• Title/Summary/Keyword: brake pad

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An Effect of Number of Passes in Wire-Cut Electric Discharge Machining on Fine Blanking Dies and Products (와이어 컷 방전가공에서 방전가공횟수가 파인 블랭킹 금형과 제품에 미치는 영향)

  • 유헌일;김세환;최계광
    • Transactions of Materials Processing
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    • v.6 no.3
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    • pp.192-202
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    • 1997
  • This study presents an effect of number of passes in wire-cut electric discharge machining on fine blanking dies and products. Three part fine blanking dies were produced by the difference of numbers of passes discharge machining. Brake pad was produced, through the die produced like that, the objective of this study is the improvement in surface roughness of die block and punch, life extension of die block, the decrease of second fracture dimensions, the rise of productive.

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Study for Characteristic of Frictional Heat Transfer in Rotating Brake System (회전을 고려한 브레이크 디스크의 마찰열전달 연구)

  • Nam, Jiwoo;Ryou, Hong Sun;Cho, Seong Wook
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.10
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    • pp.817-822
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    • 2017
  • The braking system is one of the most important components in vehicles and machines. It must exert a reliable braking force when they are brought to a halt. Generally, frictional heat is generated by converting kinetic energy into heat energy through friction. As the kinetic energy is converted into heat energy, high temperature heat is generated which affects the mechanical behavior of the braking system. Frictional heat affects the thermal expansion and friction coefficient of the brake system. If the temperature is not controlled, the brake performance will be decreased. Therefore, it is important to predict and control the heat generation of the brake. Various numerical analysis studies have been carried out to predict the frictional heat, but they assumed the existence of boundary conditions in the numerical analysis to simulate the frictional heat, because the simulation of frictional heat is difficult and time consuming. The results were based on the assumption that the frictional heat is different from the actual temperature distribution in a rotating brake system. Therefore, the reliability of the cooling effect or thermal stress using the results of these studies is insufficient. In order to overcome these limitations and establish a simulation procedure to predict the frictional heat, this study directly simulates the frictional heat generation by using a thermal-structure coupling element. In this study, we analyzed the thermo-mechanical behavior of a brake model, in order to investigate the thermal characteristics of brake systems by using the Finite Element method (FEM). This study suggests the necessity to directly simulate the frictional heating and it is hoped that it can provide the necessary information for simulations.

Experimental Investigation of Creep Groan Noise (크립 그론 소음 특성에 대한 실험적 연구)

  • Kang, Kyung Min;Jeon, Hyun Cheol;Kang, Yeon June;Cho, Min Hyung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.5
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    • pp.673-678
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    • 2013
  • Creep groan noise occurs at low frequencies immediately after releasing brake pressure or when a car stops. This noise can be used to predict problems in not only the brake system but also the vehicle system. Because of its complexity, it is difficult to determine its characteristics. Therefore, most improvements are conducted by changing the brake pad, and it still remains difficult to conduct a test using a vehicle. In this study, the characteristics of creep groan noise and the effects from a vehicle system are investigated by using vehicles and an NVH chassis-dynamometer through various tests. A new evaluation method for creep groan noise by using a vehicle is proposed, and the possibility of reduction schemes from the viewpoint of the vehicle system is confirmed from the results mentioned above.

Synthesis of Potassium Hexatitanate with Non-Fibrous Shape as a Raw Material for Friction Material in Brake System (자동차 브레이크 마찰재용 비침상형 육티탄산칼륨의 합성 연구)

  • Lee, Jung Ju;Lee, Na-Ri;Pee, Jae-Hwan;Kim, Jong-Young;Kim, Jeong-Joo
    • Korean Journal of Materials Research
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    • v.27 no.3
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    • pp.132-136
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    • 2017
  • We synthesized potassium hexatitanate, ($K_2Ti_6O_{13}$, PT6), with a non-fibrous shape, by acid leaching and subsequent thermal treatment of potassium tetratitanate ($K_2Ti_4O_9$, PT4), with layered crystal structure. By controlling nucleation and growth of PT4 crystals, we obtained splinter-type crystals of PT6 with increased width and reduced thickness. The optimal holding temperature for the layered PT4 was found to be ${\sim}920^{\circ}C$. The length and width of the PT4 crystals were increased when the nucleation and growth time were increased. After a proton exchange reaction using aqueous 0.3 M HCl solution, and subsequent heat treatment at $850^{\circ}C$, the PT4 crystal transformed into splinter-type PT6 crystals. The frictional characteristics of the friction materials show that as the particle size of PT6 increases, the coefficient of friction (COF) and wear amounts of both the friction materials and counter disc increase.

Analysis of the Effect of Contact Stiffness on the Out-of-plane Motion of a Disc Brake System using 2-DOE Model (2자유도 모텔을 이용한 디스크 브레이크의 면외 운동에 미치는 접촉강성의 영향 분석)

  • 신기홍;조용구;차병규;오재응
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.2
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    • pp.160-167
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    • 2004
  • A two degree-of-freedom mathematical model is presented to investigate the friction mechanism of a disc brake system. A contact parameter is introduced to describe the coupling between the in-plane and the out-of-plane motions. The model with the contact parameter is considered under the assumption that the out-of-plane motion depends on the friction force along the in-plane motion. In order to describe the relationship between the friction force and the out-of plane motion, the dynamic friction coefficient is considered as a function of both relative velocity and normal farce. Using this friction law, a contact stiffness matrix along the normal direction can be obtained. The out-of-plane motion is then investigated by both the stability analysis and the numerical analysis for various parametric conditions. The results show that the stiffness parameters of the pad and the disc must be controlled at the same time. Also, the numerical analysis shows the existence of limit cycle caused by the effect of intermittent contact stiffness.

