• 대한기계학회논문집A
• /
• 제35권8호
• /
• pp.877-882
• /
• 2011

스태빌라이저는 선박, 자동차 및 비행기 등에서 과도한 동요를 막고 자세를 안정시키는 장치를 말한다. 본 연구에서 스태빌라이저 링크 POM-GF25%인 복합재료와 금속을 사용하여 제조하였다. 스태빌라이저 강도 평가를 위하여 인장, 압축 및 볼스터드 빠짐으로 실시하였으며, 모두 기준을 만족하였다. 4가지 형태의 로드에서, 널링된 로드가 가장 큰 강도를 나타내었으며, 금속제를 대체할 수 있을 것으로 판단된다. 또한 사출 금형의 재해석으로 스태빌라이저 링크 본체의 형상을 개선하였다.

• Composites Research
• /
• 제30권6호
• /
• pp.399-405
• /
• 2017

ILC 기술을 이용하여 장섬유강화 플라스틱 자동차 언더커버 시제품을 제작하고, 시제품의 성형성, 기계적성질 및 내구성을 평가하였다. 언더커버에 대한 사출성형해석과 경량화를 고려하여 시제품을 위한 사출금형을 제작하였다. 보강섬유의 잔존길이 및 분포도를 평가하여 시제품의 성형성을 검토하였고 굴곡강성 및 강도, 충격강도 등의 기계적 성질도 조사하였다. 자동차 내장부품 내구수명 평가 방법인 KLT(Key Life Test)법으로 내구성을 평가하였다.

• 한국정밀공학회지
• /
• 제23권7호
• /
• pp.101-107
• /
• 2006

Cold gas dynamic spray or cold spray is a novel manufacturing method for coatings. Cold spray is a high rate and direct material deposition process that utilizes the kinetic energy of particles sprayed at high velocity (300-1,200m/s). In this research, a technique to repair the damaged mold by cold spray deposition and mechanical machining was proposed. An aluminum 6061 mold with three-dimensional surface was fabricated, intentionally damaged and material-added by cold spray, and its original geometry was re-obtained successfully by Computer Numerical Control (CNC) machining. To investigate deformation of material caused by cold spray, deposition was conducted on thin aluminum plates ($100mm{\times}100mm{\times}3mm$). The average deformation of the plates was $205{\sim}290{\mu}m$ by Coordinate Measurement Machine (CMM). In addition, the cross section of deposited layer was analyzed by scanning electron microscopy (SEM). To compare variation of hardness, Vickers hardness was measured by micro-hardness tester.

• 열처리공학회지
• /
• 제24권4호
• /
• pp.209-216
• /
• 2011

Surface coatings were prepared on SKD11 core mold steel by plasma electrolytic oxidation (PEO). The coatings were investigated about the formation condition of core mold steel. SKD11 were coated by PEO in a mix solution of Sodium Aluminate $NaAlO_2$ (10 g/l), Sodium Silicate powder $Na_2SiO_3$ (0.5 g/l), Sodium tungstate dihydrate $Na_2WO_42H_2O$ (0.5 g/l) at less than $30^{\circ}C$. The electrical condition were voltage : 500~600 V; Pulse : 600~1800 Hz; current density 15~20 $A/dm^2$ various time : 3 min~40 min. The coatings surface morphology, cross-section, friction coefficient, hardness were investigated. The PEO coatings on SKD11 core mold steel showed the extended service life.

• 열처리공학회지
• /
• 제13권2호
• /
• pp.71-84
• /
• 2000

A study on adhesion and wear resistance of VC(vanadium carbide) coating on die steels, STD11 and STD61, has been carried out. The VC coating on the die steels was made by immersing them in molten borax bath, a kind of TRD(thermo-reactive deposition and diffusion). Adhesion strength and wear resistance were investigated using scratch test, indentation test and plate-disc test(Ogoshi type) respectively. The influence of sliding distance on the amount of wear has been determined and dominant wear mechanisms has been characterized using optical microscopy, scanning electron microscopy and EDS spectroscopy. The critical adhesion strength($L_c$) between VC coating layer and substrate(STD11) was increased to 60N($L_c$) in the scratch test. In the case of STD61, the strength increased to 24N. The wear resistance of VC coated die steels was excellent because the diffusion layer formed just below the coating layer. The dominant wear mechanism was identified as adhesive wear for VC coating die steels which were worn by combination of cracking and plucking of VC fragments and disc.

