• Title, Summary, Keyword: Cavity Pressure

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Variations of Temperature and Pressure in the Cavity for Operational Conditions of Injection Molding (사출성형의 공정변수에 따른 캐비티 내의 온도와 압력의 변화)

  • Kim S. W.;Park H. C.;Lyu M.-Y.;Jin Y. S.;Kim D.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.70-74
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    • 2004
  • Pressure and temperature in the cavity of injection molding have been investigated. Special injection mold was designed to install pressure and temperature sensors. The sensors were supplied by KISTLER and the pressure and temperature were measured for various operational conditions, such as injection pressure, holding pressure, cooling time, mold temperature, and injection temperature. As injection pressure increased cavity pressure and temperature increase. There were no big differences in temperatures according to the holding pressures. As mold temperature increased pressure and temperature in the cavity increase. The flowability of resin increases as mold temperature increases subsequently the pressure in the cavity increases since the pressure loss is less in the low viscous medium than high ciscous medium. The cavity temperature highly depends upon mold temperature.

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An analysis of cavity pressure for various injection molding conditions (성형조건에 따른 캐비티의 내압분포 분석)

  • Kim, D.W.;Kim, S.Y.;Shin, K.S.;Kim, D.W.;Kim, K.Y.;Lyu, M.Y.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.293-296
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    • 2008
  • Injection molding operation consists of filling, packing, and cooling phase. The highest pressure is involved during the packing phase among the operation phases. Cavity pressure depends upon velocity to pressure switchover time and magnitude of packing pressure. The cavity pressure is directly related to stress concentration in the cavity of mold. Thus the observation and control of cavity pressure is very important to prevent mold cracking. In this study, cavity pressures were observed for operational conditions using the commercial CAE software, Moldflow. Operational conditions were velocity to pressure switchover time and packing pressure. Cavity pressures were also measured directly during injection molding. Simulation and experimental results showed good agreement.

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Experimental/Computational Study on the Supersonic Cavity Flow with a Sub-Cavity to Reduce the Pressure Oscillation (압력진동을 저감하기 위한 sub-cavity를 가진 초음속 공동유동에 대한 실험 및 수치해석적 연구)

  • Lim, Chae-Min;Lee, Young-Ki;Kim, Heuy-Dong
    • Proceedings of the KSME Conference
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    • pp.3009-3014
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    • 2007
  • The effectiveness of passive control techniques for alleviating the pressure oscillation generated in a supersonic cavity flow was investigated numerically and experimentally, respectively. The control device includes a sub-cavity installed near the leading edge of a rectangular cavity. Time-dependent supersonic cavity flow characteristics with turbulent features were examined by using the three-dimensional, mass-averaged Navier-Stokes computation based on a finite volume scheme and large eddy simulation. The results show that the pressure oscillation near the trailing edge dominates overall time-dependent cavity pressure variations. Such an oscillation can be attenuated more significantly in the presence of the sub-cavity compared with the cavity without sub-cavity, and a larger sub-cavity leads to better control performance.

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Water-Entry Induced Cavity Pressure

  • Lee, Min-Hyung
    • Journal of Mechanical Science and Technology
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    • v.14 no.5
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    • pp.562-568
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    • 2000
  • The pressure in a water-entry induced cavity, is analyzed up to the closed cavity (bubble). Water-entry is a highly transient phenomenon, and the evolution of the water-entry cavity must be explained by considering the entry speed, shape of the solid body, atmosphere pressure, and cavity pressure as the primary variables. This work is an extension of the cavity dynamics model recently reported by Lee (l997a). To extend the model for a wide range of entry speeds the cavity pressure is calculated from a one-dimensional quasi-steady flow model. The estimation of the cavity pressure allows us to explain the experimentally observed surface closure phenomena at low entry speeds. Predictions for the time of surface closure are compared with the published experimental data.

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A Study on Flow Balance and Cavity Pressure in Family Mold (FAMILY MOLD의 유동 밸런스와 금형 내압에 관한 연구)

  • 김태철;이대근;홍기복;김영근;박인수
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.603-607
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    • 2002
  • Cavity pressure is a factor of what is occurring inside the mold and is used as one of the process parameters that control the overall injection molding cycle. The insight of cavity pressure is able to predict part quality and optimum process condition. In this paper, it is adapted ejector pin sensor to measure the cavity pressure and investigates the flow balance and the cavity pressure according to different runner thickness for adjusting the flow balance. Flow balance is very important to have not the poor results such as flash and warpage in the family mold. This paper predicted flow balance and cavity pressure using CAE analysis tool and compared with the test results. The results of analysis and test have a good agreement with the cavity pressure profile and flow pattern of the test.

