• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.08a
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• pp.29-34
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• 2003

In order to study the shearing characteristics of anti-vibration sheet metal which has been bonded by resin, a blanking die of 40.02mm was manufactured to blank a material and it is used to reduce vibrational noise. The variables employed in this study were 1) Clearance 2) types of stripper plate, and 3) types of the die design technique. These variables were used to study the effects on burr height, diameter of product, and camber height. Lastly, the effect of the position of the rubber during blanking was observed. In the case of burr height from experimental investigation, the push-back die, combined with a movable stripper plate, resulted in the concentration of additional pressure between the cutting edges, meaning the crack initiation was delayed. This result was not affected by lubrication, although appropriate lubrication is preferred to enable a longer lasting die in terms of wear, which results from the presence of adhesive as the sheet metal is blanked. In the comparison of diameter measurement, the push-back die, combined with the back pressure from the knock-out plate showed a favorable precision. The use of the push back die with a fixed stripper plate, with a $4.5\%$ clearance, showed better accuracy in the diameter measurement. For comparing camber height, the push back die resulted in less cambering than the drop-through die. Also, the larger the clearance, the greater was the camber height. Considering experimental results, the shearing of anti-vibrational sheet metal is best achieved when the rubber is laying on the top, blanked with a fixed-stripper plate in a push-back die, with a $4.5\%$ clearance.

• Transactions of Materials Processing
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• v.12 no.8
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• pp.724-729
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• 2003

In order to study the shearing characteristic of anti-vibration sheet metal which is used to reduce vibration noise, a blanking die was manufactured to blank a workpiece. The variables employed in this study were clearance, type of stripper plate, position of the rubber layer and type of the die design. These variables were used to study the effects on burr height, blank diameter and camber height. In the case of burr height from experimental investigation, the push-back die, combined with a movable stripper plate, showed greater burr height. The rubber-top position of a workpiece resulted in better qualities regardless of working variables. In the comparison of diameter measurement, the use of the push-back die with a fixed stripper plate, with a 4.5% clearance, showed better accuracy. For comparing camber height, the push-back die resulted in less cambering than the drop-through die. Also, the larger the clearance, the greater was the camber height. Considering experimental results, the shearing of anti-vibrational sheet metal is best achieved when the rubber layer is laying on the top, blanked with a fixed stripper plate in a push-back die, with a 4.5％ clearance.

• Structural Engineering and Mechanics
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• v.65 no.4
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• pp.447-452
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• 2018

The controlling and prediction of spring back is one of the most important factors in sheet metal forming processes which require high dimensional precision. The relationship between effective parameters and spring back phenomenon is highly nonlinear and complicated. Moreover, the objective function is implicit with regard to the design variables. In this paper, first the influence of some effective factors on spring back in U-die bending process was studied through some experiments and then regarding the robustness of artificial neural network (ANN) approach in predicting objectives in mentioned kind of problems, ANN was used to estimate a prediction model of spring back. Eventually, the spring back angle was optimized using the Imperialist Competitive Algorithm (ICA). The results showed that the employment of ANN provides us with less complicated and time-consuming analytical calculations as well as good results with reasonable accuracy.

• Transactions of Materials Processing
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• v.15 no.5 s.86
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• pp.387-394
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• 2006

In order to see the effect of die deformation on the forming analysis of sheet metals, the draw-ins, strains, and spring-backs of an automotive fender panels are numerically simulated by considering the die deformation found by the simultaneous structural analysis of press and dies. By coupling the forming analysis and the structural analysis, the die deformation is simultaneously taken into account in the forming process. Furthermore, for the consideration of load difference transferred among the upper die, punch, and blank holder due to the changes in sheet thickness, the gap elements are employed instead of the blank sheet in the structural analysis. The numerical simulation results of an automotive finder draw panel are compared with the measurements. The comparison of the forming and spring-back analysis results between the rigid die and the deformed die shows that the consideration of tool deformation can predict more accurately the forming and spring-back of sheet metals.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.246-251
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• 2000

In the present study, the analysis on heat and fluid flow in the single screw extruder is carried out by simultaneously considering the metering section and the die. The finite difference method and the finite volume method are applied to the metering section and the die, respectively. The zonal method is used to couple the metering section and the die. To investigate the effect of die on the characteristics of heat and fluid flow in the single screw extruder, the pressure back flow is included in the analysis. The screw-tip rotation is also considered by employing the quasi 3-dimensional die model. The present results are compared with the numerical and experimental data available in the literatures.

• Design & Manufacturing
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• v.14 no.3
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• pp.37-43
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• 2020

Progressive drawing processing is one of the manufacturing processes used to mass-produce a variety of products on the industrial site. In this study, the goal is to achieve a uniform product thickness of at least 1.3mm by reducing the wall thickness of the coupler parts used in automotive air conditioning systems to within 15% using A5052-H32 materials. The progressive die was designed using Blank's law of volume invariance. Due to the characteristics of the drawing process, the material thickness in the punch R part decreases and the thickness in the die R part increases. When designing the progressive die of the coupler part, an ironing method, a push back method, and a stand-alone die pad method were applied to each process to design a mold in consideration of the drawing rate and to artificially adjust the thickness change. The suitability of the method used in die design was investigated by measuring the thickness change of forming parts for each process. In the final part, it was confirmed that the thickness measurement values of the five regions of a radial line were implemented as 1.34-1.36 mm.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.4
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• pp.450-456
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• 2002

Die desig for manufacturing hooks from steel wires has been depended on empirical procedures based on trial and error method. To design die, at first the curvature and bending angle of hook are computed by using AutoCAD and developed program which is composed of Visual Basic. Then spring back should be considered because the elastic recovery of material is very important in bending process. In this study, bending analysis of elastic-plastic materials is applied to predict curvature of hook and spring back. Therefore, systematic procedure of die design for bending hook is achieved to consider elastic recovery in terms of hook shapes. Experimental results are good agreement with calculated results.

• Journal of the Semiconductor & Display Technology
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• v.5 no.3 s.16
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• pp.5-10
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• 2006

This paper investigates cutting qualities after laser dicing and predicts the problems that can be generated by laser dicing. And through 3 point bending test, die strength is measured and the die strength after laser dicing is compared with the die strength after mechanical sawing. Laser dicing is chiefly considered as an alternative to overcome the defects of mechanical sawing such as chipping on the surface and crack on the back side. Laser micromachining is based on the thermal ablation and evaporation mechanism. As a result of laser dicing experiments, debris on the surface of wafer is observed. To eliminate the debris and protect the surface, an experiment is done using a water soluble coating material and ultrasonic. The consequence is that most of debris is removed. But there are some residues around the cutting line. Unlike mechanical sawing, chipping on the surface and crack on the back side is not observed. The cross section of cutting line by laser dicing is rough as compared with that by mechanical sawing. But micro crack can not be seen. Micro crack reduces die strength. To measure this, 3 point bending test is done. The die strength after laser dicing decreases to a half of the die strength after mechanical sawing. This means that die cracking during package assembly can occur.

• 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.