• 한국해양공학회지
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• 제13권4호통권35호
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• pp.75-81
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• 1999

Roll forming process is simulated with a commercial FEM code LS-DYNA. The rolls are treated as rigid bodies rotating with a constant angular velocity. The strip and the rolls are modeled with 4-node plate elements. It is assumed that the nodes along the front end of the strip move along paths given by sine functions. It is found that the analysis can be applied to the optimal design of forming rolls. With these analyses, it is expected that forming defects can be avoided and process development efforts can be reduced.

• 대한기계학회논문집
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• 제12권4호
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• pp.712-720
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• 1988

본 연구에서는 프레스에 의한 축대칭 냉간단조품의 자동공정설계 및 금형설계 를 위한 대화식 프로그램인 "COLD-FORMING"과 "DESIGN-DIE"의 개발에 대하여 설명한다. 프로그램의 능력은 "COLD-FORMING"에서는 (1) 중실부품의 냉간단조에 있어서 작업 순 서의 해석과 각 단계에 포함된 개별작업의 인식 (2)중간 예비성형단계의 형상 및 치수 결정 (3) 각각의 성형단계에서의 성형하중계산 (4) 작업지시서를 위한 그래픽 출력 등 이며, "DESIGN-DIE"에서는 앞의 공정설계에서 구해진 결과를 이용하여 (1) 성형에 필 요한 다이세ㅌ의 형상, 재질 및 최적 치수를 결정 (2) 다이세ㅌ의 그래픽 출력 등을 할 수 있다. 및 최적 치수를 결정 (2) 다이세ㅌ의 그래픽 출력 등을 할 수 있다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.240-243
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• 1995

This paper describes the process design and forming limit of the forged hinge produec with the axial protrusion on the sheet metal. Process design is consisted of preform and forging process. In this case, the forged hinge product can be formed in a single workpiece without assembling another axial part to it. Process design of the forged hinge product is analyzed by the commercial FEM program. It is known that process design with perform process, shown by the FEM simulaion, can bring the forming limit of the forged hinge product to a great expansion.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1414-1417
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• 2003

In chemical forming process, mixed materials of LDPE, EVA and forming agent are used. However mechanical properties has been dropping remarkably through this forming process. In this study, Above materials(LDPE, EVA) were used in microcellular foaming injection process. And various effective factors in this process were selected by Axiomatic approach and systematically estimated by DOE(Design of Experiments). As a results, injection type and rate of mixing resins have more influence on forming rate than other factors.

• 한국기계가공학회지
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• 제12권2호
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• pp.41-48
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• 2013

Springback is a very typical dimensional discrepancy phenomenon, which occurs usually on the final stamping parts after the tool loading is removed. Variation of springback leads to amplified variations and problems during assembly of the stamped components, in turn, resulting in quality issues. The variations in the properties of the incoming material and process parameters are the main causes of springback variation. In this research, a robust design methodology which combines orthogonal array based experimental design and design space reduction skim to reduce the springback variation for advanced high strength steel parts in sheet metal forming is suggested. The concept of design space reduction is adapted in the experimental design setup to improve the quality of the obtained solution. The effectiveness of the proposed procedures is illustrated through a robust design of springback in metal forming process of a cross member of auto body.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.97-100
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• 2005

The purpose of this study is to apply the partial-size die forming process to actual segment head farming process of semi-ellipsoidal heads and to verify the availability of the suggested forming method. The initial curvature for the preliminary forming process was determined through anticlastic behavior of plate bending and the partial-size die for final forming was designed based on the results of springback analysis using F.EA. From the results of actual forming, it was concluded that die design was appropriate and proposed forming process would be successfully applied to actual forming jobs.

• 한국기계가공학회지
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• 제11권2호
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• pp.125-136
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• 2012

Wrinkle and fracture are two major defects frequently found in the sheet metal forming process. In this process there are more than one design attributes to optimize and several uncontrollable factors which cannot be ignored in determining the optimal values of design variables. Therefore, attempts to reduce defects through a traditional optimization technique are often led to failures. In this research, a new design method for reducing the wrinkle and fracture under uncontrollable factors is presented by using decision-making theory. To avoid the psychological difficulties in determining the scaling constants of the multi-attribute utility function by using the ordinary lottery questions, a pair-wise comparison procedure is adapted to avoid this problem. The effectiveness of the proposed method is illustrated through a robust design of sheet metal forming process of a side member of an automotive body.

• 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.

• 한국기계가공학회지
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• 제13권4호
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• pp.44-49
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• 2014

Roll forming technology has a problem in that it depends only on experience without accurate data in the actual field. To solve this problem, it is necessary to procure accurate data during the roll forming process. To this end, we determined the operating force and the material thickness by implementing several changes to those variables during an experiment. This study compares the FEA results and experimental results. Experimental results were used for the basic data of the design. The FEA results show that the roll forming machine is operating accurately and safely. And, a comparison of the results shows that the design of the automatic roll forming machine is operating in the right way. This design of an automatic roll forming machine will be helpful for many areas of the industry.

• 한국정밀공학회지
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• 제11권1호
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• pp.129-137
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• 1994

A rigid-viscoplastic finite element method has been used for modeling superplastic stretch/blow process design to improve thickness distribution. Punch velocity-time relationship of the stretch forming and pressure-time cycle of the blow forming for a given strain rate are calculated. A superplastic material is assumed to be isotropic and a plane-strain line element based on membrane approximation is employed for the formulation. The effects of the width, corner radius and height of the punch during stretch forming are examined for the final thickness distribution, and the process design to improve thickness distribution can be established.