• Title/Summary/Keyword: Core Injection

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A Study on Injection Characteristics of Piezo Injector with Bypass by Various Piezo Stack and Applied Voltage (바이패스 방식 피에조 인젝터의 피에조 적층 및 인가전압에 따른 연료분사 특성 연구)

  • Cho, Insu;Kim, Wootaek;Lee, Jinwook
    • Journal of ILASS-Korea
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    • v.25 no.1
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    • pp.1-7
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    • 2020
  • In the common rail fuel injection system, which is the core of diesel high efficiency and NOX reduction, injection strategies such as high pressure injection of fuel, accurate injection rate control, and multistage injection are important to increase fuel atomization. In this study, the bypass type piezo injector for the electronic control based common rail injection system applied to diesel fuel vehicle was studied. In particular, the injection rate and internal fuel flow characteristics of the high-pressure injector according to the piezo stacking number and applied voltage were analyzed by theoretical numerical method. When the applied voltage changes, it is determined that additional fuel flow through the bypass compensates for the reduced valve driving force due to the change in the driving voltage.

Powder Injection Mold Design for Dental Scaler (Dental Scaler 분말사출용 금형설계)

  • Park H. P.;Ko Y. B.;Chung S. T.;Rhee B. O.;Hwang C. J.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.05a
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    • pp.270-274
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    • 2005
  • The capability of net shaping for complex 3-D geometry, powder injection molding(PIM) is widely used for parts in the field of automotives, electronics and medical industry. Powder injection mold design for dental scaler tip, a component of medical appliance, was presented. In comparison with conventional machining process, powder injection molding has many advantages, specially in price and dimensional stability, for molding dental scaler tip. Product design and mold design for dental scaler tip was presented. Short shot experiment with scaler tip PIM mold and several defect (flash etc.) during injection molding process was discussed.

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Large core polymeric single mode waveguide for passive fiber alignment (광섬유 수동정렬을 위한 단일 모드 대형 코어 폴리머 광도파로)

  • Cho, Su-Hong;Beak, Yu-Jin;Oh, Min-Choel
    • Korean Journal of Optics and Photonics
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    • v.16 no.1
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    • pp.79-84
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    • 2005
  • To increase the tolerance for passive fiber alignment, a single mode polymer waveguide with a large core structure is demonstrated. The large core waveguide is designed to have a mode profile comparable to that of a thermally expanded core (TEC) fiber, and it can be connected to a high-contrast waveguide through an adiabatic transition taper structure. From a waveguide with a rectangular core of 25 ${\times}$ 25 ${\mu}{\textrm}{m}$$^2$, a single mode propagation is observed when the index contrast is as low as 0.0005. A UV-cured injection molding method is used to fabricate the thick core structure. Due to the large mode size, the insertion loss of the device is below 0.5 dB until the lateral displacement of the TEC fiber is 4.5 ${\mu}{\textrm}{m}$. The low insertion loss is important for reproducible passive alignment.

Influence of Mold Temperature on the Thickness of a Skin Layer and Impact Strength in the Microcellular Injection Molding Process (초미세 발포 사출공정에서 금형의 온도가 스킨층 두께와 충격강도에 미치는 영향)

  • Lee J.J.;Cha S.W.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1630-1635
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    • 2005
  • The microstructure of the parts made by the microcellular injection molding process influence properties, including impact strength, tensile strength and density of material. Microstructure of microcellular plastics is divided into core foaming region and solid skin region. Core foaming region is influenced by pressure drop rate, viscosity and cell coalescence. However, actual mechanism of the skin layers is not known despite its importance. The study on the skin layer is getting important because foaming rate of the plastics is determined by the thickness ratio of the skin layer. Especially in case of large molded part, control of the skin layer is needed because skin layer thickness is changed largely. Therefore it is necessary to study variation in skin layer thickness with processing parameters. In this paper, the influence of temperatures in the mold cavity on the skin layer s thickness was also addressed. In addition, the relationship between the temperature distributions across cavity of the mold with impact strength on parts made with the microcellular injection molding process was addressed. In addition, the method to predict the variation in skin layer thickness with mold temperature is discussed.

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Development of µ-PIM standard mold with exchangable insert core in order to manufacture micro pattern (마이크로 패턴 성형을 위한 인서트 코어 적용 µ-PIM 표준금형 개발에 관한 연구)

  • Park, Chi Yoel;Seo, Chan-Yoel;Kim, Yongdae
    • Design & Manufacturing
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    • v.11 no.3
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    • pp.29-34
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    • 2017
  • Increased demand for parts with micro-pattern structure made of metals, ceramics, and composites in various fields such as medical ultrasonic sensors, CT collimators, and ultra-small actuator parts. Micro powder injection molding (PIM) is a technology for manufacturing micro size, high volume, complex, precision, net-shape components from either metal or ceramic powder. In the present study, a standard mold with a variable insert core capable of producing various micro patterns was investigated. An injection molding test was performed on a standard mold using a line type micro-pattern core having an aspect ratio of 2, a slenderness ratio of 70, a pattern size of $200{\mu}m$, and a pattern spacing of $150{\mu}m$. During the filling process, the deformation of the mold with large aspect ratio and slenderness ratio was analyzed by the experiment and the numerical simulation according to the position of the gate. We proposed a mold structure that minimizes mold deformation by gate modification and enables uniform pattern filling behavior.

New Core-Layer Soft Decoding Method for ATSC3.0 LDM-MIMO Broadcasting Systems (ATSC3.0 LDM-MIMO 방송 시스템을 위한 새로운 Core-Layer 연판정 기법)

  • Baek, Hyeonguk;Kim, Seunghyeon;Kim, Hojun;Jung, Taejin
    • Journal of Broadcast Engineering
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    • v.24 no.6
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    • pp.1072-1075
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    • 2019
  • In this letter, we propose a new soft decoding method for a Core-Layer(CL) signal in ATSC3.0 Layered-Division-Multiplexing Multiple-Inputs-Multiple-Outputs broadcasting systems. Unlike a conventional Gaussian-Approximation(GA) method, the proposed method decodes the CL signal by reducing a Enhanced-Layer signal simply to a QPSK signal, and thus exhibits greatly improved performance compared to the GA method especially for a lower CL injection-level.

Numerical Analysis of Mold Deformation Including Plastic Melt Flow During Injection Molding (플라스틱 유동을 고려한 사출성형 충전공정 중 금형의 변형 해석)

  • Jung, Joon Tae;Lee, Bong-Kee
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.7
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    • pp.719-725
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    • 2014
  • In the present study, a numerical analysis of an injection molding process was conducted for predicting the mold deformation considering non-Newtonian flow, heat transfer, and structural behavior. The accurate prediction of mold deformation during the filling stage is important to successfully design and manufacture a precision injection mold. While the local mold deformation can be caused by various factors, a pressure induced by the polymer melt is considered to be one of the most significant ones. In this regard, the numerical simulation considering both the melt filling and the mold deformation was carried out. A mold core for a 2D axisymmetric center-gated disk was used for the demonstration of the present study. The flow behavior inside the mold cavity and temperature distribution were analyzed along with the core displacement. Also, a Taguchi method was employed to investigate the influence of the relevant parameters including flow velocity, mold core temperature, and melt temperature.