• 한국정밀공학회지
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• 제11권4호
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• pp.77-87
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• 1994

This paper deals with an automated forming sequence design system by which designers can determine desirable operation sequences even if they have little experience in the design of cold forging process. The forming sequence design in the cold forging is very important and requires many kinds of technical and empirical knowledge. They system isproposed, which generates forming sequence plans for the multistage cold forging of axisymmtrical solid products. Since the process of metal forming can be considered as a transformation of geometry, treatment of the geometry of the product is a key in planning process. To recognize the geometry of the product section, section entity representation and primitive geometries were used. Section entity representation can be used for the calculation of maximum diameter, maximum height, and volume. Forming sequence for the part can be determined by means of primitive geometries such as cylinder, cone, convex, and concave. By utilizing this geometrical characteristics (diameter, height, and radius), the product geometry is expressed by a list of the priitive geometries. Accordingly the forming sequence design is formulated as the search problem which starts with a billet geometry and finishes with a given product one. Using the developed system, the sequence drawing with all dimensions, which includes the proper sequence of operations for the part, is generated under the environment of AutoCAD. Based on the results of forming sequence, process variables(strain, punch pressure, die inner pressure, and forming load) are determined.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 추계학술대회 논문집
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• pp.75-80
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• 2001

The purpose of this study is to investigate the characteristics of springback for various process conditions of the 2D draw-bending operation. The process variables are the forming temperature, the geometry of tools such as punch profile radius(Rp) and die profile radius(Rd). Especially, in order to control the springback, the use of the warm forming method is applied. For the warm draw-bending, five steps of temperature ranges, from room temperature to $200^{\circ}C$, were adopted. And two kinds of steel sheets, namely SCP1 and TRIP(transformation-induced plasticity), the newly developed high strength Steel, were adopted. As a result, the springback was affected by the elevated temperature and the geometry of tools in two kinds of steel sheets.

• 소성∙가공
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• 제12권3호
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• pp.251-258
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• 2003

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

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.753-756
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• 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.

• 소성∙가공
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• 제17권3호
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• pp.203-209
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• 2008

In this paper, experimental investigation has been performed to analyze the forming process of toothed or serrated sheets, which is used as strap engaging surface of the seal to secure together overlapping portions of steel or plastic strapping ligature. Serration formed on the strap engaging surface of the seal prevent from relative slipping between overlapping ligatures after closing the seal. The geometry of tooth on the strap engaging surface is directly related to the quality of securing overlapping ligatures together. Inclined indentation followed by scratching operation has been proposed and applied to the experiments. Punch entry and face angles are selected as process variables to see the influence of these variables on the tooth geometry. Five different punch entry angles have been applied to experiments and three different punch face angles have been selected for each case of punch entry angle. Clay is selected as model material for experiments. Experimental results are summarized in terms of tooth height, tooth width, and aspect ratio such as tooth height to width ratio, respectively.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.210-215
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• 2003

A terminal pin, which is a part of high-voltage capacitors, has a head section of plate-shaped geometry with 0.8 thickness. The current manufacturing process, in which the head section is welded on the body part, has given wide deviations of part qualities such as geometrical accuracy, mechanical strength and electrical stability. In this paper, a cold forging process sequence was designed in order to produce the terminal pin as one piece. The plate-shaped head section requires an upsetting in the lateral direction of a cylindrical billet, which is followed by a blanking process. The deformed geometry of the upsetting, however, could not be predicted precisely by intuition since metal flows of an axial and a lateral direction of the cylindrical billet would occur simultaneously. Therefore, the geometry of the initial billet was determined by three dimensional finite element analysis in order to avoid defects in blanking process and intermediate forging processes were designed by applying design rules and two dimensional FE analysis. In addition, cold forging tryouts were conducted by using the die sets which were manufactured based on the designed process sequence.

• 소성∙가공
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• 제9권3호
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• pp.226-232
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• 2000

The optimal blank design method by sensitivity analysis has been applied to the formings of oil-pan, tailored blank and front panel as the examples. Die geometry is prepared by a commercial CAD system. Excellent results has been obtained between the numerical results and the target contour shapes. Through the investigation, the proposed systematic method of optimal blank design is found to be effective in the practical forming processes.

• 소성∙가공
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• 제9권5호
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• pp.526-532
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• 2000

Springback simulation is receiving increasing attention throughout the automotive industry and the academic world. The knowledge of the real springback of stamped parts can help the stamping technicians to modify the process parameters or die geometry in order to reduce the shape defect. This paper presents the results of springback simulation after aluminium square cup deep drawing and trimming simulation, and results of springback optimization using response surface method.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 춘계학술대회논문집
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• pp.57-61
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• 1999

Springback after forming is the critical factor affecting the product quality. It is very difficult to predict the amount of springback not only because of complex geometry and material characteristics of the stamping product but because the methodology has not been established. In this study springback mechanism is introduced and experimental tryout and computer simulation are carried out for die design of automotive rear side frame. Futher springback was verified by comparing the result of computer simulation with the measured tryout result.

• 한국유변학회:학술대회논문집
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• 한국유변학회 2001년도 Australian-Korean Rheology Conference 2001
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• pp.164.2-164
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• 2001