• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 춘계학술대회 논문집
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• pp.31-34
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• 2004

A new extrusion process of the circular section product with helical fins could be developed by using rotating extrusion dies. The twisting of extruded product is caused by the twisted conical die surface connecting the die entrance section and the die exit section linearly. But, until now, because the process has used fixed extrusion dies, it needs high pressure in order to twist billet and form fin shape on the surface of billet. So, during extruding billet, in order not to twist billet, the extrusion dies is needed to rotate itself instead of twisting billet. And in order to rotate dies, the shape of inside contour of extrusion dies must have conical type with twisted Inclined die surface connecting the die entrance section and the die exit section linearly. The results of experiments show that, in spite of using twisted extrusion dies, twisting of the billet should not happen because of rotating dies in the opposite direction of twisting direction of billet during extruding billet, and, from the results, it shows that it can decrease the power of extrusion pressure and could prevent crack of teeth for fin forming.

• 한국정밀공학회지
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• 제10권2호
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• pp.30-39
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• 1993

The study is concerned with the thermo-viscoplastic finite element analysis of nonisothermal hot container extrusion through conical dies. The problem is treated as a non-steady state incorporating the nonisothermal heat transfer analysis. The analysis of temperature distribution includes heat transfer though the boundary surface including conduction, convection and radiation. The analysis of heat transfer is decoupled with the analysis of deformation and the material interaction is considered through iteration procedure. The effect of important process parameters including die angle and extrusion ratio in the process is investigated. Due to the geometric feature for the container extrusion through conical dies, automatic remeshing is mandatory. Automatic remeshing is achieved by introducing the modular remeshing technique.

• 대한기계학회논문집
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• 제9권4호
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• pp.452-462
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• 1985

본 논문에서는 금형의 형상과 단면 감소율등이 이에 미치는 영향을 조사하였 다. 이론과의 비교를 위해서 풀림처리된 특수강 소재인 SCM4로 실험을 행하였다. 압출하중은 로드셀(loadcell)로 측정하였으며 수치계산에서 구해진 속도장과 실제속도 장의 차이를 살펴보기 위해서 시편단면에 포토에칭(photoetching)한 압출시킬 시편의 그리드변형을 강소성유한요소법으로 계산한 그리드패턴과 비교 검토하였다.

• 소성∙가공
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• 제14권2호
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• pp.160-167
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• 2005

In the present study about extru-bending of angle product, the bending of extruded angle products with the $'\Lambda'$ section and 'ㄱ', section can be obtained using two extrusion billets by the hot metal extru-bending machine with the two punches moving in the different velocity. The bending curvature can be controlled by the different velocity of billets through the two-hole container. This paper describes simulations and experiments of extru-bending process that can make bending during extruding by the difference of stem velocities. And they are applied to two kinds of dies, that is, one of them is conical dies with symmetry $'\Lambda'$ section and the other one is conical dies with asymmetry 'ㄱ' section. The results of the forming simulation by $DEFORM^{TM}-3D$ and results of experiments show that the bending phenomenon at the die exit during extrusion can be obtained with two extrusion billet by the two stems moving in the different velocity. And it was known that it is possible to design the structure of conical cavity of extrusion dies and to control the curvature of product through the simulation and experiment of extru-bending process.

• 대한기계학회논문집A
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• 제25권10호
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• pp.1541-1550
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• 2001

This paper describes experimental investigations in the direct extrusion of copper clad aluminum rods through conical dies. Composite materials consist of two or more different material layers. Copper clad aluminum composite materials are being used fur economic and structural purposes and the development of an efficient production method of copper clad aluminum composite material rods by extrusion is very important, It is necessary to know the conditions in which successful uniform extrusion ,and sound cladding may be carried out without any defects in the direct extrusion. There are several variables that have an influence on determining a sound clad extrusion. In order to investigate the influence of these parameters on the hot direct extrudability of the copper clad aluminum composite material rods, the experimental study have been performed with various extrusion temperatures, extrusion ratios and semi-cone angles of die. Subsequently, the microscopic inspection of interface bonding is carried out for extruded products. By measuring hardness, along extrusion way of products, a variation of hardness has been discussed. Proportional flow state has been considered by measuring radius ratio of Cu sleeve and Al core before and after extrusion.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 제5회 압출 및 인발가공 심포지엄
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• pp.63-70
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• 2002

