• Title, Summary, Keyword: Flexible pad

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Study on Development of Flexible Pad for High Speed Train Disk Brake (고속철도 디스크 브레이크의 유연 패드 개발에 대한 연구)

  • Lee, Min-Gyu;Kim, Joo-Yong;Kim, Jae-Min;Yang, Young-Min;Kim, Sang-Ho;Cho, Chong-Du
    • Journal of the Korean Society for Railway
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    • v.14 no.2
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    • pp.100-108
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    • 2011
  • This paper investigates the structural stability and reliability on improving performance of flexible brake pad used in high speed train. To this end, an improved model of flexible pad was obtained through structural analysis. Brake pad specimens were subjected to modal, stroke and endurance tests to examine the dynamic characteristics and mechanical stability. The hot spot generation with increasing rotational speed was observed on chassis dynamometer equipment and then the structurally uniform contact between the disc and pad was achieved. The temperature distribution of flexible pad was measured using the infrared camcorder. Hence, the proposed flexible pad showed the better structural stability and thermal energy emission.

Application of Flexible Sintered Brake Pad for TTX (한국형 틸팅열차용 Flexible 소결 브레이크 패드 적용 연구)

  • Ku, Seong-Mo;Lee, Dong-Kyun;Ko, Tae-Hwan;Na, Jong-Tae;Kim, Sang-Ho
    • Proceedings of the KSR Conference
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    • pp.597-603
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    • 2010
  • Metallic sintered brake pads are often applied to Mid/High Speed Train due to its high strength and thermal characteristics. Because of its imbalance contact between discs and pads can greatly influence the life span, one sided wear, discs attack/crack and threat the safety of the train during operation. In this research, we analyzed pressure/temperature distribution between brake pads and disks. Analyzed data had been verified and modified to conduct further tests of Flexible brake pads with small/full-scale dynamo test. Flexible brake pads were installed to TTX train to conduct further tests to identify the differences between Rigid brake pads and Flexible brake pads. In result, Flexible brake pads showed outstanding disk thermal stability, one sided wear, noise and life of pad than rigid brake pad.

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Application of Flexible-Type Sintered Brake Pads (플렉서블 타입 소결 브레이크 패드의 적용 연구)

  • Kim, Soung-Kwon;Kim, Sang-Ho;Kwon, Seok-Jin;Lee, Hi-Sung
    • Tribology and Lubricants
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    • v.27 no.1
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    • pp.19-24
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    • 2011
  • Metallic sintered brake pads are often applied to mid/high speed train due to their high strength and thermal characteristics. Imbalance contact between discs and pads can greatly influence the life span, one sided wear, discs attack/crack and threat the safety of the train during operation. In this research, we analyzed pressure/temperature distribution between brake pads and disks. Analyzed data had been verified and modified to conduct further tests of flexible brake pads with small/full-scale dynamo test. Flexible brake pads were installed to high speed train to conduct further tests to identify the differences between rigid brake pads and flexible brake pads. In result, Flexible brake pads showed outstanding disk thermal stability, one sided wear, noise and wear rate than rigid brake pad.

Tendency Analysis of Shape Error According to Forming Parameter in Flexible Stretch Forming Process Using Finite Element Method (유한요소법을 이용한 가변스트레치공정 성형변수에 따른 성형오차 경향분석)

  • Seo, Y.H.;Heo, S.C.;Song, W.J.;Kim, J.;Kang, B.S.
    • Transactions of Materials Processing
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    • v.19 no.8
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    • pp.486-493
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    • 2010
  • A shape error of the sheet metal product made by a flexible stretch forming process is occurred by a various forming parameters. A die used in the flexible stretch forming is composed of a punch array to obtain the various objective surfaces using only one die. But gaps between the punches induce the shape error and the defect such as a scratch. Forming parameters of the punch size and the elastic pad to prevent the surface defect must be considered in the flexible die design process. In this study, tendency analysis of shape error according to the forming parameters in the flexible stretch process is conducted using a finite element method. Three forming parameters, which are the punch size, the objective curvature radius and the elastic pad thickness, are considered. Finite element modeling using the punch height calculation algorithm and the evaluation method of the shape error, which is a representative value for the formability of formed surface, are proposed. Consequently, the shape error is in proportion to the punch size and is out of proportion to the objective curvature radius and the elastic pad thickness.

Study on Application of Flexible Die to Sheet Metal Forming Process (가변금형의 박판 성형공정 적용 연구)

  • Heo, S.C.;Seo, Y.H.;Ku, T.W.;Kim, J.;Kang, B.S.
    • Transactions of Materials Processing
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    • v.18 no.7
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    • pp.556-564
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    • 2009
  • Flexible forming process for sheet material using reconfigurable die is introduced based on numerical simulation. In general, this flexible forming process using the reconfigurable die has been utilized for manufacturing of curved thick plates used for hull structures, architectural structures and so on. In this study, numerical simulation of sheet metal forming process is carried out by using flexible dies model instead of conventional matched die set. The numerical simulation and experimental verification for sheet metal forming process using a flexible forming machine that is more suitable for thick plate forming process are carried out to confirm the appropriateness of the simulation process. As an elastic cushion, urethane pads are utilized using hyperelastic material model in the simulation for smoothing the forming surface which is discrete due to characteristics of the flexile die. In the flexible forming process for sheet metal, effect of a blank holder is also investigated according to blank holding methods. Formability in view of occurrence of dimples is compared with regard to the various punch sizes. Consequently, it is confirmed that the flexible forming for sheet material using urethane pad has enough capability and feasibility for manufacturing of smoothly curved surface instead of conventional die forming method.