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Frozen Layer Effect on Internal Cavity Pressure during Injection Molding (사출성형 공정에서 고화층이 캐비티 압력에 미치는 영향)

  • Lee H.S.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.474-479
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    • 2005
  • Experimental and theoretical studies of internal cavity pressure during injection molding of a spiral tube cavity were carried out. The frozen layer thickness and the evolution of internal cavity pressure were calculated using a commercial software (C-MOLD). The evolution of the internal cavity pressure was recorded during injection molding of polystyrene into a spiral tube mold. To explain the differences observed between the calculated and measured internal cavity pressure, a pressure correction factor (PCF) was introduced based on the plane stress theory. This factor was determined by analyzing the stress state in the melt and calculating the frozen layer thickness near the mold wall. The corrected and experimental pressures have been compared to validate the applicability of the pressure correction factor.

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A Passive Control of Cavity-Induced Pressure Oscillations Using Sub-Cavity System (보조공동계를 이용한 공동 유기 압력진동의 피동제어)

  • Kang, M.S.;Kwon, J.K.;Lee, J.S.;Kim, H.D.;Setoguchi, T.
    • 한국전산유체공학회:학술대회논문집
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    • pp.452-455
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    • 2008
  • A new passive control technique of cavity-induced pressure oscillations has been investigated numerically for a supersonic two-dimensional flow over open rectangular cavities at Mach number 1.83 just upstream of a cavity, in which a sub-cavity system is installed on the backward-facing step of the main cavity. A third-order TVD (Total Variation Diminishing) finite difference scheme with MUSCL is used to discretize the spatial derivatives in the unsteady compressible Navier-Stokes equations. The results obtained show that the present sub-cavity system is very effective in reducing cavity-induced pressure oscillations. The results also showed that the resultant amount of attenuation of cavity-induced pressure oscillations was dependent on the length and thickness of the flat plate, and also on the depth of the sub-cavity used as an oscillation suppressor.

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A study on the measurement of cavity pressure and computer simulation (성형조건에 따른 캐비티 내압 측정 및 컴퓨터 모사)

  • Kim, D.W.;Kim, S.Y.;Shin, K.S.;Kim, D.W.;Kim, K.Y.;Lyu, M.Y.
    • 한국금형공학회:학술대회논문집
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    • pp.163-166
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    • 2008
  • Injection molding operation consists of filling, packing, and cooling phase. The highest pressure is involved during the packing phase among the operation phases. Cavity pressure depends upon velocity to pressure switchover time and magnitude of packing pressure. The cavity pressure is directly related to stress concentration in the cavity of mold. Thus the observation and control of cavity pressure is very important to prevent mold cracking. In this study, cavity pressures were observed for operational conditions using the commercial CAE software,Moldflow. Operational conditions were velocity to pressure switchover time and packing pressure. Cavity pressures were also measured directly during injection molding. Simulation and experimental results showed good agreement.

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The Pressure and Degree of Filling Balance between Cavity to Cavity in Multi-Cavity Injection Mold (다수 캐비티 금형에서 캐비티 간의 압력과 균형충전도)

  • Noh, Byeong-Su;Park, Tae-Won;Jeong, Yeong-Deug
    • Journal of the Korea Society of Die & Mold Engineering
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    • v.2 no.6
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    • pp.33-37
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    • 2008
  • Almost all injection molds have multi-cavity, which are designed with geometrically balanced runner system in order to made filling balance between cavity to cavity during injection molding. However, filling imbalance has been existed in the geometrically balanced runner system. In this study, we made an experiment and investigated that are filling balanced according to material. Also, in case of filling imbalance was occurred, we conducted experiments in order to find out difference of cavity pressure with cavity pressure sensor. When filling imbalance was occurred between cavity to cavity, we investigated the filling imbalance and pressure differences by computer-aided engineering(CAE).

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A Study on Cavity Pressure and Tensile Strength of Injection Molding (사출성형에서 캐비티압력과 인장강도에 관한 연구)

  • Yoo, J.H.;Kim, H.S.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.2 no.6
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    • pp.110-116
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    • 1994
  • In this research, the tensile strength of molded parts and pressure distribution were analyzed to study the cavity filling stage and packing stage in injection molding. The measurement of cavity pressure was obtained by a data acquisition system with the installation of transducers in the cavity. Molded parts were tested by a universal testing machine to obtain the tensile strength. For the experimental work, the tensile strength of molded parts increased with longer packing time and exact freezing time of the gate was obtained by a cavity pressure curve. In addition, the effect of packing did not occur and tensile strength was almost constant after early 1.5 sec of the freezing time of gate. Density tended to be higher about 0.2% due to a larger degree of mold temperature and melt temperature. Also, changing pressure in the cavity was effectively sensed. Thereafter, the possibility of the development of pattern recognition expert system was confirmed on the basis of the experimental results.

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