• Title, Summary, Keyword: roller

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A Preliminary Study of Roller Types for Chip Seals Construction (Chip Seals 시공을 위한 롤러 종류에 따른 기초적인 연구)

  • Lee, Jae-Jun;Kim, R. Young-Soo
    • International Journal of Highway Engineering
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    • v.12 no.3
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    • pp.79-85
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    • 2010
  • This paper presents a preliminary study of roller types for chip seals based on aggregate retention performance. Chip seal test sections composed of single seals of granite 78M aggregate and CRS-2 emulsion were constructed using three different roller types: the pneumatic tire roller, steel wheel roller, and combination roller. In order to investigate the performance of these rollers effectively, it is critical to test chip seal samples obtained directly from field construction. Therefore, test sections were constructed on New Sandy Hill Church Road near Bailey, North Carolina. Chip seal samples obtained from these sections were used for laboratory testing. The aggregate retention performance was evaluated using the flip-over test (FOT), Vialit test, and the third-scale Model Mobile Loading Simulator (MMLS3). Based on the test results and visual observation, both the pneumatic roller and the combination roller used together are recommended to improve chip seal performance with the sequence of the pneumatic roller rolling first followed by the combination roller.

A Study on the Characteristics of the Wheel/Roller Contact Geometry (차륜/궤조륜 기하학적 접촉특성에 관한 연구)

  • Hur, Hyun-Moo
    • Journal of the Korean Society for Railway
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    • v.9 no.5
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    • pp.618-623
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    • 2006
  • Understanding the contact between wheel and rail is a starting point in railway vehicle dynamic research area and especially analysis for the contact geometry between wheel and rail is important. On the one hand, the critical speed as the natural characteristics of rolling-stock is generally tested on the roller rig. The geometrical characteristics of the wheel/roller contact on the roller rig are different from these of the general wheel/rail contact because the longitudinal radius of roller is not infinite compared with rail. Thus, in this paper we developed the algorithm to analyze the wheel/roller contact geometry of our roller rig which is constructed now and analyzed the difference between whee/roller contact and wheel/rail contact. In conclusion, we found that the yaw motion of wheelset and the roller radius influence the geometrical contact parameters in wheel flange contact area.

A Study on the Rolling Friction Characteristics of Large Scale Roller Shoe for Bridge Supporter (교량받침용 대형 Roller Shoe의 구름마찰특성에 관한 연구)

  • 김영득;김재철
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.660-663
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    • 2001
  • There is a mechanical device between the superstructure and substructure of a bridge, which transmit vertical load of superstructure to the substructure and absorb horizontal displacement of super structure due to thermal, dynamic, load, etc. In order to meet two requirements at once, the structure of roller between plates is widely used, and this roller between plates is widely used, and this roller shoe system is known to have smaller horizontal movement resistance than any other type of bridge shoe. In this study, rolling friction resistance characteristics of roller-plate friction system is investigated according to roller dimension, vertical load, hardness and roughness of roller and plate. On the base of the results, the rolling friction resistance of large scale roller shoe is evaluated using model experiment.

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Optimization of Roller Levelling Process for Aluminum 7001 Pipes with Finite Element Method and Taguchi Method (유한요소해석과 다구찌 방법을 이용한 알루미늄 7001 소재 파이프의 Roller Levelling 공정 최적화)

  • Heo J. H.;Lee H. W.;Huh H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.106-109
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    • 2001
  • Process parameters of roller levelling process are intermesh of each roller, roller angle, roller arrangement and shape of rollers. Experimental optimization of these process parameters is very troublesome because of difficulties in evaluating the straightness of pipes to be levelled quantitatively. Finite element method can be a very efficient way to evaluate the straightness of the pipes and therefore to optimize the process. This paper is concerned with simulation and optimization of a roller levelling process. Process parameters of a 14-roller levller for aluminum T9 pipes are optimized with finite element method and Taguchi method. Parameters of significance in roller levelling process and their optimum are obtained.

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A Study on the Noise Characteristics of Cylindrical Roller Bearings (원통형 로울러 베어링의 소음 특성에 관한 연구)

  • 노병후;김대곤;김경웅
    • Tribology and Lubricants
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    • v.19 no.6
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    • pp.342-348
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    • 2003
  • The purpose of the paper is to investigate the noise characteristics of cylindrical roller bearings. For the sake of simplicity, it is assumed that the cylindrical roller bearing is infinitely long, and there is no outside force acting on the bearing. The effects of radial clearance of the bearing, viscosity of the lubricant and number of the roller on the noise of the bearing are also examined. Results show that the fundamental frequency of the bearing noise corresponds to the multiplication of number of the roller and whirling frequency of the roller center or the retainer. The acoustical frequency spectra of the roller bearing are pure tone spectra, containing the fundamental frequency of the bearing and its super­harmonics. The low viscosity of the lubricant, high radial clearance of the bearing, and low number of the roller decrease the bearing noise. The results and discussions of the present paper could aid in the low­noise design of the cylindrical roller bearing.

A Study on the Slippage between a Moving Web and a Roller (이송중인 웹과 롤러의 슬립에 관한 연구)

  • Kwon, Soon-Oh;Shin, Kee-Hyun
    • Proceedings of the KSME Conference
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    • pp.1542-1547
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    • 2003
  • Air entrainment can become a significant problem in a web handling process. The development of air film between a web and an idle roller can cause a reduction of traction and traction coefficient, by which a slip is occurrred. Computational and experimental study was carried out to describe the slippage of an idle roller for given operating conditions, tension and web velocity. An extended mathematical model to find out a slip condition was developed by using the models of air film height, dynamic traction coefficient, and torque balance of a rotational roller. And by using the extended model, a mechanism to define the slippage between the roller and the moving web was suggested. The results of simulation and experiment showed that the extended dynamic model could properly characterize the rotational motion of the idle roller by considering dynamic traction coefficient. By examining the rotational motion of the idle roller with web dynamics(speed), the mechanism to define al slip condition between the roller and the web was found to be effective.

