• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 추계학술대회 논문집
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• pp.212-215
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• 2001

The bending process for the rectangular curved tube can be developed by the hot metal extrusion machine with the multiple punches moving in the different velocity. The bending phenomenon can be controlled by the two variables, the one of them is the difference of velocity at the die exit section by the different velocity of billets through the multi-hole container. The other is the difference by the different hole diameter. The results of the experiment show that the rectangular curved tube can be formed by the extrusion process and that the curvature of the curved product can be controlled by the velocity of punch and the diameter of container hole and that the defects such as the distortion of section and the thickness change of the wall of tube and the folding and wrinkling of thin tube did not happen after the bending processing by the extrusion bending machine.

• 대한기계학회논문집B
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• 제40권3호
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• pp.173-179
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• 2016

본 연구에서는 전산유체역학 상용코드를 이용하여 수소 개질기의 곡유로 채널형에 대하여 수치해석적 연구를 수행하였다. 선행연구모델에 대한 수치해석 모델과 다른 관 형태의 곡유로 채널을 모델링하여 수치해석적으로 비교하였다. 4가지 타입의 곡유로 채널형 개질기의 수치해석 결과 메탄올 전환율은 타입1~4까지 각각 45.0%, 45.3%, 45.6%, 45.6%로 ${\pm}0.6%$ 포인트의 차이로 거의 차이가 없음을 나타내었다. 유동특성에 대해서는 사각타입의 관과 45도 곡관의 각도를 가지는 타입2에서 상대적으로 가장 균일한 유동 특성 및 메탄올 농도 분포를 보였으며, 원형타입의 관과 90도 곡관의 각도를 가지는 타입3에서 상대적으로 가장 불균일한 유동특성 및 메탄올 농도분포 특성을 나타내었다. 곡유로 채널형 개질기의 설계 시에는 45도 곡관의 각도를 가지는 타입과 같이 사각타입의 관과 45에 가까운 곡관의 각도를 가지도록 설계해야 한다는 결과에 도달하였다.

• 설비공학논문집
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• 제3권1호
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• pp.11-25
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• 1991

The steady, incompressible developing 3-dimensional turblent flow in a square sectioned curved duct has been investigated by using partially-parabolic equation and Finite Analytic Method. The calculation of turbulent flow field is performed using 2-equation K-$\epsilon$ turbulence model, modified wall function, simpler algorithm and numerically generated body fitted coordinates. Iso-mean velocity contours at the various sections are compared with the existing experimental data and elliptic solutions by other authors. In the region of $0^{\circ}<{\theta}<71^{\circ}$, present results agree with the experimental data much better than the elliptic solution for the similar number of grid points. Furthermore, for the same tolerance, the present solution converges four times faster than the elliptic solution.

• 비파괴검사학회지
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• 제24권4호
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• pp.307-314
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• 2004

배관의 축방향 균열 검사를 위하여 원주 방향으로 진행하는 유도초음파 모드를 적용하였다. 배관의 곡률을 변수로 원주 유도초음파의 분산선도를 계산하였으며 이를 배관 검사에 적용하기 위하여 중수로 피더관의 곡관부 축방향 균열을 탐지에 적용하였다. 상대적으로 낮은 주파수에서는 Lamb 파 특성을 따르나 주파수가 증가함에 따라 평판의 경우, 즉 곡률이 무한대인 경우 첫 번째 $A_0$ 모드와 두 번째 $S_0$ 모드가 합쳐져서 Rayleigh 모드 형태로 변화한다. 한편 곡률을 가진 배관의 경우는 주파수가 증가하더라도 첫 번째 모드와 두 번째 모드가 합쳐지지 않았다. 이러한 해석을 기초로 하여 배관의 일종인 중수로 피더관 곡관부 축방향 결함을 탐지하기 위하여 사각 탐촉자를 사용하여 Rocking 원주 유도초음파 기법을 적용하였다. 원주 방향으로 유도파를 진행시키면서 인공 결함으로부터의 수집된 신호를 분석하여 진동 모드를 확인하였으며 두께 대비 10% 깊이의 notch도 검출할 수 있음을 확인할 수 있었다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 추계학술대회 논문집
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• pp.204-207
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• 2001

The bending process for the circular curved tube and rectangular curved tube with fins can be developed by the hot metal extrusion machine with the multiple punches moving in the different velocity. The bending phenomenon can be controlled by the two variables. The one of them is the difference of velocity at the die exit section by the different velocity of billets through the multi-hole container. The other is the one by the different hole diameter. The results of the experiment show that the circular curved tube with fins and rectangular curved tube with pins can be formed by the extrusion process and that the curveture of the product can be controlled by the velocity of punch and diameter of container hole and that the defects such as the distortion of section and the thickness change of the wall of tube the folding and wrinkling of thin tube and fins did not happen after the bending processing by the extrusion bending machine.

• 소성∙가공
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• 제13권8호
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• pp.663-670
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• 2004

The bending phenomenon has been known to be occurred by the difference of velocity at the die exit. The difference of velocity at the die exit section can be obtained by the different velocity of billets through the multi-hole container. The difference of velocity at the die exit can be controlled by the two variables, the one of them is the different velocity of extrusion punch through the multi-hole container, the other is the difference of hole diameter of muliti-hole container. In this paper the difference of hole diameter is applied. So it can bend during extruding products because of the different amount of two billets when billets would be bonded in the porthole dies cavity. And the bending curvature can be controlled by the size of holes. The experiments with aluminum material for the curved tube product had been done for circular or rectangular curved tube section. The results of the experiments show that the curved tube product can be formed by the extru-bending process without the defects such as distortion of section and thickness change of wall of tube and folding and wrinkling. The curvature of product can be controlled by shape of cross section and the difference of billet diameters. And it is known that the bonding and extruding and bending process can be done simultaneously in the die cavity by the experiments that rectangular hollow curved tubes could be extruded by porthole dies with four different size billets made of aluminum material. And it shows that bending phenomenon can happen during extruding with for different billets from the analysis by DEFORM-3D.