The Roles of Reinforcing Fibers on the Performance of Automotive Brake Pads (자동차용 마찰재의 성능에 미치는 강화섬유의 역할)

  • Lim, Hyun-Woo;Yoon, Ho-Gyu;Jang, Ho
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2000.06a
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    • pp.173-179
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    • 2000
  • The friction and wear characteristics of brake friction materials reinforced with aramid fiber, carbon fiber, glass fiber, and potassium titanate whiskers were investigated using a pad-on-disk type friction tester. In particular, the morphology of rubbing surfaces was carefully investigated to correlate the friction performance and properties of transfer films. The aramid fiber reinforced specimen showed severe oscillation of friction coefficient at low speed and low applied pressure. The carbon fiber reinforced specimen showing better friction stability exhibited uniform and stable transfer film than any other specimens. The glass fiber reinforced specimen showed unstable friction changes at high speed and high-applied pressure and the non-uniform transfer film was observed in both friction material and rotor surface. The potassium titanate whiskers reinforced specimen showed stable coherent transfer film. The wear test exhibited the potassium titanate whiskers reinforced specimen was lowest in wear amount and glass fiber reinforced specimen showed the severe wear.

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Study on the Tribo-Characteristics of Tin-Bronze Matrix Material for Brake Pad (Brake Pad용 청동기지 복합재료의 마찰.마모특성에 관한 연구(I))

  • Song, Geon;Hwang, Soon-Hong;Kong, Ho-Sung;Choi, Woong-Soo;Cheong, Dong-Yun;Huh, Moo-Young
    • Tribology and Lubricants
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    • v.12 no.4
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    • pp.18-27
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    • 1996
  • An interlaboratory wear testing was performed in order to understand the friction behaviors and the wear mechanisms of the sintered composites. The specimens were the sintered bronze matrix composites having various contents of friction additives, friction control agents and reinforcements. The variation of the wear characteristics according to the constituents of the composites as well as the wear conditions was investigated by SEM, EPMA, OM, the hardness testing and the measurement of friction. The specimen having glass fiber as the matrix reinforcement showed a remarkable increase in wear resistance as increasing the content of glass fiber. Graphite particles in the composites exhibited the lubricating effect and also resulted in the lowering strength of the matrix. Addition of Mo powder to the composites led to the deterioration of wear properties at the room temperature, however, an enhanced wear properties were obtained in the containing Mo at an elevated temperature.

Factor Effects of Low-Frequency Instability of Brake System Using Complex Eigenvalue Analysis (복소 고유치 해석을 통한 브레이크 시스템의 저주파 불안정성 영향인자 분석)

  • Lee, Ik Hwan;Jeong, Wontae;Park, Kyung Hwan;Lee, Jongsoo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.6
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    • pp.683-689
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    • 2014
  • The present study conducted a parameter effect analysis of low-frequency squeal noise using a numerical simulation. The finite element program ABAQUS was used to calculate the dynamic instability based on a complex eigenvalue analysis. A total of five parameters, including the chassis, wear, piston, material property, and contact condition, were selected to identify the factor effects on a low-frequency squeal noise between 2.5 and 3.1 kHz. The present study found the dominant level of each factor through an analysis of the means in the context of the experiment design.

High Temperature Fade Behavior of Brake Friction Materials at Extreme Braking Conditions (실험통계법을 이용한 마찰재의 고온 마찰특성에 대한 고찰)

  • Ko, Kil-Ju;Park, Sang-Jin;Jang, Ho
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2001.11a
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    • pp.117-126
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    • 2001
  • Tribological properties of high temperature fade were investigated by changing relative amounts of ingredients in the brake friction material. Based on a simple experimental formulation containing 10 ingredients, friction materials were tested using a pad-on-disk type friction tester. Twenty-five friction material specimens with different relative amounts of the ingredients were manufactured according to the constrained mixture design .The difference ($\Delta$${\mu}$=${\mu}$$\sub$max/. -${\mu}$$\sub$min/. ) of friction coefficients was measured to represent the high temperature fade. Results from elevated temperature tests showed that five ingredients including cashew, graphite, Sb$_2$S$_3$, ZrSiO$_4$, and Cu fibers played important roles on $\Delta$${\mu}$. In order to find relative importance on fade phenomena among these ingredients, ANOVA(analysis of variance) was performed in this investigation. Thirty-two friction material specimens by changing ${\pm}$50vol.% of these five ingredients were tested to examine the relative importance. Results showed that cashew, graphite '||'&'||' Sb$_2$S$_3$, and cashew '||'&'||' graphite aggravated the fade behavior and Cu fibers improved on fade resistance.

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