• Title/Summary/Keyword: Roller Profile

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Development of Control Software for Daylight Responsive Dimming Systems and Automated Roller Shading Systems (광센서 조광제어시스템과 자동롤러쉐이딩 시스템을 위한 제어 소프트웨어 개발)

  • Hong, Seong-Kwan;Kim, Yu-Sin;Park, Byoung-Chul;Choi, An-Seop
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2008.10a
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    • pp.149-152
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    • 2008
  • The purpose of this study is to develop a control software for daylight responsive dimming systems and automated roller shading systems. Developed software in this study is to used determinate sky conditions, calculation of solar profile angle, control height of roller shade, calculation of dimming level(%) for daylight responsive dimming systems.

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Prediction of the Dynamic behavior and Contact Pressure of Overhung Rotor Systems According to the Support Characteristics of Double-row Tapered Roller Bearings (복열테이퍼 롤러베어링 지지특성에 따른 오버헝 회전축 시스템의 동적 거동 예측 및 접촉부 압력 해석)

  • Taewoo Kim;Junho Suh;Min-Soo Kim;Yonghun Yu
    • Tribology and Lubricants
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    • v.39 no.4
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    • pp.154-166
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    • 2023
  • This study establishes a numerical analysis model of the finite element overhung rotor supported by a DTRB and describes the stiffness properties of the DTRB. The vibration characteristics and contact pressure of the RBR system are predicted according to the DTRB support characteristics such as the initial axial compression and roller profile. The stiffness of the DTRB significantly varies depending on the initial axial compression and external load owing to the occurrence of rollers under the no-load condition and increase in the Hertz contact force. The increase in the initial axial compression increases the rigidity of the DTRB, thereby reducing the displacement of the RBR system and simultaneously increasing the natural frequency. However, above a certain initial axial compression, the effect becomes insignificant, and an excessive increase in the initial axial compression increases the contact pressure. The roller crowning radius, which gives a curvature in the longitudinal direction of the roller, decreases the displacement of the RBR system and increases the natural frequency as the value increases. However, an increase in the crowning radius increases the edge stress, causing a negative effect in terms of the contact pressure. These results show that the DTRB support characteristics required for reducing the vibration and contact pressure of the RBR system supported by the DTRB can be designed.

Pitting Life for RRP System (RRP 시스템의 피팅수명)

  • Kim, Chang-Hyun;Nam, Hyung-Chul;Kwon, Soon-Man
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.4
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    • pp.387-393
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    • 2012
  • A roller rack pinion (RRP) system, which consists of a rack-bar and a cam pinion, transforms a rotation motion into a linear one. The rack-bar has a series of roller trains, and meshes with the cam pinion. This paper first proposes the exact tooth profile of the cam pinion and the non-undercut condition to satisfy the required performance by introducing the profile shift coefficient. The paper then investigates the load stress factors under various shape design parameters to predict the gear surface fatigue limit, which was strongly related to the gear noise and vibration at the contact patch. The results show that the pitting life can be extended significantly with an increase in the profile shift coefficient.

Contact Surface Fatigue Life for RPG System (RPG 시스템의 접촉 피로수명)

  • Nam, Hyoung-Chul;Kwon, Soon-Man;Shin, Joong-Ho
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.11
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    • pp.1453-1459
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    • 2011
  • A roller pinion gear (RPG) system composed of either a pin or a roller and its conjugated cam gear can improve the gear endurance from that of a conventional gear system by reducing the sliding contact while increasing the rolling motion. In this paper, we first proposed the exact cam gear profile and the self-intersection condition obtained when the profile shift coefficient is introduced. Then, we investigated the Hertzian contact stresses and the load stress factors while the varying the shape design parameters to predict the gear surface fatigue life, which is strongly related to the gear noise and vibration at the contact patch. The results show that the pitting life can be extended significantly by increasing the profile shift coefficient.

