• Transactions of Materials Processing
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• v.14 no.7 s.79
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• pp.628-634
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• 2005

The drawability of AZ31B magnesium sheet is estimated at various temperatures (200, 250, 300, 350, $400^{\circ}C$), forming speeds (20, 50, 100mm/min), thicknesses (0.8, 1.4mm) and blank holding forces (2.0, 2.8, 3.4kN). The deep drawing process (DDP) of circular cup is used in forming experiments. The results of deep drawing experiments show that the drawability is well at the range from 250 to $300^{\circ}C$, 50mm/min forming speed and 2.0kN blank holding force. The 0.8mm magnesium sheets were deformed better than 1.4 mm. Blank holding force was controlled in order to improve drawability and prevent the change of cup thickness. When blank holding force was controlled, tearing and thickness change were decreased and limit drawing ratio was improved from 2.1 to 3.0.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.123-127
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• 1996

The tendency of wrinkling formation on the flange of a deep-drawn rectangular container was investigated experimentally under different process conditions. Such process variables as blank size, sheet thickness, blank-holding force, and depth of drawing are chosen to examine their effects on the flange wrinkles of the products. Number and amplitudes of the wrinkles are measured along the periphery of the flange and compared between each case of process condition.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.10a
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• pp.105-108
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• 2000

Finite element analysis of a multi-stage deep drawing process is carried out for the die design of rectangular cup drawing with the large aspect ratio. Simulation is performed for thorough investigation of unfavorable mechanisms in the initial design. The analysis reveals that the difference of the drawing ratio and the irregular contact condition produces non-uniform metal flow to cause wrinkling and severe extension. In this paper, the modification guideline is proposed in the design of the process and the tool shape. The analysis result confirms that the modified design not only improves the quality of a deep-drawn product but also reduces the possibility of failure.

• Transactions of Materials Processing
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• v.6 no.4
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• pp.300-310
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• 1997

A finite element inverse method is introduced for direct prediction of blank shapes, strain distributions, and reliable intermediate shapes from desired final shapes in axisymmetric multi-step deep drawing processes. This mothod enables the determination of process disign. The approach deals with the Hencky's deformation theory. Hill's second order yield criterion, simplified boundary conditions, and minimization of plastic work with constraints. The algorithm developed is applied to motor case forming, and cylindrical cup drawing with the large limit drawing ratio so that it confirms its validity by demonstrating resonably accurate numerical results of each problem. Numerical examples reveal the reason of difficulties in motor case forming with corresponding limit diagrams.

• Transactions of Materials Processing
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• v.21 no.1
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• pp.49-57
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• 2012

It is difficult to estimate the properties of multilayered sheet because they are composed of one or more different materials. Plastic deformation behavior of the multilayered sheet is quite different as compared to each material individually. The deformation behavior of multilayered sheet should be investigated in order to prevent forming defects and to predict the properties of the formed part. In this study, the mechanical properties and formability of stainless steel-aluminum-magnesium multilayered sheet were investigated. The multilayered sheet needs to be deformed at an elevated temperature because of its poor formability at room temperature. Uniaxial tensile tests were performed at various temperatures and strain rates. Fracture patterns changed mainly at a temperature of $200^{\circ}C$. Uniform and total elongation of multilayered sheet increased to values greater than those of each material when deformed at $250^{\circ}C$. The limiting drawing ratio (LDR) was obtained using a circular cup deep drawing test to measure the formability of the multilayered sheet. A maximum value for the LDR of about 2 was achieved at $250^{\circ}C$, which is the appropriate forming temperature for the Mg alloy. Fracture patterns on a circular cup and thickness of formed part were predicted by a rigid-viscoplastic FEM analysis. Two kinds of modeling techniques were used to simulate deep drawing process of multilayered sheet. A single-layer FE-model, which combines the three different layers into a macroscopic single layer, predicted well the thickness distribution of the drawn cup. In contrast, the location and the time of fracture were estimated better with a multi-layer FE model, which used different material properties for each of the three layers.

