• 제목/요약/키워드: Metal Forming

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이중 곡률을 갖는 판재의 성형 공정의 개발에 대한 실험적 연구 (Experimental Study on the Development of a Forming Process for Manufacturing Doubly-curved Sheet Metal)

  • 양동열
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 1999년도 춘계학술대회논문집
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    • pp.18-21
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    • 1999
  • In this study in order to make doubly-curved sheet metal effectively a sheet metal forming process has been developed by adopting the flexibility of the incremental forming process and the principle of bending deformation which causes slight deformation to thickness The developed process is an unconstrained forming process with no holder. For this study the experimental equipment is set up with the punch-set which consists of two pairs of lower support-punches and one upper center-punch. In the experiments using aluminum sheet it is found that the curvature of the formed sheet metal is determined by controlling the distance between supporting punches in pairs and the forming depth of the center-punch. and the edge-forming method is proposed for forming the sheet metal into the balanced shape. The equation using process variables such as the distance between supporting punches in pairs and the forming depth of the center-punch is proposed for the prediction of the radii of curvatures of the formed shape and it is corrected by the experimental results and the FEM simulation results about whether springback takes place. It is found that according o the simulation there is a certain set of the distance between a pair of supporting punches and the forming depth of the center-punch which causes a little springback. It is thus shown that the radii of curvatures of the formed sheet metal can be predicated by the corrected equation unless significant springback occurs.

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점진성형에서 형상 정밀도에 영향을 미치는 공정 변수 (Effective Process Parameters on Shape Dimensional Accuracy in Incremental Sheet Metal Forming)

  • 강재관;정종윤
    • 산업경영시스템학회지
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    • 제38권4호
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    • pp.177-183
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    • 2015
  • Incremental sheet metal forming is a manufacturing process to produce thin parts using sheet metals by a series of small incremental deformation. The process rarely needs dedicated dies and molds, thus, preparation time for the process is relatively short as to be compared to conventional metal forming. Spring back in sheet metal working is very common, which causes critical errors in dimensions. Incremental sheet metal forming is not fully investigated yet. Hence, incremental sheet metal forming frequently produces inaccurate parts. This paper proposes a method to minimize dimensional errors to improve shape accuracy of products manufactured by incremental forming. This study conducts experiments using an exclusive incremental forming machine and the material for these experiments are sheets of aluminum AL1015. This research defines a process parameter and selects a few factors for the experiments. The parameters employed in this paper are tool feed rate, tool diameter, step depth, material thickness, forming method, dies applied, and tool path method. In addition, their levels for each factor are determined. The plan of the experiments is designed using orthogonal array $L_8$ ($2^7$) which requires minimum number of experiments. Based on the measurements, dimensional errors are collected both on the tool contacted surfaces and on the non-contacted surfaces. The distances between the formed surfaces and the CAD models are scanned and recorded using a commercial software product. These collected data are statistically analyzed and ANOVAs (analysis of variances) are drawn up. From the ANOVAs, this paper concludes that the process parameters of tool diameter, forming depth, and forming method are the significant factors to reduce the errors on the tool contacted surface. On the other hand, the experimental factors of forming method and dies applied are the significant factors on the non-contacted surface. However, the negative forming method always produces better accuracy than the positive forming method.

변형경로를 고려한 판재의 성형한계도 예측 (Prediction of Forming Limit Diagram Dependent on Strain History in Sheet Metal Forming)

  • 김낙수;최광규
    • 대한기계학회논문집A
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    • 제25권7호
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    • pp.1107-1118
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    • 2001
  • The forming limit diagram introduced by Keeler and Goodwin has been used generally to analyze the formability of sheet metal. However, path dependent forming limit curves based on the state of strain can be explained only by a single criterion which is based on the state. In this study, experimental forming limits in strain space of some metal sheets are transformed into forming limit curves in stress space. Effects of yield criterion are investigated in transforming the forming limit curves. Some important design aspects which are based on the close prediction of movements in forming limit curves during sheet forming are concluded.

판재의 점진성형법에 대한 기초연구 (A Basic Study on Incremental Forming Method for Sheet Metal)

  • 심명섭;박종진
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2000년도 추계학술대회 논문집
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    • pp.128-131
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    • 2000
  • The technology of incremental forming has drawn attention for small-batch production of sheet metal components. In the present investigation a forming tool containing a freely-rotating ball was developed and applied to forming experiments. Deformation characteristics including crack occurred during forming with this tool was examined for full annealed Al1050 sheet. The finite element analysis was successfully applied to this special type of forming process, and provided results that agree well with the measurements.

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가변금형의 박판 성형공정 적용 연구 (Study on Application of Flexible Die to Sheet Metal Forming Process)

  • 허성찬;서영호;구태완;김정;강범수
    • 소성∙가공
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    • 제18권7호
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    • pp.556-564
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    • 2009
  • Flexible forming process for sheet material using reconfigurable die is introduced based on numerical simulation. In general, this flexible forming process using the reconfigurable die has been utilized for manufacturing of curved thick plates used for hull structures, architectural structures and so on. In this study, numerical simulation of sheet metal forming process is carried out by using flexible dies model instead of conventional matched die set. The numerical simulation and experimental verification for sheet metal forming process using a flexible forming machine that is more suitable for thick plate forming process are carried out to confirm the appropriateness of the simulation process. As an elastic cushion, urethane pads are utilized using hyperelastic material model in the simulation for smoothing the forming surface which is discrete due to characteristics of the flexile die. In the flexible forming process for sheet metal, effect of a blank holder is also investigated according to blank holding methods. Formability in view of occurrence of dimples is compared with regard to the various punch sizes. Consequently, it is confirmed that the flexible forming for sheet material using urethane pad has enough capability and feasibility for manufacturing of smoothly curved surface instead of conventional die forming method.

