• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2009년도 추계학술발표대회
• /
• pp.43.2-43.2
• /
• 2009

Al-Mg 알루미늄 합금은 강도가 높고 성형성이 우수하여 수송기기 경량화용 소재로서 사용량이 증가하고 있다. 특히고강도 특성을 보이는 Al-Mg-Mn합금은 자동차, 선박및 철도차량등의 형재 및 판재로 그 사용량이 증가하고 있다. 또한 결정립을 미세화 시킨 Al-Mg-Mn합금판재의 경우에는 온간성형으로 복잡한 형상의 판재부품제조에 사용되고 있다. 연속주조공정인 Twin roll strip casting(TRC)은용탕으로부터 직접 판재를 생산할 수 있는 공정으로 주로 순알루미늄계열의 판재 생산에 사용되고 있으나 최근에는 고강도 판재의 저비용 생산을 위하여 고합금계 판재에 적용하는 연구가 수행되고 있다. 합금량이 높은 고강도Al-Mg계 합금의 TRC 주조시 고액공존구간이 커서 더욱 정밀한 공정제어가 필요하다. 또한 기존의 슬라브주조방식보다 높은 냉각속도로 주조가 가능하기 때문에 결정립 및 정출상의 미세화공정으로 응용되기도한다. 본 연구에서는 TRC공정을 기초로 주조시 열간 압연의효과를 동시에 부여하는 용탕직접압연공정을 개발하였으며 상용 고강도 알루미늄 합금인 5083합금 판재를제조하였다. 또한 기존 Al-Mg 합금에 Mn을 첨가하여 용탕직접압연함으로서 정출상의 크기 및 밀도를 제어하여 강도가 우수한 Al-Mg-Mn 합금판재를 제조하는 기술을 개발하였다. 용탕직접압연된 Al-Mg-Mn계 합금의 경우에 주조시 높은 냉각속도로 인하여 결정립이 미세하고 Al6Mn과 같은 미세한 정출상이 다량 형성되었으며, 최종압연 및 열처리에 의하여 높은 강도를 갖는 고강도 알루미늄 합금 판재의 제조가 가능하였다.

• 대한기계학회논문집A
• /
• 제26권9호
• /
• pp.1831-1841
• /
• 2002

The effect of a rubber mould on densification and deformation of aluminum alloy powder was investigated during warm isostatic pressing. The hyperelastic constitutive equations based on various strain energy potentials were employed to analyze deformation of rubber. The parameters in the strain energy potentials were obtained from experimental data for uniaxial and volumetric compression of Viton rubber at two warm temperatures. For elastoplastic response, the yield function of Shima and Oyane was implemented into a finite element program (ABAQUS) to predict compaction responses of metal powder during warm isostatic pressing. Finite element results were compared with experimental data for densification and deformation of aluminum alloy powder with/without a rubber mould under warm die pressing.

• 대한기계학회논문집A
• /
• 제27권11호
• /
• pp.1897-1906
• /
• 2003

A finite element analysis for near-net-shape forming of A16061 powder was performed under warm rubber isostatic pressing and warm die pressing. The advantages of warm compaction by rubber isostatic pressing were discussed to obtain a part with better density distributions. The shape of rubber mold was designed by determining a cavity shape that provides a desired shape of the final powder compact. To simulate densification and deformed shape of a powder compact during pressing, the elastoplastic constitutive equation based on yield function of Shima-Oyane was implemented into a finite element program(ABAQUS). The hyperelastic constitutive equation based on the Ogden strain energy Potential was employed to analyze nonlinear elastic response of rubber. Finite element results were compared with experimental data for Al6061 powder compacts under warm die pressing and warm isostatic pressing.

• 한국기계가공학회지
• /
• 제3권1호
• /
• pp.52-58
• /
• 2004

The material used is a commercial magnesium based alloy AZ31(Mg-3Al-1Zn)sheet with a thickness of 1.0mm. Uniaxial tension tests at warm temperature were carried out to investigate the material characteristics of K, m, and n. A warm drawing process with a local heating and cooling technique was developed to improve formability in this study with results of uniaxial tension tests because it is very difficult for Mg alloy to deform at room temperature by the conventional method. The die and blank holder were heated up, while the punch was water-cooled during deformation. FE simulations considering heat transfer were executed with Mg alloy to investigate the Improvement of deep drawability. For the assessment of improvement those were compare with the results of no considering heat transfer and room temperature.

