• Title/Summary/Keyword: Folding Defect

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A Study for Preventing Folding Defect of the Common Rail Pipe in Heading Process (커먼레일 파이프 헤딩공정의 접힘결함 방지에 관한 연구)

  • Song, Myung-Jun;Woo, Ta-Kwan;Jung, Sung-Yuen;Hur, Kwan-Do;Kim, Chul
    • Journal of the Korean Society for Precision Engineering
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    • v.27 no.1
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    • pp.25-32
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    • 2010
  • With the latest automobile technology, though the third generation common rail system requires high injection pressures up to 1,800bar, the next generation diesel engine is expected to require more higher pressures than the third generation. The common rail pipe requires higher strength because it is one of the parts in the common rail system, which is influenced directly by fuel under high pressure. Preform design is very important for preventing head of the common rail pipe from folding in the heading process. In this study, die angle, curvature, outer diameter of die and length of trapped part are selected as main parameters to obtain best preform shape minimizing radius of folding. Therefore optimal design is carried out by finite element analysis and Taguchi method through main parameters. Results of the finite element analysis have good agreements with those of the experiments in the actual field.

A Study on Structure Analysis and Fatigue Life of the Common Rail Pipe (커먼레일 파이프의 구조해석 및 피로수명에 관한 연구)

  • Song, M.J.;Jung, S.Y.;Hwang, B.C.;Kim, C.
    • Transactions of Materials Processing
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    • v.19 no.2
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    • pp.88-94
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    • 2010
  • The next generation of diesel engine can operate at high injection pressure up to 1,800bar. The common rail pipe must have higher internal strength because it is directly influenced by the high-pressure fuel. Folding defects in the Common rail pipe can not ensure the structural safety. Therefore, Preform design and fatigue-life analysis are very important for preventing the head of the common rail pipe from folding in the heading process and for predicting fatigue life according to the amount of folding. In this study, a closed form equation to predict fatigue life was suggested by Goodman theory and pressure vessels theory in ASME Code in order to develop an optimization technique of the heading process and verified its reliability through fatigue-structural coupled field analysis. The results calculated by the theory were in good agreement with those obtained by the finite element analysis.

Prediction of defect shape change using multiple scale modeling during wire rod rolling process (멀티 스케일 모델을 적용한 선재 공정의 미세결함 형상 변화 예측)

  • Kwak, Eun-Jeong;Kang, Gyeong-Pil;Lee, Kyung-Hoon;Son, Il-Heon
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2009.10a
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    • pp.169-172
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    • 2009
  • Multiple scale modeling has been applied to predict defect shape change during the wire rod rolling process. The size difference between bloom and defect prevent using usual FEM approaches due to the enormous number of elements required to depict the defect. The newly developed multiple scale model can visualize defect shape changes during the multi stands rolling process. The defect positioned at the top and side of bloom are smoothed out but the one at the middle evolved as folding or remained as crack. This approach can be used for defect control with roll shape design and initial bloom shape.

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A Study on Die Forging of a Hollow T-shaped Part (중공 T형상의 형단조에 관한 연구)

  • 김현수;김용조
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.1
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    • pp.32-39
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    • 2004
  • Traditional forging of a hollow T-shaped part has been applied to forge a solid T-shaped product from a solid billet and then to machine the hollow in that. In a case, a hollow T-shaped part can be forged by backward-extruding from a solid billet. In this study, four types of forging were suggested for manufacture of hollow T-shaped parts. Forging simulations for each of these forging methods were carried out to investigate folding defect, metal flow pattern, effective strain, and forging loads. Experimental works were carried out to be compared with the simulation results. Here, the ratio of the thickness of the hollow tube to that of the flange was selected to investigate a forging defect like folding.

The effect of thread rolling process parameters on the quality of large stud bolts (대형 스터드 볼트의 나사부 품질에 미치는 전조 공정 변수의 영향)

  • Kwon, I.K.;Yoon, Y.C.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2006.05a
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    • pp.341-344
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    • 2006
  • Finite element analysis and verification experiments were performed in order to find cause of defects such as folding and improper radius around the root area of the thread rolled stud bolts. Thread rolling experiments under several conditions were also carried out to understand the effect of process parameters, such as the rotation speed of the dies and the hardness of the work pieces, on the product quality. Folding defects at the top of thread are attributed to the higher hardness of the work piece and higher rotation speed of the rolling die. It was also found that the radius of screw mainly determined by the radius of the die.