The purpose of the present study is to propose a new way of manufacturing curved metal tubes with arbitrary sections and way of eliminating the conventional bending defects such as thinning and thickening, in the wall of tube, distortion of the section, and wrinkling and folding on the surface by the extrusion bending process that can extrude and weld together one or more billets inside dies cavity, and can bend them during extrusion due to the gradient of extrusion velocities controlled by the eccentricity of the cavity sections between the entrance and the exit of the eccentric conical extrusion bending dies and conical plug, or by the relative size of the holes of multi-hole container, or by the relative moving velocity of multi-punches.

• 대한기계학회논문집
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• 제7권2호
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• pp.168-174
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• 1983

The study is concerned with an analysis on the hydrofilm extrusion through conical dies. The upper bound method is adopted for the analysis of metal deformation in connection with hydrodynamic lubrication theory for the lubricant in order to determine the extrusion pressure for some variables such as reduction of area, die cone angle. In the upper bound method, a kinematically admissible velocity field is found by assuming proper streamlines and applying the flow function concept to the region of plastic deformation. The effect of work hardening is incorporated approximately by calculating the strains at the exit of the die. The experiments are carried out with the commercially pure aluminium for some chosen variables at room temperature. It is shown that the theoretical predictions are in good agreement with the experimental observations.

• 한국안전학회지
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• 제15권4호
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• pp.28-34
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• 2000

Copper clad aluminum composite materials are being used for economic and structural purposes, The development of an efficient production method of copper clad aluminum composite material rods by extrusion is very important. This paper describes experimental investigations in the direct extrusion of copper clad aluminum rods through conical dies. There are several parameters that have an influence on determining a sound clad extrusion. These variables are extrusion temperature, extrusion ratio, semi-cone angle of die, extrusion force, extrusion velocity, friction of between the container and billet, percentage of copper used and ratio of flow stress of copper to aluminum. In order to investigate the influence of extrusion temperature, extrusion ratio, semi-cone angle of die on the hot direct extrudability of the copper clad aluminum composite material rods, the experimental study have been performed with these variation.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.759-765
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• 2000

A composite material consists of two or more different material layers. Copper clad aluminum composite materials are being used for economic and structural reasons. This study is concerned with experimental investigation in the direct extrusion of copper clad aluminum rods through conical dies. The suggestion are given for the proper extrudability of copper clad aluminum rods via hot direct extrusion. This paper presents the variation of flow state and hardness at a variable of extrusion ratio and semi-angle of die. By measuring after and before extrusion radius ratio of Cu sleeve and Al core, proportional flow state has been considered. And also by measuring hardness, through extrusion way, a variation of hardness has been considered.

• 소성∙가공
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• 제6권4호
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• pp.346-356
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• 1997

The fiber orientation distribution and interface bonding in hot extrusion process have an effect on the maechanical properties of metal matrix composites(MMC's). Aluminium alloy matrix composites reinforced with alumina short fibers are fabricated by compocasting method. MMC's billets are extruded at high temperature through conical and curved shaped dies with various extrusion ratios and temperature. This present study was directed to describe the systematic correlation between extrusion die shape and subsequent results such as fiber breakage, fiber orientation and tensile strength to hot extruded MMC's billet. Extrusion load, tensile strength and hardness for variation of extrusion ratios and temperature are investigated to examine mechanical properties of extruded MMC's SEM fractographs of tensile specimens are observed to analyze the fracture mechanism.