• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.87-90
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• 2004

In this paper, net-shape forming of an automobile gear is investigated. Barrel, a component of automobile start motor, is adopted as a net-shape forming. In order to accomplish the goal of net-shape forming without cutting of tooth and cam after forming, forming ability is raised through billet treatment and die design. As a technique of billet treatment spheroidizing annealing of billet to get low hardness and molybdenum disulphide coating to get low contact friction between billet and die is carried out. One of critical points of die design, fillet radii variation of tooth of die is applied to get smooth surface of barrel after cold forging. As a measurement of tooth accuracy, distance between two pins and lead-tooth alignments are investigated. Cam profile accuracy is checked with a 3D measuring instrument. Results obtained from the tests revealed reasonable result with respect to design goal. By these results, the paper shows that reasonable results can be obtained by billet treatment and die design for net-shape forming.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.211-214
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• 2006

The outer race of the constant velocity(CV) joint is an important load-supporting automotive part, which transmits torque between the transmission and the wheel. The outer race is difficult to forge, because its shape is very complex and the required dimensional tolerances are very stringent. Therefore, the internet based shape inspection system is developed in this study to provide quick and accurate data through the easy control from users. Proposed system uses mechanical displacement sensors to measure the shape of CV joint that has six inner ball grooves, and commercially available Lab-View program is used to process measured data into the dimensional shape. Developed program provides a simple user interface that enables users real-time access of data measured from industrial production lines. Furthermore, it can exchange measured data via the internet between users and forging system operators. A java applet helped the system connection via internet. A data, IP access, is transmitted to the packet by TCP/IP. Our proposed system has many advantages over current measuring systems including fast and efficient data processing by real-time control, and system flexibility.

• Journal of the Korean Society of Industry Convergence
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• v.19 no.2
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• pp.88-94
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• 2016

In this paper, we describe a new approch to control method of a four joints-robot gripper for the purpose of parts assemblying. The robot gripper is specifically modeled by using a 3D CAD program (ANSYS), considering artificial grippers, and then the proposed control method is illustrated through the dynamic simulation tool (Adams). Each gripper finger is individually controlled to be located at the optimal positions where the maximal joint torque can be calculated. To verified the effectiveness of the proposed control method, we proposed two cases for the reference position of gripper. By comparing the control performance of two method, the performance of the proposed control method was verified.

• Transactions of Materials Processing
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• v.28 no.3
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• pp.115-122
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• 2019

In this paper, finite element analysis of an automatic five-stage precision cold forging process of a yoke, a steering part of a passenger's car, is conducted with emphasis on spring back analysis at the yoke-forming stage and its experimental verification is subsequently made. An elastoplastic finite element method with MINI-element technique employed for the analysis of the entire process is explained. There is emphasis that the thin film of material formed between the punch and die in the stage may result to some errors especially in elastoplastic finite element analysis of spring back due to frequent remeshing. The numerical robustness of the spring back analysis in regards to remeshing is hence shown first through investigation into its effect on the predicted spring back. Experimental measurement of displacement due to spring back is carried out for comparison with the predicted results, and they are in a qualitative agreement with each other.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.4 no.4
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• pp.37-48
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• 1984

The yield-line analysis is used for earring out the limit analysis of reinforced concrete slabs which are for example like those of vertical walls of tanks subjected to the loads of hydrostatical type. It is considered both isotropic and orthotropic reinforcement using the coefficient of orthotropy with different edge conditions. The yield-line analysis is carried out by using the vertical work method and four collapse mechanisms including the fan mechanisms which is more realistic than over diagonal mechanisms is considered. It is found that the fan mechanisms are more complicated than ever simple diagonal mechanisms which have used for the orthotropically reinforced concrete slabs subjected to hydrostatic pressures. Especially Horton's study is extended in this study, and they are formulated to the constrained multi-variables nonlinear optimization problems, which are solved by the Rosen-Brock Hillclimb Procedure Program and are more critical.

• Korean Journal of Materials Research
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• v.10 no.1
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• pp.69-76
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• 2000

Despite the improved formability and processing advantages, the use of semi-solid metals is greatly limited due to the difficulties in controlling the optimum forming parameters. In the present study, the tensile properties of closed die, pressure formed semi-solid A356 alloy were examined. It was demonstrated that the tensile strength of thixoformed A356 alloy could be greatly reduced when the forming parameters were not rigorously controlled. The reduced strength of unappropriately formed products appeared to be related to the coarsening of the primary phases. The possibility of improving tensile properties of as-formed products by simple post heat treatment was also assessed.