• 한국기계가공학회지
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• 제11권4호
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• pp.173-179
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• 2012

In recent years, Magnesium(Mg) and its alloys have become a center of special interest in the automotive industry. Due to their high specific mechanical properties, they offer a significant weight saving potential in modern vehicle constructions. Most Mg alloys show very good machinability and processability, and even the most complicated die casting parts can be easily produced. In this study, Microstructure, Vickers hardness and tensile tests were examined and performed for each specimen to verify effects of forming conditions. Also to verify upsettability and forming limit of the specimen at room temperature and elevated temperature, upsetting experiments were performed. For comparison, experiments at elevated temperature were performed for various Mg alloy, such as AZ31, AZ91, and AM50. The experimental results were compared with those of CAE analysis to propose forming limit of Magnesium alloys.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 춘계학술대회논문집
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• pp.88-94
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• 1999

This study is to investigate the effects of warm deep drawing with steel sheets of SCP3C and SCP1 for improving deep drawability. Experiments were carried out in various working conditions such as forming temperature and lubricantion. The effect of lubricantion and temperature on drawabillity of steel sheets as well as thickness distribution of drawn oil pan were examined and discussed. One step forming at room temperature and uniform distribution of thickness was achieved at optimum formability for lubricantion. The optimum forming temperature was obtained that both the die and the blankholder were heated to 10$0^{\circ}C$ while the punch was cooled by circulating coolant of $0^{\circ}C$.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.116-119
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• 2007

The application of light weight materials, such as aluminum alloy, has been limited due of their poor formability. Especially, aluminum alloy tube has limited expansion capability at most 15% at room temperature. New manufacturing process, called hot air forming, is introduced to apply aluminum tube to the automotive suspension components which have complex shape and require high expansion ratio about 40%. The process is carried out at the elevated temperature above $500^{\circ}C$, so numerous material properties and process parameters related to the high temperature should be investigated and determined to get a sound product. In this study, the effect of thermal properties and forming parameters such as the temperature of tool, axial feeding and gas pressure are analyzed by using explicit finite element method.

• Advances in aircraft and spacecraft science
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• 제3권1호
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• pp.29-43
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• 2016

Composite materials are rapidly gaining popularity as an alternative to metals for structural and load bearing applications in the aerospace, automotive, alternate energy and consumer industries. With the advent of thermoplastic composites and advances in recycling technologies, fully recyclable composites are gaining ground over traditional thermoset composites. Stamp forming as an alternative processing technique for sheet products has proven to be effective in allowing the fast manufacturing rates required for mass production of components. This study investigates the feasibility of using the stamp forming technique for the processing of thermoplastic, recyclable composite materials. The material system used in this study is a self-reinforced polypropylene composite material (Curv$^{(R)}$). The investigation includes a detailed experimental study based on strain measurements using a non-contact optical measurement system in conjunction with stamping equipment to record and measure the formability of the thermoplastic composites in real time. A Design of Experiments (DOE) methodology was adopted to elucidate the effect of process parameters that included blank holder force, pre heat temperature and feed rate on stamp forming. DOE analyses indicate that feed rate had negligible influence on the strain evolution during stamp forming and blank holder force and preheat temperature had significant effect on strain evolution during forming.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1994년도 박판성형기술의 진보
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• pp.1-9
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• 1994

Three recent developments made at Rensselaer in sheet material forming processes are briefly reviewed in this paper. These advances represent three broad disciplines of Process Simulation, Forming Processes, and Computer-Aided Measurement Methods. The first development deals with simple and quick computer simulation of 2D sheet forming process without depending on popular finite element analysis methods. An analytical method based on a thin shell theory accounts for bending and unbending effects, and is capable of simulating practical sheet metal forming processes under the plane strain condition. The second area is concerned with innovative methods to improve formability of sheet materials by temperature gradient forming. The drawing limit is increased by such an improved temperature gradient forming process. The third and final area deals with a totally new experimental technique to capture 3D geometry data and measure strain distributions of sheet metal parts using a digital 35mm SLR camera.

