• Design & Manufacturing
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• 제16권4호
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• pp.1-6
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• 2022

Fine blanking is a press processing technology that can process most of the product thickness into a smooth surface with a single stroke. In this fine blanking process, shear is an essential step. The punches and dies used in the shear are subjected to impacts of tens to hundreds of gravitational accelerations, depending on the type and thickness of the material. Therefore, among the components of the fine blanking mold (dies), punches and dies are the parts with the shortest lifespan. In the actual production site, various types of tool damage occur such as wear of the tool as well as sudden punch breakage. In this study, machine learning algorithms were used to predict these problems in advance. The dataset used in this paper consisted of the signal of the vibration sensor installed in the tool and the measured burr size (tool wear). Various features were extracted so that artificial intelligence can learn effectively from signals. It was trained with 5 features with excellent distinguishing performance, and the SVM algorithm performance was the best among 33 learning models. As a result of the research, the vibration signal at the time of imminent tool replacement was matched with an accuracy of more than 85%. It is expected that the results of this research will solve problems such as tool damage due to accidental punch breakage at the production site, and increase in maintenance costs due to prediction errors in punch exchange cycles due to wear.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 The Korea-Japan Plastics Processing Joint Seminar
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• pp.1-6
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• 2003

In injection molding of an optical disk, a toric lens, etc., their performance depends on the transcription preciseness of fine surface structure of a mold. However, transcription behavior has not been made clear yet, because transcription is made in very short time and the structure is very small. In this paper, transcription properties have been examined, by using V-grooves of various sizes. machined on mold surfaces, and the following results are obtained. (1) Transcription properties have been made clear experimentally and it was found that the mold temperature $T_D$ makes great influence on the transcription property and that compression applying time $t_c$ should be taken more than 2.0s for fine transcription. (2) A mechanical model of transcription process, in consideration with strain recovery due to viscoelastic property of polymer. is proposed. (3) Simulation results agree with experimental ones fairly well. It means that the transcription model is useful for estimation of transcription property in advance of an actual. injection molding.

• 한국산학기술학회논문지
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• 제12권2호
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• pp.565-570
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• 2011

본 연구는 파인 블랭킹(fine blanking) 프레스로부터 기능면으로 사용되는 100% 매끄러운 전단면을 얻는 파인 블랭킹 공정에서 다이 롤(die roll) 크기를 최소화하기 위한 목적으로 실험을 통해 다이 챔퍼(die chamfer) 형상에 따라 성형되는 제품의 다이 롤 크기 변화를 검토한 것이다. 다이 챔퍼가 다른 여러 가지 다이 편(die insert)을 제작하여 파인 블랭킹 실험을 실시한 후 다이 챔퍼 형상에 따른 다이 롤 크기를 측정 분석하여 두께 방향 다이 롤 크기의 경향을 파악하였다. 이 연구 결과는 파인 블랭킹 판재 성형에서 두께 방향 다이 롤 크기를 최소화하기 위한 다이챔퍼 설계에 유용하게 적용될 것으로 판단된다.

• Carbon letters
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• 제15권1호
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• pp.32-37
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• 2014

Multi-walled carbon nanotube (MWCNT)/epoxy composites are prepared by a vacuum assisted resin transfer molding (VARTM) method. The mechanical properties, fracture surface morphologies, and thermal stabilities of these nanocomposites are evaluated for epoxy resins with various amounts of MWCNTs. Composites consisting of different amounts of MWCNTs displayed an increase of the work of adhesion between the MWCNTs and the matrix, which improved both the tensile and impact strengths of the composites. The tensile and impact strengths of the MWCNT/epoxy composite improved by 59 and 562% with 0.3 phr of MWCNTs, respectively, compared to the epoxy composite without MWCNTs. Thermal stability of the 0.3 phr MWCNT/epoxy composite increased compared to other epoxy composites with MWCNTs. The enhancement of the mechanical and thermal properties of the MWCNT/epoxy nanocomposites is attributed to improved dispersibility and strong interfacial interaction between the MWCNTs and the epoxy in the composites prepared by VARTM.

• 한국전자거래학회:학술대회논문집
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• 한국전자거래학회 2001년도 International Conference CALS/EC KOREA
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• pp.105-109
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• 2001

성형의 종류 ◈금속 성형 ㆍ 스탬핑(Stamping) ㆍ 정밀 블랭킹(Fine Blanking) ㆍ 딥 드로잉(Deep Drawing) ㆍ 다이캐스팅(Die Casting) ㆍ 인베스트먼트 주조(Investment Casting) ㆍ 분말 야금(Power Metallurgy) ㆍ 인발(Wire Drawing) ㆍ 압출(Extrusion) ㆍ 단조(Forging) ㆍ ㆍ코이닝(Coining) ㆍ... ◈비금속 성형 ㆍ 사출(Injection) ㆍ 압축(Compression) ㆍ 블로우 성형(Blow Molding) ㆍ 진공 성형(Vacuum Molding) ㆍ 발포 성형(Foam Molding) ㆍ 피복(Encapsulation) ㆍ 회전식(Rotational) ㆍ 주조(Casting) ㆍ 적층(Laminating) ㆍ 압출(Extrusion) ㆍ...(중략)