Experimental Study on Oscillatory Behavior of Hydraulic Jump Roller (도수 롤러의 거동 분석을 위한 실험 연구)

  • Park, Moonhyung;Kim, Hyung Suk;Choi, Seohye;Ryu, Yonguk
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.30 no.6
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    • pp.319-325
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    • 2018
  • This study conducted an experimental investigation on oscillatory behavior of the hydraulic jump roller. Based on the similarity of the hydraulic jump and tidal bore, the behavior of the front face of hydraulic jump with increasing downstream water depth was studied focusing on profile and fluctuation. In this study, for statistical approach, the ensemble averaging was applied to obtain relevant front profile and compared with the time averaging. The front profile gets mildly sloped and the fluctuation of the starting point of hydraulic jump decreases as the downstream water depth increases.

A Study on the Cam Profile Synthesis Method for Automotive Engines Using Hermite Curve (Hermite 곡선을 이용한 자동차 엔진 캠 형상 합성법에 관한 연구)

  • Kim, D.J.;Lee, J.W.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.3 no.5
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    • pp.90-99
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    • 1995
  • A numerical method is proposed to synthesize automotive cam profiles. An arbitrary acceleration profile for the cam follower motion is divided into several segments, each of them is described by a Hermite curve. A cam profile is defined by control point locations and control variables assigned to each segment. Closed form equations are derived for velocity and displacement constraints which should be satisfied for the curve to be a cam profile. Because the method is flexible and provide arbitrary local controllability, any types of cam acceleration profile can be reproduced by the method. The method is expecially useful for the design of roller type OHC valve trains which need precise local control in the cam profile design to avoid under-cutting problems.

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Elastohydrodynamic Lubrication of a Profiled Cylindrical Roller (I) (프로파일링을 한 원통형 로울러의 탄성유체윤활 (I))

  • 박태조;김경웅
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.2
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    • pp.262-270
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    • 1988
  • A numerical solution of the elastohydrodynamic lubrication problem for an axially profiled cylindrical roller is presented. The problem is analyzed using finite difference method and Newton-Raphson method. The effect of side leakage and compressibility of lubricants are considered and axially nonuniform grid is constructed over the computation zone. Isobars, contours and section graphs show pressure variation and film shape. Contours plot is very similar to the previously reported experimental observations based upon optical interferometry. The maximum pressure and the minimum film thickness occur near the start of the profiling. The method used makes it possible to design an optimum axial profile of the roller to increase the life of rolling bearings.

Flash Temperature Analysis on the Contact Surfaces between Cam and Roller-Follower Mechanism (캠과 롤러 종동자 기구의 접촉표면 순간온도 해석)

  • Koo, Young-Pil;Kim, Min-Nam;Kim, Nam-Shik
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.3 no.2
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    • pp.86-94
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    • 2004
  • The flash temperature distribution on the contact surfaces between cam and roller-follower mechanism was analysed numerically. The elasto-hydrodynamic lubrication pressure and film thickness were used to get the accurate analysis results. The temperature distribution was obtained by numerical integration by making use of Carslaw and Jaeger's formulation to the whole contact surfaces. The maximum flash temperature was increased with both the increasing slip ratio of the contact surface and increasing external load Profile of the temperature distribution was affected by the sliding velocity of the surface.

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Numerical Analysis of Misaligned Finite Line Contacts EHL Problem (Misalignment가 있는 유한한 선접촉 EHL 문제의 수치해석)

  • Park, Tae-Jo
    • Tribology and Lubricants
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    • v.26 no.5
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    • pp.263-271
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    • 2010
  • The rollers of cylindrical roller bearing are axially profiled to relieve high edge stress concentration caused by mainly their finite length and by misalignment. In this paper, a numerical analysis is carried to study the EHL of misaligned (tilted) rollers with axially profiled ends. Using a finite difference method with non-uniform grids and the Newton-Raphson method, the highly nonlinear EHL problems are systematically solved. Physically consistent solutions are obtained for moderate load, material parameters and very small misalignment. For different misalignment angles, contours and sectional plots of pressure and film shape near both edge regions are compared. The asymmetric pressure distributions and film shapes show that the EHL results of finite line contacts are highly dependent upon very small amounts of roller misalignment. Especially, the effect of misalignment on the EHL pressure distribution is much higher than the film shapes.