• 열처리공학회지
• /
• 제30권5호
• /
• pp.197-206
• /
• 2017

The microstructure of a high-carbon and high-chromium cast steel (HK700) for cold-work die inserts was analyzed by advanced scanning electron microscopy. A continuous network of primary $M_7C_3$ carbide was developed among austenitic matrix after casting. A small amount of $M_2C$ was added to the carbide network owing to the enrichment of Mo and W during the solidification. After quenching in which the austenitization was performed at $1030^{\circ}C$ and double tempering at $520^{\circ}C$, the network structure of $M_7C_3$ was preserved while most of the matrix was transformed to martensite because of additional carbide precipitation. The $M_2C$ in the as-cast microstructure was also transformed to $M_6C$ due to its instability. The continuous network of coarse carbides owing to the absence of hot-working had little influence on the hardness after quenching and tempering, whereas it resulted in severe brittleness upon flexural loading.

• 소성∙가공
• /
• 제23권7호
• /
• pp.439-445
• /
• 2014

Changes in the accuracy of the geometrical shape after a surface treatment are often very large due to the variation of the deformation mechanisms such as edge draw-in and the variation in springback caused by the reduction in the coefficient of friction between the tool and the blank. In the present study, the resulting shape accuracy due to the changes in deformation is quantitatively examined in order to predict the variation and to remove any undesirable additional tool compensation for the center pillar member made from steel with a UTS of 980MPa. The study examines important process parameters that are closely related with the edge draw-in such as the blank holding force, the contact status between the tool and the blank and the friction coefficient. The proposed method is applied within the finite element analysis of the stamping process for tools after a surface treatment and the amount of edge draw-in and flush values are compared between the analysis and experiments. The results demonstrate that the proposed quantification and finite element scheme are applicable to complicated tool compensation procedures and compensation can be designed effectively.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2000년도 추계학술발표대회 논문집
• /
• pp.265-270
• /
• 2000

Injection molding is a very important industrial process for the manufacturing of plastics objects. During an injection molding process of composites, the fiber-matrix separation and fiber orientation are caused by the flow of molten polymer/fiber mixture. As a result, the product tends to be nonhomogeneous and anisotropic. Hence, it is very important to clarify the relations between separation· orientation and injection molding conditions. So far, there is no research on the measurement of fiber orientation using image processing. In this study, the effects of fiber content ratio and molding condition on the fiber orientation-angle distributions are studied experimentally. Using the image processing method, the fiber orientation distribution of weld-line parts in injection-molded products is assessed. And the effects of fiber content and injection molding conditions on the fiber orientation functions are also discussed

• 한국기계가공학회지
• /
• 제16권6호
• /
• pp.81-86
• /
• 2017

The high-pressure resin transfer molding (HP-RTM) process has a very effective for the mass production of carbon fiber reinforced plastic (CFRP) for light weight in the automotive industry. In developing robust equipment, new process and fast cure matrix systems reduces significantly the cycle time less than 5 minutes in recent years. This paper describes the cavity pressure, temperature and molding characteristics of the HP-RTM process. The HP-RTM mold was equipped with two cavity pressure sensors and three temperature sensors. The cavity pressure characteristics of the HP-RTM injection, pressurization, and curing processes were studied. This experiment was conducted with selected process parameters such as mold cap size, maximum press force, and injection volume. Consequently, this monitoring method provides correlations between the selected process parameters and final forming characteristics in this work.

• 대한공업교육학회지
• /
• 제31권2호
• /
• pp.350-363
• /
• 2006

최근 마이크로 엔드밀을 이용한 가공은 소형구조물이나 소형기계의 부품과 금형산업에서 양호한 표면 거칠기와 가공시간의 단축을 위해 고정도의 기술을 요구하고 있다. 마이크로 엔드밀을 이용한 가공에 있어서 가공조건은 절삭면의 표면거칠기에 커다란 영향을 미치게 된다. 따라서 본 연구에서는 마이크로 엔드밀을 이용하여 스테인리스 강(STS 304)의 표면을 가공하였고, 실험계획법에 의해 최적의 표면거칠기를 얻기 위한 가공조건에 대해 분산분석하였다. 본 연구를 통하여 마이크로 엔드밀에 의한 가공에서 가공조건은 절삭깊이, 스핀들의 회전수, 이송속도의 순서로 표면거칠기에 영향을 미치는 것을 알았다.