• 소성∙가공
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• 제13권7호
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• pp.586-593
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• 2004

A terminal pin, which is a part of high-voltage capacitors, has a plate-shaped head section with thickness of 0.8mm. 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 study, 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 lateral 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, in this study, three dimensional finite element analyses were applied to the lateral upsetting process in order to determine a proper diameter and height of the cylindrical billet. Once the geometry of the initial billet was determined, intermediate forging processes were designed by applying cold forging guidelines and the designed process sequence was verified by two dimensional finite element analysis. In addition, cold forging tryouts were conducted by using a die set, which was manufactured based on the designed process and finally we found that the part qualities were improved by the proposed cold forging process.

• 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.

• 대한기계학회논문집
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• 제13권3호
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• pp.345-352
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• 1989

본 연구에서는 3차원 변형형상을 갖는 소재에서 상하금형면의 마찰이 다른 경우에, 작각주 소재와 비직각주 소재(non-prismatic block)에 대해서 적용할 수 있는 동적 가용 속도장(kinematically admissible velocity field)을 유도해 내고자 한다.이론계산에 있어서 가공경화를 고려하기 위해 소성변형 영역을 유한개의 요소들로 나누고 이들 각 요소에 대해서 유효변형도, 유효응력을 계산하여 에너지 소비율을 계산하였다.

• 한국산학기술학회논문지
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• 제11권1호
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• pp.49-54
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• 2010

자동차의 A.C 제너레이터(alternating current generator) 부품으로 사용되는 로터폴(rotor pole)을 가공할 때는 트랜스퍼온간단조금형(transfer warm forging die)으로 성형한다. 소재를 온간가공 영역으로 가열한 후 즉시 금형안으로 이송시켜 제1스테이지(1st stage)에서 업세팅가공(upsetting work)하고 제2스테이지(2nd stage)로 이송하여 측방압출(lateral extrusion)가공을 한다. 이때 측방압출 스테이지의 금형에서 다이블록(die block), 다이부싱(die bushing), 센터펀치(center punch), 사이드펀치(side punch)의 접촉면이 압출시의 과혹(過酷)한 조건에 견디지 못하여 쉽게 마멸(abrasion)되어 금형수명(die life)을 단축시키고 있다. 이 때문에 생산량 감소로 인한 납기지연, 금형의 수리보수시간 과다, 제품의 정밀도 저하 등의 문제점이 발생되고 있다. 이러한 문제점을 해결하기 위하여 금형재질 선정과 열처리 작업 싸이클 개선, 방전가공시의 트러블 해소, 핵심부품의 구조변경 등을 연구하여 금형수명을 40~50% 연장 하고자 하였다.

• Journal of Magnetics
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• 제2권3호
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• pp.67-71
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• 1997

A new hot-forming process has been studied to produce anisotropic Nd-Fe-B based magnets from melt-spun ribbons. The ribbon fragments were inserted in a Cu tube and hot-deformed together with one-stroke. At a height reduction ratio of 0.44, the melt-spun ribbons were densified into a magnet with a density of 7.14 g/cm3, and showed a (BH)max of 14.6 MGOe. With further deformation, the magnets were plastically deformed with Cu tubes in the lateral direction, and crystallographic anisotropy was introduced. The magnets with a height reduction ratio of 0.75 exhibited magnetic properties of (BH)max = 32.1 MGOe, Br = 11.7 kG, and iHc = 10.6 kOe. This process shows the possibility that the conventional hot-pressing and subsequent die-upsetting for anisotropic magnets can be simplified into a one-step process.