• 제목/요약/키워드: Bending

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박판의 Z-굽힘가공에서 외측 굽힘반지름 치수의 최소화(샤프에지) 가공법에 관한 연구 (A Research on the Processing Method to Minimize the Outer Radius(Sharp edge) in Sheet Metal Z-bending Work)

  • 윤재웅
    • 한국산학기술학회논문지
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    • 제18권2호
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    • pp.349-355
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    • 2017
  • 프레스금형(press dies)에 의한 굽힘가공(bending work) 이라는 것은 평평한 블랭크(blank)를 필요로 하는 각도(角度)로 굽히는 것이다. 굽힘가공을 하면 굽혀진부분(flange)과 굽혀지지 않은 부분(web)으로 구분되며, 굽힘라인(bending line) 부분에는 굽혀진 각도(bending angle)와 굽힘반지름(bending radius)이 내측과 외측으로 성형된다. 이때, 내측 굽힘반지름의 크기는 제품의 재질별로 최소치수가 제시 된다. 제시된 최소치수 보다 작게 굽히면 절단면 굽힘부위에 덧살이 발생 하거나 외측 굽힘반지름 부위에는 균열(crack)이 생긴다. 굽힘가공에서의 외측 굽힘반지름은 자연적으로 생긴다. 그래서 외측 굽힘반지름 치수를 굽힘펀치와 다이블록으로 조정하면서 필요한 치수로 굽힐수 없다. 굽힘가공에는 V-굽힘, U-굽힘, Z-굽힘, O-굽힘, P-굽힘, 에지굽힘(edge bending), 트위스트굽힘(twist bending), 크림핑(crimping) 등이 있다.이 중에서 Z-굽힘은 굽힘라인이 2개로써 블랭크의 상면(上面)과 하면(下面)에 설정하여 상향(上向)굽힘이나 하향(下向)굽힘으로 작동되는 금형을 사용한다. Z-굽힘을 크랭크굽힘(crank bending) 이라고도 한다. 이런 구조의 금형으로 Z-굽힘가공을 하면 내측반지름은 표준치수로 굽혀진다. 표준치수라는 것은 굽힘가공에서 굽힐 수 있는 최소 굽힘반지름 치수로서 굽힘펀치의 각(角)반지름(Rp)를 뜻한다. 그런데 산업현장에서는 외측 굽힘반지름 치수를 굽힘펀치와 다이블록으로 굽힐수 없는 미세한 샤프에지(sharp edge) 형상인 매우 작은 치수(R=0.2mm)를 필요로하고 있는 바, 본 논문에서는 외측 굽힘반지름 치수를 0.2mm 이하로 굽힐수 있는 Z-굽힘가공 공법을 개발 하고자 하였다.

국산 소경재의 휨 성질을 이용한 충격에너지와 최대하중까지 일-에너지 예측연구 (Study on the Prediction of the Work-Energy to the Maximum Load and Impact Bending Energy from the Bending Properties)

  • 차재경
    • 한국가구학회지
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    • 제19권5호
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    • pp.350-357
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    • 2008
  • This research investigates the bending properties to predict the work-energy to maximum load and impact bending energy from static bending and impact bending test. Specimens were prepared from lumber made of thinning crop-trees. Matched specimens were used for MC 12% and green moisture specimens to measure the effect of moisture content on the absorbed energy from static and impact bending tests. The bending properties such as MOE, MOR, etc. is a good predictor to investigate the work-energy and work-energy per unit volume from static bending and impact bending test. The impact bending energy is increased with increasing moisture content. However, the work to maximum load from static bending test is increasing with increasing the MC only for higher density species.

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일체화 성형 서브프레임 개발을 위한 벤딩 공정의 영향성 연구 (A Study of Bending Process for Development of Subframe by Hydroforming)

  • 서창희;이우식;김헌영;임희택
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2003년도 춘계학술대회논문집
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    • pp.262-265
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    • 2003
  • In the present study, subframe was developed using hydroforming technology. The manufacturing process for subframe consists of tube bending, pre-forming and hydroforming. The effects of bending process for manufacturing hydroformed subframe were researched. And the variables of bending process were studied by FEM simulation. The bending method is rotary draw bending that is the most popular, cost-effective bending method for thin walled tubes.

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박판을 이용한 Z-굽힘 가공의 전개 길이에 관한 연구 (A study on the unfolding length of Z-bending machining using thin plate)

  • 박용순;최계광
    • Design & Manufacturing
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    • 제15권3호
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    • pp.19-25
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    • 2021
  • The bending process of a press die is to bend a flat blank to the required angle. There are V-bending, U-bending, Z-bending, O-bending etc. for bending processing, and the basic principle of calculating the unfolding length of die processing is used as the neutral plane length. Since the constant of the length value of the neutral surface is different depending on the type of bending, it is impossible to accurately calculate it. In particular, Z-bending processing is performed twice, and it is set on the upper and lower surfaces of the blank, and bending processing occurs at the same time as the upward and downward bending, and the elongation of the material occurs and the material increases. It is not possible to check with the calculated value, and it occurs in many cases where the mold is modified after start-up. This study aims to minimize die modification by developing a formula to calculate the development length of Z-bend.

