• Title/Summary/Keyword: Volume Friction

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Static Characteristic Analysis of Mechanical Face Seal Used for Boiler Feedwater Pump (보일러 급수 펌프용 미케니컬 페이스 실의 정특성 해석)

  • Kim, Dong-Wook;Jin, Sung-Sik;Kim, Jun-Ho;Kim, Kyung-Woong
    • Tribology and Lubricants
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    • v.26 no.4
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    • pp.230-239
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    • 2010
  • Mechanical face seal installed in boiler feedwater pump prevents leakage of working fluid using thin fluid film between stator and rotor. If the leakage of working fluid exceeds the allowable volume, serious malfunction of boiler feedwater pump will be happen. The thinner fluid film exists between stator and rotor, the less working fluid leaks out. However, if the thickness of fluid film is not enough, the wear of seal face will be increased. And it causes the decrease in life of mechanical face seal. Therefore appropriate design is necessary to maximize the performance and life of mechanical face seal. In this study, numerical analysis using finite volume method was conducted to investigate the static characteristics of wavy mechanical face seals which have 4 different wavy surface profiles on rotor. As a result, opening force, leakage volume of working fluid and friction torque were obtained. For the same minimum film thickness, the static characteristics of mechanical face seal were affected by the wavy surface profile which can change the thickness of working fluid film and pressure distribution.

Friction, Wear and Scuffing Life of Piston Rings With Several Coating for Low Friction Diesel Enging (다양한 박막을 증착한 디젤 엔진용 피스톤링과 실린더 블록의 마찰 마멸 및 스커핑 수명 평가)

  • Ahn, Tae-Sik;Cho, Dae-Hyun;Oh, Chung-Soon;Lee, Young-Ze
    • Tribology and Lubricants
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    • v.23 no.4
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    • pp.170-174
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    • 2007
  • Wear and scuffing tests were conducted using friction and wear measurement of piston rings and cylinder blocks in low friction diesel engine. The frictional forces, wear amounts and cycles to scuffing in boundary lubricated sliding condition were measured using the reciprocating wear tester. The cylinder blocks were used as reciprocating specimens, and the piston rings with several coatings were used as fixed pin. Several coatings were used such as DLC, TiN, Cr-ceramic and TiAlN in order to improve the tribological characteristics. From the tests wear volume of piston ring surfaces applied various coatings were compared. During the tests coefficients of friction were monitored. Test results showed that DLC coatings showed good tribological properties. TiN and Cr-ceramic coated rings showed good wear resistance properties but produced high friction.

Modeling of Friction Characteristic Between Concrete Pavement Slab and Subbase (콘크리트 포장 슬래브와 보조기층 간 마찰특성 모형화)

  • Lim, Jin-Sun;Son, Suk-Chul;Liu, Ju-Ho;Jeong, Jin-Hoon
    • International Journal of Highway Engineering
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    • v.12 no.4
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    • pp.211-218
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    • 2010
  • Volume of concrete slab changes by temperature and moisture effects. At that time, tensile stress develops because the slab volume change is restrained by friction resistance between the slab and subbase, and then crack occurs occasionally. Accordingly, researchers have made efforts to figure out the friction characteristics between the slab and subbase by performing push-off tests. Lately, researches to analyze concrete pavement behavior by the friction characteristics have been performed by finite element method. In this study, The friction characteristics between the slab and subbase were investigated based on the friction test results for lean concrete, aggregate, and asphalt subase widely used in Korean concrete pavements. The energy method bilinearizing relation between nonlinear friction resistance and displacement were suggested. The friction test was modeled by 3-D finite element program, ABAQUS, and the model was verified by comparing the analyzed results to the test results. The bilinear model developed by the energy method was validated by comparing analysis results obtained by using the nonlinear and bilinear friction resistance displacement relation as input data. A typical Korean concrete pavement was modeled by ABAQUS and EverFE and analyzed results were compared to evaluate applicability of the bilinear model.

A Combination Study on the Elevation Motion Friction Compensation Parameters in Gas Spring (1) (가스 스프링 Elevation 동작 마찰력 보상 변수 조합 연구 (1))

  • Lee, Jeong-Ick
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.5
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    • pp.657-666
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    • 2017
  • In this study, factor analysis was performed to reduce the friction in the elevation motion of a stand for a 50-inchtelevision. Pipe type cross-section control was used for accurate positioning control of the piston rod. The pipe type was also compared with a labyrinth-type crosssection for the orifice. The frictional force was then reduced using gas seal lip technology. Specifications were chosen, and a volume compensation experiment was carried out using an apparatus for compensating the volume of the cylinder, which is compressed by the volume of the piston rod. Based on CAE and experimental considerations, the labyrinth-type orifice is preferred for reducing friction. For the gas seal lip technology, outer and inner diameters of ${\Phi}20$ and ${\Phi}8$ for the hollow rod were more appropriate when assuming the weight of a 50-inch television to be 30kgf. The third is that the result of total consideration in stability problem and performance of volume compensation for specification decision and volume compensation experiment is determined the final speculation of hollow rod ?8x?4 and riveting system. The last is that the labyrinth orifice is not founded that of the ${\O}0.4{\sim}0.6$ orifice both tests on 300 mm intervals.