이중 곡률을 갖는 판재 성형을 위한 롤셋(Roll Set) 성형 공정 개발 (Development of a Forming Process using the Roll Set for the Manufacture of a Doubly Curved Sheet Metal)

  • 윤석준;양동열
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2002년도 춘계학술대회 논문집
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    • pp.44-47
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    • 2002
  • In order to make a doubly curved sheet metal effectively, a sheet metal forming process has been developed by adopting the flexibility of the incremental forming process and the principle of bending deformation which causes slight deformation to thickness. The developed process is an unconstrained forcing process with no holder. For this study, the experimental equipment is set up with the roll set which consists of two pairs of support rolls and one center roll. In the experiments using aluminum sheets and FEM simulation, it is found that the curvature of the formed sheet metal is determined by controlling the distance between supporting rolls in pairs and the forming depth of the center roll. The FEM simulation of the forming process using the roll set along the one path shows the distributions of the curvatures in two directions along the path, and gives information about the characteristics of the proposed forming process.

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저주파 가진 성형의 특성 분석 (Characteristic analysis of low frequency vibration forming)

  • 박찬진;최종필;박동영;홍남표;이혜진;이낙규;김성욱;주은덕;김병희
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2009년도 추계학술대회 논문집
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    • pp.254-258
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    • 2009
  • In this paper, the low frequency vibration forming system is developed for micro-patterns formation on the metal substrate. many researchers have studied about micro-forming technologies such as micro deep drawing, press forming, forging, extrusion etc. for the formation of precise micro-patterns on the surface of metal substrates, multi-step forming process must be used to improve qualifies of the deformed patterns. Since the low frequency vibration forming system could easily deform the surface of metal substrates, several steps of multi-step forming process should be removed by using the low frequency vibration forming system. In order to find optimal process conditions, we have carried out low frequency vibration forming process with varying the vibration frequency from 110Hz to 500Hz.

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디지털 이미지 상관관계를 이용한 알루미늄 합금 판재의 성형한계도 평가 (Experimental Study on the Forming Limit Curve of Aluminum Alloy Sheets using Digital Image Correlation)

  • 김용배;박정수;송정한
    • 융복합기술연구소 논문집
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    • 제5권1호
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    • pp.7-12
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    • 2015
  • Sheet metal formability can be defined as the ability of metal to deform without necking or fracture into desired shape. Every sheet metal can be deformed without failure only up to a certain limit, which is normally known as forming limit curve(FLC). In this paper, the dome stretching tests and tensile tests have been performed to obtain forming limit curve of aluminum alloy. During the experiment, failure strain is measured using digital image correlation(DIC) method. DIC method is a whole-field measurement technique that acquires surface displacements and strains from images information which characterized a random speckle as intensity grey levels. Recently years, this DIC method is being developed and used increasingly in various research. DIC results demonstrated the usefulness and ability to determine a strain.

무요소법에 의한 금속성형공정의 해석 (Analysis of Metal Forming Process Using Meshfree Method)

  • Han, Kyu-Taek
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2003년도 춘계학술대회 논문집
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    • pp.1569-1572
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    • 2003
  • Meshfree approximations exhibit significant potential to solve partial differential equations. Meshfree methods have been successfully applied to various problems which the traditional finite element methods have difficulties to handle, including the quasi-static and dynamic fracture. large deformation problems, contact problems, and strain localization problems. A meshfree method based on the reproducing kernel particle approximation(RKPM) is applied to sheet metal forming analysis in this research. Metal forming examples, such as stretch forming and flanging operation, are analyzed to demonstrate the performance of the proposed meshfree method for largely deformed elasto-plastic material.

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박판성형기술의 개발과 적용 (The Development and Application of Sheet Metal Forming Technology)

  • 박춘달;이장희;양동열;허훈;정동원
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 1994년도 박판성형기술의 진보
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    • pp.147-162
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    • 1994
  • Generally, the forming process of sheet metal is very complex and difficult process because of many variables such as tool geometry, material properties and lubrication. In this view point, the numerical analysis of sheet metal forming process is very difficult. High speed computer is used to model complex sheet metal forming process on a reasonable time scale. The design and development of sheet metal parts in the automotive industry and the need for improved sheet forming process and reduced part development cost have led to the use of computer simulation in tool/die design of sheet metal pressing. HMC(Hyundai Mator Company) has invested to develop programs for analysis of sheet metal forming process with connection of Universities. As a result, several programs were developed. Recently, the commercial software, PAM-STAMP of ESI was installed and is being tried to application of it to the real automotive panels. This article reviews the ongoing activities on development and application of analytical modeling of sheet metal forming at HMC.