• 한국철도학회논문집
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• 제6권3호
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• pp.194-202
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• 2003

To make railway carbody light in weight has advantages at some aspects of both manufacturing and maintenance. Recently, railway carbodys of steel structure have been lightened their weight by using aluminum extrusion plate. for the additional lightening of railway carbody, an optimal design which maintains proper strength and minimizes weight must be achieved. Optimization which is used with finite element analysis for aluminum extrusion plate has the disadvantage of consuming much time. In this paper, the method of equivalent material property which is available to FEA code is established using the method of equivalent stiffness. This method for plate is expanded into the method for railway carbody structure with plates and shells. An objective function is established for maximum stiffness of unit aluminum extrusion plate using established method of equivalent material property. We performed an multi-objective optimization using the penalty function method. As a result, recommendable shapes and sizes of unit extrusion plate for under-frame of high speed train is presented.

• 소성∙가공
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• 제19권8호
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• pp.460-467
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• 2010

It was studied that two plates of aluminum can be welded by extru-riveting experiments with extru-rivet welding dies, and that the welding strength and metal flow on the welding section were analyzed by computer simulation according to the welding variable such as the diameter of extrusion insert dies. It was known by computer simulation that welding strength on the welding section of plates could be influenced by the diameter of extrusion insert dies. And it was known by experiments that two plates of aluminum can be welded on a spot point on aluminum plate by extru-rivet welding process, and that welding strength is higher and higher if the diameter of extrusion insert die is smaller and smaller, and that welding strength is the highest when diameter of extrusion insert dies is ${\emptyset}4.2$mm in the case that the diameter of rivet is 5 mm, when aluminum 5052 two plates with 1.5 mm thickness and one plate with 3mm thickness for rivet plate are used as welding material.

• 한국전산구조공학회논문집
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• 제16권2호
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• pp.133-140
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• 2003

샌드위치 판은 질량에 비해 높은 강성과 강도를 갖고 있으므로 매우 효율적인 구조재로서 폭넓게 쓰이고 있다. 알루미늄 압출 샌드위치 판의 적절한 설계를 위하여는 역학적 거동 해석이 선행되어야 하나, 아직 이에 대한 연구는 미비한 상태이다. 코어가 채워져 있지 않은 중공 단면(hollow section)인 샌드위치 판의 역학적 거동 해석에는 일반적으로 상세 유한 요소 해석을 하게되나, 이는 모델링과 해석에 많은 시간이 소요된다. 본 논문에서는 트러스(truss) 형상의 심재를 갖는 샌드위치 구조 압출재를 이방성의 판으로 치환하여 해석하는 방법을 제시하였다 적절한 이방성 후판으로의 치환을 위해 등가의 강성을 평가하는 방법을 제안하였으며, 이 등가의 강성을 판 이론에 적용하여 균일 분포 하중을 받는 사변 단순지지 조건의 알루미늄 압출재에 대한 처짐과 응력에 대해 간이 해석식을 개발하였다. 아울러 상용 유한 요소 프로그램을 이용하여 계산한 결과와 비교한 결과 제시한 간이식의 높은 정도와 효율성이 입증되었다.

• 한국주조공학회지
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• 제34권3호
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• pp.87-93
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• 2014

Thixo-extrusion of semi-solid 7075 aluminum alloy and the mechanical properties of its extrudates were investigated. The semisolid alloy was prepared by a cooling slope cast. In other to perform thixo-extrusion, semi-solid 7075 aluminum alloy billets were reheated at the reheating conditions reported in a previous study. The maximum extrusion pressure in thixo-extrusion was 615MPa. This was lower than that of conventional hot extrusion ($P_{max}=940MPa$) at the same extrusion conditions due to the increased fluidity of the alloy billet in the semi-solid state. The values of Rockwell hardness (scale B) at the extrusion direction of the as thixoextruded bar were 48~53HRB and the difference in Rockwell hardness between the transverse direction and the extrusion direction was 5HRB or less. The results show that thxio-extrusion of semi-solid 7075 Al alloy improves the workability and anisotropic with the extrusion direction compared with hot extrusion of the conventional alloy.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.265-268
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• 2003

In the extrusion process, the working material is forced to flow through a die with the desired profile. In general, the width of an extruded section is limited to about an inch less than the diameter of the round billet. But through the lip die, material is spreaded to produce a wider extruded section than the diameter of round billet. In this study, the extrusion process of an aluminum plate using the lip die is investigated. The width of the extruded plate is 450mm that is formed from the round billet with a diameter of 250mm. The flow characteristic through the lip die is considered to produce the wide-extruded plate with a small billet using rigid plastic FE analysis. Based on the result of FE analysis, new designs of lip die are proposed.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 제5회 압출 및 인발가공 심포지엄
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• pp.1-6
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• 2002