Tribological performance of some organic fluorine-containing compounds as lubricants

  • Liu, Weimin;Ye, Chengfeng;Xue, Qunji
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2002.10b
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    • pp.349-350
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    • 2002
  • The friction and wear behaviors of fluorine-containing compounds such as perfluoropolyethers (PFPE), phosphazenes (X-1P), ionic liquids as lubricants for steel/seel, steel/ceramic, ceramic/ceramic were investigated using a SRV tester and a one-way reciprocating friction tester both in ball-on-disc configuration. It was found that the three fluorine-containing lubricants could reduce friction coefficient and wear volume effectively. The effectiveness of the three lubricants in reducing wear volume could be ranked as ionic liquids>X-1P>PFPE. Tests also showed that aryloxyphosphazene with polar substituent as a lubricant of steel/steel pair gave low wear, while aryloxyphosphazene with nonpolar group on the phenyl pendant led to high wear. The morphology and the tribo-chemical reaction of the worn surfaces were analyzed with a scanning electron microscope (SEM) and X-ray photoelectron spectroscope (XPS). XPS analyses illustrated the formation of iron fluoride in steel/steel system with the lubrication of both phosphazenes and ionic liquids.

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The Analysis for Surface Hardening by Repeated Sliding Contact (반복 미끄럼 접촉에 의한 표면층의 경화에 대한 해석)

  • 박준목;김석삼
    • Tribology and Lubricants
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    • v.13 no.4
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    • pp.71-78
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    • 1997
  • Wear is affected by numerous factors-contact load, sliding velocity and distance, friction coefficient, material properties and environmental conditions. Among these wear factors, surface hardness is one of very important factors to determine wear. But surface hardness is varied by work hardening during repeated sliding contact. In this reason wear rate is increased or decreased with varying surface hardness, and transition of wear mechanism is happened. In this study, the surface hardening by accumulating residual stress was analyzed by considering the repeated sliding Hertzian contact model. The results showed that surface hardness was increased with increasing contact load, friction coefficient and contact number. And the depth of hardening layer, plastic layer and elastic layer depended upon contact load and number, but they didn't depend upon friction coefficient. The predicted surface hardness was about 1.5-1.8 times as hard as the material.

Analysis on the Causes and Countermeasures of Sino-US Trade Friction

  • Tan, Dan;Shuai, Xiaoyu
    • Asia-Pacific Journal of Business
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    • v.7 no.2
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    • pp.49-59
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    • 2016
  • The study attempts to investigate the causes of Sino-U.S. trade friction in recent years and provides countermeasures accordingly. The import and export volume of two countries, the product structure of China's export, the 337th Act lawsuits related to China, the industries involved in trade friction, and the G-L Index of Sino-U.S. Products are analyzed in detail. The causes of Sino-US trade frictions are discussed from the aspect of mercantilism and trade protectionism, interest groups and governments' trade policies, Chinese product structure, intellectual property protection in China, and performance of Chinese enterprises in litigation. Based on these, countermeasures are put forward. China needs to implement industrial upgrading, increasing the added value of products, and improving intellectual property protection. A trade friction warning system also needs to be constructed. The Chinese government needs to carry out strategic dialogue and international negotiation.

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A Study on Friction Coefficient Prediction of Hydraulic Driving Members by Neural Network (신경회로망에 의한 유압구동 부재의 마찰계수 추정 에 관한 연구)

  • 김동호
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.12 no.5
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    • pp.53-58
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    • 2003
  • Wear debris can be collected from the lubricants of operating machinery and its morphology is directly related to the fiction condition of the interacting materials from which the wear particles originated in lubricated machinery. But in order to predict and estimate working conditions, it is need to analyze the shape characteristics of wear debris and to identify. Therefore, if the shape characteristics of wear debris is identified by computer image analysis and the neural network, The four parameter (50% volumetric diameter, aspect, roundness and reflectivity) of wear debris are used as inputs to the network and learned the friction. It is shown that identification results depend on the ranges of these shape parameters learned. The three kinds of the wear debris had a different pattern characteristic and recognized the friction condition and materials very well by neural network. We resented how the neural network recognize wear debris on driving condition.

Friction and Wear Behaviors of WC-Co/WC-Co Pairs in Air

  • Hosokawa, H.;Nakajima, T.;Shimojima, K.
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.629-630
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    • 2006
  • To investigate sliding friction and wear behaviors of WC-Co/WC-Co pairs containing different WC grain sizes, the ball-on-disc test in air were carried out, where WC grain sizes a $0.5\;{\mu}m$ (F.G.) and $1.5\;{\mu}m$ (C.G.). The wear volume of F.G. pin for F.G. pin/C.G. disc is larger than that of F.G. pin for F.G. pin/F.G. disc due to higher friction coefficient, and the surfaces after wear test are richer in oxygen compared to those before test. Furthermore, the wear debris, which is composed of nona-scale grain, after the wear test are remarkably richer in oxygen than to those before test.

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A Study on the Absorption of Thermal Stress on the Underground piping for the District heating (지역난방용 매설배관의 열응력 흡수에 관한 연구)

  • Kong Jae Hyang;Sin Byung Kug
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.14 no.1
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    • pp.81-88
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    • 2005
  • There have been many studies on generation equipment and plant piping, but there is no significant study result on the heat transportation pipe. As such, this study established basic theory on the compensated method among buried pipe for regional heating, and further obtained the following results by applying the conditions of AGFW and NCHPP respectively in calculation of friction and maximum installation distance for the buried pipe. Friction coefficient according to the types and physical properties of soil, friction and maximum installation distance were compared to set the application value of friction coefficient according to the location of works. Calculation formula of clay load to be applied for calculation of friction was introduced to the formula of AGFW and the formula of NCHPP that has been used in Nowon district since 1997 to determine the difference and applicability. $120^{\circ}C$ and $95^{\circ}C$ were applied in temperature difference for expansion volume to compare the arm length at the curve pipe so thai it can be reflected in the design in the future. Maximum installation distance according to thickness of pipe was compared to present the necessity of unified specification so that same kinds of pipe materials can be used for same kinds of works.