• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.660-665
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• 2014

Optimization of process parameters in polymer extrusion is an important task to reduce manufacturing cost. To determine the optimum values of the process parameters, it is essential to find their influence on the elongation of polymer breathable thin film. The significance of six important process parameters namely, extruder cylinder temperature, extruder speed, extruder dies temperature, cooling roll temperature, stretching ratio, stretching roll temperature on breathable film elongation of polymer extrusion was determined. Moreover, this paper presents the application of Taguchi method and analysis of variance(ANOVA) for maximization of the breathable film elongation influenced by extrusion parameters. The optimum parameter combination of extrusion process was obtained by using the analysis of signal-to-noise ratio. The conclusion revealed that stretching ratio were the most influential factor on the film elongation. The best results of film elongation were obtained at lower stretching ratio.

• 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 of Precision Engineering Conference
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• 2002.10a
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• pp.312-315
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• 2002

This paper summarizes the results of a numerical study conducted to analyze the effect of selected process parameters on material flow and thread profile in thread rolling of large diameter blanks. Based on the previous work where a plane strain mode was found to provide a reasonable approximation of the thread rolling process, the effect of varying thread form, friction factor, flow stress, and blank diameter on effective strain and thread height was analyzed using the finite element code DEFORM. This study show that effective strain for flank angle, that blank diameter had important effect on the as-rolled thread while flow stress, friction factor, and crest round of dies had significant impact on effective strain at the thread root and crest and load of thread rolling. While the rate of strain harding was found to have an effect on the crest profile, the results indicate that it is the primary factor responsible for seam formation in rolled threads.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.10
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• pp.57-64
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• 2004

The objective of this study is to suggest the form rolling technology to produce high precision worm on the base of three dimensional finite element simulation and experiment. It is important to determine the initial workpiece diameter in form rolling because it affects the quality of tooth profile. The calculation method of the initial workpiece diameter in form rolling is suggested and it is verified by finite element simulation. The form rolling processes of worm shaft used as automotive part using both the rack dies of counter flow type and the roll dies are considered and simulated with the same numerical model as actual process by the commercial finite element code, BEFORM-3D. Deformation modes of workpiece between the form rolling by the rack dies of counter flow type and the roll dies are investigated from the result of simulation. The experiments using rack dies and roll dies are performed under the same conditions as those of simulation. The surface roughness, the straightness and the profile of worm are measured precisely using the worm shafts obtained from experiment. The results of simulation and experiment in this study show that the form rolling process of worn shaft using the rack dies is decidedly superior to that using roll dies from the aspect of the precision of worm such as the surface roughness, the straightness and the profile of worm.