• 제목/요약/키워드: hot sealing

검색결과 38건 처리시간 0.02초

Air Bulging을 이용한 열간 알루미늄 성형에 관한 연구 (Study on Al Hot Forming using Air Bulging)

  • 박동환;강성수;김병년
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2009년도 춘계학술대회 논문집
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    • pp.145-147
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    • 2009
  • The benefits of hydroforming technology are known as weight and cost savings through part consolidation and reduced post-forming processes such as welding and piercing. Hydroforming technology has some weaknesses in terms of process cycle times. But, as the hydraulic system and process designs are continuously developed, the cycle time is also reduced to acceptable and competitive levels. Hot air bulging is one of recently developed hydroforming techniques. Hot air bulging in order to further extend the forming degrees of Al lightweight material is investigated. A heated tube is placed in a heated die and sealed at the ends by sealing cylinders. The tube is subsequently expanded against the die cavity wall by internal pressure provided by air medium. The result of this study shows that axial feeding speed and air pressure have an effect on formability of Al air bulging at elevated temperature.

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아스팔트 콘크리트 포장용 균열실링재의 부착특성 평가 (Evaluation of Adhesion Characteristics of Crack Sealants Used in Asphalt Concrete Pavement)

  • 이재준;김승훈;백종은;임재규;김용주
    • 한국도로학회논문집
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    • 제17권2호
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    • pp.55-62
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    • 2015
  • Cracking is an inevitable fact of asphalt concrete pavements and plays a major role in pavement deterioration. Pavement cracking is one of the main factors determining the frequency and method of repair. Cracks can be treated with a number of preventative maintenance actions, including overlay surface treatments such as slurry sealing, crack sealing, or crack filling. Pavement cracks can show up as one or all of the following types: transverse, longitudinal, fatigue, block, reflective, edge, and slippage. Crack sealing is a frequently used pavement maintenance treatment because it significantly extends the pavement service life. However, crack sealant often fails prematurely due to a loss of adhesion. Because current test methods are mostly empirical and only provide a qualitative measure of the bond strength, they cannot accurately predict the adhesive failure of the sealant. This study introduces a laboratory test aimed at assessing the bonding of hot-poured crack sealant to the walls of pavement cracks. A pneumatic adhesion tensile testing instrument (PATTI) was adopted to measure the bonding strength of the hot-poured crack sealant as a function of the curing time and temperature. Based on a limited number of test results, the hot-poured crack sealants have very different bonding performances. Therefore, this test method can be proposed as part of a newly developed performance-based standard specification for hot-poured crack sealants for use in the future. PURPOSES : The purpose of this study was to evaluate both the adhesion and failure performance of a crack sealant as a function of its curing time and curing temperature. METHODS: A pneumatic adhesion tensile testing instrument (PATTI) was adopted to measure the adhesion performance of a crack sealant as a function of the curing time and curing temperature. RESULTS: With changes in the curing time, curing temperature, and sealant type, the bond strengths were found to be significantly different. Also, higher bond strengths were measured at lower temperatures. Different sealant types produced completely different bond strengths and failure behaviors. CONCLUSIONS: The bonding strength of an evaluated crack sealant was shown to differ depending on various factors. Two sealant types, which were composed of different raw materials, were shown to perform differently. The newly proposed test offers the possibility of evaluating and differentiating between different crack sealants. Based on alimited number of test results, this test method can be proposed as part of a newly developed performance-based standard specification for crack sealants or as part of a guideline for the selection of hot-poured crack sealant in the future.

플라이애쉬를 다량 치환한 콘크리트의 초기강도성상에 관한 실험적 연구 (The Experimental Study on Early Strength Properties of High Volume Fly-Ash Concrete)

  • 이동하;김상미;강태경;백민수;이영도;정상진
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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    • pp.281-286
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    • 2002
  • To study of binder and fine aggregate a lot of replacement fly-ash concrete, initial characteristics, standard environment of curing temperature $20^{\circ}C$, hot-weather environment of curing temperature $35^{\circ}C$, . Flesh concrete tested slump. air contest and Hardening concrete valuated setting period of form, day of age 1, 3, 5. 7, 10, 28 compression strength in sealing curing. Purpose of study is consultation materials in field that variety of fly-ash replacement concrete mix proportion comparison and valuation. (1) Experiment result age 28day compression strength more higher plan concrete then standard environment in curing temperature $20^{\circ}C$, , most strength F43 is hot-weather environment in curing temperature $35^{\circ}C$, replacement binder 25%, fine aggregate 15%. (2) Hot-weather environment replacement a mount of fly-ash is a same of plan concrete setting period of form. Age 28day compression strength replacement a mount of fly-ash more hot-weather concrete then plan concrete.

