• Title/Summary/Keyword: Rolling contact

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The Rolling-Sliding Friction of Rubber and the Behavior of Contact Area

  • Uchiyama, Y.;Monden, N.;Miyao, T.;Iwai, T.
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2002.10b
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    • pp.189-190
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    • 2002
  • Rolling-sliding friction was investigated for three SBR (styrene-butadiene rubber) specimens including silica-filled, HAF carbon black-filled, and SAF carbon black-filled SBR. When a rubber wheel was rolled against a glass disk, the coefficient of friction varied with the slip ratios. The coefficient of friction for the silica-tilled SBR showed the highest value of the rubber specimens examined under various slip ratios. The contact areas of silica-filled SBR were larger than those of the carbon black-filled SBRs, as indicated the modulus of the silica-filled SBR showing the lowest value. The contact area during rolling-sliding friction was always smaller than those during the static contact. The friction force at the unit contact area for the silica-filled SBR under braking and driving was higher than those of carbon black-filled SBRs.

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Analytical Theory of Ball Bearing Considering Waviness of Rolling Elements (구름요소의 Waviness 를 고려한 볼베어링 해석 이론)

  • 정성원;장건희
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.11 no.7
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    • pp.275-286
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    • 2001
  • The research presents an analytical theory to calculate the characteristics of the bal bearing with waviness in its rolling elements considering the centrifugal force and gyroscopic moment of bal. The effects of centrifugal force and gyroscopic moment are introduced to the kinematic constraints and force equilibrium equations. and the waviness of rolling elements is modeled by sinusoidal function to calculate the contact force at each ball. The numerical solutions of governing equation of berating due to waviness are calculated by using the Newton-Raphson method. The accuracy of the research is validated by comparing the contact force. contact angle in case of considering the centrifugal force and gyroscopic moment of bal and the contact force and vibration frequencies in cases of considering waviness with the prior researches respectively. It investigates the stiffness, contact force. displacement and vibration frequencies of the ball bearing considering not only the centrifugal force and gyroscopic moment of ball but also the waviness of the rolling elements.

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Study on the effect of the surface rolling condition to the surface roughness (표면 Rolling시 작업조건이 표면조도에 미치는 영향)

  • 강명순;김희남
    • Journal of the korean Society of Automotive Engineers
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    • v.8 no.3
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    • pp.68-76
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    • 1986
  • The surface rolling method which is one of the plastic deformation processes increases the surface roughness and hardness of materials. In this study, three NACHI6000 ZZ bearing were used for surface rolling tool on the mild steel and high carbon steel. The purpose of this study is to investigate the effects of rolling speed, feed rate and contact pressure on the surface roughness. The following results have been obtained with the mild steel and high carbon steel. 1. The roller finishing method has increased surface roughness from 2.4 .mu.m Ra at initial ground surface to 0.17 .mu.m Ra-0.4 .mu.m Ra. 2. The contact pressure has influenced greatly on the surface roughness. There is an optimal contact pressure. 3. As the rolling speed and the feed rate decrease, the surface roughness improves. 4. The optimal contact pressure for the good surface roughness of SS40 and STC 3 has been at 213 Kgf/Cm$^{2}$ and 220 Kgf/Cm$^{2}$ respectively.

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Discussion on Wear Ope of Steel in Rolling Friction (철강재료의 구름마찰시에 발생하는 마모형태에 관한 연구)

  • 이한영
    • Tribology and Lubricants
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    • v.16 no.1
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    • pp.9-14
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    • 2000
  • It has been cleared in previous author's paper that the fatigue life before the pitting on the rolling contact surface with lubricant are influenced by the wear amount. In this study, the wear type has been clarified when wear amount is extremely large such as the case without lubricant. The test of rolling contact fatigue has been conducted under two different of herzian pressures and three different of slide ratios without lubricant. In addition, residual stress and half-value breadth using X-ray diffraction on worn surface have been measured as well as the wear amount. The results show that the pitting type wear by rolling contact fatigue has not been occurred when the wear amount is considerably large. Thus this type of wear has been deduced by the fatigue wear depending on delamination theory.

