• Transactions of Materials Processing
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• v.11 no.8
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• pp.710-715
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• 2002

This paper describes the numerical determination of optimum blank diameter for sound material flow and high precise thread profile of a spindle screw through external thread rolling using two-three roll dies. Initial blank diameter affects the dimensional accuracy and surface finish qualities of a spindle screw in thread rolling process, therefore it is very important to determine the optimum blank diameter in thread rolling process. In order to determine the optimum blank diameter, this paper suggests the calculation method of initial bland diameter considering the real shape of tooth. The finite element code DEFORM is applied to analyze the metal flow of tooth, and these analytical results are verified by thread rolling experiment for spindle screw.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.133-137
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• 2002

This paper summarizes the results of a numerical study conducted to analyze the determination of optimum blank diameter on material flow and thread profile for Spindle Screw in external thread rolling. Initial blank diameter affect a quality of Spindle Screw in thread rolling process. Therefore, it is very important to determine the optimum blank diameter in thread rolling process. In order to determine the optimum blank diameter, this paper suggest the calculating method of initial blank diameter considering real shape of tooth. The finite element code DEFORM is applied to analyze the metal flow of tooth. then the analytical results are verified by experiment of thread rolling for Spindle Screw.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1861-1864
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• 2003

The objective of this study is to suggest the form rolling technology to produce high precision worm. Rack dies and roll dies are usually used to roll parts with worm teeth. The form roiling processes of worm shaft used as automotive part using the rack dies of counter flow type and the roll dies are considered and simulated by the commercial finite element code, DEFORM-3D. It is also important to determine the initial blank diameter in form rolling because it affects the quality of thread. The calculation method of the initial blank diameter in form rolling is suggested and it is verified by FE-simulation. The experiments using rack dies and roll dies are performed under the same conditions as those of simulation. The results of simulation and experiment in this study show that the from rolling process of worm shaft using the rack dies is decidedly superior to that using rolling dies from the aspect of the surface roughness and the profile of worm.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.10a
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• pp.149-152
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• 2000

By using a three-dimensional finite element program HydroFORM-3D based on a rigid-plastic model, the hydroforming process for automobile subfrmae is analyzed in this study. The goal of this study is to accomplish preform design and determine the level of internal pressure for producing final hydroformed subframe component. Prior to hydroforming, the initial tube blank must be bent to the approximate centerline of the final part to enable the tube to be placed in the die cavity, After then, a preforming operation like stamping is carried out to the prebent tube. Finally, hydroforming process is performed to the preformed tube to get the final production. And through ductile fracture theory, the failure, bursting, is predicted during hydroforming process for tube blank with different diameter.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.393-396
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• 2003

A systematic investigation for the process design in deep drawing is necessary to improve the quality of drawn cups. This study concentrates mainly on the influence of process design strategy on the product quality. Several types of process design were chosen from initial blank of 100mm in diameter to make final cup of 50mm in diameter. Forming analysis are carried out to find out optimal design in terms of drawing force. We assume that the case which shows minimum drawing force in the subsequent operations is the best case. Through experiments it is found that the case which shows minimum drawing force also results in minimum drawing force and better product quality than other case. Thus, it is shown that this design strategy is very effective in the improvement of quality in drawn cups.

• Transactions of Materials Processing
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• v.12 no.7
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• pp.647-653
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• 2003

A systematic approach for the process design in deep drawing is necessary to improve the quality of drawn cups. This study concentrates mainly on the influence of process design strategy on the product quality. Different types of process design were chosen from initial blank of 100mm in diameter to make final cup of 50mm in diameter. In order to make this cup, we used 2-stage deep drawing. Forming analyses are carried out to find out better design in terms of drawing force. It is proposed that the process design, in which maximum drawing forces during successive operations are equal, is a more desirable one. Through experiment, it is found that the proposed case shows equivalent values in terms of maximum drawing force during successive operations in real process and can achieve the best product quality in terms of dimensional accuracy. Thus, it is shown that proposed design is very effective in the improvement of quality in drawn cups and may be extended to deep drawing with more stages.