• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.139-143
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• 1996

The theoretical study of deformation behavior for continous extrusion process (CONFORM) is shown in this paper. The extrusion process is compared with a conventional route, side extrusion, considering extrusion ratios, flash gaps and coefficients of friction. In each case the distribution of strain and strain rate is predicted by using the finite element method. In this study simplifying assumptions on the deformation geometry are made to investigate the plastic flow occuring in the area of deformation of the Conform process.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.232-235
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• 1995

A side-extrusion model, meant for deeper understanding of the material flow in the CONFORM (continuous extrusion forming) of trub shaped aluminum profiles is presented. In order to get the desirded straight shape of the extrudate,every part of its cross-section must exit the die with the same velocity. Problem is assumed by plane strain UBET-model to analyze it in a simplified way. This has been done by studying the side-extrusion through a two -hole die face. The flow is balanced by determining the optimum lengths of the bearing lands, i.e., those lengths which result in equal exit velocities of the extrudates. Furthermore, the material flow, as influenced by the punch velocity, has been investigated.

• 한국정밀공학회지
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• 제16권11호
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• pp.116-121
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• 1999

Since the material flow near the die part in CONFORM (Continuous Extrusion Forming) process is similar to that of side-extrusion, the side-extrusion model of tube shaped aluminum profiles was studied for the die design in CONFORM process. In this paper, the effects of process parameters in the side -extrusion through a two-hole die face, such as material flow, height and thickness of the tube, velocities of punch and lengths of bearing land were investigated using UBET program and DEFORM commercial FEM code. The optimum lengths of the bearing lands and punch velocities for obtaining the straight shape products required were determined.

• 한국정밀공학회지
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• 제18권6호
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• pp.174-181
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• 2001

An upper bound elemental technique(UBET) has been carried out to predict the forming load, the deformation pattern and the extrude length of the lateral extrusion of a spider for the automotive universal joint. For the upper bound analysis, a kinematically admissible velocity field(KAVF) is proposed. From the proposed velocity field, the upper bound load, the deformation pattern and the average length of the extruded billets are determined by minimizing the total energy consumption rate which is a function of unknown velocities at each element. Experiments are carried out with antimony-lead billets at room temperature using the rectangular shape punch. The theoretical prediction of the forming load, the deformation pattern and the extruded length are good in agreement with the experimental results.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.1129-1133
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• 2001

An upper bound elemental technique(UBET) has been carried out to predict the forming load, the deformation pattern and the extruded length of the lateral extrusion of a spider for the automotive universal joint. For the upper bound analysis, a kinematically admissible velocity field(KAVF) is proposed. From the proposed velocity field, the upper bound load, the deformation pattern and the average length of the extruded billets are determined by minimizing the total energy consumption rate which is a function of unknown velocities at each element. Experiments are carried out with antimony-lead billets at room temperature using the rectangular shaped punch. The theoretical prediction of the forming load, the deformation pattern and the extruded length are good in agreement with the experimental results.

• 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.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1997년도 춘계학술대회 논문집
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• pp.54-61
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• 1997

Furthermore the rothor pole, with a solid type, manufactured by cold forging process at present should dmploy 3 press lines which consist of total 7 processes. Since A.S.B. treatment is prerequisite for the press line, the 3 times of A.S.B. treatment requires a long lead time, with little contribution to the reduction in cost. The author has investigated, through this researach, the possibility of a new forging method for a rotor pole production with (1) 2 pass instead of 3 press lines (2) only one A.S.B. treatment instead of 3 ones (3) solid type instead of sectional type, and (4) improvment of material property during process using a modified forging process and a specially designed die.

• 한국지반공학회논문집
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• 제17권1호
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• pp.99-107
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• 2001

일반적으로 샌드파일 설치로 인해 파일주변지반은 교란되어 스미어 영향과 배수저항에 의해 압밀지연 현상이 발생하는 것으로 알려져 있다. 특히 예민한 점성토 지반일 경우 교란정도가 크며, 틱소트로피현상이 지연될 경우 지지력 및 압축특성은 불리하게 된다. 본 연구에서는 원지반 특성이 파악된 채취시료를 이용하여 완전 교란조건에서의 실내모형시험과, 염분농도변화에 의한 실내역학시험을 실시하였다. 실내모형시험 결과 낮은 하중단계에서의 압밀계수는 비교란 시료의 특성과 유사하게 나타났으며, 염분농도 증가에 따라 일축압출강도가 증가하고 강도회복은 빠르며 압축지수는 작게 나타났다. 결과적으로 점성토지반 간극수중 염분농도는 강도증대와 압축특성 변화에 영향을 주며, 틱소트로피 증대의 영향요소가 적은 담수지반에서 샌드파일을 시공할 경우 발생하는 과다침하의 한 원인으로 여겨지는바, 이와 같은 요인은 측방유동에 의한 침하거동과 함께 고려하여야 할 영향요소로 파악되어야 할 것으로 판단된다.