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원형으로 굽은 광도파로의 low bending loss를 위한 trench 구조설계: 원통좌표계 FD-BPM (A Trench Structure for Low Bending Loss of Bent Optical Waveguides)

  • 한영진;김창민
    • 한국광학회지
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    • 제6권4호
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    • pp.373-378
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    • 1995
  • 원통좌표계에서의 FD-BPM(finite difference-beam propagation method)을 이용하여 굽은 광도파로의 bending loss를 계산하였다. Bending loss를 최소화하기 위해 trench구조를 적용하였으며 다음의 세가지 측면에서 해석하였다. 1)trench구조가 없을때 곡률반경에 따른 bending loss, 2)폭과 위치가 일정한 trench구조가 있을때 곡률반경과 굴절율차에 따른 bending loss, 3)trench의 위치가 일정할 때 trench의 폭에 따른 bending loss를 계산하였다.

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Hard bending시 Bi-2223 초전도테이프의 임계전류 열화 거동 (The Ic degradation behavior in Bi-2223 superconducting tapes during hard bending)

  • 신형섭;최수용;고동균;하홍수;하동우;오상수
    • 한국초전도ㆍ저온공학회논문지
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    • 제4권1호
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    • pp.40-44
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    • 2002
  • Influences of bending strain on the critical current (Ic) were investigated in Bi-2223 superconducting tapes at 77K. The effect of bending mode on the Ic degradation behavior was discussed in viewpoints of test procedure, n-value and damage morphology Especially, in this paper, we reported the Ic behavior in Ag alloy/Bi-2223 multifilamentary superconducting tapes under bending occurred within a width plane of the tape which was called as a hard bending. The Ic degradation under hard bending appeared significantly as compared with that under easy bending. The n-value decreased slightly with the increase in bending strain under the hard bending.

헤밍 (Hemming) 구조를 가진 박판의 굽힘품질 개선에 관한 연구 (A Study on Improvement of Bending Quality of Hemmed Plates in Sheet Metal Forming)

  • 김판근;박상후
    • 한국정밀공학회지
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    • 제29권12호
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    • pp.1360-1367
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    • 2012
  • A bending process is considered as one of fundamental sheet metal forming processes, and it is widely used for fabrication of simple or complicated sheet metal products in industrial fields. Most of automobiles and electronics have many parts made by the bending process inside or outside of them. However, till now, there is few research reports on the bending process of hemmed plates. A hemmed plate has a locally different bending strength, so a waving shape occurs after bending. A poor outlook due to local uneven shape influences greatly on product competitiveness. To settle this problem, we studied the bending parameters of a hemmed plate and showed the major sensitive design-parameters on the bending quality.

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

  • 류경희;김동진;김병민;이동주
    • 소성가공
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    • 제10권4호
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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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Hair Pin Bending Machine을 이용한 동 튜브 굽힘 성형가공에 관한 연구 (A study about shape processing for the bend of the Copper-Tube that use Hair Pin Bending Machine)

  • 강흥식;김동성;허신;홍성인
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2003년도 춘계학술대회 논문집
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    • pp.1705-1708
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    • 2003
  • The purpose of this study is to investigate the manufacturing technique on the U type Draw-Bending of inner grooved tube. This bending process make the U shape tube by Hair Pin Bending machine. The U type tube requires the quality of product that satisfy sufficient conditions for a heat exchanger. The mandrel components act the important roles that prevent wrinkles and keep the shape of cross section of bended tube at bending process. We performed the FEM simulation using LS-DYNA software and the bending test of inner groove tube and then, compared bending simulation with bending test results about mandrel ball diameter, mandrel position and optimal clearance between mandrel and tube.

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도어 임팩트 빔의 3점 굽힘 최대강도와 차량 장착 시 굽힘 좌굴강도와의 관계 (The Relation of Bending Buckling Strength in Vehicle and Three Point Bending Maximum Strength of Door Impact Beam)

  • 강성종;이상민
    • 자동차안전학회지
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    • 제11권1호
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    • pp.40-47
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    • 2019
  • First, three point bending analysis for the inclined press door impact beam was carried out to investigate inclination angle effect on the maximum strength with varying support distance. Next, for the system model with spring elements representing body stiffness at door mounting area, the bending structural behavior of impact beam mounted on vehicle was estimated. The mounting distance and inclination angle were changed and the beam bending buckling strength was presumed at the head displacement below which spring stiffness change has little effect on the load. Finally strength ratio to predict the bending buckling strength of impact beam mounted on vehicle from three point bending maximum strength of fixed support distance was suggested.