• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.03b
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• pp.93-100
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• 1996

In this paper, a computer simulationtechnique for the forging process having a spring-attached die was presented . The penalty rigid-thermoviscoplastic finite element method was empolyed together with an interatively force-balancing method, in which the convergence was achieved when the forming load and the spring reaction force are in equilibrium within the user-specified allowable accuracy. The force balance was controled by adjusting the velocity of the spring-attched die. th minimize the number of internations, a velocity estimating schemewas proposed. Two application examples found in the related company were given. In the first application example, the predicted metal folw lines were compared with the acturally forged ones. in the second example, a hot forging process with a spring-attached die was simulated and the analyzed results were discussed in order to investigated the effects of spring-attached dies on the metal flow lines and the forming loads.

• Transactions of Materials Processing
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• v.12 no.6
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• pp.536-541
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• 2003

In this paper, the rigid-viscoplastic finite element method is employed together with an iteratively force-balancing method to analyze a piercing and trimming process with a spring-attached die in hot former forging. An actual piercing and trimming process with a spring-attached die is investigated in detail and a generalized analysis model is proposed. A multi-stage hot former forging process is simulated under various spring constants. The analyzed results are discussed in order to investigate the effects of spring constants on the metal flow lines and the formed shapes. Then an optimal piercing and trimming process in hot former forging is devised.

• Design & Manufacturing
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• v.12 no.3
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• pp.13-18
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• 2018

Flexible display tends to grow every year, It tends to be larger, slimmer, and higher in image quality. Therefore, accuracy is required in the manufacturing process of each part. In the curved monitor, the bottom chassis has a structure to which other parts can be attached. The accuracy of the curvature which the bottom chassis of the curve monitor monitors has is important. If the curvature error is large, serious defects such as cracks, warpage, twisting and the like occur. Curvature was analyzed using 3D scanner. In the Forming process and Restriking process steps, spring go occurred, and spring back occurred in the Notching process and Bending process steps. Even in the same process, it was confirmed that the curvature value varied depending on the formed shape.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.470-473
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• 2009

In this paper, back pressure forging processes of which back pressures are exerted by mechanical forces including spring reaction are simulated by three-dimensional finite element method. The basic three-dimensional approach extended from two-dimensional approach is accounted for. An axisymmetric backward and forward extrusion process having a back pressing die, which is exposed to oscillation of forming load due to variation of reduction ratios with stroke and its related frequent variation of major deforming region, is simulated by both two and three dimensional approaches to justify the presented approach by their comparison. A three-dimensional forging process having a back pressing die attached to the punch by a mechanical spring is simulated and the results are investigated to reveal accuracy of the presented approach.

• Transactions of Materials Processing
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• v.19 no.5
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• pp.273-276
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• 2010

In this paper, back pressure forging processes of which back pressures are exerted by mechanical forces including spring reaction are simulated by three-dimensional finite element method. The basic three-dimensional approach extended from two-dimensional approach is accounted for. An axisymmetric backward and forward extrusion process having a back pressing die, which is exposed to oscillation of forming load due to variation of reduction ratios with stroke and its related frequent variation of major deforming region, is simulated by both two and three dimensional approaches to justify the presented approach by their comparison. A three-dimensional forging process having a back pressing die attached to the punch by a mechanical spring is simulated and the results are investigated to reveal accuracy of the presented approach.