• Title/Summary/Keyword: Roll Stiffness

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Vibration Behavior of a Rotating Brush Roll in Contact with a Solid Roll (강체롤과 접촉 회전하는 브러시롤의 진동 현상)

  • 허주호
    • Journal of KSNVE
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    • v.7 no.3
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    • pp.499-509
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    • 1997
  • During the process of oxide removal from work rolls in sheet metal manufacture, filamentary brushes frequently exhibit a bouncing or chatter behavior. The dynamics of this phenomenon is investigated through the development of expressions for the non-linear contact stiffness between the brush and the roll. With formulation of simple structural models, the time responses in the presence and absence of friction under random excitation are investigated. Possible solutions for the minimization or avoidance of this bouncing or chatter problem are also suggested.

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A Study on the Application of the Steering Control to Increase Roll Stiffness for the Relatively Tall Vehicles (무게중심이 높은 차량의 롤 강성계수 증대를 위한 스티어링 제어기법의 응용에 관한 연구)

  • 소상균;변기식
    • Journal of the Institute of Convergence Signal Processing
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    • v.4 no.2
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    • pp.53-60
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    • 2003
  • For the high center of gravity vehicles the roll stiffness of their suspensions is arranged to be very high because such vehicles are in some danger of tipping over in cornering. In some cases, the effective roll stiffness is determined significantly by the compliance of the tires because of the very stiff anti-roll members incorporated in the suspension. In such cases, it is clear that the shock absorbers which may be effective in damping heave oscillations have little effect on roll oscillations. Therefore, wind gusts and roadway unevenness may cause large swaying oscillations. In this paper, to improve the stability for the high center of gravity vehicles a control scheme to augment the damping of the roll mode is proposed. As the feedback signals needed to provide damping of the roll motion, the front or rear steer angles or both are chosen because they are very related to roll motion. The scheme is effective from moderate to high speeds and stabilizes the roll mode without introducing disturbance moments from roadway unevenness as shock absorbers do. The validity on the proposed method is verified through the computer simulation.

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Development of New Back-Up Roll for Strip Shape Control (형상제어를 위한 새로운 보강롤의 개발)

  • Lee, Won-Ho
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.2
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    • pp.327-333
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    • 2003
  • Most of shape defects in steel strip are originated from the structure of rolling mill itself. For instance, strip crown occurs when the work roll is deformed by the bending moment induced on roll chocks. To get rids of the shape defects, it is necessary to increase the stiffness of rolling mill. The structure change of back-up roll is one of alternative ways to increase the mill stiffness without facility revamping from 4 high mill to 6 high mill. In this research work, the new back-up roll was developed and can be used in any type of 4 high mill to reduce the strip shape defects. The developed back-up roll consists of sleeve, arbor and phase angle adjusting system for arbor. The circumference of arbor is specially machined to adapt the strip width change during rolling. The experimental cold rolling test was done to prove the effectiveness of newly developed back-up roll. The experimental rolling results show that the new back-up roll has more powerful performance in reducing the shape defects than conventional back-up roll. It was also found that the new back-up roll has higher stability for shape control. In addition to, the only sleeve surface needs to be reground and changed in most cases, so that the maintenance cost can be greatly reduced.

Effects of an actuator attached to roll stabilizer bar on vehicle performance (롤안정바에 부착된 엑츄체이터가 차량의 성능에 미치는 영향 분석)

  • Sung, In-Chol;Kim, Keun-Soo;Yoo, Wan-Suk
    • Proceedings of the KSME Conference
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    • 2000.04a
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    • pp.649-654
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    • 2000
  • To analyze the effects of the front and rear roll stabilizer bar, five different models of roll stabilizer bar are simulated in this paper. It is shown that the stiffness change of the roll stabilizer bar is an effective way to alter the vehicle's roll gradient. Attaching an actuator at the roll stabilizer bar the vehicle's roll gradient can be controlled within error limits.

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Optimization of ride comfort for a three-axle vehicle equipped with interconnected hydro-pneumatic suspension system

  • Saglam, Ferhat;Unlusoy, Y. Samim
    • Advances in Automotive Engineering
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    • v.1 no.1
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    • pp.1-20
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    • 2018
  • The aim of this study is the optimization of the parameters of interconnected Hydro-Pneumatic (HP) suspension system of a three-axle vehicle for ride comfort and handling. For HP suspension systems of equivalent vertical stiffness and damping characteristics, interconnected HP suspension systems increase roll and pitch stiffness and damping characteristics of the vehicle as compared to unconnected HP suspension systems. Thus, they result in improved handling and braking/acceleration performances of the vehicle. However, increased roll and pitch stiffness and damping characteristics also increase roll and pitch accelerations, which in turn result in degraded ride comfort performance. Therefore, in order to improve both ride comfort and vehicle handling performances simultaneously, an optimum parameter set of an interconnected HP suspension system is obtained through an optimization procedure. The objective function is formed as the sum of the weighted vertical accelerations according to ISO 2631. The roll angle, one of the important measures of vehicle handling and driving safety, is imposed as a constraint in the optimization study. Upper and lower parameter bounds are used in the optimization in order to get a physically realizable parameter set. Optimization procedure is implemented for a three-axle vehicle with unconnected and interconnected suspension systems separately. Optimization results show that interconnected HP suspension system results in improvements in both ride comfort and vehicle handling performance, as compared to the unconnected suspension system. As a result, interconnected HP suspension systems present a solution to the conflict between ride comfort and vehicle handling which is present in unconnected suspension systems.

