• 제목/요약/키워드: punch-through

검색결과 236건 처리시간 0.028초

충격하중에 의한 1180MPa급 초고강도강의 단열해석 (Adiabatic Analysis of 1180MPa Advanced High Strength Steel by Impact Weight)

  • 김건우;이재욱;양민석;이승엽;김다혜;이재진;문지훈;박지원
    • 한국기계가공학회지
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    • 제21권8호
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    • pp.93-98
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    • 2022
  • Adiabatic blanking is a method to improve productivity through an autocatalytic cycle that occurs repeatedly through plastic deformation and thermal softening caused by impact energy. In this study, an axisymmetric analysis model comprising a punch, die, holder, and specimen was developed to confirm the temperature and deformation characteristics caused by an impact load. Through this, the impact energy, diameter of the punch, gap between the punch and die, and the effect of the fillet were analyzed. Because this process occurs in a very short time, adiabatic analysis can be performed using the explicit time-integration method. The analysis, confirmed that it is necessary to design a structure capable of increasing the local temperature and plastic deformation by controlling the impact energy, working area, gap, and the fillet.

Penetration Behavior of Jack-up Leg with Spudcan for Offshore Wind Turbine to Multi-layered Soils Using Centrifuge Tests

  • Min Jy Lee;Yun Wook Choo
    • 한국해양공학회지
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    • 제38권1호
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    • pp.30-42
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    • 2024
  • This study examined the jack-up spudcan penetration for a new type of offshore wind substructure newly proposed using the jack-up concept to reduce construction costs. The jack-up spudcan for offshore wind turbines should be designed to penetrate a stable soil layer capable of supporting operational loads. This study evaluated multi-layered soil conditions using centrifuge tests: loose sand over clay and loose sand-clay-dense sand. The penetration resistance profiles of spudcan recorded at the centrifuge tests were compared with the ISO and InSafeJIP methods. In the tests, a spudcan punch-through effect slightly emerged under the sand-over-clay condition, and a spudcan squeezing effect occurred in the clay-over-sand layer. On the other hand, these two effects were not critically predicted using the ISO method, and the InSafeJIP result predicted only punch-through failure. Nevertheless, ISO and InSafeJIP methods were well-matched under the conditions of the clay layer beneath the sand and the penetration resistance profiles at the clay layer of centrifuge tests. Therefore, the ISO and InSafeJIP methods well predict the punch-through effect at the clay layer but have limitations for penetration resistance predictions at shallow depths and strong stratum soil below a weak layer.

X20CrMoV121강과 2.25Cr1Mo강 용접부의 ASP 시험과 CVN 충격 시험의 상관관계에 대한 연구 (A Study on the Correlation between Advanced Small Punch Test and Charpy V-notch Test on X20CrMoV121 and 2.25Cr1Mo steels Weldment)

  • 이동환;김형섭
    • Journal of Welding and Joining
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    • 제26권3호
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    • pp.37-44
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    • 2008
  • Charpy V-Notch test is commonly used to evaluate fracture toughness. However, since the region to be evaluated is limited to bulk material due to the specimen size required, individual evaluation of micro-structures on weldment is very difficult. In this study, ASP(Advanced Small Punch) test was carried out to evaluate material degradation and fracture toughness on the B.M, W.M and each micro-structures of HAZ for X20CrMoV121 and 2.25Cr1Mo steels with artificial aging time. In addition, to evaluate fracture toughness and material degradation of B.M and W.M of X20CrMoV121 steels with aging times, CVN (Charpy V-notch) test was performed. And then the correlation between ASP and CVN test on X20CrMoV121 steels was obtained. Furthermore, through this correlation, material degradation property of each micro-region of the HAZ in weldment, which was impossible to be evaluated by the CVN test, can be estimated and determined.

수치해석을 이용한 열간 가변금형 성형특성 평가 (Numerical Study on Forming Characteristics of Hot Multi-Point Forming Die)

  • 이인규;이성윤;정명식;김병민;이상곤
    • 소성∙가공
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    • 제27권4호
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    • pp.236-243
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    • 2018
  • A multi-point forming die (MPFD), which has been used for producing curved plates, is capable of forming various curved plates with just one MPFD. However, in real industries, an MPFD is difficult to be adopted since the structural properties, punch strength, elastic recovery correction and dimensional accuracy become problems. In order to overcome these problems, the hot multi-point forming die (HMPFD) was proposed in this study. This HMPFD commonly provide more less spring-back and forming load than conventional MPFD. Nevertheless, this process is very difficult to form the curved plate, because the final curved shape of the plate depends on many process variables such as the punch/nozzle arrangement (height and distance), the radius of punch, contact conditions between plate and punch. In this study, the forming characteristics of HMPFD and conventional MPFD are compared with each other through the finite element analysis.

