion. We have discussed the influences of tool geometry such as punch nose angle, relative gap height, die corner radius on material flow and surface expansion into can and flange region. To analyse the process, numerical simulations by the FEM and experiment by physical modeling using Al alloy as a model material have been performed. Based on the results, the influence of fixed parameters on the distribution of divided material flow and surface expansion are obtained.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1757-1760
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• 2005

This paper is concerned with spring back after sheet forming of bulk amorphous alloys in the super cooled liquid state. The temperature-dependence and strain-rate dependence of Newtonian/non-Newtonian viscosities as well as the stress overshoot/undershoot behavior of amorphous alloys are reflected in the thermo-mechanical Finite Element simulations. Hemispherical deep drawing operations are simulated for various forming conditions such as punch velocity, die corner radius, friction, blank holder force, clearance and initial forming temperature. Here, spring back by an instantaneous elastic unloading was followed by thermal deformation during cooling and two modes of spring backs are examined in detail. It could be concluded that the superior sheet formability of an amorphous alloy can be obtained by taking the proper forming conditions for loading/unloading.

• Transactions of Materials Processing
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• v.18 no.7
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• pp.531-537
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• 2009

The effect of blank holding force on thickness variation in simultaneous sheet forming with rectangular shape and circular has been demonstrated. Because has investigated an effect on formability of magnesium sheet, in this paper, the effect of punch radius on formability have been thinning, various crack phenomena and forming velocity. By simultaneously forming process with circular and rectangular shape, the data of simultaneously forming process with circular and rectangular shape will used to a part development such as notebook computer case, cell phone and bipolar plate of fuel cell.

• Transactions of Materials Processing
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• v.20 no.2
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• pp.124-131
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• 2011

A flexible stretch forming process is useful for small quantity batch production because various shape changes of the flexible die can be achieved conveniently. In this study, the design variables, namely, the punch size, curvature radius and elastic pad thickness, were quantitatively evaluated to understand their influence on sheet formability using statistical methods such as the correlation and regression analyses. Forming simulations were designed and conducted by a three-way factorial design to obtain numerical values of a shape error. Linear relationships between the design variables and the shape error resulted from the Pearson correlation analysis. Subsequently, a regression analysis was also conducted between the design variables and the shape error. A regression equation was derived and used in the flexible die design stage to estimate the shape error.