• Title/Summary/Keyword: Preform Design

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Preform Design by the Sensitivity Method (민감도법을 이용한 자유단조 공정의 예비성형체 설계)

  • 심현보;노현철;서의권
    • Transactions of Materials Processing
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    • v.10 no.4
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    • pp.294-301
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    • 2001
  • The sensitivity method has been applied to find perform shape that results in the desired shape after foring. As a 2D example, initial shape of specimen for the cylinder shape without barrelling after forging has been found. The method is then applied to various shapes of 3D free forging and initial shapes of the corresponding specimens after forging have been found successfully The sensitivity method is proven to be an effective and accurate tool for the preform design.

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Preform Design for the Sinter-forging Process of Arc-shaped Powdered Magnets (원호 형상을 가지는 분말자석 단조성형공정에서의 예비성형체 설계)

  • Kim, Seung-Ho;Lee, Choong-Ho;Huh, Hoon
    • Transactions of Materials Processing
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    • v.8 no.2
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    • pp.135-142
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    • 1999
  • Tube Process(TP) is one of the processes to produce permanent magnets. Advantage claimed for this process is that it can accmplish both densification and anisotropication in one step forming. This process is distinguished from other processes since it uses deformable tube for densification of powder magnets. TP has, however, difficulties in manufacturing permanent magnets from Nd-Fe-B green powder due to folding resulted from large height reduction and localized densification. Therefore, an adequate preform is necessary to reduce folding resulted from large height reduction and localized densification. Therefore, an adequate preform is necessary to reduce folding, lead magnets into almost desired final shape and get uniform densification. In this paper, preform design for TP is carried out without a deformable tube to investigate the behaviour of magnet sinter-forging. Preform design is accomplished to increase the effective magnet area with a near net shape and uniform densification.

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Preform Design Technique by Tracing the Material Deformation Behavior (재료의 변형거동 추적을 통한 예비형상 설계)

  • Hong J. T.;Park C. H.;Lee S. R.;Yang D. Y.
    • Transactions of Materials Processing
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    • v.13 no.6
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    • pp.503-508
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    • 2004
  • Preform design techniques have been investigated to reduce die wear and forming load and to improve material flow, filling ratio, etc. In hot forging processes, a thin deformed part of a workpiece, known as a flash, is formed in the narrow gap between the upper and lower tools. Although designers make tools that generate a flash intentionally in order to improve flow properties, excessive flash increases die wear and forming load. Therefore, it is necessary to make a preform shape that can reduce the excessive flash without changing flow properties. In this paper, a new preform design technique is proposed to reduce the excessive flash in a metal forging process. After a finite element simulation of the process is carried out with an initial billet, the flow of material in the flash region is traced from the final shape to the initial billet. The region belonging to the flash is then easily found in the initial billet. The finite element simulation is then carried out again with the modified billet from which the selected region has been removed. In several iterations of this technique, the optimal preform shape that minimizes the amount of flash without changing the forgeability can be obtained.

Preform Design Technique by Tracing The Material Deformation Behavior (재료의 변형거동 추적을 통한 예비형상 설계)

  • Hong J. T.;Park C. H.;Lee S. R.;Yang D. Y.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.91-94
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    • 2004
  • Preform design techniques have been investigated in efforts to reduce die wear and forming load and to improve material flow, filing ratio, etc. In hot forging processes, a thin deformed part of a workpiece, known as a flash, is formed in the narrow gap between the upper and lower tools. Although designers make tools that generate a flash intentionally in order to improve flow properties, excessive flash increases die wear and forming load. Therefore, it is necessary to make a preform shape that can reduce the excessive flash without changing flow properties. In this paper, a new preform design technique is proposed to reduce the excessive flash in a metal forging process. After a finite element simulation of the process is carried out with an initial billet, the flow of material in the flash region is traced from the final shape to the initial billet. The region belonging to the flash is then easily found in the initial billet. The finite element simulation is then carried out again with the modified billet from which the selected region has been removed. In several iterations of this technique, the optimal preform shape that minimizes the amount of flash without changing the forgeability can be obtained.

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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
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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.

Preform Design for Forging by the Sensitivity Method (단조공정에서 민감도법을 이용한 예비 성형체 설계)

  • Shim H. B.;Noh H. C.;Son K. C.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.180-185
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    • 2001
  • The sensitivity method has been applied to find perform shape that results in the desired shape after forging. As a 2D example, initial shape of specimen for the cylinder shape without barrelling after forging has been found. The method is then applied to various shapes of 3D free forging and initial shapes of the corresponding specimens after forging have been found successfully. The sensitivity method is proven to be an effective and accurate tool for the preform design.

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민감도법을 이용한 단조 공정에서의 예비성형체 설계

  • 심현보;노현철
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • pp.291-296
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    • 2000
  • The sensitivity method has been applied to find perform shape that results in the desired shape after forging. As a basic example, initial shape of specimen for the cylinder shape without barrelling after forging has been found. The method is then applied to various shapes of 3D free forging and initial shapes of the corresponding specimens after forging have been found successfully. The sensitivity method is proven to be an effective and accurate tool for the preform design.

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A Preliminary Study on the Application of Three-Dimensional (3D) Printing Technologies to Hot Bulk Forming Processes - Example of Preform Design and Investigation of Hot-working Tool Steel Deposited Surface (3 차원 프린팅 기술의 열간 체적 성형 공정 적용에 관한 기초 연구 - 예비형상 설계 예 및 열간 금형강으로 적층된 표면 특성 분석)

  • Ahn, Dong-Gyu;Kim, Se-Hun;Lee, Ho-Jin
    • Journal of the Korean Society for Precision Engineering
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    • v.31 no.12
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    • pp.1093-1100
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    • 2014
  • The goal of this paper is to investigate preliminary the applicability of 3D printing technologies for the development of the hot bulk forming process and die. 3D printing technology based on the plastic material was applied to the preform design of the hot forging process. Plastic hot forging dies were fabricated by Polyjet process for the physical simulation of the workpiece deformation. The feasibility of application of Laser-aided Direct Metal Rapid Tooling (DMT) process to the fabrication of the hot bulk metal forming die was investigated. The SKD61 hot-working tool steel was deposited on the heat treated SKD61 using the DMT process. Fundamental characteristics of SKD 61 hot-working tool steel deposited specimen were examined via hardness and wear experiments as well as the observation of the morphology. Using the results of the examination of fundamental characteristics, the applicability of the DMT process to manufacture hot bulk forming die was discussed.

The Optimal Design of Preform in 3-D Forging by using Electric Field Theory (전기장 이론을 이용한 3차원 단조공정에서의 예비형상 설계)

  • 신현기;이석렬;박철현;양동열
    • Transactions of Materials Processing
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    • v.11 no.2
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    • pp.165-170
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    • 2002
  • The preform design of forging processes plays a key role in improving product qualities, such as defect prevention, dimensional accuracy and mechanical strengths. In the industry, preforms are generally designed by the iterative trial-and-error approach, but it results in significant tooling cost and time. It is thus necessary to minimize lead-time and human intervention through an effective preform design method. In this paper, the equi-potential lines designed in the electric field are introduced to find the preform shape, and then the optimization process is used to choose the equi-potential lines that will keep the die wear to a minimum Because, in the forging process, the die wear is a function of various important factors, such as forming stress and strain, microstructure and mechanical properties of a Product.