• Title/Summary/Keyword: Pipe Bending

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An Optimum Design of Pipe Bending Process Using High Frequency Induction Heating and Dynamic Reverse Moment (고주파 유도가열 및 동적 반력 모멘트를 이용한 파이프 벤딩 공정의 최적설계)

  • Lee, H.W.;Jung, S.Y.;Woo, T.K.;Kim, C.
    • Transactions of Materials Processing
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    • v.19 no.2
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    • pp.79-87
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    • 2010
  • The Pipe bending process using high frequency local induction heating is an advanced technique to bend pipes with a small bending radius and a large diameter. Even though the pipe bending process is a quite widespread engineering practice, it depends heavily upon trial and error method by field engineers with several years of experience. So it is necessary to develop an integrated methodology for optimum design of the pipe bending process. During hot pipe bending using induction heating, outward wall thickness of a pipe is thinned due to tensile stress and the reduction of wall thickness is not allowed to exceed 12.5%. Taguchi method and dynamic reverse moment is proposed to maintain a reduction ratio of thickness within 12.5%, when D/t ratio is high. An application of the proposed approach was compared with those of the finite element analysis and has good in agreements.

Process Design of the Hot Pipe Bending Process Using High Frequency Induction Heating (고주파 유도가열을 이용한 열간 파이프 벤딩 공정 설계)

  • Ryu, Gyeong-Hui;Lee, Dong-Ju;Kim, Dong-Jin;Kim, Byeong-Min;Kim, Gwang-Ho
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.9
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    • pp.110-121
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    • 2001
  • During hot pipe bending using induction heating, the wall of bending outside is thinned by tensile stress. In design requirement, the reduction of wall thickness is not allowed to exceed 12.5%. So in this study, two methods of bending, one is loading of reverse moment and the other is loading of temperature gradient, have been investigated to design pipe bending process that satisfy design requirements. For this purpose, finite element analysis with a bending radius 2Do(outer diameter of pipe) has been performed to calculate proper reverse moment and temperature gradient to be applied. Induction heating process has been analyzed to estimate influence of heating process parameters on heating characteristic by finite difference method. Then pipe bending experiments have been performed for verification of finite element and finite difference analysis results. Experimental results are in good agreement with the results of simulations.

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Analysis and Process Design of Hot Pipe Bending Process With Small Bending Radius (작은 곡률반경 파이프 벤딩을 위한 열간 파이프 벤딩공정 해석 및 설계)

  • 류경희;김동진;김병민;이동주
    • Transactions of Materials Processing
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    • v.10 no.4
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    • pp.329-337
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    • 2001
  • The finite element simulation model and the program to calculate the reverse moment have been developed to analyse the stress state and deformation of pipe bending using local induction heating with small bending radius in this study. The reverse moment that is to be applied on the bending arm to control the wall thinning ratio of the bending outside to within a particular value. Even though the demand of pipes with small bending radius is increasing in power plants and ship buildings, the welded elbows are still widely used. The bending process with or without a reverse moment acting on the bending arm has been simulated. The reverse moments calculated from the developed program are in good agreement with the finite element simulations and the experiments.

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Autofrettage Analysis of Pipe Bend using Finite Element Method (유한요소법을 이용한 곡관의 자긴가공 해석)

  • Park, C.J.;Koh, S.K.;Na, E.G.;Baek, T.H.
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.637-642
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    • 2008
  • Autofrettage analysis of a bend in the fuel injcetion pipe has been performed to investigate the distribution of residual stresses due to pipe bending and autofrettage processes. The pipe bending was simulated by metal forming analysis using finite element method, and residual stress distribution after bending was found. Autofrettage following the pipe bending was performed by applying the hydrostatic internal pressures of 603 MPa, 535 MPa, 500 MPa on the pipe bend, corresponding to theoretical 26 %, 14 %, 9 % overstrain levels, respectively. Residual stress distributions due to bending and autofrettage were evaluated.

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The Effects of Sheet Strength and Thickness on Bending Behavior of Steel Pipes (소재강도와 두께가 파이프 굽힘변형의 꺽임발생 거동에 미치는 영향)

  • 박기철;이형진
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.9
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    • pp.2071-2081
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    • 1995
  • In order to examine the effects of yield stress, tensile strength and thickness on the buckling behavior during bending of pipes, the nonlinear finite element analysis of the 3-point bending tests was carried out using the commercial software (ABAQUS) under the condition of L4(2$^{3}$) performed according to the designed condition. Form the analysis of simulation results, it was found that yield stress and thickness were the major factors on buckling load at pipe bending and tensile strength gave little influence because the plastic strain and plastic zone are small. For the punch displacement to the occurrence of buckling, thickness is a major factor and yield stress and tensile strength are the minor factors.

A Study on the Bending Process for Precision Pipe Forming (정밀 파이프 성형을 위한 벤딩 공정 개발에 관한 연구)

  • Kim, Hyun-Jin;Lee, Choon-Man
    • Journal of the Korean Society for Precision Engineering
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    • v.24 no.6
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    • pp.58-65
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    • 2007
  • The arbitrarily-bended pipe is widely used in a heat exchanger system. Thus, the pipe bending process has important role in performance and productivity of heat exchanger system. The purpose of this study is to investigate the bending process for manufacturing of sound pipe. And, the spring-back effect and the variation of pipe thickness should be controlled effectively. The change of spring-back ratio and the thickness variation of pipe according to the change of bending radius, bending angle and pipe thickness are analyzed by FEM analysis. The analytic results are compared with the experimental data, accordingly the results show good agreement. The method of the analysis can be applied for manufacturing of precision bended pipe.

Deformation analysis of copper pipe for hair pin under the bending forming using the Mandrel (맨드릴을 사용한 굽힘 성형시 헤어핀용 동관의 변형 해석)

  • 김광영;윤두표
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1630-1633
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    • 2003
  • Hair pin bending machine is pipe forming machine consisting of heat exchanger product system. Hair pin produced by these machine is pathway of refrigerant and play a important role improving the performance and productivity of heat exchanger. The core technology of hair pin bending machine is forming the straight pipe into U-type without any defaults. Therefore, this paper study the relation between the pipe bending forming and the shape and position of mandrel using the elastic-plastic finite element analysis and provide a foundation technology for which developing the hair pin bending machine. The results are followed 1. Mandrel located in front of rotating center of bending die minimized the circular shape variation of copper pipe. 2. Diameter change of mandrel hardly effect the pipe shape.

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