In the extrusion process, the working material is forced to flow through a die with the desired profile. In general the width of m extruded section is limited to about an inch less than the diameter of the round billet But through the lip die, material is spreaded to produce a wider extruded section than the diameter of round billet. In this study, the extrusion process of an aluminum plate using the lip die is investigated. The width of extruded plate is 450nm that is formed form the round billet with a diameter of 250mm. The flow characteristic through the lip die is considered to produce the wide-extruded plate with a small billet.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 추계학술대회논문집
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• pp.115-119
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• 2004

In the extrusion process, the working material is forced to flow through a die with the desired profile. In general, the width of an extruded section is limited to about an inch less than the diameter of the round billet. But through the lip die, material is spreaded to produce a wider extruded section than the diameter of round billet. In this study, the extrusion process of an aluminum plate using the lip die is investigated. The width of the extruded plate is 450mm that is formed from the round billet with a diameter of 250mm. The flow characteristic through the lip die is considered to produce the wide-extruded plate with a small billet using rigid plastic FE analysis. Based on the result of FE analysis, an optimized design of the lip die is then proposed.

• 소성∙가공
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• 제13권5호
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• pp.422-428
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• 2004

At present, the design of extrusion dies and operation in extrusion companies are primarily based on trial and error. The experience of the die designer, the press operator and the die corrector determine the performance of the extrusion die and the efficiency of the process. In order to produce defect-free products of desirable quality in terms of strength, surface quality and geometrical dimensions, it is important to obtain more knowledge of the processes that occur during extrusion. Recently, to reduce the costs of designing and manufacturing of extrusion dies, and to ensure the quality of the extruded products, numerical simulation for extrusion processes such as FEM (finite element method) is applied increasingly and becomes a very important tool for the design and development of new products. However, most of the studies about FE simulation have been accomplished for simple geometry and low extrusion ratio in the filed of steady metal flow conditions. The extruded products of AI alloy in industrial practice involve complicated sectional geometry. This study was designed to reduce the time of die design and manufacturing in the extrusion process using FEM simulation. FEM simulations of extrusion process were performed in non-steady states conditions by changing weld plate included in extrusion die set. Product which was employed in this study is heat sink that has been used in the parts of heat exchanger of electric circuits. It is generally applied for aluminum or its alloys due to heat efficiency and easy production of complicated shapes, and manufactured by extrusion process. The simulated results showed that weld plate shape in extrusion dies influences meta] flow and dimensional accuracy of products.

• 대한기계학회논문집A
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• 제35권2호
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• pp.213-221
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• 2011

알루미늄 재질의 도시철도차량 차체의 경량화를 위해 이중 판재구조로 이루어진 철도차량용 알루미늄 압출재의 최적설계를 수행하였다. 위상최적설계 기법을 이용하여 알루미늄 차체에서 가장 큰 중량을 차지하는 하부 프레임 베이스 플레이트의 경량화된 위상을 도출하였고, 이를 기반으로 압출재 부재별 치수 최적화를 수행하였다. 하부 프레임 다음으로 큰 중량을 차지하는 측면 프레임 압출재에 대해서는 치수 최적화를 통하여 경량설계를 수행하였다. 최적설계안과 현재 설계의 최대발생응력과 최대 변형량을 비교하여 최적설계결과의 타당성을 검증하였다. 이 과정을 통하여 언더프레임과 사이드프레임의 중량을 현재보다 평균 12% 줄일 수 있었고, 차체 전체로는 8.5%의 경량화 효과를 얻었다.

• 한국주조공학회지
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• 제34권4호
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• pp.123-129
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• 2014

This work presents the results of a thixo-extrusion process applied to aluminum alloy and and reheating characteristics of semi-solid A356 Alloy using have been discussed. The reheating experiment was performed using an electric resistance furnace and multi-stage heating for uniform reheating. The thixo-extrusion was performed at the optimal reheating conditions of the semi-solid A356 alloy, the the extrusion conditions were an extrusion ratio of 33 and ram speed of 6 mm/sec. The results showed that the thixo-extrusion of semi-solid A356 alloy fabricated by the cooling slope reduced the extrusion pressure by 180% in comparison with hot extrusion, and that a sound extrusion could be obtained in spite of the same extrusion ratio and strain rate.