• Title/Summary/Keyword: 유압 프레스

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Evaluation of plastic flow curve of pure titanium sheet using hydraulic bulge test (유압벌지실험을 이용한 순 티탄늄 판재의 소성유동곡선 평가(제2보))

  • Kim, Young-Suk;Kim, Jin-Jae
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.4
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    • pp.718-725
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    • 2016
  • In this study, the plastic flow curve of commercially pure titanium sheet (CP Ti) actively used in the plate heat exchanger etc., was evaluated. The plastic flow curve known as hardening curve is a key factor needed in conducting finite element analyses (FEA) for the forming process of a sheet material. A hydraulic bulge test was performed on the CP Ti sheet and the strain in this test was measured using the DIC method and ARAMIS system. The measured true stress-true strain curve from the hydraulic bulge test (HBT) was compared with that from the tensile test. The measured true stress-true strain curve from the hydraulic bulge test showed stable plastic flow curve over the strain range of 0.7 which cannot be obtained in the case of the uniaxial tensile test. The measured true stress-true strain curve from the hydraulic bulge test can be fitted well by the hardening equation known as the Kim-Tuan model.

Comparison of Warm Deep Drawability of Stainless Sheet Between Crank Press and Hydraulic Press (크랭크 프레스와 유압 프레스에서 스테인리스 강판의 온간 드로잉성 비교)

  • 김종호;최치수;나경환
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1995.03a
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    • pp.178-185
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    • 1995
  • Warm deep drawing for optimum forming conditions to give the maximum drawing depth is investigated and compared with the results at room temperature. Experiments which draw square cups of STS 304 stainless steel sheet under the constant lubrication condition of teflon film made both in a crank and hydrqulic press for two kinds of specimens . The maximum drawing depth at warm forming condition reaches 1.4 times the drawing depth at room temperature in a crank press, whereas 1.6 times in a hydrqulic press, and also more uniform distribution of thickness in case of warm deep drawn cup is observed. The effects of other factors on formability , such as forming temperature, speed of press and cooling of punch are examinnied and discussed.

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Development of Fine Blanking Die with Fluid Chamber and its Application to Procuction of Circular Blanks in a Hydraulic Press (간이 파인 블랭킹 금형의 개발을 통한 범용 유압 프레스에서의 원형 정밀진단 가공성 연구)

  • Kim, J.H.;Ryu, J.G.;Chung, W.J.
    • Journal of the Korean Society for Precision Engineering
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    • v.13 no.5
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    • pp.157-163
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    • 1996
  • This paper is concered on the development of low-cost fine blanking die with two fluid chambers of which the pressure can be controlled by a hydraulic unit and its application to producting circular blanks in a conventional hydraulic press, not in a special triple-action press usually adopte in fine blanking operation. Four important working parameters affecting on the precision accuracy of products such as existence and position of Vee-ring, stripping force and counter punching force are primarily considered for experiments. Finite element analysis by suing ABAQUA software is approxi- mately made for blanking of circular specimen with a flat stripper plate and then compared with experimental measurements. The the theoretical prediction of camber height which represents deflection of a dish-shaped specimen after blanking seems to give a qualitatively good agreement. It is shown through experiments the the camber height decreases with decreasing stripping force and also with increasing counter punching force, but particularly depending on the latter much more than the former.

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A Study on the Computer-aided Control of the Blankholder Force in the Deep Drawing Process (딥드로잉에서의 소재누르기 힘의 컴퓨터제어에 관한 연구)

  • Song, Chang-Seop;Lee, Dae-Yong
    • Journal of the Korean Society for Precision Engineering
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    • v.4 no.1
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    • pp.74-82
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    • 1987
  • 딥 드로오잉 시의 소재누르기판의 힘을 펀치의 변위 혹은 힘의 임의의 함수로서 제어 시킬 수 있는 서브프레스장치 및 유압장치를 제작하고 제어용 프로그램을 작성하여 시 험하였다. 제작한 장치를 인스트론 시험기에 설치하고 제어용 프로그램을 IBM퍼스널 컴퓨터를 사용하여 실행시킨 결과, 기계 제어 부분은 어셈블러언어로, 계산 부분은 고급 언어로 프로그램을 작성하여 링크시킨 후에 컴파일링하여 사용하는것이 제어의 응답성 및 정확도를 향상시킬 수 있음이 판명되었다. 또한, 소재누르기판의 힘의 제어에 필요한 이론 및 예비 결과들도 제시하였다.

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Microstructure and Hardness Evolution in Press-formed 925 Silver Alloys (가압성형 925 은합금의 미세구조와 경도 변화)

  • Song Ohsung
    • Proceedings of the KAIS Fall Conference
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    • 2005.05a
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    • pp.55-57
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    • 2005
  • 기존의 장신구 은제품은 무르고 주조공정 특유의 미세한 표면결함을 가져서 착웅 중 쉽게 변색되는 문제가 있었다. 본 연구에서는 내식성을 향상시키기 위해 $92.5\%Ag-6.5\%Cu-1\%Zn$의 삼원계 은합금을 기초 소재로 해서 반지장신구를 상정하여 기존의 주조공정으로 대략의 형태를 만들고 금형과 유압프레스로 성형 가압시켜서 적극적으로 주조 시에 발생한 미세기공을 제거하고 결정립을 미세화하여 표면경도와 밀도를 향상시켰다. 선반가공과 미세연마를 실시하여 내식성이 향상된 표면과 기존 주조공정에 비해 3배 이상 향상된 경도를 가져서 스프링백 효과에 의해 귀보석을 세팅할 수 있는 개선된 텐션형 은장신구 공정을 개발하였고 이때의 최적 성형 정도를 확인하였다.