Numerical Simulations for Suppressing Transverse Vibration of a very Flexible Rotating Disk using Air Bearing Concept (고속 회전 유연 디스크의 진동 저감용 공기 베어링 해석)

  • Lee Sung-ho;Rhim Yoon-chul
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • pp.175-185
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    • 2004
  • Rotating disks are used in various machines such as data storage device, gyroscope, circular saw, etc. Transverse vibration of a rotating disk is very important for the performance of these machines. This work proposes a method to suppress transverse vibration of a very flexible rotating disk in non-contacting manner. A system considered in this study is a very flexible rotating disk with a thrust bearing pad which is located underneath the rotating disk. The pressure force generated in the gap between the rotating disk and the thrust pad pushes the rotating disk in the direction of axis of rotation while the centrifugal force and the elastic recovery force push the rotating disk in reverse direction. The balance between these forces suppresses the transverse vibration of the rotating disk. A coupled disk-fluid system is analyzed numerically. The finite element method is used to compute the pressure distribution between the thrust pad and the rotating disk while the finite difference method is used to compute the transverse vibration of a rotating disk. Results show that the transverse vibration of the rotating disk can be suppressed effectively for certain combination of air bearing and operating parameters.

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Structure Design of Fall Impact Protection Pad Using 3D Printing Technology and Comparison of Characteristics According to Filament Material (3D 프린팅 기술을 활용한 낙상충격 보호패드 구조설계 및 필라멘트 소재에 따른 특성 비교)

  • Park, Jung Hyun;Jung, Hee-Kyeong;Lee, Jeong Ran
    • Journal of the Korean Society of Clothing and Textiles
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    • v.41 no.5
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    • pp.939-949
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    • 2017
  • This study uses 3D printing technology to design and fabricate a fall impact protection pad with a spacer fabric structure. The design of the pads consists of hexagonal three-dimensional units connected in a honey-comb shape; in addition, the unit consists of a surface layer and a spacer layer. Protect pads were designed as either a hexagonal type or diamond type according to the surface layer structure; subsequently, a spacer filament was also designed as the most basic I-shape type. Designed pads were printed using four types of flexible filaments to select suitable material for a fall impact protection pad. Impact protection performance and bending stiffness were evaluated for the eight type of pad outputs. As a result of the impact protection performance evaluation, when the force of 6,500N was applied, the force passed through the pad was in the range of 1,370-2,132N. FlexSolid$^{(R)}$ and Skinflex$^{TM}$ showed good protection performance and cubicon flexible filament showed the lowest protection. NinjaFlex$^{(R)}$ was found to be the most flexible in the bending stiffness evaluation.

Numerical Study on Effect of Using Elastic Pads in Flexible Forming Process (가변성형 공정에서 탄성 패드의 영향에 관한 수치적 연구)

  • Heo, Seong-Chan;Seo, Young-Ho;Noh, Hak-Gon;Ku, Tae-Wan;Kang, Beom-Soo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.5
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    • pp.549-556
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    • 2010
  • In general, materials that can be used to form elastic pads, such as urethane and rubber, are often used in flexible forming processes by inserting the pads between a blank and flexible die for smoothing the forming surface that is formed by a reconfigurable die. In this study, the effects of the elastic pad on formability in the flexible forming process for sheet metals are investigated by performing numerical simulations. In the simulation, the hyperelastic material model is used, where the urethane elastic pads serve as elastic cushions. Case studies are carried out for elastic materials with different hardness values and thicknesses. The results are used to evaluate formability by comparing the configuration of the deformed blank and its major cross-sectional profiles. It is verified that the elastic pad used in the flexible forming process for sheet materials should be hard and that its thickness should be chosen appropriately.

CMP Properties of Oxide Film with Various Pad Conditioning Temperatures (CMP 패드 컨디셔닝 온도에 따른 산화막의 연마특성)

  • Choi, Gwon-Woo;Kim, Nam-Hoon;Seo, Yong-Jin;Lee, Woo-Sun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.18 no.4
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    • pp.297-302
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    • 2005
  • Chemical mechanical polishing(CMP) performances can be optimized by several process parameters such as equipment and consumables (pad, backing film and slurry). Pad properties are important in determining removal rate and planarization ability of a CMP process. It is investigated the performance of oxide CMP process using commercial silica slurry after the pad conditioning temperature was varied. Conditioning process with the high temperature made the slurry be unrestricted to flow and be hold, which made the removal rate of oxide film increase. The pad became softer and flexible as the conditioning temperature increases. Then the softer pad provided the better surface planarity of oxide film without defect.