Treatment of Contact between Roll/Roll and Roll/Strip for Rolling Process Simulation (압연공정해석을 위한 판과 롤의 접촉 경계면 처리)

  • 김태효;황상무
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.05a
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    • pp.156-159
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    • 2003
  • Surface normal vector and surface velocity are very important parameters to simulate rolling processes precisely. In this study, Local displacement functions are constructed for each node on the contact surface and parameters are found by the least square fitting of displacement on the neighbor nodes. Deformation gradient tensor is calculated from the displacement function and surface normal vector and velocity also can be derived. Flat rolling simulation model is presented on the basis of the suggested contact scheme. Series of rolling process simulation are carried out and the results are compared with the experiments.

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Prediction of Rolling Noise of a Korean High-Speed Train Using FEM and BEM (유한요소법과 경계요소법을 이용한 한국형 고속전철의 전동소음 예측)

  • 양윤석;김관주
    • Journal of KSNVE
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    • v.10 no.3
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    • pp.444-450
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    • 2000
  • Wheel-rail noise is normally classified into three catagories : rolling impact and squeal noise. In this paper rolling noise caused by the irregularity between a wheel and a rail is analysed as follows: The irregularity between the wheel and the rail is assumed as linear superposition of sinusoidal profiles. Wheel-rail contact stiffness is linearized by using Hertzian contact theory and then contact force between the wheel and the rail is calculated. vibration of the rail and the wheel is calculated theoretically by receptance method or FEM depending on the geometry of the wheel or the rail for the frequency range of 100-500 Hz important for noise generation. The radiation noise caused by those vibration response is computed by BEM To verify this analysis tools rolling noise is calculated by proposed analysis steps using typical roughness data and these results are compared with experimental rolling noise data. This analysis tools show reasonable results and finally used for the prediction of the Korean high speed train rolling noise.

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A Behavior of Rolling Contact Fatigue on Retained Austenite in High-Carbon Chromium Bearing Steel (고탄소 크롬 베어링 강에서의 잔류 오스테나이트 변화에 따른 회전접촉 피로거동)

  • Jin, Jai Koan;Kim, Dong Keon
    • Journal of the Korean Society for Heat Treatment
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    • v.7 no.3
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    • pp.190-198
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    • 1994
  • In order to study the effect of retained austenite on rolling contact fatigue in high-carbon chromium bearing steel, retained austenite was controlled by only tempering temperature, individually 200, 220 and $240^{\circ}C$. Among various microstructural alteration during rolling contact fatigue test, plate-like carbide most related to the flaking at sub-surface of contact pressure. The plate-like carbides formed during rolling contact fatigue test decrease with increasing tempering temperature, and fatigue life is much more improved. The retained austenite was decreased with the tempering temperature, and that decreased plate-like carbide formation. Therefore fatigue life is much more improved with decreasing retained austenite.

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Estimation of Fatigue Damage Due to Rolling Contact in a Railway Wheel Using FEM Analysis (유한요소법을 이용한 철도 차륜에서 구름 접촉으로 인한 피로손상 평가)

  • Lee, Sang-Hoon;Kim, Ho-Kyung
    • Journal of the Korean Society of Safety
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    • v.26 no.3
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    • pp.1-7
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    • 2011
  • Fatigue damage on the train wheel surface was estimated by considering the effect of friction coefficient of rolling on the contact surface between the wheel and rail during operation. From FEM analys, the maximum Tresca stress was 550.7 MPa at a depth of 2.07 mm under the maximum contact pressure ($P_{max}$ = 894.3 MPa) between wheel and rail. The maximum stress continued to increase along with the increase in the frictional coefficient. The fatigue initiation lifetime of the wheel by the rolling contact was predicted using the Smith-Watson-Topper (SWT) equation and the maximum principal strain equation (${\varepsilon}$-N).