• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2005.09a
• /
• pp.9-12
• /
• 2005

The rapid thermal response (RTR) molding is a novel process developed to raise the temperature of mold surface rapidly to the polymer melt temperature prior to the injection stage and then cool rapidly to the ejection temperature. The resulting filling process is achieved inside a hot mold cavity by prohibiting formation of frozen layer so as to enable thin wall injection molding without filing difficulty. The present work covers flow simulation of thin wall injection molding using the RTR molding process. In order to take into account the effects of thermal boundary conditions of the RTR mold, coupled analysis with transient heat transfer simulation is suggested and compared with conventional isothermal analysis. The proposed coupled simulation approach based on solid elements provides reliable thin wall flow estimation fur both the conventional molding and the RTR molding processes

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2002.04a
• /
• pp.112-118
• /
• 2002

Injection molding process factors such as molding temperature, injection pressure, flow rate and flow velocity, must be controlled properly in filling and packing phases in the injection molding process. In this study, effects of these factors on the injection molding were investigated through the flow analysis fur the filling and packing phases. Molding troubles like flow mark, weld line, sink mark, short shot and warpage can be caused by these injection molding process factors. Among them, the short shot was caused by that the packing pressure could not reach properly to the filling end part in the packing phase and hence the flow rate could not be supplied to the full. In addition, as the flow rate for the volumetric shrinkage during the frozen phase could not be supplied properly by the packing pressure, the short shot appeared. Here, the volumetric shrinkage reduced with increasing the packing pressure and also the warpage of molded part increased with increasing the packing pressure.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.8 no.6
• /
• pp.64-70
• /
• 1999

Family injection molding of plastic is widely used to enhance productivity. Runners for molded products in fami-ly injection molding have to be balanced so that each of the producs is filled completely at the same time,. In this study computer simulations were performed to determine balanced circular section runners in family injection molding with two cavities where each of he cavity shapes is like a case. It was found from the computer simula-tions that runner balance could be fulfilled only by modifying runner diameters. But in order to get more quality molded products other process factors such as flow length flow resistance shapes of products and etc, should be taken in to consideration for the design of a family injection molding process.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.7 no.3
• /
• pp.25-29
• /
• 2008

In this paper, we design internal space in plunger-type low pressure vacuum injection molding machine from numerical study. And we study characteristic of viscoelastic flow for searching injection molding condition. Then the flow analysis was performed using the CAE S/W. The result shows optimal value of nozzle and hole in injection chamber. And we investigated qualitatively relationship between injection pressure and injection mass flow with variable shear rate

• Korea-Australia Rheology Journal
• /
• v.20 no.2
• /
• pp.79-88
• /
• 2008

In this study, we focus on the improvement of the filling efficiency in injection molding by application of ultrasonic vibration. While studies about the filling efficiency of typical filling processes in the injection molding have been widely performed, there have been only few studies about the filling efficiency of an ultrasonic process. The effect of the ultrasonic vibration is an important process condition, which influences the flow characteristics of polymer melt. This new condition even affects well-known injection conditions such as cavity pressure, injection temperature and mold temperature. For this study, we carried out a numerical analysis by appropriate modeling and analysis of the ultrasonic process in the filling process. To verify this numerical analysis, we compared the numerical results with the experimental data. Also, we analyzed the filling process in a thin cavity using this numerical analysis. To understand the flow characteristics of polymer melt in the ultrasonic process, we substituted real and complex vibration conditions with simplified and classified conditions according to the position of vibrating cavity surfaces and the phase difference between two opposing cavity surfaces. We also introduced MFR (melt flow ratio) as a new index to estimate the filling efficiency in the ultrasonic process.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.16 no.6
• /
• pp.21-28
• /
• 2007

Injection molding process factors such as molding temperature, injection pressure, flow rate and flow velocity, must be controlled properly in filling and packing phases in the injection molding process. In this study, effects of these factors on the injection molding were investigated through the flow analysis for birefringence and refractive index for pickup lens. This paper presents the birefringence and refractive index reduced with increasing the holding pressure and also the holding pressure time. And there are interaction with birefringence and fill time in the injection process. The optimal conditions through DOE are validated by using injection molding analysis.

• Design & Manufacturing
• /
• v.13 no.4
• /
• pp.34-39
• /
• 2019

In this paper, in order to improve the formability and quality of the injection molded parts in the molds for molding the motorcycle rear cowl injection molded parts with different volumes at the same time, the flow of the molded parts is changed through the injection molding CAE analysis by changing the gate position, runner size and position. It is to find the optimum gate position, the diameter of the runner and the position where the balance is equal. The molded article formed by the optimization resulted in the uniformity of the molten resin at the same time at the corner of the product, thereby maintaining the flow balance favorable for mass production at lower injection pressure.

• 한국연소학회:학술대회논문집
• /
• 2005.10a
• /
• pp.261-267
• /
• 2005

A comprehensive DES quality numerical analysis has been carried out for reacting flows in constant-area and divergent scramjet combustor configuration with and without a cavity. Transverse injection of hydrogen is considered over a broad range of injection pressure. The corresponding equivalence ratio of the overall fuel-air mixture ranges from 0.167 to 0.50. The work features detailed resolution of the flow and flame dynamics in the combustor, which was not typically available in most of the pervious studies. Much of the flow unsteadiness is related not only the cavity, but also to the intrinsic unsteadiness in the flowfield. The interactions between the unsteady flow and flame evolution may cause a large excursion of flow oscillation. The roles of the cavity, injection pressure, and heat release in determining the flow dynamics are examined systematically.

• Journal of Electrochemical Science and Technology
• /
• v.11 no.3
• /
• pp.248-256
• /
• 2020

In this study, pyrocatechol violet (Pcv) is proposed for the first time as an efficient electrocatalyst for oxidation of sulfide and flow injection analysis (FIA) of sulfide. A graphite pencil electrode (GPE) was modified with Pcv via immersion of the GPE into 0.01 M Pcv solution for 15 min. Cyclic voltammograms (CVs) demonstrated that Pcv/GPE exhibits a good electrocatalytic performance due to shift in the potential from +400 at bare GPE to +70 mV at Pcv/GPE and obtaining an enhancement in the peak current compared with the bare GPE. A linear range between 0.25 and 250 μM sulfide with a detection limit of 0.07 μM was obtained from the recorded current-time curves in Flow Injection Analysis (FIA) of sulfide. Sulfide in water samples was also successfully determined using the proposed FI amperometric methods.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2006.11a
• /
• pp.265-268
• /
• 2006

The preliminary design of a deep-sea injection system for carbon dioxide ocean sequestration is performed. Common functional requirements for a deep-sea injection system of mid-depth type and lake type are determined, Liquid transport system, liquid storage system and liquid injection system are conceptually determined for the functional requirements. For liquid injection system, the control of flow rate and temperature of liquid $CO_2$ in the injection pipe is needed in the view of internal flow. The function of depressing VIV(Vortex Induced Vibration) is also required in the view of dynamic stability of the injection pipe. A case study is performed for $CO_2$ sequestration capacity of 10 million tons per year. In this study, the total number of injection ships, the flow rate of liquid $CO_2$ and the configuration of a injection pipe are designed. The static structural analysis of the injection pipe is also performed. Finally the preliminary design of a deep-sea injection system is proposed.