• Journal of Korea Society of Industrial Information Systems
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• v.27 no.1
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• pp.1-9
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• 2022

The goal of this paper is to create a deep learning model based on triplet loss for generating similar child drawing selection algorithms. To assess the similarity of children's drawings, the distance between feature vectors belonging to the same class should be close, and the distance between feature vectors belonging to different classes should be greater. Therefore, a similar child drawing selection algorithm was developed in this study by building a deep learning model combining Triplet Loss and residual network(ResNet), which has an advantage in measuring image similarity regardless of the number of classes. Finally, using this model's similar child drawing selection algorithm, the similarity between the target child drawing and the other drawings can be measured and drawings with a high similarity can be chosen.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.06a
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• pp.57-64
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• 1998

The purpose of this research is to develop a CAD/CAM system for generation all kind of information such as, total drawing, sub assembly drawing, part drawing, detail drawing, part list, and NC data for machining by CNC lathe, Wire CUT, machining center. Through this study the CAD/CAM System for deep drawing transfer die in mechanical press process has been developed. The developed CAD system can generate the drawing of transfer die in mechanical press. Using these results from CAD system, it can generate the NC data to machine die's elements on the CAD system. This system can reduce design man-hours and human errors. In order to construct the system, it is used to automate the design process using knowledge base system. The developed system is based on the knowledge base system which is involved a lot of expert's technology in the practice field. Using AutoLISP language under the AutoCAD system, CTK customer language of SmartCAM is used as the overall CAD/CAM environment. Results of this system will be provide effective aids to the designer and manufacturer in this field.

• Tribology and Lubricants
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• v.36 no.6
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• pp.350-358
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• 2020

Hot stamping is an effective and suitable process widely used in automotive applications, though critical issues such as the transfer of the coating materials and build-up of these materials on tool surfaces have been encountered. Past researches figured out the resultant wear phenomenon using pin-on-disc and drawing (for example, strip drawing and deep drawing) methods to mimic the process and analyzed the wear behavior with respect to the influencing factors such as surface coating, load, and roughness. Although the pin-on-disc is a conventional and widely-used method, it presented a methodological limitation when simulating the hot stamping process by forming a new blank each time, and hence, a drawing-based friction method has been proposed and developed. Each drawing method applies loads in a different way, resulting in a different wear behavior. Notably, the deep drawing process is most similar to the hot stamping process compared to other drawing methods. In this paper we present a review of the friction testing methods mimicking the hot stamping process and the associated wear behavior. This can be helpful in presenting a step-by-step approach and different perspectives on the wear behavior in the hot stamping process.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.279-280
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• 2007

In this study, it is investigated that the effect of material properties such as various temperature, forming speed and strain rates on formability and forming limits of Mg alloy sheet in square cup deep drawing. Since the sheet metal forming of Mg alloy is perform at elevated temperature, the effect of strain rates related with the forming temperature and forming speed is very important factor for formability and forming limits. Therefore, the investigation for process variables is necessary to improve formability and forming limits. Also, the effects of strain rate and thickness transformation were studied by the experimental and FE analysis using the square cup deep drawing. The temperature, forming speed, and strain rates were investigated. Forming of Mg alloy takes consider into temperature, proper forming speed and strain-rate the formed parts were good without defects fur forming limits.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1082-1086
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• 2004

Since the sheet forming of Mg alloy has many difficulties due to the low formability, many forming conditions need to be selected properly. Especially, the process variables should be investigated to increase the formability, such as, forming temperature. In this paper, the effects of forming process variables has been investigated using the bending and deep drawing process. A simple U-bending designed for mobile part could be formed in room temperature and springback amounts are surveyed. On the other hand, square cup part couldn't be formed in room temperature due to the low formability. Therefore, the effects of forming temperature are investigated in deep drawing process for square cup part. As a experimental and FEM results, the optimum forming temperature is presence and formability in a higher temperature is less than that of lower temperature. Above experimental results are compared with the FEM analysis and well coincided with the experimental results. Therefore, more detail investigations could be progressed to select more appropriate process conditions by the FEA.