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An Experimental Study on the Mass and Energy Release for a Hot Leg Break LBLOCA During Post Blowdown

  • S.J. Hong;Kim, J.H.;Park, G.C.
    • Nuclear Engineering and Technology
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    • 제32권2호
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    • pp.108-127
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    • 2000
  • Hot leg break LBLOCA(Large Break LOCA) had a potential to be a containment maximum pressure accident in YGN3&4, which was induced from excessive conservatism in the CE analysis methodology of mass and energy release. This study conducted mass and energy release experiment for the hot leg break LBLOCA during post blowdown with an integral test facility, SNUF(Seoul National University Facility). This facility simulated YGN 3&4 with volume ratio of 1/1140 based on Ishii's three level scaling. Experiment showed that SI(Safety Injection) water refilled cold leg first and core later. SI water was vaporized in the core, which resulted in the repressurization of reactor. This increase of pressure drove the water in cold leg to flow up half height of U tubes. However, since the water was drained back soon, the release through the SG side broken section by evaporation was negligibly small. This study also provided experimental assessment of RELAP5 results by KAERI for the release through the SG side broken section.

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자동차 조향장치용 소???R의 온간단조 공정 설계를 위한 3차원 유한요소해석 (3D FEM Analysis of Warm Forging Process Design for Socket at Automotive Steering Unit)

  • 이영선;이정환;이준용;배명한
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2001년도 춘계학술대회 논문집
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    • pp.186-189
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    • 2001
  • In keeping with the needs of the times for energy and labor saving and simplifying production processes, interests has been growing in warm forging. Moreover, it is interested in increasing the material usage and production amounts. To improve the productivity and material usage, it is studied the process design of warm forging for socket. Until now, socket is manufactured by hot forging in hammer. The percentage of material usage is under $60\%$ in hammer forging. On the other han4 the percentage can be increased over $90\%$ in warm forging. To change the process from hot forging to warm forging, process designs must be performed. In this time, by using the FEM package, DEFORM-3D, we could get the shape of 1st process and minimum sealing pressure. They are very essential design data to decrease the trial and error. Practically, the overlap defect could be detected and eliminated with design modification of rib height and fillet radius. Moreover, forging load and minimum sealing pressure was defined by the 3D FEM analysis.

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극세선 및 미세 튜브 압출 장치 개발 (Development of Hot Hydrostatic Extruder for Fine Wire and Tube)

  • 나경찬;박훈재;김승순;윤덕재;최태훈;김응주;조남선
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2001년도 춘계학술대회 논문집
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    • pp.239-244
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    • 2001
  • Hot hydrostatic extruder was developed. The main objective of the development is forming fine wire and tube. On account of effectiveness and high performance, the extruder was designed to have double action. Therefore the main cylinder and mandrel can be driven independently. To cope with severe condition of high temperature and pressure, wire-wound container equipped with heater was used. Sealing technique also is important in this process, so seal ring was made of super-elastic metal. Another key for successful forming is choice of proper pressure medium. Fine wire and tube produced by the extruder can be used in semiconductor industry and medicine.

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점토 결합 SiC 소결체의 마찰 마모 특성 (Tribological Properties of Clay Bonded SiC)

  • 한상준;이경희;이재한;김홍기
    • 한국세라믹학회지
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    • 제32권9호
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    • pp.1027-1032
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    • 1995
  • SiC had been widely applied for mechanical sealing as a sealing material. SiC sintering is commonly made of reaction sintering, presureless sintering, and hot isostatic pressing (HIP) sintering. In this investigation, however, clay bonded sintering was used to avoide any complications of the special sintering methods as mentioned above. In order to prevent harmful SiC oxidation in the clay bonded sintering, clay and frit were used to form the SiC oxidation protecting layer and graphite was added to provide high solid lubricity. As a result, the material with 6% clay (clay 5.4% and frit 0.6%) and 2~4% graphite (45 mesh) sintered at 140$0^{\circ}C$ for 3 hours, showed the following physical properties; porosity 6%, static friction coefficient 0.15, kinematic coefficient 0.1,. and specific wear rate 4.8$\times$10-8 $\textrm{mm}^2$kgf-1. On the other hand, the flexural strength was 900kgf/$\textrm{cm}^2$. This tribological characteristic properties were similar to those of the reaction sintered SiC except the flexural strength.

