• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.3
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• pp.1-6
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• 2012

This study is focused on simulation technology in injection molding process for plastic optic lenses. The CAE program, $3D-TIMON^{TM}$ is used for the injection molding simulation with O-PET resin material. The design for different gate shape and runner layout has been under review by CAE simulation results. Moreover, the prediction of birefringence and polarized light in injection molded optic lenses has been tested by the CAE Program. The simulation results have been expected to effectively use in the design of injection molding mould.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.4
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• pp.17-23
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• 2008

Development of die technology for holder and barrel dies is necessary according to minimization of lens assembly, image sensor, and connectors. In these cases, there are two technical problems arising from die design. One is determination of knock-out pin location in die set. Minimization of lens assembly size make it difficult to obtain ejecting space. The other is whether or not high-precision die technology is possible to reduce torque variation when holer and barrel products is assembled. In this study, multi-cavity die set was developed taking advantage of gear-driven ejecting method. In the developed technology, die manufacturing technology was guaranteed with a high-precision level.

• Design & Manufacturing
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• v.17 no.4
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• pp.57-62
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• 2023

As a representative method for mass production, a multi-cavity type mold capable of simultaneously molding products of the same shape can be applied. It has the advantage of improving the productivity from several times to several tens of times, but it may cause disadvantages which is the quality deviation with each cavity. This study, therefore, has tried to increase the cavity filling balance by using a melt flipper and a flow distance control part in the runner part of the mold. Along with this, the design and manufacturing of air vents during injection molding have been verified through experimental methods to achieve a higher level of multi-cavity filling balance and dimensional accuracy.

• Laser Solutions
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• v.12 no.3
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• pp.1-6
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• 2009

This paper describes the method for the fabrication of micro dot array on a plastic mold steel using DPSS (diode pumped solid-states) UV laser and wet etching process. We suggest the process of the ablation of a photoresist (PR) coated on plastic mold steel and wet etching process using solutions of various concentrations of $FeCl_3$, $HNO_3$ in water as etchant. This method makes it possible to fabricate metallic roller mold because the microstructures are directly fabricated on the metal surface. In the range of operating conditions studied, $17\;{\mu}J$ laser pulse energy and 50 ms laser exposure time, an etchant containing 40wt% $FeCl_3$, 5wt% $HNO_3$ and etch time for 45 s gave the $10\;{\mu}m$ of micro dot pattern on plastic mold steel.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.5
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• pp.225-231
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• 2003

The injection molding is a traditional manufacturing method that can make plastic parts by just one time in mold. Therefore, the injection molding has become one of a manufacturing method, which is widely applied in a producing of plastic products. Nowadays, to use of plastic parts has increased and plastic product-model using term has been shorten. By these reasons, using term of a injection mold has fast been reduced. These produced molds will be disused and leaved in a storage after a regular term to use it. These leaved molds are sometime sold as scrap iron. But, these molds have lots parts for recycling except special parts for example, cavities, cores and eject pins, etc. In this research, we investigated when the cavity and core of in injection mold would be changed, the injection mold could be recycled. We suggested the structures and standardizations for recycling of a moldbase. We also developed a program in which can be used when the recycling moldbase design in the Auto-CAD with the recycling standards. We called this program as the Recy-Mold. For the availability of the program and moldbase structure fur the recycling standards, we experimented a used mold for automobile lens, which was remanufactured by the recycling standard. The results of this test showed feasibility for the recycling mold.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.260-261
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• 2003

최근들어 플라스틱 렌즈는 여러 분야에 응용되고 있으며 광학적 시스템에도 널리 사용되고 있다. 광학적 플라스틱은 제작이 용이하고 크기에 제한을 받지 않아 그 수요가 크게 확대되고 있다. 그러나, 광학적인 시스템에 사용되기 위해서는 높은 순도가 요구되면서 또한 재질의 균일성이 확보되어야 하고 개구율이 점차 높아 가는 현실에서는 그 특성의 연구가 또한 중요하다. 본 연구에서는 간섭계를 구성하여 광학 디스크 경사에 따른 파면을 측정하고 광학수차 평가를 통하여 광학적인 시스템에 미치는 영향을 분석하였다. (중략)

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.163-164
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• 2000

We discuss the design and fabrication of CCD or C-MOS imaging lenses with hybrid diffractive / refractive optics. The hybrid lenses are made of optical grade plastic materials. We have been able to significantly reduce the number of elements while maintaining very high optical quality. This paper describes the conception, design, fabrication and evaluation of hybrid lenses in comparison with conventional refractive lenses. The new lens has excellent optical quality, very light weight, compact size and low manufacturing cost.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.4
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• pp.507-514
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• 2003

Most of CAE analyses for injection molding have been based on the Mele Shaw's approximation: two-dimensional flow analysis. in some cases, that approximation causes significant errors due to loss of the geometrical information as well as simplification of the flow characteristics in the thickness direction. Although injection molding analysis software using three-dimensional solid elements has been developed recently, such as Moldflow Flow3D, it does not contain a deformation analysis function yet. The present work covers three-dimensional deformation analysis or injection molded plastic parts using solid elements. A numerical scheme for deformation analysis has bun proposed from the results of injection molding analysis using Moldflow Flow3D. The accuracy of the proposed approach has been verified through a numerical analysis of rectangular plates with various thicknesses in comparison with the classical shell-based approach. In addition, the reliability of the approach has also been proved through an industrial example. an optical plastic lens, in comparison of real experiments.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.1
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• pp.71-81
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• 2009

Die steel for plastic molding were used as mold material of automobile parts and electronic component industry. The material of this paper has superior to mechanical properties, such as repair weldability, corrosion resistance and high temperature strength, required mold parts for semitransparent. Laser-induced surface hardening technology is widely adopted to improver fatigue life and wear resistance via localized hardening at the surface of mold parts. The objective of this research work is to investigate on the characteristics of surface hardening of the laser process parameters, such as beam travel speed, laser power and defocsued spot position, for the case of die steel for plastic molding. Lens for surface hardening of large area is plano-convex type with elliptical profile to maintain uniform laser irradiation. According to the experimental results, large size of hardened layer at the surface of die steel for plastic molding was achieved, and microstructure of this layer was lath martensite. Optimal surface status and mechanical property of hardened layer could be obtained at 1095Watt, $0.25{\sim}0.3m/min$, 0mm (focal length: 232mm) for laser power, beam travel speed, and focal position. Where, heat input was $0.793{\times}10^{3}J/cm^2$, and width of hardened layer was 27.58mm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.3
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• pp.465-470
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• 2006

Coating are needed on ophthalmic lenses to enhance both the mechanical durability of the relatively soft plastic surface and the optical performance of lenses. Organic-inorganic hybrid materials as molar ratio of 3-glycidoxypropyltrimethoxysilane(GPTS), methyltrimethoxysilane(MTMS) and tetraethyl orthosilicate(TEOS) were used to improve the surface characteristics and the optical properties on allyl diglycol carbonate lenses. Coating for these plastics were at $140^{\circ}C$ for 4hrs, applied using the sol-grl process flow-coating technique. The coated lens properties of transmittance, adhesion, pencil hardness, abrasion resistance, hot water resistance and chemical resistance were investigated. The optimum properties was obtained when the ratio of GPTS : MTMS : TEOS was 1:1:2, respectively.