• 대한기계학회논문집
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• 제14권1호
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• pp.54-71
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• 1990

본 연구에서는 세라믹 기계요소를 생산하기 위한 기초연구로서, 세라믹 사출 성형에 대한 기본적인 가공조건과 여러변수들을 고찰하고 가능한한 최대의 세라믹체적 비를 갖고 세라믹입자와 완벽한 융합을 이룰수 있는 최적의 결합제 구성과 세라믹입자 의 충진비율에 따른 혼합체(mixture)의 유동특성을 규명하여 사출성형의 적부를 판별 함과 동시에 그 훈련된 상태를 고찰하여 이후의 공정에서 불균일에 의한 결함이 발생 하지 않도록 정확한 성형조건을 제시하고자 한다. 또한 사출성형에 가장 적절한 혼 합체를 선정하여 탈지공정 및 소결을 행하고 각 공정에서의 부품의 수축률 및 결함을 관찰하여 그 결함의 원인 및 제거방법에 대하여 논의할 것이다. 본 논문에서 제시한 각 공정 및 고찰은 중요한 모든 변수들의 경향 및 특성을 다루었으며 정밀한 세라믹부 품의 신속한 생산을 위한 기초 연구로서 실제 산업체에 응용될 수 있을 것으로 사료된 다.

• 한국자기학회지
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• 제11권4호
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• pp.157-162
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• 2001

Sm-Co계 플라스틱 자석 제조를 위한 사출 성형용 컴 파운드의 제조법을 연구하기 위해 미세분말과 조대분말을 혼합하여 자성분말의 입도 변화, 배합비 및 부피분율에 따른 컴파운드의 유변학적 특성을 조사하였다. 조대분말의 평균입도가 증가하면 분말의 충진율이 증가하여 컴파운드의 점도가 감소하였다. 그러나 미세분말의 평균입도가 작아지는 경우, 미세분말들간의 응집성으로 인하여 오히려 점도가 증가하였다. 기계적으로 분쇄된 Sm-Co계 분말의 경우, 125~75 $\mu\textrm{m}$ 크기의 조대분말과 평균입도 4.9 $\mu\textrm{m}$인 미세분말을 혼합하여 제조된 컴파운드의 점도는 분말의 배합비에 의존하며 조대분말을 60%혼합한 경우 가장 낮은 점도를 나타냈다. 이는조대분말의 양이 60 %일 때 자성분말의 충진율이 최대가 됨을 의미한다. 자성분말의 부피분율에 따른 컴파운드의 점도는 유변학적 모델을 잘 만족시켰으며 사출 성형이 가능한 Sm-Co계 자성분말의 최대 부피분율은 약 66 %이었다.

• Design & Manufacturing
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• 제16권1호
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• pp.62-69
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• 2022

In the present study, the injection molding optimization of a large thick LH type elastic frames for the reduction of warpage was performed. Two kinds of fine and coarse finite element models were prepared to investigate the efficiency of analysis time and quality on simulation results. In order to derive injection molding conditions that can minimize distortion of parts, it was investigated that the effects of mold temperature, resin temperature, injection time, hold pressure switching time, holding pressure and the hold time on deformation characteristics using the design of experiments. The main influential factors on the warpage were found from the optimization simulation and the geometry data of the warpage result was converted into an initial model for injection simulation. It was shown that a coarse model with good mesh quality could be adapted for mold design since the total analysis time using the proposed model was reduced to 1/10. The suggested inversed warpage model produced the best minimized result of warpage.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 1994년도 추계학술대회강연 및 발표대회 강연및 발표논문 초록집
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• pp.6-6
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• 1994

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.39-40
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• 2006

The relationship between the powder particle size change and a mechanical property of the Metal Injection Molding (MIM) product was examined in detail. The XRD results indicate that the diffraction peaks of BCC appeared in compacts of powder particle size of 4 to $10{\mu}m$ as well as the bulk SUS630. However, the diffraction peaks from both BCC and FCC were observed in the compact with powder size less than $3{\mu}m$. TEM observation revealed that the powder with those BCC/FCC two phase structure have a finely dispersed $SiO_2$ precipitates. Because the Si is ferrite stabilizing element, decrease of Si composition in the matrix phase by the $SiO_2$ precipitation resulted in formation of the retained austenite. Therefore, controlling the elements such as Si as well as oxygen decrease is very important to obtain a normal microstructure in ultra-fine powder $(<3{\mu}m)$ injection molding.