• Title/Summary/Keyword: J-shape

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Determination of Initial Billet Shape to Improve Dimensional Accuracy in Backward Extruded Cups (후방압출공정에서 치수정밀도 향상을 위한 초기소재형상 결정)

  • Kim, H.C.;Kim, T.H.;Park, J.C.
    • Journal of the Korean Society for Precision Engineering
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    • v.14 no.2
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    • pp.129-135
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    • 1997

  • Experimental studies have been carried out to obtain uniform cups by one operation of backward extrusion. A lot of factors on dimensional accuracy of backward extruded cups are billet material, billet shape, punch shape, punch velocity, geometry of tool, tool material, and lubrication etc. In manufacturing cup-shaped parts by backward extrusion, it is very important to design the initial billet shape or the preform. The objective of this paper is to find that the shape of the initial billet is related to dimensional accuracy and also to manufacture the more accurate product simultaneously reducing the loss of material as forming the shape of the initial billet by means of upsetting.

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Estimations of Strain-Based J-integral and CTOD for Circumferential Outer Surface Crack in the Weld of Gas Pipeline Under Axial Displacement (축방향 변위가 작용하는 가스 파이프라인 용접부에 존재하는 원주방향 외부표면균열의 변형률 기반 J-적분 및 CTOD 계산)

  • Kim, Kyoung-Min;Park, Ji-Su;Moon, Ji-Hee;Jang, Youn-Young;Park, Seung-Hyun;Huh, Nam-Su
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.16 no.1
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    • pp.100-109
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    • 2020

  • Pipelines subjected to ground movement would be easily exposed to large-scale deformation. Since such deformations may cause the pipeline failure, it is important to ensure the safety of pipelines in various operation conditions. However, crack in weld metal have been considered as one of the main causes that can deteriorate the structural integrity of the pipeline. For this reason, the structural integrity of the pipe containing the crack in the weld should be obtained. In order to assess cracked pipe, J-integral and crack-tip opening displacement(CTOD) have been applied widely as the elastic-plastic fracture mechanics parameters representing crack driving force. In this study, engineering solutions to calculate the J-integral and CTOD of pipes with a circumferential outer surface crack in the weld are proposed. For this purpose, 3-dimensional elastic-plastic finite element(FE) analyses have been performed considering the effect of overmatch and width of weld. The shape of the weld was simplified to I-groove, and axial displacement was employed as for loading condition. Based on FE results, the effects of crack size, material properties and width of weldment on J-integral and CTOD were investigated. Additionally, the J-integral and CTOD for I-groove were compared with those for V-groove to examine the effects of the weld shape, and a proportionality coefficient of J-integral and CTOD was calculated from the results of this paper.

  • https://doi.org/10.20466/KPVP.2020.16.1.100 인용 PDF KSCI

A Study on Cross Sectional Shape Design of Intermediate Pass in the Multi-Stage Shape Drawing (다단 이형인발공정의 중간패스 단면형상 설계에 관한 연구)

  • Lee, J.E.;Lee, T.K.;Lee, S.K.;Kim, S.M.;Kim, B.M.
    • Transactions of Materials Processing
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    • v.18 no.4
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    • pp.283-289
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    • 2009

  • The multi-stage shape drawing is used to obtain long shaped products with high levels of dimensional accuracy and quality. It is important to design the cross sectional shapes of the intermediate passes to meet the required dimensional accuracy of the final product in the multi-stage shape drawing. Until now, the cross sectional shapes of the intermediate passes have been designed by the experiences. It is still remained unsolved problem to design the cross sectional shapes of intermediate pass drawing dies in the multi-pass shape drawing. In this study, a new technique is proposed to design the cross sectional shapes of intermediate passes. The proposed method is applied to a multi-stage shape drawing for a LM-guide which is one of the representative shape drawing products. In order to verify the effectiveness of the proposed method, FE-simulation and experiments have been carried out. The dimensional accuracy of the proposed method is compared with that of the conventional shape drawing process designed by the industrial engineers.

  • https://doi.org/10.5228/KSPP.2009.18.4.283 인용 PDF KSCI