• Journal of Advanced Marine Engineering and Technology
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• 제32권5호
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• pp.698-706
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• 2008

Performance improvement of Small hydro turbine is a very important subject to solve in the stage of introduction and development of the turbine. Cross-flow hydro turbine should be also studied more in detail for the turbine performance in order to extend the sites of application. In order to improve the turbine performance, the effect of the turbine shape on the turbine performance should be examined. Therefore, the effect of runner blade number on the turbine performance is investigated by use of a commercial CFD code. The results show that runner blade number gives remarkable effect on the efficiency and output power of the turbine. Pressure on the surface of the runner blade changes considerably by the blade number at Stage 1, but relatively small change of velocity distribution occurs in the flow passage.

• 한국금형공학회:학술대회논문집
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• 한국금형공학회 2008년도 하계 학술대회
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• pp.155-158
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• 2008

Flow imbalance among the cavities was often observed in multi-cavity mold. The flow imbalance affects on the dimensions and physical properties of molded articles. First of all, the origin of flow imbalance is geometrical imbalance of delivery system. However, even the geometry of delivery system is balanced the cavity imbalance is being developed. This comes from the temperature distribution in the cross-section of runner, which is affected by the operational conditions. In this study, experimental study of flow imbalance has been conducted for various injection speeds. This study also suggests new runner design to eliminate flow imbalance in multi-cavity injection mold. Simulation and experimental results showed suggested new designed runner could eliminate or reduce flow imbalance in multi-cavity injection mold.

• Design & Manufacturing
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• 제2권3호
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• pp.1-5
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• 2008

Plastic parts are molded for the purpose of mass production in injection molding. Therefore designer is usually designing molds that has geometrically balanced hot runner lay-out for filling balance at cavities. Although, mold is manufactured with geometrically balanced runner lay-out, there are actually filling imbalances in cavities. These filling imbalances phenomenon are caused by complicated interaction between melt and mold. In this paper, filling imbalances for internal gear based on injection molding in hot-runner mold were investigated by CAE and injection molding experiences.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 금형가공,미세가공,플라스틱가공 공동 심포지엄
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• pp.132-140
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• 2005

It is well known that the family-mold has an advantage to reduce the cost for production and mold. However, defects are frequently occurred by over packing the smaller volume cavity during molding, especially whorl the family-mold has a volumetric difference between two cavities. In this study, we confirmed the cavity-filling imbalance by the temperature and the pressure sensors, and developed a variable-runner system for the cavity-filling balance. We carried out experiments fur balancing the cavity filling in the family-mold with the variable-runner system, and confirmed a balanced cavity-filing through analyzing the temperature and pressure change in each cavity as the cross-sectional area of the runner changed. We also examined the influence of the injection-speed to the balancing-capability of the variable-runner system in the experiment.

• 소성∙가공
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• 제18권2호
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• pp.122-127
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• 2009

The injection mold with multi-cavity is essential for mass production of plastic products. Multi-cavity molds are designed to geometrically balanced runner system to uniformly fill to each cavity. However, despite geometrical balanced runner system, filling imbalances between cavity to cavity have always been observed in injection molding. To solve these problems, many studies such as Melt Flipper, RC Pin, and others have been presented. The results of these studies have been an effect on filling balances in multi-cavity molds. But, those have had a limitation that additional insert parts must have existed in the mold. In this study, a new runner system is suggested for filling balance between cavity to cavity using "Melt-Buffer" with simple change of runner shape. A series of simulation to confirm feasibility of Melt-Buffer's effects was conducted using injection molding CAE program. Also, a series of injection molding experiment was conducted using plastic materials such as ABS and PP. As results of this study, feasibilities of filling balances by Melt-Buffer were confirmed.

• Design & Manufacturing
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• 제2권6호
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• pp.23-27
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• 2008

It is well known that the family-mold has an advantage to reduce the cost for production and mold. However, defects are frequently occurred by over packing the smaller volume cavity during molding, especially when the family-mold has a volumetric difference between two cavities. In this study, the cavity-filling imbalance was confirmed by the temperature and the pressure sensors, and a variable-runner system was developed for balancing the cavity-filling. Experiments of balancing the cavity filling was carried out in the family-mold with the variable-runner system, and balancing the cavity-filling was confirmed by changing the cross-sectional area of a runner in the variable-runner system with the temperature and pressure sensors. The influence of the injection speed to the balancing-capability of the variable-runner system was also examined in the experiment.

• 소음진동
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• 제8권6호
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• pp.1062-1068
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• 1998

This paper describes the vibration characteristics of a high head pump-turbine runner. with nine blades and an outer diameter of 4.410 mm. of the pumped storage power plant. Mode shapes and natural frequencies were obtained by means of both the finite element analysis and modal testing. both in air and in water. The natural frequencies in air were calculated using the finite element method by ANSYS software. In order to confirm calculation results. the natural frequencies and mode shapes of the runner were measured using a hydraulic exciter both in air and in water. Natural frequencies of the pump-turbine runner were found at 174. 310 Hz in air, and at 107. 184 Hz in water. The first mode shape is flat plate mode with two nodal diameter and the second one is also flat plate mode with three nodal diameter. It can be shown that the natural frequencies of the pump-turbine runner in water is reduced approximately 40 ％ due to additional mass effect. Natural frequencies in air predicted by ANSYS software are in good agreement with test results.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 추계학술대회논문집
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• pp.54-57
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• 2004

Almost all injection molds have multi-cavity runner for mass production, which are designed with geometrically balanced runner system in order to minimize filling imbalance between cavity to cavity during processing. However, even though geometrically balanced runner is used, filling imbalances have sometimes been observed. These filling imbalances have historically been considered as result of uneven mold temperature and mold deflection, but it actually results from non-symmetrically shear, pressure, temperature distribution within melt material as it flows through the runner system. Filling imbalance could be decreased by modifying processing conditions that are related to shear, pressure, temperature such as injection rate, mold temperature, injection pressure, melt temperature. In this study, a series of experiment was conducted using Taguchi method to determine which processing condition influence as the primary cause of filling imbalance in geometrically balanced runner system. As a result of experiments, this paper could present an optimal processing condition to minimize variable that brings about filling imbalance geometrically balanced runner system

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.275-278
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• 2007

In family mold, defects are frequently occurred by an excessive packing the smaller volume cavity during molding. Although runner size could be optimized by CAE analysis or experimental data, the filling imbalance is hardly avoided in the actual injection molding process by various means. Before this study, we developed a variable-runner system for balancing the cavity-filling for three resins (ABS, LDPE, and PA66) in the family-mold, and examined the effect of cross-sectional area reduction of a runner in the system. In this study, we examined the conditions of the pressure and temperature in the system with a CAE analysis. We also analyzed the influence of the rheological characteristic of resins to the balancing-capability of the system in order to help mold designers easily adopt the variable-runner system to their design.

• 한국정밀공학회지
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• 제33권12호
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• pp.1021-1030
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• 2016

The runner system of the injection mould and the injection volume of the injection molding process greatly affect the quality of the produced part. The goal of this paper is the design of the runner system and the prediction of the injection volume for the injection moulding of a housing part of small-size air cleaner to improve the formability through the three-dimensional injection moulding analysis. The effects of the runner system of the mould on the injection moulding characteristics are investigated. From the results of the investigation, a proper design of the runner system with uniform filling characteristics and the minimized defect formation is obtained. In addition, the influence of the moving distance of the screw on filling characteristics, weldline formation and deformation characteristics is examined. From the results of the examination, an appropriate moving distance of the screw for the housing part of small-size air cleaner is estimated.