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Preform Effect on the Plastic Deformation Behavior of Workpieces in Equal Channel Angular Pressing (Equal Channel Angular Pressing 가공 중 소성 변형에 미치는 재료의 초기 형상 효과)

  • Yoon, Seung-Chae;Seo, Min-Hong;Kim, Hyoung-Seop
    • Transactions of Materials Processing
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    • v.15 no.5 s.86
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    • pp.382-386
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    • 2006
  • Preform design is an effective means of achieving the homogeneous deformation of workpiece materials and decreased load in metal forming. However, this approach has not been applied to equal channel angula. pressing (ECAP). In this paper, plastic deformation behavior of workpieces having four different preform shapes during ECAP was investigated using finite element analyses. The results indicated that a preform design of the workpiece head has a beneficial effect on homogeneous deformation, reducing the maximum pressing load at the initial stage and eliminating folding defects at strain concentration points.

Rigid-Plastic Finite Element Analysis for Forging Process Design of a Hollow Flange

  • Bae, Sung-Woo;Kim, Yohng-Jo
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.3 no.1
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    • pp.59-65
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    • 2004
  • Hollow flange-shaped parts rue widely used in transportation systems. For good quality products, in general, design of preforms and die shapes for a progressive forging process is an important issue. For the design of die shapes for the forging process of a hollow flange, computer simulations Were earned out using the rigid-plastic finite element method. Forging defects like folding were seen in the vicinity of die corners at the typical shape ratios of upper and lower dies Die shape ratios at which the forging defect could occur during the extrusion-forging process of the hollow flange were investigated. The results might be efficiently used for the proper design of perform shapes, die shapes, and forging processes.

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A Study on the Defect of T type Forging Products (T형 다조부품의 결함에 관한 연구)

  • 손경호;김영호;서윤수
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.04a
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    • pp.952-956
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    • 1997
  • This paper describes the method that can expand the forming limit of T type forging products used in aircraft and automotive forged products. The forming limitis determined by the ratio of web thickness to rib width in T type and the reduction in height of workpiece and especially depends on the ratio of web thickness to rib width. For this method, the geometric condition that consists of triangle type was introduced and FEM simulations and model exoeriments were carried out and compared with each other. The objective of this paper is to give the method not only that sink mark and folding phenomenon are eliminated but also that the forming limit and the structural strength of rib and web is increased.

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Design of a Hinge Bracket Forming Process Using Thick Plate (후판을 이용한 힌지 브래킷 성형 공정 설계)

  • Jang, M.G.;Choi, H.S.;Lee, H.K.;Shin, Y.J.;Kim, J.B.
    • Transactions of Materials Processing
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    • v.25 no.4
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    • pp.227-234
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    • 2016
  • In the transportation between countries using container, too many empty containers must be transported due to the transportation unbalance. For transportation efficiency, therefore, foldable containers are being developed. Hinge brackets are important parts of foldable containers because great force is applied on the hinges during loading onto and unloading from ships. In this study, the hinge bracket for a foldable container is designed to be made using thick plate or bulk materials to endure the heavy loads. The forming process for the hinge bracket using a thick plate is designed via numerical analysis. First of all, the shape of bracket is designed for the better formability. Bending and successive side wall thickening processes are employed for the forming of the hinge bracket. Maximum thickening that can be achieved in a single stage of forming without a folding defect is determined and three stage of thickening processes are designed.

Usefulness of using Tissue Expander in Pediatric Patient (소아 환자에서 조직확장기 사용의 유용성)

  • Lee, Jun-Woo;Park, Chul-Gyoo;Park, Jong-Lim;Kim, Yong-Kyu
    • Archives of Plastic Surgery
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    • v.37 no.6
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    • pp.763-768
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    • 2010
  • Purpose: Reconstruction of soft tissue defect using tissue expander can provide better flap which is more similar to surrounding tissue in color, skin texture and hair compared to other methods. Many pediatric patients need reconstruction of soft tissue defect because of giant congenital nevi, congenital or acquired malformations and burn scars. Reconstruction using tissue expander is adequate to minimize dysmorphism in these patients. We intended to assess outcomes of using tissue expander in pediatric patients by retrospective study. Methods: Total cases were 168 of pediatric patients who received soft tissue reconstruction using tissue expander by the same surgeon from February, 1982 to May, 2009. All patients who received soft tissue reconstruction were under 10 years old. Mean age was 4.3 years old, the youngest 13 months, the oldest 8 years. Eightynine cases were male and 79 cases were female. Most common cause was giant hairy nevi (67 cases, 39.9%), secondary cause was burn scar/scar contracture (61 cases, 36.3%). Trunk (38 cases, 22.6%) was most common anatomical location. Results: Soft tissue defects were successfully covered using tissue expander in 149 cases (88.7%) without major complications. There was infection on 8 cases (4.7%) and we treated by adequate antibiotics in these cases. There were tissue expander folding or valve displacement on 5 cases (3%). Conclusion: Usage of tissue expander is useful on pediatric patients because tissue expansion is rapid on children and there are less secondary contractures on operation site than full thickness skin graft. Because of psychological stress due to tissue expander, operation should be performed before school age.