• 동력기계공학회지
• /
• 제6권3호
• /
• pp.31-35
• /
• 2002

Brake tube is considered one of the most important parts in automobile. The shape of brake tube end has a great influence on the function of brake, and the quality and productivity of brake tube have relation to die design. The forming process of brake tube end is performed by hydraulic press forming machine. In this paper, the forming processes of tube end for automobile is analyzed and designed to make the optimal form of brake tube end. Also, finite element analysis has been carried out using $DEFORM^{TM}% 3D to predict the optimal shape of brake tube end and the results obtained showed the optimal length between punch and chuck is $1.0{\sim}1.2mm$. The shape of tube end is in good agreement with the finite element simulations and the experimental results.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2000년도 춘계학술대회논문집
• /
• pp.119-122
• /
• 2000

Dynamic deformation of metallic materials mostly accompanies substantial amounts of deformation heat. Since the flow stress of deformation is sensitive to temperature implication of heat due to plastic work is essential to the evaluation of constitutive relations. In this study a series of compression tests were conducted for SAF 2507 super duplex stainless steel and the accumulation of deformation heat was calculated through numerical integration method. Isothermal flow surfaces were deduced from subsequent logarithmic interpolation. Simple closed die forging process was analyzed and optimized with commercial FEM code applying both raw and calibrated material database.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2002년도 추계학술대회 논문집
• /
• pp.53-57
• /
• 2002

Brake tube is considered one of the most important parts in automobile. The shape of brake tube-end has a great influence on the function of brake, and the quality and productivity of brake tube have relation to die design. The forming process of brake tube-end is peformed by hydraulic press forming machine. In this paper, the forming processes of tube-end for automobile is analyzed and designed to make the optimal form of brake tube-end. Also, finite element analysis has been carried out using DEFORM-3D$\^$TM/ to predict the optimal shape of brake tube-end and the results obtained showed the optimal length between punch and chuck is 1.0 ∼ 1.2mm. The shape of tube-end is in good agreement with the finite element simulations and the experimental results.

• 한국전자통신학회논문지
• /
• 제6권3호
• /
• pp.405-410
• /
• 2011

단조산업에서의 철강제품의 열처리는 산업의 근간이 되며 제품경쟁력에 아주 중요한 부분을 차지한다. 열처리를 수행하는 열처리로에서의 버너제어는 연료인 LNG가스의 절감뿐만 아니라 균질한 열처리를 요구하는 제품 경쟁력에 막대한 영행을 준다. 본 연구는 열처리로에서의 버너제어를 비례제어를 이용하여 수행하고, 그 결과가 에너지 절감뿐만 아니라 열처리로의 성능을 향상시키는 것을 보여준다.

• 소성∙가공
• /
• 제13권5호
• /
• pp.441-448
• /
• 2004

Heat treatment is one of the critical manufacturing processes that determine the quality of a product. This paper presents experimental and analytical results for the quench of a ring gear in stagnant oil. The goal of this study is to develop heat transfer predicting model in an overall analysis of the quenching process, Thermal conductivities which are dependant on temperatures and convection coefficients which are obtained by inverse method are used to develop the accurate heat transfer model. The results of heat transfer model have a good agreement with experimental results.

• 보존과학회지
• /
• 제29권4호
• /
• pp.367-378
• /
• 2013

원삼국시대에 속하는 경기도 김포시 양촌유적에서 출토된 단조철부 5점과 주조철부 1점을 대상으로 미세조직 관찰과 비금속개재물 분석을 실시하였다. 단조품에 사용된 소재는 순철에 가까운 소재와 저탄소강이 사용되었고 성형 후 1점에만 담금질을 하였다. 주조품은 주철을 탈탄시킨 미세조직이 보여 주철탈탄 제강법이 적용된 것을 확인하였다. 비금속개재물 분석결과 철부는 고체저온환원법으로 제련하여 생산된 괴련철을 두드려서 제작하였다. FeO 함량이 $SiO_2$에 비해 비교적 높게 나타나 제련 시 노의 온도가 환원에 충분하지 못해 Fe의 회수율이 적었던 것으로 보이며 이 과정에서 광물에 포함된 K, P, Mg, Mn, Ti 등 불순물이 혼입되었다. Ca 함량이 높게 검출되는 곳이 있어 일부는 조제제로 석회물질을 넣었던 것으로 추정된다.

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

• 한국기계가공학회지
• /
• 제13권5호
• /
• pp.50-56
• /
• 2014

A technique based on the finite element method (FEM) is used in the simulation of metal cutting process. This offers the advantages of the prediction of the cutting force, the stresses, the temperature, the tool wear, and optimization of the cutting condition, the tool shape and the residual stress of the surface. However, the accuracy and reliability of prediction depend on the flow stress of the workpiece. There are various models which describe the relationship between the flow stress and the strain. The Johnson-Cook model is a well-known material model capable of doing this. Low-alloy steel is developed for a dry storage container for used nuclear fuel. Related to this, a process analysis of the plastic machining capability is necessary. For a plastic processing analysis of machining or forging, there are five parameters that must be input into the Johnson-Cook model in this paper. These are (1) the determination of the strain-hardening modulus and the strain hardening exponent through a room-temperature tensile test, (2) the determination of the thermal softening exponent through a high-temperature tensile test, (3) the determination of the cutting forces through an orthogonal cutting test at various cutting speeds, (4) the determination of the strain-rate hardening modulus comparing the orthogonal cutting test results with FEM results. (5) Finally, to validate the Johnson-Cook material parameters, a comparison of the room-temperature tensile test result with a quasi-static simulation using LS-Dyna is necessary.

• 열처리공학회지
• /
• 제28권5호
• /
• pp.239-249
• /
• 2015

Various amount of NbC carbide was intentionally formed in a matrix-type cold-work tool steel by controlled amount of Nb and C addition. And the effect of NbC addition on the mechanical properties was investigated. Four alloys with different Nb and C contents were cast by vacuum induction melting, then hot forging and spheroidizing annealing were conducted. The machinability of the annealed specimens was examined with 3 different cutting tools. And tensile tests at room temperature were conducted. After quenching and tempering, hardness and impact toughness were measured, while wear resistance was evaluated by disk-on-plate type wear test. The increasing amount of NbC addition resulted in degraded machinability with increased strength, whereas the absence of NbC also led to poor machinability due to high toughness. After quenching and tempering, the additional NbC improved wear resistance with increasing hardness, whereas it deteriorated impact toughness. Therefore, it could be found that a moderate addition of NbC was desirable for the balanced combination of mechanical properties.

• 대한기계학회논문집A
• /
• 제41권3호
• /
• pp.219-224
• /
• 2017

본 연구는 수송기계 축 등에 이용되는 캠 형상 부분만을 기존의 단조품인 SF45와 축 부분은 일반기계구조용 탄소강재인 SM45C를 직경 20 mm를 이용하여 이종 마찰용접을 수행하였다. 최적조건을 규명하기 위해 인장시험 등 용접품질과의 상관관계를 고찰하였고, 또한 최적조건에서 마찰용접 후 열처리를 시행하여 용접재(As-welded)와 후열처리재(PWHT)에 대한 회전굽힘 피로시험을 시행하였다. 결과적으로 두 이종재가 강한 혼합으로 계면에서도 개재물 및 산화막이 플래시로 토출되어 양호한 접합상태임을 확인하였다. 더욱이 모재(SF45)와 후열처리재의 피로한도 각각 180 MPa, 250 MPa로 나타났다. 이는 후열처리재가 SF45 모재에 비해 약 40 %의 피로수명이 향상되었음을 확인하였다.