롤 포밍 공정에서 컷팅 펀치 형상에 관한 연구 (A study on the cutting punch shape about roll forming process)

  • 정문수
    • Design & Manufacturing
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    • 제10권3호
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    • pp.34-38
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    • 2016
  • Roll forming is a continuous production process that is mass-produced. The roll forming process is produced in various forms. The special feature of roll forming is a continuous production. Therefore, the process of cutting the material is essential. The troubles in a shearing process affects the low productivity. Accordingly, it is important to reduce the factors that inhibit the material flow. And it is difficult to apply the common shear angle. Because it is not a simple forms, such as a progressive die. This study shows how to select the angle of a shear punch and the shape of a cutting punch in the product with a specific shape. Conclusively through three different model, it is advantageous to apply the different shear angle and clearance along the forms.

소프트 다이 플레이트를 이용한 미세 구멍 펀칭 연구 (A Study on Micro Hole Punching with Soft Die Plate)

  • 유준환;주병윤;전병희;오수익
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2002년도 금형가공 심포지엄
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    • pp.260-265
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    • 2002
  • In micro hole punching process, it is very difficult to align punch with die hole. Misalignment can cause a falling-on in hole quality and breakage of punch and die. Micro punching using soft die plate without a die hole has a big advantage because it is not necessary to align punch with die hole and to consider die clearance. Soft die plates are made by polymers or hard rubbers which are softer than metals. In this study, several micro punching experiments are conducted. Micro punching test with some materials shows that micro hole punching is feasible with some soft die plates. Through the section shape obtained by mounting and polishing, the punched hole quality is measured and the shapes of burr and dome we studied.

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헬리컬 기어의 냉간단조에 관한 상계해석 (II) (Upper-bound Analysis for Cold Forging of Helical Gear ( II ))

  • 최재찬;탁성준;최영
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 1996년도 추계학술대회 논문집
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    • pp.144-149
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    • 1996
  • In this paper, the clamping type forging of helical gears has been investigated. Clamping type forging is an operation in which the product is constrained to extrude sideways through an orifice in the container wall. Punch is cylindrical shaped. The punch compresses a cylindrical billet placed in a die insert. As a consequence the material flows in a direction perpendicular to that of punch movement. The forging has been analysed by using the upper-bound method. A kinematically admissible velocity field has been developed, wherein, an involute curve has been introduced to represent tooth profile of the gear. Numerical calculations have been carried out to investigate the effects of various parameters, such as module, number of teeth, helix angle, friction factor and initial height of billet on the forging of helical gears.

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UBET에 의한 측방압출에서의 재료유동특성에 관한 연구 (A Study on Characteristics of the Material Flow Side-Extrusion by UBET)

  • 김강수;김영호
    • 한국정밀공학회지
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    • 제16권11호
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    • pp.116-121
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    • 1999
  • Since the material flow near the die part in CONFORM (Continuous Extrusion Forming) process is similar to that of side-extrusion, the side-extrusion model of tube shaped aluminum profiles was studied for the die design in CONFORM process. In this paper, the effects of process parameters in the side -extrusion through a two-hole die face, such as material flow, height and thickness of the tube, velocities of punch and lengths of bearing land were investigated using UBET program and DEFORM commercial FEM code. The optimum lengths of the bearing lands and punch velocities for obtaining the straight shape products required were determined.

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후판 소재를 적용한 파인 블랭킹 금형 수명에 관한 연구 (Experimental Study on the Mold Life of Fine Blanking Using Thick Plate Materials)

  • 박동환;현경환
    • 소성∙가공
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    • 제30권3호
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    • pp.149-156
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    • 2021
  • Fine blanking is a high-precision process combining principles of metal stamping and cold forming. Unlike conventional metal stamping, fine blanking uses a special triple action such as V-ring force, counter force, shearing force. This study performed the effect of pocket-shaped compression molding on the mold life of the fine blanking using the 7.4mm thick SM45C material. In order to determine the lifespan of the punch and die in the fine blanking molds, a trial mold was manufactured and various punch materials were selected to perform the mold life test. A study on the life of a fine blanking mold by applying a thick plate material was experimentally performed through a mold test.

국부가열효과를 활용한 다점성형공정기술 (Multi-point Dieless Forming Technology Using Local Heating Effect)

  • 박지우
    • 소성∙가공
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    • 제31권2호
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    • pp.96-102
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    • 2022
  • The multi-point dieless forming technology is one of flexible forming technologies that can form 3D curved surfaces of various shapes utilizing a lot of punch arrangements. A new technology that can simultaneously apply high-temperature forming and flexible forming technology by fusing local heating effect to such multi-point dieless forming technology was proposed in the present study. A simple local heating multi-point dieless forming apparatus was fabricated to confirm the applicability of this new technology. This equipment was designed to be used as a heat source by inserting heating cartridges in the head of the multi-point punch. Cartridges were used for all individual punches. Using the manufactured equipment, the time to raise the temperature to the target temperature and the surface temperature of the punch head part in contact with the plate were measured. In addition, forming experiments were carried out according to sheet material temperature (100 ℃, 200 ℃, and 300 ℃) to obtain forming results for each condition. The applicability and feasibility of this technology were confirmed through experimental results.