Factors Influencing on movement of crashed Vehicle by using EDSMAC (EDSMAC을 이용한 충돌 후 차량운동에 영향을 미치는 인자)

  • Jung, H.K.;Kang, D.M.
    • Journal of Power System Engineering
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    • v.6 no.3
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    • pp.42-48
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    • 2002
  • Velocity change of crashed vehicle has been applied to assess the safety of passenger and degree of impact severity widely. In this study, 1 D crash analysis and 2 D crash analysis were performed for velocity change of crashed vehicle with HVE 2D, and factors used for these analysis are weight, C.G, roll resistance, stiffness and brake force which influence on velocity change of crashed vehicle. According to results, the velocity change of crashed vehicle was influenced by weight, center of gravity stiffness and brake force but not roll resistance.

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A Study on Roll Characteristics of Railway Vehicle (철도차량 롤 특성에 대한 고찰)

  • 김필환
    • Proceedings of the KSR Conference
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    • 1998.11a
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    • pp.512-521
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    • 1998
  • The roll characteristic of railway vehicle is an important factor that affects the roll-over of vehicle and lateral ride comfort of passenger. Generally the roll characteristics of railway vehicle is defined by the term of roll-coefficient, s, which represents the ratio of incline or carbody to that of rail-cant. The limit values of roll coefficient recommended in UIC Bre 0.4 for coach without pantograph and 0.15 for vehicle with pantograph. The roll coefficient can be calculated by VAMPIRE that is the well-known commercial software for analysis of dynamic behavior of railway vehicle. The value of roll coefficient is effected by height of gravity center of carbody, stiffness of primary and secondary suspension and etc. The calculated roll-coefficient for electric locomotive and passenger coach is 0.12 and 0.77 respectively, The additional equipment such as anti-roll bar is considered in order to decrease roll-coefficient of passenger coach. In relation to roll characteristics, the analysis for roll-over due to wind is a1so performed. The results show that roll-characteristics affect the roll-over of vehicle.

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A Study on Roll Forming Technology for Inner Structure Plate with Micro Dimple (미세 딤플 내부구조재 제작을 위한 롤 성형기술 연구)

  • Je T.J.;Kim H.J.;Kim B.H.;Huh B.W.;Seong D.Y.;Yang D.Y.;Choi D.S.
    • Transactions of Materials Processing
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    • v.15 no.4 s.85
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    • pp.326-332
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    • 2006
  • Sandwich structures, which are composed of a thick core between two faces, are commonly used in many engineering applications because they combine high stiffness and strength with low weight. Depending on the sheets by a rolling process, which is a more efficient and economical approach compared to other types of processes, has become an increasingly important subject of study. In this paper, we made a roll forming machine which progressive forming possible and force measurement for a roll forming of the sheet metal forming. And we designed a roll molding that arrayed of embossing size 3mm in diameter fabricate micro dimple inner structure plate. We carried out forming experiment such as array change and thickness to sts304 sheet. Ultimately, this research developed inner structure plate of high stiffness.

Engine Mounting System Optimization for Improve NVH (NVH 향상을 위한 엔진 설치 시스템 최적화)

  • Kim, Jang-Su
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.10
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    • pp.4665-4671
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    • 2013
  • Engine mounting system is the most responsible system for NVH performance of vehicle. The vibration at idle shake, road shake, Key ON/OFF, gear shift tuned by the engine mount position and stiffness. Previously described Engine mounting system theory investigated and summarized in this paper. Decoupling of the Power train rigid mode and Reducing the angle between Torque-Roll-Axis and Elastic-roll-Axis is starting point of optimization. Multi-optimization analysis was performed because of variety simulation case and FE-model. Eventually, Find the best mount location and the stiffness has improved the performance of the vehicle NVH.

The roll gap control hydraulic hot strip mill using time delay control method (TDC기법을 이용한 유압식 열연압연기의 롤갭제어)

  • 홍성철;현장환;이정오
    • 제어로봇시스템학회:학술대회논문집
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    • 1996.10b
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    • pp.1469-1472
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    • 1996
  • Hydraulic Hot Strip Mill (HHSM) rolls materials whose size and stiffness are various. So a roll gap controller for HHSM was designed using TDC(Time Delay Control) method. The performance of the roll gap control was evaluated through computer simulations. The simulation results indicate that TDC method show excellent robustness and tracking properties against PID control method in various rolling conditions.

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