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Pressure-load Calibration of Multi-anvil Press and the Thermal Gradient within the Sample Chamber (멀티 앤빌 프레스의 압력-부하 보정 작업과 시료 내의 온도구배 연구)

  • Kim, Eun Jeong;Lee, Sung Keun
    • Journal of the Mineralogical Society of Korea
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    • v.31 no.3
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    • pp.161-172
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    • 2018
  • Multi-anvil press (MAP) is one of the high pressure apparatuses and often generates the pressure-conditions ranging from 5 to 25 GPa and temperature-conditions up to $2,300^{\circ}C$. The MAP is, therefore, suitable to explore the pressure-induced structural changes in diverse earth materials from Earth's mantle and the bottom of the mantle transition zone (~660 km). In this study, we present the experimental results for pressure-load calibration of the 1,100-ton multi-anvil press equipped in the authors' laboratory. The pressure-load calibration experiments were performed for the 14/8 step, 14/8 G2, 14/8 HT, and 18/12 assembly sets. The high pressure experiments using ${\alpha}$-quartz, wollastonitestructure of $CaGeO_3$, and forsterite as starting materials were analyzed by powder X-ray diffraction spectroscopy. The phase transition of each mineral indicates the specific pressure that is loaded to a sample at $1,200^{\circ}C$: a transition of ${\alpha}$-quartz to coesite at 3.1 GPa, that of garnet-structure of $CaGeO_3$ to perovskite-structure at 5.9 GPa, that of coesite to stishovite at 9.2 GPa, and that of forsterite to wadsleyite at 13.6 GPa. While the estimated pressure-load calibration curve is generally consistent with those obtained in other laboratories, the deviation up to 50 tons is observed at high pressure above 10 GPa. This is partly because of the loss of oil pressure at high pressure resulting from the differences in a sample chamber, and the frictional force between pressure medium and second anvil. We also report the ${\sim}200^{\circ}C/mm$ of thermal gradient in the vertical direction of the sample chamber of 14/8 HT assembly. The pressure-load calibration curve and the observed thermal gradient within the sample chamber can be applied to explain the structural changes and the relevant macroscopic properties of diverse crystalline and amorphous earth materials in the mantle.

Hydro-forming Process Control and Design Concept of Automotive Rear Sub-frame Components Through Cross Sectional Analysis (단면 분석을 통한 자동차용 리어 서브-프레임 하이드로포밍 부품의 공정 제어 및 설계)

  • Kim, Kee Joo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.9
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    • pp.1-6
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    • 2018
  • Hydro-forming technology has spread dramatically throughout automotive industry over the last 20 years. This technology has many advantages for automotive applications in terms of better structural integrity of the parts, lower cost from fewer parts, material savings, weight reduction, lower springback, improved strength, durability, and design flexibility. In this study, various simulation technologies were developed to investigate the formability of hydro-forming components. Through this technology, to establish the effective forming process for appropriate components design, the bending process, pre-forming process, die closing process, etc. were considered for good forming. This paper proposes the forming amount, section length (corresponding to the hydro-forming press capacity), and minimum curvature (curvature effect evaluation according to the hydro-forming pressure) among the considerations in the design of the hydro-forming part. In addition, a design method is proposed for hydro-forming molding by carrying out cross section analysis of a real sub-frame part for automobiles. The effects of pre-bending, axial feed, hydraulic pressure, press load, and friction among the hydro-forming process parameters were analyzed. Therefore, whether these processes are necessary factors for hydro-forming were examined.

Development of 22,000Ton Hydraulic Press for the Forming of Heat Plate with Ultra-Large Size (초대형 열교환기용 열판 성형을 위한 22,000Ton급 유압 프레스 개발)

  • Lim S. J.;Park H. J.;Yoon D. J.;Kim E. Z.;Lim H.;Na K. H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2001.10a
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    • pp.166-169
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    • 2001
  • 22,000 Ton hydraulic press was developed using wire winding method. The hydraulic press consists of three piece of frame type. The outer layers of yoke-column frame and main cylinder linear were wound with piano wire(1mm${\times}$4mm) under controlled tension and the total length of wound wire was about 450Km. The developed hydraulic press is used for the forming of heat plate with ultra-large size. To obtain large force with relative small apparatus, high pressure of $1,500 Kgf/cm^2$ was supplied to main cylinder through pressure amplification by booster pump. Therefore sealing technique of main cylinder is so crucial that the seals were made of mitre ring type with super-elastic metal. The press total weight is about 150 tons, which is quite light and compact relative to that of conventional hydraulic press.

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Design Alterations of a Hydraulic Press Machine for the Improved Stability (구조 안정성 향상을 위한 유압프레스 설계개선)

  • Shin, Yun Ho;Ro, Seung Hoon;Kim, Young Jo;Lee, Dae Woong;Kim, Sang Hwa;Kil, Sa Geun;Yi, Il Hwan
    • Journal of the Semiconductor & Display Technology
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    • v.18 no.2
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    • pp.38-43
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    • 2019
  • In this study, a hydraulic press structure has been investigated in order to enhance the precision machining and the productivity, which are generally damaged by the structural deformation from the pressure and the vibrations originated from the centrifugal forces from the rotating parts of the machine. Computer simulation based on the finite element method has been utilized for the analysis of static and dynamic characteristics to investigate each component's critical points, and to further improve the static and dynamic stabilities of a hydraulic press structure. The result shows that the deformations and the vibrations of the machine could be reduced 35% without increasing the weight of the machine.