• 대한기계학회논문집A
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• 제37권7호
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• pp.913-919
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• 2013

본 연구에서는 마그네슘 합금 AZ31을 적용한 배터리 팩 케이스를 개발하여 자체 진동 및 외부 충격으로부터 배터리를 보호하도록 하며, 기존 스틸 소재 대비 50% 이상 경량화하여 친환경 기술개발을 목적으로 한다. 또한, 제품의 복잡한 형상 및 마그네슘 소재의 특성으로 제품을 성형하기에는 힘든 측면이 많으므로 이를 해결하기 위해 마그네슘 합금소재의 온도별 최적성형조건을 제시하고자 한다. 즉 AZ31의 성형방법에 따라 상온, $230^{\circ}C$, $250^{\circ}C$ 및 $270^{\circ}C$의 4가지 조건하의 시험편으로 인장시험, 경도시험, 부식시험 및 피로시험 등을 실시하여 기계적 특성을 정량적으로 분석하였고, 또 FEM해석을 통하여 자동차 부품 배터리 팩 케이스 개발에 적용토록 하였다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.26-29
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• 2008

Recently, the hydroforming of high strength aluminum tubes has many studies and applications in manufacturing industry, especially in automotive industry. But high strength aluminum tube has limited expansion capability at most 15% at normal temperature. New manufacturing process, called hot air forming, is introduced to apply aluminum tube to the automotive sub frame components which have complex shape and require high expansion ratio about 40%. The process is carried out at the elevated temperature above $500^{\circ}C$, so numerous material properties and process parameters related to high temperature should be investigated and determined to get a sound product. In this paper, the hot air forming process of automotive sub frame was investigated. The effect of the forming parameters such as the temperature of tool, axial feeding and gas pressure are analyzes by using explicit finite element method.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.452-455
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• 2008

In the present study, blow forming characteristics of commercially roiled AZ31 alloy sheets were investigated. Two different kinds of AZ31 sheets were originally fabricated by using direct casting and strip casting methods respectively. Both sheets have similar grain sizes of about $7{\mu}m$ with a relatively equiaxed structure after rolling. A series of tensile tests were carried out to get flow behavior in terms of temperature and strain rate. Also, grain size effect was investigated by annealing as-received sheet at elevated temperatures. Elongation increased with temperature increment as well expected. However, the differences in tensile test condition did not give much difference in elongation even at the temperature range where a large elongation would be expected with such as fine grain of $7{\mu}m$. Blow forming experiments showed that forming condition did not result in higher difference in dome height. However, the interesting feature from this study was that formability of this AZ31 alloy got different with stress condition. Firstly, biaxial stress condition might result in lower temperature and strain rate dependencies compared to uniaxial tension results for both DC and SC sheets. Secondly, DC showed slower grain growth in uniaxial tension than in biaxial stress state while SC has much higher grain growth rage in uniaxial tension than in bulging.

• 소성∙가공
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• 제27권3호
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• pp.139-144
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• 2018

Many studies have been conducted on the process of forming magnesium alloy sheets to reduce the body weights of vehicles. Magnesium has a lower specific gravity than steel and also has a higher specific strength. Mg alloy sheets have low formability and a lot of springback due to their limited ductility and low young's modulus. As the temperature increases, the yield strength of the material decreases. Warm forming increases the formability and minimizes the springback of a material by heating it and the die to reduce the required load at forming. In this study, the temperature of the AZ31B sheet was controlled in order to reduce springback and increase formability. However, as the temperature increased, the deformation characteristics of the material changed and the radius of curvature of the material increased. The load and springback amount required for forming were analyzed according to the temperature and the bottoming force in the bending deformation.

• 대한기계학회논문집
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• 제14권5호
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• pp.1119-1128
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• 1990

본 연구에서는 박판의 프레스 성형에 관련된 열소성 문제를 해석할 수 있는 효과적이고, 신뢰도가 높은 수치적 방법을 개발하는 것이다. 박판 성형에서 변형과 열전달이 결합된 문제의 해석을 위하여 3차원 유한 요소 해석을 행하고 그를 이용하여 박판의 스트레치 성형 공정을 해석하였다. 해석 결과를 기존의 실험 결과와 비교하 여 본 해석의 타당성을 보이고, 재료 거동에 영향을 미치는 여러가지 공정 변수의 영 향을 검토하였다.