• 소성∙가공
• /
• 제4권4호
• /
• pp.345-352
• /
• 1995

Warm deep drawing for optimum forming conditions to give the maximum drawing depth is investigated and compared with the results from experiments performed at room temperature. Experiments which draw square cups of STS 304 stainless steel sheet under the constant lubrication condition of teflon film are made both in a crank and hydraulic press for two kinds of specimens. The maximum drawing depth at warm forming condition reaches 1.4 times the drawing depth at room temperature in a crank press, whereas 1.6 times in a hydraulic press, and also more uniform distribution of thickness in case of warm deep drawn cup is observed. The effects of other factors on formability, such as forming temperature, speed of press and cooling of punch are examined and discussed.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1995년도 춘계학술대회 논문집
• /
• pp.204-208
• /
• 1995

Copper magnetron anode of a microwave-oven consists of an cylindrical outer-tube and various inner-vanes. The magnetron anode is produced by the complex process ; vane blanking, pipe cutting and sliver-alloy brazing of vanes. Recently, the backward extrusion process for forming vanes has been developed to avoid the complex procedures. The developed process is analyzed by using upper-bound elemental technique(UBET). In the UBET analysis, the upper-bound load, the configuration and the vane-height of final extruded product are determined by minimizing the total power consumption with respect to chosen parameters. To verify theoretical analysis, experiments have been carried out with pure plasticine billets at room temperature, using different web-thickness and number of vanes. The theoretical predictions both for forming load and vane-height are in reasonable agreement with the experimental results.

• 한국생산제조학회지
• /
• 제23권5호
• /
• pp.519-524
• /
• 2014

The use of light weight magnesium alloy offers significant potential towards improvement of the automotive fuel efficiency. However, the application of formed magnesium alloy components in auto-body structures is restricted due to the low formability at room temperature and lack of knowledge for processing magnesium alloys at elevated temperatures. In this study, a warm tensile test of magnesium alloys was performed to measure tensile strength and elongation. An improvement in formability was confirmed at increased temperatures above about $250^{\circ}C$. Car body warm forming technology was conducted for forming forming reinforced dash components of the magnesium alloy AZ31B sheet at elevated temperatures.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2008년도 춘계학술대회 논문집
• /
• pp.370-373
• /
• 2008

It is known that the temperatures of die, punch, holder and punch pad need to be kept different to get better formability in Mg sheet forming processes. Heating and cooling channels are usually equipped in each tool to assign different temperature. This study focused on the optimal design of the heating and cooling channels for a cross-shaped deep drawing die set. While the die and blankholder were heated to and kept at $250^{\circ}C$ by using heat cartridges, the punch and punch pad were kept at much lower temperature than that of the die and blankholder by water circulating through cooling channels. All the approaches were done by numerical analyses, aiming to maximize the cup height and to minimize the punch corner radius without any failure.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1992년도 춘계학술대회 논문집
• /
• pp.104-108
• /
• 1992

국소가열 가공방법은 종래 사용 되어온 온간,열간 가공의 경우와는 달리 프레스 성형의 응력조건 또는 양긱,열(온도)에 의한 재료 성질의변화 등을 고려하여, 가공하는 박판의 필요 부분을 선택적으로가열, 냉각 또는 두가지를 조합하여 처리하는 것이다. 온도 구배의 영향이 박판 성형의 공정에 많은 영향을 줌에도 불구하고 종래의 박판 성형가공은 주로 열을 고려하지않은 성형해석이 대부분이었고 열을 고려 하였다라도 대 부분이 실험에의존 한 방법이었다. 그러나 실제의 공정 설계에서 실험만을 통한 공정 변수의규명은 많은 노 력과 시간을 필요로 하기 때문에 컴퓨터를 통한 시뮬레이션의 필요성이 대두 되었다. 본 연구는 박판 축대칭 온도 구배와, 변형해석을 유한 요소적 방법을 통해 행하고 이를 실제 공정 설계에 적용할 수있도록 도움을 주고자 하는 데에 있다.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2007년도 춘계학술대회 논문집
• /
• pp.279-280
• /
• 2007

In this study, it is investigated that the effect of material properties such as various temperature, forming speed and strain rates on formability and forming limits of Mg alloy sheet in square cup deep drawing. Since the sheet metal forming of Mg alloy is perform at elevated temperature, the effect of strain rates related with the forming temperature and forming speed is very important factor for formability and forming limits. Therefore, the investigation for process variables is necessary to improve formability and forming limits. Also, the effects of strain rate and thickness transformation were studied by the experimental and FE analysis using the square cup deep drawing. The temperature, forming speed, and strain rates were investigated. Forming of Mg alloy takes consider into temperature, proper forming speed and strain-rate the formed parts were good without defects fur forming limits.