• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.7
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• pp.1685-1696
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• 1994

In this paper, a new forming process of the large-size forgings within the limit of forming loads is developed by introducing the incremental forging method and combined forming method. For the development of the forming process, various related processes are proposed and modelling experiments of plasticine and corresponding numerical simulation ate carried out. Thus, an optimal process considering the productivity and economical efficiency is recommended from the study of formability and forming loads, etc. The selected process is subjected to a modelling experiment of lead and 1/7 scale prototype experiment of the real material so as to verify the effectiveness of a selected process as well as to determine the design parameters. The developed process is then applied the forging product of dome shape. Dome-shaped forgings can be produced by the developed process within the limit loads and with the simple tools.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1142-1147
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• 2003

The formability of sheet metal appears better in incremental forming than in conventional forming. in this study, the effect of process parameters - tool type, tool size, feed rate, friction at the interface between tool and sheet, plane-anisotropy of sheet - on the formability was investigated by experiments and FEM analyses. it was found that the formability is improved when a ball tool of a particular size is used with a small feed rate and a little friction. Due to the plane anisotropy, the formability differs according to the direction of the tool movement. in this paper, details of the experimental procedures and the results obtained from the study are discussed.

• Transactions of Materials Processing
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• v.20 no.4
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• pp.279-283
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• 2011

Recently incremental sheet metal forming (ISF) has used widely in making prototypes and small-volume products in automotive industry etc. We apply the ISF to make a 1/4 sized automobile body-in-white. First, ISF tests for rectangular shaped cup have been performed to clarify the formability denoting the relationship between the component wall angle and maximum cup height of safe forming. Next, a CAD model for the automobile was designed and segmented into several components in order to accommodate the working space of the CNC machine we adopted and the formability of the sheet metal. Then, a CAM software was employed to generate the tool path for manufacturing wooden dies and all the small parts. Finally, the different parts were joined into a single component by laser welding after the ISF process. By using the ISF we successfully produced the 1/4 sized automobile body-in-white.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.125-126
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.405-408
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• 2004

The sheet parts are formed with dies conventionally. But this conventional forming process is not suited to small volume and varied production for the reason of high cost. For the solution of this problem, a new forming process, which is called CNC incremental sheet forming, is being introduced. This process can form sheet parts without die, and is very well suited to small volume and varied production in space flight and automobile. In this paper, dieless CNC forming system based on a machining center is developed. A special device to grasp and pull the blank sheet built in the machining center and tool path generation S/W from STL file of 3-D model are developed. Several sheet parts are incrementally formed to verify the effectiveness of the developed system.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.184-187
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• 2004

The sheet parts are formed with dies conventionally. But this conventional forming process is not suited to small volume and varied production for the reason of high cost. For the solution of this problem, a new forming process, which is called CNC incremental sheet forming, is being introduced. This process can form sheet parts without die, and is very well suited to small volume and varied production in space flight and automobile. In this paper, dieless CNC forming system based on a machining center is developed. A special device to grasp and pull the blank sheet built in the machining center and tool path generation S/W from STL file of 3-D model are developed. Several sheet parts are incrementally formed to verify the effectiveness of the developed system.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.207-212
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• 2009

In order to optimize the press formability of incremental sheet forming for complex shape (e.g human face), a combination of both CAM and FEM simulation, is implemented and evaluated from the histories of stress and strain value by means of finite element analysis. Here, the results, using ABAQUS/Explicit finite element code, are compared with fracture limit curve (FLC) in order to predict and optimize the press formability by changing parameters of tool radius and tool down-step according to the orthogonal array of Taguchi's method. Firstly, The CAM simulation is used to create cutter location data (CL data). This data are then calculated, modified and exported to the input file format required by ABAQUS through using MATLAB programming. The FEM results are implemented for negative incremental sheet forming and then investigate by experiment.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.812-815
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• 2005

The incremental forming process employs several tens or hundreds of continuous local strokes, so the entire process is difficult to analyze due to much computation time and large computer memory. The objective of this work is to propose a new numerical scheme of the finite element method, automatic expansion of domain (AED), and to reduce computation time and computer memory. In the AED scheme, an effective analysis domain in each local forming step is defined and then the domain is automatically expanded in accordance with the repeated process. In order to verify the validity of the criterion for the AED scheme and the applicability of the AED scheme, two-dimensional incremental plane-strain forging process is first analyzed using the proposed scheme with various criteria and full domain. In addition, three-dimensional incremental radial forging process is analyzed to verify the applicability of the proposed scheme to a practical incremental forging process.

• Transactions of Materials Processing
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• v.28 no.6
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• pp.328-335
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• 2019

Demand for ultra-thin materials is increasing due to their light-weight and versatile properties. In this work, the formability of the ultra-thin stainless steel sheets of various thicknesses in the incremental sheet forming (ISF) process is investigated. The effects of the thickness on formability were evaluated with forming experiments of the truncated cone shape with 10° intervals. As the thickness of the material decreased, the maximum forming angle decreased and wrinkles also occurred quickly. The maximum forming angles in the truncated cone shape without the wrinkles for the thickness of 0.05 mm, 0.08 mm, and 0.1mm were 30°, 40°, and 50°, respectively. Wrinkles occurred in a twisted shape along the moving direction of the tool. As the material thickness increased, the size of the wrinkles increased.