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열가소성 엘라스토머 패킹의 열융착 해석 (Analysis on Hot Plate Welding of Thermoplastic Elastomer Packing)

  • 김민호;이용태;정재동
    • 설비공학논문집
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    • 제28권12호
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    • pp.477-482
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    • 2016
  • Airtight containers have been widely used in many industries and household. They need a packing for sealing between the inside and outside. Previous packing materials have some drawbacks like stench, stickiness, and difficulty of applying to automated manufacturing systems. So, a new packing material which is harmless and suitable for automation is needed. This study performed a hot plate welding process of thermoplastic elastomer (TPE) as the packing material. The hot plate welding process included a phase change process of solidification and melting. The porosity-enthalpy method was adopted in order to simulate phase change problems. The TPE showed non-Newtonian fluid characteristics during the melting process. Since properties of SEBS are not well-defined, we established TPE properties by observing the melting behavior of TPE. In order to find an optimized condition, a parametric study including packing thickness, shapes, hot plate temperature, and thermal resistance, was conducted.

B2O3첨가에 따른 V2O5-P2O5-ZnO계 유리의 물성 및 구조와 봉착특성 (Effect of B2O3 Addition on Thermal, Structure, and Sealing Properties V2O5-P2O5-ZnO Glass)

  • 성아람;김유리안;김형순
    • 한국재료학회지
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    • 제26권10호
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    • pp.549-555
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    • 2016
  • We have investigated a glass-forming region of $V_2O_5-P_2O_5-ZnO$ glass and the effects of the addition of modifier oxides ($B_2O_3$) to the glass systems as a sealing material to improve the adhesion between the glass frits and a soda lime substrate. Thermal properties and coefficient of thermal expansion were measured using a differential scanning calorimetry, a dilatometer and a hot stage microscopy. Structural changes and interfacial reactions between the glass substrate and the glass frit after sintering (at $400^{\circ}C$ for 1 h) were measured by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscope. The results showed that the adhesion strength increases as the content of $B_2O_3$ at 5 mol% increases because of changes in the structural properties. It seems that the glass structures change with $B_2O_3$, and the $Si^{4+}$ ions from the substrate are diffused to the sealing glass. From these results, we could understand the mechanism of strengthening of the adhesion of soda lime silica substrate by ion-diffusion from the substrate to the glass.

가스터빈 회전부 림 씰 두께 증가에 따른 씰링 효율 변화에 대한 수치해석 연구 (Numerical Study on Sealing Effectiveness Changes with Increased Turbine Rotor Rim Seal Thickness)

  • 윤태두;최승영;김태현;박희승;조형희
    • 한국추진공학회지
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    • 제26권1호
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    • pp.38-46
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    • 2022
  • 가스터빈 림 씰 연구의 주요 목표 중 하나는 고온의 주 유동 유입을 차단하여 디스크 내부의 열 손상을 방지하는 것이다. 이를 위해 지금까지 림 씰의 형상에 대한 연구와 함께 이를 개선하기 위한 연구도 수행되었다. 또한, 실제 터빈에 림 씰 형상을 적용하기 위해서는 터빈 작동 시에 발생할 수 있는 다양한 상황에 대한 연구가 필요하다. 따라서 본 연구에서는 수치해석을 통해 회전부 림 씰 위치의 두께가 변화하는 상황에 대해 연구하였다. 연구는 반지름 방향으로 로터 림 씰이 상향된 경우와 림 씰 내부 방향으로 로터 디스크가 확장된 상황을 모사하여 진행하였다. 그 결과, 유입되는 이차유동의 양에 따라 각 경우에서 서로 다른 내부 압력과 씰링 성능 및 유동이 발생함을 확인하였다.