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A Study on the Wheelset Behavior on the Roller Rig for Railway Bogie Testing (대차 주행시험대상에서의 윤축 거동에 대한 연구)

  • Hur, Hyun-Moo;Park, Joon-Hyuk;You, Won-Hee;Park, Tae-Won
    • Proceedings of the KSME Conference
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    • pp.1207-1212
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    • 2007
  • The critical speed of railway bogie related to the stability of the railway rolling-stock is important. Testing of the dynamic performance of bogie is conducted using a roller rig in a laboratory in place of field testing on track. This roller rig is composed of two rollers equivalent to track and used to test the dynamic characteristics of vehicle. But, the geometrical characteristics of the wheel/roller contact on the roller rig are different from those of the wheel/rail contact because the longitudinal radius of roller is not infinite compared with rail. This difference has influence on the wheelset behavior and the critical speed of bogie. Therefore in this paper, we have studied the behavior of wheelset and bogie on the roller rig for railway bogie testing with the purpose of developing the scaled roller rig. As an analysis results, it has been shown that the critical speed of bogie on the roller rig is slightly lower than that of bogie on track.

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High-Contrast Imaging of Biomolecular Interactions Using Liquid Crystals Supported on Roller Printed Protein Surfaces

  • Park, Min-Kyung;Jang, Chang-Hyun
    • Bulletin of the Korean Chemical Society
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    • v.33 no.10
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    • pp.3269-3273
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    • 2012
  • In this study, we report a new method for the high contrast imaging of biomolecular interactions at roller printed protein surfaces using thermotropic liquid crystals (LCs). Avidin was roller printed and covalently immobilized onto the obliquely deposited gold surface that was decorated with carboxylic acid-terminated self-assembled monolayers (SAMs). The optical response of LCs on the roller printed film of avidin contrasted sharply with that on the obliquely deposited gold surface. The binding of biotin-peroxidase to the roller printed avidin was then investigated on the obliquely deposited gold substrate. LCs exhibited a non-uniform and random orientation on the roller printed area decorated with the complex of avidin and biotin-peroxidase, while LCs displayed a uniform and planar orientation on the area without roller printed proteins. The orientational transition of LCs from uniform to non-uniform state was triggered by the erasion of nanometer-scale topographies on the roller printed surface after the binding of biotin-peroxidase to the surface-immobilized avidin. The specific binding events of protein-receptor interactions were also confirmed by atomic force microscopy and ellipsometry. These results demonstrate that the roller printing of proteins on obliquely deposited gold substrates could provide a high contrast signal for imaging biomolecular interactions using LC-based sensors.

Roller Design of IRB Seismic Isolation Device Using Testing Evaluation : Part I. Geometry Dimension and Crowning (시험평가법을 이용한 IRB 면진장치 롤러 설계 : Part 1. 기하학적 형상 및 크라우닝)

  • Park, Young-Gee;Ha, Sung Hoon;Seong, Min-Sang;Jeon, Junchul;Choi, Seung-Bok
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.2
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    • pp.185-191
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    • 2013
  • This paper presents a new method for roller design of IRB(isolation roller bearing) seismic isolation device using experimental evaluation. Three layered plate is adopted for the IRB in which the upper plate is placed on x direction and the lower plate is placed on y direction. The rollers placed in each plate make a plate movement. The roller is then optimally designed using variable geometric conditions. Stress distribution depends on the diameter and length of the roller and hence this is used for the determination of optimal geometry of the roller. In the experimental evaluation, it is observed that stress concentration at the end sides of roller is decreased and geometric coefficients depend on crowning dimension. In addition, in order to determine optimal design parameters of the roller the plastic deformation and friction are experimentally identified.

Stress and Life Evaluation of Universal Joint of Cardan Shaft for Waterjet System of Special-Purpose Vehicle (특수 목적 차량의 수상 추진체용 카단 샤프트의 유니버셜 조인트에 대한 응력 및 수명 평가)

  • Bae, Myungho;Lee, Taeyoung;Cho, Yonsang
    • Tribology and Lubricants
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    • v.36 no.1
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    • pp.34-38
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    • 2020
  • The powertrain of the waterjet system of a special-purpose vehicle makes use of the cardan shaft, which is composed of universal joints and shafts. These universal joints, composed of spiders and needle roller bearings, have to be designed with consideration for the bending and compressive stresses of the spiders and needle roller bearings, and the rating lives of the bearings. The bending and compressive stresses of the spider and bearing of a universal joint have been studied by many researchers. However, to design a universal joint effectively, overall consideration of the different specifications of needle roller bearings is necessary. In this study, the bending stresses of spiders and compressive stresses of needle roller bearings are calculated to design universal joints for powertrain cardan shafts with different roller diameters of bearing. Furthermore, the rating lives of the needle roller bearings are predicted using the calculated basic dynamic load ratings of the bearings. As a result, roller diameters less than ��2.5 mm are found suitable through an analysis of the bending stress of the spider. All compressive stresses between spider and bearing, regardless of roller diameter, satisfy the requirements. Moreover, roller diameters of more than ��2 mm are found suitable for the required rating life.