Papers by Author: Jeong Jin Kang

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Authors: Sung Ho Chang, Young Moo Heo, G.H. Shin, Young Min Lee, Jeong Jin Kang, T.S. Jung
Abstract: Remarkable progress had been made in both technology and production of optical elements including aspheric lens. Especially, requirements for machining glass materials have been increasing in terms of limitation on using environment, flexibility of material selection and surface accuracy. In the past, precision optical glass lenses were produced through multiple processes such as grinding and polishing, but mass production of aspheric lenses requiring high accuracy and having complex profile was rather difficult. Against such a background, the high-precision optical GMP process was developed with an eye on mass production of precision optical glass pasts by molding press. This GMP process can produce with precision and good repeatability special form lenses such as for cameras, video cameras, aspheric lenses for laser pickup, f-θ lens for laser printer and prism, and fine glass parts including diffraction grating and V-grooved base. Generally, GMP process can be classified into batch and progressive type. In these types, because progressive type has many merits in that productivity is higher and repair/retouch of mold is easier than batch type, progressive GMP process is mainly used to produce aspheric glass lenses these days. In this paper, as a fundamental study to develop the multi-cavity mold for higher productivity of progressive GMP process used in fabrication of aspheric glass lens, compression tests for K-PBK40, which is the material of aspheric glass lens, were conducted at high temperature. As a result, flow characteristics of K-PBK40 were obtained for aspheric glass lens press simulation.
Authors: Jeong Jin Kang, Seok Kwan Hong, Sang Yong Lee, Sang Chul Lee, Sung Hee Lee
Abstract: In recent years, a lot of effort has gone into many researchers making components of specific functions, mimicking various microstructures in nature. In this study, a super hydrophobic surface on injection-molded liquid silicone rubber was fabricated, mimicking micro-bumps on a lotus leaf. Original patterns were machined by electric discharge machining and liquid silicone rubber was injection-molded by using the original patterns as molds. The hydrophobic characteristics of injection-molded liquid silicone rubber surface replicated from the original electric discharge machined surface were studied. According to variations of injection molding process parameters like mold temperature, injection speed, injection pressure, vacuum, etc. the variations of water contact angles, as a hydrophobic index, measured on the injection-molded surfaces were examined. The liquid silicone rubber surface molded from wire-cutting electric discharge machined surface at mold temperature 120°C, injection speed 5 mm/sec, injection pressure 70 bar and in a vacuum cavity showed water contact angle of 148°, which is close to super-hydrophobic level.
Authors: Jong Deok Kim, Jeong Jin Kang
Abstract: The use of turbochargers improves engine power, reduces the rate of fuel consumption. The vane lever is an important part of a turbocharger that regulates the volume of hot exhaust gas. Until now it has been produced by a 4 cavity fine blanking tool, but it requires the use of an 8 cavity fine blanking tool for better productivity. In this paper, we conducted structural simulation of an 8 cavity fine blanking tool and predicted the deformation of fine blanking tool elements. The maximum vertical deformation of the die was 0.01222mm and the maximum horizontal deformation of the die was 0.00096mm. This deformation led to a clearance change in the 8 cavity fine blanking tool. According to the simulation results, the calculated clearance was increased to a maximum of 45.9%, decreased to a minimum of 49.0%. Through the fine blanking experiment with the manufactured 8 cavity fine blanking tool, we demonstrated that 8 vane levers could be simultaneously produced by the 8 cavity fine blanking tool.
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